Scr denitration system

Abstract

The application relates to the field of SCR denitration technology and discloses an SCR denitration system. The system comprises a heat storage unit, an economizer, a high-pressure heater and an SCR denitration device; the economizer is arranged in a flue, a bypass flue gas outlet of the flue is in communication with a flue gas inlet of a bypass flue, and a flue gas outlet of the bypass flue is connected with the SCR denitration device; a heat exchange pipe is arranged in the bypass flue; the heat storage unit is connected with the high-pressure heater and the heat exchange pipe; the SCR denitration system can heat the to-be-processed flue gas, realizes denitration treatment of low-temperature flue gas, and guarantees normal operation of the SCR denitration device when the boiler is ignited.

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 environmental problems, reducing the emission of industrial pollutants is a technical problem that needs to be solved at present. The flue gas discharged by coal chemical industry contains a large amount of nitrogen oxides, and removing nitrogen oxides from flue gas has important practical significance for preventing air pollution.

[0003] The mainstream technology for removing nitrogen oxides in flue gas at present is SCR denitration method, which is the most mature flue gas denitration technology. This method has high denitration efficiency and relatively low price, and is widely used in domestic and foreign engineering, becoming the mainstream technology of flue gas denitration of generator set. In the SCR denitration technology, the required reaction temperature of the SCR denitration catalyst is 270-420 DEG C.

[0004] At present, in order to save energy, the requirement for deep peak regulation of coal-fired unit is more and more strict, and it is required that the SCR denitration device needs to be in normal operation when the generator set is connected to the grid. However, during the initial stage of boiler ignition and start of the generator set, the temperature of the flue gas produced by combustion is low, and cannot reach the reaction temperature of the SCR denitration catalyst. At this time, the SCR denitration device cannot operate normally, and cannot carry out denitration treatment on the flue gas, which will cause a certain degree of environmental pollution. SUMMARY

[0005] The purpose of the present application is to overcome the problems in the prior art that the flue gas temperature produced during the period from the initial stage of boiler ignition and start to the connection of generator set is low, which causes the SCR denitration device to be unable to operate normally, and to provide an SCR denitration system. The SCR denitration system can heat the flue gas to be treated, realize the denitration treatment of low-temperature flue gas, and ensure the normal operation of the SCR denitration device during the initial stage of boiler ignition.

[0006] In order to achieve the above purpose, the present application provides an SCR denitration system, which comprises a heat storage unit, an economizer, a high-pressure heater and an SCR denitration device.

[0007] The economizer is arranged in the flue, the bypass flue gas outlet of the flue is communicated with the flue gas inlet of the bypass flue, and the flue gas outlet of the bypass flue is connected with the SCR denitration device.

[0008] The bypass flue is provided with a heat exchange pipe;

[0009] The heat storage unit is connected with the high-pressure heater and the heat exchange pipe, respectively.

[0010] The high-temperature steam from the heat storage unit is transported into the high-pressure heater to exchange heat with water, the water after heat exchange is transported into the economizer, the flue gas to be treated exchanges heat with the water in the economizer, the flue gas after heat exchange further exchanges heat with the high-temperature steam from the heat storage unit in the heat exchange pipe, and the flue gas after further heat exchange is transported into the SCR denitration device for treatment.

[0011] Preferably, the system further comprises a deaerator connected with the high-pressure heater and the heat exchange pipe respectively.

[0012] The steam after heat exchange in the heat exchange pipe is condensed and transported into the deaerator.

[0013] The steam after heat exchange in the high-pressure heater is condensed and transported into the deaerator.

[0014] Preferably, the system further comprises a steam transportation pump for transporting the high-temperature steam in the heat storage unit.

[0015] Preferably, a first switching device is arranged between the flue and the bypass flue for adjusting the flow of flue gas transported from the flue into the bypass flue.

[0016] Preferably, a second switching device is arranged between the steam transportation pump and the heat exchange pipe for adjusting the flow of high-temperature steam transported from the heat storage unit into the heat exchange pipe.

[0017] Preferably, a third switching device is arranged between the steam transportation pump and the high-pressure heater for adjusting the flow of high-temperature steam transported from the heat storage unit into the high-pressure heater.

[0018] Preferably, the heat exchange pipe is a multi-layer coil pipe.

[0019] Preferably, the temperature of the flue gas to be treated is 50-250℃.

[0020] Preferably, the temperature of the high-temperature steam is 300-450℃.

[0021] Preferably, the number of layers of the multi-layer coil pipe is 1-10.

[0022] The SCR denitration system provided by the application can improve the temperature of the flue gas to be treated by the following steps: setting a bypass flue and a heat exchange pipe in the bypass flue, conveying high-temperature steam in the heat storage unit to the heat exchange pipe to exchange heat with the flue gas to be treated, and conveying the flue gas after heat exchange to the SCR denitration device for denitration treatment. In addition, the system can also convey part of the high-temperature steam output by the heat storage unit to the high-pressure heater to heat the water in the economizer, and then convey the heated water to the economizer to improve the temperature of the flue gas to be treated by heat exchange between the economizer and the flue gas in the flue, and then convey the flue gas after heat exchange to the bypass flue to exchange heat with the heat exchange pipe again to further improve the temperature of the flue gas, so that the temperature of the flue gas conveyed to the SCR denitration device meets the operating temperature of the SCR denitration catalyst. The two methods are used together to improve the temperature of the flue gas to be treated, so that the SCR denitration device can also operate normally during the period from the ignition and start of the boiler to the connection of the generator set to the grid. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Figure 1 is a schematic diagram of the SCR denitration system provided by the application.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] 1 heat storage unit; 2 economizer;

[0026] 3 high-pressure heater; 4 SCR denitration device;

[0027] 5 flue; 6 bypass flue;

[0028] 7 heat exchange pipe; 8 deaerator;

[0029] 9 steam conveying pump. DETAILED DESCRIPTION

[0030] The specific embodiments of the 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 application, and are not used to limit the application.

[0031] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and should be understood to include values approximately near these ranges and values within these ranges. For ranges of values, the endpoints of the ranges are combined with the individual points to form new ranges within the scope of the ranges.

[0032] In addition, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium, or internal connection of two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present application can be understood according to the specific circumstances.

[0033] In addition, if the present application involves the description of "first", "second" and the like, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments provided by the present application can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0034] 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 operation mode of the generator set reducing power output beyond the basic peak shaving range due to the large peak-valley difference of the power grid load.

[0035] In this paper, the "grid connection" refers to the power transmission line of the generator set being connected with the power transmission network, and starting to transmit power outward.

[0036] In combination with the description of Figure 1 The SCR denitration system comprises a heat storage unit 1, an economizer 2, a high-pressure heater 3 and an SCR denitration device 4.

[0037] In the system, the flue gas to be treated comes from the flue gas generated during the ignition start of the boiler to the grid connection of the generator set, and the temperature of the flue gas is 50-250 DEG C.

[0038] In the system, the bypass flue gas outlet of the flue 5 is communicated with the flue gas inlet of the bypass flue 6, the bypass flue 6 is provided with a heat exchange pipe 7, and the flue gas outlet of the bypass flue 6 is connected with the SCR denitration device 4. In the present application, the flue gas in the flue 5 is conveyed to the bypass flue 6 after flowing through the economizer 2 to exchange heat with the heat exchange pipe 7, and the flue gas after heat exchange is conveyed to the SCR denitration device 4 for denitration treatment. Specifically, the heat exchange medium in the heat exchange pipe 7 is high-temperature steam conveyed by the heat storage unit 1.

[0039] In the system, a first switching device is arranged between the flue 5 and the bypass flue 6, and is used to adjust the flow of flue gas from the flue 5 to the bypass flue 6.

[0040] In specific embodiments, the first switching device can be a device commonly used in the art for controlling the flow of gas, and can be a gas regulating valve or a gate valve.

[0041] In the system, the heat storage unit 1 is a steam accumulator, which has a structure similar to that of the prior art, and is used to assist in adjusting the steam load when it changes, so as to ensure that the generator set can be stably operated regardless of the steam load. The high-temperature steam stored in the heat storage unit 1 has a temperature of 300-450°C, and preferably 350-450°C.

[0042] In the prior art, when the generator set needs to reduce the load or participate in deep peak shaving, the high-temperature steam generated by the boiler can be transported to the heat storage unit 1 for storage, and can be used as a heat source for the generator set. In the present application, the high-temperature steam in the heat storage unit 1 is used for heat exchange with the flue gas to be treated, without the need for substantial modification of the equipment, so as to achieve the purpose of heat exchange of the flue gas, while reducing the energy consumption of the system.

[0043] In specific embodiments, the system comprises a steam delivery pump 9, which is used to transport the high-temperature steam in the heat storage unit 1 to the high-pressure heater 3 and the heat exchange pipe 7. Specifically, the steam delivery pump 9 is in communication with the outlet of the heat storage unit 1, and the steam delivery pump 9 is provided with a first outlet and a second outlet. The high-pressure heater 3 is connected to the first outlet of the steam delivery pump 9, and the heat exchange pipe 7 is connected to the second outlet of the steam delivery pump 9.

[0044] In specific embodiments, the high-temperature steam in the heat storage unit 1 is transported to the high-pressure heater 3 and the heat exchange pipe 7 through the steam delivery pump 9. The high-temperature steam in the high-pressure heater 3 exchanges heat with water, and the water after heat exchange is transported to the economizer 2 to exchange heat with flue gas. The flue gas after heat exchange is transported to the heat exchange pipe 7 to exchange heat with the high-temperature steam, and is then transported to the SCR denitration device 4 for treatment.

[0045] In the system, the steam delivery pump 9 can be a pump commonly used in the art for transporting high-temperature gas. Specifically, the steam delivery pump 9 can be a steam reciprocating pump or a steam jet pump.

[0046] In the preferred embodiment, the heat exchange pipe 7 is a multi-layer coil pipe, and the number of layers of the multi-layer coil pipe is 1-10, preferably 3-7. In the present application, by arranging the multi-layer coil pipe in the bypass flue 6, the heat exchange surface between the high-temperature steam in the pipe and the flue gas can be further increased, which helps to improve the heat exchange efficiency between the high-temperature steam and the flue gas, and further improves the heating rate of the flue gas.

[0047] In the preferred embodiment, in order to further improve the heating rate of the flue gas to be treated, a second switching device is arranged between the heat exchange pipe 7 and the steam delivery pump 9, which is used to adjust the flow of high-temperature steam delivered by the heat storage unit 1 into the heat exchange pipe 7. Specifically, the second switching device can be a device commonly used in the art to control the flow of gas, which can be a gas regulating valve or a gate valve.

[0048] In the system of the present application, the high-pressure heater 3 can be a device commonly used in the art. In the prior art, the high-pressure heater 3 is usually used to heat the feedwater of the generator set by using part of the steam of the steam turbine of the generator set, which is a heat conversion device. The high-pressure heater 3 includes a tube and a shell, and the steam is delivered in the tube of the high-pressure heater 3, and the water is delivered in the shell of the high-pressure heater 3. In the present application, the high-temperature steam in the heat storage unit 1 is delivered into the tube of the high-pressure heater 3, and the water in the shell is heated by the high-temperature steam in the tube. The heated water is delivered into the economizer 2 to exchange heat with the flue gas, and the heat exchange between the water in the economizer 2 and the flue gas to be treated is used to improve the temperature of the flue gas.

[0049] In the preferred embodiment, in order to further improve the heat exchange efficiency between the water in the economizer 2 and the flue gas, the steam delivery pump 9 and the high-pressure heater 3 are provided with a third switching device, which is used to adjust the flow of high-temperature steam delivered by the heat storage unit 1 into the high-pressure heater 3. The input amount of high-temperature steam can be adjusted by adjusting the opening and closing of the third switching device, so as to adjust the heating rate of the flue gas. Specifically, the third switching device can be a device commonly used in the art to control the flow of gas, which can be a gas regulating valve or a gate valve.

[0050] In the system of the present application, part of the high-temperature steam from the heat storage unit 1 is delivered into the high-pressure heater 3 to exchange heat with the water, and the water after heat exchange is delivered into the economizer 2 to exchange heat with the flue gas, and the flue gas after heat exchange is delivered into the bypass flue 6. The remaining part of the high-temperature steam from the heat storage unit 1 is delivered into the heat exchange pipe 7, and the flue gas after heat exchange exchanges heat with the high-temperature steam in the heat exchange pipe 7 again, and the flue gas after heat exchange again is delivered into the SCR denitration device 4 for denitration treatment.

[0051] In the system of the present application, the economizer 2 is a device commonly used in the art, which can be a light-pipe economizer and a finned economizer. The structure of the economizer 2 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 2 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 so as to achieve the purpose of saving energy. In the present application, the inventor of the present application, based on the original equipment arrangement of the entire generating set, delivers the high-temperature steam in the heat storage unit 1 to the high-pressure heater 3 through a pipeline to heat the inlet water temperature in the economizer 2, and raises the temperature of the water delivered to the economizer 2, so as to raise the flue gas temperature by using the heat exchange between the economizer 2 and the flue gas to be treated, and then heat the flue gas to be treated by using the original equipment in the generating set, thereby raising the temperature of the flue gas to be treated and saving the cost of system modification.

[0052] In a specific embodiment, there are two heat exchange modes between the economizer 2 and the flue gas: when the temperature of the flue gas to be treated is lower than the water temperature in the pipe of the economizer 2, the heat exchange mode between the economizer 2 and the flue gas is that the economizer 2 heats the flue gas to raise the flue gas temperature; when the flue gas temperature is higher than the water temperature in the pipe of the economizer 2, the heat exchange mode between the economizer 2 and the flue gas is that the water in the pipe of the economizer 2 absorbs heat from the flue gas, and after raising the inlet water temperature in the economizer 2, the heat absorbed by the economizer 2 from the flue gas to be treated is reduced, so as to raise the temperature of the flue gas to be treated.

[0053] In a specific embodiment, the water in the economizer 2 after heat exchange is used in the water system of the generating set.

[0054] In the prior art, the flue gas generated by the boiler is sent into the SCR denitration device 4 for treatment after passing through the flue 5. In a specific embodiment, the flue 5 is provided with a flue gas outlet connected with the SCR denitration device 4, which is used to send the flue gas in the flue 5 into the SCR denitration device 4. More specifically, in order to facilitate the adjustment of the flue gas flow in the flue 5 sent into the SCR denitration device 4, the flue outlet is provided with a fourth switching device for controlling the flue gas flow in the flue 5 sent into the SCR denitration device 4. Specifically, the fourth switching device can be a gas regulating valve. In the prior art, the flue gas generated during the ignition start-up of the boiler to grid connection has a low temperature and cannot reach the operating temperature of the SCR catalyst filled in the SCR denitration device 4, resulting in that the SCR denitration device 4 cannot operate normally. In the present application, by changing the connection relationship between the original devices in the generator set, the high-temperature steam in the heat storage unit 1 is sent into the high-pressure heater 3 and the heat exchange pipe 7 respectively, the high-temperature steam in the high-pressure heater 3 exchanges heat with water, and then the heat-exchanged water is sent into the economizer 2, and then the heat exchange between the economizer 2 and the flue gas to be treated is used to improve the flue gas temperature, and then the heat-exchanged flue gas is sent into the bypass flue 6 and exchanges heat with the high-temperature steam in the heat exchange pipe 7 to further improve the temperature, and finally the heat-exchanged flue gas is sent into the SCR denitration device 4 for denitration treatment, which realizes the purpose of denitration treatment of low-temperature flue gas and ensures that the boiler ignition and the SCR denitration device can be started and operated at the same time.

[0055] In the system of the present application, the SCR denitration system further comprises a deaerator 8 connected with the high-pressure heater 3 and the heat exchange pipe 7 respectively. The high-temperature steam exchanged in the high-pressure heater 3 and the heat exchange pipe 7 is sent into the deaerator 8 for treatment, and the treated water is used in the water system of the generator set, realizing the reuse of water resources and saving water resources.

[0056] In a specific embodiment, the heat-exchanged high-temperature steam sent into the deaerator 8 can be steam or liquid water.

[0057] The operation process of the system is as follows: part of the high-temperature steam from the heat storage unit 1 is transported to the high-pressure heater 3 to exchange heat with water, the water after heat exchange is transported to the economizer 2, and the remaining part of the high-temperature steam is transported to the heat exchange pipe 7; the flue gas to be treated exchanges heat with the water in the economizer 2, the flue gas after heat exchange is transported to the bypass flue 6 to further exchange heat with the high-temperature steam in the heat exchange pipe 7, the flue gas after further heat exchange is transported to the SCR denitration device 4 for denitration treatment; the high-temperature steam after heat exchange in the high-pressure heater 3 and the heat exchange pipe 7 is transported to the deaerator 8 for treatment.

[0058] In the system, the temperature of the flue gas after heat exchange obtained by exchanging heat between the water in the economizer 2 and the flue gas to be treated still cannot meet the operating temperature of the SCR denitration catalyst, so the flue gas after heat exchange needs to be transported to the bypass flue 6 to further exchange heat with the high-temperature steam in the heat exchange pipe 7 to increase the temperature of the flue gas, and the temperature of the flue gas after further heat exchange reaches the operating temperature of the SCR denitration catalyst, and the two methods jointly act on increasing the temperature of the flue gas to be treated.

[0059] In the system, the outlet of the heat storage unit 1 is connected with the steam delivery pump 9, the steam delivery pump 9 is provided with a first outlet and a second outlet; the inlet end of the high-pressure heater 3 is connected with the first outlet of the steam delivery pump 9, and the inlet end of the heat exchange pipe 7 is connected with the second outlet of the steam delivery pump 9; the high-pressure heater 3 is provided with a water outlet end, and the water outlet end is connected with the economizer 2; the economizer 2 is arranged in the flue 5, the flue gas outlet of the flue 5 is connected with the SCR denitration device 4, and the flue 5 is communicated with the bypass flue 6; the heat exchange pipe 7 is arranged in the bypass flue 6; the high-pressure heater 3 is provided with a heat exchange steam outlet, and the heat exchange steam outlet is connected with the deaerator 8; and the outlet end of the heat exchange pipe 7 is connected with the deaerator 8.

[0060] In a specific embodiment, the system is used to heat the flue gas generated during the ignition and grid connection of the boiler, and the flue gas after heating is transported to the SCR denitration device 4 to enable the SCR denitration device 4 to operate normally. When the generator set is stably operated, the temperature of the flue gas to be treated has met the temperature required for the operation of the SCR denitration device, the first switch device, the second switch device and the third switch device can be adjusted to stop inputting high-temperature steam into the heat exchange pipe 7 and the high-pressure heater 3, and the flue gas to be treated is directly transported to the SCR denitration device 4 after flowing through the economizer 2 for treatment, at this time, the devices in the system restore their original functions, and the generator set starts to operate normally.

[0061] According to the first embodiment of the SCR denitration system, the system comprises a heat storage unit 1, an economizer 2, a high-pressure heater 3 and an SCR denitration device 4; the economizer 2 is arranged in a flue 5, a bypass flue gas outlet of the flue 5 is communicated with a flue gas inlet of a bypass flue 6, a flue gas outlet of the bypass flue 6 is connected with the SCR denitration device 4; the bypass flue 6 is provided with a heat exchange pipe 7; the heat storage unit 1 is connected with the high-pressure heater 3 and the heat exchange pipe 7 respectively; high-temperature steam from the heat storage unit 1 is transported into the high-pressure heater 3 to exchange heat with water, the water after heat exchange is transported into the economizer 2, flue gas to be treated exchanges heat with the water in the economizer 2, the flue gas after heat exchange is transported into the bypass flue 6 to exchange heat with high-temperature steam from the heat storage unit 1 in the heat exchange pipe 7, and then is transported into the SCR denitration device 4 for treatment; the system further comprises a deaerator 8, the deaerator 8 is connected with the high-pressure heater 3 and the heat exchange pipe 7 respectively.

[0062] According to the first embodiment of the SCR denitration system, the system comprises a heat storage unit 1, an economizer 2, a high-pressure heater 3 and an SCR denitration device 4; the economizer 2 is arranged in a flue 5, a bypass flue gas outlet of the flue 5 is communicated with a flue gas inlet of a bypass flue 6, a flue gas outlet of the bypass flue 6 is connected with the SCR denitration device 4; the bypass flue 6 is provided with a heat exchange pipe 7; the heat storage unit 1 is connected with the high-pressure heater 3 and the heat exchange pipe 7 respectively; high-temperature steam from the heat storage unit 1 is transported into the high-pressure heater 3 to exchange heat with water, the water after heat exchange is transported into the economizer 2, flue gas to be treated exchanges heat with the water in the economizer 2, the flue gas after heat exchange is transported into the bypass flue 6 to exchange heat with high-temperature steam from the heat storage unit 1 in the heat exchange pipe 7, and then is transported into the SCR denitration device 4 for treatment; the system further comprises a deaerator 8, the deaerator 8 is connected with the high-pressure heater 3 and the heat exchange pipe 7 respectively; the flue 5 and the bypass flue 6 are provided with a first switch device for adjusting the flue gas flow rate transported from the flue 5 into the bypass flue 6; a second switch device is arranged between the steam transportation pump 9 and the heat exchange pipe 7 for adjusting the flow rate of high-temperature steam from the heat storage unit 1 transported into the heat exchange pipe 7; a third switch device is arranged between the steam transportation pump 9 and the high-pressure heater 3 for adjusting the flow rate of high-temperature steam from the heat storage unit 1 transported into the high-pressure heater 3.

[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 and comparative examples are implemented by using the following SCR denitration system, and the flow chart of the SCR denitration system is shown in Figure 1The SCR denitration system comprises a heat storage unit 1, a coal economizer 2, a high-pressure heater 3, and an SCR denitration device 4, as well as a deaerator 8, a steam delivery pump 9, a first switching device, a second switching device, a third switching device, and a fourth switching device;

[0065] The coal economizer 2 is arranged in a flue 5, a bypass flue gas outlet of the flue 5 is in communication with a flue gas inlet of a bypass flue 6, a flue gas outlet of the flue 5 is connected with the SCR denitration device 4, and a flue gas outlet of the bypass flue 6 is connected with the SCR denitration device 4;

[0066] The bypass flue 6 is provided with a heat exchange pipe 7;

[0067] The heat storage unit 1 is connected with the high-pressure heater 3 and the heat exchange pipe 7, respectively;

[0068] The deaerator 8 is connected with the high-pressure heater 3 and the heat exchange pipe 7, respectively;

[0069] The steam delivery pump 9 is connected with the heat storage unit 1;

[0070] The first switching device is located between the flue 5 and the bypass flue 6;

[0071] The second switching device is located between the steam delivery pump 9 and the heat exchange pipe 7;

[0072] The third switching device is located between the steam delivery pump 9 and the high-pressure heater 3;

[0073] The flue gas outlet of the flue 5 is provided with the fourth switching device;

[0074] The heat storage unit 1 is a steam heat accumulator, and the first switching device, the second switching device, the third switching device, and the fourth switching device are all gas regulating valves.

[0075] Embodiment 1

[0076] Close the fourth switch device, open the first switch device, the second switch device and the third switch device, part of the high-temperature steam (temperature is 350 DEG C) from the heat storage unit 1 is transported to the high-pressure heater 3 and exchanges heat with water, the water after heat exchange is transported to the economizer 2, the remaining part of the high-temperature steam (temperature is 350 DEG C) is transported to the heat exchange pipe 7;The flue gas to be treated (temperature is 100 DEG C) exchanges heat with the water (temperature is 200 DEG C) in the economizer 2, the flue gas after heat exchange (temperature is 150 DEG C) is transported to the bypass flue 6 and further exchanges heat with the high-temperature steam in the heat exchange pipe 7, the flue gas after further heat exchange (temperature is 270 DEG C) is transported to the SCR denitration device 4 and is subjected to denitration treatment;The steam after heat exchange in the high-pressure heater 3 and the heat exchange pipe 7 is transported to the deaerator 8 and is treated.

[0077] Comparative example 1

[0078] Close the first switch device and the second switch device, open the third switch device and the fourth switch device, the high-temperature steam (temperature is 350 DEG C) from the heat storage unit 1 is transported to the high-pressure heater 3 and exchanges heat with water, the water after heat exchange is transported to the economizer 2, the flue gas to be treated (temperature is 100 DEG C) exchanges heat with the water (210 DEG C) in the economizer 2, the flue gas after heat exchange (temperature is 170 DEG C) is directly transported to the SCR denitration device 4 and is subjected to denitration treatment.

[0079] Because the temperature of the flue gas at the inlet of the SCR denitration device 4 is too low, the SCR denitration device 4 cannot be normally started at this time.

[0080] The system disclosed by the application can heat the flue gas to be treated, ensure that the SCR denitration device can be normally put into operation when the boiler is ignited and started, realize the denitration treatment process of the low-temperature flue gas, ensure that the flue gas generated during the period when the boiler is started to the generator set and is connected to the grid can be smoothly subjected to denitration treatment, and have great application prospect.

[0081] The above describes the preferred embodiments of the application, but the application is not limited to this. Within the technical concept of the application, the technical solutions of the application can be subjected to various simple modifications, including that various technical features are combined in any other suitable manner, and these simple modifications and combinations should also be regarded 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 heat storage unit (1), an economizer (2), a high-pressure heater (3) and an SCR denitration device (4); The economizer (2) is arranged in a flue (5), a bypass flue gas outlet of the flue (5) is communicated with a flue gas inlet of a bypass flue (6), and a flue gas outlet of the bypass flue (6) is connected with the SCR denitration device (4); The bypass flue (6) is provided with a heat exchange pipe (7); The heat storage unit (1) is connected with the high-pressure heater (3) and the heat exchange pipe (7) respectively; High-temperature steam from the heat storage unit (1) is transported into the high-pressure heater (3) to exchange heat with water, the water after heat exchange is transported into the economizer (2), the flue gas to be treated exchanges heat with the water in the economizer (2), the flue gas after heat exchange exchanges heat with high-temperature steam from the heat storage unit (1) in the heat exchange pipe (7), and then is transported into the SCR denitration device (4) for treatment; The system further comprises a steam delivery pump (9) for transporting high-temperature steam in the heat storage unit (1) to the high-pressure heater (3) and the heat exchange pipe (7); an outlet of the heat storage unit (1) is connected with the steam delivery pump (9), the steam delivery pump (9) is provided with a first outlet and a second outlet; an inlet end of the high-pressure heater (3) is connected with the first outlet of the steam delivery pump (9), and an inlet end of the heat exchange pipe (7) is connected with the second outlet of the steam delivery pump (9).

2. The SCR de-NOx system according to claim 1, characterized by, The system further comprises a deaerator (8) connected with the high-pressure heater (3) and the heat exchange pipe (7) respectively.

3. The SCR de-NOx system according to claim 1, characterized by, A first switching device is arranged between the flue (5) and the bypass flue (6) for adjusting the flue gas flow rate transported from the flue (5) into the bypass flue (6).

4. The SCR de-NOx system according to claim 1, characterized by, The heat exchange pipe (7) is a multi-layer coil pipe.

5. The SCR de-NOx system of claim 1, wherein, The temperature of the flue gas to be treated is 50-250℃.

6. The SCR de-NOx system of claim 1, wherein, The temperature of the high-temperature steam is 300-450℃.

7. The SCR de-NOx system of claim 1, wherein, A second switching device is arranged between the steam delivery pump (9) and the heat exchange pipe (7) for adjusting the flow rate of high-temperature steam transported from the heat storage unit (1) into the heat exchange pipe (7).

8. The SCR de-NOx system of claim 1, wherein, A third switching device is arranged between the steam delivery pump (9) and the high-pressure heater (3) for adjusting the flow rate of high-temperature steam transported from the heat storage unit (1) into the high-pressure heater (3).

9. The SCR deNOx system of claim 4, wherein, The multi-layer coil pipe has 1-10 layers.

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