What to prepare for building biogas
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.
(1) Gas pipelines Gas pipelines are used to ensure that the biogas generated by the biogas digesters can be smoothly sent to the biogas stoves or biogas lamps 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) 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. Seal not 3. Good, 4. Cause air leakage, 5. The processing is rough, the inner hole is often frizzy, 6. The pressure loss of biogas increases, 7. The flow rate decreases; 8. Switch Handle is too tight, 9. Inconvenient 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.
(3) Gauge pressure gauges are indicator instruments for observing the number of biogas in a biogas digester. At present, most of the pressure gauges used by farmers are U-glass tube type liquid level pressure gauges. The pressure gauge has a simple structure and is highly sensitive to use. The price is low, but the glass tube is easily broken during transportation. After a period of use, the indication value is inaccurate due to temperature change, and the scale is fuzzy and difficult to read. When the pressure of the biogas tank increases rapidly, the U-type pressure gauge liquid will be If you don't deal with it in time, it is prone to safety accidents. 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. At the same time, when using, it is necessary to control the use pressure of the cooking appliances as much as possible, so that it is in the design pressure, in particular should not be excessive overpressure operation, so as to avoid too much pressure, the fire running out of the pot, a waste of biogas.
Note: When there is a large amount of biogas in the biogas digester, the pressure gauge indicates that the pressure limit is 10kpa. At this time, the biogas should be used as soon as possible to protect the pressure gauge and the biogas digester, to prevent the table from being damaged or the biogas tank seal cover being washed away, and the pressure collapse tank. Wall incident.
(4) Gravity gas-water separators are currently used for gas-water separators. 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.
(5) Desulfurizer Biogas contains a certain amount of hydrogen sulfide. Hydrogen sulfide is an acid gas. It is corrosive to pipelines, switches, valves, 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. The composition of the biogas stove The biogas stove we use is an atmospheric combustion type of biogas stove. The atmospheric biogas stove is mainly composed of five parts: the nozzle, the assembly, the air conditioning plate, the ejector and the 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.
The following describes the rational use of biogas products.
(1) Gas pipelines Gas pipelines are used to ensure that the biogas generated by the biogas digesters can be smoothly sent to the biogas stoves or biogas lamps 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) 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. Seal not 3. Good, 4. Cause air leakage, 5. The processing is rough, the inner hole is often frizzy, 6. The pressure loss of biogas increases, 7. The flow rate decreases; 8. Switch Handle is too tight, 9. Inconvenient 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.
(3) Gauge pressure gauges are indicator instruments for observing the number of biogas in a biogas digester. At present, most of the pressure gauges used by farmers are U-glass tube type liquid level pressure gauges. The pressure gauge has a simple structure and is highly sensitive to use. The price is low, but the glass tube is easily broken during transportation. After a period of use, the indication value is inaccurate due to temperature change, and the scale is fuzzy and difficult to read. When the pressure of the biogas tank increases rapidly, the U-type pressure gauge liquid will be If you don't deal with it in time, it is prone to safety accidents. 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. At the same time, when using, it is necessary to control the use pressure of the cooking appliances as much as possible, so that it is in the design pressure, in particular should not be excessive overpressure operation, so as to avoid too much pressure, the fire running out of the pot, a waste of biogas.
Note: When there is a large amount of biogas in the biogas digester, the pressure gauge indicates that the pressure limit is 10kpa. At this time, the biogas should be used as soon as possible to protect the pressure gauge and the biogas digester, to prevent the table from being damaged or the biogas tank seal cover being washed away, and the pressure collapse tank. Wall incident.
(4) Gravity gas-water separators are currently used for gas-water separators. 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.
(5) Desulfurizer Biogas contains a certain amount of hydrogen sulfide. Hydrogen sulfide is an acid gas. It is corrosive to pipelines, switches, valves, 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. The composition of the biogas stove The biogas stove we use is an atmospheric combustion type of biogas stove. The atmospheric biogas stove is mainly composed of five parts: the nozzle, the assembly, the air conditioning plate, the ejector and the 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.
Knee Warmer is using batteries as power supply, to reduce pains of the knees. It provides stable heat penetrating so as to relax fatigue caused to the knees.
It is always with velcro for fastening better, which also enhance the heat therapy effect, as it touches better to human knees.
Below picture for reference, it can be made in different shapes and designs.
Knee Warmer
Knee Warmers for Arthritis, Specialized Knee Warmers, Electric Knee Warmer, Thermal Knee Warmer
Ningbo JustLive Electrical Appliance Co., Ltd , https://www.makeheat.net