Vapor compression ammonia distillation and absorption device and method

Abstract

The invention provides a vapor compression ammonia distillation and absorption device and method, and relates to the technical field of ammonia-containing wastewater treatment. Through the arrangement of the ammonia distillation tower, the steam compressor and the absorber, low-temperature and low-pressure steam generated in the ammonia absorption process of the absorber is converted into high-temperature steam and conveyed to the ammonia distillation tower to drive the ammonia distillation tower to distill ammonia, so that the steam in the ammonia distillation and absorption process can be recycled, and external steam is not consumed; and circulating cooling water is not consumed to cool the acidic ammonia absorption liquid, so that the ammonia distillation cost is reduced, and the secondary pollution is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonia-containing wastewater treatment, and in particular to a steam compression ammonia evaporation and absorption device and method. Background Art

[0002] Ammonia-containing wastewater is a common pollutant generated in industrial production processes. In the prior art, ammonia evaporation and absorption processes are often used to remove ammonia from ammonia-containing wastewater. The traditional ammonia evaporation and absorption technology is to introduce high-temperature steam into an ammonia evaporation tower, wherein the ammonia-containing wastewater is sprayed downward from the top of the tower, and the high-temperature steam enters upward from the bottom, so that the ammonia-containing wastewater and the high-temperature steam form a countercurrent, heat transfer occurs, and the ammonia-containing wastewater reaches the boiling point, ammonia evaporates and escapes, and is sucked into the absorption tower through the induced draft fan for internal absorption to obtain ammonia water with a high concentration. This process requires consumption of external steam. At the same time, the ammonia absorption process also consumes a large amount of circulating cooling water to cool the acidic ammonia absorption liquid, so the cost of ammonia evaporation is relatively high; The traditional stripping method uses air to strip ammonia-containing wastewater. The air is sent into the stripping tower by a blower to strip the ammonia wastewater in countercurrent. The ammonia-containing air flowing out of the top of the tower enters the absorption tower. The ammonia in the air is absorbed by the acidic liquid and then discharged. This process often causes ammonia in the discharged air and has been basically eliminated. Reports show that the use of a closed-loop stripping method, that is, the air is not discharged and is recycled for stripping ammonia, can reduce pollution. However, since this air stripping method has no heat support, the stripping capacity is not strong, and the air volume for stripping is large. Generally, the air-to-water ratio needs to be about 3500:1, which is costly. Therefore, we have made improvements to this and proposed a steam compression ammonia evaporation and ammonia absorption device and method. Summary of the invention

[0003] The purpose of the present invention is to address the problems of high cost and secondary pollution in the current treatment process of ammonia-containing wastewater.

[0004] In order to achieve the above-mentioned purpose of the invention, the present invention provides a steam compression ammonia evaporation and absorption device and method to improve the above-mentioned problems.

[0005] The specific application is as follows: A steam compression ammonia evaporation and absorption device comprises an ammonia evaporation tower, a steam compressor and an absorber. The steam compressor is connected between the ammonia evaporation tower and the absorber. The low-temperature and low-pressure steam generated during the ammonia absorption process of the absorber is compressed by the compressor, converted into high-temperature steam and transported to the ammonia evaporation tower to drive the ammonia evaporation tower to evaporate ammonia.

[0006] A steam compression ammonia evaporation and absorption method comprises: a steam compressor delivers high-temperature steam to the bottom of an ammonia evaporation tower, raw ammonia water is sprayed from the top of the ammonia evaporation tower, the raw ammonia water flows downward through the filler in the ammonia evaporation tower to form a liquid film, and performs countercurrent heat exchange with the high-temperature steam coming from the bottom of the ammonia evaporation tower to evaporate ammonia, so that ammonia in the raw ammonia water is continuously evaporated and flows to the top of the ammonia evaporation tower, ammonia gas and part of water vapor produced by ammonia evaporation are sucked into an absorber from the top of the ammonia evaporation tower, ammonia gas is absorbed by acidic ammonia absorbing liquid in the absorber to generate ammonium salt liquid, heat generated by ammonia absorption and water vapor entrained in ammonia evaporation are produced at the top of the absorber to produce low-temperature water vapor, the low-temperature water vapor is delivered to the steam compressor, converted into high-temperature water vapor after being pressurized by the steam compressor, and then delivered back to the bottom of the ammonia evaporation tower for ammonia evaporation.

[0007] Compared with the prior art, the present invention has the following beneficial effects: In the scheme of this application: Compared with the traditional stripping method, the advantages of this technology are as follows: In order to solve the problems of high cost and secondary pollution in the prior art of ammonia-containing wastewater treatment process, the present application sets up an ammonia evaporation tower, a steam compressor and an absorber. The low-temperature and low-pressure steam generated in the ammonia absorption process of the absorber is converted into high-temperature steam and transported to the ammonia evaporation tower to drive the ammonia evaporation tower to evaporate ammonia, so that the steam in the ammonia evaporation and ammonia absorption process can be recycled, no external steam is consumed, and no circulating cooling water is consumed to cool the acidic ammonia absorption liquid, thereby reducing the cost of ammonia evaporation and reducing secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of a steam compression ammonia evaporation and absorption device provided in this application; Figure 2 A schematic diagram of a steam compression ammonia evaporation and absorption device provided in this application; Figure 3 A schematic diagram of parameters during use of the steam compression ammonia evaporation and absorption device provided in this application; Indicated in the figure: 1. Ammonia evaporation tower; 2. Steam compressor; 3. Absorber; 4. Liquid storage tank; 5. Acidic ammonia absorption liquid circulation pump; 6. Ejector circulation pump; 7. Hydraulic ejector; 8. Material tank; 9. Material circulation pump; 10. induced draft fan. DETAILED DESCRIPTION

[0009] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0010] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0011] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0012] Example 1, please refer to Figure 1 , a steam compression ammonia evaporation and absorption device, comprising an ammonia evaporation tower 1, a steam compressor 2 and an absorber 3, the steam compressor 2 is connected between the ammonia evaporation tower 1 and the absorber 3, the low-temperature and low-pressure steam generated in the process of absorbing ammonia in the absorber 3 is compressed by the compressor 2, converted into high-temperature steam and transported to the ammonia evaporation tower 1, so as to drive the ammonia evaporation tower 1 to evaporate ammonia, thereby realizing efficient recycling of energy, significantly reducing energy consumption and production costs, and improving the operation stability and sustainability of the entire device, and reducing the waste of steam by converting the low-temperature and low-pressure steam generated by the absorber 3 into high-temperature steam for reuse in the ammonia evaporation tower 3 to evaporate ammonia, so that energy can be reused many times in the system, which not only reduces the input of external energy and reduces the energy procurement cost of the enterprise, but also reduces the environmental burden such as carbon emissions generated by energy production, and the stable steam circulation supply ensures the continuity and stability of the ammonia evaporation process, reduces the risk of production interruption due to unstable steam supply, improves the stability of production efficiency and product quality, and lays a solid foundation for the long-term stable production of the enterprise.

[0013] Further, such as Figure 1 As shown, the ammonia distillation tower 1 is connected to an ammonia water conveying structure, and the ammonia water conveying structure is used to convey ammonia water to the ammonia distillation tower 1; the ammonia water conveying structure includes a feed tank 8 connected to the ammonia distillation tower 1, and the feed tank 8 is connected to a feed circulation pump 9, and the feed circulation pump 9 is connected to the ammonia distillation tower 1; the stable conveying and efficient recycling of ammonia water are effectively guaranteed, the ammonia distillation efficiency and raw material utilization rate are greatly improved, and the waste and treatment cost of ammonia water are reduced. The feed circulation pump 9 can continuously and stably convey the ammonia water in the feed tank to the top of the ammonia distillation tower 3 for spraying, so that the ammonia water and steam are fully in contact and heat exchange, and the ammonia is evaporated. This uniform and stable spraying method ensures the high efficiency of the ammonia distillation process, reduces the residual ammonia in the ammonia distillation 3, and improves the recovery rate of ammonia. At the same time, the qualified water after deammoniation is returned to the feed tank 8 and mixed with the original ammonia water to participate in ammonia distillation again, which reduces the waste of qualified water and realizes the maximum utilization of resources.

[0014] Further, such as Figure 1As shown, the absorber 3 is connected to an acidic ammonia absorbing liquid circulation structure, and the acidic ammonia absorbing liquid circulation structure includes a liquid storage tank 4 connected to the absorber 3, and the liquid storage tank 4 is connected to an acidic ammonia absorbing liquid circulation pump 5, and the acidic ammonia absorbing liquid circulation pump 5 is connected to the absorber 3, which effectively ensures the efficient recycling of the acidic ammonia absorbing liquid, significantly enhances the ammonia absorption effect, effectively reduces the consumption and procurement cost of the acidic ammonia absorbing liquid, and at the same time improves the ammonia absorption efficiency and the environmental protection performance of the entire device. The acidic ammonia absorbing liquid circulation pump 5 continuously transports the acidic ammonia absorbing liquid in the liquid storage tank 4 to the absorber 3, so that the absorber 3 always maintains sufficient acidic ammonia absorbing liquid to absorb ammonia, thereby ensuring the continuity and efficiency of the ammonia absorption process. The sufficient supply of acidic ammonia absorbing liquid enables ammonia to be more fully absorbed, reduces the escape emission of ammonia, reduces the risk of pollution to the environment, improves the economic and environmental benefits of the enterprise, and achieves a win-win development of economy and environment.

[0015] Example 2, the steam compression ammonia evaporation and ammonia absorption device provided in Example 1 is further optimized, specifically, as follows Figure 1 As shown, a vacuum generating device is connected between the absorber 3 and the liquid storage tank 4, and the vacuum generating device is used to extract non-condensable gases such as air in the device to form a vacuum environment in the device.

[0016] Example 3, the steam compression ammonia evaporation and absorption device provided in Example 2 is further optimized. Specifically, the vacuum generating equipment is a water ring vacuum pump.

[0017] Example 4: The steam compression ammonia evaporation and absorption device provided in Example 2 is further optimized. Specifically, the vacuum generating equipment is a Luoci vacuum pump.

[0018] Example 5, the steam compression ammonia evaporation and absorption device provided in Example 2 is further optimized. Specifically, the vacuum generating equipment is a hydraulic jet vacuum device, and the hydraulic jet vacuum device includes an ejector circulation pump 6 connected to the liquid storage tank 4, the ejector circulation pump 6 is connected to a hydraulic ejector 7, and the hydraulic ejector 7 is connected to the absorption tower 3. The ejector circulation pump 6 and the hydraulic ejector 7 cooperate to extract non-condensable gases such as air in the device to form a vacuum environment in the device.

[0019] Example 6, the steam compression ammonia evaporation and ammonia absorption device provided in Example 1 is further optimized, specifically, as follows Figure 2 As shown, an induced draft fan 10 is connected between the ammonia evaporation tower 1 and the absorber 3. The induced draft fan 10 is arranged to facilitate the transportation of ammonia gas generated by ammonia evaporation in the ammonia evaporation tower 1 to the absorber 3, that is, the suction force generated by the induced draft fan 10 can enable the ammonia gas evaporated from the ammonia evaporation tower 1 to be transported to the absorber 3 more quickly, thereby shortening the transportation time of the ammonia gas and making the entire ammonia evaporation and absorption process more stable and efficient.

[0020] Embodiment 7, as Figure 3 As shown, a method for steam compression ammonia evaporation and ammonia absorption comprises: First, the steam compressor 2 is given initial steam for operation. The steam compressor 2 delivers high-temperature steam to the bottom of the ammonia evaporation tower 1. The raw ammonia water in the feed tank 8 is delivered to the top of the ammonia evaporation tower 1 by the material circulation pump 9 for spraying. The qualified water after deammoniation flows back to the feed tank 8. Part of the qualified water in the feed tank 8 meets the standards and is discharged externally, and part of it is mixed with the raw ammonia water and then delivered to the ammonia evaporation tower 1 through the material circulation pump 9 for ammonia evaporation. The recycling of water resources and ammonia resources is successfully realized, the discharge of wastewater and ammonia is significantly reduced, the treatment cost and resource waste are greatly reduced, and the economic and environmental benefits of the enterprise are improved. The qualified water after deammoniation is partially reused and mixed with the raw ammonia water to participate in ammonia evaporation again, which reduces the amount of fresh water, reduces the consumption of water resources, and alleviates the water pressure of the enterprise. The raw ammonia water flows downward through the filler to form a liquid film in the ammonia still 1, and performs countercurrent heat exchange with the high-temperature steam coming from the bottom of the ammonia still 1 to perform ammonia still. The ammonia in the raw ammonia water is continuously evaporated and flows to the top of the ammonia still 1. The ammonia gas and part of the water vapor produced by the ammonia still 1 are sucked into the absorber 3 from the top of the ammonia still 1. The ammonia gas is absorbed by the acidic ammonia absorbing liquid in the absorber 3 to generate an ammonium salt solution. The heat generated by the ammonia absorption and the water vapor entrained by the ammonia still 3 produce low-temperature water vapor at the top of the absorber 3. The low-temperature water vapor is transported to the steam compressor 2, converted into high-temperature water vapor after being pressurized by the steam compressor 2, and then sent back to the bottom of the ammonia still 1 for ammonia still. After absorbing ammonia in the absorber 3, the temperature of the low-temperature acidic ammonia absorbing liquid increases and flows back to the liquid storage tank 4.

[0021] The material tank 8 has two chambers, which are used to inject the original ammonia water and collect the qualified water after deammoniation in the ammonia distillation tower 1 respectively; The ammonia absorption adopts acidic ammonia absorption water, so that non-volatile ammonium salts, such as ammonium sulfate, can be generated during the ammonia absorption process. Only in this way, no ammonia gas will evaporate from the top of the ammonia absorption tower 3. Otherwise, the ammonia gas will be evaporated and returned to the ammonia evaporation tower 3 through the steam compressor 2. Therefore, this application is suitable for deammoniation of wastewater; Ammonia is absorbed by ammonium brine to generate ammonium salt liquid, which successfully realizes the resource utilization of ammonia, significantly improves the added value of products, effectively reduces environmental pollution, and brings new economic growth points and environmental benefits to the company. Ammonia is absorbed by ammonium brine to generate ammonium salt liquid, which can be used as a by-product, increasing the variety of products and economic benefits, broadening the company's profit channels, and at the same time converting ammonia into useful products, reducing the pollution of ammonia emissions to the environment, reducing the company's environmental governance costs, and realizing the effective utilization of resources and environmental protection.

[0022] Compared with the traditional stripping method, this application also has the following advantages: 1. The present application utilizes the heat generated by absorbing ammonia and uses it to evaporate water, thereby obtaining a high-concentration ammonium salt solution, which is beneficial for its utilization as a by-product, greatly improving resource utilization and economic benefits, significantly increasing product added value, effectively reducing waste emissions, achieving maximum resource utilization and maximum environmental benefits, and realizing a virtuous interaction between economic development and environmental protection; Second, the ammonia is evaporated by steam, and the ammonium brine absorbs ammonia and is converted into ammonium salt, so the efficiency is very high. Generally, the gas-water ratio only needs to be 70:1 to achieve a good effect. The combination of steam ammonia evaporation and ammonium brine absorption has a high efficiency. Compared with the traditional method, a good ammonia evaporation and absorption effect can be achieved at a lower gas-water ratio, which reduces the use of steam and water, reduces energy consumption and raw material costs, and can produce more qualified products at a lower cost; 3. The present application utilizes steam to remove ammonia from wastewater and enrich it into a by-product in ammonium salt water. The deammonified water vapor is basically not absorbed by the ammonium salt water, so a high-concentration ammonium salt solution can be obtained, which is beneficial to the utilization of acidic ammonia absorbing liquid, thereby improving the recovery rate of ammonia and the market value of the product.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to replace some of the technical features therein with equivalents. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A steam compression ammonia evaporation and absorption device, characterized in that: The invention comprises an ammonia evaporation tower (1), a steam compressor (2) and an absorber (3), wherein the steam compressor (2) is connected between the ammonia evaporation tower (1) and the absorber (3), and low-temperature and low-pressure steam generated in the process of absorbing ammonia in the absorber (3) is compressed by the compressor (2), converted into high-temperature steam and transported to the ammonia evaporation tower (1), so as to drive the ammonia evaporation tower (1) to evaporate ammonia.

2. The steam compression ammonia evaporation and absorption device according to claim 1, characterized in that: The ammonia still (1) is connected to an ammonia water delivery structure, and the ammonia water delivery structure is used to deliver ammonia water to the ammonia still (1); The ammonia water conveying structure comprises a material tank (8) connected to the ammonia distillation tower (1), the material tank (8) is connected to a material circulation pump (9), and the material circulation pump (9) is connected to the ammonia distillation tower (1).

3. A steam compression ammonia evaporation and absorption device according to claim 1 or 2, characterized in that: The absorber (3) is connected to an acidic ammonia absorption liquid circulation structure.

4. The steam compression ammonia evaporation and absorption device according to claim 3, characterized in that: The acidic ammonia absorption liquid circulation structure comprises a liquid storage tank (4) connected to an absorber (3), the liquid storage tank (4) is connected to an acidic ammonia absorption liquid circulation pump (5), and the acidic ammonia absorption liquid circulation pump (5) is connected to the absorber (3).

5. The steam compression ammonia evaporation and absorption device according to claim 4, characterized in that: A vacuum generating device is connected between the absorber (3) and the liquid storage tank (4).

6. The steam compression ammonia evaporation and absorption device according to claim 1, characterized in that: An induced draft fan (10) is connected between the ammonia distillation tower (1) and the absorber (3).

7. A method for steam compression ammonia evaporation and absorption, characterized in that: include: The steam compressor (2) delivers high-temperature steam to the bottom of the ammonia evaporation tower (1), and the raw ammonia water is sprayed from the top of the ammonia evaporation tower (1). The raw ammonia water flows downward through the filler in the ammonia evaporation tower (1) in the form of a liquid film, and performs countercurrent heat exchange with the high-temperature steam coming from the bottom of the ammonia evaporation tower (1) to evaporate ammonia, so that ammonia in the raw ammonia water is continuously evaporated and flows to the top of the ammonia evaporation tower (1). Ammonia gas and part of water vapor produced by ammonia evaporation are sucked into the absorber (3) from the top of the ammonia evaporation tower (1). The ammonia gas is absorbed by the acidic ammonia absorbing liquid in the absorber (3) to generate ammonium salt liquid. The heat generated by ammonia absorption and the water vapor entrained by ammonia evaporation produce low-temperature water vapor at the top of the absorber (3). The low-temperature water vapor is delivered to the steam compressor (2), converted into high-temperature water vapor after being pressurized by the steam compressor (2), and then delivered back to the bottom of the ammonia evaporation tower (1) for ammonia evaporation.

8. The method for steam compression ammonia evaporation and absorption according to claim 7, characterized in that: The material tank (8) has two chambers, which are respectively used to inject raw ammonia water and collect qualified water after deammoniation in the ammonia evaporation tower (1). Part of the qualified water after deammoniation meets the standards and is discharged, while part is mixed with the raw ammonia water and then sent to the ammonia evaporation tower (1) through the material circulation pump (9) for ammonia evaporation.

9. A method for steam compression ammonia evaporation and absorption according to claim 7 or 8, characterized in that: The liquid storage tank (4) is used to store the acidic ammonia absorbing liquid. The acidic ammonia absorbing liquid is transported to the absorber (3) by the acidic ammonia absorbing liquid circulation pump (5). The acidic ammonia absorbing liquid in the absorber (3) absorbs ammonia and then flows back to the liquid storage tank (4).

10. The method for steam compression ammonia evaporation and absorption according to claim 9, characterized in that: The ejector circulation pump (6) cooperates with the hydraulic ejector (7) to extract non-condensable gases such as air to form a vacuum environment.

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