The problem of biogas digester, major?

Household biogas digesters commonly used in rural areas in China are generally round, square and rectangular in shape. Practice has proved that the circular pool is the best and the most built at present.

Rural household biogas digesters are equipment for producing and storing biogas. Whether its quality and structural layout are reasonable is directly related to whether biogas can be produced, utilized and managed well. Therefore, the construction of biogas digesters should be reasonable in design, simple in structure, convenient in construction, durable and low in cost.

In some places, due to lack of experience, insufficient attention was paid to the construction quality of the pool. After completion, the pool leaked water and could not be used normally, making it a "sick pool". Some biogas digesters are too big and deep, with low effective utilization rate and inconvenient discharge. Years of practical experience has proved that the structure of biogas digesters should be "round" (circular pool), "small" (small volume) and "shallow" (pool depth); In the layout of biogas digesters, the "three combinations" (toilet, pigsty and biogas digester) are mostly used in the south, and the "four in one" (toilet, pigsty, biogas digester and solar greenhouse) is mostly used in the north.

How to build biogas digesters, the size and dimensions of biogas digesters, what materials are used in biogas digesters, and how to judge whether the quality of biogas digesters after repair meets the use requirements can be found in the following national standards, namely:

GB4750 Standard Atlas of Rural Household Hydraulic Biogas Pool;

GB475 1 quality acceptance standard for rural household hydraulic biogas digesters;

GB4752 operating rules for the construction of rural household hydraulic biogas digesters;

GB7637 "Operating Rules for Construction and Installation of Rural Household Biogas Pipelines";

GB9958 rural household biogas fermentation process specification;

GB7959 Hygienic standard for harmless feces.

You can also refer to the northern rural energy ecological model DB2 1/T-835-94 standard. Building biogas digesters is different from building private houses, and there are some special requirements. Therefore, the state has specially issued relevant technical standards (including relevant national standards in civil engineering) to ensure the construction quality of biogas digesters. If the quality of the pool is not up to the requirements or the foundation of the pool is not properly treated, the biogas digester will leak and leak, and it will not work normally, and it will be laborious to check the faults and maintenance costs.

China's biogas technology promotion departments have formed a network, and all provinces (autonomous regions), cities and counties have specialized agencies responsible for biogas promotion. In some towns and villages, biogas technicians are responsible for the promotion of biogas. If you want to build a biogas digester, you can find a local rural energy office (called biogas office in some places) and sign a contract to let them send biogas technicians to help you build a biogas digester. Because they have received special technical training and passed the examination to obtain the qualification certificate, the quality of the biogas digester can be guaranteed.

The materials for building biogas digesters are mainly cement, sand, stone and brick, and some prefabricated concrete members are needed or other molding materials are selected as water inlet and outlet pipes, pool covers, transmission and distribution pipes, lamps and cookers, etc.

Steps of building biogas digester:

(1) Check the terrain and determine the location of the biogas digester;

(2) Draw up the construction plan and draw the construction drawings;

(3) Prepare the materials for building the pond;

(4) pay-off;

(5) Earthwork excavation;

(6) formwork support (external formwork and internal formwork);

(7) concrete is poured and compacted, or brick masonry, or precast concrete slab assembly;

(8) maintenance;

(9) form removal;

(10) backfill soil;

(1 1) seal coat construction;

(12) Installation of gas pipe fittings, lamps and cookers for power transmission and distribution;

(13) pressure test and acceptance.

All localities should adjust measures to local conditions, use local materials, and do not insist on reunification.

The operation and management procedures of rural household biogas digesters are as follows:

1 and range

This regulation determines the technical requirements, safe use, common faults, causes, treatment methods, management requirements and responsibilities of rural household biogas digesters.

This regulation is applicable to the managers and users of rural household biogas digesters.

2, biogas digester operation technical requirements

2. 1 Start of biogas digester fermentation

2. 1. 1 Preparation of inoculum: Before the new pond is put into operation, sludge rich in biogas microorganisms or fermented concentrated solution of old biogas digesters with good gas production should be collected from ponds, sewers and sewage pits around the storage yard and put into the pond as inoculum, and the amount should be10-30% of the biogas digesters' feeding amount; Biogas digesters with large refueling capacity can leave 10-30% of the original fermentation broth as inoculum.

2. 1.2 Feeding: In spring, summer and autumn, the prepared livestock manure, grass, fallen leaves or chopped straw are mixed and piled for 2-4 days, or the grass, fallen leaves and straw can be chopped and used as livestock bedding for 5-7 days, and then put into the pond; If the first feeding is all feces, the concentration should be 3-5%; If straw is added, its concentration should be greater than 8%.

It is advocated to use feces as the main fermentation raw material.

2. 1.3 water seal: after the raw materials are put into the tank, water can be added to seal the tank; The water added to the biogas digester is preferably the original biogas digester water, sewage or pond and paddy water without pesticide pollution, and the dosage should exceed the edge of the communication port between the fermenter and the discharging room by 0.3m, and then the movable port cover plate is sealed with yellow mud with good viscosity. Water should be added to the aquifer frequently to keep it moist.

2. 1.4 deflate for fire test; In the early stage of fermentation, the content of non-combustible gases such as CO 2 is high and cannot be ignited, so it should be released intermittently until it can be ignited. The ignition test must be carried out on the stove, and it is forbidden to ignite at the gas duct of the biogas digester to prevent backfire and explosion. For biogas digesters in plastic greenhouses, ventilation tests should be carried out on lamps and stoves outside the greenhouse.

2.2 the daily management of biogas digesters

2.2. 1 Add new materials in time. Due to the low concentration at start-up, new materials should be added continuously. The biogas digester communicated with the pigsty and the toilet can take clean water from the discharge room to wash the pigsty and the toilet; Conditional farmers can bring fresh cow dung, pig manure or poultry manure into the pond, and farmers who have the habit of planting grass can pile grass and straw outside the pond for 1-3 days before adding them; The amount of fresh manure entering the pond every day is more than 50kg, and the biogas generated is sufficient, so there is no need to add grass and straw.

2.2.2 Timely stirring: stirring is an effective method to improve the gas production rate of biogas digesters and should be vigorously promoted. The mixing method comprises the following steps:

A. If there is a slag extraction stirring tube, stir it once a day after feeding, and the time is about 5- 10 minute.

B. For biogas digesters with manure as the main raw material, a bamboo woven conical shell-breaking net with a length of 1m and a diameter of 0.6m can be added in the center of the arch cover, which can not only increase the gas production capacity, but also break the shell.

C. the entrance and exit are all outdoors. After each feeding, 5 buckets of water can be scooped from the discharge room and washed into the pool from the water inlet.

D, use a long-handled dung spoon or a long rod with a wooden board nailed at one end to extend into the discharging room and stir for 5 minutes.

2.2.3 Rural household biogas digesters in cold areas should be insulated in winter, the pool surface should be covered with crop straws, and outdoor gas pipelines should be wrapped with warm things.

2.2.4 Regular inspection

A. Always check whether the sealing movable cover leaks, and repair it in time once it is found, so as to avoid fire; Each cover plate is damaged or lost, and should be replaced and repaired in time. For biogas digesters built outdoors, attention should be paid to whether the ground around the pool is cracked and whether the drainage is smooth. If there is any problem, pay close attention to it.

B. Always check whether switches, pipes and interfaces are leaking. If it is loose, broken or damaged, it should be repaired and replaced in time.

C always keep pressure gauges, lamps, stoves and other equipment in good condition and clean. Replace the pressure gauge in time when the water is insufficient or polluted, and repair and replace the stove in time when it is damaged.

2.2.5 When the fertilizer is used daily, it should be taken out from the discharge port before feeding on the same day. If the negative pressure exceeds 0. 1m, open the valve to avoid damaging the tank wall.

2.3 biogas digester emissions.

2.3. 1 biogas digesters with feces as the main raw material generally do not need large displacement; In biogas digesters with straw as the main raw material, the fermentation residue should be used in agricultural production with fertilizer and discharged once a year; Other raw materials and pond types shall be discharged according to the design requirements.

2.3.2 Stop feeding 7- 10 days before large discharge.

2.3.3 Before large-scale unloading, sufficient new materials should be prepared for quick unloading and fast forwarding.

2.3.4 Before a large amount of discharge, more than 65438 00% feed liquid should be reserved as the initial inoculum.

2.3.5 Before a large amount of discharge, the biogas digester can be used normally without maintenance. If water leakage or air leakage is found, it should be repaired in combination with large displacement. After the hydrostatic test, it can be restarted.

2.3.6 When discharging, the requirements of safety operation procedures must be strictly observed to avoid casualties.

3. Safe use of biogas digesters

3. 1 In order to ensure fermentation safety, stems and leaves that have just been sprayed with various toxic pesticides, livestock manure that has just been disinfected, and livestock carcasses that have died of poisoning cannot enter the pool; Drying oil, bone meal, cottonseed cake and substances with high phosphorus content are not allowed to be added into the biogas digester.

3.2 After the biogas digester is discharged and stirred, the import and export shall be sealed immediately.

3.3 When the biogas pressure is too high, use gas in time; When the pressure is too low, check the cause of air leakage as soon as possible and maintain it in time; When there is a large amount of feeding and discharging at a time, the gas transmission switch should be turned on.

3.4 It is not allowed to ignite the gas test at the gas channel of biogas digester, and it is not allowed to check whether the connector and switch are leaking with open flame; Soap water should be used for gas pipeline leakage inspection. If bubbles are found, they should be handled in time.

3.5 indoor found rotten preserved egg smell, no open flame. Doors and windows should be opened quickly, and the gas should be discharged to the outside by means of fans and blowers until the smell disappears, and then lamps and stoves should be used indoors.

3.6 Biogas lamps and stoves should be placed in safe, convenient and far away from flammable materials1m..

3.7 Safe Unloading and Maintenance

3.7. 1 The biogas digester that has been fed, whether it produces gas or not, is not allowed to be discharged or repaired.

3.7.2 When personnel need to discharge or maintain in the pool, the following procedures must be observed:

A. Open the movable cover plate to discharge the combustible gas in the pool; For biogas digesters without movable covers, the gas pipeline on the gas pipeline should be removed.

B. The operator should stand outside the pool and use the discharging tool to remove the feed liquid as much as possible, so that the opening is smooth, which is beneficial to the formation of air convection inside and outside the pool.

C blowing air into the pool manually or mechanically to update the air in the pool.

D release small animals (chickens, ducks, rabbits, cats, etc.). ) observation in the pool 15-30 minutes. If the animals are normal, people can enter the pool.

E. The personnel entering the pool should wear a firm safety rope under their armpits, and there should be special personnel outside the pool. If the person entering the pool feels a little uncomfortable, the nursing staff should immediately pull him out of the pool and rest in a ventilated and cool place.

F. Before entering the pool, lighting shall not be started at the mouth of the pool, and the personnel entering the pool shall not use naked light for lighting or smoking. If you really need lighting, you can only use a flashlight or a mirror to reflect light.

G. If the biogas digester is used normally, there is no need for discharge and maintenance, thus reducing the probability of accidents.

3.8 General rescue methods for accidents

3.8. 1 rescue of methane suffocation poisoning

A. Once the personnel in the pool suffocate and faint and cannot be rescued quickly, they should immediately adopt artificial methods to supply air to the pool and input fresh air; Never blindly enter the pool for rescue, so as not to cause continuous suffocation and poisoning accidents. After the air is updated, the personnel entering the pool shall abide by the provisions of Article 3.7.2, e.

B. Lift the asphyxiated person to a cool and sheltered place on the ground, unbutton his coat and belt, and keep warm; Serious patients should be sent to the nearest hospital for emergency treatment.

3.8.2 Emergency measures for biogas combustion:

A. put out the fire. People burned by biogas should take off their burning clothes quickly, or others should take various measures such as splashing water to put out the fire; Never pat with your hands, let alone run in panic and add fuel to the fire; If the pool is on fire, pour water from top to bottom to put out the fire and rescue people from the pool as soon as possible.

B. protect the wound. After the fire is put out, cut off the burnt clothes first, rinse the dirty things with clear water, and protect the wound or the whole body with clean clothes or sheets. Keep warm in cold season and send to hospital as soon as possible.

4. See table 1 for common failures, causes and treatment methods of biogas digesters.

Table 1 Common faults, causes and treatment methods

Treatment methods of common fault causes

The water column of the pressure gauge fluctuates up and down, and the flame combustion is unstable. There is water in the gas pipeline. Drain the accumulated water in the pipeline. Add a drainage bottle.

Turn on the switch, the pressure gauge drops sharply, turn off the switch, and the pressure gauge rises sharply. The airway is blocked or twisted at the corner, and the pipeline is poorly ventilated. Clear the airway and straighten out the pipeline.

Pressure gauge rises slowly or does not rise. A. leakage of biogas digesters or gas pipelines. B. insufficient fermentation raw materials. Inoculants for biogas fermentation are insufficient. Overhaul biogas digesters or gas pipelines. Add fresh fermentation materials. Increase the inoculation amount of biogas fermentation.

The pressure gauge rises slowly until it reaches a certain height. A. air box or pipeline leaks. B. there are water leakage holes in the feed pipe or discharge room. Overhaul the gas box and pipeline of biogas digester. Plug the water leakage hole between the water inlet and the water outlet.

When the pressure gauge is used, it rises quickly and falls quickly. There is too much fermentation broth in the pool and the volume of the gas box is too small. Take out some feed liquid and enlarge the gas box appropriately.

The pressure gauge rises quickly and has a lot of gas, but it doesn't burn for a long time. A. the inoculation amount of fermentation raw materials is small. B. abnormal fermentation. Exhaust the nonflammable gas in the tank, add inoculum or replace most of the feed liquid, and adjust the pH value.

Gas production was normal at first, and then decreased gradually or significantly. The gradual decline is nothing new. B. the obvious decline is the leakage of the pipeline. C the raw materials that have just been sprayed are filled in the tank, which affects the normal fermentation. Take out some old materials and add new ones. Check the air leakage in the maintenance system. Accumulate the collected raw materials for retching, and then re-enter the pool after the medicinal properties disappear.

Gas production is normal at ordinary times, and it will not suddenly produce gas. A. the movable cover was washed away. B. the gas pipeline is broken or disconnected. C. the gas pipeline was bitten by a mouse. D. Pressure gauge leaks. E. the pool suddenly leaks and leaks. F. The valve is not closed or not closed correctly after use. Reinstall the removable cover. Connect the gas pipeline. Replace the damaged pipeline. Repair the pressure gauge. Check and repair. Close the valve after using gas.

Gas production is normal, but the combustion firepower is small or the flame is red and yellow. A. Low firepower is the blockage of the fire hole in the cooker. B. The red and yellow flame indicates that the fermentation broth in the tank is too acidic and the methane content of biogas is low. C. unreasonable air coordination. Clean the fire hole in the stove. Plant ash, lime water or cow dung are added appropriately, and some old materials are taken out to supplement new materials; Adjust the air adjusting plate of the furnace.

The gas production is normal, the furnace is in good condition, but the firepower is insufficient. The mixed air of biogas stove is insufficient. Adjust the air adjusting plate of the furnace.

The biogas lamp doesn't turn on or go out. A. biogas has low methane content and unstable pressure. B. the nozzle diameter is not suitable. C. gauze will get wet if it is covered for a long time. D. nozzle is blocked or deviated. E. there is water in the gas pipeline. F the model of the mesh hood does not match the required pressure of the biogas lamp. Increase fermentation raw materials and inoculation amount, and improve biogas production and methane content. Select the appropriate nozzle and adjust the intake valve. Select 100-300 quality veil. Dredge and adjust the nozzle. Drain the accumulated water in the pipeline. Place the drain bottle.

5, management requirements and responsibilities

5. 1 The household biogas digesters provided to farmers shall conform to the Quality Acceptance Standard for Rural Household Hydraulic Biogas Digesters (GB 475 1-84), Operating Rules for Rural Household Hydraulic Biogas Digesters (GB 4752-84) and Operating Rules for Pipeline Construction and Installation of Rural Household Biogas Digesters (GB 7637-87).

5.2 In the design and management of rural biogas digesters, we encourage the popularization and application of new biogas digesters, new technologies, new processes and new materials that have been identified and approved by the competent departments of rural energy and biogas construction above the region.

5.3 Biogas management personnel should pass the biogas technical training organized by the competent department at or above the county level, and pass the examination, and obtain the certificate of completion (or employment certificate).

5.4 Management personnel conditions

5.4. 1 junior high school education.

5.4.2 Engaged in biogas construction or management for more than three years, with management experience, full of enthusiasm for biogas industry and serious and responsible work.

5.4.3 Familiar with and master biogas management technology, basic knowledge of biogas comprehensive utilization and common fault handling methods.

5.5 Responsibilities of management personnel

5.5. 1 Teach users the basic knowledge of management, use and safe operation of biogas digesters.

5.5.2 According to the requirements of biogas fermentation process, guide users to collect fermentation inoculum and pretreat fermentation raw materials, ensure normal start-up and operation, and guide daily use and management.

5.5.3 Guide users to check (diagnose) and deal with common faults of biogas digester system. Guide users to use the comprehensive utilization technology of biogas, biogas residue and biogas slurry to improve economic benefits.

5.5.4 Pay attention to collecting and reflecting users' opinions and usage, and summarize the good experience of biogas management in time.

5.6 User Responsibility

5.6. 1 Learn and master the basic knowledge of biogas management and use and the basic skills of safe gas use.

5.6.2 According to the requirements of biogas fermentation process, collect culture inoculum and prepare enough fermentation raw materials for starting biogas digesters; In use, it is necessary to feed, discharge, check and stir frequently.

5.6.3 According to the opinions of biogas management personnel, timely maintain and update biogas equipment to ensure the safe use of biogas.

5.6.4 Learn and master the comprehensive utilization technology of biogas, actively carry out comprehensive utilization of biogas, and improve the economic benefits of running biogas.

The above contents are for reference only.

Safety matters are as follows:

1. During the start-up and operation of biogas digester, ventilation test should be carried out on biogas digester. Do not conduct ignition test directly on the gas channel of biogas digester to prevent explosion.

2. When using gas, you should ignite the gas before turning it on (except for the electronic ignition biogas stove), and turn off the biogas pipeline switch immediately after using the gas.

3. Don't pile up flammable materials such as firewood near the biogas stove. The distance between the biogas lamp and the roof (especially wooden houses and huts) should be more than 70 cm. In case of fire caused by biogas combustion, the airway should be blocked immediately and the gas source should be cut off. Children must be taught not to tamper with biogas facilities at ordinary times, let alone play with fire near biogas digesters.

4. Users should always open windows for ventilation and check the sealing condition of gas transmission pipelines. Once the smell of rotten chicken bile is found indoors, it is methane leakage. Immediately open the doors and windows for ventilation. After the smell is removed, immediately check the leaking part and repair the available gas.

5, when using biogas combustion, don't man-made emissions, especially not fast emissions, so as to avoid negative pressure tempering caused by methane tank explosion.

6. The import and export of biogas digesters should be covered with plates to prevent people and animals from falling into them. The top of the biogas digester should avoid the impact of heavy objects or the extrusion of cars to prevent collapse.

7. It is forbidden to add highly toxic pesticides and various pesticides, fungicides and calcium carbide to the biogas digester, so as not to destroy normal fermentation or even stop gas production.

8, in order to prevent the harm of hydrogen sulfide in biogas to human body, and the corrosion of metal appliances, desulfurization device should be installed.

9, big refueling or into the pool maintenance should pay attention to prevent poisoning. Before people enter the pool, they must first open the movable cover for ventilation (make a danger sign immediately) to eliminate the biogas in the pool, and then put the small animals into the pool for testing. Only when no abnormal reaction is found can you enter the pool for operation. People must fasten their seat belts when entering the pool, and the top of the pool should be guarded, just in case.

There are two types of cylinders on the ground: vertical and horizontal. Feeding must be carried out with a hoist, and dry fermentation is generally used. Now it is basically a one-step assembly structure, which is convenient to transport. The price of 200 cubic meters is about 80 thousand yuan. You can help if necessary.