In view of the global fossil fuel depletion crisis, the development and application of biomass fuel has become the focus of attention. Among them, biogas and biogas, as renewable energy, have the characteristics of low utilization cost and no pollution to the environment. They are high-quality environmental protection fuels instead of conventional fossil energy. With the rapid development of large-scale biogas and biogas projects, the demand of biogas desulfurization and purification to high value-added biogas is increasingly urgent, and the biogas purification technology has been applied and developed in different degrees.
Desulfurization technology of biogas purification and purification
The common processes used for biogas desulfurization at home and abroad are dry desulfurization, PSA desulfurization, chemical desulfurization, biological desulfurization, membrane separation desulfurization, etc. In the field of biogas purification and purification, there are mainly activated carbon or iron oxide dry desulfurization, alkali washing desulfurization and biological desulfurization. Meanwhile, bio desulfurization can only be used for biogas power generation but not for biogas purification because of the introduction of impurity gases such as oxygen and nitrogen into the feed gas. The following describes the desulfurization skills and characteristics in biogas purification:
1 dry desulfurization
Dry desulfurization is the conversion of gaseous sulfide to solid sulfide by solid desulfurizer, which is characterized by simple equipment manufacturing, simple operation, high purification degree and renewable desulfurizer. But the disadvantage is that the value is very low, and it needs to be replaced after reaching the saturated sulfur capacity. It is generally used for gas desulfurization with small gas volume, low hydrogen sulfide content and deep desulfurization demand, and has certain requirements for air temperature and water content. Desulfurizer is generally divided into activated carbon system, iron oxide system, zinc manganese system. The desulfurizer is mostly fixed bed, which is used in series. The used desulfurizer can be burned with coal or recycled by the manufacturer.
2psa and membrane separation desulfurization
The principle of PSA is to separate different gases with different adsorption rate and amount under different pressure. The separation rule of membrane is to use the gas molecules with different sizes to selectively penetrate the membrane and different gas penetration rates to complete gas separation. The hydrogen sulfide separated from these two methods needs to be reprocessed, and at the same time, it will bring great loss to methane gas.
In addition, the membrane used in membrane separation method should be replaced frequently with high operation cost, while the PSA and chemical absorbent can be recycled, so the practical application of PSA on membrane separation technology is more extensive.
3 alkali washing desulfurization
Alkali washing desulfurization refers to the use of alkali liquor circulation for desulfurization, which can be divided into chemical method and biological method according to different regeneration methods. The two methods are the same in desulfurization, sulfur treatment, alkali preparation and other processes. The process of catalyst regeneration is called chemical regeneration desulfurization, and the process of biological bacteria regeneration is called biological regeneration desulfurization.
In addition to the different regeneration methods, the main application fields of the two methods are also different. In the meantime, the biological regeneration alkali washing desulfurization process has certain application in the gas pretreatment process of biogas power generation, but not in the actual project of gas hydrogen sulfide removal of biogas refined natural gas. The chemical regeneration method is relatively more widely used.
5 biological desulfurization
Biological desulfurization process is a new type of desulfurization process, which is more and more popular in enterprises. The basic principle of biological desulfurization is to use the metabolism effect of Thiobacillus and thiomyces to synthesize hydrogen sulfide and oxygen into sulfate and then remove hydrogen sulfide in biogas, and the desulfurization product is sulfate.
Although it is convenient to use and low in operation cost, due to the introduction of impurity gas in the desulfurization process, it can not be removed in the subsequent process. At the same time, the biological desulfurization is just in its infancy and the skills are not mature. Most of the imported skills and equipment are used, so the investment cost is relatively high, about 3-5 times of the conventional dry desulfurization.
The above is a brief introduction to the desulfurization technology of biogas purification and purification. For more information, please click biogas desulfurization http://www.hneee.net Website.