JPH0335932Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed combustion furnace, and in particular to an improvement of a fluidizing air jet nozzle provided on a distribution plate at the bottom of the furnace.

Coal-fired boilers, garbage incinerators, woodchip-fired boilers, etc. that utilize fluidized bed technology have been developed and are all entering the practical stage.

To explain the fluidized bed formation process, the first
As shown in the figure, a fluid substance 3 is filled on the air distribution plate 2 at the bottom of the combustion furnace 1, and air is flowed upward from air jet nozzles 4 arranged at regular intervals on the air distribution plate 2. While the air supply flow rate is low, the fluid material 3 is in a fixed bed state as shown in the figure, but when the air supply flow rate exceeds the fluidization start speed of the fluid material 3, the fluid material floats to the top and becomes the state shown in FIG. As shown, it becomes a fluidized bed that looks like it is boiling.

If the fluidized material 3 thus formed into a fluidized bed is a combustible material, continuous combustion of the fluidized material 3 becomes possible by igniting it.

Then, when the supply of air from the air jet nozzle 4 is stopped, the fluidized substance 3 settles and returns to the original fixed bed state, and the fluidized bed combustion stops.

When this fluidized bed combustion stops, the high-temperature fluid substance 3 enters the air jet nozzle 4, flows backward into the wind box 5, and falls.
The air supply pipe connected to the pipe may become dirty or clogged, and may even burn out.

For this reason, at present, generally when fluidized bed combustion is stopped, fluidized material 3 is placed inside the air jet nozzle 4.
A cover made of special steel plate with air circulation holes is placed over the lid to prevent air from entering.

However, even with a lid made of heat-resistant special steel plate, combustion furnace 1
In the high temperature environment inside, problems such as burnout and friction may occur. Furthermore, when fluidized bed combustion is stopped, the pressure inside the combustion furnace 1 is high and the pressure inside the wind box 5 is low, so even if the lid is covered, high-temperature fluid material 3 enters through the air circulation holes in the lid, and furthermore, the air jet nozzle 4, flows backward into the wind box 5, and falls, resulting in staining or burning of the wind box 5 and the air supply pipe connected thereto. Therefore, even if fluidized bed combustion is stopped, it is necessary to supply air into the wind box 5 so that the pressure inside the combustion furnace 1 and the pressure inside the wind box 5 are balanced, and the pressure inside the combustion furnace 1 is Since the pressure in the wind box 5 decreases over time, the pressure within the wind box 5 must be decreased accordingly, which is extremely troublesome to control.

The present invention was devised in view of these circumstances, and it is possible to prevent the fluidized substance from flowing back into the wind box 5 or falling into it when fluidized bed combustion is stopped, and also to provide airflow that will not cause burnout or wear. The present invention aims to provide a fluidized bed combustion furnace equipped with a jet nozzle.

As shown in FIG. 3, the fluidized bed combustion furnace of the present invention has a large number of air jet nozzles 6 arranged at regular intervals on the air distribution plate 2 at the bottom of the furnace, and is made of porous refractory (porous brick). It is characterized in that a cylindrical sleeve 7 is fitted into the sleeve. The illustrated air ejection nozzle 6 made of porous refractory has a convex (or trapezoidal) longitudinal section, has an outer sleeve 7 fitted around the upper part, and is bored at regular intervals in the air distribution plate 2 at the bottom of the furnace. It is fitted into the convex through hole 8 from below and protrudes upward, and is supported by an annular support plate 9 attached to the periphery of the through hole 8 on the lower surface of the furnace bottom air distribution plate 2 . This porous refractory air jet nozzle 6
has uniformly distributed pores, excellent air permeability, and a dense structure. Further, the air jet nozzle 6 made of this porous refractory has excellent heat resistance and wear resistance under high temperatures, and can be formed into any desired shape.

The porous refractory air jet nozzle 6' shown in FIG. The furnace bottom air distribution plate 2 is fitted from below into the drilled convex through hole 8' so that only the upper part of the cylindrical guide 11 protrudes upward.
The lower surface of the hole 8' is supported by an annular support plate 9 attached to the periphery of the through hole 8'.

The air ejection nozzle 6'' made of porous refractory shown in FIG. It protrudes upward and is fitted from below into convex holes 8' bored at regular intervals in the furnace bottom air distribution plate 2, so that the through holes 8' are formed on the lower surface of the furnace bottom air distribution plate 2. It is supported by an annular support plate 9 attached to the periphery of.

A porous refractory air jet nozzle 6 as described above,
In a fluidized bed combustion furnace equipped with 6' and 6'', the fluidized substance 3 is filled on the bottom air distribution plate 2 in the same manner as shown in FIG. When supplied, the fluidizing air is ejected from porous refractory air ejection nozzles 6, 6', 6'' disposed on the hearth bottom diffuser plate 2. In blowing out this fluidizing air, the air blowing nozzles 6, 6', and 6'' of the porous refractories shown in FIGS. 3 to 5 have pores uniformly distributed and have excellent air permeability. As a result, sufficient fluidizing air is ejected through the air, and the flow velocity reaches the fluidization starting speed of the fluid material 3 relatively quickly, and the cylindrical sleeve 7 fitted around the air jet nozzles 6, 6', 6'' The cylindrical guide 11 suppresses air escaping to the surroundings, further increases the flow velocity of the ejected air, and fluidizes the fluid material at an early stage, causing the fluid material 3 to float to form a fluidized bed. Therefore, if the fluidized material 3 is a combustible material, if it is ignited immediately, fluidized bed combustion will start.

In this fluidized bed combustion, the air jet nozzles 6, 6', 6'' of each porous refractory rub against the burning fluid material 3 in a high-temperature environment.
It has excellent wear resistance, so there are no problems such as burnout or abrasion.

When the jetting of fluidizing air from each air jetting nozzle 6, 6', 6'' is stopped, the fluidizing substance 3 settles and becomes a fixed bed state, and fluidized bed combustion stops.At this time, inside the combustion furnace 1 Since the pressure is high, the fluid material 3 tries to flow back toward the wind box 5 side, but the structure of the porous refractory air jet nozzles 6, 6', 6'' is so dense that the particles of the fluid material 3 cannot penetrate. Even if some particles enter the pores on the top surface, they cannot enter any further. Therefore, there is no possibility that the fluid material will flow backwards or fall toward the wind box 5 side.

As can be seen from the above explanation, the fluidized bed combustion furnace of the present invention has a large number of air jet nozzles arranged at regular intervals on the air distribution plate at the bottom of the furnace. It is made of high quality refractory material, and a cylindrical sleeve is fitted to the nozzle, so it can supply enough fluidizing air necessary for fluidized bed combustion.
Smooth fluidized bed combustion is possible. In addition, the porous refractory air jet nozzle has excellent heat resistance and wear resistance under high temperatures, so it does not burn out or wear out during fluidized bed combustion, and can be used for a long period of time and has a long life. Therefore, the maintainability of the fluidized bed combustion furnace is improved. Furthermore, the air jet nozzle of porous refractories has a dense structure that particles of fluid material cannot pass through, so when fluidized bed combustion is stopped, even if the pressure inside the combustion furnace is high, the high temperature fluid material will pass through the air jet nozzle. There is no backflow or falling to the wind box side, which has excellent effects such as eliminating staining and burnout of the wind box and air supply pipe.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the state of the fixed bed in a conventional fluidized bed combustion furnace, and FIG. 2 is a schematic vertical sectional view showing the state during fluidized bed combustion in the fluidized bed combustion furnace. 3 to 5 are longitudinal cross-sectional views of essential parts showing various examples of air jet nozzles in the fluidized bed combustion furnace of the present invention. 1... Fluidized bed combustion furnace, 2... Furnace bottom air distribution plate, 6, 6', 6''... Porous refractory air jet nozzle.

Claims (1)

[Scope of utility model registration request] In a fluidized bed combustion furnace, a large number of air jet nozzles arranged at regular intervals on the air distribution plate at the bottom of the furnace are made of porous refractory material, and a cylindrical sleeve is fitted over the air jet nozzles. Fluidized bed combustion furnace.