Process for co-production of electronic ultra-pure ammonia and ammonia water by step filtration-medium-pressure double-tower rectification

Abstract

The invention discloses a process for co-production of electronic ultra-pure ammonia and ammonia water by step filtration-medium-pressure double-tower rectification, and relates to the field of production of electronic-grade ultra-pure ammonia. The method comprises the following steps: (1) carrying out gradient filtration treatment on raw materials; (2) carrying out medium-pressure double-tower rectification treatment; (3) carrying out stepped filtering treatment on the product; (4) tail gas treatment; and (5) preparing ammonia water. According to the invention, industrial anhydrous ammonia is taken as a raw material, the ultra-pure ammonia purification technology is optimized by adopting a technical means of combining step filtration and medium-pressure double-tower rectification, the 7N ultra-pure ammonia product is efficiently and stably obtained, the production capacity of a continuous process is large, the product quality is stable and easy to control, and industrial ammonia water with the concentration of more than 20% can be co-produced; in the whole process, comprehensive utilization of industrial anhydrous ammonia is achieved, no production wastewater is discharged, no pollution is caused after tail gas is subjected to multi-stage treatment, the utilization rate of raw materials is increased, meanwhile, energy consumption is reduced, the production process is more efficient and environmentally friendly, and the requirement of the market for high-purity ammonia products is met.

Description

Technical Field

[0001] The invention relates to the field of production of electronic grade ultra-pure ammonia, and specifically is a process for co-producing ammonia water by step filtration and medium-pressure double-tower distillation of electronic ultra-pure ammonia. Background Art

[0002] With the rapid development of microelectronics and optoelectronics technology, especially the silicon nitride masking film plays a vital role in the performance of light-emitting diodes (LEDs), ultra-pure ammonia, as one of the key materials for making silicon nitride films, has seen an increasing demand year by year. However, the market has increasingly higher requirements for the purity of ultra-pure ammonia. In the preparation process of gallium nitride (GaN), the purity of ammonia must reach 7N (99.99999%) or above. At present, there is a great demand for ultra-pure ammonia in the international market, but due to technical barriers and resource limitations, my country's self-sufficiency rate in this field is relatively low.

[0003] Companies such as Praxair in the United States, Sumitomo Chemical in Japan, and Showa Denko have extensive experience in the production of ultra-pure ammonia, and mainly provide ultra-pure ammonia materials for my country's LED industry. These companies use chemical methods to remove water and catalytic methods to remove oxygen, supplemented by adsorption purification, to keep ultra-pure ammonia products stable at the 7N level for a long time. my country's ultra-pure ammonia technology started relatively late. The first ultra-pure ammonia plant put into operation by Linde in Xiamen in 2010 used Y-tower distillation and purification technology to achieve a purity of 7N. In recent years, domestic companies have successfully solved the problem of ultra-pure ammonia process stability through continuous innovation on the basis of absorbing advanced foreign technologies, so that the purity of the ultra-pure ammonia produced is consistently stable at 7N.

[0004] The traditional pre-purification (adsorption purification) + single-tower distillation technology has certain limitations in production capacity and product quality control. Therefore, it is of great significance to develop a new type of high-efficiency and low-energy consumption electronic-grade ultra-pure ammonia separation and purification process. Summary of the invention

[0005] The present invention aims to solve the problems existing in the prior art in the above-mentioned background technology, and aims to provide a process for the co-production of ammonia water by using cascade filtration and medium-pressure double-tower distillation of electronic ultra-pure ammonia. The method uses industrial anhydrous ammonia as raw material, and obtains 7N ultra-pure ammonia product through cascade filtration, light removal tower and heavy removal tower double-tower distillation, and can also co-produce industrial ammonia water. The whole process realizes the comprehensive utilization of ammonia water and pollution-free emission, improves the utilization rate of raw materials, and reduces energy consumption, making the production process more efficient and environmentally friendly, and the product quality is stable, meeting the market demand for high-purity ammonia products.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a process for co-producing ammonia water by step filtration-medium pressure double-tower distillation of electronic ultrapure ammonia, comprising:

[0008] (1) Raw material cascade filtration treatment

[0009] The liquid ammonia in the liquid ammonia storage tank in the tank area is used as raw material, filtered through multiple series-connected raw material filters, and then pressurized by the feed pump and sent to the lightness removal tower;

[0010] (2) Medium-pressure double-tower distillation treatment

[0011] The pressurized liquid ammonia flows through the reboiler of the light-removing tower for heat exchange, the light component gas coming out of the top of the light-removing tower is condensed by the condenser of the light-removing tower and separated by the separator of the light-removing tower, the light component impurities separated at the top of the separator of the light-removing tower are sent to the venting buffer tank, the liquid material separated at the bottom of the separator of the light-removing tower is refluxed into the light-removing tower, the liquid ammonia produced from the kettle of the light-removing tower to remove the light component gas enters the de-weighting tower by pressure difference, flows through the reboiler of the de-weighting tower for heat exchange, the heavy component impurities discharged from the kettle of the de-weighting tower enter the residual liquid vaporizer for gasification and then are sent to the venting buffer tank, the gaseous ammonia coming out of the top of the de-weighting tower is condensed by the condenser of the de-weighting tower and separated by the separator of the de-weighting tower, the non-condensable gas separated at the top of the separator of the de-weighting tower is sent to the venting buffer tank, and the ultra-pure liquid ammonia is separated at the bottom of the separator of the de-weighting tower;

[0012] (3) Product cascade filtration treatment

[0013] The ultra-pure liquid ammonia separated at the bottom of the de-weighting tower separator is divided into two paths, one path is refluxed to the de-weighting tower, and the other path is tested for product quality. The qualified 7N ultra-pure ammonia is condensed in the product condenser and filtered by multiple series-connected product filters, and then directly sent to the tank truck for filling or product storage tanks. The unqualified liquid ammonia is sent to the liquid ammonia storage tank in the tank area.

[0014] (4) Exhaust gas treatment

[0015] The tail gas discharged from the air buffer tank is sent to the high-efficiency ammonia absorber, mixed with the dilute ammonia water from the first dilute ammonia water tank to form concentrated ammonia water and enter the ammonia water tank. The ammonia water coming out of the ammonia water tank is pressurized by the ammonia water pump and divided into four paths. The first path returns to the ammonia water tank, the second path returns to the upper part of the high-efficiency ammonia absorber to continue absorbing ammonia tail gas, and the third path is when the concentration of ammonia water is lower than the specified requirement after analysis and detection, it enters the upper part of the ammonia water preparation device to continue mixing with the liquid ammonia from the tank area to a high-concentration ammonia water of qualified concentration. The fourth path is ammonia water with qualified concentration directly sent to the ammonia water storage tank. The tail gas coming out of the top of the ammonia water tank is combined with the ammonia at the top of the ammonia water storage tank in the tank area and the ammonia discharged during the filling process and then enters Enter the secondary ammonia absorption tower, mix with the dilute ammonia water from the second dilute ammonia water tank to form a relatively concentrated dilute ammonia water and enter the first dilute ammonia water tank. The tail gas from the top of the secondary ammonia absorption tower enters the lower part of the tertiary ammonia absorption tower, mixes with softened water from the outside to form dilute ammonia water and enters the second dilute ammonia water tank. The dilute ammonia water from the bottom of the first dilute ammonia water tank is divided into two paths, one path returns to the ammonia water tank, and the other path flows through the first heat exchanger for cooling and then returns to the upper part of the secondary ammonia absorption tower. The tail gas from the top of the tertiary ammonia absorption tower is vented for treatment. The dilute ammonia water from the bottom of the second dilute ammonia water tank is divided into two paths, one path returns to the first dilute ammonia water tank, and the other path flows through the second heat exchanger for cooling and then returns to the upper part of the tertiary ammonia absorption tower.

[0016] (5) Preparation of Ammonia Water

[0017] Liquid ammonia from the liquid ammonia storage tank in the tank area is input into the lower part of the ammonia water preparation device, and softened water from outside the boundary is also input into the upper part of the ammonia water preparation device. The ammonia water prepared by the ammonia water preparation device is sent to the ammonia water storage tank from the lower part of the ammonia water preparation device.

[0018] Furthermore, the tail gas discharged from the air venting buffer tank directly enters the lower part of the three-stage ammonia absorption tower through a branch line, and the upper part of the three-stage ammonia absorption tower is input with out-of-boundary softened water.

[0019] Furthermore, hot water from outside the boundary is used as a heat source to provide thermal energy to the light removal tower reboiler, heavy removal tower reboiler and residual liquid vaporizer.

[0020] Furthermore, external circulating cooling water is used as a cold source to provide cold energy to the light removal tower condenser, heavy removal tower condenser, ammonia water preparation device, high-efficiency ammonia absorber, the first heat exchanger, and the second heat exchanger.

[0021] Furthermore, in step (1), the pressure of liquid ammonia in the liquid ammonia storage tank in the tank area at room temperature is 0.8 MPa≤P≤1.6 MPa, the flow rate is 4000 kg / h, and the feed pump is pressurized to 1.9 MPa.

[0022] Furthermore, in step (2), the liquid ammonia extracted from the kettle of the light component removal tower to remove the light component gas is reduced in pressure to 1.7 MPa by pressure difference and then enters the heavy component removal tower.

[0023] Furthermore, in step (4), the pressure of the external softened water at room temperature is ≥0.2 MPa, the flow rate is 16000 kg / h, and the mass concentration of the ammonia water prepared by the ammonia water preparation device is ≥20%.

[0024] Compared with the prior art, the technical advantages and progress of the present invention are:

[0025] The process for co-producing ammonia water by using cascade filtration and medium-pressure double-tower distillation for electronic ultra-pure ammonia takes industrial anhydrous ammonia as raw material, optimizes ultra-pure ammonia purification technology by adopting the technical means of combining cascade filtration and medium-pressure double-tower distillation, and obtains 7N ultra-pure ammonia products efficiently and stably. The continuous process has large production capacity, stable and easy-to-control product quality, and can co-produce industrial ammonia water with a concentration of more than 20%. The whole process realizes the comprehensive utilization of industrial anhydrous ammonia, without the discharge of production wastewater, and the discharge of tail gas after multi-stage treatment is pollution-free, which improves the utilization rate of raw materials and reduces energy consumption at the same time, making the production process more efficient and environmentally friendly, and meeting the market demand for high-purity ammonia products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention discloses a flow chart of a process for co-producing ammonia water by using cascade filtration and medium-pressure double-tower distillation for electronic ultrapure ammonia. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below through specific embodiments in combination with the accompanying drawings, but the implementation mode of the present invention is not limited thereto.

[0028] Example

[0029] In this embodiment, liquid ammonia that meets the superior quality standard of "Liquid Anhydrous Ammonia" (GB536-2017) is used as raw material, with a purity specification of 99.8%, a dosage of 840 kg / h, an operating time of 8000 h / a, and a raw material liquid ammonia dosage of 6720 t / a.

[0030] A process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultra-pure ammonia, comprising:

[0031] (1) Raw material cascade filtration treatment

[0032] The liquid ammonia in the liquid ammonia storage tank in the tank area is used as raw material, filtered through multiple series-connected raw material filters, and then pressurized by the feed pump and sent to the lightness removal tower;

[0033] (2) Medium-pressure double-tower distillation treatment

[0034] The pressurized liquid ammonia flows through the reboiler of the light-removing tower for heat exchange, the light component gas coming out of the top of the light-removing tower is condensed by the condenser of the light-removing tower and separated by the separator of the light-removing tower, the light component impurities separated at the top of the separator of the light-removing tower are sent to the venting buffer tank, the liquid material separated at the bottom of the separator of the light-removing tower is refluxed into the light-removing tower, the liquid ammonia produced from the kettle of the light-removing tower to remove the light component gas enters the de-weighting tower by pressure difference, flows through the reboiler of the de-weighting tower for heat exchange, the heavy component impurities discharged from the kettle of the de-weighting tower enter the residual liquid vaporizer for gasification and then are sent to the venting buffer tank, the gaseous ammonia coming out of the top of the de-weighting tower is condensed by the condenser of the de-weighting tower and separated by the separator of the de-weighting tower, the non-condensable gas separated at the top of the separator of the de-weighting tower is sent to the venting buffer tank, and the ultra-pure liquid ammonia is separated at the bottom of the separator of the de-weighting tower;

[0035] (3) Product cascade filtration treatment

[0036] The ultra-pure liquid ammonia separated at the bottom of the de-weighting tower separator is divided into two paths, one path is refluxed to the de-weighting tower, and the other path is tested for product quality. The qualified 7N ultra-pure ammonia is condensed in the product condenser and filtered by multiple series-connected product filters, and then directly sent to the tank truck for filling or product storage tanks. The unqualified liquid ammonia is sent to the liquid ammonia storage tank in the tank area.

[0037] (4) Exhaust gas treatment

[0038] The tail gas discharged from the air buffer tank is sent to the high-efficiency ammonia absorber, mixed with the dilute ammonia water from the first dilute ammonia water tank to form concentrated ammonia water and enter the ammonia water tank. The ammonia water coming out of the ammonia water tank is pressurized by the ammonia water pump and divided into four paths. The first path returns to the ammonia water tank, the second path returns to the upper part of the high-efficiency ammonia absorber to continue absorbing ammonia tail gas, and the third path is when the concentration of ammonia water is lower than the specified requirement after analysis and detection, it enters the upper part of the ammonia water preparation device to continue mixing with the liquid ammonia from the tank area to a high-concentration ammonia water of qualified concentration. The fourth path is ammonia water with qualified concentration directly sent to the ammonia water storage tank. The tail gas coming out of the top of the ammonia water tank is combined with the ammonia at the top of the ammonia water storage tank in the tank area and the ammonia discharged during the filling process and then enters Enter the secondary ammonia absorption tower, mix with the dilute ammonia water from the second dilute ammonia water tank to form a relatively concentrated dilute ammonia water and enter the first dilute ammonia water tank. The tail gas from the top of the secondary ammonia absorption tower enters the lower part of the tertiary ammonia absorption tower, mixes with softened water from the outside to form dilute ammonia water and enters the second dilute ammonia water tank. The dilute ammonia water from the bottom of the first dilute ammonia water tank is divided into two paths, one path returns to the ammonia water tank, and the other path flows through the first heat exchanger for cooling and then returns to the upper part of the secondary ammonia absorption tower. The tail gas from the top of the tertiary ammonia absorption tower is vented for treatment. The dilute ammonia water from the bottom of the second dilute ammonia water tank is divided into two paths, one path returns to the first dilute ammonia water tank, and the other path flows through the second heat exchanger for cooling and then returns to the upper part of the tertiary ammonia absorption tower.

[0039] (5) Preparation of Ammonia Water

[0040] Liquid ammonia from the liquid ammonia storage tank in the tank area is input into the lower part of the ammonia water preparation device, and softened water from outside the boundary is also input into the upper part of the ammonia water preparation device. The ammonia water prepared by the ammonia water preparation device is sent to the ammonia water storage tank from the lower part of the ammonia water preparation device.

[0041] Specifically, the tail gas discharged from the air venting buffer tank directly enters the lower part of the three-stage ammonia absorption tower through a branch line, and the upper part of the three-stage ammonia absorption tower inputs out-of-boundary softened water.

[0042] Specifically, hot water from outside the boundary is used as a heat source to provide heat energy to the light removal tower reboiler, heavy removal tower reboiler, and residual liquid vaporizer; and circulating cooling water from outside the boundary is used as a cold source to provide cold energy to the light removal tower condenser, heavy removal tower condenser, ammonia water preparation device, high-efficiency ammonia absorber, the first heat exchanger, and the second heat exchanger.

[0043] In this embodiment, in step (1), the pressure of liquid ammonia in the liquid ammonia storage tank in the tank area at room temperature is 0.8MPa≤P≤1.6MPa, the flow rate is 4000kg / h, and the feed pump is pressurized to 1.9MPa; in step (2), the liquid ammonia extracted from the kettle of the light component removal tower is depressurized to 1.7MPa by pressure difference and then enters the heavy component removal tower; in step (4), the pressure of the demineralized water outside the boundary at room temperature is ≥0.2MPa, and the flow rate is 16000kg / h.

[0044] The product obtained in this example is 7N (99.99999%) ultra-pure ammonia, 750kg / h, 6000t / a; the by-product is industrial ammonia water (20%), 750kg / h, 6000t / a. The product ultra-pure ammonia index complies with the T / CCGA30001-2019 "Ultra-pure Ammonia" group standard, and the industrial ammonia water product quality complies with the HG / T5353-2018 "Industrial Ammonia Water".

[0045] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia, characterized in that: include: (1) Raw material cascade filtration treatment The liquid ammonia in the liquid ammonia storage tank in the tank area is used as raw material, filtered through multiple series-connected raw material filters, and then pressurized by the feed pump and sent to the lightness removal tower; (2) Medium-pressure double-tower distillation treatment The pressurized liquid ammonia flows through the reboiler of the light-removing tower for heat exchange, the light component gas coming out of the top of the light-removing tower is condensed by the condenser of the light-removing tower and separated by the separator of the light-removing tower, the light component impurities separated at the top of the separator of the light-removing tower are sent to the venting buffer tank, the liquid material separated at the bottom of the separator of the light-removing tower is refluxed into the light-removing tower, the liquid ammonia produced from the kettle of the light-removing tower to remove the light component gas enters the de-weighting tower by pressure difference, flows through the reboiler of the de-weighting tower for heat exchange, the heavy component impurities discharged from the kettle of the de-weighting tower enter the residual liquid vaporizer for gasification and then are sent to the venting buffer tank, the gaseous ammonia coming out of the top of the de-weighting tower is condensed by the condenser of the de-weighting tower and separated by the separator of the de-weighting tower, the non-condensable gas separated at the top of the separator of the de-weighting tower is sent to the venting buffer tank, and the ultra-pure liquid ammonia is separated at the bottom of the separator of the de-weighting tower; (3) Product cascade filtration treatment The ultra-pure liquid ammonia separated at the bottom of the de-weighting tower separator is divided into two paths, one path is refluxed to the de-weighting tower, and the other path is tested for product quality. The qualified 7N ultra-pure ammonia is condensed in the product condenser and filtered by multiple series-connected product filters, and then directly sent to the tank truck for filling or product storage tanks. The unqualified liquid ammonia is sent to the liquid ammonia storage tank in the tank area. (4) Exhaust gas treatment The tail gas discharged from the air buffer tank is sent to the high-efficiency ammonia absorber, mixed with the dilute ammonia water from the first dilute ammonia water tank to form concentrated ammonia water and enter the ammonia water tank. The ammonia water coming out of the ammonia water tank is pressurized by the ammonia water pump and divided into four paths. The first path returns to the ammonia water tank, the second path returns to the upper part of the high-efficiency ammonia absorber to continue absorbing ammonia tail gas, and the third path is when the concentration of ammonia water is lower than the specified requirement after analysis and detection, it enters the upper part of the ammonia water preparation device to continue mixing with the liquid ammonia from the tank area to a high-concentration ammonia water of qualified concentration. The fourth path is ammonia water with qualified concentration directly sent to the ammonia water storage tank. The tail gas coming out of the top of the ammonia water tank is combined with the ammonia at the top of the ammonia water storage tank in the tank area and the ammonia discharged during the filling process and then enters Enter the secondary ammonia absorption tower, mix with the dilute ammonia water from the second dilute ammonia water tank to form a relatively concentrated dilute ammonia water and enter the first dilute ammonia water tank. The tail gas from the top of the secondary ammonia absorption tower enters the lower part of the tertiary ammonia absorption tower, mixes with softened water from the outside to form dilute ammonia water and enters the second dilute ammonia water tank. The dilute ammonia water from the bottom of the first dilute ammonia water tank is divided into two paths, one path returns to the ammonia water tank, and the other path flows through the first heat exchanger for cooling and then returns to the upper part of the secondary ammonia absorption tower. The tail gas from the top of the tertiary ammonia absorption tower is vented for treatment. The dilute ammonia water from the bottom of the second dilute ammonia water tank is divided into two paths, one path returns to the first dilute ammonia water tank, and the other path flows through the second heat exchanger for cooling and then returns to the upper part of the tertiary ammonia absorption tower. (5) Preparation of Ammonia Water Liquid ammonia from the liquid ammonia storage tank in the tank area is input into the lower part of the ammonia water preparation device, and softened water from outside the boundary is also input into the upper part of the ammonia water preparation device. The ammonia water prepared by the ammonia water preparation device is sent to the ammonia water storage tank from the lower part of the ammonia water preparation device.

2. The process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia according to claim 1, characterized in that: The tail gas discharged from the air venting buffer tank also directly enters the lower part of the three-stage ammonia absorption tower through a branch line, and the upper part of the three-stage ammonia absorption tower inputs out-of-boundary softened water.

3. The process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia according to claim 1, characterized in that: The hot water outside the boundary is used as a heat source to provide heat energy to the light removal tower reboiler, the heavy removal tower reboiler and the residual liquid vaporizer.

4. The process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia according to claim 3 is characterized by: The external circulating cooling water is used as a cold source to provide cold energy to the light removal tower condenser, heavy removal tower condenser, ammonia water preparation device, high-efficiency ammonia absorber, the first heat exchanger and the second heat exchanger.

5. The process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia according to claim 1, characterized in that: In step (1), the pressure of liquid ammonia in the liquid ammonia storage tank in the tank area at room temperature is 0.8MPa≤P≤1.6MPa, the flow rate is 4000kg / h, and the feed pump is pressurized to 1.9MPa.

6. The process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia according to claim 1, characterized in that: In step (2), the liquid ammonia extracted from the kettle of the light component removal tower is decompressed to 1.7 MPa by pressure difference and then enters the heavy component removal tower.

7. The process for co-producing ammonia water by cascade filtration-medium pressure double-tower distillation of electronic ultrapure ammonia according to claim 1, characterized in that: In step (4), the pressure of the demineralized water at room temperature is ≥0.2 MPa, the flow rate is 16000 kg / h, and the mass concentration of the ammonia water prepared by the ammonia water preparation device is ≥20%.

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