Secondary reheating unit coupling biomass parallel blending combustion device

Abstract

The invention discloses a secondary reheat unit coupled biomass parallel blending combustion device, which comprises a biomass circulating fluidized bed boiler, a connecting flue, a secondary reheat boiler and a steam pressure cylinder, the biomass circulating fluidized bed boiler is provided with a biomass bin and a water bin which are separated from each other, biomass burns in the biomass bin to heat water liquid in the water bin into steam, the biomass bin communicates with the secondary reheating boiler through the connecting flue, flue gas generated by the biomass in the biomass bin is used for being conveyed towards the secondary reheating boiler, the water bin communicates with the steam pressure cylinder, and the steam pressure cylinder is used for conveying the flue gas to the secondary reheating boiler. Steam in the water sump is used for being conveyed towards the steam pressure cylinder. The secondary reheat unit coupling biomass parallel blending combustion device not only can realize blending combustion of biomass in a traditional coal power unit, but also can solve the problem of low steam temperature of an existing secondary reheat unit by utilizing biomass flue gas.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass co-firing, and in particular to a device for coupling biomass parallel co-firing in a secondary reheat unit. Background Art

[0002] In related technologies, the problem of low steam temperature at low load exists in all secondary reheat units, which seriously affects the economy of secondary reheat units. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, an object of the present invention is to provide a device for coupling biomass parallel co-firing in a secondary reheat unit. The device for coupling biomass parallel co-firing in a secondary reheat unit can not only realize the co-firing of biomass in a traditional coal-fired power unit, but also use the biomass flue gas to solve the problem of low steam temperature in the existing secondary reheat unit.

[0004] According to an embodiment of the present invention, the device for coupling biomass parallel co-firing in a secondary reheat unit includes: a biomass circulating fluidized bed boiler, a connecting flue, a secondary reheat boiler, and a steam cylinder. The biomass circulating fluidized bed boiler has a separated biomass bin and a water bin. Biomass is burned in the biomass bin to heat the water liquid in the water bin into steam. The biomass bin is communicated with the secondary reheat boiler through the connecting flue. The flue gas generated by the biomass in the biomass bin is used to be transported towards the secondary reheat boiler. The water bin is communicated with the steam cylinder, and the steam in the water bin is used to be transported towards the steam cylinder.

[0005] According to an embodiment of the present invention, burning biomass in the biomass bin can heat the water liquid in the water bin into steam, and the generated steam can be transported towards the steam cylinder, thereby providing heat energy for the steam turbine system of the power station boiler, which is beneficial to power generation. The flue gas generated by biomass combustion can make up for the problem of low flue gas volume in the secondary reheat boiler at low load, increase the convective heat absorption, and improve the reheat steam temperature of the secondary reheat boiler at low load. Therefore, it can not only realize the co-firing of biomass in a traditional coal-fired power unit, but also use the biomass flue gas to solve the problem of low steam temperature in the existing secondary reheat boiler.

[0006] In some embodiments of the present invention, the device for coupling biomass parallel co-firing in a secondary reheat unit further includes: a flue gas circulation fan, which is located in the connecting flue and is used to transport the flue gas generated by the biomass in the biomass bin towards the secondary reheat boiler.

[0007] In some embodiments of the present invention, the double reheat boiler includes a platen superheater, a first reheat medium-temperature stage, a high-temperature superheater, a second reheat high-temperature stage, a first reheat high-temperature stage, a first reheater, a second reheat low-temperature stage, a low-temperature superheater, and an economizer. Among them, after the flue gas transported towards the double reheat boiler through the connecting flue is mixed with the flue gas inside the double reheat boiler, it sequentially passes through the platen superheater, the first reheat medium-temperature stage, the high-temperature superheater, the second reheat high-temperature stage, the first reheat high-temperature stage, the first reheater, the second reheat low-temperature stage, the low-temperature superheater, and the economizer.

[0008] In some embodiments of the present invention, there is a communication area inside the double reheat boiler. The communication area is located below the overfire air of the double reheat boiler, and the connecting flue is communicated with the communication area.

[0009] In some embodiments of the present invention, there is also a main combustion area inside the double reheat boiler. Coal is burned in the main combustion area, and the communication area is located between the main combustion area and the overfire air.

[0010] In some embodiments of the present invention, the biomass burned in the biomass bin includes wood chips and straw.

[0011] In some embodiments of the present invention, the steam cylinder includes an intermediate-pressure cylinder, a low-pressure cylinder, a connecting pipe, and a control valve. The connecting pipe includes a first pipeline and a second pipeline. The intermediate-pressure cylinder is communicated with the water tank through the first pipeline, the low-pressure cylinder is communicated with the water tank through the second pipeline, and the control valve is arranged between the connecting pipe and the water tank for controlling the conduction of the first pipeline or the second pipeline with the water tank.

[0012] In some embodiments of the present invention, it further includes a temperature sensor, a pressure sensor, and a controller. The temperature sensor and the pressure sensor are both arranged at the steam outlet of the water tank. The controller is used to control the control valve to conduct the first pipeline with the water tank or conduct the second pipeline with the water tank according to the detection data of the temperature sensor and the pressure sensor.

[0013] In some embodiments of the present invention, the biomass circulating fluidized bed boiler is a circulating fluidized bed boiler or a grate furnace.

[0014] In some embodiments of the present invention, the double reheat boiler is an opposed fired boiler, a tangentially fired boiler with four corners, or a single furnace chamber double tangentially fired boiler.

[0015] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0017] Figure 1 is a schematic structural diagram of a biomass parallel co-firing device coupled with a secondary reheat unit according to some embodiments of the present invention.

[0018] Reference numerals:

[0019] 1. Biomass circulating fluidized bed boiler; 2. Connecting flue; 3. Flue gas circulating fan; 4. Platen superheater; 5. First reheat medium temperature stage; 6. High temperature superheater; 7. Second reheat high temperature stage; 8. First reheat high temperature stage; 9. First reheater; 10. Second reheat low temperature stage; 11. Low temperature superheater; 12. Economizer; 13. Intermediate pressure cylinder; 14. Low pressure cylinder. Detailed description of the embodiments

[0020] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0022] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] There are mainly three ways to co - fire biomass in pulverized coal boilers, specifically including direct co - firing, gasification co - firing, and parallel co - firing. In related technologies, there are already demonstration projects and applications for direct co - firing and gasification co - firing. However, due to reasons such as high initial investment, there is no engineering demonstration for parallel co - firing. Parallel co - firing can further increase the co - firing ratio, can adapt to a variety of biomass raw materials, can send the steam generated by the biomass boiler into the steam turbine system, and has no adverse effect on the original boiler system. At the same time, in the related technologies, all secondary reheat units have the problem of low steam temperature at low load. With the trend of deep peak shaving, this problem has become increasingly prominent, seriously affecting the economy of secondary reheat units. Biomass parallel co - firing can not only generate steam to be coupled with the original steam turbine system, but also the flue gas generated by biomass combustion can make up for the problem of low flue gas volume in the secondary reheat unit at low load, increase the convective heat absorption, and improve the reheat steam temperature of the secondary reheat unit at low load. Therefore, it is necessary to provide a technical solution that can realize the deep coupling of biomass co - firing and secondary reheat units, which can not only realize the co - firing of biomass in traditional coal - fired power units, but also use biomass flue gas to solve the problem of low steam temperature in existing secondary reheat units.

[0024] The following refers to Figure 1 Describe the device for coupling biomass parallel co - firing with a secondary reheat unit according to an embodiment of the present invention.

[0025] The device for coupling biomass parallel co - firing with a secondary reheat unit according to an embodiment of the present invention includes: a biomass circulating fluidized bed boiler 1, a connecting flue 2, a secondary reheat boiler, and a steam cylinder. The biomass circulating fluidized bed boiler 1 has a separated biomass bin and a water bin. Biomass is burned in the biomass bin to heat the water liquid in the water bin into steam. The biomass bin is connected to the secondary reheat boiler through the connecting flue 2. The flue gas generated by the biomass in the biomass bin is used to be transported towards the secondary reheat boiler. The water bin is connected to the steam cylinder, and the steam in the water bin is used to be transported towards the steam cylinder.

[0026] That is to say, burning biomass in the biomass bin can heat the water liquid in the water bin into steam, and the generated steam can be transported towards the steam cylinder, thereby providing heat energy for the steam turbine system of the power station boiler, which is beneficial for power generation. The flue gas generated by biomass combustion can make up for the problem of low flue gas volume in the secondary reheat boiler at low load, increase the convective heat absorption, and improve the reheat steam temperature of the secondary reheat boiler at low load. Therefore, it can not only realize the co - firing of biomass in traditional coal - fired power units, but also use biomass flue gas to solve the problem of low steam temperature in existing secondary reheat boilers.

[0027] The flue gas generated by the biomass circulating fluidized bed boiler 1 is sent into the secondary reheat boiler, increasing the flue gas volume and flue gas enthalpy value, which can improve the reheat steam temperature of the secondary reheat boiler at low load.

[0028] According to the biomass parallel co-firing device coupled with a secondary reheat unit in an embodiment of the present invention, the biomass burned in the biomass bin can heat the water liquid in the water bin into steam, and the generated steam can be transported towards the steam cylinder, thereby providing heat energy for the steam turbine system of the power plant boiler, which is conducive to power generation. The flue gas generated by biomass combustion can make up for the problem of low flue gas volume in the secondary reheat boiler under low load, increase the convective heat absorption, and improve the reheat steam temperature of the secondary reheat boiler under low load. Therefore, not only can the traditional coal-fired power unit co-fire biomass, but also the problem of low steam temperature of the existing secondary reheat boiler can be solved by using biomass flue gas.

[0029] In some embodiments of the present invention, the biomass parallel co-firing device coupled with a secondary reheat unit further includes: a flue gas circulation fan 3, which is located in the connecting flue 2 and is used to transport the flue gas generated by the biomass in the biomass bin towards the secondary reheat boiler.

[0030] That is to say, the biomass circulating fluidized bed boiler 1 is connected to the secondary reheat boiler through the connecting flue 2, and the flue gas circulation fan 3 provides the power for the flue gas to enter the secondary reheat boiler.

[0031] In some embodiments of the present invention, the secondary reheat boiler includes a platen superheater 4, a primary reheat medium temperature stage 5, a high-temperature superheater 6, a secondary reheat high temperature stage 7, a primary reheat high temperature stage 8, a primary reheater 9, a secondary reheat low temperature stage, a low-temperature superheater, and an economizer. Among them, after the flue gas transported towards the secondary reheat boiler through the connecting flue 2 is mixed with the flue gas in the secondary reheat boiler, it successively passes through the platen superheater 4, the primary reheat medium temperature stage 5, the high-temperature superheater 6, the secondary reheat high temperature stage 7, the primary reheat high temperature stage 8, the primary reheater 9, the secondary reheat low temperature stage 10, the low-temperature superheater 11, and the economizer 12.

[0032] In some embodiments of the present invention, there is a communication area in the secondary reheat boiler. The communication area is located below the overfire air of the secondary reheat boiler, and the connecting flue 2 is communicated with the communication area. The biomass flue gas is sent into the area below the overfire air of the secondary reheat boiler and is not sent into the main combustion area to affect the combustion stability.

[0033] In some embodiments of the present invention, there is also a main combustion area in the secondary reheat boiler, where coal is burned, and the communication area is located between the main combustion area and the overfire air.

[0034] In some embodiments of the present invention, the biomass burned in the biomass bin includes wood chips and straw. Biomass particles such as wood chips and straw are burned separately outside the secondary reheat boiler and are not directly incorporated into the secondary reheat boiler. The proportion of biomass co-firing is higher than that of direct co-firing and gasification co-firing, and large-scale biomass co-firing in a pulverized coal boiler can be achieved.

[0035] In some embodiments of the present invention, the steam cylinder includes a medium-pressure cylinder 13, a low-pressure cylinder 14, a connecting pipe, and a control valve. The connecting pipe includes a first pipeline and a second pipeline. The medium-pressure cylinder 13 is connected to the water sump through the first pipeline, and the low-pressure cylinder 14 is connected to the water sump through the second pipeline. The control valve is arranged between the connecting pipe and the water sump and is used to control the conduction of the first pipeline or the second pipeline with the water sump.

[0036] In some embodiments of the present invention, the secondary reheat unit coupled with the biomass parallel co-firing device further includes a temperature sensor, a pressure sensor, and a controller. The temperature sensor and the pressure sensor are both arranged at the steam outlet of the water sump. The controller is used to control the control valve to conduct the first pipeline with the water sump or the second pipeline with the water sump according to the detection data of the temperature sensor and the pressure sensor.

[0037] Exemplarily, when the steam pressure is about 3 MPa and the temperature is between 520 - 620 °C, the steam is sent into the medium-pressure cylinder; when the steam pressure is about 0.5 MPa and the temperature is between 320 - 340 °C, the steam is sent into the low-pressure cylinder; when the steam temperature is lower than 320 °C, the steam is sent into the corresponding heater according to the steam pressure to heat the feed water. That is, the controller can judge and control the steam to be sent into the corresponding system according to the steam parameters of the biomass circulating fluidized bed boiler 1.

[0038] In some embodiments of the present invention, the biomass circulating fluidized bed boiler 1 is a circulating fluidized bed boiler or a grate boiler.

[0039] In some embodiments of the present invention, the secondary reheat boiler is an opposed firing boiler, a tangentially fired boiler with four corners, or a single furnace chamber double tangentially fired boiler. For the opposed firing boiler, the biomass flue gas is sent in from both side walls and below the burnout air. For the tangentially fired boiler with four corners, the biomass flue gas is sent in from the four side walls and below the burnout air.

[0040] In some embodiments of the present invention, for the secondary reheat unit coupled with the biomass parallel co-firing device, at high load, the biomass boiler co-firing amount is reduced, and the biomass flue gas amount is controlled to be lower than 5% of the total flue gas amount; at low load, the biomass boiler co-firing amount is increased, and the total biomass flue gas amount accounts for not less than 30% of the total flue gas amount.

[0041] In some embodiments of the present invention, the control system can automatically adjust the biomass co-firing amount according to the main and reheat steam temperatures of the secondary reheat boiler, so as to control the biomass flue gas amount entering the secondary reheat boiler.

[0042] In some embodiments of the present invention, the biomass circulating fluidized bed boiler 1 can be coupled with a 1000 MW secondary reheat boiler or a 660 MW secondary reheat boiler.

[0043] Reference Figure 1Describe the biomass parallel co-firing device coupled with a secondary reheat unit of the present application for a specific embodiment.

[0044] The biomass parallel co-firing device coupled with a secondary reheat unit includes a biomass circulating fluidized bed boiler 1, a connecting flue 2, a flue gas circulating fan 3, a platen superheater 4, a first reheat medium temperature stage 5, a high temperature superheater 6, a second reheat high temperature stage 7, a first reheat high temperature stage 8, a first reheater 9, a second reheat low temperature stage 10, a low temperature superheater 11, an economizer 12, an intermediate pressure cylinder 13, and a low pressure cylinder 14. Biomass particles such as wood chips and straw are burned in the biomass circulating fluidized bed boiler 1. According to different biomass input amounts, the power of the biomass circulating fluidized bed boiler 1 is different, generating flue gas at different temperatures and steam at different temperatures and pressures. The biomass circulating fluidized bed boiler 1 is connected to the secondary reheat boiler through the connecting flue 2, and the high temperature flue gas in the biomass circulating fluidized bed boiler 1 is sent into the secondary reheat boiler through the flue gas circulating fan 3.

[0045] The biomass flue gas sequentially passes through the heating surfaces of the platen superheater 4, the first reheat medium temperature stage 5, the high temperature superheater 6, the second reheat high temperature stage 7, the first reheat high temperature stage 8, the first reheater 9, the second reheat low temperature stage 10, the low temperature superheater 11, and the economizer 12, solving the problem of low steam temperature in the secondary reheat boiler due to insufficient flue gas volume under low load.

[0046] The water tank is connected to the steam cylinder, and the steam in the water tank is used to be transported towards the steam cylinder. According to the temperature and pressure of the steam, it is decided whether to send it into the intermediate pressure cylinder or the low pressure cylinder. When the power of the biomass circulating fluidized bed boiler 1 is small, the generated steam is difficult to reach the requirements of the low pressure cylinder 14, then the generated steam is used to heat the feed water, reducing the extraction steam of the original steam turbine system. Through the double parallel connection of the flue gas system and the steam-water system, the co-firing of biomass in a traditional secondary reheat coal-fired power unit is realized, providing a technical route for biomass parallel co-firing to reduce carbon.

[0047] Biomass particles such as wood chips and straw are burned in the biomass circulating fluidized bed boiler 1. According to different biomass input amounts, the power of the biomass circulating fluidized bed boiler 1 is different, generating flue gas at different temperatures and steam at different temperatures and pressures.

[0048] Other components and operations of the biomass parallel co-firing device coupled with a secondary reheat unit according to the embodiments of the present invention are known to those of ordinary skill in the art and will not be described in detail here.

[0049] In the description of this specification, the descriptions referring to terms such as "some embodiments", "optionally", "furthermore" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0050] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A coupling biomass parallel co-firing device for a secondary reheat unit, characterized in that, Comprising: A biomass circulating fluidized bed boiler, a connecting flue, a secondary reheat boiler, and a steam cylinder, The biomass circulating fluidized bed boiler has a separated biomass bin and a water bin. Biomass is burned in the biomass bin to heat the water liquid in the water bin into steam. The biomass bin is communicated with the secondary reheat boiler through the connecting flue. The flue gas generated by the biomass in the biomass bin is used to be conveyed towards the secondary reheat boiler. The water bin is communicated with the steam cylinder. The steam in the water bin is used to be conveyed towards the steam cylinder.

2. The secondary reheat unit coupled biomass parallel co-firing device according to claim 1, wherein, Also comprising: A flue gas circulation fan, which is located in the connecting flue and is used to convey the flue gas generated by the biomass in the biomass bin towards the secondary reheat boiler.

3. The biomass parallel co-firing device coupled with a secondary reheat unit according to claim 1, wherein The secondary reheat boiler includes a platen superheater, a first reheat medium-temperature stage, a high-temperature superheater, a secondary reheat high-temperature stage, a first reheat high-temperature stage, a first reheater, a secondary reheat low-temperature stage, a low-temperature superheater, and an economizer. Among them, After the flue gas conveyed towards the secondary reheat boiler through the connecting flue is mixed with the flue gas in the secondary reheat boiler, it sequentially passes through the platen superheater, the first reheat medium-temperature stage, the high-temperature superheater, the secondary reheat high-temperature stage, the first reheat high-temperature stage, the first reheater, the secondary reheat low-temperature stage, the low-temperature superheater, and the economizer.

4. The secondary reheat unit coupled biomass parallel co-firing device according to claim 1, characterized in that, There is a communication area in the secondary reheat boiler. The communication area is located below the overfire air of the secondary reheat boiler. The connecting flue is communicated with the communication area.

5. The secondary reheat unit coupled biomass parallel co-firing device according to claim 4, characterized in that, There is also a main combustion area in the secondary reheat boiler. Coal is burned in the main combustion area. The communication area is located between the main combustion area and the overfire air.

6. The biomass parallel co-firing device coupled with a secondary reheat unit according to claim 1, characterized in that The biomass burned in the biomass bin includes wood chips and straw.

7. The secondary reheat unit coupled biomass parallel co-firing device according to claim 1, wherein, The steam cylinder includes an intermediate pressure cylinder, a low pressure cylinder, a connecting pipe, and a control valve. The connecting pipe includes a first pipeline and a second pipeline. The intermediate pressure cylinder is communicated with the water bin through the first pipeline. The low pressure cylinder is communicated with the water bin through the second pipeline. The control valve is arranged between the connecting pipe and the water bin and is used to control the conduction of the first pipeline or the second pipeline with the water bin.

8. The biomass parallel co-firing device coupled with a secondary reheat unit according to claim 7, wherein, Also including a temperature sensor, a pressure sensor, and a controller. The temperature sensor and the pressure sensor are both arranged at the steam outlet of the water bin. The controller is used to control the control valve to conduct the first pipeline with the water bin or conduct the second pipeline with the water bin according to the detection data of the temperature sensor and the pressure sensor.

9. The secondary reheat unit coupled biomass parallel co-firing device according to claim 1, characterized in that, The biomass circulating fluidized bed boiler is a circulating fluidized bed boiler or a grate furnace.

10. The biomass parallel co-firing device coupled with a secondary reheat unit according to claim 1, wherein The secondary reheat boiler is an opposed fired boiler, a tangentially fired boiler, or a single furnace chamber double tangentially fired boiler.

Images