DIY assembly of a biogas plant is a very real undertaking. In addition, the cost of such work will be much lower than the purchase of a ready-made model. You can use the obtained resource in order to heat the house, cook food, and for many more needs.
general information
To begin with, the extraction of this substance is carried out as a result of the fermentation of a biological substrate. Here we can add that in its composition the gas obtained is practically no different from ordinary natural gas, which is used very actively in people's lives. Thanks to this, some owners were able to run a car on biogas with their own hands.
Another important fact is that biogas is an environmentally friendly raw material, upon receipt of which there is no negative impact on the environment. Vital waste, which must be disposed of, became the starting material for obtaining this resource. For this, there is a special reactor in which several processes take place:
- Biogas production begins when the biomass loaded into the container is exposed to certain bacteria. The duration of this treatment depends on how much substance was loaded inside.
- Anaerobic bacteria act inside the reactor. Under their influence, the raw material decomposes and a combustible mixture is released. The composition of this substance is approximately the following - methane 60%, carbon dioxide 35% and another 5% of some other volatile gases. It is very important to note here that, as a result of fermentation in small amounts, hydrogen sulfide, which is a potentially hazardous substance, can be released. Must have protective equipment.
- A do-it-yourself biogas plant has certain filters that clean the gas of other unnecessary components. After that, the resource enters the gas tank - the storage in which it remains until its use.
- It is possible to use the gas located in the gas tank in the same way as regular natural gas. You can connect the storage to a gas stove, boiler, etc.
- The place where the biomass is located is called a fermenter. It is necessary to regularly remove the used substance from this department. This is considered additional labor costs, but they pay off - such biomass is considered an excellent fertilizer for use in gardens.
Who benefits from processing equipment
It is worth saying that it is not always beneficial to have such equipment. Firstly, for effective and permanent work it is necessary to have access to the waste of livestock farms. Secondly, the production of this substance is uneven and strongly depends on the temperature of the biomass itself, which is loaded inside. As practice shows from 1 m 3 of the substance, you can get from 70 to 80 m 3 of biogas for heating your own home.
In order to stabilize the production of gas, as well as to make this process continuous, it is recommended to have several plants. The bottom line is that you need to lay the biomass with a certain time difference in different reactors. In this case, the development of the desired substance will be carried out in parallel, but the loading will be sequential.
As for the self-assembly of such equipment, it is worthwhile to understand that its effectiveness will be lower. However, the cost will be significantly lower than the price of an industrial installation, and therefore it is safe to say that the homemade product will work out its money.
Pros and cons of having a system on the farm
Do-it-yourself equipment installation for biogas production in the country has both positive and negative sides, and therefore, before starting work, you need to consider everything.
- One of the clear advantages is waste disposal. The presence of such a device will allow more efficient, and most importantly, safe disposal of unnecessary waste.
- The second plus is the constant renewability of raw materials. Biomass is a substance that is always abundant if you have your own farm.
- Low CO 2 content. When processing and obtaining biogas, carbon dioxide is not released into the atmosphere at all. A certain amount will get into the air when it is used, but this is not critical, since its content is small and the surrounding plants will absorb it.
- The biogas plant may well work stably. If you compare this equipment with other sources, for example, solar panels or wind generators, then they are not stable, but the production of biogas completely depends on the activity of the owner.
Despite this, such installations still have disadvantages. Of course, biogas is a much cleaner material, but its use nevertheless leaves little sediment in the atmosphere. In addition, problems with the supply of plant biomass may periodically occur. Too greedy use of such reactors will lead to the fact that the balance in a certain area will be upset.
How to get started
To get started, you will need a biogas drawing (you can do almost nothing with your own hands at home). The drawing shows the installation or the entire system, if you plan to install more than one reactor. However, if this is the first attempt at assembly, it is best to start with a simple one and start assembling only one object. It is also worth adding that the simpler the installation scheme, the more reliable and durable it is considered.
It is very important to calculate the volume of the fermenter - this is the place where the biomass will be stored. It is recommended to make it so that 5 m 3 of raw material is placed inside. This is enough to heat a private house with an area of up to 50 m 2 without problems if a gas boiler or stove is used.
In order to maximally stabilize the fermentation process inside the chamber, it is necessary to create an acceptable temperature regime. To do this, most often digs an earthen hole, inside which the object is located. If this is not possible, then it is necessary to create reliable thermal insulation in another way. Some owners, to ensure constant heating of the substance, conduct a pipe with water heating under the fermenter.
Deepening preparation
DIY biogas extraction equipment, the drawings of which should already be ready, almost everything is placed underground. That is why it is very important to carefully prepare the earthen pit. Currently, several materials are used for thermal insulation of the pit. It can be plastic, concrete, polymer rings.
The intensity of fermentation, as well as the gas exit rate, will depend on how well the bottom and the walls of the pit are prepared. In addition, this stage is considered the most difficult and time-consuming. The most optimal solution is the acquisition of polymer rings with a blank bottom. This product, of course, will cost more than improvised materials, but the installation of this material does not require additional sealing, which saves time, money and effort. It is also worth remembering that polymers are quite sensitive to mechanical stresses, and therefore it is worth handling them carefully, but at the same time they are very resistant to aggressive chemicals, and also are not afraid of moisture, which plays a key role. Such material cannot be repaired, but it will be quite simple to replace it with a new one.
The process itself is quite simple and straightforward. It is necessary to dig a recess of the desired size, and then engage in mounting polymer rings.
Arrangement of system elements
To produce biogas with your own hands at home, you must have a system of special mixers. However, their purchase and installation is considered quite an expensive pleasure, and therefore, you can do otherwise. You can significantly reduce material costs by installing gas drainage. To do this, you must have a certain number of sewer polymer pipes, which are installed in the pit in a vertical position. They make many small holes.
It is worth noting that you can use not only polymer, but also metal pipes. Their advantage is that they are much stronger in terms of mechanical loads than polymers that are more resistant to chemical influences. However, a significant drawback of the metal lies in the imminent occurrence of corrosion, and therefore it is still better not to install them.
As for the length of the pipes, it is calculated on the basis of such a value as the filling height of the fermenter. Pipes should be slightly higher than this indicator. After that, the bioreactor is already considered ready for operation, and you can start producing biogas with your own hands at home. However, since it still does not have a dome, it can be covered with a film so that the gas that will be released during the fermentation remains inside and is under slight pressure. A constant gas supply in normal mode will only be possible after mounting the dome and the outlet pipe.
The final stage is the assembly of the dome and pipes. Everything is also quite simple here. The finished reactor is closed on top by a “lid”, which has a domed shape. At the highest point of this part, a gas outlet hose is attached, which goes to the gas holder. It is important to note here that the free space inside the dome is a small storage of gas, but it is not enough. For this reason, gas must be consumed constantly, otherwise there is a risk that an explosion will occur under the dome overpressure.
In order to prevent the displacement of gas and air, it is necessary to close the reactor tightly with a lid. Quite often, a water lock is arranged so that rain does not get inside. Another important element is the installation of a system that will control the pressure. We need a valve that opens and releases a certain amount of substance if the pressure becomes too high.
Fermenter heating
In order to equip biogas heating with your own hands of your own home, you need to carefully heat the fermenter itself. Here you need to know the following. Microorganisms that process the substrate are always present in biomass. However, for their successful functioning and reproduction a constant temperature of 38 degrees Celsius is required. In order to heat the reactor in winter, you can use, for example, a coil that is connected to the heating system of the house or an electric heater. However, the use of electricity for these purposes is usually much more expensive, because it is connected specifically to the heating system in order to reduce the cost of the biogas heating process with your own hands.
The easiest way is to lay a pipe under the reactor itself. However, the effectiveness of such a system is rather low. It is best to do the arrangement of external heating. The ideal option is to have a heating system with steam so that the biomass does not overheat.
Feedstock
Do-it-yourself biogas extraction from manure is quite simple. Studies have shown that in the manure of any animal, there is initially a huge number of microorganisms that are enough to process it. The overwhelming majority of such organisms belongs to the group of methane-forming ones; therefore, gas production has become possible. To make the extraction of the substance as efficient as possible, you need to know which raw materials are best used. It has been proven that when combining plant mass and cattle biomass, the maximum amount of volatile matter will be released.
However, simply combining these substances and falling asleep in the reactor will not be enough. To maintain high productivity of biogas production from manure with your own hands, it is necessary that the substrate humidity is always in the region of 85-90%. It is important to know that water for wetting should be used only that which does not have other chemical impurities. Another important nuance is that for the flow of an effective process, there should be no large fragments in the fluid. If the plant part is also added to the biomass, you will have to grind it first.
In addition, one of the important factors was the maintenance of the pH of the substance at the right level. The limits that are considered normal are 6.7-7.6. Usually the quantitative acid content is normal in itself and rarely develops faster than bacteria from the methane-forming group. However, if this does happen and the acid forms faster, gas production will decrease. In order to stabilize the process, it is necessary to add ordinary soda or lime to the substrate.
Material loading and unloading
As for the location of the loading and unloading hatches, they should lead directly to the reactor vessel. It is important to note here that they should be located lower than the substrate. This must be done in order to avoid air entering the fermenter. In addition, the pipes must be at an acute angle. The loading and unloading hatches should be on opposite walls. These holes must have a cover, with which they will be closed during the entire period of operation.
Another nuance concerns the fact that manure can contain a variety of elements, for example, grass stems. This means that the pipe in the installation for biogas extraction with your own hands should be wide enough. If it is small in diameter, it will clog too quickly. The optimal diameter of the pipe is from 20 to 30 cm. It is worth adding that the pipes are assembled before proceeding with the arrangement of thermal insulation, but already after the fermenter is installed in the pit.
You can achieve maximum efficiency from a biogas plant with your own hands if you regularly load new raw materials and unload old ones. Such procedures should be carried out either once a day, or once every two days. A small trick is that while calculating the depth of the pit, you need to make it so that the biomass flows into the fermenter by gravity.
Cleaning
As mentioned earlier, not only methane-forming substances are released after biomass processing. In order to get rid of an unpleasant odor, as well as to achieve maximum burning of the substance, it must be cleaned. Remove impurities such as carbon dioxide, hydrogen sulfide, water vapor. Removal of CO 2 is carried out in a water seal. It is quite simple to arrange it - slaked lime must be placed on the bottom of the fermenter. However, such a bookmark will sometimes have to be changed. When the gas starts to burn worse, then the replacement time has come.
There are two different ways to dry gas . In the first case, you can equip the water locks in the gas pipeline. Curved sections are inserted into the pipe, which will be used as closures. Condensation will accumulate in these places. However, the method has a drawback, which consists in the need for periodic cleaning of the gate from condensate, since if the liquid becomes too much, the gas will cease to pass.
The second way is to install a filter with silica gel. The principle of operation is the same as in the hydraulic lock. Gas passes through it, and then is supplied already in the dried form. If you use this method, instead of cleaning the shutter, you will have to periodically dry the compartment with silica gel, which absorbs moisture.