DEAR Biogas purification unit.In order to prevent freezing and impermeability of the foundation, a layer of fine aggregate concrete is required on its surface, and a metal waterproof layer of copper sheet or aluminum plate is required around if necessary. The foundation body is made of concrete with waterproof and frost resistance (No. 200 waterproof concrete). In order to reduce cooling, a layer of pearlite concrete mortar with thickness of no less than 300 mm shall be laid on the upper part, with compressive strength of no less than 7.5 MPa, thermal conductivity of no more than 0.2 w / (m ·℃), and no cracks.It can be divided into three stages: cooling equipment, liquid accumulation and rectification condition adjustment. Compared with the start-up mode of switching process, it can be called "overall cooling method" or "one-time cooling method". Attention should be paid to the following points during the start-up operation: the molecular sieve used for the first time should be activated and regenerated to remove the water and carbon dioxide absorbed in the transportation and filling process.
Large size gate valves and pneumatic control valves should be installed vertically to avoid deviation due to the heavy weight of the valve core, which will increase the mechanical wear between the valve core and the bushing and cause leakage; when tightening the compression screw, the valve should be slightly open to avoid damaging the top sealing surface of the valve;For the first type, it is usually adjusted by changing the liquid level of evaporation side, that is, changing the size of heat transfer area. This regulation condition is relatively stable, and the pressure change of upper and lower tower is small. For the second type, when the liquid oxygen in the tube reaches 30% of the apparent liquid level, the churning condition can be established, and the heat transfer surface can fully play the role of heat transfer. Therefore, it can not be adjusted by changing the liquid level on the evaporation side.If the expansion amount is within the allowable range of the minimum reflux ratio (less than 20% - 25% of the process air volume) required by the upper column distillation, it can all enter the column. Otherwise, it can't enter the tower completely, and part of the expanded air only produces cold air and doesn't participate in distillation. These three quantities restrict each other. The expansion capacity is composed of two parts: the circulating flow and the bypass flow from the lower tower. Therefore, the temperature and gas flow of the circulating flow will directly affect the inlet state of the expander.
If the upper and lower correction irons outside the shell of the fractionator are broken or lost during transportation, the pearlite in the fractionator shall be unloaded, a vertical line shall be hung from the top of the upper tower to the condensing evaporator, and the distance between the vertical line and the tower body shall be measured from the top, middle and bottom, and the verticality deviation shall not be greater than 1 / 1000. Every 90 degrees, the measured values should be basically consistent. If not, the bottom of fractionator can be adjusted by adding pad iron to make it meet the requirements.In order to have a preliminary judgment on the leakage position and leakage before shutdown for maintenance, and to shorten the shutdown time, many units have explored some effective methods in practice.Flange connection is to fix two pipes, pipe fittings or equipment on one flange respectively, and then add flange gasket between the two flanges and fasten them together with bolts to complete the connection. Some pipe fittings and equipment have their own flange, which also belongs to flange connection. The flange is divided into threaded connection (threaded connection) flange and welding flange.
