Ethylene is a very important basic raw material for petrochemical industry, and its bulk downstream products mainly include polyethylene, polyvinyl chloride, ethylene oxide, ethylene glycol, styrene, vinyl acetate, etc.
At present, the main method of producing ethylene using petroleum as raw material is cracking at home and abroad. With the increasing reduction of petroleum resources and the continuous rise of international oil prices, the production of ethylene through petroleum routes will face unprecedented challenges. Many petrochemical companies around the world are actively exploring other routes, including using coal, natural gas, biomass raw materials, etc. to produce olefins, in order to reduce the excessive dependence of ethylene on limited petroleum resources.
The technology of using renewable biomass raw materials to produce ethanol and then dehydrating to produce ethylene is one of the important ways to adjust energy structure, reduce environmental pollution, and promote sustainable development of the national economy and society. The main research goal for ethanol dehydration to produce ethylene is to improve the process flow, reduce the energy consumption of the device, and increase efficiency.
In the process of ethanol dehydration to produce ethylene, the main industrial applications are fixed bed processes, including isothermal fixed bed processes and adiabatic fixed bed processes. The isothermal bed process technology is more suitable for small-scale industrial devices. When the scale of the device reaches or exceeds tens of thousands of tons/year, the adiabatic bed process technology is usually used because it is difficult to scale up in engineering. US4232179 proposed an adiabatic process for ethanol dehydration reaction, where the ethanol dehydration reaction is carried out in an adiabatic fixed bed, and the reaction material is heated to the required temperature before entering the reactor. Afterwards, US4396789 proposed a three-stage adiabatic fixed bed reaction process for ethanol dehydration to produce ethylene, and in the early 1980s, a 60000 ton/year ethylene plant was established using this process. US20130178674A1 introduces a reactor and process for ethanol dehydration to produce ethylene. The reaction process consists of multiple reactors with different sizes and catalyst loading amounts, each of which can be independently controlled. For the adiabatic bed ethanol dehydration process to produce ethylene, developing high-performance adiabatic fixed bed reactors and reaction processes is one of the key technologies for expanding the scale of the device. The main solutions in the development of adiabatic fixed bed reaction processes are the reaction process plan and the structural design of the reactor. For the design of the reactor, the key is to solve the problem of uniform fluid distribution inside the reactor, as the distribution of fluid in the reactor directly affects the heat and mass transfer of the catalyst bed, as well as the reaction process. Uneven gas distribution can reduce the efficiency of the catalyst and reactor. The study of gas pre distributors in fixed bed reactors (Chemical Engineering, 2006, 34 (4): 24-27) investigated the effect of gas pre distributors on flow in reactors. For adiabatic fixed bed reactors, designing a reasonable inlet gas distributor will effectively improve the gas distribution effect and the utilization efficiency of catalysts and reactors.