Preparation system of high-pressure steam for production of synthetic ammonia

Abstract

The utility model discloses a preparation system of high-pressure steam for synthesis ammonia production, and belongs to the technical field of synthesis ammonia. The system comprises a boiler, a deaerator, a desalted water preparation device, a slag extractor, a slag cooler, a drain expansion heat exchanger, a deaerator emptying heat exchanger, a drain expansion device and a drain tank. A cold water inlet of the slag extractor is connected with the desalted water preparation device; a cold water inlet of the drain expansion heat exchanger is connected with a hot water outlet of the slag cooler, a hot water outlet of the drain expansion heat exchanger is connected with a cold water inlet of the deaerator emptying heat exchanger, a steam inlet of the drain expansion heat exchanger is connected with an outlet of the drain expansion device, and a condensate water outlet of the drain expansion heat exchanger is connected with the drain tank; a steam inlet of the deaerator emptying heat exchanger is connected with an exhaust port of the deaerator, and a condensed water outlet of the deaerator emptying heat exchanger is connected with the blowdown cooling pool; the steam trap is connected with an inlet of the drain flash tank; a water inlet of the deaerator is connected with a hot water outlet of the conversion section, a hot water outlet of the deaerator emptying heat exchanger and the drain tank, and a steam inlet of the deaerator is connected with a steam outlet of the conversion section.

Description

TECHNICAL FIELD

[0001] The utility model belongs to synthetic ammonia technical field, especially relate to a preparation system of high pressure steam for synthetic ammonia production, the steam of preparation is used in air separation section (mainly) and synthetic section steam turbine generates electricity. BACKGROUND

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

[0003] The sulfur-tolerant shift process refers to the CO shift reaction of raw gas (including CO, H2, CO2, H2S, etc.) obtained by coal gasification, etc. with steam on a catalyst to generate hydrogen and carbon dioxide to obtain synthesis gas for ammonia production. The shift device produces a large amount of shift hot water (temperature about 130℃), which can be used as boiler feed water.

[0004] A patent with application number CN202210704515.4 discloses a sulfur-resistant shift process optimization method. After the crude synthesis gas from coal gasification is washed, it enters the shift system first. The raw gas is separated by a raw gas separator to remove the water entrained in the previous system. The coal gas enters the coal gas preheater tube side and exchanges heat with the shift gas from the steam superheater. Then it is divided into three streams. The first stream enters the pre-shift furnace. The second stream is controlled by the first flow regulating valve to distribute the load. The distributed coal gas enters the second quenching filter and mixes with the shift gas from the steam superheater, and then enters the second shift furnace for reaction. The third stream of gas enters the first shift furnace after being adjusted by the fourth temperature regulating valve to control the reaction temperature of the first shift furnace. The normal inlet temperature of the pre-shift furnace is controlled at 200-240℃. The process gas temperature out of the pre-shift furnace rises to 300-350℃. The process gas out of the pre-shift furnace is sprayed into the first quenching filter with process condensate through the third temperature regulating valve, and the temperature is controlled at 210-240℃. The shift gas out of the first quenching filter is controlled by the second flow regulating valve to add saturated medium-pressure steam, and then enters the steam mixer. After the shift gas out of the steam mixer mixes with the crude coal gas out of the coal gas preheater in the pipeline, the temperature is controlled at 200-250℃ by the fourth temperature regulating valve, and then enters the first shift furnace for shift reaction. The temperature of the shift gas out of the first shift furnace is controlled by the fourth temperature regulating valve to rise to 440-470℃, and the CO content is reduced to 7-10% (vol, dry basis). The 240-270℃ saturated medium-pressure steam is superheated to 370-430℃ in the steam superheater and sent to the medium-pressure steam main pipe. The shift gas out of the steam superheater tube side enters the coal gas preheater shell side and exchanges heat with the crude coal gas. The shift gas entering the coal gas preheater shell side is controlled by the second temperature control valve to control the inlet temperature of the pre-shift furnace. The shift gas after heat exchange by the coal gas preheater mixes with the crude coal gas distributed by the first flow regulating valve and enters the second quenching filter. The amount of process condensate sprayed into the second quenching filter is controlled by the fifth temperature regulating valve to cool the shift gas to 200-220℃, and then the shift gas enters the second shift furnace for shift reaction. After the shift in the second shift furnace, the outlet temperature of the second shift furnace rises to 340-370℃, and the CO content is reduced to 2-3.5% (vol, dry basis). Then the shift gas enters the third quenching filter, and the condensate is sprayed into the third quenching filter by the sixth temperature regulating valve to cool the shift gas to 200-220℃, and then the shift gas enters the third shift furnace for reaction. The outlet temperature of the third shift furnace rises to 215-240℃, and the CO content is reduced to 0.5-1.5% (vol, dry basis). Low-pressure steam is generated in the low-pressure waste heat boiler to recover heat, and the pressure of the low-pressure steam is 0.35-0.55MPa. The liquid level of the low-pressure boiler is controlled by the third liquid level regulating valve, and the steam output is controlled by the first pressure regulating valve to maintain the pressure of the waste heat boiler at 0.35-0.55MPa, for low temperature methanol washing system, the temperature of the shift gas after the waste boiler is reduced to 160-180℃, and the shift gas enters two parallel desalted water preheaters to preheat the desalted water; in order to prevent the desalted water from being gasified and overpressured in the equipment, causing damage to the equipment and pipelines, the desalted water heated by the desalted water preheater is sent to a heat and power deaerator and a coal gasification deaerator respectively, and a liquid level regulating valve of the deaerator is arranged on the inlet pipeline of the desalted water preheater; the desalted water preheater is provided with a process gas bypass, and a valve is arranged at the inlet of the heat exchanger; according to the running condition of the device and the distribution of the desalted water, the outlet temperature of the desalted water is adjusted, and the desalted water is heated from 30-50℃ to 105-135℃.

[0005] The patent with application number CN202310885988.3 discloses an energy-saving and efficient adjustable alcohol pre-gas ammonia production process, which specifically comprises the following steps: S1, a raw material gas is separated from a pressurized coal gasification methanol device as alcohol pre-gas and sent to a shift device of ammonia synthesis through a sealed pipeline; S2, when entering the shift device, the alcohol pre-gas is mixed with the crude synthesis gas to form a mixed gas, and then high-pressure steam is introduced to adjust the water-gas ratio and increase the mixed temperature, and in the shift device, carbon monoxide reacts with water vapor to produce hydrogen gas as shift gas; S3, the shift gas is subjected to low-temperature methanol washing and liquid nitrogen washing, and then nitrogen gas produced by air separation is added to form synthesis gas and sent to an ammonia synthesis device.

[0006] The patent with application number CN202322703494.7 discloses a synthetic ammonia shift cycle cooling system, which comprises a coal gas pipeline connected with the inlet of a gas-liquid separator, a gas phase outlet of the gas-liquid separator connected with a first shift furnace through a tube side of a raw material gas preheater, an outlet of the first shift furnace connected with an inlet of a second shift furnace through a steam superheater, a shell side of the raw material gas preheater and a tube side of a steam generator, and an outlet of the second shift furnace connected with a washing ammonia tower through a cooling heat exchanger, and a gas phase outlet of the washing ammonia tower connected with a methanol washing system.

[0007] However, the shift hot water is not enough to meet the feed water requirement of the boiler, and accounts for 3 / 4 of the feed water requirement of the boiler. Therefore, desalted water needs to be additionally supplemented. The desalted water needs to be heated and deaerated by a deaerator first, and then sent to the boiler as boiler feed water. SUMMARY

[0008] In order to solve the foregoing problems, the embodiments of the present application provide a preparation system of high-pressure steam for synthetic ammonia production, which utilizes the shift hot water and low-pressure steam of a shift section to prepare high-pressure steam, and simultaneously recovers the heat of slag, the condensate (including heat) of a trap and the heat of deaerator exhaust gas, thereby reducing energy consumption and water consumption. The technical solution is as follows:

[0009] The utility model discloses an embodiment provides a preparation system of high pressure steam for synthetic ammonia production, including boiler, deaerator, desalted water preparation device, slag extractor and cold slag machine, the slag outlet of boiler, slag extractor and cold slag machine are connected in proper order, be equipped with trap on the output pipeline of boiler, its characterized in that, this system still includes hydrophobic expansion heat exchanger, deaerator venting heat exchanger, hydrophobic expansion vessel and hydrophobic tank, the cold water import of slag extractor is connected with desalted water preparation device through the pipeline, the cold water import of hydrophobic expansion heat exchanger is connected with the hot water export of cold slag machine through the pipeline, and its hot water export is connected with the cold water import of deaerator venting heat exchanger through the pipeline, and its steam import is connected with the export of hydrophobic expansion vessel through the pipeline, and its condensed water export is connected with hydrophobic tank through the pipeline, the steam import of deaerator venting heat exchanger is connected with the exhaust port of deaerator through the pipeline, and its condensed water export is connected with the blowdown cooling pool through the pipeline, the trap is connected with the import of hydrophobic expansion vessel through the pipeline, the water import of deaerator is connected with the hot water export of shift section, the hot water export of deaerator venting heat exchanger and hydrophobic tank through the pipeline, and its steam import is connected with the steam export of shift section through the pipeline.

[0010] Further, the water inlet of the deaerator is also connected with the desalted water preparation device through the pipeline.

[0011] The hydrophobic expansion heat exchanger and the deaerator venting heat exchanger are both shell-and-tube heat exchangers.

[0012] The heat exchanger area of the hydrophobic expansion heat exchanger is 1 / 2-4 / 5 of the heat exchange area of the deaerator venting heat exchanger.

[0013] Specifically, the heat exchanger area of the hydrophobic expansion heat exchanger is 30m 2 , the heat exchanger area of the deaerator venting heat exchanger is 40m 2 , the volume of the hydrophobic tank is 30m 3 , and the volume of the hydrophobic expansion vessel is 1m 3 .

[0014] The embodiment of the utility model provides a preparation system of high pressure steam for synthetic ammonia production, utilize the conversion heat water and low pressure steam of conversion section to prepare high pressure steam, recover the heat of slag, the condensate (including heat) of drain trap and the heat of deaerator exhaust simultaneously, reduce energy consumption and water consumption, realize the comprehensive utilization of water and heat in synthetic ammonia system. Can reduce the dosage of desalted water. Adopt desalted water as the cooling water of slag cooler, not easy to scale. In addition, desalted water is first heated to about 30 DEG C, then heated to about 50 DEG C, and then heated to about 95 DEG C, the temperature difference is not very high, the requirement of heat exchanger is low, and common column tube heat exchanger can be adopted. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the principle diagram of the preparation system of high pressure steam for synthetic ammonia production provided by the embodiment 1. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantage of the utility model more clear, the utility model will be described further in detail below in combination with the drawings.

[0017] Embodiment 1

[0018] See Figure 1The preparation system for high-pressure steam for synthetic ammonia production provided by the embodiment 1 comprises a boiler, a deaerator, a desalted water preparation device, a slag discharger, a slag cooler, a drain expansion heat exchanger, a deaerator venting heat exchanger, a drain expansion vessel and a drain tank, etc. The slag discharge port of the boiler, the slag discharger and the slag cooler are sequentially connected to realize slag discharge and slag cooling, and the water cooling heat exchanger is arranged in the slag cooler. The drain trap is arranged on the boiler and its output pipeline (for example, at the low position of the pipeline, the bending position of the pipeline, etc.). The cold water inlet of the drain expansion heat exchanger is connected with the hot water outlet of the slag cooler (specifically, the hot water outlet of the water cooling heat exchanger, and the temperature of the output hot water is about 30 DEG C) through a pipeline, the hot water outlet (the temperature of the output hot water is about 50 DEG C) of the drain expansion heat exchanger is connected with the cold water inlet of the deaerator venting heat exchanger through a pipeline, the steam inlet of the drain expansion heat exchanger is connected with the outlet of the drain expansion vessel (output steam, and the temperature of the steam is about 120 DEG C) through a pipeline, and the condensate outlet of the drain expansion heat exchanger is connected with the drain tank through a pipeline. The steam inlet of the deaerator venting heat exchanger is connected with the exhaust port of the deaerator (output steam with a temperature of 130 DEG C) through a pipeline, and the condensate outlet (output condensate water with a temperature of 90 DEG C, and the condensate water is rich in oxygen) of the deaerator venting heat exchanger is connected with the blowdown cooling pool through a pipeline. The drain trap (output steam-water mixture with high pressure, which cannot be directly used by the deaerator) is connected with the inlet of the drain expansion vessel through a pipeline, the drain expansion vessel is used for controlling pressure and steam-water separation, and the drain expansion heat exchanger can be used. The water inlet of the deaerator is connected with the hot water outlet of the shift section (output shift hot water with a temperature of about 130 DEG C), the hot water outlet of the deaerator venting heat exchanger (output desalted water with a temperature of about 95 DEG C), the drain tank (output condensate water with a temperature of 70-80 DEG C) and the desalted water preparation device (output normal-temperature desalted water, and usually no output) through a pipeline with a valve (selected and controlled). The steam inlet of the deaerator is connected with the steam outlet of the shift section (specifically, low-pressure steam with a pressure of 0.6 Mpa, and the steam outlet is specifically the steam outlet of the waste heat boiler, if the steam is insufficient, the low-pressure steam pipe network is supplemented, and then the low-pressure steam pipe network is usually output to the deaerator). Usually, the valve on the pipeline between the water inlet of the deaerator and the desalted water preparation device is closed. That is, the water supply of the deaerator mainly includes three aspects, that is, the shift hot water (with a temperature of about 130 DEG C) output by the shift section (mainly), the desalted water (with a temperature of about 95 DEG C) output by the deaerator venting heat exchanger (secondarily), and the condensate water (with a temperature of about 70-80 DEG C) output by the drain tank.

[0019] In the embodiment of the utility model, the drain expansion heat exchanger and the deaerator venting heat exchanger are both column tube heat exchangers, and the heat exchange area of the drain expansion heat exchanger is 1 / 2-4 / 5 of the heat exchange area of the deaerator venting heat exchanger.

[0020] The working process of the system is as follows: the desalted water (calculated at 20 DEG C) is heated to about 30 DEG C in the slag cooler, then heated to about 50 DEG C in the drain expansion heat exchanger, then heated to about 95 DEG C in the deaerator vent heat exchanger, then heated and deaerated in the deaerator, and finally sent to the boiler. The condensate water generated by the boiler and its pipe network is collected by the drain collector, separated into steam and water by the drain expansion vessel, and then the steam separated from the water is changed into 70-80 DEG C condensate water by the drain expansion heat exchanger. The condensate water is finally sent to the deaerator. The 130 DEG C non-condensable gas and steam discharged from the deaerator are sent to the deaerator vent heat exchanger, and the condensate water output by the deaerator vent heat exchanger is discharged or used as process water. The shift heat water and the surplus low-pressure steam (directly introduced into the deaerator) of the shift section are sent to the deaerator for thermal deaeration.

[0021] Embodiment 2

[0022] Embodiment 2 provides a preparation system of high-pressure steam for synthetic ammonia production, which has basically the same structure as that of Embodiment 1, except that the heat exchanger area of the drain expansion heat exchanger in this embodiment is 30 m 2 , the heat exchanger area of the deaerator vent heat exchanger is 40 m 2 , the volume of the drain tank is 30 m 3 , and the volume of the drain expansion vessel is 1 m 3 . The shift heat water output by the shift section is 250 tons, the desalted water output by the deaerator vent heat exchanger is 80 tons, and the condensate water output by the drain tank is less than 10 tons.

[0023] Embodiment 3

[0024] Embodiment 3 provides a preparation system of high-pressure steam for synthetic ammonia production, which has basically the same structure as that of Embodiment 1, except that the boiler in this embodiment uses coal as a heat source, and the steam pressure output by the boiler is 9.8 Mpa. The steam output to the air separation section (mainly) and the steam turbine of the synthesis section is used for power generation. The reduced-pressure steam is changed into low-pressure steam by a series of treatments (such as heat exchange or pressure reduction) and then input into the low-pressure steam pipe network. The steam outlet of the shift section is connected to the low-pressure steam pipe network by a pipeline, and the steam inlet of the deaerator is connected to the low-pressure steam pipe network by a pipeline, that is, the low-pressure steam pipe network provides steam for the deaerator.

[0025] In this embodiment, pumps, flow meters or valves are arranged on the pipelines between the structures as needed.

[0026] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A system for preparing high-pressure steam for synthetic ammonia production, comprising a boiler, a deaerator, a desalted water preparation device, a slag discharger and a slag cooler, the slag discharge port of the boiler, the slag discharger and the slag cooler being connected in sequence, and a drain trap being provided on the boiler and its output pipeline; characterized in that, The system further comprises a hydrophobic expansion heat exchanger, a deaerator vent heat exchanger, a hydrophobic expander and a hydrophobic tank, the cold water inlet of the deslagging machine is connected with the desalted water preparation device through a pipeline; the cold water inlet of the hydrophobic expansion heat exchanger is connected with the hot water outlet of the cold deslagging machine through a pipeline, the hot water outlet is connected with the cold water inlet of the deaerator vent heat exchanger through a pipeline, the steam inlet is connected with the outlet of the hydrophobic expander through a pipeline, and the condensate water outlet is connected with the hydrophobic tank through a pipeline; the steam inlet of the deaerator vent heat exchanger is connected with the exhaust port of the deaerator through a pipeline, and the condensate water outlet is connected with the blowdown cooling pond through a pipeline; the hydrophobic expander is connected with the inlet of the hydrophobic expander through a pipeline; the water inlet of the deaerator is connected with the hot water outlet of the shift section, the hot water outlet of the deaerator vent heat exchanger and the hydrophobic tank through a pipeline, and the steam inlet is connected with the steam outlet of the shift section through a pipeline.

2. The preparation system of high-pressure steam for synthetic ammonia production according to claim 1, characterized by, The water inlet of the deaerator is also connected with the desalted water preparation device through a pipeline.

3. The preparation system of high-pressure steam for synthetic ammonia production according to claim 1, characterized by, The hydrophobic expansion heat exchanger and the deaerator vent heat exchanger are both shell-and-tube heat exchangers.

4. The preparation system of high-pressure steam for synthetic ammonia production according to claim 1, characterized by, The heat exchanger area of the hydrophobic expansion heat exchanger is 1 / 2-4 / 5 of the heat exchange area of the deaerator vent heat exchanger.

5. The preparation system of high-pressure steam for synthetic ammonia production according to claim 1 or 4, characterized by, The heat exchanger area of the hydrophobic expansion heat exchanger is 30m 2 The heat exchanger area of the deaerator vent heat exchanger is 40m 2 The volume of the hydrophobic tank is 30m 3 The volume of the hydrophobic expansion tank is 1m 3 .

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