First, the basic conditions of biogas production
1, strictly oxygen-free environment. Build a sealed container-biogas digester, which is watertight and airtight and can withstand certain pressure.
2. There should be enough raw materials for biogas fermentation. The raw materials for biogas fermentation are very rich. Crop stalks, weeds, leaves, human and animal manure, domestic sewage, waste mash and wastewater from most organic processing plants are all good raw materials for biogas fermentation.
3. water. Water is an important part of microbial cells, so a certain amount of water should be kept in the biogas digester.
4. Suitable temperature. Biogas fermentation temperature range is relatively large, generally within 9℃-60℃, which can produce biogas.
5. pH value of biogas fermentation. The optimum pH value of biogas fermentation is between 6.5 and 7.5.
6. Excellent inoculum. When feeding for the first time, the inoculation amount should be 10%-30% of the total fermentation broth. Generally speaking, the larger the inoculation amount, the faster the biogas fermentation starts. Heavy metal salts, pesticides, poisonous plants, etc. Attention should be paid to the use and management of biogas digesters.
Second, the biogas digester supporting structure construction requirements
Generally speaking, toilets and pigsty must be connected with biogas trinity, so that organic pollutants can enter the pool in time. Therefore, the construction requirements of pigsty and toilet are put forward.
1, construction scale. The three-in-one household biogas digester covers an area of about 30-42 square meters, with one column and one toilet of about 30 square meters and two columns and one toilet of about 42 square meters. Its principles are: ① the structural layout is reasonable; (2) Coordinate with the main structure (such as residence), (3) The horizontal elevation of the building should be lower than the main building10cm; ④ Convenient traffic operation; ⑤ The dimensions of each part are coordinated.
2. Toilet building. (1) The total height of the toilet should be 2.3-2.4 meters, and the clear height of the internal space should be greater than 2.2 meters, so that it can also be used as a bathroom; ② The internal area is 2-3 square meters; ③ The height of the toilet door should reach 1.85m and the width should be 0.8m(4) The toilet should be equipped with ventilation window; ⑤ The toilet elevation is higher than the pigsty elevation10cm; 6. The inside and outside of the bathroom should be painted flat and smooth, and the lines should be horizontal and vertical.
3, pigsty, pigsty building. (1) The height and span of the crib should be consistent with the toilet; The horizon should be 5-8 cm higher than the pigsty, which is convenient for drying; The inner and outer walls of the pigsty should be painted flat and smooth with horizontal and vertical lines. (2) Pigpen: The height of the pen is about 80 cm, and the area depends on the pig raising scale and site area.
Toilets and pigsty are built on it. Flat roofs can be used to cover prefabricated panels or cast-in-place templates. If it is cast-in-place, it should be reinforced with iron wires, steel bars and bamboo strips. , and the top and bottom of the flat roof should be painted, smooth and flat, impervious.
Third, the daily management of household biogas digesters
1, strengthen the usual maintenance of biogas digesters.
(1) The abnormal use of biogas digesters is mainly caused by two situations: one is caused by water leakage; The other is abnormal fermentation of raw materials.
Abnormal gas consumption caused by water leakage should be treated symptomatically. (1) The biogas digester did not produce gas or produced gas abnormally after feeding, and the pressure label never exceeded a certain value. The water levels of the two pools have not changed, and most of them are air leakage pools. (2) The gas can only be used normally by adding several barrels of water every day, which belongs to the leaky pool. (3) The gas used for gas production is normal at ordinary times, and suddenly the gas pressure drops to zero, and will not rise again in the future. This situation mostly belongs to the rupture of the pool body, which is both leaking and leaking. (4) The liquid level fluctuation of the pressure gauge indicates a small amount of air leakage. In order to determine the location of air leakage, the following methods can be adopted: a, clamp the gas pipeline at the gas pipeline and observe the change of the pressure gauge. If the pressure drops, it means that there is air leakage at the joint of gas pipeline or accessories; B, card after the death of the pressure gauge liquid level does not drop, also does not fluctuate, that airway joint or pool cover leakage; C, dig out the airway and fill it with water. If there are bubbles in the water, the airway is leaking, otherwise it is leaking at the pool cover. ⑤ When the switch is turned on, the liquid level of the pressure gauge drops a lot. At the same time, when boiling water, the fire is big or small, and the gas pipeline is noisy, indicating that there is water in the gas pipeline, which should be eliminated as soon as possible.
Microscopically, the following methods should be taken to deal with abnormal gas production: ① For those with insufficient strains, sludge strains should be added to promote the balance of fermentation process in the pool; (2) Adjust the proportion of raw materials for acid production, so that the proportion of carbon-rich raw materials and nitrogen-rich raw materials tends to be reasonable, and pay special attention not to put too much into the tank at one time; (3) Adjust the pH value of raw materials in the tank to make the pH value stable in a neutral and acidic state (6.8-7.0).
(2) When adding fuel to the biogas digester every year, clean the cover and inner surface of the biogas digester and brush the cement slurry 1-2 times to improve the air tightness.
(3) No matter whether it is a new biogas digester or an old biogas digester that has been used for many years, it is necessary to feed in time when adding fuel, and it is not allowed to leave the pool empty for a long time and damage the pool body; The reasons are as follows: ① Because of the high groundwater level, it may break through the bottom of the pool; (2) summer exposure leads to cracks; (3) freezing pool body in winter; (4) artificial damage to the bottom of the forebay, etc.
(4) Always keep a certain amount of water in the reservoir of the movable cover of biogas digester to prevent cracking and air leakage.
(5) The fermentation raw materials in the tank should be often stirred in different forms to promote decomposition and digestion and speed up production.
Degree and gas production.
2. Strengthen the management of biogas digesters in winter.
(1) Do a good job of refueling biogas digesters before winter. Refueling time is around the autumnal equinox.
(2) Properly increase the concentration of thousands of substances in fermentation raw materials. Generally, it is 7%-8% in spring, and the fermentation concentration in wintering period should be above 10%.
(3) Strengthen daily management. On the one hand, it is necessary to adhere to the conventional feed liquid small inlet and small outlet. On the other hand, we should pay attention to frequent stirring to promote the vitality of microorganisms. On the other hand, it is necessary to do a good job of biogas insulation, such as building a plastic greenhouse and covering the pool with a film.
Fourthly, the construction and use of biogas digesters.
Safety measures of biogas
1, prevention of industrial accidents
(1) When the foundation pit is excavated, when the underground water level is high and sand flows, the excavation should be carried out at a certain slope, and the excavated soil should be piled away from the foundation pit. Don't pile up heavy objects around the pit to avoid unnecessary landslides. When building a pool in rainy season, a drainage ditch should be dug around the pit to prevent water from rushing through the pit wall.
(2) When the formwork is cast-in-place, it should be firm and stable, safe and reliable, and easy to disassemble and assemble. Dismantle the formwork not too early, and only when the cement strength reaches more than 70%. Be careful when ripping, and no one is allowed to stand on the pool cover.
2, to prevent poisoning suffocation
Biogas pit is a closed container, with no air circulation and lack of oxygen. In order to prevent poisoning and suffocation accidents, feeding and discharging must be carried out in strict accordance with the operating procedures.
(1) When the biogas digester is fed, it can only be fed from the feed inlet and the movable cover, and no one is allowed to enter the pool to refuel. If it is necessary to refuel in the pool, the residual gas in the pool must be exhausted, and only after there is enough fresh air can it enter the pool.
(2) When the biogas digester is discharged or maintained, firstly, the feed liquid is discharged from below the closed door, so that air convection is formed between the inlet and outlet and the movable cover, and the biogas digester is opened for several days. Before entering the pool, it is best to tie small animals (chickens, mice and rabbits) into the pool with ropes, and take them out after 15 minutes. If the activity is normal, it proves that there is enough air in the pool, and then people can enter the pool. At the same time, the swimming pool should also be looked after. The person who got off the bus for the first time tied a rope around his waist and left one end on the ground. To prevent suffocation symptoms, you can leave the pool in time.
(3) It is forbidden to put organic raw materials with high phosphorus content into the pond, such as oil tea cake, cottonseed cake and phosphate fertilizer (such as calcium superphosphate, calcium magnesium phosphate, etc.). ). Because these substances will produce highly toxic gases under absolutely oxygen-free conditions, which will poison people to death.
(4) In case of poisoning, emergency rescue measures should be taken.
(1) If someone is found fainting in the biogas digester, first of all, various measures should be taken to ventilate the pool body, such as blowing air into the pool with a blower, and removing residual biogas or other harmful gases as soon as possible. Never blindly enter the pool for rescue. When entering the pool for rescue, the personnel entering the pool must be tied with ropes. Before entering the pool, people should take a deep breath or have a snorkel in their mouth, and one end of the snorkel is placed outside the pool. Rescue action should be quick, don't panic, so as to avoid continuous poisoning.
(2) Move the rescued patient to a well-ventilated place, untie his chest or belt, and carry out artificial respiration. But pay attention to keep warm to prevent freezing.
③ Patients with respiratory or cardiac arrest should be given chest massage and artificial respiration. At the same time, respiratory stimulants, such as coramine and caffeine, are injected. Patients with spasms should be injected with sedatives, such as felagan and diazepam.
On the basis of the above measures, they should be sent to the hospital immediately for treatment.
3. Prevent burns, fires and drowning.
Biogas is a combustible gas, which can easily cause combustion and explosion in case of fire. Attention should be paid to prevent burns and fire accidents.
(1) When cooking with biogas, you must strike a match first, and then turn on the switch to release the biogas. If you turn on the switch first and then light it, methane will fill the kitchen. Once it catches fire, it will easily burn your hair, eyebrows and skin. Tighten the switch after use. In case of fire, the switch should be turned off as soon as possible, or the gas source should be cut off from the gas pipeline.
(2) When the biogas digester is discharged or maintained, open flames (such as lighted oil lamps and candles) shall not be brought into the biogas digester. It is best to use flashlights or electric lights for lighting, and smoking in the swimming pool is strictly prohibited.
(3) It is forbidden to burn fire around biogas digesters, air pipes and gas pipelines. It is also necessary to educate children not to play with fire near the entrance and exit to avoid fire.
(4) When you smell rotten eggs indoors (the smell of hydrogen sulfide in biogas), you should immediately open the doors and windows to let the indoor air circulate. Do not light it indoors. At the same time, turn off the main switch and timely check the leaking parts for maintenance.
(5) Strengthen the daily management of gas pipeline equipment. If the pipeline is broken due to rat bite and aging, it should be replaced in time. Lamps and stoves should not be close to flammable items such as firewood and clothes, and lamps and stoves should have a certain safe distance from the roof.
(6) In case of personnel burns, the patient should be sent to hospital for treatment in time.
(7) The inlet, outlet and movable cover of biogas digester should be covered to avoid drowning accidents caused by people and animals falling into the pool.
4, to prevent the pool explosion
Cement concrete is a fragile material, and methane burning in the pool is easy to cause explosion, so it must be very intentional.
(1) The newly-built biogas digester should be backfilled, and the test can only be carried out after the cement reaches the strength. The water inlet speed should be slow, especially when the water has been sealed, so as to avoid the water inlet speed being too fast, the pressure in the pool rising rapidly and bursting the tank. The test pressure should be controlled in the positive and negative water level difference 1000- 1200mm.
(2) It is forbidden to ignite and try to burn in the movable cover and air duct, and biogas should be led to the furnace for testing by air duct. Because the airway is ignited every day, it is easy to lead the fire into the pool to burn, which makes the gas expand violently, causing an explosion and destroying the pool body.
(3) Biogas burners are not allowed to be used when feeding and discharging, so as to avoid backfiring caused by negative pressure and damaging the tank.
(4) The pressure gauge measurement should not be too long, and the total range should be controlled within the positive and negative water level 1200mm.
(5) Clear the accumulated water in the gas transmission pipe regularly, otherwise the accumulated water will continue to increase after a long time, so that the air pressure in the pool cannot wash away the accumulated water, and the normal pressure cannot be reflected in the pressure. Table, there may be a danger of expanding the pool body.