TWI391610B - A circulating fluidized bed, an operating system having the circulating fluidized bed, and a driving method of the circulating fluidized bed - Google Patents

Description

Circulating fluidized bed furnace, treatment system with circulating fluidized bed furnace, and operation method of circulating fluidized bed furnace

The present invention relates to a circulating fluidized bed furnace for incinerating waste water such as sewage sludge, municipal waste, industrial waste, and the like, and a system including the circulating fluidized bed furnace, in particular, the desulfurization material is put into the furnace. A circulating fluidized bed furnace for performing a desulfurization reaction and a desalination reaction, and a system including the circulating fluidized bed furnace.

Conventionally, circulating fluidized bed furnaces have been widely used in the combustion treatment of wastes such as sewage sludge, municipal waste, and industrial waste. The circulating fluidized bed furnace is characterized in that it is burned and scattered by mixing the waste with the flowing medium by the primary air introduced from the bottom of the riser, and the scattered flow medium is accompanied by the introduction of the secondary air. The freeboard completely burns the unburned components in the exhaust gas, separates the flowing medium from the combustion exhaust gas by the cyclone, and returns it to the riser to recycle the flowing medium. Such a circulating fluidized bed furnace is capable of instantaneously drying and incinerating waste, whereby the flow medium can be maintained at a high temperature for continuous combustion. Moreover, since the heat capacity of the fluid medium is very large, the heat generation at the time of stopping is small, and it is also suitable for intermittent operation, and since the fluid medium has a large thermal conductivity, it is also ideally used for sewage sludge having a high water content. The treated object.

In the case where the sulfur-containing component is present in the above-mentioned waste, when the combustion treatment is performed in a circulating fluidized bed furnace, sulfur oxide (SOx) such as SO ₂ may be generated. The exhaust gas containing sulfur oxides causes air pollution and acid rain, and is also harmful to the human body. Therefore, in order to remove it, desulfurization treatment is required.

Among the desulfurization methods, there are a wet method, a semi-dry method, and a dry method, and the most commonly used method in the past is a smoking tower (air scrubber) which is one of the wet methods. In the scrubber, the washing water to which the alkaline agent is added is dispersed in the combustion exhaust gas, and the acid gas including SOx is neutralized and treated. However, most of the scrubbers use caustic soda (NaOH) as an alkali agent, which is not only costly but also costly to maintain. Further, the scrubber is limited to a place where the water can be sufficiently secured and the waste water treatment cost is not used. Further, since the concentration of SOx in the exhaust gas is high up to the scrubber, when the flue is below the dew point, there is a problem that corrosion is likely to occur and corrosion occurs.

Further, one of the dry methods has a desulfurization method in the furnace in which a desulfurization material is directly injected into the furnace. The in-furnace desulfurization method is widely used as a simple method because the equipment is simply modified and does not require the use of water or the like. As the desulfurization material, most of them are limestone (CaCO ₃ ), hydrated lime (Ca(OH) ₂ ), dolomite (CaCO ₃ ‧MgCO ₃ ), and the like which are Ca-based solid desulfurization materials. In a general in-furnace desulfurization, a desulfurization material having a particle diameter substantially the same as that of a flow medium is used, and a desulfurization material introduced into the furnace is circulated together with a flow medium to secure a residence time and to obtain a desulfurization efficiency. Upgrade.

A circulating fluidized bed furnace which performs such in-furnace desulfurization is disclosed in Patent Document 1 (JP-A-2002-130637).

In addition, in the patent document 2 (Japanese Patent No. 3,940,431), it is disclosed that a desulfurization material is introduced into the furnace so as to have a 2Ca/S equivalent ratio or more, thereby performing desulfurization in the furnace.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-130637

[Patent Document 2] Japanese Patent No. 3790431

However, in the case where the conventional chlorine in the furnace is used for desulfurization of the chlorine-containing waste, a part of the desulfurization material may cause a desalination reaction, but the exhaust gas or the ash in the fly ash cannot be sufficiently removed. Therefore, in order to carry out desalination, it is necessary to blow slaked lime into the flue, but the chemical requires two types of limestone and slaked lime, which causes a problem of high cost and complicated handling.

Further, when the desulfurization material and the flow medium are recycled, the desulfurization material gradually increases, and the circulating particles in the furnace increase to cause the pressure in the furnace to rise. Therefore, it is necessary to frequently extract the flow medium, and it is necessary to increase the blower capacity to supply the air for circulating the increased circulating particles.

Therefore, the present invention has been developed in view of the above problems of the prior art, and an object of the invention is to provide desulfurization and sufficient desalination efficiency by desulfurization in a furnace, and to perform desulfurization simply and at low cost. A circulating fluidized bed furnace with desalination and a treatment system equipped with the circulating fluidized bed furnace.

Therefore, in order to solve the problem, the present invention provides a circulating fluidized bed furnace in which a waste containing a chlorine component is mixed with a flow medium and burned, and a circulating medium is separated and collected from the combustion exhaust gas by a cyclone. A circulating fluidized bed furnace in which a desulfurization material composed of a powder of a Ca compound is introduced and desulfurized in a furnace is characterized in that the maximum particle diameter of the desulfurization material is 100 μm or less, and the cyclone has Before capture The flow medium, on the one hand, the particle separation performance of the desulfurization material discharged together with the combustion exhaust gas, and the desulfurization material discharged from the flue gas is desulfurized by the desulfurization material discharged together with the exhaust gas; Desalting.

According to the present invention, by discharging the desulfurization material along with the combustion exhaust gas to the flue, the desalination reaction can be promoted in the flue, and the desalination efficiency can be improved.

Further, since the particle diameter of the desulfurization material is a small particle diameter of 100 μm or less, the reaction area is increased, and the reaction efficiency in the furnace for desulfurization and desalination is improved. Further, by promoting desalination, generation of dioxin and ammonium chloride can be suppressed.

Further, since the amount of the desulfurized material remaining in the furnace is reduced, the pressure in the furnace can be maintained at a low pressure. As a result, the number of times the flow medium is discharged from the bottom of the furnace can be reduced, and the capacity of the blower can be reduced. Moreover, since the particle diameter to be circulated becomes small, the wear of the refractory material in the furnace can be reduced. Moreover, since the desulfurization material having a large particle diameter and a large desulfurization material is inexpensive, it is possible to reduce the cost.

Further, in one of the features of the present invention, the cyclone has particle separation performance of particles having a particle diameter of 150 μm or more.

In general, since the particle diameter of the fluid medium is about 200 μm, it can be surely collected by the cyclone, and only the desulfurization material of 100 μm or less can be discharged together with the combustion exhaust gas.

Further, it is preferable that the amount of the desulfurization material to be supplied is an input amount of Ca/(S+Cl) equivalent ratio of the inlet of the furnace of 3.5 or more.

By setting the Ca/(S+Cl) equivalent ratio of the amount of the desulfurization material to the inlet of the furnace to 3.5 or more, the unreacted Ca component and HCl discharged from the cyclone can be sufficiently obtained. The reaction gives a high degree of desalting efficiency.

Further, it is preferable that the desulfurization material is mixed with the waste and then introduced into the furnace.

Thereby, even if it is a desulfurization material of a small particle size, the desulfurization material can be reliably supplied to the lower part of a furnace, and sufficient retention time can be acquired, and the desulfurization efficiency and the desalination efficiency can be improved. In addition, the reaction of the lower part of the most powerful furnace also contributes to the improvement of desulfurization efficiency.

Further, a treatment system comprising the above-described circulating fluidized bed furnace; and an exhaust gas treatment device disposed on a flue extending from a cyclone of the circulating fluidized bed furnace, the exhaust gas treatment device having at least A processing system for collecting a dust removing device for burning fly ash in exhaust gas, characterized in that the dust removing device is a filter type dust removing device including a bag filter or a ceramic filter.

Thereby, the desalination reaction can be more efficiently caused by capturing the small-sized desulfurization material by the filter type dust removing device. Further, it is more preferable to manage the differential pressure of the filter type dust removing device, and to maintain the thickness of the cake layer deposited on the filter, whereby the desalting reaction can be further promoted by the desulfurized material held in the cake layer.

The operation method of the circulating fluidized bed furnace of the present invention comprises a riser pipe that mixes and burns waste with a flowing medium to generate exhaust gas for combustion; and collects the flow medium from the exhaust gas of the combustion exhaust gas to exhaust the exhaust gas A method of operating a circulating fluidized bed furnace that is discharged to a flue and returns the aforementioned flow medium to the cyclone of the aforementioned riser. This operation method includes a process of supplying the first desulfurization material into the above-mentioned 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 the invention, the first desulfurizing material is discharged to the flue side by the cyclone together with the exhaust gas. Thereby, the combustion exhaust gas can be desalted by the first desulfurization material on the flue side.

The circulating fluidized bed furnace of the present invention comprises: a riser pipe that mixes and burns waste with a flow medium to generate exhaust gas; and collects the flow medium from the combustion exhaust gas to exhaust the exhaust gas a cyclone that is discharged to the flue and returns the flow medium to the riser; and a first desulfurization material supply mechanism that supplies the first desulfurization material to the inside of the riser. 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 be discharged to the flue along with the combustion exhaust gas, the desalination reaction can be promoted in the flue, and the desalination efficiency can be improved. Further, since the particle diameter of the desulfurization material is a small particle diameter of 100 μm or less, the reaction area can be increased, and the reaction efficiency in the furnace for desulfurization and desalination can be improved.

Further, since the amount of the desulfurization material remaining in the furnace is reduced, the pressure in the furnace can be kept at a low pressure, and the number of times of discharging the medium from the bottom of the furnace can be reduced, and the capacity of the blower can be reduced. Further, since the desulfurization material having a large particle diameter and a large desulfurization material is inexpensive, it is possible to reduce the cost.

In addition, the cyclone has the particle separation performance of the particles having a particle diameter of 150 μm or more, so that the flow medium can be surely collected, and only the desulfurization material of 100 μm or less is discharged together with the combustion exhaust gas.

In addition, by setting the amount of the desulfurization material to be an input amount of Ca/(S+Cl) equivalent ratio of 3.5 or more, it is possible to prevent the discharge from the cyclone. The Ca component is sufficiently reacted with HCl to obtain a high degree of desalting efficiency.

Further, by mixing the desulfurization material with the waste and then putting it into the furnace, even if it is a small-sized desulfurization material, the desulfurization material can be reliably supplied to the lower portion of the furnace, and a sufficient residence time can be obtained. .

Further, by using the dust removing device of the exhaust gas treating apparatus as a filter type, the filter type dust removing device can capture the small-sized desulfurized material, and the desalination reaction can be more efficiently caused.

(First embodiment)

Hereinafter, a preferred embodiment 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 the embodiments are not intended to limit the scope of the invention to the description, and are merely illustrative examples.

The treatment target of the circulating fluidized bed furnace of the present embodiment is chlorine-containing waste, and examples thereof include sewage sludge, municipal waste, industrial waste, and the like, but the circulating fluidized bed furnace of the present embodiment is particularly Ideally used in the treatment of sewage sludge. In the circulating fluidized bed furnace, these wastes are subjected to combustion treatment, and desulfurization in the furnace is carried out by the input of the desulfurization material, thereby performing desulfurization and desalination.

Referring to Fig. 1, a circulating fluidized bed furnace and a treatment system according to the present embodiment will be described. In the same figure, the main structure of the circulating fluidized bed furnace 1 is constituted by a fluidized bed 2a obtained by fluidizing a flowing medium such as ceramsite filled in a furnace bottom, and a freeboard 2b located above it. Upflow tube 2; Connected to the upper portion of the riser tube 2, traps the flow medium blown from the freeboard 2b, and discharges the exhaust gas from which the flow medium is separated to the cyclone 3 of the flue 21; and connects to the cyclone via the downflow tube 4. The sealed tank 5 for preventing the unburned gas in the furnace from flowing toward the cyclone 3; and the flowing medium returning pipe 6 for returning the flowing medium stored in the sealed can 5 to the riser 2.

A primary air introduction port 11 is provided at the bottom of the riser pipe 2, and the flow medium is fluidized by the primary air introduced from the primary air introduction port 11, thereby forming the fluidized bed 2a. A secondary air introduction port (not shown) is provided in the riser wall above the fluidized bed 2a, and the secondary air introduced from the introduction maintains the tube speed of the freeboard 2b and causes the combustion row The unburned components in the exhaust gas are burned.

Above the fluidized bed 2a of the above-mentioned riser pipe 2, a waste input means 12 is provided. The waste injecting means 12 is provided with a structure in which the waste which is taken from the waste into the hopper is supplied to the furnace in an appropriate amount by the supply feeder.

Further, the circulating fluidized bed furnace 1 is provided with a desulfurization material input port 13 for introducing a desulfurization material into the furnace, and a flow medium input port (not shown) for introducing a flow medium. The desulfurization material inlet 13 and the fluid medium inlet may be provided at any position in the circulation system of the fluid medium. However, the desulfurization material inlet 13 is preferably provided in the secondary air of the riser tube 2. The lower side of the inlet is located.

The desulfurization material introduced into the furnace from the desulfurization material inlet 13 is a desulfurization material composed of a powder of a Ca compound. Further, the desulfurized material is used as a desulfurized material having a maximum particle diameter of 100 μm or less. Examples of the desulfurization material include limestone (CaCO ₃ ), hydrated lime (Ca(OH) ₂ ), and dolomite (CaCO ₃ -MgCO ₃ ).

The cyclone 3 has a particle separation performance in which the flow medium is separated from the combustion exhaust gas and the flow medium is collected, and the desulfurization material is discharged to the flue 21 together with the exhaust gas. It is preferable that the cyclone 3 is a particle separation performance of particles having a particle diameter of 150 μm or more.

An exhaust gas treatment device 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 apparatus described above has a structure in which an air preheater 22, a waste heat boiler 23, a gas cooling tower 24, and a bag filter 25 are disposed in series.

The air preheater 22 performs heat exchange between the air introduced by the press-in fan 15 and the combustion exhaust gas from the cyclone 3 to perform preheating of primary air or secondary air. The waste heat boiler 23 generates steam by heating exhaust gas and heating the feed water. The gas cooling tower 24 is cooled by heat exchange with cooling water to cool the exhaust gas. The bag-shaped filter 25 is a device that collects and removes fly ash in the exhaust gas that has been cooled. The combustion exhaust gas is discharged from the stack 27 to the outside of the system by the induction fan 26 provided in the rear stage of the bag filter 25 through the above-described exhaust gas treatment device.

Further, the exhaust gas treatment device is not limited to the above-described structure, and may be configured by a suitable and necessary device. As another configuration example, as shown in FIG. 2, the air preheater 22, the waste heat boiler 23, and the ceramic filter 28 are arranged in series. Thus, the exhaust gas treatment suitable for the present embodiment The apparatus may have any structure if it has at least a structure including a dust removing device (a bag filter 25 or a ceramic filter 28).

In the circulating fluidized bed furnace having the above configuration, the waste introduced into the furnace by the waste charging means 12 is mixed with the fluid medium in the fluidized bed 2a and burned, and the unburned components are completely burned on the freeboard 2b, and Desulfurization in the furnace is performed by using the desulfurization material supplied from the desulfurization material inlet 13 . Desulfurization in the furnace mainly removes Sox by a desulfurization reaction represented by the following reaction formula (1).

SO ₂ +CaO+1/2O ₂ →CaSO ₄ ...(1)

Further, CaO is a desulfurized material such as limestone or slaked lime which is generated by heat in the furnace.

Further, in the furnace, a part of HCl was removed by a desalting reaction represented by the following reaction formula (2) as a desulfurized 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 the present embodiment, the maximum particle diameter of the desulfurization material charged into the furnace is set to 100 μm or less, and the cyclone 3 has a trapping flow medium, and on the other hand, the desulfurization material is separated from the particles discharged from the combustion exhaust gas. Performance, therefore, in the combustion exhaust gas that is separated from the flow medium by the cyclone 3 With the unreacted desulfurized material, it is discharged to the flue 21 together.

Then, desalination is carried out in the flue 21 by the discharged desulfurized material. Of course, desulfurization is also carried out. Desalting, especially when the temperature is lowered, increases the reaction efficiency, so almost all of the HCl is removed as it passes through the flue 21.

According to the present embodiment, by discharging the desulfurization material along with the combustion exhaust gas to the flue 21, the desalination reaction can be promoted in the flue, and the desalination efficiency can be improved.

Further, since the particle diameter of the desulfurization material is a small particle diameter of 100 μm or less, the reaction area is increased, and the reaction efficiency in the furnace for desulfurization and desalination can be improved. Further, the desalination is promoted, and the generation of dioxin and ammonium chloride can be suppressed.

Further, since the amount of the desulfurization material remaining in the furnace is reduced, the pressure in the furnace can be maintained at a low pressure. As a result, the number of discharges of the flow medium from the bottom of the furnace can be reduced, and the capacity of the blower (pressing fan 15) can be reduced. Moreover, since the particle size of the circulation becomes small, the wear of the refractory material in the furnace can be reduced. Further, since the desulfurization material having a large particle diameter and a large diameter is inexpensive, it is possible to reduce the cost.

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

Moreover, it is preferable that the amount of the desulfurization material to be supplied is an input amount of a Ca/(S+Cl) equivalent ratio of the inlet of the furnace of 3.5 or more.

Figure 3 shows the desulfurization rate and desalination rate of the desulfurization input. Such a picture As shown in the table, the desulfurization rate shows a relatively high value even if the Ca/(S+Cl) equivalent ratio is small.

In addition, the salt rejection rate is a sharp increase in the Ca/(S+Cl) equivalent ratio of 3.5.

Therefore, by setting the amount of the desulfurization material to be an input amount of Ca/(S+Cl) equivalent ratio in the furnace of 3.5 or more, the unreacted Ca component and HCl discharged from the cyclone can be sufficiently obtained. The reaction gives a high degree of desalting efficiency.

Further, in the present embodiment, the dust removing device of the exhaust gas treating apparatus is preferably formed as a filter type dust removing device including a bag filter or a ceramic filter, whereby the small particle diameter is captured by the filter type dust removing device. The desulfurization material can cause the desalination reaction more efficiently. Further, it is desirable to manage the differential pressure of the filter type dust removing device, and to maintain the thickness of the cake layer deposited on the filter to be thick, and to further promote the desalination reaction by the desulfurized material held in the cake layer.

Further, as shown in Fig. 2, it is preferred that the desulfurization material is mixed with the waste in advance and is introduced into the furnace by the waste input means 12.

Thereby, even if it is a desulfurization material of a small particle diameter, the desulfurization material can be reliably supplied to the lower part of a furnace, and sufficient retention time can be acquired, and the desulfurization efficiency and the desalination efficiency can be improved. In addition, the reaction of the reaction in the lower part of the most intense furnace also contributes to the improvement of desulfurization efficiency.

In the present embodiment, the cyclone 3 has a particle separation performance of particles having a particle diameter of 150 μm or more, and the maximum particle diameter of the desulfurization material is 100 μm or less. However, if the average particle diameter of the desulfurized material is made smaller than the boundary particle diameter of the cyclone 3, the phase can be achieved. The same effect. For example, when the boundary particle diameter of the cyclone 3 is 150 μm, a desulfurization material can be used in which the average particle diameter is smaller than 150 μm. Even in such a case, since most of the desulfurized material is discharged to the flue, HCl can be effectively removed.

In addition, the maximum particle diameter system referred to in the present specification can be obtained by a weight cumulative distribution obtained by "JIS M 8511; Industrial Analysis and Experimental Method of Natural Graphite" according to Japanese Industrial Standards (JIS Standard).

In addition, the average particle diameter system referred to in the present specification can be calculated from the weight distribution of the above-mentioned "JIS M 8511; industrial analysis and experimental method of natural graphite", and the cumulative weight is calculated as a medium diameter of 50% (medium number) d ₅₀ ) to find out.

Further, the boundary particle diameter of the cyclone 3 referred to in the present specification can be obtained in the following manner. That is, the desulfurized material having a sufficiently wide particle diameter distribution is introduced into the cyclone 3. The desulfurization material discharged from the cyclone 3 is collected as a discharge desulfurization material. Then, the minimum particle diameter of the discharged desulfurization material is obtained as the boundary particle diameter of the cyclone 3.

(Second embodiment)

Next, a second embodiment of the present invention will be described.

According to the first embodiment, the desalination effect can be improved by using the deuterium having a smaller average particle diameter than the boundary particle diameter of the cyclone 3 as the desulfurization material. Further, the waste which is put into the circulating fluidized bed furnace may contain a nitrogen compound. In the case where the waste contains nitrogen compounds, nitrogen compounds (NH ₃ , HCN, N ₂ O, etc.) may also be contained in the exhaust gas in the furnace. For example, when the sewage sludge is discharged as waste, the content of the nitrogen compound tends to increase. Then, the present inventors have found that the nitrogen compound (NH) contained in the exhaust gas is used only when the desulfurization material having a smaller average particle diameter than the boundary particle diameter of the cyclone 3 (hereinafter referred to as the first desulfurization material) is used. _3. The concentration of HCN, N ₂ O, etc. will increase.

Fig. 4 is a graph showing the behavior of exhaust gas from combustion. 4 shows the results when only the first desulfurization material is used as the desulfurization material, and the case where only the average particle diameter is larger than the boundary particle diameter of the cyclone 3 (hereinafter referred to as the second desulfurization material) is used as the desulfurization. The result of the material. In Fig. 4, a shows CO, shows SO ₂ , c shows NOx, d shows HCl, e shows HCN, and f shows NH ₃ . As shown in FIG. 4, it was confirmed that when only the first desulfurization material was used, when the second desulfurization material was used, the HCN concentration and the concentration of NH ₃ were increased although the HCl concentration could be reduced.

As a reason for the increase in the nitrogen compound, the following structure can be considered.

Fig. 5 is a schematic view for explaining the action of a desulfurization material in a system including a circulating fluidized bed furnace. Fig. 5 is a view showing a case where calcium carbonate (CaCO ₃ ) is used as a desulfurization material. As shown in Fig. 5, generally, the furnace (riser tube) has a high temperature (for example, about 850 ° C). CaCO ₃ that is put into the furnace is oxidized at a high temperature to generate CaO. The CaO produced causes the desulfurization reaction of the desulfurized material to cause the change of Sox to CaSO ₄ . Also, at the lower temperature (e.g., about 200 ° C) flue side, CaO will be desalted with HCl to produce CaCl ₂ .

The CaO present in the furnace is not only a desulfurization reaction, but also acts as a catalyst for the oxidation reaction of nitrogen compounds in a high temperature environment. That is, as shown in Fig. 5, nitrogen compounds such as NH ₃ , HCN, and N ₂ O are oxidized by the catalytic action of CaO to generate NOx. This reaction is caused in particular in the lower part of the riser tube which produces the thermal decomposition reaction of the sludge. This reason is as follows. The sludge that is put into the riser pipe will flow to the lower part of the riser pipe first because of the large specific gravity. In the primary air supplied to the lower portion of the riser, there is no oxygen in an amount sufficient to completely burn the sludge. Therefore, in the lower part of the riser pipe, a thermal decomposition reaction of the sludge occurs. As a result, nitrogen compounds such as NH ₃ , HCN, and N ₂ O are generated from the N component (containing a nitrogen component) in the sludge. As described above, since the concentration of the nitrogen compound is high in the lower portion of the riser, the oxidation reaction of the nitrogen compound due to CaO is likely to occur in the lower portion of the riser. Further, in the upper portion of the riser pipe, the concentration of the nitrogen compound is low due to the oxidation of the nitrogen compound of the secondary air. Therefore, the oxidation reaction of the nitrogen compound caused by CaO is not easily produced.

Here, as in the first embodiment, when only the first desulfurization material is used, the first desulfurization material that has been introduced into the riser pipe is blown upward with the gas in the furnace. Therefore, the first desulfurization material is less likely to remain in the lower portion of the riser pipe. Further, since the first desulfurization material is discharged from the cyclone, there is no possibility that the first desulfurization material is supplied to the lower portion of the riser pipe through the downflow pipe. Therefore, it becomes difficult to sufficiently exert the function of the nitrogen compound as an oxidation catalyst. As a result, the concentration of nitrogen compounds in the exhaust gas is increased.

Therefore, in the present embodiment, an operation for promoting the oxidation reaction of the nitrogen compound in the furnace is carried out.

Fig. 6 is a view showing the overall configuration of a system including the circulating fluidized bed furnace of the present embodiment. The same structure is given to the same as in the first embodiment Symbols and their descriptions are omitted.

As shown in Fig. 6, in the system of the present embodiment, a first desulfurization material supply mechanism 36, a second desulfurization material supply mechanism 37, a pressure sensor 31, a pressure sensor 32, and a differential pressure measuring mechanism are added. 33; concentration measuring mechanism 34, flow medium discharge mechanism 35; fan 38; and air preheater 39. Moreover, the first desulfurization material inlet 13-1 and the second desulfurization material inlet 13-2 as the desulfurization material inlet 13 are provided.

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

The second desulfurization material supply mechanism 37 supplies the second desulfurization material into the riser pipe 2 from the second desulfurization material supply port 13-2. The particle size of the second desulfurization material is different from that of the first desulfurization material, and is a particle size that can be trapped together with the flow medium in the cyclone 3. Specifically, a desulfurization material having a larger average particle diameter than the boundary particle diameter of the cyclone 3 is used as the second desulfurization material.

The differential pressure measuring mechanism 33 is provided to measure the differential pressure between the upper portion and the lower portion in the riser tube 2. A pressure sensor 31 is mounted on the upper portion of the riser tube, and a pressure sensor 32 is mounted on the lower portion of the riser tube. The differential pressure measuring mechanism 33 measures the differential pressure in the riser tube 2 based on the pressure measurement results of the pressure sensor 31 and the pressure sensor 32.

The concentration measuring mechanism 34 is provided in the flue 21 . The concentration of the NOx component in the exhaust gas of the combustion exhaust gas is measured by the concentration measuring means 34. Furthermore, the concentration measuring mechanism 34 does not necessarily need to be provided in the flue 21 . If it is a position where the concentration of the component in the exhaust gas of combustion can be measured, it can be installed in another place.

The fluid medium discharge mechanism 35 is provided at the bottom of the riser tube 2. The flow medium discharge mechanism 35 is provided to discharge the flow medium from the fluid layer 2a.

The fan 38 is connected to the flow layer 2a in the riser 2 via an air preheater 39. The fan 38 supplies the combustion air as secondary air and supplies it to the upper side of the fluid layer 2a.

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

Next, a method of operating the circulating fluidized bed furnace of the present embodiment will be described.

The waste that has been introduced into the riser pipe 2 by the waste input means 12 is mixed with the flow medium by the fluidized bed 2a and burned to generate combustion exhaust gas. Here, the first desulfurization material supply unit 36 and the second desulfurization material supply unit 37 supply the first desulfurization material and the second desulfurization material into the riser tube 2. The presence of the desulfurization material causes the combustion exhaust gas to be desulfurized. The combustion exhaust gas in the riser pipe 2 is guided to the cyclone 3 together with the first desulfurization material, the second desulfurization material, and the flow medium.

In the cyclone 3, only the second desulfurization material and the flow medium are collected and returned to the riser tube 2. Further, the first desulfurization material and the combustion exhaust gas are discharged from the cyclone 3 to the flue 21 . By the first desulfurization material discharged to the flue, as in the above-described embodiment, desalination of the combustion exhaust gas is performed, and HCl in the exhaust gas from the combustion passage passing through the flue 21 can be removed.

Here, when only the first desulfurization material is supplied, the desulfurization material does not circulate in the circulating fluidized bed furnace. Therefore, it becomes impossible to sufficiently maintain the concentration of the desulfurization material in the riser tube 2.

On the other hand, in the present embodiment, since the second desulfurization material is returned to the riser pipe 2, the concentration of the desulfurization material in the riser pipe 2 can be prevented from decreasing. As a result, it is possible to perform desalination in the flue 21, and also promote desulfurization in the riser tube 2 and oxidation of unburned components.

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

Further, the particle size of the second desulfurization material will be described. The cyclone 3 is configured to discharge particles of 150 μm or less and collect particles larger than 150 μm. That is, the boundary particle diameter of the cyclone 3 was 150 μm. In this case, it is preferable to use the second desulfurization material as the average particle diameter of 150 μm. Thereby, the concentration of the desulfurization material in the furnace, in particular, the lower portion of the riser pipe can be sufficiently maintained, and the oxidation reaction of the nitrogen compound can be sufficiently promoted. Further, the average particle diameter of the second desulfurization material is preferably 350 μm or less. When the average particle diameter exceeds 350 μm, the second desulfurization material may be deposited on the lower portion of the riser tube 2 and may not be blown up toward the upper portion. As a result, the desulfurization action, the oxidation catalyst action, and the like are not sufficiently exhibited. Also, the power required by the fan 15 is increased.

When the boundary particle diameter of the cyclone 3 is 150 μm, it is more preferable that the second desulfurization material has an average particle diameter of 150 μm or more. The particle diameter of the particles (50% or more by weight) is in the range of 100 μm or more and 350 μm or less. When a desulfurized material having a particle size distribution in such a range is used, there is no possibility that the second desulfurization material is accumulated in the furnace due to long-term operation, and the second desulfurization material cannot be blown up toward the upper portion.

As the type of the first desulfurization material and the second desulfurization material, the same type (limestone, slaked lime, and dolomite) as the desulfurization material of the above-described embodiment can be used.

The amount of the first desulfurization material and the second desulfurization material to be charged is preferably an input amount of a Ca/(S+Cl) equivalent ratio of the inlet of the furnace of 3.5 or more as in the above-described embodiment. Further, the amount of this input can be determined by measuring the component ratio of the waste in advance.

Further, in the present embodiment, the concentration of the NOx in the exhaust gas is measured by the concentration measuring means 34. Then, the operation of the combustion control means (fan 15 and fan 38) is controlled based on the measurement result of the concentration measuring means 34.

As described above, in the present embodiment, the oxidation of the unburned components in the riser tube 2 is promoted by the second desulfurization material. When the nitrogen compound (HCN, NH ₃ or the like) in the unburned component is 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 pipe 2 is controlled to be less likely to cause combustion (oxidation) by the combustion control mechanism (fan 15 and fan 38). . Specifically, the environment in which the oxidation reaction is less likely to occur is controlled by reducing the supply amount of the primary air and the secondary air or reducing the supply ratio of the primary air to the secondary air. Thereby, the increase in the NOx concentration can be suppressed, and the NOx concentration in the combustion exhaust gas can be suppressed.

In addition, when the NOx concentration is not sufficiently suppressed by the combustion control means, the second desulfurization material supply means 37 reduces the supply amount of the second desulfurization material. Thereby, the oxidation reaction in the riser pipe 2 can be surely suppressed, and the NOx concentration in the combustion exhaust gas can be reliably suppressed.

Further, in the present embodiment, when the operation is performed, the differential pressure between the upper portion and the lower portion of the riser tube 2 is measured by the differential pressure measuring means 33. As described above, the second desulfurization material is circulated in the circulating fluidized bed furnace. Therefore, by controlling the supply amount of the second desulfurization material, it is possible to control the differential pressure in the furnace. Therefore, based on the measurement result of the differential pressure measuring means 33, the second desulfurization material supply means 37 controls the supply amount of the second desulfurization material, and the differential pressure in the riser tube 2 is made constant.

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

Specifically, when the measurement result of the differential pressure is smaller than a predetermined value, the second desulfurization material supply mechanism 37 replenishes the second desulfurization material. In addition, when the differential pressure is larger than the predetermined value, the second desulfurization material supply mechanism 37 stops the supply of the second desulfurization material. Further, the second desulfurization material is discharged together with the flow medium from the fluidized bed 2a by the fluid medium discharge mechanism 35.

As described above, according to the present embodiment, by using the first desulfurization material and the second desulfurization material, not only the demineralization action can be promoted in the flue 21, but also the oxidation in the riser tube 2 can be promoted.

Further, when the NOx concentration is high, the concentration measuring means 34 and the combustion control means (fan 15 and fan 38) suppress the oxidation in the riser tube 2. Thereby, the NOx concentration can be suppressed.

Moreover, the amount of particles in the riser tube 2 can be kept constant by the differential pressure measuring means 33, the second desulfurizing means supply means 37, and the flow medium discharge means 35. Thereby, the temperature in the riser tube 2 can be equalized. Moreover, the desulfurization reaction can be promoted by promoting solid-gas contact.

In the present embodiment, the case where the first desulfurization material inlet 13-1 and the second desulfurization material inlet 13-2 are provided separately has been described. However, these input ports do not necessarily need to be separately provided, and the first desulfurization material and the second desulfurization material can be supplied from a common input port.

Further, similarly to the above-described embodiment, the first desulfurization material supply mechanism 36 and the second desulfurization material supply mechanism 37 may be configured to cause the first desulfurization material and the second desulfurization material by the waste input means 12. After being mixed with the waste, it is again put into the riser tube 2. Thereby, the desulfurization material can be surely supplied to the lower portion of the riser pipe 2, and the residence time of the desulfurization material in the riser pipe 2 can be increased. As a result, the desulfurization efficiency can be improved. Further, desulfurization is carried out in the lower portion of the most complicated riser pipe 2, and from this point of view, the desulfurization efficiency can be improved.

[Industry use possibility]

According to the present invention, desulfurization and sufficient desalination efficiency can be obtained by desulfurization in a furnace, and desulfurization and desalination can be carried out simply and at low cost, so that it can be suitably applied to sewage sludge and municipal waste. a circulating fluidized bed furnace that incinerates chlorine waste such as industrial waste, And the entire system with the bed furnace.

1‧‧‧Circulating Fluidized Bed Furnace

2a‧‧‧Mobile layer

2b‧‧‧ freeboard

2‧‧‧Rise tube

3‧‧‧Cyclone

4‧‧‧ downflow tube

5‧‧‧Sealed cans

6‧‧‧Mobile media return tube

11‧‧‧One air inlet

12‧‧‧ Waste input means

13‧‧‧Desulfurization input

13-1‧‧‧1st desulfurization input

13-2‧‧‧Second desulfurization input

15‧‧‧Filling fan

21‧‧‧ flue

22‧‧‧Air preheater

23‧‧‧Waste heat boiler

24‧‧‧ gas cooling tower

25‧‧‧Bag filter

26‧‧‧Induction fan

27‧‧‧ chimney

28‧‧‧Ceramic filter

31‧‧‧ Pressure Sensor

32‧‧‧ Pressure Sensor

33‧‧‧Differential pressure measuring mechanism

34‧‧‧Concentration measuring agency

35‧‧‧Mobile media discharge agency

36‧‧‧1st desulfurization material feeder

37‧‧‧Second desulfurization material feeder

38‧‧‧fan

39‧‧‧Air preheater

Fig. 1 is a view showing the overall configuration of a system including a circulating fluidized bed furnace according to an embodiment of the present invention.

Fig. 2 is a view showing the overall configuration of a system including a circulating fluidized bed furnace according to an application example of the embodiment of the present invention.

Fig. 3 is a graph showing the desulfurization rate and the desalination rate of the amount of desulfurization input.

Fig. 4 is a graph showing the behavior of exhaust gas from combustion.

Fig. 5 is a schematic view for explaining the action of the desulfurization material.

Fig. 6 is a view showing the overall configuration of a system including the circulating fluidized bed furnace of the second embodiment.

1‧‧‧Circulating Fluidized Bed Furnace

2a‧‧‧Mobile layer

2b‧‧‧ freeboard

2‧‧‧Rise tube

3‧‧‧Cyclone

4‧‧‧ downflow tube

5‧‧‧Sealed cans

6‧‧‧Mobile media return tube

11‧‧‧One air inlet

12‧‧‧ Waste input means

13‧‧‧Desulfurization input

15‧‧‧Filling fan

21‧‧‧ flue

22‧‧‧Air preheater

23‧‧‧Waste heat boiler

24‧‧‧ gas cooling tower

25‧‧‧Bag filter

26‧‧‧Induction fan

27‧‧‧ chimney

Claims (27)

A circulating fluidized bed furnace is characterized in that a waste containing a chlorine component is mixed with a flowing medium and then burned, and a flow medium is separated and collected from the combustion exhaust gas by a cyclone, and recycled, and a powder of a Ca compound is introduced. The desulfurization material composed of the body is a circulating fluidized bed furnace for desulfurization in a furnace, characterized in that the maximum particle diameter of the desulfurization material is 100 μm or less, and the amount of the desulfurization material is used as an inlet of the furnace. The Ca/(S+Cl) equivalent ratio is an input amount of 3.5 or more, and the cyclone has a particle separation property for collecting the desulfurization material accompanied by the combustion exhaust gas, and the exhaust gas is accompanied by the exhaust gas. The discharged desulfurized material is subjected to desulfurization and desalination on a flue extending from the cyclone. The circulating fluidized bed furnace according to claim 1, wherein the cyclone has particle separation performance of particles having a particle diameter of 150 μm or more. The circulating fluidized bed furnace according to claim 1, wherein the desulfurized material is mixed with the waste and then introduced into the furnace. The circulating fluidized bed furnace according to claim 1, wherein the desulfurization material is a powder of limestone (CaCO ₃ ). A processing system having a circulating fluidized bed furnace, comprising a circulating fluidized bed furnace as described in claim 1 of the patent application scope, and An exhaust gas treatment device disposed on a flue disposed along a cyclone of the circulating fluidized bed furnace, the exhaust gas treatment device having a treatment system for at least a dust removal device for trapping fly ash in the exhaust gas of the combustion exhaust, The utility model is characterized in that the dust removing device is a filter type dust removing device comprising a bag filter or a ceramic filter. A circulating fluidized bed furnace operating method comprising: a riser pipe for mixing waste and a flowing medium to generate combustion exhaust gas; and collecting the foregoing flow medium from the combustion exhaust gas to exhaust the exhaust gas A method of operating a circulating fluidized bed furnace that is discharged to a flue and returns the flow medium to a cyclone of the riser, and is characterized in that it is provided with a process of supplying a first desulfurization material into the riser The particle diameter of the first desulfurization material is a particle diameter that can be discharged toward the flue side by the cyclone, and further includes a process of measuring a differential pressure between an upper portion and a lower portion of the riser tube; and controlling the foregoing The amount of the second desulfurization material applied to the riser tube causes the differential pressure to be a constant process. The method of operating a circulating fluidized bed furnace according to claim 6, wherein the average particle diameter of the first desulfurization material is smaller than a boundary particle diameter of the cyclone. The method for operating a circulating fluidized bed furnace according to item 6 of the patent application, wherein Further, a process for supplying the second desulfurization material to the inside of the riser pipe, wherein the particle diameter of the second desulfurization material is a particle diameter that can be collected by the cyclone. The method of operating a circulating fluidized bed furnace according to claim 8, wherein the second particle diameter of the second desulfurization material is larger than a boundary particle diameter of the cyclone. The method for operating a circulating fluidized bed furnace according to the eighth aspect of the invention, wherein the first desulfurization material and the second desulfurization material each contain a Ca compound. The method for operating a circulating fluidized bed furnace according to claim 10, wherein the Ca compound is limestone (CaCO ₃ ). The method for operating a circulating fluidized bed furnace according to claim 6, further comprising a process of discharging the fluid medium in accordance with a measurement result of the differential pressure measuring means. The method for operating a circulating fluidized bed furnace according to the sixth aspect of the invention, wherein the process of controlling the input amount includes controlling an input amount of the first desulfurization material and the second desulfurization material to cause a furnace The Ca/(S+Cl) equivalent ratio at the inlet is 3.5 or more. For example, the circulation type fluidized bed furnace of the patent application scope 8 Further, the method further includes: a process of measuring a concentration of NOx in the exhaust gas of the combustion exhaust; and a process of controlling a degree of combustion of the waste in the riser pipe in accordance with a concentration of NOx in the exhaust gas of the combustion exhaust. The method of operating a circulating fluidized bed furnace according to claim 14, further comprising: supplying the fluidized layer obtained by fluidizing the flow medium filled in the riser tube, and supplying the mixture as a combustion a process for controlling the primary air of the air; and a process of supplying the secondary air as the combustion air in the freeboard above the fluidized bed formed in the riser pipe, and controlling the ease of combustion is controlled once The ratio of the supply of air to the aforementioned secondary air. A circulating fluidized bed furnace characterized by comprising: mixing and burning waste with a flowing medium to generate a riser pipe for burning exhaust gas; collecting the above-mentioned flowing medium from the combustion exhaust gas, and exhausting the exhaust gas a cyclone that is discharged to the flue and returns the flow medium to the riser; and a first desulfurization material supply mechanism that supplies the first desulfurization material to the inside of the riser, the particles of the first desulfurization material The diameter system is forwardable by the aforementioned cyclone The particle diameter discharged from the flue side. The circulating fluidized bed furnace according to claim 16, wherein the first particle diameter of the first desulfurization material is smaller than a boundary particle diameter of the cyclone. The circulating fluidized bed furnace according to claim 16, further comprising: a second desulfurization material supply mechanism that supplies the second desulfurization material to the riser, and a particle diameter of the second desulfurization material It is a particle diameter that can be trapped by the aforementioned cyclone. The circulating fluidized bed furnace according to claim 18, wherein the second particle diameter of the second desulfurization material is larger than a boundary particle diameter of the cyclone. The circulating fluidized bed furnace according to claim 18, wherein the first desulfurization material and the second desulfurization material each contain a Ca compound. The circulating fluidized bed furnace according to claim 18, further comprising: a differential pressure measuring mechanism that measures a differential pressure between an upper portion and a lower portion of the riser tube, wherein the second desulfurizing material supply mechanism controls the first 2 desulfurization materials face forward The input amount of the riser pipe is such that the differential pressure is constant. The circulating fluidized bed furnace according to claim 21, further comprising a flow medium discharge mechanism that discharges the flow medium according to a measurement result of the differential pressure measuring means. The circulating fluidized bed furnace according to claim 21, wherein the first desulfurization material supply means and the second desulfurization material supply means control the first desulfurization material and the second desulfurization material The amount of input is such that the Ca/(S+Cl) equivalent ratio at the inlet of the furnace is 3.5 or more. The circulating fluidized bed furnace according to claim 16, further comprising: a concentration measuring mechanism for measuring a concentration of NOx in the exhaust gas of the combustion exhaust; and controlling the upward flow according to a concentration of NOx in the exhaust gas of the combustion exhaust gas A combustion control mechanism for the ease of combustion of the aforementioned waste in the pipe. The circulating fluidized bed furnace according to claim 24, wherein the combustion control mechanism supplies the combustion air to the fluidized layer obtained by fluidizing the flow medium filled in the riser pipe. The primary air is supplied to the free air above the fluidized bed formed in the riser pipe, and the secondary air as the combustion air is supplied, by controlling the supply ratio of the primary air to the secondary air. Control the aforementioned The ease of burning of waste. The circulating fluidized bed furnace according to claim 16, wherein the first desulfurization material supply means and the second desulfurization material supply means supply the desulfurization material from the individual input ports. The circulating fluidized bed furnace according to claim 16, wherein the first desulfurization material supply means and the second desulfurization material supply means supply the desulfurization material from a common input port.