Alternative heating - biogas installation. How to produce biogas at home Scheme of a continuous biogas plant

Hello to all readers and visitors of the “build a house” blog. I remember in one of the articles where we “invented”, I promised to tell you about getting biogas at home. Well, you promised, so you have to fulfill it, so as not to be sent to one of the bad places.

What do we know about the biogas plant? At the moment, many have only a vague idea about this, and most do not know anything at all about what it is - the whole idea of ​​\u200b\u200bsupplying energy to your home comes down to paying bills for gas or other energy resources on time. However, the endless increase in energy costs is prompting some inquisitive minds to look for alternative solutions and look for production methods, for example equipment for producing biogas at home from organic waste. Moreover, there are also Kulibins who manage to make 2 in 1 at once - combine a septic tank with a biogas plant. Do you think it's a joke? Not at all. In our world this is not possible.

So, a biogas plant will provide not only cheap energy for cooking and heating the house, but also high-quality fertilizer.

Home biogas plant using manure - diagram

The production of biogas from waste is an environmentally friendly type of fuel. In terms of its characteristics, it is practically in no way inferior to natural gas. It’s just that it’s not extracted from the ground, but by fermentation of organic waste.

The technology for extracting biogas can be imagined as follows: in a special collection facility called a bioreactor, the process of processing and fermenting waste is carried out. As a result, a mixture of gases is released, consisting of 60% methane, 35% carbon dioxide and the remaining 5% other gaseous substances. The extracted gas is constantly removed from the bioreactor and, after purification, is used for domestic purposes.

Diagram of the operating principle of a biogas plant

Waste waste, turned into first-class fertilizer, are periodically extracted and transported to the fields.

Note: studies have shown that a field treated with fertilizers fermented anaerobically gives a yield 20-30% more than a field fertilized in the usual way.

Biogas plants for home – buy or make it yourself?

If large farmers can afford to buy a biogas installation created in industrial conditions, then small enterprises, and even more so private homeowners, will most likely be able not to buy, but to install with their own hands less powerful installations that operate according to the same method, from scrap materials. But first you need to understand exactly what size, and most importantly what type of installation you want to get on your site.

Installation diagram for producing biogas for enterprises, farms

Types of installations, like the types of fermentation of organic substances, there are only two - with the supply of air (aerobic) and without it (anaerobic). At aerobic fermentation During the decomposition of biomass, hydrogen is oxidized to water, and carbon to carbon dioxide. Moreover, at this moment a large amount is released - the fermenting biomass heats up greatly.

During anaerobic fermentation 60-70% of carbon turns into methane, and the rest of it - into hydrogen, carbon dioxide and nitrogen. A regular gas burner is well suited for burning methane.

Biogas plant near the collective farm barn

The aerobic method of obtaining energy is easier and simpler than the anaerobic method. It does not require the production of sealed fermentation chambers and control. Aerobic installations are called BTS(biothermal stations). And anaerobic - BES(bioenergy or biogas stations). Any organic agricultural product is suitable as a raw material for fermentation. One Israeli company, for example, presented a compact biogas production plant that operates exclusively on fruit and vegetable peelings.

Home biogas plant from HomeBioGas

The biogas installation developed by the Israeli company HomeBioGas for producing gas at home, with its modest dimensions (123 x 165 x 100 cm) and weighing no more than 40 kg, can ensure the operation of one tile burner at maximum heat for an hour.

Homebiogas - biogas plant of an Israeli company

In addition, this installation produces up to 8 liters liquid fertilizers per day at maximum tank load (6 kg).

It is estimated that one small agricultural enterprise can process about a ton of organic waste per year using this installation. True, the installation is designed to operate at an average daily temperature of +20 o C. I, however, want to tell you how to create a home biogas installation that works perfectly in the climatic zone of central Russia. In principle, there is nothing particularly complicated about it.

Home biogas station

If the owners of the installation want it to produce 0.7-0.9 m 3 of biogas every day (quite enough to cook food for two people), then they need to do the following.

1. Load a fermentation chamber with a volume of 1 m3 with finely chopped organic waste diluted in water (let me remind you - fruit and vegetable peelings) in a weight ratio of 1: 10 - 1: 5.
2. Close it hermetically and ensure constant temperature supply from +25 to +30°C.

To maintain a constant temperature in the chamber, through it it is necessary to run the hot water coil, heated by gas produced by the same installation. Two taps need to be installed on the gas pipeline line: one at the gas stove, the other at the outlet of the reactor.

Note: our savvy rural people have long been thinking, and some have put it into practice, to obtain gas for heating the house from their own feces - that is, they combine a septic tank with a biogas plant. If you search the Internet well, you can even find diagrams.

Gas collector or gas holder- the second most important element of a biogas plant, after the fermentation plant. It consists of two steel vessels (one of which is turned upside down), easily entering each other. Water is poured into the outer vessel, forming a hydraulic seal for biogas entering the cavity of the inverted vessel. The annular gap between the walls of the vessels is approximately 50 mm. You can connect both tanks using ½-inch diameter pipes. The same gas pipeline takes gas from an inverted vessel and delivers methane to a conventional gas stove. It is recommended to cover the outside of the gas holder with an insulated tent.

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It is not easy for farms to dispose of manure. It is produced in excess, and a lot of money has to be spent on removal and disposal. In small private farms, manure is actively used as a free and effective fertilizer. It turns out that there is another way to usefully use this raw material, which makes it possible to obtain natural gas.

Many farms are already producing biogas from manure, using environmentally friendly technology that allows them to obtain a valuable product. Biomethane from manure is of high quality, which is why it is used in many countries.

What is biogas

Biogas from manure is an environmentally friendly fuel. According to its characteristics, it is close to natural gas, which is extracted from the bowels of the earth industrially.

Biogas can be an alternative to conventional fuel, because it is made from the waste of animals and birds, which can be found in abundance in any agriculture. With proper processing of raw materials, you can obtain colorless biogas without a characteristic odor, which contains at least 70% methane.

Biogas has good characteristics. One cubic meter of such fuel from manure produces the same amount of heat as one and a half kg of coal.

Process Benefits

Manure was processed to produce biogas back in Soviet times. Today, many countries are engaged in this type of industry, as it is profitable, easy and does not pose a threat to the environment.

Such alternative biogas does not require labor-intensive extraction of raw materials for production, the process of its creation is relatively cheap, and no toxic substances are released into the environment.

Of course, manure can be used simply as fertilizer if there are only a few cows on the farm. It is much more difficult for large farmers with hundreds of heads of livestock, because every year they have to get rid of several tons of manure.

In order for manure to become a high-quality fertilizer, it must be stored at a controlled temperature. But this requires extra expenses, so most farmers simply collect it in a certain place and then transport it to arable land.

If stored improperly, manure loses almost half of the nitrogen compounds in it and most of the phosphorus, so its performance becomes much worse. Methane gas is continuously released into the atmosphere from manure, which worsens the environmental situation.

The latest technologies for producing biomethane make it possible to process raw materials in such a way that the resulting biogas does not have a toxic effect on the environment. Biogas releases an incredible amount of energy when burned, and heated manure, after its use, becomes a very valuable anaerobic fertilizer.

Biogas technology

Biogas can be produced using bacteria, which do not require oxygen to function. Therefore, to produce biogas, it is necessary to build sealed containers in which the fermentation of raw materials will occur. The exhaust pipes are designed in containers in such a way that air from the external environment is not able to leak inside.

First, the reservoir is filled with liquid raw materials and the temperature is raised to the required level so that the world organisms begin to work. Methane rises up from liquid manure and accumulates in special tanks in which it undergoes a filtration stage. Then it is collected in gas cylinders. Used masses of manure accumulate at the bottom of containers, from where they are periodically removed and stored in other places. After pumping out the waste liquid, new manure is supplied to the tank.

Temperature regime of bacteria functioning

Methane can be released from manure only when a suitable temperature regime is created for it. Manure contains different bacteria that are activated and release biogas at different temperatures and at different speeds:

• Mesophilic bacteria. They start working if the ambient temperature rises above 30 degrees. Biogas is produced very slowly - the products can be collected after half a month.
• Thermophilic bacteria. To activate them, a temperature of 50-65 degrees is required. Biogas can be collected in just three days. Of particular value is sludge - manure waste after strong heating. This is a useful fertilizer and, most importantly, harmless - any helminths, weed seeds, pathogenic microorganisms are destroyed when heated.
• There is also another type of thermophilic bacteria that survive when heated to a temperature of 90 degrees. They are additionally included in manure so that fermentation occurs faster.

As temperatures drop, all types of bacteria become less active. In a small farm, mesophylls are usually used, because in this case additional heating is not required. Further, primary biogas can be used to artificially heat manure and activate thermophilic bacteria.

The disadvantage of storing raw materials is that they should not be subject to temperature fluctuations. Therefore, in winter, it is necessary to take care of a warm room for storing manure.

Preparation of raw materials for pouring into the reactor

As a rule, there is no need to further enrich manure with microorganisms, since they are already contained in it. All that needs to be done is to properly prepare the manure solution, monitor the temperature and change the raw materials in the bioreactor on time.

The moisture content of the raw materials should be at least 90% (the consistency of liquid sour cream). Therefore, before use, dry droppings (goats, sheep, horses, rabbits) are mixed with water. There is no need to dilute pig manure due to its high urine content.

It is also important that the manure is homogeneous and free of solid particles. The amount of biogas produced at the outlet depends on the fineness of the fractions. For this reason, a constantly running mixer is installed inside the equipment, destroying the hard crust on the surface of the raw material and preventing the release of methane.

Highly acidic waste (pig and cow manure) is best suited for the process. When the acidity level decreases, the bacteria slow down their work, so it is important to find out for the first time how long it takes to completely process one portion of the manure solution, and only then refill it.

The resulting product contains about seventy percent methane, one percent impurities (hydrogen sulfide and some volatile elements) and just under thirty percent carbon dioxide.

It can be used as fuel only after purification from impurities. Hydrogen sulfide compounds are removed using special filters. This must be done for the reason that such a substance, forming an acid with water, accelerates the corrosion processes of metals, pipes, tanks and the entire biogas plant, if it is metal.

Carbon dioxide also needs to be removed from the fuel, but this takes a lot of time:

• First of all, biogas is compressed under high pressure.
• Water is sent into the container, in which the impurity will dissolve.

If biogas is produced on a large scale, then purification is carried out with lime, activated carbon and special filters.

Reducing moisture content

At this stage, the purification of raw materials is carried out in different ways.

The first method is similar to the operation of a moonshine still. Biogas is directed upward through cold tubes. The water turns into condensate and flows down the tube, while the methane is sent to a reservoir for further storage.

Another way is to use a water seal. The resulting biogas is mixed with water, where all impurities remain. This method requires less time for cleaning, since water gets rid of both excess liquid and unnecessary elements.

For the manufacture of an installation near farms, a design that can subsequently be easily disassembled and moved to another area is best suited. The main equipment of the entire installation is a bioreactor - a container for pouring manure and fermenting it. Large enterprises use tanks of 50 cubic meters.

Small private farms use an underground reservoir instead of tanks. It is laid out with bricks in a dug hole. For tightness and strength, everything is fixed with cement mass. The volume depends on the amount of manure produced daily.

For above-ground installation, tanks made of plastic, metal or polyvinyl chloride can be used.

Installations can be either automated (in which the entire process occurs without human intervention) or mechanical (you must pump out, add raw materials, take in biogas, monitor pressure and temperature yourself).

On a small farm, it is advisable to use electric pumps, mixers, and grinders, which will prevent the appearance of crusts on the surface of manure and clean the structure of waste.

The most important rule is the absence of oxygen in the reactor. If present, an explosion may occur.

To prevent the reactor lid from being blown off by high pressure, counterweights and protective gaskets between the tanks and lids are needed.

The reservoir should never be completely full. It is advisable to leave a fifth of its volume unfilled.

At the site before installation, the equipment must:

• choose the right location (preferably as far as possible from a residential building)
• calculate the daily volumes of manure produced
• select a location for pipes (shipping, loading, condensing)
• find a place for manure waste
• dig a pit
• purchase a container for the tank and secure it to the bottom of the pit
• seal all joints
• construct a hatch for inspecting the reactor (be sure to place a gasket between the hatch and the reactor)

If the installation takes place in a cold climate, then you should definitely consider ways to heat it.

The final stage of construction is checking the equipment for leaks.

Gas quantity calculation

On average, a ton of manure will provide the owner with hundreds of cubic meters of biogas. In order to calculate the amount of biogas produced, it is necessary to multiply the daily mass of manure from each livestock by the number of animals.

Naturally, different animals and birds produce different amounts of manure:

• poultry (primarily chickens) – 150-170 g per day
• cow - 34-36 kg
• goat – 900 – 1100 g
• horse – 14-16 kg
• sheep – 900 – 1100 g
• pig – 4-6 kg

Pig and cow manure provides more fuel. The amount of biogas released can be increased by adding millet, beet tops, marsh plants, algae or corn to the mixture (the presence of chlorophyll in biomass improves methane release).

Biomass waste after gas production

The sludge formed after heating manure is used throughout agriculture in the form of fertilizers.

The carbon dioxide produced is usually purified, but when it is dissolved in water, a useful liquid is obtained.

Full utilization of biogas plant products

With rational use of manure, there may be no waste at all after the formation of biogas. For example, carbon dioxide is used as a fertilizer for vegetable crops.

The sludge is also used for root feeding.

Therefore, if you have a small installation for the production of biogas, it will be useful to install a biogreenhouse, which, due to fertilizers and the resulting energy, can operate all year round.

On the farmstead of any farm you can use not only the energy of wind, sun, but also biogas.

Biogas- gaseous fuel, a product of anaerobic microbiological decomposition of organic substances. Biogas technologies are the most radical, environmentally friendly, waste-free method of processing, recycling and disinfection of a variety of organic waste of plant and animal origin.

Conditions for obtaining and energy value of biogas.

Those who want to build a small-sized biogas plant on their farmstead need to know in detail what raw materials and what technology can be used to produce biogas.

Biogas is obtained in the process of anaerobic (without air access) fermentation (decomposition) of organic substances (biomass) of various origins: bird droppings, tops, leaves, straw, plant stems and other organic waste from individual households. Thus, biogas can be produced from all household waste that has the ability to ferment and decompose in a liquid or wet state without access to oxygen. Anaerobic plants (fermenters) make it possible to process any organic mass during the process in two phases: decomposition of the organic mass (hydration) and its gasification.

The use of organic matter that has undergone microbiological decomposition in biogas plants increases soil fertility and the yield of various crops by 10-50%.

Biogas, which is released during the complex fermentation of organic waste, consists of a mixture of gases: methane (“swamp” gas) - 55-75%, carbon dioxide - 23-33%, hydrogen sulfide - 7%. Methane fermentation is a bacterial process. The main condition for its flow and biogas production is the presence of heat in the biomass without air access, which can be created in simple biogas plants. Installations are easy to build on individual farms in the form of special fermenters for fermenting biomass.

In homestead farming, the main organic raw material for loading into the fermenter is manure.

At the first stage of loading cattle manure into the fermenter container, the duration of the fermentation process should be 20 days, pig manure - 30 days. More gas is obtained when loading various organic components compared to loading only one component. For example, when processing cattle manure and poultry manure, biogas can contain up to 70% methane, which significantly increases the efficiency of biogas as a fuel. After the fermentation process has stabilized, raw materials should be loaded into the fermenter daily, but not more than 10% of the amount of mass processed in it. The recommended humidity of raw materials in summer is 92-95%, in winter - 88-90%.

In the fermenter, along with gas production, organic waste is disinfected from pathogenic microflora and the unpleasant odors released are deodorized. The resulting brown sludge is periodically discharged from the fermenter and used as fertilizer.

To heat the processed mass, the heat that is released during its decomposition in the biofermenter is used. When the temperature in the fermenter decreases, the intensity of gas evolution decreases, since microbiological processes in the organic mass slow down. Therefore, reliable thermal insulation of a biogas plant (biofermenter) is one of the most important conditions for its normal operation.

To ensure the required fermentation regime, it is recommended to mix the manure placed in the fermenter with hot water (preferably 35-40 °C). Heat losses must also be minimized during periodic reloading and cleaning of the fermenter. For better heating of the fermenter, you can use “ greenhouse effect" To do this, a wooden or light metal frame is installed above the dome and covered with plastic film. The best results are achieved at a temperature of the raw material that is being fermented, 30-32 ° C and a humidity of 90-95%. In the south of Ukraine, biogas plants can operate efficiently without additional heating of the organic mass in the fermenter. In the regions of the middle and northern zone, part of the gas produced must be spent during the cold periods of the year on additional heating of the fermented mass, which complicates the design of biogas plants. It is possible that after the first filling of the fermenter and the start of gas extraction, the latter does not burn. This is explained by the fact that the initially produced gas contains more than 60% carbon dioxide. In this case, it must be released into the atmosphere and after 1-3 days the biogas plant will operate in a stable manner.

When fermenting excrement from one animal, you can get per day: cattle (live weight 500-600 kg) - 1.5 cubic meters of biogas, pigs (live weight 80-100 kg) - 0.2 cubic meters, chicken or rabbit - 0.015 cubic meters.

In one day of fermentation, 36% of biogas is formed from cattle manure, and 57% from pork manure. In terms of energy, 1 cubic meter of biogas is equivalent to 1.5 kg of coal, 0.6 kg of kerosene, 2 kW/h of electricity, 3.5 kg of firewood, 12 kg of manure briquettes.

Biogas technologies have been widely developed in China; they are being actively implemented in a number of countries in Europe, America, Asia, and Africa. In Western Europe, for example in Romania and Italy, more than 10 years ago they began to widely use small-sized biogas plants with a volume of processed raw materials of 6-12 cubic meters.

Owners of homesteads and farms in Ukraine also began to show interest in such installations. On the territory of any estate it is possible to equip one of the simplest biogas plants, which, for example, are used in individual farms in Romania. According to those shown in Fig. 1-a, pit 1 and dome 3 are equipped according to the dimensions. The pit is lined with reinforced concrete slabs 10 cm thick, which are plastered with cement mortar and coated with resin for tightness. A bell 3 m high is welded from roofing iron, in the upper part of which biogas will accumulate. To protect against corrosion, the bell is periodically painted with two layers of oil paint. It is even better to first coat the inside of the bell with red lead.

In the upper part of the bell, a pipe 4 is installed for removing biogas and a pressure gauge 5 for measuring its pressure. The gas outlet pipe 6 can be made of a rubber hose, plastic or metal pipe.

Around the fermentation pit, a concrete groove-water seal 2 is installed, filled with water, into which the lower side of the bell is immersed to a depth of 0.5 m.

Gas can be supplied to the stove through metal, plastic or rubber tubes. To prevent pipes from breaking due to freezing of condensing water in winter, a simple device is used (Fig. 1-b): U-shaped tube 2 is connected to pipeline 1 at the lowest point. The height of its free part must be greater than the biogas pressure (in mm water column). Condensate 3 is drained through the free end of the tube, and there will be no gas leakage.

In the second installation option (Fig. 1-c), pit 1 with a diameter of 4 mm and a depth of 2 m is lined inside with roofing iron, the sheets of which are tightly welded. The inner surface of the welded tank is coated with resin for anti-corrosion protection. On the outside of the upper edge of the concrete tank, a circular groove 5 up to 1 m deep is installed, which is filled with water. The vertical part of the dome 2, covering the tank, is freely installed into it. Thus, the groove with water poured into it serves as a water seal. Biogas is collected in the upper part of the dome, from where it is supplied through the outlet pipe 3 and then through pipeline 4 (or hose) to the place of use.

About 12 cubic meters of organic mass (preferably fresh manure) is loaded into round tank 1, which is filled with the liquid fraction of manure (urine) without adding water. A week after filling, the fermenter starts working. In this installation, the fermenter capacity is 12 cubic meters, which makes it possible to build it for 2-3 families whose houses are located nearby. Such an installation can be built on a farmstead if the family rears bulls on contract or keeps several cows.

The design and technological diagrams of the simplest small-sized installations are shown in Fig. 1-d, d, f, g. Arrows indicate technological movements of the initial organic mass, gas, and sludge. Structurally, the dome can be rigid or made of polyethylene film. The rigid dome can be made with a long cylindrical part for deep immersion into the processed mass, “floating” (Fig. 1-d) or inserted into a hydraulic valve (Fig. 1-e). A film dome can be inserted into a water seal (Fig. 1-e) or made in the form of a one-piece glued large bag (Fig. 1-g). In the latter version, a weight 9 is placed on the film bag so that the bag does not swell too much, and also to create sufficient pressure under the film.

The gas, which is collected under the dome or film, is supplied through a gas pipeline to the place of use. To avoid a gas explosion, a valve adjusted to a certain pressure can be installed on the outlet pipe. However, the danger of a gas explosion is unlikely, since with a significant increase in gas pressure under the dome, the latter will be raised in the hydraulic seal to a critical height and will tip over, releasing the gas.

Biogas production may be reduced due to the fact that a crust forms on the surface of the organic raw material in the fermenter during fermentation. To ensure that it does not interfere with the escape of gas, it is broken by mixing the mass in the fermenter. You can mix not by hand, but by attaching a metal fork to the dome from below. The dome rises in the hydraulic seal to a certain height when gas accumulates and lowers as it is used.

Due to the systematic movement of the dome from top to bottom, the forks connected to the dome will destroy the crust.

High humidity and the presence of hydrogen sulfide (up to 0.5%) contribute to increased corrosion of metal parts biogas plants. Therefore, the condition of all metal elements of the fermenter is regularly monitored and places of damage are carefully protected, preferably with lead lead in one or two layers, and then painted in two layers with any oil paint.

Rice. 1. Schemes of the simplest biogas plants:

A). with a pyramidal dome: 1 - pit for manure; 2 - groove-water seal; 3 - bell for collecting gas; 4, 5 - gas outlet pipe; 6 - pressure gauge;

b). device for condensate removal: 1 - pipeline for gas removal; 2 - U-shaped pipe for condensate; 3 - condensate;

V). with a conical dome: 1 - pit for manure; 2 - dome (bell); 3 - expanded part of the pipe; 4 - gas outlet pipe; 5 - groove-water seal;

d, e, f, g - diagrams of variants of the simplest installations: 1 - supply of organic waste; 2 - container for organic waste; 3 - gas collection area under the dome; 4 - gas outlet pipe; 5 - sludge removal; 6 - pressure gauge; 7 - dome made of polyethylene film; 8 - water seal; 9 - load; 10 - one-piece polyethylene bag.

Biogas plant with heating of the fermentable mass by the heat released during the decomposition of manure in an aerobic fermenter, is shown in Fig. 2, includes a methane tank - a cylindrical metal container with a filler neck 3, a drain valve 9, a mechanical stirrer 5 and a biogas selection pipe 6.

Fermenter 1 can be made rectangular from wooden materials. To unload treated manure, the side walls are removable. The floor of the fermenter is lattice; air is blown through the technological channel 10 from a blower 11. The top of the fermenter is covered with wooden panels 2. To reduce heat loss, the walls and bottom are made with a heat-insulating layer 7.

The installation works like this. Pre-prepared liquid manure with a moisture content of 88-92% is poured into the methane tank 4 through Head 3, the liquid level is determined by the lower part of the filler neck. Aerobic fermenter 1 is filled through the upper opening part with bedding manure or a mixture of manure with loose dry organic filler (straw, sawdust) with a moisture content of 65-69%. When air is supplied through the technological channel in the fermenter, the organic mass begins to decompose and heat is released. It is enough to heat the contents of the methane tank. As a result, biogas is released. It accumulates in the upper part of the digester tank. Through pipe 6 it is used for domestic needs. During the fermentation process, the manure in the digester is mixed with a mixer 5.

Such an installation will pay for itself within a year only due to waste disposal in personal households.

Rice. 2. Diagram of a heated biogas plant:
1 - fermenter; 2 - wooden shield; 3 - filler neck; 4 - methane tank; 5 - stirrer; 6 - pipe for biogas sampling; 7 - thermal insulation layer; 8 - grate; 9 - drain valve for processed mass; 10 - channel for air supply; 11 - blower.

Individual biogas plant(IBGU-1) for a peasant family with 2 to 6 cows or 20-60 pigs, or 100-300 poultry (Fig. 3). The installation can process from 100 to 300 kg of manure every day and produces 100-300 kg of environmentally friendly organic fertilizers and 3-12 cubic meters of biogas.

To cook food for a family of 3-4 people, it is necessary to burn 3-4 cubic meters of biogas per day, to heat a house with an area of ​​50-60 sq.m - 10-11 cubic meters. The installation can operate in any climate zone. The Tula Stroytekhnika plant and the Orlovsky repair and mechanical plant (Orel) began their serial production.

Rice. 3. Scheme of an individual biogas plant IBGU-1:
1 - filler neck; 2 - stirrer; 3 - gas sampling pipe; 4 - thermal insulation layer; 5 - pipe with a tap for unloading processed mass; 6 - thermometer.

Typical design

In recent years, it has become fashionable to use various biogas plants for your own needs, which allow you to obtain energy from waste. As a rule, such a design is a sealed container where, at a given temperature, fermentation of the organic components of wastewater, various wastes, etc. occurs. Do-it-yourself biogas plant is difficult, but doable. The main thing is to know the types of these devices and the principle of their operation, as well as understand the drawings.

Operating principle of the installation

The process of producing biogas from manure or other raw materials is called fermentation, and fermentation is carried out through the activity of special bacteria. In this case, a crust forms on the surface of the raw material, which must be constantly destroyed. This must be done by thoroughly mixing the contents manually or using special devices inside the reactor. As a result of such manipulations, biogas is released.

The resulting biogas, after purification, is collected in a special container - a gas holder, from which it is carried through gas pipes to the place of use. The processed raw materials are turned into biofertilizer. It is unloaded through a special opening, and then can be applied to the soil or used as a feed additive for animals, which depends on the feedstock.

To obtain biogas with your own hands, in addition to observing the oxygen-free regime, several conditions must also be met:

• Availability of nutrients for bacteria.
• Maintaining temperature conditions.
• Choosing the right time for fermentation.
• Maintaining acid and alkaline balance.
• Maintaining the proportions of solid particles in the raw materials and timely mixing.

Types of biogas plants

Note! Today, there are a large number of designs of biogas plants to make the production of biogas not only convenient, but also effective.

They are distinguished by their appearance, as well as by their constituent structural elements and materials used in their creation.

By download type

Depending on the type of raw material loading, there are two types of installation - continuous loading and batch loading.

They differ from each other in the fermentation time of raw materials and the regularity of loading. The most effective from the point of view of producing biogas is a continuous loading installation.

By appearance

The appearance of the device depends on the method of accumulation and storage of biogas. It can be collected in a special gas tank, at the top of the reactor, or under a flexible dome, floating or standing separately from the reactor.

Creating a DIY installation

Building a biogas structure with your own hands is a rather complex and time-consuming process. Such an installation makes the production of biogas an alternative option that allows you to save money on the purchase of fuel and electricity.

What do you need to know?

Generalized scheme

You can make a structure from those materials that are available on the farm, but are not used. For example, a reactor for such an installation can be easily built from old pots, boilings, and basins, but it is better to use cylindrical objects.

Here are some important requirements that a reactor must meet:

• Good thermal insulation.
• Air and water permeability. After all, when biogas and oxygen are mixed, a reaction occurs, and its destructive force can not only break the reactor, but also explode it.
• Reliability and durability, since a huge amount of energy is released during the reaction.

To build a high-quality and efficient biological installation, you must adhere to the following sequence:

• Select a location for installing the future reactor. And be sure to calculate the amount of waste needed for 1 day. This is necessary to determine the dimensions of the structure.
• Prepare the basin, then install the unloading and loading pipes.
• Install and secure the loading hopper and gas outlet pipe as firmly as possible.
• For use, as well as subsequent maintenance and repair of the biogas plant, the manhole cover must be installed.
• Carefully check the reactor for thermal insulation and tightness.

The walls of the future installation should ideally be made of concrete, since the strength of the structure is the key to your safety. In addition, it is very important that the distance from the reactor to the nearest building is at least 500 meters. After all, during fermentation, a poisonous gas is released, which has a detrimental effect on a person and can kill him in a matter of minutes.

To obtain biogas you will need:

The principle of heating a house

• Mix 2 tons of cow manure and about 4.5 tons of humus from rotten waste, tops and leaves.
• Add water to the mixture so that the humidity in the reactor is 70%.
• Unload the resulting mass into the pit and heat it using a heating unit to +40 degrees. After the mixture begins to ferment, its temperature will reach +70 degrees.
• Attach a counterweight to the dome, which should be 2 times heavier than the mixture, so that the dome does not fly off the pit due to the released gas.

It should be remembered that the mass loaded into the reactor should not contain antibiotics, solvents or other synthetic substances. They will not only interfere with the reaction, but even stop it altogether, and will also cause the destruction of the reactor walls.

Equipment options

A homemade installation today is a rare type of alternative energy source on farms. But, given the efficiency and payback of such a design, many farmers began to think about building a biogas plant on their own in order to provide themselves with electricity and heat in this way.

Today there are many options for this type of equipment for producing biogas. Taking into account the climatic conditions of Russia, it is recommended to create the following types of installations.

Manual loading reactor without stirring

This is the simplest installation for a home, the volume of which can range from 1 to 10 cubic meters. It is capable of processing up to 200 kg of manure per day.

Manual loading option

It consists of a minimum number of parts:

• Bunker for fresh raw materials.
• Reactor.
• Biogas selection device.
• Capacity for unloading fermented raw materials.

This installation can be used for southern regions, since it operates without stirring or heating, and is also designed to operate in psychophilic mode. The used raw materials are removed from the reactor through the unloading pipe during the loading of the next portion of manure. This occurs due to the biogas pressure in the reactor.

When making such a structure with your own hands, it is recommended to follow the following sequence:

• After calculating the daily volume of manure and selecting a reactor of the required size, it is necessary to determine the location of the future structure, as well as prepare materials for installation.
• Then you need to build a loading and unloading pipe, and also make a pit for installation.
• After installing the reactor in the pit, it is necessary to install a loading hopper and a gas outlet, as well as a manhole cover.
• Check the structure for leaks, paint it and insulate it.
• Put into operation.

Manual loading, heating and stirring design

A biogas plant can be constructed with manual loading of raw materials and periodic mixing. At the same time, it will not require large financial investments from the owner. The design is suitable for a small farm, since its capacity is to process up to 200 kg of manure per day. The drawings of such an installation are similar to the drawings of the previous version, and they can be made by contacting a specialist.

This unit can operate in mesophilic and thermophilic modes

For a stable and maximally intensive fermentation process, a special reactor heating system is installed. The biogas plant can operate in two modes. The reactor is heated using a hot water boiler running on the produced biogas. The rest of the biogas can be used to operate household appliances.

The processed raw materials are stored in a special container until applied to the soil or used as a breeding ground for California worms.

Installation with gas holder, pneumatic loading, heating and mixing of raw materials

A similar installation is intended for small and medium-sized farms with the processing of up to 1.5 tons of manure per day into biogas. The raw materials are heated through a heat exchanger with a water heating boiler, which runs on the resulting gas. The mass unloading pipeline is equipped with a special branch for collecting biofertilizer in storage and for loading into vehicles with subsequent removal to the fields.

The design of such a home-made installation involves pneumatic loading of manure into the reactor, as well as mixing with biogas, the selection of which is carried out automatically. Biogas is stored in a special compartment - a gas holder.

Conclusion

Biogas is a relatively new source of energy. Using it, you can forever forget about electricity tariffs and even solve such issues as methane production. Correctly developed drawings and the efforts made in the manufacture of the installation will significantly save money for more than one farmer, which is especially important these days.

Related Posts

Ecology of consumption. Estate: Is it profitable to produce biofuel at home in small quantities on a private plot? If you have several metal barrels and other iron junk, as well as a lot of free time and you don’t know how to manage it - yes.

Suppose there was no natural gas in your village and there never will be. And even if there is, it costs money. Although it is an order of magnitude cheaper than costly heating with electricity and liquid fuel. The nearest pellet production workshop is a couple of hundred kilometers away, and transport is expensive. It’s becoming more and more difficult to buy firewood every year, and it’s also troublesome to burn with it. Against this background, the idea of ​​obtaining free biogas in your own backyard from weeds, chicken droppings, manure from your favorite pig or the contents of the owner’s outhouse looks very tempting. All you have to do is make a bioreactor! On TV they talk about how thrifty German farmers keep themselves warm with “manure” resources and now they don’t need any “Gazprom”. This is where the saying “takes the film off feces” is true. The Internet is replete with articles and videos on the topic “biogas from biomass” and “do-it-yourself biogas plant.” But we know little about the practical application of the technology: everyone is talking about the production of biogas at home, but few people have seen concrete examples in the village, as well as the legendary Yo-Mobile on the road. Let's try to figure out why this is so and what are the prospects for progressive bioenergy technologies in rural areas.

What is biogas + a little history

Biogas is formed as a result of sequential three-stage decomposition (hydrolysis, acid and methane formation) of biomass by various types of bacteria. The useful combustible component is methane, and hydrogen may also be present.

The process of bacterial decomposition that produces flammable methane

To a greater or lesser extent, flammable gases are formed during the decomposition of any remains of animal and plant origin.

The approximate composition of biogas, the specific proportions of the components depend on the raw materials and technology used

People have long been trying to use this type of natural fuel; medieval chronicles contain references to the fact that residents of the low-lying regions of what is now Germany a millennium ago received biogas from rotting vegetation by immersing leather furs in swamp slurry. In the dark Middle Ages and even the enlightened centuries, the most talented meteorists, who, thanks to a specially selected diet, were able to release and ignite abundant methane flatus in time, aroused the constant delight of the public at cheerful fair performances. Industrial biogas plants began to be built with varying degrees of success in the mid-19th century. In the USSR in the 80s of the last century, a state program for the development of the industry was adopted, but not implemented, although a dozen production facilities were launched. Abroad, the technology for producing biogas is being improved and is being promoted relatively actively; the total number of operating installations is in the tens of thousands. In developed countries (EEC, USA, Canada, Australia) these are highly automated large complexes, in developing countries (China, India) - semi-handicraft biogas plants for homes and small farms.

Percentage of the number of biogas plants in the European Union. It is clearly visible that the technology is actively developing only in Germany, the reason is solid government subsidies and tax incentives

What uses does biogas have?

It is clear that it is used as fuel, since it burns. Heating of industrial and residential buildings, electricity generation, cooking. However, not everything is as simple as they show in the videos scattered on YouTube. Biogas must burn stably in heat-generating installations. To do this, its gas environment parameters must be brought to fairly stringent standards. The methane content must be at least 65% (optimum 90-95%), hydrogen must be absent, water vapor has been removed, carbon dioxide has been removed, the remaining components are inert to high temperatures.

It is impossible to use biogas of “animal dung” origin, not freed from foul-smelling impurities, in residential buildings.

The normalized pressure is 12.5 bar; if the value is less than 8-10 bar, the automation in modern models of heating equipment and kitchen equipment stops the gas supply. It is very important that the characteristics of the gas entering the heat generator are stable. If the pressure jumps beyond the normal limits, the valve will work and you will have to turn it back on manually. It’s bad if you use outdated gas appliances that are not equipped with a gas control system. At best, the boiler burner may fail. The worst case scenario is that the gas will go out, but its supply will not stop. And this is already fraught with tragedy. Let us summarize what has been said: the characteristics of biogas must be brought to the required parameters, and safety precautions must be strictly observed. Simplified technological chain for biogas production. An important stage is separation and gas separation

What raw materials are used to produce biogas

Plant and animal raw materials

• Plant raw materials are excellent for the production of biogas: from fresh grass you can get the maximum fuel yield - up to 250 m3 per ton of raw material, methane content up to 70%. Somewhat less, up to 220 m3 can be obtained from corn silage, up to 180 m3 from beet tops. Any green plants are suitable, algae and hay are good (100 m3 per ton), but it makes sense to use valuable feed for fuel only if there is an obvious excess of it. The yield of methane from the pulp formed during the production of juices, oils and biodiesel is low, but the material is also free. The lack of plant raw materials is a long production cycle, 1.5-2 months. It is possible to obtain biogas from cellulose and other slowly decomposing plant waste, but the efficiency is extremely low, little methane is produced, and the production cycle is very long. In conclusion, we say that plant raw materials must be finely chopped.
• Raw materials of animal origin: traditional horns and hooves, waste from dairies, slaughterhouses and processing plants are also suitable and also in crushed form. The richest “ore” is animal fats; the yield of high-quality biogas with a methane concentration of up to 87% reaches 1500 m3 per ton. However, animal raw materials are in short supply and, as a rule, other uses are found for them.

Flammable gas from excrement

• Manure is cheap and is available in abundance on many farms, but the yield and quality of biogas is significantly lower than from other types. Cow pats and horse apples can be used in their pure form, fermentation begins immediately, biogas yield is 60 m2 per ton of raw material with a low methane content (up to 60%). The production cycle is short, 10-15 days. Pig manure and chicken droppings are toxic - so that beneficial bacteria can develop, it is mixed with plant waste and silage. A big problem is represented by detergent compositions and surfactants, which are used when cleaning livestock buildings. Together with antibiotics, which enter manure in large quantities, they inhibit the bacterial environment and inhibit the formation of methane. It is completely impossible not to use disinfectants, and agricultural enterprises that have invested in the production of gas from manure are forced to seek a compromise between hygiene and control over animal disease, on the one hand, and maintaining the productivity of bioreactors, on the other.
• Human excrement, completely free, is also suitable. But using ordinary sewage is unprofitable, the concentration of feces is too low and the concentration of disinfectants and surfactants is high. Technologists claim that they could be used only if “products” only flow from the toilet into the sewer system, provided that the bowl is flushed with only one liter of water (standard 4/8 l). And without detergents, of course.

Additional requirements for raw materials

A serious problem faced by farms that have installed modern equipment for producing biogas is that the raw material should not contain solid inclusions; a stone, nut, piece of wire or board that accidentally gets into the mass will clog the pipeline and disable an expensive fecal pump or mixer. It must be said that the given data on the maximum gas yield from the raw material correspond to ideal laboratory conditions. To get closer to these figures in real production, a number of conditions must be met: maintain the required temperature, periodically stir finely ground raw materials, add additives that activate fermentation, etc. In a makeshift installation, assembled according to the recommendations of articles on “producing biogas with your own hands,” it is barely possible to achieve 20% of the maximum level, while high-tech installations allow you to achieve values ​​of 60-95%.

Quite objective data on the maximum biogas yield for various types of raw materials

Biogas plant design

Is it profitable to produce biogas?

We have already mentioned that in developed countries large industrial installations are built, while in developing countries they mainly build small ones for small farms. Let's explain why this is so:

Does it make sense to produce biofuels at home?

Is it profitable to produce biofuel at home in small quantities on a private plot? If you have several metal barrels and other iron junk, as well as a lot of free time and you don’t know how to manage it - yes. But the savings, alas, are meager. And investing in high-tech equipment with small volumes of raw materials and methane production does not make sense under any circumstances.

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Without mixing the raw materials and activating the fermentation process, the methane yield will be no more than 20% of the possible one. This means that, in the best case, with 100 kg (hopper loading) of selected grass you can get 5 m3 of gas without taking into account compression. And it will be good if the methane content exceeds 50% and it is not a fact that it will burn in the heat generator. According to the author, raw materials are loaded daily, that is, his production cycle is one day. In fact, the required time is 60 days. The amount of biogas obtained by the inventor, contained in a 50-liter cylinder, which he managed to fill, in frosty weather for a heating boiler with a capacity of 15 kW (a residential building of about 150 m2) is enough for 2 minutes.

Those who are interested in the possibility of producing biogas are advised to carefully study the problem, especially from a financial point of view, and contact specialists with experience in such work with technical questions. Practical information obtained from those farms where bioenergy technologies have already been used for some time will be very valuable. published