Selection of synthesis process for methanol production from coke oven gas
Thread Content
As the title suggests, what processes and types of furnaces are commonly used these days? Could anyone explain in detail the problems that often arise with various processes in practice? There’s a lot of theoretical research available online, but seems to be little exchange of practical experience.
It seems that the conversion is a type of pure oxygen catalytic conversion
We use the low-pressure process, partial oxidation catalytic conversion, Ruhr process reactor, three-column distillation, and dry iron-molybdenum-cobalt-zinc oxide desulfurization.
Coke oven gas has a too high hydrogen-to-carbon ratio; if steam reforming in one stage is used, it is not suitable for methanol production (it is mainly used for hydrogen production). Currently, pure oxygen conversion is commonly used, which can be further divided into “partial catalytic oxidation” and “non-catalytic oxidation”. Currently, industrial applications mostly involve “partial catalytic oxidation”. A few years ago, due to the high profits in the methanol market, domestic coking or steel companies began to launch projects for producing methanol from coke oven gas, but not many of these projects were successful.
In my opinion, using higher pressure in some catalytic oxidation processes is more energy-efficient； The conversion pressure being higher than the synthesis pressure helps to save compression power consumption ； Since it is a pure oxygen conversion, the residual CH4 content in the conversion gas does not increase significantly as pressure rises. To increase conversion pressure, it is crucial to give thorough consideration from a safety perspective.
Since the Second Chemical Research Institute built the first methanol production plant in Qujing, Yunnan, many such plants have been established across the country’s coking industry like mushrooms after rain. But in summary, the basic principle remains the same: compression of coke oven gas, dry desulfurization, conversion, compression of syngas, Ruhr synthesis tower, and three-or four-column distillation. Dry desulfurization generally involves a two-stage process of iron-molybdenum hydrogenation followed by iron-manganese or iron oxide treatment, with zinc oxide used as the final control element. Most conversions are carried out via partial catalytic oxidation with pure oxygen. (Ningdong Baofeng uses the non-catalytic oxidation method and has not yet started operation.) ) Since coke oven gas and natural gas have much lower methane content, two-stage conversion is not employed. However, some design institutes have adopted a two-stage conversion process using converter switching; generally, the designs in China are quite similar to each other. Most accidents in the methanol production process using coke oven gas occur in the conversion section; they are generally caused by overheating of the conversion furnace or explosions in the oxygen pipelines, and are related to equipment selection, process control, and construction quality.