JP2019105399A - Limestone preliminary supply facility for circulating fluidized bed boiler and preliminary supply method - Google Patents

Abstract

To provide a small limestone preliminary supply facility which can be easily installed without being almost subjected to constraints of an installation location.SOLUTION: A limestone preliminary supply facility for a CFB boiler 1 comprises ejectors 12 and 22 provided in air transport systems 13 and 23 communicating with a furnace of a CFB boiler 1, and hoppers 11 and 21 for limestone storage communicating with the ejectors 12 and 22 via flow rate restriction means 11a or 21a such as a slide damper. Preferably, the ejectors 12 and 22 are provided in each of a first bypass piping system 13 bypassing a connection part of a limestone quantitative clipping device 3a in a limestone air transport piping system 4 which continuously supplies limestones, and a second bypass piping system 23 bypassing a connection part of a fluid material quantitative clipping device 6a in a fluid material air transport piping system 7 which periodically supplies fluid materials.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a limestone pre-supplying system used at the time of stopping a limestone supplying system provided in connection with a circulating fluidized bed boiler and a method of pre-supplying limestone using the same.

  For example, as described in Patent Document 1, a circulating fluidized bed boiler (hereinafter referred to as "CFB boiler") collects fluid sand and fuel ejected from the top of a furnace (combuster) with a cyclone, and again collects the fluidized sand and fuel. It is structured to be returned to the furnace and can increase the gas velocity (empty velocity) in the furnace compared to a Bubbling Fluidized Bed boiler, so that the mixing of particles and gas in the furnace is activated. It is possible to improve the combustion efficiency.

Moreover, since the combustion temperature in a furnace is 1,400-1,500 degreeC in a general boiler, since it can be restrained to about 800-900 degreeC in CFB boiler, it generate | occur | produces depending on a combustion temperature The generation amount of thermal NO _X can be suppressed. Furthermore, in the CFB boiler, by supplying limestone as a desulfurization agent in the furnace, the desulfurization reaction shown in the following reaction formula 1 can be generated in the furnace, so the flue gas desulfurization device becomes unnecessary or simplified It is possible to do with the desulfurization device which
[Reaction Formula 1]
CaCO ₃ + SO ₂ + 1 / 2O ₂ → CaSO ₄ + CO ₂

Japanese Patent Laid-Open No. 6-281108

As a feed facility of limestone as a desulfurization agent as described above, CFB boiler generally transports silo that stores limestone and limestone cut out via a quantitative extraction device provided at the bottom to the CFB boiler In many cases, a system is provided, and in the transport apparatus, there is often adopted a method of continuously supplying the inside of a furnace of a CFB boiler by pneumatic transport using compressed air as a transport medium. If this limestone supply facility is shut down due to equipment failure or pipe blockage, desulfurization will not be performed in the furnace, so the SO _X concentration in the exhaust gas will rise, and the exhaust gas containing SO _X exceeding the regulation value will be released to the atmosphere. There was a risk of In order to avoid such environmental problems, it is desirable for CFB boilers to have a backup facility that can continue the limestone supply even when the limestone supply facility is shut down.

  However, providing a facility having the same specifications as the above-described limestone supply facility including the silo, the quantitative extraction device, and the transfer device as a backup facility results in high investment cost. In addition, it is often difficult to add one series of equipment with the same specifications as the existing limestone supply equipment due to restrictions on the installation location. The present invention has been made in view of the above-described conventional problems, and it is an object of the present invention to provide a small-sized limestone spare supply facility which can be easily installed without being limited by the installation location.

  In order to achieve the above-mentioned object, the limestone reserve supply facility according to the present invention comprises an ejector provided in an air transport system in communication with a furnace of a CFB boiler, and limestone storage in communication with the ejector via a flow rate limiting means. And a hopper.

Further, the method for preliminarily supplying limestone according to the present invention is a method for preliminarily supplying limestone to a CFB boiler by introducing compressed air to an ejector provided through a flow rate limiting means at a lower portion of a hopper storing limestone. The opening degree of the flow rate limiting means is adjusted based on the SO _X concentration in the exhaust gas from the CFB boiler.

  According to the present invention, it is possible to easily install a small and inexpensive spare limestone supply facility with almost no restriction on the installation location.

It is a typical flow figure of the limestone reserve supply equipment of one example of the present invention.

  Hereinafter, a specific example of the limestone preliminary supply facility of the present invention will be described with reference to the case where the existing CFB boiler provided with the limestone supply facility and the fluid material supply facility is provided as an example. In the CFB boiler in which the limestone preliminary supply facility according to one embodiment of the present invention is installed, an air distribution plate is generally provided at a lower portion in the boiler body, and cut out from the fuel bunker on the air distribution plate Limestone as fuel is continuously supplied along with limestone as a desulfurizing agent cut out from the desulfurizing agent silo. A fluid material (sand) such as borax cut out from the fluid material silo is periodically supplied on the air dispersion plate. The fluid material plays a role of forming a fluid bed in the furnace, and preferably swirls and flows in the main combustion chamber to enable efficient combustion of fuel.

  As shown in FIG. 1, the supply of limestone and fluid material as the above desulfurization agent to the furnace of the CFB boiler 1 is respectively performed by the desulfurization agent supply facility and the fluid material supply facility. Specifically, the desulfurizing agent supply facility includes a desulfurizing agent silo 3 for storing powdered limestone, and a desulfurizing agent quantitative extraction device 3a such as a rotary valve and a table feeder provided at the bottom of the desulfurizing agent silo 3. The desulfurizing agent pneumatic transportation piping system 4 mainly transports powdered limestone cut out from the desulfurizing agent quantitative extracting device 3a using compressed air as a medium. In the desulfurizing agent quantitative extraction device 3a, for example, control of the extraction amount is performed by rotation speed control by an inverter motor. In the desulfurization agent pneumatic transportation piping system 4, before and after the portion to which the desulfurization agent quantitative extraction device 3a is connected, the desulfurization agent supply piping system 4 is desulfurizing agent pneumatic transportation piping system 4 when the desulfurization agent supply equipment is stopped due to a trouble or the like. ON / OFF valves 5a and 5b are provided to shut off the valve.

  On the other hand, similar to the above desulfurization agent supply facility, the fluid material supply facility is a fluid material silo 6 storing fluid material, and a flow material quantitative quantity such as a rotary valve and a table feeder provided at the bottom of the fluid material silo 6 It mainly comprises a cutting device 6a and a fluid material pneumatic transport piping system 7 for transporting the fluid material cut out from the fluid material quantitative cutting device 6a using compressed air as a medium. In the fluid material quantitative extraction device 6a, control of the extraction amount is performed, for example, by rotation speed control by an inverter motor. In the fluid material pneumatic transport piping system 7, ON / OFF valves 8a and 8b for blocking the fluid material supply facility from the fluid material pneumatic transport piping system 7 before and after the portion connected by the fluid material quantitative extraction device 6a. Are provided respectively.

  The limestone pre-supplying system of one embodiment of the present invention may be provided in any one of the above-described existing desulfurizing agent supply facilities and fluid material supply facilities described above, but is provided in both cases so as to flexibly cope with various situations Is preferred. That is, as shown in FIG. 1, the first limestone preliminary supply facility 10 includes a first limestone hopper 11 storing powdery limestone, and a first flow rate limiting unit 11a such as a slide damper provided at the bottom thereof. A first ejector 12 provided under the first flow rate limiting means 11a for sucking and transporting powder using compressed air, introducing the compressed air into the first ejector 12 and using the compressed air as a medium The first bypass piping system 13 is mainly composed of the first bypass piping system 13 where the limestone is transported by air, and the first bypass piping system 13 is a connecting portion of the desulfurization agent quantitative extraction device 3a in the desulfurization agent air transportation piping system 4 and its It is provided to bypass the front and rear inlet side and outlet side ON / OFF valves 5a and 5b.

  Further, in the first bypass piping system 13, inlet side and outlet side ON / OFF valves 14 a and 14 b that are preferably automatically opened and closed are provided before and after the first ejector 12. These ON / OFF valves 14a and 14b are normally in a closed state, and when the desulfurizing agent supply facility is stopped due to a trouble or the like, the on / off valves 14a and 14b are opened automatically or by the operation of the operator. Further, in the first bypass piping system 13, the first regulator 15 is provided on the primary side of the inlet side ON / OFF valve 14a, and the pneumatic pressure of the compressed air supplied to the first ejector 12 is 0. 0 by gauge pressure. It can be adjusted to an appropriate value of about 06 to 0.10 MPa. Furthermore, a first manual valve 16 is provided between the first ejector 12 and the inlet side ON / OFF valve 14a, and this first manual valve 16 regulates the flow rate of compressed air supplied to the first ejector 12 can do.

  The first ejector 12 described above comprises a nozzle for releasing high pressure gas such as compressed air as a driving fluid, a suction chamber in which powder limestone is sucked by the action of the gas released from the nozzle, and the suction chamber It consists mainly of a thick limestone and a diffuser that discharges while mixing the gas released from the nozzle, and there is no moving part, so there is no need for power supply work or supply of lubricating oil at the time of installation. Because it is basically unnecessary, it is excellent as a backup device.

  A commercially available general ejector can be used for the first ejector 12 having such a function. The ejector is an application of Bernoulli's theorem that the static pressure in the pipe is converted to kinetic energy when the velocity of the fluid (air) flowing in the pipe is increased, so that the fluid becomes negative pressure in the pipe. Powder can be sucked from the outside by increasing the speed of. In the diffuser through which the fluid after suction flows, the diameter of the fluid is reduced by expanding the diameter, and the kinetic energy is lowered. As a result, the static pressure in the pipe is recovered to the positive pressure side, and the sucked powder can be pumped.

  Since the second limestone reserve supply facility 20 provided in the fluid material supply facility also basically has the same configuration as the first limestone reserve supply facility 10 described above as shown in FIG. I omit it. The components of the second limestone reserve supply facility 20 and the components of the first limestone reserve supply facility 10 described above correspond to one another in the same order of magnitude.

  Next, a limestone prefeeding method using the first and second limestone prefeeding facilities 10 and 20 described above will be described. When the desulfurizing agent quantitative extraction device 3a of the desulfurizing agent silo 3 is stopped due to a trouble or the like, the ON / OFF valves 5a and 5b of the desulfurizing agent air transport piping system 4 are closed automatically or by the operator's operation in the desulfurizing agent supply facility. Instead, the ON / OFF valves 14a and 14b of the first bypass piping system 13 of the first limestone spare supply facility 10 are opened automatically or by the operation of the operator, and the first ejector 12 is connected to the first bypass piping system 13. Compressed air is introduced via the primary side. As a result, the powdered limestone that flows out quantitatively from the first limestone hopper 11 via the first flow rate limiting means 11a is a part of the secondary side of the first bypass piping system 13 and a part of the existing desulfurization agent air transportation piping system 4 Through to the CFB boiler 1. This allows air transport of the desulfurizing agent to the CFB boiler 1 to be continued with little interruption.

  On the other hand, since the injection of the fluidizing material is carried out only about 10 minutes once a day, normally, the inlet and outlet side ON / OFF valves 8a and 8b of the air conveying piping system 7 for fluidizing material are closed. Therefore, with the stop due to the trouble of the quantitative extraction device 3a of the desulfurizing agent silo 3 described above, the ON / OFF valve 24a, 24b of the second bypass piping system 23 opens automatically or by the operation of the operator. Similar to the limestone preliminary supply facility 10, compressed air is introduced to the second ejector 22, and limestone flowing out of the second limestone hopper 21 is supplied to the CFB boiler 1. In the case where the fluid material is accidentally introduced when the desulfurizing agent supply facility is stopped, it is preferable to open the ON / OFF valves 24a and 24b after the fluid material is completely introduced.

As described above, the supply amount of limestone preliminarily supplied from the first and second limestone preliminary supply facilities 10, 20 depends on the opening degree of the first and second flow rate limiting means 11a, 21a, or the first and second It can be adjusted by the second manual valve 16, 26. At that time, for example, preferably adjusted to an appropriate opening based on SO _X concentration meter 2 values provided in the piping which the exhaust gas flows. The supply of limestone to the first and second hoppers 11 and 21 can be performed, for example, by lifting the limestone filled in the flexible container bag with a forklift or a crane.

  In the structure shown in Fig. 1, when the limestone falling from the limestone hopper by suction is sucked into the ejector and transported by air, although the amount depends on the distance, piping diameter, bend diameter, etc. 200 to 500 kg / hr. When the supply amount is smaller than that of the existing limestone supply facility, it is preferable to install the limestone preliminary supply facility in both the limestone charging facility and the fluid material charging facility as described above. As shown in FIG. 1, limestone is sucked from the limestone hopper provided below the ejector to be pneumatically transported instead of a system in which the limestone falling by its own weight from the limestone hopper provided above is sucked into the ejector for air transportation. It may be a method. Next, although the Example of the limestone preparatory supply installation of this invention is described, this invention is not limited to a following example.

  As shown in Figure 1, the pneumatic transportation piping of limestone supply equipment and fluid material supply equipment provided in the CFB boiler (model number: THP-1, capacity: 300T / H x 48MW) made by existing Formosa Heavy Industry Cooperation The first and second bypass piping systems 13 and 23 are provided, respectively, and the ejectors made by Fluid Industrial Co., Ltd. as the first and second ejectors 12 and 22 (the model number: PEJAP-100. -Z type was installed respectively. At the top of these ejectors, slide dampers are installed as first and second flow rate limiting means 11a and 21a, respectively, and first and second limestone hoppers 11 and 21 with a capacity of 200 L are respectively installed thereon. In this way, the first and second limestone reserve supply facilities 10, 20 were installed in the CFB boiler.

  When repairing and checking the above-mentioned fixed quantity cutting device of the existing limestone supply facility, the inlet side and the outlet side ON / OFF valves 5a, 5b are closed and the inlet side provided in the first bypass piping system 13 described above And the outlet side ON / OFF valves 14a and 14b, and the inlet and outlet side ON / OFF valves 24a and 24b provided in the second bypass piping system 23 described above, and the first and second ejectors 12 and 22 described above Was introduced compressed air with a gauge pressure of 0.06 MPa. As a result, the limestone was supplied continuously for 8 hours by operating the first and second limestone reserve supply facilities 10 and 20 together. In addition, at the time of the stop of the above-mentioned limestone supply facility, the existing fluid material supply facility was in a stop state.

The amount of limestone supplied from the first and second limestone preliminary supply facilities 10 and 20 was 200 kg / hr, respectively, as converted from the loss of limestone in the first and second limestone hoppers 11 and 21. Then, the SO _X concentration in these exhaust gases during operation of limestone preliminary supply equipment, and analyzed in compliance with sulfur oxides analytical method in an exhaust gas according to Japanese Industrial Standard K0103.

For comparison, in each of the existing limestone supply facility and fluid material supply facility, a pressure vessel was installed via a slide damper on the branch pipe of the air transport piping. Then, in each pressure device, after supplying limestone from the manhole and closing the manhole to make a closed state, pressurize the inside of the pressure vessel with compressed air and then open the slide damper to make limestone in 1 batch 50 kg 1 Pumped to a 4-batch CFB boiler on time. The SO _X concentration of the exhaust gas was analyzed in the same manner as in the case of using the ejector except for the above. Table 1 below shows the maximum SO _X concentration in the exhaust gas and the average SO _X concentration in the case of using the above ejector and using the pressure vessel for 8 hours of operation.

As can be seen from the results in Table 1 above, by providing a limestone preliminary supply facility consisting of a limestone hopper and an ejector, even if the existing limestone supply facility is shut down, the SO _X concentration in the exhaust gas is regulated voluntarily (160 ± 30 ppm) It was possible to control within the range of In contrast, in the case of limestone preliminary supply equipment for pumping a pressure vessel without using ejector, is SO _X concentration in the exhaust gas varies to become a batch operation rather than continuous operation, the above-mentioned self-regulation of the SO _X concentration Could not control within the value.

Reference Signs List 1 circulating fluidized bed boiler 2 SO _X concentration meter 3 desulfurizing agent silo 3a desulfurizing agent quantitative extraction device 4 desulfurizing agent pneumatic transportation piping system 5a inlet side ON / OFF valve 5b outlet side ON / OFF valve 6 fluid material silo 6a fluid material determination Cutting device 7 Fluid material pneumatic transportation piping system 8a Inlet side ON / OFF valve 8b Outlet side ON / OFF valve 10 1st limestone spare supply facility 11 1st limestone hopper 11a 1st flow restriction means 12 1st ejector 13 1st bypass Piping system 14a 1st bypass inlet side ON / OFF valve 14b 1st bypass outlet side ON / OFF valve 15 1st regulator 16 1st manual valve 20 2nd limestone reserve supply facility 21 2nd limestone hopper 21a 2nd flow restriction means 22 Second ejector 23 Second bypass piping system 24a Second bypass inlet side ON / OFF valve 24b Second bypass Mouth-side ON / OFF valve 25 second regulator 26 second manual valve

Claims (3)

  A limestone reserve supply facility for a CFB boiler, comprising: an ejector provided in an air transport system communicating with a furnace of a CFB boiler; and a hopper for storing limestone communicated with the ejector via a flow rate limiting means.   The first bypass piping system which bypasses the connection part of the limestone quantitative extraction device in the limestone pneumatic transportation piping system where the limestone supply is continuously performed, and the air of the fluid material where the supply of the fluid material is performed periodically. The limestone reserve supply facility according to claim 1, wherein the ejector is provided in each of the transport piping system and the second bypass piping system which bypasses the connection part of the fluid material quantitative extraction device. . A method of preliminarily supplying limestone to a CFB boiler by introducing compressed air into an ejector provided via a flow rate limiting means below a hopper for storing limestone, comprising SO in exhaust gas from the CFB boiler _The limestone pre-supplying method characterized by adjusting the opening degree of the said flow restriction means based on _X density _| concentration.

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