A device and method for purifying crude ammonia and preparing liquid ammonia

Abstract

This invention discloses an apparatus and method for purifying crude ammonia and producing liquid ammonia. By using an acid gas scrubbing tower and an ammonia refining tower in combination, the process involves three stages of scrubbing crude ammonia in the acid gas scrubbing tower, ammonia refining in the ammonia refining tower, ammonia condensation in the ammonia cooler, and ammonia absorption in the ammonia absorber. This achieves multi-stage scrubbing at different temperatures within a single acid gas scrubbing tower unit, fixing the acidic gases in the ammonia to the liquid phase, thus reducing the acid content in the gaseous ammonia to <3 ppm. The ammonia refining tower further reduces the organic matter content in the gaseous ammonia to <10 ppm. This completely solves the quality problem of ammonia products, provides diversified ammonia products, shortens the process, and reduces energy consumption.

Description

Technical Field

[0001] The invention belongs to the field of ammonia purification, and in particular relates to a device and method for purifying crude ammonia and preparing liquid ammonia at the same time. Background Art

[0002] The quality of wastewater produced by different coal gasification technologies is different. The quality of ammonia nitrogen wastewater produced by fixed bed gasification technology is the most complex, often containing pollutants such as H2S, CO2, oils and phenols. The COD concentration in the wastewater before treatment is above 20000mg / L. This ammonia nitrogen wastewater is usually treated by steam stripping, and the ammonia resources are recovered after removing the acid gas. Conventional steam stripping processes include single-tower pressurized steam stripping and double-tower pressurized steam stripping. After multi-stage condensation, ammonia-containing steam obtains a high-concentration crude ammonia gas with a temperature of 50-60℃, a pressure of 0.2-0.3mPa (G), H2O>1.5% (wt), H2S>2000ppm, and organic matter (oils, phenols, etc.)>3000ppm. Due to the high content of H2S and organic matter (oils, phenols, etc.) in crude ammonia, it can only be used to produce low-quality concentrated ammonia water, which limits the use of ammonia products and affects the economic benefits of ammonia products. Summary of the invention

[0003] The technical scheme of the present invention is: a device for purifying crude ammonia and preparing liquid ammonia, comprising an acid gas washing tower, an ammonia refining tower, a lower washing circulation pump, a washing cooler, an upper washing circulation pump, an ammonia refining tower reboiler, an ammonia refining tower bottom metering pump, an ammonia cooler, a liquid ammonia tank, a liquid ammonia reflux pump, a liquid ammonia discharge pump, an ammonia absorber, an ammonia water tank, an ammonia water circulation pump, and an ammonia side line sewage pump;

[0004] The crude ammonia gas is connected to the lower part of the acid gas washing tower through a pipeline, the bottom of the acid gas washing tower is connected to the inlet of the washing cooler through a lower washing circulation pump, the outlet of the washing cooler is connected to the middle and lower part of the acid gas washing tower through a pipeline, and the outlet of the lower washing circulation pump is connected to the off-site raw material tank through a pipeline;

[0005] The middle part of the acid gas washing tower is connected to the middle and upper part of the acid gas washing tower through the upper washing circulation pump; the top of the acid gas washing tower is connected to the middle part of the ammonia refining tower through a pipeline, the bottom of the ammonia refining tower is connected to the inlet of the ammonia refining tower reboiler through a pipeline, the outlet of the ammonia refining tower reboiler is connected to the lower part of the ammonia refining tower through a pipeline, and the bottom of the ammonia refining tower is connected to the outside through the ammonia refining tower bottom metering pump;

[0006] The middle of the ammonia refining tower is connected to the middle of the acid gas washing tower through an ammonia side-line sewage pump, and the outlet of the middle and upper part of the ammonia refining tower is divided into two routes: one route is connected to the middle of the ammonia refining tower and the inlet pipeline of the ammonia side-line sewage pump through pipelines, and the other route is connected to the middle and lower part of the ammonia refining tower through pipelines;

[0007] The top of the ammonia refining tower is connected to the inlet of the ammonia cooler through a pipeline, the outlet of the ammonia cooler is connected to the top of the liquid ammonia tank through a pipeline, and the bottom of the liquid ammonia tank is divided into two paths through a liquid ammonia reflux pump: one path is connected to the top of the ammonia refining tower through a pipeline, and the other path is connected to the lower part of the absorption section of the ammonia absorber through a pipeline; the bottom of the liquid ammonia tank is connected to the liquid ammonia outside the boundary through a pipeline through a liquid ammonia discharge pump;

[0008] The desalted water is connected to the top of the absorption section of the ammonia absorber through a pipeline, and the bottom of the cooling section of the ammonia absorber is connected to the top of the ammonia water tank through a pipeline. The ammonia water tank is divided into three routes after passing through the ammonia water circulation pump: the first route is connected to the middle of the absorption section of the ammonia absorber through a pipeline, the second route is connected to the top of the acid gas washing tower through a pipeline, and the third route is connected to the ammonia water outside the boundary through a pipeline.

[0009] Furthermore, the ammonia absorber is divided into an absorption section and a cooling section. The absorption section is provided with two sections of fillers, the upper section is a desalted water primary absorption filler, and the lower section is a circulating absorption filler. The cooling section is below the absorption section and is a horizontal shell and tube heat exchanger.

[0010] Furthermore, the ammonia refining tower is divided into three sections: the upper section is the rectifying section, the middle section is the liquid collecting tank, and the lower section is the stripping section; an annular filler is arranged above the liquid collecting tank in the middle section.

[0011] A method for purifying crude ammonia and preparing liquid ammonia comprises the following steps:

[0012] The first step is to perform three-stage washing of crude ammonia in the acid gas washing tower.

[0013] The crude ammonia gas containing H2S and organic matter enters the lower part of the acid gas washing tower, and the washing liquid is drawn out from the bottom of the acid gas washing tower, pressurized by the lower washing circulation pump, and heat-exchanged with the off-site chilled water through the washing cooler. After its own temperature drops to 20-30°C, it enters the upper part of the lower packing of the acid gas washing tower, fully contacts with the crude ammonia gas containing H2S and organic matter, transfers mass and heat, absorbs the acid gas in the crude ammonia gas, and performs primary washing on the crude ammonia gas; the sulfur-containing ammonia liquid is regularly discharged from the outlet of the lower washing circulation pump into the off-site raw material tank for re-stripping; the washing liquid in the middle of the acid gas washing tower is introduced from the liquid collecting tank, pressurized by the upper washing circulation pump, and enters the upper part of the middle and upper packing of the acid gas washing tower, and performs secondary washing on the crude ammonia gas, and further removes the acid gas in the crude ammonia gas; the concentrated ammonia water from the ammonia water circulation pump enters from the top of the acid gas washing tower, performs tertiary washing on the crude ammonia gas, and serves as the supplementary liquid of the acid gas washing tower at the same time, and the ammonia gas content of the gas coming out from the top of the tower is less than 3ppm;

[0014] Step 2: Refining gaseous ammonia in an ammonia refining tower

[0015] The gaseous ammonia coming out of the top of the acid gas scrubbing tower enters from below the annular packing above the liquid collecting tank in the middle section of the ammonia refining tower, fully contacts with the liquid phase of part of the low-temperature rectification section from the upper section, and conducts mass and heat transfer. After the temperature is lowered, most of the organic matter and part of the ammonia in the ammonia are condensed, and the gas and liquid are separated. The liquid phase is collected in the liquid collecting tank and sent to the middle part of the acid gas scrubbing tower through the ammonia side line sewage pump. The gas phase enters the rectification section of the upper section, and fully contacts with the reflux liquid in the upper section packing, and conducts mass and heat transfer, and the gaseous ammonia is further concentrated; most of the liquid phase of the rectification section is introduced into the stripping section of the lower section through a pipeline, and ammonia in the organic matter and water is further extracted. The organic content of the gaseous ammonia coming out of the top of the tower is less than 10ppm;

[0016] Step 3: Condensation of ammonia in the ammonia cooler

[0017] The pure ammonia gas coming out from the top of the ammonia refining tower has a pressure of 0.15mPa (G) and a temperature of -13.5℃. It enters the ammonia cooler and is cooled to -25℃. The pure ammonia gas is condensed into liquid ammonia and enters the liquid ammonia tank. A part of it is pressurized by the liquid ammonia reflux pump and then enters the top of the ammonia refining tower for reflux. A part of it is pressurized by the liquid ammonia discharge pump and then sent out as a product. The other part is sent to the ammonia absorber to produce concentrated ammonia water.

[0018] Step 4: Absorb ammonia in the ammonia absorber

[0019] The liquid ammonia sent by the liquid ammonia reflux pump enters the ammonia absorber for ammonia absorption. The ammonia water indirectly exchanges heat with the chilled water to remove the absorption heat of ammonia. After being cooled, the ammonia water enters the ammonia water tank and is then pressurized by the ammonia water circulation pump and divided into three paths: the first path is used as the circulating absorption liquid and sent to the absorption section of the ammonia absorber for circulating ammonia absorption; the second path is used as the supplementary liquid of the acid gas scrubbing tower; the third path is selectively sent out as an ammonia water product.

[0020] Furthermore, the acid gas washing tower is divided into two sections, the upper and lower sections, which are separated by a liquid collecting tank. The lower section is provided with a first-stage circulating washing, and the circulating washing temperature is controlled to be 20°C ~ 30°C; the upper section is provided with two-stage washing: the first stage is circulating washing, and the circulating washing temperature is controlled to be 10°C ~ 15°C; the other stage is a single washing, and the primary washing liquid adopts finished concentrated ammonia water, which enters from the top of the acid gas washing tower, and at the same time, the acid gas washing tower is replenished with liquid, and the excess sulfur-containing ammonia liquid is regularly discharged into the raw material tank for re-stripping.

[0021] Furthermore, the primary circulation washing temperature of the lower section of the acid gas washing tower is controlled by the flow rate of chilled water in the washing cooler, and the chilled water temperature is <20°C. The primary circulation washing temperature of the upper section is controlled by the flow rate of liquid ammonia in the ammonia side line sewage pump, and the temperature is controlled at 10-15°C.

[0022] Furthermore, the heat source of the ammonia refining tower is provided by the ammonia refining tower reboiler, the heating medium is hot water, the pressure of the ammonia refining tower is controlled at 0.15mPa (G), the top temperature is -13.5°C, the bottom temperature is 60-65°C, and the organic content of the gas ammonia coming out from the top of the tower is <10ppm.

[0023] Furthermore, the absorption pressure of ammonia gas can be arbitrarily adjusted between 0 and 0.2 mPa (G), and the concentration of ammonia water is 20%wt to 40%wt.

[0024] Furthermore, the heat source of the ammonia refining tower is provided by the ammonia refining tower reboiler, the operating temperature of the ammonia refining tower kettle is 60-65°C, the heating medium is hot water, and the hot water temperature is greater than 85°C.

[0025] Furthermore, the ammonia cooler provides low temperature by gasifying the cold source liquid ammonia, and controls the pressure on the cold side of the ammonia cooler to ≤ 0.03 mPa (G) to ensure that the cold source provides sufficient temperature.

[0026] The present invention has the following beneficial effects

[0027] (1) The acid gas washing tower is divided into two sections, the upper and lower sections, which are separated by a liquid collecting tank. The lower section is provided with a first-stage circulating washing, and the circulating washing temperature is controlled at 20°C to 30°C. The upper section is provided with two-stage washing: the first stage is circulating washing, and the circulating washing temperature is controlled at 10°C to 15°C, and the other stage is a primary washing. The primary washing liquid adopts finished concentrated ammonia water, which enters from the top of the acid gas washing tower. At the same time, the acid gas washing tower is replenished with liquid, and the excess sulfur-containing ammonia liquid is regularly discharged into the raw material tank for re-stripping. The present invention realizes multi-stage washing at different temperatures in one device, fixes the acid gas in the ammonia gas in the liquid phase, and thus makes the acid gas content in the gaseous ammonia less than 3ppm.

[0028] (2) The primary circulation washing temperature in the lower section of the acid gas washing tower is controlled by the flow rate of chilled water in the washing cooler. The chilled water temperature is less than 20°C. The primary circulation washing temperature in the upper section is controlled by the flow rate of liquid ammonia in the ammonia side line sewage pump.

[0029] (3) The pressure of the ammonia refining tower is 0.15mPa (G), the top temperature is -13.5℃, and the bottom temperature is 60~65℃. It is divided into three sections: upper, middle and lower. An annular packing is set above the liquid collecting box of the middle section. The desulfurized ammonia enters from the bottom of the annular packing and fully contacts with the liquid phase of part of the low-temperature distillation section from the upper section, mass transfer and heat transfer. After the temperature is lowered, most of the organic matter and part of the ammonia in the ammonia are condensed, and the gas and liquid are separated. The liquid phase is collected in the liquid collecting box and sent to the middle part of the acid gas washing tower through the ammonia side line sewage pump. The gas phase enters the distillation section of the upper section of the ammonia refining tower and fully contacts with the reflux liquid in the upper section packing, mass transfer and heat transfer, and the gas ammonia is further concentrated; most of the liquid phase of the distillation section is introduced into the stripping section of the lower section through a pipeline to further extract the ammonia from the organic matter and water, so that the organic matter content in the gas ammonia is less than 10ppm.

[0030] (4) The pure ammonia gas coming out from the top of the ammonia refining tower has a pressure of 0.15mPa (G) and a temperature of -13.5℃. It enters the ammonia cooler to cool the ammonia gas to -25℃. The ammonia cooler provides low temperature through the vaporization of the cold source (liquid ammonia). The pressure on the cold side of the ammonia cooler is controlled to be ≤0.03mPa (G) (corresponding to the vaporization temperature of -28℃) to ensure that the cold source provides sufficient temperature. The pure ammonia gas is condensed into liquid ammonia and enters the liquid ammonia tank. A part of it is pressurized by the liquid ammonia reflux pump and then enters the top of the ammonia refining tower for reflux. A part of it is sent out as a product after being pressurized by the liquid ammonia discharge pump. The other part is sent to the ammonia absorber to produce concentrated ammonia water.

[0031] (5) Liquid ammonia sent by the liquid ammonia reflux pump enters the ammonia absorber. The ammonia absorber is divided into two parts: the absorption section and the cooling section. The absorption section is provided with two sections of fillers. The upper section is a desalted water primary absorption filler, and the lower section is a circulating absorption filler. The cooling section is below the absorption section and is a horizontal shell and tube heat exchanger. Ammonia water and chilled water exchange heat indirectly to remove the absorption heat of ammonia. The absorption pressure of ammonia gas can be adjusted arbitrarily between 0 and 0.2 mPa (G), and the concentration of ammonia water is 20%wt to 40%wt. After being cooled, the ammonia water enters the ammonia water tank, and then is pressurized by the ammonia water circulation pump and divided into three paths: the first path is used as the circulating absorption liquid and sent to the ammonia absorber absorption section for circulating ammonia absorption; the second path is used as the replenishing liquid of the acid gas scrubber; and the third path can be selectively sent out as an ammonia water product.

[0032] (6) The feed ammonia concentration of the ammonia refining tower is high (98%wt). Compared with the traditional ammonia water feed (20%wt), the processing load of the ammonia refining tower is greatly reduced, and the equipment investment is also reduced accordingly.

[0033] (7) The heat source of the ammonia refining tower is provided by the ammonia refining tower reboiler. The operating temperature of the ammonia refining tower kettle is 60-65°C. The heating medium is hot water. The hot water temperature is greater than 85°C, which saves steam consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a process flow chart of the present invention;

[0035] Explanation of the reference numerals: acid gas washing tower 1, ammonia refining tower 2, lower washing circulation pump 3, washing cooler 4, upper washing circulation pump 5, ammonia refining tower reboiler 6, ammonia refining tower bottom metering pump 7, ammonia cooler 8, liquid ammonia tank 9, liquid ammonia reflux pump 10, liquid ammonia discharge pump 11, ammonia absorber 12, ammonia water tank 13, ammonia water circulation pump 14, ammonia side line sewage pump 15. DETAILED DESCRIPTION

[0036] like Figure 1As shown, a device for purifying crude ammonia and preparing liquid ammonia comprises an acid gas washing tower 1, an ammonia refining tower 2, a lower washing circulation pump 3, a washing cooler 4, an upper washing circulation pump 5, an ammonia refining tower reboiler 6, an ammonia refining tower bottom metering pump 7, an ammonia cooler 8, a liquid ammonia tank 9, a liquid ammonia reflux pump 10, a liquid ammonia discharge pump 11, an ammonia absorber 12, an ammonia water tank 13, an ammonia water circulation pump 14, and an ammonia side line sewage pump 15.

[0037] The ammonia absorber 12 is divided into an absorption section and a cooling section. The absorption section is provided with two sections of fillers, the upper section is a desalted water primary absorption filler, and the lower section is a circulating absorption filler. The cooling section is below the absorption section and is a horizontal shell and tube heat exchanger.

[0038] The ammonia refining tower 2 is divided into three sections: the upper section is a rectifying section, the middle section is a liquid collecting tank, and the lower section is a stripping section; an annular packing is arranged above the liquid collecting tank in the middle section.

[0039] The crude ammonia is connected to the lower part of the acid gas washing tower 1 through a pipeline, the bottom of the acid gas washing tower 1 is connected to the inlet of the washing cooler 4 through the lower washing circulation pump 3, the outlet of the washing cooler 4 is connected to the middle and lower part of the acid gas washing tower 1 through a pipeline, and the outlet of the lower washing circulation pump 3 is connected to the off-site raw material tank through a pipeline.

[0040] The middle part of the acid gas washing tower 1 is connected to the upper middle part of the acid gas washing tower 1 through the upper washing circulation pump 5, the top of the acid gas washing tower 1 is connected to the middle part of the ammonia refining tower 2 through a pipeline, the bottom of the ammonia refining tower 2 is connected to the inlet of the ammonia refining tower reboiler 6 through a pipeline, the outlet of the ammonia refining tower reboiler 6 is connected to the lower part of the ammonia refining tower 2 through a pipeline, and the bottom of the ammonia refining tower 2 is connected to the outside through the ammonia refining tower bottom metering pump 7.

[0041] The middle part of the ammonia refining tower 2 is connected to the middle part of the acid gas washing tower 1 through an ammonia side line sewage pump 15 .

[0042] The middle and upper outlet of the ammonia refining tower 2 is divided into two routes: one route is connected to the middle of the ammonia refining tower 2 and the inlet pipeline of the ammonia side line sewage pump 15 through pipelines, and the other route is connected to the middle and lower part of the ammonia refining tower 2 through pipelines.

[0043] The top of the ammonia refining tower 2 is connected to the inlet of the ammonia cooler 8 through a pipeline, and the outlet of the ammonia cooler 8 is connected to the top of the liquid ammonia tank 9 through a pipeline. The bottom of the liquid ammonia tank 9 is divided into two paths through a liquid ammonia reflux pump 10: one path is connected to the top of the ammonia refining tower 2 through a pipeline, and the other path is connected to the lower part of the absorption section of the ammonia absorber 12 through a pipeline; the bottom of the liquid ammonia tank 9 is connected to the liquid ammonia outside the boundary through a pipeline through a liquid ammonia discharge pump 11.

[0044] The desalted water is connected to the top of the absorption section of the ammonia absorber 12 through a pipeline, and the bottom of the cooling section of the ammonia absorber 12 is connected to the top of the ammonia water tank 13 through a pipeline. The ammonia water tank 13 is divided into three routes after passing through the ammonia water circulation pump 14: the first route is connected to the middle of the absorption section of the ammonia absorber 12 through a pipeline, the second route is connected to the top of the acid gas washing tower 1 through a pipeline, and the third route is connected to the ammonia water outside the boundary through a pipeline.

[0045] The off-site chilled water inlet is connected to the washing cooler 4 and the cooling section of the ammonia absorber 12 through pipelines, and the washing cooler 4 and the cooling section of the ammonia absorber 12 are connected to the off-site chilled water return through pipelines.

[0046] The liquid ammonia outside the boundary is connected to the ammonia cooler 8 through a pipeline, and the ammonia cooler 8 is connected to the gaseous ammonia outside the boundary through a pipeline.

[0047] The process is as follows:

[0048] The first step of acid gas washing: the crude ammonia containing H2S and organic matter enters the lower part of the acid gas washing tower 1, and the washing liquid is drawn out from the bottom of the acid gas washing tower 1, pressurized by the lower washing circulation pump 3, and heat exchanged with the off-site chilled water through the washing cooler 4. After its own temperature drops to 20-30°C, it enters the upper part of the lower packing of the acid gas washing tower 1, fully contacts with the crude ammonia containing H2S and organic matter, transfers mass and heat, absorbs the acid gas in the crude ammonia, and performs a primary washing of the crude ammonia; the sulfur-containing ammonia liquid is regularly discharged from the outlet of the lower washing circulation pump 3 into the off-site raw material tank for re-washing. Stripping; the washing liquid in the middle of the acid gas washing tower 1 is introduced from the liquid collecting tank, and after being pressurized by the upper washing circulation pump 5, it enters above the upper packing in the acid gas washing tower 1 to perform secondary washing on the crude ammonia gas, and further remove the acid gas in the crude ammonia gas. The temperature of the secondary washing is controlled by the liquid ammonia from the ammonia side line sewage pump 15, and the temperature is controlled at 10-15°C; the concentrated ammonia water from the ammonia water circulation pump 14 enters from the top of the acid gas washing tower 1, performs tertiary washing on the crude ammonia gas, and serves as the supplementary liquid of the acid gas washing tower 1; the ammonia gas content of the gas coming out from the top of the tower is less than 3ppm.

[0049] The second step is ammonia refining: the gaseous ammonia coming out of the top of the acid gas washing tower 1 enters from the bottom of the annular packing above the middle section of the ammonia refining tower 2, and fully contacts with the liquid phase of part of the low-temperature rectification section from the upper section, and transfers mass and heat. After the temperature is lowered, most of the organic matter and part of the ammonia in the ammonia are condensed, and the gas and liquid are separated. The liquid phase is collected in the liquid collecting tank and sent to the middle part of the acid gas washing tower through the ammonia side line sewage pump 15. The gas phase enters the rectification section of the upper section and fully contacts with the reflux liquid in the upper section packing, and transfers mass and heat to further concentrate the gaseous ammonia; most of the liquid phase of the rectification section is introduced into the stripping section of the lower section through a pipeline to further extract ammonia from the organic matter and water; the heat source of the ammonia refining tower 2 is provided by the ammonia refining tower reboiler 6, and the heating medium is hot water; the pressure of the ammonia refining tower 2 is controlled to be 0.15mPa (G), the tower top temperature is -13.5℃, the tower bottom temperature is 60~65℃, and the organic matter content of the gaseous ammonia coming out of the tower top is less than 10ppm.

[0050] The third step is ammonia condensation: the pure ammonia gas coming out from the top of the ammonia refining tower 2 has a pressure of 0.15mPa (G) and a temperature of -13.5℃, and enters the ammonia cooler 8 to cool the ammonia gas to -25℃. The ammonia cooler 8 provides low temperature by gasifying the cold source (liquid ammonia) to ensure that the cold source provides sufficient temperature; the pure ammonia gas is condensed into liquid ammonia and enters the liquid ammonia tank 9. A part of it is pressurized by the liquid ammonia reflux pump 10 and enters the top of the ammonia refining tower 2 for reflux, a part of it is sent out as a product after being pressurized by the liquid ammonia discharge pump 11, and the other part is sent to the ammonia absorber 12 to produce concentrated ammonia water.

[0051] The fourth step is ammonia absorption: the liquid ammonia sent from the liquid ammonia reflux pump 10 enters the ammonia absorber 12 for ammonia absorption. The ammonia absorber 12 is divided into an absorption section and a cooling section. The absorption section is provided with two sections of fillers: the upper section is a desalted water one-time absorption filler, and the lower section is a circulating absorption filler; the cooling section is below the absorption section and is a horizontal shell and tube heat exchanger; the ammonia water and the chilled water exchange heat indirectly to remove the absorption heat of ammonia; the absorption pressure of ammonia gas can be arbitrarily adjusted between 0 and 0.2 mPa (G), and the ammonia water concentration is 20%wt to 40%wt; the ammonia water is cooled and enters the ammonia water tank 13, and then is pressurized by the ammonia water circulation pump and is divided into three paths: the first path is used as a circulating absorption liquid and sent to the absorption section of the ammonia absorber 12 for circulating ammonia absorption; the second path is used as a supplementary liquid for the acid gas scrubbing tower 1, and the third path can be selectively sent out as an ammonia water product.

Claims

1. A device for purifying crude ammonia and producing liquid ammonia, characterized in that: It comprises an acid gas washing tower (1), an ammonia refining tower (2), a lower washing circulation pump (3), a washing cooler (4), an upper washing circulation pump (5), an ammonia refining tower reboiler (6), an ammonia refining tower bottom metering pump (7), an ammonia cooler (8), a liquid ammonia tank (9), a liquid ammonia reflux pump (10), a liquid ammonia discharge pump (11), an ammonia absorber (12), an ammonia water tank (13), an ammonia water circulation pump (14), and an ammonia side line sewage pump (15); The crude ammonia gas is connected to the lower part of the acid gas scrubber (1) through a pipeline, the bottom of the acid gas scrubber (1) is connected to the inlet of the scrubber cooler (4) through a lower scrubber circulation pump (3), the outlet of the scrubber cooler (4) is connected to the middle and lower part of the acid gas scrubber (1) through a pipeline, and the outlet of the lower scrubber circulation pump (3) is connected to an off-site raw material tank through a pipeline; The middle part of the acid gas washing tower (1) is connected to the middle and upper part of the acid gas washing tower (1) through an upper washing circulation pump (5); The top of the acid gas scrubbing tower (1) is connected to the middle of the ammonia refining tower (2) through a pipeline, the bottom of the ammonia refining tower (2) is connected to the inlet of the ammonia refining tower reboiler (6) through a pipeline, the outlet of the ammonia refining tower reboiler (6) is connected to the lower part of the ammonia refining tower (2) through a pipeline, and the bottom of the ammonia refining tower (2) is connected to the outside through the ammonia refining tower bottom metering pump (7); The middle of the ammonia refining tower (2) is connected to the middle of the acid gas washing tower (1) through an ammonia side-line sewage pump (15), and the outlet of the middle and upper part of the ammonia refining tower (2) is divided into two routes: one route is connected to the middle of the ammonia refining tower (2) and the inlet pipeline of the ammonia side-line sewage pump (15) through a pipeline, and the other route is connected to the middle and lower part of the ammonia refining tower (2) through a pipeline; The top of the ammonia refining tower (2) is connected to the inlet of the ammonia cooler (8) through a pipeline, the outlet of the ammonia cooler (8) is connected to the top of the liquid ammonia tank (9) through a pipeline, and the bottom of the liquid ammonia tank (9) is divided into two paths through a liquid ammonia reflux pump (10): one path is connected to the top of the ammonia refining tower (2) through a pipeline, and the other path is connected to the lower part of the absorption section of the ammonia absorber (12) through a pipeline; the bottom of the liquid ammonia tank (9) is connected to the liquid ammonia outside the boundary through a pipeline through a liquid ammonia discharge pump (11); The desalted water is connected to the top of the absorption section of the ammonia absorber (12) through a pipeline, the bottom of the cooling section of the ammonia absorber (12) is connected to the top of the ammonia water tank (13) through a pipeline, and the ammonia water tank (13) is divided into three paths after passing through the ammonia water circulation pump (14): the first path is connected to the middle of the absorption section of the ammonia absorber (12) through a pipeline, the second path is connected to the top of the acid gas scrubbing tower (1) through a pipeline, and the third path is connected to the ammonia water outside the boundary through a pipeline; The acid gas washing tower (1) is divided into two sections, the upper and lower sections, separated by a liquid collecting tank. The lower section is provided with a first-stage circulating washing, and the circulating washing temperature is 20°C to 30°C controlled by the flow rate of chilled water in the washing cooler (4), and the chilled water temperature is less than 20°C; the upper section is provided with two-stage washing: the first stage is circulating washing, and the circulating washing temperature is 10°C to 15°C controlled by the flow rate of liquid ammonia from the ammonia side line sewage pump (15); the other stage is a primary washing, and the primary washing liquid adopts finished concentrated ammonia water, which enters from the top of the acid gas washing tower (1), and the acid gas washing tower (1) is replenished with liquid at the same time, and the excess sulfur-containing ammonia liquid is regularly discharged into the raw material tank for re-stripping; The ammonia refining tower (2) is divided into three sections: an upper section, a liquid collecting tank in the middle section, and a lower section, a stripping section; an annular packing is arranged above the liquid collecting tank in the middle section.

2. The device for purifying crude ammonia and producing liquid ammonia according to claim 1, characterized in that: The ammonia absorber (12) is divided into an absorption section and a cooling section. The absorption section is provided with two sections of fillers, the upper section is a desalted water primary absorption filler, and the lower section is a circulating absorption filler. The cooling section is below the absorption section and is a horizontal shell and tube heat exchanger.

3. A method for purifying crude ammonia and producing liquid ammonia, characterized in that: The device for purifying crude ammonia and preparing liquid ammonia according to any one of claims 1 to 2 comprises the following steps: The first step is to perform three-stage washing of crude ammonia in the acid gas washing tower. The crude ammonia gas containing H2S and organic matter enters the lower part of the acid gas scrubber (1), and the scrubbing liquid is drawn out from the bottom of the acid gas scrubber (1), pressurized by the lower scrubbing circulation pump (3), and heat-exchanged with the off-site chilled water through the scrubbing cooler (4). After its own temperature drops to 20-30°C, it enters the upper part of the lower packing of the acid gas scrubber (1), fully contacts with the crude ammonia gas containing H2S and organic matter, transfers mass and heat, absorbs the acid gas in the crude ammonia gas, and performs primary scrubbing of the crude ammonia gas. The sulfur-containing ammonia liquid is discharged from the lower scrubbing circulation pump (3) The washing liquid in the middle of the acid gas washing tower (1) is introduced from the liquid collecting tank, and after being pressurized by the upper washing circulation pump (5), it enters the upper part of the packing in the middle of the acid gas washing tower (1) to perform secondary washing on the crude ammonia gas, and further remove the acid gas in the crude ammonia gas; the concentrated ammonia water from the ammonia water circulation pump (14) enters from the top of the acid gas washing tower (1), performs tertiary washing on the crude ammonia gas, and is also used as the supplementary liquid of the acid gas washing tower (1). The ammonia gas content of the gas discharged from the top of the tower is less than 3ppm; Step 2: Refining gaseous ammonia in an ammonia refining tower The gaseous ammonia coming out of the top of the acid gas washing tower (1) enters from below the annular packing above the liquid collecting tank in the middle section of the ammonia refining tower (2), fully contacts with the liquid phase of part of the low-temperature rectification section from the upper section, and conducts mass transfer and heat transfer. After the temperature is lowered, most of the organic matter and part of the ammonia in the ammonia gas are condensed, and the gas and liquid are separated. The liquid phase is collected in the liquid collecting tank and sent to the middle part of the acid gas washing tower through the ammonia side line sewage pump (15). The gas phase enters the rectification section of the upper section, and fully contacts with the reflux liquid in the upper section packing, and conducts mass transfer and heat transfer, so that the gaseous ammonia is further concentrated. Most of the liquid phase in the rectification section is introduced into the stripping section of the lower section through a pipeline, and ammonia in the organic matter and water is further extracted. The organic content of the gaseous ammonia coming out of the top of the tower is less than 10ppm. Step 3: Condensation of ammonia in the ammonia cooler The pure ammonia gas coming out from the top of the ammonia refining tower has a pressure of 0.15 mPa (G) and a temperature of -13.5°C. It enters the ammonia cooler (8) to cool the ammonia gas to -25°C. The pure ammonia gas is condensed into liquid ammonia and then enters the liquid ammonia tank (9). A portion of the ammonia gas is pressurized by the liquid ammonia reflux pump (10) and then enters the top of the ammonia refining tower (2) for reflux. A portion of the ammonia gas is pressurized by the liquid ammonia discharge pump (11) as a product and then sent to the outside. The other portion is sent to the ammonia absorber (12) to produce concentrated ammonia water. Step 4: Absorb ammonia in the ammonia absorber The liquid ammonia sent from the liquid ammonia reflux pump (10) enters the ammonia absorber (12) for ammonia absorption. The ammonia water indirectly exchanges heat with the chilled water to remove the absorption heat of ammonia. The ammonia water is cooled and enters the ammonia water tank (13). Then, it is pressurized by the ammonia water circulation pump (14) and divided into three paths: the first path is used as the circulating absorption liquid and sent to the absorption section of the ammonia absorber (12) for circulating ammonia absorption; the second path is used as the supplementary liquid of the acid gas washing tower (1); and the third path is selectively sent out as an ammonia water product.

4. The method for purifying crude ammonia and producing liquid ammonia according to claim 3, characterized in that: The heat source of the ammonia refining tower (2) is provided by the ammonia refining tower reboiler (6), and the heating medium is hot water. The pressure of the ammonia refining tower (2) is controlled to be 0.15mPa (G), the tower top temperature is -13.5°C, the tower bottom temperature is 60-65°C, and the organic matter content of the gas ammonia coming out from the tower top is less than 10ppm.

5. The method for purifying crude ammonia and producing liquid ammonia according to claim 3, characterized in that: The absorption pressure of ammonia can be adjusted arbitrarily between 0 and 0.2 mPa (G), and the concentration of ammonia water is 20%wt to 40%wt.

6. The method for purifying crude ammonia and producing liquid ammonia according to claim 3, characterized in that: The heat source of the ammonia refining tower (2) is provided by the ammonia refining tower reboiler (6). The operating temperature of the bottom of the ammonia refining tower (2) is 60-65°C. The heating medium is hot water, and the temperature of the hot water is greater than 85°C.

7. The method for purifying crude ammonia and producing liquid ammonia according to claim 3, characterized in that: The ammonia cooler (8) provides low temperature by gasifying liquid ammonia as a cold source, and the pressure on the cold side of the ammonia cooler (8) is controlled to be ≤ 0.03 mPa (G) to ensure that the cold source provides a sufficient temperature.

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