PROCESS FOR RECOVERING POWER

摘要

The present invention provides a process for power recovery in a process for producing ethylene, comprising steam cracking a hydrocarbon feed to produce a cracked gas product; cooling the cracked gas product by indirect heat exchange with high pressure liquid water to obtain cooled cracked gas product while evaporating the high pressure liquid water to high pressure steam; expanding the high pressure steam in a first steam expansion turbine to produce power and to obtain medium pressure steam; heating at least part of the medium pressure steam to increase the temperature of the medium pressure steam by passing the medium pressure steam through a convection zone of the cracking furnace and retrieving reheated medium pressure steam from the convection zone; expanding at least part of the reheated medium pressure steam in a second steam expansion turbine to produce power and to obtain low pressure steam.

主权项

1. A process for power recovery in a process for producing ethylene, comprising the steps of:
a) steam cracking a hydrocarbon feed in a cracking furnace at temperatures above 1000° C. to produce a cracked gas product having a temperature in the range of from 700 to 1000° C.; b) cooling the cracked gas product by indirect heat exchange with high pressure liquid water having an initial temperature above 270° C. and an initial pressure above 65 bar (gauge) to obtain cooled cracked gas product while evaporating the high pressure liquid water to high pressure steam having a pressure above 65 bar (gauge); c) expanding at least part of the high pressure steam in a first steam expansion turbine to produce power and to obtain medium pressure steam having a reduced temperature and reduced pressure compared to the high pressure steam; d) heating at least part of the medium pressure steam to increase the temperature of the medium pressure steam by in the range of from 40 to 100° C. by passing the medium pressure steam through a convection zone of the cracking furnace and retrieving reheated medium pressure steam from the convection zone; e) expanding at least part of the reheated medium pressure steam in a second steam expansion turbine to produce power and to obtain low pressure steam having a reduced pressure compared to the reheated medium pressure steam.