11.4 Daily Topic: Changing the Material of Process Piping
Thread Content
As the title suggests, what is the material used for the process gas pipelines in the transformation section?
We use a relatively high pressure (8.0 MPa); chromium-molybdenum steel is employed in the high-temperature sections, while 304 stainless steel is used in the low-temperature sections, and no problems have occurred over the past seven or eight years
It depends on the process used; for example, in the case of a full low-pressure conversion process at 0.8 MPa, stainless steel is used only for the pipelines between the heat exchanger and the converter, while carbon steel can be used for everything else. In contrast, in the sulfur-tolerant conversion processes used for gas production from water-coal slurry, which operate at around 6.0 MPa, stainless steel is generally used.
Generally, the transformation temperature ranges from 300 to 500 degrees, and the hydrogen partial pressure is also high. Therefore, chromium-molybdenum steel resistant to hydrogen embrittlement must be used. 15 chromium-molybdenum material is generally used.
Reply 1# z880347730 321 stainless steel thick-walled pipe
In systems with saturated hot water, stainless steel should be used for the pipe running from the saturated hot water tower to the inlet of the converter. Since the outlet temperature of the medium converter is relatively high, around 350–400 degrees, 15CrMo can be used
Is stainless steel such as 316 suitable for use in the conversion section of coal slurry gasification?
Reply to 8# xuqinger: I’m not sure what material is used for gasification
321 is commonly used; carbon steel can also be used, with no problem
Reply to 10# cubomb: It is said that steel grade 321 was phased out at Shanghai Coking Plant 20 years ago. From the information I’ve found, it seems that 321 is essentially equivalent to 304 steel. Steel with a 321 grade has poor weldability; if the welder’s skills are not good, it can lead to disaster. It is still recommended to use 316L or 15 chromium-molybdenum steel.