Reasonable use of soft biogas digester equipment Scarborough Biogas reminds you

The rational use of biogas

The use of biogas is very extensive. For farmers, the main use is for cooking fuel and direct lighting. Therefore, whether the correct selection and use of biogas supporting products is the key to whether the biogas benefits can be fully utilized. Therefore, we should grasp the correct and reasonable use of methods in order to achieve a multiplier effect.

Products commonly used for biogas include biogas stoves, biogas lamps, biogas pressure gauges, biogas switches, direct-flow, three-way, and gas pipelines. In addition, there are biogas igniters, biogas gas-water separators, Biogas desulfurizers, biogas water heaters, biogas rice cookers, etc.

The following describes the rational use of biogas products.
(I) Gas pipeline

The gas pipeline ensures that the biogas produced by the biogas digester can be smoothly sent to the biogas stove or the biogas lamp for combustion. The main quality requirements for biogas gas pipelines are that they can withstand pressures of 10 kPa (1000 mmH2O) without leakage, ageing resistance, and tensile resistance. Therefore, the use of biogas gas pipeline should be selected qualified plastic gas pipeline.
Before installation, check whether the gas pipe leaks, especially the buried gas pipe must be checked.
Inspection method: Put the tube in water, block one end of the nozzle, use a pump to inflate or inflate the other end, and observe whether there are any bubbles around the tube. If there is no air bubble, the gas pipe will not leak. The leak is made when it is issued.
The size of the inner diameter of the gas pipeline depends on the volume of the digester, the gas distance and the application. For example, if the volume of the biogas digester is large, the gas volume is large, and the gas distance is long, the internal diameter of the gas pipeline should be larger. The biogas digester used by general farmers should have an internal diameter of 8-10 mm. Internal diameter less than 8 mm cannot be used. For large biogas tanks used for power, due to the large gas consumption, the internal diameter of gas pipelines should be more than 20 mm.

Plastic (or rubber) air ducts exposed outdoors are subject to ageing and cracking due to long periods of exposure to the sun and rain. Placing a plastic pipe (or bamboo pipe) on the outside of the gas pipe can extend the service life. The buried gas pipelines can also be sheathed with plastic pipes, iron pipes or brick trenches.

The gas pipeline should be reasonable. If there is a slope, tilt 0.05% toward the direction of the biogas, and the best length is shorter, the longer the tube is cut off, do not circle, hang on the wall or other places, this is equal to the growth of the pipeline distance and the pressure of the biogas The loss increases.

Recycled plastic tubes are not permitted as gas lines.

(b) Switch

The function of the switch is to open or close the biogas transmission channel, and at the same time, the biogas flow rate can be adjusted. It is an important part of the gas pipeline. It must be sturdy, tight, fast, flexible, and easily accessible. Switch material is divided into two major categories of plastic and metal.

The plastic switch usually adopts the compression degree of the pressure gas pipeline to control the biogas flow, completely deflate the gas pipeline, is in a closed state, the gas pipeline is fully loosened, is in the open state, and is also the state with the largest amount of biogas transportation. Because biogas gas pipelines are not easily compacted, latex tubes are usually used. However, latex tubes are not resistant to corrosion and are prone to ageing. After several months of use, cracking, blocking, etc. may occur, and there may be leaks and insecurity.

Plastic switches also have the following problems:
1. Easy to wear

2, the seal is not good, resulting in leakage
3, processing is relatively coarse, the hole is often frizzy

4. As a result, the pressure loss of biogas increases and the flow decreases.
5, the switch handle is too tight, easy to operate.
Due to the above reasons, plastic switches have gradually been replaced by metal switches. Metal switches can be made of steel, copper, aluminum and other materials. The opening and closing is performed by using the rotation of the cone or core with the open hole, and the operation is simple and the action is rapid. In the selection of these switches, the cock diameter should be greater than 6 mm. At the same time, the cock hole is required to be concentric with the inlet and outlet. When the switch is opened, the hand sensing is flexible.

It is reasonable and safe to install a switch in front of each stove or lamp. Some users installed the main switch behind the air duct and installed switches at the bifurcation of the pipeline. This is completely unnecessary. Each switch installed more than one, not only more money, but also the more switches and gas pipe joints, the more chance of gas pipe leakage, the same time, the greater the pressure loss of biogas, easily lead to the pressure of the biogas stove can not reach the stove The design requirements will affect the ignition, reduce the thermal efficiency and heat flow of the cooker, and fail to achieve the intended use of biogas.

(a) pressure gauge

The pressure gauge is an indicator instrument to observe how much biogas is in the digester. At present, most pressure gauges used by farmers are U-glass tube type liquid level pressure gauges. The pressure gauge has a simple structure, high sensitivity and low price, but glass The tube is easily broken during transportation. After a period of use, the indication value is inaccurate due to temperature changes. The scale is fuzzy and difficult to read. When the pressure in the digester increases rapidly, the U-type pressure gauge liquid will be washed away. If you deal with it in time, it is prone to safety incidents. Membrane-type pressure gauges that have been used gradually have rapidly replaced U-type pressure gauges due to their small size, beautiful appearance, light weight, and high sensitivity. At the same time, a new type of glass straight-tube pressure gauge has been introduced to the market. The tube pressure gauge is small, corrosion resistant and intuitive.

The main function of the pressure gauge is to check whether the digester and the gas pipeline are leaky. Another function is to adjust the flow according to the pressure when the gas is used, so that the stove can work under the optimal conditions, but the inspection of the digester can only leak gas. Capsule pressure gauges cannot be used with U-type gauges.

The correct installation position of the pressure gauge should be on the gas pipeline between the stove switch and the biogas stove. In this way, the switch is opened, the pressure rises, the switch is turned off, and the pressure drops. This facilitates the monitoring of the working condition of the cooker. When using, it is necessary to control the cooking pressure of the cooking appliance as much as possible, so that it is not too overpressured in operation, especially in order to avoid too much pressure. The artillery will be out of the pot and waste gas.

Note: When there is a large amount of biogas in the biogas digester, that is, the gauge indicates that the gauge pressure limit is 10kpa. At this time, the biogas should be used or stored as soon as possible to protect the pressure gauge and the biogas digester, so as to avoid the table from being damaged or the biogas tank seal cover being washed away. Inflated pressure damage the pool wall.

(4) Gas-water separator

At present, gravity-type gas-water separators are used more often. The principle of the separator is that the biogas produced by the biogas digester is imported into the tube by a gas-water separator. After entering the tube body, the cross-sectional area of ​​the instrument body is much larger than the cross-sectional area of ​​the inlet tube, resulting in a sudden drop in the biogas flow rate due to the lack of specific gravity of water and gas. In the same way, the falling speed of the water drop is greater than the rising speed of the air flow, and the water sinks to the bottom of the device and the biogas rises to be output from the outlet pipe.

If there is no gas-water separator, there will be blisters in the gas pipeline when the gas stove is burning, and the flame of the gas stove will be rushed down quickly. Like gasping, the gas lamp often flashes. The reason for these conditions is that the water vapor in the biogas accumulates in the tube or causes negative pressure during large discharge. The water in the pressure gauge is poured into the gas pipeline. In serious cases, the stove and the lighting fixture will not ignite. If a gas-water separator is installed, this problem can be solved. The gas-water separator should be installed at the lowest point of the gas pipeline.

(five) Desulfurizer

Biogas contains a certain amount of hydrogen sulfide. Hydrogen sulfide is an acid gas. It is corrosive to pipelines, switch valves, instruments, and other equipment. It also has a corrosive effect on household appliances. In order to ensure normal gas supply and extend the service life of the equipment, desulfurizers must be installed in the gas pipelines.

There are two methods of desulfurization: wet and dry desulfurization. Dry desulfurization has the advantages of simple process, mature and reliable, low cost, and can achieve good purification effect. Current home biogas desulfurizers basically use this method.

Dry desulfurizers include activated carbon, zinc oxide, manganese oxide, molecular sieves, and iron oxides. Considering the operating time, temperature, pollution, price, and other factors, the most commonly used desulfurizer is iron oxide (Fe2O3).

After the desulfurizer has been used for a period of time, the desulfurizer in the desulfurizer will turn black, lose its activity, reduce the desulfurization effect, and may also cause compaction and increase the biogas transmission resistance. In severe cases, the biogas will be blocked and cannot pass. At this point, the desulfurizer must be regenerated. The regeneration method is to remove the deactivated desulfurizing agent and evenly and loosely deposit it on a flat, clean, back-yang, ventilated site, often turning the desulfurizing agent so that it is in full contact with the air to oxidize and regenerate. When the moisture content of the desulfurizer is low, the dilute alkaline solution can be uniformly sprayed to accelerate the regeneration speed and shorten the regeneration time. Generally, after about one month, the desulfurizer can be loaded into a desulfurizer and used continuously. Desulfurizer can be regenerated 1 or 2 times. Note that when the digester is refueled, the switch in front of the desulfurizer must be closed to prevent the air from passing through the desulfurizer because when the digester is refueled, the gas passing through the gas pipe to the desulfurizer is not biogas but oxygen-containing gas. Once the desulfurizer is directly introduced into the desulfurizer, the desulfurizer undergoes a chemical reaction and the temperature rises sharply, which can damage the plastic housing of the desulfurizer and cause the desulfurizer to be unusable.

(VI) Biogas stove
1. Composition of biogas stoves

The biogas stove we use is an atmospheric combustion type biogas stove. The atmospheric type biogas stove is mainly composed of a nozzle, an assembly, an air conditioning plate, an ejector and a combustion head. The role of the nozzle is to deliver the biogas needed for combustion and control the biogas flow (ie load). The caliber of the nozzle gradually shrinks from large to small. It is a key part of converting the static pressure of the biogas into kinetic energy, and it also brings in air at the same time as the biogas is ejected. The nozzle is generally made of copper, and the machining accuracy is high. The nozzle design and processing technology directly affect the burner performance and use effect. The nozzle is usually fixed on the assembly.

The function of the assembly is to operate the opening and closing of the biogas, control the flow of the biogas, the transfer of pressure and size, and the assembly is equipped with an automatic ignition device, which is an important part of ignition and flow regulation. The shell of the assembly is generally aluminum casting, the center has a copper cone, the cone has two holes, a Φ5, Φ0.5, when the knob to drive the cone to rotate to block the big hole, the biogas can only Through the small hole into the head of the burning that is the center of small fire burning, the normal use of small fire or fire at the same time burning.

The function of the air conditioning plate is to adjust the primary air volume (primary air factor a?) according to the flow rate of biogas, the pressure change, and the size of the biogas calorific value. During use, the air conditioning plate must not be closed, otherwise, atmospheric combustion It becomes diffused combustion (primary air coefficient a? = 0) diffusion combustion has the following disadvantages:
(1) The combustion is incomplete and the CO content in the combustion flue gas is high. It not only wastes biogas, pollutes the environment, but also harms human health.
(2) The combustion temperature is very low, the flame temperature is generally only 300 °C -400 °C, and the atmospheric combustion temperature can reach more than 1000 °C.
(3) Flaming, light and powerless like burning firewood. It seems that the flames are very large and very high, but in fact they are some of the flames that are not high in temperature and flutter outside the pot and lose a lot of heat.
(4) Low thermal efficiency. According to measurements, the thermal efficiency of diffusional combustion is only 50% or even lower.

The role of the ejector is to rely on the amount of air injected by the biogas emitted from the nozzle, and the biogas and the air are evenly mixed, and the mixed gas is formed in the outlet hole of the burner head to maintain the necessary speed to ensure stable combustion. .

The role of the combustion head is to evenly distribute the mixed gas of methane and air to each fire hole for stable and complete combustion.

2, the choice of biogas stove Choose home cooking things, be sure to buy the product quality inspection structure inspection qualified products, do not buy unexperienced stove or unqualified stove. At the same time, we should also consider the heat flow, thermal efficiency, and use pressure of the stove in conjunction with the family.

The heat flow of the stove refers to the amount of heat released by the biogas stove in accordance with the design pressure during the 1 hour. She stated that the heating capacity of the stove is in the unit of kilowatts, which is one of the main technical indicators of the biogas stove.

The national standards for household gas stoves stipulate that the heat flow rate is set at 2.33 kilowatts, 2.79 kilowatts and 3.26 kilowatts. If the calorific value per cubic meter of methane is lower than the calorific value of 21,000 kilojoules, it is equivalent to 0.4-0.56 standard cubic meters of methane gas consumed per hour. Farmers can determine the heat flow of stoves according to the number of their families, their standard of living, and their gas use standards.

3. The use of biogas stoves

Before using the biogas stove, you should read the instructions and the nameplate on the stove to understand the rated pressure and heat flux of the biogas stove. When used, adjust the pressure before the stove to make it equal to the rated pressure of the biogas stove. In order to achieve the thermal efficiency of the gas stove.

Because of the different feed quantities, raw material types, tank temperatures, and design pressures for each biogas digester, the methane content of the produced biogas and the biogas pressure are also different, so the calorific value and pressure of biogas are also different. Biogas combustion requires 5-6 times more air, so the degree of opening of the air-conditioning panel (behind the front panel of the biogas stove) should be adjusted with the amount of methane in the biogas. When the methane content is high, the air-conditioning plate can be opened to make the biogas burn completely to obtain high heat efficiency. If the air deflector is opened too much and too much air is blown in, the phenomenon of falling flame or even off-fire will occur (that is, when the pot is not released, the fire is not burned above the combustion head and is not connected with the combustion head fire hole); Part of the heat taken away by the flue gas will also reduce the thermal efficiency of the cooker. When the methane content is low, the wind deflector can be turned off slightly, but the wind deflector must not be shut down, so that the flame seems long and weak. After the wind deflector dies, no air enters the stove, and once the air is equal to zero, a diffused combustion is formed. As a result, the flame temperature is low, combustion is incomplete, and excess carbon monoxide is generated, affecting human health.

Therefore, when using a biogas stove, it is necessary to adjust the size of the damper by correctly grasping the color and length of the flame. Learning to use the air conditioning plate is an important part of whether the farmer can use the biogas stove correctly.

Some farmers prefer to use the stove on the stove. If the time of use is long, the oven will reach the thermal equilibrium with the stove after heating. This will continue to be used, which will increase the thermal efficiency of the stove. However, if the use time is short, the heat efficiency of the cooker will be reduced due to the heat absorption from the furnace wall. So whether the stove is placed in the furnace is beneficial, depending on the circumstances. In addition, the furnace must be well-ventilated and can quickly remove the fumes, which can meet the needs of the cooking appliances to use the secondary air supply. Therefore, the hearth and stove doors should be properly increased. It is recommended that you do not use the gas stove in the furnace.

4. Biogas stove electric ignition

For ease of use, biogas stoves are equipped with electronic or pulse ignition. When the ignition is on, press the switch button and hold it for 3-6 seconds. Turn it to the “ON” position and make sure that the stove is turned on before you let go. If you leave the stove and the fire goes out, repeat the above ignition method. The frequency of electrical ignition problems is relatively high. On the one hand, the quality of the electrical ignition device of the product is defective, and on the other hand, the conditions of use are not suitable. If methane is less than 50% methane, the pressure in front of the stove is too high, the amount of battery is not enough, and moisture may not be on fire. Under normal circumstances (after deducting the quality of the cooking stove ignition device), the pressure before the stove is controlled and the ignition should be no problem.

(7) Biogas water heaters

Biogas water heaters are much more complex than biogas stoves and biogas lamps because of the large gas consumption of gas water heaters, the use of gas for centralized gas supply by users, and the use of solvent-based water heaters for winter aquaculture products for warm water. A single biogas digester uses water heaters. Fewer users, as long as there is enough biogas, while paying attention to safety, can also use biogas water heater products.
1. Composition of biogas water heaters Biogas water heaters consist of water system, gas system, heat exchange system and flue gas removal system.

The main components:
The main burner, water and gas linkage valve, lead or burn it, solenoid valve, heat exchanger, combustion chamber, exhaust chamber and other components.

2. Matters needing attention when using biogas water heaters:

If the biogas water heater fails, it must be repaired by a professional; therefore, the working principle of the components of the biogas water heater is not introduced. However, due to the large amount of gas consumed per unit time, the water heater needs more fresh gas to be added, and it is the first place in safety when it is used.
1 installation

The water heater should be installed in a place close to the gas pipeline and the water pipe and able to ventilate (it can supply the water heater with sufficient oxygen for combustion). The connection between the water pipe and the gas pipe must be buckled and fastened to prevent the gas pipe from being pressurized when the gas or water pressure is high. Or water hoses open.
2 out of hot water

From the "Ignition Viewing Hole", confirm that the fire is lit, open the cold water valve, the fire is burning, and the water flows from the hot water outlet. After a few seconds, the hot water can be used.
3 water temperature regulation

The water temperature of the water heater is determined by the size of the fire and the size of the water. When the size of the fire is adjusted, the temperature of the outlet water is adjusted by the "water temperature adjustment knob", the water is opened and the outlet water temperature is low, the water is opened small, and the outlet water temperature is high (never adjust the hot water temperature higher than 60 °C, In case of heat exchanger fouling). When the size of the water is adjusted, the temperature of the outlet water is regulated by the “gas adjustment knob”, the fire is opened, the outlet water temperature is high, the fire is small, and the outlet water temperature is low.
4 suspension of use

Suspend the use of water heaters, just close the "cold water method" that is no hot water flow out, the fire automatically extinguished (but the fire is still burning) If you need to use hot water, then open the cold water method, the fire automatically burns, hot water is coming.
5 stop using

Close the "gas valve" and then close the "cold water valve" to confirm that the water vapor is turned off before people can leave.

(8) Biogas rice cookers Biogas rice cookers are similar to rice cookers and can cook 2.5 kilograms of rice at a time, which is economical and convenient.
1. The composition of biogas rice cooker

Biogas rice cookers mainly include a temperature sensor, a juice receiver, a main fuel switch, and an insulation switch. There are also lids, inner pots, hoods and other components.

2. The use of biogas cookers

1 The rice cooker should be placed in a smooth and ventilated place, 10 cm away from the wall, 50 cm above the height, and not near other flammable and explosive materials.
2 care to use the inner pot, do not make it deformed.
3 When installing, insert the gas hose of Φ9.5 into the air inlet of the rice cooker and secure it with the pipe clamp.
4 First, bring the main combustion and heat preservation switch to the upper end, and then press the switch. When the ignition is fired, lift the windshield and re-ignite it. After confirming that the fire has been normal, place the windshield within the hood and leave it.
5 Lightly press down the main burning insulation switch, and the pulse-ignited rice cooker will emit continuous firing sound for about 5 seconds. (Electronic ignition fired rice cooker should be pressed after reaching the end point, stay for 1-2 seconds and then press rotation Twist and give out a fear. The fire ignites.
6 Sometimes, because there is air in the pipeline and it doesn't ignite, it can be turned on and off repeatedly until it catches fire.
7 After the rice is cooked, the main burner is automatically turned off and enters the keep-warm state. After the insulation is completed, the heat-insulated switch must be referred to the upper-end home position to turn off the gas switch.
8 pulse ignition rice cooker, install a section of the 5th battery prior to activation.

(9) Biogas Lamps

Due to safety hazards, biogas lamps are generally not recommended.

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