Do-it-yourself biogas plant. Do-it-yourself biogas plant: Internet myths and rural reality Biogas plant farmer

Owners of private houses located in regions with limited access to traditional fuels should definitely turn their attention to modern biogas plants. Such units make it possible to obtain biogas from a variety of organic waste and use it for personal needs, including heating residential premises.

Gas can be obtained from almost any biomass - waste from the livestock industry, food production, agriculture, foliage, etc. At the same time, you can build such an installation with your own hands.

Mechanism of action of biogas plants

Both homogeneous raw materials and mixtures of various biomass are suitable for producing biogas. A biogas plant is a volumetric sealed structure equipped with devices for supplying raw materials, heating biomass, mixing components, discharging the resulting biogas into a gas collector and, of course, protecting the structure.

In the reactor, under the influence of anaerobic bacteria, rapid decomposition of biomass occurs. During the fermentation of organic raw materials, biogas is released. Approximately 70% of the composition of such gas is represented by methane, the remaining part is carbon dioxide.

Biogas is characterized by excellent calorific value; it has no pronounced odor or color. In terms of its properties, biogas is practically in no way inferior to more traditional natural gas.

In developed countries, additional installations are used to purify biogas from carbon dioxide. If you wish, you can buy the same installation and obtain pure biomethane.

Biogas plants on silos. 1 Silo pits. 2 Biomass loading system. 3 Reactor. 4 Post-fermentation reactor. 5 Substrater. 6 Heating system. 7 Power plant. 8 Automation and control system. 9 Gas pipeline system

On average, one cow or other animal weighing half a ton is capable of producing enough manure per day to produce approximately 1.5 m3 of biogas. Daily manure from one average pig can be processed into 0.2 m3 of biogas, and a rabbit or chicken into 0.01-0.02 m3 of fuel.

For comparison: 1 m3 of biogas from manure provides approximately the same amount of thermal energy as 3.5 kg of firewood, 1-2 kg of coal, 9-10 kW/h of electricity.

The simplest mixture recipe for producing biogas includes the following components:

• cow manure - about 1500 kg;
• rotted leaves or other organic waste – 3500 kg;
• water – 65-75% of the total mass of the previous components. The water must first be heated to about 35 degrees.

This amount of biomass will be enough to produce biogas for six months of operation with moderate consumption. On average, biogas begins to be released within 1.5-2 weeks after the mixture is loaded into the installation.

Gas can be used to heat a home and a variety of commercial and domestic buildings.

Design of a typical biogas plant

Biogas plant

The main components of a complete biogas system are:

• reactor;
• humus supply system;
• stirrers;
• biomass;
• gas holder;
• separator;
• protective part.

A household installation will have a somewhat simplified design, however, for a complete understanding, you are invited to read the description of all the listed elements.

Biogas plants

Reactor

This part of the installation is usually assembled from stainless steel or concrete. Externally, the reactor looks like a large sealed container, on top of which is a dome, usually spherical in shape.

Currently, the most popular are reactors with a collapsible design, made using innovative technologies. Such a reactor can be easily assembled with your own hands with minimal time investment. If necessary, it can be easily disassembled and transported to another location.

Steel is convenient because you can easily create holes in it to connect other elements of the system. Concrete is superior to steel in terms of strength and durability.

Biomass feeding system

This part of the installation includes a hopper for receiving waste, a supply pipeline for water supply and a screw pump designed to send humus to the reactor.

A front loader is used to load the dry component into the hopper. At home, you can cope with this task without a loader, using various improvised means, for example, shovels.

In the hopper the mixture is moistened to a semi-liquid state. After reaching the desired level of moisture, the screw transfers the semi-liquid mass to the lower compartment of the reactor.

Stirrers

Fermentation of humus in the reactor should occur evenly. This is one of the most important conditions for ensuring intensive release of biogas from the mixture. It is to achieve the most uniform fermentation process of the mixture that the design of a typical biogas plant includes mixers with electric drives.

There are submersible and inclined type mixers. Submersible mechanisms can be lowered into the biomass to the required depth to ensure intensive and uniform mixing of the substrate. Usually such mixers are placed on a mast.

Installation of inclined mixers is carried out on the side surfaces of the reactor. An electric motor is responsible for rotating the screw in the fermenter.

Automated heating system

To successfully produce biogas, the temperature inside the system must be maintained at +35-+40 degrees. For this purpose, automated heating systems are included in the design.

The heat source in this case is a hot water boiler, in individual situations Electric heating units are used.

Gas holder

Gas holder

Biogas is collected in this structural element. Most often, the gas holder is placed on the roof of the reactor.

The production of modern gas tanks is usually carried out using polyvinyl chloride, a material that is resistant to sunlight and various adverse natural phenomena.

Gas holder

In some situations, instead of a regular gas tank, special bags are used. Also, these devices allow you to temporarily increase the volume of the produced biogas.

For the manufacture of gas holder bags, a special polyvinyl chloride with elastic properties is used, which can inflate as the volume of biogas increases.

Separator

Separator

This part of the system is responsible for drying waste humus and producing, if necessary, high-quality fertilizers.

The simplest separator consists of a screw and a separator chamber. The chamber is made in the form of a sieve. This allows the biomass to be separated into a solid component and a liquid part.

Press-screw separator

The dried humus is sent to the shipping compartment. The system directs the liquid part back to the receiving chamber. Here the liquid is used to moisten the new feedstock.

The simplest DIY biogas plant

Biogas plant for home

A household biogas installation will have a somewhat simplified design, but its manufacture should be approached with maximum responsibility.

First step. Dig a hole. At its core, a biogas plant is a large pit with a special finish. The most important and at the same time difficult part of manufacturing the system in question is the correct preparation of the walls of the bioreactor and its base.

The pit must be sealed. Strengthen the base and walls with plastic or concrete. Instead, you can purchase ready-made polymer rings with a solid bottom. Such devices make it possible to ensure the necessary tightness of the system. The material will retain its original characteristics for many years, and if necessary, you can easily replace the old ring with a new one.

Second step. Install a gas drainage system. This will save you from the need to purchase and install agitators, due to which the time and money spent on assembling the installation will be significantly reduced.

The simplest version of a gas drainage system is vertically mounted sewer pipes made of polyvinyl chloride with many holes throughout the body.

Select pipes of such length that their upper edges rise slightly above the upper level of the loaded humus.

Third step. Cover the outer layer of the substrate with film insulation. Thanks to the film, conditions will be created for the accumulation of biogas under the dome under conditions of slight excess pressure.

Fourth step. Install the dome and mount the gas exhaust pipe at its highest point.

Gas consumption should be regular. Otherwise, the dome over the biomass container may simply explode. In summer, gas is formed more intensively than in winter. To solve the latter problem, purchase and install suitable heaters.

Procedure and conditions for successful use of a biogas plant

Average specific biogas yield

Thus, it is not difficult to assemble a simple biogas plant yourself. However, for its successful operation, you must remember and follow a few simple rules.

One of the most important requirements is that the loaded organic mass should not contain any substances that can have a negative impact on the vital activity of anaerobic microorganisms. Prohibited inclusions include various types of solvents, antibacterial drugs and other similar substances.

A number of inorganic substances can also lead to a deterioration in the functioning of bacteria. In view of this, it is prohibited, for example, to dilute humus with water remaining after washing clothes or washing a car.

Remember: a biogas installation is a potentially explosive unit, so follow all safety regulations relevant for the operation of any gas equipment.

Thus, even manure and, in principle, almost everything that you previously tried your best to get rid of, can be useful on the farm. You just need to properly build a home biogas installation, and very soon your home will be warm. Follow the recommendations received, and you will no longer have to spend enormous sums on heating.

Good luck!

Read also the article on our website - do-it-yourself hydroponic installation.

Video - Do-it-yourself biogas plant

svoimi-rykami.ru

Do-it-yourself biogas plant

The article on biogas production provided the theoretical basis for the production of methane gas from biomass by anaerobic digestion.

The role of bacteria in the step-by-step transformation of organic substances was explained, with a description of the necessary conditions for the most intensive production of biogas. This article will present practical implementations of biogas plants, with a description of some home-made designs.

Since energy prices are rising, and many owners of livestock farms and small farms have problems with waste disposal, industrial complexes for the production of biogas and small biogas plants for private homes have become available for sale. Using search engines, an Internet user can easily find an affordable ready-made solution so that the biogas plant and its price meet the needs, get in touch with equipment suppliers and agree on the construction of a biogas generator at home or on the farm.

Industrial complex for biogas production

Bioreactor - the basis of a biogas plant

The container in which anaerobic decomposition of biomass occurs is called a bioreactor, fermenter, or methane tank. Bioreactors can be completely sealed, with a fixed or floating dome, and have a diving bell design. Bell psychrophilic (not requiring heating) bioreactors have the form of an open reservoir with liquid biomass, into which a container in the form of a cylinder or bell is immersed, where biogas is collected.

The collected biogas puts pressure on the cylinder, causing it to rise above the tank. Thus, the bell also serves as a gas holder - a temporary storage facility for the generated gas.

Floating dome bioreactor

The disadvantage of the bell design of the biogas reactor is the impossibility of mixing the substrate and heating it during cold periods of the year. Also a negative factor is a strong odor, and unsanitary conditions due to the open surface of part of the substrate.

In addition, part of the resulting gas will escape into the atmosphere, polluting the environment. Therefore, these bioreactors are used only in artisanal biogas plants in poor countries with hot climates.

Another example of a floating dome bioreactor

To prevent environmental pollution and eliminate unpleasant odors, reactors in biogas plants for homes and large industries are designed with a fixed dome. Shape of the structure during gas formation of great importance does not, but when using a cylinder with a dome-shaped roof, significant savings in building materials are achieved. Bioreactors with a fixed dome are equipped with pipes for adding new portions of biomass and selecting spent substrate.

A type of fixed dome bioreactor

Main types of biogas plants

Since the most acceptable design is a fixed dome, most ready-made bioreactor solutions are of this type. Depending on the loading method, bioreactors have different designs and are divided into:

• Portion-based, with a one-time loading of all biomass, and subsequent complete unloading after processing of the raw materials. The main disadvantage of this type of bioreactor is the uneven release of gas during substrate processing;
• continuous loading and unloading of raw materials, thereby achieving uniform release of biogas. Thanks to the design of the bioreactor, during loading and unloading, the production of biogas does not stop and no leaks occur, since the pipes through which biomass is added and removed are made in the form of a water seal that prevents gas leakage.

Example of a batch bioreactor

Batch biogas reactors can have any design that prevents gas leakage. For example, at one time in Australia, channel methane tanks with an elastic inflatable roof were popular, where a slight excess pressure inside the bioreactor inflated a bubble made of durable polypropylene. When a certain pressure level inside the bioreactor was reached, a compressor was turned on, pumping out the produced biogas.

Channel bioreactors with elastic gas holder

The type of fermentation in this biogas plant can be mesophilic (with low heating). Due to the large area of ​​the inflating dome, channel bioreactors can only be installed in heated rooms or in regions with a hot climate. The advantage of the design is that there is no need for an intermediate receiver, but the big disadvantage is the vulnerability of the elastic dome to mechanical damage.

Large channel bioreactor with elastic gas tank

Recently, batch bioreactors with dry fermentation of manure without adding water to the substrate have been gaining popularity. Since manure has its own moisture, it will be sufficient for the life of organisms, although the intensity of reactions will decrease.

Dry-type bioreactors look like a sealed garage with tightly closing doors. Biomass is loaded into the reactor using a front-end loader and remains in this state until the full gas formation cycle is completed (about six months), without the need to add a substrate or mix it.

Batch bioreactor with loading through a hermetically sealed door

DIY biogas plant

It should be noted that in most bioreactors, as a rule, only the gas formation zone is sealed, and the liquid biomass at the inlet and outlet is under atmospheric pressure. Excessive pressure inside the bioreactor displaces part of the liquid substrate into the nozzles, which is why the level of biomass in them is slightly higher than inside the container.

The red lines in the diagram indicate the difference in levels in the bioreactor and pipes

These designs of homemade bioreactors are popular among folk craftsmen who independently make biogas plants with their own hands for the home, allowing for repeated manual loading and unloading of the substrate. When making bioreactors with their own hands, many craftsmen experiment with completely sealed containers, using several rubber tubes from the tires of large vehicles as a gas holder.

Drawing of a gas holder made from tractor inner tubes

In the video below, an enthusiast of homemade biogas production, using barrels filled with bird droppings as an example, proves the possibility of actually producing combustible gas at home by processing poultry house waste into useful fertilizer. The only thing that can be added to the design described in this video is that you need to install a pressure gauge and a safety valve on a homemade bioreactor.

Bioreactor productivity calculations

The amount of biogas is determined by the mass and quality of the raw materials used. On the Internet you can find tables that indicate the amount of waste produced by various animals, but for owners who have to remove manure every day, this theory is of no use, since thanks to their own practice they know the amount and mass of the future substrate. Based on the availability of raw materials renewable every day, it is possible to calculate the required volume of the bioreactor and the daily production of biogas.

Table for obtaining the amount of manure from some animals with an approximate calculation of biogas yield

After the calculations have been made and the design of the bioreactor has been approved, its construction can begin. The material can be a reinforced concrete container poured into the ground, or brickwork sealed with a special coating that is used to treat swimming pools.

It is also possible to build the main tank of a home biogas plant from iron coated with anti-corrosion material. Small industrial bioreactors are often made from large-volume, chemical-resistant plastic tanks.

Construction of a bioreactor from brickwork

Industrial biogas plants use electronic control systems and various reagents for correction. chemical composition substrate and its acidity level, and special substances are added to the biomass - enzymes and vitamins that stimulate the reproduction and activity of microorganisms inside the bioreactor. In the process of development of microbiology, more and more stable and effective strains of methanogen bacteria are being created, which can be purchased from companies involved in the production of biogas.

The graph shows that with the use of enzymes, the maximum biogas yield occurs twice as fast

The need for pumping out and purifying biogas

Constant gas production in a bioreactor of any design leads to the need to pump out biogas. Some primitive biogas plants can burn the resulting gas directly in a burner installed nearby, but instability of the excess pressure in the bioreactor can lead to the disappearance of the flame with the subsequent release of poisonous gas. The use of such a primitive biogas installation connected to a stove is categorically unacceptable due to the possibility of poisoning by the toxic components of unpurified biogas.

The burner flame when burning biogas must be clean, even and stable.

Therefore, almost any biogas installation scheme includes gas storage tanks and a gas purification system. As a homemade cleaning complex, you can use a water filter and a homemade container filled with metal shavings, or purchase professional filtration systems. A container for temporary storage of biogas can be made from inner tubes from tires, from which the gas is pumped out from time to time by a compressor into standard propane cylinders for storage and subsequent use.

In some African countries, inflatable gas holders in the form of a pillow are used for storing and transporting biogas

An improved bioreactor with a floating dome can be considered as an alternative to the mandatory use of a gas tank. The improvement consists of adding a concentric partition, which forms a water pocket, acting like a water seal and preventing the biomass from coming into contact with air. The pressure inside the floating dome will depend on its weight. By passing the gas through a cleaning system and a reducer, it can be used in a household stove, periodically venting it from the bioreactor.

Bioreactor with floating dome and water pocket

Grinding and mixing the substrate in a bioreactor

Stirring the biomass is an important part of the biogas production process, providing bacteria with access to nutrients that may be clumped at the bottom of the digester. In order for biomass particles to be better mixed in the bioreactor, they must be crushed mechanically or manually before loading into the methane tank. Currently, in industrial and home-made biogas plants, three methods of mixing the substrate are used:

1. mechanical stirrers, driven by an electric motor or manually;
2. circulation mixing using a pump or propeller pumping the substrate inside the bioreactor;
3. bubbling mixing using purging of liquid biomass with existing biogas. The disadvantage of this method is the formation of foam on the surface of the substrate.

The arrow indicates the mixing circulation screw in a homemade bioreactor

Mechanical mixing of the substrate inside the bioreactor can be done manually or automatically by turning on the electric motor using an electronic timer. Water jet or bubbling mixing of biomass can only be carried out using electric motors controlled manually or using a software algorithm.

This bioreactor is equipped with a mechanical mixing device.

Substrate heating in mesophilic and thermophilic biogas plants

The optimum temperature for gas formation is the substrate temperature within 35-50ºC. To maintain this temperature, the bioreactor can be equipped with various systems heating - water, steam, electric. Temperature control should be carried out using a thermostat or thermocouples connected to an actuator that regulates the heating of the bioreactor.

You also need to remember that an open flame will overheat the walls of the bioreactor, and the biomass inside will burn. A burnt substrate will reduce heat transfer and heating quality, and the hot wall of the bioreactor will quickly collapse. One of the best options is water heating from the return pipe of the home heating system. It is necessary to install a system of electric valves to be able to turn off the heating of the bioreactor or connect the heating of the substrate directly from the boiler if it is too cold.

Electric and water heating system for the bioreactor

Heating the substrate in a bioreactor using heating elements will be beneficial only if alternative electricity is available, obtained from a wind generator or solar panels. In this case, heating elements can be connected directly to a generator or battery, which eliminates expensive voltage converters from the circuit. To reduce heat loss and reduce the cost of heating the substrate in a bioreactor, it is necessary to insulate it as much as possible using various insulation materials.

Insulation of the bioreactor with thermal insulation material

Practical experiments inevitable when building biogas plants with your own hands

No matter how much literature a novice enthusiast of self-production of biogas reads, and no matter how many videos he watches, in practice he will have to learn a lot on his own, and the results, as a rule, will be far from the calculated ones.

Therefore, many beginning craftsmen follow the path of independent experiments in producing biogas, starting with small containers, determining how much gas their small experimental biogas plant produces from the available raw materials. Prices for components, methane output and future costs of building a full-fledged working biogas plant will determine its profitability and feasibility.

In the video above, the master demonstrates the capabilities of his biogas installation, measuring how much biogas is produced in one day. In his case, when eight atmospheres are pumped into the compressor receiver, the volume of the resulting gas after recalculation taking into account the volume of the 24 liter container will be about 0.2 m².

This volume of biogas obtained from a two-hundred-liter barrel is not significant, but, as shown in the following video of this master, this amount of gas is enough to burn one stove burner for an hour (15 minutes multiplied by four atmospheres of a cylinder, which is twice the size of the receiver).

In another video below, the master talks about producing biogas and biologically pure fertilizers by processing organic waste in a biogas plant. It must be borne in mind that the value of environmental fertilizers may exceed the cost of the resulting gas, and then biogas will become a useful by-product of the process of producing quality fertilizers. One more useful property organic raw materials is the possibility of storing them for a certain period for use at the right time.

infoelectrik.ru

Do-it-yourself biogas: technology for producing alternative fuel from biological waste

Concerned about the impending energy crisis, humanity is actively trying to develop renewable energy sources.

Along with solar and wind power plants, installations have emerged for producing gaseous fuel called biogas from organic waste.

The great thing about this technology is its simplicity: anyone can implement it on a small scale. So, do-it-yourself biogas – that’s what we’ll be talking about.

If we owe the appearance of solar panels and wind generators to the discoveries of scientists, then in the case of biogas they did not have to invent anything - nature did everything itself. This type of fuel is a product of the vital activity of special bacteria, which are collectively called hydrolytic, acid-forming and methane-forming.

From the name it is not difficult to guess the main component of biogas - it is methane, which is also found in natural gas. In biogas, it accounts for 60% of the total volume. About a third (35%) is carbon dioxide, the remaining 5% is other gases, for example, hydrogen sulfide.

Schematic diagram of a biogas plant

Where do these wonderful microorganisms come from? They are natural microflora that live in the intestines of cattle and decompose their contents. These bacteria are excreted along with the manure, which is used to fuel the new gas generator.

When microbes are settled in a new place of residence, their “menu” can be diversified with other waste. Any organic matter will do: excrement of other animals and birds, plants and sawdust, food industry waste. All this is fermented to form biogas. In this case, the raw materials are transformed into valuable fertilizer.

A prerequisite for the vital activity of methanogens and other bacteria is the absence of air access (such microorganisms are called anaerobic).

Factors influencing biogas production

The volume of biogas produced by a friendly team of microbes under different conditions can vary and depends on a number of factors.

Type of raw material

Most biogas can be obtained from food industry waste containing sugar pulp and large amounts of fat. The least profitable type of raw material is cattle manure.

Manure - raw material for biogas

Temperature

As the temperature rises, the productivity of bacteria increases. According to temperature conditions, gas generators are divided into three types.

Psychrophilic

These are unheated installations in which the temperature is maintained between 18 and 25 degrees. At the moment they are almost never used.

Mesophilic

Thanks to heating, the temperature is maintained within the range from 25 to 40 degrees.

Advantages:

• low energy consumption;
• The amino acid composition of fertilizers is as beneficial as possible.

Flaws:

• relatively low biogas productivity;
• lack of disinfecting effect (the raw materials contain pathogenic bacteria that should be eliminated).

Thermophilic

Intensive heating is used, the temperature exceeds 40 degrees.

Advantages:

• high performance;
• pathogenic bacteria die.

Flaws:

• high energy consumption;
• low quality fertilizers.

Thermophilic manure bioreactor

For each type of raw material there is an optimal temperature regime. Why can't you just heat the reactor to the highest possible temperature? For two reasons:

• due to rising energy costs, the profitability of the installation will decrease;
• As the temperature increases, the amount of free ammonia also increases.

The latter dependence leads to inhibition of gas generation (this gas is toxic to bacteria).

Metabolism and freedom of movement

The raw material must be sufficiently liquefied so that microbes and gas bubbles can move in it. To do this, hot water is added to the installation, bringing the humidity of the load to 85% in winter and up to 92% in summer.

In order for metabolic processes to occur better in the reactor, its contents must be stirred from time to time (approximately every 4 to 6 hours).

Fermentation time

If raw materials are unloaded ahead of schedule, the bacteria will not have time to compensate for the loss in numbers and the productivity of their colonies will drop.

If held for too long, productivity also decreases due to lack of nutrients.

On average, the optimal fermentation time is:

• for the psychrophilic regimen: 30 – 40 days or more;
• for mesophilic: 10 – 20 days;
• for thermophilic: 5 – 10 days.

Acid-base balance

The highest productivity is observed at pH values ​​from 6.5 to 8.5 (depending on the raw material).

Carbon to Nitrogen Ratio

The optimal value again depends on the raw material. There should be 10–20 times more carbon than nitrogen.

Comparison of biogas with more traditional fuels

The strengths of this technology include the following:

1. The raw materials used to produce biogas are an inexhaustible resource and are free of charge.
2. Biogas energy is not tied to specific place– raw materials for installation can be found in any region.
3. Wide range of applications: biogas can act as a source of heat, electricity and motor fuel.

In terms of construction costs (3–4 thousand euros per kW of power), biogas plants are between nuclear (5 thousand euros per 1 kW) and coal (2 thousand euros per 1 kW) stations.

Installation for biogas production

In practice, it has been proven: the greater the power of the installation, the cheaper the energy generated with its help is. Profitability also depends on the type of raw materials used.

Scheme for organizing biogas production at home

When constructing a gas generator with a capacity of over 10 MW, operating on food waste, you will have to spend about 2 thousand euros for each kW of power; at the same time, an installation with a capacity of up to 1 MW, using cow manure as a raw material, will cost 7 thousand euros per 1 kW.

The unit consists of several technological units.

Reactor

It is a solid reinforced concrete container covered with thermal insulation with several technological holes. The reactor must be hermetically sealed to prevent air from entering its interior.

Biomass feeding system

To load raw materials, the installation is equipped with a bunker. Waste is fed here manually or using a conveyor.

A pipe with hot water is also supplied to the reactor.

Stirrers

The mixing blades are mounted on a vertical shaft, the shank of which extends out through a sealed hole in the reactor lid.

The device is driven by an electric motor through a gear reducer.

The electric motor can be turned on manually or automatically.

Automated heating system

Heating is installed in the lower part of the reactor. The coolant can be water or electricity. The heating elements are turned on by a thermostat set to a certain temperature.

Gas holder

This is the container into which the biogas generated in the reactor enters.

Separator

As mentioned above, biogas is a mixture of various gases. The separator allows you to separate methane from impurities for subsequent delivery to the consumer.

The simplest DIY biogas plant for home

A homemade biogas generator, of course, is inferior in characteristics to expensive factory-made units, but it will require significantly lower initial costs.

To build it you will need:

• reinforced concrete rings;
• steel bunker;
• a massive lid made of steel or reinforced concrete (there is a known case when a heavy bell was used as a lid);
• pipelines for supplying water and discharging the finished product.

The reactor volume should exceed the loading volume by 1.5 times.

Installation diagram

In its simplest design, the gas generator is not equipped with heating and a mixing device. Work on the construction of the installation is carried out in the following sequence:

1. A pit of sufficient size is dug, the bottom of which is concreted.
2. Several reinforced concrete rings are lowered into the pit one after another, forming a cylindrical tank from them. All joints should be sealed with bitumen mastic.
3. The concrete container is covered with thermal insulation and waterproofing, after which they begin to backfill the pit.
4. A lid with a tightly closing loading hatch is placed on top of the reactor. During the fermentation of raw materials, high pressure is generated in the reactor, so the lid can be secured with cables for reliability. It would not be superfluous to install a safety valve in it with a counterweight in the form of a weight.
5. A hopper must be attached to the loading hatch.
6. All that remains is to connect the pipelines to the reactor. In this case, a water seal must be installed on the finished product discharge line.

Biomass is prepared as follows:

• You should take 3 parts of cow manure and 7 parts of rotted plant residues - vegetable tops, leaves, peelings, etc.
• The resulting mixture must be diluted with water, thereby raising its humidity to 60% - 70%.

In order to increase productivity, you can use a more advanced installation scheme that includes water heating. The heat generator will be a hot water boiler running on the fuel produced by the installation.

DIY biogas plant - drawing

When loading the raw material, it is enough to warm it up to 35 degrees, after which its temperature as a result of fermentation will rise to 70 degrees.

As practice has shown, a 5-ton loading of biomass makes it possible to obtain an average of about 40 cubic meters daily within 6 months. m of gaseous fuel.

Video on the topic

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microclimat.pro

Do-it-yourself biogas plant for a private home: recommendations for the device and an example of arranging a homemade product

A thrifty owner dreams of cheap energy resources, efficient waste disposal and obtaining fertilizers. A DIY home biogas plant is an inexpensive way to make your dream come true. Self-assembly Such equipment will cost a reasonable amount of money, and the gas produced will be a good help in the household: it can be used for cooking, heating the house and other needs.

What is needed to produce biogas

Biogas is formed as a result of fermentation of a biological substrate. It is decomposed by hydrolytic, acid- and methane-forming bacteria. The mixture of gases produced by bacteria is flammable, because contains a large percentage of methane.

Its properties are practically no different from natural gas, which is used for industrial and domestic needs.

If desired, every home owner can purchase an industrial-made biogas plant, but it is expensive, and the investment pays off within 7-10 years. Therefore, it makes sense to make an effort and make a bioreactor with your own hands

Biogas is an environmentally friendly fuel, and the technology for its production does not have much impact on the environment. Moreover, waste products that need to be disposed of are used as raw materials for biogas. They are placed in a bioreactor, where processing occurs:

• The biomass is exposed to bacteria for some time. The fermentation period depends on the volume of raw materials.
• As a result of the activity of anaerobic bacteria, a flammable mixture of gases is released, which includes methane (60%), carbon dioxide (35%) and some other gases (5%). Fermentation also releases potentially dangerous hydrogen sulfide in small quantities. It is poisonous, so it is highly undesirable for people to be exposed to it.
• The mixture of gases from the bioreactor is purified and enters a gas tank, where it is stored until it is used for its intended purpose.
• Gas from a gas holder can be used in the same way as natural gas. He goes to household appliances– gas furnaces, heating boilers, etc.
• Decomposed biomass must be regularly removed from the fermenter. This is additional labor, but the effort pays off. After fermentation, the raw material turns into high-quality fertilizer, which is used in fields and vegetable gardens.

A biogas plant is beneficial for the owner of a private house only if he has constant access to waste from livestock farms. On average, from 1 cubic meter. You can get 70-80 cubic meters of substrate. biogas, but gas production is uneven and depends on many factors, including biomass temperatures. This complicates calculations.

Biogas plants are ideal for farms. Animal waste can provide enough gas to fully heat residential premises and outbuildings

In order for the gas production process to be stable and continuous, it is best to build several biogas plants, and add the substrate to the fermenters with a time difference. Such installations operate in parallel, and raw materials are loaded into them sequentially. This guarantees a constant production of gas, so that it can be continuously supplied to household appliances.

Ideally, the bioreactor should be heated. Every 10 degrees of heat increases gas production by half. Although heating installation requires investment, it pays off in greater design efficiency

Homemade biogas equipment, assembled from scrap materials, is much cheaper than industrial production plants. Its efficiency is lower, but it is well worth the investment. If you have access to manure and the desire to put in your own effort to assemble and maintain the structure, this is very profitable.

Advantages and disadvantages of the system

Biogas plants have many advantages, but there are also a lot of disadvantages, so before starting design and construction you should weigh everything:

• Waste disposal. Thanks to a biogas plant, you can get the maximum benefit from waste that would otherwise have to be disposed of. This disposal is less hazardous to the environment than landfilling.
• Renewability of raw materials. Biomass is not coal or natural gas, the extraction of which depletes resources. When farming, raw materials appear constantly.
• Relatively small amount of CO2. When gas is produced, the environment is not polluted, but when it is used, a small amount of carbon dioxide is released into the atmosphere. It is not dangerous and is not capable of critically changing the environment, because... it is absorbed by plants during growth.
• Moderate sulfur release. When biogas is burned, a small amount of sulfur is released into the atmosphere. This is a negative phenomenon, but its scale can be seen in comparison: when burning natural gas, environmental pollution with sulfur oxides is much greater.
• Stable job. Biogas production is more stable than solar panels or wind turbines. While solar and wind energy cannot be controlled, biogas plants depend on human activity.
• Multiple settings can be used. Gas always carries risks. To reduce potential damage in the event of an accident, several biogas plants can be dispersed throughout the site. If a system of several fermenters is properly designed and assembled, it will operate more stable than a single large bioreactor.
• Benefits for agriculture. Some types of plants are planted to obtain biomass. You can choose ones that improve the condition of the soil. For example, sorghum reduces soil erosion and improves its quality.

Biogas also has disadvantages. Although it is a relatively clean fuel, it still pollutes the atmosphere. There may also be problems with the supply of plant biomass. Irresponsible plant owners often harvest it in such a way that they deplete the land and upset the ecological balance.

How to calculate the profitability of an installation

Cow dung is usually used as a raw material for biogas production. One adult cow can produce enough to provide 1.5 cubic meters. fuel; pig – 0.2 cubic meters; chicken or rabbit (depending on body weight) – 0.01-0.02 cubic meters. To understand whether this is a lot or a little, you can compare it with more familiar types of resources.

1 cubic meter biogas provides the same amount of thermal energy as:

• firewood – 3.5 kg;
• coal – 1-2 kg;
• electricity – 9-10 kW/h.

If you know the approximate weight of agricultural waste that will be available over the coming years and the amount of energy required, you can calculate the profitability of a biogas plant.

One of the main disadvantages of biogas production is the smell. The ability to use small compost heaps is a big plus, but you will have to endure the inconvenience and carefully control the process so as not to provoke the spread of pathogens

To put it into the bioreactor, a substrate is prepared, which includes several components in the following proportions:

• manure (best cow or pork) – 1.5 t;
• organic waste (this can be rotten leaves or other components of plant origin) – 3.5 t;
• water heated to 35 degrees (the amount of warm water is calculated so that its mass is 65-75% of the total amount of organic matter).

The calculation of the substrate was made for one laying for six months, based on moderate gas consumption. After about 10-15 days, the fermentation process will give the first results: gas will appear in small quantities and begin to fill the storage. After 30 days, you can expect full fuel production.

Equipment for the production of biogas is not yet particularly widespread in our country. This is largely due to poor awareness of people about the advantages and features of biogas systems. In China and India, many small farms are equipped with makeshift plants to produce additional clean fuel

If the installation works correctly, the volume of biogas will gradually increase until the substrate rots. The performance of the structure directly depends on the rate of biomass fermentation, which in turn is related to the temperature and humidity of the substrate.

Instructions for self-construction

If you have no experience in assembling complex systems, it makes sense to select online or develop the simplest drawing of a biogas plant for a private home.

The simpler the design, the more reliable and durable it is. Later, when you have the skills to build and handle the system, you can redo the equipment or install an additional installation.

Expensive industrial designs include systems for biomass mixing, automatic heating, gas purification, etc. Household equipment is not that complicated. It's better to collect easy installation, and then add elements that are needed

When calculating the volume of the fermenter, you should focus on 5 cubic meters. This installation allows you to obtain the amount of gas necessary to heat a private house with an area of ​​50 square meters, if a gas boiler or stove is used as a heat source. This is an average figure, because The caloric content of biogas is usually not higher than 6000 kcal/m3.

In order for the fermentation process to proceed more or less stably, it is necessary to achieve the correct temperature conditions. To do this, the bioreactor is installed in an earthen pit or reliable thermal insulation is thought out in advance. Constant heating of the substrate can be ensured if a water heating pipe is installed under the base of the fermenter

The construction of a biogas plant can be divided into several stages.

Stage 1: preparing the pit for the bioreactor

Almost the entire biogas plant is underground, so a lot depends on how the pit was dug and finished. There are several options for strengthening the walls and sealing the pit - plastic, concrete, polymer rings.

The intensity of fermentation of the substrate and the release of gas depend on the preparation of the walls and bottom of the bioreactor, so the pit is carefully strengthened, insulated and sealed. This is the most difficult and time-consuming stage of work

The optimal solution is to purchase ready-made polymer rings with a solid bottom. They will cost more than available materials, but no additional sealing will be required. Polymers are sensitive to mechanical loads, but are not afraid of moisture and chemically aggressive substances. They cannot be repaired, but if necessary they can be easily replaced.

Stage 2: arrangement of gas drainage

Purchasing and installing special mixers for biogas plants is an expensive proposition. The system can be made cheaper by installing gas drainage. It consists of vertically installed polymer sewer pipes with many holes made in them.

For gas drainage, you can choose metal or polymer pipes. The former are stronger, and the latter are more resistant to chemical influences. It is better to give preference to polymers, because the metal will quickly rust and rot

When calculating the length of drainage pipes, you should focus on the planned filling depth of the bioreactor. The tops of the pipes must be above this level.

Stage 3: arrangement of the insulating layer

You can immediately load the substrate into the finished bioreactor. It is covered with a film so that the gas released during the fermentation process is under slight pressure. When the dome is ready, this will ensure a normal supply of biomethane through the outlet pipe.

Stage 4: installation of the dome and pipes

The final stage of assembling the simplest biogas plant is the installation of the dome top part. At the highest point of the dome, a gas exhaust pipe is installed and extended to the gas holder.

The free space of the bioreactor to some extent serves as a gas storage facility, but this is not enough for the safe operation of the installation. Gas must be consumed constantly, otherwise an explosion from excess pressure under the dome is possible

The bioreactor container is closed with a tight lid. To prevent biomethane from mixing with air, a water seal is installed. It also serves for gas purification. It is necessary to provide a release valve that will operate if the pressure in the fermenter is too high.

Two ways to heat a bioreactor

Microorganisms that process the substrate are constantly present in the biomass, but for their intensive reproduction they need a temperature of 38 degrees or higher. For heating during cold periods, you can use a coil connected to the home heating system or electric heaters. The first method is more economical, so it is used more often.

The easiest way to arrange heating from below is to lay a pipe from the heating system, but the efficiency of such a heat exchanger is relatively low. It is better to arrange external heating, ideally steam, so that the biomass does not overheat

The biogas plant does not have to be buried in the ground; there are other options for arrangement. An example of the operation of a system assembled from barrels is shown in the video below.

Videos on assembly and arrangement of the system

Although there is nothing complicated in assembling and arranging biogas equipment, you need to be extremely attentive to details. Errors are unacceptable, because... may lead to explosions and destruction. We offer video instructions that will help you understand the design of the plants, assemble them correctly and supplement them with useful devices for more convenient use of biogas.

The video describes how a standard biogas plant works and works:

An example of a homemade biogas plant. Video tutorial on how to set up a system with your own hands:

Video instructions for assembling a biogas plant from a barrel:

Description of the manufacturing process of substrate mixers:

Detailed description of the operation of a homemade gas storage:

No matter how simple the biogas installation chosen for a private home is, you should not skimp on it. If possible, it is better to buy a collapsible industrial bioreactor. If not, make it from high-quality and sustainable materials: polymers, concrete or stainless steel. This will allow you to create a truly reliable and safe gas supply system at home.

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How to install heating in a private house with your own hands

Rising energy prices make us think about the possibility of providing ourselves with them ourselves. One option is a biogas plant. With its help, biogas is obtained from manure, droppings and plant residues, which, after purification, can be used for gas appliances (stoves, boilers), pumped into cylinders and used as fuel for cars or electric generators. In general, processing manure into biogas can meet all the energy needs of a home or farm.

Construction of a biogas plant is a way to independently provide energy resources

General principles

Biogas is a product that is obtained from the decomposition of organic substances. During the process of rotting/fermentation, gases are released, collecting which you can meet the needs of your own household. The equipment in which this process occurs is called a “biogas plant”.

The process of biogas formation occurs due to the vital activity of various kinds of bacteria that are contained in the waste itself. But in order for them to actively “work”, they need to create certain conditions: humidity and temperature. To create them, a biogas plant is being built. This is a complex of devices, the basis of which is a bioreactor, in which waste decomposition occurs, which is accompanied by gas formation.

There are three modes for processing manure into biogas:

• Psychophilic mode. The temperature in the biogas plant is from +5°C to +20°C. Under such conditions, the decomposition process is slow, much gas is formed, and its quality is low.
• Mesophilic. The unit enters this mode at temperatures from +30°C to +40°C. In this case, mesophilic bacteria actively reproduce. In this case, more gas is formed, the processing process takes less time - from 10 to 20 days.
• Thermophilic. These bacteria multiply at temperatures from +50°C. The process is the fastest (3-5 days), the gas output is the largest (under ideal conditions, with 1 kg of delivery you can get up to 4.5 liters of gas). Most reference tables for gas yield from processing are given specifically for this mode, so when using other modes it is worth making a smaller adjustment.

The most difficult thing to implement in biogas plants is the thermophilic mode. This requires high-quality thermal insulation of the biogas plant, heating and a temperature control system. But at the output we get the maximum amount of biogas. Another feature of thermophilic processing is the impossibility of additional loading. The remaining two modes - psychophilic and mesophilic - allow you to add a fresh portion of prepared raw materials daily. But, in the thermophilic mode, the short processing time makes it possible to divide the bioreactor into zones in which their share of raw materials will be processed with different loading times.

Biogas plant diagram

The basis of a biogas plant is a bioreactor or bunker. The fermentation process occurs in it, and the resulting gas accumulates in it. There is also a loading and unloading hopper; the generated gas is discharged through a pipe inserted into the upper part. Next comes the gas treatment system - cleaning it and increasing the pressure in the gas pipeline to working pressure.

For mesophilic and thermophilic modes, a bioreactor heating system is also required to reach the required modes. For this purpose, gas boilers running on produced fuel are usually used. From it, a pipeline system goes to the bioreactor. Usually these are polymer pipes, since they best withstand being in an aggressive environment.

A biogas plant also needs a system for mixing the substance. During fermentation, a hard crust forms at the top, and heavy particles settle down. All this together worsens the process of gas formation. Mixers are needed to maintain a homogeneous state of the processed mass. They can be mechanical or even manual. They can be started by timer or manually. It all depends on how the biogas plant is made. An automated system is more expensive to install, but requires a minimum of attention during operation.

According to the type of location, a biogas plant can be:

• Overground.
• Semi-recessed.
• Recessed.

Recessed ones are more expensive to install - a large amount of excavation work is required. But when used in our conditions, they are better - it is easier to organize insulation, and the heating costs are lower.

What can be recycled

A biogas plant is essentially omnivorous - any organic matter can be processed. Any manure and urine, plant residues are suitable. Detergents, antibiotics, and chemicals negatively affect the process. It is advisable to minimize their intake, as they kill the flora that processes them.

Cattle manure is considered ideal, since it contains large quantities of microorganisms. If there are no cows on the farm, when loading the bioreactor, it is advisable to add some of the manure to populate the substrate with the required microflora. Plant residues are pre-crushed and diluted with water. Plant materials and excrement are mixed in a bioreactor. This “filling” takes longer to process, but at the end of the day, under the correct mode, we have the highest product yield.

Location determination

To minimize the costs of organizing the process, it makes sense to locate the biogas plant close to the source of waste - near buildings where poultry or animals are kept. It is advisable to develop the design so that loading occurs by gravity. From a barn or pigsty, you can lay a pipeline at a slope through which manure will flow by gravity into the bunker. This greatly simplifies the task of maintaining the reactor, and also removing manure.

It is most advisable to locate the biogas plant so that waste from the farm can flow by gravity

Typically, buildings with animals are located at some distance from a residential building. Therefore, the generated gas will need to be transferred to consumers. But laying one gas pipe is cheaper and easier than organizing a line for transporting and loading manure.

Bioreactor

There are quite strict requirements for manure processing tanks:

All these requirements for the construction of a biogas plant must be met, as they ensure safety and create normal conditions for processing manure into biogas.

What materials can it be made from?

Resistance to aggressive environments is the main requirement for materials from which containers can be made. The substrate in the bioreactor can be acidic or alkaline. Accordingly, the material from which the container is made must tolerate various environments well.

Not many materials meet these requests. The first thing that comes to mind is metal. It is durable and can be used to make containers of any shape. The good thing is that you can use a ready-made container - some old tank. In this case, the construction of a biogas plant will take very little time. The disadvantage of metal is that it reacts with chemically active substances and begins to deteriorate. To neutralize this disadvantage, the metal is coated with a protective coating.

An excellent option is a bioreactor container made of polymer. Plastic is chemically neutral, does not rot, does not rust. You just need to choose from materials that can withstand freezing and heating to fairly high temperatures. The reactor walls should be thick, preferably glass fiber reinforced. Such containers are not cheap, but they last a long time.

A cheaper option is a biogas plant with a container made of bricks, concrete blocks, or stone. In order for the masonry to withstand high loads, it is necessary to reinforce the masonry (in every 3-5 rows, depending on the thickness of the wall and the material). After completing the wall construction process, to ensure water and gas impermeability, subsequent multi-layer treatment of the walls is necessary both inside and outside. The walls are plastered with a cement-sand composition with additives (additives) that provide the required properties.

Reactor sizing

The reactor volume depends on the selected temperature for processing manure into biogas. Most often, mesophilic is chosen - it is easier to maintain and it allows for the possibility of daily reloading of the reactor. Biogas production after reaching normal mode (about 2 days) is stable, without surges or dips (when normal conditions are created). In this case, it makes sense to calculate the volume of the biogas plant depending on the amount of manure generated on the farm per day. Everything is easily calculated based on average statistical data.

The decomposition of manure at mesophilic temperatures takes from 10 to 20 days. Accordingly, the volume is calculated by multiplying by 10 or 20. When calculating, it is necessary to take into account the amount of water that is necessary to bring the substrate to an ideal state - its humidity should be 85-90%. The found volume is increased by 50%, since the maximum load should not exceed 2/3 of the tank volume - gas should accumulate under the ceiling.

For example, there are 5 cows, 10 pigs and 40 chickens on a farm. Basically, 5 * 55 kg + 10 * 4.5 kg + 40 * 0.17 kg = 275 kg + 45 kg + 6.8 kg = 326.8 kg. To bring chicken manure to 85% humidity, you need to add a little more than 5 liters of water (that’s another 5 kg). The total weight is 331.8 kg. For processing in 20 days you need: 331.8 kg * 20 = 6636 kg - about 7 cubic meters only for the substrate. We multiply the found figure by 1.5 (increase by 50%), we get 10.5 cubic meters. This will be the calculated volume of the biogas plant reactor.

Loading and unloading hatches lead directly into the bioreactor tank. In order for the substrate to be evenly distributed over the entire area, they are made at opposite ends of the container.

When installing a biogas plant in-depth, the loading and unloading pipes approach the body at an acute angle. Moreover, the lower end of the pipe should be below the liquid level in the reactor. This prevents air from entering the container. Also, rotary or shut-off valves are installed on the pipes, which are closed in the normal position. They open only during loading or unloading.

Since manure may contain large fragments (litter elements, grass stems, etc.), small diameter pipes will often become clogged. Therefore, for loading and unloading, they must have a diameter of 20-30 cm. They must be installed before the start of work on insulating the biogas plant, but after the container is installed in place.

The most convenient mode of operation of a biogas plant is with regular loading and unloading of the substrate. This operation can be performed once a day or once every two days. Manure and other components are preliminarily collected in a storage tank, where they are brought to the required state - crushed, if necessary, moistened and mixed. For convenience, this container may have a mechanical stirrer. The prepared substrate is poured into the receiving hatch. If you place the receiving container in the sun, the substrate will be preheated, which will reduce the cost of maintaining the required temperature.

It is advisable to calculate the installation depth of the receiving hopper so that waste flows into it by gravity. The same applies to unloading into the bioreactor. The best case is if the prepared substrate moves by gravity. And a shutter will fence it off during preparation.

To ensure the tightness of the biogas plant, the hatches on the receiving hopper and in the unloading area must have a sealing rubber seal. The less air there is in the container, the cleaner the gas will be at the outlet.

Collection and disposal of biogas

Biogas is removed from the reactor through a pipe, one end of which is under the roof, the other is usually lowered into a water seal. This is a container with water into which the resulting biogas is discharged. There is a second pipe in the water seal - it is located above the liquid level. Cleaner biogas comes out into it. A gas shut-off valve is installed at the outlet of their bioreactor. The best option is a ball one.

What materials can be used for the gas transmission system? Galvanized metal pipes and gas pipes made of HDPE or PPR. They must ensure tightness; seams and joints are checked using soap foam. The entire pipeline is assembled from pipes and fittings of the same diameter. No contractions or expansions.

Purification from impurities

The approximate composition of the resulting biogas is:

• methane - up to 60%;
• carbon dioxide - 35%;
• other gaseous substances (including hydrogen sulfide, which gives gas bad smell) — 5%.

In order for biogas to be odorless and burn well, it is necessary to remove carbon dioxide, hydrogen sulfide, and water vapor from it. Carbon dioxide is removed in a water seal if slaked lime is added to the bottom of the installation. Such a bookmark will have to be changed periodically (as soon as the gas starts to burn worse, it’s time to change it).

Gas drying can be done in two ways - by making water seals in the gas pipeline - by inserting curved sections into the pipe under the water seals, in which condensate will accumulate. The disadvantage of this method is the need to regularly empty the water seal - if there is a large amount of collected water, it can block the passage of gas.

The second way is to install a filter with silica gel. The principle is the same as in a water seal - the gas is supplied to the silica gel, and dried out from under the lid. With this method of drying biogas, the silica gel must be dried periodically. To do this, you need to warm it up in the microwave for some time. It heats up and the moisture evaporates. You can fill it up and use it again.

To remove hydrogen sulfide, a filter loaded with metal shavings is used. You can load old metal scourers into the container. Purification occurs in exactly the same way: gas is supplied to the lower part of a container filled with metal. As it passes, it is cleared of hydrogen sulfide, collected in the upper free part of the filter, from where it is discharged through another pipe/hose.

Gas tank and compressor

The purified biogas enters a storage tank - a gas holder. This can be a sealed plastic bag or plastic container. The main condition is gas tightness; shape and material do not matter. The gas holder stores a supply of biogas. From it, with the help of a compressor, gas under a certain pressure (set by the compressor) is supplied to the consumer - to the gas stove or boiler. This gas can also be used to generate electricity using a generator.

To create stable pressure in the system after the compressor, it is advisable to install a receiver - a small device for leveling pressure surges.

Mixing devices

In order for the biogas plant to operate normally, it is necessary to regularly mix the liquid in the bioreactor. This simple process solves many problems:

• mixes a fresh portion of the load with a colony of bacteria;
• promotes the release of produced gas;
• equalizes the temperature of the liquid, excluding warmer and colder areas;
• maintains the homogeneity of the substrate, preventing the settling or floating of some components.

Typically, a small homemade biogas plant has mechanical agitators that are driven by muscle power. In large-volume systems, the agitators can be driven by motors that are activated by a timer.

The second method is to stir the liquid by passing some of the generated gas through it. To do this, after exiting the metatank, a tee is installed and part of the gas flows into the lower part of the reactor, where it exits through a tube with holes. This part of the gas cannot be considered a consumption, since it still enters the system again and, as a result, ends up in the gas tank.

The third method of mixing is to pump the substrate from the bottom using fecal pumps and pour it at the top. The disadvantage of this method is its dependence on the availability of electricity.

Heating system and thermal insulation

Without heating the processed liquid, psychophilic bacteria will multiply. The processing process in this case will take 30 days, and the gas output will be small. In the summer, if there is thermal insulation and preheating of the load, it is possible to reach temperatures of up to 40 degrees, when the development of mesophilic bacteria begins, but in winter such an installation is practically inoperative - the processes proceed very sluggishly. At temperatures below +5°C they practically freeze.

What to heat and where to place it

To receive best results use heating. The most rational is water heating from a boiler. The boiler can run on electricity, solid or liquid fuel, and you can also run it on the produced biogas. The maximum temperature to which water needs to be heated is +60°C. Hotter pipes can cause particles to stick to the surface, reducing heating efficiency.

You can also use direct heating - insert heating elements, but firstly, it is difficult to organize mixing, secondly, the substrate will stick to the surface, reducing heat transfer, the heating elements will quickly burn out

A biogas plant can be heated using standard heating radiators, simply pipes twisted into a coil, or welded registers. It is better to use polymer pipes - metal-plastic or polypropylene. Corrugated stainless steel pipes are also suitable; they are easier to install, especially in cylindrical vertical bioreactors, but the corrugated surface provokes sediment sticking, which is not very good for heat transfer.

To reduce the possibility of particles settling on the heating elements, they are located in the stirrer area. Only in this case everything must be designed so that the mixer cannot touch the pipes. It often seems that it is better to place the heaters at the bottom, but practice has shown that due to sediment on the bottom, such heating is ineffective. So it is more rational to place heaters on the walls of the metatank of a biogas plant.

Water heating methods

Depending on the method of pipe arrangement, heating can be external or internal. When installed internally, heating is effective, but repair and maintenance of heaters is impossible without stopping and pumping out the system. Therefore, special attention is paid to the selection of materials and the quality of connections.

Heating increases the productivity of the biogas plant and reduces the processing time of raw materials

When the heaters are located externally, more heat is required (the cost of heating the contents of a biogas plant is much higher), since a lot of heat is spent on heating the walls. But the system is always available for repair, and heating is more uniform, since the environment is heated from the walls. Another advantage of this solution is that stirrers cannot damage the heating system.

How to insulate

First, a leveling layer of sand is poured onto the bottom of the pit, then a heat-insulating layer. It can be clay mixed with straw and expanded clay, slag. All these components can be mixed and poured in separate layers. They are leveled to the horizon, and the capacity of the biogas plant is installed.

The sides of the bioreactor can be insulated with modern materials or with classic old-fashioned methods. One of the old-fashioned methods is coating with clay and straw. Apply in several layers.

Modern materials include high-density extruded polystyrene foam, low-density aerated concrete blocks, etc. The most technologically advanced in this case is polyurethane foam (PPU), but the services for its application are not cheap. But the result is seamless thermal insulation, which minimizes heating costs. There's another one thermal insulation material- foam glass. It is very expensive in slabs, but its chips or crumbs cost very little, and in terms of characteristics it is almost ideal: it does not absorb moisture, is not afraid of freezing, tolerates static loads well, and has low thermal conductivity.

Biological gas (biogas) is a substance that consists of carbon dioxide (40%) and methane (60%). Its analogues are swamp gas, mine gas, sewer gas and methane.

If we take manure as an example, then if an enterprise produces a ton of this biological waste per day, approximately 50 m 3 of gas, or 100 kW of electrical energy, or 35 liters of diesel fuel can be obtained from this amount of material. Equipment for the production of biogas pays for itself in two to three years, and when using other types of raw materials, the period may be even shorter - about one and a half years.

Benefits from a biogas plant

A biogas production plant will bring more than just monetary profit to the company. There are also indirect benefits to its use. For example, it will cost much less than installing power lines, gas pipelines, creating lagoons or backup diesel generators.

Biogas plants are modern bioreactor complexes. They operate with minimal costs and high efficiency. Basically, equipment for the production of biogas is installed on the basis of livestock enterprises, complexes for processing agricultural products and other waste.

Purpose of the biogas plant

As a rule, biogas production plants are used for processing waste from the food industry and agriculture. Thanks to such equipment, it is possible not only to use waste materials, but also to improve the environmental situation in production and processing areas.

In addition, an additional source of energy resources is provided. In fact, biogas production equipment shortens the cycle of substances many times over, from several years to several weeks.

Components that a biogas plant must include

1. Homogenization container.
2. Reactor.
3. Loader of raw materials: solid or liquid.
4. Gas holder.
5. Stirrers.
6. Fuel and water connection system.
7. Gas system.
8. Separator.
9. Pumping station.
10. Control devices.
11. Instrumentation and automation with visualization capabilities.
12. Security system.

Raw material waste is periodically supplied to the reactor using a loader or pumping station. The reactor is a reinforced concrete tank, insulated and heated, equipped with mixers. It contains beneficial bacteria that feed on waste and produce biogas during their life.

In order for the bacteria to be constantly viable, they need to be fed food - waste materials, ensure a temperature of no higher than 35 degrees and stir from time to time. The gas generated during the process is accumulated in a special storage facility (gas holder), and then, after passing through the cleaning system, it is supplied to the final point, to a boiler or electric generator. The reactor is completely sealed and safe.

Biogas use

Biogas is used as fuel to generate heat, steam, electricity or to refuel cars. Equipment for the production of biogas can also be installed as a treatment facility at poultry farms, farms, meat processing plants, alcohol and sugar factories.

For new enterprises, the use of such an installation will significantly reduce start-up costs, since it will be possible not to spend money on laying power lines, gas pipelines, not installing diesel generators and not building waste storage tanks. As a result, capital costs are reduced by approximately 30-40% of the cost of equipment for biogas production.

The topic of alternative fuels has been relevant for several decades. Biogas is a natural fuel source that you can produce and use yourself, especially if you have livestock.

What is it

The composition of biogas is similar to that produced on an industrial scale. Stages of biogas production:

1. A bioreactor is a container in which biological mass is processed by anaerobic bacteria in a vacuum.
2. After some time, a gas is released consisting of methane, carbon dioxide, hydrogen sulfide and other gaseous substances.
3. This gas is purified and removed from the reactor.
4. Recycled biomass is an excellent fertilizer that is removed from the reactor to enrich fields.

Producing biogas with your own hands at home is possible provided that you live in a village and have access to animal waste. It is a good fuel option for livestock farms and agricultural enterprises.

The advantage of biogas is that it reduces methane emissions and provides an alternative energy source. As a result of biomass processing, fertilizer is formed for vegetable gardens and fields, which is an additional advantage.

To make your own biogas, you need to build a bioreactor to process manure, bird droppings and other organic waste. The raw materials used are:

• waste water;
• straw;
• grass;
• river silt

It is important to prevent chemical impurities from entering the reactor, as they interfere with the processing process.

Use Cases

Processing manure into biogas makes it possible to obtain electrical, thermal and mechanical energy. This fuel is used on an industrial scale or in private homes. It is used for:

• heating;
• lighting;
• water heating;
• operation of internal combustion engines.

Using a bioreactor, you can create your own energy base to power your private home or agricultural production.

Thermal power plants using biogas are an alternative way to heat a private farm or small village. Organic waste can be converted into electricity, which is much cheaper than running it to the site and paying utility bills. Biogas can be used for cooking on gas stoves. The great advantage of biofuel is that it is an inexhaustible, renewable source of energy.

Biofuel efficiency

Biogas from litter and manure is colorless and odorless. It provides the same amount of heat as natural gas. One cubic meter of biogas provides the same amount of energy as 1.5 kg of coal.

Most often, farms do not dispose of waste from livestock, but store it in one area. As a result, methane is released into the atmosphere, and manure loses its properties as a fertilizer. Timely recycled waste will bring much more benefit farming.

It is easy to calculate the efficiency of manure disposal in this way. The average cow produces 30-40 kg of manure per day. This mass produces 1.5 cubic meters of gas. From this amount, 3 kW/h of electricity is generated.

How to build a biomaterial reactor

Bioreactors are concrete containers with holes for the removal of raw materials. Before construction, you need to choose a location on the site. The size of the reactor depends on the amount of biomass you have daily. It should fill the container 2/3 full.

If there is not much biomass, instead of a concrete container, you can take an iron barrel, for example, an ordinary barrel. But it must be strong, with high-quality welds.

The amount of gas produced directly depends on the volume of raw materials. In a small container you will get a little of it. To get 100 cubic meters of biogas, you need to process a ton of biological mass.

To increase the strength of the installation, it is usually buried in the ground. The reactor must have an inlet pipe for loading biomass and an outlet for removing waste material. There should be a hole at the top of the tank through which biogas is discharged. It is better to close it with a water seal.

For a correct reaction, the container must be hermetically sealed, without air access. The water seal will ensure timely removal of gases, which will prevent the system from exploding.

Reactor for a large farm

A simple bioreactor design is suitable for small farms with 1-2 animals. If you own a farm, it is best to install an industrial reactor that can handle large volumes of fuel. It is best to involve special companies involved in developing the project and installing the system.

Industrial complexes consist of:

• Interim storage tanks;
• Mixing installations;
• A small thermal power plant that provides energy for heating buildings and greenhouses, as well as electricity;
• Containers for fermented manure used as fertilizer.

The most effective option is to build one complex for several neighboring farms. The more biomaterial is processed, the more energy is produced as a result.

Before receiving biogas, industrial installations must be approved by the sanitary and epidemiological station, fire and gas inspection. They are documented; there are special standards for the location of all elements.

How to calculate reactor volume

The volume of the reactor depends on the amount of waste generated daily. Remember that the container only needs to be 2/3 full for effective fermentation. Also consider fermentation time, temperature and type of raw material.

It is best to dilute manure with water before sending it to the digester. It will take about 2 weeks to process manure at a temperature of 35-40 degrees. To calculate the volume, determine the initial volume of waste with water and add 25-30%. The volume of biomass should be the same every two weeks.

How to ensure biomass activity

For proper fermentation of biomass, it is best to heat the mixture. In the southern regions, the air temperature promotes the onset of fermentation. If you live in the north or in the middle zone, you can connect additional heating elements.

To start the process, a temperature of 38 degrees is required. There are several ways to ensure this:

• A coil under the reactor connected to the heating system;
• Heating elements inside the container;
• Direct heating of the container with electric heating devices.

The biological mass already contains bacteria that are needed to produce biogas. They wake up and begin activity when the air temperature rises.

It is best to heat them with automatic heating systems. They turn on when cold mass enters the reactor and automatically turn off when the temperature reaches the desired value. Such systems are installed in water heating boilers; they can be purchased at gas equipment stores.

If you provide heating to 30-40 degrees, then processing will take 12-30 days. It depends on the composition and volume of the mass. When heated to 50 degrees, bacterial activity increases, and processing takes 3-7 days. The disadvantage of such installations is the high cost of maintaining high temperatures. They are comparable to the amount of fuel received, so the system becomes ineffective.

Another way to activate anaerobic bacteria is by stirring the biomass. You can install the shafts in the boiler yourself and move the handle out to stir the mass if necessary. But it is much more convenient to design an automatic system that will mix the mass without your participation.

Correct gas removal

Biogas from the manure is removed through the top cover of the reactor. It must be tightly closed during the fermentation process. Typically a water seal is used. It controls the pressure in the system; when it increases, the lid rises and the release valve is activated. A weight is used as a counterweight. At the outlet, the gas is purified with water and flows further through the tubes. Purification with water is necessary to remove water vapor from the gas, otherwise it will not burn.

Before biogas can be processed into energy, it must be accumulated. It should be stored in a gas tank:

• It is made in the shape of a dome and installed at the outlet of the reactor.
• Most often it is made of iron and coated with several layers of paint to prevent corrosion.
• In industrial complexes, the gas tank is a separate tank.

Another option for making a gas holder: use a PVC bag. This elastic material stretches as the bag fills. If necessary, it can store large quantities of biogas.

Underground biofuel production plant

To save space, it is best to build underground installations. This is the easiest way to get biogas at home. To set up an underground bioreactor, you need to dig a hole and fill its walls and bottom with reinforced concrete.

Holes are made on both sides of the container for the inlet and outlet pipes. Moreover, the outlet pipe should be located at the base of the container for pumping out the waste mass. Its diameter is 7-10 cm. The entrance hole with a diameter of 25-30 cm is best located in the upper part.

The installation is covered with brickwork on top and a gas tank is installed to receive biogas. At the outlet of the container you need to make a valve to regulate the pressure.

A biogas plant can be buried in the yard of a private house and sewage and livestock waste can be connected to it. Recycling reactors can completely cover a family's electricity and heating needs. An additional benefit is getting fertilizer for your garden.

A DIY bioreactor is a way to get energy from pasture and make money from manure. It reduces farm energy costs and increases profitability. You can do it yourself or order installation. The price depends on the volume, starting from 7,000 rubles.

Owners of private houses located in regions with limited access to traditional fuels should definitely turn their attention to modern biogas plants. Such units make it possible to obtain biogas from a variety of organic waste and use it for personal needs, including heating residential premises.

Gas can be obtained from almost any biomass - waste from the livestock industry, food production, agriculture, foliage, etc. At the same time, you can build such an installation with your own hands.

Both homogeneous raw materials and mixtures of various biomass are suitable for producing biogas. A biogas plant is a volumetric sealed structure equipped with devices for supplying raw materials, heating biomass, mixing components, discharging the resulting biogas into a gas collector and, of course, protecting the structure.

In the reactor, under the influence of anaerobic bacteria, rapid decomposition of biomass occurs. During the fermentation of organic raw materials, biogas is released. Approximately 70% of the composition of such gas is represented by methane, the remaining part is carbon dioxide.

Biogas is characterized by excellent calorific value; it has no pronounced odor or color. In terms of its properties, biogas is practically in no way inferior to more traditional natural gas.

In developed countries, additional installations are used to purify biogas from carbon dioxide. If you wish, you can buy the same installation and obtain pure biomethane.

Biogas plants on silos. 1 Silo pits. 2 Biomass loading system. 3 Reactor. 4 Post-fermentation reactor. 5 Substrater. 6 Heating system. 7 Power plant. 8 Automation and control system. 9 Gas pipeline system

Comparison of biogas with more traditional fuels

On average, one cow or other animal weighing half a ton is capable of producing enough manure per day to produce approximately 1.5 m3 of biogas. Daily manure from one average pig can be processed into 0.2 m3 of biogas, and a rabbit or chicken into 0.01-0.02 m3 of fuel.

For comparison: 1 m3 of biogas from manure provides approximately the same amount of thermal energy as 3.5 kg of firewood, 1-2 kg of coal, 9-10 kW/h of electricity.

The simplest mixture recipe for producing biogas includes the following components:

• cow manure - about 1500 kg;
• rotted leaves or other organic waste – 3500 kg;
• water – 65-75% of the total mass of the previous components. The water must first be heated to about 35 degrees.

This amount of biomass will be enough to produce biogas for six months of operation with moderate consumption. On average, biogas begins to be released within 1.5-2 weeks after the mixture is loaded into the installation.

Gas can be used to heat a home and a variety of commercial and domestic buildings.

Design of a typical biogas plant

The main components of a complete biogas system are:

• reactor;
• humus supply system;
• stirrers;
• automated biomass heating system;
• gas holder;
• separator;
• protective part.

A household installation will have a somewhat simplified design, however, for a complete understanding, you are invited to read the description of all the listed elements.

Reactor

This part of the installation is usually assembled from stainless steel or concrete. Externally, the reactor looks like a large sealed container, on top of which is a dome, usually spherical in shape.

Currently, the most popular are reactors with a collapsible design, made using innovative technologies. Such a reactor can be easily assembled with your own hands with minimal time investment. If necessary, it can be easily disassembled and transported to another location.

Steel is convenient because you can easily create holes in it to connect other elements of the system. Concrete is superior to steel in terms of strength and durability.

Biomass feeding system

This part of the installation includes a hopper for receiving waste, a supply pipeline for water supply and a screw pump designed to send humus to the reactor.

A front loader is used to load the dry component into the hopper. At home, you can cope with this task without a loader, using various improvised means, for example, shovels.

In the hopper the mixture is moistened to a semi-liquid state. After reaching the desired level of moisture, the screw transfers the semi-liquid mass to the lower compartment of the reactor.

Stirrers

Fermentation of humus in the reactor should occur evenly. This is one of the most important conditions for ensuring intensive release of biogas from the mixture. It is to achieve the most uniform fermentation process of the mixture that the design of a typical biogas plant includes mixers with electric drives.

There are submersible and inclined type mixers. Submersible mechanisms can be lowered into the biomass to the required depth to ensure intensive and uniform mixing of the substrate. Usually such mixers are placed on a mast.

Installation of inclined mixers is carried out on the side surfaces of the reactor. An electric motor is responsible for rotating the screw in the fermenter.

Automated heating system

To successfully produce biogas, the temperature inside the system must be maintained at +35-+40 degrees. For this purpose, automated heating systems are included in the design.

The heat source in this case is a hot water boiler; in some situations, electric heating units are used.

Biogas is collected in this structural element. Most often, the gas holder is placed on the roof of the reactor.

The production of modern gas tanks is usually carried out using polyvinyl chloride, a material that is resistant to sunlight and various adverse natural phenomena.

In some situations, instead of a regular gas tank, special bags are used. Also, these devices allow you to temporarily increase the volume of the produced biogas.

To make a gas holder bag, a special polyvinyl chloride with elastic properties is used, which can inflate as the volume of biogas increases.

This part of the system is responsible for drying waste humus and obtaining, if necessary, high-quality fertilizers.

The simplest separator consists of a screw and a separator chamber. The chamber is made in the form of a sieve. This allows the biomass to be separated into a solid component and a liquid part.

The dried humus is sent to the shipping compartment. The system directs the liquid part back to the receiving chamber. Here the liquid is used to moisten the new feedstock.

The simplest DIY biogas plant

A household biogas installation will have a somewhat simplified design, but its manufacture should be approached with maximum responsibility.

First step. Dig a hole. At its core, a biogas plant is a large pit with a special finish. The most important and at the same time difficult part of manufacturing the system in question is the correct preparation of the walls of the bioreactor and its base.

The pit must be sealed. Strengthen the base and walls with plastic or concrete. Instead, you can purchase ready-made polymer rings with a solid bottom. Such devices make it possible to ensure the necessary tightness of the system. The material will retain its original characteristics for many years, and if necessary, you can easily replace the old ring with a new one.

Second step. Install a gas drainage system. This will save you from the need to purchase and install agitators, due to which the time and money spent on assembling the installation will be significantly reduced.

The simplest version of a gas drainage system is vertically fixed sewer pipes made of polyvinyl chloride with many holes throughout the body.

Select pipes of such length that their upper edges rise slightly above the upper level of the loaded humus.

Third step. Cover the outer layer of the substrate with film insulation. Thanks to the film, conditions will be created for the accumulation of biogas under the dome under conditions of slight excess pressure.

Fourth step. Install the dome and mount the gas exhaust pipe at its highest point.

Gas consumption should be regular. Otherwise, the dome over the biomass container may simply explode. In summer, gas is formed more intensively than in winter. To solve the latter problem, purchase and install suitable heaters.

Procedure and conditions for successful use of a biogas plant

Thus, it is not difficult to assemble a simple biogas plant yourself. However, for its successful operation, you must remember and follow a few simple rules.

One of the most important requirements is that the loaded organic mass should not contain any substances that can have a negative impact on the life of anaerobic microorganisms. Prohibited inclusions include various types of solvents, antibacterial drugs and other similar substances.

A number of inorganic substances can also lead to deterioration in the functioning of bacteria. In view of this, it is prohibited, for example, to dilute humus with water remaining after washing clothes or washing a car.

Remember: a biogas installation is a potentially explosive unit, so follow all safety regulations relevant for the operation of any gas equipment.

Thus, even manure and, in principle, almost everything that you previously tried your best to get rid of, can be useful on the farm. You just need to properly build a home biogas installation, and very soon your home will be warm. Follow the recommendations received, and you will no longer have to spend enormous sums on heating.

Good luck!