Ammonia distillation method for SCR (Selective Catalytic Reduction) system of garbage incinerator

Abstract

The invention discloses an ammonia distillation method for a garbage incinerator SCR (Selective Catalytic Reduction) system. The problems that existing equipment is high in ammonia water steaming energy consumption and inconvenient to control are solved. The method comprises the following steps; the method comprises the following steps: S1, taking a 20-25% concentrated ammonia water solution as a raw material, and filling the concentrated ammonia water solution into a concentrated ammonia water storage tank for storage; s2, conveying 20-25% of concentrated ammonia water solution in a concentrated ammonia water storage tank into an ammonia distillation tower by using a first metering pump; ammonia gas in the concentrated ammonia water solution is separated out by using an ammonia distillation tower and is used for SCR (Selective Catalytic Reduction) denitration reaction; s3, dilute ammonia water generated at the bottom of the ammonia still is pumped out by a second metering pump and conveyed into a dilute ammonia water buffer tank for temporary storage, and the concentration of the dilute ammonia water is below 5%; s4, denitration is completed through a catalyst. The method has the beneficial effects that ammonia for SCR and SNCR in flue gas treatment equipment of the garbage incinerator is combined together, the ammonia still is used for separation and purification, ammonia gas is sprayed into the SCR, and raw materials of a reducing agent, the equipment cost and the operation cost are saved.

Description

Technical Field

[0001] The invention relates to a flue gas purification and denitration treatment suitable for the waste incineration industry, namely, auxiliary ammonia injection equipment of an SCR system, and in particular to an ammonia evaporation method for an SCR system of a waste incinerator. Background Art

[0002] Centralized incineration has gradually become the main method of treating domestic waste in my country. A certain amount of nitrogen oxides - NOx (a general term for nitrogen oxides such as NO, NO2, N2O, N2O3, N2O4, and N2O5) will be produced in the flue gas of the waste incinerator. Among the air pollutants produced by domestic waste incinerators, the purification of NOx is the most difficult and expensive technology, which is determined by the inertness of NO (not easy to react chemically) and its insoluble nature in water. The currently widely used flue gas denitrification treatment technologies are selective catalytic reduction - SCR and selective non-catalytic reduction - SNCR.

[0003] SCR (Selective Catalytic Reduction, abbreviated as SCR) denitrification technology refers to a clean denitrification technology that uses liquid ammonia or ammonia water containing amino groups (NH3) as a reducing agent to selectively reduce nitrogen oxides in flue gas under a certain temperature and catalyst, and generate non-toxic and non-polluting N2 and water. This technology was first applied in oil, gas, and coal-fired power plant boilers in the 1970s. After more than 40 years of promotion and technical research and development, SCR flue gas denitrification technology has now matured internationally, and the denitrification efficiency can reach more than 90%.

[0004] Without adding a catalyst, the reaction temperature of ammonia and nitrogen oxides is 900°C. If a catalyst is added, the reaction temperature can be reduced to 250°C. Figure 1 Attached Figure 1 In the process, the reducing agent NH3 reacts with nitrogen oxides (NO and NO2) on the surface. The catalyst is generally a mixture of V2O5 and WoO3 based on TiO2. The specific formula is determined according to the flue gas parameters.

[0005] In the application of waste incinerators, the commonly used SCR arrangement method is to arrange the SCR reactor downstream of the dust collector and flue gas desulfurization device. Its main feature is that the flue gas entering the reactor has removed a large amount of fly ash, which is not easy to cause catalyst wear. The injection point of ammonia NH3 is on the reactor inlet flue. Due to safety management considerations, ammonia is now mostly obtained by evaporating ammonia water and pyrolyzing urea.

[0006] In the actual use of the existing ammonia evaporation system in waste power plants, since 20% ammonia is directly evaporated, the hot air used to heat the ammonia needs to be heated to above 250°C by electricity first, which requires a large heating power, and the ammonia mixed gas contains a large proportion of water vapor. It is inconvenient to adjust the amount of ammonia evaporation. If the amount is too small, more heat will be wasted. If the amount is too large, it is easy to not evaporate completely, and the mixed gas will contain more droplets, which is easy to cause subsequent corrosion or reduce the denitrification efficiency. Summary of the invention

[0007] In order to solve the problems of high energy consumption and inconvenient control of ammonia evaporation in existing equipment in the background technology, the present invention provides an ammonia evaporation method for a waste incinerator SCR system.

[0008] The technical solution of the present invention is: a method for steaming ammonia for a waste incinerator SCR system, comprising the following steps; S1, using 20-25% concentrated ammonia solution as raw material, the ammonia tank truck uses the unloading pump to add 20-25% concentrated ammonia solution to 40m 3 Store in concentrated ammonia water tank; S2, using the first metering pump to transport the 20-25% concentrated ammonia solution in the concentrated ammonia storage tank to the ammonia evaporation tower; utilizing the different boiling points of ammonia and water, through the process of first heating and then cooling, the ammonia in the concentrated ammonia solution is separated for SCR denitration reaction; S3, the second metering pump extracts the dilute ammonia water produced at the bottom of the ammonia evaporation tower and transports it to the dilute ammonia water buffer tank for temporary storage. The concentration of the dilute ammonia water is below 5%. The ammonia gas produced at the top of the ammonia evaporation tower is injected into the 2m 3 The ammonia gas is cached in the cache tank with a pressure of 1 to 3 bar. After being adjusted by the metering control module, it is transported to the SCR ammonia injection point. S4, the SCR ammonia injection point is selected on the SCR inlet flue, and an SCR ammonia injection grid is installed on the flue. Air is introduced into the ammonia-air mixer. After the ammonia is diluted in the ammonia-air mixer, it is evenly distributed in the SCR reaction chamber through the ammonia injection grid. According to the combustion conditions of the boiler and the NOx content measured in real time in the flue gas, the quality of ammonia is metered and adjusted through the metering control module to achieve the best denitrification effect and realize efficient reduction of NOx in the flue gas. NH3 and NOx react chemically on the surface of the microporous active material of the catalyst to generate N2 and H2O to complete the denitrification.

[0009] As a further improvement of the present invention, each boiler corresponds to a set of metering control modules and an ammonia-air mixer; the ammonia evaporation tower corresponds to multiple boilers.

[0010] As a further improvement of the present invention, in step S3, a dilute ammonia water delivery pump is provided to regularly deliver the dilute ammonia water in the dilute ammonia water buffer tank to the SNCR system, and a pressure transmitter is provided at the outlet to monitor the solution pipeline pressure in real time.

[0011] As a further improvement of the present invention, the first metering pump and the second metering pump share a backup metering pump, and the backup metering pump can be switched by opening and closing a valve.

[0012] As a further improvement of the present invention, in step S2, the concentrated ammonia solution passes through the concentrated ammonia preheater and enters the ammonia distillation tower, forming a liquid pool on the tower plate, which exchanges heat with the ammonia rising from the bottom of the tower to separate the ammonia; when the liquid level of the liquid pool on the upper tower plate is higher than the downcomer, the concentrated ammonia solution falls from the downcomer onto the lower tower plate, thereby achieving the staged falling of the concentrated ammonia solution into the reboiler at the bottom of the tower; in the heat exchange tube of the reboiler at the bottom of the tower, high-temperature steam is passed into the reboiler shell and indirectly heats the ammonia solution through the heat exchange tube, and the ammonia generated in the heat exchange tube rises step by step along the tower plate in the ammonia distillation tower, and after being separated and removed by the condenser at the top of the ammonia distillation tower to remove the contained water vapor, it is discharged from the ammonia distillation tower to be cached in the ammonia cache tank.

[0013] As a further improvement of the present invention, in step S2, when the dilute ammonia water level in the reboiler exceeds the set value, the valve at the circulating liquid discharge port at the bottom of the reboiler is controlled to open automatically for discharge. At this time, the ammonia water in the reboiler is evaporated after multiple cycles, and high-temperature dilute ammonia water with a concentration of less than 5% is discharged; the high-temperature dilute ammonia water is heated by the concentrated ammonia water preheater to heat the concentrated ammonia solution at a low temperature before entering the ammonia evaporation tower, and the temperature of the high-temperature dilute ammonia water is reduced to realize heat recovery and utilization. After being cooled by the dilute ammonia water cooler, it enters the ammonia water buffer tank for storage and can be used by the SNCR system.

[0014] As a further improvement of the present invention, the ammonia still comprises: case; A reboiler is provided in the bottom area of ​​the shell and is used to heat the incoming ammonia water to form ammonia gas; the reboiler is provided with a heat exchange tube for the circulation of the ammonia water; A condenser, arranged in the top area of ​​the shell, for removing water vapor from the ammonia gas; An ammonia outlet is provided at the top of the shell; The ammonia distillation layer is arranged between the reboiler and the condenser; the ammonia distillation layer comprises a tower plate and a downcomer; the shell is provided with a concentrated ammonia mother liquor inlet, and the concentrated ammonia solution entering the concentrated ammonia mother liquor inlet forms a liquid pool on the tower plate; the ammonia gas generated in the reboiler enters the ammonia distillation layer so that the ammonia gas is separated from the water, the ammonia gas is purified and discharged from the ammonia gas outlet through the condenser.

[0015] As a further improvement of the present invention, the ammonia distillation layer has multiple layers, each of which includes the tower plate and the downcomer; the downcomers of two adjacent ammonia distillation layers are staggered; there are multiple concentrated ammonia solution inlets, and the multiple concentrated ammonia solution inlets are arranged in different ammonia distillation layers for balancing the ammonia production and purity.

[0016] As a further improvement of the present invention, different ammonia distillation layers are arranged in a linear manner; when the liquid level of the liquid pool of the upper ammonia distillation layer is higher than the end of the downcomer, the concentrated ammonia water of this layer falls from the downcomer to the tower plate of the lower ammonia distillation layer; when the liquid level of the liquid pool of the lowest ammonia distillation layer is higher than the end of the downcomer, the concentrated ammonia water of this layer falls from the downcomer to the reboiler; the downcomer includes a downcomer plate and an arc plate; the downcomer plate is arranged close to one side of the tower plate, and the upper surface of the downcomer plate is provided with a wave shape that bends back and forth.

[0017] As a further improvement of the present invention, a labyrinth structure is provided inside the ammonia buffer tank, so that the ammonia in the ammonia evaporation tower passes through the labyrinth structure, so that the ammonia needs to bend back and forth to enter, and the ammonia finally enters the upper area of ​​the ammonia buffer tank. The water vapor in the ammonia falls on the inner wall of the labyrinth structure and falls into the bottom of the ammonia buffer tank, thereby separating the ammonia and the water vapor.

[0018] The beneficial effects of the present invention are as follows: 20-25% ammonia aqueous solution is used as a reducing agent raw material, and the ammonia gas in the ammonia aqueous solution is separated for SCR denitration reaction by a process of first heating and then cooling, utilizing the different boiling points of ammonia gas and water; the SCR and SNCR ammonia in the flue gas treatment equipment of the garbage incinerator are combined together, and the ammonia gas is sprayed into the SCR and the dilute ammonia aqueous solution is sprayed into the SNCR by separation and purification using an ammonia evaporation tower, thereby saving reducing agent raw materials, equipment costs, and operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Attached Figure 1 Schematic diagram of the reaction mechanism of ammonia and nitrogen oxides when a catalyst is added in the prior art.

[0020] Attached Figure 2 This is a schematic diagram of the main process of the existing commonly used SCR arrangement for flue gas denitrification.

[0021] Attached Figure 3 It is a schematic diagram of the main process of existing ammonia evaporation.

[0022] Attached Figure 4 The figure is a schematic diagram of the ammonia distillation process according to an embodiment of the present invention.

[0023] Attached Figure 5 It is a schematic structural diagram of an embodiment of the present invention.

[0024] Attached Figure 6 It is a schematic cross-sectional structural diagram of an embodiment of the present invention.

[0025] Attached Figure 7 It is a schematic diagram of the structure of the reboiler according to an embodiment of the present invention.

[0026] Attached Figure 8 It is a schematic structural diagram of a condenser according to an embodiment of the present invention.

[0027] Attached Fig. 9 It is a schematic diagram of the structure of the multi-layer ammonia evaporation layer in the embodiment of the present invention.

[0028] Attached Fig.10 It is a schematic structural diagram of a single-layer ammonia evaporation layer according to an embodiment of the present invention.

[0029] Attached Fig.11 For attachment Fig.10 Schematic diagram of the structure in the other direction.

[0030] Attached Fig.12 It is a schematic diagram of the structure of an ammonia buffer tank according to an embodiment of the present invention.

[0031] In the figure, 1. shell; 11. ammonia outlet; 12. concentrated ammonia solution inlet; 13. high-temperature steam inlet; 14. condensed water outlet; 15. circulating liquid outlet; 16. cooling water inlet; 17. cooling water outlet; 2. reboiler; 21. heat exchange tube; 3. condenser; 4. ammonia evaporation layer; 41. tower plate; 42. downcomer; 421. downcomer plate; 422. curved plate; 5. ammonia buffer tank; 51. labyrinth structure. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are further described below in conjunction with the accompanying drawings: Depend on Figure 4-12 As shown, a method for steaming ammonia for a waste incinerator SCR system comprises the following steps; S1, using 20-25% concentrated ammonia solution as raw material, the ammonia tank truck uses the unloading pump to add 20-25% concentrated ammonia solution to 40m 3 Store in concentrated ammonia water tank; S2, using the first metering pump to transport the 20-25% concentrated ammonia solution in the concentrated ammonia storage tank to the ammonia evaporation tower; utilizing the different boiling points of ammonia and water, through the process of first heating and then cooling, the ammonia in the concentrated ammonia solution is separated for SCR denitration reaction; S3, the second metering pump extracts the dilute ammonia water produced at the bottom of the ammonia evaporation tower and transports it to the dilute ammonia water buffer tank for temporary storage. The concentration of the dilute ammonia water is below 5%. The ammonia gas produced at the top of the ammonia evaporation tower is injected into the 2m 3 The ammonia gas is cached in the cache tank with a pressure of 1 to 3 bar. After being adjusted by the metering control module, it is transported to the SCR ammonia injection point. S4, the SCR ammonia spraying point is selected on the SCR inlet flue, and the flue is provided with an SCR ammonia spraying grid. Air is introduced into the ammonia-air mixer, and the ammonia is diluted in the ammonia-air mixer and then evenly distributed in the SCR reaction chamber through the ammonia spraying grid; according to the combustion conditions of the boiler and the NOx content measured in real time in the flue gas, the quality of ammonia is metered and adjusted through the metering control module to achieve the best denitration effect, and realize the efficient reduction of NOx in the flue gas. NH3 and NOx react chemically on the surface of the microporous active material of the catalyst to generate N2 and H2O to complete denitration. The beneficial effect of the present invention is that 20-25% ammonia solution is used as the reducing agent raw material, and the boiling points of ammonia and water are different. Through the process of heating first and then cooling, the ammonia in the ammonia water is separated for SCR denitration reaction; at the same time, the ammonia wastewater, i.e., dilute ammonia water, is supplied to the SNCR system for use, so as to achieve the secondary utilization of ammonia water, reduce production costs and environmental protection costs, and achieve the purpose of energy saving and emission reduction. The SCR and SNCR ammonia in the flue gas treatment equipment of the waste incinerator are combined together, separated and purified by using an ammonia evaporator, and the ammonia gas is sprayed into the SCR and the dilute ammonia water is sprayed into the SNCR, saving the reducing agent raw materials, equipment costs and operating costs.

[0033] Specifically, in the present invention Unloading pump: used to add the concentrated ammonia solution provided by the supplier from the tank truck into the concentrated ammonia storage tank; Concentrated ammonia storage tank: used to store the purchased concentrated ammonia solution (concentrated ammonia mother liquor) raw materials, which is equipped with a float type liquid level switch and a static pressure liquid level gauge to monitor the solution level in real time; Dilute ammonia solution buffer tank: used to buffer the dilute ammonia solution produced by the ammonia distillation tower. It is equipped with a float type liquid level switch and a static pressure liquid level gauge to monitor the solution level in real time.

[0034] The first metering pump, the second metering pump and the spare metering pump are used to transport concentrated ammonia solution raw materials to the ammonia evaporation tower and to transport the dilute ammonia solution produced by the ammonia evaporation tower to the dilute ammonia solution buffer tank for cache. An electromagnetic flowmeter is installed on the delivery pipeline to measure the solution flow.

[0035] Ammonia buffer tank: used to buffer the ammonia produced by the ammonia distillation tower. The interior of the tank is designed with a maze structure to separate the ammonia and water vapor. It is equipped with a safety valve, a pressure transmitter, and a magnetic flap level gauge with remote electrical signals to monitor the ammonia pressure and the solution level at the bottom of the tank in real time.

[0036] Ammonia still: used to separate ammonia gas and water in ammonia water, and produce ammonia gas and dilute ammonia solution. The ammonia still adopts a sieve plate distillation tower, and the specially designed plates ensure the high efficiency and energy saving of ammonia production. The reboiler is located at the bottom of the tower for steam heating of ammonia water, and the condenser is located at the top of the tower for circulating cooling water to condense and separate the ammonia gas and water vapor mixture.

[0037] Dilution fan, air mixer, ammonia spray grid: used to dilute ammonia and mix ammonia and flue gas evenly, which is more conducive to catalytic denitrification reaction.

[0038] Dilute ammonia water delivery pump: used to regularly deliver the dilute ammonia water in the dilute ammonia water buffer tank to the SNCR system. A pressure transmitter is set at the outlet to monitor the solution pipeline pressure in real time.

[0039] Metering control module: It consists of a distribution valve, a mass flow meter, a regulating valve, and a pressure transmitter, and is used to distribute, regulate, and monitor the quality of the ammonia reducing agent input into each furnace SCR.

[0040] PLC controller, temperature and pressure instruments: used to control the operation and function switching of each device, ensure the normal operation of pumps and valves, and realize automatic and stable operation of the system.

[0041] NOx detection and control: including nitrogen oxide and ammonia analyzers, used to detect NOx content and ammonia escape to ensure that the system meets the design indicators.

[0042] The present invention also has the following benefits: The present invention uses 20-25% ammonia aqueous solution as the reducing agent raw material, which is safer and more reliable than using liquid ammonia, and there is no need to be careful about the risk caused by liquid ammonia leakage; This process uses an ammonia evaporator to purify ammonia, reducing the amount of water vapor injected into the SCR. It uses single or double extraction steam for heating, with low heating power and low energy consumption. The ammonia supply is stable and adjustable, which improves the utilization efficiency of the reducing agent and effectively ensures that nitrogen oxides (NOx) meet emission standards. The combination of ammonia buffer tank, regulation control module, ammonia-air mixer and dilution fan reduces the heating of dilution air, and the system structure is simple and the cost is low. This process adopts modular design, is easy to install, and has a high degree of automation. It realizes complete unattended operation, automatic adjustment, and automatic operation. The system equipment can be maintained faster and more conveniently, reducing system downtime. By utilizing the process of the present invention, the SCR and SNCR ammonia in the flue gas treatment equipment of the garbage incinerator are combined together, and the ammonia gas is sprayed into the SCR and the dilute ammonia water is sprayed into the SNCR by using an ammonia evaporation tower for separation and purification, thereby saving reducing agent raw materials, equipment costs and operating costs.

[0043] Each boiler corresponds to a set of metering control modules and ammonia-air mixers; the ammonia evaporation tower corresponds to multiple boilers. This reduces equipment costs, and the ammonia evaporation tower can correspond to multiple boilers.

[0044] In step S3, a dilute ammonia water delivery pump is provided to regularly deliver the dilute ammonia water in the dilute ammonia water buffer tank to the SNCR system, and a pressure transmitter is provided at the outlet to monitor the solution pipeline pressure in real time. Such a structure reasonably utilizes the dilute ammonia water solution and reduces production costs.

[0045] The first metering pump and the second metering pump share a backup metering pump, and the backup metering pump can be switched by turning on and off the valve. In this way, even if the metering pump is damaged, the system can still work as a whole, improving efficiency and safety.

[0046] In step S2, the concentrated ammonia solution passes through the concentrated ammonia preheater and enters the ammonia distillation tower, where a liquid pool is formed on the tower plate, and heat is exchanged with the ammonia rising from the bottom of the tower to separate the ammonia. When the liquid level of the liquid pool on the upper tower plate is higher than the downcomer, the concentrated ammonia solution falls from the downcomer onto the lower tower plate, thereby achieving graded concentrated ammonia solution falling into the reboiler at the bottom of the tower. In the heat exchange tube of the reboiler at the bottom of the tower, high-temperature steam is passed into the reboiler shell and indirectly heats the ammonia solution through the heat exchange tube. The ammonia generated in the heat exchange tube rises step by step along the tower plate in the ammonia distillation tower, and after being separated and removed by the condenser at the top of the ammonia distillation tower to remove the contained water vapor, it is discharged from the ammonia distillation tower to be cached in the ammonia buffer tank.

[0047] In step S2, when the dilute ammonia water level in the reboiler exceeds the set value, the valve at the circulating liquid drain port at the bottom of the reboiler is controlled to open automatically for drainage. At this time, the ammonia water in the reboiler is evaporated after multiple cycles, and high-temperature dilute ammonia water with a concentration of less than 5% is discharged; the high-temperature dilute ammonia water is heated by the concentrated ammonia water preheater to heat the low-temperature concentrated ammonia water before entering the ammonia evaporation tower, and at the same time, the temperature of the high-temperature dilute ammonia water is reduced to achieve heat recovery and utilization. After being cooled by the dilute ammonia water cooler, it enters the ammonia water buffer tank for storage and can be used by the SNCR system. In this way, the ammonia evaporation tower can be reasonably used to produce ammonia gas and purify ammonia gas. The ammonia still comprises: Shell 1; The reboiler 2 is arranged at the bottom area of ​​the shell 1 and is used to heat the incoming ammonia water to form ammonia gas; the reboiler 2 is provided with a heat exchange tube 21 for the circulation of the ammonia water; The condenser 3 is arranged in the top area of ​​the shell 1 and is used to remove water vapor from the ammonia gas; An ammonia outlet 11 is provided at the top of the housing 1; The ammonia evaporation layer 4 is arranged between the reboiler 2 and the condenser 3; the ammonia evaporation layer 4 includes a tower plate 41 and a downcomer 42; the shell 1 is provided with a concentrated ammonia solution inlet 12, and the concentrated ammonia solution entering the concentrated ammonia solution inlet 12 forms a liquid pool on the tower plate 41; the ammonia gas generated in the reboiler 2 enters the ammonia evaporation layer 4 so that the ammonia gas is separated from the water, the ammonia gas is purified, and the ammonia gas is discharged from the ammonia outlet 11 through the condenser 3. The beneficial effect of the present invention is that the reboiler, the ammonia evaporation layer, and the condenser are arranged in the shell to form an integrated structure, which reduces the pipeline connection and greatly simplifies the structure. The ammonia water is heated by the reboiler to form ammonia gas, and then the ammonia gas is discharged through the ammonia evaporation layer, which improves the ammonia production efficiency, has low energy consumption, and is suitable for the rapid production of a small amount of gas in a garbage power plant. Specifically, a thermometer interface, a pressure gauge interface, and a liquid level gauge interface are provided at the reboiler and the condenser. In this way, a thermometer, a pressure gauge, or a liquid level gauge can be installed as needed, which is convenient for understanding the situation in the ammonia evaporation tower, convenient for precise control, and reduces energy consumption. Further explanation in combination with the product structure: concentrated ammonia solution enters the ammonia layer of the ammonia evaporation tower from the side of the concentrated ammonia solution inlet, forms a liquid pool on the tower plate, exchanges heat with the ammonia rising from the bottom of the tower, and separates the ammonia; when the liquid level of the liquid pool on the upper tower plate is higher than the downcomer, the concentrated ammonia solution falls from the downcomer onto the lower tower plate, thereby achieving the classification of concentrated ammonia solution, and finally falls into the reboiler at the bottom of the tower. In the heat exchange tube of the reboiler at the bottom of the tower, high-temperature steam enters the reboiler shell through the warm steam inlet and indirectly heats the ammonia solution through the heat exchange tube. The ammonia generated in the heat exchange tube rises step by step along the tower plate in the ammonia evaporation tower, and is separated and removed by the condenser at the top of the ammonia evaporation tower after the contained water vapor is removed, and then discharged from the ammonia evaporation tower. Although there are holes for steam to pass through the tower plate, in actual use, the high-pressure ammonia below keeps rising, so the concentrated ammonia solution will not fall directly from the holes on the upper tower plate to the lower tower plate. After adjustment and metering, it goes to the flue gas purification and denitrification treatment system; the clean condensed water generated by the high-temperature steam in the reboiler is discharged from the steam condensed water outlet; when the dilute ammonia water level in the reboiler exceeds the set value, the valve at the circulating liquid drain port at the bottom of the reboiler will be controlled to open automatically for drainage. At this time, the ammonia water in the reboiler is evaporated after multiple cycles, and the high-temperature dilute ammonia water with a concentration of less than 5% is discharged. The high-temperature dilute ammonia water is heated by the concentrated ammonia water preheater to heat the concentrated ammonia water solution, so that the low-temperature concentrated ammonia water is heated before entering the ammonia evaporation tower, and the temperature of the high-temperature dilute ammonia water is reduced to achieve heat recovery and utilization; it is then cooled by the dilute ammonia water cooler and stored in the ammonia water storage tank for use by the SNCR system. This ammonia evaporation system uses water vapor to indirectly heat ammonia gas, and the obtained ammonia evaporation wastewater is dilute ammonia water with a concentration of less than 5%, which can be used by the SNCR system, achieving the secondary utilization of ammonia water and reducing production costs and environmental protection costs. The high-temperature dilute ammonia solution after ammonia evaporation is used to exchange heat with the concentrated ammonia solution. There is no need to set up a heater to heat the concentrated ammonia solution, and its temperature also meets the temperature required for entering the ammonia evaporation tower; the high-temperature dilute ammonia solution is cooled once here, and the demand for cooling water is reduced when the cooler performs secondary cooling, thereby fully utilizing energy and reducing water resource waste.

[0048] The ammonia distillation layer 4 has multiple layers, and each layer of the ammonia distillation layer 4 includes the tower plate 41 and the downcomer 42; the downcomers 42 of two adjacent layers of the ammonia distillation layer 4 are staggered. This makes it easy for the concentrated ammonia solution in the upper liquid pool to fall into the adjacent lower mother liquid, which is easy to control and can achieve separation and purification of ammonia and water.

[0049] There are multiple concentrated ammonia solution inlets 12, and the multiple concentrated ammonia solution inlets 12 are arranged in different ammonia evaporation layers 4 for balancing the ammonia production and purity. Specifically, there are three concentrated ammonia solution inlets, and the three concentrated ammonia solution inlets are convenient for balancing the ammonia production and purity, which is convenient for users to accurately control and reduce energy consumption.

[0050] Different ammonia distillation layers 4 are arranged linearly; when the liquid level of the liquid pool of the upper ammonia distillation layer 4 is higher than the end of the downcomer 42, the concentrated ammonia water of this layer falls from the downcomer 42 onto the tray 41 of the lower ammonia distillation layer 4; when the liquid level of the liquid pool of the lowest ammonia distillation layer 4 is higher than the end of the downcomer 42, the concentrated ammonia water of this layer falls from the downcomer 42 into the reboiler 2. This makes it easy for the concentrated ammonia water solution in the upper liquid pool to fall into the adjacent lower mother liquor, which is easy to control and can achieve separation and purification of ammonia gas and water.

[0051] The downcomer 42 includes a downcomer plate 421 and an arc plate 422; the downcomer plate 421 is arranged on one side close to the tower plate 41, and the upper surface of the downcomer plate 421 is provided with a wave shape that bends back and forth. Specifically, the downcomer plate 421 separates the downcomer 42 from the tower plate 41, and the area ratio of the downcomer 42 to the pedal is 1 / 6-1 / 5. In this way, the area of ​​the liquid pool is larger, which is convenient for heat exchange between ammonia gas and concentrated ammonia water, separation of ammonia gas, and separation and purification of ammonia gas.

[0052] There are multiple heat exchange tubes 21, and three heat exchange tubes 21 that are not on the same straight line are arranged in an equilateral triangle, and the ammonia water moves from bottom to top in the heat exchange tubes 21. In this way, the reboiler has high heat exchange efficiency, saves energy consumption, and reduces costs.

[0053] The present invention also includes: A high-temperature steam inlet 13 is provided at the bottom area of ​​the shell 1 and is used for high-temperature steam to enter and heat the ammonia water in the reboiler 2 to generate ammonia gas; The condensed water outlet 14 is provided at the bottom area of ​​the shell 1 for discharging condensed water, and the high temperature steam inlet 13 is provided above the condensed water outlet 14. This makes it easy to heat the reboiler and generate ammonia, and at the same time, it can realize the reuse of heat and reduce energy consumption.

[0054] The present invention further comprises a circulating liquid discharge port 15, which is arranged at the bottom of the shell 1 and below the reboiler 2. In this way, when the liquid level of ammonia water (dilute ammonia water, with a low concentration) in the reboiler exceeds a set value, the valve at the circulating liquid discharge port at the bottom of the reboiler is controlled to open automatically for discharge. At this time, the ammonia water in the reboiler is evaporated through multiple cycles, and high-temperature dilute ammonia water with a concentration of less than 5% is discharged.

[0055] The present invention further comprises a cooling water inlet 16 and a cooling water outlet 17, which cooperate with each other to remove water vapor in the ammonia gas in the condenser, and the cooling water outlet 17 is arranged above the cooling water inlet 16. This facilitates the re-condensation of water vapor in the discharged ammonia gas to further purify the ammonia gas.

[0056] The ammonia buffer tank 5 is provided with a labyrinth structure 51, so that the ammonia in the ammonia evaporation tower passes through the labyrinth structure 51, so that the ammonia needs to bend back and forth to enter, and the ammonia finally enters the upper area of ​​the ammonia buffer tank 5, and the water vapor in the ammonia falls on the inner wall of the labyrinth structure 51 and falls into the bottom of the ammonia buffer tank 5, so that the ammonia and the water vapor are separated. The purified ammonia bends back and forth in the labyrinth structure of the ammonia buffer tank, and reaches the upper area of ​​the ammonia buffer tank, and the water vapor in the ammonia is further condensed, so that the ammonia and the water vapor are separated.

[0057] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "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 or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0059] Technical personnel should note that: Although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention, and any modification using the inventive concept will be included in the scope of protection of the patent right of the present invention.

Claims

1. A method for steaming ammonia for a waste incinerator SCR system, characterized in that : Includes the following steps; S1, using 20-25% concentrated ammonia solution as raw material, the ammonia tank truck uses the unloading pump to add 20-25% concentrated ammonia solution to 40m 3 Store in concentrated ammonia water tank; S2, using the first metering pump to transport the 20-25% concentrated ammonia solution in the concentrated ammonia storage tank to the ammonia evaporation tower; utilizing the different boiling points of ammonia and water, through the process of first heating and then cooling, the ammonia in the concentrated ammonia solution is separated for SCR denitration reaction; S3, the second metering pump extracts the dilute ammonia water produced at the bottom of the ammonia evaporation tower and transports it to the dilute ammonia water buffer tank for temporary storage. The concentration of the dilute ammonia water is below 5%. The ammonia gas produced at the top of the ammonia evaporation tower is injected into the 2m 3 The ammonia gas is cached in the cache tank with a pressure of 1 to 3 bar. After being adjusted by the metering control module, it is transported to the SCR ammonia injection point. S4, the SCR ammonia injection point is selected on the SCR inlet flue, and an SCR ammonia injection grid is installed on the flue. Air is introduced into the ammonia-air mixer. After the ammonia is diluted in the ammonia-air mixer, it is evenly distributed in the SCR reaction chamber through the ammonia injection grid. According to the combustion conditions of the boiler and the NOx content measured in real time in the flue gas, the quality of ammonia is metered and adjusted through the metering control module to achieve the best denitrification effect and realize efficient reduction of NOx in the flue gas. NH3 and NOx react chemically on the surface of the microporous active material of the catalyst to generate N2 and H2O to complete the denitrification.

2. The method for distilling ammonia for a waste incinerator SCR system according to claim 1, characterized in that Each boiler corresponds to a set of metering control modules and an ammonia-air mixer; the ammonia evaporation tower corresponds to multiple boilers.

3. The method for distilling ammonia for a waste incinerator SCR system according to claim 1, characterized in that In step S3, a dilute ammonia water delivery pump is provided to regularly deliver the dilute ammonia water in the dilute ammonia water buffer tank to the SNCR system, and a pressure transmitter is provided at the outlet to monitor the solution pipeline pressure in real time.

4. The method for distilling ammonia for a waste incinerator SCR system according to claim 1, characterized in that The first metering pump and the second metering pump share a backup metering pump, and the backup metering pump can be switched by opening and closing the valve.

5. The method for distilling ammonia for a waste incinerator SCR system according to claim 1, characterized in that In step S2, the concentrated ammonia solution passes through the concentrated ammonia preheater and enters the ammonia distillation tower, where a liquid pool is formed on the tower plate, and heat is exchanged with the ammonia rising from the bottom of the tower to separate the ammonia. When the liquid level of the liquid pool on the upper tower plate is higher than the downcomer, the concentrated ammonia solution falls from the downcomer onto the lower tower plate, thereby achieving graded concentrated ammonia solution falling into the reboiler at the bottom of the tower. In the heat exchange tube of the reboiler at the bottom of the tower, high-temperature steam is passed into the reboiler shell and indirectly heats the ammonia solution through the heat exchange tube. The ammonia generated in the heat exchange tube rises step by step along the tower plate in the ammonia distillation tower, and after being separated and removed by the condenser at the top of the ammonia distillation tower to remove the contained water vapor, it is discharged from the ammonia distillation tower to be cached in the ammonia buffer tank.

6. The method for distilling ammonia for a waste incinerator SCR system according to claim 5, characterized in that In step S2, when the liquid level of dilute ammonia water in the reboiler exceeds the set value, the valve at the circulating liquid discharge port at the bottom of the reboiler is controlled to open automatically for discharge. At this time, the ammonia water in the reboiler is evaporated after multiple cycles, and high-temperature dilute ammonia water with a concentration of less than 5% is discharged; the high-temperature dilute ammonia water is heated by the concentrated ammonia water preheater to heat the concentrated ammonia solution at a low temperature before entering the ammonia evaporation tower, and at the same time, the temperature of the high-temperature dilute ammonia water is reduced to realize heat recovery and utilization. After being cooled by the dilute ammonia water cooler, it enters the ammonia water buffer tank for storage and can be used by the SNCR system.

7. The method for distilling ammonia for a waste incinerator SCR system according to claim 1, characterized in that The ammonia still comprises: Housing (1); A reboiler (2) is arranged in the bottom area of ​​the shell (1) and is used to heat the incoming ammonia water to form ammonia gas; the reboiler (2) is provided with a heat exchange tube (21) for circulating the ammonia water; A condenser (3) is disposed in the top region of the shell (1) and is used to remove water vapor from the ammonia gas; An ammonia outlet (11) is provided at the top of the shell (1); An ammonia evaporation layer (4) is provided between the reboiler (2) and the condenser (3); the ammonia evaporation layer (4) comprises a tower plate (41) and a downcomer (42); the shell (1) is provided with a concentrated ammonia mother liquor inlet (12), and the concentrated ammonia solution entering through the concentrated ammonia mother liquor inlet (12) forms a liquid pool on the tower plate (41); ammonia gas generated in the reboiler (2) enters the ammonia evaporation layer (4) so ​​that the ammonia gas is separated from water, the purified ammonia gas is discharged from the ammonia gas outlet (11) through the condenser (3).

8. The method for distilling ammonia for a waste incinerator SCR system according to claim 7, characterized in that The ammonia distillation layer (4) has multiple layers, each of which comprises the tower plate (41) and the downcomer (42); the downcomers (42) of two adjacent ammonia distillation layers (4) are staggered; there are multiple concentrated ammonia solution inlets (12), which are arranged in different ammonia distillation layers (4) for balancing the ammonia production and purity.

9. The method for distilling ammonia for a waste incinerator SCR system according to claim 8, characterized in that Different ammonia distillation layers (4) are arranged in a linear manner; when the liquid level of the liquid pool of the upper ammonia distillation layer (4) is higher than the end of the downcomer (42), the concentrated ammonia water of this layer falls from the downcomer (42) onto the tower plate (41) of the lower ammonia distillation layer (4); when the liquid level of the liquid pool of the lowest ammonia distillation layer (4) is higher than the end of the downcomer (42), the concentrated ammonia water of this layer falls from the downcomer (42) into the reboiler (2); the downcomer (42) comprises a downcomer plate (421) and an arc plate (422); the downcomer plate (421) is arranged close to one side of the tower plate (41), and the upper surface of the downcomer plate (421) is provided with a wave shape that bends back and forth.

10. The method for distilling ammonia for a waste incinerator SCR system according to claim 1, characterized in that The ammonia buffer tank (5) is provided with a labyrinth structure (51) in the tank, so that the ammonia in the ammonia evaporation tower passes through the labyrinth structure (51), so that the ammonia needs to bend back and forth to enter, and the ammonia finally enters the upper area of ​​the ammonia buffer tank (5). The water vapor contained in the ammonia falls on the inner wall of the labyrinth structure (51) and falls into the bottom of the ammonia buffer tank (5), thereby separating the ammonia and the water vapor.

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