System and method for realizing ignition denitration by coupling gas unit with coal-fired unit

Abstract

The invention provides a system and a method for realizing ignition and denitration by coupling a gas unit with a coal-fired unit, and belongs to the field of denitration of thermal generator sets. The invention discloses a system for realizing ignition and denitration by coupling a gas unit with a coal-fired unit. The system comprises the gas unit, the coal-fired unit, a denitration module and a flue gas bypass, the input end of the flue gas bypass is used for inputting exhaust steam generated by a gas turbine in the gas unit, and the output end of the flue gas bypass is used for conveying the exhaust steam to a coal-fired boiler in the coal-fired unit; and the exhaust steam is used for drying a coal-fired boiler of the coal-fired unit and heating a denitration catalyst in the denitration module in advance, so that the denitration module is immediately put into use when the coal-fired unit is ignited. According to the system, exhaust steam generated by a gas unit is conveyed into a coal-fired boiler of the coal-fired unit in advance before the coal-fired unit is ignited, and heat of the exhaust steam generated by the gas unit is used for drying the coal-fired boiler and heating a denitration catalyst in a denitration module, so that the denitration module is immediately put into use when the coal-fired unit is ignited.

Description

Technical Field

[0001] The present invention relates to the technical field of denitration of thermal power generating sets, and in particular to a system for coupling a gas-fired set to realize ignition head denitration and a method for coupling a gas-fired set to realize ignition denitration. Background Art

[0002] During the ignition and startup phase of a power plant boiler, the overall temperature of the boiler is low, making it difficult to reach the minimum operating temperature of the denitrification system, resulting in the failure to denitrify the flue gas before grid connection. However, as environmental protection is increasingly valued, it is required that the SCR denitrification system be put into operation after the power plant boiler is connected to the grid. The minimum operating temperature of the SCR denitrification system is generally around 300°C. When the minimum operating temperature is lower than the minimum operating temperature, NO in the flue gas will x There is no catalytic reduction reaction with NH3.

[0003] In the context of the construction of new power systems, frequent start and stop of coal-fired power units has become the norm, and pollutant emission standards are becoming increasingly stringent. Therefore, solving the technical problem of denitrification of flue gas during the ignition and startup phase of power plant boilers has become the key to connecting thermal power generating units to the grid. Summary of the invention

[0004] In order to solve the above-mentioned technical defects, the present invention provides a system and method for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification. The system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, by pre-transmitting the exhaust steam generated by the gas-fired unit to the coal-fired boiler of the coal-fired unit before the ignition of the coal-fired unit, and utilizing the heat of the exhaust steam generated by the gas-fired unit to heat the coal-fired boiler and the denitrification catalyst in the denitrification module, so that the denitrification module can be immediately put into use when the coal-fired unit is ignited, that is, solving the technical problem of denitrifying the flue gas during the ignition and startup stage of the power station boiler.

[0005] The first aspect of the present invention provides a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitration, comprising: a gas-fired unit, a coal-fired unit, a denitration module and a flue gas bypass;

[0006] The gas turbine of the gas-fired unit is connected to the coal-fired boiler of the coal-fired unit through the flue gas bypass, and the coal-fired boiler is connected to the denitration module;

[0007] The flue gas bypass is used to input the exhaust steam generated by the gas turbine of the gas unit within a preset time period before the ignition of the coal-fired unit, and output the exhaust steam to the coal-fired boiler of the coal-fired unit. The exhaust steam is used to heat the coal-fired boiler in advance and to heat the denitration catalyst in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

[0008] In an embodiment of the present invention, the flue gas bypass includes a main flue gas bypass, a first flue gas bypass branch and a second flue gas bypass branch;

[0009] The input end of the main flue gas bypass is used to input the exhaust steam, and the output end of the main flue gas bypass is respectively connected to the input end of the first flue gas bypass branch and the input end of the second flue gas bypass branch;

[0010] The output end of the first flue gas bypass branch is connected to the first and second small wind boxes located in the middle layer of the coal-fired boiler, and the output end of the second flue gas bypass branch is connected to the second and second small wind boxes located in the middle layer of the coal-fired boiler. The flue gas bypass transports the exhaust steam generated by the gas turbine to the coal-fired boiler through the first and second small wind boxes.

[0011] In an embodiment of the present invention, the gas unit further comprises: a waste heat boiler;

[0012] The input end of the waste heat boiler is connected to the output end of the gas turbine for receiving exhaust steam generated by the gas turbine;

[0013] The input end of the flue gas bypass is connected to the waste heat boiler and is used to receive exhaust steam from the gas turbine of the waste heat boiler.

[0014] In an embodiment of the present invention, the temperature of the exhaust steam of the gas turbine input to the input end of the flue gas bypass is greater than a preset temperature.

[0015] In the embodiment of the present invention, the flue gas bypass further includes a first flow collection device, a first bypass regulating door, a second flow collection device and a second bypass regulating door;

[0016] The first flow collection device is used to collect the flow value of the exhaust steam in the first flue gas bypass branch;

[0017] The first bypass regulating gate is used to adjust the flow rate of exhaust steam in the first flue gas bypass branch according to the flow rate value collected by the first flow rate collection device;

[0018] The second flow rate collection device is used to collect the flow value of the exhaust steam in the second flue gas bypass branch;

[0019] The second bypass regulating door is used to regulate the exhaust steam generated by the gas turbine flowing in the second flue gas bypass branch.

[0020] In an embodiment of the present invention, a deviation between a flow rate of exhaust steam generated by the gas turbine in the first flue gas bypass branch and a flow rate of exhaust steam generated by the gas turbine flowing in the second flue gas bypass branch is less than a preset deviation value.

[0021] In an embodiment of the present invention, the denitration module includes a temperature acquisition device;

[0022] The temperature collection device is used to collect the flue gas temperature value at the inlet of the denitration module.

[0023] In an embodiment of the present invention, a shut-off door is provided in the flue gas bypass;

[0024] The shut-off door is used to shut off the flue gas bypass when the flue gas temperature value collected by the temperature collection device reaches a preset temperature value.

[0025] The second aspect of the present invention provides a method for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, comprising:

[0026] In a preset time period before the ignition of the coal-fired unit, the exhaust steam generated by the gas turbine in the gas-fired unit enters the coal-fired boiler of the coal-fired unit through the flue gas bypass;

[0027] The heat of the exhaust steam generated by the gas turbine is used to heat the coal-fired boiler and the denitration catalyst in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

[0028] In an embodiment of the present invention, the method further includes:

[0029] When the flue gas temperature at the inlet of the denitration module reaches a preset temperature value, the flue gas bypass is shut down and the coal-fired unit is connected to the grid for operation.

[0030] The system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, wherein the exhaust steam generated by the gas-fired unit is pre-transmitted to the coal-fired boiler of the coal-fired unit before the ignition of the coal-fired unit, and the heat of the exhaust steam generated by the gas-fired unit is used to heat the coal-fired boiler and the denitrification catalyst in the denitrification module, so that the denitrification module can be immediately put into use when the coal-fired unit is ignited, thereby solving the technical problem of denitrifying the flue gas during the ignition and startup stage of the power station boiler.

[0031] Other features and advantages of the technical solution of the present invention will be described in detail in the specific implementation section below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 It is a schematic diagram of the structure of a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, provided in Example 1 of the present invention;

[0034] Figure 2 This is a flow chart of a method for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, provided in Example 1 of the present invention;

[0035] Figure 3 It is a structural schematic diagram of a system for coupling a gas-fired unit with a coal-fired unit to achieve ignition and denitrification, provided in Example 2 of the present invention.

[0036] Description of Reference Numerals

[0037] 1-gas turbine, 2-coal-fired boiler, 3-flue gas bypass, 31-main flue gas bypass, 32-first flue gas bypass branch, 33-second flue gas bypass branch, 4-waste heat boiler, 5-first flow collection device, 6-first bypass regulating gate, 7-second flow collection device, 8-second bypass regulating gate, 9-first and second small wind boxes, 10-second and second small wind boxes, 11-denitrification catalyst, 12-temperature collection device, 13-tail flue gas treatment device, 14-chimney, 15-ammonia injection branch pipe, 16-shutoff door. DETAILED DESCRIPTION

[0038] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0041] In the present invention, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In the process of realizing the present invention, the inventors found that during the ignition and startup phase of the power plant boiler, the overall temperature of the boiler was low, making it difficult to reach the minimum operating temperature of the denitrification system, resulting in the failure to denitrify the flue gas before grid connection. However, as environmental protection has received increasing attention, it is required that the SCR denitrification system be put into operation after the power plant boiler is connected to the grid. The minimum operating temperature of the SCR denitrification system is generally around 300°C. When the minimum operating temperature is lower than the minimum operating temperature, NO in the flue gas will x There is no catalytic reduction reaction with NH3.

[0043] In the context of the construction of new power systems, frequent start and stop of coal-fired power units has become the norm, and pollutant emission standards are becoming increasingly stringent. Therefore, solving the technical problem of denitrification of flue gas during the ignition and startup phase of power plant boilers has become the key to connecting thermal power generating units to the grid.

[0044] In view of the above problems, an embodiment of the present invention provides a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitration, comprising: a gas-fired unit, a coal-fired unit, a denitration module and a flue gas bypass 3; the gas turbine 1 of the gas-fired unit is connected to the coal-fired boiler 2 of the coal-fired unit through the flue gas bypass 3, and the coal-fired boiler 2 is connected to the denitration module;

[0045] The flue gas bypass 3 is used to input the exhaust steam generated by the gas turbine 1 of the gas unit within a preset time period before the ignition of the coal-fired unit, output the exhaust steam to the coal-fired boiler 2 of the coal-fired unit, and use the exhaust steam to heat the coal-fired boiler 2 in advance and heat the denitration catalyst 11 in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited. The system of coupling the gas unit with the coal-fired unit to realize ignition and denitration is achieved by pre-transmitting the exhaust steam generated by the gas unit to the coal-fired boiler 2 of the coal-fired unit before the ignition of the coal-fired unit, and using the heat of the exhaust steam generated by the gas unit to heat the coal-fired boiler 2 and heat the denitration catalyst 11 in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited, that is, solving the technical problem of denitrifying the flue gas during the ignition and startup stage of the power station boiler.

[0046] Example 1

[0047] Figure 1 Schematic diagram of the structure of a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification provided by Example 1 of the present invention. Figure 1 As shown, the present embodiment provides a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitration, comprising: a gas-fired unit, a coal-fired unit, a denitration module and a flue gas bypass 3;

[0048] The gas turbine 1 of the gas-fired unit is connected to the coal-fired boiler 2 of the coal-fired unit through the flue gas bypass 3, and the coal-fired boiler 2 is connected to the denitration module;

[0049] The flue gas bypass 3 is used to input the exhaust steam generated by the gas turbine 1 of the gas unit within a preset time period before the ignition of the coal-fired unit, and output the exhaust steam to the coal-fired boiler 2 of the coal-fired unit. The exhaust steam is used to heat the coal-fired boiler 2 in advance and the denitration catalyst 11 in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

[0050] More specifically, the flue gas bypass 3 is opened, and the exhaust steam generated by the gas turbine 1 is used to heat the removed catalyst in the denitration module. At the same time, the denitration module denitrates the exhaust steam generated by the gas turbine 1 to ensure that the ultra-low emission of nitrogen oxides meets the standard.

[0051] In this embodiment, the flue gas bypass 3 includes a main flue gas bypass 31, a first flue gas bypass branch 32 and a second flue gas bypass branch 33;

[0052] The input end of the main flue gas bypass 31 is used to input the exhaust steam, and the output end of the main flue gas bypass 31 is respectively connected to the input end of the first flue gas bypass branch 32 and the input end of the second flue gas bypass branch 33;

[0053] The output end of the first flue gas bypass branch 32 is connected to the first and second small wind boxes 9 located in the middle layer of the coal-fired boiler 2, and the output end of the second flue gas bypass branch 33 is connected to the second and second small wind boxes 10 located in the middle layer of the coal-fired boiler 2. The flue gas bypass 3 transports the exhaust steam generated by the gas turbine 1 to the coal-fired boiler 2 through the first and second small wind boxes 9 and the second secondary small wind boxes 10.

[0054] In this embodiment, the flue gas bypass 3 is selected to be directed to the secondary small wind box in the middle layer of the coal-fired boiler 2, and the exhaust steam of the gas turbine 1 is only delivered to the secondary small wind box of the burner in the middle layer of the coal-fired boiler 2. The exhaust steam of the gas turbine 1 will not be delivered to the secondary small wind boxes at the bottom and top layers of the gas boiler, thereby ensuring the stable ignition of the burner at the bottom layer of the coal-fired boiler 2.

[0055] In this embodiment, the gas unit further comprises: a waste heat boiler 4;

[0056] The input end of the waste heat boiler 4 is connected to the output end of the gas turbine 1 for receiving exhaust steam generated by the gas turbine 1;

[0057] An input end of the flue gas bypass 3 is connected to the waste heat boiler 4 for receiving exhaust steam from the gas turbine 1 of the waste heat boiler 4 .

[0058] In this embodiment, the flue gas generated by the combustion of the waste heat boiler 4 is processed in turn by the tail flue gas treatment device 13 and the chimney 14 and then discharged to ensure that environmental protection requirements are met.

[0059] In this embodiment, the temperature of the exhaust steam of the gas turbine 1 input to the input end of the flue gas bypass 3 is greater than a preset temperature.

[0060] Specifically, the input end of the flue gas bypass 3 is connected to a predetermined position on the waste heat boiler 4 to ensure that the exhaust temperature of the waste heat boiler 4 entering the flue gas bypass 3 is greater than a preset temperature value. In this embodiment, the preset temperature value is 380°C.

[0061] In this embodiment, the flue gas bypass 3 further includes a first flow collection device 5, a first bypass regulating door 6, a second flow collection device 7 and a second bypass regulating door 8;

[0062] The first flow collection device 5 is used to collect the flow value of the exhaust steam in the first flue gas bypass branch 32;

[0063] The first bypass regulating gate 6 is used to adjust the flow rate of exhaust steam in the first flue gas bypass branch 32 according to the flow rate value collected by the first flow rate collection device 5;

[0064] The second flow rate collection device 7 is used to collect the flow value of the exhaust steam in the second flue gas bypass branch 33;

[0065] The second bypass regulating door 8 is used to regulate the exhaust steam generated by the gas turbine 1 flowing in the second flue gas bypass branch 33 .

[0066] In this embodiment, a deviation between the flow rate of exhaust steam generated by the gas turbine 1 in the first flue gas bypass branch 32 and the flow rate of exhaust steam generated by the gas turbine 1 flowing in the second flue gas bypass branch 33 is less than a preset deviation value.

[0067] Furthermore, the first bypass regulating door 6 and the second bypass regulating door 8 are electric regulating doors.

[0068] Specifically, the first bypass regulating gate 6 is used to regulate the exhaust steam flow in the first flue gas bypass branch 32, and the second bypass regulating gate 8 is used to regulate the exhaust steam flow in the second flue gas bypass branch 33, to ensure that the exhaust steam flow of the first and second small wind boxes 9 and the second and second small wind boxes 10 entering the total layer of the front and rear walls of the coal-fired boiler 2 are consistent.

[0069] In this embodiment, the denitration module includes a temperature acquisition device 12;

[0070] The temperature collection device 12 is used to collect the flue gas temperature value at the inlet of the denitration module.

[0071] In this embodiment, a shutoff door 16 is provided in the flue gas bypass 3;

[0072] The shut-off door 16 is used to shut off the flue gas bypass 3 when the flue gas temperature value collected by the temperature collection device 12 reaches a preset temperature value.

[0073] In this embodiment, the denitration module further includes an ammonia injection branch pipe 15 , and the ammonia injection branch pipe 15 is arranged in the flue connecting the denitration module and the coal-fired boiler 2 .

[0074] Specifically, in this embodiment, the preset temperature value is 330° C. When the flue gas temperature at the inlet of the denitration module is stabilized at 330° C., the shutoff door 16 is closed to close the flue gas bypass 3 .

[0075] When the coal-fired boiler 2 is ignited and started, the shutoff door 16 is opened about 6 hours in advance, and the exhaust gas of the gas turbine 1 enters the boiler furnace through the two secondary small wind boxes in the middle layer of the coal-fired boiler 2 to heat the boiler heating surface, the denitration catalyst 11, etc. The pollutants of this part of the exhaust gas can be treated by the original denitration, dust removal, desulfurization and other equipment (i.e., denitration module) of the boiler, and will not cause environmental emission problems.

[0076] When the coal-fired boiler 2 is ignited, the burner of the lowest layer of the coal-fired boiler 2 is put into operation first. At this time, the flue gas temperature at the inlet of the denitrification module can be kept above the minimum operation temperature, and the denitrification module can be put into operation all the time. The exhaust gas of the gas turbine enters the furnace at the middle layer burner, and will not affect the combustion stability of the lower layer burner. When the flue gas temperature at the inlet of the denitrification module is stabilized at above 330°C, the shut-off door 16 is closed. At this time, the exhaust gas of the gas turbine no longer enters the coal-fired boiler 2, and the middle layer burner of the coal-fired boiler 2 is also ignited and put into operation. After the burner of the middle layer is ignited and put into operation, the flue gas temperature at the inlet of the denitrification module will only increase and not decrease. After the coal-fired unit is connected to the grid, the denitrification flue gas temperature can reach the minimum operation temperature.

[0077] Figure 2 The flowchart of a method for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification is provided in an embodiment of the present invention. Figure 2 As shown, this embodiment provides a method for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, comprising:

[0078] S1. In a preset time period before the ignition of the coal-fired unit, the exhaust steam generated by the gas turbine 1 in the gas unit enters the coal-fired boiler 2 of the coal-fired unit through the flue gas bypass 3;

[0079] S2. The heat of the exhaust steam generated by the gas turbine 1 is used to heat the coal-fired boiler 2 and the denitration catalyst 11 in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

[0080] In this embodiment, the method further includes:

[0081] S3. When the flue gas temperature at the inlet of the denitration module reaches a preset temperature value, the flue gas bypass 3 is shut down and the coal-fired unit is connected to the grid for operation.

[0082] Specifically, when the coal-fired boiler 2 is ignited and started, the shutoff door 16 is opened about 6 hours in advance, and the exhaust gas of the gas turbine 1 enters the boiler furnace through the two secondary small wind boxes in the middle layer of the coal-fired boiler 2, and heats the boiler heating surface, the denitration catalyst 11, etc. The pollutants of this part of the exhaust gas can be treated by the original denitration, dust removal, desulfurization and other equipment (i.e., denitration module) of the boiler, and will not cause environmental emission problems.

[0083] When the coal-fired boiler 2 is ignited, the burner of the lowest layer of the coal-fired boiler 2 is put into operation first. At this time, the flue gas temperature at the inlet of the denitrification module can be kept above the minimum operation temperature, and the denitrification module can be put into operation all the time. The exhaust gas of the gas turbine enters the furnace at the middle layer burner, and will not affect the combustion stability of the lower layer burner. When the flue gas temperature at the inlet of the denitrification module is stabilized at above 330°C, the shut-off door 16 is closed. At this time, the exhaust gas of the gas turbine no longer enters the coal-fired boiler 2, and the middle layer burner of the coal-fired boiler 2 is also ignited and put into operation. After the burner of the middle layer is ignited and put into operation, the flue gas temperature at the inlet of the denitrification module will only increase and not decrease. After the coal-fired unit is connected to the grid, the denitrification flue gas temperature can reach the minimum operation temperature.

[0084] Since the gas turbine 1 has a fast ignition speed, strong peak capacity and fast load change rate, the deep coupling between the gas turbine system and the coal-fired boiler 2 is conducive to the flexible peak regulation of the coal-fired unit and enhances the competitiveness of the coal-fired unit in the context of new power system construction.

[0085] Example 2

[0086] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the gas-fired unit and the coal-fired unit share a set of tail flue gas treatment equipment to reduce investment and operating costs.

[0087] Specifically, Figure 3 : is a schematic diagram of the structure of a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, provided in Example 2 of the present invention. Figure 3As shown, the gas unit includes a gas turbine 1 and a waste heat boiler 4, and the gas unit includes a coal-fired boiler 2; the waste heat boiler 4 of the gas unit and the coal-fired boiler 2 of the coal-fired unit are connected through a flue gas bypass 3, which is used to transport the exhaust steam of the gas unit to the coal-fired boiler 2.

[0088] When the exhaust steam of the gas unit is transported to the coal-fired boiler 2 to heat the coal-fired boiler 2 and the denitration catalyst 11, the denitration module is used to denitrate the exhaust steam generated by the gas turbine 1, thereby ensuring ultra-low emission of nitrogen oxides.

[0089] The tail flue gas generated by the waste heat boiler 4 of the gas unit is directly sent to the air preheater outlet of the coal-fired boiler 2, and shares the dust collector and desulfurization equipment with the original boiler system. Since there is little nitrogen oxide in the exhaust gas of the gas turbine, it will not affect the emission of nitrogen oxides from the boiler system.

[0090] like Figure 3 As shown, the present embodiment provides a system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitration, comprising: a gas-fired unit, a coal-fired unit, a denitration module and a flue gas bypass 3;

[0091] The gas turbine 1 of the gas-fired unit is connected to the coal-fired boiler 2 of the coal-fired unit through the flue gas bypass 3, and the coal-fired boiler 2 is connected to the denitration module;

[0092] The flue gas bypass 3 is used to input the exhaust steam generated by the gas turbine 1 of the gas unit within a preset time period before the ignition of the coal-fired unit, and output the exhaust steam to the coal-fired boiler 2 of the coal-fired unit. The exhaust steam is used to heat the coal-fired boiler 2 in advance and the denitration catalyst 11 in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

[0093] More specifically, the flue gas bypass 3 is opened, and the exhaust steam generated by the gas turbine 1 is used to heat the removed catalyst in the denitration module. At the same time, the denitration module denitrates the exhaust steam generated by the gas turbine 1 to ensure that the ultra-low emission of nitrogen oxides meets the standard.

[0094] In this embodiment, the flue gas bypass 3 includes a main flue gas bypass 31, a first flue gas bypass branch 32 and a second flue gas bypass branch 33;

[0095] The input end of the main flue gas bypass 31 is used to input the exhaust steam, and the output end of the main flue gas bypass 31 is respectively connected to the input end of the first flue gas bypass branch 32 and the input end of the second flue gas bypass branch 33;

[0096] The output end of the first flue gas bypass branch 32 is connected to the first and second small wind boxes 9 located in the middle layer of the coal-fired boiler 2, and the output end of the second flue gas bypass branch 33 is connected to the second and second small wind boxes 10 located in the middle layer of the coal-fired boiler 2. The flue gas bypass 3 transports the exhaust steam generated by the gas turbine 1 to the coal-fired boiler 2 through the first and second small wind boxes 9 and the second secondary small wind boxes 10.

[0097] In this embodiment, the flue gas bypass 3 is selected to be directed to the secondary small wind box in the middle layer of the coal-fired boiler 2, and the exhaust steam of the gas turbine 1 is only delivered to the secondary small wind box of the burner in the middle layer of the coal-fired boiler 2. The exhaust steam of the gas turbine 1 will not be delivered to the secondary small wind boxes at the bottom and top layers of the gas boiler, thereby ensuring the stable ignition of the burner at the bottom layer of the coal-fired boiler 2.

[0098] In this embodiment, the gas unit further comprises: a waste heat boiler 4;

[0099] The input end of the waste heat boiler 4 is connected to the output end of the gas turbine 1 for receiving exhaust steam generated by the gas turbine 1;

[0100] An input end of the flue gas bypass 3 is connected to the waste heat boiler 4 for receiving exhaust steam from the gas turbine 1 of the waste heat boiler 4 .

[0101] In this embodiment, the temperature of the exhaust steam of the gas turbine 1 input to the input end of the flue gas bypass 3 is greater than a preset temperature.

[0102] Specifically, the input end of the flue gas bypass 3 is connected to a predetermined position on the waste heat boiler 4 to ensure that the exhaust temperature of the waste heat boiler 4 entering the flue gas bypass 3 is greater than a preset temperature value. In this embodiment, the preset temperature value is 380°C.

[0103] In this embodiment, the flue gas bypass 3 further includes a first flow collection device 5, a first bypass regulating door 6, a second flow collection device 7 and a second bypass regulating door 8;

[0104] The first flow collection device 5 is used to collect the flow value of the exhaust steam in the first flue gas bypass branch 32;

[0105] The first bypass regulating gate 6 is used to adjust the flow rate of exhaust steam in the first flue gas bypass branch 32 according to the flow rate value collected by the first flow rate collection device 5;

[0106] The second flow rate collection device 7 is used to collect the flow value of the exhaust steam in the second flue gas bypass branch 33;

[0107] The second bypass regulating door 8 is used to regulate the exhaust steam generated by the gas turbine 1 flowing in the second flue gas bypass branch 33 .

[0108] In this embodiment, a deviation between the flow rate of exhaust steam generated by the gas turbine 1 in the first flue gas bypass branch 32 and the flow rate of exhaust steam generated by the gas turbine 1 flowing in the second flue gas bypass branch 33 is less than a preset deviation value.

[0109] Furthermore, the first bypass regulating door 6 and the second bypass regulating door 8 are electric regulating doors.

[0110] Specifically, the first bypass regulating gate 6 is used to regulate the exhaust steam flow in the first flue gas bypass branch 32, and the second bypass regulating gate 8 is used to regulate the exhaust steam flow in the second flue gas bypass branch 33, to ensure that the exhaust steam flow of the first and second small wind boxes 9 and the second and second small wind boxes 10 entering the total layer of the front and rear walls of the coal-fired boiler 2 are consistent.

[0111] In this embodiment, the denitration module includes a temperature acquisition device 12;

[0112] The temperature collection device 12 is used to collect the flue gas temperature value at the inlet of the denitration module.

[0113] In this embodiment, a shutoff door 16 is also provided in the flue gas bypass 3;

[0114] The shut-off door 16 is used to shut off the flue gas bypass 3 when the flue gas temperature value collected by the temperature collection device 12 reaches a preset temperature value.

[0115] Specifically, in this embodiment, the preset temperature value is 330° C. When the flue gas temperature at the inlet of the denitration module is stabilized at 330° C., the shutoff door 16 is closed to close the flue gas bypass 3 .

[0116] When the coal-fired boiler 2 is ignited and started, the shutoff door 16 is opened about 6 hours in advance, and the exhaust gas of the gas turbine 1 enters the boiler furnace through the two secondary small wind boxes in the middle layer of the coal-fired boiler 2 to heat the boiler heating surface, the denitration catalyst 11, etc. The pollutants of this part of the exhaust gas can be treated by the original denitration, dust removal, desulfurization and other equipment (i.e., denitration module) of the boiler, and will not cause environmental emission problems.

[0117] When the coal-fired boiler 2 is ignited, the burner of the lowest layer of the coal-fired boiler 2 is put into operation first. At this time, the flue gas temperature at the inlet of the denitrification module can be kept above the minimum operation temperature, and the denitrification module can be put into operation all the time. The exhaust gas of the gas turbine enters the furnace at the middle layer burner, and will not affect the combustion stability of the lower layer burner. When the flue gas temperature at the inlet of the denitrification module is stabilized at above 330°C, the shut-off door 16 is closed. At this time, the exhaust gas of the gas turbine no longer enters the coal-fired boiler 2, and the middle layer burner of the coal-fired boiler 2 is also ignited and put into operation. After the burner of the middle layer is ignited and put into operation, the flue gas temperature at the inlet of the denitrification module will only increase and not decrease. After the coal-fired unit is connected to the grid, the denitrification flue gas temperature can reach the minimum operation temperature.

[0118] Since the gas turbine 1 has a fast ignition speed, strong peak capacity and fast load change rate, the deep coupling between the gas turbine system and the coal-fired boiler 2 is conducive to the flexible peak regulation of the coal-fired unit and enhances the competitiveness of the coal-fired unit in the context of new power system construction.

[0119] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0120] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0121] The optional implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings. However, the implementation modes of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the implementation modes of the present invention, a variety of simple modifications can be made to the technical solutions of the implementation modes of the present invention, and these simple modifications all belong to the protection scope of the implementation modes of the present invention. It should also be noted that the various specific technical features described in the above specific implementation modes can be combined in any suitable manner without contradiction, and as long as the combination does not violate the concept of the implementation modes of the present invention, it should also be regarded as the content disclosed in the implementation modes of the present invention.

Claims

1. A system for coupling a gas-fired unit with a coal-fired unit to realize ignition and denitrification, characterized in that: include: Gas-fired units, coal-fired units, denitrification modules and flue gas bypass; The gas turbine of the gas-fired unit is connected to the coal-fired boiler of the coal-fired unit through the flue gas bypass, and the coal-fired boiler is connected to the denitration module; The flue gas bypass is used to input the exhaust steam generated by the gas turbine of the gas unit within a preset time period before the ignition of the coal-fired unit, and output the exhaust steam to the coal-fired boiler of the coal-fired unit. The exhaust steam is used to heat the coal-fired boiler in advance and to heat the denitration catalyst in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

2. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 1 is characterized in that: The flue gas bypass includes a main flue gas bypass, a first flue gas bypass branch and a second flue gas bypass branch; The input end of the main flue gas bypass is used to input the exhaust steam, and the output end of the main flue gas bypass is respectively connected to the input end of the first flue gas bypass branch and the input end of the second flue gas bypass branch; The output end of the first flue gas bypass branch is connected to the first and second small wind boxes located in the middle layer of the coal-fired boiler, and the output end of the second flue gas bypass branch is connected to the second and second small wind boxes located in the middle layer of the coal-fired boiler. The flue gas bypass transports the exhaust steam generated by the gas turbine to the coal-fired boiler through the first and second small wind boxes.

3. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 2 is characterized in that: The gas unit further comprises: a waste heat boiler; The input end of the waste heat boiler is connected to the output end of the gas turbine for receiving exhaust steam generated by the gas turbine; The input end of the flue gas bypass is connected to the waste heat boiler and is used to receive exhaust steam from the gas turbine of the waste heat boiler.

4. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 3 is characterized in that: The temperature of the exhaust steam of the gas turbine input to the input end of the flue gas bypass is greater than a preset temperature.

5. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 2 is characterized in that: The flue gas bypass also includes a first flow collection device, a first bypass regulating door, a second flow collection device and a second bypass regulating door; The first flow collection device is used to collect the flow value of the exhaust steam in the first flue gas bypass branch; The first bypass regulating gate is used to adjust the flow rate of exhaust steam in the first flue gas bypass branch according to the flow rate value collected by the first flow rate collection device; The second flow rate collection device is used to collect the flow value of the exhaust steam in the second flue gas bypass branch; The second bypass regulating door is used to regulate the exhaust steam generated by the gas turbine flowing in the second flue gas bypass branch.

6. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 5 is characterized in that: A deviation between a flow rate of exhaust steam generated by the gas turbine in the first flue gas bypass branch and a flow rate of exhaust steam generated by the gas turbine flowing in the second flue gas bypass branch is less than a preset deviation value.

7. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 1 is characterized in that: The denitration module includes a temperature collection device; The temperature collection device is used to collect the flue gas temperature value at the inlet of the denitration module.

8. The system for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 7 is characterized in that: A shut-off door is provided in the flue gas bypass; The shut-off door is used to shut off the flue gas bypass when the flue gas temperature value collected by the temperature collection device reaches a preset temperature value.

9. A method for realizing ignition and denitrification by coupling a gas-fired unit with a coal-fired unit, characterized in that: include: In a preset time period before the ignition of the coal-fired unit, the exhaust steam generated by the gas turbine in the gas-fired unit enters the coal-fired boiler of the coal-fired unit through the flue gas bypass; The heat of the exhaust steam generated by the gas turbine is used to heat the coal-fired boiler and the denitration catalyst in the denitration module, so that the denitration module can be put into use immediately when the coal-fired unit is ignited.

10. The method for realizing ignition and denitrification of a gas-fired unit coupled with a coal-fired unit according to claim 9, characterized in that: The method further comprises: When the flue gas temperature at the inlet of the denitration module reaches a preset temperature value, the flue gas bypass is shut down and the coal-fired unit is connected to the grid for operation.

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