KR-102962598-B1 - CIRCULATING FLUIDIZED BED BOILER USING QUICKLIME AND METHOD FOR OPERATING THE SAME

KR102962598B1KR 102962598 B1KR102962598 B1KR 102962598B1KR-102962598-B1

Abstract

The present invention provides a circulating fluidized bed boiler using quicklime and a method for operating the same. The method for operating the circulating fluidized bed boiler comprises: i) a step of supplying fuel, a circulating medium, quicklime, and steam to a combustion furnace; ii) a step of heating the circulating medium as the fuel is combusted; iii) a step of further heating the circulating medium as calcium hydroxide is produced by the release of heat from the reaction between quicklime and steam; iv) a step of supplying the circulating medium to a heat exchanger connected to the combustion furnace, and then charging it into the combustion furnace after heat exchange; v) a step of discharging and storing calcium hydroxide by gravity drop; and vi) a step of supplying calcium hydroxide to the combustion furnace or heat exchanger when the output of the circulating fluidized bed boiler is reduced.

Inventors

이규화
이종민
김동원
박상빈
박경일

Assignees

한국전력공사

Dates

Publication Date: 20260512
Application Date: 20220520

Claims (17)

As a method of operating a circulating fluidized bed boiler, Step of providing fuel, circulating medium, quicklime, and steam to a combustion furnace, A step of heating the circulating medium as the fuel burns, A step of further heating the circulation medium as heat is released from the reaction between the quicklime and the steam to generate calcium hydroxide, A step in which the above-mentioned circulating medium is supplied to a heat exchanger connected to the combustion furnace, heat exchanged, and then charged into the combustion furnace, A step in which the above calcium hydroxide is discharged externally and stored by gravity fall, and When reducing the output of the above-mentioned circulating fluidized bed boiler, the step of providing the above-mentioned calcium hydroxide to the combustion furnace or the above-mentioned heat exchanger A method of operating a circulating fluidized bed boiler including
In Paragraph 1, A method of operating a circulating fluidized bed boiler, wherein, in the step of providing the calcium hydroxide to the combustion furnace or the heat exchanger, the calcium hydroxide is provided to the combustion furnace, and the calcium hydroxide is converted into another quicklime and reacts with the sulfur oxide generated by the combustion of the fuel to remove the sulfur oxide.
In Paragraph 1, A method of operating a circulating fluidized bed boiler in the step of providing the calcium hydroxide to the combustion furnace or the heat exchanger, wherein the calcium hydroxide is converted into another quicklime in the combustion furnace or the heat exchanger and used as the circulating medium.
In Paragraph 1, A method of operating a circulating fluidized bed boiler, wherein, in the step of providing the calcium hydroxide to the combustion furnace or the heat exchanger, the calcium hydroxide is provided to the combustion furnace, and the calcium hydroxide is charged into the combustion furnace at a position higher than the circulating medium.
In Paragraph 1, In the step of providing the calcium hydroxide to the combustion furnace or the heat exchanger, the calcium hydroxide is connected to the combustion furnace and is loaded into the combustion furnace through a calcium hydroxide transfer pipe equipped with a first gate valve, and In the step where the above-mentioned circulation medium is charged into the combustion furnace, the above-mentioned circulation medium is supplied to the heat exchanger through a circulation medium transfer pipe equipped with a second gate valve. A method of operating a circulating fluidized bed boiler in which the calcium hydroxide transfer pipe and the circulating medium transfer pipe are connected in an intersecting manner.
In paragraph 5, A method of operating a circulating fluidized bed boiler in which the calcium hydroxide is transferred to the combustion furnace side while rising and falling through the calcium hydroxide transfer pipe.
In paragraph 5, A method of operating a circulating fluidized bed boiler in which, when the calcium hydroxide is supplied to the combustion furnace, the first gate valve is opened and the second gate valve is closed.
In paragraph 5, A method of operating a circulating fluidized bed boiler in which, when the calcium hydroxide is supplied to the heat exchanger, the first gate valve is closed and the second gate valve is opened.
In paragraph 1, A method of operating a circulating fluidized bed boiler in which, in the step where the calcium hydroxide falls by gravity and is discharged to the outside for storage, the calcium hydroxide is stored at a position higher than the external discharge location.
In Paragraph 1, A method of operating a circulating fluidized bed boiler in which, at the step in which the circulating medium is charged into the combustion furnace, a portion of another steam generated by heat exchange with the circulating medium in the heat exchanger is provided as the steam.
Step of providing fuel, circulating medium, quicklime, and steam to a combustion furnace, A step of heating the circulating medium as the fuel burns, A step of further heating the circulation medium as heat is released from the reaction between the quicklime and the steam to generate calcium hydroxide, A step in which the above-mentioned circulating medium is discharged to a heat exchanger connected to the combustion furnace, heat exchanged, and then charged into the combustion furnace, and The step in which the above calcium hydroxide falls by gravity and is discharged externally and stored. Includes, A method of operating a circulating fluidized bed boiler in the step of providing the above fuel, circulating medium, quicklime, and steam to a combustion furnace, wherein the quicklime and steam are provided at the time of starting an ignition burner installed in the combustion furnace.
A combustion furnace supplied with fuel, a circulating medium, quicklime, and steam, respectively A cyclone connected to the above combustion furnace to separate the combustion gas discharged from the above combustion furnace and the heated circulating medium, A heat exchanger connected to the above cyclone and generating steam through heat exchange with the above heated circulating medium, A circulation medium transfer pipe connected to the above heat exchanger for charging the above circulation medium, after heat exchange is completed, into the above combustion furnace, A calcium hydroxide storage tank connected to the lower part of the combustion furnace and storing calcium hydroxide produced by the reaction of the quicklime and the steam from the combustion, A calcium hydroxide transfer pipe connected to the side of the calcium hydroxide storage tank and the combustion furnace to transfer the calcium hydroxide from the calcium hydroxide storage tank to the combustion furnace, and A circulation medium transfer pipe that is cross-connected with the calcium hydroxide transfer pipe and connected to the cyclone and the heat exchanger to transfer the circulation medium from the cyclone to the heat exchanger. A circulating fluidized bed boiler including
In Paragraph 12, The above calcium hydroxide transfer pipe is, Ascending part and The descending part connected to the above-mentioned rising part Includes, The above-mentioned descending section is inclined and connected to the combustion chamber in a circulating fluidized bed boiler.
In Paragraph 13, The above-mentioned descending section is a circulating fluidized bed boiler located above the above-mentioned circulating medium transfer pipe.
In Paragraph 12, A circulating fluidized bed boiler in which a first gate valve is installed in the calcium hydroxide transfer pipe and a second gate valve is installed in the circulating medium transfer pipe.
In Paragraph 12, A circulating fluidized bed boiler in which a heater capable of heating the calcium hydroxide is installed in the heat exchanger.
In Paragraph 12, A circulating fluidized bed boiler further comprising a steam supply pipe connected to the combustion furnace to supply steam to the combustion furnace, wherein the heat exchanger is connected to the steam supply pipe to supply the steam.

Description

Circulating Fluidized Bed Boiler Using Quicklime and Method for Operating the Same The present invention relates to a circulating fluidized bed boiler and a method of operating the same. More specifically, the present invention relates to a circulating fluidized bed boiler using quicklime and a method of operating the same. Renewable energy generation experiences significant fluctuations in output due to external environmental factors. Consequently, as the proportion of renewable energy generation increases, the responsiveness of existing power sources is becoming increasingly important for ensuring stable power supply. One such existing power source is the circulating fluidized bed boiler (CFB). The CFB was developed to burn low-grade coal with high ash content. Because the CFB generates power by burning various fuels—such as low-grade coal, biomass, and waste—with high efficiency, it is the most environmentally friendly among conventional boilers. A circulating fluidized bed boiler utilizes a material bed formed from fuel, limestone, sand, etc. Here, limestone and sand are used for desulfurization. The material bed is combusted in the combustion chamber included in the circulating fluidized bed boiler. Then, a particle separator is used to separate the material bed from the exhaust gas, and the material bed is recirculated to heat the water inside the tubes surrounding the combustion chamber, converting it into high-pressure steam to drive a turbine and generate electricity. FIG. 1 is a schematic diagram showing the energy flow during the operation of a circulating fluidized bed boiler according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a circulating fluidized bed boiler according to one embodiment of the present invention. FIGS. 3 to 5 are schematic diagrams of various operating methods of the circulating fluidized bed boiler of FIG. 2. FIG. 6 is a schematic flowchart of a method for operating a circulating fluidized bed boiler according to one embodiment of the present invention. Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. FIG. 1 schematically illustrates the energy flow during the operation of a circulating fluidized bed boiler according to one embodiment of the present invention. The energy flow of FIG. 1 is merely for illustrating the present invention and is not limited thereto. Accordingly, the energy flow of FIG. 1 may be modified differently. When output evaporation is required in a circulating fluidized bed boiler, quicklime (CaO) and steam are supplied to the combustion furnace as energy separately from the fuel and circulating medium. In this case, the reversible reaction of Chemical Formula 1 below proceeds. [Chemical Formula 1] CaO (s) + H 2 O → Ca(OH) 2 (s), △H 298 K = - 109 kJ/mol The heat generated by the reaction between quicklime and steam in Chemical Formula 1 supplies energy to the combustion furnace. And the calcium hydroxide (Ca(OH) ₂ ) produced by the reaction between quicklime and steam is stored in a calcium hydroxide storage tank. Conversely, when a reduction in the output of a circulating fluidized bed boiler is required, the calcium hydroxide stored in the calcium hydroxide storage tank is supplied to a combustion furnace or heat exchanger. In this case, the calcium hydroxide decomposes into quicklime according to Chemical Formula 2 below. [Chemical Formula 2] Ca(OH)2 (s) → CaO (s) + H 2 O , △H 298 K = 65.2 kJ/mol Calcium hydroxide decomposes into quicklime and steam according to the endothermic reaction of Chemical Formula 2, which is the reverse reaction of Chemical Formula 1, absorbing heat from the circulating medium and water-cooled walls within the combustion furnace. Additionally, through this reaction, heat is also absorbed from the circulating medium and tubes inside the heat exchanger located outside the combustion furnace. Quicklime can be delivered to the combustion furnace and used as a desulfurization material to remove sulfur from the combustion furnace by reacting with sulfur oxides generated due to sulfur components contained in the fuel. As shown in FIG. 1, quicklime can be supplied back to the combustion furnace and used as a circulation medium. In addition, if boiler output evaporation is required, steam can be supplied to the quicklime to carry out the exothermic reaction of the aforementioned chemical formula 1. As described above, in one embodiment of the present invention, the output evaporation and output reduction of a circu