Ascending pipe follow-up raw gas waste heat recovery equipment

Abstract

The utility model relates to the technical field of chemical industry, energy conservation and environmental protection, in particular to ascending pipe follow-up raw gas waste heat recovery equipment which comprises a bridge pipe, a high-temperature gas collecting pipe, a low-temperature gas collecting pipe, a pi-shaped pipe, a second coal tar spraying head, a first coal tar spraying head, a heavy oil tank, a high-temperature oil pump, a high-temperature oil pipeline, a heat exchange boiler and a tar settling tank. Two ends of the pi-shaped pipe are respectively connected with the top end of the high-temperature gas collecting pipe and the top end of the low-temperature gas collecting pipe; the first coal tar spraying head is arranged in the bridge pipe, the second coal tar spraying head is arranged in the pi-shaped pipe, an outlet of the high-temperature gas collecting pipe is connected with an inlet of the heavy oil tank, an outlet of the heavy oil tank is connected with the high-temperature oil pump, an outlet of the high-temperature oil pump is connected with an inlet of the heat exchange boiler, and a bottom end outlet of the heat exchange boiler is connected with an inlet of the tar settling tank. The device can recover heat energy below 500 DEG C of raw coke oven gas, reduce the load of the primary cooler, generate steam for use, and improve economic benefits.

Description

Technical Field

[0001] The utility model relates to the technical fields of chemical engineering, energy conservation and environmental protection, in particular to a waste heat recovery device for raw coke oven gas after the riser pipe. Background Technique

[0002] During the production process of coke ovens, a large amount of raw coke oven gas is produced, and the raw coke oven gas contains organic compounds such as tar, benzene, and naphthalene. The temperature of the raw coke oven gas is 650°C to 750°C. At present, the main method for recovering heat energy is to change the ordinary riser pipe into a riser pipe heat exchanger, and usually reduce the raw coke oven gas to 500°C to recover a part of the heat energy. If the temperature of the raw coke oven gas continues to drop, tar will condense and block the riser pipe. Therefore, in the current riser pipe waste heat utilization project, the recovery efficiency of heat energy is only 30% - 35%. Ammonia water is sprayed at the subsequent bridge pipe of the riser pipe, the ammonia water evaporates, absorbs the heat energy of the raw coke oven gas, the temperature of the raw coke oven gas drops to 85°C, and the ammonia water turns into steam and enters the raw coke oven gas. The raw coke oven gas enters the primary cooler, and the circulating cooling water in the primary cooler cools the raw coke oven gas to 25°C, and the moisture in the raw coke oven gas condenses and is discharged. The primary cooler uses circulating cooling water, and the cooling water tower fan needs to operate for cooling, consuming electricity and increasing the electricity cost.

[0003] Spraying ammonia water has a negative impact in actual coking production. Since the ammonia water is recycled, the concentration of ammonium salts in the ammonia water continues to accumulate. The tar and ammonia water in the collecting pipe are mixed together, and under the action of pulverized coal and coke powder, an emulsion of tar and water is formed, and the salts also enter the tar. During the subsequent tar distillation to extract various valuable oil products, it is first necessary to break the emulsion, then separate the tar and ammonia water, and then add sodium carbonate to separate ammonia, which causes sodium chloride to enter the tar. It is necessary to control the amount of sodium carbonate added to prevent the salt content from being too high. The subsequent ammonia water spraying process of the riser pipe not only wastes the heat energy of the raw coke oven gas, but also causes some salts to enter the tar due to the recycling of ammonia water, reducing the quality of the tar. At present, coking enterprises generally hope to update the process equipment to recover the heat energy below 500°C of the raw coke oven gas and reduce the use of ammonia water.

[0004] Patent technology of Qingdao University of Science and Technology, "Waste gas heat recovery system and method based on washing and rectification", application publication number CN 105779027 A, inventors, Chen Guanghui, Wang Weiwen. Qingdao University of Science and Technology proposed a heat recovery system for a washing and distillation tower, using a distillation tower device with a height of 20 meters. In the trays at different heights of the tower, light components are distilled and separated, and the heat energy of waste gas is recovered. Since there are many tar components, the distillation tower is 20 meters high and cannot be reduced. Chen Guanghui and Wang Weiwen communicated with the author of this article and, under the leadership of the author of this article, entered the coking plant for on-site investigation. When inspecting the top of the coke oven, it was found that the patented technology equipment of Qingdao University of Science and Technology, the washing and distillation tower, is 20 meters high, the equipment is too high, and the distillation tower cannot be docked and installed with the existing equipment of the coke oven, including the riser pipe and the collecting pipe. The patented technology of Qingdao University of Science and Technology can only stay at the theoretical level and cannot be applied in the actual application of the coke oven. To sum up, the coking plant needs to reduce costs and improve energy utilization efficiency, and intends to further recover the heat energy of waste gas below 500 °C behind the riser pipe. When the waste gas drops below 380 °C, a large amount of tar will condense and precipitate. To prevent tar from accumulating on the inner surface of the steel pipe, the new equipment also needs to solve this problem. Utility Model Content

[0005] In order to solve the problems of the heat energy recovery process flow of waste gas below 500 °C and the problem of tar precipitation in the coking plant, the present utility model proposes a waste gas waste heat recovery device after the riser pipe to achieve the purpose of reusing heat energy and separating tar components.

[0006] The specific technical solutions adopted are as follows:

[0007] A waste gas waste heat recovery device after the riser pipe includes a bridge pipe, a high-temperature collecting pipe, a low-temperature collecting pipe, a π-shaped pipe, a second coal tar spray head, a first coal tar spray head, a heavy oil tank, a high-temperature oil pump, a high-temperature oil pipeline, a heat exchange boiler, and a tar sedimentation tank; one end of the bridge pipe is connected to the riser pipe, the other end of the bridge pipe is connected to the inlet of the high-temperature collecting pipe, both ends of the π-shaped pipe are respectively connected to the top of the high-temperature collecting pipe and the top of the low-temperature collecting pipe, and it is arranged above the high-temperature collecting pipe and the low-temperature collecting pipe; the first coal tar spray head is arranged in the bridge pipe, the second coal tar spray head is arranged in the π-shaped pipe, the bottom outlet of the high-temperature collecting pipe is connected to the inlet of the heavy oil tank, the outlet of the heavy oil tank is connected to the inlet of the high-temperature oil pump, the outlet of the high-temperature oil pump is connected to the inlet of the heat exchange boiler through the high-temperature oil pipeline, and the bottom outlet of the heat exchange boiler is connected to the inlet of the tar sedimentation tank.

[0008] Further, the π-shaped pipe includes a first vertical pipe of the π-shaped pipe, a horizontal pipe of the π-shaped pipe, and a second vertical pipe of the π-shaped pipe connected in sequence. The π-shaped pipe has an overall π-shaped structure. The horizontal pipe of the π-shaped pipe is located above the first vertical pipe and the second vertical pipe of the π-shaped pipe. The horizontal pipe of the π-shaped pipe is connected to the first vertical pipe and the second vertical pipe of the π-shaped pipe through π-shaped pipe elbows respectively. The bottom end of the first vertical pipe of the π-shaped pipe is connected to the top end of the high-temperature gas collector, and the bottom end of the second vertical pipe of the π-shaped pipe is connected to the top end of the low-temperature gas collector.

[0009] Further, the first vertical pipe of the π-shaped pipe is a heavy oil spray vertical pipe, and the second coal tar spray head is arranged at the top of the first vertical pipe of the π-shaped pipe. The second vertical pipe of the π-shaped pipe is a wash oil spray heat exchanger, and the first wash oil spray head is arranged at the top of the second vertical pipe of the π-shaped pipe. A heat exchanger is arranged inside the second vertical pipe of the π-shaped pipe. The π-shaped pipe is a composite steel pipe, the inner surface is a non-stick coating, and the outside of the π-shaped pipe is a heat insulation layer.

[0010] Further, the recovery equipment further includes a gas-liquid separator, a primary cooler, a rich oil storage tank, a rich oil pump, a rich oil heater, and a distillation column. The inlet of the gas-liquid separator is connected to the outlet of the low-temperature gas collector, and the upper outlet of the gas-liquid separator is connected upward to the primary cooler. The bottom outlet of the gas-liquid separator is connected to the inlet of the rich oil storage tank, the outlet of the rich oil storage tank is connected to the inlet of the rich oil pump, the outlet of the rich oil pump is connected to the inlet at the bottom end of the rich oil heater, and the outlet at the upper end of the rich oil heater is connected to the distillation column.

[0011] Further, the high-temperature oil pipeline 10 is made of stainless steel, and a heat insulation material is provided on its outer surface. The heat insulation material is made of aluminosilicate fiber blanket, and the outside of the heat insulation material is wrapped with a heat insulation outer skin, and the heat insulation outer skin is made of aluminum skin for heat insulation.

[0012] Further, a high-temperature valve is arranged at the first end of the bridge pipe, and the high-temperature valve is made of heat-resistant steel. A steam spray head is arranged inside the bridge pipe.

[0013] Further, a plurality of second wash oil spray heads are arranged at the top of the low-temperature gas collector. The low-temperature gas collector is made of stainless steel, and the outside is heat-insulated with aluminosilicate fiber or alumina fiber.

[0014] Further, the bridge pipe is an arc-shaped elbow pipe, and the high-temperature gas collector is arranged below the bridge pipe.

[0015] Further, both the high-temperature gas collector and the heavy oil tank adopt a double-layer steel pipe structure. The inner layer steel pipe is made of 304, 316, 309 or 310S material, and the outer layer steel pipe is made of carbon steel or stainless steel.

[0016] Further, the inner layer and the outer layer of the double-layer steel pipe structure are supported by a steel structure and filled with aluminosilicate ceramic fiber blanket.

[0017] The beneficial effects of the present utility model are:

[0018] First, the present utility model belongs to a brand-new device. Currently, the riser pipe of the coke oven can only reduce the raw gas to 500 °C. The present utility model can further recover the heat energy of the raw gas below 500 °C, reduce the load of the primary cooler, generate steam for use, and improve economic benefits.

[0019] Second, coal tar is sprayed on the bridge pipe and the first vertical pipe of the π-shaped pipe. The coal tar and the raw gas directly conduct heat exchange, with high heat exchange efficiency. At the same time, the tar vapor in the raw gas is washed by the coal tar and enters the high-temperature gas collecting pipe. The coal tar washing flushes the precipitated tar and flows downward into the high-temperature gas collecting pipe, solving the problem of blockage of the pipe caused by the precipitation of coal tar below 500 °C.

[0020] Third, coal tar includes components such as tar pitch, anthracene oil, wash oil, naphthalene oil, phenol oil, and light oil, and is a mixture of various components. The first vertical pipe of the π-shaped pipe is a heavy oil spraying vertical pipe, and the second vertical pipe of the π-shaped pipe is a wash oil spraying heat exchanger. Taking 230 °C as the demarcation point, heavy oil is mainly recovered above 230 °C, and components such as naphthalene, phenol, and light oil are mainly recovered below 230 °C. In the first vertical pipe of the π-shaped pipe, the high-molecular-weight heavy components such as tar pitch, anthracene oil, and wash oil are first recovered. The second vertical pipe of the π-shaped pipe is a wash oil spraying heat exchanger, and naphthalene, phenol, light oil and other components are recovered with wash oil. The present application can realize the preliminary separation of tar heavy oil and light oil, providing convenient conditions for subsequent tar deep processing.

[0021] Fourth, coal tar is sprayed on the bridge pipe without spraying ammonia water, and the water content of the coal tar will be greatly reduced, improving the quality of the coal tar. In the previous process equipment, spraying ammonia water would cause the tar to contain 4% water. When various components were distilled and extracted from the subsequent coal tar, dehydration had to be carried out first and then distillation. Since the tar in this application has less water, the energy consumption of subsequent production can be reduced.

[0022] Fifth, in the traditional bridge pipe spraying ammonia water, the circulating ammonia water used accumulates ammonium salts, resulting in an increase in the salt content of the coal tar. When producing subsequently, sodium carbonate needs to be added to separate the ammonia, and the salt finally exists in the tar in the form of sodium chloride. This application cancels the spraying of ammonia water on the bridge pipe, the tar has a low salt content, the quality will be further improved, the selling price of the tar will be increased, and the economic benefits will be improved. Brief Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a subsequent waste heat recovery device for raw gas of a riser pipe of the present utility model;

[0024] Figure 2 It is a schematic structural diagram of the subsequent process of the rich oil storage tank of the present utility model;

[0025] Among them, 1. riser pipe; 2. high-temperature valve; 3. steam nozzle; 4. first coal tar spray head; 5. first vertical pipe of π-shaped pipe; 6. second vertical pipe of π-shaped pipe; 7. high-temperature gas collector; 8. heavy oil tank; 9. high-temperature oil pump; 10. high-temperature oil pipeline; 11. low-temperature gas collector; 12. second coal tar spray head; 13. horizontal pipe of π-shaped pipe; 14. elbow of π-shaped pipe; 15. spray pipe; 16. second wash oil spray head; 17. bridge pipe; 18. first wash oil spray head; 19. gas-liquid separator; 20. primary cooler; 21. rich oil storage tank; 22. heat exchange boiler; 23. tar sedimentation tank; 24. rich oil pump; 25. rich oil heater; 26. distillation column. Specific embodiments

[0026] To better explain the present invention for easy understanding, the technical solutions and effects of the present invention will be described in detail below in conjunction with the accompanying drawings through specific embodiments.

[0027] As Figure 1 and Figure 2 shown, this embodiment provides a waste heat recovery device for the subsequent raw coal gas of the riser pipe, including a bridge pipe 17, a high-temperature gas collector 7, a low-temperature gas collector 11, a π-shaped pipe, a second coal tar spray head 12, a first coal tar spray head 4, a heavy oil tank 8, a high-temperature oil pump 9, a high-temperature oil pipeline 10, a heat exchange boiler 22, and a tar sedimentation tank 23; one end of the bridge pipe 17 is connected to the riser pipe 1, the other end of the bridge pipe 17 is connected to the inlet of the high-temperature gas collector 7, the bridge pipe 17 is an arc-shaped elbow, and the high-temperature gas collector 7 is arranged below the bridge pipe 17; both ends of the π-shaped pipe are respectively connected to the top of the high-temperature gas collector 7 and the top of the low-temperature gas collector 11, and are arranged above the high-temperature gas collector 7 and the low-temperature gas collector 11; the first coal tar spray head 4 is arranged in the bridge pipe 17, the second coal tar spray head 12 is arranged in the π-shaped pipe, the bottom outlet of the high-temperature gas collector 7 is connected to the inlet of the heavy oil tank 8, the outlet of the heavy oil tank 8 is connected to the inlet of the high-temperature oil pump 9, the outlet of the high-temperature oil pump 9 is connected to the inlet of the heat exchange boiler 22 through the high-temperature oil pipeline 10, and the bottom outlet of the heat exchange boiler 22 is connected to the inlet of the tar sedimentation tank 23. The heavy oil tank 8 is used to collect high-temperature coal tar, and the high-temperature oil pump 9 sends the introduced coal tar into the heat exchange boiler 22 through the high-temperature oil pipeline 10 for heat exchange to generate steam, and the steam is recovered and utilized. After the heavy oil leaves the boiler, the temperature drops to 80 °C and enters the tar sedimentation tank 23. Using the principle of gravity sedimentation, the pulverized coal and coke powder in the heavy oil are separated, and the remaining high-quality heavy oil enters the tar storage tank for storage (not shown in the figure). The setting of the heavy oil tank 8 can ensure the stable flow rate at the inlet of the high-temperature oil pump 9.

[0028] In this embodiment, the π-shaped pipe includes a first vertical pipe 5 of the π-shaped pipe, a horizontal pipe 13 of the π-shaped pipe, and a second vertical pipe 6 of the π-shaped pipe that are connected in sequence. The π-shaped pipe has an overall π-shaped structure. The horizontal pipe 13 of the π-shaped pipe is located above the first vertical pipe 5 and the second vertical pipe 6 of the π-shaped pipe. The horizontal pipe 13 of the π-shaped pipe is connected to the first vertical pipe 5 and the second vertical pipe 6 of the π-shaped pipe respectively through π-shaped pipe elbows 14. The bottom end of the first vertical pipe 5 of the π-shaped pipe is connected to the top end of the high-temperature gas collector 7, and the bottom end of the second vertical pipe 6 of the π-shaped pipe is connected to the top end of the low-temperature gas collector 11. The first vertical pipe 5 of the π-shaped pipe is a heavy oil spray vertical pipe. The second coal tar spray head 12 is arranged at the top of the first vertical pipe 5 of the π-shaped pipe and has an empty tower structure. The second coal tar spray head 12 in the first vertical pipe 5 of the π-shaped pipe sprays the coal tar conveyed by the spray pipe 15. The sprayed coal tar has a washing effect. The raw coal gas entering the first vertical pipe 5 of the π-shaped pipe precipitates coal tar. After the coal tar is precipitated, it will be washed away by the sprayed coal tar.

[0029] The π-shaped pipe is a composite steel pipe. The inner surface of the π-shaped pipe is a ceramic non-stick coating to prevent coal tar from accumulating on the inner surface of the steel pipe. The outside of the π-shaped pipe is an aerogel high-efficiency heat insulation layer to prevent heat loss caused by heat dissipation. The raw coal gas is cooled in the first vertical pipe 5 of the π-shaped pipe, and a large amount of coal tar is precipitated. The coal tar sprayed by the second coal tar spray head 12 and the condensed coal tar flow downward together, enter the high-temperature gas collector 7, are mixed with the coal tar, enter the heavy oil tank 8, and are pumped out together by the high-temperature oil pump 9. In this way, the problem of tar precipitation is solved.

[0030] The second vertical pipe 6 of the π-shaped pipe is a wash oil spray heat exchanger. Several tubular heat exchangers such as horizontal tube heat exchangers, coil tube heat exchangers, and vertical tube heat exchangers can be used inside the second vertical pipe 6 of the π-shaped pipe. In this embodiment, a coil tube heat exchanger is preferably used. Water flows through the coil tube heat exchanger to cool the raw coal gas. The first wash oil spray head 18 is arranged at the top of the second vertical pipe 6 of the π-shaped pipe. The light oil is washed through the first wash oil spray head 18 to recover light components (including, for example, naphthalene and phenolic light oil components). The raw coal gas, wash oil, and light components enter the low-temperature gas collector 11 together. The low-temperature environment is conducive to absorbing light components.

[0031] In addition, this device also includes a gas-liquid separator 19, a primary cooler 20, a rich oil storage tank 21, a rich oil pump 24, a rich oil heater 25, and a distillation tower 26. The inlet of the gas-liquid separator 19 is connected to the outlet of the low-temperature gas collector 11. The upper outlet of the gas-liquid separator 19 is connected upward to the primary cooler 20. The bottom outlet of the gas-liquid separator 19 is connected to the inlet of the rich oil storage tank 21. The outlet of the rich oil storage tank 21 is connected to the inlet of the rich oil pump 24. The outlet of the rich oil pump 24 is connected to the inlet at the bottom end of the rich oil heater 25. The outlet at the upper end of the rich oil heater 25 is connected to the distillation tower 26.

[0032] After the crude gas, wash oil, and light components enter the low-temperature gas collector 11 together, the rich wash oil (after the wash oil recovers light oil components such as naphthalene and phenol, it is called rich wash oil) flows below the low-temperature gas collector 11, and the crude gas flows above the low-temperature gas collector 11; the low-temperature gas collector 11 is made of stainless steel and is insulated with aluminum silicate fiber on the outside; there are 10 second wash oil spray nozzles 16 provided at the top of the low-temperature gas collector 11, which can further spray and cool down when the temperature of the crude gas is higher than 85°C; the temperature of the crude gas is further reduced to 85°C, and after being separated by the gas-liquid separator 19, it enters the primary cooler 20 and is cooled to 25°C, then it can be output for subsequent conventional processes; the 85°C rich wash oil, after being separated by the gas-liquid separator 19, enters the rich oil storage tank 21, is sent to the rich oil heater 25 by the rich oil pump 24 for heating, and then enters the distillation tower 26 to distill out naphthalene, phenol, and light oil. The oil below the distillation tower 26 is poor wash oil, and after the poor wash oil is cooled by the heat exchanger, it returns to the second vertical pipe 6 of the π-shaped pipe to continue spraying and cooling.

[0033] As a preferred embodiment, the heavy oil tank 8 has a double-layer structure. The inner layer steel pipe is made of 304, 316, 309, or 310S material, which has the effects of high temperature resistance and corrosion resistance. In this embodiment, 316 material is preferably used; the outer layer steel pipe is made of carbon steel or stainless steel. In this embodiment, stainless steel is selected; between the inner layer and the outer layer of the double-layer structure, a steel structure is used for support, and heat insulation materials, such as aluminum silicate ceramic fiber blanket, are used to greatly reduce heat dissipation loss.

[0034] The high-temperature gas collector 7 has a double-layer steel pipe structure. The inner layer steel pipe is made of 304, 316, 309, or 310S material, which has the effects of high temperature resistance and corrosion resistance. In this embodiment, 310S steel is preferably used; the outer layer steel pipe can be selected from carbon steel or stainless steel. In this embodiment, 304 stainless steel is preferably used; between the inner layer and the outer layer of the double-layer steel pipe structure, a steel structure is used for support, and aluminum silicate fiber blanket is filled to greatly reduce heat dissipation loss. For traditional gas collectors, there is only a single-layer steel plate, and the heat dissipation loss accounts for 10% of the total heat. Adopting a double-layer insulation structure is beneficial to reducing heat dissipation loss.

[0035] The high-temperature oil pump 9 and the high-temperature oil pipeline 10 are located on the right side of the high-temperature gas collector 7. The material of the high-temperature oil pipeline 10 is 316 stainless steel, its outer surface is insulated, the insulation material is selected as aluminum silicate fiber blanket, and the outside of the insulation material is wrapped with an insulation outer skin, and the insulation outer skin is made of aluminum skin for insulation.

[0036] In addition, a high-temperature valve 2 is provided on the bridge pipe 17. The material of the high-temperature valve 2 is heat-resistant steel. The high-temperature valve 2 can be a gate valve, a ball valve, a butterfly valve or a flap valve. In this embodiment, a butterfly valve is preferably used. The high-temperature valve 2 plays an isolation role. In the later stage of the production of the carbonization chamber, when the riser pipe 1 is opened for incineration, the high-temperature valve 2 is closed to prevent air from entering the high-temperature gas collector 7 and also prevent the raw gas from being released from the high-temperature gas collector 7; when coal is charged, the high-temperature valve 2 is opened, and the raw gas enters the high-temperature gas collector 7 from the riser pipe 1.

[0037] A steam spray head 3 is arranged in the bridge pipe 17. The steam spray head 3 is used for high-pressure spraying during coal charging to form a negative pressure and suck the raw gas into the high-temperature gas collector 7. The high-temperature gas collector 7 transports the high-temperature coal tar to the heat exchange boiler 22 through the connected heavy oil tank 8, high-temperature oil pump 9 and high-temperature oil pipeline 10 to produce steam.

[0038] The process flow using the above equipment is specifically as follows:

[0039] The raw gas enters the bridge pipe 17 through the riser pipe 1 of the coke oven. The bridge pipe 1 sprays coal tar to reduce the temperature of the raw gas to below 300°C, and at the same time, the heavy tar in the raw gas condenses. The raw gas and tar all enter the high-temperature gas collector 7;

[0040] The coal tar flows below the gas collector, and the raw gas flows above the gas collector. The 300°C heavy tar flows through the pipeline below the high-temperature gas collector 7, into the heavy oil tank 8, is sent to the heat exchange boiler 22 by the high-temperature oil pump 9 to produce steam for output and utilization. After the high-temperature tar is heat-exchanged, the temperature drops to below 80°C, enters the subsequent tar sedimentation tank 23 to separate out tar slag, and the tar enters the tar storage tank;

[0041] The 300°C raw gas enters the π-shaped pipe. The first vertical pipe 5 of the π-shaped pipe sprays coal tar to cool the raw gas to 230°C, and the coal tar and the raw gas exchange heat in a countercurrent manner. Due to the spraying of coal tar, which has a rinsing effect, after the coal tar precipitates, it will be washed away by the sprayed coal tar, flow downward into the high-temperature gas collector 7, mix with the tar in the high-temperature gas collector 7 before, and be pumped out together;

[0042] The raw coke oven gas continues to enter the second vertical pipe 6 of the π-shaped pipe. There are multiple groups of heat exchange pipes inside the second vertical pipe 6 of the π-shaped pipe. Water flows inside the pipes to recover the heat of the passing raw coke oven gas and generate steam for output and utilization. The second vertical pipe 6 of the π-shaped pipe sprays wash oil to recover light components, including light components such as naphthalene, phenol, and light oil. Due to heat recovery, light oil adheres to the pipe surface, and the spraying of wash oil will recover the light oil on the pipe surface to form rich wash oil, which all enters the low-temperature gas collector 11. The temperature of the raw coke oven gas further decreases to 85°C. The raw coke oven gas and light components are separated by the gas-liquid separator 19. After that, the raw coke oven gas enters the primary cooler 20 to complete the cooling to 25°C and then is output. The rich wash oil flows into the rich oil storage tank 21, enters the rich oil heater 25 through the rich oil pump 24 for heating. After the rich wash oil is heated, it enters the subsequent distillation column 26 to extract light components such as naphthalene, phenol, and light oil, and the rich wash oil becomes lean wash oil. After the lean wash oil is cooled by the heat exchanger, it returns to the spray head of the second vertical pipe 6 of the π-shaped pipe to continue spraying and cooling.

[0043] Application example 1: A coking enterprise with an annual coke production of 1.2 million tons. The hourly amount of raw coke oven gas is 78,000 Nm 3 / h, and the gas contains tar with a tar content of 65 - 120 grams / m 3 . Currently, 120 riser 1 heat exchangers have been installed in the coke oven to reduce the temperature of the raw coke oven gas from 750°C to 500°C, and the subsequent waste heat recovery equipment for the subsequent raw coke oven gas is used for cooling.

[0044] After the 500°C raw coke oven gas passes through the riser 1, it enters the bridge pipe 17. The bridge pipe 17 sprays coal tar to reduce the temperature of the raw coke oven gas to below 280°C, and at the same time, the heavy tar in the raw coke oven gas condenses. The raw coke oven gas and coal tar all enter the high-temperature gas collector 7. The coal tar flows below the high-temperature gas collector 7, and the raw coke oven gas flows above the high-temperature gas collector 7.

[0045] The raw coke oven gas passes upward through the high-temperature gas collector 7 and enters the first vertical pipe 5 of the π-shaped pipe. The second coal tar spray head 12 sprays coal tar, and the coal tar and the raw coke oven gas exchange heat countercurrently to reduce the temperature of the raw coke oven gas to 230°C. The coal tar sprayed in the bridge pipe 17 and the raw coke oven gas are combined with the coal tar sprayed in the first vertical pipe 5 of the π-shaped pipe, flow through the pipe below the high-temperature gas collector 7, and enter the heavy oil tank 8. After passing through the high-temperature oil pump 9, it is sent to the heat exchange boiler 22 to produce steam with a steam flow rate of 15 tons / h. After the high-temperature coal tar exchanges heat, the temperature drops to below 80°C, enters the tar precipitation tank 23 to separate out tar slag, and then enters the tar storage tank.

[0046] The raw coke oven gas enters the second vertical pipe 6 of the π-shaped pipe, and is sprayed with wash oil by the first wash oil spray head 18 to recover light components. Then they enter the low-temperature gas collector 11 together. The temperature of the raw coke oven gas drops to 85°C, and after being separated by the gas-liquid separator 19, the raw coke oven gas enters the primary cooler 20 and is cooled to 25°C under the action of circulating cooling water. The second vertical pipe 6 of the π-shaped pipe uses a tube heat exchanger with multiple groups of heat exchange pipes inside. Water flows inside the pipes to recover the heat of the raw coke oven gas and produce 3 tons of steam per hour. Due to heat recovery, light oil adheres to the surfaces of multiple groups of heat exchange pipes, and the light oil on the surfaces of multiple groups of heat exchange pipes can be recovered by the showering of wash oil. The rich wash oil at 85°C enters the rich oil storage tank 21, is sent to the rich oil heater 25 by the rich oil pump 24 for heating, and then enters the distillation column 26 to distill out naphthalene, phenol, and light oil. The oil below the distillation column 26 is lean oil. After the lean oil is cooled down by the heat exchanger, it returns to the π-shaped pipe for continuous showering and cooling.

[0047] This example can recover the heat energy of the raw coke oven gas below 500°C, reduce the load of the subsequent primary cooler 20, and produce steam for use, with a total of 18 tons per hour. Each ton of steam is 150 yuan, and the economic benefit per hour is 2700 yuan. Since this project operates continuously for 365 days, the annual economic benefit is 23.652 million yuan from steam revenue.

[0048] Application Example 2: A coking enterprise with an annual output of 2.04 million tons of coke. The hourly volume of raw coke oven gas is 132,600 Nm 3 / h, and the gas contains tar with a tar content of 65 - 120 grams / m 3 . Currently, 144 riser 1 heat exchangers have been installed in the coke oven to reduce the temperature of the raw coke oven gas from 750°C to 500°C, and the subsequent waste heat recovery equipment of the riser 1 is used for cooling.

[0049] After the 500°C raw coke oven gas passes through the riser 1, it enters the bridge pipe 17. The bridge pipe 17 sprays coal tar to reduce the temperature of the raw coke oven gas below 300°C, and at the same time, the heavy tar in the raw coke oven gas condenses. The raw coke oven gas and tar all enter the high-temperature gas collector 7. The coal tar flows below the high-temperature gas collector 7, and the raw coke oven gas flows above the high-temperature gas collector 7. The raw coke oven gas enters the first vertical pipe 5 of the π-shaped pipe and is sprayed with coal tar, and the temperature of the raw coke oven gas drops to 230°C. The tar sprayed by the bridge pipe 17 and the tar sprayed by the raw coke oven gas entering the first vertical pipe 5 of the π-shaped pipe are combined and flow through the pipe below the high-temperature gas collector 7 into the heavy oil tank 8, and then are sent to the heat exchange boiler 22 by the high-temperature oil pump 9 to produce steam with a steam flow of 25 tons per hour. After the high-temperature tar exchanges heat, the temperature drops below 80°C, enters the subsequent tar sedimentation tank 23 to separate out tar slag, and then enters the tar storage tank.

[0050] The raw gas enters the second vertical pipe of the π-shaped pipe and is sprayed with wash oil by the first wash oil spray head 18 to recover light components, including light components such as naphthalene, phenol, and light oil. The temperature of the raw gas is reduced to 85 °C and then enters the primary cooler 20. The second vertical pipe is a tubular heat exchanger with multiple groups of heat exchange pipes inside. Water flows inside the pipes to recover the heat of the raw gas and produce 5 tons / hour of steam. Due to heat recovery, light oil adheres to the surface of the pipes, and the spraying of wash oil will recover the light tar on the pipe surface. The wash oil also exchanges heat with the raw gas. After being heated, it enters the rich oil storage tank 21 and then enters the subsequent chemical process to extract light components such as naphthalene, phenol, and light oil. After the wash oil sprays and absorbs naphthalene oil and phenol oil from the raw gas, it becomes rich wash oil. The rich wash oil is heated by the rich oil heater 25 and then goes to the distillation tower 26. After recovering light components such as naphthalene and phenol in sections, it becomes lean wash oil. After the lean wash oil is cooled, it enters the wash oil storage tank (not shown in the figure). Finally, the lean wash oil returns to the spray tower of the π-shaped pipe to continue to be used.

[0051] In the heat exchanger of the second vertical pipe 6 of the π-shaped pipe, horizontal heat exchange pipes are used. Water flows inside the pipes to cool the gas and produce 3 tons / hour of saturated steam with a saturated steam pressure of 0.6 MPa.

[0052] This example can recover the heat energy of the raw gas below 500 °C, reduce the load of the subsequent primary cooler 20, and produce steam for use, with a total of 30 tons / hour. Each ton of steam costs 150 yuan, and the economic benefit per hour is 4,500 yuan. Since this project operates continuously for 365 days, the direct economic income, the annual economic benefit is 39.42 million yuan in steam income.

Claims

1. A rising pipe subsequent raw gas waste heat recovery device, characterized in that: It includes a bridge pipe, a high-temperature gas collecting pipe, a low-temperature gas collecting pipe, a π-shaped pipe, a second coal tar spray head, a first coal tar spray head, a heavy oil tank, a high-temperature oil pump, a high-temperature oil pipeline, a heat exchange boiler, and a tar sedimentation tank; one end of the bridge pipe is connected to the riser pipe, the other end of the bridge pipe is connected to the inlet of the high-temperature gas collecting pipe, both ends of the π-shaped pipe are respectively connected to the top of the high-temperature gas collecting pipe and the top of the low-temperature gas collecting pipe, and it is arranged above the high-temperature gas collecting pipe and the low-temperature gas collecting pipe; the first coal tar spray head is arranged in the bridge pipe, the second coal tar spray head is arranged in the π-shaped pipe, the bottom outlet of the high-temperature gas collecting pipe is connected to the inlet of the heavy oil tank, the outlet of the heavy oil tank is connected to the inlet of the high-temperature oil pump, the outlet of the high-temperature oil pump is connected to the inlet of the heat exchange boiler through the high-temperature oil pipeline, and the bottom outlet of the heat exchange boiler is connected to the inlet of the tar sedimentation tank.

2. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that The π-shaped pipe includes a π-shaped pipe first vertical pipe, a π-shaped pipe horizontal pipe, and a π-shaped pipe second vertical pipe connected in sequence. The π-shaped pipe is in an overall π-shaped structure. The π-shaped pipe horizontal pipe is located above the π-shaped pipe first vertical pipe and the π-shaped pipe second vertical pipe. The π-shaped pipe horizontal pipe is respectively connected to the π-shaped pipe first vertical pipe and the π-shaped pipe second vertical pipe through π-shaped pipe elbows; the bottom end of the π-shaped pipe first vertical pipe is connected to the top of the high-temperature gas collecting pipe, and the bottom end of the π-shaped pipe second vertical pipe is connected to the top of the low-temperature gas collecting pipe.

3. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that, The π-shaped pipe first vertical pipe is a heavy oil spray vertical pipe, and the second coal tar spray head is arranged at the top of the π-shaped pipe first vertical pipe; the π-shaped pipe second vertical pipe is a wash oil spray heat exchanger, and a first wash oil spray head is arranged at the top of the π-shaped pipe second vertical pipe; a heat exchanger is arranged inside the π-shaped pipe second vertical pipe. The π-shaped pipe is a composite steel pipe, the inner surface is a non-stick coating, and the outside of the π-shaped pipe is a heat insulation layer.

4. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that, It also includes a gas-liquid separator, a primary cooler, a rich oil storage tank, a rich oil pump, a rich oil heater, and a distillation tower; the inlet of the gas-liquid separator is connected to the outlet of the low-temperature gas collecting pipe, the upper outlet of the gas-liquid separator is connected upward to the primary cooler; the bottom outlet of the gas-liquid separator is connected to the inlet of the rich oil storage tank, the outlet of the rich oil storage tank is connected to the inlet of the rich oil pump, the outlet of the rich oil pump is connected to the inlet at the bottom end of the rich oil heater, and the outlet at the upper end of the rich oil heater is connected to the distillation tower.

5. The subsequent waste gas heat recovery device for the riser pipe according to claim 1, characterized in that, The material of the high-temperature oil pipeline is stainless steel, and a heat insulation material is provided on its outer surface. The heat insulation material is made of aluminum silicate fiber blanket, and the outside of the heat insulation material is wrapped with a heat insulation outer skin, and the heat insulation outer skin is made of aluminum skin for heat insulation.

6. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that, A high-temperature valve is arranged at the first end of the bridge pipe, and the material of the high-temperature valve is heat-resistant steel; a steam spray head is arranged in the bridge pipe.

7. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that, A plurality of second wash oil spray heads are arranged on the top of the low-temperature gas collecting pipe. The low-temperature gas collecting pipe is made of stainless steel, and the outside is heat-insulated with aluminum silicate fiber or alumina fiber.

8. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that, The bridge pipe is an arc-shaped elbow pipe, and the high-temperature gas collecting pipe is arranged below the bridge pipe.

9. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 1, characterized in that, Both the high-temperature gas collecting pipe and the heavy oil tank adopt a double-layer steel pipe structure. The material of the inner-layer steel pipe is 304, 316, 309, or 310S material, and the outer-layer steel pipe is made of carbon steel or stainless steel.

10. The subsequent waste gas heat recovery equipment for the riser pipe according to claim 9, characterized in that, Between the inner layer and the outer layer of the double-layer steel pipe structure, a steel structure is used for support, and aluminum silicate ceramic fiber blanket is filled.

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