Utilization method for waste heat and excess pressure of gas fractionation apparatus

Abstract

The invention discloses a utilization method for waste heat and excess pressure of a gas fractionation apparatus. According to the method, a material flow from the bottom of a propylene tower and a saturated solution from a working medium pump are mixed and then undergo heat exchange in a low temperature waste heat exchanger; obtained steam and low pressure injection steam are introduced into an injector; deceleration and pressurization are carried out by the injector so as to obtain medium-pressure overheated steam which enters into a circulating water condenser or an air cooler for condensation into a medium-pressure saturated solution; one part of the medium-pressure saturated solution is pressurized by the working medium pump to a pressure which is same as the pressure at the bottom of the propylene tower and is then mixed with the material flow at the bottom of the propylene tower, and an obtained mixture is sent back to the low temperature waste heat exchanger for cyclic usage; the other part of the medium-pressure saturated solution is converted into a medium-pressure supercooled liquid phase by a circulating water cooler and then divided into two paths, wherein one path of the medium-pressure supercooled liquid phase is discharged as a product from a system, and the other path of the medium-pressure supercooled liquid phase is throttled and decompressed by a thermal expansion valve so as to obtain a cold source which is used for cooling a material flow at the top of a deethanization tower, a material flow at the top of the propylene tower and refrigerant water. With the method provided by the invention, waste heat and excess pressure of the material flow at the bottom of the propylene tower are fully used, operation stability of the propylene tower is improved, and product quality is guaranteed.

Description

technical field [0001] The invention belongs to energy recovery and utilization in the field of petrochemical industry, in particular to a method for utilizing waste heat and pressure in a gas separation device. Background technique [0002] With the development of my country's economy, the demand for energy continues to grow, the contradiction between supply and demand in the global energy market has intensified, and my country's dependence on foreign oil resources has continued to increase, and energy security issues have become increasingly prominent. Energy saving and consumption reduction has become the focus of refining and chemical enterprises, and the recovery and utilization of waste heat and pressure plays an important role in the current energy saving and consumption reduction. The waste heat and pressure of refining and chemical enterprises are widely distributed and have a huge base, especially the low-temperature waste heat with a temperature of 95-120 ℃, which...

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Problems solved by technology

[0006] In general, the temperature at the top of the rectification tower is determined according to the operating pressure, product quality requirements, and cooling utilities. When other conditions remain unchanged, a lower tower top temperature is conducive to improving product purity, but under certain working conditions, the temperature of the cooling utilities is lower. Influence, in order to ensure product purity have to increase operating costs, or sacrifice product recovery to reduce operating costs

The traditional deethanizer condenser is cooled by circulating water. Due to the limitation of circulating water, the top temperature of the tower is still high, the separation efficiency of the deethanizer is not high, the dry gas is not "dry" seriously, and the high value-added propylene in the dry gas The content is as high as 60%, which reduces the propylene yield and economic benefits of the gas separation device to a certain extent

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