Equipment and method for utilizing cold energy in demethanizer with multi-stream plate fin reboiler

Abstract

The invention provides equipment and method for utilizing cold energy in a demethanizer with a multi-stream plate fin reboiler. The equipment for utilizing the cold energy in the demethanizer with themulti-stream plate fin reboiler at least comprises a raw material natural gas, a backflow lean natural gas, a high pressure normal temperature mixed refrigerant, a main cooling box, a low temperatureseparator, a coaxial pressure increased expansion machine, the demethanizer and the multi-stream plate fin reboiler. According to the equipment and method for utilizing the cold energy in the demethanizer with the multi-stream plate fin reboiler, by using the multi-stream plate fin reboiler as a demethanizer bottom reboiler, the defects of a large setting number, large floor area and inconvenientoverhead mounting of a traditional tubular heat exchanger are avoided; and by using a measure of supplementing other material flows, the maximum heat exchanging temperature of a plate-fin heat exchanger is reduced so that the defect of small heat transfer temperature difference of the plate-fin heat exchanger is overcome.

Description

technical field [0001] The invention belongs to the field of natural gas processing, and in particular relates to equipment and a method for utilizing cold energy in a demethanizer with a multi-flow plate-fin reboiler. Background technique [0002] Ethane is a high-quality raw material for ethylene, and the production cost of cracking ethane to produce ethylene is two-thirds of that of naphtha. Internationally, ethylene raw material C 2 -C 4 Accounted for about 48%, while my country is restricted by raw materials, mainly naphtha. Recovering ethane products from natural gas and using them as raw materials for ethylene production by steam thermal cracking has positive significance for increasing the output of ethylene products, reducing energy consumption of ethylene plants, and improving quality and efficiency. [0003] The total amount of Upper Paleozoic natural gas produced by Changqing Oilfield is large, and contains large-scale ethane and above heavy hydrocarbon compone...

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Problems solved by technology

[0005] The demethanizer realizes the separation of methane from ethane and above light hydrocarbon components by adopting the principle of rectification and separation, with a reboiler at the bottom of the tower and a condensing reflux at the top of the tower. At present, the reboiler at the bottom of the demethanizer for similar projects The forms of all the tubes and tubes are used in the reboiler, because the processing scale of the single set of equipment in this project is very large (1500×10 4 m 3 / d), ranking the top three in the world and the largest in Asia, if a conventional tube-and-tube kettle reboiler is used, 2 to 3 reboilers will be installed in parallel, not only the process is complicated, the investment is high, the floor area is large, and the installation and maintenance are inconvenient It is easy to cause uneven flow and heat distribution, which will affect the stable operation of the device, and then affect the quality index of the product

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