Scr denitration system

Abstract

The present application relates to the technical fields of SCR denitration, and discloses a kind of SCR denitration system.The system includes gas boiler and SCR denitration device and sequentially connected deaerator, high-pressure heater and economizer;The economizer is arranged in flue, and the flue is provided with gas boiler flue gas inlet, and the flue gas outlet of the flue is connected with the SCR denitration device;The deaerator is connected with the high-temperature hot water outlet provided on the gas boiler;The high-pressure heater is connected with the high-temperature steam outlet provided on the gas boiler.The system can ensure that the purpose of SCR denitration device can be put into operation while the boiler is started, and reduce the content of nitrogen oxides in flue gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of SCR denitration technology, in particular to an SCR denitration system. BACKGROUND

[0002] In recent years, due to the deterioration of the environment, reducing the emission of pollutants is a technical problem that needs to be solved at present. In order to deal with the environmental problems of nitrogen oxides, sulfides and smoke generated by coal-fired power generation, it is required to take relevant measures in industrial production to further reduce the emission of flue gas and reduce the concentration of pollutants. At present, the technology widely used in coal-fired industry is the selective catalytic reduction flue gas denitration method (SCR denitration method), which has the advantages of stable performance, strong load adaptability, etc. It is the mainstream technology for reducing the emission of oxides in the current combustion engine.

[0003] In the SCR denitration technology, the required reaction temperature of the SCR denitration catalyst is 270-420℃. At present, the requirement for deep peak shaving of coal-fired generating units is becoming more and more strict, but the most important factor affecting the participation of power generating units in deep peak shaving is that the flue gas temperature generated by the coal-fired boiler in the initial stage of starting is low, which cannot reach the reaction temperature of the SCR denitration catalyst. At this time, the SCR denitration device cannot operate normally, the emission of nitrogen oxides in the flue gas exceeds the standard, and serious environmental pollution problems are caused.

[0004] With the increasingly strict requirements for environmental emission gases of power generating units at present, it is a common problem faced by all coal-fired power plants to ensure that the SCR denitration system can operate normally during the period from the ignition start of the boiler to the grid connection of the power generating unit. SUMMARY

[0005] The purpose of the present application is to overcome the problem that the flue gas temperature at the inlet of the SCR denitration device is too low during the period from the ignition start of the boiler to the grid connection, which causes the SCR denitration device to be unable to operate normally, and to provide an SCR denitration system that can successfully heat the flue gas generated during the period from the ignition start of the boiler to the grid connection, ensuring that the SCR denitration device can be put into operation at the same time as the boiler is started, reducing the content of nitrogen oxides in the flue gas, and making the emitted tail gas meet the environmental protection standards.

[0006] In order to achieve the above-mentioned purpose, the present application provides an SCR denitration system, which comprises a gas-fired boiler and an SCR denitration device, a deaerator, a high-pressure heater and an economizer connected in sequence.

[0007] The economizer is arranged in the flue, and a gas-fired boiler flue gas inlet is arranged on the flue. The flue gas outlet of the flue is connected with the SCR denitration device.

[0008] The deaerator is connected with the high-temperature hot water outlet arranged on the gas-fired boiler.

[0009] The high-pressure heater is connected with a high-temperature steam outlet provided on the gas boiler.

[0010] The high-temperature hot water from the gas boiler is mixed with water in the deaerator, and the mixed water is delivered to the economizer, the flue gas to be treated is exchanged with the water in the economizer, the exchanged flue gas is mixed with the high-temperature flue gas from the gas boiler, and the mixed gas is delivered to the SCR denitration device for treatment; or

[0011] The high-temperature steam from the gas boiler is exchanged with water in the high-pressure heater, the exchanged water is delivered to the economizer, the flue gas to be treated is exchanged with the water in the economizer, the exchanged flue gas is mixed with the high-temperature flue gas from the gas boiler, and the mixed gas is delivered to the SCR denitration device for treatment.

[0012] Preferably, a solution delivery pump is provided between the high-pressure heater and the gas boiler, for delivering the exchanged steam in the high-pressure heater to the gas boiler for reuse.

[0013] Preferably, a first switching device is provided at the high-temperature hot water outlet of the gas boiler, for adjusting the flow of the high-temperature hot water delivered by the gas boiler to the deaerator.

[0014] Preferably, a second switching device is provided at the high-temperature steam outlet of the gas boiler, for adjusting the flow of the high-temperature steam delivered by the gas boiler to the high-pressure heater.

[0015] Preferably, a third switching device is provided between the solution delivery pump and the gas boiler, for adjusting the flow of the exchanged steam in the high-pressure heater returned to the gas boiler.

[0016] Preferably, the temperature of the flue gas to be treated is 50-250℃.

[0017] Preferably, the temperature of the high-temperature steam is 350-500℃.

[0018] Preferably, the temperature of the high-temperature hot water is 350-450℃.

[0019] Preferably, the temperature of the high-temperature flue gas is 300-600℃,

[0020] Preferably, the flow of the high-temperature flue gas is 100-1000t / h.

[0021] The high-temperature steam or high-temperature hot water generated by the gas boiler in the SCR denitration system of the present application is used to raise the water inlet temperature of the economizer, and then the economizer is used to exchange heat with flue gas to raise the temperature of the flue gas, and then the flue gas is mixed with the high-temperature flue gas generated by the gas boiler to further raise the temperature of the flue gas, and then the heated flue gas is transported to the SCR denitration device for denitration treatment, so that the purpose that the SCR denitration device can be normally put into operation during the period from the ignition start of the boiler to the grid connection of the generator set can be achieved. In the system of the present application, the flue gas of the gas boiler is used as a heat source, which will not pollute the environment with harmful gas, and the starting speed is fast, and after the high-temperature steam in the gas boiler is exchanged and condensed into liquid water, it can be recycled and returned to the gas boiler for reuse, and the high-temperature hot water can enter the water circulation system of the generator set, which will not cause waste of water resources. In addition, the system of the present application does not change the routes and arrangements of the devices in the original generator set, and through the connection of the pipelines, the original devices such as the deaerator, the high-pressure heater and the economizer are given new functions and purposes, and the modification cost is small. In addition, the system of the present application also has multiple operation modes, and the change of the operation mode can be realized by adjusting the switch equipment provided on the pipeline, and the multiple operation modes can all realize the heating of the flue gas to ensure that the boiler ignition and the SCR denitration device are put into operation at the same time, realize the denitration treatment of the low-temperature flue gas, and the system operation is simple and flexible, and has very great application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 FIG. 1 is a schematic diagram of the SCR denitration system of the present application.

[0023] BRIEF DESCRIPTION OF DRAWINGS

[0024] 1 gas boiler; 2 deaerator;

[0025] 3 high-pressure heater; 4 economizer;

[0026] 5 SCR denitration device; 6 flue;

[0027] 7 solution delivery pump. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0029] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint. Any ranges of values disclosed herein are not to be constrained to the exact values recited as the endpoints of the ranges. The endpoints of the ranges and any values are provided as approximations only, and are merely intended to illustrate a range of values. Any numerical values are approximations only. Although the exact values recited will be understood to be approximations by one of ordinary skill in the art, different instances of the same numerical value will typically mean or suggest

[0030] In addition, unless specifically stated otherwise and / or limited by context, the term "connected" is used broadly and can refer to direct or indirect connections, mechanical or electrical connections, direct or indirect coupling or the like, and can include fixedly connected, releasably connected, removably connected, or integrally connected, or the like. The term "connected" can also refer to an element that is in communication with or "connected" to an element, either directly or through intervening elements. The term "connected" is intended to be construed broadly, and can include an element in communication with or "connected" to an element, either directly or through intervening elements.

[0031] In addition, if the present disclosure describes the use of "first" "second" and the like, these designations are only used to assist in the description of the application and are not intended to limit the scope of the application. Thus, the use of "first" "second" and the like is not intended to limit the scope of the application to only two such features. In addition, the technical solutions provided by various embodiments of the present disclosure can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection required by the present disclosure.

[0032] In this paper, the "peak shaving" refers to the load of the generator set adjusting to the fluctuation of the power grid load, and the "deep peak shaving" refers to the load of the generator set adjusting to the fluctuation of the power grid load.

[0033] In this paper, the "grid-connected" refers to the power transmission line of the generator set being connected to the power transmission network, and starting to transmit power outward.

[0034] In combination with reference to Figure 1 The system comprises a gas-fired boiler 1, an SCR denitration device 5, and a deaerator 2, a high-pressure heater 3 and an economizer 4 connected in sequence.

[0035] In the system of the present disclosure, the economizer 4 is arranged in the flue 6, and a gas-fired boiler flue gas inlet is arranged on the flue 6 for inputting high-temperature flue gas generated by the gas-fired boiler 1. The high-temperature flue gas transported into the flue 6 is mixed with the flue gas in the flue 6 to further increase the temperature of the flue gas.

[0036] In a specific embodiment, the gas boiler flue gas inlet is provided with a regulating valve for controlling the flow of high-temperature flue gas from the gas boiler 1 input into the flue 6. Specifically, the regulating valve can be a gas regulating valve.

[0037] In the system of the present application, the flue gas outlet of the flue 6 is connected to the SCR denitration device 5.

[0038] In the system of the present application, the flue gas outlet of the flue 6 is used to deliver the mixed gas to the SCR denitration device 5. Specifically, the high-temperature flue gas delivered by the gas boiler 1 to the flue 6 is mixed with the heat-exchanged flue gas and then delivered to the SCR denitration device 5 for denitration treatment.

[0039] In a specific embodiment, the deaerator 2 is connected to the high-temperature hot water outlet provided on the gas boiler 1, and the high-pressure heater 3 is connected to the high-temperature steam outlet provided on the gas boiler 1. In the system of the present application, the water in the economizer 4 is heated by the high-temperature steam or high-temperature hot water delivered by the gas boiler 1. When the heat transfer medium delivered by the gas boiler 1 is high-temperature steam, the high-temperature steam is delivered to the high-pressure heater 3 to exchange heat with water, and the heat-exchanged water is delivered to the economizer 4 to exchange heat with the flue gas to be treated. When the heat transfer medium delivered by the gas boiler 1 is high-temperature hot water, the high-temperature hot water is delivered to the deaerator 2 to mix with water, and the mixed water is delivered to the economizer 4 to exchange heat with the flue gas to be treated. The heat-exchanged flue gas is mixed with the high-temperature flue gas from the gas boiler 1 to further increase the temperature of the flue gas, and the mixed gas is delivered to the SCR denitration device 5 for treatment. The system of the present application uses two methods to increase the temperature of the flue gas to be treated, thereby realizing the denitration treatment of low-temperature flue gas.

[0040] In the system of the present application, only the economizer 4 is used to exchange heat with the flue gas to be treated, and the water in the economizer 4 cannot exchange enough heat with the flue gas to increase the temperature of the flue gas to be treated to the target temperature. Therefore, the heat-exchanged flue gas needs to be mixed with the high-temperature flue gas generated by the gas boiler 1 to increase the temperature of the flue gas to be treated to the temperature required by the SCR denitration catalyst. Both methods are necessary and are used together to increase the temperature of the flue gas to be treated.

[0041] In the system of the present application, the flue gas to be treated is the flue gas generated by the boiler during the period from the ignition of the boiler to the grid connection of the generator set, and the temperature of the flue gas to be treated is 50-250℃. In the prior art, during the initial start-up of the generator set, the flue gas generated by the ignition of the boiler has a low temperature and cannot reach the required temperature of the SCR denitration catalyst filled in the SCR denitration device 5, so that the SCR denitration device 5 cannot normally start the denitration treatment of the flue gas during the period from the ignition of the boiler to the grid connection of the generator set. In the present application, the present inventors adjust the pipeline connection between the original devices of the generator set, raise the water temperature in the economizer 4 by the high-temperature hot water or high-temperature flue gas provided by the gas-fired boiler 1, and further raise the flue gas temperature by the high-temperature flue gas generated by the gas-fired boiler 1, so as to ensure that the flue gas delivered to the SCR denitration device 5 meets the required temperature of the SCR denitration catalyst, realize the treatment of low-temperature flue gas, and ensure the synchronous operation of the boiler ignition and the SCR denitration device 5.

[0042] In the system of the present application, the heat source of the gas-fired boiler 1 is natural gas, the main component of the high-temperature flue gas generated by the gas-fired boiler 1 is CO2, the temperature of the high-temperature flue gas is 300-600℃, preferably 350-550℃, the amount of the high-temperature flue gas is 100t / h-1000t / h, preferably 300-800t / h, the temperature of the delivered high-temperature steam is 350-500℃, preferably 400-500℃, and the temperature of the delivered high-temperature hot water is 350-450℃, preferably 350-400℃. In the prior art, the gas-fired boiler 1 is used to provide heat source for the generator set. In the present application, the high-temperature hot water or high-temperature steam generated by the gas-fired boiler 1 is used to heat the water in the economizer 4 by adjusting the pipeline, and the flue gas temperature is raised by the heat exchange between the economizer 4 and the flue gas to be treated. In addition, the system of the present application further mixes the high-temperature flue gas generated by the gas-fired boiler 1 with the heat-exchanged flue gas to further raise the flue gas temperature, and fully utilizes the heat energy provided by the gas-fired boiler 1 to heat the flue gas to be treated.

[0043] In a specific embodiment, a high-temperature fan is arranged at the flue gas inlet of the gas-fired boiler, and the high-temperature fan is used to deliver the high-temperature flue gas generated by the gas-fired boiler 1 into the flue 6. Specifically, the high-temperature fan can be a centrifugal fan or a Roots fan.

[0044] In the system of the present application, the economizer 4 is a device commonly used in the art, which can be a light pipe economizer and a finned economizer. The structure is formed by arranging a plurality of pipes according to a certain rule, which can be the structure of the economizer commonly used in the art, and will not be described here. In the prior art, the economizer 4 is usually used to absorb the heat of the flue gas to be treated, and the absorbed heat is used to heat the boiler feed water to achieve the purpose of saving energy. In the present application, based on the original equipment arrangement of the entire generator set, the high-temperature steam in the gas-fired boiler 1 is transported to the high-pressure heater 3 to exchange heat with water, and the water after heat exchange is transported to the economizer 4; or the high-temperature hot water in the gas-fired boiler 1 is transported to the deaerator 2 to mix with water, and the mixed water is transported to the economizer 4, which improves the temperature of the water transported to the economizer 4, thereby using the heat exchange between the economizer 4 and the flue gas to be treated to improve the flue gas temperature, and then using the original equipment in the generator set to heat the flue gas to be treated, which improves the temperature of the flue gas to be treated and saves the cost of system modification.

[0045] In a specific embodiment, there are two ways of heat exchange between the economizer 4 and the flue gas to be treated: when the temperature of the flue gas to be treated is lower than the water temperature in the economizer 4, the heat exchange between the economizer 4 and the flue gas to be treated is that the economizer 4 heats the flue gas to be treated to increase the temperature of the flue gas to be treated; when the temperature of the flue gas to be treated is higher than the water temperature in the economizer 4, the heat exchange between the economizer 4 and the flue gas to be treated is that the water in the economizer 4 absorbs heat from the flue gas to be treated, but since the water temperature in the economizer 4 is higher than the water temperature before heat exchange at this time, the heat absorbed by the economizer 4 from the flue gas to be treated is reduced, thereby increasing the temperature of the flue gas to be treated. In the present application, the temperature of the water in the economizer 4 is improved, thereby reducing the heat absorption of the water in the economizer 4 from the flue gas to be treated to improve the flue gas temperature, and the water in the economizer 4 can also heat the flue gas to be treated to improve the flue gas temperature.

[0046] In a specific embodiment, the system of the present application has two operating modes according to the different heat transfer media output from the gas-fired boiler 1. The first mode is that the high-temperature steam from the gas-fired boiler 1 exchanges heat with water in the high-pressure heater 3, the water after heat exchange is transported to the economizer 4, the flue gas to be treated exchanges heat with the water in the economizer 4, the flue gas after heat exchange mixes with the high-temperature flue gas from the gas-fired boiler 1, and the mixed gas is transported to the SCR denitration device 5 for treatment; the second mode is that the high-temperature hot water from the gas-fired boiler 1 mixes with water in the deaerator 2, the mixed water is transported to the economizer 4, the flue gas to be treated exchanges heat with the water in the economizer 4, the flue gas after heat exchange mixes with the high-temperature flue gas generated by the gas-fired boiler 1, and the mixed gas is transported to the SCR denitration device 5.

[0047] In the first mode, the water in the high-pressure heater 3 comes from the deaerator 2. Specifically, the water from the deaerator 2 is delivered to the high-pressure heater 3, the high-temperature steam from the gas boiler 1 is delivered to the deaerator 3, the high-temperature steam exchanges heat with the water in the high-pressure heater 3, and the exchanged water is delivered to the economizer 4 to exchange heat with the flue gas to be treated.

[0048] In the specific embodiment, the heat transfer medium output from the gas boiler 1 is high-temperature steam or high-temperature hot water, and different operation modes can be adopted according to the heat transfer medium provided in the gas boiler 1, and the two modes can be switched by the valves provided on the pipeline, which is simple to operate.

[0049] In the specific embodiment, the high-temperature hot water outlet of the gas boiler 1 is provided with a first switching device for adjusting the flow of high-temperature hot water delivered by the gas boiler 1 to the deaerator 2, and the high-temperature steam outlet of the gas boiler 1 is provided with a second switching device for adjusting the flow of high-temperature steam delivered by the gas boiler 1 to the high-pressure heater 3. The first switching device can be a device commonly used in the art for controlling the flow of liquid, specifically an automatic regulating valve or an electrically controlled valve; and the second switching device can be a device commonly used in the art for controlling the flow of gas, specifically a gas regulating valve.

[0050] In the preferred embodiment, when the heat transfer medium delivered by the gas boiler 1 is high-temperature steam, the high-temperature steam exchanges heat with the water in the high-pressure heater 3, and the cooled steam is returned to the gas boiler 1 for reuse; when the heat transfer medium delivered by the gas boiler 1 is high-temperature hot water, the high-temperature hot water is mixed with the water in the deaerator 2 and then delivered to the economizer 4 to exchange heat with the flue gas, and the exchanged water enters the water circulation system of the generator set, the high-temperature hot water output by the gas boiler 1 cannot be returned to the gas boiler 1 for reuse after mixing, and at this time, cold water can be delivered from the chemical system provided in the generator set to the gas boiler for supplementing the water in the gas boiler 1.

[0051] In the system, the high-pressure heater 3 is provided with a solution delivery pump 7 for delivering the steam after heat exchange in the high-pressure heater 3 to the gas-fired boiler 1 for reuse. Specifically, the high-temperature steam from the gas-fired boiler 1 is subjected to heat exchange in the high-pressure heater 3 and then condensed into water in the high-pressure heater 3, and then the water after heat exchange of the high-temperature steam is delivered to the gas-fired boiler 1 by the solution delivery pump 7 for reuse. It can be understood that the solution delivery pump 7 delivers the liquid water after heat exchange of the high-temperature steam, and the steam after heat exchange is liquid water.

[0052] In a specific embodiment, the solution delivery pump 7 is provided with a third switching device between the solution delivery pump 7 and the gas-fired boiler 1 for adjusting the flow of the steam after heat exchange in the high-pressure heater 3 to the gas-fired boiler 1, wherein the steam is actually the liquid water after heat exchange and condensation of the high-temperature steam. The third switching device can be a device commonly used in the art for controlling the flow of liquid, specifically, an automatic regulating valve or an electrically controlled valve.

[0053] In the system, the deaerator 2 is a device commonly used in the art for deaerating water and can have a structure commonly used in the art. In the prior art, the deaerator 2 is used for treating boiler feed water, and in the present application, the deaerator 2 is used for mixing with the high-temperature hot water from the gas-fired boiler 1, and the mixed water is delivered to the economizer 4 to exchange heat with the flue gas to be treated to increase the temperature of the flue gas to be treated. In the present application, when the gas-fired boiler 1 delivers high-temperature steam, the deaerator 2 delivers water to the high-pressure heater 3 and exchanges heat with the high-temperature steam delivered to the high-pressure heater 3, and the water after heat exchange is delivered to the economizer 4 to exchange heat with the flue gas to be treated.

[0054] In the system, the high-pressure heater 3 can be a device commonly used in the art. In the prior art, the high-pressure heater 3 is a device for heating feed water by using part of the steam of a steam turbine in a generator set, which is a heat conversion device. The high-pressure heater 3 includes a tube pass and a shell pass. The high-pressure heater 3 delivers steam in the tube pass and water in the shell pass. In the present application, the high-temperature steam from the gas-fired boiler 1 is delivered to the tube pass of the high-pressure heater 3, the water in the shell pass is heated by the high-temperature steam in the tube pass, the heated water is delivered to the economizer 4 to exchange heat with the flue gas to be treated, and the temperature of the flue gas is increased by the heat exchange between the water in the economizer 4 and the flue gas to be treated.

[0055] In the system, when the heat transfer medium output from the gas boiler 1 is high-temperature steam, a double-pipe heat exchanger can be arranged between the high-pressure heater 3 and the economizer 4, the high-temperature steam from the gas boiler 1 is transported into the tube side of the double-pipe heat exchanger, the water from the deaerator 2 is transported into the shell side of the double-pipe heat exchanger after flowing through the high-pressure heater 3, the water in the shell side is heated by the high-temperature steam in the tube side, the heated water is transported into the economizer 4 to exchange heat with the flue gas to be treated, and the high-temperature steam after heat exchange is condensed into water and returned to the gas boiler 1 by the solution delivery pump 7 for reuse.

[0056] In a specific embodiment, when the heat transfer medium output from the gas boiler 1 is high-temperature hot water, the first switch device is opened, and the second switch device and the third switch device are closed, the high-temperature hot water is transported into the deaerator 2 to mix with water, the mixed water is transported into the economizer 4 to exchange heat with the flue gas to be treated after flowing through the shell side of the high-pressure heater 3 in sequence, the flue gas after heat exchange is mixed with the high-temperature flue gas from the gas boiler 1, and the mixed gas is transported into the SCR denitration device 5 for treatment.

[0057] In a specific embodiment, when the heat transfer medium output from the gas boiler 1 is high-temperature steam, the second switch device and the third switch device are opened, and the first switch device is closed, the high-temperature steam is transported into the tube side of the high-pressure heater 3, the water from the deaerator 2 is transported into the shell side of the high-pressure heater 3, the high-temperature steam exchanges heat with the water in the shell side, the heated water is transported into the economizer 4 to exchange heat with the flue gas to be treated, the flue gas after heat exchange is mixed with the high-temperature flue gas from the gas boiler 1, and the mixed gas is transported into the SCR denitration device 5 for treatment; the steam after heat exchange is transported into the gas boiler 1 by the solution delivery pump 7 for reuse.

[0058] In a specific embodiment, when the high-temperature flue gas generated by the gas boiler 1 has a temperature of 500-600℃ and a flow rate of 800-1000t / h, the high-temperature flue gas can be directly mixed with the flue gas to be treated, and the mixed gas is transported into the SCR denitration device 5 for treatment, without the need to heat the water in the economizer 4 by the heat transfer medium in the gas boiler 1 and then heat the flue gas to be treated by the water in the economizer 4 to increase the temperature of the flue gas.

[0059] In a specific embodiment, the first switch device, the second switch device, and the third switch device are closed, the high-temperature flue gas generated by the gas boiler 1 is transported into the flue 6 to mix with the flue gas to be treated, and the mixed gas is transported into the SCR denitration device 5 for treatment.

[0060] In a specific embodiment, when the flow and temperature of the high-temperature flue gas generated by the gas-fired boiler 1 are high, it indicates that the load of the gas-fired boiler 1 is high, and the consumption of natural gas is large. Therefore, based on the consideration of energy, the preferred mode is to use the high-temperature hot water or high-temperature steam conveyed in the gas-fired boiler 1 to heat the water in the economizer 4. The heated water is heat-exchanged with the flue gas to be treated, and the heat-exchanged flue gas is mixed with the high-temperature flue gas generated by the gas-fired boiler 1 to increase the temperature of the flue gas to be treated.

[0061] According to the first specific embodiment of the SCR denitration system, the system comprises a gas-fired boiler 1, an SCR denitration device 5, and an oxygen remover 2, a high-pressure heater 3, and an economizer 4 connected in sequence; the economizer 4 is arranged in a flue 6, the flue 6 is provided with a gas-fired boiler flue gas inlet, and the flue gas outlet of the flue 6 is connected with the SCR denitration device 5; the oxygen remover 2 is connected with the high-temperature hot water outlet provided on the gas-fired boiler 1; the high-pressure heater 3 is connected with the high-temperature hot water outlet provided on the gas-fired boiler 1; the high-temperature hot water from the gas-fired boiler 1 is mixed with water in the oxygen remover 2, the mixed water is conveyed to the economizer 4, the flue gas to be treated is heat-exchanged with the water in the economizer 4, the heat-exchanged flue gas is mixed with the high-temperature flue gas from the gas-fired boiler 1, and the mixed gas is conveyed to the SCR denitration device 5 for treatment; or the high-temperature steam from the gas-fired boiler 1 is heat-exchanged with water in the high-pressure heater 3, the heat-exchanged water is conveyed to the economizer 4, the flue gas to be treated is heat-exchanged with the water in the economizer 4, the heat-exchanged flue gas is mixed with the high-temperature flue gas from the gas-fired boiler 1, and the mixed gas is conveyed to the SCR denitration device 5 for treatment; a solution conveying pump 7 is arranged between the high-pressure heater 3 and the gas-fired boiler 1, which is used to convey the heat-exchanged steam in the high-pressure heater 3 to the gas-fired boiler 1 for reuse; a first switching device is arranged at the high-temperature hot water outlet of the gas-fired boiler 1, which is used to adjust the flow of the high-temperature hot water conveyed from the gas-fired boiler 1 to the oxygen remover 2; a second switching device is arranged at the high-temperature steam outlet of the gas-fired boiler 1, which is used to adjust the flow of the high-temperature steam conveyed from the gas-fired boiler 1 to the high-pressure heater 3.

[0062] According to another specific embodiment of the SCR denitration system, the system comprises a gas-fired boiler 1, an SCR denitration device 5, and a deaerator 2, a high-pressure heater 3, and an economizer 4 connected in sequence; the economizer 4 is arranged in a flue 6, the flue 6 is provided with a gas-fired boiler flue gas inlet, and a flue gas outlet of the flue 6 is connected with the SCR denitration device 5; the deaerator 2 is connected with a high-temperature hot water outlet provided on the gas-fired boiler 1; the high-pressure heater 3 is connected with a high-temperature steam outlet provided on the gas-fired boiler 1; high-temperature hot water from the gas-fired boiler 1 is mixed with water in the deaerator 2, the mixed water is transported to the economizer 4, the flue gas to be treated is heat-exchanged with the water in the economizer 4, the heat-exchanged flue gas is mixed with high-temperature flue gas from the gas-fired boiler 1, and the mixed gas is transported to the SCR denitration device 5 for treatment; or high-temperature steam from the gas-fired boiler 1 is heat-exchanged with water in the high-pressure heater 3, the heat-exchanged water is transported to the economizer 4, the flue gas to be treated is heat-exchanged with the water in the economizer 4, the heat-exchanged flue gas is mixed with high-temperature flue gas from the gas-fired boiler 1, and the mixed gas is transported to the SCR denitration device 5 for treatment; a solution delivery pump 7 is arranged between the high-pressure heater 3 and the gas-fired boiler 1, and is used to transport the heat-exchanged steam in the high-pressure heater 3 to the gas-fired boiler 1 for reuse; a first switching device is arranged at the high-temperature hot water outlet of the gas-fired boiler 1, and is used to adjust the flow of high-temperature hot water from the gas-fired boiler 1 to the deaerator 2; a second switching device is arranged at the high-temperature steam outlet of the gas-fired boiler 1, and is used to adjust the flow of high-temperature steam from the gas-fired boiler 1 to the high-pressure heater 3; and a third switching device is arranged between the solution delivery pump 7 and the gas-fired boiler 1, and is used to adjust the flow of heat-exchanged steam in the high-pressure heater 3 returned to the gas-fired boiler 1.

[0063] The application will be described in detail below through examples, but the protection scope of the application is not limited thereto.

[0064] The following examples are processed by using the following system, and the flowchart of the SCR denitration system is shown in Figure 1 , which comprises a gas-fired boiler 1, an SCR denitration device 5, and a deaerator 2, a high-pressure heater 3, and an economizer 4 connected in sequence; and further comprises a solution delivery pump 7, a first switching device, a second switching device, and a third switching device.

[0065] The economizer 4 is arranged in a flue 6, and the gas-fired boiler 1 is in communication with a gas-fired boiler flue gas inlet of the flue 6.

[0066] A flue gas outlet of the flue 6 is connected with the SCR denitration device 5.

[0067] The deaerator 2 is connected with the high-temperature hot water outlet of the gas boiler 1;

[0068] The high-pressure heater 3 is connected with the high-temperature steam outlet of the gas boiler 1;

[0069] The solution delivery pump 7 is located between the gas boiler 1 and the high-pressure heater 3;

[0070] The high-temperature hot water outlet of the gas boiler 1 is provided with a first switch device;

[0071] The high-temperature steam outlet of the gas boiler 1 is provided with a second switch device;

[0072] The solution delivery pump 7 is provided with a third switch device between the gas boiler 1;

[0073] The gas boiler inlet is provided with an adjusting valve.

[0074] Embodiment 1

[0075] When the heat exchange medium output from the gas boiler 1 is high-temperature hot water, the first switch device is opened, and the second switch device and the third switch device are closed, and the high-temperature hot water (350℃) is delivered into the deaerator 2 to mix with water (temperature 50℃), and the mixed water (temperature 150℃) flows through the high-pressure heater 3 to be delivered into the economizer 4 to exchange heat with the to-be-treated flue gas (temperature 80℃), and the heat-exchanged flue gas (temperature 90℃) mixes with the high-temperature flue gas (temperature 450℃, flow rate 300t / h) from the gas boiler 1 in the flue 6, and the mixed gas (temperature 280℃) is delivered into the SCR denitration device 5 for treatment.

[0076] Embodiment 2

[0077] When the heat exchange medium output from the gas boiler 1 is high-temperature steam, the second switch device and the third switch device are opened, and the first switch device is closed, and the high-temperature steam (temperature 450℃) is delivered into the tube side of the high-pressure heater 3, and the water (temperature 50℃) in the deaerator 2 is delivered into the shell side of the high-pressure heater 3, the high-temperature steam exchanges heat with the water in the shell side of the high-pressure heater 3, the heated water (temperature 200℃) is delivered into the economizer 4 to exchange heat with the to-be-treated flue gas (temperature 50℃), the heat-exchanged flue gas (temperature 120℃) mixes with the high-temperature flue gas (temperature 480℃, flow rate 400t / h) from the gas boiler 1 in the flue 6, and the mixed gas (temperature 320℃) is delivered into the SCR denitration device 5 for treatment; the heat-exchanged high-temperature steam is condensed into water in the high-pressure heater 3, and then the water obtained after heat exchange is delivered into the gas boiler 1 by the solution delivery pump 7 for reuse.

[0078] Comparative Example 1

[0079] The second switch device, the third switch device and the gas boiler flue gas inlet regulating valve are closed, the first switch device is opened, and the high-temperature hot water (temperature 350 DEG C) is delivered to the deaerator 2 to mix with water (temperature 60 DEG C), and the mixed water (temperature 180 DEG C) flows through the high-pressure heater 3 and is delivered to the economizer 4 to exchange heat with the to-be-treated flue gas (temperature 60 DEG C), and the flue gas after heat exchange (temperature 125 DEG C) is delivered to the SCR denitration device 5 for treatment, at this time, the temperature of the flue gas does not meet the use temperature of the SCR denitration catalyst, and the SCR denitration device 5 cannot be started.

[0080] The system can heat the boiler ignition flue gas in multiple ways, the operation mode of the system can be controlled through the switch device arranged on the pipeline, and the flue gas can be heated in each operation mode, so that the boiler ignition and the SCR denitration device can be started at the same time, and in addition, the system does not change the original generator set device connection, and the original device is given a new function through the change of the pipeline, so that the transformation cost is saved, the low-temperature flue gas can be denitration-treated, and the system has great application prospect.

[0081] The above describes the preferred embodiments of the application, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the application and belong to the protection scope of the application.

Claims

1. An SCR De-NOx system characterized by, The system comprises a gas boiler (1) and an SCR denitration device (5), and a deaerator (2), a high-pressure heater (3) and an economizer (4) connected in sequence; The economizer (4) is arranged in a flue (6), the flue (6) is provided with a gas boiler flue gas inlet, and the flue gas outlet of the flue (6) is connected with the SCR denitration device (5); The deaerator (2) is connected with a high-temperature hot water outlet provided on the gas boiler (1), and a first switching device is arranged at the high-temperature hot water outlet of the gas boiler (1) and used for adjusting the flow of high-temperature hot water delivered by the gas boiler (1) to the deaerator (2); The high-pressure heater (3) is connected with a high-temperature steam outlet provided on the gas boiler (1), and a second switching device is arranged at the high-temperature steam outlet of the gas boiler (1) and used for adjusting the flow of high-temperature steam delivered by the gas boiler (1) to the high-pressure heater (3); The high-temperature hot water from the gas boiler (1) is mixed with water in the deaerator (2), the mixed water flows through the high-pressure heater (3) and is then delivered to the economizer (4), the flue gas to be treated is heat-exchanged with the water in the economizer (4), the heat-exchanged flue gas is mixed with the high-temperature flue gas from the gas boiler (1), and the mixed gas is delivered to the SCR denitration device (5) for treatment; or The water from the deaerator (2) is delivered to the high-pressure heater (3), the high-temperature steam from the gas boiler (1) is heat-exchanged with the water in the high-pressure heater (3), the heat-exchanged water is delivered to the economizer (4), the flue gas to be treated is heat-exchanged with the water in the economizer (4), the heat-exchanged flue gas is mixed with the high-temperature flue gas from the gas boiler (1), and the mixed gas is delivered to the SCR denitration device (5) for treatment.

2. The SCR de-NOx system according to claim 1, characterized by, A solution delivery pump (7) is arranged between the high-pressure heater (3) and the gas boiler (1) and used for delivering the heat-exchanged steam in the high-pressure heater (3) to the gas boiler (1) for reuse.

3. The SCR de-NOx system according to claim 2, characterized by, A third switching device is arranged between the solution delivery pump (7) and the gas boiler (1) and used for adjusting the flow of the heat-exchanged steam in the high-pressure heater (3) returned to the gas boiler (1).

4. The SCR de-NOx system according to claim 1, characterized by, The temperature of the flue gas to be treated is 50-250℃.

5. The SCR de-NOx system of claim 1, wherein, The temperature of the high-temperature steam is 350-500℃.

6. The SCR de-NOx system of claim 1, wherein, The temperature of the high-temperature hot water is 350-450℃.

7. The SCR de-NOx system of claim 1, wherein, The temperature of the high-temperature flue gas is 300-600℃.

8. The SCR de-NOx system of claim 1, wherein, The flow of the high-temperature flue gas is 100-1000t / h.

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