JPH03286913A - Pressurized fluidized-bed boiler - Google Patents

Abstract

PURPOSE:To obtain a pressurized fluidized-bed boiler which shortens boiler starting time and improves thermal efficiency by providing a air-cooling means which guides the air of a pressure vessel to cool a cyclone and trapped ash and an air supply means which supplies air from the cooling air to a boiler body as the combustion air. CONSTITUTION:Combustion waste gas flows into a combustion waste gas line 8, gets its ash or the like trapped through a cyclone 9, and is then supplied to a gas turbine, etc. This cyclone 9 allows the air of a pressure vessel 2 to come from an introduction port 11 into an upper header 12 and to flow into a lower header 13 through a cooling pipe wall. This way of air's passage through the cooling pipe wall makes the air exchange heat with a refractory material heated by high-temperature combustion waste gas, so that the refractory material is cooled. Thus, boiler starting time can be shortened. Air cooing into the upper header 12 is heated by the cooling pipe wall and then preheated on heating by the ash cooling pipe 16 of an air cooling means 17. This preheated air comes into the combustion air supply line 5 of an air supply means 19 through an air line 18 and is supplied into a boiler body 1 with the combustion air. It follows that thermal efficiency improves.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a pressurized fluidized bed boiler, and in particular to a pressurized fluidized bed boiler that cools a cyclone that collects ash from combustion exhaust gas and cools the collected ash. It concerns boilers.

[Prior Art] In recent years, pressurized fluidized bed boilers have been proposed that can burn coal with high combustion efficiency, are compact, have a high desulfurization rate, and improve plant thermal efficiency.

This pressurized fluidized bed boiler fluidizes and burns powdered coal together with bed material under high pressure using combustion air in the boiler body housed in a pressure vessel. part is cooled by the heat exchanger tube. The steam generated by this heating is supplied to a steam turbine, etc., and the high-temperature combustion exhaust gas from the boiler body is supplied to a gas turbine, etc. after ash and the like are collected in a cyclone.

[Problems to be Solved by the Invention] By the way, the inside of the above-mentioned cyclone is internally reinforced with a refractory material, which is the inner wall, but due to the high temperature of the combustion exhaust gas,
The refractory must be made thicker.

For this reason, if a certain amount of time is not taken to bring the refractory from a cold state to a warm state, cracks will form in the refractory, causing the problem that it takes time to start up the boiler.

Therefore, the present invention was made to solve the above problems, and an object of the present invention is to provide a pressurized fluidized bed boiler that makes it possible to shorten the boiler startup time.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a pressure vessel with:
A boiler body is provided that fluidizes coal and bed material with combustion air to burn the coal, and a cyclone is provided that collects ash from the combustion exhaust gas from the boiler body.
An air cooling means is provided for guiding the air in the pressure vessel to cool the cyclone and the collected ash, and an air supply means is provided for supplying the air from the air cooling means to the boiler body as the combustion air. It is something.

[Function] According to the above configuration, the cyclone warmed by the combustion exhaust gas is cooled by the air in the pressure vessel guided by the air cooling means, and the collected ash is also cooled. As the cyclone is cooled in this way, the refractory that is the inner wall of the cyclone can be made thinner, so it takes less time to raise the temperature of the refractory, so the boiler startup time can be shortened.

In addition, since the air that has been preheated by cooling the cyclone and collected ash together with the combustion air by the air supply means, or only the preheated air, is supplied to the boiler body, heat loss due to air within the boiler body is reduced. Therefore, thermal efficiency is improved.

[Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, 1 is a boiler body housed in a pressure vessel 2, to which is connected a coal supply line 3 for supplying powdered coal (for example, coal with a particle size of about 10 m).

The pressure vessel 2 is connected to an air supply line 4 for making the inside of the vessel 2 high pressure, and the boiler body 1 is connected to
A combustion air supply line 5 for introducing combustion air is connected. Powdered coal is fluidized and combusted together with bed material made of ash, limestone, dolomite, etc. in the boiler body 1 under high temperature and high pressure by high pressure combustion air from this combustion air supply line 5. .

A heat exchanger tube 6 is provided in the boiler body 1 to generate steam by heating a part of combustion in the fluidized bed, and a steam line 7 is connected to the heat exchanger tube 6. Furthermore, a combustion exhaust gas line 8 for flue gas is connected to the upper part of the boiler main body 1 . A cyclone 9 is interposed in the pressure vessel 2 of the combustion exhaust gas line 8 to collect dust such as ash (particularly ash) from the combustion exhaust gas. An ash discharge pipe 10 for discharging the collected ash is connected to the lower part of the cyclone 9.

The cyclone 9 is formed into an upright, substantially cylindrical shape, and an air-cooled imm cooled by the air inside the pressure vessel 2. Specifically, an upper header 12 having an opening 11 at the upper part of the cyclone 9 and a lower header 13 at the lower part are provided, and a plurality of cooling pipes 1 are provided between the headers 12 and 13.
4 to form a cooling pipe wall, which is disposed along the inner periphery of the cyclone 9.

The inner wall of the cooling pipe is lined with a refractory material 15 made of plastic or the like, and the high-temperature refractory material is cooled through the cooling pipe wall by air from the inlet 11 of the upper header 12. It is supposed to be done. Furthermore, the cyclone is
In the illustrated example, there is one cyclone, but since multiple cyclones are installed in parallel, each cyclone may be provided with a cooling pipe wall for cooling the refractory.
The ash cooling pipe 16 is 21 so as to cover the ash discharge pipe 10! It is set up so that it is close to the control structure. The upper part of this ash cooling pipe 16 is connected to the lower header 13 to form an air cooler 817, and the ash in the ash discharge pipe 10 is cooled by the air from the lower header 13.

An air line 18 is connected to the lower part of the ash cooling pipe 16,
This air line 18 is connected to the combustion air supply line 5 to constitute an air supply means 19, so that air from the air line 18 is supplied to the boiler main body 1 together with combustion air.

Next, the operation of Honjitsu aS will be explained.

The high-pressure air from the air supply line 4 makes the pressure inside the pressure vessel 2 high (for example, about 17 ka/cd), and the air from the combustion air supply line 5 is supplied to the boiler main #l. Then, the powdered coal and bed material are fluidized under high temperature (about 850 to 950° C.) and high pressure (for example, about 15 to 16 klJ/ad) to form a fluidized bed, and the coal is combusted. A part of the combustion heat in the fluidized bed is converted into steam by the heat exchanger tube 6 to generate steam, which flows into a steam line 7 and is supplied to a steam turbine or the like.

The combustion exhaust gas flows into a combustion exhaust gas line 8, and after ash and the like in the gas are collected via a cyclone 9, it is supplied to a gas turbine or the like.

In the cyclone 9, since the pressure inside the pressure vessel 2 is high, the air inside the pressure vessel 2 flows from the inlet 11 to the upper header 1.
2 and flows into the lower header 13 through the cooling pipe wall. As the air passes through the cooling pipe wall in this way, the air and the refractory heated by the high-temperature combustion exhaust gas exchange heat, thereby cooling the refractory. Therefore, although the thickness of the refractory can be made thin, it takes less time to bring the refractory from a cold state to a warm state, so the boiler startup time can be shortened.

Furthermore, since the thickness of the refractory can be made thin, maintenance of the cyclone 9 can be easily performed at low cost.

The air flowing into the lower header 13 enters the ash cooling pipe 16 where it collects the high temperature collected ash from the cyclone 9 and the ash discharge pipe 1.
The ash is cooled by heat exchange through 0. This cooled ash is discharged from the ash discharge pipe 10 and treated in another treatment system.

As mentioned above, the air entering the upper header 12 is warmed by the cooling tube walls and then further warmed and preheated by the ash cooling tubes 16. This preheated air enters the combustion air supply line 5 via the air line 18 and is supplied to the boiler body 1 together with the combustion air. In this way, since the air supplied to the boiler main body 1 is preheated, the boiler i
Thermal efficiency is improved because heat loss due to air inside the tank is reduced. In addition, cyclone 9 (combustion exhaust gas)
Since the heat of the boiler and the heat of the collected ash are recovered by the air and returned to the boiler main body l, the exhaust heat can be used effectively.

In this embodiment, combustion air is supplied to the boiler body along with air preheated by heat from a cyclone or the like from inside the pressure vessel, but only preheated air may be supplied to the boiler body.

[Effects of the Invention] In summary, the present invention exhibits the following excellent effects.

(T) Since the cyclone was cooled with the air inside the pressure vessel,
Boiler startup time can be shortened.

(2) Since the air that has been cooled by the cyclone and the collected ash is supplied to the boiler body as combustion air, thermal efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is a boiler body, 2 is a pressure vessel, 9 is a cyclone, 17 is an air cooling means, and 19 is an air supply means.

Claims (1)

[Claims] 1. A boiler body is provided in the pressure vessel to fluidize coal and bed material with combustion air to burn the coal, and a cyclone is provided to collect ash from the combustion exhaust gas from the boiler body. An air cooling means is provided to guide the air inside to cool the cyclone and the collected ash.
A pressurized fluidized bed boiler further comprising an air supply means for supplying air from the air cooling means to the boiler body as the combustion air.