Raw gas waste heat recovery device and method

Abstract

The invention belongs to the field of steel and coal chemical industry, and relates to a raw gas waste heat recovery device and method.The recovery device comprises a quenching oil tower, a water scrubber, a clarifying tank and a gas-liquid mixer; and the quenching oil tower and the water washing tower are provided with matched heat exchangers and material conveying pumps. According to the raw coke oven gas waste heat recovery method, low-temperature waste heat in the raw coke oven gas can be recovered, the waste heat recovery efficiency of the raw coke oven gas is remarkably improved, light and heavy oil products in the raw coke oven gas are recovered in a quenching mode, the oil product recovery rate is larger than or equal to 80%, the water content of the recovered oil products is smaller than or equal to 1%, and it is avoided that the oil products are coked in a tower to pollute and block the tower; and the method has important significance for realizing long-term stable operation, energy conservation and consumption reduction of the raw gas purification system.

Description

Technical Field

[0001] The present invention belongs to the fields of iron and steel and coal chemical industry, and particularly relates to a waste gas heat recovery device and method for raw coke oven gas. Background Art

[0002] Energy conservation and carbon reduction are of great significance to the energy-consuming and carbon-emitting industries of iron and steel and coal chemical industry. In traditional coking industrial production, the temperature of the high-temperature raw coke oven gas generated from the coke oven is as high as 700 - 1200 °C, and the proportion of the sensible heat energy at the high temperature level exceeds 40%. Although the riser waste heat recovery technology is currently applied in the industry to recover part of the sensible heat of the coal pyrolysis gas, in order to prevent the liquefaction of tar in the raw coke oven gas, the temperature of the raw coke oven gas after recovery exceeds 500 °C. Subsequently, the raw coke oven gas enters the collecting pipe through the bridge pipe, and the raw coke oven gas is rapidly cooled by spraying circulating ammonia water. The raw coke oven gas is directly quenched in the bridge pipe and the collecting pipe by the circulating ammonia water with a gauge pressure of 0.15 - 0.2 MPa and a mass concentration of 3 - 5% in a spraying form. The raw coke oven gas is directly cooled from 500 - 850 °C to 80 - 90 °C. This process not only fails to fully recover a large amount of latent sensible heat of the raw coke oven gas, but also dissolves biochemical poisons such as tar, phenols, and polycyclic aromatic compounds in the gas into the ammonia water, greatly increasing the difficulty of separating and recovering oil products and the treatment difficulty and cost of the remaining ammonia water.

[0003] Under the above background, there is an urgent need to develop a method with higher waste heat recovery efficiency to realize the recovery of the waste heat of the raw coke oven gas. Summary of the Invention

[0004] To solve the problems of low waste heat recovery rate of the existing raw coke oven gas and the large difficulty in subsequent wastewater treatment caused by the entry of organic substances such as tar and phenols into the remaining ammonia water, the present invention develops a waste heat recovery method and device for raw coke oven gas, which can realize the recovery of the waste heat of the raw coke oven gas and improve the recovery rate of oil products in the raw coke oven gas.

[0005] The technical solution of the present invention is as follows:

[0006] The first aspect of the present invention provides a waste gas heat recovery device, comprising: a quench oil tower, a water wash tower, a clarifying tank and a gas-liquid mixer; the quench oil tower and the water wash tower are both equipped with supporting heat exchangers and material transfer pumps, and are divided into upper and lower sections with gas-phase connection by partition plates; the quench oil tower has a lower section feed inlet, an upper section discharge outlet, a bottom discharge outlet and a top gas-phase outlet, and the water wash tower has a lower section feed inlet, a bottom discharge outlet, a light oil 02 product discharge outlet, an upper section discharge outlet and a top discharge outlet; the top gas-phase outlet of the quench oil tower is connected to the lower section feed inlet of the water wash tower through a pipeline; the gas-liquid mixer is on the feed pipeline of the quench oil tower, and the bottom discharge pipeline of the quench oil tower is divided into two paths, one path of the pipeline is connected to the gas-liquid mixer through a transfer pump, and the other path of the pipeline is sequentially connected to the clarifying tank through the bottom transfer pump of the quench oil tower and the lower section heat exchanger of the quench oil tower, and the bottom discharge pipeline of the clarifying tank is connected to a heavy tar external discharge pump, and the middle discharge pipeline is connected to the lower section circulating spray nozzle of the quench oil tower through the lower section circulating pump of the quench oil tower; the upper section discharge pipeline of the quench oil tower is sequentially divided into two paths after passing through the upper section circulating pump of the quench oil tower and the upper section heat exchanger of the quench oil tower, one path is used as the output pipeline of the light oil 01 product, and the other path enters the upper section of the quench oil tower; the bottom discharge pipeline of the water wash tower is sequentially divided into two paths after passing through the lower section circulating pump of the water wash tower and the lower section heat exchanger of the water wash tower, one path is used as the system external discharge sewage pipeline, and the other path enters the lower section of the water wash tower, and the top discharge pipeline of the water wash tower is used as the waste gas outlet pipeline after recovering the waste heat.

[0007] Further, the upper discharge outlet of the water wash tower is divided into two paths after passing through the upper section circulating pump of the water wash tower and the upper section heat exchanger of the water wash tower, one path enters the lower section of the water wash tower, and the other path enters the upper section of the water wash tower.

[0008] Further, the internal components of the lower section of the quench oil tower are one or more of a grid, a wire mesh, a tray and a distributor; the internal components of the lower section of the water wash tower are one or more of a distributor, a tray and a packing, an overflow plate is arranged at the bottom of the water wash tower kettle, the bottom of the overflow plate is welded to the kettle, and the height of the overflow pipe is 1000-2000 mm;

[0009] Further, the internal components of the upper sections of the quench oil tower and the water wash tower are all a distributor, a tray, a packing or a combination thereof; the partition structures of the quench oil tower and the water wash tower both adopt a head or a liquid collecting tank; a plurality of openings are arranged on the partition plate, and the openings are all connected to riser pipes, the distance between the upper end outlet position of the riser pipe and the partition plate is 1000-1500 mm, and the distance between the lower end outlet position of the riser pipe and the partition plate is 200-500 mm.

[0010] Further, the upper section heat exchanger of the quench oil tower is one or two of the upper section first-stage heat exchanger of the quench oil tower and the upper section second-stage heat exchanger of the quench oil tower; the lower section heat exchanger of the quench oil tower is one or two of the lower section first-stage heat exchanger of the quench oil tower and the lower section second-stage heat exchanger of the quench oil tower.

[0011] Further, the heat exchange medium of the first-stage heat exchanger in the lower section of the quench oil tower is medium-pressure circulating water, the temperature of the medium-pressure circulating water is 220 - 235 °C, and the absolute pressure is 2.5 - 3.0 Mpa; the heat exchange medium of the second-stage heat exchanger in the lower section of the quench oil tower is low-pressure circulating water, the temperature of the low-pressure circulating water is 140 - 180 °C, and the absolute pressure is 0.4 - 1.0 Mpa; the heat exchange medium of the first-stage heat exchanger in the upper section of the quench oil tower is low-pressure circulating water, the temperature of the low-pressure circulating water is 112 - 134 °C, and the absolute pressure is 0.15 - 0.3 Mpa; the heat exchange medium of the second-stage heat exchanger in the upper section of the quench oil tower is circulating water, and the temperature of the circulating water is 30 - 50 °C.

[0012] The second aspect of the present invention provides a method for recovering waste heat from raw coke oven gas, using the waste heat recovery device for raw coke oven gas to recover the waste heat of raw coke oven gas, including:

[0013] The raw coke oven gas at 500 - 850 °C coming from the coke oven riser pipe is fully mixed with the quench circulating oil discharged from the bottom of the quench oil tower in the gas-liquid mixer, and the mixed gas-liquid material is cooled to 280 - 300 °C and sent to the lower section of the quench oil tower;

[0014] In the lower section of the quench oil tower, the mixed gas-liquid material exchanges heat with the quench oil tower lower-section circulating oil and is separated. The separated gas phase enters the upper section of the quench oil tower for heat recovery. The lower-section circulating oil entraining solids is sent out in two paths from the bottom discharge port of the tower. One path returns to the gas-liquid mixer, and the other path of the material continuously enters the heat exchanger in the lower section of the quench oil tower, exchanges heat, and then enters the clarifying tank. Heavy tar is discharged from the bottom of the clarifying tank, and the circulating oil is discharged from the side to the lower section of the quench oil tower;

[0015] In the upper section of the quench oil tower, after the raw coke oven gas exchanges heat with the quench oil tower upper-section circulating oil, the separated gas phase enters the lower part of the water washing tower. The upper-section circulating oil continuously enters the heat exchanger in the upper section of the quench oil tower, exchanges heat, and then part of it returns to the upper section of the quench oil tower, and part of it is collected as light oil 01 product;

[0016] In the lower section of the water washing tower, after the heat-exchanged raw coke oven gas exchanges heat with the water washing tower lower-section circulating liquid, it enters the upper section of the water washing tower. The heat-exchanged lower-section circulating liquid undergoes oil-water separation in the bottom of the water washing tower. The oil phase is collected as light oil 02 product, and the separated water phase continuously enters the heat exchanger in the lower section of the water washing tower, exchanges heat, and then part of it returns to the lower section of the water washing tower, and part of it is discharged from the system as sewage;

[0017] In the upper section of the water washing tower, after the heat-exchanged raw coke oven gas exchanges heat with the water washing tower upper-section circulating liquid, it is sent to the subsequent raw coke oven gas processing system through the top discharge port. The heat-exchanged lower-section circulating liquid enters the heat exchanger in the upper section of the water washing tower, exchanges heat, and then part of it returns to the upper section of the water washing tower, and part of it returns to the lower section of the water washing tower.

[0018] Further, the temperature of the circulating oil discharged from the bottom of the quenching oil tower is 260 - 280°C; the temperature of the circulating oil entering the clarifying tank is 150 - 200°C; the temperature of the upper-stage circulating oil after heat exchange in the upper stage of the quenching oil tower is 130 - 150°C; the temperature of the light oil 01 product is 85 - 105°C;

[0019] Further, the temperature of the raw coke oven gas entering the water washing tower is 105 - 110°C;

[0020] Further, the temperature of the lower-stage circulating liquid after heat exchange in the water washing tower is 65 - 75°C; the heat exchange medium of the lower-stage heat exchanger of the water washing tower is circulating cooling water, and the temperature of the circulating cooling water is 30 - 40°C; the temperature of the light oil 02 product is 65 - 75°C; the temperature of the raw coke oven gas after heat exchange in the lower stage of the water washing tower is 50 - 65°C;

[0021] Further, the temperature of the upper-stage circulating liquid after heat exchange in the water washing tower is 50 - 55°C; the heat exchange medium of the upper-stage heat exchanger of the water washing tower is low-temperature circulating water, and the temperature of the low-temperature circulating water is 15 - 30°C; the temperature of the circulating liquid after heat exchange in the upper-stage heat exchanger of the water washing tower is 35 - 40°C; the temperature of the raw coke oven gas discharged from the top of the water washing tower after recovering heat is 40 - 45°C;

[0022] Further, the components of the heavy tar include asphaltene, anthracene, phenanthrene, methylnaphthalene, carbazole, and xylenol, and the temperature of the heavy tar discharged from the bottom of the clarifying tank (L01) is 150 - 200°C; the components of the light oil 01 product include naphthalene, indole, dimethylnaphthalene, quinoline, and phenol, and the temperature of the light oil 01 product discharged from the upper stage of the quenching oil tower (T01) is 85 - 105°C; the components of the light oil 02 product include benzene, toluene, xylene, and pyridine, and the temperature of the light oil 02 product discharged from the lower stage of the water washing tower (T02) is 50 - 65°C.

[0023] The advantages and beneficial effects of the present invention are as follows:

[0024] The raw coke oven gas waste heat recovery device and method of the present invention realize the waste heat recovery of coke oven raw coke oven gas, and at the same time effectively separate light and heavy tars, coke powder and other solid particles in the raw coke oven gas. While completing the purification of the raw coke oven gas, the oil products in the raw coke oven gas are efficiently recovered. The oil product recovery rate is ≥80%, and the water content of the recovered oil products is ≤1%. It has important significance for the resource utilization of the raw coke oven gas and the energy conservation and consumption reduction of the entire coking system.

[0025] Other features and advantages of the present invention will be described in detail in the following specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0027] Figure 1 Schematic diagram of the waste gas heat recovery device for Embodiment 1 of the present invention.

[0028] Figure 2 Schematic diagram of the waste gas heat recovery device for Embodiment 3 of the present invention.

[0029] Description of reference numerals:

[0030] C01: Gas-liquid mixer; T01: Quenching oil tower; T02: Water washing tower; E01: First-stage heat exchanger at the lower section of the quenching oil tower; E02: Second-stage heat exchanger at the lower section of the quenching oil tower; E03: First-stage heat exchanger at the upper section of the quenching oil tower; E04: Second-stage heat exchanger at the upper section of the quenching oil tower; E05: Heat exchanger at the lower section of the water washing tower; E06: Heat exchanger at the upper section of the water washing tower; L01: Clarifying tank; P01: Transfer pump at the bottom of the quenching oil tower; P02: Circulation pump at the lower section of the quenching oil tower; P03: Heavy tar discharge pump; P04: Circulation pump at the upper section of the quenching oil tower; P05: Circulation pump at the lower section of the water washing tower; P06: Circulation pump at the upper section of the water washing tower; P07: Liquid feed pump for the gas-liquid mixer. Detailed implementation manners

[0031] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein.

[0032] For the convenience of comparison, in the following examples and comparative examples, the treatment scale of the waste gas purification device is compared at 1 million m 3 / year, and the composition of the waste gas is as shown in Table 1 below:

[0033] Table 1

[0034] Component of raw coke oven gas Volume content <![CDATA[H2]]> 19％ <![CDATA[CH4]]> 20％ CO 8％ <![CDATA[CO2]]> 6％ Other hydrocarbons 5％ Water vapor 42％

[0035] Example 1

[0036] As Figure 1 shown in the schematic diagram of the waste gas heat recovery device, it includes: a quenching oil tower T01, a water washing tower T02, a clarifying tank L01, and a gas-liquid mixer C01. The quenching oil tower T01 is equipped with a first-stage heat exchanger E01 at the lower section of the quenching oil tower, a second-stage heat exchanger E02 at the lower section of the quenching oil tower, a first-stage heat exchanger E03 at the upper section of the quenching oil tower, a second-stage heat exchanger E04 at the upper section of the quenching oil tower, and a transfer pump P01 at the bottom of the quenching oil tower, a circulation pump P02 at the lower section of the quenching oil tower, a heavy tar discharge pump P03, and a circulation pump P04 at the upper section of the quenching oil tower; the water washing tower T02 is equipped with a heat exchanger E05 at the lower section of the water washing tower, a heat exchanger E06 at the upper section of the water washing tower, and a circulation pump P05 at the lower section of the water washing tower, a circulation pump P06 at the upper section of the water washing tower. The gas-liquid mixer C01 is equipped with a liquid feed pump P07 for the gas-liquid mixer.

[0037] The connection relationships between the above devices are as follows:

[0038] The quench oil tower T01 has a lower section feed port, an upper section discharge port, a bottom discharge port, and a top gas phase outlet. The feed pipeline S1 is connected to the gas-liquid mixer C01. The gas-liquid mixer C01 is connected to the lower section feed port of the quench oil tower T01 through the pipeline S39. The top gas phase outlet of the quench oil tower T01 is connected to the lower section feed port of the water wash tower T02 through the pipeline S22. The top gas outlet pipe S34 of the water wash tower T02 serves as the raw coal gas outlet pipeline after recovering waste heat;

[0039] The quench oil tower T01 is divided into upper and lower parts with gas-phase connection by a partition. A number of openings are provided on the partition, and the openings are all connected to riser pipes for maintaining gas connection between the lower and upper sections inside the tower. The distance between the upper outlet position of the riser pipe and the partition is 2000 mm, and the distance between the lower outlet position of the riser pipe and the partition is 250 mm. The upper section of the quench oil tower T01 is provided with an upper section discharge port, an upper section circulating spray nozzle, a top gas phase outlet, and internal components. The internal components include a liquid distributor and structured packing. The lower section of the quench oil tower T01 is provided with a bottom discharge port, a lower section circulating spray nozzle, and internal components. The internal components of the lower section include a liquid distributor and trays;

[0040] The pipeline of the bottom discharge port of the quench oil tower T01 is divided into two paths. One path is connected to the liquid feed pump P07 of the gas-liquid mixer through the pipeline S35. The outlet pipeline S36 of the liquid feed pump P07 of the gas-liquid mixer is connected to the cooling spray nozzle inside the gas-liquid mixer C01. The other path is connected to the quench oil tower bottom transfer pump P01 through the pipeline S2. The discharge pipeline S3 of the quench oil tower bottom transfer pump P01 is connected to the first-stage heat exchanger E01 in the lower section of the quench oil tower. After the material exchanges heat through the first-stage heat exchanger E01 in the lower section of the quench oil tower, it enters the second-stage heat exchanger E02 in the lower section of the quench oil tower through the discharge pipeline S4. After the material recovers heat through the second-stage heat exchanger E02 in the lower section of the quench oil tower, it flows out from the discharge pipeline S5 and enters the clarification tank L01. The bottom discharge pipeline S6 of the clarification tank L01 is connected to the heavy tar external discharge pump P03. The middle discharge pipeline S8 is connected to the quench oil tower lower section circulating pump P02. The discharge pipeline S9 of the quench oil tower lower section circulating pump P02 is connected to the lower section circulating spray nozzle of the quench oil tower;

[0041] The upper section discharge port of the quench oil tower T01 is connected to the upper section recycle pump P04 of the quench oil tower through pipeline S14. The outlet pipeline S15 of the upper section recycle pump P04 of the quench oil tower is connected to the first-stage heat exchanger E03 of the upper section of the quench oil tower. After the material recovers heat through the first-stage heat exchanger E03 of the upper section of the quench oil tower, it flows out through the discharge pipeline S16 and enters the second-stage heat exchanger E04 of the upper section of the quench oil tower. After the material recovers heat through the second-stage heat exchanger E04 of the upper section of the quench oil tower, it is divided into two streams. One stream is connected to the upper section recycle spray nozzle through pipeline S17 and returns to the upper section of the quench oil tower T01, and one stream flows out of light oil 01 product to the outside of the system through pipeline S18;

[0042] The water wash tower T02 is divided into upper and lower sections with gas-phase connection by a partition plate; several openings are arranged on the partition plate, and all the openings are connected with riser pipes for maintaining the gas connection between the lower and upper sections of the tower; the distance between the upper end outlet position of the riser pipe and the partition plate is 2000mm, and the distance between the lower end outlet position of the riser pipe and the partition plate is 200mm;

[0043] The water wash tower T02 has a lower section feed port, a tower bottom discharge port, a light oil 02 product discharge port, an upper section discharge port and a top discharge port; a tower bottom discharge port, a lower section discharge port, a light oil 02 product discharge port, a lower section recycle spray nozzle and internal components are arranged in the lower section of the water wash tower T02, and the internal components include: a liquid distributor, a tray; an overflow plate is arranged at the tower bottom of the water wash tower T02 for collecting light oil 02; the bottom of the overflow plate is welded to the tower bottom, and the height of the overflow pipe is 2000mm;

[0044] The tower bottom discharge port of the water wash tower T02 is connected to the lower section recycle pump P05 of the water wash tower through pipeline S24. The outlet pipeline S25 of the lower section recycle pump P05 of the water wash tower is connected to the lower section heat exchanger E05 of the water wash tower. After the material is heat-exchanged through the lower section heat exchanger E05 of the water wash tower, it is divided into two streams. One stream is connected to the lower section recycle spray nozzle through pipeline S26 and returns to the lower section of the water wash tower T02, and one stream discharges sewage to the outside of the system through pipeline S38.

[0045] The light oil 02 product discharge port of the water wash tower T02 flows out the light oil 02 product to the outside of the system through pipeline S23.

[0046] An upper section discharge port, an upper section recycle spray nozzle, a top discharge port and internal components are arranged in the upper section of the water wash tower T02, and the internal components include a liquid distributor, packing. The upper section discharge port of the water wash tower T03 is connected to the upper section recycle pump P06 of the water wash tower through pipeline S29. The outlet pipeline S30 of the upper section recycle pump P06 of the water wash tower is connected to the upper section heat exchanger E06 of the water wash tower. After the material is heat-exchanged through the upper section heat exchanger E06 of the water wash tower, it is divided into two streams. One stream is connected to the upper section recycle spray nozzle through pipeline S31 and returns to the upper section of the water wash tower T02, and one stream is connected to the lower section recycle spray nozzle through pipeline S37 and returns to the lower section of the water wash tower T02.

[0047] Example 2

[0048] A method for recovering waste heat from raw coke oven gas, which uses the raw coke oven gas waste heat recovery device described in Embodiment 1 to recover the waste heat of raw coke oven gas, includes:

[0049] The raw coke oven gas at 500 - 850 °C coming from the coke oven riser pipe is in full contact with the quench recycle oil discharged from the bottom of the quench oil tower T01 in the gas-liquid mixer C01 and undergoes quenching. The mixed gas-liquid material is cooled to 300 °C and sent into the quench oil tower T01.

[0050] In the lower section of the quench oil tower T01, the incoming tower material is in full contact with the lower section recycle oil sprayed from the lower section recycle spray nozzle, conducts heat exchange, and separates gas, liquid, and solid particles. The separated gas phase enters the upper section T01 of the quench oil tower to continue heat recovery. The recycle oil entraining solids is cooled to 280 °C and sent out from the tower bottom in two paths. One path of the material returns to the gas-liquid mixer C01, and the other path of the material enters the first-stage heat exchanger E01 at the bottom of the quench oil tower through the pipeline S2 by the quench oil tower bottom transfer pump P01, and exchanges heat with the pressurized condensate water at a pressure of 3.0 Mpa and a temperature of 235 °C. After heat exchange, the temperature of the recycle oil drops to 250 °C, and the pressurized condensate water after heat exchange is sent out of the system to prepare medium-pressure steam at 3.0 Mpa. The recycle oil coming out of the first-stage heat exchanger E01 at the bottom of the quench oil tower enters the second-stage heat exchanger E02 at the bottom of the quench oil tower through the pipeline S4, and exchanges heat with the pressurized condensate water at a temperature of 140 °C and a pressure of 0.4 Mpa. After heat exchange, the temperature of the recycle oil drops to 140 °C, and the pressurized condensate water after heat exchange is sent out of the system to prepare low-pressure steam at 0.4 Mpa. The recycle oil after heat exchange in the second-stage heat exchanger E02 at the bottom of the quench oil tower enters the clarifying tank L01.

[0051] In the upper section of the quench oil tower T01, the raw coke oven gas is in full contact with the upper section recycle oil of the quench oil tower T01 to exchange heat. The temperature of the separated gas phase drops to 110 °C and enters the lower part of the water wash tower T02 through the top gas phase outlet pipeline S22. The temperature of the upper section recycle oil after heat exchange in the quench oil tower T01 rises to 150 °C, and is connected to the upper section recycle pump P04 of the quench oil tower through the pipeline S14 at the upper section discharge port. The continuous flow of the upper section recycle pump P04 of the quench oil tower enters the first-stage heat exchanger E03 of the upper section of the quench oil tower and exchanges heat with the pressurized condensate water at a pressure of 0.2 Mpa and a temperature of 121 °C. After heat exchange, the temperature of the recycle oil drops to 125 °C, and the pressurized condensate water after heat exchange is sent out of the system to prepare low-pressure steam at 0.2 Mpa. The recycle oil coming out of the first-stage heat exchanger E03 of the upper section of the quench oil tower enters the second-stage heat exchanger E04 of the upper section of the quench oil tower through the pipeline S16 and exchanges heat with the cooling water at a temperature of 30 - 35 °C. After heat exchange, the temperature of the recycle oil drops to 105 °C and is divided into two paths of materials. One path is sent out of the system as the light oil 01 product, and the other path is returned to the upper part of the quench oil tower as the upper section recycle oil.

[0052] In the lower section of the water scrubber T02, the raw coal gas comes into full contact with the circulating water in the lower section of the water scrubber T02 to exchange heat. After heat exchange, the temperature of the raw coal gas drops to 80 - 85 °C and enters the upper section of the water scrubber T02. The temperature of the lower section circulating liquid after heat exchange rises to 70 - 75 °C, and oil-water separation is carried out at the bottom of the water scrubber T02. The separated oil phase discharges the light oil 02 product at 50 - 65 °C through the light oil 02 product discharge port of the water scrubber T02, and the separated water phase enters the lower section heat exchanger E05 of the water scrubber as the lower section circulating water through the bottom discharge port of the water scrubber and exchanges heat with the cooling water at 30 - 35 °C. After heat exchange, the temperature of the circulating water drops to 50 - 55 °C. Part of it returns to the lower section of the water scrubber T02 to wash the raw coal gas, and part of it is discharged from the system as sewage;

[0053] In the upper section of the water scrubber T02, the raw coal gas comes into full contact with the circulating liquid in the upper section of the water scrubber T02 to exchange heat. After heat exchange, the temperature of the raw coal gas drops to 40 - 45 °C and is discharged from the top of the water scrubber. The temperature of the upper section circulating liquid after heat exchange rises to 50 - 55 °C, and enters the upper section heat exchanger E06 of the water scrubber to exchange heat with the cooling water at 15 - 30 °C. After heat exchange, the temperature of the circulating liquid drops to 35 - 40 °C. Part of it returns to the upper section of the water scrubber T02 to wash the raw coal gas, and part of it returns to the lower section of the water scrubber T02 to wash the raw coal gas;

[0054] The main components of the heavy tar include asphaltene, anthracene, phenanthrene, methylnaphthalene, carbazole, and xylenol;

[0055] The main components of the light oil 01 product include naphthalene, indole, dimethylnaphthalene, quinoline, and phenol;

[0056] The main components of the light oil 02 product include benzene, toluene, xylene, and pyridine.

[0057] Example 3

[0058] As Figure 2 shown in the device for recovering the waste heat of the raw coal gas, the difference from Example 1 is only that the discharge pipeline S3 of the bottom transfer pump P01 of the quench oil tower is connected to the lower section primary heat exchanger E01 of the quench oil tower. After the material exchanges heat through the lower section primary heat exchanger E01 of the quench oil tower, it flows out through the discharge pipeline S5 and enters the clarifying tank L01; the outlet pipeline S15 of the upper section circulating pump P04 of the quench oil tower is connected to the upper section primary heat exchanger E03 of the quench oil tower. After the material recovers heat through the upper section primary heat exchanger E03 of the quench oil tower, it is divided into two streams. One stream is connected to the upper section circulating spray nozzle through the pipeline S17 and returns to the upper section of the quench oil tower T01, and the other stream flows out of the light oil 01 product to the outside of the system through the pipeline S18.

[0059] The quench oil tower T01 is divided into upper and lower sections with gas-phase connection by a partition plate. A number of openings are provided on the partition plate, and all the openings are connected to riser pipes for maintaining the gas connection between the lower and upper sections inside the tower. The distance between the upper outlet position of the riser pipe and the partition plate is 2000 mm, and the distance between the lower outlet position of the riser pipe and the partition plate is 500 mm. The upper section of the quench oil tower T01 is provided with an upper section discharge pipe opening, an upper section circulating spray pipe opening, a top gas-phase outlet and internals. The internals include a liquid distributor and a tray. The lower section of the quench oil tower T01 is provided with a bottom discharge opening, a lower section circulating spray pipe opening and internals. The internals in the lower section include: a liquid distributor, a grid and a wire mesh.

[0060] The water wash tower T02 is divided into upper and lower parts with gas-phase connection by a partition plate. A number of openings are provided on the partition plate, and all the openings are connected to riser pipes for maintaining the gas connection between the lower and upper sections inside the tower. The distance between the upper outlet position of the riser pipe and the partition plate is 2500 mm, and the distance between the lower outlet position of the riser pipe and the partition plate is 500 mm.

[0061] The upper section of the water wash tower T02 is provided with upper section internals including a liquid distributor and a tray.

[0062] Example 4

[0063] A method for recovering waste heat from raw coke oven gas uses the waste heat recovery device of Example 3 to recover the waste heat of raw coke oven gas, including:

[0064] The method for recovering waste heat from raw coke oven gas using the above device includes:

[0065] The raw coke oven gas at 500 - 850 °C coming from the coke oven riser pipe is in full contact with the quench circulation oil discharged from the bottom of the quench oil tower T01 in the gas-liquid mixer C01 and undergoes quenching. The mixed gas-liquid material is cooled to 280 °C and sent into the quench oil tower T01.

[0066] In the lower section of the quench oil tower T01, the incoming tower material is in full contact with the lower section circulation oil sprayed from the lower section circulating spray opening, conducts heat exchange and separates gas, liquid and solid particles. The separated gas phase enters the upper section T01 of the quench oil tower to continue heat recovery. The circulating oil entraining solids is cooled to 260 °C and sent out from the tower kettle in two paths. One path of the material returns to the gas-liquid mixer C01, and the other path of the material enters the first-stage heat exchanger E01 in the lower section of the quench oil tower through the pipeline S2 by the quench oil tower bottom transfer pump P01 and exchanges heat with the pressurized condensate water at a pressure of 1.0 Mpa and a temperature of 180 °C. After heat exchange, the temperature of the circulating oil drops to 200 °C, and the pressurized condensate water after heat exchange is sent out of the system to produce 1.0 Mpa low-pressure steam. The circulating oil after heat exchange in the first-stage heat exchanger E01 in the lower section of the quench oil tower enters the clarification tank L01;

[0067] In the upper section of the quench oil tower T01, the raw coal gas fully contacts and exchanges heat with the circulating oil in the upper section of the quench oil tower T01. The temperature of the separated gas phase is reduced to 105°C and enters the lower part of the water wash tower T02 through the top discharge pipe orifice. The temperature of the circulating oil in the upper section after heat exchange rises to 130°C and continuously enters the first-stage heat exchanger E03 of the upper section of the quench oil tower through the upper section discharge port by the quench oil tower upper section circulating pump P04, and exchanges heat with the pressurized condensate water at a pressure of 0.15 Mpa and a temperature of 112°C. After heat exchange, the temperature of the circulating oil drops to 115°C, and the pressurized condensate water after heat exchange is sent out of the system to produce low-pressure steam at 0.15 Mpa. The circulating oil coming out of the first-stage heat exchanger E03 of the upper section of the quench oil tower is divided into two streams of materials. One stream is sent out of the system as the light oil 01 product, and the other stream returns to the upper part of the quench oil tower as the upper section circulating oil.

[0068] In the lower section of the water wash tower T02, the raw coal gas fully contacts and exchanges heat with the circulating water in the lower section of the water wash tower T02. The temperature of the raw coal gas after heat exchange is reduced to 80 - 85°C and enters the upper section of the water wash tower T02. The temperature of the circulating liquid in the lower section after heat exchange rises to 65 - 70°C and undergoes oil-water separation at the bottom of the water wash tower T02. The separated oil phase discharges the light oil 02 product through the light oil 02 product discharge orifice of the water wash tower T02, and the separated water phase enters the heat exchanger E05 at the bottom of the water wash tower as the lower section circulating water to exchange heat with the cooling water at a temperature of 30 - 35°C. After heat exchange, the temperature of the circulating water drops to 50 - 55°C. Part of it returns to the lower section of the water wash tower T02 to wash the raw coal gas, and part is discharged out of the system as sewage.

[0069] In the upper section of the water wash tower T02, the raw coal gas fully contacts and exchanges heat with the circulating liquid in the upper section of the water wash tower T02. The temperature of the raw coal gas after heat exchange is reduced to 40 - 45°C and is discharged out of the system from the top of the water wash tower. The temperature of the circulating liquid in the upper section after heat exchange rises to 50 - 55°C and enters the heat exchanger E06 in the upper section of the water wash tower to exchange heat with the cooling water at a temperature of 15 - 30°C. After heat exchange, the temperature of the circulating liquid drops to 35 - 40°C. Part of it returns to the upper section of the water wash tower T02 to wash the raw coal gas, and part returns to the lower section of the water wash tower T02 to wash the raw coal gas.

[0070] The main components of the heavy tar include asphaltene, anthracene, phenanthrene, methylnaphthalene, carbazole, and xylenol;

[0071] The main components of the light oil 01 product include naphthalene, indole, dimethylnaphthalene, quinoline, and phenol;

[0072] The main components of the light oil 02 product include benzene, toluene, xylene, and pyridine.

[0073] Comparative Example 1

[0074] Comparative Example 1 adopts the traditional process and uses the same raw coal gas as in Examples 2 and 4.

[0075] The raw gas at 500 - 850 °C recovered from the riser pipe of the coke oven is mixed with a large amount of sprayed circulating ammonia water and enters the gas collecting pipe. After being cooled by the circulating ammonia water spray, the temperature of the raw gas drops to 85 - 95 °C, and then it enters the gas - liquid separator.

[0076] The liquid phase with solid particles separated in the gas - liquid separator enters the mechanical slag scraping tank, and the separated gas - phase raw gas enters the horizontal tube primary cooler to further cool the raw gas;

[0077] In the mechanical slag scraping tank, solid - liquid separation of the material is carried out. The solid particles separated from the mechanical slag scraping tank are discharged from the system as tar slag, and the separated liquid phase enters the ammonia - water separator;

[0078] In the ammonia - water separator, the liquid - phase material completes oil - water separation. Among them, the oil phase is collected as coal tar product, and part of the water phase returns to the raw gas collecting pipe as circulating ammonia water to cool the raw gas, and part of it enters the sewage treatment system as surplus ammonia water;

[0079] In the horizontal tube primary cooler, after the raw gas exchanges heat with circulating cooling water and low - temperature water, the temperature drops to 20 - 35 °C, completing cooling and purification, and is sent to the subsequent treatment unit.

[0080] Table 2 lists the recovery data of the raw gas waste heat recovery methods of Example 2 and Example 4 and Comparative Example 1, as well as the recovered oil product data under the same raw gas raw material conditions.

[0081] Table 2

[0082] Comparative example 1 Example 2 Example 4 Recovery of medium-pressure steam (3.0 Mpa) None 34.36 tons None Recovery of low-pressure steam (≤1.0 Mpa) None 88.26 tons 143.58 tons Oil recovery rate ≤70％ ≥80％ ≥80％ Water content of recovered oil ≥20％ ≤1％ ≤1％

[0083] From the data in Table 2, it can be seen that under the same raw gas conditions as in Example 2 and Example 4, using the method of Comparative Example 1, the medium - and low - temperature waste heat in the raw gas cannot be recovered. The recovery rate of the recovered oil product is ≤ 70%, and the moisture content of the recovered oil product exceeds 20%. Using the recovery methods of Example 2 and Example 4, the waste heat in the raw gas can be recovered in the form of medium - and low - pressure steam. Among them, using the recovery method of Example 2, for every 1 million cubic meters of raw gas processed, 34.36 tons of 3.0 Mpa medium - pressure steam and 88.26 tons of low - pressure steam ≤ 1.0 Mpa can be recovered; using the recovery method of Example 4, for every 1 million cubic meters of raw gas processed, 143.58 tons of low - pressure steam ≤ 1.0 Mpa can be recovered. And using Example 2 and Example 4 can more efficiently recover the oil product in the raw gas, with a recovery rate ≥ 80%, the moisture content of the recovered oil product ≤ 1%, and the quality is better. It shows that the method of the present invention can more efficiently recover the heat in the raw gas and more efficiently recover the oil product in the raw gas, with a lower moisture content of the recovered oil product and better quality.

[0084] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A waste gas heat recovery device, characterized in that Including: A quench oil tower (T01), a water wash tower (T02), a clarifying tank (L01) and a gas-liquid mixer (C01); both the quench oil tower (T01) and the water wash tower (T02) are equipped with supporting heat exchangers and material transfer pumps, and are divided into upper and lower sections with gas-phase connection by partitions; the quench oil tower (T01) has a lower section feed port, an upper section discharge port, a bottom discharge port and a top gas-phase outlet, and the water wash tower (T02) has a lower section feed port, a bottom discharge port, a light oil 02 product discharge port, an upper section discharge port and a top discharge port; the top gas-phase outlet of the quench oil tower (T01) is connected to the lower section feed port of the water wash tower (T02) through a pipeline; the gas-liquid mixer (C01) is on the feed pipeline of the quench oil tower (T01), and the bottom discharge pipeline of the quench oil tower (T01) is divided into two paths. One path passes through the liquid feed pump (P07) of the gas-liquid mixer and is connected to the gas-liquid mixer (C01), and the other path is sequentially connected to the clarifying tank (L01) through the bottom transfer pump (P01) of the quench oil tower and the lower section heat exchanger of the quench oil tower. The bottom discharge pipeline of the clarifying tank (L01) is connected to the heavy tar external discharge pump (P03), and the middle discharge pipeline passes through the lower section recycle pump (P02) of the quench oil tower and is connected to the lower section recycle spray nozzle of the quench oil tower (T01); the upper section discharge pipeline of the quench oil tower (T01) passes through the upper section recycle pump (P04) of the quench oil tower and the upper section heat exchanger of the quench oil tower and is then divided into two paths. One path is used as the output pipeline of the light oil 01 product, and the other path enters the upper section of the quench oil tower (T01); the bottom discharge pipeline of the water wash tower (T02) passes through the lower section recycle pump (P05) of the water wash tower and the lower section heat exchanger (E05) of the water wash tower and is then divided into two paths. One path is used as the system external discharge sewage pipeline, and the other path enters the lower section of the water wash tower. The top discharge pipeline of the water wash tower (T02) is used as the waste gas pipeline of the raw gas after recovering waste heat.

2. The waste gas heat recovery device according to claim 1, wherein The upper discharge port of the water wash tower (T02) passes through the upper section recycle pump (P06) of the water wash tower and the upper section heat exchanger (E06) of the water wash tower and is then divided into two paths. One path enters the lower section of the water wash tower (T02), and the other path enters the upper section of the water wash tower (T02).

3. The waste gas heat recovery device according to claim 1, characterized in that, The internal components of the lower section of the quench oil tower (T01) are one or more of grille, wire mesh, tray, distributor; the internal components of the lower section of the water wash tower (T02) are one or more of distributor, tray, packing; the internal components of the upper sections of the quench oil tower (T01) and the water wash tower (T02) are all distributor, tray, packing or their combination; the partition structures of the quench oil tower (T01) and the water wash tower (T02) both adopt head or liquid collecting tank.

4. The waste gas heat recovery device according to claim 1, characterized in that, The upper section heat exchanger of the quench oil tower is one or two of the upper section primary heat exchanger (E03) of the quench oil tower and the upper section secondary heat exchanger (E04) of the quench oil tower; the lower section heat exchanger of the quench oil tower is one or two of the lower section primary heat exchanger (E01) of the quench oil tower and the lower section secondary heat exchanger (E02) of the quench oil tower.

5. The waste gas heat recovery device according to claim 4, wherein The heat exchange medium of the first-stage heat exchanger (E01) at the lower stage of the quench oil tower is medium-pressure circulating water, the temperature of the medium-pressure circulating water is 220 - 235 °C, and the absolute pressure is 2.5 - 3.0 Mpa; the heat exchange medium of the second-stage heat exchanger (E02) at the lower stage of the quench oil tower is low-pressure circulating water, the temperature of the low-pressure circulating water is 140 - 180 °C, and the absolute pressure is 0.4 - 1.0 Mpa; the heat exchange medium of the first-stage heat exchanger (E03) at the upper stage of the quench oil tower is low-pressure circulating water, the temperature of the low-pressure circulating water is 112 - 134 °C, and the absolute pressure is 0.15 - 0.3 Mpa; the heat exchange medium of the second-stage heat exchanger (E04) at the upper stage of the quench oil tower is circulating water, and the temperature of the circulating water is 30 - 50 °C.

6. A method for recovering waste heat from raw coke oven gas, characterized in that, Using the waste gas heat recovery device according to any one of claims 1 - 5 to recover the waste heat of the waste gas, including: The waste gas at 500 - 850 °C coming from the coke oven riser pipe is mixed with the quench circulating oil discharged from the bottom of the quench oil tower (T01) in the gas-liquid mixer (C01), and the mixed gas-liquid material is cooled to 280 - 300 °C and sent to the lower stage of the quench oil tower (T01); In the lower stage of the quench oil tower (T01), the mixed gas-liquid material exchanges heat with the circulating oil at the lower stage of the quench oil tower (T01) and is separated. The separated gas phase enters the upper stage of the quench oil tower (T01) for heat recovery. The lower-stage circulating oil entraining solids is sent out in two paths from the bottom discharge port. One path returns to the gas-liquid mixer (C01), and the other path of the material continuously enters the heat exchanger of the lower stage of the quench oil tower for heat exchange and then enters the clarifying tank (L01). The heavy tar is discharged from the bottom of the clarifying tank (L01), and the circulating oil is discharged from the side to the lower stage of the quench oil tower (T01); In the upper stage of the quench oil tower (T01), after the waste gas exchanges heat with the circulating oil at the upper stage of the quench oil tower (T01), the separated gas phase enters the lower part of the water washing tower (T02). The upper-stage circulating oil continuously enters the heat exchanger of the upper stage of the quench oil tower for heat exchange, and a part of it returns to the upper stage of the quench oil tower (T01), and a part is collected as the light oil 01 product; In the lower stage of the water washing tower (T02), the waste gas after heat exchange in the upper stage of the quench oil tower (T01) exchanges heat with the circulating liquid at the lower stage of the water washing tower (T02) and then enters the upper stage of the water washing tower (T02). The heat-exchanged lower-stage circulating liquid undergoes oil-water separation in the bottom of the water washing tower (T02). The oil phase is collected as the light oil 02 product, and the separated water phase continuously enters the heat exchanger (E05) of the lower stage of the water washing tower for heat exchange, and a part of it returns to the lower stage of the water washing tower (T02), and a part is discharged from the system as sewage; In the upper stage of the water washing tower (T02), the waste gas after heat exchange exchanges heat with the circulating liquid at the upper stage of the water washing tower (T02) and then is sent to the subsequent waste gas processing system through the top discharge port. The heat-exchanged lower-stage circulating liquid enters the heat exchanger (E06) of the upper stage of the water washing tower for heat exchange, and a part of it returns to the upper stage of the water washing tower (T02), and a part returns to the lower stage of the water washing tower (T02).

7. The waste gas heat recovery method according to claim 6, characterized in that, The temperature of the circulating oil discharged from the bottom of the quenching oil tower (T01) is 260 - 280 °C; the temperature of the circulating oil entering the clarifying tank (L01) is 150 - 200 °C; the temperature of the upper-stage circulating oil after heat exchange in the upper stage of the quenching oil tower (T01) is 130 - 150 °C; the temperature of the light oil 01 product is 85 - 105 °C.

8. The waste gas heat recovery method according to claim 6, characterized in that, The temperature of the raw coal gas entering the water washing tower (T02) is 105 - 110 °C; the temperature of the lower-stage circulating liquid after heat exchange in the water washing tower (T02) is 65 - 75 °C; the heat exchange medium of the lower-stage heat exchanger (E05) of the water washing tower is circulating cooling water, and the temperature of the circulating cooling water is 30 - 40 °C; the temperature of the light oil 02 product is 65 - 75 °C; the temperature of the raw coal gas after heat exchange in the lower stage of the water washing tower is 50 - 65 °C; the temperature of the upper-stage circulating liquid after heat exchange in the water washing tower (T02) is 50 - 55 °C; the heat exchange medium of the upper-stage heat exchanger (E06) of the water washing tower is low-temperature circulating water, and the temperature of the low-temperature circulating water is 15 - 30 °C; the temperature of the circulating liquid after heat exchange in the upper-stage heat exchanger (E06) of the water washing tower is 35 - 40 °C; the temperature of the raw coal gas after heat recovery from the top of the water washing tower (T02) is 40 - 45 °C.

9. The method for recovering waste gas heat according to claim 6, characterized in that, The components of the heavy tar include asphaltene, anthracene, phenanthrene, methylnaphthalene, carbazole, and xylenol. The temperature of the heavy tar discharged from the bottom of the clarifying tank (L01) is 150 - 200 °C; The components of the light oil 01 product include naphthalene, indole, dimethylnaphthalene, quinoline, and phenol. The temperature of the light oil 01 product discharged from the upper stage of the quenching oil tower (T01) is 85 - 105 °C; The components of the light oil 02 product include benzene, toluene, xylene, and pyridine. The temperature of the light oil 02 product discharged from the lower stage of the water washing tower (T02) is 50 - 65 °C.

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