Mini biogas plant. Do-it-yourself biogas plant: Internet myths and rural reality. The principle of obtaining biogas

The issue of obtaining methane is of interest to those owners of private farms who breed poultry or pigs, and also keep cattle. As a rule, such farms produce a significant amount of organic animal waste, and it is they who can bring considerable benefits, becoming a source of cheap fuel. The purpose of this material is to tell you how to get biogas at home using these very wastes.

General information about biogas

Derived from various manure and bird droppings, domestic biogas mostly consists of methane. There it is from 50 to 80%, depending on whose waste products were used for production. The same methane that burns in our stoves and boilers, and for which we sometimes pay a lot of money according to the meter readings.

To give an idea of ​​the amount of fuel that can theoretically be obtained by keeping animals at home or in the country, we present a table with data on the yield of biogas and the content of pure methane in it:

As can be seen from the table, for the efficient production of gas from cow dung and silage waste, quite a large amount of raw materials will be needed. It is more profitable to extract fuel from pig manure and turkey droppings.

The rest of the substances (25-45%) that make up home biogas are carbon dioxide (up to 43%) and hydrogen sulfide (1%). Also in the composition of the fuel there is nitrogen, ammonia and oxygen, but in small quantities. By the way, it is thanks to the release of hydrogen sulfide and ammonia that the dunghill emits such a familiar “pleasant” smell. As for the energy content, 1 m3 of methane can theoretically release up to 25 MJ (6.95 kW) of thermal energy during combustion. The specific heat of combustion of biogas depends on the proportion of methane in its composition.

For reference. In practice, it has been verified that for heating an insulated house located in the middle lane, about 45 m3 of biological fuel per 1 m2 of area per heating season is required.

By nature, it is arranged in such a way that biogas from manure is formed spontaneously and regardless of whether we want to receive it or not. The dung heap rots within a year - one and a half, just being in the open air and even at sub-zero temperatures. All this time, it emits biogas, but only in small quantities, since the process is extended in time. The reason is hundreds of species of microorganisms found in animal excrement. That is, nothing is needed to start gassing, it will occur on its own. But to optimize the process and speed it up, special equipment will be required, which will be discussed later.

Biogas technology

The essence of efficient production is the acceleration of the natural process of decomposition of organic raw materials. To do this, the bacteria in it need to create the best conditions for the reproduction and processing of waste. And the first condition is to place the raw material in a closed container - a reactor, otherwise - a biogas generator. The waste is crushed and mixed in the reactor with the calculated amount of pure water until the initial substrate is obtained.

Note. Clean water is necessary so that substances that adversely affect the vital activity of bacteria do not get into the substrate. As a result, the fermentation process can be greatly slowed down.

The industrial plant for the production of biogas is equipped with substrate heating, mixing facilities and control over the acidity of the medium. Agitation is performed to remove the hard crust from the surface, which occurs during fermentation and interferes with the release of biogas. The duration of the technological process is at least 15 days, during which time the degree of decomposition reaches 25%. It is believed that the maximum fuel yield occurs up to 33% of biomass decomposition.

The technology provides for daily renewal of the substrate, thus ensuring intensive production of gas from manure, in industrial installations it amounts to hundreds of cubic meters per day. Part of the spent mass in the amount of about 5% of the total volume is removed from the reactor, and the same amount of fresh biological raw materials is loaded in its place. The waste material is used as organic fertilizer for the fields.

Scheme of a biogas plant

By obtaining biogas at home, it is impossible to create such favorable conditions for microorganisms as in industrial production. And first of all, this statement concerns the organization of heating the generator. As you know, this requires energy, which leads to a significant increase in the cost of fuel. It is quite possible to control compliance with the slightly alkaline environment inherent in the fermentation process. But how to correct it in case of deviations? Again costs.

Owners of private households who want to produce biogas with their own hands are advised to make a reactor of a simple design from available materials, and then upgrade it to the best of their ability. What need to do:

• a hermetically sealed container with a volume of at least 1 m3. Different tanks and barrels of small sizes are also suitable, but little fuel will be released from them due to an insufficient amount of raw materials. Such volumes of production will not suit you;
• organizing the production of biogas at home, you are unlikely to start heating the tank, but it is necessary to insulate it. Another option is to bury the reactor in the ground by thermally insulating the upper part;
• install a manual stirrer of any design in the reactor, pulling the handle through the top cover. The handle passage assembly must be airtight;
• provide nozzles for supplying and unloading the substrate, as well as for sampling biogas.

Below is a diagram of a biogas plant located below ground level:

1 - fuel generator (tank made of metal, plastic or concrete); 2 - bunker for pouring the substrate; 3 - technical hatch; 4 - a vessel that plays the role of a water seal; 5 - branch pipe for unloading waste; 6 – biogas sampling pipe.

How to get biogas at home?

The first operation is the grinding of waste to a fraction whose size is not more than 10 mm. So it is much easier to prepare the substrate, and it will be easier for the bacteria to process the raw materials. The resulting mass is thoroughly mixed with water, its amount is about 0.7 l per 1 kg of organic matter. As mentioned above, only clean water should be used. Then the substrate is filled with a do-it-yourself biogas plant, after which the reactor is hermetically sealed.

Several times during the day you need to visit the container to mix the contents. On the 5th day, you can check the presence of gas, and if it appears, periodically pump it out with a compressor into a cylinder. If this is not done in time, then the pressure inside the reactor will increase and fermentation will slow down, or even stop altogether. After 15 days, it is necessary to unload part of the substrate and add the same amount of new. Details can be found by watching the video:

Conclusion

It is likely that a simple biogas plant will not meet all your needs. But, given the current cost of energy resources, this will already be a considerable help in the household, because you do not have to pay for raw materials. Over time, closely engaged in production, you will be able to catch all the features and make the necessary improvements to the installation.

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

What it is

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 the 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. Processed biomass is an excellent fertilizer that is removed from the reactor to enrich the fields.

Do-it-yourself biogas production at home is possible, provided that you live in a village and you have access to animal waste. It is a good fuel option for livestock farms and agricultural businesses.

The advantage of biogas is that it reduces methane emissions and provides a source of alternative energy. 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. As raw materials are used:

• wastewater;
• straw;
• grass;
• river silt.

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

Use cases

The processing of 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.

With the help of a bioreactor, you can create your own energy base to provide a private home or agricultural production.

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

Biofuel efficiency

Biogas from litter and manure is colorless and odorless. It gives as much heat as natural gas. One cubic meter of biogas provides as much 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, manure loses its properties as a fertilizer. Timely processed waste will bring much more benefits to the farm.

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

How to build a biomaterial reactor

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

If there is little biomass, instead of a concrete container, you can take an iron, 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, it will turn out a little. 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 spent material. There must be a hole in the top of the tank through which the 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 the timely removal of gases, which will prevent the explosion of the system.

Reactor for a large farm

A simple bioreactor scheme 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 amounts of fuel. It is best to involve special firms involved in the development of the project and installation of the system.

Industrial complexes consist of:

• Intermediate storage tanks;
• mixer plant;
• A small CHP plant that provides energy for heating buildings and greenhouses, as well as electricity;
• Tanks for fermented manure used as fertilizer.

The most effective option is the construction of one complex for several neighboring farms. The more biomaterial is processed, the more energy is obtained as a result.

Before receiving biogas, industrial installations must be coordinated with the sanitary and epidemiological station, fire and gas inspection. They are documented, there are special rules for the location of all elements.

How to calculate the reactor volume

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

Manure is best diluted with water before being sent to the reactor. 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 biomass fermentation, it is best to heat the mixture. In the southern regions, the air temperature contributes to the start of fermentation. If you live in the north or in the middle lane, you can connect additional heating elements.

To start the process, a temperature of 38 degrees is needed. There are several ways to provide it:

• Coil under the reactor, connected to the heating system;
• Heating elements inside the tank;
• Direct heating of the tank with electric heaters.

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 turn off automatically when the temperature reaches the desired value. Such systems are installed in water-heating boilers, they can be bought at gas equipment stores.

If you provide heating to 30-40 degrees, then it will take 12-30 days to process. 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 a high temperature. They are comparable to the amount of fuel received, so the system becomes inefficient.

Another way to activate anaerobic bacteria is biomass mixing. You can independently install the shafts in the boiler and bring 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.

Proper gas venting

Biogas from manure is removed through the top cover of the reactor. During fermentation, it must be tightly closed. Usually a water seal is used. It controls the pressure in the system, with an increase in the cover rises, the release valve is activated. A weight is used as a counterweight. At the outlet, the gas is cleaned with water and flows further through the pipes. Purification with water is necessary to remove water vapor from the gas, otherwise it will not burn.

Before biogas can be converted into energy, it must be stored. It should be stored in a gas holder:

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

Another option for making a gas tank is to use a PVC bag. This elastic material stretches as the bag fills up. If necessary, it can store a large amount of biogas.

Underground Biofuel Plant

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

On both sides of the container, holes are made 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. An inlet with a diameter of 25-30 cm is best located in the upper part.

From above, the installation is closed with brickwork and a gas holder is installed to receive biogas. At the outlet of the tank, you need to make a valve to regulate the pressure.

The biogas plant can be buried in the yard of a private house and connected to sewage and livestock waste. Processing reactors can fully cover the needs of the family in electricity and heating. An additional plus in obtaining fertilizer for the garden.

A do-it-yourself bioreactor is a way to get energy from pasture material and make money from manure. It reduces farm energy costs and increases profitability. You can make it yourself or have it installed. The price for it depends on the volume, starts from 7000 rubles.

Tools and materials:
-Plastic capacity 750 liters;
-Plastic capacity 500 liters;
- Sanitary pipes and adapters;
- Cement for PVC pipes;
-Epoxy adhesive;
-Knife;
-Hacksaw;
-Hammer;
- Open-end wrenches;
-Gas fittings (detailed in step 7);

The next step the wizard had to make a more complete installation. Let's consider what it is.
-Installation consists of a storage tank in which organic material is stored, and microorganisms, processing it, emit gas.
-The resulting gas is collected in a reservoir known as a gas collector. In the floating type model, this tank floats in suspension and moves up and down depending on the amount of gas stored in it.
- The guide tube helps the gas collector tank move up and down inside the storage tank.
-Waste is fed through a supply pipe inside the storage tank.
-Fully recycled slurry flows down through the outlet pipe. It can be harvested, diluted and used as plant fertilizer.
- From the gas collector, gas is supplied through a pipe to consumption devices (gas stoves, water heaters, generators)

Step two: choose a container
To choose a container, you need to consider how much waste can be collected per day. According to the master, there is a rule where 5 kg of waste needs a capacity of 1000 liters. The master has about 3.5 - 4 kg. So the capacity is needed 700-800 liters. As a result, the master acquired a capacity of 750 liters.
Installation with a floating type of gas collector, which means that you need to choose such a capacity that gas losses are minimal. For these purposes, a 500 liter tank came up. This 500 liter container will move inside the 750 liter one. The distance between the walls of the two containers is about 5 cm on each side. Containers must be chosen that will be resistant to sunlight and aggressive environments.

Biogas plants. Biogas production

Complete stainless steel plants for biogas production.

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

The German company designs and manufactures complete biogas plants and sells them all over the world. More than 300 biogas plants have been built, launched and are successfully operating in Germany, France, the Netherlands, Greece, Great Britain, Sweden, Spain, Luxembourg, Czech Republic, Lithuania, USA, Japan and Cyprus. The proposed installations are not experimental, but working, tested and reliable German equipment, certified according to ISO and manufactured as a set at our own factory.

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

Biogas is a gas composed 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 the enterprise generates 1 ton of such “bio-waste” per day, then 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 manure processing equipment 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 pulling 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 plants is large agro-industrial complexes, cattle farms, poultry farms, fish factories, bakeries, food processing plants, meat processing plants, distilleries, breweries, dairies, crop plants, sugar factories, starch factories, enterprises for yeast production, and not only as an alternative source of energy, but also as an effective method of manure (dung) disposal and the production of cheap fertilizer, both for own needs and for sale on the market. The biogas plant produces biogas and biofertilizers from organic waste from agriculture and the food industry through oxygen-free fermentation, which provides the most active cleaning system. Can be used as raw materials: cattle manure, pig manure, poultry manure, slaughterhouse waste (blood, fat, intestines, bones), plant waste, silage, rotten grain, sewage, fats, biowaste, food industry waste, garden waste, malt sludge , pomace, distillery stillage, beet pulp, technical glycerin (from biodiesel production). Most 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.

All of the above is produced at zero cost. After all, manure is free, and the installation itself consumes only 10-15% of energy. For the operation of a powerful installation, one person is enough 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 trucks or pumped to the biogas plant. First, the coenzymes are poured out (ground), homogenized and mixed with manure (litter). Homogenization is most often carried out at 70°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, fully sealed vessel. This design is thermally insulated, because the temperature inside the tank must be fixed for microorganisms. Inside the reactor 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 the necessary nutrients. Fresh feed should be fed into the reactor in small portions several times a day. The average time of hydraulic settling inside the reactor (depending on substrates) is 20-40 days. During this time, organic substances within the biomass are metabolized (transformed) by microorganisms. At the outlet of the plant, two products are formed: biogas and substrate (composted and liquid).

The biogas is stored in a gas storage tank, where 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 in its origin.

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

This employee controls with a simple computer and also works on a tractor to feed the biomass. After 2 weeks of training, a person without special skills can work on the unit, i.e. with secondary or secondary special education.

BENEFITS

• Biogas.
• Own bioenergy station.
• Proper disposal of organic waste. Waste to 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 manufactured by the enterprise, as the cost of buying gas, electricity, hot water and fertilizers is reduced.
• Additional profit can be used to repay the loan and to develop production. Reduction of energy dependence, reduction of greenhouse gas emissions, reduction of environmental pollution by agricultural waste, absence of an unpleasant smell at the enterprise.

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

Biogas plant price

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

Project example

We give an example of average costs and revenues for the installation of biogas equipment.
Calculation of costs and revenues on the example of a biogas plant for a distillery. The installation cost is 1280 thousand euros. All services and works included. Productivity on a grain bard is 100 tons a day.

Humidity of the separated bard is 70%. The average payback period of 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, the sale of all fertilizers produced.

Energy costs are one of the main cost items that significantly affect the cost of production. Wastewater 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 provides a closed production cycle.

The project pays off by reducing the cost of production, as the cost of buying gas, electricity, hot water and fertilizers is reduced. Additional profit can be used to repay the loan and to develop production.

The material was prepared by Shilova E.P.

Owners of private houses located in regions with limited access to traditional fuels should definitely pay 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 yourself.

The mechanism of action of biogas plants

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

In the reactor, under the influence of anaerobic bacteria, the biomass is rapidly decomposed. During the fermentation of organic raw materials, biogas is released. Approximately 70% of the composition of such a gas is methane, the rest is carbon dioxide.

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

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

Biogas plants on a silo. 1 Silos. 2 Biomass loading system. 3 Reactor. 4 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 about 1.5 m3 of biogas. The daily manure of 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 gives about the same amount of thermal energy as 3.5 kg of firewood, 1-2 kg of coal, 9-10 kWh of electricity.

The simplest biogas mixture recipe includes the following components:

• cow dung - about 1500 kg;
• rotted leaves or other organic waste - 3500 kg;
• water - 65-75% of the total mass of the previous components. Pre-heat the water to about 35 degrees.

This amount of biomass will be enough to produce biogas for half a year of operation with moderate consumption. On average, biogas begins to be released within 1.5-2 weeks after loading the mixture into the plant.

Gas can be used to heat the house and a variety of household and household buildings.

Construction of a typical biogas plant

biogas plant

The main components of a complete biogas system are:

• reactor;
• humus supply system;
• agitators;
• biomass;
• gasholder;
• separator;
• protective part.

A domestic installation will have a somewhat simplified design, however, for completeness of perception, 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 hermetic container, on top of which a dome is installed, usually having a spherical shape.

Currently, the most popular are the collapsible design reactors made using innovative technologies. Such a reactor can be easily assembled with your own hands with minimal time. If necessary, it is just as easy to disassemble and transport to another place.

Steel is convenient in that you can easily create holes in it for connecting 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 waste receiving bin, a water inlet pipe and a screw pump designed to send the humus to the reactor.

A front loader is used to load the dry component into the bunker. At home, this task can be done without a loader, using various improvised means, for example, shovels.

In the bunker, 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.

Agitators

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 in order to achieve the most uniform fermentation process of the mixture that the design of a typical biogas plant includes agitators 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.

Inclined mixers are mounted on the side surfaces of the reactor. An electric motor is responsible for the rotation of the screw in the fermenter.

Automated heating system

For successful production of biogas, the temperature inside the system must be maintained at +35-+40 degrees. For this, automated heating systems are included in the design.

The source of heat in this case is a hot water boiler, in some 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 a variety of adverse natural phenomena.

gas holder

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

For the manufacture of gas-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 the spent 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.

Press screw separator

The drained humus is sent to the shipping compartment. The system sends the liquid part back to the receiving chamber. Here, the liquid is applied to moisten the new feedstock.

The simplest do-it-yourself biogas plant

Biogas plant for home

A domestic biogas plant will have a somewhat simplified design, but its manufacture should be approached with the utmost 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 the most difficult part of the manufacture of the system under consideration 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 solid-bottomed polymer rings. Such devices provide 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. Equip a gas drainage system. This saves you the hassle of buying and installing agitators, which saves time and money on assembling the plant.

The simplest version of the gas drainage system is vertically fixed PVC sewer pipes with many holes in the body.

Choose 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 foil insulation. Thanks to the film, conditions will be created for the accumulation of biogas under the dome under conditions of slight overpressure.

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

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

Procedure and conditions for the successful use of a biogas plant

Average specific yield of biogas

Thus, it is not difficult to assemble a simple biogas plant on your own. 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 kinds of solvents, antibacterial drugs and other similar substances.

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

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

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

Successful work!

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

Video - DIY biogas plant

svoimi-rykami.ru

Biogas plant on your own

The article on biogas production presented the theoretical foundations 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. In this article, practical implementations of biogas plants will be given, with a description of some improvised designs.

As energy prices are rising and many livestock and small farm owners have problems with waste disposal, biogas industrial complexes and small biogas plants for a private home have come on the market. Using search engines, the Internet user can easily find an affordable turnkey solution to meet the needs of the biogas plant and its price, get in touch with equipment suppliers and agree on the construction of a biogas generator at home or on the farm.

Biogas industrial complex

Bioreactor - the basis of a biogas plant

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

The collected biogas exerts pressure on the cylinder, causing it to rise above the tank. Thus, the bell also performs the function of a gas tank - a temporary storage of the resulting gas.

Floating Dome Bioreactor

The disadvantage of the bell design of a biogas reactor is the impossibility of mixing the substrate and heating it during the cold periods of the year. Also a negative factor is a strong smell, 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 a hot climate.

Another example of a floating dome bioreactor

In order to prevent environmental pollution and eliminate unpleasant odors, the reactors of biogas plants for home and large industries have a fixed dome design. The shape of the structure in the process of gas formation does not matter much, 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 nozzles for adding new portions of biomass and removing the spent substrate.

A variation of the fixed dome bioreactor

Main types of biogas plants

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

• Portion, with a single load of the entire biomass, and with subsequent full unloading after the processing of raw materials. The main disadvantage of this type of bioreactors is the uneven release of gas during the processing of the substrate;
• continuous loading and unloading of raw materials, due to which a uniform release of biogas is achieved. Due to the design of the bioreactor, during loading and unloading, biogas production does not stop and there are no leaks, since the nozzles through which the addition and removal of biomass is carried out are made in the form of a water seal that prevents gas from escaping.

Batch bioreactor example

Batch biogas reactors can be of any design that prevents gas leakage. So, for example, at one time in Australia, channel methanetanks with an elastic inflatable roof were popular, where a slight overpressure inside the bioreactor inflated a bubble of durable polypropylene. Upon reaching a certain pressure level inside the bioreactor, the compressor was turned on, pumping out the generated biogas.

Channel bioreactors with flexible gas holder

The type of fermentation in this biogas plant can be mesophilic (with weak 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 the absence of the need for an intermediate receiver, but the big disadvantage is the vulnerability of the elastic dome to mechanical damage.

Large channel bioreactor with flexible gas tank

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

Dry-type bioreactors look like a sealed garage with tightly closing doors. The biomass is loaded into the reactor using a front loader and remains in this state until the completion of the complete gas generation cycle (about half a year), without the need to add the substrate and mix it.

Batch bioreactor loaded through a hermetically sealed door

DIY biogas plant

It should be noted that in most bioreactors, as a rule, only the gas generation 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, due to which the level of biomass in them is slightly higher than inside the tank.

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

These designs of home-made bioreactors are popular among folk craftsmen who independently make biogas plants with their own hands for the home, allowing reusable manual loading and unloading of the substrate. In the manufacture of bioreactors with their own hands, many craftsmen experiment with completely sealed containers, using several rubber chambers from the tires of the wheels of large vehicles as a gas holder.

Drawing of a gas tank made from tractor chambers

In the video below, an enthusiast of homemade biogas production, using the example of barrels filled with bird droppings, proves the possibility of actually obtaining combustible gas at home, processing poultry waste into useful fertilizer. The only thing that can be added to the design described in this video is that you need to put 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 the owners, who have to remove manure every day, do not need this theory, because they know the amount and mass of the future substrate through their own practice. 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 of obtaining the amount of manure from some animals with an approximate calculation of the biogas yield

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

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

Construction of a masonry bioreactor

In industrial biogas plants, electronic control systems and various reagents are used to correct the chemical composition of the substrate and its acidity level, and special substances are added to the biomass - enzymes and vitamins that stimulate the reproduction and vital activity of microorganisms inside the bioreactor. In the process of development of microbiology, more and more resistant and effective strains of bacteria methanogens 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 and cleaning biogas

The constant production of gas 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 the instability of the overpressure in the bioreactor can lead to the extinction of the flame, followed by the release of poisonous gas. The use of such a primitive biogas plant connected to a stove is categorically unacceptable because of the possibility of poisoning with toxic components of raw biogas.

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

Therefore, almost any scheme of a biogas plant 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. The tank for temporary storage of biogas can be made of chambers from tires, from which the gas is pumped 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 to store and transport biogas.

As an alternative to the mandatory use of a gas tank, an improved floating dome bioreactor can be perceived. The improvement consists in the addition of a concentric baffle which forms a water pocket that acts like a water seal and prevents the biomass from coming into contact with air. The pressure inside the floating dome will depend on its weight. By passing the gas through the purification system and reducer, it can be used in a household stove, periodically bled from the bioreactor.

Bioreactor with floating dome and water pocket

Grinding and mixing of the substrate in the bioreactor

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

1. mechanical agitators driven by an electric motor or manually;
2. circulating mixing with a pump or propeller pumping the substrate inside the bioreactor;
3. bubbling mixing by blowing the already existing biogas into the liquid biomass. 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 carried out 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 has a mechanical agitator

Substrate heating in mesophilic and thermophilic biogas plants

The optimal temperature for gas formation is the temperature of the substrate in the range of 35-50ºC. To maintain this temperature, various heating systems can be installed in the bioreactor - water, steam, electric. Temperature control should be carried out using a thermal switch or thermocouples connected to the 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 inside its biomass will burn. The burnt substrate will reduce heat transfer and the quality of heating, 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 of the bioreactor

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

Insulation of the bioreactor with thermal insulation material

Practical experiences that are inevitable when building biogas plants with your own hands

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

Therefore, many novice masters follow the path of independent experiments in obtaining biogas, starting with small containers, determining how much gas from the available raw materials is produced by their small experimental biogas plant. Component prices, methane output and the future costs of building a complete working biogas plant will determine its viability and feasibility.

In the video above, the master demonstrates the capabilities of his biogas plant, noting how much biogas will be produced in one day. In his case, when pumping eight atmospheres into the compressor receiver, the volume of the resulting gas after recalculations, taking into account the volume of the tank 24 l, will be about 0.2 m².

This amount of biogas obtained from a 200 liter barrel is not significant, but, as shown in the following video of this wizard, this amount of gas is enough for an hour of burning one stove burner (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 obtaining biogas and biologically pure fertilizers by processing organic waste in a biogas plant. It must be borne in mind that the value of organic fertilizers may exceed the cost of the resulting gas, and then biogas will become a useful by-product of the process of making quality fertilizers. Another useful property of organic raw materials is the ability to store them for a certain period for use at the right time.

infoelectric.ru

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

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

Along with solar and wind power plants, installations have appeared for obtaining gaseous fuels called biogas from organic waste.

A remarkable feature of this technology is its simplicity: anyone can implement it on a small scale. So, do-it-yourself biogas - that's what the conversation will be about.

If we owe the appearance of solar panels and wind turbines 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.

As the name suggests, the main component of biogas 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 a natural microflora that lives in the intestines of cattle and decomposes its contents. These bacteria are carried outside with manure, which is used to fuel the new gas generating plant.

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 subjected to fermentation with the formation of biogas. At the same time, the raw material turns into the most valuable fertilizer.

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

Factors affecting 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 a large amount of fat. The least profitable type of raw material is cattle manure.

Manure - raw material for biogas

Temperature

With increasing temperature, the productivity of bacteria increases. According to the temperature regime, gas generators are divided into three types.

Psychrophilic

These are installations without heating, in which the temperature is maintained in the range from 18 to 25 degrees. At the moment, they are almost never used.

mesophilic

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

Advantages:

• low energy consumption;
• the amino acid composition of fertilizers is the most useful.

Flaws:

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

thermophilic

Intensive heating is applied, the temperature exceeds 40 degrees.

Advantages:

• high performance;
• pathogenic bacteria die.

Flaws:

• high energy costs;
• low quality fertilizers.

Thermophilic bioreactor on manure

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

• due to the increase in energy costs, the profitability of the installation will decrease;
• as the temperature rises, 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 load humidity to 85% in winter and up to 92% in summer.

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

Fermentation time

If the 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.

With excessively long exposure, productivity is also reduced due to a lack of nutrients.

On average, the optimal fermentation time is:

• for 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. Carbon should be 10 to 20 times more than nitrogen.

Comparison of biogas with more traditional fuels

The strengths of this technology include:

1. The raw material used to produce biogas is an inexhaustible resource and is free of charge.
2. Biogas energy is not tied to a 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 capacity), biogas plants are between nuclear (5 thousand euros per 1 kW) and coal (2 thousand euros per 1 kW) stations.

Biogas plant

In practice, it has been proven that the greater the power of the installation, the cheaper the energy generated with its help. Also, profitability depends on the type of raw materials used.

Scheme of organizing the production of biogas at home

When constructing a gas generator with a capacity of more than 10 MW, operating on food waste, it will be necessary to spend about 2 thousand euros for each kW of power; at the same time, a plant with a capacity of up to 1 MW, using cow dung as a raw material, will cost 7 thousand euros per 1 kW.

The unit consists of several technological units.

Reactor

Represents the integral reinforced concrete capacity upholstered with thermal insulation with several technological openings. The reactor must be hermetically sealed to prevent air from entering its interior.

Biomass Feeding System

To load raw materials, the plant is equipped with a bunker. Waste is fed here manually or with the help of a conveyor.

Also, a pipe with hot water is supplied to the reactor.

Agitators

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

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

The motor can be turned on manually or automatically.

Automated heating system

Heating is installed at the bottom of the reactor. The heat carrier can be water or electricity. The heating elements are switched on by a thermostat set to a certain temperature.

gas holder

This is a 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 supply to the consumer.

The simplest do-it-yourself biogas plant for home

A self-made biogas generator, of course, is inferior in performance to expensive factory-made plants, but it will require significantly lower initial costs.

For its construction 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 water supply and discharge of the finished product.

The volume of the reactor should exceed the volume of the load by 1.5 times.

Installation scheme

In the simplest version, the gas generator is not equipped with heating and mixing device. Works on the construction of the installation are 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 the other, forming a cylindrical tank from them. All joints should be sealed with bituminous mastic.
3. The concrete container is pasted over with thermal insulation and waterproofing, after which they proceed to backfill the pit.
4. A lid with a tightly closed loading hatch is placed on top of the reactor. During the fermentation of raw materials in the reactor, high pressure is formed, so the lid can be secured with cables for reliability. It will not be superfluous to install a safety valve in it with a counterweight in the form of a weight.
5. It is necessary to attach the bunker to the loading hatch.
6. It remains to connect pipelines to the reactor. At the same time, a water seal must be installed on the line of discharge of the finished product.

Biomass is prepared as follows:

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

In order to increase productivity, a more advanced installation scheme can be applied, including water heating. A hot water boiler operating on the fuel produced by the plant will act as a heat generator.

DIY biogas plant - drawing

When loading raw materials, it is enough to warm 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 load of biomass allows for 6 months to receive an average of about 40 cubic meters per day. m of gaseous fuel.

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microclimat.pro

Do-it-yourself biogas plant for a private house: recommendations for the device and an example of homemade arrangement

A prudent owner dreams of cheap energy resources, efficient waste disposal and obtaining fertilizers. A do-it-yourself home biogas plant is an inexpensive way to make dreams come true. Self-assembly of such equipment will cost reasonable 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 do you need to get biogas

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

By its properties, it practically does not differ from natural gas, which is used for industrial and domestic needs.

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

• For some time, the biomass is exposed to bacteria. The fermentation period depends on the volume of raw materials.
• As a result of the activity of anaerobic bacteria, a combustible mixture of gases is released, which includes methane (60%), carbon dioxide (35%) and some other gases (5%). Also, during fermentation, potentially dangerous hydrogen sulfide is released 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 cleaned and enters the gas tank, where it is stored until it is used for its intended purpose.
• Gas from a gas tank can be used in the same way as natural gas. It goes to household appliances - gas stoves, heating boilers, etc.
• Decomposed biomass must be regularly removed from the fermenter. This is an additional effort, but the effort pays off. After fermentation, the raw material turns into high-quality fertilizer, which is used in fields and 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, out of 1 cubic meter. substrate can be obtained 70-80 cubic meters. biogas, but gas production is uneven and depends on many factors, incl. biomass temperature. This complicates the calculations.

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

Homemade biogas equipment, assembled from improvised materials, is much cheaper than industrial production plants. Its efficiency is lower, but it fully corresponds to the invested funds. If you have access to manure and the desire to make your own efforts to assemble and maintain the structure, this is very beneficial.

Advantages and disadvantages of the system

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

• Recycling. Thanks to a biogas plant, you can get the most out of the garbage that you would have to get rid of anyway. This disposal is less hazardous to the environment than landfill.
• Renewability of raw materials. Biomass is not coal or natural gas, the extraction of which depletes resources. In agriculture, raw materials appear constantly.
• Relative 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 emission. When biogas is burned, a small amount of sulfur is released into the atmosphere. This is a negative phenomenon, but its scale is known in comparison: when natural gas is burned, environmental pollution with sulfur oxides is much greater.
• Stable work. Biogas production is more stable than solar panels or windmills. If solar and wind power cannot be controlled, then biogas plants depend on human activity.
• You can use multiple settings. Gas is always a risk. To reduce potential damage in the event of an accident, several biogas plants can be dispersed around the site. If correctly designed and assembled, a system of several fermenters will work more stable than one large bioreactor.
• Benefits for agriculture. Some types of plants are planted to obtain biomass. You can choose those 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 ways that 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 give enough of it 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 m3 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 in the coming years, and the amount of energy needed, you can calculate the profitability of a biogas plant.

For laying in a bioreactor, a substrate is prepared, which includes several components in the following proportions:

• manure (preferably cow or pig) - 1.5 tons;
• organic waste (it can be rotted leaves or other components of plant origin) - 3.5 tons;
• 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 bookmark for six months, based on moderate gas consumption. After about 10-15 days, the fermentation process will give the first results: the gas will appear in small quantities and begin to fill the storage. After 30 days, you can expect full fuel production.

If the plant is working 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 there is no experience in assembling complex systems, it makes sense to pick up on the net or develop the simplest drawing of a biogas plant for a private house.

The simpler the design, the more reliable and durable it is. Later, when building and system handling skills become available, it will be possible to remake the equipment or mount an additional installation.

When calculating the volume of the fermenter, it is worth focusing on 5 cubic meters. Such an installation allows you to get the amount of gas needed 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 indicator, because the calorific value of biogas is usually not higher than 6000 kcal/m3.

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

Stage 1: preparation of a pit for a bioreactor

Almost the entire biogas plant is located 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 best solution is to buy ready-made polymer rings with a blank bottom. They will cost more than improvised materials, but additional sealing is not required. Polymers are sensitive to mechanical stress, but they are not afraid of moisture and chemically aggressive substances. They are not repairable, but if necessary, they can be easily replaced.

Stage 2: arrangement of gas drainage

Buying and installing special agitators for biogas plants is expensive. The system can be reduced in cost by equipping gas drainage. It is a vertically installed polymer sewer pipes, in which many holes have been made.

When calculating the length of the drainage pipes, one should be guided by the planned filling depth of the bioreactor. The tops of the pipes must be above this level.

Stage 3: arrangement of the insulating layer

The substrate can be immediately loaded 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, it will ensure the 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. At the highest point of the dome, a gas outlet pipe is installed and pulled to the gas holder.

The capacity of the bioreactor is closed with a tight lid. To prevent mixing of biomethane with air, a water seal is equipped. It also serves to purify gas. It is necessary to provide a release valve that will work if the pressure in the fermenter is too high.

Two ways to heat the bioreactor

Microorganisms that process the substrate are constantly present in the biomass, however, for their intensive reproduction, a temperature of 38 degrees and above is required. For heating during the cold period, you can use a coil connected to the home heating system, or electric heaters. The first method is more cost-effective, so it is more often used.

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

Video materials on assembling and arranging the system

Although there is nothing complicated in assembling and arranging biogas equipment, you need to be extremely attentive to details. Errors are not allowed, because can lead to explosions and destruction. We offer video instructions that will help you understand how the plants are arranged, assemble them correctly and supplement them with useful devices for more convenient use of biogas.

The video shows how a standard biogas plant works:

An example of a homemade biogas plant. Video tutorial on arranging the system with your own hands:

Video instruction for assembling a biogas plant from a barrel:

Description of the manufacturing process of substrate agitators:

A detailed description of the work of a makeshift gas storage:

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

sovet-ingenera.com

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