CN213841390U

CN213841390U - Waste heat recovery system of PTA device

Info

Publication number: CN213841390U
Application number: CN202022255940.9U
Authority: CN
Inventors: 李华; 江益兰; 张存吉; 孟欣; 张洪; 程川; 王玉明
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Petrochemical Co Ltd
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Petrochemical Co Ltd
Priority date: 2020-10-12
Filing date: 2020-10-12
Publication date: 2021-07-30
Anticipated expiration: 2030-10-12

Abstract

The utility model discloses a waste heat recovery system of PTA device belongs to PTA production field, and the system includes flash tank, whirlwind vapour and liquid separator, washes piping, steam pressure monitor, two types of heat pumps of lithium bromide, steam generator jar, waste heat condensate tank, gas phase condenser, liquid ring vacuum pump, catch water jar, U type liquid seal, waste heat condensate pump. The low-grade energy contained in the PTA mother liquor is effectively utilized by adopting a lithium bromide heat pump heating technology. Through PTA low temperature technology water treatment and energy recovery, can produce high-grade steam, clean steam condensate, eliminate the unordered waste heat that discharges in the PTA production process, reduced the pollution to the environment, produce comparatively considerable economic benefits simultaneously.

Description

Waste heat recovery system of PTA device

Technical Field

The utility model relates to a PTA production field especially relates to a waste heat recovery system of PTA device.

Background

In the production process of producing Purified Terephthalic Acid (PTA) by refining Crude Terephthalic Acid (CTA), separated mother liquor can be flashed to generate a large amount of low-grade steam, and a white dragon is formed at the top of a production device, so that the latest environmental protection requirement is not met, and energy waste is caused.

With the increasing maturity of PTA production technology and the increasing environmental protection requirements, in order to meet the latest environmental protection requirements and reduce the production cost, the requirements for the treatment work of the disordered discharge in the production process are more and more urgent, in particular to a low-grade steam or waste water recovery technology which can generate certain benefits after the treatment.

At present, the refined mother liquor and the low-grade steam recovery technology generated by the refined mother liquor in the PTA production process are different according to the difference of the PTA production processes, and in the three-well PTA production process, the lithium bromide heat pump heating technology is used for recovering the low-grade steam and is used for the first time in the PTA production field.

In the existing waste heat recycling system of PTA refining unit mother liquor as disclosed in patent CN201920779761X, flash steam of refining mother liquor enters a steam drum, liquid drops and organic matters are possibly carried in the steam, and the system cannot be applied to occasions with higher cleanliness; the flash steam enters the direct steam drum and the steam system fluctuates if the flash tank fluctuates. The recovery technology disclosed in PTA refining mother liquor waste heat recovery technology research is that the refining mother liquor enters a multi-stage flash tower, the equipment structure is complex, the blocking probability is high, and the stable operation effect of the equipment is poor; the whole system operates at normal pressure, and if the flash tower or upstream pressure fluctuates, the heat recovery system cannot operate stably.

SUMMERY OF THE UTILITY MODEL

In order to overcome the defects of the prior art, the utility model aims to provide a waste heat recovery system of PTA device, which can solve the problems.

The design principle is as follows: sending the PTA mother liquor into a flash tank, sending the steam generated by flash evaporation into a second-class heat pump to generate 0.2MPa steam which can be directly used; a pressure monitoring and multi-medium flushing pipeline is arranged on the flash steam conveying pipeline to prevent the system from being blocked; the negative pressure technology is used in the second type heat pump steam condensate system, so that the pressure fluctuation of a flash tank can be avoided, the medium flow is facilitated, and the system operation stability is good; clean steam condensate obtained after the heat of the flash steam is recovered can be directly recovered and used.

The design scheme is as follows: after the PTA mother liquor is subjected to flash evaporation through the flash evaporation tank, a certain amount of liquid drops and organic matter particles are carried in a flash evaporation vapor phase. The liquid drops and organic particles can cause the blockage or resistance rise of a vapor phase pipeline, flash steam is processed by a cyclone gas-liquid separator and then enters a lithium bromide class II heat pump, a pressure monitor is arranged on the vapor phase pipeline to monitor the vapor phase pressure, and different media such as hot water, steam and alkali are used for dredging the pipeline according to different pressure rising degrees, so that the stable operation of the system is ensured. The lithium bromide heat pump of the second class recovers the heat of the waste heat steam by utilizing the material characteristics of lithium bromide, and the recovered heat heats boiler water to generate steam of 0.11-0.25 MPa, so that the steam can be directly used. And after the flash steam is subjected to heat recovery by a lithium bromide second-class heat pump, condensing to obtain clean steam condensate, conveying the clean steam condensate to a waste heat condensate tank, and conveying the steam condensate to a system for recycling by a waste heat condensate pump. The waste heat condensate tank maintains a certain pressure negative pressure, so that the pressure fluctuation of an upstream flash tank can be prevented, and the flow of a flash steam phase is utilized, so that the sedimentation blockage is reduced, and the stable operation of the system is facilitated. And the waste heat condensate tank is under negative pressure, the flash evaporation steam of the waste heat condensate in the tank is cooled by a vapor phase condenser on the top of the tank, the cooling liquid is sealed back to the waste heat condensate tank by U-shaped liquid, and a certain liquid level can be permanently established by the U-shaped liquid seal. The liquid ring vacuum pump pumps the vapor phase condenser to maintain the negative pressure of the waste heat condensate tank and the waste heat recovery system. A certain liquid level is maintained in the steam-water separation tank, the normal operation of the liquid ring vacuum pump is ensured, and the noncondensable gas of the system is discharged out of the waste heat recovery system.

Preferably, the boiler water in the steam generating tank produces low pressure steam of 0.2 MPa.

The optimized steam-water separation tank provides normal operation working fluid for the liquid ring vacuum pump, and the top end of the steam-water separation tank is communicated with the atmosphere for emptying.

Compared with the prior art, the beneficial effects of the utility model reside in that: the utility model discloses a lithium bromide heat pump heating technology carries out effective utilization to the low-grade energy that PTA mother liquor contains. Through PTA low temperature technology water treatment and energy recovery, can produce high-grade steam, clean steam condensate, eliminate the unordered waste heat that discharges in the PTA production process, reduced the pollution to the environment, produce comparatively considerable economic benefits simultaneously.

Drawings

Fig. 1 is a schematic diagram of a waste heat recovery system of a PTA device.

In the figure: 1. a flash tank; 2. a cyclone gas-liquid separator; 3. flushing the tubing; 4. a steam pressure monitor; 5. lithium bromide type II heat pumps; 6. a steam generating tank; 7. a waste heat condensate tank; 8. a gas phase condenser; 9. a liquid ring vacuum pump; 10. a steam-water separation tank; 11. u-shaped liquid seal; 12. waste heat condensate pump.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

A waste heat recovery system of a PTA device is shown in figure 1 and comprises a flash tank 1, a cyclone gas-liquid separator 2, a flushing pipe 3, a steam pressure monitor 4, a lithium bromide two-class heat pump 5, a steam generation tank 6, a waste heat condensate tank 7, a gas phase condenser 8, a liquid ring vacuum pump 9, a gas-water separation tank 10, a U-shaped liquid seal 11 and a waste heat condensate pump 12.

Wherein, the PTA mother liquor is sent into a flash tank 1, and the outlet end of the flash tank 1 is communicated with a cyclone gas-liquid separator 2 through a pipeline.

The cyclone gas-liquid separator 2 discharges and separates a liquid phase through the lower end, a vapor phase is conveyed to enter a lithium bromide second-class heat pump 5 through a top end pipeline for heat recovery, the vapor phase pipeline is provided with the flushing piping 3 to dredge the vapor phase pipeline, and the vapor pressure monitor 4 is installed on the vapor phase pipeline for vapor phase pressure monitoring.

The lithium bromide heat pump 5 heats the steam generating tank 6 by the recovered heat, so that the boiler water in the steam generating tank 6 generates steam. The vapor phase is condensed after the heat recovery of the lithium bromide second-class heat pump 5, and the liquid phase enters the waste heat condensate tank 7 through a pipeline at the bottom end of the heat pump.

And a gas phase condenser 8 is arranged on the top of the waste heat condensate tank 7, and condensate of the gas phase condenser 8 flows back to the waste heat condensate tank 7 through a U-shaped liquid seal 11. It will be appreciated that the condenser herein may be employed with other types of condensers known in the art to achieve the same effect.

The bottom end of the waste heat condensate tank 7 is connected with a waste heat condensate pump 12 so as to send the liquid in the tank back to the system for recycling through the waste heat condensate pump 12.

Further, the flushing pipe 3 supplies hot water, steam, a flushing mixture of alkali or a pressure-dependent selectable supply to the vapor phase pipeline of the cyclone vapor-liquid separator 2.

Furthermore, the boiler water in the steam generating tank 6 generates 0.11-0.25 MPa of steam, preferably 0.2 MPa.

Further, the system is provided with a liquid ring vacuum pump 9 connected with the gas phase condenser 8 to suck the gas phase condenser 8 so as to maintain the negative pressure of the system.

Further, the system also comprises a steam-water separation tank 10, wherein the steam-water separation tank 10 provides normal operation working fluid for the liquid ring vacuum pump 9, and the top end of the steam-water separation tank 10 is communicated with the atmosphere for emptying.

Wherein, the refined mother liquor is vaporized through the flash tank 1, and the equipment structure is simple. Because of the PTA production characteristic, the refined mother liquor contains a certain solid content, the equipment structure is simple, the blocking probability is low, the equipment stable operation effect is good, the heat recovery efficiency is high, the generated steam is clean, and the equipment can be used in any occasions.

The lithium bromide second-class heat pump 5 recovery system adopts a negative pressure technology, can maintain the pressure stability of an upstream heat recovery system and a heat recovery system, and has good system operation stability.

The utility model discloses can use two kinds of heat pump technologies of lithium bromide in PTA apparatus for heat recovery field, eliminate the unordered waste heat that discharges in the PTA production process, make apparatus for producing green operation to produce steam and steam condensate, have obvious economic benefits.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims

1. The utility model provides a waste heat recovery system of PTA device which characterized in that: the system comprises a flash tank (1), a cyclone gas-liquid separator (2), a flushing piping (3), a steam pressure monitor (4), a lithium bromide second-class heat pump (5), a steam generation tank (6), a waste heat condensate tank (7), a gas phase condenser (8), a U-shaped liquid seal (11) and a waste heat condensate pump (12);

wherein, the PTA mother liquor is sent into a flash tank (1), and the outlet end of the flash tank (1) is communicated with a cyclone gas-liquid separator (2) through a pipeline;

the cyclone gas-liquid separator (2) discharges and separates liquid phase through the lower end, the vapor phase is conveyed to enter a lithium bromide second-class heat pump (5) through a top end pipeline for heat recovery, the flushing piping (3) is arranged on the vapor phase pipeline to dredge the vapor phase pipeline, and the vapor pressure monitor (4) is arranged on the vapor phase pipeline for vapor phase pressure monitoring;

the lithium bromide second-class heat pump (5) heats the steam generating tank (6) through the recovered heat, so that boiler water in the steam generating tank (6) generates steam; the vapor phase is condensed after the heat recovery of the lithium bromide second-class heat pump (5), and the liquid phase enters a waste heat condensate tank (7) through a pipeline at the bottom end of the heat pump;

a gas phase condenser (8) is arranged on the top of the waste heat condensate tank (7), and condensate of the gas phase condenser (8) flows back to the waste heat condensate tank (7) through a U-shaped liquid seal (11);

the bottom end of the waste heat condensate tank (7) is connected with a waste heat condensate pump (12) so as to send the liquid in the tank back to the system for recycling through the waste heat condensate pump (12).

2. The system of claim 1, wherein: the flushing pipe (3) provides a flushing mixture of hot water, steam and alkali to a vapor phase pipeline of the cyclone gas-liquid separator (2).

3. The system of claim 1, wherein: the boiler water in the steam generating tank (6) generates 0.11-0.25 MPa steam.

4. The system of claim 1, wherein: the system is connected with the gas phase condenser (8) through a liquid ring vacuum pump (9) to suck the gas phase condenser (8) so as to maintain the negative pressure of the system.

5. The system of claim 4, wherein: the system further comprises a steam-water separation tank (10), the steam-water separation tank (10) provides normal operation working fluid for the liquid ring vacuum pump (9), and the top end of the steam-water separation tank (10) is communicated with the atmosphere to be emptied.