Device and process for recovery of low-grade waste heat of rectification system

Abstract

The invention discloses a device and process for recovery of low-grade waste heat of a rectification system. The device comprises a rectification tower, a tower top evaporation condenser, a raw material preheater, a tower kettle reboiler and a waste heat recovery system, wherein the waste heat recovery system comprises an intermediate heat-exchange working-medium vaporization device and a workingmedium compressor, all the tower top evaporation condenser, the raw material preheater and the tower kettle reboiler are heat exchangers, and an intermediate heat-exchange working medium is introducedinto a cold fluid inlet of the tower top evaporation condenser; a cold fluid outlet of the tower top evaporation condenser is connected with an air inlet of the working medium compressor through theintermediate heat-exchange working-medium vaporization device by using pipelines, an air outlet of the working medium compressor is connected with a hot fluid inlet of the tower kettle reboiler by using pipelines, and a hot fluid outlet of the tower kettle reboiler is connected with a hot fluid inlet of the raw material preheater through a pipeline; and the intermediate heat exchange working medium which is obtained after cooling is performed through heat exchange is discharged from the hot fluid outlet of the raw material preheater. The device has a simple structure, and low-grade heat of steam in the tower top of the rectification tower can be recovered effectively through the device.

Description

technical field [0001] The invention relates to a low-grade waste heat recovery device and process of a rectification system. Background technique [0002] Distillation is a technology that separates components in a mixture by utilizing their different volatilities. It is an important unit operation in petrochemical, pharmaceutical and other industries. With the rapid development of the chemical industry, the application of rectification operations is becoming more and more widespread; however, the energy consumption of the rectification process is very high, accounting for 50% to 70% of the energy consumption of the separation process in the entire chemical industry. Most of the energy consumed in the rectification process is not used for component separation, but is taken away by cooling water or materials. Therefore, the energy saving potential of the rectification process is great. Reasonable use of the heat energy of the rectification process itself can reduce the energ...

AI Technical Summary

Problems solved by technology

[0004] Some rectification waste heat recovery technologies that use the latent heat of the overhead steam often introduce the overhead steam into other devices such as the concentration evaporator as a heat source. Although a large part of the waste heat can be recovered, the actual use is relatively low temperature. Grade waste heat

This direct recycling method has restrictions on the temperature requirements of other devices, and there are safety risks in the direct use of flammable and explosive tower top steam, and the introduction of materials into other devices also increases leakage points

[0005] Since the temperature of the steam at the top of the tower is lower than that of the reboiler at the bottom of the tower, a large amount of low-grade latent heat in the steam at the top of the tower cannot be directly recycled to the bottom reboiler

At the same time, if there are no other devices that require relatively low-grade heat sources nearby, this part of waste heat cannot be recycled

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