JP2002168423A - Circulation fluidized bed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circulation fluidized bed boiler for improving economy by reducing wear at the inlet section of a cyclone, and eliminating the need for frequently exchanging wear-resistant materials in the cyclone. SOLUTION: An ash separation chamber 23 is provided at the upstream side of the cyclone 4. The ash separation chamber 23 reduces the flow rate of an exhaust gas that is generated by combustion in a furnace 1, separating ash contained in the exhaust gas according to gravity classification, and returning the ash to the bottom of the furnace 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating fluidized bed boiler.

[0002]

2. Description of the Related Art In recent years, refuse solidified fuel (RDF: Refuse D) which has attracted attention as an effective use of city refuse.
Development of boiler power generation equipment using waste such as enhanced fuel (biofuel) and biomass is underway.

As one type of the boiler power generation equipment, there is a circulating fluidized bed boiler, as shown in FIG.
A furnace 1 for burning waste while solidifying fuel and the like together with a bed material 3 made of sand, limestone or the like by primary air A blown out from an air dispersion nozzle 2 and being connected to an upper part of the furnace 1; A cyclone 4 for collecting ash contained in exhaust gas generated by combustion in the furnace 1,
An external heat exchanger 7 for introducing ash collected by the cyclone 4 through an ash drop tube 5 to cool the ash and circulating the ash back to the bottom of the furnace 1 through an ash return tube 6; The exhaust gas from which the ash has been collected in 4 is introduced, and has a rear heat transfer section 10 in which a superheater 8 and a economizer 9 are disposed.

Downstream of the economizer 9 of the rear heat transfer section 10, there is provided a gas air heater 12 for heating the air fed from the forced draft fan 11 by the heat of the exhaust gas. The gas air heater 12 is heated by the gas air heater 12. Air is supplied as primary air A to the bottom of the furnace 1 through the primary air line 13 and the secondary air line 1 is branched from the primary air line 13.
The secondary air B is supplied as a secondary air B to a required position in the vertical middle of the furnace 1 through the air flow 4, and the air supplied from the air blower 15 for flow is supplied via the air line 18 for flow to the external heat exchanger 18. It is supplied to the bottom of the vessel 7 as flowing air C. A damper 16 for adjusting the flow rate of the primary air A is provided in the middle of the primary air line 13 on the downstream side of the branch of the secondary air line 14, and a secondary air B is provided in the middle of the secondary air line 14. A damper 17 for adjusting the flow rate is provided.

[0005] The external heat exchanger 7 has a flow air C
Box 21 for blowing air upward from the air distribution nozzle 20 to generate superheated steam by heat exchange with circulating ash in the seal box 19 above the air distribution nozzle 20 and introduce the superheated steam into the steam turbine. Of the final superheater 22 is disposed. or,
The external heat exchanger 7 considers that the pressure in the lower part of the furnace 1 is generally higher than the pressure in the lower part of the cyclone 4, and in this state, the exhaust gas in the furnace 1 is reduced in the lower part of the cyclone 4. To prevent it from flowing into the ash drop tube 5 side,
In addition, the ash separated in the cyclone 4 is formed in a so-called siphon-like shape so that the ash can surely flow down into the furnace 1 and return.

In a circulating fluidized-bed boiler as a boiler power generation facility as described above, air fed from a forced air ventilator 11 is heated by a gas air heater 12, and primary air A is sent to the bottom of the furnace 1 via a primary air line 13. And is supplied as secondary air B to a required position in the vertical middle part of the furnace 1 via a secondary air line 14 branched from the primary air line 13, and is further supplied to a flow air blower 15.
Is supplied as fluidizing air C to the bottom of the external heat exchanger 7 via the fluidizing air line 18 in this state, and in this state, the solidified fuel or the like Of the bed material 3 by the primary air A blown out from the air dispersing nozzle 2
Combustion while fluidizing with.

Exhaust gas generated by the combustion of waste in the furnace 1 is blown up together with the ash and introduced into the cyclone 4, where the ash is collected, and the ash collected by the cyclone 4. Is introduced into an external heat exchanger 7 as an ash recirculation device from an ash falling pipe 5 connected to the lower part of the cyclone 4, and after the heat is removed and cooled in the external heat exchanger 7, the ash return pipe 6 is removed. It is returned to the bottom of the furnace 1 through the furnace and circulated.

The exhaust gas from which the ash has been separated by the cyclone 4 is led to a rear heat transfer section 10, where heat is recovered in a superheater 8 and a economizer 9 of the rear heat transfer section 10, and further, in a gas air heater 12. After being collected, it is discharged to the atmosphere from a chimney via a dust collector (not shown).

On the other hand, the boiler feed water is heated by the exhaust gas in the economizer 9, flows through the steam drum (not shown), flows through the boiler furnace wall 1a of the furnace 1, returns to the steam drum again, becomes saturated steam, and is overheated. The superheated steam introduced into the heater 8 and superheated by the exhaust gas, and superheated in the superheater 8,
The superheated steam guided to the final superheater 22 and further superheated by the circulating ash, and superheated in the final superheater 22, is introduced into a steam turbine to generate power.

[0010]

In the case of a circulating fluidized bed boiler as described above, the cyclone 4 is designed to increase the flow rate of exhaust gas at the inlet thereof in order to improve the classification performance. Since the gas flow rate is proportional to the power of the gas to the power of 3.5, wear at the inlet of the cyclone 4 has become a problem, and the wear-resistant material inside the cyclone 4 has to be frequently replaced, which is wasteful.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a circulating fluidized bed boiler that can reduce wear at the cyclone inlet, eliminate the need for frequent replacement of wear-resistant materials inside the cyclone, and improve economic efficiency. It is something to offer.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a furnace for burning while fluidizing a fuel together with a bed material, and an ash connected to an upper portion of the furnace and contained in exhaust gas generated by combustion in the furnace. In a circulating fluidized bed boiler equipped with a cyclone that collects and returns to the bottom of the furnace, in the upstream part of the cyclone, the flow rate of exhaust gas generated by combustion in the furnace is reduced, and ash contained in the exhaust gas is classified by gravity. The present invention relates to a circulating fluidized bed boiler provided with an ash separation chamber which is separated and returned to the bottom of the furnace.

According to the above means, the following effects can be obtained.

Exhaust gas generated by the combustion of fuel in the furnace is blown up together with the ash and introduced into the ash separation chamber.
The flow rate of the exhaust gas is reduced in the ash separation chamber, a part of the ash contained in the exhaust gas is separated by gravity classification, returned to the bottom of the furnace, and the ash concentration in the ash separation chamber is reduced. Is introduced into a cyclone where ash is collected, and the ash collected in the cyclone is returned to the bottom of the furnace and circulated.

As described above, the amount of wear is proportional to the 3.5th power of the flow velocity of the gas, but at the same time, the amount of wear is proportional to the concentration of particles contained in the gas. As in, the flow rate of the exhaust gas is reduced in the ash separation chamber, and a part of the ash contained in the exhaust gas is separated by gravity classification,
By reducing the concentration of the ash contained in the exhaust gas and then introducing the ash into the cyclone, the amount of wear at the cyclone inlet can be reduced.

[0016]

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

FIG. 1 shows an example of an embodiment of the present invention. In the figure, portions denoted by the same reference numerals as those in FIG. 2 represent the same components, and the basic configuration is the same as that of the conventional device shown in FIG. The feature of this illustrated example is that, as shown in FIG. 1, the flow rate of the exhaust gas generated by the combustion in the furnace 1 is reduced in the upstream part of the cyclone 4 and is included in the exhaust gas as shown in FIG. An ash separation chamber 23 is provided for separating ash by gravity classification and returning the ash to the bottom of the furnace 1.

The bottom of the ash separation chamber 23 is provided with an ash separation tube 24.
The ash separated in the ash separation chamber 23 is connected to the upper portion of the seal box 19 through the seal box 1.
The ash collected by the cyclone 4 is merged with the ash 9 and returned from the seal box 19 to the bottom of the furnace 1 via the ash return pipe 6.

Next, the operation of the above illustrated example will be described.

Exhaust gas generated by the combustion of fuel such as waste in the furnace 1 is blown up together with the ash and introduced into the ash separation chamber 23 where the flow rate of the exhaust gas is reduced. Part of the ash contained in the exhaust gas is separated by gravity classification and introduced into the seal box 19 via the ash separation tube 24.

The exhaust gas whose ash concentration has been reduced in the ash separation chamber 23 is introduced into the cyclone 4, where the ash is collected, and the ash collected by the cyclone 4 is connected to the lower part of the cyclone 4. After being introduced from the ash falling pipe 5 into the external heat exchanger 7 as an ash recirculation device, the heat is removed by the external heat exchanger 7 and cooled, the ash is separated together with the ash separated in the ash separation chamber 23. Is returned to the bottom of the furnace 1 via the ash return pipe 6 and circulated.

Here, as described above, the amount of wear is proportional to the power of gas to the 3.5th power, but at the same time, the amount of wear is proportional to the concentration of particles contained in the gas. As shown in the example, the flow rate of the exhaust gas is reduced in the ash separation chamber 23, a part of the ash contained in the exhaust gas is separated by gravity classification, and the concentration of the ash contained in the exhaust gas is reduced before being introduced into the cyclone 4. This makes it possible to reduce the amount of wear at the inlet of the cyclone 4.

In the ash separation chamber 23, the flow rate of the exhaust gas once decreases, but at the inlet of the cyclone 4, the cross-sectional area of the flow path is narrowed and the flow rate of the exhaust gas increases again. No worries.

In this manner, wear at the inlet of the cyclone 4 can be reduced, frequent replacement of the wear-resistant material inside the cyclone 4 becomes unnecessary, and the economic efficiency can be improved.

The circulating fluidized-bed boiler of the present invention is not limited to the above-described example, but may be variously modified without departing from the gist of the present invention.

[0026]

As described above, according to the circulating fluidized bed boiler of the present invention, the wear at the inlet of the cyclone can be reduced, and the need to frequently replace the wear-resistant material inside the cyclone can be eliminated. An excellent effect that the property can be enhanced can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace 3 Bed material 4 Cyclone 23 Ash separation room

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23C 10/24 F23C 11/02 308 10/02 311 F-term (Reference) 3K064 AA06 AB01 AD05 AD08 AE15 BA07 BA15 BA19 4D053 AA03 AB01 BA01 BB02 BC01 BD04 DA02 DA06 4G070 AA01 AB06 BB32 CA09 CA13 CA25 CA26 CA30 CB02 DA01

Claims (1)

[Claims] 1. A furnace for burning while fluidizing a fuel together with a bed material, and an ash connected to an upper portion of the furnace and contained in exhaust gas generated by combustion in the furnace and collected to a bottom of the furnace. In a circulating fluidized bed boiler equipped with a returning cyclone, the flow rate of exhaust gas generated by combustion in the furnace is reduced upstream of the cyclone, and ash contained in the exhaust gas is separated by gravity classification and returned to the bottom of the furnace. A circulating fluidized bed boiler comprising an ash separation chamber.