JP2009063288A - Dust removing method for pressurized fluidized bed boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust removing method for a pressurized fluidized bed boiler achieving an appropriate fly ash composition in high-temperature exhaust gas in accordance with a difference of types of burned coal, change in the combustion state and change in particle size distribution of ash dust etc. and preventing wear of piping and a cyclone due to ash dust. <P>SOLUTION: In the dust removing method for the pressurized fluidized bed boiler to supply high-temperature exhaust gas discharged from the pressurized fluidized bed boiler to the cyclone to remove ash dust in the exhaust gas, the fly ash composition in the exhaust gas entering to the cyclone is measured, and the supply amount of coal as fuel to be supplied to the pressurized fluidized bed boiler or the addition amount of coal particles as a desulfurizing agent is adjusted so that based on the measurement value, the fly ash composition in the exhaust gas satisfies the following formulas: (1) SiO<SB>2</SB>(chemical analysis value)≤40 wt.%; (2) SiO<SB>2</SB>-1.3 Al<SB>2</SB>O<SB>3</SB>(chemical analysis value)≤15 wt.%; and (3) (SiO<SB>2</SB>-1.3 Al<SB>2</SB>O<SB>3</SB>)-CaO-CaCO<SB>3</SB>-CaSO<SB>4</SB>-Fe<SB>2</SB>O<SB>3</SB>(chemical analysis value)≤-20 wt.%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a dust removal method for a pressurized fluidized bed boiler, and more particularly, a dust removal method for a pressurized fluidized bed boiler suitable for effectively reducing the dust concentration in high-temperature exhaust gas discharged from the pressurized fluidized bed boiler. Regarding the method.

  In a pressurized fluidized bed boiler combined power plant, instead of a pulverized coal combustion boiler, finely crushed coal is fluidized and burned in a pressurized boiler, and a steam turbine is driven by steam generated from a water pipe laid in the fluidized bed. At the same time, the gas turbine is driven by the high-pressure combustion exhaust gas discharged from the boiler, and power is generated by both the steam turbine and the gas turbine. FIG. 11 is a system diagram of a pressurized fluidized bed boiler combined power plant according to the prior art.

  This combined power plant is discharged from a pressurized fluidized bed boiler 1 that supplies coal to a fluidized bed for combustion, a steam turbine 2 that generates power using steam generated by the combustion, and the pressurized fluidized bed boiler 1. Cyclones 7 and 8 for removing dust from the hot exhaust gas, and a gas turbine 10 for generating electric power from the removed hot exhaust gas. In such a configuration, steam generated by the combustion of coal in the pressurized fluidized bed boiler 1 is supplied to the steam turbine 2, and power is generated by the steam turbine generator 3. The steam that has driven the steam turbine 2 is cooled by the condenser 4 to become boiler feed water, and is re-supplied from the feed water pump 5 to the pressurized fluidized bed boiler 1 as boiler feed water. Further, the high-temperature and high-pressure dust-containing exhaust gas generated in the pressurized fluidized bed boiler 1 is roughly dedusted by the primary cyclone 7 from the high-temperature gas pipe 6 and then precisely dedusted by the secondary cyclone 8. The gas discharged from the secondary cyclone 8 is supplied to the gas turbine 10 from the high temperature gas pipe 9 to drive it, and the generator 11 for gas turbine generates power. The exhaust gas exiting the gas turbine 10 is cooled by the exhaust gas cooler 12, fine dust is removed by the low-temperature dust collector 13, and discharged from the chimney 14 to the atmosphere. In addition, 15 and 16 in FIG. 11 show the storage container which accommodates the primary cyclone 7 and the secondary cyclone 8, respectively, 17 shows an air compressor, 18 shows an ash processing apparatus.

  When the plant is operated, wear of the blades of the gas turbine 10 due to soot generated by combustion of coal becomes a problem. Therefore, dedusting is performed to a sufficiently low dust concentration so that wear of the blades of the gas turbine 10 does not become a problem. A cyclone type dust collector, which is a centrifugal dust collection method that can be used under high temperature and pressure, is used. However, by using such a cyclone type dust collector, when burning using homogeneous coal, the dust concentration can be lowered to such an extent that wear of the blades of the gas turbine 10 does not become a problem. When the type of charcoal to be used is different, or when the particle size of the soot is reduced due to changes in the combustion state, etc., the dust collection performance is deteriorated, so that soot flows into the gas turbine 10 and the blades of the gas turbine 10 are increased. There was a problem of giving wear.

FIG. 12 is an explanatory diagram of a cyclone container storing a plurality of cyclones used as a cyclone type dust collector. In FIG. 12, a high-temperature dust-containing gas 39 at 800 to 900 ° C. containing combustion ash, limestone or the like having an average particle diameter of several tens of μm and having an ash concentration of several 10 g / Nm ³ The cyclone element 32 is supplied to the cyclone element 32 at a flow rate of several tens of m / s, and is dedusted by swirling the airflow inside the cyclone element 32. To be discharged. The collected ash 35 is discharged from the lower hopper of the container by gravity sedimentation. However, in such a cyclone type dust collector, if the particle size or dust concentration of the furnace scattered dust fluctuates during plant operation, the cyclone itself is not provided with a function for adjusting the dust removal performance. There was a problem that the dust concentration in the exhaust gas from the cyclone outlet fluctuated. For this reason, conventionally, when the inlet dust concentration fluctuates in the direction of increasing, in order to protect the gas turbine, the output of the plant is once lowered to reduce the dust load, or the plant is stopped to increase the cyclone. It was necessary to take measures such as replacing it with an efficient one.

  In the high-temperature and high-pressure exhaust gas (temperature of about 850 ° C., pressure of 8 to 10 atm) led from the pressurized fluidized bed boiler to the gas turbine in the gas turbine power generation system, coal ash and limestone as a desulfurization agent (some lime is also part). Included), and gypsum produced by the desulfurization reaction was included, which had the problem of causing wear damage to the equipment of the exhaust gas line (hereinafter, coal ash, limestone, gypsum, etc. scattered from the above boilers are called fly ash) ). The parts that are subject to wear include high-temperature gas pipes, cyclones, gas turbine blades, and the like, all of which are devices that require important functions. Conventionally, as a countermeasure for wear of these devices, a high-grade material with excellent wear resistance is selected, a design that takes into account the surplus material for wear, and a structure that is easy to replace on the premise of replacing if wear occurs. In addition, a method such as slowing the gas flow rate has been adopted so that wear does not easily occur. However, with the countermeasures as described above, (1) high-temperature gas pipes are 200 to 300 m long in commercial plants (250 to 350 MW), so adopting a method that uses high-grade materials and increases the surplus (2) Lowering the flow rate of high-temperature gas piping increases the diameter of the piping, increases the external surface area, increases heat loss, lowers the gas turbine inlet temperature, and lowers gas turbine efficiency. There was a problem.

  The object of the present invention is to solve the above-mentioned problems of the prior art and to optimize the fly ash composition in the high-temperature exhaust gas due to differences in the types of coal to be burned, changes in the combustion state, changes in the particle size distribution of soot, etc. To provide a dust removal method for a pressurized fluidized bed boiler capable of effectively reducing the dust concentration in the high-temperature exhaust gas supplied to the gas turbine by preventing wear of piping and cyclones due to dust inside is there.

The invention claimed in the present application is as follows.
(1) Measuring the fly ash component in the exhaust gas entering the cyclone in the method of supplying high temperature exhaust gas discharged from the pressurized fluidized bed boiler to the cyclone, removing the dust in the exhaust gas, and then discharging it outside the system The amount of coal supplied as fuel to be supplied to the pressurized fluidized bed boiler so that the fly ash component in the exhaust gas satisfies any of the following formulas (1) to (3) based on the measured value: A method for dedusting a pressurized fluidized bed boiler, characterized in that the amount of lime fine particles added as a desulfurizing agent is adjusted.
(1) SiO ₂ (chemical analysis value) ≦ 40% by weight
(2) SiO ₂ -1.3Al ₂ O ₃ (chemical analysis value) ≤ 15 wt%
(3) (SiO ₂ -1.3Al ₂ O ₃ ) -CaO-CaCo ₃ -CaSO ₄ -Fe ₂ O ₃ (chemical analysis value) ≤ -20 wt%
(2) The removal of the pressurized fluidized bed boiler according to (1), wherein the fine coal particles are at least one of fine limestone, fine quicklime, and fine slaked lime and have a particle size of 200 μm or less. Dust method.

  According to the dedusting method for a pressurized fluidized bed boiler of the present invention, by optimizing the fly ash composition of the exhaust gas discharged from the pressurized fluidized bed boiler, the hot gas piping, cyclone and gas turbine blade of the PFBC plant are optimized. Wear can be prevented and stable operation is possible. Moreover, since the flow velocity can be increased, the heat loss of the high-temperature gas piping is reduced and the gas turbine efficiency can be increased. Moreover, in a cyclone, since the flow velocity can be increased, highly efficient dedusting can be performed.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view of a dedusting device for a pressurized fluidized bed boiler showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the cyclone of FIG. 1, and FIG. It is sectional drawing. In FIG. 1 to FIG. 3, the difference from FIG. 11 of the prior art is that a measuring device 24 for measuring the dust particle size distribution in the high-temperature exhaust gas is provided in parallel with the storage containers 15 and 16 containing the cyclones 7 and 8, respectively. A cascade impactor 23 is provided, and a damper 29 is provided as a gas flow rate regulator at the cyclone inlet, and the damper 29 is opened and closed based on the dust particle size distribution in the high-temperature exhaust gas measured by the measuring instrument 24. is there. The combustion exhaust gas discharged from the pressurized fluidized bed boiler 1 contains about 32 g of soot per 1 m ³ N, and the particle size of soot is distributed in the range of about 0.1 to 100 μm. The gas temperature is 850 to 900 ° C.

  In FIG. 1, the exhaust gas from the pressurized fluidized bed boiler 1 is firstly roughly dedusted by the primary cyclone 7 and precisely dedusted by the secondary cyclone 8, so that there is no problem with the abrasion of the blades of the gas turbine 10. Supplied as Since there is a pressure loss of exhaust gas due to the primary cyclone 7 and the secondary cyclone 8 between the hot gas pipe 6 on the inlet side of the primary cyclone 7 and the hot gas pipe 9 on the outlet side of the secondary cyclone 8, the differential pressure of the exhaust gas Has occurred. Therefore, the exhaust gas flows through the cascade impactor 23 provided in parallel with the primary cyclone 7 and the secondary cyclone 8 due to the differential pressure of the exhaust gas, and soot can be collected for each particle size of the soot. The dust collected by the cascade impactor 23 for each particle size can be measured for its weight by the measuring device 24 and the particle size distribution can be measured.

  2 and 3, the gas flowing in from the cyclone inlet pipe 25 descends while turning in the cyclone main body 26 like a gas flow 28, reverses and rises in the vicinity of the dust hopper 27, and is discharged from the cyclone outlet pipe 21. Is done. On the other hand, the dust falls along the inner wall of the dust hopper 27 by centrifugal force and is discharged as the collected ash 22. Reference numeral 21 denotes a cyclone outlet pipe, and 28 denotes a gas flow. The dust collection efficiency differs depending on the centrifugal force of the gas flow 28 generated in the cyclone main body 26. The finer the particle size of the dust, the faster the gas flow rate necessary for collecting the dust. Therefore, when the particle size of the dust becomes fine, the dust collection efficiency can be increased by closing the damper 29 at the inlet of the cyclone body 26 and increasing the gas flow rate. The damper 29 is opened and closed based on the particle size distribution of the dust in the exhaust gas measured by the cascade impactor 23 so as to be within a predetermined particle size distribution range. In addition, the opening and closing of the damper 29 can be adjusted.

  For example, when the particle size of the dust becomes large, the damper 29 is opened to reduce the gas flow rate of the exhaust gas, thereby preventing wear of the castable inside the cyclone. When the particle size of the dust becomes fine, the damper 29 is closed. By increasing the gas flow rate in the direction, it is possible to prevent the dust collection efficiency from being lowered and to prevent the blades of the gas turbine 10 from being worn. In this way, a damper for adjusting the gas flow rate is provided at the inlet of the cyclone, and the gas flow rate at the cyclone inlet is adjusted by adjusting the opening and closing of the cyclone inlet adjustment damper based on the particle size distribution of the dust measured by the cascade impactor. By making the gas flow rate suitable for the particle size distribution of the soot, it is possible to prevent a decrease in the dust collection efficiency caused by the change in the particle size distribution of the soot dust due to the change of the type of coal to be burned and the change of the combustion state. It is possible to effectively prevent the wear of the blade.

  FIG. 4 is an explanatory view of a cyclone container used in a dust removing apparatus according to another embodiment of the present invention. In FIG. 4, a cyclone inner cylinder 37 of a cyclone element 32 stored in a cyclone container 33 is provided with an inner cylinder slide mechanism 34 that slides the inner cylinder 37 in the vertical direction, and is supplied to the cyclone element 32. The insertion depth of the cyclone inner cylinder 37 from the inlet duct floor surface can be adjusted according to the dust properties in the exhaust gas. Dust-containing exhaust gas flows from the container account 30. The inflowing gas is distributed and flows into the individual cyclone elements 32, descends while rotating in the cyclone, reverses and rises in the vicinity of the leg 36, passes through the cyclone inner cylinder 37, and is mixed with gas from other elements in the outlet plenum 37. And discharged from the container withdrawal account 31. The dust in the exhaust gas moves to the wall side by the swirling of the air current in the cyclone, reaches the wall surface, the collected dust descends along the wall surface, gathers in the container hopper from the leg 36, and goes outside from the ash discharge seat 35 Discharged. When properties such as the particle size or dust concentration of the furnace scattered dust fluctuate during operation of the plant, the inlet dust conditions can be adjusted without stopping the plant by adjusting the insertion depth of the inner cylinder 37 by the inner cylinder slide mechanism 34. Can be adjusted to obtain optimum dust removal efficiency.

  That is, the dust-containing exhaust gas is introduced below the duct floor provided at the inlet of the cyclone element 32. However, if the insertion depth of the inner cylinder is insufficient, a part of the dust that has flowed in immediately enters the interior. A short pass to the cylinder side is caused and the dust is not collected, so that a phenomenon in which the entire dust removal efficiency is lowered may occur. In addition, when the inner cylinder is inserted too deeply, only the pressure loss of the cyclone increases, but the dust removal efficiency reaches a peak, and the power generation efficiency of the entire plant decreases. The influence of the insertion depth of the cyclone inner cylinder on the dust removal efficiency was examined using the cyclone shown in FIG. 5, and the result is shown in FIG. The experiment was conducted by changing the ratio of the inner cylinder insertion depth h to the height B of the inlet duct (inner cylinder length ratio) in the range of 0.04 to 0.22. Regarding the adjustment of the cyclone dust removal efficiency, It was found effective to change the insertion depth of the cyclone inner cylinder, and it was found that the highest dust removal efficiency was obtained particularly when h / B = 0.12. Although the cyclone container in which the inner cylinder slide mechanism 34 is provided in the cyclone container hopper so that the insertion depth of the inner cylinder 37 can be adjusted is shown in FIG. 7, the same effect as described above can be obtained even in this case. It is done.

  FIG. 8 is an explanatory view of a dedusting device for a pressurized fluidized bed boiler showing still another embodiment of the present invention. As a fuel for pressurized fluidized bed boiler (PFBC), there are known a method of supplying coal in a dry state and a method of supplying it as CWP (Coal Water Paste). Here, the case of using the CWP method is used. explain. In FIG. 8, raw coal as a PFBC fuel is sent from a raw coal bunker 61 to a coarse pulverizer 62 and coarsely pulverized to a particle size of about 2 to 3 mm. The reason why this 2 to 3 mm coarsely pulverized charcoal is used as fuel is that it is necessary to stay in the bed for a sufficient time in order for combustion to be performed sufficiently. However, if the CWP is composed of only coarse pulverized coal, troubles such as blockage in piping are likely to be induced. Therefore, the pulverized coal finely pulverized by the fine pulverizer 63 and the coarse pulverized coal are kneaded by the kneader 64. At this time, limestone as a desulfurizing agent is simultaneously supplied from the coarse limestone tank 65 and kneaded. Limestone is supplied in coarse grains (usually 1 to 3 mm) because sufficient residence time is required to cause the desulfurization reaction in the bed. The fuel kneaded in this manner is temporarily stored in the CWP tank 66 and sent into the fluidized bed by the CWP pump 67.

The fuel is burned in the fluidized bed, and the coal ash and the desulfurization agent CaCO ₃ (including CaO generated in part of the decarboxylation reaction) and the desulfurization reaction product CaSO ₄ are fly ash. Then, it is carried together with the exhaust gas through the high-temperature gas pipe 68 to the cyclone 69 and the high-precision dust removing device 70 (ceramics filter or high-precision cyclone), and further guided to the gas turbine. At this time, wear of the high-temperature gas piping, cyclone and gas turbine becomes a problem. However, since the amount of wear increases with time, the fly ash composition is periodically sampled by the fly ash sampling device 72, and the analysis device 73. It is possible to deal with the wear phenomenon by investigating with. Hereinafter, the relationship between the fly ash composition and the wear phenomenon will be described in detail.

  Table 1 shows the chemical composition of the fly ash and the results of the wear test, and results of conducting fly ash impact wear experiments at high temperatures by burning various coals in a small pilot plant and collecting fly ash. It is. In Table 1, fly ash G, H, and I are obtained by adding fine quartz (average particle size of about 40 microns) to fly ash collected from a small pilot plant, and fly ash J is pure fine quartz. From Table 1, it can be confirmed that depending on the type of lyash, there are two forms in which the wear phenomenon occurs or the fly ash adheres without wear.

This phenomenon is considered to be related to the composition of fly ash. (1) The distinction between fly ash composition and wear and adhesion, (2) The relationship between fly ash composition and wear rate is organized and shown in FIG. Shown in b) and (c). That is, (a) in FIG. 9 is simply the relationship between SiO ₂ obtained by chemical analysis and the wear rate, and (b) is SiO ₂ -1.3Al as the chemical analysis value of quartz, which is the main mineral that causes wear. Considering that it can be approximated by ₂ O ₃ (Reference: EPRICS-5071 Report 2711-1 Final Report Feb. 1987 “Fire Side Corrosion and Fly Ash Erosion in Boiler”), the value of SiO ₂ -1.3Al ₂ O ₃ And (c) shows that the wear resistance of the quartz, whereas CaO, CaCO ₃ , CaSO ₄ and Fe ₂ O ₃ as the Ca component are softer than the metal at that temperature, so that the wear is suppressed. Subtracting this component from a considerable amount (SiO ₂ -1.3Al ₂ O ₃ ), specifically (SiO ₂ -1.3Al ₂ O ₃ ) -CaO, CaCO ₃ , CaSO ₄ —Fe ₂ O ₃

From FIG. 9, there is a limit parameter value that governs the wear and adhesion phenomenon regardless of which method is used, and by using that parameter value, the wear and adhesion phenomenon can be clearly determined, and it corresponds to the wear rate to some extent. It became clear that. This means that the wear of the PFBC exhaust gas system equipment can be prevented by appropriately controlling the fly ash composition. The composition of this fly ash is derived from the ash component in coal and the Ca component added as a desulfurizing agent, and the controllable desulfurizing agent component (Ca component) is also included as a factor as shown in FIG. 9 (c). Focused on that. FIGS. 9 (a) and 9 (b) are simply arranged with SiO ₂ and SiO ₂ -1.3Al ₂ O ₃ , but if the desulfurizing agent component is increased, both values will be reduced, so that wear is reduced. It is possible to make the component range not.

Next, means for adding a Ca component in order to control the composition in the fly ash within a range where it will not be worn will be described below. First, regarding what kind of chemical composition is appropriate as the Ca component, it is appropriate to add CaCO ₃ , CaO, and Ca (OH) ₂ in terms of having a desulfurization action. Next, there are two ways to add the Ca component to the hot gas piping inlet (furnace outlet) and the furnace, but it is more effective to contribute to the desulfurization reaction, so it is better to put it in the furnace. It is. In addition, when adding to the furnace, it is appropriate to make the particle size smaller than the fly ash, but in the case of CaCO ₃ , the superficial velocity is 1.0 m / s, the pressure is 8.5 atg, and the temperature is 850 ° C. The particle size to be scattered is about 0.2 mm. Such maximum particle size can generally be determined from the flow velocity (end velocity) in which the gravity acting on the particles and the buoyancy received from the fluid are balanced.

The abrasion phenomenon is a phenomenon in which quartz, which is harder than metal and has a square shape, collides with the metal and causes tears, which accumulate and decrease in thickness. On the other hand, CaO, CaCO ₃ , CaSO ₄ Since Ca components such as are softer than metal, they do not have an effect of wear, but rather deposit thinly on the surface. FIG. 10 shows as a model diagram the mechanism of the phenomenon in which wear or adhesion occurs depending on the amount of SiO ₂ . FIG. 10A is a model diagram when the amount of SiO ₂ is small with respect to the Ca compound, but since the ratio of the Ca compound 77 is large, the Ca compound 77 adheres to the metal 75 to form a thin film 76. Since the temperature is as high as 850 ° C., slight sintering occurs and the film thickness δ increases. Accordingly, quartz (SiO ₂ ) 78 collides from above the generated film, but collision damage does not reach the base metal 75. On the other hand, as shown in (b), when the proportion of the Ca compound is reduced, the film thickness δ is reduced, the collision damage of the quartz 78 reaches the metal 75, and wear is considered to progress. Thus, it is considered that there is a limit value that shifts from wear to adhesion.

Next, how much CaCO ₃ is actually supplied will be described. The most wearable fly ash sampled at the PFBC small pilot plant has 44% SiO _2, but in order to obtain a fly ash having no wear, 40% SiO ₂ content is required as described above. Must be: For this purpose, the amount of fine CaCO ₃ supplied is 2.3% of the supplied coal amount, based on the following assumptions.
(1) In order to reduce SiO ₂ from 44% to 40%, fine CaCO ₃ may be added to SiO ₂ 44 at a ratio of 10, that is, 23% of SiO ₂ .
(2) SiO ₂ is all derived from coal ash, but in the case of B coal, 15% of ash is present in the coal.
(3) 65% SiO ₂ is present in the ash.

The amount of CaCO ₃ supplied as a desulfurizing agent is about 10% with respect to coal. (Assuming that the amount of S is 0.6 to 1% and Ca / S = 3 to 4 is supplied) No analysis of the composition after mixing with the fine limestone tank over time and no wear It is possible to control the composition to the limit. The timing of fly ash analysis is as follows: (a) when the coal used is changed (as ash and SiO ₂ content changes), (b) when the used desulfurizer is changed (the weathering rate of the desulfurizer is (C) When the load is changed (because the weathering rate of the desulfurizing agent changes because the bed height changes), etc. can be considered. Although the example which mixed fine limestone in CWP was described above, as fine limestone, it is also possible to supply in a furnace dry using a lock hopper. As the Ca component to be mixed, CaO or Ca (OH) ₂ can be used in addition to CaCO ₃ .

The sample analysis device 73 may be any device that can analyze Si, Ca, Al, Fe, CO ₃ roots, and SO ₄ roots, but can analyze Si, Ca, Al, and Fe in a relatively short time with high accuracy. For this, plasma emission analysis (ICP) is preferred. As a method for analyzing CO ₃ root and SO _4, a known titration method can be employed. If calculated from the analysis results (SiO ₂ -1.3Al ₂ O ₃₎ value of _{-CaO-CaCO 3 -CaSO 4 -Fe 2} O 3 is more than 20%, into a kneader 4 from fine limestone tank 71 Mix fine limestone to increase the Ca component in fly ash. As the composition control index, the value of SiO ₂ itself or the value of SiO ₂ -1.3Al ₂ O ₃ may be used as described above.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing of the dedusting apparatus for pressurized fluidized bed boilers which shows one Example of this invention. The longitudinal cross-sectional view of the cyclone of FIG. FIG. 3 is a cross-sectional view of the cyclone of FIG. Explanatory drawing of the dedusting apparatus for pressurized fluidized bed boilers which shows the other Example of this invention. The figure which shows the influence which it has on the insertion depth and dust removal efficiency of the cyclone inner cylinder of FIG. The figure which shows the influence which it has on the insertion depth and dust removal efficiency of the cyclone inner cylinder of FIG. Explanatory drawing of the dedusting apparatus for pressurized fluidized bed boilers which shows the other Example of this invention. Explanatory drawing of the dedusting apparatus for pressurized fluidized bed boilers which shows the other Example of this invention. The figure which shows the relationship between a fly ash composition and a wear rate. The figure which shows the progress of abrasion by a fly ash component. Explanatory drawing of the dedusting apparatus for pressurized fluidized bed boilers by a prior art. Explanatory drawing of the cyclone of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pressurized fluidized bed boiler, 2 ... Steam turbine, 6 ... High temperature gas piping, 7 ... Primary cyclone, 8 ... Secondary cyclone, 9 ... Koon gas piping, 10 ... Gas turn, 13 Low temperature dust collector, 23 ... Cascade impactor 24 ... Measuring instrument, 26 ... Cyclone body, 27 ... Dust hopper, 29 ... Damper, 32 ... Cyclone element, 33 ... Cyclone container, 34 ... Inner cylinder slide mechanism, 37 ... Cyclone inner cylinder, 41 ... Cyclone body, 43 ... Casing 44 ... Refractory material, 45 mesh metal anchor, 53 ... anchor claw, 54 ... wear resistant layer, 56 ... projection, 64 ... kneading machine, 71 ... fine limestone tank, 72 ... fly ash sampling device, 73 ... fly ash Analyzing device 74 ... control valve 122 ... emergency dust removing device 123 ... mist separator 126 ... dust removing Spray water head tank, 201 ... duct casing 202 ... spray pipe 205 ... shield plate, 210 ... bellows 215 ... slit, 218 ... oval hole,

Claims (2)

In a method of supplying high-temperature exhaust gas discharged from a pressurized fluidized bed boiler to a cyclone, removing dust in the exhaust gas, and then discharging out of the system, the fly ash component in the exhaust gas entering the cyclone is measured, As a desulfurizing agent or supply amount of coal as fuel to be supplied to the pressurized fluidized bed boiler so that the fly ash component in the exhaust gas satisfies any of the following formulas (1) to (3) based on the measured value A method for dedusting a pressurized fluidized bed boiler, characterized in that the amount of lime fine particles added is adjusted.
(1) SiO ₂ (chemical analysis value) ≦ 40% by weight
(2) SiO ₂ -1.3Al ₂ O ₃ (chemical analysis value) ≤ 15 wt%
(3) (SiO ₂ -1.3Al ₂ O ₃ ) -CaO-CaCO ₃ -CaSO ₄ -Fe ₂ O ₃ (chemical analysis value) ≤ -20 wt% 2. The method for dedusting a pressurized fluidized bed boiler according to claim 1, wherein the lime fine particles are at least one of fine limestone, fine quicklime and fine slaked lime, and have a particle size of 200 μm or less.