Method and system for energy-saving and efficient production of stronger ammonia water from coking residual ammonia water

Abstract

The invention provides a method and a system for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water. The system comprises an ammonia still (1), an ammonia washing tower (2), a desorption tower (3), a vapor compressor (4), a wastewater evaporator (5), a division evaporator (6), a condensation evaporator (7), an ammonia still wastewater pump (8), an ammonium phosphate circulating pump (9), an ammonium phosphate feeding pump (10), a wastewater circulating pump (11), an ammonium phosphate circulating liquid cooler (12), an ammonium phosphate pregnant solution heat exchanger (13), an ammonia still wastewater heat exchanger (14) and a stronger ammonia water cooler (15). And a heater (16). The invention also discloses a method for energy-saving and efficient production of stronger ammonia water from coking residual ammonia water. The energy-saving and efficient concentrated ammonia water production system for coking residual ammonia water is simple, energy-saving and efficient, and a concentrated ammonia water product prepared by adopting the system can meet related standard requirements.

Description

Technical Field

[0001] The invention relates to coal chemical technology, and in particular to a method and a system for energy-saving and efficient production of concentrated ammonia water from residual ammonia water from coking. Background Art

[0002] Coke ovens produce a large amount of production wastewater during the coking process; the main source of this production wastewater is the moisture carried by the coking coal and the coking chemical water. This production wastewater is called residual ammonia water. The amount of residual ammonia water produced is about 12-13% of the coking coal. The residual ammonia water contains a large number of various pollutants, including organic pollutants and inorganic pollutants; the organic pollutants mainly include aromatic hydrocarbons such as phenols; the inorganic pollutants include NH3, H2S, HCN and ammonium salts. It contains NH3~4g / l, H2S~0.5g / l, and HCN~0.3g / l. Domestic coking plants generally use steam desorption process to treat residual ammonia water, and the ammonia wastewater discharged from the ammonia tower contains 150-200mmg / l of ammonia nitrogen. The top reducer of the ammonia tower discharges ammonia vapor with an NH3 concentration of 15-20%, and the ammonia vapor also contains about 2-3% H2S and about 1% HCN. The ammonia vapor containing acidic gas discharged by the reducer is sent to the coal gas primary cooling system.

[0003] The ammonia evaporation unit uses steam as a heat source to desorb and treat the remaining ammonia water. The wastewater biochemical treatment unit requires that the ammonia nitrogen in the ammonia evaporation wastewater discharged from the ammonia evaporation unit is ≤150-200 mmg / l. In order to ensure the desorption efficiency of the ammonia evaporation tower, 150-180 kg of steam is required to treat each ton of remaining ammonia water. The ammonia vapor discharged from the top of the ammonia evaporation tower can only contain 3-4% NH3. The top reducer condenses the ammonia vapor to ammonia vapor containing 20% ​​NH3 and discharges it from the reducer. A large amount of water vapor in the ammonia vapor is condensed in the reducer, and a large amount of cooling water is also consumed in the ammonia vapor process. Summary of the invention

[0004] The purpose of the present invention is to propose a system for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water, in view of the problems that the current method for analyzing and treating the residual ammonia water from coking has large steam consumption and high operating costs; the ammonia water produced by condensing ammonia vapor contains oil and acidic gas, and the ammonia water product cannot be exported. The system is simple, energy-saving and efficient, and the concentrated ammonia water product prepared by the system can meet the requirements of relevant standards.

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

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is: a system for energy-saving and efficient production of concentrated ammonia water from residual ammonia water in coking, comprising an ammonia evaporator, an ammonia washing tower, a desorption tower, a steam compressor, a wastewater evaporator, a fractionation evaporator, a condensation evaporator, an ammonia evaporation wastewater pump, a phosphate ammonium circulation pump, a phosphate ammonium feed pump, a wastewater circulation pump, a phosphate ammonium circulation liquid cooler, a phosphate ammonium rich liquid heat exchanger, an ammonia evaporation wastewater heat exchanger, a concentrated ammonia water cooler and a heater;

[0007] The top of the ammonia evaporation tower is connected to the ammonia washing tower, and the ammonia washing tower is connected to the heating medium inlet of the phosphate ammonium circulating liquid cooler through the phosphate ammonium circulation pump; the bottom of the ammonia washing tower is connected to the cooling medium inlet of the phosphate ammonium rich liquid heat exchanger through the phosphate ammonium feeding pump, and the cooling medium outlet of the phosphate ammonium 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 through the steam compressor, the steam outlet of the wastewater evaporator is connected to the ammonia evaporation tower, the bottom outlet of the cooling medium of the wastewater evaporator is connected to the inlet of the wastewater circulation pump, and the outlet of the wastewater circulation pump is connected to the spray pipe of the wastewater evaporator, and the ammonia evaporation wastewater outlet at the bottom of the ammonia evaporation tower is respectively connected to the wastewater evaporator, the fractionation evaporator, the condensation evaporator and the ammonia evaporation wastewater heat exchanger through the ammonia evaporation wastewater pump. The residual ammonia water outlet of the tar ammonia water separation equipment is connected with the ammonia evaporation wastewater heat exchanger, the phosphate ammonium circulating liquid cooler and the ammonia evaporation tower in sequence, the lean liquid outlet at the bottom of the desorption tower is connected with the heating medium inlet of the phosphate ammonium rich liquid heat exchanger, the heating medium outlet of the phosphate ammonium rich liquid heat exchanger is connected with the heating medium inlet of the phosphate ammonium circulating liquid cooler, and the heating medium outlet of the phosphate ammonium circulating liquid cooler is connected with the liquid inlet pipe of the ammonia washing tower; the top of the desorption tower is connected with the fractionation evaporator, the fractionation evaporator is connected with the condensation evaporator, and the condensation evaporator is connected with the concentrated ammonia water cooler; the fractionation evaporator and the condensation evaporator tops are connected with the ammonia evaporation tower; the bottom of the desorption tower is connected with the cooling medium inlet of the heater, and the cooling medium outlet of the heater is connected with the desorption tower.

[0008] Furthermore, the condensate outlet of the fractionation evaporator is communicated with the upper part of the desorption tower.

[0009] Another object of the present invention is to disclose a method for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water, comprising the following steps:

[0010] Step 1, the remaining ammonia water sent into the tar ammonia water separation equipment is heat-exchanged and heated through the ammonia distillation wastewater heat exchanger and the phosphate ammonium circulating liquid cooler before entering the ammonia distillation tower;

[0011] Step 2, the ammonia vapor discharged from the top of the ammonia evaporation tower is sent to the ammonia washing tower; the ammonia evaporation wastewater at the bottom of the ammonia evaporation tower is respectively sent to the wastewater evaporator, the fractionation evaporator, the condensation evaporator and the ammonia evaporation wastewater heat exchanger through the ammonia evaporation wastewater pump; the ammonia evaporation wastewater sent to the ammonia evaporation wastewater heat exchanger is cooled by heat exchange and then sent to the biochemical device;

[0012] The ammonia evaporation wastewater sent to the wastewater evaporator, fractionation evaporator and condensation evaporator is heat exchanged and vaporized to generate steam which enters the bottom of the ammonia evaporation tower and serves as a desorption heat source for the ammonia evaporation tower.

[0013] Step 3, the ammonia washing tower uses ammonium phosphate solution as an absorption liquid, the ammonia vapor entering the ammonia washing tower is in countercurrent contact with the sprayed ammonium phosphate absorption liquid in the tower, the ammonium phosphate solution absorbs NH3 in the ammonia vapor to generate (NH4)2HPO4, and the secondary steam from which NH3 is removed is discharged from the top of the ammonia washing tower;

[0014] The ammonium phosphate rich liquid at the bottom of the ammonia washing tower is sent to the ammonium phosphate circulating liquid cooler for cooling through 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 phosphate ammonium rich liquid that needs to be desorbed at the bottom of the ammonia washing tower is pumped to the phosphate ammonium rich liquid heat exchanger for heat exchange and temperature increase through the phosphate ammonium feed pump;

[0016] Step 4, the secondary steam (deammoniation 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, the pressurized secondary steam enters the tube side of the wastewater evaporator, the wastewater at the lower part of the shell side of the wastewater evaporator is pressurized by the wastewater circulation pump 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 of the tube side through the nozzle, the pressurized secondary steam in the heat exchange tube exchanges heat 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 wastewater evaporator discharges steam and enters the ammonia distillation tower;

[0018] The pressurized secondary steam is condensed in the tube, and part of the non-condensable gas in the tube is discharged to the gas system or the incinerator of the acid-making device;

[0019] Step 6, the phosphate ammonium feeding pump delivers the phosphate ammonium rich liquid from the ammonia washing tower to the phosphate ammonium rich liquid heat exchanger for heat exchange with the phosphate ammonium lean liquid, and the heated phosphate ammonium rich liquid enters the upper part of the analytical tower;

[0020] The ammonia gas discharged from the top of the desorption tower enters the fractionation evaporator;

[0021] The phosphate ammonium lean liquid at the bottom of the desorption tower is discharged to the phosphate ammonium rich liquid heat exchanger, and the phosphate ammonium lean liquid is heat exchanged with the phosphate ammonium rich liquid to cool down and then discharged to the outlet of the phosphate ammonium circulating liquid pump and mixed with the phosphate ammonium circulating liquid to enter the phosphate ammonium circulating liquid cooler;

[0022] Step 7, the ammonia vapor entering the fractionation evaporator is cooled by the ammonia evaporation wastewater, and the condensate generated by the condensation of the ammonia vapor flows back to the desorption tower; the ammonia vapor in the shell side of the fractionation evaporator releases heat during the condensation process to heat and vaporize the ammonia evaporation wastewater in the tube side, and the steam generated by the vaporization of the ammonia evaporation wastewater enters the ammonia evaporation tower;

[0023] The ammonia vapor discharged from the fractionation evaporator enters the condensation evaporator;

[0024] Step 8, the ammonia vapor entering the condensation evaporator is condensed into ammonia water, and the heat released during the condensation process of the ammonia vapor vaporizes the ammonia evaporation wastewater, and the steam generated by the vaporization of the ammonia evaporation wastewater enters the bottom of the ammonia evaporation tower;

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

[0026] Furthermore, the ammonia vapor at the inlet of the ammonia scrubbing tower contains 3-4% NH3, and the secondary steam at the outlet of the ammonia scrubbing tower contains 500-800 mmg / M NH3. 3 Unless otherwise specified, % in the present invention refers to mass percentage.

[0027] Furthermore, the operating pressure of the desorption tower is 0.65-1.0 MPa (G), the tube-side pressure of the fractionation evaporator is higher than 300-350 kPa (G), and the tube-side operating pressure of the condensation 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 from the analysis tower is 1.18-1.23.

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

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

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

[0032] Furthermore, the ammonia vapor discharged from the fractionation evaporator enters the condensation evaporator, and the NH3 concentration of the ammonia vapor is controlled to be 15-20%.

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

[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, and an appropriate amount of direct steam is added as needed to maintain the water balance of the system;

[0035] The method and system for producing concentrated ammonia water from residual ammonia water from coking in the present invention in an energy-saving and efficient manner have the following advantages compared with the prior art:

[0036] 1) The present invention can recover NH3 in the 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 less than 0.02%; the quality of the ammonia water meets the requirements for flue gas denitrification.

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

[0038] 3) The present invention adopts the acid cleaning + MVR (steam compressor) combination technology to solve the problem of wastewater evaporator corrosion, improve the energy efficiency ratio of the heat pump unit, and the COP energy efficiency coefficient reaches 15-18%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the structure of a system for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0041] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0042] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0043] Example 1

[0044] This embodiment discloses a system for energy-saving and efficient production of concentrated ammonia water from residual ammonia water from coking, and its structure is as follows: Figure 1 As shown, it includes an ammonia evaporation tower 1, an ammonia washing tower 2, a desorption tower 3, a steam compressor 4, an evaporator 5, a fractionation evaporator 6, a condensation evaporator 7, an ammonia evaporation wastewater pump 8, a phosphate ammonium circulation pump 9, a phosphate ammonium feeding pump 10, a wastewater circulation 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 still tower 1 is connected with the lower part of the ammonia washing tower 2, and the lower part of the ammonia washing tower 2 is connected with the heating medium inlet of the phosphate ammonium circulating liquid cooler 12 through the phosphate ammonium circulating pump 9; the bottom of the ammonia washing tower 2 is connected with the cooling medium inlet of the phosphate ammonium rich liquid heat exchanger 13 through the phosphate ammonium feeding pump 10, and the cooling medium outlet of the phosphate ammonium rich liquid heat exchanger 13 is connected with the upper part of the desorption tower 3, the top of the ammonia washing tower 2 is connected with the heating medium (tube side) inlet of the wastewater evaporator 5 through the steam compressor 4, the steam outlet of the wastewater evaporator 5 is connected with the lower part of the ammonia still tower 1, the cooling medium (shell side) bottom outlet of the wastewater evaporator 5 is connected with the inlet of the wastewater circulating pump 11, and the outlet of the wastewater circulating pump 11 is connected with the spray pipe of the wastewater evaporator 5, the ammonia wastewater outlet at the bottom of the ammonia still tower 1 is connected with the wastewater evaporator 5, the fractionation evaporator 6, the condensation evaporator 7 and the ammonia wastewater heat exchanger 14 (heating medium) through the ammonia wastewater pump 8, and the residual of the tar ammonia separation equipment is connected with the wastewater evaporator 5, the fractionation evaporator 6, the condensation evaporator 7 and the ammonia wastewater heat exchanger 14 (heating medium). The ammonia water outlet is connected with the ammonia evaporation wastewater heat exchanger 14 (cooling medium), the phosphate ammonium circulating liquid cooler 12 (cooling medium) and the upper part of the ammonia evaporation tower 1 in sequence, the lean liquid outlet at the bottom of the desorption tower 3 is connected with the heating medium inlet of the phosphate ammonium rich liquid heat exchanger 13, the heating medium outlet of the phosphate ammonium rich liquid heat exchanger 13 is connected with the heating medium inlet of the phosphate ammonium circulating liquid cooler 12, and the heating medium outlet of the phosphate ammonium circulating liquid cooler 12 is connected with the liquid inlet pipe of the ammonia washing tower 2; the top of the desorption tower 3 is connected with the fractionation and contraction evaporator 6, and the condensate outlet of the fractionation and contraction evaporator 6 is connected with the upper part of the desorption tower 3; the fractionation and contraction evaporator 6 is connected with the condensation evaporator 7, and the lower part of the condensation evaporator 7 is connected with the concentrated ammonia water cooler 15; the fractionation and contraction evaporator 6 and the condensation evaporator 7 are connected with the ammonia evaporation tower 1; the bottom of the desorption tower 3 is connected with the cooling medium (tube side) inlet of the heater 16, and the cooling medium (tube side) outlet of the heater 16 is connected with the lower part of the desorption tower 3.

[0046] Example 2

[0047] This embodiment discloses a method for energy-saving and efficient production of concentrated ammonia water from residual ammonia water in coking, using the system described in Example 1, specifically comprising the following steps:

[0048] Step 1, the remaining ammonia water sent into the tar ammonia water separation equipment is heat exchanged and heated by the ammonia evaporation wastewater heat exchanger 14 and the phosphate ammonium circulating liquid cooler 12 to enter the ammonia evaporation tower 1;

[0049] Step 2, the ammonia vapor discharged from the top of the ammonia still 1 is sent to the ammonia scrubbing tower 2; the ammonia still wastewater at the bottom of the ammonia still 1 is sent to the wastewater evaporator 5, the fractionation evaporator 6, the condensation evaporator 7 and the ammonia still wastewater heat exchanger 14 respectively through the ammonia still wastewater pump 8; the ammonia still wastewater sent to the ammonia still wastewater heat exchanger 14 is sent to the biochemical device after heat exchange and cooling;

[0050] The ammonia evaporation wastewater sent to the wastewater evaporator 5, the fractionation evaporator 6 and the condensation evaporator 7 is heat exchanged and vaporized to generate steam which enters the bottom of the ammonia evaporation tower 1 and serves as a desorption heat source for the ammonia evaporation tower 1;

[0051] Step 3, the ammonia washing tower 2 uses ammonium phosphate solution as the absorption liquid, the ammonia gas entering the ammonia washing tower 2 is countercurrently contacted with the sprayed ammonium phosphate absorption liquid in the tower, the ammonium phosphate solution absorbs NH3 in the ammonia gas to generate (NH4)2HPO4, and the secondary steam from which NH3 is removed is discharged from the top of the ammonia washing tower 2;

[0052] The ammonium phosphate rich liquid at the bottom of the ammonia washing tower 2 is sent to the ammonium phosphate circulating liquid cooler 12 for cooling through 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 phosphate ammonium rich liquid that needs to be desorbed at the bottom of the ammonia washing tower 2 is sent to the phosphate ammonium rich liquid heat exchanger 13 for heat exchange and temperature increase through the phosphate ammonium feed pump 10;

[0054] Step 4, the secondary steam (deammoniation steam) discharged from the top of the ammonia washing tower 2 enters the steam compressor 4, and 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, the pressurized secondary steam enters the tube side of the wastewater evaporator 5, the wastewater in the lower part of the shell side of the wastewater evaporator 5 is pressurized by the wastewater circulation pump 11 and sent to the spray pipe on the upper part of the evaporator tube side, the wastewater is sprayed on the outer wall of the tube side heat exchange tube through the nozzle, the pressurized secondary steam in the heat exchange tube exchanges heat with the wastewater on the outside 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 wastewater evaporator 5 discharges steam and enters the ammonia distillation tower 1.

[0056] The pressurized secondary steam is condensed in the tube, and part of the non-condensable gas in the tube is discharged to the gas system or the incinerator of the acid-making device;

[0057] Step 6, the phosphate ammonium feeding pump 10 delivers the phosphate ammonium rich liquid from the ammonia washing tower 2 to the phosphate ammonium rich liquid heat exchanger 13 for heat exchange with the phosphate ammonium lean liquid, and the heated phosphate ammonium rich liquid enters the upper part of the analytical tower 3;

[0058] A heater 16 is provided at the bottom of the desorption tower 3, and medium-pressure steam is used to indirectly heat the ammonium phosphate solution at the bottom of the desorption tower 3, and direct steam is added in an appropriate amount as needed to maintain the water balance of the system;

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

[0060] The phosphate ammonium lean liquid at the bottom of the desorption tower 3 is discharged to the phosphate ammonium rich liquid heat exchanger 13, and the phosphate ammonium lean liquid is cooled by heat exchange with the phosphate ammonium rich liquid and then discharged to the outlet of the phosphate ammonium circulating liquid pump 9 and mixed with the phosphate ammonium circulating liquid to enter the phosphate ammonium circulating liquid cooler 12;

[0061] Step 7, the ammonia vapor entering the fractionation evaporator 6 is cooled by the ammonia evaporation wastewater, and the condensate generated by the condensation of the ammonia vapor flows back to the desorption tower 3; the ammonia vapor in the shell side of the fractionation evaporator 6 releases heat during the condensation process to heat and vaporize the ammonia evaporation wastewater in the tube side, and the steam generated by the vaporization of the ammonia evaporation wastewater enters the ammonia evaporation tower 1;

[0062] The ammonia vapor discharged from the fractionation evaporator 6 enters the condensation evaporator 7; the NH3 concentration of the ammonia vapor is controlled to be 15-20%.

[0063] The shell-side condensate reflux pipe of the fractionation evaporator 6 adopts a stepped discharge method, and the heat exchange area is adjusted by controlling the condensate level height of the shell-side of the fractionation evaporator 6; the steam pipe pressure regulating valve at the outlet of the tube-side of the fractionation 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 regulating means cooperate to control the NH3 concentration of the discharged ammonia vapor to be 15-20%.

[0064] Step 8, the ammonia vapor entering the condensation evaporator 7 is condensed into ammonia water, and the heat released during the condensation of the ammonia vapor vaporizes the ammonia evaporation wastewater, and the steam generated by the vaporization of the ammonia evaporation wastewater enters the bottom of the ammonia evaporation 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 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 600 mmg / M 3 .

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

[0068] The concentration of ammonium phosphate 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 from the desorption tower is 1.20.

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

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

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

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

[0073] Example 3

[0074] This embodiment discloses a method for energy-saving and efficient production of concentrated ammonia water from residual ammonia water in coking, using the system described in Example 1, including the following steps:

[0075] The coking plant produces 2 million tons of coke per year, and produces 80t / h of residual ammonia water in the coking production. The residual ammonia water is pre-treated by deslagging, degreasing and degassing. The energy-saving and efficient concentrated ammonia water production process and equipment of the coking residual ammonia water of the present invention are used to treat the residual ammonia water after pretreatment.

[0076] Step 1, the remaining ammonia water is heated by the heat exchanger 14 and the ammonium phosphate circulating liquid cooler 12 and then sent to the ammonia distillation tower 1;

[0077] Step 2: Steam generated by the vaporization of wastewater in the wastewater evaporator 5, the fractionation evaporator 6, and the condensation evaporator 7 enters the ammonia distillation tower 1. The wastewater at the bottom of the ammonia distillation tower 1 is sent to the wastewater evaporator 5, the fractionation evaporator 6, the condensation evaporator 7, and the ammonia distillation wastewater heat exchanger 14 via the ammonia distillation wastewater pump 8. The top temperature of the ammonia distillation tower 1 is 100°C and the operating pressure is 1 kPa (G), and the bottom temperature of the ammonia distillation tower 1 is 105°C and the operating pressure is 25 kPa (G).

[0078] Step 3, the ammonia vapor discharged from the top of the ammonia still 1 enters the ammonia scrubber 2 and contacts with the sprayed phosphate ammonium absorption liquid in countercurrent, and the phosphate ammonium absorption liquid removes NH3 in the ammonia vapor;

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

[0080] Step 5, the pressurized secondary steam enters the tube side of the wastewater evaporator 5, and the wastewater at the bottom of the wastewater evaporator 5 is pumped to the spray pipe to spray the outer wall of the heat exchange tube through the wastewater circulation pump. The wastewater exchanges heat with the secondary steam in the tube to generate steam that is sent to the ammonia distillation tower 1. The shell side operating pressure of the wastewater evaporator 5 is 45kPa (G).

[0081] Step 6: The ammonium phosphate rich liquid at the bottom of the ammonia washing tower 2 is pressurized by the ammonium phosphate feed pump 10 and sent to the ammonium phosphate rich liquid heat exchanger 13 for heat exchange with the lean liquid of the desorption tower. The ammonium phosphate rich liquid is heated to 135°C and enters the desorption tower 3. The ammonium phosphate solution at the bottom of the desorption tower 3 is heated by Central Asian steam to provide heat for the desorption tower 3. 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 at the top of the desorption tower 3 enters the fractionation evaporator, the wastewater and the ammonia vapor are heat exchanged and vaporized to generate 300kPa (G) steam which is sent to the ammonia evaporation tower 1, and the ammonia vapor condensate is refluxed 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 and ammonia vapor are heat-exchanged and vaporized to generate 250 kPa (G) steam which is sent to the ammonia evaporation tower 1.

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

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 in that: It comprises an ammonia evaporation 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 evaporation wastewater pump (8), a phosphate ammonium circulation pump (9), a phosphate ammonium feed pump (10), a wastewater circulation pump (11), a phosphate ammonium circulation liquid cooler (12), a phosphate ammonium rich liquid heat exchanger (13), an ammonia evaporation wastewater heat exchanger (14), a concentrated ammonia water cooler (15) and a heater (16); The top of the ammonia evaporation tower (1) is connected to the ammonia washing tower (2), and the ammonia washing tower (2) is connected to the heating medium inlet of the phosphate ammonium circulating liquid cooler (12) through the phosphate ammonium circulation pump (9); the bottom of the ammonia washing tower (2) is connected to the cooling medium inlet of the phosphate ammonium rich liquid heat exchanger (13) through the phosphate ammonium feeding pump (10), and the cooling medium outlet of the phosphate ammonium rich liquid heat exchanger (13) is connected to the desorption tower (3); the top of the ammonia washing tower (2) is connected to the wastewater evaporator (5) through the steam compressor (4). The heating medium inlet is connected, the steam outlet of the wastewater evaporator (5) is connected to the ammonia evaporation tower (1), the cooling medium bottom outlet of the wastewater evaporator (5) is connected to the inlet of the wastewater circulation pump (11), the outlet of the wastewater circulation pump (11) is connected to the spray pipe of the wastewater evaporator (5), and the ammonia evaporation wastewater outlet at the bottom of the ammonia evaporation tower (1) is connected to the wastewater evaporator (5), the fractionation evaporator (6), the condensation evaporator (7) and the ammonia evaporation wastewater heat exchanger (1) through the ammonia evaporation wastewater pump (8). 4), the residual ammonia water outlet of the tar ammonia water separation equipment is connected to the ammonia evaporation wastewater heat exchanger (14), the phosphate ammonium circulating liquid cooler (12) and the ammonia evaporation tower (1) in sequence, the lean liquid outlet at the bottom of the desorption tower (3) is connected to the heating medium inlet of the phosphate ammonium rich liquid heat exchanger (13), the heating medium outlet of the phosphate ammonium rich liquid heat exchanger (13) is connected to the heating medium inlet of the phosphate ammonium circulating liquid cooler (12), and the heating medium outlet of the phosphate ammonium circulating liquid cooler (12) is connected to the ammonia washing tower (2) the liquid inlet pipe is connected; the top of the desorption tower (3) is connected to the fractionation evaporator (6), the fractionation evaporator (6) is connected to the condensation evaporator (7), and the condensation evaporator (7) is connected to the concentrated ammonia water cooler (15); the tops of the fractionation evaporator (6) and the condensation evaporator (7) are connected to the ammonia evaporation tower (1); the bottom of the desorption tower (3) is connected to the cooling medium inlet of the heater (16), and the cooling medium (tube side) outlet of the heater (16) is connected to the lower part of the desorption tower (3).

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

3. A method for energy-saving and efficient production of concentrated ammonia water from coking residual ammonia water, characterized in that: The following steps are involved: Step 1, the remaining ammonia water sent into the tar ammonia water separation device is heated through the ammonia evaporation wastewater heat exchanger (14) and the phosphate ammonium circulating liquid cooler (12) and then enters the ammonia evaporation tower (1); Step 2, ammonia vapor discharged from the top of the ammonia evaporation tower (1) is sent to the ammonia scrubbing tower (2); ammonia evaporation wastewater at the bottom of the ammonia evaporation tower (1) is sent to the wastewater evaporator (5), the fractionation evaporator (6), the condensation evaporator (7) and the ammonia evaporation wastewater heat exchanger (14) through the ammonia evaporation wastewater pump (8); the ammonia evaporation wastewater sent to the ammonia evaporation wastewater heat exchanger (14) is sent to the biochemical device after heat exchange and cooling; The ammonia evaporation wastewater sent to the wastewater evaporator (5), the fractionation evaporator (6) and the condensation evaporator (7) is heat exchanged and vaporized to generate steam which enters the bottom of the ammonia evaporation tower (1) and serves as a desorption heat source for the ammonia evaporation tower (1); Step 3, the ammonia washing tower (2) uses ammonium phosphate solution as an absorption liquid, the ammonia vapor entering the ammonia washing tower (2) is countercurrently contacted with the sprayed ammonium phosphate absorption liquid in the tower, the ammonium phosphate solution absorbs NH3 in the ammonia vapor to generate (NH4)2HPO4, and the secondary steam from which NH3 is removed is discharged from the top of the ammonia washing tower (2); The ammonium phosphate rich liquid at the bottom of the ammonia washing tower (2) is sent to the ammonium phosphate circulating liquid cooler (12) for cooling through 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); The phosphate ammonium rich liquid to be desorbed at the bottom of the ammonia washing tower (2) is sent to the phosphate ammonium rich liquid heat exchanger (13) through the phosphate ammonium feed pump (10) for heat exchange and temperature increase; 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 a 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 in the lower part of the shell side of the wastewater evaporator (5) is pressurized by the wastewater circulation 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 of the tube side through the nozzle, the pressurized secondary steam in the heat exchange tube exchanges heat with the wastewater outside the tube wall, the pressurized secondary steam in the tube condenses into condensed water, and the wastewater on the outer wall of the tube vaporizes to generate steam; the wastewater evaporator (5) discharges steam and enters the ammonia distillation tower (1); The pressurized secondary steam is condensed in the tube, and part of the non-condensable gas in the tube is discharged to the gas system or the incinerator of the acid-making device; Step 6, the ammonium phosphate feed pump (10) delivers the ammonium phosphate rich liquid from the ammonia washing tower (2) to the ammonium phosphate rich liquid heat exchanger (13) for heat exchange with the ammonium phosphate lean liquid, and the heated ammonium phosphate rich liquid enters the upper part of the analytical tower 3; Ammonia gas is discharged from the top of the desorption tower (3) and enters the fractionation evaporator (6); The phosphate ammonium lean liquid at the bottom of the desorption tower (3) is discharged to the phosphate ammonium rich liquid heat exchanger (13), and the phosphate ammonium lean liquid is cooled by heat exchange with the phosphate ammonium rich liquid and discharged to the outlet of the phosphate ammonium circulating liquid pump 9 to mix with the phosphate ammonium circulating liquid and enter the phosphate ammonium circulating liquid cooler (12); Step 7, the ammonia vapor entering the fractionation evaporator (6) is cooled by the ammonia evaporation wastewater, and the condensate generated by the condensation of the ammonia vapor flows back to the desorption tower (3); the ammonia vapor in the shell side of the fractionation evaporator (6) releases heat during the condensation process to increase the temperature and vaporize the ammonia evaporation wastewater in the tube side, and the steam generated by the vaporization of the ammonia evaporation wastewater enters the ammonia evaporation tower (1); The ammonia vapor discharged from the fractionation evaporator (6) enters the condensation evaporator (7); Step 8, the ammonia vapor entering the condensation evaporator (7) is condensed into ammonia water, and the heat released during the condensation of the ammonia vapor vaporizes the ammonia evaporation wastewater, and the steam generated by the vaporization of the ammonia evaporation wastewater enters the bottom of the ammonia evaporation tower (1); 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.

4. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: 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 mmg / M 3 .

5. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: The operating pressure of the desorption tower (3) is 0.65-1.0 MPa (G), the tube-side pressure of the fractionation evaporator (6) is higher than 300-350 kPa (G), and the tube-side operating pressure of the condensation evaporator (7) is higher than 250-300 kPa (G); And / or, the phosphate ammonium concentration in the phosphate ammonium lean solution discharged from the desorption tower (3) is 40-45%, and the NH3:H3PO4 molar ratio in the phosphate ammonium lean solution of the desorption tower is 1.18-1.

23.

6. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: A heater (16) is provided at the bottom of the desorption tower (3), and medium-pressure steam is used to indirectly heat the ammonium phosphate solution at the bottom of the desorption tower (3), and direct steam is added in an appropriate amount as required to maintain the water balance of the system.

7. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: The secondary steam is pressurized by the steam compressor (4), and the pressure of the secondary steam at the outlet of the steam compressor (4) needs to be 40 to 60 kPa higher than the bottom operating pressure of the ammonia distillation tower (1).

8. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: The shell side operating pressure of the wastewater evaporator (5) is 10 to 15 kPa higher than the bottom pressure of the ammonia distillation tower (1).

9. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: The outlet temperature of the phosphate ammonium circulating liquid of the phosphate ammonium circulating liquid cooler (12) is 1 to 2°C lower than the steam temperature of the ammonia washing tower (2).

10. The method for energy-saving and efficient production of concentrated ammonia water from coking surplus ammonia water according to claim 3, characterized in that: The ammonia vapor discharged from the fractionation evaporator (6) enters the condensation evaporator (7), and the NH3 concentration of the ammonia vapor is controlled to be 15-20%; And / or, the shell-side condensate reflux pipe of the fractionating evaporator (6) adopts a stepped discharge method, and the heat exchange area is adjusted by controlling the height of the condensate level on the shell side of the fractionating evaporator (6); the steam pipe pressure regulating valve at the outlet of the tube side of the fractionating 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 regulating means cooperate to control the NH3 concentration of the discharged ammonia vapor to be 15-20%.

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