Energy-saving process system and method for separating refined phenol from tar crude phenol

Abstract

The invention relates to an energy-saving process system and method for separating refined phenol from tar crude phenol, and belongs to the field of tar crude phenol refining. The system comprises a separation process system and an energy-saving thermal circulation loop system, the separation process system comprises a first tower, a second tower, a third tower, a fourth tower, a fifth tower and matched cold exchange equipment, and the energy-saving thermal circulation loop system comprises a compressor, a throttle valve, a buffer tank and matched cold exchange equipment. The method comprises the following steps: removing water and light components, removing slag phenol, refining phenol, o-cresol, m-cresol and p-cresol, separating areas in the tower to improve the product purity, and converting low-grade waste heat into a high-grade heat source by using a compressor to replace traditional heating media and refrigerants, so that the aim of saving energy is fulfilled. According to the process system and the method, the tar crude phenol is separated and refined into high-purity phenol, o-cresol and m-cresol and p-cresol products, meanwhile, the purposes of saving energy and reducing consumption are achieved, and the process system and the method have important significance.

Description

Technical Field

[0001] The present invention relates to the refining of crude tar phenol, and specifically to an energy-saving process system and method for separating refined phenol from crude tar phenol. Background Art

[0002] Crude phenol is a by-product in industrial processes and is commonly found in tar. Crude phenol is a mixture of various phenols with very diverse and complex components. Its direct utilization efficiency is low, and directly using crude phenol will reduce the performance of downstream products and has poor stability. Therefore, it is necessary to convert crude phenol into high-value-added products through refining and purification to meet the needs of high-end fields. Among them, phenol, cresol, etc. in crude phenol are key raw materials for synthetic resins, pharmaceuticals, and pesticides, and the market demand is large, but industrial-grade phenols all require a purity of ≥99%.

[0003] The refining of crude phenol mainly uses the rectification process. Since the boiling points of various effective phenol products in crude phenol are relatively close, batch rectification requires multiple batches of repeated rectification, with extremely high energy consumption, large losses of phenols, and low yields. Continuous rectification, compared with batch rectification, although improves the yield to some extent, requires multiple towers for multiple purifications to obtain a higher concentration, and the operating reflux ratio is relatively large, with a long production process and high energy consumption.

[0004] In summary, the process flow for refining crude tar phenol is complex and energy-consuming, showing multi-dimensional requirements in terms of resources, environment, technology, and economy. The core lies in achieving the efficient separation and high-value conversion of the complex mixture of crude phenol through technological innovation. Therefore, developing an efficient and low-cost process system and method for refining crude tar phenol can enhance product competitiveness, reduce environmental pollution, and achieve energy-saving goals. Patents CN102731264 and CN107721826 both disclose methods for continuously rectifying and separating crude tar phenol, but neither mentions energy-saving measures. And in order to obtain high-purity phenol products, Patent CN107721826 is equipped with a pre-component tower in front of each product tower, further increasing the operating energy consumption and the number of equipment. Patents CN214088348U and CN114436782A disclose devices and methods for multi-effect rectification to recover phenol from tar, but do not mention energy-saving measures for the production of other phenol products. Summary of the Invention

[0005] The purpose of the present invention is to provide an energy-saving process system and method for separating refined phenol from crude tar phenol, which can efficiently convert the heat of the top condenser in the recovery system into the heating source of the bottom reboiler to achieve the purpose of energy saving. By separating the regions in the dividing tower, the removal of the pre-fraction is realized, further achieving the purpose of energy saving and improving the purity of the product.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: An energy-saving process system for separating refined phenol from crude tar phenol, including Tower 1, the condenser of Tower 1, the reboiler of Tower 1, Tower 2, the condenser of Tower 2, the reboiler of Tower 2, Tower 3, the condenser of Tower 3, the reboiler of Tower 3, Tower 4, the condenser of Tower 4, the reboiler of Tower 4, Tower 5, the condenser of Tower 5, the reboiler of Tower 5, a compressor, a throttle valve, and a buffer tank.

[0007] There are material pipelines connected between Tower 1, the hot side of the condenser of Tower 1, the cold side of the reboiler of Tower 1, Tower 2, the hot side of the condenser of Tower 2, the cold side of the reboiler of Tower 2, Tower 3, the hot side of the condenser of Tower 3, the cold side of the reboiler of Tower 3, Tower 4, the hot side of the condenser of Tower 4, the cold side of the reboiler of Tower 4, Tower 5, the hot side of the condenser of Tower 5, and the cold side of the reboiler of Tower 5, forming a separation process system.

[0008] There are working medium pipelines connected between the cold side of the condenser of Tower 2, the cold side of the condenser of Tower 3, the cold side of the condenser of Tower 4, the cold side of the condenser of Tower 5, the compressor, the hot side of the reboiler of Tower 1, the hot side of the reboiler of Tower 3, the hot side of the reboiler of Tower 4, the hot side of the reboiler of Tower 5, the throttle valve, and the buffer tank. The pipeline is filled with a heat transfer working medium, forming the main loop system of the energy-saving heat cycle.

[0009] Furthermore, the cold side of the condenser of Tower 1 is connected to the refrigerant circulating water or low-temperature water, the hot side of the reboiler of Tower 2 is connected to the heat medium steam or heat-conducting oil or electric heating, and mass transfer packing and tower internals or trays are installed inside Tower 1, Tower 2, Tower 3, Tower 4, and Tower 5.

[0010] Furthermore, a partition plate is installed in the upper-middle part of Tower 4, dividing the tower into three areas A, B, and C. The tops of areas A and B are respectively connected to their respective condensers, and the bottom of area C is connected to the reboiler.

[0011] Furthermore, a partition plate is installed in the upper-middle part of Tower 5, dividing the tower into three areas A, B, and C. The tops of areas A and B are respectively connected to their respective condensers, and the bottom of area C is connected to the reboiler.

[0012] Furthermore, there are heat exchange tubes in the buffer tank. The heat exchange tubes are connected to the heat medium or refrigerant. The buffer tank body is provided with a supplementary working medium inlet, and the bottom and top of the buffer tank are connected with working medium pipelines, forming an auxiliary loop system of the energy-saving heat cycle.

[0013] Furthermore, the heat transfer working medium filled in the pipeline of the energy-saving heat cycle loop system is water or R22 or R32 or R134 or R245 or R454 or R290 or R744 or CO2.

[0014] An energy-saving process method for separating refined phenol from crude tar phenol. The raw material crude phenol enters the middle part of Column 1. The gas at the top of Column 1 enters the hot side of the condenser of Column 1 and is cooled and liquefied by the circulating water or low-temperature water on the cold side. Part of it flows back into the top of Column 1, and part is taken out as water and light components. Part of the liquid at the bottom of Column 1 enters the cold side of the reboiler of Column 1 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of Column 1. Part of the mixed phenol after removing water and light components is taken out and enters the middle part of Column 2. Part of the liquid at the bottom of Column 2 enters the cold side of the reboiler of Column 2 and is vaporized by the steam or heat-conducting oil or electric heating on the hot side and then returns to the bottom of Column 2. Part of the slag phenol is taken out. The gas at the top of Column 2 enters the hot side of the condenser of Column 2 and is cooled and liquefied by the heat transfer working medium liquid on the cold side. Part of it flows back into the top of Column 2, and part of the mixed phenol after removing slag is taken out and enters the middle part of Column 3. The gas at the top of Column 3 enters the hot side of the condenser of Column 3 and is cooled and liquefied by the heat transfer working medium liquid on the cold side. Part of it flows back into the top of Column 3, and part of the phenol product is taken out. Part of the liquid at the bottom of Column 3 enters the cold side of the reboiler of Column 3 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of Column 3. Part of the mixed phenol is taken out and enters the middle part of Column 4. The gas at the top of Column 4 enters the hot side of the condenser of Column 4 and is cooled and liquefied by the heat transfer working medium liquid on the cold side. Part of it flows back into the top of Column 4, and part of the o-cresol product is taken out. Part of the liquid at the bottom of Column 4 enters the cold side of the reboiler of Column 4 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of Column 4. Part of the mixed phenol is taken out and enters the middle part of Column 5. The gas at the top of Column 5 enters the hot side of the condenser of Column 5 and is cooled and liquefied by the heat transfer working medium liquid on the cold side. Part of it flows back into the top of Column 5, and part of the m,p-cresol product is taken out. Part of the liquid at the bottom of Column 5 enters the cold side of the reboiler of Column 5 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of Column 5. Part of the mixed miscellaneous phenol product is taken out.

[0015] After passing through the buffer tank, the working medium liquid enters the cold sides of the condensers of Column 2, Column 3, Column 4, and Column 5 respectively to cool the gas at the top of Column 2, Column 3, Column 4, and Column 5 on the hot side. After the working medium liquid is heated and vaporized by itself, it forms heat transfer working medium steam. The heat transfer working medium steam enters the compressor to be pressurized into high-pressure working medium steam, and then enters the hot sides of the reboilers of Column 1, Column 3, Column 4, and Column 5 respectively to heat the liquid at the bottom of Column 1, Column 3, Column 4, and Column 5 on the cold side, generating working medium liquid. The working medium liquid passes through the throttle valve and then enters the buffer tank to form the main loop of the energy-saving heat cycle. The working medium liquid in the buffer tank is pressurized by a pump and enters the top of the buffer tank for direct heat exchange with the working medium steam to form the secondary loop of the energy-saving heat cycle.

[0016] Furthermore, the operating pressures of Column 1, Column 2, Column 3, Column 4, and Column 5 are all under negative pressure operation. The operating pressure of Column 3 is greater than that of Column 4, and the operating pressure of Column 4 is greater than that of Column 5.

[0017] Furthermore, part of the condensate of the condenser at the top of the A area of Column 4 is taken out as mixed phenol and enters the middle part of Column 3.

[0018] Furthermore, a part of the condensate of the top condenser in the Tower Five A area is extracted as mixed phenol and enters the bottom of the Tower Four B area.

[0019] The energy-saving process system and method for separating refined phenol from crude tar phenol according to the present invention have the following beneficial effects: (1) The energy-saving process system and method for separating refined phenol from crude tar phenol disclosed in the present invention adopt a fully continuous method for crude phenol separation and refining, obtaining various high-quality phenolic products. The whole process has low energy consumption, simple operation, is suitable for large-scale continuous production, and has good social and economic benefits.

[0020] (2) The energy-saving process system and method for separating refined phenol from crude tar phenol disclosed in the present invention only requires providing heat once on the hot side of the reboiler of Tower Two and cold once on the cold side of the condenser of Tower One in the whole system, and the comprehensive energy consumption is significantly reduced. The heat on the hot sides of the condensers of Tower Two, Tower Three, Tower Four, and Tower Five is recovered by using a heat transfer medium, and after the heat grade is increased by a compressor, it is used to heat the bottom materials in the towers on the cold sides of the reboilers of Tower One, Tower Three, Tower Four, and Tower Five. This not only saves the heat originally required on the hot sides of the reboilers of Tower One, Tower Three, Tower Four, and Tower Five, but also saves the cold originally required on the cold sides of the condensers of Tower Two, Tower Three, Tower Four, and Tower Five, achieving a significant energy-saving effect.

[0021] (3) The energy-saving process system and method for separating refined phenol from crude tar phenol disclosed in the present invention control the operating conditions of each tower, enabling multiple devices in the whole system to share a set of energy-saving heat circulation loop systems, and greatly reducing the equipment investment.

[0022] (4) The energy-saving process system and method for separating refined phenol from crude tar phenol disclosed in the present invention installs a partition plate in the middle and upper part of Tower Four to further remove the pre-fraction, reducing the number of tower equipment while improving the product quality. This not only further realizes the energy-saving effect but also reduces the investment cost of the device system.

[0023] (5) The energy-saving process system and method for separating refined phenol from crude tar phenol disclosed in the present invention installs a partition plate in the middle and upper part of Tower Five to further remove the pre-fraction, reducing the number of tower equipment while improving the product quality. This not only further realizes the energy-saving effect but also reduces the investment cost of the device system. Description of the Drawings

[0024] For a further understanding of the present invention, the following drawings are provided for illustration: Figure 1 It is a schematic process flow diagram of Embodiment 1 of the present invention.

[0025] Figure 2 It is a schematic process flow diagram of Embodiment 2 of the present invention.

[0026] Description of reference numerals: 1 is Tower 1; 2 is Tower 2; 3 is Tower 3; 4 is Tower 4; 5 is Tower 5; 6 is the condenser of Tower 1; 7 is the condenser of Tower 2; 8 is the condenser of Tower 3; 9 is Condenser I of Tower 4; 10 is Condenser II of Tower 4; 11 is Condenser I of Tower 5; 12 is Condenser II of Tower 5; 13 is the reboiler of Tower 1; 14 is the reboiler of Tower 2; 15 is the reboiler of Tower 3; 16 is the reboiler of Tower 4; 17 is the reboiler of Tower 5; 18 is a compressor; 19 is a throttle valve; 20 is a buffer tank; 21 is mass transfer packing and internals or trays in the tower; 22 is a partition plate; 23 is a heat exchange tube; 24 is a preheater; 25 is a regulating valve; 26 is a pump; A is Area A of the internal partition in the tower; B is Area B of the internal partition in the tower; C is Area C of the internal partition in the tower; HWS is the incoming heat medium; HWR is the returning heat medium; RWS is the incoming refrigerant; RWR is the returning refrigerant. Detailed implementation manners

[0027] The present invention will be further described in detail below with reference to the drawings and specific implementation manners. Embodiment 1

[0028] Refer to Figure 1 , this embodiment provides an energy-saving process system and method for separating refined phenol from crude tar phenol. The process system includes Tower 1, Tower 2, Tower 3, Tower 4, Tower 5, the condenser of Tower 1, the condenser of Tower 2, the condenser of Tower 3, Condenser I of Tower 4, Condenser II of Tower 4, Condenser I of Tower 5, Condenser II of Tower 5, the reboiler of Tower 1, the reboiler of Tower 2, the reboiler of Tower 3, the reboiler of Tower 4, the reboiler of Tower 5, a compressor, a throttle valve, a buffer tank, a regulating valve, and a pump.

[0029] The Tower 1, Tower 2, Tower 3, Tower 4, and Tower 5 are all vertical towers, and mass transfer packing and internals or trays are installed inside the towers. The Tower 4 and Tower 5 are installed with partition plates, which divide the inside of the towers into three areas A, B, and C.

[0030] A material pipeline is connected between the Tower 1, the hot side of the condenser of Tower 1, the cold side of the reboiler of Tower 1, Tower 2, the hot side of the condenser of Tower 2, the cold side of the reboiler of Tower 2, Tower 3, the hot side of the condenser of Tower 3, the cold side of the reboiler of Tower 3, Tower 4, the hot side of Condenser I of Tower 4, the hot side of Condenser II of Tower 4, the cold side of the reboiler of Tower 4, Tower 5, the hot side of Condenser I of Tower 5, the hot side of Condenser II of Tower 5, and the cold side of the reboiler of Tower 5 to form a separation process system.

[0031] The cold sides of the second tower condenser 7, the third tower condenser 8, the first fourth tower condenser 9, the second fourth tower condenser 10, the first fifth tower condenser 11, and the second fifth tower condenser 12, the compressor 18, the hot side of the first tower reboiler 13, the hot side of the third tower reboiler 15, the hot side of the fourth tower reboiler 16, the hot side of the fifth tower reboiler 17, the throttle valve 19, and the buffer tank 20 are connected by a working medium pipeline filled with a heat transfer working medium to form a main loop system of an energy-saving heat cycle; the buffer tank 20, the regulating valve 25, and the pump 26 form an auxiliary loop system of the energy-saving heat cycle.

[0032] The cold side of the first tower condenser 6 is connected to a refrigerant, and the refrigerant can be selected from circulating water or low-temperature water. In this embodiment, circulating water is preferably used. The hot side of the second tower reboiler 14 is connected to a heat medium, and the heat medium can be selected from steam, heat-conducting oil, or electric heating. In this embodiment, heat-conducting oil is preferably used.

[0033] The buffer tank 20 is provided with a heat exchange tube 23, and the heat exchange tube 23 is connected to the refrigerant circulating water. The buffer tank body is provided with a supplementary working medium inlet. The heat transfer working medium can be selected from water, R22, R32, R134, R245, R454, R290, R744, or CO2. In this embodiment, water is preferably used, the corresponding working medium liquid is liquid water, and the working medium steam is water vapor.

[0034] The energy-saving process method provided in this embodiment includes the following steps: The raw material crude phenol enters the middle of column 1. The gas at the top of column 1 enters the hot side of condenser 6 of column 1 and is cooled and liquefied by the refrigerant circulating water on the cold side. Part of it flows back into the top of column 1, and part is taken out as water and light components. Part of the liquid at the bottom of column 1 enters the cold side of reboiler 13 of column 1 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of column 1. Part of it is taken out as the mixed phenol after removing water and light components and enters the middle of column 2. Part of the liquid at the bottom of column 2 enters the cold side of reboiler 14 of column 2 and is vaporized by the heat medium heat-conducting oil on the hot side and then returns to the bottom of column 2. Part of it is taken out as slag phenol. The gas at the top of column 2 enters the hot side of condenser 7 of column 2 and is cooled and liquefied by the heat transfer working medium liquid water on the cold side. Part of it flows back into the top of column 2, and part is taken out as the mixed phenol after removing slag and enters the middle of column 3. The gas at the top of column 3 enters the hot side of condenser 8 of column 3 and is cooled and liquefied by the heat transfer working medium liquid water on the cold side. Part of it flows back into the top of column 3, and part is taken out as phenol product. Part of the liquid at the bottom of column 3 enters the cold side of reboiler 15 of column 3 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of column 3. Part of it is taken out as mixed phenol and enters the middle of column 4. The gas at the top of the A area of column 4 enters the hot side of condenser I 9 of column 4 and is cooled and liquefied by the heat transfer working medium liquid water on the cold side. Part of it flows back into the top of the A area of column 4, and part is taken out as mixed phenol and enters the middle of column 3. The gas at the top of the B area of column 4 enters the hot side of condenser II 10 of column 4 and is cooled and liquefied by the heat transfer working medium liquid water on the cold side. Part of it flows back into the top of the B area of column 4, and part is taken out as o-cresol product. Part of the liquid at the bottom of column 4 enters the cold side of reboiler 16 of column 4 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of column 4. Part of it is taken out as mixed phenol and enters the middle of column 5. The gas at the top of the A area of column 5 enters the hot side of condenser I 11 of column 5 and is cooled and liquefied by the heat transfer working medium liquid water on the cold side. Part of it flows back into the top of the A area of column 5, and part is taken out as mixed phenol and enters the bottom of the B area of column 4. The gas at the top of the B area of column 5 enters the hot side of condenser II 12 of column 5 and is cooled and liquefied by the heat transfer working medium liquid water on the cold side. Part of it flows back into the top of the B area of column 5, and part is taken out as m / p-cresol product. Part of the liquid at the bottom of column 5 enters the cold side of reboiler 17 of column 5 and is vaporized by the heat transfer working medium steam on the hot side and then returns to the bottom of column 5. Part of it is taken out as mixed miscellaneous phenol product.

[0035] The working medium liquid water after the buffer tank 20 enters the cold sides of the second tower condenser 7, the third tower condenser 8, the first fourth tower condenser 9, the second fourth tower condenser 10, the first fifth tower condenser 11, and the second fifth tower condenser 12 respectively to cool the top gases of the second tower 2, the third tower 3, the fourth tower 4, and the fifth tower 5 on the hot side. After that, the working medium liquid water is heated and vaporized by itself to form a heat transfer working medium water vapor. The heat transfer working medium water vapor enters the compressor 18 to be pressurized into a high-pressure working medium water vapor, and then enters the hot sides of the first tower reboiler 13, the third tower reboiler 15, the fourth tower reboiler 16, and the fifth tower reboiler 17 respectively to heat the bottom liquids of the first tower 1, the third tower 3, the fourth tower 4, and the fifth tower 5 on the cold side. After that, working medium liquid water is generated. The working medium liquid water passes through the throttle valve 19 and then enters the buffer tank 20 for further cooling to form the main loop of the energy-saving heat cycle; the working medium liquid in the buffer tank 20 is pressurized by the pump 26 and then enters the top of the buffer tank through the regulating valve 25 for direct heat exchange with the working medium steam to form the secondary loop of the energy-saving heat cycle.

[0036] In this embodiment, the processing capacity of the crude phenol raw material is 30,000 tons / year, and the mass contents of the components of the crude phenol raw material are: water 0.473%, light miscellaneous phenols 0.473%, phenol 48.424%, o-cresol 10.315%, p-cresol 11.262%, m-cresol 16.4%, o-ethylphenol 0.653%, 2,4-xylenol 1.968%, and slag phenol 10.031%. After being processed by the technology and device of the present invention, phenol with a mass concentration of 99.5%, o-cresol with a mass concentration of 99.5%, and m-p-cresol with a mass concentration of 97.5% are stably produced.

[0037] In this embodiment, the operating pressure of the first tower 1 is 17 KPaA, the operating temperature at the top of the first tower 1 is 57.4 °C, and the operating temperature at the bottom of the first tower 1 is 135.7 °C. The operating pressure of the second tower 2 is 11 KPaA, the operating temperature at the top of the second tower 2 is 121.7 °C, and the operating temperature at the bottom of the second tower 2 is 160.1 °C. The operating pressure of the third tower 3 is 12.5 KPaA, the operating temperature at the top of the third tower 3 is 119.2 °C, and the operating temperature at the bottom of the third tower 3 is 135.5 °C. The operating pressure of the fourth tower 4 is 10.5 KPaA, the operating temperature in area A at the top of the fourth tower 4 is 118.1 °C, the operating temperature in area B at the top of the fourth tower 4 is 121.0 °C, and the operating temperature at the bottom of the fourth tower 4 is 135.1 °C. The operating pressure of the fifth tower 5 is 8 KPaA, the operating temperature in area A at the top of the fifth tower 5 is 124.6 °C, the operating temperature in area B at the top of the fifth tower 5 is 125.8 °C, and the operating temperature at the bottom of the fifth tower 5 is 135.7 °C.

[0038] In this embodiment, the heat transfer working medium cycle makes full use of the waste heat. The heat transfer working medium, liquid water, absorbs the heat from the hot sides of the second column condenser 7, the third column condenser 8, the first fourth-column condenser 9, the second fourth-column condenser 10, the first fifth-column condenser 11, and the second fifth-column condenser 12. The liquid water of the working medium vaporizes to form working medium steam. After the working medium steam is pressurized to 600 KPaA steam by the compressor 18, it is used to heat the materials on the cold sides of the first column reboiler 13, the third column reboiler 15, the fourth column reboiler 16, and the fifth column reboiler 17. This not only saves the heat medium required for the hot sides of the first column reboiler 13, the third column reboiler 15, the fourth column reboiler 16, and the fifth column reboiler 17, but also saves the refrigerant required for the cold sides of the second column condenser 7, the third column condenser 8, the first fourth-column condenser 9, the second fourth-column condenser 10, the first fifth-column condenser 11, and the second fifth-column condenser 12. Only the hot side of the second column reboiler 14 needs the heat medium in the entire process system, and the cold side of the first column condenser 6 and the heat exchange tubes 23 in the buffer tank 20 need the refrigerant. Compared with the traditional process system, 409.8 tons of heat medium heat transfer oil can be saved per ton of crude phenol raw material produced, with a savings of 83.9% of the heat medium heat transfer oil, 444.3 tons of refrigerant circulating water can be saved, with a savings of 82.3% of the refrigerant circulating water, and the power consumption of the compressor 18 required per ton of crude phenol raw material produced is 73.4 KWh, resulting in a significant reduction in the comprehensive energy consumption.

[0039] In this embodiment, the fourth column 4 and the fifth column 5 are equipped with partition plates 22, which divide the inside of the columns into three areas: A, B, and C. Area A realizes the further removal of light mixed phenol, saving two columns compared to the traditional process, reducing the equipment investment in the system, and also reducing the energy consumption. Embodiment 2

[0040] Refer to Figure 2 This embodiment provides an energy-saving process system and method for separating refined phenol from crude tar phenol. The process system includes the first column 1, the second column 2, the third column 3, the fourth column 4, the fifth column 5, the first column condenser 6, the second column condenser 7, the third column condenser 8, the first fourth-column condenser 9, the second fourth-column condenser 10, the first fifth-column condenser 11, the second fifth-column condenser 12, the first column reboiler 13, the second column reboiler 14, the third column reboiler 15, the fourth column reboiler 16, the fifth column reboiler 17, the compressor 18, the throttle valve 19, the buffer tank 20, the preheater 24, the regulating valve 25, and the pump 26.

[0041] Same as Embodiment 1, the first column 1, the second column 2, the third column 3, the fourth column 4, and the fifth column 5 are all vertical tower bodies, and mass transfer packings and internals or trays 21 are installed inside the columns. The fourth column 4 and the fifth column 5 are equipped with partition plates 22, which divide the inside of the columns into three areas: A, B, and C.

[0042] There are material pipelines connected between the cold side of the preheater 24, Tower 1, the hot side of the condenser 6 of Tower 1, the cold side of the reboiler 13 of Tower 1, Tower 2, the hot side of the condenser 7 of Tower 2, the cold side of the reboiler 14 of Tower 2, Tower 3, the hot side of the condenser 8 of Tower 3, the cold side of the reboiler 15 of Tower 3, Tower 4, the hot side of the condenser I 9 of Tower 4, the hot side of the condenser II 10 of Tower 4, the cold side of the reboiler 16 of Tower 4, Tower 5, the hot side of the condenser I 11 of Tower 5, the hot side of the condenser II 12 of Tower 5, and the cold side of the reboiler 17 of Tower 5 to form a separation process system.

[0043] There are working medium pipelines connected between the cold side of the condenser 7 of Tower 2, the cold side of the condenser 8 of Tower 3, the cold side of the condenser I 9 of Tower 4, the cold side of the condenser II 10 of Tower 4, the cold side of the condenser I 11 of Tower 5, the cold side of the condenser II 12 of Tower 5, the buffer tank 20, the compressor 18, the hot side of the reboiler 13 of Tower 1, the hot side of the reboiler 15 of Tower 3, the hot side of the reboiler 16 of Tower 4, the hot side of the reboiler 17 of Tower 5, the hot side of the preheater 24, and the throttle valve 19. The pipeline is filled with a heat transfer working medium to form an energy-saving heat circulation main loop system; the buffer tank 20, the regulating valve 25, and the pump 26 form an energy-saving heat circulation sub-loop system.

[0044] The cold side of the condenser 6 of Tower 1 is connected to a refrigerant, and the refrigerant can be circulating water or low-temperature water. In this embodiment, circulating water is preferably selected. The hot side of the reboiler 14 of Tower 2 is connected to a heat medium, and the heat medium can be steam, heat-conducting oil, or electric heating. In this embodiment, steam is preferably selected.

[0045] There is a heat exchange tube 23 in the buffer tank 20. The heat exchange tube 23 is connected to the heat medium steam, and a supplementary working medium inlet is provided on the buffer tank body. The heat transfer working medium can be water, R22, R32, R134, R245, R454, R290, R744, or CO2. In this embodiment, water is preferably selected. The corresponding working medium liquid is liquid water, and the working medium steam is water vapor.

[0046] The energy-saving process method provided in this embodiment includes the following steps: After the raw material crude phenol exchanges heat with the working fluid liquid on the cold side and the hot side of the preheater 24, it enters the middle of column 1. The gas at the top of column 1 enters the hot side of the column 1 condenser 6 and is cooled and liquefied by the refrigerant circulating water on the cold side. Part of it flows back into the top of column 1, and part is taken out as water and light components. Part of the liquid at the bottom of column 1 enters the cold side of the column 1 reboiler 13 and is heated and vaporized by the heat transfer working fluid steam on the hot side and then returns to the bottom of column 1. Part of it is taken out as the mixed phenol after removing water and light components and enters the middle of column 2. Part of the liquid at the bottom of column 2 enters the cold side of the column 2 reboiler 14 and is heated and vaporized by the heat medium steam on the hot side and then returns to the bottom of column 2. Part of it is taken out as slag phenol. The gas at the top of column 2 enters the hot side of the column 2 condenser 7 and is cooled and liquefied by the heat transfer working fluid liquid water on the cold side. Part of it flows back into the top of column 2, and part is taken out as the mixed phenol after removing slag and enters the middle of column 3. The gas at the top of column 3 enters the hot side of the column 3 condenser 8 and is cooled and liquefied by the heat transfer working fluid liquid water on the cold side. Part of it flows back into the top of column 3, and part is taken out as phenol product. Part of the liquid at the bottom of column 3 enters the cold side of the column 3 reboiler 15 and is heated and vaporized by the heat transfer working fluid steam on the hot side and then returns to the bottom of column 3. Part of it is taken out as mixed phenol and enters the middle of column 4. The gas at the top of the A area of column 4 enters the hot side of the column 4 condenser I 9 and is cooled and liquefied by the heat transfer working fluid liquid water on the cold side. Part of it flows back into the top of the A area of column 4, and part is taken out as mixed phenol and enters the middle of column 3. The gas at the top of the B area of column 4 enters the hot side of the column 4 condenser II 10 and is cooled and liquefied by the heat transfer working fluid liquid water on the cold side. Part of it flows back into the top of the B area of column 4, and part is taken out as o-cresol product. Part of the liquid at the bottom of column 4 enters the cold side of the column 4 reboiler 16 and is heated and vaporized by the heat transfer working fluid steam on the hot side and then returns to the bottom of column 4. Part of it is taken out as mixed phenol and enters the middle of column 5. The gas at the top of the A area of column 5 enters the hot side of the column 5 condenser I 11 and is cooled and liquefied by the heat transfer working fluid liquid water on the cold side. Part of it flows back into the top of the A area of column 5, and part is taken out as mixed phenol and enters the bottom of the B area of column 4. The gas at the top of the B area of column 5 enters the hot side of the column 5 condenser II 12 and is cooled and liquefied by the heat transfer working fluid liquid water on the cold side. Part of it flows back into the top of the B area of column 5, and part is taken out as m,p-cresol product. Part of the liquid at the bottom of column 5 enters the cold side of the column 5 reboiler 17 and is heated and vaporized by the heat transfer working fluid steam on the hot side and then returns to the bottom of column 5. Part of it is taken out as mixed miscellaneous phenol product.

[0047] After the heat transfer working medium water vapor passes through the buffer tank 20 and is pressurized by the compressor 18 to become high-pressure working medium water vapor, it enters the hot sides of the column-1 reboiler 13, column-3 reboiler 15, column-4 reboiler 16, and column-5 reboiler 17 respectively to heat the column-1 bottom liquid, column-3 bottom liquid, column-4 bottom liquid, and column-5 bottom liquid on the cold sides. The working medium water vapor condenses into working medium liquid water by itself; the working medium liquid water enters the hot side of the preheater 24 to heat the crude phenol raw material on the cold side. After its own temperature drops, it passes through the throttle valve 19 and enters the cold sides of the column-2 condenser 7, column-3 condenser 8, column-4 condenser I 9, column-4 condenser II 10, column-5 condenser I 11, and column-5 condenser II 12 respectively to cool the column-2 top gas, column-3 top gas, column-4 top gas, and column-5 top gas on the hot sides. The working medium liquid water is heated and vaporized by itself to form heat transfer working medium water vapor. The working medium water vapor enters the buffer tank 20, is further heated, and then goes to the compressor 18 to form the main loop of the energy-saving heat cycle; the working medium liquid in the buffer tank 20 is pressurized by the pump 26, and after being jointly controlled by the regulating valve 25 with the pipeline after the throttle valve 19, it enters the top of the buffer tank 20 to directly exchange heat with the working medium steam, forming the secondary loop of the energy-saving heat cycle.

[0048] In this embodiment, the processing capacity of the crude phenol raw material is 10,000 tons / year. The mass contents of the components of the crude phenol raw material are as follows: water 3.31%, light miscellaneous phenols 0.23%, phenol 35.47%, o-cresol 12.5%, p-cresol 12.53%, m-cresol 23.09%, o-ethylphenol 0.69%, 2,4-xylenol 5.47%, and residual phenol 6.71%. After being processed by the technology and device of the present invention, phenol with a mass concentration of 99.5%, o-cresol with a mass concentration of 98.5%, and m / p-cresol with a mass concentration of 98% are stably produced.

[0049] In this embodiment, the operating pressure of column-1 is 18 KPaA, the operating temperature at the top of column-1 is 57.8 °C, and the operating temperature at the bottom of column-1 is 139.6 °C. The operating pressure of column-2 is 11 KPaA, the operating temperature at the top of column-2 is 124.5 °C, and the operating temperature at the bottom of column-2 is 155.5 °C. The operating pressure of column-3 is 14.5 KPaA, the operating temperature at the top of column-3 is 122.9 °C, and the operating temperature at the bottom of column-3 is 139.8 °C. The operating pressure of column-4 is 12.5 KPaA, the operating temperature in area A at the top of column-4 is 122.2 °C, the operating temperature in area B at the top of column-4 is 125.1 °C, and the operating temperature at the bottom of column-4 is 139.5 °C. The operating pressure of column-5 is 10 KPaA, the operating temperature in area A at the top of column-5 is 122.8 °C, the operating temperature in area B at the top of column-5 is 131.2 °C, and the operating temperature at the bottom of column-5 is 140.2 °C.

[0050] In this embodiment, the heat transfer working medium circulation makes full use of the waste heat. The heat transfer working medium, liquid water, absorbs the heat from the hot sides of the second tower condenser 7, the third tower condenser 8, the first fourth tower condenser 9, the second fourth tower condenser 10, the first fifth tower condenser 11, and the second fifth tower condenser 12. The liquid water of the working medium itself is vaporized to form working medium steam. After passing through the buffer tank 20, the working medium steam is pressurized to 650 KPaA steam by the compressor 18 and then used to heat the materials on the cold sides of the first tower reboiler 13, the third tower reboiler 15, the fourth tower reboiler 16, and the fifth tower reboiler 17. This not only saves the heat medium required for the hot sides of the first tower reboiler 13, the third tower reboiler 15, the fourth tower reboiler 16, and the fifth tower reboiler 17, but also saves the refrigerant required for the cold sides of the second tower condenser 7, the third tower condenser 8, the first fourth tower condenser 9, the second fourth tower condenser 10, the first fifth tower condenser 11, and the second fifth tower condenser 12. Only the hot side of the second tower reboiler 14 and the heat exchange tubes 23 in the buffer tank 20 need heat medium in the entire process system, and the cold side of the first tower condenser 6 needs refrigerant. Compared with the traditional process system, 4.65 tons of heat medium steam can be saved per ton of crude phenol raw material production, with a 79.1% savings in heat medium steam, 426.2 tons of refrigerant circulating water can be saved, with an 81.5% savings in refrigerant circulating water, and the power consumption of the compressor 18 required for each ton of crude phenol raw material production is 51.3 KWh, resulting in a significant reduction in the comprehensive energy consumption.

[0051] Similar to Embodiment 1, in this embodiment, partition plates 22 are installed in the fourth tower 4 and the fifth tower 5, dividing the towers into three areas: A, B, and C. Area A realizes the further removal of light mixed phenol, saving two towers compared to the traditional process, reducing the equipment investment in the system, and also reducing the energy consumption.

[0052] The preferred embodiments of the present invention have been described in detail above, but the above content is only the preferred embodiments of the present invention and should not be considered as limiting the scope of implementation of the present invention. Any equivalent changes and improvements made within the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. An energy-saving process system for separating refined phenol from crude phenol in tar, characterized in that: Including tower one, tower one condenser, tower one reboiler, tower two, tower two condenser, tower two reboiler, tower three, tower three condenser, tower three reboiler, tower four, tower four condenser, tower four reboiler, tower five, tower five condenser, tower five reboiler, compressor, throttle valve, buffer tank; The tower 1, the hot side of the tower 1 condenser, the cold side of the tower 1 reboiler, the tower 2, the hot side of the tower 2 condenser, the cold side of the tower 2 reboiler, the tower 3, the hot side of the tower 3 condenser, the cold side of the tower 3 reboiler, the tower 4, the hot side of the tower 4 condenser, the cold side of the tower 4 reboiler, the tower 5, the hot side of the tower 5 condenser, and the cold side of the tower 5 reboiler are connected with material pipelines to form a separation process system; The cold side of the tower two condenser, the cold side of the tower three condenser, the cold side of the tower four condenser, the cold side of the tower five condenser, the compressor, the hot side of the tower one reboiler, the hot side of the tower three reboiler, the hot side of the tower four reboiler, the hot side of the tower five reboiler, the throttle valve, and the buffer tank are connected by a working fluid pipeline, and the pipeline is filled with heat transfer working fluid to form an energy-saving heat cycle main loop system.

2. The energy-saving process system for separating refined phenol from crude phenol in tar as claimed in claim 1, characterized in that: The cold side of the condenser of tower one is connected to refrigerant circulating water or low-temperature water, the hot side of the reboiler of tower two is connected to heat medium steam or heat transfer oil or electric heating, and mass transfer packing and tower internals or tower plates are installed in towers one, two, three, four and five.

3. The energy-saving process system for separating refined phenol from crude phenol in tar as claimed in claim 1, characterized in that: A partition plate is installed in the middle and upper part of Tower 4 to divide the tower into three areas: A, B and C. The tops of areas A and B are connected to their respective condensers, and the bottom of area C is connected to the reboiler.

4. The energy-saving process system for separating refined phenol from crude phenol in tar as claimed in claim 1, characterized in that: A partition plate is installed in the middle and upper part of Tower 5 to divide the tower into three areas: A, B and C. The tops of areas A and B are connected to their respective condensers, and the bottom of area C is connected to the reboiler.

5. The energy-saving process system for separating refined phenol from crude phenol in tar as claimed in claim 1, characterized in that: The buffer tank is provided with heat exchange tubes connected to the heat medium or the refrigerant. The buffer tank body is provided with a supplementary working fluid inlet. The bottom and the top of the buffer tank are connected with working fluid pipelines to form an energy-saving heat cycle secondary loop system.

6. The energy-saving process system for separating refined phenol from crude phenol in tar as claimed in claim 1, characterized in that: The heat transfer medium filled in the pipeline of the energy-saving heat circulation loop system is water or R22 or R32 or R134 or R245 or R454 or R290 or R744 or CO2.

7. An energy-saving process for separating refined phenol from crude phenol from tar using any one of claims 1 to 6, characterized in that: The raw material crude phenol enters the middle part of tower one, and the gas at the top of tower one enters the hot side of the condenser of tower one, and is cooled and liquefied by the circulating water or low-temperature water on the cold side, and part of it is refluxed into the top of tower one, and part of water and light components are produced. Part of the liquid in the kettle of tower one enters the cold side of the reboiler of tower one, and is heated and vaporized by the heat transfer medium steam on the hot side, and then returns to the bottom of tower one. Part of the mixed phenol after water and light components are removed is produced and enters the middle part of tower two, and part of the liquid in the kettle of tower two enters the cold side of the reboiler of tower two, and is vaporized by the steam or heat transfer oil or electric heating on the hot side, and then returns to the bottom of tower two, and part of the slag phenol is produced. The gas at the top of tower two enters the hot side of the condenser of tower two, and is cooled and liquefied by the heat transfer medium liquid on the cold side, and part of it is refluxed into the top of tower two. Part of the mixed phenol after slag removal is produced and enters the middle part of tower three, and the gas at the top of tower three enters the hot side of the condenser of tower three, and is cooled and liquefied by the heat transfer medium liquid on the cold side, and part of it is refluxed into tower At the top of the third tower, part of the phenol product is produced, part of the liquid in the kettle of the third tower enters the cold side of the reboiler of the third tower, is heated and vaporized by the heat transfer medium steam on the hot side, and then returns to the bottom of the third tower, part of the mixed phenol is produced and enters the middle part of the fourth tower, the gas at the top of the fourth tower enters the hot side of the condenser of the fourth tower, is cooled and liquefied by the heat transfer medium liquid on the cold side, and part of it is refluxed into the top of the fourth tower, part of the o-cresol product is produced, part of the liquid in the kettle of the fourth tower enters the cold side of the reboiler of the fourth tower, is heated and vaporized by the heat transfer medium steam on the hot side, and then returns to the bottom of the fourth tower, part of the mixed phenol is produced and enters the middle part of the fifth tower, the gas at the top of the fifth tower enters the hot side of the condenser of the fifth tower, is cooled and liquefied by the heat transfer medium liquid on the cold side, and then part of it is refluxed into the top of the fifth tower, part of the m-cresol product is produced, part of the liquid in the kettle of the fifth tower enters the cold side of the reboiler of the fifth tower, is heated and vaporized by the heat transfer medium steam on the hot side, and then returns to the bottom of the fifth tower, and part of the mixed phenol product is produced; After passing through the buffer tank, the working fluid liquid enters the cold side of the tower two condenser, the cold side of the tower three condenser, the cold side of the tower four condenser, and the cold side of the tower five condenser respectively to cool the hot side of the tower two top gas, the tower three top gas, the tower four top gas, and the tower five top gas. The working fluid liquid itself is heated and vaporized to form heat transfer working fluid steam. After the heat transfer working fluid steam enters the compressor to be pressurized into high-pressure working fluid steam, it enters the hot side of the tower one reboiler, the hot side of the tower three reboiler, the hot side of the tower four reboiler, and the hot side of the tower five reboiler respectively to heat the cold side of the tower one kettle liquid, the tower three kettle liquid, the tower four kettle liquid, and the tower five kettle liquid to produce working fluid liquid. After passing through the throttle valve, the working fluid liquid enters the buffer tank to form an energy-saving heat cycle main loop. The working fluid liquid in the buffer tank is pressurized by a pump and enters the top of the buffer tank to directly exchange heat with the working fluid steam to form an energy-saving heat cycle secondary loop.

8. The energy-saving process for separating refined phenol from crude phenol in tar as claimed in claim 7, characterized in that: The operating pressures of Tower 1, Tower 2, Tower 3, Tower 4 and Tower 5 are all negative pressure operations, the operating pressure of Tower 3 is greater than the operating pressure of Tower 4, and the operating pressure of Tower 4 is greater than the operating pressure of Tower 5.

9. The energy-saving process for separating refined phenol from crude phenol in tar according to claim 7, characterized in that: The condensate from the top condenser in the A area of ​​tower 4 is partially extracted with mixed phenol and enters the middle part of tower 3.

10. An energy-saving process for separating refined phenol from crude phenol in tar as claimed in claim 7, characterized in that: The condensate from the top condenser in the A area of ​​Tower 5 is partially extracted with mixed phenol and enters the bottom of the B area of ​​Tower 4.

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