Why is the pressure difference of the raw gas after transformation so large?
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For the pressure of the raw gas after transformation, some companies use a pressure of 3.3 MPA or less, while others use 5.3 MPA – is this due to differences in process technology? What are their respective benefits? Thank you all for your advice
The differences in the pressure of the raw materials after transformation are mainly due to different processes. A high transformation pressure is beneficial for the compressors in subsequent processes, as it helps to save energy consumption and reduce the investment required for compressors. However, a higher transformation pressure increases initial investment, while reducing production costs.
The pressure for the shift reaction is determined based on the previous process stage (the gas generation system); the shift system itself cannot change this pressure (with the exception of pressure drop losses). The level of pressure should have little impact on the shift process – what matters mainly is the tolerance of the catalyst. The benefits of the compression process are as answered above
Below 3.3 MPA, it is generally low-temperature methanol washing used in conjunction with Shell’s gasification system； 5.3MPA is likely the low-temperature methanol washing unit associated with the system after coal water slurry gasification ； The pressure of the process gas at the methanol washing inlet is primarily determined by the gas generation process in the upstream system. The lower the pressure drop in the sulfur-resistant shift system, the more effective the methanol absorption of CO2 and H2S in the methanol washing unit; this also helps to reduce energy consumption in the compressors of the downstream system
This is mainly determined by the operating pressure of the previous process, the gasification furnace! The transformation itself does not have the function of controlling pressure! Low pressure results in relatively lower costs for the equipment of the front-end system, as well as lower operating and investment expenses; however, the energy consumption of the back-end system is relatively high ； High pressure is beneficial for energy savings and reduced consumption in subsequent processes, as it lowers the energy demand of syngas compressors and reduces the volume of solution circulation in the purification system; however, the downside is that the initial investment cost for the preceding system is higher!