A method and system for energy-saving and efficient production of concentrated ammonia water from waste ammonia water from coking plants.

Abstract

This invention provides an energy-saving and efficient method and system for producing concentrated ammonia from coking waste ammonia water. The system includes an ammonia stripping tower (1), an ammonia washing tower (2), a desorption tower (3), a steam compressor (4), a wastewater evaporator (5), a fractional evaporator (6), a condenser evaporator (7), an ammonia stripping wastewater pump (8), a phosphate fertilizer circulation pump (9), a phosphate fertilizer feed pump (10), a wastewater circulation pump (11), a phosphate fertilizer circulation liquid cooler (12), a phosphate fertilizer rich liquid heat exchanger (13), an ammonia stripping wastewater heat exchanger (14), a concentrated ammonia water cooler (15), and a heater (16). This invention also discloses an energy-saving and efficient method for producing concentrated ammonia from coking waste ammonia water. The system for producing concentrated ammonia from coking waste ammonia water using this invention is simple, energy-saving, and efficient. The concentrated ammonia water product prepared using this system meets relevant standard requirements.

Description

Technical Field

[0001] This invention relates to coal chemical technology, and more particularly to a method and system for energy-saving and efficient production of concentrated ammonia water from waste ammonia water from coking. Background Technology

[0002] Coke ovens generate a large amount of production wastewater during the coking process. The main sources of this wastewater are the moisture carried by the coal used for charging and the chemically bound water from coking. This wastewater is called residual ammonia water. The amount of residual ammonia water generated is approximately 12-13% of the coking coal. Residual ammonia water contains a large number of various pollutants, including organic and inorganic pollutants. The main organic pollutants are aromatic hydrocarbons such as phenols; the inorganic pollutants include NH3, H2S, HCN, and ammonium salts. Specifically, it contains NH3 ~4 g / L, H2S ~0.5 g / L, and HCN ~0.3 g / L. Domestic coking plants generally use steam desorption processes to treat residual ammonia water. The ammonia stripping wastewater discharged from the ammonia stripping tower contains 150-200 mmg / L of ammonia nitrogen. The ammonia vapor discharged from the top of the ammonia stripping tower contains 15-20% NH3, and also contains approximately 2-3% H2S and approximately 1% HCN. The ammonia vapor containing acidic gases discharged from the separator is sent to the primary gas cooling system.

[0003] The ammonia stripping unit uses steam as a heat source to desorb and treat residual ammonia water. The wastewater biological treatment unit requires the ammonia nitrogen content in the wastewater discharged from the ammonia stripping unit to be ≤150–200 mmg / L. To ensure the desorption efficiency of the ammonia stripping tower, 150–180 kg of steam is required to treat each ton of residual ammonia water. The ammonia vapor discharged from the top of the ammonia stripping tower contains only 3–4% NH3. The ammonia vapor is condensed at the top of the tower to a concentration of 20% NH3 before being discharged. A large amount of water vapor in the ammonia vapor is condensed in the condenser, and a large amount of cooling water is also consumed during the ammonia vaporization process. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high steam consumption and high operating costs in current methods for treating waste ammonia water from coking plants, as well as the presence of oil and acidic gases in the ammonia water produced by ammonia steam condensation, making the ammonia water product unsellable. This invention proposes an energy-saving and efficient system for producing concentrated ammonia water from waste ammonia water from coking plants. This system is simple, energy-saving, and efficient, and the concentrated ammonia water product prepared using this system meets relevant standards.

[0005] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a system for energy-saving and efficient production of concentrated ammonia water from coking waste ammonia water, comprising an ammonia stripping tower, an ammonia washing tower, a desorption tower, a steam compressor, a wastewater evaporator, a fractionating evaporator, a condensing evaporator, an ammonia stripping wastewater pump, a phosphate ammonium circulating pump, a phosphate ammonium feed pump, a wastewater circulating pump, a phosphate ammonium circulating liquid cooler, a phosphate ammonium rich liquid heat exchanger, an ammonia stripping wastewater heat exchanger, a concentrated ammonia water cooler, and a heater;

[0007] The top of the ammonia stripping tower is connected to the ammonia washing tower, and the ammonia washing tower is connected to the heating medium inlet of the ammonium phosphate circulating liquid cooler via an ammonium phosphate circulating pump. The bottom of the ammonia washing tower is connected to the cooling medium inlet of the ammonium phosphate rich liquid heat exchanger via an ammonium phosphate feed pump, and the cooling medium outlet of the ammonium phosphate rich liquid heat exchanger is connected to the desorption tower. The top of the ammonia washing tower is connected to the heating medium inlet of the wastewater evaporator via a steam compressor, and the steam outlet of the wastewater evaporator is connected to the ammonia stripping tower. The bottom outlet of the cooling medium of the wastewater evaporator is connected to the inlet of the wastewater circulating pump, and the outlet of the wastewater circulating pump is connected to the spray pipe of the wastewater evaporator. The ammonia stripping wastewater outlet at the bottom of the ammonia stripping tower is connected to the wastewater evaporator, the fractionating evaporator, the condensing evaporator, and the ammonia stripping wastewater heat exchanger via an ammonia stripping wastewater pump. The residual ammonia outlet of the tar-ammonia water separation equipment is sequentially connected to the ammonia stripping wastewater heat exchanger, the ammonium phosphate circulating liquid cooler, and the ammonia stripping tower. The lean liquid outlet at the bottom of the desorption tower is connected to the heating medium inlet of the rich ammonium phosphate liquid heat exchanger. The heating medium outlet of the rich ammonium phosphate liquid heat exchanger is connected to the heating medium inlet of the ammonium phosphate circulating liquid cooler. The heating medium outlet of the ammonium phosphate circulating liquid cooler is connected to the inlet pipe of the ammonia washing tower. The top of the desorption tower is connected to the fractional evaporator. The fractional evaporator is connected to the condenser evaporator. The condenser evaporator is connected to the concentrated ammonia water cooler. The tops of the fractional evaporator and the condenser evaporator are connected to the ammonia stripping tower. The bottom of the desorption tower is connected to the heater cooling medium inlet. The heater cooling medium outlet is connected to the desorption tower.

[0008] Furthermore, the condensate outlet of the fractional evaporator is connected to the upper part of the desorption tower.

[0009] Another objective of this invention is to disclose an energy-saving and efficient method for producing concentrated ammonia water from waste ammonia water from coking plants, comprising the following steps:

[0010] Step 1: The residual ammonia water fed into the tar ammonia water separation equipment is heated and heated by the ammonia stripping wastewater heat exchanger and the ammonium phosphate circulating liquid cooler before entering the ammonia stripping tower.

[0011] Step 2: The ammonia vapor discharged from the top of the ammonia stripping tower is sent to the ammonia washing tower; the ammonia stripping wastewater from the bottom of the ammonia stripping tower is sent to the wastewater evaporator, the condenser evaporator, the condenser evaporator, and the ammonia stripping wastewater heat exchanger respectively by the ammonia stripping wastewater pump; the ammonia stripping wastewater sent to the ammonia stripping wastewater heat exchanger is sent to the biochemical device after being cooled by heat exchange.

[0012] The ammonia stripping wastewater sent to the wastewater evaporator, the fractional evaporator and the condenser evaporator exchanges heat and vaporizes to generate steam which enters the bottom of the ammonia stripping tower as a desorption heat source for the ammonia stripping tower.

[0013] Step 3: The ammonia washing tower uses ammonium phosphate solution as the absorbent. The ammonia vapor entering the ammonia washing tower comes into countercurrent contact with the sprayed ammonium phosphate absorbent inside the tower. The ammonium phosphate solution absorbs NH3 from the ammonia vapor to generate (NH4)2HPO4. The secondary vapor after removing NH3 is discharged from the top of the ammonia washing tower.

[0014] The ammonium phosphate solution at the bottom of the ammonia washing tower is sent to the ammonium phosphate circulating liquid cooler for cooling via an ammonium phosphate circulating pump, and the ammonium phosphate solution discharged from the ammonium phosphate circulating liquid cooler is sent to the ammonia washing tower.

[0015] The ammonium phosphate rich solution that needs to be desorbed at the bottom of the ammonia washing tower is sent to the ammonium phosphate rich solution heat exchanger for heat exchange and temperature increase via an ammonium phosphate feed pump.

[0016] Step 4: The secondary steam (ammonia removal steam) discharged from the top of the ammonia washing tower enters the steam compressor. The steam compressor is driven by a motor to pressurize the secondary steam, and the pressurized secondary steam enters the wastewater evaporator.

[0017] Step 5: Pressurized secondary steam enters the tube side of the wastewater evaporator. The wastewater in the lower shell side of the wastewater evaporator is pressurized by a wastewater circulation pump and sent to the spray pipes in the upper tube side of the evaporator. The wastewater is sprayed onto the outer wall of the heat exchange tubes through the spray nozzles. The pressurized secondary steam inside the heat exchange tubes exchanges heat with the wastewater on the outside of the tubes. The pressurized secondary steam inside the tubes condenses into condensate, and the wastewater on the outside of the tubes vaporizes to generate steam. The steam discharged from the wastewater evaporator enters the ammonia stripping tower.

[0018] Pressurized secondary steam condenses in the tube side, and some of the non-condensable gas in the tube side is discharged to the gas system or the incinerator of the acid production unit.

[0019] Step 6: The ammonium phosphate feed pump sends the ammonium phosphate rich solution from the ammonia washing tower to the ammonium phosphate rich solution heat exchanger to exchange heat with the ammonium phosphate lean solution. The heated ammonium phosphate rich solution enters the upper part of the stripping tower.

[0020] The ammonia vapor discharged from the top of the desorption tower enters the fractional evaporator;

[0021] The lean ammonium phosphate solution at the bottom of the desorption tower is discharged to the ammonium phosphate rich solution heat exchanger. After the lean ammonium phosphate solution is cooled down by exchanging heat with the ammonium phosphate rich solution, it is discharged to the outlet of the ammonium phosphate circulating liquid pump and mixed with the ammonium phosphate circulating liquid before entering the ammonium phosphate circulating liquid cooler.

[0022] Step 7: The ammonia vapor entering the fractional evaporator is cooled by the ammonia stripping wastewater, and the condensate generated by the condensation of the ammonia vapor is returned to the desorption tower; the shell-side ammonia vapor in the fractional evaporator releases heat during the condensation process, which causes the tube-side ammonia stripping wastewater to heat up and vaporize, and the steam generated by the vaporization of the ammonia stripping wastewater enters the ammonia stripping tower.

[0023] The ammonia vapor discharged from the split evaporator enters the condenser evaporator;

[0024] Step 8: The ammonia vapor entering the condenser condenses into ammonia water. The heat released during the ammonia vapor condensation process vaporizes the ammonia stripping wastewater. The steam generated from the vaporization of the ammonia stripping wastewater enters the bottom of the ammonia stripping tower.

[0025] Step 9: The ammonia water discharged from the condenser evaporator is cooled to room temperature by the concentrated ammonia water cooler and then sent out.

[0026] Furthermore, the ammonia vapor at the inlet of the ammonia washing tower contains 3-4% NH3, and the secondary steam at the outlet of the ammonia washing tower contains 500-800 mmg / m³ of NH3. 3 Unless otherwise specified, all percentages in this invention refer to mass percentages.

[0027] Furthermore, the desorption tower operates at a pressure of 0.65–1.0 MPa (G), the tube-side pressure of the condenser evaporator is higher than 300–350 kPa (G), and the tube-side operating pressure of the condenser evaporator is higher than 250–300 kPa (G).

[0028] Furthermore, the concentration of ammonium phosphate in the ammonium phosphate lean solution discharged from the desorption tower is 40-45%, and the molar ratio of NH3:H3PO4 in the ammonium phosphate lean solution of the stripping tower is 1.18-1.23.

[0029] Furthermore, the secondary steam is pressurized by a steam compressor, and the secondary steam pressure at the outlet of the steam compressor needs to be 40-60 kPa higher than the operating pressure at the bottom of the ammonia stripping tower.

[0030] Furthermore, the shell-side operating pressure of the wastewater evaporator is 10-15 kPa higher than the bottom pressure of the ammonia stripping tower.

[0031] Furthermore, the outlet temperature of the ammonium phosphate circulating liquid in the ammonium phosphate circulating liquid cooler is 1-2°C lower than the steam temperature of the ammonia washing tower. The remaining ammonia water is used to heat up and remove the ammonium phosphate solution to absorb the heat of reaction generated by NH3.

[0032] Furthermore, the ammonia vapor discharged from the fractional evaporator enters the condenser evaporator, and the NH3 concentration of the ammonia vapor is controlled at 15-20%.

[0033] Furthermore, the shell-side condensate return pipe of the fractional evaporator adopts a stepped drainage method, and the heat exchange area is adjusted by controlling the condensate level in the shell side of the fractional evaporator; the steam pipe pressure regulating valve at the outlet of the tube side of the fractional evaporator controls the wastewater vaporization pressure and adjusts the heat transfer temperature difference between the shell side and the tube side; the above two adjustment methods work together to control the NH3 concentration of the discharged ammonia vapor to be between 15% and 20%.

[0034] Furthermore, a heater is provided at the bottom of the desorption tower, and medium-pressure steam is used to indirectly heat the ammonium phosphate solution at the bottom of the desorption tower. Direct steam is added as needed to maintain the water balance of the system.

[0035] The present invention provides an energy-saving and efficient method and system for producing concentrated ammonia water from waste ammonia water from coking plants, which has the following advantages compared with the prior art:

[0036] 1) This invention can recover NH3 from residual ammonia water, and produce high-quality concentrated ammonia water in an energy-saving and efficient manner. The acidic gas impurities such as H2S in the ammonia water are <0.02%; the quality of the ammonia water meets the requirements for flue gas denitrification.

[0037] 2) This invention utilizes the synergistic coupling of the operating conditions of the ammonium phosphate desorption system and the operating conditions of the ammonia stripping tower to achieve cascade utilization of system heat and save 60-65% of steam consumption.

[0038] 3) This invention uses a combination of acid washing and MVR (methane vapor compressor) technology to solve the problem of corrosion in wastewater evaporators, improve the energy efficiency ratio of heat pump units, and achieve a COP energy efficiency coefficient of 15-18%. Attached Figure Description

[0039] Figure 1 A schematic diagram of a system for energy-saving and efficient production of concentrated ammonia water from waste ammonia water from coking. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0041] In the description of this application, it should be noted that, unless otherwise expressly 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, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically limited. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0042] The following disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure of this application, the components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit this application.

[0043] Example 1

[0044] This embodiment discloses an energy-saving and efficient system for producing concentrated ammonia water from waste ammonia water from coking plants, the structure of which is as follows: Figure 1 As shown, it includes an ammonia stripping tower 1, an ammonia washing tower 2, a desorption tower 3, a steam compressor 4, an evaporator 5, a fractional evaporator 6, a condensing evaporator 7, an ammonia stripping wastewater pump 8, a phosphate ammonium circulating pump 9, a phosphate ammonium feed pump 10, a wastewater circulating pump 11, a phosphate ammonium circulating liquid cooler 12, a phosphate ammonium rich liquid heat exchanger 13, a wastewater heat exchanger 14, a concentrated ammonia water cooler 15, and a heater 16.

[0045] The top of the ammonia stripping tower 1 is connected to the bottom of the ammonia washing tower 2. The bottom of the ammonia washing tower 2 is connected to the heating medium inlet of the ammonium phosphate circulating liquid cooler 12 via the ammonium phosphate circulating pump 9. The bottom of the ammonia washing tower 2 is connected to the cooling medium inlet of the ammonium phosphate rich liquid heat exchanger 13 via the ammonium phosphate feed pump 10. The cooling medium outlet of the ammonium phosphate rich liquid heat exchanger 13 is connected to the top of the desorption tower 3. The top of the ammonia washing tower 2 is connected to the heating medium (tube side) inlet of the wastewater evaporator 5 via the steam compressor 4. The steam outlet of the wastewater evaporator 5 is connected to the bottom of the ammonia stripping tower 1. The bottom outlet of the cooling medium (shell side) of the wastewater evaporator 5 is connected to the inlet of the wastewater circulating pump 11. The outlet of the wastewater circulating pump 11 is connected to the spray pipe of the wastewater evaporator 5. The ammonia stripping wastewater outlet at the bottom of the ammonia stripping tower 1 is connected to the wastewater evaporator 5, the split evaporator 6, the condenser evaporator 7, and the ammonia stripping wastewater heat exchanger 14 (heating medium) via the ammonia stripping wastewater pump 8. The remaining ammonia water from the tar-ammonia separation equipment... The ammonia water outlet is sequentially connected to the ammonia stripping wastewater heat exchanger 14 (cooling medium), the ammonium phosphate circulating liquid cooler 12 (cooling medium), and the upper part of the ammonia stripping tower 1. The lean liquid outlet at the bottom of the desorption tower 3 is connected to the heating medium inlet of the ammonium phosphate rich liquid heat exchanger 13. The heating medium outlet of the ammonium phosphate rich liquid heat exchanger 13 is connected to the heating medium inlet of the ammonium phosphate circulating liquid cooler 12. The heating medium outlet of the ammonium phosphate circulating liquid cooler 12 is connected to the liquid inlet pipe of the ammonia washing tower 2. The top of the desorption tower 3 is connected to the fractional evaporator 6. The condensate outlet of the fractional evaporator 6 is connected to the upper part of the desorption tower 3. The fractional evaporator 6 is connected to the condenser evaporator 7. The lower part of the condenser evaporator 7 is connected to the concentrated ammonia water cooler 15. The tops of the fractional evaporator 6 and the condenser evaporator 7 are connected to the ammonia stripping tower 1. The bottom of the desorption tower 3 is connected to the cooling medium (tube side) inlet of the heater 16. The cooling medium (tube side) outlet of the heater 16 is connected to the lower part of the desorption tower 3.

[0046] Example 2

[0047] This embodiment discloses an energy-saving and efficient method for producing concentrated ammonia water from waste ammonia water from coking plants. The method uses the system described in Embodiment 1 and specifically includes the following steps:

[0048] Step 1: The residual ammonia water fed into the tar ammonia water separation equipment is heated and heated by the ammonia stripping wastewater heat exchanger 14 and the ammonium phosphate circulating liquid cooler 12 before entering the ammonia stripping tower 1.

[0049] Step 2: The ammonia vapor discharged from the top of the ammonia stripping tower 1 is sent to the ammonia washing tower 2; the ammonia stripping wastewater at the bottom of the ammonia stripping tower 1 is sent to the wastewater evaporator 5, the condenser evaporator 6, the condenser evaporator 7 and the ammonia stripping wastewater heat exchanger 14 respectively via the ammonia stripping wastewater pump 8; the ammonia stripping wastewater sent to the ammonia stripping wastewater heat exchanger 14 is sent to the biochemical device after being cooled by heat exchange.

[0050] The ammonia stripping wastewater sent to wastewater evaporator 5, condenser evaporator 6 and condenser evaporator 7 undergoes heat exchange and vaporization to generate steam which enters the bottom of ammonia stripping tower 1 as a desorption heat source for ammonia stripping tower 1.

[0051] Step 3: The ammonia washing tower 2 uses ammonium phosphate solution as the absorbent. The ammonia vapor entering the ammonia washing tower 2 comes into countercurrent contact with the sprayed ammonium phosphate absorbent inside the tower. The ammonium phosphate solution absorbs NH3 from the ammonia vapor to generate (NH4)2HPO4. The secondary vapor after removing NH3 is discharged from the top of the ammonia washing tower 2.

[0052] The ammonium phosphate solution at the bottom of the ammonia washing tower 2 is sent to the ammonium phosphate circulating liquid cooler 12 for cooling via the ammonium phosphate circulating pump 9, and the ammonium phosphate solution discharged from the ammonium phosphate circulating liquid cooler 12 is sent to the ammonia washing tower 2.

[0053] The ammonium phosphate rich solution that needs to be desorbed at the bottom of the ammonia washing tower 2 is sent to the ammonium phosphate rich solution heat exchanger 13 for heat exchange and temperature increase via the ammonium phosphate feed pump 10.

[0054] Step 4: The secondary steam (ammonia removal steam) discharged from the top of the ammonia washing tower 2 enters the steam compressor 4. The steam compressor 4 is driven by a motor to pressurize the secondary steam, and the pressurized secondary steam enters the wastewater evaporator 5.

[0055] Step 5: Pressurized secondary steam enters the tube side of wastewater evaporator 5. Wastewater in the lower shell side of wastewater evaporator 5 is pressurized by wastewater circulation pump 11 and sent to the spray pipe in the upper tube side of evaporator. Wastewater is sprayed onto the outer wall of heat exchange tubes through the spray nozzles. Pressurized secondary steam in heat exchange tubes exchanges heat with wastewater on the outside of tube walls. Pressurized secondary steam in tubes condenses into condensate, and wastewater on the outside of tubes vaporizes to generate steam. Steam discharged from wastewater evaporator 5 enters ammonia stripping tower 1.

[0056] Pressurized secondary steam condenses in the tube side, and some of the non-condensable gas in the tube side is discharged to the gas system or the incinerator of the acid production unit.

[0057] Step 6: The ammonium phosphate feed pump 10 sends the ammonium phosphate rich solution from the ammonia washing tower 2 to the ammonium phosphate rich solution heat exchanger 13 to exchange heat with the ammonium phosphate lean solution. The heated ammonium phosphate rich solution enters the upper part of the stripping tower 3.

[0058] The desorption tower 3 is equipped with a heater 16 at the bottom, which uses medium-pressure steam to indirectly heat the ammonium phosphate solution at the bottom of the desorption tower 3, and adds direct steam as needed to maintain the system water balance.

[0059] The ammonia vapor discharged from the top of the desorption tower 3 enters the fractional evaporator 6;

[0060] The lean ammonium phosphate solution at the bottom of the desorption tower 3 is discharged to the ammonium phosphate rich solution heat exchanger 13. After the lean ammonium phosphate solution is cooled down by exchanging heat with the ammonium phosphate rich solution, it is discharged to the outlet of the ammonium phosphate circulating liquid pump 9 and mixed with the ammonium phosphate circulating liquid before entering the ammonium phosphate circulating liquid cooler 12.

[0061] Step 7: The ammonia vapor entering the fractional evaporator 6 is cooled by the ammonia stripping wastewater, and the condensate generated by the ammonia vapor condensation is returned to the desorption tower 3; the shell-side ammonia vapor in the fractional evaporator 6 releases heat during the condensation process, which causes the tube-side ammonia stripping wastewater to heat up and vaporize, and the steam generated by the vaporization of the ammonia stripping wastewater enters the ammonia stripping tower 1.

[0062] The ammonia vapor discharged from the split evaporator 6 enters the condenser evaporator 7; the NH3 concentration of the ammonia vapor is controlled at 15-20%.

[0063] The shell-side condensate return pipe of the evaporator 6 adopts a stepped drainage method, and the heat exchange area is adjusted by controlling the condensate level in the shell side of the evaporator 6. The steam pipe pressure regulating valve at the outlet of the tube side of the evaporator 6 controls the wastewater vaporization pressure and adjusts the heat transfer temperature difference between the shell side and the tube side. The above two adjustment methods work together to control the NH3 concentration of the discharged ammonia vapor to be between 15% and 20%.

[0064] Step 8: The ammonia vapor entering the condenser evaporator 7 is condensed into ammonia water. The heat released during the condensation process of the ammonia vapor causes the ammonia stripping wastewater to vaporize. The steam generated by the vaporization of the ammonia stripping wastewater enters the bottom of the ammonia stripping tower 1.

[0065] Step 9: The ammonia water discharged from the condenser evaporator 7 is cooled to room temperature by the concentrated ammonia water cooler 15 and then sent out.

[0066] The ammonia vapor at the inlet of the ammonia washing tower 2 contains 3-4% NH3, and the secondary steam at the outlet of the ammonia washing tower 2 contains 600 mmg / m³ of NH3. 3 .

[0067] The desorption tower 3 operates at a pressure of 0.65 MPa (G), the tube-side pressure of the condenser evaporator 6 is higher than 300 kPa (G), and the tube-side operating pressure of the condenser evaporator 7 is higher than 250 kPa (G).

[0068] The ammonium phosphate concentration in the ammonium phosphate lean solution discharged from the desorption tower 3 is 40%, and the molar ratio of NH3:H3PO4 in the ammonium phosphate lean solution of the stripping tower is 1.20.

[0069] The secondary steam is pressurized by steam compressor 4, and the outlet pressure of the secondary steam of steam compressor 4 needs to be 90 kPa higher than the bottom operating pressure of ammonia stripping tower 1.

[0070] The shell-side operating pressure of the wastewater evaporator 5 is 15 kPa higher than the bottom pressure of the ammonia stripping tower 1.

[0071] The top operating pressure of the ammonia stripping tower (1) is 1.0 kPa, and the bottom operating pressure of the ammonia stripping tower (1) is 25 kPa.

[0072] The outlet temperature of the ammonium phosphate circulating liquid in the ammonium phosphate circulating liquid cooler 12 is 2°C lower than the steam temperature of the ammonia washing tower 2. The remaining ammonia water is used to heat up and remove the ammonium phosphate solution to absorb the heat of reaction generated by NH3.

[0073] Example 3

[0074] This embodiment discloses an energy-saving and efficient method for producing concentrated ammonia water from waste ammonia water from coking plants, using the system described in Embodiment 1, and including the following steps:

[0075] The coking plant produces 2 million tons of coke annually, generating 80 tons of residual ammonia water per hour during coking production. This residual ammonia water undergoes pretreatment including slag removal, oil removal, and degassing. The present invention utilizes an energy-saving and efficient process and equipment for producing concentrated ammonia water from coking residual ammonia water to treat the pretreated residual ammonia water.

[0076] Step 1: The remaining ammonia water is heated by the heat exchanger 14 and the ammonia stripping wastewater cooler 12 and then sent to the ammonia stripping tower 1.

[0077] In step 2, the steam generated from the vaporization of wastewater in wastewater evaporator 5, condenser evaporator 6, and condenser evaporator 7 enters ammonia stripping tower 1. The wastewater at the bottom of ammonia stripping tower 1 is pumped by ammonia stripping wastewater pump 8 to wastewater evaporator 5, condenser evaporator 6, condenser evaporator 7, and ammonia stripping wastewater heat exchanger 14. The top temperature of ammonia stripping tower 1 is 100℃, and the operating pressure is 1 kPa(G). The bottom temperature of ammonia stripping tower 1 is 105℃, and the operating pressure is 25 kPa(G).

[0078] Step 3: Ammonia vapor discharged from the top of ammonia stripping tower 1 enters ammonia washing tower 2 and comes into countercurrent contact with the sprayed ammonium phosphate absorbent, which removes NH3 from the ammonia vapor.

[0079] Step 4: The secondary steam from the ammonia removal tower 2 is discharged to the steam compressor 4 for pressurization. The secondary steam is pressurized to 90 kPa (G) by the steam compressor 4.

[0080] Step 5: Pressurized secondary steam enters the tube side of wastewater evaporator 5. Wastewater from the bottom of wastewater evaporator 5 is pumped to the outer wall of the spray heat exchange tubes via a wastewater circulation pump. The wastewater exchanges heat with the secondary steam inside the tubes and vaporizes to generate steam, which is then sent to ammonia stripping tower 1. The shell side operating pressure of wastewater evaporator 5 is 45 kPa (G).

[0081] Step 6: The rich ammonium phosphate solution at the bottom of the ammonia washing tower 2 is pressurized by the ammonium phosphate feed pump 10 and sent to the rich ammonium phosphate solution heat exchanger 13 to exchange heat with the lean solution in the desorption tower. The rich ammonium phosphate solution is heated to 135°C and enters the desorption tower 3. The bottom of the desorption tower 3 is heated by Central Asian steam to provide heat to the bottom ammonium phosphate solution. The operating pressure at the bottom of the desorption tower 3 is 650 kPa(G), and the operating pressure at the top of the desorption tower is ~600 kPa(G).

[0082] Step 7: The ammonia vapor from the top of the desorption tower 3 enters the fractional evaporator. The wastewater exchanges heat with the ammonia vapor and vaporizes to generate 300 kPa (G) steam, which is sent to the ammonia stripping tower 1. The ammonia vapor condensate is returned to the desorption tower 3.

[0083] Step 8: Ammonia vapor is condensed and reduced to a concentration of 20% and enters the condenser evaporator 7. Wastewater exchanges heat with ammonia vapor to generate 250 kPa (G) steam, which is sent to the ammonia stripping tower 1.

[0084] Step 9: Ammonia vapor is condensed into concentrated ammonia water and flows to concentrated ammonia water cooler 15 to be cooled to room temperature before being sent out.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water, characterized by, The system comprises an ammonia distillation tower (1), an ammonia washing tower (2), a desorption tower (3), a steam compressor (4), a wastewater evaporator (5), a fractionation evaporator (6), a condensation evaporator (7), an ammonia distillation wastewater pump (8), a phosphorus-ammonium circulating pump (9), a phosphorus-ammonium feeding pump (10), a wastewater circulating pump (11), a phosphorus-ammonium circulating liquid cooler (12), a phosphorus-ammonium rich liquid heat exchanger (13), an ammonia distillation wastewater heat exchanger (14), a concentrated ammonia water cooler (15) and a heater (16). The top of the ammonia distillation tower (1) is communicated with the ammonia washing tower (2), the ammonia washing tower (2) is communicated with the heating medium inlet of the phosphorus-ammonium circulating liquid cooler (12) through the phosphorus-ammonium circulating pump (9), the bottom of the ammonia washing tower (2) is communicated with the cooling medium inlet of the phosphorus-ammonium rich liquid heat exchanger (13) through the phosphorus-ammonium feeding pump (10), the cooling medium outlet of the phosphorus-ammonium rich liquid heat exchanger (13) is communicated with the desorption tower (3), the top of the ammonia washing tower (2) is communicated with the heating medium inlet of the wastewater evaporator (5) through the steam compressor (4), the steam outlet of the wastewater evaporator (5) is communicated with the ammonia distillation tower (1), the bottom cooling medium outlet of the wastewater evaporator (5) is communicated with the inlet of the wastewater circulating pump (11), the outlet of the wastewater circulating pump (11) is communicated with the spraying pipe of the wastewater evaporator (5), the ammonia distillation wastewater outlet at the bottom of the ammonia distillation tower (1) is respectively communicated with the wastewater evaporator (5), the fractionation evaporator (6), the condensation evaporator (7) and the ammonia distillation wastewater heat exchanger (14) through the ammonia distillation wastewater pump (8), the remaining ammonia water outlet of the tar-ammonia water separation equipment is sequentially communicated with the ammonia distillation wastewater heat exchanger (14), the phosphorus-ammonium circulating liquid cooler (12) and the ammonia distillation tower (1), the bottom lean liquid outlet of the desorption tower (3) is communicated with the heating medium inlet of the phosphorus-ammonium rich liquid heat exchanger (13), the heating medium outlet of the phosphorus-ammonium rich liquid heat exchanger (13) is communicated with the heating medium inlet of the phosphorus-ammonium circulating liquid cooler (12), the heating medium outlet of the phosphorus-ammonium circulating liquid cooler (12) is communicated with the liquid inlet pipe of the ammonia washing tower (2), the top of the desorption tower (3) is communicated with the fractionation evaporator (6), the fractionation evaporator (6) is communicated with the condensation evaporator (7), the condensation evaporator (7) is communicated with the concentrated ammonia water cooler (15), the top of the fractionation evaporator (6) and the condensation evaporator (7) is communicated with the ammonia distillation tower (1), the bottom of the desorption tower (3) is communicated with the cooling medium inlet of the heater (16), and the cooling medium outlet of the heater (16) is communicated with the lower part of the desorption tower (3).

2. The system for energy saving and efficient production of concentrated ammonia water from coke-making residual ammonia water according to claim 1, characterized in that, The condensate outlet of the fractionation evaporator (6) is communicated with the desorption tower (3).

3. A method for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water, characterized by, The system for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water according to claim 1 or 2 comprises the following steps: Step 1: the residual ammonia water sent by the tar-ammonia water separation equipment is heated and warmed by the ammonia distillation wastewater heat exchanger (14) and the phosphorus-ammonium circulating liquid cooler (12) and then enters the ammonia distillation tower (1); Step 2, the ammonia vapor discharged from the top of the ammonia stripping tower (1) is sent to the ammonia washing tower (2); the ammonia stripping wastewater at the bottom of the ammonia stripping tower (1) is sent to the wastewater evaporator (5), the partial condensation evaporator (6), the condensation evaporator (7) and the ammonia stripping wastewater heat exchanger (14) by the ammonia stripping wastewater pump (8) respectively; the ammonia stripping wastewater sent to the ammonia stripping wastewater heat exchanger (14) is cooled by heat exchange and then sent to the biochemical device; The ammonia stripping wastewater sent to the wastewater evaporator (5), the partial condensation evaporator (6) and the condensation evaporator (7) is heat exchanged and vaporized to generate steam which enters the bottom of the ammonia stripping tower (1) as a heat source for desorption of the ammonia stripping tower (1); Step 3, the ammonia washing tower (2) uses phosphorus ammonium solution as the absorbing liquid, the ammonia vapor entering the ammonia washing tower (2) is in countercurrent contact with the sprayed phosphorus ammonium absorbing liquid in the tower, the phosphorus ammonium solution absorbs NH3 in the ammonia vapor to generate (NH4)2HPO4, and the secondary steam after removal of NH3 is discharged from the top of the ammonia washing tower (2); The phosphorus ammonium rich solution at the bottom of the ammonia washing tower (2) is sent to the phosphorus ammonium circulating liquid cooler (12) by the phosphorus ammonium circulating pump (9) for cooling, and the phosphorus ammonium solution discharged from the phosphorus ammonium circulating liquid cooler (12) is sent to the ammonia washing tower (2); The phosphorus ammonium rich solution that needs to be desorbed at the bottom of the ammonia washing tower (2) is sent to the phosphorus ammonium rich solution heat exchanger (13) by the phosphorus ammonium feeding pump (10) for heat exchange and temperature rise; Step 4, the secondary steam discharged from the top of the ammonia washing tower (2) enters the steam compressor (4), the steam compressor (4) is driven by the motor to pressurize the secondary steam, and the pressurized secondary steam enters the wastewater evaporator (5); Step 5, the pressurized secondary steam enters the tube side of the wastewater evaporator (5), the wastewater at the lower part of the shell side of the wastewater evaporator (5) is pressurized by the wastewater circulating pump (11) and sent to the spray pipe at the upper part of the evaporator tube side, the wastewater is sprayed on the outer wall of the heat exchange tube by the nozzle, the pressurized secondary steam in the heat exchange tube is heat exchanged with the wastewater on the outer side of the tube wall, the pressurized secondary steam in the tube is condensed into condensed water, and the wastewater on the outer wall of the tube is vaporized to generate steam; the steam discharged from the wastewater evaporator (5) enters the ammonia stripping tower (1); The pressurized secondary steam is condensed in the tube side, and part of the non-condensable gas in the tube side is discharged to the gas system or the incinerator of the acid making device; Step 6, the phosphorus ammonium rich solution of the ammonia washing tower (2) is sent to the phosphorus ammonium rich solution heat exchanger (13) by the phosphorus ammonium feeding pump (10) for heat exchange with the phosphorus ammonium lean solution, and the phosphorus ammonium rich solution after temperature rise enters the upper part of the desorption tower (3); The ammonia vapor discharged from the top of the desorption tower (3) enters the partial condensation evaporator (6); The phosphorus ammonium lean solution at the bottom of the desorption tower (3) is discharged to the phosphorus ammonium rich solution heat exchanger (13), and the phosphorus ammonium lean solution is cooled by heat exchange with the phosphorus ammonium rich solution and then discharged to the outlet of the phosphorus ammonium circulating pump (9) to be mixed with the phosphorus ammonium circulating liquid and then enter the phosphorus ammonium circulating liquid cooler (12); Step 7, the ammonia vapor entering the partial condensation evaporator (6) is cooled by the ammonia stripping wastewater, the condensed liquid generated by the condensation of the ammonia vapor flows back to the desorption tower (3); the ammonia vapor in the shell side of the partial condensation evaporator (6) releases heat during the condensation process to heat and vaporize the ammonia stripping wastewater in the tube side, and the steam generated by the vaporization of the ammonia stripping wastewater enters the ammonia stripping tower (1); The ammonia vapor discharged from the partial condensation evaporator (6) enters the condensation evaporator (7); Step 8, the ammonia vapor entering the condensing evaporator (7) is condensed into ammonia water, and the heat released during the condensation of the ammonia vapor vaporizes the ammonia vaporized wastewater, and the steam generated by the vaporization of the ammonia vaporized wastewater enters the bottom of the ammonia stripping tower (1); Step 9, the ammonia water discharged from the condensing evaporator (7) is cooled to room temperature by the concentrated ammonia water cooler (15) and then sent out.

4. The method for saving energy and efficiently producing concentrated ammonia water from coking residual ammonia water according to claim 3, characterized by, The NH3 concentration of the ammonia vapor at the inlet of the ammonia washing tower (2) is 3-4%, and the NH3 concentration of the secondary steam at the outlet of the ammonia washing tower (2) is 500-800 mg / M 3 .

5. The method for saving energy and efficiently producing concentrated ammonia water from coke-making residual ammonia water according to claim 3, characterized by, The operating pressure of the desorption tower (3) is 0.65-1.0 MPa (G), the tube side pressure of the partial condensing evaporator (6) is higher than 300-350 kPa (G), and the tube side operating pressure of the condensing evaporator (7) is higher than 250-300 kPa (G); And / or, the concentration of phosphorus ammonium in the phosphorus ammonium lean solution discharged from the desorption tower (3) is 40-45%, and the molar ratio of NH3 to H3PO4 in the phosphorus ammonium lean solution in the desorption tower is 1.18-1.

23.

6. The method for saving energy and efficiently producing concentrated ammonia water from coking residual ammonia water according to claim 3, characterized by, The bottom of the desorption tower (3) is provided with a heater (16) for indirectly heating the phosphorus ammonium solution at the bottom of the desorption tower (3) with medium-pressure steam, and appropriate direct steam is supplemented as needed to maintain the water balance of the system.

7. The method for saving energy and efficiently producing concentrated ammonia water from coke-making residual ammonia water according to claim 3, characterized by, The secondary steam is pressurized by the steam compressor (4), and the outlet pressure of the secondary steam of the steam compressor (4) needs to be higher than the operating pressure of the bottom of the ammonia stripping tower (1) by 40-60 kPa.

8. The method for saving energy and efficiently producing concentrated ammonia water from coke-making residual ammonia water according to claim 3, characterized by, The shell side operating pressure of the wastewater evaporator (5) is higher than the bottom pressure of the ammonia stripping tower (1) by 10-15 kPa.

9. The method for saving energy and efficiently producing concentrated ammonia water from coke-making residual ammonia water according to claim 3, characterized by, The outlet temperature of the phosphorus ammonium circulating liquid cooler (12) is lower than the steam temperature of the ammonia washing tower (2) by 1-2℃.

10. The method for saving energy and efficiently producing concentrated ammonia water from coke-making residual ammonia water according to claim 3, characterized by, The ammonia vapor discharged from the partial condensing evaporator (6) enters the condensing evaporator (7), and the NH3 concentration of the ammonia vapor is controlled to be 15-20%.

Images