JP2011106701A - Bed material regeneration device for fluid bed and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bed material regeneration device for a fluid bed and a method therefor capable of efficiently separating a deposit from a bed material. <P>SOLUTION: The bed material regeneration device 3 for the fluid bed which regenerates the bed material Fa by separating the deposit from the bed material Fa extracted from the fluid bed F of a fluid bed-type combustion furnace 2 includes a cooling water tank 11 for separating the deposit from the bed material Fa by utilizing a difference of the shrinkage of the bed material Fa and the deposit by charging the bed material Fa extracted from the fluid bed F of the combustion furnace 2 into water and cooling it. According to the bed material regeneration device 3, the bed material Fa of a high temperature extracted from the fluid bed F of the combustion furnace 2 is charged into water and cooled so that the deposit is separated due to the difference of the shrinkage between the bed material Fa and the deposit, the deposit dissolves in the water, and thus the bed material Fa and the deposit can be efficiently separated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fluidized bed regenerating apparatus and method for regenerating a fluidized medium that forms a fluidized bed of a fluidized bed combustion furnace.

  In recent years, operation of a fluidized bed boiler using biomass fuel has been demanded. Among biomass fuels, low-grade biomass fuels such as fir shells and EFB (Empty Fruit Bunches) contain a large amount of alkali components, and these alkali components generate low melting point compounds. Such a low-melting-point compound may adhere to the fluidized medium and cause flow failure, so that the fluidized medium to which the compound adheres needs to be extracted from the fluidized bed. The fluid medium extracted from the fluidized bed is regenerated by separating it from the deposits, and can be returned to the fluidized bed again.

  Patent Document 1 describes a fluid medium sorting apparatus including a gas transport pipe and a gas transport device that perform gas transport by extracting a fluid medium such as sand from a fluidized bed of a fluidized bed combustion furnace. According to this fluid medium sorting device, it is said that the fluid medium can be separated from the deposits by colliding the fluid medium with the pipe wall surface or other fluid medium in the process of gas transport of the fluid medium. .

JP 2001-193912 A

  However, in the above-described fluid medium sorting apparatus, enormous energy is consumed to give the fluid medium sufficient momentum to be able to separate the deposits by collision during gas transport of the fluid medium such as sand, and the deposits There is a high possibility that these parts collide at an appropriate angle and are separated, and there is a problem that they are inefficient.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a fluidized-bed fluid medium regenerating apparatus and a method thereof that can efficiently separate deposits from the fluidized medium. .

  The present invention relates to a fluidized bed fluid medium regeneration device for regenerating a fluidized medium by separating deposits from the fluidized medium extracted from the fluidized bed of the fluidized bed combustion furnace, wherein the fluidized fluid is extracted from the fluidized bed of the combustion furnace. A cooling water tank is provided that separates the deposit from the fluidized medium by using a difference in shrinkage between the fluidized medium and the deposit by cooling the medium by putting it in water.

  According to the fluidized bed regenerating apparatus of the fluidized bed according to the present invention, the deposit caused by the difference in shrinkage between the fluidized medium and the deposit is obtained by cooling the fluidized medium extracted from the fluidized bed of the combustion furnace into water. Separation of the deposits and dissolution of the deposits in water can be achieved, thereby achieving separation of the fluid medium and deposits. In this way, by using the difference in shrinkage during cooling of the fluid medium and the deposit and the solubility of the deposit in water, the deposit can be removed from the fluid medium very efficiently compared to the conventional method using physical collision. Can be separated.

In the fluidized bed regenerating apparatus of the fluidized bed according to the present invention, it is preferable to further include an intermediate cooling means for cooling the fluidized medium to a predetermined appropriate temperature before being charged into the cooling water tank.
In this way, the temperature of the fluidized medium is cooled to a predetermined appropriate temperature by the intermediate cooling means and then introduced into the cooling water tank, so that it is possible to suppress water evaporation and a significant change in the water temperature due to the fluidized medium being introduced. become. As a result, it is possible to avoid a situation in which a large amount of water is stored or the water temperature is frequently adjusted to suppress changes in the water temperature, thereby reducing the size of the cooling water tank and lowering the operation cost. Can do. The predetermined appropriate temperature is a temperature at which the peeling of the deposit caused by the difference in shrinkage between the fluid medium and the deposit in water can be appropriately generated. The amount of water in the cooling water tank, the water temperature, and other fluid medium input It is determined appropriately according to the amount.

In the fluidized bed regenerating apparatus of the fluidized bed according to the present invention, it is preferable to further include a return means for collecting the fluidized medium from which the deposits have been separated and returning it to the fluidized bed.
As a result, the fluid medium extracted from the fluidized bed can be returned to the fluidized bed and automatically replenished, and the labor involved in supplementing the fluidized medium can be reduced.

  The present invention relates to a fluidized bed regeneration method for regenerating a fluidized medium by separating deposits from a fluidized medium extracted from a fluidized bed of a fluidized bed combustion furnace, wherein the fluid extracted from the fluidized bed of the combustion furnace By putting the medium into water and cooling it, the deposit is separated from the fluid medium using the difference in shrinkage between the fluid medium and the deposit.

  According to the fluidized bed regeneration method of the fluidized bed according to the present invention, the fluidized medium extracted from the fluidized bed of the combustion furnace is cooled by introducing it into water, thereby causing the deposits due to the shrinkage difference between the fluidized medium and the deposits. Separation of the deposits and dissolution of the deposits in water can be achieved, thereby achieving separation of the fluid medium and deposits. In this way, by using the difference in shrinkage during cooling of the fluid medium and the deposit and the solubility of the deposit in water, the deposit can be removed from the fluid medium very efficiently compared to the conventional method using physical collision. Can be separated.

  According to the present invention, deposits can be efficiently separated from a fluid medium.

It is sectional drawing which shows the combustion equipment provided with the fluidized-medium regeneration apparatus of the fluidized bed which concerns on 1st Embodiment. It is explanatory drawing which shows the formation mechanism of an agglomerate, (a) is a figure which shows a coating induction mechanism, (b) is a figure which shows a melting induction mechanism. It is a K2O-SiO2 phase diagram. It is sectional drawing which shows the combustion equipment provided with the fluidized-medium regeneration apparatus of the fluidized bed which concerns on 2nd Embodiment.

Hereinafter, a fluidized bed regenerating apparatus and method for fluidized bed according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[First Embodiment]

  As shown in FIG. 1, a fluid medium regenerator 3 according to a first embodiment is incorporated in a combustion facility 1 including a fluidized bed type combustion furnace 2, and sand extracted from a fluidized bed F of the combustion furnace 2. The fluid medium Fa is regenerated by separating the deposits from the fluid medium Fa.

  The combustion facility 1 includes a combustion furnace 2 that burns biomass fuel such as fir shells and EFB (Empty Fruit Bunches) and heats water in a sealed container to generate steam. The combustion furnace 2 is an external circulation type fluidized bed combustion furnace, and is a so-called CFB (Circulating Fluidized Bed) boiler. A fuel input port for supplying fuel is provided in an intermediate portion of the combustion furnace 2, and biomass fuel is input from this fuel input port.

  The combustion furnace 2 is supplied with a fluid medium Fa such as sand mainly composed of quartz particles, and air is supplied into the fluid medium Fa from the lower part so that the fluid medium Fa flows and the fluidized bed F flows. Is formed. The formation of the fluidized bed F promotes the combustion of biomass fuel. Combustion gas generated as a result of combustion rises in the combustion furnace 2 with a part of the fluid medium Fa.

  A gas outlet 2 a for discharging combustion gas is provided at the upper part of the combustion furnace 2. A cyclone separator 4 that functions as a solid-gas separator is connected to the gas outlet 2a. A combustion gas generated in the combustion furnace 2 is introduced into the cyclone separator 4 while accompanying solid particles. The cyclone separator 4 separates the collected solid particles and the combustion gas by a centrifugal separation action. The separated collected solid particles are returned to the combustion furnace 2 through the return line 5. On the other hand, the combustion gas from which the collected solid particles are removed is sent to the heat recovery device 6 through the discharge port 4a.

  The return line 5 consists of a pipe line connected to the lower part of the combustion furnace 2, and a loop seal 5a is provided in the middle thereof. The loop seal 5 a is a facility that prevents the combustion gas from flowing back into the combustion furnace 2. In the loop seal 5a, the fluid medium Fa sent from the cyclone separator 4 is accumulated, and the fluid medium Fa is introduced into the combustion furnace 2 from a return chute portion 5b serving as an outlet of the loop seal 5a.

  The heat recovery device 6 has a boiler tube that forms a flow path for combustion gas and flows water as a heat medium. The boiler tube is provided so as to cross the flow path of the combustion gas in the heat recovery device 6, and the heat of the combustion gas sent from the cyclone separator 4 is recovered by the water in the tube. In the boiler tube, high-temperature steam is generated by the recovered heat, and the generated steam is sent to the turbine for power generation through the boiler tube. The heat recovery device 6 sends the combustion gas after heat recovery to the bag filter 7 through the discharge port 6a.

  The bag filter 7 removes fine particles such as fly ash still accompanying the combustion gas. The combustion gas filtered by the bag filter 7 is sucked into the suction pump 8 and discharged from the chimney 9 to the outside.

  In the combustion furnace 2, in the process of burning biomass fuel, combustion ash and a part of the fuel generated by the combustion melt with the surrounding fluid medium Fa to form a lump. This lump is called agglomerate and accumulates at the bottom of the combustion furnace 2 and causes fluidity failure of the fluidized bed F. Therefore, it is necessary to periodically extract it together with the fluidized medium Fa. The fluid medium Fa extracted from the discharge port 2 b of the combustion furnace 2 is sent to the fluid medium regenerator 3.

  Next, the formation mechanism of agglomerates in the combustion furnace 2 will be described.

  The agglomerates that are the main cause of the flow failure of the fluidized bed F are mostly low melting point compound melts, that is, melts of substances formed by components in the biomass fuel adhere to the surface of the fluidized medium Fa, or the fluidized medium Fa. Eutectic formation on the surface of the fuel, that is, components in the biomass fuel are caused to chemically react on the surface of the fluid medium Fa. It is known that there are two mechanisms for agglomeration: coating induction and melting induction.

(Coating induction mechanism)
FIG. 2 (a) shows the formation of agglomerates X induced by coating. The formation of agglomerates X induced by coating is caused by a chemical reaction between vapor N of an alkaline component (potassium, sodium, etc.) in the biomass fuel and quartz particles which are the main components of the fluid medium Fa. By this chemical reaction, a sticky eutectic coating (K 2 O—SiO 2: alkali silicate phase) C is formed on the surface of the fluid medium Fa. Thereafter, the fluid media Fa on which the eutectic coating C is formed are repeatedly joined and discrete in the fluidized bed F. As a result, particle aggregation starts and gradually leads to formation of agglomer X that becomes a bottleneck (flow inhibiting factor).

  The main controlling factors of this mechanism are eutectic coating thickness (ease of bonding separation), eutectic coating composition (bonding strength) and local temperature. Moreover, as a component contained in biomass fuel, it has been confirmed that phosphorus is also an important factor in the formation of agglomer X in addition to the alkali component.

  Incidentally, the eutectic coating C starts to melt at about 700 ° C. as shown in the K 2 O—SiO 2 phase diagram of FIG. For this reason, at the temperature in the combustion furnace 2 (about 800 ° C. to 900 ° C.), the eutectic coating C is in a molten state, and the fluid media Fa easily aggregate. On the other hand, it has been confirmed that by adding magnesium oxide (MgO) into the fluid medium Fa, the melting point of the eutectic coating C can be increased and the formation of agglomerates due to the melting of the eutectic coating C can be suppressed.

(Mechanism of melting induction)
FIG. 2 (b) shows the formation of agglomerates X by melting induction. The agglomeration X due to melting induction is caused by adhesion of a low melting point compound (alkali silicate) formed by an alkali component in the biomass fuel to the surface of the fluid medium Fa of the melt M. The fluid media Fa to which the melt M adheres gradually aggregate in the fluidized bed F to reach the formation of the agglomerate X. The controlling factors of this mechanism are local temperature and fuel ash composition. In combustion ash containing a high concentration of alkali components and chlorine, agglomerates X tend to be formed through the melting induction mechanism.

  Next, the fluid medium regeneration device 3 that separates and reproduces the deposits such as the alkali silicate phase from the fluid medium Fa will be described.

  As shown in FIG. 1, the fluid medium regeneration device 3 includes a screw carrier 10 that conveys the fluid medium Fa extracted from the fluidized bed F of the combustion furnace 2 and a cooling water tank 11 that cools the fluid medium Fa. Yes. The screw conveyor 10 is connected to the discharge port 2 b of the combustion furnace 2, and conveys the high-temperature (for example, 700 ° C.) fluid medium Fa extracted from the discharge port 2 b to the cooling water tank 11. The screw conveyor 10 puts the conveyed high-temperature fluid medium Fa into the cooling water tank 11.

  A large amount of water for rapidly cooling the high-temperature fluid medium Fa that has been charged is stored in the cooling water tank 11. The cooling water tank 11 is connected to a drain line 12a, a circulation pump 13, and a charging line 12b for stirring by circulating the water in the cooling water tank 11. Moreover, the water temperature in the cooling water tank 11 is adjusted to be within a predetermined temperature range. The lower the temperature of the water, the more advantageous is the prevention of water evaporation, and the higher the temperature, the more advantageous is the prevention of cracking of the fluid medium Fa. The water temperature is preferably adjusted to be within a range of 40 to 80 ° C. In addition, a water supply line 11 a for replenishing water and a drain line 11 b for discharging water are provided at the lower part of the cooling water tank 11.

  The fluid medium Fa and the deposits put into the water in the cooling water tank 11 are rapidly cooled from a high temperature state. At this time, in the water, the deposits are peeled off due to the difference in thermal expansion between the fluid medium Fa and the deposits, and the deposits are dissolved in the water, whereby the fluid medium Fa and the deposits are separated.

  The cooling water tank 11 is connected to a return line (return means) 14 that recovers the fluid medium Fa separated from the deposit and returns it to the fluidized bed F of the combustion furnace 2. In FIG. 1, the “a” mark indicated by the arrow of the return line 14 is connected to the “a” mark side of the combustion furnace 2, and the fluid medium Fa recovered in the return line 14 is the fuel of the combustion furnace 2. It means returning to the fluidized bed F from the inlet. In the middle of the return line 14, a sorting device (not shown) for sorting the fluid medium Fa and non-combustible substances such as deposits is provided.

  According to the fluid medium regenerator 3 according to the first embodiment described above, the high-temperature fluid medium Fa extracted from the bottom of the fluidized bed F of the combustion furnace 2 is poured into water and rapidly cooled. The deposits are peeled off due to the difference in shrinkage between the medium Fa and the deposits, and the deposits are dissolved in water. This is due to the fact that the physical properties of the alkali silicate phase such as K2O-SiO2 and the fluid medium Fa such as sand differ, so that a difference in shrinkage occurs due to rapid cooling, and that K2O-SiO2 and the like melt into water. As a result, the separation of the fluid medium Fa and the deposit is realized. As described above, the fluid medium regenerator 3 uses the difference in shrinkage and the solubility in water based on the difference in physical properties between the fluid medium Fa and the deposits, so that it can be compared with a conventional device that utilizes physical collision. Thus, it is possible to regenerate the fluid medium Fa by separating the deposits from the fluid medium Fa very efficiently.

Further, according to the fluid medium regenerator 3, the fluid medium Fa separated from the deposits by the return line 14 can be recovered and returned to the fluidized bed F, so that the fluid medium Fa extracted from the fluidized bed F is removed. It is possible to return to the fluidized bed F and automatically replenish it, and to reduce the labor involved in replenishing the fluidized medium Fa.
[Second Embodiment]

  As shown in FIG. 4, the fluid medium regenerator 22 of the combustion facility 21 according to the second embodiment is the first embodiment only in that the fluid medium Fa is cooled when the fluid medium Fa is conveyed by the screw conveyor 10. And different. Hereinafter, members having the same configurations as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the fluid medium regenerator 22 according to the second embodiment, a coolant flow path (intermediate cooling means) 23 for allowing a coolant such as oil to flow around the screw carrier 10 is formed. Both ends of the cooling medium flow path 23 are connected to a circulation pipe for circulating the cooling medium, and the cooling medium tank 24 for storing the cooling medium and the cooling medium smoothly flow in the middle of the pipe. A pump 26 is provided. A cooler 25 that cools the cooling medium in the tank 24 is provided below the tank 24.

  The high-temperature (about 850 ° C.) fluid medium Fa discharged from the discharge port 2 b of the combustion furnace 2 is cooled by moving heat to the coolant in the coolant flow path 23 while being transported by the screw transporter 10. The The fluid medium Fa is cooled until the temperature immediately before being introduced into the cooling water tank 11 reaches a predetermined appropriate temperature. This appropriate temperature is a temperature at which the separation of the deposit due to the shrinkage difference between the fluid medium Fa and the deposit can be appropriately generated in water, and the fluid medium Fa itself does not crack due to rapid cooling. . The appropriate temperature is appropriately selected from 200 to 450 ° C., for example, according to the amount of water in the cooling water tank 11, the water temperature, the amount of fluid medium Fa input, and the like.

  According to the fluid medium regenerator 22 according to the second embodiment described above, the fluid medium is cooled by cooling the hot fluid medium Fa to an appropriate temperature through the coolant flow path 23 and then put into the cooling water tank 11. It becomes possible to suppress the evaporation of water and the drastic change in water temperature due to the introduction of Fa. As a result, it is possible to avoid a situation in which a large amount of water is stored in order to suppress changes in the water temperature or the water temperature is frequently adjusted, thereby reducing the size of the cooling water tank 11 and reducing the operation cost. be able to.

  The present invention is not limited to the embodiment described above.

  For example, the present invention can be applied to a fluidized bed combustion furnace other than a CFB boiler. Further, the fuel used in the combustion furnace is not limited to biomass fuel. Any fuel may be used as long as the deposit that adheres to the fluid medium Fa becomes a component that dissolves in water or a fuel that causes a sufficient shrinkage difference between the deposit and the fluid medium Fa. The present invention can be suitably applied particularly when a fuel containing a high alkali component is used.

  Further, the intermediate cooling means described in the claims is not limited to the cooling medium flow path 23 described in the second embodiment, and may be an aspect in which the fluid medium Fa is cooled by, for example, air cooling. In addition, it can also be set as the structure which utilizes the heat | fever collect | recovered by the cooling-medium flow path 23 with another installation.

  Further, the return line 14 is not necessarily provided.

  DESCRIPTION OF SYMBOLS 1,21 ... Combustion equipment, 2 ... Combustion furnace, 3,22 ... Fluid medium regeneration device, 10 ... Screw carrier, 11 ... Cooling water tank, 14 ... Return line (return means), 23 ... Coolant flow path (intermediate cooling) Means), F ... fluidized bed.

Claims (4)

A fluidized bed regenerating apparatus for a fluidized bed that regenerates the fluidized medium by separating deposits from the fluidized medium extracted from the fluidized bed of a fluidized bed combustion furnace,
Cooling that separates the deposit from the fluidized medium by using the difference in shrinkage between the fluidized medium and the deposit by cooling the fluidized medium extracted from the fluidized bed of the combustion furnace into water. A fluidized bed regenerating apparatus for a fluidized bed comprising a water tank.   2. The fluidized bed regeneration device for fluidized beds according to claim 1, further comprising intermediate cooling means for cooling the fluidized medium to a predetermined appropriate temperature before being introduced into the cooling water tank.   The fluidized bed regeneration device for a fluidized bed according to claim 1 or 2, further comprising a return means for collecting the fluidized medium from which the deposit has been separated and returning it to the fluidized bed. A fluidized bed regeneration method for a fluidized bed that regenerates the fluidized medium by separating deposits from the fluidized medium extracted from the fluidized bed of a fluidized bed combustion furnace,
Separating the deposit from the fluidized medium by using the difference in shrinkage between the fluidized medium and the deposit by cooling the fluid medium extracted from the fluidized bed of the combustion furnace into water. A fluidized bed regeneration method for fluidized beds.

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