Technical Requirements Of Coal Chemical Industry For Valve Products

Valve material requirements

Due to the existence of oil-coal slurry in the direct coal liquefaction reaction, the wear of the coal slurry on equipment materials such as valves and pipelines must be considered. Therefore, it is required that the materials used to manufacture valves have comprehensive properties that meet the requirements of use. Specifically, it should have:

1. The properties of compactness, purity and homogeneity, which are used to describe the intrinsic properties of the material, are superior, which is especially important for thick (or large section) steel.

2. It must meet the requirements of chemical composition, room temperature and high temperature mechanical properties that meet the requirements of the design specification.

3. It must have anti-environmental embrittlement performance that can be used for a long time in harsh environments. 

Valve process requirements

Coal direct liquefaction not only has the characteristics of high temperature, high pressure, and hydrogen in the hydrogenation unit, but also has the characteristics of coexisting corrosion and wear conditions in coal chemical industry. Therefore, the source of raw materials is very important. Generally speaking, the composition of valve materials, especially harmful elements The content puts forward corresponding clear index requirements, although this requirement is often higher than the basic general requirements of the material, but for the quality of the final product, these component indicators alone are not enough.

Therefore, the foundry should strictly control the source of raw materials, and the processed raw materials should not only be smelted, but also further refined, especially the control before the furnace. Only in this way can it be possible to ensure the quality of castings. 

Valve structure requirements

The design of the valve structure should avoid the coking of the coal slurry to make the valve ineffective and facilitate cleaning. Coal oil slurry has a characteristic: if the flow is not smooth or stationary, that is, the flow condition of the medium is not good, it will deposit and possibly polymerize, which will cause coking and lock the valve.

At present, the shut-off valves used in the direct liquefaction coal slurry pipeline are all ball valves. When the operation needs to cut off the pipeline to close the ball valve, the oil-coal slurry inside the valve ball cannot be discharged and deposited in the ball cavity, which may coke and lock. In fact, the selection of ball valves is not the most suitable choice under this working condition.