It is found in people's use that in the storage and utilization of methane, the air tank rises and falls frequently, sometimes too fast (the rising speed of wet tank is 1. (2m / min) results in frequent maintenance of wet gas storage tank, and corrosion of gas storage tank caused by acid gas dissolving in water, which shortens service life and causes great loss to production. Therefore, it is necessary to consider the maintenance of methane gas storage tank.
In order to ensure the continuous supply of methane to all points, even in the sewage treatment plant, the methane storage equipment shall be set in the system to balance the methane flow, and the volume of methane gas tank shall be calculated and determined according to the natural gas production and utilization rate.
(1) Source and composition of methane.
About 70% of the wastewater from the sewage treatment plant is industrial wastewater, and about 30% is domestic sewage. The water quality is complex. The wastewater treatment plant adopts AB process, which is characterized by a large amount of excess sludge. A. B. the two pieces of excess sludge are mixed and concentrated in the thickener, and then anaerobic digestion is carried out. The sludge of the urban sewage treatment plant is mainly composed of three kinds of organic substances, such as carbohydrate, fat, protein, components with different sludge volume generated by biogas, and different methane content. According to the composition of organic substances in the wastewater
The methane produced in the anaerobic digestion process is filtered and desulfurized and then enters the biogas digester. Under the stable operation conditions, the methane content in the sludge digester can reach 55% ~ 60%.
(2) The internal and external environment of biogas.
The water tank in the methane gas tank is full of water, and above the water surface is methane. Therefore, the gas components dissolved in water form a dynamic equilibrium on the water surface. The solubility of CO2 and H2S is high, and the concentration in water is high.