JPS6117810A - Multi-stage fluidized bed layer boiler - Google Patents

Abstract

PURPOSE:To improve the gas mixture by forming a contracted part in the fluid layer empty tower part and forming a fluid injection port in the proximity of the constricted part. CONSTITUTION:A projected wall 9 is formed above a burning gas outlet 10 in the upper fluidized layer 2 in the fluidized bed layer empty tower part 3. By this arrangement, a contracted part 3a is formed in the empty tower part 3. Fluid is injected from a fluid injection port 17 disposed near to the contracted part against burning gas G1 and G2 which are joined in the contracted part 3a in order to cause turbulence for more effective mixture of the two gases. By supplying air from the fluid injection port 17, it can be utilized as a two-stage burning port for reducing nitrogen oxides. Since the burnt gas expelled from the multiple fluidized layers can effectively mixed, there will be no adverse effect to heat conductive pipes in the downstream, and the boiler can be operated always under good conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a multistage fluidized bed boiler that improves the mixing of combustion gas.

<Prior art and its problems> Fluidized bed boilers that recover heat generated by combustion in a fluidized bed also need to be made larger in order to improve efficiency, but as the size increases, the area of the fluidized bed naturally increases. . For this reason, in order to suppress the increase in the installation area of the equipment due to the increase in size as much as possible, a multi-stage fluidized bed boiler in which fluidized beds are stacked in multiple stages in the vertical direction has been proposed.

Figure 4 shows a multistage fluidized bed boiler. The one shown is a two-stage fluidized bed, in which the combustion gases G□ and G2 generated from the lower fluidized bed 1 and the upper fluidized bed 2 ascend through the boiler tower section 3 and then pass through the superheater 5 and the economizer. 6 and is discharged to the outside. In this case, the combustion gases G and 02 tend to flow in a laminar flow as shown in the figure, and both pass through the heat exchanger tube groups 5 and 6 with insufficient mixing.

There is no problem if the surface combustion gases G and G2 have the same properties, but in reality, both fluidized beds are rarely operated under the same conditions, so the combustion gases G□ and G2 have the same properties. Their properties often differ as well. In particular, differences in gas temperature and gas-containing components will have an adverse effect on the downstream heat exchanger tube group. For example, if the temperature of combustion gas G1 is lower than 02, if both gases are mixed, the low-temperature combustion gas G2 remains poorly mixed even though the temperature is maintained above the dew point in the economizer 6. By passing through the economizer 6, low-temperature corrosion occurs in the portion through which the gas 02 passes.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the present invention provides a fluidized bed boiler in which a means for mixing combustion gas discharged from each fluidized bed is attached to the empty tower section.

<Summary of Means> In short, the present invention forms a condenser section in the fluidized bed's empty column to improve the mixing of a plurality of gases, and if necessary, forms a gas injection boat near the condenser section to improve gas mixing. This is a multi-stage fluidized bed boiler designed to provide good performance.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the upper fluidized bed 2 of the fluidized bed empty tower section 3
A projecting wall part 9 is formed at the upper part of the combustion gas outlet part 10, thereby forming a contracting flow part 3a in the empty column part 3. Reference numeral 17 denotes a gas injection port formed near the contraction part, which injects gas to the combustion gases G and G2 that have merged in the contraction part 3a to create a turbulent flow, thereby making the mixing of both gases more effective. . Gas injection port 1
By supplying air from 7, nitrogen oxides (N0
x) It can also be used as a two-stage combustion boat for reduction.

FIG. 2 is a modification of the device shown in FIG.
The structure is such that a strong turbulent flow is formed in a to further improve the mixing of both gases G and 02. In this case, in order to obtain high injection force while maintaining the 0□ supply amount to the inside of the furnace at the set value, combustion exhaust gas G is supplied as an inert gas in addition to or in place of air A as the injection gas. You may also do so.

FIG. 3 shows an application to another type of fluidized bed. This type of fluidized bed has two second-stage fluidized beds 2a and 2b formed above the first-stage fluidized bed 1 to face each other.
, each combustion gas GIT 02103 mixes relatively well at the confluence part, but there is a protruding wall part 9a in the upper part of this confluence part.
By locating 9b' opposite each other, each gas can be mixed more effectively.

<Effects> By implementing this invention, the combustion gases discharged from multiple fluidized beds can be mixed well, so there is no adverse effect on the downstream heat transfer tube group, and the boiler can be operated properly at all times. It can be performed.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a fluidized bed boiler according to the present invention, Fig. 2 is a partial sectional view of the fluidized bed boiler showing the mixing state of combustion gas in the contraction section, and Fig. 3 is a fluidized bed showing another embodiment. FIG. 4 is a sectional view of a conventional two-stage fluidized bed boiler. 1...Lower fluidized bed 2.2fL, 2b...Upper fluidized bed 3...
・Sky tower section 3a... Condenser section 17... Gas injection port

Claims (1)

[Claims] 1. In a fluidized bed boiler in which fluidized beds are arranged in multiple stages, a condensation section is formed in the empty column above the combustion gas outlet section of the uppermost fluidized bed, and the combustion gas is discharged from each fluidized bed. A multi-stage fluidized bed boiler characterized in that the exhaust gas is mixed in this condensation section. 2. The multi-stage flow according to claim 1, characterized in that a gas injection port is disposed near the contraction part, and the gas injected from the injection port promotes mixing of combustion gas. Layer boiler.