Processing device for surplus cooling capacity of liquid nitrogen wash

Abstract

The utility model discloses a liquid nitrogen wash surplus cooling capacity treatment device, and belongs to the technical field of synthesis ammonia. The device comprises a buffer tank, a tubular heat exchanger and a water bath vaporizer, the cold box pipeline is divided into two paths for output, one path is connected with the buffer tank, and the other path is connected with a liquid inlet of the water bath vaporizer; the buffer tank, the shell-and-tube heat exchanger and the torch header pipe are sequentially connected; a gas outlet of the water bath vaporizer is connected with a torch header pipe through a pipeline, and a cold water outlet is connected with a reflux inlet of a surface air cooler of the steam turbine through a pipeline; a condensate water outlet of the surface air cooler is divided into two paths for simultaneous output, one path is connected with a condensate water storage tank through a pipeline, and the other path is connected with a hot water inlet of the water bath vaporizer through a pipeline; when the water bath vaporizer can work normally, the cold box pipeline gate is connected with the water bath vaporizer; and when the water bath vaporizer cannot work normally, the cold box pipeline is gated to be connected with the buffer tank. Return water of the surface air cooler can be cooled to utilize cold energy, and steam consumption is reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to synthetic ammonia technical field, especially relate to a kind of processing device of liquid nitrogen wash surplus cold quantity, according to cold quantity calculation, the backwater of surface cooling device can be cooled, to utilize cold quantity. BACKGROUND

[0002] Ammonia is an important raw material for chemical products, and is one of the main raw materials for chemical fertilizers. The demand for ammonia in China is huge. Therefore, the process of synthesizing ammonia from coal as raw material gasification has gradually become popular.

[0003] Liquid nitrogen washing is the last purification process upstream of ammonia synthesis. The main function of liquid nitrogen washing is to remove carbon monoxide, argon and methane and other residual impurities in crude hydrogen, and adjust the stoichiometric ratio of nitrogen and hydrogen to 1:3. The cold energy required by the liquid nitrogen washing process is provided by the throttling expansion of high-pressure nitrogen gas, i.e. the Joule-Thomson effect (J-T effect). During normal operation of the device, the system has abundant cold energy, and the abundant cold energy is mainly in the form of liquid fuel gas that has absorbed carbon monoxide, argon and methane and other impurities, and is discharged at a temperature of about -190℃. It is usually heated to normal temperature by steam and then discharged to the flare for combustion.

[0004] For example, patent No. CN201410491444.X discloses a method for heating liquid nitrogen washing fuel gas in synthetic ammonia production. A coil is arranged in the circulating water tank of the circulating water system of the synthetic ammonia production process as a heat exchanger. The liquid nitrogen washing fuel gas obtained from the synthetic ammonia liquid nitrogen washing process is introduced into the coil, and the water in the circulating water tank is used as a heat source to heat the liquid nitrogen washing fuel gas. The temperature of the liquid nitrogen washing fuel gas is raised to 10℃-33℃, and then it is transported to the flare main pipe.

[0005] A patent with application number CN202123349729.4 discloses a torch gas collection and processing device, which comprises a torch, a cold box pipeline, a cold torch gas collection pipeline, a normal temperature torch gas collection pipeline, a heat exchanger, a buffer tank, a nitrogen supply structure, and a spray heating structure. The initial end of the cold box pipeline, the initial end of the cold torch gas collection pipeline, and the initial end of the normal temperature torch gas collection pipeline are all connected with the nitrogen supply structure. The terminal end of the cold box pipeline is connected with the buffer tank. The waste outlet of the liquid nitrogen washing cold box is connected with the cold box pipeline. The buffer tank is connected with the cold gas inlet of the heat exchanger through a first pipeline. The cold torch gas collection pipeline is used for collecting cold torch gas, and its terminal end is connected with the first pipeline. The hot gas outlet of the heat exchanger is connected with the torch through a second pipeline. The normal temperature torch gas collection pipeline is used for collecting normal temperature torch gas, and its terminal end is connected with the second pipeline. The hot gas inlet of the heat exchanger is connected with the low-pressure steam pipe network of the synthetic ammonia production system. The buffer tank comprises a horizontal tank arranged along the front and back directions and two support foundations arranged side by side at the bottom of the horizontal tank. The spray heating structure is located directly below the horizontal tank and between the two support foundations. The spray heating structure is connected with the low-pressure steam pipe network and sprays steam to the bottom of the horizontal tank.

[0006] A patent with application number CN201621461835.8 discloses a liquid nitrogen washing fuel gas discharge treatment system, which comprises a coiled tube heat exchanger. The shell side inlet of the heat exchanger is connected with a regenerated tower steam condensate discharge main pipe. The tube side inlet of the heat exchanger is connected with a liquid nitrogen washing fuel gas discharge main pipe. The tube side outlet of the heat exchanger is connected with a torch main pipe.

[0007] When the applicant heats the overflow liquid nitrogen of the nitrogen washing tower of the cold box through the heat exchanger, the following problems are found:

[0008] (1) Waste of cold energy;

[0009] (2) The temperature of the liquid nitrogen is -190℃, and the ordinary tube heat exchanger is not durable at low temperature. Specifically, the temperature difference between the two sides of the tube is large, which easily leads to steam leakage to the shell side at the welded part of the tube, thereby causing water accumulation in the heat exchanger and waste of steam. In addition, the buffer tank needs to be heated and deiced by steam all the year round due to the frost hanging on the cold liquid discharge, which wastes steam and manpower. SUMMARY

[0010] In order to solve the foregoing problems, the utility model embodiment provides a kind of processing device of liquid nitrogen washing surplus cold energy, utilize the water bath vaporizer specially processing low temperature liquid, can be used at low temperature;Simultaneously, according to the cold energy calculation, the backwater of surface cooler can be cooled to utilize cold energy, reduce steam consumption.The technical scheme is as follows:

[0011] The utility model discloses an embodiment of a kind of liquid nitrogen washs processing device of surplus cold quantity, and the device includes buffer tank, column tube heat exchanger and water bath vaporizer;Cold box pipeline is two-way alternative output, one way is connected with buffer tank, another way is connected with the liquid import of water bath vaporizer;The buffer tank, column tube heat exchanger and torch main pipe are sequentially connected by pipeline;The gas outlet of water bath vaporizer is connected with torch main pipe by pipeline, and its cold water outlet is connected with the backflow port of surface cooler of steam turbine by pipeline;The condensate outlet of surface cooler is two-way simultaneous output, one way is connected with condensate storage tank by pipeline, and another way is connected with the hot water import of water bath vaporizer by pipeline;When water bath vaporizer can work normally, the cold box pipeline is connected with water bath vaporizer, at this time, the column tube heat exchanger does not work;When water bath vaporizer can not work normally, the cold box pipeline is connected with buffer tank, at this time, the column tube heat exchanger works.

[0012] Specifically, the surface cooler in the utility model embodiment includes synthetic gas compressor surface cooler and ammonia compressor surface cooler, and the corresponding steam turbines of the synthetic gas compressor surface cooler and the ammonia compressor surface cooler are connected with the boiler by pipelines.

[0013] Further, the condensate storage tank, the boiler feed water treatment device and the boiler in the utility model embodiment are sequentially connected by pipelines, the steam outlet of the boiler is connected with the high-pressure steam pipe network, and the steam inlets of the steam turbine of the synthetic section and the steam turbine of the ammonia compression section are connected with the high-pressure steam pipe network.

[0014] Specifically, the water bath vaporizer in the utility model embodiment has a specification of Φ1900mm*4400mm, a heat exchange area of 101m 2 , a working pressure of 0.8Mpa and a gasification amount of 17000Nm 3 / h.

[0015] The water bath vaporizer in the utility model embodiment includes 304 stainless steel tube and austenitic stainless steel shell.

[0016] Preferably, the buffer tank in the utility model embodiment is a horizontal tank, and a spray heating structure is arranged directly below the buffer tank, and the steam inlets of the column tube heat exchanger and the spray heating structure are connected with the low-pressure steam pipe network by pipelines.

[0017] Preferably, when the water bath vaporizer can work normally, the condensate outlet of the surface cooler is three-way output, the first way is connected with the condensate storage tank by pipeline and is opened, the second way is connected with the hot water import of the water bath vaporizer by pipeline and is opened, and the third way is directly connected with the backflow port of the surface cooler by pipeline and is closed.

[0018] The technical scheme provided by the embodiment of the utility model has the beneficial effects that the embodiment of the utility model provides a processing device for surplus cold quantity of liquid nitrogen washing, uses the water bath vaporizer for processing low-temperature liquid, can resist low temperature and use, and will not appear the situation of leakage; meanwhile, according to the calculation of cold quantity and water quantity, the backwater of the surface cooler (after calculation, needs to adopt synthetic section steam turbine and ammonia compression section steam turbine) can be cooled to utilize the cold quantity and reduce the steam consumption.In addition, the buffer tank and the tube heat exchanger of the prior art can be retained, and the water bath vaporizer (such as abnormal or maintenance) cannot be used when liquid nitrogen is heated to normal temperature gas. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the principle block diagram of the processing of the surplus cold quantity of the prior art liquid nitrogen washing;

[0020] Figure 2 is the principle block diagram of the prior art steam turbine driving compressor;

[0021] Figure 3 The principle block diagram of the processing device for surplus cold quantity of liquid nitrogen washing disclosed by the embodiment of the utility model. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model will be further described in detail in combination with the drawings.

[0023] Embodiment 1

[0024] See Figure 3, the embodiment 1 provides a liquid nitrogen washing surplus cold quantity processing device, the device includes buffer tank, column tube heat exchanger and water bath vaporizer etc.. The cold box pipeline (output by the nitrogen washing tower of the cold box, output-190 DEG C liquid nitrogen) is connected with the buffer tank in two ways (controlled by the valve), one way is connected with the water bath vaporizer liquid inlet, the buffer tank, column tube heat exchanger and torch main pipe are sequentially connected by pipeline. The gas outlet of the water bath vaporizer is connected with the torch main pipe (for burning treatment gas, including various tail gas of synthetic ammonia) through pipeline, and the cold water outlet of the water bath vaporizer is connected with the return port of the surface cooler of the steam turbine (by high-pressure steam) through pipeline. The condensate tank, boiler feed water treatment device (including ion exchange bed and deaerator, etc., for treating the condensate to meet the requirements of boiler feed water, which is a conventional structure) and boiler are sequentially connected by pipeline, and the steam outlet of the boiler is connected with the high-pressure steam pipe network. The high-pressure steam pipe network outputs high-pressure steam to the steam turbine, and the condensate outlet of the surface cooler of the steam turbine is divided into three paths, the first path is connected with the condensate tank (always open) through pipeline, the second path is connected with the hot water inlet of the water bath vaporizer (always open, closed according to requirements) through pipeline, and the third path is directly connected with the return port of the surface cooler (always closed, used when the water bath vaporizer is abnormal, controlled by the valve; it is a pipeline reserved in the prior art itself). The steam turbine can be one or more of the steam turbine of the synthesis section, the steam turbine of the ammonia compression section, the steam turbine of the air separation section and the steam turbine of the shift section.

[0025] When the water bath vaporizer can work normally, the cold box pipeline is connected with the water bath vaporizer; at this time, the column tube heat exchanger does not work, the water bath vaporizer works, and the third path is closed and the second path is opened. When the water bath vaporizer cannot work normally (such as abnormal or maintenance), the cold box pipeline is connected with the buffer tank; at this time, the column tube heat exchanger works, the water bath vaporizer does not work, the third path is opened, and the second path is closed.

[0026] In the patent, the water bath vaporizer can heat the liquid nitrogen to room temperature. The cold water temperature sent by the water bath vaporizer to the surface cooler is about 20 DEG C, which can obviously reduce the temperature of the condensate water output by the surface cooler (to 45-65 DEG C) within the optimized working temperature range of the boiler feed water treatment device.

[0027] In the embodiment of the utility model, the water bath vaporizer includes 304 stainless steel tube and austenitic stainless steel shell (material 06cr19ni10), and the setting mode is the same as the prior art.

[0028] Preferably, the buffer tank in this embodiment is a horizontal tank with a spray heating structure directly below it (to prevent the buffer tank from freezing), as described in application number CN202123349729.4. The steam inlets of both the tube heat exchanger and the spray heating structure are connected to the low-pressure steam network via pipelines.

[0029] Example 2

[0030] Example 2 provides a liquid nitrogen washing excess cooling capacity treatment device, whose structure is basically the same as that of Example 1, except that: the surface cooler in this example includes a syngas compressor surface cooler (located on the turbine of the synthesis section, the turbine drives the corresponding compressor) and an ammonia compressor surface cooler (located on the turbine of the ammonia compression section, the turbine drives the corresponding compressor). The turbines corresponding to the syngas compressor surface cooler (corresponding to the turbine of the synthesis section) and the ammonia compressor surface cooler (corresponding to the turbine of the ammonia compression section) are both connected to the high-pressure steam pipeline network, which is connected to the boiler. The condensate outlets of the syngas compressor surface cooler and the ammonia compressor surface cooler (both outputting condensate at 45-65℃) are both connected to the condensate storage tank through pipelines.

[0031] Example 3

[0032] Example 3 provides a device for treating excess cold energy from liquid nitrogen washing. Its structure is basically the same as that of Example 1, except that the water bath vaporizer (for a 300,000-ton synthetic ammonia production line) in this example has dimensions of Φ1900mm*4400mm and a heat exchange area of ​​101m². 2 The working pressure is 0.8 MPa, and the gasification capacity is 17000 Nm³. 3 / h, motor power is 1.5KW; from Hangzhou Hangyang Cryogenic Container Co., Ltd.

[0033] In this embodiment, the terms "first," "second," and "third" serve only as distinctions and have no other special meaning. Pumps, flow meters, or valves may be installed on the pipelines connecting the various structures as needed.

[0034] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for processing the surplus cold of liquid nitrogen washing, comprising a buffer tank and a shell-and-tube heat exchanger; characterized in that, The water bath vaporizer is further included; the cold box pipeline is connected with the buffer tank in one way and connected with the liquid inlet of the water bath vaporizer in another way; the buffer tank, the tube heat exchanger and the torch main pipe are sequentially connected through pipelines; the gas outlet of the water bath vaporizer is connected with the torch main pipe through a pipeline, and the cold water outlet of the water bath vaporizer is connected with the backflow port of the surface cooler of the steam turbine through a pipeline; the condensate water outlet of the surface cooler is simultaneously output in two ways, one way is connected with the condensate water storage tank through a pipeline, and the other way is connected with the hot water inlet of the water bath vaporizer through a pipeline; When the water bath vaporizer works normally, the cold box pipeline is connected with the water bath vaporizer, at this time, the tube heat exchanger does not work; when the water bath vaporizer cannot work normally, the cold box pipeline is connected with the buffer tank, at this time, the tube heat exchanger works.

2. The liquid nitrogen wash excess cold quantity processing device according to claim 1, wherein, The surface cooler includes a syngas compressor surface cooler and an ammonia compressor surface cooler, the corresponding steam turbines of the syngas compressor surface cooler and the ammonia compressor surface cooler are connected with the boiler through pipelines, and the condensate water outlets of the syngas compressor surface cooler and the ammonia compressor surface cooler are connected with the condensate water storage tank through pipelines.

3. The liquid nitrogen excess cold handling device according to claim 2, wherein, The condensate water storage tank, the boiler feed water treatment device and the boiler are sequentially connected through pipelines, the steam outlet of the boiler is connected with the high-pressure steam pipe network, and the steam inlets of the steam turbines of the synthesis section and the ammonia compression section are connected with the high-pressure steam pipe network.

4. The liquid nitrogen excess cold handling device of claim 1, wherein, The water bath vaporizer has a size of Φ1900mm*4400mm, a heat exchange area of 101m 2 , a working pressure of 0.8Mpa, and a gasification amount of 17000Nm 3 / h.

5. The liquid nitrogen excess cold handling apparatus according to claim 1, wherein The water bath vaporizer includes a 304 stainless steel tube and an austenitic stainless steel shell.

6. The liquid nitrogen excess cold handling apparatus according to claim 1, wherein The buffer tank is a horizontal tank, and a spray heating structure is arranged directly below the buffer tank, the steam inlets of the tube heat exchanger and the spray heating structure are connected with the low-pressure steam pipe network through pipelines.

7. The liquid nitrogen excess cold handling apparatus according to claim 1, wherein When the water bath vaporizer works normally, the condensate water outlet of the surface cooler is output in three ways, the first way is connected with the condensate water storage tank through a pipeline and is opened, the second way is connected with the hot water inlet of the water bath vaporizer through a pipeline and is opened, and the third way is directly connected with the backflow port of the surface cooler through a pipeline and is closed.

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