JP3396376B2 - Waste-fired circulating fluidized bed combustion furnace - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is based on the problem that combustion ash generated by combustion in a combustor is difficult to form a high-speed fluidized bed required for combustion in a combustor. , Waste fuel that becomes fine particles containing a large amount of small particles, especially chicken dung,
The present invention relates to a waste-fired circulating fluidized-bed combustion furnace for livestock waste fuel such as pork pork. 2. Description of the Related Art FIG. 3 shows a chicken-firing circulating fluidized-bed combustion furnace as a conventional waste-fired circulating fluidized-bed combustion furnace. As shown in the figure, this chicken-firing circulating fluidized-bed combustion furnace is composed of a main part including a combustor 01, a cyclone 02, a fluidized-bed heat exchanger 03, and a stand pipe 04. In the combustor 01 and the fluidized bed heat exchanger 03, combustion air is blown by blowers 05a, 05b,
It is characterized in that a fluidized state called a high-speed fluidized bed is formed by being supplied from the fuel cell 05c. That is, in such a circulating fluidized bed combustion furnace, fluidized material such as silica sand that forms a high-speed fluidized bed is present, and together with combustion ash generated by burning the main fuel described later, the combustor 01 and the cyclone 02, a fluidized bed heat exchanger 03 and a stand pipe 04 are circulated in the system. [0004] A high-speed fluidized bed is formed in the combustor 01, and the burning particles and gas exit the combustor 01 and are separated by a cyclone 02.
6. After passing through bag filter 07 and induction fan 08, chimney 0
Particles composed of fluidized material, combustion ash, and the like released from the system 9 and separated from the gas are guided to a fluidized bed heat exchanger 03 forming a high-speed fluidized bed through a standpipe 04, where the particles are formed. Heat exchanged. Further, the particles cooled by performing the heat exchange in the fluidized bed heat exchanger 03 return to the combustor 01 again, adjust the combustion temperature, and change the temperature of the combustor 0.
1 to form the high-speed fluidized bed required for combustion. [0005] The main fuel consisting of waste such as poultry manure incinerated in such a circulating fluidized bed combustion furnace is a main fuel hopper 01.
0 is supplied to the combustor 01. Further, since the combustion calorific value of the main fuel is small, the fuel for auxiliary combustion composed of heavy oil or the like added to the main fuel in order to continue the self-combustion is supplied from the auxiliary fuel tank 011 via a system different from the main fuel, and similarly. Is supplied to the combustor 01. [0006] Such combustion ash using chicken dung as a main fuel, in order to burn in the combustor 1, that is, to form a high-speed fluidized bed required in a circulating fluidized bed combustion furnace, increases the number of fine particles having a small particle size. Heavy fuel oil, etc., which is excessively contained and further used as a fuel for auxiliary combustion, has a small amount of ash generated by combustion. As a result, in order to form a high-speed fluidized bed and perform combustion, the fluid retained in the circulating fluidized bed combustion furnace The amount of material is reduced, making it difficult to continue operation. As a countermeasure, a fluid material such as silica sand having a predetermined particle size is generally supplied from the fluid material hopper 012 into the combustor 01. [0007] In addition, when mixed with fuel or the like, the combustor 01
The incombustibles supplied to the inside stay at the bottom of the combustor 01 and increase with the elapse of the operation time, and are discharged out of the system by the incombustible discharge conveyor 013 as necessary. [0008] Such a waste-fired circulating fluidized-bed combustion furnace using waste such as pork poultry, chicken dung and other livestock waste as a main fuel generally has the following problems.
That is, even in the above-described chicken-firing circulating fluidized-bed boiler, as described above, the combustion ash generated by the combustion of the main fuel composed of such waste forms a high-speed fluidized bed required for combustion in the combustor. Contains too many fine particles having a small particle diameter, which is not preferable as a fluid material. Accordingly, in order to maintain stable circulating fluidized bed combustion for a long period of time, it is necessary to constantly replenish fluidized material such as silica sand having a particle size necessary for forming a high-speed fluidized bed. However, the economic burden associated with purchasing the fluidized material increases. [0010] The present invention relates to the above-mentioned,
Waste livestock system as main fuel, the formation of the fast fluidized bed combustion ash becomes fine is difficult, there needs to be replenished constantly flowing material, eliminating the problem of a conventional waste-fired circulating fluidized bed combustion furnace Therefore, part of the combustion ash generated by the combustion of the main fuel is
Fluid material to be replenished by melting, softening, and granulating to convert the combustion ash with a large amount of fine particles into combustion ash with a large particle size that can be used for forming a high-speed fluidized bed so that it can be used as a fluid material. It is an object of the present invention to provide a waste-fired circulating fluidized-bed combustion furnace that can reduce the operating cost and reduce the operating cost. Therefore, a waste-fired circulating fluidized bed combustion furnace according to the present invention has the following means. (1) A livestock- based waste fuel containing a large amount of fine particles and generating undesirable combustion ash is required to obtain a fluid material for forming a high-speed fluidized bed required for combustion in a combustor. And a mixing device that mixes the fuel for combustion with a larger calorific value than the waste fuel and supplies the mixed fuel to the combustor. The fuel for auxiliary combustion may be a liquid such as heavy oil or a solid at normal temperature and a liquid under combustion conditions, for example, asphalt. Further, the mixing ratio of the waste fuel and the fuel for auxiliary combustion is such that the self-combustion in the combustor can be continued.
It is preferable that the pressure is not less than 00 kcal / kg. (2) The supplied fuel is burned, and the combustion ash generated by the combustion of the waste fuel is supplied with the high-temperature heat generated by the combustion of the auxiliary fuel having a large calorific value and good combustibility. Then, a combustor was provided which melts and softens the combustion ash and granulates it into particles of a preferable size suitable for forming a high-speed fluidized bed necessary for combustion of the combustor and usable as a fluidizing material. In the waste-fired circulating fluidized bed combustion furnace of the present invention, the combustion ash containing a large amount of fine particles having a small particle diameter, which is not preferable for forming a high-speed fluidized bed, is obtained by the means (1) and (2). By mixing the generated waste fuel such as chicken dung and the auxiliary fuel such as heavy oil with a mixing device in advance, the heat generated from the auxiliary fuel during combustion is efficiently transmitted to the waste fuel side. Can be As a result, the combustion ash generated in the combustion of the waste fuel is partially heated on the surface of the combustion ash at a high temperature field when the fuel for combustion is burned, that is, at a temperature higher than the average temperature in the combustor performing combustion. As a result, softening, melting, etc., occur, and the combustion ash is granulated to have a large particle size. Since the melting point of the combustion ash granulated through such a process is higher than the average temperature of the combustor, the combustion ash is less likely to be further melted and softened by the heat in the combustor. Can function as a fluidized material for a high-speed fluidized bed, which is required for combustion in the inside, that is, combustion in a circulating fluidized bed combustion furnace. [0016] Thereby, in order to maintain stable circulating fluidized bed combustion for a long period of time, it is necessary to constantly replenish the circulating fluidized bed combustion furnace. The economic burden associated with the purchase of fluidized material can be reduced, and operating costs can be kept low. [0017] Conversely, this translates into a reduction in the amount of combustion ash to be disposed of, which contributes to a reduction in ash processing costs and to secure a location for ash processing or to secure environmental conservation. Will be done. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a waste-fired circulating fluidized-bed combustion furnace according to the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing a first embodiment of a waste-fired circulating fluidized bed combustion furnace of the present invention. In the present embodiment, the conventional waste-fired circulating fluidized bed combustion furnace shown in FIG. 2 is improved as described below. In FIG. 1, the same parts as those in FIG. The description is omitted here. As shown in the figure, in this embodiment, the combustion ash of chicken dung and the like becomes fine particles, and it is not preferable to form a high-speed fluidized bed required for combustion in the combustor 1. Before the combustor 1 was supplied with the auxiliary fuel 5 such as asphalt into the combustor 1, a mixing device 7 was provided which was mixed in advance to provide the supplied fuel 8 . That is, the auxiliary fuel 5 from the auxiliary fuel tank 4 is supplied to a mixing device 7 including a feeder provided below the main fuel hopper 2, and similarly mixed with the main fuel 3 supplied from the main fuel hopper 2, The supplied fuel 8 is supplied into the combustor 1. Of the supplied fuel 8 supplied to the combustor 1, chicken poultry and the like, which is the main fuel 3, generally has a large amount of moisture and a low calorific value, and therefore, the combustor 1 first includes the auxiliary fuel The use fuel 5 burns, and then the main fuel 3 burns. The temperature at this time is temporarily 850 to 850, which is a general combustion temperature in the combustion in the combustor 1.
Since the temperature is higher than 900 ° C., a part of the combustion ash generated by burning the main fuel 3 is melted and softened to become a combustion ash containing a large amount of large granulated particles. That is, the granulated combustion ash contains a large amount of large particle size compared with the combustion ash generated only from the original main fuel 3 and is coarse. It shows the properties that can be used as a fluidizing material necessary to make it flow. This will be described based on a specific example. FIG. 2 shows the particle size distribution A of the combustion ash generated when chicken poultry as the main fuel 3 and asphalt as the auxiliary fuel 5 are separately supplied into the combustor 1 and burned.
And chicken dung and asphalt are mixed with the mixing device 7,
It shows the particle size distribution B of combustion ash generated when the fuel is supplied to the combustor 1 and burned. In the circulating fluidized bed combustion furnace, the particle size range usable as a fluid material is mainly determined by the performance of the cyclone 02. However, if the particle size range is 0.1 mm or more, it can be used as a fluid material. Comparing the two, the particle size distribution A of the combustion ash when the main fuel 3 and the auxiliary fuel 5 are separately supplied is about 20% by mass,
On the other hand, the particle size distribution B of the combustion ash when mixed and supplied as the supply fuel 8 is about 65% on a mass basis, and it can be seen that the amount of the combustion ash that can be a fluid material increases about three times. This means that, in other words, as in the present embodiment, the main fuel 3 and the auxiliary fuel 5 are mixed by the mixing device 7 to be supplied fuel 8 and supplied into the combustor 1. As a result, the consumption of silica sand, which is replenished to the circulating fluidized bed combustion furnace as a fluidized material, can be reduced, and the economy of operation of the circulating fluidized bed combustion furnace improves. The calorific value of chicken dung as the main fuel 3 is 500 to 1,500 kcal / kg, and
Asphalt combustion heat value is about 10,000
kcal / kg, and when chicken dung and asphalt are mixed to form the supplied fuel 8, the weighted average of the calorific value of the supplied fuel 8 that can be self-burned in the combustor 1 is 10
What is necessary is just to determine the mixing ratio of chicken manure and asphalt so that it may become 00 kcal / kg or more. As described above, according to the waste-fired circulating fluidized-bed combustion furnace of the present invention, (1) silica sand or the like is additionally charged by the configuration shown in the claims. Since the consumption of the flowing material can be reduced, the economy during operation is improved. (2) Since the consumption of fluidized material such as silica sand to be additionally added is reduced, the amount of combustion ash to be finally disposed of is also reduced. As a result, it is possible to contribute to the reduction of the ash processing cost and the preservation of the environment. And the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a first embodiment of a waste-fired circulating fluidized-bed combustion furnace according to the present invention. FIG. 2 is a diagram showing a separate combustor for separating waste fuel and auxiliary fuel. Fig. 3 is a diagram showing a comparison of the particle size distribution of combustion ash between the case where the mixture is charged and the case where the mixture is charged. Fig. 3 is a configuration diagram showing a conventional waste-fired circulating fluidized bed combustion furnace. [Description of Signs] 1,01 Combustor 2,010 Main fuel hopper 3 Main fuel 4,011 as waste fuel Auxiliary fuel tank 5 Auxiliary fuel 7 Conveyor as mixing device 8 Supply fuel 02 Cyclone 03 Fluidized bed heat exchanger 04 Stand pipes 05a, 05b, 05c Blower 06 Convection heat transfer surface 07 Bag filter 08 Induction fan 09 Chimney 012 Fluid material hopper 013 Non-combustible material discharge conveyor

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F23G 5/30 ZAB F23C 10/22 F23G 7/00 ZAB

Claims (1)

(57) [Claims] [Claim 1] Chicken dung, pork dung, etc. in which combustion ash becomes fine particles
In a waste-fired circulating fluidized-bed combustion furnace in which livestock-based waste fuel is burned in a combustor that forms and burns a high-speed fluidized bed, the calorific value of combustion is calculated from the waste fuel and the waste fuel. a mixing apparatus for supplying fuel by mixing with high co燃用fuel, before the supplied the fuel supply
By Rukoto burned in serial combustor, before Symbol fast fluidized waste characterized and this <br/> of layers to generate a combustion ash is granulated to a particle size that can be formed is fired circulating fluidized bed combustion furnace.