JP2009229056A - Circulating type fluidized bed furnace, treatment system with circulating type fluidized bed furnace and operating method for circulating type fluidized bed furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circulating type fluidized bed furnace and a treatment system with the circulating type fluidized bed furnace, providing a sufficient desalting efficiency together with desulfurization by in-furnace desulfurization and easily and inexpensively performing desulfurization and desalination. <P>SOLUTION: In the circulating type fluidized bed furnace 1, waste including chlorine content is mixed with a fluid medium and burned, and the fluid medium is separated and collected from combustion exhaust gas by a cyclone 3 and circulated and used. A desulfurization material comprising powder of Ca compound is charged to perform in-furnace desulfurization. The maximum particle size of the desulfurization material is 100 μm or less, and the cyclone 3 has particle separation performance for collecting the fluid medium and discharging the desulfurization material along with the combustion exhaust gas. By the desulfurization material discharged along with the combustion exhaust gas, desulfurization and desalination are performed on a gas duct 21 extended from the cyclone 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a circulating fluidized bed furnace for incinerating wastes such as sewage sludge, municipal waste, and industrial waste, and a system including the circulating fluidized bed furnace. The present invention relates to a circulating fluidized bed furnace for performing a desulfurization reaction and a desalting reaction, and a system including the circulating fluidized bed furnace.

  Conventionally, circulation type fluidized bed furnaces are widely used in the combustion treatment of wastes such as sewage sludge, municipal waste and industrial waste. The circulating fluidized bed furnace burns and disperses the waste and fluid medium while mixing them with the primary air introduced from the bottom of the riser, and entrains the dispersed fluid medium into the freeboard by introducing secondary air. The unburned portion of the inside is completely burned, the fluidized medium is separated from the combustion exhaust gas by a cyclone, and returned to the riser to circulate and use the fluidized medium. Such a circulating fluidized bed furnace can instantly dry and incinerate waste, thereby maintaining a fluid medium at a high temperature and enabling continuous combustion. In addition, since the heat capacity of the fluidized medium is very large, it is suitable for intermittent operation with little heat dissipation when stopped, and the fluidized medium has a high thermal conductivity, so it has a high water content such as sewage sludge. It is also suitably used for products.

Some of the wastes described above contain a sulfur component, and sulfur oxides (SOx) such as SO ₂ may be generated during combustion treatment in a circulating fluidized bed furnace. Since exhaust gas containing sulfur oxides causes air pollution and acid rain and is harmful to human bodies, it is necessary to desulfurize it to remove it.
The desulfurization method includes a wet method, a semi-dry method, and a dry method, and a smoke washing tower (scrubber), which is one of the wet methods, is used more than ever. The scrubber sprays cleaning water to which an alkaline agent has been added to the combustion exhaust gas, and neutralizes and treats acidic gases such as SOx. However, scrubbers often use caustic soda (NaOH) as an alkaline agent, but the cost of chemicals is high and maintenance is also expensive. In addition, the scrubber was limited to a place where sufficient water could be secured and no wastewater treatment costs were incurred. Furthermore, since the SOx concentration in the exhaust gas is high up to the scrubber, there is a problem that corrosion tends to occur when the dew point is below the flue.

On the other hand, one of the dry methods is an in-furnace desulfurization method in which a desulfurization material is directly blown into the furnace. The in-furnace desulfurization method is widely used as a simple method such as simple modification of equipment and not using water. The most frequently used desulfurization materials are Ca-based solid desulfurization materials such as limestone (CaCO ₃ ), slaked lime (Ca (OH) ₂ ), and dolomite (CaCO ₃ .MgCO ₃ ). In general in-furnace desulfurization, a desulfurization material having approximately the same particle size as that of the fluidized medium is used, and the desulfurization material introduced into the furnace is circulated together with the fluidized medium to ensure a residence time and improve the desulfurization efficiency. I was planning.
A circulating fluidized bed furnace that performs such in-furnace desulfurization is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2002-130637) and the like.
Further, Patent Document 2 (Japanese Patent No. 3790431) discloses an apparatus for performing desulfurization in a furnace by introducing a desulfurization material into the furnace so as to have a 2Ca / S equivalent ratio or more.

JP 2002-130637 A Japanese Patent No. 3790431

However, when conventional in-furnace desulfurization is applied to waste containing chlorine, although a part of the desulfurization reaction is performed by the desulfurization material, HCl in exhaust gas or fly ash cannot be sufficiently removed. Therefore, it has been necessary to blow slaked lime into the flue for desalination, but two types of chemicals are required, limestone and slaked lime, and there remains a problem that handling is troublesome in addition to an increase in cost.
Further, when the desulfurization material is circulated and used together with the fluidized medium, the desulfurization material accumulates, the circulating particles in the furnace increase, and the furnace pressure increases. As a result, the fluid medium must be frequently extracted, and the blower capacity for supplying air for blowing up the increased circulating particles has to be increased.

  Therefore, in view of the above-mentioned problems of the prior art, the present invention can obtain sufficient demineralization efficiency together with desulfurization by in-furnace desulfurization, and can perform desulfurization and demineralization easily and at low cost. It aims at providing the processing system provided with the type | mold fluidized bed furnace and this circulation type fluidized bed furnace.

Therefore, in order to solve such problems, the present invention mixes and burns chlorine-containing waste with a fluid medium, separates and collects the fluid medium from the combustion exhaust gas using a cyclone, and circulates it. In a circulating fluidized bed furnace in which a desulfurization material made of a powder of
The maximum particle size of the desulfurization material is 100 μm or less,
The cyclone collects the fluid medium, while the desulfurization material has a particle separation performance to be discharged with combustion exhaust gas;
The desulfurization material discharged along with the exhaust gas is characterized in that desulfurization and desalting are performed on a flue extending from the cyclone.

ADVANTAGE OF THE INVENTION According to this invention, a desalination reaction can be accelerated | stimulated on a flue by making a desulfurization material accompany combustion exhaust gas, and discharging to a flue, and it can improve desalination efficiency.
In addition, since the particle size of the desulfurization material is as small as 100 μm or less, the reaction area is increased, and the in-furnace reaction efficiency of desulfurization and demineralization is improved. Further, by promoting desalting, generation of dioxins and ammonium chloride can be suppressed.
Furthermore, since the amount of the desulfurizing material remaining in the furnace decreases, the furnace pressure can be kept low. As a result, the number of fluid medium extractions from the furnace bottom can be reduced, and the blower capacity can be reduced. Moreover, since the circulating particle diameter becomes small, refractory material wear in the furnace can be reduced. Furthermore, since a desulfurization material with a small particle diameter is cheaper than a large desulfurization material, cost reduction can be achieved.

Further, the cyclone has a particle separation performance for collecting particles having a particle diameter of 150 μm or more.
In general, since the fluidized medium has a particle size of about 200 μm, it can be reliably collected by a cyclone, and only a desulfurized material of 100 μm or less can be accompanied by combustion exhaust gas and discharged.

Furthermore, the amount of the desulfurized material introduced is such that the Ca / (S + Cl) equivalent ratio at the furnace inlet is 3.5 or more.
In this way, by making the input amount of the desulfurization material to be an input amount at which the Ca / (S + Cl) equivalent ratio at the inlet of the furnace becomes 3.5 or more, the unreacted Ca content and HCl discharged from the cyclone are sufficient. To obtain a high desalting efficiency.

Furthermore, the desulfurization material is mixed with the waste and is put into a furnace.
Thereby, even if it is a desulfurization material of a small particle size, this desulfurization material can be reliably supplied to the lower part of a furnace, it becomes possible to earn sufficient residence time, and it can improve desulfurization efficiency and desalination efficiency by extension. It becomes possible. Further, the reaction occurring in the lower part of the furnace where the mixing is most intense also contributes to the improvement of the desulfurization efficiency.

The circulation type fluidized bed furnace, and an exhaust gas treatment facility installed on a flue extending from the cyclone of the circulation type fluidized bed furnace, wherein the exhaust gas treatment facility at least contains fly ash in the combustion exhaust gas. In a processing system having a dust removing device to collect,
The dust removing device is a filter type dust removing device including a bag filter or a ceramic filter.
As a result, the small particle size desulfurization material is supplemented by the filter type dust removing device, so that the desalting reaction can be caused more efficiently. More preferably, the differential pressure of the filter type dust remover is controlled and the cake layer deposited on the filter is kept thick, and thereby the desalting reaction is further promoted by the desulfurization material held in the cake layer.

  The operation method of the circulating fluidized bed furnace according to the present invention includes a riser that mixes and burns waste with a fluid medium to generate combustion exhaust gas, collects the fluid medium from the combustion exhaust gas, An operation method of a circulating fluidized bed furnace comprising a cyclone that discharges to a flue and returns the fluid medium to the riser. This operation method includes a step of supplying a first desulfurization material into the riser. The particle diameter of the first desulfurization material is a particle diameter that is discharged to the flue side by the cyclone.

  According to this invention, the first desulfurization material is discharged to the flue side by the cyclone together with the combustion exhaust gas. Thereby, combustion exhaust gas can be desalted with a 1st desulfurization material in a flue side.

  A circulating fluidized bed furnace according to the present invention comprises a riser that mixes and combusts waste with a fluidized medium to generate combustion exhaust gas, collects the fluidized medium from the combustion exhaust gas, and uses the combustion exhaust gas in a flue. A cyclone that discharges and returns the fluid medium to the riser and a first desulfurization material supply mechanism that supplies a first desulfurization material to the riser are provided. The particle diameter of the first desulfurization material is a particle diameter that is discharged to the flue side by the cyclone.

As described above, according to the present invention, by allowing the desulfurization material to accompany the combustion exhaust gas and discharging it to the flue, the desalination reaction can be promoted on the flue, and the desalination efficiency can be improved. is there. In addition, since the particle size of the desulfurization material is as small as 100 μm or less, the reaction area is increased, and the in-furnace reaction efficiency of desulfurization and demineralization is improved.
Furthermore, since the amount of desulfurizing material remaining in the furnace is reduced, the pressure in the furnace can be kept low, the number of fluid medium extractions from the furnace bottom can be reduced, and the blower capacity can be reduced. Furthermore, since a desulfurization material with a small particle diameter is cheaper than a large desulfurization material, cost reduction can be achieved.

In addition, the cyclone has a particle separation performance for collecting particles having a particle diameter of 150 μm or more, so that it can reliably collect a fluid medium and discharge only a desulfurized material of 100 μm or less with combustion exhaust gas. It becomes possible.
Furthermore, by setting the input amount of the desulfurization material to an input amount at which the Ca / (S + Cl) equivalent ratio is 3.5 or more, the unreacted Ca component discharged from the cyclone sufficiently reacts with HCl, and high desulfurization is achieved. Salt efficiency can be obtained.
Furthermore, by mixing the desulfurization material with waste in advance, the desulfurization material can be reliably supplied to the lower part of the furnace even if the desulfurization material has a small particle size, and a sufficient residence time is obtained. It becomes possible.
In addition, by using a filter type dust removing device for the exhaust gas treatment facility, a small particle size desulfurization material is supplemented by the filter type dust removing device, so that a desalting reaction can be caused more efficiently.

1 is an overall configuration diagram of a system including a circulating fluidized bed furnace according to an embodiment of the present invention. It is a whole block diagram of the system provided with the circulation type fluidized bed furnace which shows the application example of the Example of this invention. It is a graph which shows the desulfurization rate and the desalination rate with respect to desulfurization material input. It is a figure which shows a combustion exhaust gas property. It is the schematic for demonstrating the effect | action of a desulfurization material. It is a whole block diagram which shows the system provided with the circulation type fluidized bed furnace which concerns on a 2nd Example.

(First embodiment)
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
The treatment target in the circulation type fluidized bed furnace of the present embodiment is waste containing chlorine, and examples thereof include sewage sludge, municipal waste, industrial waste, etc., and in particular, the circulation type fluidized bed furnace of the present embodiment. Is suitably used for the treatment of sewage sludge. The circulating fluidized bed furnace combusts these wastes and performs desulfurization in the furnace by introducing a desulfurizing material to perform desulfurization and desalting.

  With reference to FIG. 1, the circulating fluidized bed furnace and the processing system of the present embodiment will be described. In the figure, a circulating fluidized bed furnace 1 includes a riser 2 comprising a fluidized bed 2a obtained by fluidizing a fluid medium such as silica sand filled in the furnace bottom, and a free board 2b positioned above the fluidized bed 2a. The cyclone 3 connected to the upper part of 2 and collects the fluid medium blown up from the free board 2b and exhausts the exhaust gas separated from the fluid medium to the flue 21, and is connected to the cyclone 3 via the downcomer 4. The main components are a seal pot 5 that prevents the unburned gas in the furnace from being blown into the cyclone 3, and a fluid medium return pipe 6 that returns the fluid medium stored in the seal pot 5 to the riser 2.

A primary air inlet 11 is provided at the bottom of the riser 2, and the fluidized medium is fluidized by the primary air introduced from the primary air inlet 11 to form a fluidized bed 2 a. The riser furnace wall above the fluidized bed 2a is provided with a secondary air introduction port (not shown), and the cylinder speed of the free board 2b is maintained by the secondary air introduced from the secondary air introduction port. Unburned matter is burned.
Above the fluidized bed 2 a of the riser 2, waste input means 12 is provided. The waste input unit 12 has a configuration in which the waste received from the waste input hopper is input into the furnace in an appropriate amount by a supply feeder.

The circulating fluidized bed furnace 1 includes a desulfurization material inlet 13 for introducing a desulfurized material into the furnace and a fluid medium inlet (not shown) for introducing a fluid medium. The desulfurization material inlet 13 and the fluid medium inlet may be installed anywhere as long as the circulation system of the fluid medium. Preferably, the desulfurization material inlet 13 is connected to the secondary air inlet of the riser 2. Install on the lower side.
The desulfurization material introduced into the furnace from the desulfurization material charging port 13 is a desulfurization material made of Ca compound powder. The desulfurization material is a desulfurization material having a maximum particle size of 100 μm or less. As the desulfurizing material, for example, limestone (CaCO ₃ ), slaked lime (Ca (OH) ₂ ), dolomite (CaCO ₃ .MgCO ₃ ), or the like is used.

The cyclone 3 separates and collects the fluid medium from the combustion exhaust gas, while the desulfurization material has a particle separation performance that is accompanied by the exhaust gas and discharged to the flue 21. Preferably, the cyclone 3 has a particle separation performance for collecting particles having a particle diameter of 150 μm or more.
An exhaust gas treatment facility for treating the combustion exhaust gas separated by the cyclone 3 is provided on the flue 21 extending from the cyclone 3.
The exhaust gas treatment facility has a configuration in which an air preheater 22, a waste heat boiler 23, a gas cooling tower 24, and a bag filter 25 are arranged in series.
The air preheater 22 exchanges heat between the air introduced by the pushing fan 15 and the combustion exhaust gas from the cyclone 3, and preheats the primary air or the secondary air. The waste heat boiler 23 heats feed water with combustion exhaust gas and generates steam. The gas cooling tower 24 cools the combustion exhaust gas by heat exchange with cooling water. The bag filter 25 is a device that collects and removes fly ash in the cooled exhaust gas. The combustion exhaust gas passes through the exhaust gas treatment facility described above by an induction fan 26 installed at the rear stage of the bag filter 25 and is then discharged from the chimney 27 to the outside of the system.

  Note that the exhaust gas treatment facility is not limited to the above-described configuration, and is configured by selecting a necessary apparatus as appropriate. As another configuration example, as shown in FIG. 2, there is a configuration in which an air preheater 22, a waste heat boiler 23, and a ceramic filter 28 are arranged in series. Thus, the exhaust gas treatment facility applied to the present embodiment may have any configuration as long as it includes at least a dust removing device (such as the bag filter 25 or the ceramic filter 28).

In the circulating fluidized bed furnace having the above configuration, the waste charged into the furnace by the waste charging means 12 is mixed with the fluidized medium in the fluidized bed 2a and burned, and unburned in the free board 2b. Is completely burned, and is desulfurized in the furnace by the desulfurization material introduced from the desulfurization material inlet 13. In the in-furnace desulfurization, SOx is removed mainly by a desulfurization reaction represented by the following reaction formula (1).
SO ₂ + CaO + 1 / 2O ₂ → CaSO ₄ (1)
CaO is produced by desulfurization materials such as limestone and slaked lime receiving heat in the furnace.
Further, in the furnace, a part of HCl is removed by the desulfurization reaction shown in the following reaction formula (2) by the desulfurization material.
2HCl + CaO → CaCl ₂ + H ₂ O (2)

However, since the desalination efficiency in the furnace is not large, HCl remains in the combustion exhaust gas or fly ash.
Therefore, in this embodiment, the maximum particle size of the desulfurization material introduced into the furnace is 100 μm or less, and the cyclone 3 collects the fluid medium, while the desulfurization material is accompanied by the combustion exhaust gas and discharged. Since it is configured to have performance, an unreacted desulfurization material is entrained in the combustion exhaust gas separated from the fluid medium by the cyclone 3 and discharged to the flue 21.
Then, desalting is performed in the flue 21 by the discharged desulfurized material. Of course, desulfurization is simultaneously performed. In desalting, the reaction efficiency is improved particularly when the temperature is lowered. Therefore, most of the HCl is removed when passing through the flue 21.

According to the present embodiment, by allowing the desulfurization material to accompany the combustion exhaust gas and discharging it to the flue 21, the desalting reaction can be promoted on the flue, and the desalting efficiency can be improved.
In addition, since the particle size of the desulfurization material is as small as 100 μm or less, the reaction area is increased, and the in-furnace reaction efficiency of desulfurization and demineralization is improved. Further, by promoting desalting, generation of dioxins and ammonium chloride can be suppressed.
Furthermore, since the amount of the desulfurizing material remaining in the furnace decreases, the furnace pressure can be kept low. As a result, the number of fluid medium extractions from the furnace bottom can be reduced, and the blower (pushing fan 15) capacity can be reduced. Furthermore, since the size of the circulating particles is reduced, refractory material wear in the furnace can be reduced. Moreover, since a desulfurization material with a small particle diameter is cheaper than a large desulfurization material, cost reduction can be achieved.

  Further, the cyclone 3 preferably has a particle separation performance for collecting particles having a particle diameter of 150 μm or more. In general, since the particle diameter of the fluid medium is about 200 μm, the cyclone 3 can surely collect it, and only the desulfurized material of 100 μm or less can be accompanied by the combustion exhaust gas and discharged.

Further, the input amount of the desulfurization material is preferably set so that the Ca / (S + Cl) equivalent ratio at the inlet of the furnace is 3.5 or more.
FIG. 3 shows the desulfurization rate and the demineralization rate with respect to the desulfurization material input amount. As shown in this graph, the desulfurization rate shows a relatively high value even when the Ca / (S + Cl) equivalent ratio is small.
On the other hand, the desalination rate is rapidly increasing with the Ca / (S + Cl) equivalent ratio being 3.5.
Therefore, the amount of unreacted Ca and HCl discharged from the cyclone can be sufficiently increased by setting the amount of desulfurization material introduced in this manner so that the Ca / (S + Cl) equivalent ratio in the furnace becomes 3.5 or more. To obtain a high desalting efficiency.

  Further, in this embodiment, it is preferable that the dust removal device of the exhaust gas treatment facility is a filter type dust removal device including a bag filter or a ceramic filter, whereby the small particle size desulfurization material is supplemented by this filter type dust removal device. Thus, it is possible to cause the desalting reaction more efficiently. More preferably, the differential pressure of the filter type dust remover is controlled to keep the cake layer deposited on the filter thick, and the desalting reaction is further promoted by the desulfurization material retained in the cake layer.

Further, as shown in FIG. 2, it is preferable that the desulfurization material is mixed with the waste in advance and put into the furnace by the waste throwing means 12.
Thereby, even if it is a desulfurization material of a small particle size, this desulfurization material can be reliably supplied to the lower part of a furnace, it becomes possible to earn sufficient residence time, and it can improve desulfurization efficiency and desalination efficiency by extension. It becomes possible. Further, the reaction occurring in the lower part of the furnace where the mixing is most intense also contributes to the improvement of the desulfurization efficiency.

  In the present embodiment, the case where the cyclone 3 has a particle separation performance for collecting particles having a particle diameter of 150 μm or more and the maximum particle diameter of the desulfurized material is 100 μm or less has been described. However, if the average particle size of the desulfurized material is smaller than the critical particle size of the cyclone 3, the same effect can be obtained. For example, when the limit particle diameter of the cyclone 3 is 150 μm, a desulfurization material having an average particle diameter smaller than 150 μm can be used. Even in such a case, since most of the desulfurization material is discharged to the flue, HCl can be efficiently removed.

  In addition, the maximum particle diameter as used in this specification can be calculated | required according to the weight cumulative distribution obtained according to "JIS M 8511; Industrial analysis and test method of natural graphite" of Japanese Industrial Standard (JIS standard).

In addition, the average particle diameter referred to in the present specification is the median diameter (median diameter d ₅₀ ) at which the cumulative weight becomes 50% from the cumulative weight distribution according to the above-mentioned “JIS M 8511; Industrial Analysis and Test Method of Natural Graphite”. Can be obtained by calculating.

  Further, the critical particle size of the cyclone 3 in the present specification can be determined as follows. That is, a desulfurization material having a sufficiently wide particle size distribution is introduced into the cyclone 3. Then, the desulfurized material discharged from the cyclone 3 is collected as a discharged desulfurized material. Then, the minimum particle diameter of the discharged desulfurization material is obtained as the limit particle diameter of the cyclone 3.

(Second embodiment)
Subsequently, a second embodiment of the present invention will be described.

In the first embodiment, the desalting effect can be improved by using a desulfurization material having an average particle size smaller than the critical particle size of the cyclone 3. By the way, the waste thrown into the circulating fluidized bed furnace may contain a nitrogen compound. When nitrogen compounds are contained in the waste, nitrogen compounds (such as NH ₃ , HCN, and N ₂ O) are also contained in the exhaust gas in the furnace. For example, when sewage sludge is input as waste, the content of nitrogen compounds tends to increase. And when the present inventors used only the desulfurization material (henceforth a 1st desulfurization material) whose average particle diameter is smaller than the limit particle diameter of the cyclone 3, the nitrogen compound ( It has been found that the concentration of NH ₃ , HCH, N ₂ O, etc. increases.

FIG. 4 is a diagram showing the combustion exhaust gas properties. FIG. 4 shows the result when only the first desulfurization material is used as the desulfurization material, and the desulfurization material having an average particle diameter larger than the critical particle diameter of the cyclone 3 (hereinafter referred to as a second desulfurization material). And the results when using only. In FIG. 4, a represents CO, b represents SO ₂ , c represents NOx, d represents HCl, e represents HCN, and f represents NH ₃ . As shown in FIG. 4, when only the first desulfurizing material is used, the HCl concentration can be reduced compared to the case where only the second desulfurizing material is used, but the HCN concentration and NH ₃ concentration are increased. It is confirmed that.

  The following mechanism can be considered as the reason why the nitrogen compound increases.

FIG. 5 is a schematic diagram for explaining the action of the desulfurization material in a system including a circulating fluidized bed furnace. FIG. 5 shows a diagram when calcium carbonate (CaCO ₃ ) is used as the desulfurization material. As shown in FIG. 5, the inside of the furnace (riser) is usually at a high temperature (for example, about 850 ° C.). CaCO ₃ charged into the furnace is oxidized at a high temperature to generate CaO. The produced CaO undergoes a desulfurization reaction, which is the original role of the desulfurization material, and SOx is changed to CaSO ₄ . Further, on the flue side at a relatively low temperature (for example, about 200 ° C.), CaO undergoes a desalting reaction with HCl, and CaCl ₂ is generated.

It is considered that CaO present in the furnace catalyzes not only desulfurization reaction but also oxidation reaction of nitrogen compound in a high temperature atmosphere. That is, as shown in FIG. 5, nitrogen compounds such as NH ₃ , HCN, and N ₂ O are considered to be oxidized and generate NOx by the catalytic action of CaO. This reaction occurs particularly at the lower part of the riser where the sludge pyrolysis reaction occurs. The reason is as follows. The sludge thrown into the riser has a large specific gravity, and therefore first stays in the lower part of the riser. Since the primary air supplied to the lower portion of the riser does not contain oxygen enough to completely incinerate the sludge, a thermal decomposition reaction of the sludge occurs in the lower portion of the riser, and NH ₃ , HCN, and N ₂ are generated from N content in the sludge. Nitrogen compounds such as O are generated. Thus, since the nitrogen compound concentration in the lower part of the riser is high, the oxidation reaction of the nitrogen compound by CaO tends to occur in the lower part of the riser. On the other hand, in the upper portion of the riser, since the oxidation of the nitrogen compound by the secondary air proceeds, the nitrogen compound concentration is low, so that the oxidation reaction of the nitrogen compound by CaO hardly occurs.

  Here, when only the first desulfurization material is used as in the first embodiment, the first desulfurization material charged into the riser is entrained by the gas in the furnace and blown upward. It is difficult to collect at the bottom. Further, since the first desulfurization material is discharged from the cyclone, it is not supplied to the lower portion of the riser through the downcomer. For this reason, the action of the nitrogen compound as an oxidation catalyst is not sufficiently exhibited. As a result, it is considered that the nitrogen compound concentration in the exhaust gas increases.

  Therefore, in this embodiment, a device for promoting the oxidation reaction of the nitrogen compound in the furnace is taken.

  FIG. 6 is an overall configuration diagram showing a system including a circulating fluidized bed furnace according to the present embodiment. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 6, the system of this embodiment includes a first desulfurization material supply mechanism 36, a second desulfurization material supply mechanism 37, a pressure sensor 31, a pressure sensor 32, a differential pressure measurement mechanism 33, and a concentration measurement mechanism 34. In addition, a fluid medium extraction mechanism 35, a fan 38, and an air preheater 39 are depicted. Further, as the desulfurization material input port 13, a first desulfurization material input port 13-1 and a second desulfurization material input port 13-2 are provided.

  The first desulfurization material supply mechanism 36 supplies the first desulfurization material into the riser 2 from the first desulfurization material input port 13-1. The particle size of the first desulfurization material is such a particle size that is discharged to the flue 21 side in the cyclone 3.

  The second desulfurization material supply mechanism 37 supplies the second desulfurization material into the riser 2 from the second desulfurization material inlet 13-2. Unlike the first desulfurized material, the particle size of the second desulfurized material is a particle size that is collected together with the fluid medium in the cyclone 3. Specifically, as the second desulfurizing material, a desulfurizing material having an average particle size larger than the critical particle size of the cyclone 3 is used.

  The differential pressure measurement mechanism 33 is provided for measuring the differential pressure between the upper part and the lower part in the riser 2. A pressure sensor 31 is attached to the upper portion of the riser, and a pressure sensor 32 is attached to the lower portion of the riser. The differential pressure measurement mechanism 33 measures the differential pressure in the riser 2 based on the pressure measurement results obtained by the pressure sensor 31 and the pressure sensor 32.

  The concentration measuring mechanism 34 is provided in the flue 21. The concentration measuring mechanism 34 measures the NOx component concentration in the combustion exhaust gas. The concentration measuring mechanism 34 is not necessarily provided in the flue 21. It may be provided at other locations as long as it can measure the component concentration in the combustion exhaust gas.

  The fluid medium extraction mechanism 35 is provided at the bottom of the riser 2. The fluid medium extraction mechanism 35 is provided for extracting the fluid medium from the fluidized bed 2a.

  The fan 38 is connected above the fluidized bed 2 a in the riser 2 via the air preheater 39. The fan 38 supplies the combustion air as secondary air above the fluidized bed 2a.

  The fan 38 constitutes a combustion control mechanism together with the fan 15 that supplies primary air. That is, by controlling the amount of secondary air supplied by the fan 38 and the amount of primary air supplied by the fan 15, it is possible to control the ease of combustion in the riser 2.

  Subsequently, an operation method of the circulating fluidized bed furnace according to the present embodiment will be described.

  The waste thrown into the riser 2 by the waste throwing means 12 is mixed with the fluidized medium by the fluidized bed 2a and burned to generate combustion exhaust gas. Here, the first desulfurization material supply mechanism 36 and the second desulfurization material supply mechanism 37 supply the first desulfurization material and the second desulfurization material into the riser 2. Due to the presence of the desulfurizing material, the combustion exhaust gas is desulfurized. The combustion exhaust gas in the riser 2 is guided to the cyclone 3 together with the first desulfurization material, the second desulfurization material, and the fluid medium.

  In the cyclone 3, only the second desulfurization material and the fluid medium are collected and returned to the riser 2. On the other hand, the first desulfurization material and the combustion exhaust gas are discharged from the cyclone 3 to the flue 21. The first desulfurization material discharged into the flue demineralizes the flue gas as in the above-described embodiment, and it is possible to remove HCl in the flue gas passing through the flue 21.

  Here, when only the first desulfurization material is supplied, the desulfurization material does not circulate in the circulating fluidized bed furnace. Accordingly, the concentration of the desulfurization material in the riser 2 cannot be maintained sufficiently.

  In contrast, in this embodiment, since the second desulfurization material is returned to the riser 2, it is possible to prevent the desulfurization material concentration in the riser 2 from decreasing. As a result, the desulfurization action in the riser 2 and the oxidation action of the unburned components can be promoted while performing the desalting in the flue 21.

  The particle size of the first desulfurizing material will be described. For example, it is assumed that the cyclone 3 is configured to discharge particles of 150 μm or less and collect particles larger than 150 μm. That is, it is assumed that the critical particle diameter of the cyclone 3 is 150 μm. In this case, it is preferable to use a first desulfurization material having a maximum particle size smaller than 150 μm.

  The particle size of the second desulfurization material will be described. It is assumed that the cyclone 3 is configured to discharge particles of 150 μm or less and collect particles larger than 150 μm. That is, it is assumed that the critical particle diameter of the cyclone 3 is 150 μm. In this case, it is preferable to use a material having an average particle size larger than 150 μm as the second desulfurization material. Thereby, the density | concentration of the desulfurization material in a furnace, especially the riser lower part can fully be maintained, and the oxidation reaction of a nitrogen compound can fully be accelerated | stimulated. Moreover, it is preferable that the average particle diameter of a 2nd desulfurization material is 350 micrometers or less. When the average particle diameter exceeds 350 μm, the second desulfurization material may accumulate on the lower portion of the riser 2 and may not be easily blown up to the upper portion. As a result, the desulfurization action, the oxidation catalyst action and the like are not sufficiently exhibited. Further, the power required for the fan 15 also increases.

  When the critical particle diameter of the cyclone 3 is 150 μm, the second desulfurization material is more preferably an average particle diameter larger than 150 μm and the particle diameter of most particles (50% or more on a weight basis) is 100 μm or more. It is preferable to use one within the range of 350 μm or less. If a desulfurization material having a particle size distribution in such a range is used, the second desulfurization material is reliably accumulated in the furnace by long-time operation, and the second desulfurization material is not easily blown upward.

  As a kind of 1st desulfurization material and 2nd desulfurization material, the same kind (limestone, slaked lime, dolomite, etc.) as the desulfurization material of the above-mentioned Example can be used.

  The input amounts of the first desulfurization material and the second desulfurization material are preferably such input amounts that the Ca / (S + Cl) equivalent ratio at the furnace inlet is 3.5 or more, as in the above-described embodiments. . This input amount can be determined by measuring the component ratio of waste in advance.

  In this embodiment, the concentration measurement mechanism 34 measures the NOx concentration in the combustion exhaust gas. Based on the measurement result of the concentration measurement mechanism 34, the operation of the combustion control mechanism (fan 15 and fan 38) is controlled.

As described above, in the present embodiment, the oxidation of the unburned components in the riser 2 is promoted by the second desulfurization material. Among the unburned components, when nitrogen compounds (HCN, NH ₃ , etc.) are oxidized, NOx may be generated. Therefore, when the NOx concentration in the combustion exhaust gas becomes higher than a predetermined value, the environment in the riser 2 becomes an environment in which combustion (oxidation) hardly occurs by the combustion control mechanism (fan 15 and fan 38). As controlled. Specifically, by reducing the supply amount of primary air and secondary air, or reducing the supply ratio of primary air to secondary air, the environment is controlled in which oxidation reaction hardly occurs. Thereby, the increase in the NOx concentration is suppressed, and the NOx concentration in the combustion exhaust gas can be suppressed.

  When the NOx concentration cannot be sufficiently suppressed only by the combustion control mechanism, the second desulfurization material supply mechanism 37 reduces the supply amount of the second desulfurization material. Thereby, the oxidation reaction in the riser 2 is reliably suppressed, and the NOx concentration in the combustion exhaust gas can be reliably suppressed.

  In this embodiment, the differential pressure at the upper and lower portions of the riser 2 is measured by the differential pressure measuring mechanism 33 during operation. As described above, the second desulfurization material circulates in the circulating fluidized bed furnace. Therefore, the differential pressure in the furnace can be controlled by controlling the supply amount of the second desulfurization material. Therefore, based on the measurement result by the differential pressure measuring mechanism 33, the second desulfurized material supply mechanism 37 controls the supply amount of the second desulfurized material so that the differential pressure in the riser 2 is constant.

  The differential pressure in the riser 2 depends on the amount of particles present in the riser 2. That is, the amount of particles in the riser 2 can be controlled to be constant by controlling the differential pressure existing in the riser 2 to be constant. By controlling the amount of particles in the riser 2 to be constant, the temperature in the riser 2 can be made uniform. Further, since the differential pressure is constant, the contact between the solid component and the gas component is promoted, and the desulfurization reaction, the oxidation reaction, and the like can be promoted.

  Specifically, when the measurement result of the differential pressure becomes smaller than a predetermined value, the second desulfurization material is supplemented by the second desulfurization material supply mechanism 37. On the other hand, when the differential pressure becomes larger than a predetermined value, the second desulfurization material supply mechanism 37 stops the supply of the second desulfurization material. Further, the fluid medium extraction mechanism 35 discharges the second desulfurization material together with the fluid medium from the fluidized bed 2a.

  As described above, according to the present embodiment, by using the first desulfurization material and the second desulfurization material, the desalination action is promoted in the flue 21, and the oxidation action in the riser 2 is thereby increased. Can be promoted.

  Further, when the NOx concentration becomes high, the oxidizing action in the riser 2 is suppressed by the concentration measuring mechanism 34 and the combustion control mechanism (fan 15, fan 38). Thereby, the NOx concentration can be suppressed.

  In addition, the amount of particles in the riser 2 can be kept constant by the differential pressure measurement mechanism 33, the second desulfurization material supply mechanism 37, and the fluid medium extraction mechanism 35. Thereby, the temperature in the riser 2 can be equalized. Further, the desulfurization reaction can be promoted by promoting solid-gas contact.

  In addition, in the present Example, the case where the 1st desulfurization material input port 13-1 and the 2nd desulfurization material input port 13-2 were provided separately was demonstrated. However, these are not necessarily separate, and the first desulfurization material and the second desulfurization material may be input from a common input port.

  Similarly to the above-described embodiment, the first desulfurization material supply mechanism 36 and the second desulfurization material supply mechanism 37 mix the first desulfurization material and the second desulfurization material with the waste by the waste input means 12. Then, it may be put into the riser 2. Thereby, a desulfurization material can be reliably supplied to the lower part of the riser 2, and the residence time of the desulfurization material in the riser 2 can be lengthened. As a result, the desulfurization efficiency can be increased. Further, desulfurization is performed at the lower portion of the riser 2 where mixing is most intense, and it is possible to increase the desulfurization efficiency from this viewpoint.

  According to the present invention, sufficient demineralization efficiency can be obtained together with desulfurization by in-furnace desulfurization, and desulfurization and demineralization can be performed easily and at low cost. Therefore, sewage sludge, municipal waste, industrial The present invention can be suitably applied to a circulating fluidized bed furnace for incinerating waste containing chlorine such as waste and a system including the same.

DESCRIPTION OF SYMBOLS 1 Circulation type fluidized bed furnace 2 Riser 2a Fluidized bed 2b Free board 3 Cyclone 5 Seal pot 12 Waste input means 13 Desulfurization material input 21 Flue 22 Air preheater 23 Waste heat boiler 24 Gas cooling tower 25 Bag filter 28 Ceramic filter 31 Pressure sensor 32 Pressure sensor 33 Differential pressure measurement mechanism 34 Concentration measurement mechanism 35 Fluid medium extraction mechanism 36 First desulfurization material supply mechanism 37 Second desulfurization material supply mechanism 38 Fan 39 Air preheater

Claims (29)

Waste containing chlorine is mixed with a fluid medium and combusted. The fluid medium is separated and collected from the combustion exhaust gas by a cyclone and recycled, and a desulfurization material made of Ca compound powder is introduced into the furnace. In a circulating fluidized bed furnace that performs desulfurization,
The maximum particle size of the desulfurization material is 100 μm or less,
The cyclone collects the fluid medium, while the desulfurization material has a particle separation performance to be discharged with combustion exhaust gas;
A circulating fluidized bed furnace characterized in that desulfurization and desalting are performed on a flue extending from the cyclone with a desulfurization material discharged accompanying the exhaust gas.   The circulating fluidized bed furnace according to claim 1, wherein the cyclone has a particle separation performance for collecting particles having a particle diameter of 150 µm or more.   The circulating fluidized bed furnace according to claim 1 or 2, wherein the desulfurization material is charged so that the Ca / (S + Cl) equivalent ratio at the furnace inlet is 3.5 or more.   The circulating fluidized bed furnace according to any one of claims 1 to 3, wherein the desulfurization material is mixed with the waste and charged into the furnace. The circulating fluidized bed furnace according to any one of claims 1 to 4, wherein the desulfurization material is limestone (CaCO ₃ ) powder. A circulation type fluidized bed furnace according to any one of claims 1 to 5, and an exhaust gas treatment facility installed on a flue extending from a cyclone of the circulation type fluidized bed furnace, wherein the exhaust gas treatment facility is at least A processing system having a dust removal device for collecting fly ash in the combustion exhaust gas,
A processing system comprising a circulating fluidized bed furnace, wherein the dust removing device is a filter type dust removing device including a bag filter or a ceramic filter. A riser that mixes waste with a fluid medium and burns to produce combustion exhaust gas;
A method for operating a circulating fluidized bed furnace comprising: collecting the fluidized medium from the combustion exhaust gas, discharging the combustion exhaust gas to a flue, and a cyclone for returning the fluid medium to the riser,
Supplying a first desulfurization material into the riser;
Comprising
The method of operating a circulating fluidized bed furnace, wherein the particle size of the first desulfurization material is a particle size that is discharged to the flue side by the cyclone. The operation method of the circulating fluidized bed furnace according to claim 7,
The method of operating a circulating fluidized bed furnace, wherein an average particle size of the first desulfurization material is smaller than a critical particle size of the cyclone. A method for operating a circulating fluidized bed furnace according to claim 7 or 8,
Furthermore,
Supplying a second desulfurization material into the riser;
Comprising
The method of operating a circulating fluidized bed furnace, wherein the particle size of the second desulfurization material is a particle size that is collected by the cyclone. A method for operating a circulating fluidized bed furnace according to claim 9,
The circulating fluidized bed furnace operating method, wherein an average particle size of the second desulfurization material is larger than a critical particle size of the cyclone. A method for operating a circulating fluidized bed furnace according to claim 9 or 10,
The operation method of a circulating fluidized bed furnace, wherein the first desulfurization material and the second desulfurization material each contain a Ca compound. An operation method for a circulating fluidized bed furnace according to claim 11,
The method of operating a circulating fluidized bed furnace, wherein the Ca compound is limestone (CaCO ₃ ). A method for operating a circulating fluidized bed furnace according to any one of claims 9 to 12,
Furthermore,
Measuring the differential pressure at the top and bottom of the riser;
Controlling the input amount of the second desulfurization material to the riser so that the differential pressure is constant;
A circulating fluidized bed furnace operating method characterized by comprising: An operation method for a circulating fluidized bed furnace according to claim 13,
Furthermore,
A step of pulling out the fluid medium based on the measurement result by the differential pressure measuring mechanism;
A circulating fluidized bed furnace operating method characterized by comprising: The operation method of the circulating fluidized bed furnace according to claim 13 or 14,
The step of controlling the input amount includes the step of controlling the input amounts of the first desulfurization material and the second desulfurization material so that the Ca / (S + Cl) equivalent ratio at the furnace inlet is 3.5 or more. A method for operating a circulating fluidized bed furnace. A method for operating a circulating fluidized bed furnace according to any one of claims 9 to 15,
Furthermore,
Measuring NOx concentration in the combustion exhaust gas;
Controlling the ease of combustion of the waste in the riser based on the NOx concentration in the combustion exhaust gas;
A circulating fluidized bed furnace operating method characterized by comprising: A method for operating a circulating fluidized bed furnace according to claim 16,
Furthermore,
Supplying combustion air as primary air into a fluidized bed obtained by fluidizing the fluid medium filled in the riser;
Supplying combustion air as secondary air into a freeboard formed above the fluidized bed in the riser;
Comprising
The step of controlling the ease of combustion controls the supply ratio of the primary air and the secondary air, wherein the circulating fluidized bed furnace is operated. A riser that mixes waste with a fluid medium and burns to produce combustion exhaust gas;
A cyclone that collects the fluid medium from the combustion exhaust gas, discharges the combustion exhaust gas to a flue, and returns the fluid medium to the riser;
A first desulfurization material supply mechanism for supplying a first desulfurization material into the riser;
Comprising
The circulating fluidized bed furnace according to claim 1, wherein the particle size of the first desulfurization material is a particle size that is discharged to the flue side by the cyclone. A circulating fluidized bed furnace according to claim 18,
The circulating fluidized bed furnace characterized in that an average particle size of the first desulfurization material is smaller than a critical particle size of the cyclone. A circulating fluidized bed furnace according to claim 18 or 19,
Furthermore,
A second desulfurization material supply mechanism for supplying a second desulfurization material into the riser;
Comprising
The circulating fluidized bed furnace characterized in that the particle size of the second desulfurization material is a particle size that is collected by the cyclone. A circulating fluidized bed furnace according to claim 20,
The circulating fluidized bed furnace characterized in that an average particle size of the second desulfurization material is larger than a critical particle size of the cyclone. A circulating fluidized bed furnace according to claim 20 or 21,
Each of the first desulfurization material and the second desulfurization material contains a Ca compound, and the circulation type fluidized bed furnace. A circulating fluidized bed furnace according to any one of claims 20 to 22,
Furthermore,
A differential pressure measuring mechanism for measuring the differential pressure at the upper and lower portions of the riser;
Comprising
The circulating fluidized bed furnace characterized in that the second desulfurization material supply mechanism controls the amount of the second desulfurization material input to the riser so that the differential pressure becomes constant. A circulating fluidized bed furnace according to claim 23,
Furthermore,
Based on the measurement result by the differential pressure measurement mechanism, a fluid medium extraction mechanism for extracting the fluid medium,
A circulating fluidized bed furnace characterized by comprising: A circulating fluidized bed furnace according to claim 23 or 24,
The first desulfurization material supply mechanism and the second desulfurization material supply mechanism are configured so that the Ca / (S + Cl) equivalent ratio at the furnace inlet is 3.5 or more. A circulating fluidized bed furnace characterized by controlling the input amount. A circulating fluidized bed furnace according to any one of claims 18 to 25,
Furthermore,
A concentration measuring mechanism for measuring NOx concentration in the combustion exhaust gas;
A combustion control mechanism for controlling the ease of combustion of the waste in the riser based on the NOx concentration in the combustion exhaust gas;
A circulating fluidized bed furnace characterized by comprising: A circulating fluidized bed furnace according to claim 26,
Furthermore,
The combustion control mechanism is
In a fluidized bed obtained by fluidizing the fluidized medium filled in the riser, combustion air is supplied as primary air, and in a free board formed above the fluidized bed in the riser, Circulating flow characterized by controlling combustion easiness of the waste by supplying combustion air as secondary air and controlling a supply ratio of the primary air and the secondary air Laminar furnace. A circulating fluidized bed furnace according to any one of claims 18 to 27,
The circulating fluidized bed furnace wherein the first desulfurization material supply mechanism and the second desulfurization material supply mechanism supply desulfurization materials from separate inlets. A circulating fluidized bed furnace according to any one of claims 18 to 27,
The circulating fluidized bed furnace wherein the first desulfurization material supply mechanism and the second desulfurization material supply mechanism supply the desulfurization material from a common inlet.

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