Method for combined utilization of low-temperature waste heat of a chppo device and a phenol acetone device

Abstract

This invention relates to the field of energy conservation and consumption reduction in chemical plants, specifically to a method for the combined utilization of low-temperature waste heat from a CHPPO unit and a phenol-acetone unit. The method involves setting up multiple circulating branches connecting different heat sources and heat traps within the CHPPO and phenol-acetone units. The large amount of low-temperature waste heat generated by each heat source within the units is recovered and enriched through a heat transfer medium (water) for heating low-temperature materials within the units. This replaces the low-pressure steam originally required for heating the heat traps, improving the plant's energy efficiency and reducing energy consumption and heating costs in production. Based on the different operating conditions of the units at the initial and final stages, each heat exchange component of each branch is controlled and adjusted holistically, rationally planning and utilizing the low-temperature waste heat of each unit, reducing heat loss directly discharged into the environment, and achieving the overall goal of energy conservation, consumption reduction, cost reduction, and efficiency improvement in the production unit.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and consumption reduction in chemical plants, specifically to a method for the combined utilization of low-temperature waste heat from a CHPPO plant and a phenol-acetone plant. Background Technology

[0002] The CHPPO unit (cumene hydrogen peroxide process for propylene oxide) and the phenol-acetone unit contain multiple heat sources and heat traps, resulting in low-temperature waste heat that is scattered and subject to precise temperature control. Due to design considerations, specialization, dispersed heat sources and heat traps, and relatively isolated designs of various chemical plants, it is difficult to comprehensively plan and utilize the low-temperature waste heat by simply exchanging heat in each unit individually. This leads to low heat exchange efficiency and waste of low-temperature waste heat energy.

[0003] Currently, existing equipment designs generally cool process materials to the required processing temperatures using methods such as air cooling or circulating water cooling. For example, the benzene tower overhead gas in the cumene unit and the gaseous products from the hydrogenolysis unit require air cooling, resulting in significant heat loss and energy waste. On the other hand, the propylene heater and the reboiler in the depropanizer tower of the CHPPO unit require direct heating with low-temperature steam, consuming additional energy. Existing technologies fail to consider the overall engineering perspective and the optimal utilization of energy between units and systems. A significant amount of low-temperature waste heat is not being utilized effectively. Simple utilization of this waste heat can lead to excessive venting of low-pressure steam within the unit, resulting in waste heat utilization failure, low heat recovery efficiency, and energy waste. Therefore, it is necessary to analyze and study the low-temperature waste heat of CHPPO and phenol-acetone units, and to design a reasonable heat exchange system from an overall perspective to improve the utilization efficiency of low-temperature waste heat and reduce energy waste. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low utilization rate and high energy consumption of low-temperature waste heat in existing heat exchange methods for CHPPO and phenol-acetone units. This invention provides a method for the combined utilization of low-temperature waste heat from CHPPO and phenol-acetone units. Using water as the heat transfer medium, this method, through rational planning and design, sets up multiple circulation branches connecting different heat sources and heat traps within the CHPPO and phenol-acetone units. This recovers and enriches a large amount of low-temperature waste heat that was originally cooled by air or water, and uses it for heating low-temperature materials within the units. This replaces the low-pressure steam originally required for heating, improving the plant's energy efficiency, reducing energy consumption and heating costs, and thus achieving the overall goal of energy saving, cost reduction, and efficiency improvement for the unit.

[0005] To achieve the above objectives, the present invention provides a method for the combined utilization of low-temperature waste heat from a CHPPO unit and a phenol-acetone unit. This method is carried out within a heat exchange system comprising a branch for the hydrogenolysis unit within the CHPPO unit, a branch for the cumene unit within the phenol-acetone unit, a branch for the concentrated sulfuric acid pipeline heating system, a circulating return water main pipe, and a heat transfer medium tank. The branch for the hydrogenolysis unit within the CHPPO unit includes a heat exchanger for the external circulating material of the hydrogenolysis stage reaction, a heat exchanger for the gaseous products of the hydrogenolysis reaction, a heat exchanger for the cumene side-stream products of the hydrogenolysis, a circulating heat exchanger for the hydrogenolysis reactor, a heavy component cooler, and a dehydrocarbonization tower. The reboiler and propylene heater, the cumene unit branch in the phenol-acetone removal unit includes a benzene tower top gas heat exchanger, an alkylation reactor external circulation heat exchanger, a polyisopropylbenzene tower top condenser, a hydrocarbon tar discharge cooler, an oxidation feed preheater, a coarse fractionation tower feed preheater, a lithium bromide refrigeration unit, a propane removal tower bottom reboiler, an oxidation liquid heater, and a propane gasification heater; the circulating return water header is used to connect the hydrogenolysis unit branch in the CHPPO removal unit, the cumene unit branch in the phenol-acetone removal unit, and the concentrated sulfuric acid pipeline heating system branch; the heat transfer water tank is used to store and supply heat transfer water. This method involves heat exchange according to the following heat exchange process under initial operating conditions: (1-1) The first heat transfer medium, water, is introduced into the hydrogenolysis unit branch of the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (1-1a) The first stream of the first heat medium water is exchanged with the heat exchanger of the external circulation material of the hydrogenolysis stage reaction; (1-1b) The second stream of the first heat transfer medium water is exchanged with the heat exchanger for the gaseous products of the hydrogenolysis reaction; (1-1c) The third stream of the first heat medium water is exchanged with the heat exchanger for the hydrogenated cumene side-stream product; (1-1d) The fourth stream of the first heat transfer medium water is exchanged with the circulating heat exchanger of the hydrogenolysis reactor; (1-1e) The fifth stream of the first heat medium water is exchanged with the aforementioned heavy component cooler; Next, the heat transfer water heated in step (1-1e) is directly returned to the circulating return water header, and the heat transfer water heated in steps (1-1a) to (1-1d) is combined. Then, the combined first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (1-1f) The first heat medium water after the first stream of confluence is exchanged with the reboiler of the dehydrogenation tower; (1-1g) The first heat transfer medium water after the second stream of water merges is exchanged with the propylene heater; Next, the first heat transfer medium water after heat exchange and cooling in steps (1-1f) to (1-1g) is merged and returned to the circulating return water header; (1-2) The second heat transfer medium water is introduced into the cumene unit branch of the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (1-2a) The first stream of second heat medium water is heated with the heat exchanger of the benzene tower top gas, and then this portion of second heat medium water, after being heated by the heat exchange, is heated with the external circulation heat exchanger of the alkylation reactor. (1-2b) The second stream of the second heat transfer medium water is exchanged with the condenser at the top of the polyisopropylbenzene tower; (1-2c) The third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler; Next, the heated medium water from steps (1-2a) to (1-2c) is combined and then divided into a first branch of heated medium water and a second branch of heated medium water. The first branch of heated medium water exchanges heat with the following devices in the phenol-acetone apparatus in parallel: (1-2d) The first stream of the first branch of the heat transfer medium water is exchanged with the oxidation feed preheater; (1-2e) The second stream of the first branch of the hot water medium is exchanged with the feed preheater of the coarse separator; Next, the heat transfer water cooled down in steps (1-2d) to (1-2e) is collected and returned to the circulating return water header; After passing through the steam-heated safety heat exchanger, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (1-2f) The first stream of the second branch of the heat transfer medium water is used as the heat source for the lithium bromide refrigeration unit; (1-2g) The second stream of the second branch of the heat transfer medium water is exchanged with the reboiler of the propane removal tower; (1-2h) The third stream of the second branch of the heat transfer medium water is exchanged with the oxidizing liquid heater; (1-2i) The fourth stream of the second branch of the heat transfer medium water is exchanged with the propane vaporization heater; Next, the heat transfer medium water cooled down in steps (1-2f) to (1-2i) is collected and returned to the circulating return water header; (1-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the temperature of the sulfuric acid pipeline, and then the heat medium water after heat exchange is returned to the circulating return water main pipe. The hot water returned to the circulating water header in step (1-1) is combined with the hot water returned to the circulating water header in step (1-2), and then passes through the deaerator feedwater preheater. After that, it is combined with the hot water returned to the circulating water header in step (1-3), and then passes through the circulating water cooling and safety heat exchanger before returning to the hot water tank.

[0006] Preferably, the method further includes performing heat exchange according to the following heat exchange process under final operating conditions: (2-1) The first heat transfer medium, water, is introduced into the hydrogenolysis unit branch of the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (2-1a) Stop exchanging heat between the first stream of first heat medium water and the external circulation material heat exchanger of the hydrogenolysis stage reaction; (2-1b) The second stream of the first heat transfer medium water is exchanged with the heat exchanger for the gaseous products of the hydrogenolysis reaction; (2-1c) The third stream of the first heat medium water is exchanged with the heat exchanger of the hydrogenated cumene side-stream product; (2-1d) The fourth stream of the first heat transfer medium water is exchanged with the circulating heat exchanger of the hydrogenolysis reactor; (2-1e) The fifth stream of the first heat medium water is exchanged with the aforementioned heavy component cooler; Next, the heat transfer water heated in step (2-1e) is directly returned to the circulating return water header, and the heat transfer water heated in steps (2-1b) to (2-1d) is combined. Then, the combined first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (2-1f) The first stream of combined hot water is exchanged with the reboiler of the dehydrogenation tower for heat exchange; (2-1g) The first heat transfer medium water after the second stream of water merges is exchanged with the propylene heater; Next, the heat transfer water cooled down in steps (2-1f) to (2-1g) is collected and returned to the circulating return water header; (2-2) The second heat transfer medium water is introduced into the cumene unit branch of the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (2-2a) The first stream of second heat medium water is heated with the heat exchanger of the benzene tower top gas, and then the heated first stream of second heat medium water is heated with the external circulation heat exchanger of the alkylation reactor. (2-2b) The second stream of the second heat transfer medium water is exchanged with the condenser at the top of the polyisopropylbenzene tower; (2-2c) The third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler; Next, the heat transfer water after heat exchange and heating in steps (2-2a) to (2-2c) is merged and then split into a first branch of heat transfer water and a second branch of heat transfer water. The first branch of heat transfer water exchanges heat with the following devices in the phenol-acetone unit in parallel according to the following process: (2-2d) The first stream of the first branch of the heat transfer medium water is exchanged with the oxidation feed preheater; (2-2e) The second stream of the first branch of the hot water medium is exchanged with the feed preheater of the coarse separator; Next, the heat transfer water cooled down in steps (2-2d) to (2-2e) is collected and returned to the circulating return water header; After passing through the steam-heated safety heat exchanger, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (2-2f) The first stream of the second branch of the heat transfer medium water is used as the heat source for the lithium bromide refrigeration unit; (2-2g) The second stream of the second branch of the heat transfer medium water is exchanged with the reboiler of the propane removal tower; (2-2h) The third stream of the second branch of the heat transfer medium water is exchanged with the oxidizing liquid heater; (2-2i) The fourth stream of second branch heat transfer medium water is exchanged with the propane vaporization heater; Next, the heat transfer medium water cooled down in steps (2-2f) to (2-2i) is collected and returned to the circulating return water header; (2-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the temperature of the sulfuric acid pipeline, and then the heat medium water after heat exchange is returned to the circulating return water main pipe. The hot water returned to the circulating water header in step (2-1) is combined with the hot water returned to the circulating water header in step (2-2), and then passes through the deaerator feedwater preheater. After that, it is combined with the hot water returned to the circulating water header in step (2-3), and then passes through the circulating water cooling and safety heat exchanger before returning to the hot water tank.

[0007] Preferably, the temperature of the heat transfer water in the heat transfer water tank is 68-72℃.

[0008] Preferably, with the total flow rate of the heat transfer water output from the heat transfer water tank being 100 parts by weight, under initial operating conditions, the flow rate of the first heat transfer water is 31-34 parts by weight, the flow rate of the second heat transfer water is 41-43 parts by weight, and the flow rate of the third heat transfer water is 25-27 parts by weight; under final operating conditions, the flow rate of the first heat transfer water is 30-32 parts by weight, the flow rate of the second heat transfer water is 45-46 parts by weight, and the flow rate of the third heat transfer water is 22-24 parts by weight.

[0009] Preferably, with the first heat transfer water flow rate as 100 parts by weight, under initial operating conditions, the flow rate of the first stream of first heat transfer water in step (1-1a) is 10-12 parts by weight, the flow rate of the second stream of first heat transfer water in step (1-1b) is 50-52 parts by weight, the flow rate of the third stream of first heat transfer water in step (1-1c) is 30-32 parts by weight, and the flow rate of the fourth stream of first heat transfer water in step (1-1d) is 3-5 parts by weight. In step (1-1e), the flow rate of the fifth stream of the first heat medium water is 2-3 parts by weight; under the final operating conditions, the flow rate of the second stream of the first heat medium water in step (2-1b) is 77-80 parts by weight, the flow rate of the third stream of the first heat medium water in step (2-1c) is 14-16 parts by weight, the flow rate of the fourth stream of the first heat medium water in step (2-1d) is 3-4 parts by weight, and the flow rate of the fifth stream of the first heat medium water in step (2-1e) is 2-3 parts by weight.

[0010] Preferably, with the second heat transfer water flow rate as 100 parts by weight, under initial operating conditions, the flow rate of the first stream of the second heat transfer water in step (1-2a) is 70-73 parts by weight, the flow rate of the second stream of the second heat transfer water in step (1-2b) is 26-28 parts by weight, and the flow rate of the third stream of the second heat transfer water in step (1-2c) is 0.1-1 parts by weight; under final operating conditions, the flow rate of the first stream of the second heat transfer water in step (2-2a) is 74-76 parts by weight, the flow rate of the second stream of the second heat transfer water in step (2-2b) is 23-25 ​​parts by weight, and the flow rate of the third stream of the second heat transfer water in step (2-2c) is 0.1-1 parts by weight.

[0011] Preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (1-1a) to (1-1d) is 127-133℃; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (2-1a) to (2-1d) is 125-130℃.

[0012] Preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-1f) to (1-1g) is 70-75℃, and under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-1f) to (2-1g) is 73-77℃.

[0013] Preferably, under initial operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (1-1e) is 83-87℃; under final operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (2-1e) is 83-87℃.

[0014] Preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (1-2a) to (1-2c) is 114-117℃; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (2-2a) to (2-2c) is 109-113℃.

[0015] Preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2d) to (1-2e) is 68-72℃; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2d) to (2-2e) is 84-88℃.

[0016] Preferably, under initial operating conditions, the temperature of the heat transfer water after heat exchange and cooling in steps (1-2f) to (1-2i) is 78-82℃; under final operating conditions, the temperature of the heat transfer water after heat exchange and cooling in steps (2-2f) to (2-2i) is 78-82℃.

[0017] Preferably, under initial operating conditions, after steps (1-1), (1-2), and (1-3), the temperature of the hot water returning to the circulating return water header and merging is 69-73℃; under final operating conditions, after steps (2-1), (2-2), and (2-3), the temperature of the hot water returning to the circulating return water header and merging is 73-77℃.

[0018] Preferably, under initial operating conditions, the circulating water cooling and safety heat exchanger maintains the temperature of the heat transfer water in the circulating return water header at 68-72°C before returning it to the heat transfer water tank; under final operating conditions, the circulating water cooling and safety heat exchanger maintains the temperature of the heat transfer water in the circulating return water header at 68-72°C before returning it to the heat transfer water tank.

[0019] According to the method of combined utilization of low-temperature waste heat from the CHPPO and phenol-acetone units of the present invention, through reasonable planning and design, multiple circulation branches are set up to connect different heat sources and heat traps in the CHPPO and phenol-acetone units. The large amount of low-temperature waste heat that was originally cooled by air or water is recovered and enriched in the units and used for heating the low-temperature materials in the units, replacing the low-pressure steam originally required for heating, thereby improving the energy utilization efficiency of the plant and reducing the energy consumption and heating costs of the project. According to the different operating conditions of the units in the initial and final stages of operation, each heat exchange part of each branch is controlled and adjusted from an overall perspective, and the low-temperature waste heat of each unit is reasonably planned and utilized to reduce the heat loss directly discharged into the environment, thereby achieving the overall goal of energy saving, cost reduction and efficiency improvement of the unit. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the circulating operation of the heat transfer water system for the method of combined utilization of low-temperature waste heat from the CHPPO device and the phenol-acetone device according to the present invention.

[0021] Figure 2 This is a schematic diagram of the circulating operation process of the heat transfer water system under initial operating conditions for the method of combined utilization of low-temperature waste heat from the CHPPO unit and the phenol-acetone unit according to the present invention.

[0022] Figure 3 This is a schematic diagram of the circulating operation process of the heat transfer water system under the final operating conditions of the method for combined utilization of low-temperature waste heat from the CHPPO unit and the phenol-acetone unit according to the present invention.

[0023] Figure 4 This is a heat flow balance diagram for the low-temperature waste heat utilization of the CHPPO device and the phenol-acetone device of the present invention.

[0024] Explanation of reference numerals in the attached figures 1. Branch line of the hydrolysis unit in the CHPPO unit; 11. External circulating material heat exchanger for the first stage of hydrolysis reaction; 12. Heat exchanger for the gas phase products of the hydrolysis reaction; 13. Heat exchanger for the side-stream products of the hydrolysis cumene; 14. Circulating heat exchanger for the hydrolysis reactor; 15. Heavy component cooler; 16. Reboiler for the dehydrocarbonization tower; 17. Propylene heater; 2. Branch line of the cumene unit in the phenol-acetone unit; 20. Top gas heat exchanger for the benzene tower; 21. External circulating heat exchanger for the alkylation reactor; 22. 23. Condenser at the top of the cumene tower; 24. Hydrocarbon tar discharge cooler; 25. Oxidation feed preheater; 26. Crude fractionation tower feed preheater; 27. Lithium bromide refrigeration unit; 28. Propane removal tower reboiler; 29. ​​Oxidation liquid heater; 20. Propane vaporization heater; 3. Branch of concentrated sulfuric acid pipeline heating system; 4. Circulating return water main pipe; 5. Heat transfer medium tank; A1. Steam heating safety heat exchanger; A2. Deaerator feed water preheater; A3. Circulating water cooling safety heat exchanger. Detailed Implementation

[0025] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] This invention provides a method for the combined utilization of low-temperature waste heat from a CHPPO unit and a phenol-acetone unit, such as... Figure 1As shown, the method is carried out in a heat exchange system including a branch line 1 of the hydrogenolysis unit in the CHPPO removal unit, a branch line 2 of the cumene unit in the phenol-acetone removal unit, a branch line 3 of the concentrated sulfuric acid pipeline heating system, a circulating return water main pipe 4, and a heat transfer medium tank 5. The branch line 1 of the hydrogenolysis unit in the CHPPO removal unit includes a heat exchanger 11 for the external circulating material of the hydrogenolysis reaction stage, a heat exchanger 12 for the gas phase product of the hydrogenolysis reaction, a heat exchanger 13 for the cumene side-stream product of the hydrogenolysis, a circulating heat exchanger 14 for the hydrogenolysis reactor, a heavy component cooler 15, a dehydrogenation tower reboiler 16, and a propylene heater 17. The cumene unit in the phenol-acetone removal unit... Unit branch 2 includes a benzene tower top gas heat exchanger 20, an alkylation reactor external circulation heat exchanger 21, a polyisopropylbenzene tower top condenser 22, a hydrocarbon tar discharge cooler 23, an oxidation feed preheater 24, a coarse fractionation tower feed preheater 25, a lithium bromide refrigeration unit 26, a propane stripper reboiler 27, an oxidation liquid heater 28, and a propane vaporization heater 29. The circulating return water header 4 is used to connect the hydrogenolysis unit branch 1 in the CHPPO removal unit, the cumene unit branch 2 in the phenol-acetone removal unit, and the concentrated sulfuric acid pipeline heating system branch 3. The heat medium water tank 5 is used to store and supply heat medium water. This method involves heat exchange according to the following heat exchange process under initial operating conditions: (1-1) The first heat transfer medium, water, is introduced into branch 1 of the hydrogenolysis unit in the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (1-1a) The first stream of first heat medium water is exchanged with the external circulation material heat exchanger 11 of the hydrogenolysis stage reaction; (1-1b) The second stream of the first heat medium water is exchanged with the heat exchanger 12 for the hydrogenolysis reaction gas phase products; (1-1c) The third stream of the first heat medium water is exchanged with the heat exchanger 13 for the hydrogenated cumene side-stream product; (1-1d) The fourth stream of the first heat transfer medium water is exchanged with the circulating heat exchanger 14 of the hydrogenolysis reactor; (1-1e) The fifth stream of the first heat medium water is exchanged with the recombinant component cooler 15 for heat exchange; Next, the heat transfer water heated in step (1-1e) is directly returned to the circulating return water header 4, and the heat transfer water heated in steps (1-1a) to (1-1d) is combined. Then, the combined first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (1-1f) The first heat medium water after the first stream of confluence is exchanged with the dehydrogenation tower reboiler 16 for heat exchange; (1-1g) The first heat medium water after the second stream of water merges is exchanged with the propylene heater 17 for heat; Next, the first heat medium water after heat exchange and cooling in steps (1-1f) to (1-1g) is collected and returned to the circulating return water header 4; (1-2) The second heat transfer medium water is introduced into the cumene unit branch 2 in the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (1-2a) The first stream of second heat medium water is exchanged with the benzene tower top gas heat exchanger 20, and then this portion of second heat medium water, after being heated by the heat exchange, is exchanged with the external circulation heat exchanger 21 of the alkylation reactor. (1-2b) The second stream of the second heat medium water is exchanged with the polyisopropylbenzene tower top condenser 22 for heat exchange; (1-2c) The third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler 23; Next, the heated medium water from steps (1-2a) to (1-2c) is combined and then divided into a first branch of heated medium water and a second branch of heated medium water. The first branch of heated medium water exchanges heat with the following devices in the phenol-acetone apparatus in parallel: (1-2d) The first stream of the first branch of the heat transfer medium water is exchanged with the oxidation feed preheater 24 for heat; (1-2e) The second stream of the first branch of the hot medium water is exchanged with the feed preheater 25 of the coarse separator tower; Next, the heat transfer medium water cooled down in steps (1-2d) to (1-2e) is collected and returned to the circulating return water header 4; After passing through the steam-heated safety heat exchanger A1, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (1-2f) The first stream of the second branch of the heat transfer medium water is used as the heat source for heat exchange in the lithium bromide refrigeration unit 26; (1-2g) The second stream of the second branch of the heat transfer medium water is exchanged with the reboiler 27 of the propane removal tower; (1-2h) The third stream of the second branch of the heat transfer medium water is exchanged with the oxidation liquid heater 28; (1-2i) The fourth stream of second branch heat transfer medium water is exchanged with the propane vaporization heater 29; Next, the heat transfer water cooled down in steps (1-2f) to (1-2i) is collected and returned to the circulating return water header 4; (1-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the temperature of the sulfuric acid pipeline, and then the heat medium water after heat exchange is returned to the circulating return water header 4. The hot medium water returned to the circulating water header 4 in step (1-1) is combined with the hot medium water returned to the circulating water header 4 in step (1-2), and then passes through the deaerator feedwater preheater A2. After that, it is combined with the hot medium water returned to the circulating water header 4 in step (1-3), and then passes through the circulating water cooling and safety heat exchanger A3 before returning to the hot medium water tank 5.

[0028] In the method described in this invention, preferably, the method further includes performing heat exchange according to the following heat exchange process under final operating conditions: (2-1) The first heat transfer medium, water, is introduced into branch 1 of the hydrogenolysis unit in the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (2-1a) Stop exchanging heat between the first stream of first heat medium water and the external circulation material heat exchanger 11 of the hydrogenolysis stage reaction; (2-1b) The second stream of the first heat transfer medium water is exchanged with the heat exchanger 12 for the hydrogenolysis reaction gas phase products; (2-1c) The third stream of the first heat medium water is exchanged with the heat exchanger 13 for the hydrogenated cumene side-stream product; (2-1d) The fourth stream of the first heat transfer medium water is exchanged with the circulating heat exchanger 14 of the hydrogenolysis reactor; (2-1e) The fifth stream of the first heat medium water is exchanged with the recombinant component cooler 15 for heat exchange; Next, the heat transfer water heated in step (2-1e) is directly returned to the circulating return water header 4, and the heat transfer water heated in steps (2-1b) to (2-1d) is combined. Then, the combined first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (2-1f) The first heat medium water after the first stream of confluence is exchanged with the dehydrogenation tower reboiler 16 for heat exchange; (2-1g) The first heat medium water after the second stream of water merges is exchanged with the propylene heater 17 for heat; Next, the heat transfer water cooled down in steps (2-1f) to (2-1g) is collected and returned to the circulating return water header 4; (2-2) The second heat transfer medium water is introduced into the cumene unit branch 2 in the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (2-2a) The first stream of second heat medium water is exchanged with the benzene tower top gas heat exchanger 20, and then the first stream of second heat medium water after heat exchange and temperature rise is exchanged with the external circulation heat exchanger 21 of the alkylation reactor. (2-2b) The second stream of the second heat medium water is exchanged with the polyisopropylbenzene tower top condenser 22 for heat exchange; (2-2c) The third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler 23 for heat; Next, the heat transfer water after heat exchange and heating in steps (2-2a) to (2-2c) is merged and then split into a first branch of heat transfer water and a second branch of heat transfer water. The first branch of heat transfer water exchanges heat with the following devices in the phenol-acetone unit in parallel according to the following process: (2-2d) The first stream of the first branch of the heat transfer medium water is exchanged with the oxidation feed preheater 24; (2-2e) The second stream of the first branch of the hot medium water is exchanged with the feed preheater 25 of the coarse separator tower; Next, the heat transfer medium water after heat exchange and cooling in steps (2-2d) to (2-2e) is collected and returned to the circulating return water header 4; After passing through the steam-heated safety heat exchanger A1, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (2-2f) The first stream of the second branch of the heat transfer medium water is used as the heat source for heat exchange in the lithium bromide refrigeration unit 26; (2-2g) The second stream of the second branch of the heat transfer medium water is exchanged with the reboiler 27 of the propane removal tower; (2-2h) The third stream of the second branch of the heat transfer medium water is exchanged with the oxidation liquid heater 28; (2-2i) The fourth stream of second branch heat medium water is exchanged with the propane vaporization heater 29; Next, the heat transfer medium water after heat exchange and cooling in steps (2-2f) to (2-2i) is collected and returned to the circulating return water header 4; (2-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the temperature of the sulfuric acid pipeline, and then the heat medium water after heat exchange is returned to the circulating return water main pipe 4. The hot medium water returned to the circulating water header 4 in step (2-1) is combined with the hot medium water returned to the circulating water header 4 in step (2-2), and then passes through the deaerator feedwater preheater A2. After that, it is combined with the hot medium water returned to the circulating water header 4 in step (2-3), and then passes through the circulating water cooling and safety heat exchanger A3 before returning to the hot medium water tank 5.

[0029] In the method described in this invention, preferably, the temperature of the heat transfer water in the heat transfer water tank 5 is 68-72℃, more preferably 69-71℃. In this invention, controlling the temperature of the heat transfer water tank 5 within the above range effectively exchanges heat with the heat sources in each heat exchange branch, minimizing heat loss after heat exchange while cooling the material, and maintaining the overall heat stability of the heat exchange system during operation, thus saving on control costs.

[0030] In the method described in this invention, preferably, with the total flow rate of the heat transfer water output from the heat transfer water tank 5 being 100 parts by weight, under initial operating conditions, the flow rate of the first heat transfer water is 31-34 parts by weight, the flow rate of the second heat transfer water is 41-43 parts by weight, and the flow rate of the third heat transfer water is 25-27 parts by weight; under final operating conditions, the flow rate of the first heat transfer water is 30-32 parts by weight, the flow rate of the second heat transfer water is 45-46 parts by weight, and the flow rate of the third heat transfer water is 22-24 parts by weight. More preferably, under initial operating conditions, the flow rate of the first heat transfer water is 31-32 parts by weight, the flow rate of the second heat transfer water is 42-43 parts by weight, and the flow rate of the third heat transfer water is 25-26 parts by weight; under final operating conditions, the flow rate of the first heat transfer water is 31-32 parts by weight, the flow rate of the second heat transfer water is 45-46 parts by weight, and the flow rate of the third heat transfer water is 22-23 parts by weight.

[0031] In the method described in this invention, preferably, with the first heat transfer water flow rate being 100 parts by weight, under initial operating conditions, the flow rate of the first stream of first heat transfer water in step (1-1a) is 10-12 parts by weight, the flow rate of the second stream of first heat transfer water in step (1-1b) is 50-52 parts by weight, the flow rate of the third stream of first heat transfer water in step (1-1c) is 30-32 parts by weight, and the flow rate of the fourth stream of first heat transfer water in step (1-1d) is 3-5 parts by weight. In step (1-1e), the flow rate of the fifth stream of the first heat medium water is 2-3 parts by weight; under the final operating conditions, the flow rate of the second stream of the first heat medium water in step (2-1b) is 77-80 parts by weight, the flow rate of the third stream of the first heat medium water in step (2-1c) is 14-16 parts by weight, the flow rate of the fourth stream of the first heat medium water in step (2-1d) is 3-4 parts by weight, and the flow rate of the fifth stream of the first heat medium water in step (2-1e) is 2-3 parts by weight. More preferably, under initial operating conditions, the flow rate of the first stream of first heat transfer water in step (1-1a) is 10-11 parts by weight, the flow rate of the second stream of first heat transfer water in step (1-1b) is 51-52 parts by weight, the flow rate of the third stream of first heat transfer water in step (1-1c) is 31-32 parts by weight, the flow rate of the fourth stream of first heat transfer water in step (1-1d) is 4-5 parts by weight, and the flow rate of the fifth stream of first heat transfer water in step (1-1e) is 2-3 parts by weight; under final operating conditions, the flow rate of the second stream of first heat transfer water in step (2-1b) is 78-79 parts by weight, the flow rate of the third stream of first heat transfer water in step (2-1c) is 15-16 parts by weight, the flow rate of the fourth stream of first heat transfer water in step (2-1d) is 3-4 parts by weight, and the flow rate of the fifth stream of first heat transfer water in step (2-1e) is 2-3 parts by weight.

[0032] In the method described in this invention, preferably, with the second heat transfer water flow rate as 100 parts by weight, under initial operating conditions, the flow rate of the first stream of the second heat transfer water in step (1-2a) is 70-73 parts by weight, the flow rate of the second stream of the second heat transfer water in step (1-2b) is 26-28 parts by weight, and the flow rate of the third stream of the second heat transfer water in step (1-2c) is 0.1-1 parts by weight; under final operating conditions, the flow rate of the first stream of the second heat transfer water in step (2-2a) is 74-76 parts by weight, the flow rate of the second stream of the second heat transfer water in step (2-2b) is 23-25 ​​parts by weight, and the flow rate of the third stream of the second heat transfer water in step (2-2c) is 0.1-1 parts by weight. More preferably, under initial operating conditions, the flow rate of the first stream of second heat medium water in step (1-2a) is 71-72 parts by weight, the flow rate of the second stream of second heat medium water in step (1-2b) is 27-28 parts by weight, and the flow rate of the third stream of second heat medium water in step (1-2c) is 0.1-1 parts by weight; under final operating conditions, the flow rate of the first stream of second heat medium water in step (2-2a) is 74-75 parts by weight, the flow rate of the second stream of second heat medium water in step (2-2b) is 23-24 parts by weight, and the flow rate of the third stream of second heat medium water in step (2-2c) is 0.1-1 parts by weight.

[0033] In this invention, by adopting the above-mentioned hot water flow distribution, it is possible to cool the materials in each branch while rationally recovering the low-temperature waste heat generated in each branch, and to minimize unnecessary heat loss and save the amount of hot water used.

[0034] In the method described in this invention, preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (1-1a) to (1-1d) is 127-133°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (2-1a) to (2-1d) is 125-130°C. More preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (1-1a) to (1-1d) is 128-131°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (2-1a) to (2-1d) is 126-128°C. In a specific embodiment, due to the cessation of the heat exchange branch in step (2-1a) under final operating conditions, the temperature of the combined heat transfer water is generally slightly lower than the temperature of the combined heat transfer water under initial operating conditions.

[0035] In the method described in this invention, preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-1f) to (1-1g) is 70-75°C, and under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-1f) to (2-1g) is 73-77°C. More preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-1f) to (1-1g) is 72-74°C, and under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-1f) to (2-1g) is 74-76°C.

[0036] In the method described in this invention, preferably, under initial operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (1-1e) is 83-87°C; under final operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (2-1e) is 83-87°C. More preferably, under initial operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (1-1e) is 84-86°C; under final operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (2-1e) is 84-86°C. In this invention, the heat transfer water that has exchanged heat with the heavy component cooling gas returns directly to the circulating return water header 4 at the above-mentioned temperature range after heat exchange, merging with the remaining heat transfer water after subsequent heat exchange, thus avoiding the loss of low-temperature residual heat in this branch.

[0037] In the method described in this invention, preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (1-2a) to (1-2c) is 114-117°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (2-2a) to (2-2c) is 109-113°C. More preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (1-2a) to (1-2c) is 114-116°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and heating in steps (2-2a) to (2-2c) is 111-113°C.

[0038] In the method described in this invention, preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2d) to (1-2e) is 68-72°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2d) to (2-2e) is 84-88°C. More preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2d) to (1-2e) is 70-72°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2d) to (2-2e) is 85-87°C.

[0039] In this invention, by employing the above-mentioned temperature control, while cooling the reactants, the low-temperature waste heat recovered by the heat exchangers of each heat source in the device can be transferred to the heat trap in the device through the heat transfer medium water, thereby achieving the heating and temperature rise of the materials that need to be heated, making reasonable use of the heat generated by the device itself, and minimizing the heat loss that needs to be directly discharged into the environment, thereby reducing the waste of thermal energy.

[0040] In the method described in this invention, in a preferred embodiment, the steam heating safety heat exchanger A1 is used to maintain the temperature of the second branch heat medium water when the system heat fluctuates significantly, so as to prevent the materials that need to be heated in the CHPPO unit from being unable to be heated to the temperature required for production, and to ensure normal production.

[0041] In the method described in this invention, preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2f) to (1-2i) is 78-82°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2f) to (2-2i) is 78-82°C. More preferably, under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2f) to (1-2i) is 79-81°C; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2f) to (2-2i) is 79-81°C. In a specific embodiment of the present invention, most preferably, the temperature of the heat transfer water after the above steps is combined should be kept as similar as possible in the initial and final operating conditions, so as to facilitate the reuse of excess heat after combination, or the temperature of the heat transfer water can be adjusted to be as similar as possible under different operating conditions by the circulating water cooling security heat exchanger A3, so as to maintain the stability of the overall heat exchange system and facilitate actual control.

[0042] In the method described in this invention, preferably, under the initial operating conditions, after steps (1-1), (1-2) and (1-3), the temperature of the hot water returning to the circulating return water header 4 and merging is 69-73°C; under the final operating conditions, after steps (2-1), (2-2) and (2-3), the temperature of the hot water returning to the circulating return water header 4 and merging is 73-77°C.

[0043] In the method described in this invention, preferably, under initial operating conditions, the circulating water cooling and safety heat exchanger A3 maintains the temperature of the heat transfer water in the circulating return water header 4 at 68-72°C, and then returns it to the heat transfer water tank 5; under final operating conditions, the circulating water cooling and safety heat exchanger A3 maintains the temperature of the heat transfer water in the circulating return water header 4 at 68-72°C, and then returns it to the heat transfer water tank 5.

[0044] In a specific embodiment of the present invention, the method for combined utilization of low-temperature waste heat from the CHPPO unit and the phenol-acetone unit includes: Under initial operating conditions, heat exchange is performed using the following heat exchange process: A total flow rate of 100 parts by weight of heat medium water (68-72℃) is output from heat medium water tank 5 and divided into three streams according to the following proportions: the first heat medium water flow rate is 31-34 parts by weight, the second heat medium water flow rate is 41-43 parts by weight, and the third heat medium water flow rate is 25-27 parts by weight. (1-1) The first heat transfer medium water is introduced into the hydrogenolysis unit branch 1 of the CHPPO unit. The heat exchange is carried out in parallel according to the following process with a flow rate of 100 parts by weight of the first heat transfer medium water: (1-1a) 10-12 parts by weight of the first stream of the first heat medium water are exchanged with the heat exchanger 11 of the external circulation material of the hydrogenolysis stage reaction; (1-1b) 50-52 parts by weight of the second stream of the first heat transfer medium water are exchanged with the heat exchanger 12 for the hydrogenolysis reaction gas phase products; (1-1c) 30-32 parts by weight of the third stream of the first heat medium water are exchanged with the heat exchanger 13 for the hydrogenated cumene side-stream product; (1-1d) 3-5 parts by weight of the fourth stream of the first heat transfer medium water are exchanged with the circulating heat exchanger 14 of the hydrogenolysis reactor; (1-1e) Exchange 2-3 parts by weight of the fifth stream of the first heat medium water with the heavy component cooler 15; Next, the heat transfer water heated to 83-87℃ in step (1-1e) is directly returned to the circulating return water header 4, and the heat transfer water heated in steps (1-1a) to (1-1d) is combined. Then, the combined first heat transfer water (127-133℃) is used as a heat source, and heat exchange is carried out in parallel according to the following process: (1-1f) 28-32 parts by weight of the first heat medium water after the first stream is combined is exchanged with the dehydrogenation tower reboiler 16 for heat exchange; (1-1g) 68-72 parts by weight of the second stream of the first heat medium water after merging are exchanged with the propylene heater 17; Next, the first heat transfer water after heat exchange and cooling in steps (1-1f) to (1-1g) is combined (the temperature after combination is 70-75℃) and returned to the circulating return water header 4; (1-2) The second heat medium water is introduced into the cumene unit branch 2 in the phenol-acetone unit. The heat exchange is carried out in parallel according to the following process with a flow rate of 100 parts by weight of the second heat medium water. (1-2a) 70-73 parts by weight of the first stream of second heat medium water is exchanged with the benzene tower top gas heat exchanger 20, and then this part of the second heat medium water after heat exchange and temperature rise is exchanged with the external circulation heat exchanger 21 of the alkylation reactor. (1-2b) 26-28 parts by weight of the second stream of the second heat medium water are exchanged with the polyisopropylbenzene tower top condenser 22 for heat exchange; (1-2c) 0.1-1 parts by weight of the third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler 23 for heat exchange; Next, the heated water from steps (1-2a) to (1-2c) is combined (at a combined temperature of 114-117°C) and then divided into a first branch of heated water (17-19 parts by weight) and a second branch of heated water (81-83 parts by weight). The first branch of heated water exchanges heat with the following devices in the phenol-acetone apparatus in parallel: (1-2d) The first stream of heat medium water (accounting for 68-70% of the flow rate of the first stream of heat medium water) is exchanged with the oxidation feed preheater 24; (1-2e) The second stream of the first branch of the heat medium water (accounting for 30-32% of the flow rate of the first branch of the heat medium water) is exchanged with the feed preheater 25 of the coarse separator tower; Next, the heat transfer water cooled down in steps (1-2d) to (1-2e) is combined (the combined temperature is 68-72℃) and returned to the circulating return water header 4; After passing through the steam-heated safety heat exchanger A1, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (1-2f) The first stream of the second branch of the heat transfer medium (accounting for 58-61% of the flow rate of the second branch of the heat transfer medium) is used as the heat source for heat exchange in the lithium bromide refrigeration unit 26; (1-2g) The second stream of heat medium water (accounting for 27-30% of the flow rate of the second stream of heat medium water) is exchanged with the reboiler 27 of the propane removal tower. (1-2h) The third stream of the second branch of the heat transfer medium (accounting for 8-11% of the flow rate of the second branch of the heat transfer medium) is exchanged with the oxidation liquid heater 28 for heat exchange; (1-2i) The fourth stream of the second branch of the heat transfer medium (accounting for 0.5-2% of the flow rate of the second branch of the heat transfer medium) is exchanged with the propane vaporization heater 29; Next, the heat transfer water cooled down in steps (1-2f) to (1-2i) is combined (the combined temperature is 78-82℃) and returned to the circulating return water header 4; (1-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the sulfuric acid pipeline temperature at 54-56℃, and then the heat medium water after heat exchange (temperature of 58-62℃) is returned to the circulating return water header 4. The hot medium water returned to the circulating water header 4 in step (1-1) is combined with the hot medium water returned to the circulating water header 4 in step (1-2) (the temperature after combination is 73-77℃), and then passes through the deaerator feedwater preheater A2, and then merges with the hot medium water returned to the circulating water header 4 in step (1-3) (the temperature after combination is 69-73℃), and then passes through the circulating water cooling and security heat exchanger A3 to keep the temperature of the hot medium water at 68-72℃ before returning to the hot medium water tank 5; Heat exchange should be performed under final operating conditions according to the following steps: A total flow rate of 100 parts by weight of heat medium water (68-72℃) is output from heat medium water tank 5 and divided into three streams according to the following proportions: the first heat medium water flow rate is 31-34 parts by weight, the second heat medium water flow rate is 41-43 parts by weight, and the third heat medium water flow rate is 25-27 parts by weight. (2-1) The first heat transfer medium water is introduced into the hydrogenolysis unit branch 1 of the CHPPO unit, with a flow rate of 100 parts by weight, and heat exchange is carried out in parallel according to the following process: (2-1a) Stop exchanging heat between the first stream of first heat medium water and the external circulation material heat exchanger 11 of the hydrogenolysis stage reaction; (2-1b) 77-80 parts by weight of the second stream of the first heat transfer medium water are exchanged with the heat exchanger 12 for the hydrogenolysis reaction gas phase products; (2-1c) 14-16 parts by weight of the third stream of the first heat medium water are exchanged with the heat exchanger 13 for the hydrogenated cumene side-stream product; (2-1d) 3-4 parts by weight of the fourth stream of the first heat transfer medium water are exchanged with the circulating heat exchanger 14 of the hydrogenolysis reactor; (2-1e) Exchange 2-3 parts by weight of the fifth stream of the first heat medium water with the heavy component cooler 15; Next, the heat transfer water heated to 83-87℃ in step (2-1e) is directly returned to the circulating return water header 4, and the heat transfer water heated in steps (2-1b) to (2-1d) is combined (the combined temperature is 125-130℃). The combined first heat transfer water is then used as a heat source, and heat exchange is performed in parallel according to the following process: (2-1f) 31-34 parts by weight of the first heat medium water after the first stream is combined is exchanged with the dehydrogenation tower reboiler 16 for heat exchange; (2-1g) 66-69 parts by weight of the second stream of the first heat medium water after merging are exchanged with the propylene heater 17; Next, the heat transfer water cooled down in steps (2-1f) to (2-1g) is combined (the combined temperature is 73-77℃) and returned to the circulating return water header 4; (2-2) The second heat medium water is introduced into the cumene unit branch 2 in the phenol-acetone unit. The heat exchange is carried out in parallel according to the following process with a flow rate of 100 parts by weight of the second heat medium water. (2-2a) 74-76 parts by weight of the first stream of the second heat medium water is exchanged with the benzene tower top gas heat exchanger 20, and then the first stream of the second heat medium water after heat exchange and temperature rise is exchanged with the external circulation heat exchanger 21 of the alkylation reactor. (2-2b) 23-25 ​​parts by weight of the second stream of the second heat medium water are exchanged with the polyisopropylbenzene tower top condenser 22 for heat exchange; (2-2c) 0.1-1 parts by weight of the third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler 23 for heat exchange; Next, the heat transfer water heated in steps (2-2a) to (2-2c) is combined (the combined temperature is 109-113℃) and then divided into 20-22 parts by weight of the first branch of heat transfer water and 78-80 parts by weight of the second branch of heat transfer water. The first branch of heat transfer water exchanges heat with the following devices in the phenol-acetone apparatus in parallel according to the following process: (2-2d) The first stream of heat medium water (accounting for 28-31% of the flow rate of the first stream of heat medium water) is exchanged with the oxidation feed preheater 24 for heat exchange; (2-2e) The second stream of the first branch of the heat medium water (accounting for 69-72% of the flow rate of the first branch of the heat medium water) is exchanged with the feed preheater 25 of the coarse separator tower; Next, the heat transfer water cooled down in steps (2-2d) to (2-2e) is combined (the combined temperature is 84-88℃) and returned to the circulating return water header 4; After passing through the steam-heated safety heat exchanger A1, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (2-2f) The first stream of the second branch of the heat transfer medium (accounting for 60-63% of the flow rate of the second branch of the heat transfer medium) is used as the heat source for heat exchange in the lithium bromide refrigeration unit 26; (2-2g) The second stream of heat medium water (accounting for 28-30% of the flow rate of the second stream of heat medium water) is exchanged with the reboiler 27 of the propane removal tower. (2-2h) The third stream of the second branch of the heat transfer medium (accounting for 6-8% of the flow rate of the second branch of the heat transfer medium) is exchanged with the oxidation liquid heater 28 for heat exchange; (2-2i) The fourth stream of the second branch of the heat transfer medium (accounting for 0.5-3% of the flow rate of the second branch of the heat transfer medium) is exchanged with the propane vaporization heater 29; Next, the heat transfer water cooled down in steps (2-2f) to (2-2i) is combined (the combined temperature is 78-82℃) and returned to the circulating return water header 4; (2-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the sulfuric acid pipeline temperature at 54-56℃. Then the heat medium water (temperature 58-62℃) after heat exchange is returned to the circulating return water header 4. The hot medium water returned to the circulating water return header 4 in step (2-1) is combined with the hot medium water returned to the circulating water return header 4 in step (2-2) (the temperature after combination is 78-82℃), and then passes through the deaerator feedwater preheater A2, and then merges with the hot medium water returned to the circulating water return header 4 in step (2-3) (the temperature after combination is 73-77℃). After passing through the circulating water cooling and security heat exchanger A3 to keep the temperature of the hot medium water at 68-72℃, it returns to the hot medium water tank 5.

[0045] According to the method for combined utilization of low-temperature waste heat from the CHPPO and phenol-acetone units described in this invention, through reasonable planning and design, multiple circulation branches are set up to connect different heat sources and heat traps within the CHPPO and phenol-acetone units. Heat exchange is conducted in parallel within each circulation branch, transferring heat from the heat-generating units within the units to the units requiring heating via hot water, saving additional energy required for heating and reducing energy consumption and costs. Based on the different operating conditions of the units in the initial and final stages of operation, each heat exchange component of each branch is controlled and adjusted from a holistic perspective, rationally planning and utilizing the low-temperature waste heat of each unit to reduce heat loss directly discharged into the environment. The heat exchange system also includes a steam-heated safety heat exchanger and a circulating water-cooled safety heat exchanger to maintain the stability and controllability of the overall heat exchange system, ensuring the normal operation of the production unit.

[0046] In this invention, the initial operating condition refers to the initial operating condition of the CHPPO unit determined based on the activity of the reaction catalyst, and the final operating condition refers to the final operating condition of the CHPPO unit determined based on the activity of the reaction catalyst. The activity of the reaction catalyst can be determined by monitoring the temperature and pressure changes of the device in which the reaction occurs. The criterion for determination is that when the activity of the reaction catalyst shows a significant decrease, it is considered to have entered the final operating condition.

[0047] In a specific embodiment of the present invention, the heat exchange process parameters under the initial and final operating conditions are obtained by the following method: A concentrated statistical analysis was conducted on the low-temperature waste heat generated in the CHPPO and phenol-acetone units. Basic data such as material parameters and cooling loads requiring air or water cooling, and material temperature parameters and heat loads requiring heating were collected. Potential heat users within the project area, including those requiring low-pressure steam heating, heat tracing, and temperature maintenance, were screened and analyzed. Based on the overall energy balance, a heat flow balance diagram was established using water as the heat transfer medium and pinch technology. Figure 4As shown, based on the principle of optimal overall energy saving, the heat-generating and heat-consuming process materials are precisely coupled and matched bidirectionally according to temperature gradient, reasonable heat exchange temperature difference and heat load, thereby broadening the efficient utilization range of low-temperature waste heat, constructing a global heat exchange network, and creating a series and parallel heat exchange process flow diagram of the heat transfer medium water in the chemical system.

[0048] Based on the re-optimization and balance of steam within the unit, the heat exchanger, which originally used low-pressure steam heating, was adjusted to use hot water as the heating medium. According to the activity of the catalyst in the initial and final stages of the CHPPO unit, after iterative optimization, the theoretical amount of hot water to be extracted from the low-temperature waste heat of units such as isopropylbenzene and hydrogenolysis was determined. The hot water was then distributed to various feed preheating, propane gasification and other equipment as needed, so as to achieve low-temperature waste heat recovery and utilization of the chemical plant through multi-step collaborative efforts.

[0049] Based on the pinch temperature in the heat flow balance diagram and the reasonable heat exchange temperature difference requirements of general-purpose heat exchangers, the optimal theoretical cold end temperature of the circulating heat transfer medium is determined to be 70℃. Based on the hydraulic and thermodynamic simulation results of the circulating heat transfer medium system, the optimal theoretical system water pressure is determined to be 1.2MPa. Heat transfer medium is pumped from heat transfer medium tank 5 into the circulating return water header 4, and simultaneously supplied to the hydrogenolysis unit, the cumene unit in the phenol-acetone system, and the concentrated sulfuric acid pipeline heat tracing system in three parallel loops for heat exchange. Due to the special requirements of the concentrated sulfuric acid pipeline, this heat transfer medium draws heat from the circulating heat transfer medium system to supply the pipeline for heat tracing and temperature maintenance, operating independently and not participating in the low-temperature waste heat recovery and utilization of other facilities within the unit.

[0050] The following examples further illustrate the method for combined utilization of low-temperature waste heat from the CHPPO and phenol-acetone devices according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0051] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0052] Example 1 like Figure 2 As shown, heat exchange is carried out according to the following heat exchange process under initial operating conditions: 855.8 t / h of hot medium water at a temperature of 70℃ (68-72℃) is output from the hot medium water tank 5 and divided into three streams according to the following ratio: the first hot medium water flow rate is 273.4 t / h, the second hot medium water flow rate is 362.4 t / h, and the third hot medium water flow rate is 220 t / h. (1-1) The first heat transfer medium water is introduced into the hydrogenolysis unit branch 1 in the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (1-1a) The first stream of 30t / h heat transfer medium water is exchanged with the external circulation material heat exchanger 11 of the hydrogenolysis stage reaction, so that the material temperature is cooled from 146.7℃ to 100℃, the heat is extracted by 1.81MW, and the heat transfer medium water temperature is raised from 70℃ to 121.7℃. (1-1b) The second stream of first heat transfer medium water with a capacity of 140t / h is exchanged with the heat exchanger 12 for the gaseous products of the hydrogenolysis reaction, so that the material temperature is cooled from 168℃ to 100℃, the heat is extracted by 10.1MW, and the heat transfer medium water temperature is raised from 70℃ to 131.8℃. (1-1c) The third stream of first heat medium water with a capacity of 85t / h is exchanged with the heat exchanger 13 for the hydrogenolysis of cumene side-stream products, so that the material temperature is cooled from 143.6℃ to 100℃, heat is extracted by 5.91MW, and the heat medium water temperature is raised from 70℃ to 129.6℃. (1-1d) The fourth stream of first heat medium water with a capacity of 11t / h is exchanged with the circulating heat exchanger 14 of the hydrogen decomposition reactor to extract 0.8MW of heat, maintain the material temperature at 169℃, and raise the temperature of the heat medium water from 70℃ to 132.3℃. (1-1e) The fifth stream of first heat medium water with a capacity of 7.4 t / h is exchanged with the heavy component cooler 15 to cool the material temperature from 105℃ to 85℃, extracting 0.13 MW of heat, and raising the temperature of the heat medium water from 70℃ to 85.1℃; Next, the heat transfer water heated to 85.1℃ in step (1-1e) is directly returned to the circulating return water header 4, and the heat transfer water heated in steps (1-1a) to (1-1d) is combined. Then, the combined 130℃, totaling 266t / h of the first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (1-1f) The first hot water after the first stream of 80t / h is combined with the reboiler 16 of the dehydrogenation tower to heat the material temperature from 70℃ to 72℃, recover 4.39MW of low-temperature waste heat, and cool the hot water temperature from 130℃ to 88.1℃. (1-1g) The first heat medium water after the second stream of 186t / h is combined with the propylene heater 17 to exchange heat, heating the material temperature from 55℃ to 115℃, recovering 13.23MW of low-temperature waste heat, and cooling the heat medium water temperature from 130℃ to 69℃. Next, 266 t / h of the first heat transfer water after heat exchange and cooling in steps (1-1f) to (1-1g) is combined (the combined temperature is 73.2℃) and returned to the circulating return water header 4; (1-2) The second heat transfer medium water is introduced into the cumene unit branch 2 in the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (1-2a) The first stream of second heat transfer medium water with a capacity of 260 t / h is exchanged with the heat exchanger 20 of the benzene tower top gas to cool the material temperature from 114°C to 90°C, extracting 10.3 MW of heat, and raising the temperature of the heat transfer medium water from 70°C to 104°C; then this portion of second heat transfer medium water after heat exchange and heating is exchanged with the external circulation heat exchanger 21 of the alkylation reactor to cool the material temperature from 150°C to 115°C, extracting 5.19 MW of heat, and raising the temperature of the heat transfer medium water from 104°C to 121.1°C; (1-2b) The second stream of second heat medium water with a capacity of 100t / h is exchanged with the top condenser 22 of the polyisopropylbenzene tower to cool the material temperature from 117℃ to 85℃, extracting 3.79MW of heat, and raising the temperature of the heat medium water from 70℃ to 102.5℃. (1-2c) The third stream of second heat medium water with a capacity of 2.4t / h is exchanged with the hydrocarbon tar discharge cooler 23 to cool the material temperature from 117℃ to 80℃, and the heat is extracted by 0.028MW. The temperature of the heat medium water is raised from 70℃ to 79.8℃. Next, the 362.4 t / h of heat transfer water heated in steps (1-2a) to (1-2c) is combined (the combined temperature is 115.7℃) and split into a first branch of 65 t / h and a second branch of 397.4 t / h. The first branch of heat transfer water exchanges heat with the following devices in the phenol-acetone unit in parallel: (1-2d) The first branch of the 45t / h hot water in the first stream exchanges heat with the oxidation feed preheater 24 to heat the material temperature from 57℃ to 66℃, recover 2MW of low-temperature waste heat, and cool the hot water temperature from 115.7℃ to 77.6℃. (1-2e) The second stream of the first branch of the 20t / h heat medium water is exchanged with the feed preheater 25 of the coarse separator tower to heat the material temperature from 40℃ to 80℃, recover 1.4MW of low-temperature waste heat, and cool the heat medium water temperature from 115.7℃ to 55.8℃. Next, the heat transfer water cooled down in steps (1-2d) to (1-2e) is combined (the combined temperature is 68-72℃) and returned to the circulating return water header 4; After passing through the steam-heated safety heat exchanger A1, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (1-2f) The first and second branch of the 117.4t / h heat transfer medium water is used as the heat source for the lithium bromide refrigeration unit 26, and 8.44MW of low-temperature waste heat is recycled. The temperature of the heat transfer medium water is cooled from 115.7℃ to 75℃. (1-2g) The second branch of the 85t / h second stream of hot water is exchanged with the reboiler 27 of the propane dehydrogenation tower to heat the material temperature from 57℃ to 58℃, recover 3.48MW of low-temperature waste heat, and cool the hot water temperature from 115.7℃ to 80.6℃. (1-2h) The 30t / h third stream second branch of the heat transfer medium water is exchanged with the oxidation liquid heater 28 to heat the material temperature from 60℃ to 72℃, recover 1.18MW of low-temperature waste heat, and cool the heat transfer medium water temperature from 115.7℃ to 81.9℃. (1-2i) The 5t / h fourth second branch of the hot water exchanged heat with the propane gasification heater 29, heating the material temperature from 60℃ to about 72℃, recovering 0.11MW of low-temperature waste heat, and cooling the hot water temperature from 115.7℃ to 80.4℃. Next, the heat transfer water after heat exchange and cooling in steps (1-2f) to (1-2i) totaling 297.4 t / h is combined (the combined temperature is 80.4℃) and returned to the circulating return water header 4; (1-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the sulfuric acid pipeline temperature at 55°C. Then the heat medium water (temperature 60.1°C) after heat exchange is returned to the circulating return water header 4. The hot medium water returned to the circulating water return header 4 in step (1-1) is combined with the hot medium water returned to the circulating water return header 4 in step (1-2) (the temperature after combination is 75.2℃), and then passes through the deaerator feedwater preheater A2, and then merges with the hot medium water returned to the circulating water return header 4 in step (1-3) (the temperature after combination is 71.3℃). After passing through the circulating water cooling and security heat exchanger A3 to maintain the temperature of the hot medium water at 70℃, it returns to the hot medium water tank 5. Under initial operating conditions, approximately 38.06 MW of low-temperature waste heat can be recovered and reused, with approximately 36.78 MW being reused, resulting in a low-temperature waste heat recovery and utilization efficiency of 96.6%.

[0053] Example 2 like Figure 3 As shown, heat exchange is performed according to the following steps under the final operating conditions: 958.4 t / h of hot medium water at a temperature of 70℃ (68-72℃) is output from the hot medium water tank 5 and divided into three streams according to the following ratio: the first hot medium water flow rate is 298.4 t / h, the second hot medium water flow rate is 440 t / h, and the third hot medium water flow rate is 220 t / h. (2-1) The first heat transfer medium, water, is introduced into branch 1 of the hydrogenolysis unit in the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (2-1a) Stop exchanging heat between the first stream of first heat medium water and the external circulation material heat exchanger 11 of the hydrogenolysis stage reaction; (2-1b) The second stream of first heat transfer medium water with a capacity of 235t / h is exchanged with the heat exchanger 12 for the gaseous products of the hydrogenolysis reaction, cooling the material temperature from 146.7℃ to 100℃, extracting 17.59MW of heat, and raising the temperature of the heat transfer medium water from 70℃ to 134.2℃. (2-1c) The third stream of first heat medium water with a capacity of 45t / h is exchanged with the heat exchanger 13 of the hydrogen-decomposed cumene side-stream product to cool the material temperature from 105℃ to 100℃, extract 1.05MW of heat, and raise the temperature of the heat medium water from 70℃ to 90℃. (2-1d) The fourth stream of first heat medium water with a capacity of 11t / h is exchanged with the circulating heat exchanger 14 of the hydrogen decomposition reactor to extract 0.8MW of heat, maintain the material temperature at 169℃, and raise the temperature of the heat medium water from 70℃ to 132.3℃. (2-1e) The fifth stream of the first heat medium water with a capacity of 7.4 t / h is exchanged with the heavy component cooler 15 to cool the material temperature from 105℃ to 85℃, and the heat is extracted by 0.13 MW. The temperature of the heat medium water is raised from 70℃ to 85.1℃. Next, the 7.4 t / h heat transfer water heated to 85.1℃ in step (2-1e) is directly returned to the circulating return water header 4, and the 291 t / h heat transfer water heated in steps (2-1b) to (2-1d) is combined (the combined temperature is 127.3℃). The combined first heat transfer water is then used as a heat source, and heat exchange is carried out in parallel according to the following process: (2-1f) The first heat medium water after the first stream of 96t / h is combined is exchanged with the reboiler 16 of the dehydrogenation tower to heat the material temperature from 70℃ to 72℃, recover 4.39MW of low-temperature waste heat, and cool the heat medium water temperature from 127.3℃ to 88.1℃. (2-1g) The first heat medium water after the second stream of 195t / h merges is exchanged with the propylene heater 17 to heat the material temperature from 55℃ to 115℃, recover 13.23MW of low-temperature waste heat, and cool the heat medium water temperature from 127.3℃ to 69.1℃. Next, 291 t / h of the heat transfer water after heat exchange and cooling in steps (2-1f) to (2-1g) is combined (the combined temperature is 75.4℃) and returned to the circulating return water header 4; (2-2) 440t / h of the second heat medium water is introduced into the cumene unit branch 2 in the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (2-2a) The first stream of second heat transfer medium water with a capacity of 330 t / h is exchanged with the heat exchanger 20 of the benzene tower top gas to cool the material temperature from 114℃ to 90℃, with a heat output of 10.3 MW and the heat transfer medium water temperature is raised from 70℃ to 96.8℃; then the first stream of second heat transfer medium water with the heat exchanged and heated is exchanged with the external circulation heat exchanger 21 of the alkylation reactor to cool the material temperature from 150℃ to 104℃, with a heat output of 6.82 MW and the heat transfer medium water temperature is raised from 104℃ to 114.5℃; (2-2b) The second stream of second heat medium water with a capacity of 107.6 t / h is exchanged with the top condenser 22 of the polyisopropylbenzene tower to cool the material temperature from 117°C to 80°C, extracting 4.38 MW of heat, and raising the temperature of the heat medium water from 70°C to 104.9°C. (2-2c) The third stream of second heat medium water with a capacity of 2.4t / h is exchanged with the hydrocarbon tar discharge cooler 23 to cool the material temperature from 117℃ to 80℃, and the heat is extracted by 0.028MW. The temperature of the heat medium water is raised from 70℃ to 79.8℃. Next, the 440 t / h of heat transfer water heated by heat exchange in steps (2-2a) to (2-2c) is combined (the combined temperature is 111.9℃) and split into a first branch of 92.6 t / h and a second branch of 319.7 t / h. The remaining 27.7 t / h of heat transfer water is returned to the circulating return water header 4 via the heat transfer water bypass. The first branch of heat transfer water exchanges heat with the following devices in the phenol-acetone unit in parallel according to the following process: (2-2d) The first branch of the 27.4t / h hot water in the first stream exchanges heat with the oxidation feed preheater 24, heating the material temperature from 57℃ to 65℃, recovering 1.49MW of low-temperature waste heat, and cooling the hot water temperature from 111.9℃ to 65.3℃. (2-2e) The second stream of the first branch of the 65.2t / h hot water is exchanged with the feed preheater 25 of the coarse separator to heat the material temperature from 75℃ to 95℃, recover 1.29MW of low-temperature waste heat, and cool the hot water temperature from 111.9℃ to 95℃. Next, the heat transfer water cooled down in steps (2-2d) to (2-2e) totaling 92.6 t / h is combined (the combined temperature is 96.2℃) and returned to the circulating return water header 4; After passing through the steam-heated safety heat exchanger A1, the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (2-2f) The first and second branch of the 197.4t / h heat transfer medium water is used as the heat source for the lithium bromide refrigeration unit 26, and 7.37MW of low-temperature waste heat is recycled. The temperature of the heat transfer medium water is cooled from 111.9℃ to 80℃. (2-2g) The second branch of the second stream of 93.5t / h hot water is exchanged with the reboiler 27 of the propane dehydrogenation tower to heat the material temperature from 57℃ to 58℃, recover 3.48MW of low-temperature waste heat, and cool the hot water temperature from 111.9℃ to 80℃. (2-2h) The second branch of the third stream of 23.8t / h heat transfer water is exchanged with the oxidation liquid heater 28 to heat the material temperature from 60℃ to 72℃, recover 0.89MW of low-temperature waste heat, and cool the heat transfer water temperature from 111.9℃ to 80℃. (2-2i) The 5t / h fourth second branch of the heat transfer medium water is exchanged with the propane gasification heater 29 to heat the material temperature from 60℃ to 72℃, recover 0.04MW of low-temperature waste heat, and cool the heat transfer medium water temperature from 111.9℃ to 104.7℃. Next, the heat transfer water after heat exchange and cooling in steps (2-2f) to (2-2i) totaling 319.7 t / h is combined (the combined temperature is 80.4℃) and returned to the circulating return water header 4; (2-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the sulfuric acid pipeline temperature at 55°C. Then the heat medium water (temperature 60.1°C) after heat exchange is returned to the circulating return water header 4. The hot medium water returned to the circulating water header 4 in step (2-1) and the hot medium water returned to the circulating water header 4 in step (2-2) totaling 738.4 t / h are combined (the temperature after combination is 80.4℃), and then pass through the deaerator feedwater preheater A2. Then, it is combined with the hot medium water returned to the circulating water header 4 in step (2-3) totaling 220 t / h (the temperature after combination is 75.8℃). After passing through the circulating water cooling and security heat exchanger A3 to maintain the temperature of the hot medium water at 70℃, it is returned to the hot medium water tank 5. Under the final operating conditions, approximately 41.1 MW of low-temperature waste heat can be recovered and approximately 34.74 MW can be reused, with a low-temperature waste heat recovery and utilization efficiency of approximately 84.5%.

[0054] Therefore, the method for combined utilization of low-temperature waste heat from the CHPPO and phenol-acetone units described in this invention can fully recover and utilize the low-temperature waste heat from both units after the entire system is put into operation. In the initial and final operating conditions, a total of 38.06 MW and 41.1 MW of low-temperature waste heat can be recovered from the CHPPO and phenol-acetone units, respectively, with recovery efficiencies of 96.6% and 84.5%, demonstrating high recovery efficiency. Furthermore, 36.78 MW and 34.74 MW of low-temperature waste heat will be reused for materials requiring heating in the heating unit, equivalent to saving 55 t / h and 52 t / h of S5 steam, respectively. Compared to independently using circulating water cooling and steam heating, this method simultaneously reduces the circulating water equivalent for system cooling by approximately 3300 tons / hour, saves approximately 43,000 tons / year of standard coal, and reduces CO2 emissions by approximately 113,000 tons / year, demonstrating significant energy, environmental, and economic benefits.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for combined utilization of low-temperature waste heat from a CHPPO device and a phenol acetone device, characterized in that, The method is carried out in a heat exchange system including a branch line (1) of the hydrogenolysis unit in the CHPPO unit, a branch line (2) of the cumene unit in the phenol-acetone unit, a branch line (3) of the concentrated sulfuric acid pipeline heating system, a circulating return water main pipe (4) and a heat transfer medium tank (5). The branch line (1) of the hydrogenolysis unit in the CHPPO unit includes a heat exchanger (11) of the external circulating material in the hydrogenolysis stage reaction, a heat exchanger (12) of the gas phase product in the hydrogenolysis reaction, a heat exchanger (13) of the cumene side-stream product in the hydrogenolysis, a circulating heat exchanger (14) of the hydrogenolysis reactor, a heavy component cooler (15), a dehydrogenation tower reboiler (16) and a propylene heater (17). The branch line (2) of the cumene unit in the phenol-acetone unit... (2) Includes a benzene tower top gas heat exchanger (20), an alkylation reactor external circulation heat exchanger (21), a polyisopropylbenzene tower top condenser (22), a hydrocarbon tar discharge cooler (23), an oxidation feed preheater (24), a coarse fractionation tower feed preheater (25), a lithium bromide refrigeration unit (26), a propane removal tower bottom reboiler (27), an oxidation liquid heater (28), and a propane gasification heater (29). The circulating return water header (4) is used to connect the hydrogenolysis unit branch (1) in the CHPPO removal unit, the isopropylbenzene unit branch (2) in the phenol-acetone removal unit, and the concentrated sulfuric acid pipeline heating system branch (3). The heat medium water tank (5) is used to store and supply heat medium water. This method involves heat exchange according to the following heat exchange process under initial operating conditions: (1-1) The first heat transfer medium water is introduced into the hydrogenolysis unit branch (1) of the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (1-1a) The first stream of first heat medium water is exchanged with the heat exchanger (11) of the external circulation material of the hydrogenolysis stage reaction; (1-1b) The second stream of the first heat medium water is exchanged with the heat exchanger (12) for the hydrogenolysis reaction gas phase products; (1-1c) The third stream of the first heat medium water is exchanged with the heat exchanger (13) for the hydrogenated cumene side-stream product; (1-1d) The fourth stream of the first heat medium water is exchanged with the circulating heat exchanger (14) of the hydrogenolysis reactor; (1-1e) The fifth stream of the first heat medium water is exchanged with the recombinant component cooler (15) for heat exchange; Next, the heat transfer water heated by heat exchange in step (1-1e) is directly returned to the circulating return water header (4), and the heat transfer water heated by heat exchange in steps (1-1a) to (1-1d) is combined. Then, the combined first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (1-1f) The first heat medium water after the first stream of confluence is exchanged with the dehydrogenation tower reboiler (16) for heat exchange; (1-1g) The first heat medium water after the second stream of water merges is exchanged with the propylene heater (17) for heat; Next, the first heat medium water after heat exchange and cooling in steps (1-1f) to (1-1g) is merged and returned to the circulating return water header (4). (1-2) The second heat transfer medium water is introduced into the cumene unit branch (2) of the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (1-2a) The first stream of second heat medium water is heated with the benzene tower top gas heat exchanger (20), and then this portion of second heat medium water, after being heated by the heat exchange, is heated with the external circulation heat exchanger (21) of the alkylation reactor; (1-2b) The second stream of the second heat medium water is exchanged with the polyisopropylbenzene tower top condenser (22) for heat exchange; (1-2c) The third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler (23) for heat exchange; Next, the heated medium water from steps (1-2a) to (1-2c) is combined and then divided into a first branch of heated medium water and a second branch of heated medium water. The first branch of heated medium water exchanges heat with the following devices in the phenol-acetone apparatus in parallel: (1-2d) The first stream of the first branch of the heat transfer medium water is exchanged with the oxidation feed preheater (24); (1-2e) The second stream of the first branch of the hot medium water is exchanged with the feed preheater (25) of the coarse separator; Next, the heat transfer water after heat exchange and cooling in steps (1-2d) to (1-2e) is collected and returned to the circulating return water header (4). After passing through the steam-heated safety heat exchanger (A1), the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (1-2f) The first stream of the second branch of the heat transfer medium water is used as the heat source for the lithium bromide refrigeration unit (26); (1-2g) The second stream of the second branch of the heat transfer medium water is exchanged with the reboiler (27) of the propane removal tower; (1-2h) The third stream of the second branch of the heat transfer medium water is exchanged with the oxidation liquid heater (28) for heat exchange; (1-2i) The fourth second branch of the heat transfer medium water is exchanged with the propane vaporization heater (29); Next, the heat transfer medium water after heat exchange and cooling in steps (1-2f) to (1-2i) is merged and returned to the circulating return water header (4). (1-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system for heat exchange to maintain the temperature of the sulfuric acid pipeline, and then the heat medium water after heat exchange is returned to the circulating return water main pipe (4). The hot water returned to the circulating return water header (4) in step (1-1) is combined with the hot water returned to the circulating return water header (4) in step (1-2), and then passes through the deaerator feed water preheater (A2), and then merges with the hot water returned to the circulating return water header (4) in step (1-3), and then passes through the circulating water cooling security heat exchanger (A3) before returning to the hot water tank (5).

2. The method of claim 1, wherein, The method also includes performing heat exchange according to the following heat exchange process under final operating conditions: (2-1) The first heat transfer medium water is introduced into the hydrogenolysis unit branch (1) of the CHPPO unit, and heat exchange is carried out in parallel according to the following process: (2-1a) Stop exchanging heat between the first stream of first heat medium water and the external circulation material heat exchanger (11) of the hydrogenolysis stage reaction; (2-1b) The second stream of the first heat medium water is exchanged with the heat exchanger (12) for the gaseous products of the hydrogenolysis reaction; (2-1c) The third stream of the first heat medium water is exchanged with the heat exchanger (13) for the hydrogenated cumene side-stream product; (2-1d) The fourth stream of the first heat transfer medium water is exchanged with the circulating heat exchanger (14) of the hydrogenolysis reactor; (2-1e) The fifth stream of the first heat medium water is exchanged with the heavy component cooler (15) for heat exchange; Next, the heat transfer water heated in step (2-1e) is directly returned to the circulating return water header (4), and the heat transfer water heated in steps (2-1b) to (2-1d) is combined. Then, the combined first heat transfer water is used as a heat source, and heat exchange is carried out in parallel according to the following process: (2-1f) The first heat medium water after the first stream of confluence is exchanged with the dehydrogenation tower reboiler (16) for heat exchange; (2-1g) The first heat medium water after the second stream of water merges is exchanged with the propylene heater (17) for heat exchange; Next, the heat transfer water after heat exchange and cooling in steps (2-1f) to (2-1g) is collected and returned to the circulating return water header (4). (2-2) The second heat transfer medium water is introduced into the cumene unit branch (2) of the phenol-acetone unit, and heat exchange is carried out in parallel according to the following process; (2-2a) The first stream of second heat medium water is heated with the benzene tower top gas heat exchanger (20), and then the heated first stream of second heat medium water is heated with the external circulation heat exchanger (21) of the alkylation reactor. (2-2b) The second stream of the second heat medium water is exchanged with the polyisopropylbenzene tower top condenser (22) for heat exchange; (2-2c) The third stream of the second heat medium water is exchanged with the hydrocarbon tar discharge cooler (23) for heat exchange; Next, the heat transfer water after heat exchange and heating in steps (2-2a) to (2-2c) is merged and then split into a first branch of heat transfer water and a second branch of heat transfer water. The first branch of heat transfer water exchanges heat with the following devices in the phenol-acetone unit in parallel according to the following process: (2-2d) The first stream of the first branch of the heat transfer medium water is exchanged with the oxidation feed preheater (24); (2-2e) The second stream of the first branch of the hot medium water is exchanged with the feed preheater (25) of the coarse separator; Next, the heat transfer water after heat exchange and cooling in steps (2-2d) to (2-2e) is collected and returned to the circulating return water header (4). After passing through the steam-heated safety heat exchanger (A1), the second branch of the hot water exchanger exchanges heat with the following devices in the CHPPO unit in parallel: (2-2f) The first stream of the second branch of the heat transfer medium water is used as the heat source for the lithium bromide refrigeration unit (26); (2-2g) The second stream of the second branch of the heat transfer medium water is exchanged with the reboiler (27) of the propane removal tower; (2-2h) The third stream of the second branch of the heat transfer medium water is exchanged with the oxidation liquid heater (28) for heat; (2-2i) The fourth second branch of the heat transfer medium water is exchanged with the propane vaporization heater (29); Next, the heat transfer water after heat exchange and cooling in steps (2-2f) to (2-2i) is collected and returned to the circulating return water header (4). (2-3) A third heat medium water is introduced into the branch of the sulfuric acid pipeline heat tracing system to exchange heat and maintain the temperature of the sulfuric acid pipeline. Then the heat medium water after heat exchange is returned to the circulating return water main pipe (4). The hot medium water returned to the circulating return water header (4) in step (2-1) is combined with the hot medium water returned to the circulating return water header (4) in step (2-2), and then passes through the deaerator feed water preheater (A2), and then merges with the hot medium water returned to the circulating return water header (4) in step (2-3), and then passes through the circulating water cooling security heat exchanger (A3) before returning to the hot medium water tank (5).

3. The method according to claim 1 or 2, characterized in that, The temperature of the heat medium water in the heat medium tank (5) is 68-72℃.

4. The method according to any one of claims 1 to 3, characterized in that, With the total flow rate of the heat medium water output from the heat medium water tank (5) as 100 parts by weight, under the initial operating conditions, the flow rate of the first heat medium water is 31-34 parts by weight, the flow rate of the second heat medium water is 41-43 parts by weight, and the flow rate of the third heat medium water is 25-27 parts by weight; under the final operating conditions, the flow rate of the first heat medium water is 30-32 parts by weight, the flow rate of the second heat medium water is 45-46 parts by weight, and the flow rate of the third heat medium water is 22-24 parts by weight.

5. The method of claim 4, wherein, With the first heat transfer water flow rate as 100 parts by weight, under initial operating conditions, the flow rate of the first stream of first heat transfer water in step (1-1a) is 10-12 parts by weight, the flow rate of the second stream of first heat transfer water in step (1-1b) is 50-52 parts by weight, the flow rate of the third stream of first heat transfer water in step (1-1c) is 30-32 parts by weight, and the flow rate of the fourth stream of first heat transfer water in step (1-1d) is 3-5 parts by weight. In step 1-1e), the flow rate of the fifth stream of the first heat medium water is 2-3 parts by weight; under the final operating conditions, the flow rate of the second stream of the first heat medium water in step (2-1b) is 77-80 parts by weight, the flow rate of the third stream of the first heat medium water in step (2-1c) is 14-16 parts by weight, the flow rate of the fourth stream of the first heat medium water in step (2-1d) is 3-4 parts by weight, and the flow rate of the fifth stream of the first heat medium water in step (2-1e) is 2-3 parts by weight.

6. The method of claim 4, wherein, With the second heat transfer water flow rate as 100 parts by weight, under initial operating conditions, the flow rate of the first stream of second heat transfer water in step (1-2a) is 70-73 parts by weight, the flow rate of the second stream of second heat transfer water in step (1-2b) is 26-28 parts by weight, and the flow rate of the third stream of second heat transfer water in step (1-2c) is 0.1-1 parts by weight; under final operating conditions, the flow rate of the first stream of second heat transfer water in step (2-2a) is 74-76 parts by weight, the flow rate of the second stream of second heat transfer water in step (2-2b) is 23-25 ​​parts by weight, and the flow rate of the third stream of second heat transfer water in step (2-2c) is 0.1-1 parts by weight.

7. The method according to any one of claims 1 to 6, characterized in that, Under initial operating conditions, the combined temperature of the heat transfer medium water after heat exchange and heating in steps (1-1a) to (1-1d) is 127-133℃; under final operating conditions, the combined temperature of the heat transfer medium water after heat exchange and heating in steps (2-1a) to (2-1d) is 125-130℃.

8. The method according to any one of claims 1 to 6, characterized in that, Under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-1f) to (1-1g) is 70-75℃. Under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-1f) to (2-1g) is 73-77℃.

9. The method according to any one of claims 1 to 6, characterized in that, Under initial operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (1-1e) is 83-87℃; under final operating conditions, the temperature of the heat transfer water after heat exchange and heating in step (2-1e) is 83-87℃.

10. The method according to any one of claims 1-6, characterized in that, Under initial operating conditions, the combined temperature of the heat transfer medium water after heat exchange and heating in steps (1-2a) to (1-2c) is 114-117℃; under final operating conditions, the combined temperature of the heat transfer medium water after heat exchange and heating in steps (2-2a) to (2-2c) is 109-113℃.

11. The method according to any one of claims 1 to 6, characterized in that, Under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2d) to (1-2e) is 68-72℃; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2d) to (2-2e) is 84-88℃.

12. The method of any of claims 1-6, wherein, Under initial operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (1-2f) to (1-2i) is 78-82℃; under final operating conditions, the combined temperature of the heat transfer water after heat exchange and cooling in steps (2-2f) to (2-2i) is 78-82℃.

13. The method of any of claims 1-6, wherein, Under initial operating conditions, after steps (1-1), (1-2) and (1-3), the temperature of the hot water returning to the circulating return water header (4) and merging is 69-73℃; under final operating conditions, after steps (2-1), (2-2) and (2-3), the temperature of the hot water returning to the circulating return water header (4) and merging is 73-77℃.

14. The method of any of claims 1-6, wherein, Under initial operating conditions, the circulating water cooling and safety heat exchanger (A3) maintains the temperature of the heat transfer medium water in the circulating return water header (4) at 68-72°C, and then returns it to the heat transfer medium water tank (5); under final operating conditions, the circulating water cooling and safety heat exchanger (A3) maintains the temperature of the heat transfer medium water in the circulating return water header (4) at 68-72°C, and then returns it to the heat transfer medium water tank (5).

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