Coking ammonia distillation system capable of deeply utilizing flue gas waste heat of coke oven

Abstract

The utility model discloses a coking ammonia distillation system capable of deeply utilizing flue gas waste heat of a coke oven, which comprises an ammonia distillation tower and a tubular furnace, an ammonia water heater is arranged on the tubular furnace in parallel, and a heat exchange channel of the ammonia water heater is connected with a riser waste heat system. The ascending pipe waste heat system comprises a steam pocket and an ascending pipe heat exchanger for carrying out heat exchange on coke oven flue gas, the steam pocket is respectively connected with heat exchange channel inlets of demineralized water and an ammonia water heater, and a heat exchange channel outlet of the ammonia water heater is connected to the steam pocket after passing through the ascending pipe heat exchanger. According to the utility model, the additionally arranged ammonia water heater is connected with the tube furnace in parallel, and the steam pocket, the riser heat exchanger and the ammonia water heater form a circulating water loop for recovering and utilizing the flue gas waste heat of the coke oven, so that the deep utilization of the flue gas waste heat of the coke oven can be realized, the consumption of coke oven gas required for heating the tube furnace is reduced, and energy conservation and consumption reduction are realized.

Description

Technical Field

[0001] The utility model is a coking ammonia distillation system which deeply utilizes the waste heat of coke oven flue gas, and specifically relates to a structure which can deeply recycle and utilize the waste heat of coke oven flue gas and replace the ammonia distillation tube furnace in the coking process, and belongs to the technical field of flue gas energy saving. Background Art

[0002] In the traditional coking process, the coal entering the coke oven is refined into coke through a high-temperature dry distillation in the carbonization chamber during a coking cycle, which will produce high-temperature raw coal gas at 650-850°C. At present, the high-temperature raw coal gas is usually flowed through the riser and then sprayed with ammonia water in the three-way bridge pipe to be cooled to about 85°C before being sent to the gas refining project. The heat reduced by the ammonia water spraying is not effectively recovered and utilized, resulting in heat loss in the system.

[0003] When ammonia is evaporated in coking, the ammonia evaporation wastewater produced by the ammonia evaporation tower needs to be heated in a tubular furnace and then returned to the ammonia evaporation tower to continue to be used as a heat source. However, the tubular furnace consumes a large amount of coke oven gas, which makes the system energy consumption high. Taking 1.3 million tons / year of coking as an example, the amount of ammonia evaporation wastewater is about 60t / h. The raw ammonia evaporation wastewater is heated to 90-98℃ by the ammonia evaporation wastewater heat exchanger and enters the ammonia evaporation tower. The ammonia evaporation wastewater at the bottom of the tower is taken out and heated in a tubular furnace. It enters the ammonia evaporation tower from the bottom of the tower as a heat source in a gas-liquid two-phase state. The ammonia in the ammonia evaporation water is blown out through continuous distillation. After the ammonia gas at the top of the tower passes through the condenser cooler, part of it is used to supplement the alkali source for HPF (coke oven gas desulfurization); part of it is used for ammonia decomposition. The wastewater discharged from the bottom of the tower is heat-exchanged with the raw ammonia evaporation water and cooled and sent to the sewage treatment station. The other part of the wastewater is sent to the tubular furnace through a circulating pump and returned to the bottom of the ammonia evaporation tower as a heat source for ammonia evaporation after heating. During this process, the coke oven gas consumption of the tube furnace is about 1200Nm 3 / h, heat is about 5 million Kcal / h.

[0004] In the prior art, in order to reduce the heat loss and energy consumption in the above-mentioned coking process, the invention patent with publication number CN104118887A discloses a process for ammonia evaporation using the waste heat of the flue gas of the coke oven, specifically, the flue gas is introduced into the ammonia heater, the waste ammonia water is heated to 160°C by the ammonia heater and then enters the flash tank, the saturated steam is flashed and enters the ammonia evaporation tower to evaporate the raw ammonia water, the ammonia is directly sent to the ammonium sulfate section or further condensed into concentrated ammonia water, the ammonia evaporation wastewater and the waste ammonia water in the flash tank are discharged into the ammonia heater for cyclic heating, and the flue gas after heat exchange is discharged from the ammonia heater through the chimney. Although the process uses flue gas to heat the waste ammonia water to solve the gas consumption caused by the tubular furnace in the existing ammonia evaporation system, the flue gas temperature is relatively high. After the ammonia heater is heat-exchanged, a large amount of heat energy is still present in the flue gas, which is not effectively utilized, but directly discharged from the chimney, which not only causes energy waste, but also may form white smoke to cause landscape pollution. Utility Model Content

[0005] The utility model aims to provide a coking ammonia distillation system which makes deep use of the waste heat of coke oven flue gas. An ammonia water heater is newly connected in parallel with the tubular furnace. At the same time, a steam drum, a riser heat exchanger and an ammonia water heater are used to form a circulating water loop for recovering and utilizing the waste heat of coke oven flue gas. The waste heat of the coke oven flue gas is taken away by circulating water, and then steam is generated through the steam drum to be sent to the ammonia water heater for heat exchange with ammonia distillation waste water, and then the steam is recycled. The waste heat of the coke oven flue gas can be deeply utilized, and the amount of coke oven gas required for heating the tubular furnace can be reduced, thereby saving energy and reducing consumption.

[0006] The utility model is achieved through the following technical scheme: a coking ammonia distillation system that deeply utilizes the waste heat of coke oven flue gas, comprising an ammonia distillation tower and a tubular furnace, an ammonia water heater is arranged in parallel on the tubular furnace, the heat exchange channel of the ammonia water heater is connected to the riser waste heat system, the riser waste heat system comprises a steam drum and a riser heat exchanger for heat exchange of coke oven flue gas, the steam drum is respectively connected to the heat exchange channel inlets of desalted water and the ammonia water heater, and the heat exchange channel outlet of the ammonia water heater is connected to the steam drum after passing through the riser heat exchanger.

[0007] The riser waste heat system also includes a desalted water tank and a deaerator connected in sequence, and the deaerator is connected to the steam drum via a feed water pump.

[0008] The steam drum is provided with a forced circulation pump, and the steam drum is connected to the heat exchange channel inlet of the ammonia water heater through the forced circulation pump.

[0009] The riser waste heat system is provided in two sets, and cut-off valves are provided on the connecting pipes between the forced circulation pump and the heat exchange channel inlet of the ammonia water heater, and the connecting pipes between the heat exchange channel outlet of the ammonia water heater and the riser heat exchanger.

[0010] The steam drum is also connected to the steam network, and a cut-off valve is provided on the connecting pipeline between the forced circulation pump and the riser heat exchanger.

[0011] A cut-off valve is arranged on the parallel pipeline between the ammonia water heater and the tubular furnace.

[0012] The ammonia water heater is a shell and tube heat exchanger.

[0013] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0014] (1) The utility model replaces the tubular furnace used in the existing ammonia distillation system by adding an ammonia water heater. The ammonia water heater uses the waste heat of coke oven flue gas recovered by the riser waste heat system to heat the ammonia distillation wastewater, which can save the coke oven gas consumed by the tubular furnace (about 1300Nm 3 / h).

[0015] (2) The utility model can satisfy the arbitrary switching of the tubular furnace and the ammonia water heater by arranging a switching valve on the parallel pipeline. The tubular furnace of the existing ammonia evaporation system is reserved as a spare and the two systems can be switched at will by using the valve. When the riser waste heat system or the ammonia water heater is overhauled, the tubular furnace heating can be restored, thereby ensuring stable and safe production of the system.

[0016] (3) The utility model does not directly use the coke oven flue gas to heat the ammonia wastewater, nor does it produce steam to heat the ammonia wastewater. Instead, it uses the high-temperature hot water generated by the steam drum to exchange heat with the ammonia wastewater. This can make the water temperature entering the riser heat exchanger lower after the heat exchange, and can make more use of the waste heat of the raw coal gas. The system design is safer and more reasonable.

[0017] (4) The riser heat exchanger of the utility model can be transformed from the existing coke oven riser. The number of the existing two coke oven riser is about 110 to 130. The riser heat exchanger (about 110 to 130) transformed from the riser heat generates a large amount of waste heat. After heating the ammonia wastewater, there is still a lot of residual heat. The circulating water carrying this part of heat can be flashed in the steam drum to produce steam. This steam can be directly transported to the factory steam network and can be used freely by the owner.

[0018] (5) The utility model is flexible in operation. The system can be freely switched to a conventional riser waste heat system simply by controlling the shut-off valve, so that all the heat of the coke oven flue gas (raw gas) can be converted into saturated steam for use by users or to meet the steam demand of the system.

[0019] (6) The steam pressure generated by the utility model is flexible. By controlling the drum pressure, saturated steam of 0.3 to 4.5 MPa can be generated, further reducing the steam energy consumption of the system.

[0020] (7) The ammonia water heater of the present invention can adopt a shell-and-tube heat exchanger, and the heat exchange tube material is 316l. This type of heat exchanger has low resistance and is not blocked, while ensuring the problem of ammonia water corroding the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the utility model system.

[0022] Among them, 1 is a desalted water tank, 2 is a deaerator water pump, 3 is a deaerator, 4 is a feed water pump, 5 is a riser heat exchanger, 6 is a forced circulation pump, 7 is a steam drum, 8 is an ammonia distillation tower, 9 is an ammonia water circulation pump, 10 is a tubular furnace, 11 is an ammonia water heater, 12 is a cut-off valve A, 13 is a cut-off valve B, 14 is a cut-off valve C, 15 is a cut-off valve D, 16 is a cut-off valve E, and 17 is a cut-off valve F. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the embodiments, but the implementation manner of the present invention is not limited thereto.

[0024] Example:

[0025] This embodiment is a coking ammonia distillation system that makes full use of the waste heat of coke oven flue gas.

[0026] like Figure 1 As shown in the structure, the coking ammonia evaporation system is mainly composed of an ammonia evaporation tower 8, a tubular furnace 10, an ammonia water heater 11 and a riser waste heat system, wherein the ammonia evaporation tower 8 and the tubular furnace 10 are both existing equipment. In the prior art, ammonia evaporation waste water (105-110°C) is sent to the tubular furnace 10 through an ammonia water circulation pump 9 at the bottom of the ammonia evaporation tower 8, and the tubular furnace 10 is heated by coke oven gas. The ammonia evaporation waste water is heated (about 130°C) and sent to the top of the ammonia evaporation tower 8 to complete the circulation. The tubular furnace 10 consumes 5 million Kcal / h of heat.

[0027] In this embodiment, the ammonia water heater 11 is connected in parallel with the tube furnace 10, and a cut-off valve is used to switch the ammonia water heater 11 and the tube furnace 10. The ammonia water heater 11 can replace the tube furnace 10 to heat the ammonia wastewater. The ammonia water heater 11 uses the riser waste heat system to recover the raw gas (40000Nm 3 / h, 750~800℃) of waste heat, and then heat exchange with ammonia evaporation wastewater. In a specific embodiment, ammonia evaporation wastewater is taken out from the outlet of ammonia evaporation circulation pump and introduced into ammonia evaporation heater. After ammonia evaporation wastewater is heat exchanged by ammonia water heater 11 (130℃), it is returned to ammonia evaporation tower 8 for use as a heat source.

[0028] In this embodiment, circulating water is used in the ammonia water heater 11 to exchange heat with the ammonia wastewater. The circulating water comes from the riser waste heat system. Figure 1As shown in the structure, the riser waste heat system is mainly composed of a desalted water tank 1, a deaerator 3, a drum 7, a riser heat exchanger 5 and a forced circulation pump 6, wherein the riser heat exchanger 5 can be transformed from the existing coke oven riser, and the number is about 110-130. In a specific embodiment, the riser heat exchanger 5 can be a shell-and-tube heat exchanger. During production, the external desalted water is sent to the desalted water tank, and then sent to the deaerator 3 for deoxygenation through the deoxygenation water pump 2. The deoxygenated water is then sent to the drum 7 through the feed water pump 4. Under a certain pressure control, the high-temperature water (about 200°C) generated in the drum 7 is sent to the ammonia water heater 11 through the forced circulation pump 6 to exchange heat with the ammonia wastewater. The circulating water (about 160°C) after heat exchange in the ammonia water heater 11 enters the riser heat exchanger 5, and the circulating water exchanges heat with the raw coal gas in the riser heat exchanger 5 and then enters the drum 7, thereby completing a cycle. The heat of the raw gas in the riser heat exchanger 5 is absorbed by the circulating water and the temperature drops below 500°C before entering the subsequent process. Since the temperature of the circulating water entering the riser heat exchanger 5 is relatively low, more waste heat of the raw gas can be recovered. A part of the heat is taken out through the continuous circulation of the forced circulation pump 6 through the drum 7, and the hot water produced is transported to the ammonia water heater 11 for heating the ammonia wastewater. The remaining part of the heat is vaporized by the circulating water in the drum 7 to produce saturated steam, which can be sent to the steam network and used freely by the owner. In the actual production process, the amount of steam generated by the residual heat is 5t / h, and the steam pressure of the drum 7 is controlled to be 1.2Mpa.

[0029] This embodiment can be used as Figure 1 The two riser waste heat systems shown in the figure, each riser waste heat system is composed of a steam drum 7, a forced circulation pump 6, and a plurality of riser heat exchangers 5 and an ammonia water heater 11 to realize the circulating water circuit for recovering and utilizing the waste heat of the raw coal gas. A shut-off valve C14 and a shut-off valve D15 can be respectively provided on the connecting pipes of the forced circulation pump 6 and the heat exchange channel inlet of the ammonia water heater 11, and a shut-off valve E16 and a shut-off valve F17 can be respectively provided on the connecting pipes of the heat exchange channel outlet of the ammonia water heater 11 and the riser heat exchanger 5. By switching the shut-off valve C14 and the shut-off valve E16, or the shut-off valve D15 and the shut-off valve F17, the switching use of the two riser waste heat systems can be realized. At the same time, a shut-off valve A12 and a shut-off valve B13 are respectively provided on the connecting pipes of the forced circulation pump 6 and the riser heat exchanger 5, so that all the heat of the raw coal gas can be converted into saturated steam for use by users.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A coking ammonia distillation system that makes full use of the waste heat of coke oven flue gas, comprising an ammonia distillation tower (8) and a tubular furnace (10), characterized in that: An ammonia water heater (11) is arranged in parallel with the tubular furnace (10); a heat exchange channel of the ammonia water heater (11) is connected to a riser waste heat system; the riser waste heat system comprises a steam drum (7) and a riser heat exchanger (5) for exchanging heat with coke oven flue gas; the steam drum (7) is respectively connected to the heat exchange channel inlets of desalted water and the ammonia water heater (11); and an outlet of the heat exchange channel of the ammonia water heater (11) is connected to the steam drum (7) via the riser heat exchanger (5).

2. The coking ammonia distillation system according to claim 1, characterized in that: The riser waste heat system also includes a desalted water tank (1) and a deaerator (3) which are connected in sequence, and the deaerator (3) is connected to the steam drum (7) via a feed water pump (4).

3. The coking ammonia distillation system according to claim 1, characterized in that: The steam drum (7) is provided with a forced circulation pump (6), and the steam drum (7) is connected to the heat exchange channel inlet of the ammonia water heater (11) through the forced circulation pump (6).

4. The coking ammonia distillation system according to claim 3, characterized in that: The riser waste heat system is provided in two sets, and cut-off valves are provided on the connecting pipe between the forced circulation pump (6) and the heat exchange channel inlet of the ammonia water heater (11), and on the connecting pipe between the heat exchange channel outlet of the ammonia water heater (11) and the riser heat exchanger (5).

5. The coking ammonia distillation system according to claim 4, characterized in that: The steam drum (7) is also connected to the steam network, and a cut-off valve is provided on the connecting pipeline between the forced circulation pump (6) and the riser heat exchanger (5).

6. The coking ammonia distillation system according to claim 1, characterized in that: A shut-off valve is provided on the parallel pipeline between the ammonia water heater (11) and the tubular furnace (10).

7. The coking ammonia distillation system according to claim 1, characterized in that: The ammonia water heater (11) is a shell-and-tube heat exchanger.

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