Waste heat recovery deamination system

Abstract

The utility model discloses a waste heat recovery deamination system which comprises a deamination tower, a falling film reboiler, a tower bottom liquid delivery pump, a primary condenser, a flash tank, a steam compressor, a reflux tank, a secondary condenser, an ammonia gas absorption tank, an ammonia concentration tower and an ammonia water cooler. Ammonia-containing steam is discharged from the tower top, enters a shell pass of the first-stage condenser and exchanges heat with circulating water of a tube pass of the first-stage condenser for cooling; the circulating water of the first-stage condenser is subjected to flash evaporation in the flash evaporation tank, and secondary steam is generated and enters the steam compressor; the material in the falling film reboiler exchanges heat to generate secondary steam, and the secondary steam enters the bottom of the deamination tower and is used as deamination steam; and the first-stage condenser condenses dilute ammonia water to flow into the reflux tank. According to the utility model, the waste heat of the ammonia-containing steam at the tower top is recycled through the steam compressor, so that the use amount of fresh steam is greatly reduced, the treatment cost is reduced, and the system has environmental protection benefits and economic benefits.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat recovery, in particular to a waste heat recovery and deammoniation system. Background Art

[0002] In terms of development at home and abroad, with the improvement of environmental awareness and the strictness of environmental protection regulations, more and more companies have begun to pay attention to the treatment and recycling of waste liquid. Abroad, some developed countries have formed a complete set of waste liquid treatment and recycling systems, which can not only effectively treat waste liquid, but also recover valuable resources from it. In China, although waste liquid treatment and recycling technology is still in the development stage, with the support of policies and the advancement of technology, waste liquid treatment and recycling technology is also constantly improving.

[0003] In the treatment process of high ammonia nitrogen wastewater, deamination is an important process technology. For high ammonia nitrogen alkaline wastewater, steam stripping deamination is currently a widely used process technology. It consumes steam to separate the ammonia nitrogen in the wastewater by steam stripping, obtains ammonia water for reuse, and makes resource utilization of pollutants.

[0004] In the traditional stripping deammonification technology, steam is directly injected into the stripping tower reboiler to heat the wastewater to a boiling state. The ammonia-containing steam is discharged from the top of the tower. The first-level condenser at the top of the tower condenses the ammonia-containing steam through cooling circulating water to obtain a dilute ammonia solution, which is then increased through an ammonia concentration process. This requires a large amount of cooling circulating water to condense the ammonia-containing steam at the top of the tower, and the latent heat of the steam at the top of the tower cannot be utilized, resulting in a large loss of energy. Utility Model Content

[0005] In response to the problems existing in the prior art, the present application provides a waste heat recovery deammonification system, which recovers the waste heat of the ammonia-containing steam at the top of the tower through a steam compressor. The secondary steam generated by the waste heat is pressurized and heated by the steam compressor, and then re-transported to the reboiler for use as heating steam for the deammonification tower. This will greatly reduce the use of fresh steam and reduce processing costs, and has great environmental and economic benefits.

[0006] The technical scheme for realizing the purpose of the utility model is: a waste heat recovery deammonification system, including a deammonification tower, a falling film reboiler, a tower bottom liquid delivery pump, a primary condenser, a flash tank, a steam compressor, a reflux tank, a secondary condenser, an ammonia absorption tank, an ammonia concentration tower, and an ammonia water cooler.

[0007] After the feed is preheated, it is pumped into the deamination tower and descends from the top to the bottom of the tower. During the descent, it comes into contact with the secondary steam generated by the falling film reboiler at the bottom of the tower, and the ammonia nitrogen in the feed is removed step by step to a predetermined value, and then discharged through the bottom liquid delivery pump.

[0008] Ammonia-containing steam is discharged from the top of the tower and enters the shell side of the primary condenser, where it exchanges heat with the circulating water in the tube side of the primary condenser to cool down. After the circulating water in the primary condenser is heated up by heat exchange, it flows back to the flash tank, where it flashes to generate secondary steam that enters the steam compressor. After being pressurized and heated, it is transported to the shell side of the falling film reboiler for use as heating steam. The material in the falling film reboiler exchanges heat to generate secondary steam, which enters the bottom of the deamination tower and is used as deamination steam.

[0009] The primary condenser condenses the dilute ammonia water and flows it to the reflux tank, which is then transported to the top of the deamination tower by a reflux pump. The ammonia concentration of the ammonia vapor at the top of the deamination tower is;

[0010] The non-condensable gas from the first-stage condenser enters the second-stage condenser, which is cooled by cooling circulating water. After the ammonia-containing steam is further condensed, the high-concentration ammonia nitrogen condensate enters the ammonia absorption tank. The absorption liquid from the ammonia absorption tank is transported to the ammonia concentration tower. The exhaust gas from the ammonia absorption tank is connected to the ammonia concentration tower. The ammonia concentration tower is equipped with an ammonia water cooler, which is cooled by chilled water. After the ammonia concentration reaches the predetermined concentration, the finished ammonia water is discharged.

[0011] Preferably, the circulating water in the flash tank is pumped by a flash circulation pump.

[0012] Preferably, the ammonia absorption tank is equipped with an ammonia absorption pump and an ejector, and the ejector absorbs the uncooled non-condensable gas of the secondary condenser and maintains the deammonification tower in a slightly negative pressure state.

[0013] Preferably, the falling film reboiler is a natural circulation type reboiler.

[0014] By adopting the above technical solution, the utility model has the following beneficial effects: (1) The present invention recovers the heat in the primary condenser in the form of secondary steam, and then recompresses it through a steam compressor to increase its potential energy. The secondary steam with increased potential energy is then used in a reboiler as heating steam, thus realizing the secondary recovery and utilization of heat energy. This not only reduces the steam consumption of the system, but also effectively reduces the processing cost;

[0015] (2) The falling film reboiler adopts a vertical tube falling film method, which has the characteristics of high heat transfer efficiency and low equipment cost;

[0016] (3) The deamination tower adopts a combination of plate-type deamination and structured packing for ammonia concentration, making full use of the advantages of each tower type. While ensuring the anti-blocking performance of the stripping tower to the maximum extent, the equipment cost is low;

[0017] (4) The condensation heat of ammonia-containing steam at the top of the tower is recovered by waste heat recovery technology and reused as heating steam, greatly reducing the heating steam cost;

[0018] (5) Ammonia water concentration adopts the combination of "ejector + ammonia concentration tower", combining the coarse and fine absorption of ammonia gas to maximize the ammonia absorption efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the utility model easier to understand, the utility model is further described in detail according to specific embodiments and in conjunction with the accompanying drawings.

[0020] Figure 1 It is a system schematic diagram of the utility model. DETAILED DESCRIPTION

[0021] Embodiment 1

[0022] See Figure 1 The waste heat recovery deammonification system of this embodiment includes a deammonification tower 3, a falling film reboiler 4, a tower bottom liquid delivery pump 5, a primary condenser 6, a flash tank 7, a steam compressor 8, a reflux tank 9, a secondary condenser 11, an ammonia absorption tank 13, an ammonia concentration tower 14, and an ammonia water cooler 15.

[0023] The feed 1 is preheated 2 and then pumped into the deamination tower 3, where it descends from the top of the tower to the bottom. During the descent, it comes into contact with the secondary steam generated by the falling film reboiler 4 at the bottom of the tower, and the ammonia nitrogen in the feed is removed step by step to a predetermined value, and then discharged through the bottom liquid delivery pump 5.

[0024] Ammonia-containing steam is discharged from the top of the tower and enters the shell side of the primary condenser 6, where it exchanges heat with the circulating water in the tube side of the primary condenser to cool down; the circulating water in the primary condenser exchanges heat and heats up before flowing back to the flash tank 7, where it flashes to generate secondary steam that enters the steam compressor 8, where it is pressurized and heated before being transported to the shell side of the falling film reboiler for use as heating steam; the material in the falling film reboiler exchanges heat to generate secondary steam that enters the bottom of the deamination tower and is used as deamination steam;

[0025] The primary condenser condenses the dilute ammonia water and flows to the reflux tank 9, which is transported to the top of the deamination tower through the reflux pump 10. The ammonia concentration of the ammonia vapor at the top of the deamination tower is;

[0026] The non-condensable gas from the primary condenser enters the secondary condenser 11, which is cooled by cooling circulating water 12. After the ammonia-containing vapor is further condensed, the high-concentration ammonia nitrogen condensed water enters the ammonia absorption tank 13, and the absorption liquid from the ammonia absorption tank is transported to the ammonia concentration tower 14. The exhaust gas from the ammonia absorption tank is connected to the ammonia concentration tower, which is controlled by a concentration circulating pump 21. The ammonia concentration tower is equipped with an ammonia water cooler 15, which is cooled by chilled water 16. After the ammonia water concentration reaches a predetermined concentration, the finished ammonia water is discharged 17.

[0027] The circulating water in the flash tank is pumped by a flash circulation pump 18 .

[0028] The ammonia absorption tank is equipped with an ammonia absorption pump 19 and an ejector 20. The ejector absorbs the uncooled non-condensable gas of the secondary condenser and maintains a slightly negative pressure state of the deammonification tower.

[0029] The falling film reboiler adopts a natural circulation type reboiler.

[0030] In the traditional deamination tower process, the first-stage condenser at the top of the tower uses cooling water to dissipate heat, which causes a large amount of heat energy to be lost with the cooling water, resulting in energy waste. This system recovers the heat in the first-stage condenser in the form of secondary steam, and then recompresses it through a steam compressor to increase its potential energy. These secondary steams with increased potential energy are then used in the reboiler as heating steam, realizing the secondary recovery of heat energy. This not only reduces the steam consumption of the system, but also effectively reduces the processing cost.

[0031] When the present application is implemented, an ejector is used to reduce the operating pressure of the stripping tower, and deamination is performed at low temperature, thereby further reducing energy consumption. The falling film reboiler can be a natural circulation reboiler; the deamination tower can be a plate tower, which can be replaced by a packed tower according to different water qualities.

[0032] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A waste heat recovery and deammoniation system, characterized in that: It includes a deammonification tower (3), a falling film reboiler (4), a tower bottom liquid delivery pump (5), a primary condenser (6), a flash tank (7), a steam compressor (8), a reflux tank (9), a secondary condenser (11), an ammonia absorption tank (13), an ammonia concentration tower (14), and an ammonia water cooler (15). The feed (1) is preheated (2) and then pumped into the deamination tower (3), where it descends from the top of the tower to the bottom of the tower. During the descent, it comes into contact with the secondary steam generated by the falling film reboiler (4) at the bottom of the tower, and the ammonia nitrogen in the feed is removed step by step to a predetermined value, and then discharged through the bottom liquid delivery pump (5). The ammonia-containing steam is discharged from the top of the tower and enters the shell side of the primary condenser (6), where it is cooled by heat exchange with the circulating water in the tube side of the primary condenser; the circulating water in the primary condenser is heated by heat exchange and then refluxed to the flash tank (7), where it is flashed to generate secondary steam and enters the steam compressor (8), where it is pressurized and heated, and then transported to the shell side of the falling film reboiler for use as heating steam; the material in the falling film reboiler is heated by heat exchange to generate secondary steam, which enters the bottom of the deamination tower and is used as deamination steam; The primary condenser condenses the dilute ammonia water and flows it to the reflux tank (9), which is then transported to the top of the deamination tower through the reflux pump (10). The ammonia concentration of the ammonia-containing steam at the top of the deamination tower is The non-condensable gas from the primary condenser enters the secondary condenser (11), which is cooled by cooling circulating water (12). After the ammonia-containing steam is further condensed, the high-concentration ammonia nitrogen condensate enters the ammonia absorption tank (13). The absorption liquid from the ammonia absorption tank is transported to the ammonia concentration tower (14). The exhaust gas from the ammonia absorption tank is connected to the ammonia concentration tower. The ammonia concentration tower is equipped with an ammonia water cooler (15). The ammonia water cooler is cooled by chilled water (16). After the ammonia water concentration reaches a predetermined concentration, the finished ammonia water is discharged (17).

2. The waste heat recovery and deammonification system according to claim 1 is characterized in that: The circulating water in the flash tank is pumped by a flash circulating pump (18).

3. The waste heat recovery and deammonification system according to claim 1 is characterized in that: The ammonia absorption tank is equipped with an ammonia absorption pump (19) and an ejector (20). The ejector absorbs the uncooled non-condensable gas of the secondary condenser and maintains a slightly negative pressure state of the deammonification tower.

4. The waste heat recovery and deammoniation system according to claim 1, characterized in that: The falling film reboiler adopts a natural circulation type reboiler.

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