Treatment process and device for low-grade ammonia-containing waste heat steam

Abstract

This invention belongs to the field of waste gas recovery technology, specifically relating to a treatment process and apparatus for low-grade ammonia-containing waste heat steam. The process involves compressing and heating the ammonia-containing waste heat steam to obtain superheated steam. A portion of the superheated steam is exchanged with the bottom liquid of a deammoniation tower to obtain dilute ammonia water and a heated bottom liquid. The remaining superheated steam is exchanged with cold water to obtain dilute ammonia water and hot water. The hot water is then flash-evaporated to obtain secondary steam and saturated water. The secondary steam is then compressed, humidified, and saturated to obtain high-grade steam. The dilute ammonia water undergoes deammoniation treatment to obtain concentrated ammonia water. This invention's treatment process fully utilizes the heat from the ammonia-containing waste heat steam to heat the bottom liquid and cold water of the deammoniation tower, which is beneficial for energy saving in the deammoniation process, recovering ammonia resources, and co-producing high-grade steam. This eliminates the need for large amounts of process water, improves ammonia recovery efficiency, and avoids the generation of ammonium salt waste liquid, reducing water treatment costs and possessing high economic value.

Description

Technical Field

[0001] This invention belongs to the field of waste gas recovery technology, specifically relating to a treatment process and apparatus for low-grade ammonia-containing waste heat steam. Background Technology

[0002] In industrial production (such as hydrometallurgical processes), ammonia is often used as a buffer. After product production, the reaction vessel needs to be heated to remove ammonia as ammonia vapor. This ammonia-containing vapor has a temperature of around 95°C, and both the vapor temperature and the ammonia concentration are high. Directly releasing it into the atmosphere would cause environmental pollution and resource waste. If it leaks into the workshop, it will have a pungent odor, preventing workers from working normally. Therefore, from both environmental and economic perspectives, it is essential to recover this ammonia-containing waste heat vapor.

[0003] The usual treatment methods are direct absorption with water or absorption with dilute acid. Water absorption requires a large amount of process water, and even so, the ammonia recovery efficiency is low, and the heat of the ammonia-containing waste heat steam cannot be recovered. In addition, the low-concentration ammonia water generated needs further treatment. When dilute acid is used for absorption, an ammonium salt solution is generated, which needs to be further evaporated, concentrated and separated. Although this method treats ammonia thoroughly, it cannot recover heat and also increases the economic cost of water treatment.

[0004] It is evident that existing methods for treating ammonia-containing waste heat steam cannot recover heat simultaneously with ammonia recovery, and their ammonia recovery efficiency is low while their processing costs are high. Therefore, there is an urgent need to develop a process for treating ammonia-containing waste heat steam that achieves high ammonia recovery efficiency, low processing costs, and simultaneous heat recovery, thereby enabling the recycling and reuse of ammonia-containing waste heat steam. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is that the existing technology cannot recover heat when treating ammonia-containing waste heat steam, has low ammonia recovery efficiency and high treatment cost. Therefore, by optimizing and improving the recovery scheme, the present invention provides an ammonia-containing waste heat steam treatment process and device with high ammonia recovery efficiency, low treatment cost and heat recovery capability.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] According to an embodiment of the present invention, in a first aspect, the present invention provides a process for treating low-grade ammonia-containing waste heat steam, comprising the following steps:

[0008] S1. The ammonia-containing waste heat steam is compressed and heated to obtain superheated steam. A portion of the superheated steam is then exchanged with the liquid in the bottom of the ammonia removal tower to obtain dilute ammonia water.

[0009] The temperature of the ammonia-containing waste heat steam is 85~100℃, and the ammonia content is 1~2wt%.

[0010] The temperature of the superheated steam is 107~120℃ and the pressure is 0.10~0.2MPa;

[0011] S2. The remaining superheated steam is exchanged with cold water to obtain dilute ammonia water and hot water; the hot water is flash-evaporated to obtain secondary steam and saturated water; the secondary steam is compressed, humidified and saturated to obtain high-grade steam with a temperature of 110~120℃ and a pressure of 0.15~0.2MPa.

[0012] In an embodiment of the present invention, in step S1 of the processing technology, the temperature of the liquid in the deammoniation tower before and after heat exchange is 98~100℃ and 102~105℃, respectively.

[0013] In an embodiment of the present invention, in step S2 of the processing technology, the pressure of the hot water is 0.1~0.2MPa and the temperature is 98~102℃.

[0014] In an embodiment of the present invention, in step S2 of the processing technology, the flash evaporation treatment is performed at a pressure of 0.05~0.1MPa, a temperature of 90~98℃, and a residence time of 15~30min.

[0015] In an embodiment of the present invention, step S2 of the processing technology further includes reusing a portion of the saturated water for heat exchange with the remaining portion of the superheated steam, wherein the remaining portion of the saturated water is used to humidify the compressed secondary steam. The processing technology of the present invention utilizes the saturated water generated in the flash evaporation process in both the preceding heat exchange process and the subsequent humidification process, thereby maximizing water resource conservation.

[0016] In an embodiment of the present invention, step S2 of the processing technology further includes reusing the liquid generated after humidification saturation for the flash evaporation treatment.

[0017] In an embodiment of the present invention, the processing technology further includes step S3, in which the dilute ammonia water obtained in step S1 and / or step S2 is fed into the top of the deammoniation tower for deammoniation treatment to obtain concentrated ammonia water with an ammonia content of 18~25wt%.

[0018] It is understood that in the embodiments of the present invention, the term "cold water" is relative to the superheated steam at the hot side inlet of the heat exchanger, and the temperature of the cold water is lower than the temperature of the superheated steam at the hot side inlet of the heat exchanger; the term "hot water" is relative to "cold water", and the cold water is transformed into hot water through heat exchange.

[0019] In embodiments of the present invention, the raw material for the treatment process, ammonia-containing waste heat steam, can be, for example, from a hydrometallurgical process, specifically ammonia vapor volatilized during the heating process of the hydrometallurgical reactor. Since the temperature of this type of ammonia vapor is insufficient to concentrate the dilute ammonia water in the deammoniation tower, and the wastewater discharged from the tower bottom will contain a large amount of ammonia nitrogen, the low-grade ammonia-containing waste heat steam must be heated to meet the process requirements. The high-grade steam obtained by the treatment process can also be reused in the hydrometallurgical process, used to add ammonia water in the reactor as a hydrometallurgical reaction aid to improve the purity of the metallurgical process. Therefore, the treatment process provided by the present invention can recover the heat of ammonia-containing waste heat steam, converting low-grade ammonia-containing waste heat steam into high-grade steam. Simultaneously, the co-produced concentrated ammonia water can also be reused in the hydrometallurgical process, so that the hydrometallurgical process does not consume ammonia, does not generate additional wastewater, and does not require a large supply of steam; only a small amount of fresh steam is needed to meet the process production needs, which has high economic value.

[0020] According to an embodiment of the present invention, in a second aspect, the present invention also provides a treatment apparatus for low-grade ammonia-containing waste heat steam, comprising:

[0021] The first compressor is used to compress and heat ammonia-containing waste heat steam to obtain superheated steam.

[0022] A reboiler, the hot side inlet of which is connected to the outlet of the first compressor, is used to exchange heat between a portion of the superheated steam and the bottom liquid of the deammoniation tower.

[0023] A heat exchanger, the hot side inlet of which is connected to the outlet of the first compressor, is used to exchange heat between the remaining portion of the superheated steam and cold water.

[0024] A flash tank is connected to the cold side outlet of the heat exchanger. The flash tank is used to flash-evaporate the hot water generated after heat exchange by the heat exchanger to obtain secondary steam and saturated water.

[0025] The second compressor is connected to the gas outlet of the flash tank and is used to compress the secondary steam.

[0026] The humidification and saturation tank has its inlet connected to the outlet of the second compressor. The humidification and saturation tank is used to humidify and saturate the secondary steam after it has been compressed by the second compressor.

[0027] In an embodiment of the present invention, the liquid outlet of the humidification saturation tank in the processing device is connected to the flash tank, for recycling the liquid generated after humidification saturation for flash evaporation treatment.

[0028] In an embodiment of the present invention, the processing apparatus further includes a humidification pump and a circulation pump. The inlet of the humidification pump is connected to the outlet of the flash tank, and the outlet of the humidification pump is connected to the inlet of the humidification saturation tank. The inlet of the circulation pump is connected to the outlet of the flash tank, and the outlet of the circulation pump is connected to the cold-side inlet of the heat exchanger. The processing apparatus of the present invention uses the saturated water generated in the flash evaporation process for the preceding heat exchange process and the subsequent humidification process, thereby maximizing water conservation.

[0029] In an embodiment of the present invention, the processing device further includes a dilute ammonia water storage tank, a dilute ammonia water pump, and a deammoniation tower connected in sequence. The inlet of the dilute ammonia water storage tank is connected to the hot side outlet of the reboiler and / or the hot side outlet of the heat exchanger. The inlet of the dilute ammonia water pump is connected to the outlet of the dilute ammonia water storage tank. The top feed inlet of the deammoniation tower is connected to the outlet of the dilute ammonia water pump. The bottom liquid outlet of the deammoniation tower is connected to the cold side inlet of the reboiler. The bottom liquid inlet of the deammoniation tower is connected to the cold side outlet of the reboiler.

[0030] In an embodiment of the present invention, the processing apparatus further includes a top condenser, an ammonia condenser, and a concentrated ammonia storage tank connected in sequence. The hot-side inlet of the top condenser is connected to the gas outlet of the ammonia removal tower, the hot-side inlet of the ammonia condenser is connected to the hot-side outlet of the top condenser, and the inlet of the concentrated ammonia storage tank is connected to the hot-side outlet of the ammonia condenser. Dilute ammonia water is stripped and deammonified in the ammonia removal tower, and the ammonia vapor at the top of the tower is condensed through a two-stage condenser, continuously increasing its concentration, ultimately yielding concentrated ammonia water with an ammonia content of 18-25 wt%.

[0031] The processing apparatus of this invention, through the ingenious arrangement described above, utilizes the heat from the compressed and heated ammonia-containing waste heat steam. Part of this heat is used to heat the bottom liquid of the deammoniation tower via a reboiler. The resulting condensate, dilute ammonia water, is discharged from the hot side outlet of the reboiler, and the heated bottom liquid of the deammoniation tower is returned to the deammoniation tower. The remaining heat is exchanged with cold water in a heat exchanger, fully recovering the heat from the waste steam. The resulting hot water undergoes flash evaporation, compression, and humidification saturation treatment sequentially to obtain high-grade steam. Simultaneously, the resulting condensate, dilute ammonia water, is discharged from the hot side outlet of the heat exchanger. The dilute ammonia water from the heat exchanger and / or reboiler then enters the top of the deammoniation tower for deammoniation treatment, ultimately yielding concentrated ammonia water. This not only recovers the heat from the ammonia-containing waste heat steam and produces high-grade steam, but also recovers ammonia resources.

[0032] The processing device of the present invention can be connected to a hydrometallurgical apparatus. Specifically, the exhaust port of the reactor in the hydrometallurgical apparatus can be connected to the inlet of the first compressor in the processing device of the present invention. At the same time, the exhaust port of the humidification saturation tank in the processing device of the present invention can be connected to the air inlet of the reactor in the hydrometallurgical apparatus, and the outlet of the concentrated ammonia water storage tank in the processing device of the present invention can be connected to the liquid inlet of the reactor in the hydrometallurgical apparatus. In this way, the ammonia-containing waste heat steam discharged from the reactor can directly enter the processing device of the present invention, converting the low-grade ammonia-containing waste heat steam into high-grade water steam. At the same time, the co-produced concentrated ammonia water can also be reused in the hydrometallurgical process, so that the hydrometallurgical process does not consume ammonia, does not generate additional wastewater, and does not require a large supply of water steam. Only a small amount of fresh steam is needed to meet the production needs of the process, which has high economic value.

[0033] In an embodiment of the present invention, the operating parameters of the first compressor in the processing device include: inlet temperature 85~100℃, pressure 0.05~0.10MPa; outlet temperature and pressure 107~120℃, pressure 0.1~0.2MPa.

[0034] In embodiments of the present invention, the operating parameters of the reboiler in the processing apparatus include:

[0035] Hot side: Inlet temperature 107~120℃, inlet pressure 0.10~0.20MPa, outlet temperature 102~105℃, outlet pressure 0.1~0.2MPa; Cold side: Inlet temperature 98~100℃, inlet pressure is atmospheric pressure, outlet temperature 102~105℃, outlet pressure is atmospheric pressure.

[0036] In an embodiment of the present invention, the operating parameters of the flash tank in the processing device include: temperature 90~98℃, pressure 0.05~0.1MPa, and residence time 15~30min.

[0037] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0038] 1. The low-grade ammonia-containing waste heat steam treatment process provided in this embodiment of the invention involves compressing and heating the ammonia-containing waste heat steam to obtain superheated steam. A portion of the superheated steam is then exchanged with the bottom liquid of the ammonia removal tower to recover the heat from the ammonia-containing waste heat steam, yielding dilute ammonia water and the heated bottom liquid of the ammonia removal tower. The remaining superheated steam is further exchanged with cold water to obtain dilute ammonia water and hot water. The hot water is then flash-evaporated to obtain secondary steam and saturated water. This secondary steam is then compressed, humidified, and saturated to obtain high-grade steam with a temperature of 110-120°C and a pressure of 0.15-0.20 MPa. The secondary steam obtained using flash evaporation technology does not contain ammonia, facilitating its use as a heat source in subsequent processes without contaminating the product. This process fully utilizes the heat from the ammonia-containing waste heat steam to heat the bottom liquid of the ammonia removal tower and cold water, which not only saves energy in the ammonia removal process but also generates high-grade steam, achieving heat recovery from the ammonia-containing waste heat steam. Furthermore, the treatment process of this invention uses heat exchange to condense ammonia-containing waste heat steam into dilute ammonia water. Compared with the direct water absorption method in the prior art, it does not require a large amount of process water, and at the same time improves the recovery efficiency of ammonia and avoids the generation of dilute ammonia water with lower concentration. Compared with the dilute acid absorption method in the prior art, this invention does not generate ammonium salt waste liquid, which greatly reduces the cost of water treatment.

[0039] 2. The low-grade ammonia-containing waste heat steam treatment process provided in this embodiment of the invention, by sending the generated dilute ammonia water to the top of the deammoniation tower for deammoniation treatment, can obtain concentrated ammonia water with an ammonia content of 18~25wt%. This not only recovers the heat of the ammonia-containing waste heat steam, but also recovers the ammonia resources, further improving the economic benefits of the invention.

[0040] 3. The low-grade ammonia-containing waste heat steam treatment device provided in this embodiment of the invention includes a first compressor, a reboiler and a heat exchanger respectively connected to the first compressor, a flash tank connected in sequence to the heat exchanger, a second compressor, and a humidification saturation tank. The heat from the compressed and heated ammonia-containing waste heat steam is partially used in the reboiler to heat the bottom liquid of the deammoniation tower. The remaining heat can be further used as a heat source to exchange heat with cold water in the heat exchanger, fully recovering the heat of the waste steam. The resulting hot water is then subjected to flash evaporation, compression, and humidification saturation treatment to obtain high-grade steam. This achieves heat recovery from the ammonia-containing waste heat steam and also produces high-grade steam, which has high economic value.

[0041] 4. The low-grade ammonia-containing waste heat steam treatment device provided in this embodiment of the invention further includes a dilute ammonia water storage tank, a dilute ammonia water pump, and an ammonia removal tower. The inlet of the dilute ammonia water storage tank is connected to the hot-side outlet of the reboiler and / or the hot-side outlet of the heat exchanger. The inlet of the dilute ammonia water pump is connected to the outlet of the dilute ammonia water storage tank. The top feed inlet of the ammonia removal tower is connected to the outlet of the dilute ammonia water pump. The bottom liquid outlet of the ammonia removal tower is connected to the cold-side inlet of the reboiler, and the bottom liquid inlet of the ammonia removal tower is connected to the cold-side outlet of the reboiler. This allows dilute ammonia water from the heat exchanger and / or the reboiler to enter the top of the ammonia removal tower for ammonia removal treatment, ultimately yielding concentrated ammonia water. This not only recovers the heat of the ammonia-containing waste heat steam but also recovers ammonia resources, further improving the economic benefits of the invention. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A flowchart of the treatment process for low-grade ammonia-containing waste heat steam provided in Embodiment 3 of the present invention;

[0044] The reference numerals in the attached figures are explained as follows:

[0045] 1-First compressor; 2-Reboiler; 3-Heat exchanger; 4-Flash tank; 5-Second compressor; 6-Humidification saturation tank; 7-Humidification pump; 8-Circulation pump; 9-Dilute ammonia water pump; 10-Dilute ammonia water storage tank; 11-Ammonia removal tower; 12-Tower top condenser; 13-Ammonia condenser. Detailed Implementation

[0046] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0047] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can also refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0048] Where specific experimental steps or conditions are not specified in the embodiments of the present invention, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0049] Example 1

[0050] The device for treating low-grade ammonia-containing waste heat steam in this embodiment includes:

[0051] The first compressor is used to compress and heat ammonia-containing waste heat steam to obtain superheated steam.

[0052] A reboiler, the hot side inlet of which is connected to the outlet of the first compressor, is used to exchange heat between a portion of the superheated steam and the bottom liquid of the deammoniation tower.

[0053] A heat exchanger, the hot side inlet of which is connected to the outlet of the first compressor, is used to exchange heat between the remaining superheated steam and cold water.

[0054] A flash tank is connected to the cold side outlet of the heat exchanger. The flash tank is used to flash-evaporate the hot water generated after heat exchange by the heat exchanger to obtain secondary steam and saturated water.

[0055] The second compressor is connected to the gas outlet of the flash tank and is used to compress the secondary steam.

[0056] The humidification and saturation tank has its inlet connected to the outlet of the second compressor. The humidification and saturation tank is used to humidify and saturate the secondary steam after it has been compressed by the second compressor.

[0057] The processing device provided in this embodiment, through the ingenious design described above, can utilize the heat of the ammonia-containing waste heat steam after compression and heating. Part of the heat is used to enter the reboiler to heat the liquid in the deammoniation tower. The remaining heat can be further used as a heat source to exchange heat with cold water in the heat exchanger, fully recovering the heat of the waste steam. The resulting hot water is then subjected to flash evaporation, compression, and humidification saturation treatment to obtain high-grade steam. This achieves heat recovery of the ammonia-containing waste heat steam and also produces high-grade steam, which has high economic value.

[0058] In a preferred embodiment, the operating parameters of the first compressor include: inlet temperature 85~100℃, pressure 0.05~0.10MPa; outlet temperature and pressure 107~120℃, pressure 0.1~0.2MPa. The operating parameters of the reboiler include: hot side: inlet temperature 107~120℃, inlet pressure 0.10~0.20MPa, outlet temperature 102~105℃, outlet pressure 0.1~0.2MPa; cold side: inlet temperature 98~100℃, inlet pressure at atmospheric pressure, outlet temperature 102~105℃, outlet pressure at atmospheric pressure. The operating parameters of the flash tank include: temperature 90~98℃, pressure 0.05~0.1MPa, and residence time 15~30min.

[0059] In another embodiment of the present invention, the liquid outlet of the humidification saturation tank is connected to the flash tank for recycling the liquid generated after humidification saturation for flash evaporation treatment, thereby saving water resources.

[0060] Example 2

[0061] The low-grade ammonia-containing waste heat steam treatment device provided in this embodiment is based on Embodiment 1 and further includes:

[0062] A dilute ammonia water storage tank, the inlet of which is connected to the hot-side outlet of the reboiler and / or the hot-side outlet of the heat exchanger.

[0063] A dilute ammonia water pump, the inlet of which is connected to the outlet of the dilute ammonia water storage tank;

[0064] The ammonia stripping tower has its top inlet connected to the outlet of the dilute ammonia water pump, its bottom liquid outlet connected to the cold side inlet of the reboiler, and its bottom liquid inlet connected to the cold side outlet of the reboiler.

[0065] The top condenser has its hot-side inlet connected to the gas outlet of the ammonia removal tower;

[0066] An ammonia condenser, the hot-side inlet of which is connected to the hot-side outlet of the top condenser of the tower;

[0067] A concentrated ammonia water storage tank (not shown in the figure) is connected to the hot side outlet of the ammonia condenser.

[0068] This allows dilute ammonia water from the heat exchanger and / or reboiler to enter the top of the ammonia stripping tower for stripping and ammonia removal. The ammonia vapor at the top of the tower is condensed through two-stage condensers, continuously increasing in concentration, ultimately yielding concentrated ammonia water. Meanwhile, the bottom liquid of the ammonia stripping tower has already been heated in the reboiler. This not only recovers the heat from the ammonia-containing waste heat steam but also recovers ammonia resources, further improving the economic benefits of the invention.

[0069] Example 3

[0070] The process for treating low-grade ammonia-containing waste heat steam using the treatment device provided in Embodiment 2 of this invention is as follows: Figure 1 As shown, it includes the following steps:

[0071] S1. 2t of ammonia-containing waste heat steam (95℃, ammonia content 1wt%) is fed into the first compressor 1 for compression and heating. The operating parameters of the first compressor 1 are set as follows: inlet pressure 0.1MPa, outlet temperature 112℃, outlet pressure 0.16MPa, resulting in superheated steam (112℃, 0.16MPa). A portion of this superheated steam is fed into the hot side of the reboiler 2 to exchange heat with the ammonia removal tower bottom liquid (98℃, atmospheric pressure) on the cold side of the reboiler 2. The operating parameters of the reboiler are controlled as follows: hot side outlet temperature 102℃, hot side outlet pressure 0.11MPa, cold side outlet temperature 102℃, outlet pressure atmospheric pressure, so that this portion of superheated steam is condensed to obtain dilute ammonia water (102℃, ammonia content 1wt%). The heated ammonia removal tower bottom liquid is then returned to the bottom of the ammonia removal tower 11 for subsequent stripping and ammonia removal steps.

[0072] S2. The remaining superheated steam (112℃, 0.16MPa) generated in step S1 is fed into the hot side of heat exchanger 3 to exchange heat with the cold water (98℃) on the cold side of heat exchanger 3, resulting in dilute ammonia water (102℃, ammonia content 1wt%) and hot water (102℃, 0.2MPa). The hot water enters flash tank 4 for flash evaporation. The operating parameters of flash tank 4 are set as follows: pressure 0.095MPa, temperature 95℃, residence time 15min, generating secondary steam and saturated water. The secondary steam is compressed by the second compressor 5 and then enters the humidification and saturation tank 6 for humidification and saturation treatment to obtain 0.98t of high-grade steam (115℃, 0.17MPa). Part of the saturated water enters the heat exchanger 3 under the action of the circulating pump 8 to exchange heat with the newly generated superheated steam. The remaining part of the saturated water enters the humidification and saturation tank 6 through the humidification pump 7 and is used as a spray liquid to humidify and saturate the compressed secondary steam. The liquid generated in the humidification and saturation tank 6 is recycled to the flash tank 4 for further flash evaporation treatment.

[0073] S3. The dilute ammonia water obtained in steps S1 and S2 is stored in the dilute ammonia water storage tank 10. When a certain amount is reached, the dilute ammonia water is sent to the top of the deammoniation tower 11 by the dilute ammonia water pump 9 for deammoniation treatment. The bottom liquid of the deammoniation tower has been heated by superheated steam in step S1, which saves energy consumption in the deammoniation process. The ammonia vapor discharged from the top of the deammoniation tower 11 is condensed by the tower top condenser 12 and the ammonia condenser 13 in sequence, and finally 0.98t of concentrated ammonia water (ammonia content of 25wt%) is obtained.

[0074] Example 4

[0075] The process flow for treating low-grade ammonia-containing waste heat steam provided in this embodiment is the same as that in Embodiment 3. The difference lies in the properties of the ammonia-containing waste heat steam and the process parameters of each step, as detailed in Table 1.

[0076] Example 5

[0077] The process flow for treating low-grade ammonia-containing waste heat steam provided in this embodiment is the same as that in Embodiment 3. The difference lies in the properties of the ammonia-containing waste heat steam and the process parameters of each step, as detailed in Table 1.

[0078] Table 1. Raw materials and process parameters for Examples 3-5

[0079]

[0080] Comparative Example 1

[0081] The process flow for treating low-grade ammonia-containing waste heat steam provided in this comparative example is the same as that in Example 3. The only difference is that the operating parameters of the first compressor in step S1 are: outlet temperature 125°C.

[0082] The final yield was 0.85t of water vapor (115℃, 0.17MPa) and 0.82t of ammonia water (ammonia content 25wt%).

[0083] Therefore, compared with Comparative Example 1, the processing technology of Examples 3-5 can generate more high-grade steam and concentrated ammonia water. This shows that the low-grade ammonia-containing waste heat steam treatment process provided by the present invention can not only recover the heat of ammonia-containing waste heat steam, but also maximize the recovery of ammonia resources and co-produce high-grade steam, which has high economic value.

[0084] Obviously, the above embodiments are merely illustrative examples for clarity and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A process for the treatment of low grade ammonia containing waste heat steam, characterized in that, Includes the following steps: S1. The ammonia-containing waste heat steam is compressed and heated to obtain superheated steam. A portion of the superheated steam is then exchanged with the liquid in the bottom of the ammonia removal tower to obtain dilute ammonia water. The temperature of the ammonia-containing waste heat steam is 85~100℃, and the ammonia content is 1~2wt%. The temperature of the superheated steam is 107~120℃ and the pressure is 0.10~0.2MPa; S2. The remaining superheated steam is exchanged with cold water to obtain dilute ammonia water and hot water; the hot water is flash-evaporated to obtain secondary steam and saturated water; the secondary steam is compressed, humidified and saturated to obtain high-grade steam with a temperature of 110~120℃ and a pressure of 0.15~0.2MPa. A portion of the saturated water is reused for heat exchange with the remaining portion of the superheated steam, and the remaining saturated water is used to humidify the compressed secondary steam; the liquid generated after humidification and saturation is reused for the flash evaporation treatment.

2. The process for the treatment of low grade ammonia containing waste heat steam according to claim 1, characterized in that, In step S1, the temperatures of the liquid in the deammoniation tower before and after heat exchange are 98~100℃ and 102~105℃, respectively.

3. Process for the treatment of low-grade ammonia-containing waste heat steam according to claim 2, characterized in that, In step S2, the pressure of the hot water is 0.1~0.2MPa and the temperature is 98~102℃; and / or, The flash evaporation process is carried out at a pressure of 0.05~0.10 MPa, a temperature of 90~98℃, and a residence time of 15~30 min.

4. The process for the treatment of low grade ammonia containing waste heat steam according to claim 1, characterized in that, The processing technology further includes step S3, in which the dilute ammonia water obtained in step S1 and / or step S2 is fed into the top of the deammoniation tower for deammoniation treatment to obtain concentrated ammonia water with an ammonia content of 18~25wt%.

5. A device for treating low-grade ammonia-containing waste heat steam, characterized by include: The first compressor is used to compress and heat ammonia-containing waste heat steam to obtain superheated steam. A reboiler, the hot side inlet of which is connected to the outlet of the first compressor, is used to exchange heat between a portion of the superheated steam and the bottom liquid of the deammoniation tower. A heat exchanger, the hot side inlet of which is connected to the outlet of the first compressor, is used to exchange heat between the remaining portion of the superheated steam and cold water. A flash tank is connected to the cold side outlet of the heat exchanger. The flash tank is used to flash-evaporate the hot water generated after heat exchange by the heat exchanger to obtain secondary steam and saturated water. The second compressor is connected to the gas outlet of the flash tank and is used to compress the secondary steam. A humidification and saturation tank, the air inlet of which is connected to the outlet of the second compressor, is used to humidify and saturate the secondary steam after it has been compressed by the second compressor. A humidifying pump, the inlet of which is connected to the outlet of the flash tank, and the outlet of which is connected to the inlet of the humidifying saturation tank; A circulating pump, the inlet of which is connected to the outlet of the flash tank, and the outlet of which is connected to the cold side inlet of the heat exchanger; The liquid outlet of the humidification saturation tank is connected to the flash tank.

6. The device for treating low-grade ammonia-containing waste heat steam according to claim 5, characterized in that, The processing device further includes: A dilute ammonia water storage tank, the inlet of which is connected to the hot-side outlet of the reboiler and / or the hot-side outlet of the heat exchanger. A dilute ammonia water pump, the inlet of which is connected to the outlet of the dilute ammonia water storage tank; The deammonia removal tower has its top inlet connected to the outlet of the dilute ammonia water pump, its bottom liquid outlet connected to the cold side inlet of the reboiler, and its bottom liquid inlet connected to the cold side outlet of the reboiler.

7. The apparatus for treating low-grade ammonia-containing waste heat steam according to claim 6, characterized by The processing device further includes: The top condenser has its hot-side inlet connected to the gas outlet of the ammonia removal tower; An ammonia condenser, the hot-side inlet of which is connected to the hot-side outlet of the top condenser of the tower; A concentrated ammonia water storage tank is connected to the hot-side outlet of the ammonia condenser.

8. The apparatus for treating low-grade ammonia-containing waste heat steam according to any one of claims 5 to 7, characterized by The operating parameters of the first compressor include: inlet temperature 85~100℃, inlet pressure 0.05~0.10MPa, outlet temperature 107~120℃, outlet pressure 0.1~0.2MPa; and / or, The operating parameters of the reboiler include: Hot side: Inlet temperature 107~120℃, inlet pressure 0.10~0.20MPa, outlet temperature 102~105℃, outlet pressure 0.1~0.2MPa; Cold side: Inlet temperature 98~100℃, inlet pressure atmospheric pressure, outlet temperature 102~105℃, outlet pressure atmospheric pressure; and / or, The operating parameters of the flash tank include: temperature 90~98℃, pressure 0.05~0.1MPa, and residence time 15~30min.

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