Issues regarding the selection of a coke oven gas compressor (for 100,000 tons of methanol, with a compressor outlet pressure of 5.3 MPa)

I’m sorry, the compressor outlet pressure is 2.5 MPa

For a methanol project with an annual capacity of 100,000 tons, reciprocating and centrifugal compressors are available for use in coke oven gas compression. Centrifugal compressors offer stable performance, have fewer wearing parts, and no backup units are necessary, but their investment cost is much higher than that of reciprocating compressors. Based on the characteristics of the gas composition, a reciprocating compressor with mature technology, stable performance, and easy operation is selected. A symmetrically balanced three-row, four-stage compressor is sufficient; in such compressors, the inertial forces are completely balanced. Moreover, since the piston forces of the opposite rows are in opposite directions, they cancel each other out, reducing wear between the main journal and the main bearings. Four-column, six-stage compressors are used in installations with high volumes of coke oven gas to be processed.

Firstly, I agree with the opinion on compressor selection mentioned on the fourth floor, and would like to add the following: 1. Since the composition of coke oven gas varies depending on the coking process, the amount of coke oven gas required to produce one ton of methanol also changes. Assuming that 2200 Nm3 of coke oven gas is needed to produce one ton of methanol, for a project that produces 100,000 tons of methanol per year (at a rate of 12.5 tons per hour), the hourly consumption of coke oven gas would be 27,500 Nm3/h. 2. Considering the operating cycle of the reciprocating compressors and the characteristics of the coke oven gas, the system is configured with three compressors (two in operation and one as backup) to ensure long-term full-load operation of the facility; therefore, the gas production capacity of each compressor is approximately 14,000 Nm3/h. With an ultimate outlet pressure of 2.5 Mpa, a four-stage three-compression configuration (two single-stage cylinders) is the appropriate choice. (Note: Primary compression to 0.23–0.25 MPa, secondary compression to 0.8–0.9 MPa, tertiary compression to 2.5 MPa.) The mention of “three columns and four stages” on the fourth floor is likely a typo; it should be “four columns and three stages”. 3. The main parameters of the compressor are as follows: · Type: Reciprocating, symmetrically balanced, four-stage with three stages. · Technical parameters: Gas flow rate of 14,000 Nm3/h. · Pressure: 0.01 MPa (g) at the inlet and 2.5 MPa (g) at the outlet. · Drive method: Motor-driven. 4. A reciprocating compressor is used to compress the raw gas to 2.5 MPa; the gas exiting the conversion unit has improved quality. From the perspectives of energy savings, reduced floor space requirements, larger scale, and technical efficiency, a centrifugal compressor (operating in single-unit configuration) driven by a steam turbine is more suitable for this purpose. This post was last edited by zjyang168168 on 2008-1-10 08:00.]

Thank you all! It is said that compared to the three-stage four-row models, the four-stage six-row models have lower outlet temperatures at each stage, which helps to reduce the risk of the gas valves becoming clogged due to carbonization caused by tar at high temperatures. This is why I prefer the four-stage six-row option. Do you think my viewpoint holds weight?

Is there now a specification regarding the scale of methanol production from coke oven gas? As a result, there might be more use of centrifuges these days; I hope someone can discuss the budget related to this aspect! Now it’s mostly 300,000 and 600,000; there are those who work in design and can explain the intricacies behind it.