METHOD FOR RECOVERING LOW-TEMPERATURE HEAT AND APPLICATION OF THE METHOD TO AN AROMATICS COMPLEX

摘要

The present invention relates to a method for recovering heat available at low temperature in a process and its use in order to reduce the energy consumption of the said process. Application of the method to an aromatics complex in which the low-temperature heat is recovered at the head of distillation columns in the form of low-pressure steam and is reused to reboil other distillation columns in which the operating pressure has possibly been lowered.

主权项

1. Method for recovering low-temperature heat, i.e. between 100° C. and 180° C., from a so-called low-temperature heat source in a refining or petrochemical process, called a “complex”, comprising at least one distillation column, the said method consisting of the following stages:
1) generating low pressure steam (i.e. at a pressure between 1 bar absolute and 7 bars absolute) by exchange with at least one low-temperature heat source selected from the condensers of some distillation columns of the complex, forming a first set E1. 2) increasing the pressure of the generated steam in at least one compression stage, in order to produce MP steam, 3) modifying the operating conditions of the process by reducing the operating pressure of one or more distillation columns of the complex, so as to lower the temperature of their reboiler below the temperature of the steam obtained from stage 2. 4) using at least a part of the LP steam obtained from stage 1 and MP steam obtained from stage 2, either directly or after recompression, as heat transporting fluid supplied to the reboilers of some columns of the complex, forming a second set E2 distinct from E1.