Waste heat recovery device for coal gas elution benzene heating

Abstract

The utility model discloses a waste heat recovery device for coal gas benzene elution heating, which comprises a benzene washing tower, an oil gas heat exchanger, an oil-oil heat exchanger, a tubular heating furnace and a benzene removal tower which are sequentially connected, a flue gas heat exchanger is arranged between the oil-oil heat exchanger and the tubular heating furnace, and a plurality of vertical cylinders are concentrically arranged in the flue gas heat exchanger. The interior of the flue gas heat exchanger is divided into flue gas spaces and rich oil spaces which are alternately arranged by the plurality of vertical cylinders, the oil inlet pipe is communicated with a rich oil outlet of the oil-oil heat exchanger, a jacket is arranged on the outer wall of the debenzolization tower, a flue gas outlet of the tubular heating furnace is communicated with a flue gas inlet of the jacket, and a flue gas outlet of the jacket is communicated with the flue gas inlet pipe. In conclusion, the waste heat recovery device has the advantages of being less in waste heat waste, high in recovery efficiency and capable of reducing energy consumption.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat recovery, in particular to a waste heat recovery device used for heating coal gas eluting benzene. Background Art

[0002] In the process of heating and dry distilling coal in the carbonization chamber to produce coke, a large amount of coke oven gas will be produced, and its main components include hydrogen, methane, tar, benzene, naphthalene, ammonia, sulfur, etc. With the improvement of environmental protection requirements, it is necessary to purify the coke oven gas produced by the coke oven, remove the impurities such as sulfur, ammonia, tar, naphthalene, and recover the tar, benzene, naphthalene and other substances as chemical raw materials. The existing coke oven gas purification process generally includes ammonia water cooling, tar removal, desulfurization, deamination, final cooling and benzene washing, etc., wherein the benzene washing process is to remove and recycle the benzene in the coke oven gas, and the coal gas is washed with benzene by spraying washing oil through the benzene washing tower. After washing benzene, the washing oil becomes rich oil due to absorbing a large amount of benzene hydrocarbons or other organic compounds in the coal gas. The rich oil becomes lean oil after passing through the benzene washing tower to remove benzene, and the lean oil returns to the benzene washing tower to continue to be used as washing oil for washing benzene. Such a cycle ensures the smooth purification of coking coal gas.

[0003] Before the rich oil is sent to the debenzene tower for crude benzene distillation, it needs to be heated to increase its temperature. At present, tubular heating furnaces are mostly used to directly heat the rich oil with flames. The exhaust flue gas temperature is as high as 400°C, and the thermal efficiency is only 70-80%. The heat load and heat utilization rate need to be improved, resulting in a large amount of waste heat being wasted in the process of gas stripping benzene, and causing serious thermal pollution to the environment; secondly, during the operation of the debenzene tower, a large amount of heat will escape from the tower wall, which will not only cause the temperature inside the tower to drop, but also cause heat waste; in addition, although some companies have recovered the flue gas waste heat of the tubular heating furnace, there is still a problem of low waste heat recovery rate. Therefore, it is an objective need to develop a waste heat recovery device for heating gas stripping benzene with less waste heat waste, high recovery efficiency, and reduced energy consumption. Utility Model Content

[0004] The utility model aims to provide a waste heat recovery device for heating benzene stripping by coal gas, which has less waste heat, high recovery efficiency and can reduce energy consumption.

[0005] The purpose of the utility model is achieved in this way, including a benzene washing tower, an oil-gas heat exchanger, an oil-oil heat exchanger, a tubular heating furnace and a benzene removal tower which are connected in sequence, a flue gas heat exchanger is arranged between the oil-oil heat exchanger and the tubular heating furnace, a plurality of vertical cylinders are concentrically arranged inside the flue gas heat exchanger, the plurality of vertical cylinders divide the interior of the flue gas heat exchanger into a plurality of annular spaces, the plurality of annular spaces are alternately arranged from the outside to the inside, a smoke inlet pipe is arranged on the top of each smoke space, a smoke outlet pipe is arranged on the bottom of each smoke space, an oil inlet pipe is arranged on the bottom of each oil-rich space, an oil outlet pipe is arranged on the top of each oil-rich space, the oil inlet pipe is connected with the oil-rich outlet of the oil-oil heat exchanger, a jacket is arranged on the outer wall of the debenzene tower, the smoke outlet of the tubular heating furnace is connected with the smoke inlet of the jacket, and the smoke outlet of the jacket is connected with the smoke inlet pipe.

[0006] Furthermore, the smoke inlet pipe is tangentially connected to the side wall of the smoke space.

[0007] Furthermore, each oil-rich space is provided with a plurality of outer heat-conducting rings and inner heat-conducting rings which are arranged alternately up and down.

[0008] Furthermore, a spiral guide plate is arranged in the jacket.

[0009] Furthermore, a hot water tank and a steam generator are sequentially arranged on the smoke outlet pipe, and the steam outlet of the steam generator is connected to the steam inlet of the debenzene tower.

[0010] Furthermore, the benzene steam outlet of the oil-gas heat exchanger is connected to a water cooler, and the hot water outlet of the water cooler is connected to the water inlet of the steam generator.

[0011] The utility model is used for recycling waste heat in the process of heating of coke oven gas during benzene stripping. During operation, the benzene stripping tower discharges rich oil into the oil-gas heat exchanger, and the benzene stripping tower discharges benzene vapor into the oil-gas heat exchanger. The two complete heat exchange in the oil-gas heat exchanger, and the waste heat in the benzene vapor is used to heat the rich oil for the first time. Subsequently, the rich oil is discharged to the oil-oil heat exchanger, and the benzene stripping tower discharges lean oil into the oil-oil heat exchanger. The two complete heat exchange in the oil-oil heat exchanger, and the waste heat in the lean oil is used to heat the rich oil for the second time. The heated rich oil is sent to the flue gas heat exchanger, and the waste heat of the flue gas from the tubular heating furnace is used to heat the rich oil for the third time. The heated rich oil is sent to the tubular heating furnace for the final heating. After the rich oil temperature reaches the required temperature, it is sent to the debenzene tower for distillation. The crude benzene and oil are separated by the principle of different boiling points to obtain benzene vapor and high-temperature lean oil. The high-temperature flue gas discharged from the tubular heating furnace is first sent to the jacket of the debenzene tower to insulate and heat the inside of the debenzene tower, and then sent to the flue gas heat exchanger to heat the rich oil. In the above process, in order to solve the problem of waste heat in the heating process of benzene stripping, on the one hand, the waste heat in the benzene vapor and high-temperature lean oil discharged from the benzene stripping tower is recycled and utilized, and on the other hand, the waste heat in the high-temperature flue gas discharged from the tubular heating furnace is recycled and utilized. The rich oil discharged from the benzene stripping tower is heated by using these waste heats, which improves the distillation efficiency of the rich oil, greatly reduces the waste heat waste in the heating process of coal gas benzene stripping, and also reduces the energy consumption of rich oil heating; secondly, the utility model optimizes the structure of the flue gas heat exchanger, and alternately arranges a plurality of annular flue gas spaces and oil-rich spaces inside it. The rich oil in the oil-rich space can be heated by the two flue gas spaces on both sides thereof at the same time, which improves the heating efficiency and heating effect of the rich oil, and the recovery efficiency of the flue gas waste heat is high, and the waste of the flue gas waste heat is less. In summary, the utility model has the advantages of less waste heat, high recovery efficiency, and reduced energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0013] Figure 2 It is a schematic diagram of the overall structure of the flue gas heat exchanger 6 in the utility model;

[0014] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of AA;

[0015] In the figure: 1-benzene washing tower, 2-oil-gas heat exchanger, 3-oil-oil heat exchanger, 4-tubular heating furnace, 5-benzene removal tower, 6-flue gas heat exchanger, 7-vertical cylinder, 8-flue gas space, 9-oil-rich space, 10-flue gas inlet pipe, 11-flue gas outlet pipe, 12-oil inlet pipe, 13-oil outlet pipe, 14-jacket, 15-external heat conduction ring, 16-inner heat conduction ring, 17-spiral guide plate, 18-hot water tank, 19-steam generator, 20-water cooler. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or improvements made based on the present invention belong to the protection scope of the present invention.

[0017] like Figures 1 to 3 As shown, the utility model includes a benzene washing tower 1, an oil-gas heat exchanger 2, an oil-oil heat exchanger 3, a tubular heating furnace 4 and a benzene removal tower 5 which are connected in sequence. The above equipments are all prior art. The benzene washing tower 1 is used to spray coke oven gas with lean oil to absorb crude benzene in the coke oven gas to obtain rich oil rich in crude benzene. The oil-gas heat exchanger 2 is used for heat exchange between benzene vapor and rich oil to increase the temperature of the rich oil to 60-70°C. The oil-oil heat exchanger 3 is used for heat exchange between rich oil and lean oil discharged from the benzene removal tower 5 to increase the temperature of the rich oil to 120-130°C. The tubular heating furnace 4 is used to burn coal gas or other fuel gas to directly heat the rich oil to increase the temperature of the rich oil to 180°C. The benzene removal tower 5 is used for distillation of the rich oil, and rich oil and steam are introduced therein. The principle of different boiling points of oil and crude benzene is used to discharge benzene vapor and obtain lean oil at the same time. After the lean oil is cooled, it is sent to the benzene washing tower 1 again. The benzene vapor is condensed to obtain crude benzene. A flue gas heat exchanger 6 is arranged between 3 and the tubular heating furnace 4. The flue gas heat exchanger 6 uses the flue gas discharged from the tubular heating furnace 4 to heat the rich oil and increase the temperature of the rich oil to 150°C. A plurality of vertical cylinders 7 are concentrically arranged inside the flue gas heat exchanger 6. The plurality of vertical cylinders 7 divide the interior of the flue gas heat exchanger 6 into a plurality of annular spaces. The plurality of annular spaces are alternately arranged from the outside to the inside, and are flue gas spaces 8 and oil-rich spaces 9. A smoke inlet pipe 10 is arranged at the top of each flue gas space 8, a smoke outlet pipe 11 is arranged at the bottom of each flue gas space 8, an oil inlet pipe 12 is arranged at the bottom of each oil-rich space 9, and an oil outlet pipe 13 is arranged at the top of each oil-rich space 9. The oil inlet pipe 12 is connected to the oil-rich outlet of the oil-to-oil heat exchanger 3. A jacket 14 is arranged on the outer wall of the debenzene tower 5. The flue gas outlet of the tubular heating furnace 4 is connected to the flue gas inlet of the jacket 14, and the flue gas outlet of the jacket 14 is connected to the smoke inlet pipe 10.

[0018] The utility model is used for recycling waste heat in the process of heating of coke oven gas for stripping benzene. During operation, the stripping benzene tower 1 discharges rich oil into the oil-gas heat exchanger 2, and the stripping benzene tower 5 discharges benzene vapor into the oil-gas heat exchanger 2. The two complete heat exchange in the oil-gas heat exchanger 2, and the waste heat in the benzene vapor is used to heat the rich oil for the first time. Subsequently, the rich oil is discharged to the oil-oil heat exchanger 3, and the stripping benzene tower 5 discharges lean oil into the oil-oil heat exchanger 3. The two complete heat exchange in the oil-oil heat exchanger 3, and the waste heat in the lean oil is used to heat the rich oil for the second time. After two heatings, the rich oil is stripped to the oil-oil heat exchanger 3, and the lean oil is stripped to the oil-oil heat exchanger 3. The heated rich oil is sent to the flue gas heat exchanger 6, and the waste heat of the flue gas of the tubular heating furnace 4 is used to heat the rich oil for the third time. The heated rich oil is sent to the tubular heating furnace 4 for the final heating. After the rich oil temperature reaches the required temperature, it is sent to the debenzene tower 5 for distillation. The crude benzene and oil are separated by the principle of different boiling points to obtain benzene vapor and high-temperature lean oil. The high-temperature flue gas discharged from the tubular heating furnace 4 is first sent to the jacket 14 of the debenzene tower 5 to insulate and heat the inside of the debenzene tower 5, and then sent to the flue gas heat exchanger 6 to heat the rich oil. In the above process, in order to solve the problem of waste heat in the heating process of benzene stripping 5, on the one hand, the waste heat in the benzene vapor and high-temperature lean oil discharged from the debenzene tower 5 is recovered and utilized, and on the other hand, the waste heat in the high-temperature flue gas discharged from the tubular heating furnace 4 is recovered and utilized, and the rich oil discharged from the benzene stripping tower 1 is heated by using these waste heats, which improves the distillation efficiency of the rich oil, greatly reduces the waste heat waste in the heating process of coal gas debenzene, and also reduces the energy consumption of rich oil heating; secondly, the utility model optimizes the structure of the flue gas heat exchanger 6, and alternately arranges a plurality of annular flue gas spaces 8 and oil-rich spaces 9 therein, the rich oil in the oil-rich space 9 can be heated by the two flue gas spaces 8 on both sides thereof at the same time, and the heat dissipated by the flue gas can be fully absorbed by the rich oil, thereby improving the heating efficiency and heating effect of the rich oil, and the recovery efficiency of the flue gas waste heat is high, and the waste of the flue gas waste heat is less.

[0019] The smoke inlet pipe 10 is tangentially connected to the side wall of the smoke space 8. When the smoke enters the smoke space 8 from the smoke inlet pipe 10, it will rotate and flow along the smoke space 8, thereby increasing the flow distance of the smoke, extending the flow time of the smoke in the smoke space 8, improving the heat exchange efficiency between the smoke and the rich oil, reducing the heat loss in the smoke, and allowing the rich oil to be better heated.

[0020] Each oil-rich space 9 is provided with a plurality of outer heat-conducting rings 15 and inner heat-conducting rings 16 which are arranged in an upper and lower staggered manner. The outer heat-conducting rings 15 and the inner heat-conducting rings 16 are existing structures, which are used to deflect the rich oil, so that the rich oil flows in an S shape, thereby increasing the flow distance of the rich oil, prolonging the contact and heat exchange time between the rich oil and the flue gas, and improving the heat exchange efficiency between the flue gas and the rich oil; secondly, the outer heat-conducting rings 15 and the inner heat-conducting rings 16 also play a role of heat conduction, which can transfer the heat of the flue gas, expand the heat dissipation area of ​​the flue gas, and thereby improve the heat exchange efficiency between the flue gas and the rich oil.

[0021] The flue gas flows in the jacket 14. During actual operation, it is found that there is a problem of flue gas retention or poor circulation in local areas inside the jacket 14, which will reduce the insulation and heating effect of the flue gas on the inside of the debenzene tower 5. To prevent this problem, a spiral guide plate 17 is provided in the jacket 14. The spiral guide plate 17 can make the flue gas flow in a spiral in the jacket 14, thereby eliminating the dead zone of flue gas retention and promoting the smooth flow of flue gas.

[0022] A hot water tank 18 and a steam generator 19 are sequentially arranged on the smoke outlet pipe 11, and the steam outlet of the steam generator 19 is connected to the steam inlet of the debenzene tower 5. The hot water tank 18 and the steam generator 19 are both existing equipment. The hot water tank 18 is used to absorb the waste heat in the flue gas with cold water, reduce the flue gas temperature, reduce the heat loss, and obtain hot water at the same time. The hot water is transported to the steam generator 19, which can improve the efficiency of the steam generator 19 in generating steam.

[0023] The benzene vapor outlet of the oil-gas heat exchanger 2 is connected to a water cooler 20, and the hot water outlet of the water cooler 20 is connected to the water inlet of the steam generator 19. The water cooler 20 is an existing device, which is used to absorb the waste heat in the benzene vapor with cold water. On the one hand, it further reduces the stability of the benzene vapor and promotes its condensation. On the other hand, the cold water absorbs the heat to obtain hot water, and the hot water is transported to the steam generator 19, which can improve the efficiency of the steam generator 19 in generating steam.

Claims

1. A waste heat recovery device for heating benzene stripping from coal gas, comprising a benzene stripping tower (1), an oil-gas heat exchanger (2), an oil-oil heat exchanger (3), a tubular heating furnace (4) and a benzene stripping tower (5) connected in sequence, characterized in that A flue gas heat exchanger (6) is arranged between the oil-oil heat exchanger (3) and the tubular heating furnace (4), and a plurality of vertical cylinders (7) are concentrically arranged inside the flue gas heat exchanger (6). The plurality of vertical cylinders (7) divide the interior of the flue gas heat exchanger (6) into a plurality of annular spaces. The plurality of annular spaces are alternately arranged flue gas spaces (8) and oil-rich spaces (9) from the outside to the inside. A smoke inlet pipe (10) is arranged at the top of each flue gas space (8), and a bottom of each flue gas space (8) is provided. A smoke outlet pipe (11) is provided at each of the oil-rich spaces (9), an oil inlet pipe (12) is provided at the bottom of each oil-rich space (9), an oil outlet pipe (13) is provided at the top of each oil-rich space (9), the oil inlet pipe (12) is connected to the oil-rich outlet of the oil-oil heat exchanger (3), a jacket (14) is provided on the outer wall of the debenzene tower (5), the smoke outlet of the tubular heating furnace (4) is connected to the smoke inlet of the jacket (14), and the smoke outlet of the jacket (14) is connected to the smoke inlet pipe (10).

2. A waste heat recovery device for heating benzene by eluting coal gas according to claim 1, characterized in that The smoke inlet pipe (10) is tangentially connected to the side wall of the smoke space (8).

3. A waste heat recovery device for heating benzene by eluting coal gas according to claim 1, characterized in that Each oil-rich space (9) is provided with a plurality of outer heat-conducting rings (15) and inner heat-conducting rings (16) which are arranged in an up-and-down staggered manner.

4. A waste heat recovery device for heating benzene by gas stripping according to claim 1, characterized in that A spiral guide plate (17) is arranged in the jacket (14).

5. A waste heat recovery device for heating benzene by eluting coal gas according to claim 1, characterized in that A hot water tank (18) and a steam generator (19) are sequentially arranged on the smoke outlet pipe (11), and a steam outlet of the steam generator (19) is connected to a steam inlet of the debenzene tower (5).

6. A waste heat recovery device for heating benzene by eluting coal gas according to claim 5, characterized in that The benzene vapor outlet of the oil-gas heat exchanger (2) is connected to a water cooler (20), and the hot water outlet of the water cooler (20) is connected to the water inlet of the steam generator (19).

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