CN108151547B - Equipment and method for recycling waste heat of raw coke oven gas for benzene removal and ammonia distillation - Google Patents

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

Equipment and method for recovering coke oven raw gas waste heat for debenzene removal and ammonia distillation

technical field

The invention relates to the technical field of waste heat recovery and utilization of coke oven rising pipe raw gas, in particular to a method and equipment for recovering waste heat of coke oven raw gas by using thermal fluid for removing benzene and distilling ammonia.

Background technique

The average temperature of the raw gas in the riser of the coke oven is about 700°C, and the heat produced is equivalent to about 35% of the heat consumed by coking. In direct contact with the raw gas, the raw gas is rapidly cooled to 80-83°C by the vaporization of a large amount of circulating ammonia and sent to the subsequent gas refining system. The heat of the raw coal gas in the above process is converted into useless low-temperature water vapor (~82°C), which consumes a large amount of circulating water and low-temperature water to cool the raw coal gas, which is an obviously high energy-consuming and low-efficiency production process.

A large number of researches have been done at home and abroad on the recovery and utilization of raw gas waste heat in the rising pipe of the coking oven. The current technical method is to recycle the waste heat in the rising pipe to generate low-pressure steam and merge it into the steam pipe network (including directly adding raw gas to water to generate low-pressure steam and using heat conduction The oil recovers the waste heat and then passes through the reboiler to exchange heat to produce steam, etc.). However, it has not been considered that steam as a heating medium for coking production and recovery will generate a large amount of wastewater, which will increase the difficulty and cost of wastewater treatment in coking plants. At the same time, low-pressure steam cannot be used for the debenzene regeneration process of coking. As far as the plant is concerned, it is a development system and an inefficient heat supply energy source.

Contents of the invention

The purpose of the present invention is to solve the problems existing in the prior art, and to provide a kind of equipment for reclaiming the waste heat of coke oven waste gas for debenzene and ammonia distillation; The heat medium for the recovery of gas waste heat is also the heating medium for the processes of debenzene removal and ammonia distillation. The circulation pump provides energy for transportation to form a closed-circuit circulation system for heat extraction and heat supply. The present invention can replace the existing benzene removal And the tubular heating furnace in the ammonia distillation process device does not need to burn high-value coke oven gas, and there is no tubular furnace flue gas generation and flue gas desulfurization and denitrification device, using the hot lean oil, molten salt, etc. of the present invention The technical method and device for recovering the waste heat of the riser from the thermal fluid for benzene removal and ammonia distillation can reduce the energy consumption of the chemical production recovery system, avoid and reduce the discharge of pollutants, and correspondingly reduce the purchase cost and use of related environmental protection equipment. cost.

The invention also provides a method for recovering waste heat of raw coke oven gas for debenzene removal and ammonia distillation.

The technical scheme that the present invention solves technical problem is:

A device for recovering coke oven raw gas waste heat for debenzene removal and ammonia distillation, including riser heat exchanger, ammonia distillation reboiler, negative pressure ammonia distillation tower, benzene removal reboiler, negative pressure debenzene tower, heat Medium tank, heat-lean oil tank, the riser heat exchanger includes the outer heat medium inlet and outlet pipes, the middle raw gas inlet and outlet pipes, the heat medium inlet of the heat medium inlet and outlet pipes is at the upper part, the heat medium outlet is at the lower part, and the heat medium The inlet and the heat medium outlet are respectively connected to the external pipes through their respective flanges. The heat medium inlet and outlet pipes are equipped with heat medium. The raw gas inlet and outlet pipes include the lower raw gas inlet and the upper raw gas outlet. The flange is connected to the coke oven gas outlet pipe, the raw gas outlet is connected to the bridge pipe through the flange, the heat medium outlet is connected to the upper inlet of the ammonia distillation reboiler, and the heat medium outlet is connected to the upper part of the debenzene reboiler through pipes and valves. The top outlet of the debenzene reboiler is connected to the outlet of the heat medium through the pipeline and valve 2 and valve 4 at the same time, and the pipeline between the valve 2 and valve 4 is connected to the negative pressure debenzene tower through the pipeline 1, and the pipeline 1 is equipped with a valve 3. The outlet of the lower part of the debenzene reboiler is connected to the bottom inlet of the hot lean oil tank through the pipeline and valve five, and a valve six is set on the pipeline connected to the bottom inlet of the hot lean oil tank, and the lower outlet of the debenzene reboiler passes through the pipeline and valve seven It is connected to the inlet of the heat medium tank, and the lower outlet of the ammonia distiller reboiler is also connected to the bottom inlet of the hot lean oil tank through the pipeline and valve 6, and is connected to the inlet of the heat medium tank through the valve 7, and the steam outlet on the top of the ammonia distiller reboiler is connected to the negative pressure The middle part of the ammonia distillation tower is connected by a pipeline, and the waste water outlet at the bottom of the negative pressure ammonia distillation tower is connected to the bottom inlet of the ammonia distillation reboiler through a pipeline; The inlet of the hot lean oil circulating pump is connected, and the outlet of the hot lean oil circulating pump is connected to the bottom of the debenzene reboiler through one pipeline and valve eight, and connected to the heat medium inlet of the riser heat exchanger through valve nine and another pipeline. The other pipeline is connected to the outlet of the heat medium pump through the valve ten, and the inlet of the heat medium pump is connected to the outlet of the heat medium tank. The heat medium tank is equipped with a heating device, and the raw gas inlet and outlet flanges are connected to the coke oven and the bridge pipe. The medium inlet and outlet flanges are connected to external pipes.

The riser tube heat exchanger includes raw gas inlet and outlet flanges at both ends, an inner cylinder, an intermediate cylinder, an outer cylinder, and heat medium inlet and outlet flanges. The heat medium inlet and outlet flanges are respectively connected to the heat medium inlet and outlet The heat medium inlet and heat medium outlet of the pipeline are connected; heat medium inlet and outlet pipes are formed between the inner cylinder and the middle cylinder, and the inner cavity of the inner cylinder is a raw gas inlet and outlet pipe, and the raw gas inlet and outlet flanges are respectively connected to the inner cylinder and the middle cylinder. The end of the body and the outer cylinder are connected.

The inner wall of the inner cylinder is provided with an inorganic polymer coating which is smooth, has good radiation heat transfer and thermal stability, and prevents tar from hanging on the wall.

The inner cylinder and the middle cylinder are connected by spiral fins in the middle heat exchange layer, and an outer layer of thermal resistance material is arranged between the middle cylinder and the outer cylinder.

A deformation compensator is provided between the middle cylinder and the outer cylinder, and the deformation compensator is an annular groove protruding from one side of the outer cylinder provided on the middle cylinder.

The outer cylinder is provided with a real-time monitor for the wall temperature of the outer cylinder, and the monitor is connected with the controller.

The heat medium adopts hot lean oil, molten salt or heat conduction oil.

The heating device adopts an electric heating device.

A method for recovering coke oven raw gas waste heat for use in a device for removing benzene and ammonia. When the negative pressure debenzene tower is started, the waste heat of the raw gas in the riser is recovered through heat transfer oil or molten salt, including the following steps:

1) Open valve 1, valve 3, valve 4, valve 7, valve 8, valve 10, close valve 2, valve 5, valve 6, valve 9;

2) Heat the heat medium in the heat medium tank to 240-260°C through the electric heating device in the heat medium tank;

3) Use the heat medium pump to pump out the heat medium in the heat medium tank and send it to the riser heat exchanger to exchange heat with the high-temperature raw gas at 750-850°C. After the temperature of the heat medium rises to 260-280°C;

4) Send all the way to the debenzene reboiler to exchange heat with the hot lean oil from the hot lean oil tank, heat the hot lean oil to 225-235°C and send it to the negative pressure debenzene tower to provide heat for debenzene removal and then return to the hot lean oil oil tank;

5) The other way is sent to the negative pressure ammonia distillation reboiler to heat the ammonia distillation waste water from the bottom of the negative pressure ammonia distillation tower to generate steam and send it back to the negative pressure ammonia distillation tower to distill ammonia;

6) After the heat exchange between the negative pressure benzene reboiler and the negative pressure ammonia reboiler, the mixed heat medium temperature is 246-260°C, enters the heat medium tank, is pumped out by the heat medium pump and sent to the riser pipe for heat exchange The device exchanges heat with the high-temperature raw gas again to complete a cycle, and so on;

7) The system is in normal operation

When the system starts to run and accumulates a sufficient amount of hot lean oil at a temperature of 225-235°C, use the hot lean oil as the circulating heat medium for system operation, specifically including the following steps:

(1) Stop running the thermal medium pump, close and open valves 1, 3, 4, 7, 8, and 10, and open valves 2, 5, 6, and 9;

(2) Start the hot lean oil circulation pump to draw out the hot lean oil with a temperature of 225-235°C in the hot lean oil tank, and send it to the riser heat exchanger to exchange heat with the high-temperature raw gas at 750-850°C, and the temperature rises to 240°C ~250℃;

(3) The hot lean oil heated by high-temperature raw gas is directly sent to the negative pressure debenzene tower kettle all the way, and flashes under negative pressure to generate oil gas as the heat source for negative pressure debenzene, and the temperature of the hot lean oil after flash evaporation is at 230～240℃, enter the hot lean oil tank;

(4) The hot lean oil heated by high-temperature raw gas is sent to the negative pressure ammonia distillation reboiler to heat the waste water from the ammonia distillation tower to generate steam and send it back to the ammonia distillation tower for ammonia distillation;

(5) After heating the waste water with hot lean oil in the ammonia distillation reboiler, the temperature drops to 210-220°C and then flows out into the hot lean oil tank;

(6) After the two-way lean oil in the hot lean oil tank is mixed, the temperature is pumped out again by the hot lean oil circulation pump at 225-235°C and sent to the riser heat exchanger to exchange heat with high-temperature raw coal gas to complete a cycle, and so on.

Beneficial effects of the present invention:

1. The present invention utilizes hot fluids including hot lean oil and molten salt as the heat medium for recovering the waste heat of raw coal gas, and is also the heating medium for processes such as debenzene removal and ammonia distillation. A closed-circuit circulation system for heat and heat supply. The present invention can replace the tubular heating furnace in the existing process devices for debenzene removal and ammonia distillation. The present invention replaces the ammonia distillation and can save the heating of gas or steam ammonia distillation in the tubular furnace. Steam does not need to burn high-value coke oven gas, which can replace the debenzene tube furnace and save gas; there is no tube furnace flue gas generation and flue gas desulfurization and denitrification device. The heat transfer oil recovery rising pipe of the present invention The application of waste heat to the technical methods and devices for removing benzene and ammonia can reduce the energy consumption of the chemical production recovery system, avoid and reduce the discharge of pollutants, and correspondingly reduce the purchase and use costs of related environmental protection equipment and devices;

The method and equipment described in the present invention can be used for negative pressure ammonia distillation and negative pressure debenzene removal and can also be used for atmospheric pressure debenzene removal and normal pressure ammonia distillation; can be used for ammonia distillation or benzene removal alone; can also be used as other processes (such as Ammonium sulfate drying, sulfur melting kettle heating, etc.) heat supply.

After recovery of high-temperature waste gas waste heat (800-500°C) in the single rising pipe of the present invention, heat recovery can be 100,000 kcal/hour, and annual heat recovery: 10×24×365=876 million kcal, equivalent to standard coal Calculation of 7000kcal/kg standard coal: 125 tons of standard coal/piece.year; standard coal is 960 yuan/ton; annual benefit is: 120,000 yuan/piece.year. For a 1.1 million t/y coke unit (two 55-hole coke ovens), it can generate an annual benefit of 13.2 million yuan.

2. Compared with the recovery of steam (temperature), the present invention can recover high-quality waste heat (temperature); the two media are completely countercurrent in the equipment, the heat exchange temperature difference is the largest, and the maximum heat transfer coefficient can be obtained.

3. The heat conduction oil circulates in a closed circuit without running, popping, dripping or leaking; the ascending pipe adopts independent control, which can be replaced and maintained independently.

4. The inner wall of the inner cylinder is provided with an inorganic polymer coating composite material that is smooth, has good radiation heat transfer and thermal stability, and prevents tar from hanging on the wall. The inorganic polymer coating can make the inner wall of the equipment smooth, enhance radiation heat transfer, have good thermal stability, prevent tar from hanging on the wall, have high thermal efficiency, and reduce the temperature of the outer wall.

5. The spiral fins in the middle heat exchange layer can increase the heat exchange area, improve the strength of the inner cylinder, increase the fluid turbulence intensity, strengthen heat exchange, and improve heat exchange efficiency.

6. The outer cylinder is provided with a real-time monitor for the wall temperature of the outer cylinder, and the monitor is connected with the controller. The wall temperature of the outer cylinder is continuously detected by the real-time monitor of the wall temperature of the outer cylinder. When the wall temperature rises, it indicates that the outer cylinder may leak, ensuring the safety of the equipment.

Description of drawings

Accompanying drawing 1 is the flow chart when system works normally;

Accompanying drawing 2 is the schematic structural diagram of the riser heat exchanger.

Detailed ways

In order to better understand the present invention, the implementation manner of the present invention will be explained in detail below in conjunction with the accompanying drawings.

Method of implementation

As shown in accompanying drawing 1, Fig. 2, a kind of equipment that recovers coke oven raw gas waste heat and is used for debenzene and ammonia distillation, comprises riser heat exchanger 1, ammonia distillation reboiler 2, negative pressure ammonia distillation tower 3, Debenzene reboiler 4, negative pressure debenzene tower 5, heat medium tank 6, heat lean oil tank 9, valves 11-20 and pipeline 21 forming a closed circuit.

The riser heat exchanger 1 includes a heat medium inlet and outlet pipe 121 on the outside and a raw gas inlet and outlet pipe 122 in the middle. The heat medium inlet 123 of the heat medium inlet and outlet pipe 121 is in the upper part, the heat medium outlet 124 is in the lower part, and the heat medium inlet and outlet 124 are in the lower part. 123. The heat medium outlets 124 are respectively connected to the external pipes through respective flanges. The heat medium inlet and outlet pipes 121 are provided with heat medium. The raw gas inlet and outlet pipes include the lower raw gas inlet 125, the upper raw gas outlet 126, and the raw gas outlet 126. The gas inlet 125 is connected to the coke oven gas outlet pipe through the flange, the raw gas outlet 126 is connected to the bridge pipe through the flange, the heat medium outlet 124 is connected to the upper inlet of the ammonia steam reboiler 2, and the heat medium outlet 124 is connected through a pipe and a valve. 11 is connected to the upper part of the debenzene reboiler 4, and the top outlet of the debenzene reboiler 4 is connected to the heat medium outlet 124 through the pipeline and the valve two 12 and the valve four 14 at the same time, and the pipeline between the valve two 12 and the valve four 14 The pipeline one 22 is connected with the negative pressure debenzene tower 5, the pipeline one 22 is provided with a valve three 13, and the outlet of the lower part of the debenzene reboiler 4 is connected with the bottom inlet of the hot lean oil tank 9 through the pipeline and the valve five 15, and the heat lean The pipeline at the bottom inlet of the oil tank 9 is provided with a valve six 16, while the lower outlet of the debenzene reboiler 4 is connected to the inlet of the heat medium tank 6 through a pipeline and a valve seven 17, and the lower outlet of the ammonia distillation reboiler 2 is also connected through a pipeline and a valve six 16 is connected to the inlet of the bottom of the hot lean oil tank 9, and at the same time is connected to the inlet of the heat medium tank 6 through valve 7 17. The steam outlet at the top of the ammonia steamer reboiler 2 is connected to the middle part of the negative pressure ammonia distillation tower 3 through pipelines, and the negative pressure ammonia distillation tower 3 The outlet of the waste water at the bottom is connected to the bottom inlet of the ammonia distillation reboiler 2 through a pipeline; the lower outlet of the negative pressure debenzene tower 5 is connected to the lower inlet of the hot lean oil tank 9 through a pipeline, and the outlet of the hot lean oil tank 9 is connected to the inlet of the hot lean oil circulation pump 10, The outlet of the hot lean oil circulation pump 10 is connected to the bottom of the debenzene reboiler 4 through a pipeline 23 and a valve eight 18, and connected to the heat medium inlet 123 of the riser heat exchanger 1 through a valve nine 9 and another pipeline 21. The other pipeline 21 is connected to the outlet of the heat medium pump 8 through the valve ten 20, and the inlet of the heat medium pump 8 is connected to the outlet of the heat medium tank 6, and the heat medium tank 6 is provided with a heating device 7. The raw gas inlet and outlet flange 101 is connected to the coke oven and the bridge pipe, and the raw gas enters and exits from the bottom; the heat medium inlet and outlet flange 110 is connected to the external pipeline, and the heat medium enters and exits from the bottom. The thermal temperature difference is the largest, and the largest heat transfer coefficient can be obtained.

The heating device 7 is an electric heating device.

The heat medium adopts hot lean oil, heat conduction oil or molten salt.

The riser heat exchanger 1 includes raw gas inlet and outlet flanges 101 at both ends, an inner cylinder 103 , a middle cylinder 105 , an outer cylinder 108 , and heat medium inlet and outlet flanges 110 . The heat medium inlet and outlet flanges 110 are respectively connected with the heat medium inlet 123 and the heat medium outlet 124 of the heat medium inlet and outlet pipes. 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. The raw gas inlet and outlet flanges 101 are respectively connected to the inner cylinder 103, the middle cylinder 105, The ends of the outer cylinder 108 are connected.

The inner wall of the inner cylinder 103 is provided with an inorganic polymer coating 102 that is smooth, has good radiation heat transfer and thermal stability, and prevents tar from hanging on the wall; the inorganic polymer coating 102 can make the inner wall of the equipment smooth and enhance radiation heat transfer , good thermal stability, prevent tar hanging on the wall.

The inner cylinder 103 and the middle cylinder 105 are connected by the spiral fins 104 of the middle heat exchange layer, and the outer heat resistance material 106 is arranged between the middle cylinder 105 and the outer cylinder 108 . Through the spiral fins 104 in the middle heat exchange layer, the heat exchange area can be increased, the strength of the inner cylinder 103 can be increased, the fluid turbulence intensity can be increased, heat exchange can be enhanced, and heat exchange efficiency can be improved.

A deformation compensator 107 is provided between the middle cylinder 105 and the outer cylinder 108 , and the deformation compensator 107 is an annular groove 111 provided on the middle cylinder 105 protruding toward the side of the outer cylinder 108 .

The outer cylinder 108 is provided with a real-time monitor 109 for the wall temperature of the outer cylinder, and the monitor is connected with the controller. The wall temperature of the outer cylinder is continuously detected by the real-time monitor 9 of the wall temperature of the outer cylinder. When the wall temperature rises, it indicates that the outer cylinder may leak, so as to ensure the safety of the equipment.

A method for recovering the waste heat of raw coke oven gas for debenzene and ammonia distillation. When the negative pressure debenzene tower 5 is started, the waste heat of the waste gas in the riser is recovered through a heat medium (heat transfer oil or molten salt), comprising the following steps:

1) Open valve one 11, valve three 13, valve four 14, valve seven 17, valve eight 18, valve ten 20, close valve two 12, valve five 15, valve six 16, valve nine 19;

2) heating the heat medium in the heat medium tank 6 to 240-260°C through the electric heating device 7 in the heat medium tank 6;

3) Use the heat medium pump 8 to extract the heat medium in the heat medium tank 6 and send it to the riser heat exchanger 1 to exchange heat with the high-temperature raw gas at 750-850°C, after the temperature of the heat medium rises to 260-280°C;

4) Send all the way to the debenzene reboiler 4, exchange heat with the hot lean oil from the hot lean oil tank 9, heat the hot lean oil to 225-235°C and send it to the negative pressure debenzene tower to provide heat for debenzene removal, and then return to hot lean tank;

5) Another way is sent to the negative pressure ammonia distillation reboiler 2 to heat the ammonia distillation waste water from the bottom of the negative pressure ammonia distillation tower 3 to produce steam and send back to the negative pressure ammonia distillation tower to steam ammonia;

6) After heat exchange between the negative pressure benzene reboiler 4 and the negative pressure ammonia reboiler 2, the heat medium mixed with the temperature of 240-260°C enters the heat medium tank 6 and is pumped out by the heat medium pump 8 to the The riser heat exchanger and the high-temperature raw gas exchange heat again to complete a cycle, and so on;

7) The system is in normal operation

When the system starts to run and accumulates a sufficient amount of hot lean oil at a temperature of 225-235°C, use the hot lean oil as the circulating heat medium for system operation, specifically including the following steps:

(1) Stop running the thermal medium pump 8, close and open valve one 11, valve three 13, valve four 14, valve seven 17, valve eight 18, valve ten 20, open valve two 12, valve five 15, valve six 16, valve nine 19;

(2) Start the hot lean oil circulation pump 10 to extract the hot lean oil at a temperature of 225-235°C in the hot lean oil tank 9, and send it to the riser heat exchanger 1 to exchange heat with the high-temperature raw gas of 750-850°C, and the temperature rises High to 240～250℃;

(3) The hot lean oil heated by high-temperature raw gas is directly sent to the negative pressure debenzene tower kettle all the way, and flashes under negative pressure to generate oil gas as the heat source for negative pressure debenzene, and the temperature of the hot lean oil after flash evaporation is at 230～240℃, enter the hot lean oil tank;

(4) The hot lean oil heated by high-temperature raw gas is sent to the negative pressure ammonia distillation reboiler to heat the waste water from the ammonia distillation tower to generate steam and send it back to the ammonia distillation tower for ammonia distillation;

(5) After heating the waste water with hot lean oil in the ammonia distillation reboiler, the temperature drops to 210-220°C and then flows out into the hot lean oil tank;

(6) The temperature of the two paths of lean oil mixed in the hot lean oil tank 9 is pumped out again by the hot lean oil circulation pump at 225-235° C. and sent to the riser heat exchanger to exchange heat with high-temperature raw coal gas to complete a cycle, and so on. The invention adopts hot fluid to reclaim high-temperature raw gas waste heat of coke oven and directly uses it for removing benzene and steaming ammonia, adopts riser pipe composite material heat exchanger, and uses hot fluid (including hot lean oil and molten salt) as the recovered heat of raw gas waste heat The medium is directly used as the heating medium for processes such as debenzene removal and ammonia distillation, and the energy is provided by the circulation pump to form a closed-circuit circulation system for heat extraction and heat supply. The present invention can be used for negative pressure ammonia distillation and negative pressure debenzene removal, can also be used for atmospheric pressure debenzene removal and normal pressure ammonia distillation, can be used for ammonia distillation or benzene removal alone, and can also be used as other processes (such as ammonium sulfate drying, melting Sulfur kettle heating, etc.) for heat supply. The riser tube composite material heat exchanger of the present invention adopts an inner layer of inorganic polymer coating to make the inner wall of the equipment smooth, enhance radiation heat transfer, have good thermal stability, and prevent tar from hanging on the wall; the spiral fins of the middle heat exchange layer have the function of increasing heat transfer Area, increase the strength of the inner cylinder, increase the intensity of fluid turbulence, strengthen heat transfer, and improve heat transfer efficiency; the real-time monitor of the wall temperature of the outer cylinder can continuously detect the wall temperature of the outer cylinder, and it will indicate when the wall temperature rises The outer cylinder may leak to ensure the safety of the equipment.

Although the specific implementation of the invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. On the basis of the technical solution of the present invention, those skilled in the art can make various Modifications or variations are still within the protection scope 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.

Images