CN108151547B - Equipment and method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation - Google Patents
Equipment and method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation Download PDFInfo
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- CN108151547B CN108151547B CN201810094390.1A CN201810094390A CN108151547B CN 108151547 B CN108151547 B CN 108151547B CN 201810094390 A CN201810094390 A CN 201810094390A CN 108151547 B CN108151547 B CN 108151547B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/004—Systems for reclaiming waste heat
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B27/00—Arrangements for withdrawal of the distillation gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Abstract
The invention discloses equipment and a method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation, which comprise a riser heat exchanger, an ammonia distillation reboiler, a negative pressure ammonia distillation tower, a benzene removal reboiler, a negative pressure benzene removal tower, a heat medium tank and a heat lean oil tank, wherein a heat medium outlet of the riser heat exchanger is connected with the ammonia distillation reboiler, a heat medium outlet is connected with the benzene removal reboiler, the benzene removal reboiler is connected with the heat medium outlet, a pipeline is connected with the negative pressure benzene removal tower, the benzene removal reboiler is connected with the heat lean oil tank, the benzene removal reboiler is connected with the heat medium tank, the ammonia distillation reboiler is connected with the heat lean oil tank and the heat medium tank, the ammonia distillation reboiler is connected with the negative pressure ammonia distillation tower, and the negative pressure ammonia distillation tower is connected with the ammonia distillation reboiler; the negative pressure debenzolization tower is connected with a hot lean oil tank, the hot lean oil tank is connected with a hot lean oil circulating pump, the hot lean oil circulating pump is connected with a debenzolization reboiler and a rising pipe heat exchanger, the other pipeline is connected with a heat medium pump, and the heat medium pump is connected with the heat medium tank.
Description
Technical Field
The invention relates to the technical field of waste heat recovery and utilization of raw coke oven gas of a coke oven riser, in particular to a method and equipment for benzene removal and ammonia distillation by adopting hot fluid to recover waste heat of raw coke oven gas.
Background
The average temperature of raw gas of a coke oven riser is about 700 ℃, the heat brought out is equivalent to about 35% of the consumed coking heat, and in order to facilitate purification and treatment of the subsequent procedures, the common practice in the prior art is as follows: spraying circulating ammonia water to directly contact with the raw gas, and enabling the raw gas to be rapidly cooled to 80-83 ℃ by means of massive vaporization of the circulating ammonia water, and then sending the raw gas to a subsequent gas refining system. The heat of the raw gas is converted into useless low-temperature water vapor (82 ℃) in the process, a large amount of circulating water and low-temperature water are consumed for cooling the raw gas, and the production process is obvious and has high energy consumption and low efficiency.
The waste heat recovery of raw gas of the rising pipe of the coke oven is utilized, and a great deal of research is made domestically and abroad, and the current technical method is that the waste heat recovery of the rising pipe generates low-pressure steam and the low-pressure steam is merged into a steam pipe network (comprising various modes of directly adding water into raw gas to generate low-pressure steam, adopting heat conduction oil to recover waste heat, and then exchanging heat through a reboiler to generate steam, and the like). However, a large amount of waste water is generated when steam is used as a heating medium for recycling coking products, so that the difficulty and cost of waste water treatment of a coking plant are increased, low-pressure steam cannot be used for a coking de-benzene regeneration process, and the steam is used as a heating medium and is a development system for the coking plant, so that the low-pressure steam is an inefficient heat supply energy source.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides equipment for recycling waste heat of raw coke oven gas for debenzolization and ammonia distillation; the invention utilizes thermal fluid (including thermal lean oil, molten salt and the like) as a heating medium for recovering waste heat of raw gas, is also a heating medium for the technological processes of debenzolization, ammonia distillation and the like, and provides conveying energy through a circulating pump to form a closed-circuit circulating system for heat taking and heat supplying.
The invention also provides a method for recycling waste heat of raw coke oven gas for debenzolization and ammonia distillation.
The technical scheme for solving the technical problems is as follows:
the equipment for removing benzene and distilling ammonia by recovering waste heat of raw gas of a coke oven comprises a rising pipe heat exchanger, an ammonia distilling reboiler, a negative pressure ammonia distilling tower, a benzene removing reboiler, a negative pressure benzene removing tower, a heat medium tank and a heat lean oil tank, wherein the rising pipe heat exchanger comprises an outer heat medium inlet and outlet pipeline and a middle raw gas inlet and outlet pipeline, the heat medium inlet of the heat medium inlet and outlet pipeline is arranged at the upper part and the lower part, the heat medium inlet and the heat medium outlet are respectively connected with an external pipeline through respective flanges, a heat medium is arranged in the heat medium inlet and outlet pipeline, the raw gas inlet and outlet pipeline comprises a raw gas inlet at the lower part, a raw gas outlet at the upper part is connected with an outlet pipeline of a coke oven through a flange, the raw gas outlet is connected with an upper inlet of the ammonia distilling reboiler through a flange, the heat medium outlet is connected with the upper part of the bridge pipe through a pipeline and a valve I, the top outlet of the benzene removing reboiler is simultaneously connected with a heat medium outlet through a pipeline and a valve II, a valve IV and a heat medium outlet are connected with the heat medium outlet at the lower part through a valve I, the reboiler pipeline between the valve II and a valve III and a valve II, the reboiler pipeline is also connected with the bottom of the heat lean oil tower through a valve III and a valve II, the bottom is also connected with the bottom of the heat lean oil tower through a pipeline and a valve III-containing the bottom pipeline, the heat medium outlet is connected with the bottom of the heat tower through a pipeline, and the bottom of the heat tower is connected with the heat tower through a bottom pipeline, and the heat tower bottom is connected with the heat inlet through a bottom pipeline, and the heat tower bottom is connected with the heat tower bottom a bottom heater and the heat tower and the heat heater, the waste water outlet at the bottom of the negative pressure ammonia still is connected with the inlet at the bottom of the ammonia still reboiler through a pipeline; the outlet of the lower part of the negative pressure debenzolization tower is connected with the inlet of the lower part of the heat lean oil tank through a pipeline, the outlet of the heat lean oil tank is connected with the inlet of the heat lean oil circulating pump, the outlet of the heat lean oil circulating pump is connected with the bottom of the debenzolization reboiler through one pipeline and a valve eight, the outlet of the heat lean oil circulating pump is connected with the heat medium inlet of the rising pipe heat exchanger through a valve nine and another pipeline, the other pipeline is simultaneously connected with the heat medium pump through a valve ten, the inlet of the heat medium pump is connected with the outlet of the heat medium tank, a heating device is arranged in the heat medium tank, a raw gas inlet and outlet flange is connected with the coke oven and the bridge pipe, and the heat medium inlet and outlet flange is connected with the external pipeline.
The rising pipe heat exchanger comprises raw gas inlet and outlet flanges, an inner cylinder, a middle cylinder and an outer cylinder at two ends, and a heat medium inlet and outlet flange which is respectively connected with a heat medium inlet and a heat medium outlet of a heat medium inlet and outlet pipeline; a heat medium inlet and outlet pipeline is formed between the inner cylinder body and the middle cylinder body, the inner cavity of the inner cylinder body is a raw gas inlet and outlet pipeline, and the raw gas inlet and outlet flange is respectively connected with the ends of the inner cylinder body, the middle cylinder body and the outer cylinder body.
The inner wall of the inner cylinder body is provided with an inorganic polymer coating which is smooth, good in radiation heat transfer and thermal stability and capable of preventing tar from hanging on the wall.
The inner cylinder body is connected with the middle cylinder body through the spiral fins of the middle heat exchange layer, and an outer layer of heat resistance material is arranged between the middle cylinder body and the outer cylinder body.
A deformation compensator is arranged between the middle cylinder body and the outer cylinder body, and is an annular groove which is arranged on the middle cylinder body and protrudes towards one side of the outer cylinder body.
The outer cylinder body is provided with an outer cylinder wall temperature real-time monitor which is connected with the controller.
The heat medium adopts heat lean oil, molten salt or heat conducting oil.
The heating device adopts an electric heating device.
A method for recovering waste heat of raw coke oven gas used for a device for debenzolization and ammonia distillation, wherein the waste heat of the raw coke oven gas in a rising pipe is recovered through heat conduction oil or molten salt in a starting state of a negative pressure debenzolization tower, and the method comprises the following steps:
1) Opening the first valve, the third valve, the fourth valve, the seventh valve, the eighth valve and the tenth valve, and closing the second valve, the fifth valve, the sixth valve and the ninth valve;
2) Heating the heat medium in the heat medium tank to 240-260 ℃ by an electric heating device in the heat medium tank;
3) Pumping out the heat medium in the heat medium tank by using a heat medium pump, sending the heat medium to a riser heat exchanger to exchange heat with the high-temperature raw gas at 750-850 ℃, and raising the temperature of the heat medium to 260-280 ℃;
4) One path is sent to a benzene removal reboiler to exchange heat with the hot lean oil from the hot lean oil tank, the hot lean oil is heated to 225-235 ℃ and sent to a negative pressure benzene removal tower to provide heat for benzene removal, and then the heat is returned to the hot lean oil tank;
5) The other path of the waste water is sent to a negative pressure ammonia distillation reboiler to heat the ammonia distillation waste water at the bottom of the negative pressure ammonia distillation tower to generate steam which is sent back to the negative pressure ammonia distillation tower to distill ammonia;
6) The temperature of the heat medium which is discharged after the heat exchange of the negative pressure benzene steaming reboiler and the negative pressure ammonia steaming reboiler is between 246 and 260 ℃, the heat medium enters a heat medium tank, and the heat medium is pumped out by a heat medium pump to a riser heat exchanger to exchange heat with high-temperature raw gas again to complete a cycle, so that the cycle is reciprocated;
7) Normal operation state of system
When the system is started to operate until a sufficient amount of hot lean oil with the temperature of 225-235 ℃ is accumulated, the hot lean oil is used as a circulating heat medium for system operation, and the method specifically comprises the following steps of:
(1) Stopping the operation of the heat medium pump, closing and opening the valve I, the valve III, the valve IV, the valve seven, the valve eight and the valve ten, and opening the valve II, the valve five, the valve six and the valve nine;
(2) Starting a hot lean oil circulating pump to pump out hot lean oil with the temperature of 225-235 ℃ in a hot lean oil groove, sending the hot lean oil to a riser heat exchanger to exchange heat with high-temperature raw coke oven gas with the temperature of 750-850 ℃, and raising the temperature to 240-250 ℃;
(3) One path of the hot lean oil heated by the high-temperature raw gas is directly sent to a negative pressure debenzolization tower kettle, oil gas is produced by flash evaporation under a negative pressure state and is used as a heat source for negative pressure debenzolization, and the temperature of the hot lean oil after flash evaporation is 230-240 ℃ and enters a hot lean oil tank;
(4) The other path of the hot lean oil heated by the high-temperature raw gas is sent to a negative pressure ammonia distillation reboiler for heating the wastewater generated by the ammonia distillation tower kettle and is sent back to the ammonia distillation tower for ammonia distillation;
(5) Heating the waste water by the hot lean oil in an ammonia distillation reboiler, reducing the temperature to 210-220 ℃, and flowing out to enter a hot lean oil tank;
(6) The temperature of the mixed two paths of lean oil in the hot lean oil groove is 225-235 ℃ and is pumped again by the hot lean oil circulating pump to the rising pipe heat exchanger to exchange heat with the high-temperature raw gas to complete a cycle, and thus the cycle is reciprocated.
The invention has the beneficial effects that:
1. the invention utilizes the hot fluid such as hot lean oil, molten salt, etc. as the heat medium for recovering waste heat of crude gas, is also used for heating medium of technological processes such as debenzolization and ammonia distillation, etc., provide and convey energy through the circulating pump, form and get the heat and heat supply closed cycle system, the invention can replace the tubular heating furnace in the existing debenzolization and ammonia distillation technological device, the invention replaces ammonia distillation and can save the tubular furnace and use the gas or steam and evaporate the heating steam that ammonia uses, do not need to burn the coke oven gas with high value, can replace the debenzolization tubular furnace, save the gas; the technical method and the device for removing benzene and ammonia by using the waste heat of the heat-conducting oil recovery ascending pipe can reduce the energy consumption of a chemical production recovery system, avoid and reduce the emission of pollutants, and correspondingly reduce the acquisition cost and the use cost of related environmental protection equipment;
the method and the equipment can be used for negative pressure ammonia distillation and negative pressure benzene removal, and also can be used for normal pressure benzene removal and normal pressure ammonia distillation; can be independently used for ammonia distillation or benzene removal; can also be used for heating other technological processes (such as ammonium sulfate drying, sulfur melting kettle heating, etc.).
After the waste heat of the high-temperature raw gas of the single rising pipe is recovered (800-500 ℃), 10 ten thousand kilocalories per hour of heat can be recovered, and the heat can be recovered annually: 10×24×365=87600 kilocalories, converted to standard coal 7000 kcal/kg standard coal calculation: 125 tons of standard coal per year; standard coal is used according to 960 yuan/ton; the annual benefit is: 12 ten thousand yuan/year. For a 110 ten thousand t/y coke plant (a 2 seat 55 hole coke oven) a benefit of 1320 ten thousand yuan can be produced each year.
2. Compared with the recovery steam (temperature), the invention can recover high-quality waste heat (temperature); the two media are completely countercurrent in the equipment, the heat exchange temperature difference is maximum, and the maximum heat transfer coefficient can be obtained.
3. The conduction oil is circulated in a closed loop, and no running, overflowing, dripping and leaking occur; the ascending pipe adopts independent control, and can be independently replaced and independently maintained.
4. The inner wall of the inner cylinder body is provided with an inorganic polymer coating composite material which is smooth, good in radiation heat transfer and thermal stability and capable of preventing tar from hanging on the wall. The inorganic polymer coating can make the inner wall of the equipment smooth, strengthen radiation heat transfer, has good thermal stability, prevents tar from hanging on the wall, has high thermal efficiency and reduces the temperature of the outer wall.
5. The spiral fins of the intermediate heat exchange layer can increase the heat exchange area, improve the strength of the inner cylinder body, increase the turbulence strength of fluid, strengthen heat exchange and improve the heat exchange efficiency.
6. The outer cylinder body is provided with an outer cylinder wall temperature real-time monitor which is connected with the controller. The wall temperature of the outer cylinder body is continuously detected through the outer cylinder body wall temperature real-time monitor, and when the wall temperature rises, the situation that the outer cylinder body possibly leaks is indicated, so that the safety of equipment is ensured.
Drawings
FIG. 1 is a flow chart of a system in normal operation;
fig. 2 is a schematic block diagram of a riser heat exchanger.
Detailed Description
For a better understanding of the present invention, embodiments of the present invention are explained in detail below with reference to the drawings.
Method of implementation
As shown in the accompanying drawings 1 and 2, the equipment for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation comprises a riser heat exchanger 1, an ammonia distillation reboiler 2, a negative pressure ammonia distillation tower 3, a benzene removal reboiler 4, a negative pressure benzene removal tower 5, a heat medium tank 6, a heat lean oil tank 9, valves 11-20 and a pipeline 21 forming closed cycle.
The rising pipe heat exchanger 1 comprises an outside heat medium inlet and outlet pipe 121 and a middle raw gas inlet and outlet pipe 122, wherein a heat medium inlet 123 of the heat medium inlet and outlet pipe 121 is arranged at the upper part and a heat medium outlet 124 is arranged at the lower part, the heat medium inlet 123 and the heat medium outlet 124 are respectively connected with an external pipe through respective flanges, the heat medium inlet and outlet pipe 121 is internally provided with a heat medium, the raw gas inlet and outlet pipe comprises a lower raw gas inlet 125 and an upper raw gas outlet 126, the raw gas inlet 125 is connected with a coke oven gas outlet pipe through a flange, the raw gas outlet 126 is connected with a bridge pipe through a flange, the heat medium outlet 124 is connected with the upper inlet of the ammonia distillation reboiler 2, the heat medium outlet 124 is simultaneously connected with the upper part of the benzene removal reboiler 4 through a pipeline and a valve I11, the top outlet of the benzene removal reboiler 4 is simultaneously connected with the heat medium outlet 124 through a pipeline and a valve II 12 and a valve IV 14, the pipeline between the valve II 12 and the valve IV 14 is connected with the negative pressure debenzolization tower 5 through a pipeline I22, a valve III 13 is arranged on the pipeline I22, the outlet of the lower part of the debenzolization reboiler 4 is connected with the inlet of the bottom of the thermal lean oil tank 9 through a pipeline and a valve V15, a valve VI 16 is arranged on the pipeline connected with the inlet of the bottom of the thermal lean oil tank 9, the outlet of the lower part of the debenzolization reboiler 4 is connected with the inlet of the thermal medium tank 6 through a pipeline and a valve V17, the outlet of the lower part of the ammonia still reboiler 2 is also connected with the inlet of the bottom of the thermal lean oil tank 9 through a pipeline and a valve V17, the steam outlet at the top of the ammonia still 2 is connected with the middle part of the negative pressure ammonia still 3 through a pipeline, and the waste water outlet at the bottom of the negative pressure ammonia still 3 is connected with the inlet at the bottom of the ammonia still 2 through a pipeline; the outlet of the lower part of the negative pressure debenzolization tower 5 is connected with the inlet of the lower part of the heat lean oil tank 9 through a pipeline, the outlet of the heat lean oil tank 9 is connected with the inlet of the heat lean oil circulating pump 10, the outlet of the heat lean oil circulating pump 10 is connected with the bottom of the debenzolization reboiler 4 through one pipeline 23 and a valve eight 18, the outlet of the heat lean oil circulating pump is connected with the heat medium inlet 123 of the rising pipe heat exchanger 1 through a valve nine 9 and another pipeline 21, meanwhile, the other pipeline 21 is connected with the outlet of the heat medium pump 8 through a valve ten 20, the inlet of the heat medium pump 8 is connected with the outlet of the heat medium tank 6, and the heating device 7 is arranged in the heat medium tank 6. The raw gas inlet and outlet flange 101 is connected with the coke oven and the bridge pipe, and raw gas enters and exits from the bottom; the heat medium inlet and outlet flange 110 is connected with an external pipeline, the heat medium enters and exits from the upper part, the two mediums completely flow back in the equipment, the heat exchange temperature difference is maximum, and the maximum heat transfer coefficient can be obtained.
The heating device 7 adopts an electric heating device.
The heat medium adopts heat lean oil, heat conducting oil or molten salt.
The rising pipe heat exchanger 1 comprises a raw gas inlet and outlet flange 101, an inner cylinder 103, a middle cylinder 105 and an outer cylinder 108 at two ends, and a heat medium inlet and outlet flange 110. The heat medium inlet and outlet flange 110 is respectively connected with a heat medium inlet 123 and a heat medium outlet 124 of the heat medium inlet and outlet pipeline. A heat medium inlet and outlet pipeline 121 is formed between the inner cylinder 103 and the middle cylinder 105, the inner cavity of the inner cylinder 103 is a raw gas inlet and outlet pipeline 122, and the raw gas inlet and outlet flange 101 is respectively connected with the ends of the inner cylinder 103, the middle cylinder 105 and the outer cylinder 108.
The inner wall of the inner cylinder 103 is provided with an inorganic polymer coating 102 which is smooth, good in radiation heat transfer and thermal stability and capable of preventing tar from hanging on the wall; the inorganic polymer coating 102 can make the inner wall of the equipment smooth, strengthen radiation heat transfer, has good thermal stability and prevents tar from hanging on the wall.
The inner cylinder 103 is connected with the middle cylinder 105 through the middle heat exchange layer spiral fins 104, and an outer layer heat resistance material 106 is arranged between the middle cylinder 105 and the outer cylinder 108. The heat exchange area can be increased, the strength of the inner cylinder 103 can be improved, the fluid turbulence intensity can be increased, the heat exchange can be enhanced, and the heat exchange efficiency can be improved through the spiral fins 104 of the middle heat exchange layer.
A deformation compensator 107 is provided between the intermediate cylinder 105 and the outer cylinder 108, and the deformation compensator 107 is an annular groove 111 provided on the intermediate cylinder 105 and protruding toward the outer cylinder 108.
The outer cylinder 108 is provided with an outer cylinder wall temperature real-time monitor 109 which is connected with a controller. The wall temperature of the outer cylinder body is continuously detected by the outer cylinder body wall temperature real-time monitor 9, and the situation that the outer cylinder body possibly leaks is indicated when the wall temperature rises, so that the safety of equipment is ensured.
A method for recycling waste heat of raw coke oven gas for debenzolization and ammonia distillation, wherein the waste heat of raw coke oven gas in a rising pipe is recycled through a heat medium (heat conducting oil or molten salt) when a negative pressure debenzolization tower 5 is in a starting state, comprises the following steps:
1) Opening valve one 11, valve three 13, valve four 14, valve seven 17, valve eight 18 and valve ten 20, and closing valve two 12, valve five 15, valve six 16 and valve nine 19;
2) Heating the heat medium in the heat medium tank 6 to 240-260 ℃ by an electric heating device 7 in the heat medium tank 6;
3) Pumping out the heat medium in the heat medium tank 6 by using a heat medium pump 8, sending the heat medium to the rising pipe heat exchanger 1 to exchange heat with the high-temperature raw gas with the temperature of 750-850 ℃, and raising the temperature of the heat medium to 260-280 ℃;
4) One path is sent to a debenzolization reboiler 4 to exchange heat with the hot lean oil from the hot lean oil tank 9, the hot lean oil is heated to 225-235 ℃ and sent to a negative pressure debenzolization tower to provide heat for debenzolization, and then the hot lean oil returns to the hot lean oil tank;
5) The other path of the waste water is sent to a negative pressure ammonia distillation reboiler 2 to heat ammonia distillation waste water at the bottom of a negative pressure ammonia distillation tower 3 to generate steam which is sent back to the negative pressure ammonia distillation tower for ammonia distillation;
6) The temperature of the heat medium which is discharged after the heat exchange of the negative pressure benzene steaming reboiler 4 and the negative pressure ammonia steaming reboiler 2 is 240-260 ℃ and enters the heat medium tank 6, and the heat medium is pumped by the heat medium pump 8 to be sent to the rising pipe heat exchanger to exchange heat with the high-temperature raw gas again to complete a cycle, thus the cycle is repeated;
7) Normal operation state of system
When the system is started to operate until a sufficient amount of hot lean oil with the temperature of 225-235 ℃ is accumulated, the hot lean oil is used as a circulating heat medium for system operation, and the method specifically comprises the following steps of:
(1) Stopping the operation of the heat medium pump 8, closing and opening the valve I11, the valve III 13, the valve IV 14, the valve seven 17, the valve eight 18 and the valve ten 20, and opening the valve II 12, the valve five 15, the valve six 16 and the valve nine 19;
(2) Starting a hot lean oil circulating pump 10 to pump out hot lean oil with the temperature of 225-235 ℃ in a hot lean oil tank 9, sending the hot lean oil to a riser heat exchanger 1 to exchange heat with high-temperature raw gas with the temperature of 750-850 ℃ and raising the temperature to 240-250 ℃;
(3) One path of the hot lean oil heated by the high-temperature raw gas is directly sent to a negative pressure debenzolization tower kettle, oil gas is produced by flash evaporation under a negative pressure state and is used as a heat source for negative pressure debenzolization, and the temperature of the hot lean oil after flash evaporation is 230-240 ℃ and enters a hot lean oil tank;
(4) The other path of the hot lean oil heated by the high-temperature raw gas is sent to a negative pressure ammonia distillation reboiler for heating the wastewater generated by the ammonia distillation tower kettle and is sent back to the ammonia distillation tower for ammonia distillation;
(5) Heating the waste water by the hot lean oil in an ammonia distillation reboiler, reducing the temperature to 210-220 ℃, and flowing out to enter a hot lean oil tank;
(6) The temperature of the mixed two paths of lean oil in the thermal lean oil tank 9 is pumped again by the thermal lean oil circulating pump at 225-235 ℃ and is sent to the riser heat exchanger to exchange heat with the high-temperature raw gas to complete a cycle, and the cycle is repeated. The invention adopts a heat fluid to recycle the waste heat of the high-temperature raw gas of the coke oven for directly removing benzene and evaporating ammonia, adopts a riser composite material heat exchanger, uses the heat fluid (comprising heat lean oil and molten salt) as a heat medium for recycling the waste heat of the raw gas, directly uses the heat fluid as a heating medium in the processes of removing benzene, evaporating ammonia and the like, and provides conveying energy through a circulating pump to form a closed-loop circulation system for heat taking and heat supplying. The invention can be used for negative pressure ammonia distillation and negative pressure benzene removal, normal pressure benzene removal and normal pressure ammonia distillation, can be independently used for ammonia distillation or benzene removal, and can also be used for heating other technological processes (such as ammonium sulfate drying, sulfur melting kettle heating and the like). The inner layer inorganic polymer coating is adopted in the riser composite material heat exchanger, so that the inner wall of equipment is smooth, radiation heat transfer is enhanced, the heat stability is good, and tar wall hanging is prevented; the spiral fins of the middle heat exchange layer have the advantages of increasing the heat exchange area, improving the strength of the inner cylinder, increasing the turbulence strength of fluid, strengthening heat exchange and improving the heat exchange efficiency; the real-time monitor for the wall temperature of the outer cylinder can continuously detect the wall temperature of the outer cylinder, and when the wall temperature rises, the condition that the outer cylinder possibly leaks is indicated, so that the safety of equipment is ensured.
While the foregoing description of the embodiments of the present invention has been presented with reference to the drawings, it is not intended to limit the scope of the invention, but rather, it is apparent that various modifications or variations can be made by those skilled in the art without the need for inventive work on the basis of the technical solutions of the present invention.
Claims (7)
1. The method for removing benzene and distilling ammonia by using the waste heat of the coke oven raw gas comprises a rising pipe heat exchanger, an ammonia distilling reboiler, a negative pressure ammonia distilling tower, a benzene removing reboiler, a negative pressure benzene removing tower, a heat medium tank and a heat lean oil tank, wherein the rising pipe heat exchanger comprises an outer heat medium inlet and outlet pipe and a middle raw gas inlet and outlet pipe, the heat medium inlet of the heat medium inlet and outlet pipe is arranged at the upper part and the lower part, the heat medium inlet and the heat medium outlet are respectively connected with an external pipeline through respective flanges, the heat medium inlet and outlet pipe is internally provided with a heat medium, the raw gas inlet and outlet pipe comprises a lower raw gas inlet and an upper raw gas outlet, the raw gas inlet is connected with an air outlet pipe through a flange, the raw gas outlet is connected with a bridge pipe through a flange, the heat medium outlet is connected with the upper inlet of the ammonia distillation reboiler, the heat medium outlet is connected with the upper part of the benzene removal reboiler through a pipeline and a valve I, the top outlet of the benzene removal reboiler is connected with the heat medium outlet through a pipeline and a valve II, the pipeline between the valve II and the valve IV is connected with the negative pressure benzene removal tower through a pipeline I, a valve III is arranged on the pipeline I, the lower outlet of the benzene removal reboiler is connected with the bottom inlet of the heat lean oil tank through a pipeline and a valve V, a valve VI is arranged on the pipeline connected with the bottom inlet of the heat lean oil tank, the lower outlet of the benzene removal reboiler is connected with the bottom inlet of the heat medium tank through a pipeline and a valve seven, the lower outlet of the ammonia distillation reboiler is connected with the bottom inlet of the heat lean oil tank through a pipeline and a valve VI, the top steam outlet of the ammonia distillation reboiler is connected with the middle part of the negative pressure ammonia distillation tower through a pipeline, the waste water outlet at the bottom of the negative pressure ammonia still is connected with the inlet at the bottom of the ammonia still reboiler through a pipeline; the outlet of the negative pressure debenzolization tower is connected with the inlet of the lower part of a heat lean oil tank through a pipeline, the outlet of the heat lean oil tank is connected with the inlet of a heat lean oil circulating pump, the outlet of the heat lean oil circulating pump is connected with the bottom of a debenzolization reboiler through one pipeline and a valve eight, the outlet of the heat lean oil circulating pump is connected with the heat medium inlet of a riser heat exchanger through a valve nine and another pipeline, meanwhile, the other pipeline is connected with a heat medium pump outlet through a valve ten, the heat medium pump inlet is connected with the outlet of the heat medium tank, a heating device is arranged in the heat medium tank, a raw gas inlet and outlet flange is connected with a coke oven and a bridge pipe, and the heat medium inlet and outlet flange is connected with an external pipeline;
the rising pipe heat exchanger comprises raw gas inlet and outlet flanges, an inner cylinder, a middle cylinder and an outer cylinder at two ends, and a heat medium inlet and outlet flange which is respectively connected with a heat medium inlet and a heat medium outlet of a heat medium inlet and outlet pipeline; a heat medium inlet and outlet pipeline is formed between the inner cylinder body and the middle cylinder body, the inner cavity of the inner cylinder body is a raw gas inlet and outlet pipeline, and raw gas inlet and outlet flanges are respectively connected with the ends of the inner cylinder body, the middle cylinder body and the outer cylinder body; the method is characterized by comprising a negative pressure debenzolization tower starting state, a system normal operation state and a negative pressure debenzolization tower starting state, wherein waste heat of raw gas in a rising pipe is recovered through heat conduction oil or molten salt, and the method comprises the following steps:
1) Opening the first valve, the third valve, the fourth valve, the fifth valve, the seventh valve, the eighth valve and the tenth valve, and closing the second valve, the sixth valve and the ninth valve;
2) Heating the heat medium in the heat medium tank to 240-260 ℃ by an electric heating device in the heat medium tank;
3) Pumping out the heat medium in the heat medium tank by using a heat medium pump, sending the heat medium to a riser heat exchanger to exchange heat with high-temperature raw gas at 750-850 ℃, and raising the temperature of the heat medium to 260-280 ℃;
4) One path of the heat medium is sent to a benzene removal reboiler to exchange heat with the heat lean oil from the heat lean oil tank, the heat lean oil is heated to 225-235 ℃ and sent to a negative pressure benzene removal tower to provide heat for benzene removal, and then the heat is returned to the heat lean oil tank;
5) The other path of the heat medium is sent to an ammonia distillation reboiler to heat ammonia distillation wastewater from the bottom of the negative pressure ammonia distillation tower to generate steam which is sent back to the negative pressure ammonia distillation tower to distill ammonia;
6) The temperature of the mixed heat medium after heat exchange of the debenzolization reboiler and the ammonia distillation reboiler is 246-260 ℃, the mixed heat medium enters a heat medium tank, is pumped by a heat medium pump and is sent to a riser heat exchanger to exchange heat with high-temperature raw gas again to complete a cycle, and the cycle is repeated;
7) Normal operation state of system
When the system is started to operate until a sufficient amount of hot lean oil with the temperature of 225-235 ℃ is accumulated, the hot lean oil is used as a circulating heat medium for system operation, and the method specifically comprises the following steps of:
(1) Stopping the operation of the heat medium pump, closing the valve I, the valve IV, the valve seven, the valve eight and the valve ten, and opening the valve II, the valve III, the valve five, the valve six and the valve nine;
(2) Starting a hot lean oil circulating pump to pump out hot lean oil with the temperature of 225-235 ℃ in a hot lean oil groove, sending the hot lean oil to a riser heat exchanger to exchange heat with high-temperature raw coke oven gas with the temperature of 750-850 ℃, and raising the temperature to 240-250 ℃;
(3) One path of the hot lean oil heated by the high-temperature raw gas is directly sent to a negative pressure debenzolization tower, oil gas generated by flash evaporation is used as a heat source for negative pressure debenzolization under a negative pressure state, and the temperature of the hot lean oil after flash evaporation is 230-240 ℃ and enters a hot lean oil tank;
(4) The other path of the hot lean oil heated by the high-temperature raw gas is sent to an ammonia distillation reboiler for heating the wastewater from the negative pressure ammonia distillation tower to generate steam which is sent back to the negative pressure ammonia distillation tower for ammonia distillation;
(5) Heating the waste water by the hot lean oil in an ammonia distillation reboiler, reducing the temperature to 210-220 ℃, and flowing out to enter a hot lean oil tank;
(6) The temperature of the mixed two paths of lean oil in the hot lean oil groove is 225-235 ℃ and is pumped again by the hot lean oil circulating pump to the rising pipe heat exchanger to exchange heat with the high-temperature raw gas to complete a cycle, and thus the cycle is reciprocated.
2. The method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation as claimed in claim 1, wherein the inner wall of the inner cylinder is provided with an inorganic polymer coating which is smooth, good in radiation heat transfer and thermal stability and capable of preventing tar from hanging on the wall.
3. The method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation as claimed in claim 1, wherein the inner cylinder and the middle cylinder are connected through a spiral fin of a middle heat exchange layer, and an outer layer heat resistance material is arranged between the middle cylinder and the outer cylinder.
4. The method for recycling raw coke oven gas waste heat for benzene removal and ammonia distillation according to claim 1, wherein a deformation compensator is arranged between the middle cylinder and the outer cylinder, the deformation compensator is an annular groove which is arranged on the middle cylinder and protrudes to one side of the outer cylinder, the thermal extension of the pipeline can be compensated in the pipeline through the compensator, the deformation or damage of the pipeline is prevented, and the maintenance workload and the maintenance cost are reduced.
5. The method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation as claimed in claim 1, wherein an outer cylinder wall temperature real-time monitor is arranged on the outer cylinder body, and the monitor is connected with a controller.
6. The method for recovering waste heat of raw coke oven gas for benzene removal and ammonia distillation as claimed in claim 1, wherein the heat medium adopts heat lean oil, heat conducting oil or molten salt.
7. The method for recovering waste heat of raw coke oven gas for benzene removal and ammonia distillation as claimed in claim 1, wherein the heating device adopts an electric heating device.
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| CN103274489A (en) * | 2013-05-21 | 2013-09-04 | 中冶焦耐工程技术有限公司 | Negative-pressure ammonia distillation process and device taking crude gas waste heat as heat source |
| CN203530217U (en) * | 2013-08-30 | 2014-04-09 | 常州江南电力节能科技有限公司 | Raw coke oven gas waste heat recycling system |
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| CN104495968A (en) * | 2014-11-24 | 2015-04-08 | 北京首钢国际工程技术有限公司 | Negative-pressure ammonia distilling method used for heating ammonia distilling recycled waste water with coke oven crude gas waste heat |
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Denomination of invention: Equipment and method for recovering waste heat from coke oven raw gas for benzene removal and ammonia distillation Effective date of registration: 20230703 Granted publication date: 20230509 Pledgee: Rizhao Bank Co.,Ltd. Jinan Changqing Branch Pledgor: JINAN METALLURGY CHEMICAL EQUIPMENT CO.,LTD. Registration number: Y2023980046845 |