The main purpose of biogas purification is to remove carbon dioxide and obtain high-purity methane. Biogas purification technology mostly comes from the decarbonization technology of natural gas and synthetic ammonia. Since the treatment capacity of biogas is far less than that of natural gas or synthetic ammonia, more attention should be paid to miniaturization and energy saving in the selection of decarbonization technology. At present, biogas purification technology can be roughly divided into adsorption, absorption, membrane separation and low-temperature purification.
Widely used biogas purification technologies mainly include pressure swing adsorption, water washing, physical absorption of organic solvents, chemical absorption of organic solvents, high-pressure membrane separation and low-temperature purification. The following table shows the key parameters of six biogas purification technologies.
Pressurized water washing method is most used; In Germany, PSA is more extensive; In the Netherlands, pressurized water washing, pressure swing adsorption and membrane separation technology are widely used. The following table shows the economic comparison of five biogas purification technologies.
Note: power consumption cost (12 ~ 18 euro cents / kWh), heat consumption cost (3 ~ 5 euro cents / kWh), water cost is 5 euro / M & sup3; (including sewage treatment fee). Further treatment cost (such as separation of siloxane or ammonia) is not considered. All values are based on full load operation.
The cost of biogas purification is related to the methane content of feed gas and finished products. The cost of raw biogas purification with high methane content is lower. This is mainly due to the increase of energy output, and the total cost is related to the high energy level. The actual energy consumption can be reduced by improving the efficiency (reducing the energy consumption per unit output) and using the original biogas with high calorific value, so as to reduce the cost.
The economic benefit of biogas purification station is also related to other factors, such as operability and rated load. The rated operating load of biogas purification station not only depends on the high stability of the purification station itself, but also related to the original biogas flow and the reliability of subsequent units (such as charging station and gas filling station).
With short shutdown time and good equipment operation, the equipment can operate normally and continuously under the condition of rated load and sufficient feed gas. It is an efficient and available standard for biogas purification station. Fast response time is very necessary, so it is very important for technology suppliers to provide good network services. In addition, remote monitoring can also be adopted. When the operation is interrupted, technicians can directly find the fault and take necessary remedial measures immediately according to the fault type, so as to avoid time delay and do not need service technicians to travel long distances to the site to solve the problem.
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