Installation for biogas production (cheap do-it-yourself gas). Methods for self-production of biogas Biogas plant farmer

Required mandatory materials:

• two containers;
• connecting pipes;
• valves;
• gas filter;
• means of ensuring tightness (glue, resin, sealant, etc.);

Desirable:

• stirrer with electric motor;
• temperature sensor;
• pressure meter;

The sequence below is suitable for the southern regions. For operation under any conditions, a reactor heating system should be added, which will ensure heating of the vessel to 40 degrees Celsius and increase thermal insulation, for example, by enclosing the structure with a greenhouse. It is advisable to cover the greenhouse with black film. It is also advisable to add a condensate drainage device to the pipeline.

Creating a simple biogas plant:

1. Create a storage container. We select a tank where the resulting biogas will be stored. The reservoir is fixed with a valve and equipped with a pressure gauge. If gas consumption is constant, then there is no need for a gas tank.
2. Insulate the structure inside the pit.
3. Install pipes. Lay pipes into the pit for loading raw materials and unloading compost humus. An inlet and outlet hole are made in the reactor tank. The reactor is placed in a pit. Pipes are connected to the holes. The pipes are tightly secured using glue or other suitable means. Pipe diameters less than 30 cm will contribute to their clogging. The loading location should be chosen on the sunny side.
4. Install sunroof. The rector, equipped with a hatch, makes repair and maintenance work more convenient. The hatch and reactor vessel should be sealed with rubber. You can also install temperature, pressure and raw material level sensors.
5. Select a container for the bioreactor. The selected container must be durable - since fermentation releases a large amount of energy; have good thermal insulation; be air and waterproof. Egg-shaped vessels are best suited. If building such a reactor is problematic, then a cylindrical vessel with rounded edges would be a good alternative. Square-shaped containers are less efficient because hardened biomass will accumulate in the corners, making fermentation difficult.
6. Prepare the pit.
7. Select a location for mounting the future installation. It is advisable to choose a place far enough from the house and so that you can dig a hole. Placing it inside a pit allows you to significantly save on thermal insulation, using cheap materials like clay.
8. Check the tightness of the resulting structure.
9. Start the system.
10. Add raw materials. We wait about two weeks until all the necessary processes take place. A necessary condition for gas combustion is to get rid of carbon dioxide. A regular filter from a hardware store will do for this. A homemade filter is made from a 30 cm long piece of gas pipe filled with dry wood and metal shavings.

Composition and types

Biogas is a gas obtained as a result of a three-phase biochemical process on biomass, taking place in sealed conditions.

The process of biomass decomposition is sequential: first it is exposed to hydrolytic bacteria, then acid-forming bacteria and finally methane-forming bacteria. The material for microorganisms at each stage is the product of the activity of the previous stage.

At the output, the approximate composition of biogas looks like this:

• methane (from 50 to 70%);
• carbon dioxide (from 30 to 40%);
• hydrogen sulfide (~2%);
• hydrogen (~1%);
• ammonia (~1%);

The accuracy of the proportions is affected by the raw materials used and gas production technology. Methane has the potential for combustion; the higher its percentage, the better.

Ancient cultures dating back more than three thousand years (India, Persia or Assyria) have experience using flammable swamp gas. The scientific basis was formed much later. The chemical formula of methane CH 4 was discovered by scientist John Dalton, and the presence of methane in swamp gas was discovered by Humphry Davy. The Second World War played a major role in the development of the alternative energy industry, requiring the warring parties to have a huge need for energy resources.

The USSR's possession of huge reserves of oil and natural gas led to a lack of demand for other energy production technologies; the study of biogas was mainly a subject of interest to academic science. At the moment, the situation has changed so much that, in addition to the industrial production of various types of fuel, anyone can create a biogas plant for their own purposes.

Installation device

– a set of equipment designed to produce biogas from organic raw materials.

Based on the type of raw material supplied, the following types of biogas plants are distinguished:

• with portioned feeding;
• with continuous feed;

Biogas plants with a constant supply of raw materials are more efficient.

By type of raw material processing:

1. No automatic stirring raw materials and maintaining the required temperature - complexes with minimal equipment, suitable for small farms (Diagram 1).
2. With automatic stirring, but without maintaining the required temperature - also serves small farms, more efficiently than the previous type.
3. With support for the required temperature, but without automatic mixing.
4. With automatic mixing of raw materials and temperature support.

Principle of operation

The process of converting organic raw materials into biogas is called fermentation. The raw materials are loaded into a special container that provides reliable protection of the biomass from oxygen. An event that occurs without the intervention of oxygen is called anaerobic.

Under the influence of special bacteria, fermentation begins to occur in an anaerobic environment. As fermentation progresses, the raw material becomes covered with a crust, which must be destroyed regularly. Destruction is carried out by thorough mixing.

It is necessary to mix the contents at least twice a day, without violating the tightness of the process. In addition to removing the crust, stirring allows you to evenly distribute acidity and temperature inside the organic mass. As a result of these manipulations, biogas is produced.

The resulting gas is collected in a gas tank and from there it is delivered to the consumer through pipes. Biofertilizers obtained after processing the feedstock can be used as a food additive for animals or added to the soil. This fertilizer is called compost humus.

The biogas plant includes the following elements:

• homogenization tank;
• reactor;
• stirrers;
• storage tank (gas-holder);
• heating and water mixing complex;
• gas complex;
• complex of pumps;
• separator;
• control sensors;
• I&C with visualization;
• safety system;

An example of an industrial type biogas plant is shown in Scheme 2.

Raw materials used

The decomposition of any animal or plant matter will release flammable gas to varying degrees. Mixtures of various compositions are well suited for raw materials: manure, straw, grass, various wastes, etc. The chemical reaction requires a humidity of 70%, so the raw material must be diluted with water.

The presence of cleaning agents, chlorine, and washing powders in organic biomass is unacceptable, as they interfere with chemical reactions and can damage the reactor. Also not suitable for the reactor are raw materials with sawdust from coniferous trees (containing resins), with a high proportion of lignin and exceeding the moisture threshold of 94%.

Vegetable. Vegetable raw materials are excellent for biogas production. Fresh grass gives the maximum fuel yield - about 250 m 3 of gas with a methane share of 70% is obtained from a ton of raw material. Corn silage is slightly smaller - 220 m 3 . Tops from beets - 180 m 3.

Almost any plant, hay or algae can be used as biomass. The disadvantage of the application lies in the duration of the production cycle. The biogas production process takes up to two months. The raw material must be finely ground.

Animal. Waste from processing, dairy, slaughterhouses, etc. suitable for biogas plant. The maximum fuel yield is provided by animal fats - 1500 m 3 of biogas with a methane share of 87%. The main disadvantage is shortage. Animal raw materials must also be ground.

Excrement. The main advantage of manure is its cheapness and easy availability. Disadvantage – the quantity and quality of biogas is lower than from other types of raw materials. Horse and cow excrement can be processed immediately. The production cycle will take approximately two weeks and will produce an output of 60 m3 with 60% methane content.

Chicken manure and pig manure cannot be used directly because they are toxic. To start the fermentation process, they must be mixed with silage. Human waste products can also be used, but sewage is not suitable since the fecal content is low.

Schemes of work

Scheme 1 – biogas plant without automatic mixing of raw materials:

Scheme 2 – industrial biogas plant:

Biogas plants. Biogas production

Complete stainless steel plants for biogas production.

Biogas plants are a comprehensive solution for recycling waste from the food industry, agro-industrial complex, production of thermal, electrical energy, and fertilizers. The production of methane in a biogas production plant is the implementation of a biological process.

The German company develops and produces complete plants for the production of biogas and sells them worldwide. More than 300 biogas production plants have been built, launched and are successfully operating in Germany, France, the Netherlands, Greece, Great Britain, Sweden, Spain, Luxembourg, the Czech Republic, Lithuania, the USA, Japan and Cyprus. The offered installations are not experimental, but working, proven and reliable German equipment, ISO certified and manufactured complete in our own factory.

We will show you how you can use bioenergy intelligently and economically.

Biogas is a gas consisting of approximately 60% methane (CH4) and 40% carbon dioxide. Synonyms for biogas are sewer gas, mine gas and swamp gas, methane gas. If we consider manure as an example, then if an enterprise produces 1 ton of such “bio-waste” per day, this means that 50 m3 of gas or 100 kW of electricity can be obtained from it, or 35 liters of diesel fuel can be replaced. The payback period for equipment for processing manure is within 2-3 years, and for some other types of raw materials it is even lower and reaches 1.5 years. In addition to direct monetary benefits, the construction of a biogas plant has indirect benefits. For example, it is cheaper than installing a gas pipeline, power lines, backup diesel generators and creating lagoons. The table shows the gas yield for various types of raw materials.

SOURCES OF RAW MATERIALS

An important area of ​​application for biogas production plants is large agro-industrial complexes, cattle farms, poultry farms, fish factories, bakery plants, food industry enterprises, meat processing plants, alcohol factories, breweries, dairies, crop production enterprises, sugar factories, starch factories, production of yeast, and not only as an alternative source of energy, but also as an effective method of recycling manure (litter) and producing cheap fertilizer, both for their own needs and for sale on the market. The biogas plant produces biogas and biofertilizers from organic waste from agriculture and food processing through oxygen-free fermentation, providing the most active treatment system. Cattle manure, pig manure, bird droppings, slaughterhouse waste (blood, fat, intestines, bones), plant waste, silage, rotten grain, sewage, fats, bio-waste, food industry waste, garden waste, malt sludge can be used as raw materials. , pomace, distillery stillage, beet pulp, technical glycerin (from biodiesel production). Most types of raw materials can be mixed with each other. Waste recycling is primarily a cleaning system that pays for itself and makes a profit. At the outlet of the plant, waste is produced simultaneously and in large quantities: biogas, electricity, heat and fertilizers.

Everything listed above is produced at zero cost. After all, manure is free, and the installation itself consumes only 10-15% of energy. One person is enough to operate a powerful installation for two hours a day. Biogas plants are fully automated and, accordingly, labor costs are minimal.

Technology and principle of operation of a biogas plant

The biogas plant produces biogas and biofertilizers from biological waste from agriculture and the food industry through oxygen-free fermentation. Biogas is a waste product of beneficial methane-forming bacteria. Microorganisms metabolize carbon from organic substrates under anoxic conditions (anaerobically). This process, called putrefaction or anoxic fermentation, follows the food chain.

Composition of a typical biogas plant:

Biowaste can be delivered by truck or pumped to a biogas plant. First, the coenzymes are poured out (ground), homogenized and mixed with manure (droppings). Homogenization is most often carried out at a temperature of 70 o C for one hour with a maximum particle size of 1 cm. Homogenization with manure is carried out in a mixing tank with powerful agitators.

The reactor is a gas-tight, completely sealed tank. This design is thermally insulated, because inside the tank there must be a fixed temperature for microorganisms. Inside the reactor there is a mixer designed to completely mix the contents of the reactor. Conditions are created for the absence of floating layers and/or sediment.

Microorganisms must be provided with all necessary nutrients. Fresh raw materials should be fed into the reactor in small portions several times a day. The average time of hydraulic settling inside the reactor (depending on the substrates) is 20-40 days. During this time, organic substances inside the biomass are metabolized (transformed) by microorganisms. At the output of the installation, two products are formed: biogas and substrate (composted and liquid).

Biogas is stored in a gas storage tank, a gas holder, in which the pressure and composition of the gas are equalized. From the gas tank there is a continuous supply of gas to the gas engine generator. Heat and electricity are already produced here. If necessary, biogas is purified to natural gas (95% methane) after such purification, the resulting gas is an analogue of natural gas (90-95% methane CH4). The only difference is its origin.

Biogas plants operate 24 hours a day, 7 days a week, all year round. This mode of operation is another advantage. The entire system is controlled by an automation system. It only takes one person two hours a day to manage it.

This employee controls using an ordinary computer and also operates a tractor for feeding biomass. After 2 weeks of training, a person without special skills can work on the installation, i.e. with secondary or secondary specialized education.

BENEFITS

• Biogas.
• Own bioenergy station.
• Proper disposal of organic waste. Waste into income!
• Biofertilizers. When using fertilizers obtained from biogas plants, yields can be increased by 30-50%. Ordinary manure, bard or other waste cannot be effectively used as fertilizer for 3-5 years. When using a biogas plant, biowaste is fermented and the fermented mass can immediately be used as a highly effective biofertilizer. The fermented mass is ready-made environmentally friendly liquid and solid biofertilizers, devoid of nitrites, weed seeds, pathogenic microflora, helminth eggs, and specific odors. When using such balanced biofertilizers, the yield increases significantly.
• Electricity. By installing a biogas plant, the enterprise will have its own, in fact, free electricity, which means a significant reduction in the cost of production, which in turn will allow the latter to gain additional competitive advantages.
• Warm. The heat from generator cooling or biogas combustion can be used to heat an enterprise, greenhouses, technological purposes, get steam, dry seeds, dry firewood, get boiled water for livestock. The enterprise receives gas, electricity, heat, fertilizers and provides a closed production cycle. The project pays off by reducing the cost of products produced by the enterprise, since the costs of purchasing gas, electricity, hot water and fertilizers are reduced.
• Additional profit can be used to repay the loan and to develop production. Reduced energy dependence, reduced greenhouse gas emissions, reduced environmental pollution from agricultural waste, and the absence of an unpleasant odor at the enterprise.

The construction of a biogas plant is relevant not only for newly created farms, but also for old ones. After all, old lagoons are often overcrowded, and their repair requires significant funds. While some waste can simply be stored in settling tanks, some waste (such as slaughterhouse waste) requires energy and money to be disposed of. Site requirements. The installation can be located on the site of sedimentation tanks, lagoons or an old landfill. The average size of the site for installation is 40x70 m.

Biogas plant price

Each enterprise is individual, so in each case the financial costs will be calculated by specialists.

Sample Project

We give an example of average costs and income when installing biogas equipment.
Calculation of costs and income using the example of a biogas plant for a distillery. The cost of installation is 1280 thousand euros. All services and works are included. Capacity for grain stillage is 100 tons per day.

The humidity of the separated stillage is 70%. The average payback period for the project is 2-3 years. And with full use of the installation’s capabilities, the payback can be 1.5-1.8 years. The use of opportunities is the addition of coenzymes, the use of heat in greenhouses, and the sale of all produced fertilizers.

Energy costs are one of the main cost items, which significantly affects the cost of production. Treatment plants consume about 50% of energy, and when building a biogas plant, this 50% is saved. The enterprise receives gas, electricity, heat, fertilizers and ensures a closed production cycle.

The project pays off by reducing production costs, since the costs of purchasing gas, electricity, hot water and fertilizers are reduced. Additional profit can be used to repay the loan and to develop production.

Expenses:					Euro.
Reactor Maintenance
Depreciation expenses
Electric generator maintenance
Electricity (for the case where only gas is produced)
Salary (with a reserve we take 2 low-skilled people)
Total costs for the year
Income: 1. Sale/use of gas (or electricity as a derivative of gas) 2. Sale/use of fertilizers 3. Sale of CO2 quotas
	Unit change	Departure at one o'clock.	Output in a year.	Cost Euro.	Total amount euro
Liquid biofertilizers
CO2 quotas
Total profit
Net profit

The material was prepared by Shilova E.P.

The modern world is built on ever-increasing consumption, so mineral and raw material resources are being depleted especially quickly. At the same time, millions of tons of foul-smelling manure accumulate annually on numerous livestock farms, and considerable resources are spent on its disposal. Humans are also keeping up with the production of biological waste. Fortunately, a technology has been developed that allows us to simultaneously solve these problems: using biowaste (primarily manure) as a raw material, producing environmentally friendly renewable fuel - biogas. The use of such innovative technologies has given rise to a new promising industry - bioenergy.

What is biogas

Biogas is a volatile gaseous substance that is colorless and completely odorless. It consists of 50-70 percent methane, up to 30 percent of it is carbon dioxide CO2 and another 1-2 percent are gaseous substances - impurities (when purified from them, the purest biomethane is obtained).

The qualitative physical and chemical characteristics of this substance are close to those of ordinary high-quality natural gas. According to research by scientists, biogas has very high calorific properties: for example, the heat released when burning one cubic meter of this natural fuel is equivalent to the heat from one and a half kilograms of coal.

The release of biogas occurs due to the vital activity of a special type of bacteria - anaerobic, while mesophilic bacteria are activated when the environment is heated to 30-40 degrees Celsius, and thermophilic bacteria multiply at higher temperatures - up to +50 degrees.

Under the influence of their enzymes, organic raw materials decompose with the release of biological gas.

Raw materials for biogas

Not all organic waste is suitable for processing into biogas. For example, manure from poultry and pig farms cannot be used in its pure form, because it has a high level of toxicity. To obtain biogas from them, it is necessary to add diluents to such waste: silage mass, green grass mass, as well as cow manure. The last component is the most suitable raw material for producing environmentally friendly fuel, since cows eat only plant foods. However, it must also be monitored for the content of heavy metal impurities, chemical components, and surfactants, which in principle should not be present in the raw material. A very important point is control over antibiotics and disinfectants. Their presence in manure can prevent the process of decomposition of the raw material mass and the formation of volatile gas.

Additional Information. It is impossible to do without disinfectants completely, because otherwise mold begins to form on the biomass under the influence of high temperatures. You should also monitor and promptly clean the manure from mechanical impurities (nails, bolts, stones, etc.), which can quickly damage biogas equipment. The humidity of the raw materials used to produce biogas must be at least 80-90%.

Mechanism of gas formation

In order for biogas to begin to be released from organic raw materials during airless fermentation (scientifically called anaerobic fermentation), appropriate conditions are required: a sealed container and elevated temperature. If done correctly, the gas produced rises to the top where it is selected for use, and what solids remain is an excellent bio-organic agricultural fertilizer, rich in nitrogen and phosphorus, but free of harmful microorganisms. Temperature conditions are very important for proper and complete processes.

The full cycle of converting manure into environmental fuel ranges from 12 days to a month, it depends on the composition of the raw materials. From one liter of useful reactor volume, about two liters of biogas are produced. If you use more advanced modernized installations, the biofuel production process is accelerated to 3 days, and biogas production increases to 4.5-5 liters.

People began to study and use the technology of producing biofuel from organic natural sources since the end of the 18th century, and in the former USSR the first device for producing biogas was developed back in the 40s of the last century. Nowadays, these technologies are becoming increasingly important and popular.

Advantages and disadvantages of biogas

Biogas as an energy source has undeniable advantages:

• it serves to improve the environmental situation in those areas where it is widely used, since along with reducing the use of polluting fuel, there is a very effective destruction of biowaste and disinfection of wastewater, i.e. biogas equipment acts as a cleaning station;
• the raw materials for the production of this organic fuel are renewable and practically free - as long as animals on farms receive food, they will produce biomass, and, therefore, fuel for biogas plants;
• the acquisition and use of equipment is economically profitable - once purchased, a biogas production plant will no longer require any investments, and it is simply and cheaply maintained; Thus, a biogas plant for use on a farm begins to pay for itself within three years after launch; there is no need to build utilities and energy transmission lines, the costs of launching a biological station are reduced by 20 percent;
• there is no need to install utilities such as power lines and gas pipelines;
• biogas production at the station using local organic raw materials is a waste-free enterprise, as opposed to enterprises using traditional energy sources (gas pipelines, boiler houses, etc.), waste does not pollute the environment and does not require storage space;
• when using biogas, a certain amount of carbon dioxide and sulfur are released into the atmosphere, however, these amounts are minimal compared to the same natural gas and are absorbed by green spaces during respiration, therefore the contribution of bioethanol to the greenhouse effect is minimal;
• Compared to other alternative energy sources, biogas production is always stable; a person can control the activity and productivity of installations for its production (unlike, for example, solar panels), collecting several installations into one or, conversely, splitting them into separate sections to reduce risk accidents;
• in exhaust gases when using biofuels, the content of carbon monoxide is reduced by 25 percent, and nitrogen oxides by 15;
• in addition to manure, you can also use some types of plants to obtain biomass for fuel, for example, sorghum will help improve soil condition;
• When bioethanol is added to gasoline, its octane number increases, and the fuel itself becomes more detonation-resistant, and its auto-ignition temperature decreases significantly.

Biogas– not an ideal fuel, it and the technology for its production are also not without drawbacks:

• the speed of processing organic raw materials in equipment for the production of biogas is a weak point in the technology compared to traditional sources of energy;
• Bioethanol has a lower calorific value than petroleum fuel - it releases 30 percent less energy;
• the process is quite unstable; to maintain it, a large amount of enzymes of a certain quality is required (for example, a change in the diet of cows greatly affects the quality of manure);
• unscrupulous producers of biomass for processing stations can significantly deplete the soil with increased seeding, this disrupts the ecological balance of the territory;
• pipes and containers with biogas may become depressurized, which will lead to a sharp decrease in the quality of biofuel.

Where is biogas used?

First of all, this ecological biofuel is used to meet the household needs of the population, as a replacement for natural gas, for heating and cooking. Enterprises can use biogas to launch a closed production cycle: its use in gas turbines is especially effective. With proper adjustment and complete combination of such a turbine with a biofuel production plant, its cost competes with the cheapest nuclear energy.

The efficiency of biogas use is very easy to calculate. For example, from one unit of cattle you can get up to 40 kilograms of manure, from which one and a half cubic meters of biogas is produced, sufficient to generate 3 kilowatts/hours of electricity.

Having determined the household's electricity needs, it is possible to determine what type of biogas plant to use. With a small number of cows, it is best to produce biogas at home using a simple low-power biogas plant.

If the farm is very large, and it constantly generates a large amount of biowaste, it is beneficial to install an automated industrial-type biogas system.

Note! When designing and setting up, you will need the help of qualified specialists.

Biogas plant design

Any biological installation consists of the following main parts:

• a bioreactor where the biodecomposition of the manure mixture occurs;
• organic fuel supply system;
• unit for stirring biological masses;
• devices for creating and maintaining the required temperature level;
• tanks for placing the resulting biogas in them (gas holders);

• containers for placing the resulting solid fractions there.

This is a complete list of elements for industrial automated installations, while a biogas installation for a private home is much more simply designed.

The bioreactor must be completely sealed, i.e. access of oxygen is unacceptable. This can be a metal container in the form of a cylinder installed on the surface of the soil; former fuel tanks with a capacity of 50 cubic meters are well suited for these purposes. Ready-made dismountable bioreactors are quickly installed/dismantled and easily moved to a new location.

If a small biogas station is planned, then it is advisable to place the reactor underground and make it in the form of a brick or concrete tank, as well as metal or PVC barrels. You can place such a bioenergy reactor indoors, but it is necessary to ensure constant air ventilation.

Bunkers for the preparation of biological raw materials are a necessary element of the system, because before entering the reactor, it must be prepared: crushed into particles up to 0.7 millimeters and soaked in water to bring the moisture content of the raw material to 90 percent.

Raw material supply systems consist of a raw material receiver, a water supply system and a pump for supplying the prepared mass to the reactor.

If the bioreactor is made underground, the container for raw materials is placed on the surface so that the prepared substrate flows into the reactor independently under the influence of gravity. It is also possible to place the raw material receiver at the top of the bunker, in which case it is necessary to use a pump.

The waste outlet hole is located closer to the bottom, opposite the raw material entrance. The receiver for solid fractions is made in the form of a rectangular box, into which an outlet tube leads. When a new portion of the prepared bio-substrate enters the bioreactor, a batch of solid waste of the same volume is fed into the receiver. They are subsequently used on farms as excellent biofertilizers.

The resulting biogas is stored in gas holders, which are usually placed on top of the reactor and have a cone or dome shape. Gas tanks are made of iron and painted with oil paint in several layers (this helps to avoid corrosive destruction). In large industrial bioinstallations, biogas containers are made in the form of separate tanks connected to the reactor.

To give the resulting gas flammable properties, it is necessary to rid it of water vapor. The biofuel is piped through a water tank (hydraulic seal), after which it can be supplied through plastic pipes directly for consumption.

Sometimes you can find special bag-shaped gas holders made of PVC. They are located in close proximity to the installation. As the bags are filled with biogas, they open and their volume increases enough to accept all the produced gas.

For effective biofermentation processes to occur, constant stirring of the substrate is necessary. To prevent the formation of a crust on the surface of the biomass and slow down the fermentation processes, it is necessary to constantly actively mix it. To do this, submersible or inclined stirrers are mounted on the side of the reactor in the form of a mixer for mechanical mixing of the mass. For small stations they are manual, for industrial ones they are automatically controlled.

The temperature necessary for the vital activity of anaerobic bacteria is maintained using automated heating systems (for stationary reactors); they begin heating when the heat drops below normal and automatically turn off when normal temperature is reached. You can also use boiler systems, electric heaters, or install a special heater in the bottom of the container with raw materials. At the same time, it is necessary to reduce heat loss from the bioreactor; to do this, it is wrapped in a layer of glass wool or other thermal insulation is provided, for example, from polystyrene foam.

Do-it-yourself biogas

For private homes, the use of biogas is now very important - from practically free manure you can get gas for domestic needs and heating your home and farm. Your own biogas installation is a guarantee against power outages and rising gas prices, as well as an excellent way to recycle biowaste, as well as unnecessary paper.

For construction for the first time, it is most logical to use simple schemes; such structures will be more reliable and will last longer. In the future, the installation can be supplemented with more complex parts. For a house with an area of ​​50 square meters, a sufficient amount of gas is obtained with a fermentation tank volume of 5 cubic meters. To ensure the constant temperature required for proper fermentation, a heating pipe can be used.

At the first stage of construction, they dig a trench for the bioreactor, the walls of which must be strengthened and sealed with plastic, concrete mixture or polymer rings (preferably they have a solid bottom - they will have to be replaced periodically as they are used).

The second stage consists of installing gas drainage in the form of polymer pipes with numerous holes. During installation, it should be taken into account that the tops of the pipes must exceed the planned filling depth of the reactor. The diameter of the outlet pipes should be no more than 7-8 centimeters.

The next stage is isolation. After this, you can fill the reactor with the prepared substrate, after which it is wrapped in film to increase the pressure.

At the fourth stage, the domes and the outlet pipe are installed, which is placed at the highest point of the dome and connects the reactor to the gas tank. The gas holder can be lined with brick, a stainless steel mesh is mounted on top and covered with plaster.

A hatch is placed in the upper part of the gas holder, which closes hermetically; a gas pipe with a valve for equalizing pressure is removed from it.

Important! The resulting gas must be removed and consumed constantly, since its long-term storage in the free part of the bioreactor can provoke an explosion from high pressure. It is necessary to provide a water seal so that the biogas does not mix with air.

To heat the biomass, you can install a coil coming from the heating system of the house - this is much more economically profitable than using electric heaters. External heating can be provided using steam; this will prevent overheating of raw materials above normal.

In general, a do-it-yourself biogas plant is not such a complex structure, but when arranging it, you need to pay attention to the smallest details in order to avoid fires and destruction.

Additional Information. The construction of even the simplest biological installation must be formalized with the appropriate documents, you must have a technological diagram and equipment installation map, you must obtain approval from the Sanitary and Epidemiological Station, fire and gas services.

Nowadays, the use of alternative energy sources is gaining momentum. Among them, the bioenergy sub-sector is very promising - the production of biogas from organic waste such as manure and silage. Biogas production stations (industrial or small home) can solve the problems of waste disposal, obtaining environmental fuel and heat, as well as high-quality agricultural fertilizers.

Video

One of the problems that has to be solved in agriculture is the disposal of manure and plant waste. And this is a rather serious problem that requires constant attention. Recycling takes not only time and effort, but also considerable amounts. Today there is at least one way to turn this headache into an income source: processing manure into biogas. The technology is based on the natural process of decomposition of manure and plant residues due to the bacteria they contain. The whole task is to create special conditions for the most complete decomposition. These conditions are the absence of oxygen access and optimal temperature (40-50 o C).

Everyone knows how manure is most often disposed of: they put it in heaps, then, after fermentation, they take it out to the fields. In this case, the resulting gas is released into the atmosphere, and 40% of the nitrogen contained in the initial substance and most of the phosphorus also escape there. The resulting fertilizer is far from ideal.

To obtain biogas, it is necessary that the process of decomposition of manure takes place without access to oxygen, in a closed volume. In this case, both nitrogen and phosphorus remain in the residual product, and the gas accumulates in the upper part of the container, from where it can be easily pumped out. There are two sources of profit: gas itself and effective fertilizer. Moreover, the fertilizer is of the highest quality and 99% safe: most of the pathogenic microorganisms and helminth eggs die, and the weed seeds contained in the manure lose their viability. There are even lines for packaging this residue.

The second prerequisite for the process of processing manure into biogas is maintaining an optimal temperature. The bacteria contained in the biomass are inactive at low temperatures. They begin to act at an ambient temperature of +30 o C. Moreover, manure contains two types of bacteria:

Thermophilic plants with temperatures from +43 o C to +52 o C are the most effective: in them, manure is processed for 3 days, and the output from 1 liter of useful bioreactor area is up to 4.5 liters of biogas (this is the maximum output). But maintaining a temperature of +50 o C requires significant energy expenditure, which is not profitable in every climate. Therefore, biogas plants often operate at mesophilic temperatures. In this case, the processing time can be 12-30 days, the yield is approximately 2 liters of biogas per 1 liter of bioreactor volume.

The composition of the gas varies depending on the raw materials and processing conditions, but it is approximately as follows: methane - 50-70%, carbon dioxide - 30-50%, and also contains a small amount of hydrogen sulfide (less than 1%) and very small amounts of ammonia, hydrogen and nitrogen compounds. Depending on the design of the plant, biogas may contain a significant amount of water vapor, which will require drying (otherwise it simply will not burn). What an industrial installation looks like is demonstrated in the video.

This can be said to be an entire gas production plant. But for a private farmstead or small farm such volumes are useless. The simplest biogas plant is easy to make with your own hands. But the question is: “Where should the biogas be sent next?” The heat of combustion of the resulting gas is from 5340 kcal/m3 to 6230 kcal/m3 (6.21 - 7.24 kWh/m3). Therefore, it can be supplied to a gas boiler to generate heat (heating and hot water), or to an electricity generation installation, to a gas stove, etc. This is how Vladimir Rashin, a biogas plant designer, uses manure from his quail farm.

It turns out that if you have at least a decent amount of livestock and poultry, you can fully meet your farm’s needs for heat, gas and electricity. And if you install gas installations on cars, then it will also provide fuel for the fleet. Considering that the share of energy resources in the cost of production is 70-80%, you can only save on a bioreactor, and then earn a lot of money. Below is a screenshot of an economic calculation of the profitability of a biogas plant for a small farm (as of September 2014). The farm cannot be called small, but it is definitely not large either. We apologize for the terminology - this is the author's style.

This is an approximate breakdown of the required costs and possible income Schemes for homemade biogas plants

Schemes of homemade biogas plants

The simplest scheme of a biogas plant is a sealed container - a bioreactor, into which the prepared slurry is poured. Accordingly, there is a hatch for loading manure and a hatch for unloading processed raw materials.

The simplest scheme of a biogas plant without any bells and whistles

The container is not completely filled with the substrate: 10-15% of the volume should remain free to collect gas. A gas outlet pipe is built into the tank lid. Since the resulting gas contains a fairly large amount of water vapor, it will not burn in this form. Therefore, it is necessary to pass it through a water seal to dry it. In this simple device, most of the water vapor will condense, and the gas will burn well. Then it is advisable to clean the gas from non-flammable hydrogen sulfide and only then can it be supplied to a gas holder - a container for collecting gas. And from there it can be distributed to consumers: fed to a boiler or gas oven. Watch the video to see how to make filters for a biogas plant with your own hands.

Large industrial installations are placed on the surface. And this, in principle, is understandable - the volume of land work is too large. But on small farms the bunker bowl is buried in the ground. This, firstly, allows you to reduce the cost of maintaining the required temperature, and secondly, in a private backyard there are already enough all kinds of devices.

The container can be taken ready-made, or made of brick, concrete, etc. in a dug pit. But in this case, you will have to take care of the air tightness and obstruction: the process is anaerobic - without air access, therefore it is necessary to create a layer impermeable to oxygen. The construction turns out to be multi-layered and the manufacture of such a bunker is a long and costly process. Therefore, it is cheaper and easier to bury a ready-made container. Previously, these were necessarily metal barrels, often made of stainless steel. Today, with the advent of PVC containers on the market, you can use them. They are chemically neutral, have low thermal conductivity, long service life, and are several times cheaper than stainless steel.

But the biogas plant described above will have low productivity. To activate the processing process, active mixing of the mass in the hopper is necessary. Otherwise, a crust is formed on the surface or in the thickness of the substrate, which slows down the decomposition process, and less gas is obtained at the outlet. Mixing is carried out in any available way. For example, as demonstrated in the video. In this case, any drive can be made.

There is another way of mixing the layers, but non-mechanical - barbitation: the gas produced under pressure is fed into the lower part of the manure tank. Rising upward, gas bubbles will break the crust. Since the same biogas is supplied, there will be no changes in processing conditions. Also, this gas cannot be considered a consumption - it will again end up in the gas tank.

As mentioned above, high temperatures are required for good performance. In order not to spend too much money on maintaining this temperature, it is necessary to take care of the insulation. What type of heat insulator to choose, of course, is your business, but today the most optimal one is polystyrene foam. It is not afraid of water, is not affected by fungi and rodents, has a long service life and excellent thermal insulation performance.

The shape of the bioreactor can be different, but the most common is cylindrical. It is not ideal in terms of the complexity of mixing the substrate, but is used more often because people have accumulated a lot of experience in building such containers. And if such a cylinder is divided by a partition, then they can be used as two separate tanks in which the process is shifted in time. At the same time, a heating element can be built into the partition, thus solving the problem of maintaining the temperature in two chambers at once.

In the simplest version, homemade biogas plants are a rectangular pit, the walls of which are made of concrete, and for tightness they are treated with a layer of fiberglass and polyester resin. This container is equipped with a lid. It is extremely inconvenient to use: heating, mixing and removal of the fermented mass is difficult to implement, and it is impossible to achieve complete processing and high efficiency.

The situation is a little better with trench biogas manure processing plants. They have beveled edges, making it easier to load fresh manure. If you make the bottom at a slope, then the fermented mass will shift to one side by gravity and it will be easier to select it. In such installations, it is necessary to provide thermal insulation not only for the walls, but also for the lid. It is not difficult to implement such a biogas plant with your own hands. But complete processing and the maximum amount of gas cannot be achieved in it. Even with heating.

The basic technical issues have been dealt with, and you now know several ways to build a plant for producing biogas from manure. There are still technological nuances.

What can be recycled and how to achieve good results

The manure of any animal contains the organisms necessary for its processing. It has been discovered that more than a thousand different microorganisms are involved in the fermentation process and gas production. Methane-forming substances play the most important role. It is also believed that all these microorganisms are found in optimal proportions in cattle manure. In any case, when processing this type of waste in combination with plant matter, the largest amount of biogas is released. The table shows average data for the most common types of agricultural waste. Please note that this amount of gas output can be obtained under ideal conditions.

For good productivity it is necessary to maintain a certain substrate humidity: 85-90%. But water must be used that does not contain foreign chemicals. Solvents, antibiotics, detergents, etc. have a negative effect on processes. Also, for the process to proceed normally, the liquid should not contain large fragments. Maximum fragment sizes: 1*2 cm, smaller ones are better. Therefore, if you plan to add herbal ingredients, you need to grind them.

It is important for normal processing in the substrate to maintain an optimal pH level: within 6.7-7.6. Usually the environment has normal acidity, and only occasionally acid-forming bacteria develop faster than methane-forming bacteria. Then the environment becomes acidic, gas production decreases. To achieve the optimal value, add regular lime or soda to the substrate.

Now a little about the time it takes to process manure. In general, the time depends on the conditions created, but the first gas can begin to flow already on the third day after the start of fermentation. The most active gas formation occurs when manure decomposes by 30-33%. To be able to navigate in time, let's say that after two weeks the substrate decomposes by 20-25%. That is, optimally the processing should last a month. In this case, the fertilizer is of the highest quality.

Calculation of bin volume for processing

For small farms, the optimal setting is permanent action - this is when fresh manure is supplied in small portions daily and removed in the same portions. In order for the process not to be disturbed, the share of the daily load should not exceed 5% of the processed volume.

Home-made installations for the processing of manure into biogas are not the pinnacle of perfection, but they are quite effective

Based on this, you can easily determine the required tank volume for a homemade biogas plant. You need to multiply the daily volume of manure from your farm (already diluted with a moisture content of 85-90%) by 20 (this is for mesophilic temperatures, for thermophilic temperatures you will have to multiply by 30). Another 15-20% must be added to the figure obtained - free space for collecting biogas under the dome. You know the main parameter. All further costs and parameters of the system depend on which scheme of the biogas plant is chosen for implementation and how you will do everything. It is quite possible to get by with improvised materials, or you can order a turnkey installation. Factory developments will cost from 1.5 million euros, installations from the Kulibins will be cheaper.

Legal registration

The installation will have to be coordinated with the SES, gas inspectorate and firefighters. You will need:

• Technological diagram of the installation.
• Layout plan for equipment and components with reference to the installation itself, the installation site of the thermal unit, the location of pipelines and power lines, and the connection of the pump. The diagram should indicate the lightning rod and access roads.
• If the unit is to be located indoors, a ventilation plan will also be required, which will ensure at least eight exchanges of the total air in the room.

As we see, we cannot do without bureaucracy here.

Finally, a little about the performance of the installation. On average, a biogas plant produces a volume of gas per day that is twice the useful volume of the reservoir. That is, 40 m 3 of slurry will produce 80 m 3 of gas per day. Approximately 30% will be spent on ensuring the process itself (the main expense item is heating). Those. at the output you will receive 56 m 3 of biogas per day. To cover the needs of a family of three and to heat a medium-sized house, according to statistics, 10 m 3 is required. In net balance you have 46 m3 per day. And this is with a small installation.

Results

By investing some money in the construction of a biogas plant (do it yourself or on a turnkey basis), you will not only provide for your own needs and needs for heat and gas, but also be able to sell gas, as well as high-quality fertilizers resulting from processing.

A biogas plant is a special unit that allows you to process agricultural and food industry waste into biological fertilizers and biological gas.

The use of such an installation allows you to quickly get rid of various types of manure (including bird droppings), process plant residues (overwintered silage, tops of food crops, etc.) and efficiently dispose of organic waste from slaughterhouses and poultry farms. The time it takes to obtain biological waste and gas depends on the density of the processed materials and their quantity.

Such installations are most widespread in countries such as Germany and Holland. In recent years, a huge number of Chinese farms and food production plants have also been equipped with biogas plants of their own production.

Biogas plant device. It should be said that biogas plants have a very simple design. Modern models of such installations have a sufficient degree of automation and require minimal human control. So, a modern biogas plant consists of:

• A transition container into which raw materials enter at the very beginning of processing for heating.
• Mixers, for grinding large particles of grass and manure.
• A gas container (gas holder), in which the resulting gas is stored, is necessary to maintain reserves and pressure in the system.
• The bioreactor is the most important part of the biogas plant, in which the fermentation of raw materials occurs and gas is produced.
• Gas system, a set of pipes and hoses for supplying and discharging the resulting gas.
• Separators sort processed raw materials into solid and liquid fertilizers.
• Pumps for pumping raw materials and water.
• Devices for measuring and monitoring the pressure in the reactor and the temperature of the heating liquid.
• A cogeneration station serves to distribute the resulting gas.
• Emergency burners for bleeding excess gas from the reactor and gas tank are necessary to maintain a given pressure.

At first glance, it seems that the design of a biogas plant is too complex and confusing, and it includes expensive units and components. However, in reality this is far from the case. Most of the components have menacing names, but in fact they are based on everyday objects. In any case, similar designs have been used by people all over the world for many years, which means that the principle of operation of the installation can be understood without any difficulty.

The principle of operation of a biogas plant. Before moving on to a detailed examination of the operating principle of a biogas plant, it should be said that this device appeared solely due to the processes of fermentation and decomposition. As you know, any organic substance (over time and under appropriate conditions) breaks down into simple chemical substances, one of which is biogas. It is on the principles of fermentation and decay that any biogas plant is created, and additional components and assemblies have auxiliary or controlling functions.

Stages of operation of a biogas plant.

• 1. Delivery of processed products and waste to the plant. If the waste is liquid, it is advisable to deliver it to the reactor using specialized pumps. More solid waste can be delivered to the reactor manually or by means of a conveyor belt. In some cases, it is advisable to heat the waste in order to increase its rate of fermentation and decay in the bioreactor. To heat the waste, a transition tank is used, in which the processed products are brought to the required temperature.
• 2. Processing in a reactor. After the transition tank, the prepared (and heated!) waste enters the reactor. A high-quality bioreactor is a hermetic structure made of especially strong steel or concrete with a special anti-acid coating. Without fail, the reactor must have ideal thermal and gas insulation. Even the slightest entry of air or decrease in temperature will stop the process of fermentation and decay. The reactor is heated using hot water tubes. The system is autonomous. The water is heated using the produced biogas. The reactor operates without access to oxygen, in a completely closed environment. Several times a day, using a pump, you can add new portions of the processed substance to it. The optimal temperature regime for the reactor is about 40 degrees Celsius. If the temperature is lower, the fermentation process will slow down significantly. If you increase the temperature, rapid evaporation of water will occur, which will not allow the waste to completely disintegrate. In order to speed up the fermentation process, a special mixer is used. This device mixes the substance in the reactor after a certain period of time.
• 3. Output of the finished product. After a certain time (from several hours to several days), the first results of fermentation appear. These are biogas and biological fertilizers. As a result, the resulting biogas ends up in a gas holder (gas storage tank). The gas pressure in the gas tanks is regulated using valves. In case of excessive pressure, emergency burners will be activated, which will simply burn off excess gas, thereby stabilizing the pressure. The resulting biogas needs to be dried. Only after this can it be used like ordinary natural gas. Separately, it should be said that to maintain the operation of a biogas plant, about 15% of the gas produced is required. In turn, biological fertilizers end up in a specially prepared tank with a separator. There is a division into solid (vermicompost) and liquid fertilizers. Vermicompost makes up only about 5% of the total amount of fertilizer received. Actually, fertilizers can immediately be used for their intended purpose. They do not require additional processing. Moreover, in Europe there are entire production lines that package the resulting biological fertilizers in plastic containers. Trading such fertilizers is a fairly profitable business. The operation of the biogas plant is continuous. To put it simply, new portions of processed material are constantly entering the reactor, and gas and biological fertilizers are also constantly entering the gas holder and separator tank.

Operation and installation of a biogas plant. Installation of a biogas plant is strictly individual. You can’t just bring and assemble all the components. It is necessary to carry out a whole series of preparatory work, dig several large pits, and carry out high-quality insulation of the reactor. It is necessary to take into account all the individual characteristics of a farm or enterprise, and make the biogas plant relevant for specific tasks. One person can monitor the biogas plant, since the processing process is fully automated. Operation of the installation does not require large expenses. With good care and timely maintenance, the annual cost of maintaining such an installation will not exceed 5% of its original cost.

Advantages of using a biogas plant. A biogas plant is a truly magical device that allows you to obtain truly necessary things from industrial waste and manure. In particular, you can get:

• Biogas
• Biological fertilizers
• Electrical and thermal energy
• Fuel for cars.

In order to convert biogas into electrical and thermal energy, it is necessary to equip the installation with additional units. This increases the cost of the installation itself, but allows you to achieve significant autonomy from utilities and significantly reduce bills. If the car is equipped with gas equipment, then it can be refueled with gas produced by a biogas plant. Naturally, biological gas will require additional purification, which will filter out carbon dioxide. After this, the car will be able to drive on gas produced by the biogas plant. This helps to save significantly on the purchase of gasoline, which is very profitable at current fuel prices.

Who needs a biogas plant?

As mentioned above, a biogas plant is a technically complex device that requires professional installation and timely maintenance.

Therefore, a small farmer whose farm consists of a dozen cows and several hectares of land definitely does not need such equipment. He simply does not have enough manure and other fertilizers to make the biogas plant work around the clock and generate significant income. And it’s a completely different matter if we talk about a large farm, poultry farm or meat processing plant. These industries generate hundreds of kilograms of various waste every day, which simply has nowhere to go. For them, purchasing a biogas plant is almost the only way to solve the problem of waste disposal, and at the same time receive free gas, electricity and biological fertilizers.

As practice shows, such biogas systems begin to pay for themselves within 2 years after installation. Considering that the average service life of an installation is 25 years, it is not difficult to calculate the profit that such equipment will bring.