Low-temperature ammonia purification device

Abstract

The utility model relates to a low-temperature ammonia purification device which comprises a barrel body, an upper sealing head, a lower sealing head, an air discharging outlet and an ammonia water outlet, and further comprises a low-temperature desalted water spraying mechanism, an ammonia-containing tail gas input mechanism, a low-temperature ammonia purifier, an intermediate precooler and a circulating absorber, the low-temperature desalted water spraying mechanism and the ammonia-containing tail gas input mechanism are arranged in the top and the bottom of the barrel respectively, the low-temperature ammonia purifier is arranged below the low-temperature desalted water spraying mechanism in the barrel, and the circulation absorber is arranged above the ammonia-containing tail gas input mechanism in the barrel. The middle precooler is arranged between the low-temperature ammonia purifier and the circulating absorber in the barrel; according to the technical scheme, according to the principle that the solubility of the tail gas is greatly improved due to temperature reduction, the ammonia-containing tail gas enters the normal-temperature circulating absorption section to be primarily absorbed, the concentration of absorbed liquid ammonia water is improved, then the tail gas enters the low-temperature ammonia purification section, and the ammonia content of the tail gas is greatly reduced through low-temperature water absorption, so that the purposes of energy conservation, consumption reduction and environment-friendly emission are achieved.

Description

Technical Field

[0001] The utility model relates to a chemical engineering device, in particular to a low-temperature ammonia purification device. Background Art

[0002] In the prior art, the tail gas of a urea production device generally contains 0.5 - 2% ammonia. Directly discharging such tail gas will cause environmental pollution and waste of ammonia. At present, the main treatment method for such tail gas is absorption by normal-temperature water, but the normal-temperature water absorption process can only reduce the ammonia content in the tail gas to about 0.4%, still unable to meet the requirements of energy conservation, consumption reduction and environmental protection emissions. Content of the Utility Model

[0003] In view of this, the main purpose of the utility model is to provide a low-temperature ammonia purification device. Through this technical solution, by using the difference characteristics of the solubility of ammonia in water at different temperatures and the principle that the solubility increases significantly with the decrease of temperature, the defects of the existing process are overcome, and the ammonia content in the tail gas can be greatly reduced to achieve the purpose of energy conservation, consumption reduction and environmental protection emissions.

[0004] To achieve the above purpose, the technical solution of the utility model is realized as follows: A low-temperature ammonia purification device includes a cylinder body, an upper head, a lower head, an air discharge outlet and an ammonia water outlet. The cylinder body is arranged vertically. The upper head and the lower head are respectively fixedly arranged at the top and the bottom of the cylinder body. The air discharge outlet and the ammonia water outlet are respectively arranged on the upper head and the lower head. It also includes a low-temperature desalted water spraying mechanism, an ammonia-containing tail gas input mechanism, a low-temperature ammonia purifier, an intermediate pre-cooler and a circulating absorber. The low-temperature desalted water spraying mechanism and the ammonia-containing tail gas input mechanism are respectively arranged inside the top and the bottom of the cylinder body. The low-temperature ammonia purifier is arranged below the low-temperature desalted water spraying mechanism inside the cylinder body. The circulating absorber is arranged above the ammonia-containing tail gas input mechanism inside the cylinder body. The intermediate pre-cooler is arranged between the low-temperature ammonia purifier and the circulating absorber inside the cylinder body.

[0005] As a further technical solution, the low-temperature desalted water spraying mechanism is composed of a low-temperature desalted water delivery pipe and a spray head. The low-temperature desalted water delivery pipe extends from the outside of the top of the cylinder body into the cylinder body. The spray head is connected to the low-temperature desalted water delivery pipe inside the cylinder body, and the spray head is located in the middle of the cylinder body and sprays downward.

[0006] As a further technical solution, the low-temperature ammonia scrubber and the circulation absorber are respectively composed of a packing support grid plate, a packing pressing grid, a discharge port and Pall ring packings. The packing support grid plates are respectively arranged at the bottoms of the low-temperature ammonia scrubber and the circulation absorber and fixed on the inner walls of the corresponding cylinders. The two packing pressing grids are respectively arranged above the packing support grid plates in the cylinders. The Pall ring packings are arranged between the two corresponding packing pressing grids in the cylinders. The lower packing pressing grid presses against the packing support grid plate, and the lower surface of the upper packing pressing grid presses against the Pall ring packings. The discharge port is arranged on the side wall of the cylinder corresponding to the lower parts of the low-temperature ammonia scrubber and the circulation absorber.

[0007] As a further technical solution, the intermediate precooler is composed of a shell-and-tube heat exchanger, a dilute ammonia water inlet and a dilute ammonia water outlet. The shell-and-tube heat exchanger is arranged vertically. The dilute ammonia water inlet and the dilute ammonia water outlet are respectively arranged on the outer sides of the cylinder at the corresponding upper and lower positions of the intermediate precooler. The dilute ammonia water inlet and the dilute ammonia water outlet are respectively communicated with the shell side of the shell-and-tube heat exchanger. The ammonia-containing tail gas flows upward through the tube side of the shell-and-tube heat exchanger and exchanges heat with the low-temperature dilute ammonia water on the shell side to reduce the temperature of the ammonia-containing tail gas.

[0008] As a further technical solution, the ammonia-containing tail gas input mechanism is composed of an ammonia-containing tail gas inlet and a gas distributor. The ammonia-containing tail gas inlet is arranged on the outer side wall of the bottom of the cylinder. The gas distributor is arranged in the cylinder at the corresponding position of the ammonia-containing tail gas inlet. The gas distributor is arranged horizontally and communicated with the ammonia-containing tail gas inlet.

[0009] As a further technical solution, it further includes a low-temperature clean ammonia water outlet, a riser and a riser baffle. The riser is arranged in the cylinder between the low-temperature water purifier and the intermediate precooler. The lower end of the riser is fixed on the inner wall of the cylinder around. The low-temperature clean ammonia water outlet is arranged on the side wall of the cylinder above the lower end of the riser. The riser baffle is arranged above the gas outlet of the riser.

[0010] As a further technical solution, it further includes an ammonia water recirculation mechanism. The ammonia water recirculation mechanism is composed of an ammonia water circulation pump, an inlet valve, a filter, a check valve, a circulation pipeline, an ammonia water external discharge pipeline, an external discharge outlet valve, a circulation outlet valve and a circulation spray head. One end of the circulation pipeline is connected to the ammonia water outlet arranged at the bottom of the cylinder. The inlet valve, the filter, the ammonia water circulation pump, the check valve and the circulation outlet valve are sequentially connected in series on the circulation pipeline. The other end of the circulation pipeline extends into the cylinder above the circulation absorber and is connected to the circulation spray head. The ammonia water external discharge pipeline is communicated with the check valve through the external discharge outlet valve.

[0011] As a further technical solution, it further includes an ammonia water redistribution mechanism, which is composed of an ammonia water redistribution inlet, a redistribution spray pipe, and a redistributor. The ammonia water redistribution inlet is arranged on the outer side wall of the cylinder body below the intermediate pre-cooler. The redistribution spray pipe is horizontally arranged in the cylinder body. One end of the redistribution spray pipe is connected to the ammonia water redistribution inlet. The redistributor is horizontally arranged below the redistribution spray pipe.

[0012] As a further technical solution, the low-temperature ammonia purifier and the circulation absorber further include wire meshes, which are arranged between the lower part of the packing pressing grid and the upper part of the packing support grid plate.

[0013] As a further technical solution, it further includes manholes, which are respectively arranged on the side wall of the cylinder body at the positions of the spray heads in the low-temperature desalted water spraying mechanism and the circulation spray heads in the ammonia water recirculation mechanism.

[0014] The beneficial effects after adopting the above technical solutions are as follows: A low-temperature ammonia purification device utilizes the difference characteristics of the solubility of ammonia gas in water at different temperatures, and the principle that its solubility increases significantly with the decrease of temperature, overcomes the defects of the existing process. The ammonia-containing tail gas enters the normal-temperature circulation absorption section for preliminary absorption to increase the concentration of the absorption liquid ammonia water, and then enters the low-temperature ammonia purification section, using low-temperature water (0 - 5°C) for absorption to greatly reduce the ammonia content in the tail gas, so as to achieve the purpose of energy conservation, consumption reduction, and environmental protection emissions. Description of the Drawings

[0015] Attached Figure 1 It is a schematic diagram of the overall connection structure of the utility model.

[0016] Attached Figure 2 It is a schematic diagram of the overall structure of the utility model.

[0017] In the figure, 1 is the cylinder body, 2 is the upper head, 3 is the lower head, 4 is the air release outlet, 5 is the ammonia water outlet, 6 is the low-temperature desalted water spraying mechanism, 7 is the ammonia-containing tail gas input mechanism, 8 is the low-temperature ammonia purifier, 9 is the intermediate pre-cooler, 10 is the circulation absorber, 11 is the low-temperature desalted water delivery pipe, 12 is the spray head, 13 is the packing support grid plate, 14 is the packing pressing grid, 15 is the discharge port, 16 is the Pall ring packing, 17 is the shell and tube heat exchanger, 18 is the dilute ammonia water inlet, 19 is the dilute ammonia water outlet, 20 is the ammonia-containing tail gas inlet, 21 is the gas distributor, 22 is the low-temperature purified ammonia water outlet, 23 is the riser, 24 is the ammonia water recirculation mechanism, 25 is the ammonia water circulation pump, 26 is the inlet valve, 27 is the filter, 28 is the check valve, 29 is the circulation pipeline, 30 is the ammonia water external discharge pipeline, 31 is the external discharge outlet valve, 32 is the circulation outlet valve, 33 is the circulation spray head, 34 is the ammonia water redistribution mechanism, 35 is the ammonia water redistribution inlet, 36 is the redistribution spray pipe, 37 is the redistributor, 38 is the wire mesh, 39 is the manhole, 40 is the riser baffle. Detailed Embodiments

[0018] The following will further elaborate on specific embodiments of the present utility model in conjunction with the accompanying drawings.

[0019] The low-temperature ammonia purification device involved in the present utility model includes a cylinder body 1, an upper head 2, a lower head 3, an air release outlet 4, and an ammonia water outlet 5. The cylinder body 1 is vertically arranged. The upper head 2 and the lower head 3 are respectively fixedly arranged at the top and bottom of the cylinder body 1. The air release outlet 4 and the ammonia water outlet 5 are respectively arranged on the upper head 2 and the lower head 3. It further includes a low-temperature desalted water spraying mechanism 6, an ammonia-containing tail gas input mechanism 7, a low-temperature ammonia purifier 8, an intermediate pre-cooler 9, and a circulating absorber 10. The low-temperature desalted water spraying mechanism 6 and the ammonia-containing tail gas input mechanism 7 are respectively arranged inside the top and bottom of the cylinder body 1. The low-temperature ammonia purifier 8 is arranged below the low-temperature desalted water spraying mechanism 6 inside the cylinder body 1. The circulating absorber 10 is arranged above the ammonia-containing tail gas input mechanism 7 inside the cylinder body 1. The intermediate pre-cooler 9 is arranged between the low-temperature ammonia purifier 8 and the circulating absorber 10 inside the cylinder body 1.

[0020] As a further embodiment, the low-temperature desalted water spraying mechanism 6 is composed of a low-temperature desalted water delivery pipe 11 and a spray head 12. The low-temperature desalted water delivery pipe 11 extends from the outside of the top of the cylinder body 1 into the cylinder body 1. The spray head 12 is connected to the low-temperature desalted water delivery pipe 11 inside the cylinder body 1, and the spray head 12 is located in the middle and sprays downward inside the cylinder body 1.

[0021] As a further embodiment, the low-temperature ammonia purifier 8 and the circulating absorber 10 are respectively composed of a packing support grid plate 13, a packing pressing grid 14, a discharge port 15, and Pall ring packings 16. The packing support grid plate 13 is respectively arranged at the bottoms of the low-temperature ammonia purifier 8 and the circulating absorber 10 and is fixed on the inner wall of the corresponding cylinder body 1. Two packing pressing grids 14 are respectively arranged above the packing support grid plate 13 inside the cylinder body 1. The Pall ring packings 16 are arranged between the two corresponding packing pressing grids 14 inside the cylinder body 1. The lower packing pressing grid 14 presses against the packing support grid plate 13, and the lower surface of the upper packing pressing grid 14 presses against the Pall ring packings 16. The discharge port 15 is arranged on the side wall of the cylinder body 1 corresponding to the lower parts of the low-temperature ammonia purifier 8 and the circulating absorber 10.

[0022] As a further embodiment, the intermediate pre-cooler 9 is composed of a shell-and-tube heat exchanger 17, a dilute ammonia water inlet 18, and a dilute ammonia water outlet 19. The shell-and-tube heat exchanger 17 is vertically arranged. The dilute ammonia water inlet 18 and the dilute ammonia water outlet 19 are respectively arranged on the outside of the cylinder body 1 at the corresponding upper and lower positions of the intermediate pre-cooler 9. The dilute ammonia water inlet 18 and the dilute ammonia water outlet 19 are respectively communicated with the shell side of the shell-and-tube heat exchanger 17. The ammonia-containing tail gas flows upward through the tube side of the shell-and-tube heat exchanger 17 and exchanges heat with the low-temperature dilute ammonia water in the shell side to reduce the temperature of the ammonia-containing tail gas.

[0023] As a further embodiment, the ammonia-containing tail gas input mechanism 7 is composed of an ammonia-containing tail gas inlet 20 and a gas distributor 21. The ammonia-containing tail gas inlet 20 is arranged on the outer side wall of the bottom of the cylinder body 1, and the gas distributor 21 is arranged in the cylinder body 1 at the position corresponding to the ammonia-containing tail gas inlet 20. The gas distributor 21 is horizontally arranged and communicated with the ammonia-containing tail gas inlet 20.

[0024] As a further embodiment, it further includes a low-temperature purified ammonia water outlet 22, a riser 23 and a riser baffle 40. The riser 23 is arranged in the cylinder body 1 between the low-temperature water purifier 8 and the intermediate precooler 9. The periphery of the lower end of the riser 23 is fixed on the inner wall of the cylinder body 1. The low-temperature purified ammonia water outlet 22 is arranged on the side wall of the cylinder body 1 above the lower end of the riser 23. The riser baffle 40 is arranged above the air outlet of the riser 23.

[0025] As a further embodiment, it further includes an ammonia water recirculation mechanism 24. The ammonia water recirculation mechanism 24 is composed of an ammonia water circulation pump 25, an inlet valve 26, a filter 27, a check valve 28, a circulation pipeline 29, an ammonia water external discharge pipeline 30, an external discharge outlet valve 31, a circulation outlet valve 32 and a circulation spray head 33. One end of the circulation pipeline 29 is connected to the ammonia water outlet 5 arranged at the bottom of the cylinder body 1. The inlet valve 26, the filter 27, the ammonia water circulation pump 25, the check valve 28 and the circulation outlet valve 32 are sequentially connected in series on the circulation pipeline 29. The other end of the circulation pipeline 29 extends into the cylinder body 1 above the circulation absorber 10 and is connected to the circulation spray head 33. The ammonia water external discharge pipeline 30 is communicated with the check valve 28 through the external discharge outlet valve 31.

[0026] As a further embodiment, it further includes an ammonia water redistribution mechanism 34. The ammonia water redistribution mechanism 34 is composed of an ammonia water redistribution inlet 35, a redistribution spray pipe 36 and a redistributor 37. The ammonia water redistribution inlet 35 is arranged on the outer side wall of the cylinder body 1 below the intermediate precooler 9. The redistribution spray pipe 36 is horizontally arranged in the cylinder body 1. One end of the redistribution spray pipe 36 is connected to the ammonia water redistribution inlet 35. The redistributor 37 is horizontally arranged below the redistribution spray pipe 36.

[0027] As a further embodiment, the low-temperature ammonia purifier 8 and the circulation absorber 10 further include a wire mesh 38. The wire mesh 38 is arranged between the packing pressing grid 14 and the packing support grid plate 13.

[0028] As a further embodiment, it further includes a manhole 39. The manholes 39 are respectively arranged on the side wall of the cylinder body 1 at the positions of the spray head 12 in the low-temperature desalted water spraying mechanism 6 and the circulation spray head 33 in the ammonia water recirculation mechanism 24.

[0029] During operation, taking a 400,000-ton / year urea plant as an example: its ammonia-containing tail gas volume is 1500 Nm3 / h, with an NH3 content of approximately 0.5%, and the tail gas pressure of 0.3 MPaG. It enters the low-temperature ammonia purification device isobarically.

[0030] Firstly, it passes through the ammonia-containing tail gas inlet 20 and the gas distributor 21 of the ammonia-containing tail gas input mechanism 7, and is evenly distributed into the Pall rings 16 of the circulation absorber 10, where it countercurrently absorbs ammonia with the ammonia water from the intermediate precooler 9 and the ammonia water recirculation mechanism 24 from the upper part, initially reducing the ammonia content of the ammonia-containing tail gas, increasing the concentration of the circulating ammonia water, and the concentrated ammonia water is sent out through the ammonia water external discharge pipeline 30.

[0031] The ammonia-containing tail gas after being washed and absorbed by the circulation absorber 10 enters the tube side of the intermediate precooler 9 upwards, exchanges heat with the low-temperature dilute ammonia water from the low-temperature ammonia purifier 8 in the shell side. After the temperature of the ammonia-containing tail gas decreases, it continues to rise upwards through the riser 23 and the riser baffle 40 and enters the low-temperature ammonia purifier 8.

[0032] In the low-temperature ammonia purifier 8, the ammonia-containing tail gas enters the Pall rings 16, and undergoes countercurrent mass and heat exchange with the low-temperature demineralized water evenly sprayed by the spray heads 12 of the low-temperature demineralized water spraying mechanism 6 above, fully absorbing the ammonia in the ammonia-containing tail gas, and is discharged from the air outlet 4 of the upper head 2 of the cylinder 1 after reaching the emission standard.

[0033] An intermediate precooler 9 is arranged between the low-temperature ammonia purifier 8 and the circulation absorber 10, enabling the low-temperature water to fully exchange heat with the ammonia-containing tail gas. After the gas temperature decreases, it enters the low-temperature ammonia purifier 8 for absorption, improving the solubility of the gas.

[0034] As described above, it is only a preferred and feasible embodiment of the present utility model, and is not intended to limit the scope of the present utility model.

Claims

1. A low-temperature ammonia purification device, comprising a cylinder body, an upper head, a lower head, an air discharge outlet and an ammonia water outlet. The cylinder body is arranged vertically. The upper head and the lower head are respectively fixedly arranged at the top and bottom of the cylinder body. The air discharge outlet and the ammonia water outlet are respectively arranged on the upper head and the lower head. It is characterized in that, It also includes a low-temperature demineralized water spraying mechanism, an ammonia-containing tail gas input mechanism, a low-temperature ammonia purifier, an intermediate pre-cooler, and a circulating absorber. The low-temperature demineralized water spraying mechanism and the ammonia-containing tail gas input mechanism are respectively arranged inside the top and bottom of the cylinder body. The low-temperature ammonia purifier is arranged below the low-temperature demineralized water spraying mechanism inside the cylinder body. The circulating absorber is arranged above the ammonia-containing tail gas input mechanism inside the cylinder body. The intermediate pre-cooler is arranged between the low-temperature ammonia purifier and the circulating absorber inside the cylinder body.

2. The low-temperature ammonia purification device according to claim 1, wherein, The low-temperature demineralized water spraying mechanism consists of a low-temperature demineralized water delivery pipe and a spray head. The low-temperature demineralized water delivery pipe extends from the outside of the top of the cylinder body into the cylinder body. The spray head is connected to the low-temperature demineralized water delivery pipe inside the cylinder body, and the spray head is located in the middle of the cylinder body and sprays downward.

3. The low-temperature ammonia purification device according to claim 1, characterized in that, The low-temperature ammonia purifier and the circulating absorber respectively consist of a packing support grid plate, a packing pressing grid, a discharge port, and Pall ring packings. The packing support grid plates are respectively arranged at the bottoms of the low-temperature ammonia purifier and the circulating absorber and are fixed on the corresponding inner walls of the cylinder body. The two packing pressing grids are respectively arranged above the packing support grid plates inside the cylinder body. The Pall ring packings are arranged between the two corresponding packing pressing grids inside the cylinder body. The lower packing pressing grid presses against the packing support grid plate, and the lower surface of the upper packing pressing grid presses against the Pall ring packings. The discharge port is arranged on the side wall of the cylinder body corresponding to the lower parts of the low-temperature ammonia purifier and the circulating absorber.

4. The low-temperature ammonia purification device according to claim 1, wherein, The intermediate pre-cooler consists of a shell-and-tube heat exchanger, a dilute ammonia water inlet, and a dilute ammonia water outlet. The shell-and-tube heat exchanger is arranged vertically. The dilute ammonia water inlet and the dilute ammonia water outlet are respectively arranged on the outside of the cylinder body at the corresponding positions of the upper and lower parts of the intermediate pre-cooler. The dilute ammonia water inlet and the dilute ammonia water outlet are respectively connected to the shell side of the shell-and-tube heat exchanger. The ammonia-containing tail gas flows upward through the tube side of the shell-and-tube heat exchanger and exchanges heat with the low-temperature dilute ammonia water on the shell side to reduce the temperature of the ammonia-containing tail gas.

5. The low-temperature ammonia purification device according to claim 1, wherein, The ammonia-containing tail gas input mechanism consists of an ammonia-containing tail gas inlet and a gas distributor. The ammonia-containing tail gas inlet is arranged on the outer side wall of the bottom of the cylinder body. The gas distributor is arranged inside the cylinder body at the corresponding position of the ammonia-containing tail gas inlet. The gas distributor is arranged horizontally and is connected to the ammonia-containing tail gas inlet.

6. The low-temperature ammonia purification device according to claim 1, wherein It also includes a low-temperature clean ammonia water outlet, a riser and a riser baffle. The riser is arranged inside the cylinder body between the low-temperature ammonia purifier and the intermediate pre-cooler. The lower end of the riser is fixed around the inner wall of the cylinder body. The low-temperature clean ammonia water outlet is arranged on the side wall of the cylinder body above the lower end of the riser. The riser baffle is arranged above the gas outlet of the riser.

7. The low-temperature ammonia purification device according to claim 1, wherein It also includes an ammonia water recirculation mechanism. The ammonia water recirculation mechanism consists of an ammonia water circulation pump, an inlet valve, a filter, a check valve, a circulation pipeline, an ammonia water external discharge pipeline, an external discharge outlet valve, a circulation outlet valve, and a circulation spray head. One end of the circulation pipeline is connected to the ammonia water outlet arranged at the bottom of the cylinder body. The inlet valve, the filter, the ammonia water circulation pump, the check valve, and the circulation outlet valve are sequentially connected in series on the circulation pipeline. The other end of the circulation pipeline extends into the cylinder body above the circulating absorber and is connected to the circulation spray head. The ammonia water external discharge pipeline is connected to the check valve through the external discharge outlet valve.

8. The low-temperature ammonia purification device according to claim 1, wherein It further includes an ammonia water redistribution mechanism, which consists of an ammonia water redistribution inlet, a redistribution spray pipe, and a redistributor. The ammonia water redistribution inlet is arranged on the outer side wall of the cylinder body below the intermediate pre-cooler. The redistribution spray pipe is horizontally arranged in the cylinder body, one end of the redistribution spray pipe is connected to the ammonia water redistribution inlet, and the redistributor is horizontally arranged below the redistribution spray pipe.

9. The low-temperature ammonia purification device according to claim 3, wherein The low-temperature ammonia purifier and the circulation absorber further include wire meshes, which are arranged between the lower part of the packing pressing grid and the upper part of the packing support grid plate.

10. The low-temperature ammonia purification device according to claim 2 or 7, characterized in that, It further includes manholes, which are respectively arranged on the side walls of the cylinder body at the positions of the spray heads in the low-temperature desalted water spraying mechanism and the circulating spray heads in the ammonia water recirculation mechanism.

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