JPH11351549A - Combustion facility for high moisture coal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion facility for a high moisture coal for effectively drying and burning the coal containing much moisture without giving an adverse influence to a combustion of a pulverized coal in a burner. SOLUTION: The combustion facility for a high moisture coal comprises a heat exchanger 10 for preheating the air with a high temperature gas from a boiler 1 to a high temperature (about 700 deg.C) (e.g. a rotary generative heat exchanger, thereby supplying preheated high temperature air to a coal pulverizer 2. Since the high temperature air is used, a high moisture coal containing much moisture can be effectively dried and burned. Since the high temperature air is used instead of a conventional exhaust gas, an oxygen concentration in a finely pulverized coal igniting area near a burner becomes high, thereby expediting a combustion of the pulverized coal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion facility using high moisture coal as fuel.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional pulverized coal combustion facility. As shown in this figure, in the conventional pulverized coal combustion equipment, as ancillary equipment of the boiler 1, a coal pulverizer 2 (mill), a gas air heat exchanger 3 (GAH), a forced air blower 4
(FDF), an induction blower 5 (IDF), a stack 6, etc., preheat air with exhaust gas from the boiler 1, supply the preheated air (about 350 ° C.) to a mill 2 and dry while pulverizing coal. Then, the dry pulverized coal was supplied to the combustor 1a (burner) of the boiler together with air to burn it.

[0003]

The pulverized coal combustion equipment shown in FIG. 3 can be applied as it is when the surface moisture of the coal is about 5 to 20%. (2) has a problem that drying in the mill is insufficient and it is difficult to perform good pulverization, and combustion in the boiler is also adversely affected. Therefore, in order to apply such high-humidity coal, combustion equipment for high-humidity coal as shown in FIG. 4 is being studied. This pulverized coal combustion equipment is provided with a high temperature (for example, 8
(1000-1000 ° C.), and the high-temperature exhaust gas is supplied to a mill 2 and dried while pulverizing coal.
Dry pulverized coal is supplied to the burner 1a of the boiler together with air to burn it, and is heated at a high temperature (for example, 800 to
Since the exhaust gas of (00 ° C.) is used for drying, it can be applied to high-humidity coal containing about 30% or more of water.

However, in the high-humidity coal combustion facility shown in FIG. 4, the exhaust gas supplied to the mill 2 transports the pulverized pulverized coal to the burner 1a and is supplied as it is to the boiler together with the pulverized coal. Therefore, there has been a problem that the stability of combustion may be reduced when exhaust gas is used. That is, although the high-temperature exhaust gas of the boiler has a high temperature but a very low oxygen concentration (for example, 3 to 4%), the combustion of the pulverized coal in the burner section is adversely affected.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a high-humidity coal combustion facility capable of effectively drying and burning high-moisture coal with high moisture content without adversely affecting the combustion of pulverized coal in the burner section. Is to do.

[0006]

According to the present invention, there is provided a heat exchanger (10) for preheating air to a high temperature with high temperature exhaust gas from a boiler (1), and the preheated high temperature air is used as a coal crusher (2). The present invention provides a high-humidity coal combustion facility characterized in that it is supplied to a high-humidity coal coal.

According to the structure of the present invention, since the heat exchanger (10) for preheating the air to a high temperature with the high-temperature exhaust gas is provided,
For example, with exhaust gas at 800 to 1000 ° C.,
It can be heated to a high temperature of around 00 ° C. Therefore,
Using this high-temperature air, high-moisture coal with high moisture content can be effectively dried, pulverized and supplied to the burner. Furthermore, since high-temperature air is used instead of exhaust gas, the oxygen concentration is sufficiently high, and there is no possibility that the combustion of pulverized coal in the burner section will be adversely affected. That is, compared to the prior art, the oxygen concentration in the pulverized coal ignition region near the burner becomes higher, and as a result,
Pulverized coal combustion can be promoted.

According to a preferred embodiment of the present invention, the heat exchanger (10) is a regenerative heat exchanger. By using such a rotary regenerative heat exchanger, air is reduced to about 7
Even when heating to a high temperature of about 00 ° C., equipment costs can be reduced and a high heat exchange rate can be maintained as compared with other types of heat exchangers such as plate fins.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a combustion facility for high-humidity coal according to the present invention, and FIG. 2 is a configuration diagram of a burner for pulverized coal. As shown in FIG. 1, the high-humidity coal combustion facility of the present invention includes a coal pulverizer 2 (mill), a gas-air heat exchanger 3 (GAH), a forced air blower 4 (FDF) as ancillary facilities of the boiler 1 , An air blower 5 (IDF) and a stack 6 for preheating air with exhaust gas from the boiler 1 and supplying the preheated air (about 350 ° C.) to a combustor 1 a (burner) of the boiler. In this figure, P
AF is a primary ventilator.

As shown in FIG. 2, a burner 1a of the boiler, that is, a burner for pulverized coal, converts primary air and pulverized coal supplied from the mill 2 into a furnace 1b of the boiler 1 (right side in FIG. 2). And a secondary air duct 7b around which the secondary air preheated by the gas air heat exchanger 3 is supplied. As is clear from the configuration of FIG. 2, even if the oxygen concentration of the secondary air itself is high,
If the exhaust gas having a very low oxygen concentration is used instead of the secondary air, the oxygen concentration in the pulverized coal ignition region near the burner surrounding the pulverized coal may decrease, and stable combustion of the pulverized coal may be difficult.

As shown in FIG. 1, the high-humidity coal combustion facility of the present invention further includes a heat exchanger 10 for preheating air to a high temperature (preferably 700 ° C. or higher) with the high-temperature exhaust gas 8a from the boiler 1. Have. As the heat exchanger 10, it is preferable to use a rotary regeneration type heat exchanger as disclosed in, for example, Japanese Patent Application Laid-Open No. 8-327262. Such a regenerative heat exchanger has a lower manufacturing cost than other types of heat exchangers such as plate fins, and can easily heat air to a high temperature of about 700 ° C. Therefore, by using such a regenerative heat exchanger, equipment costs can be reduced,
And a high heat exchange rate can be maintained.

According to the configuration of the present invention described above, the heat exchanger 10 for preheating the air to a high temperature with the high temperature exhaust gas of the boiler is provided. Can be heated to high temperatures. Accordingly, the high-humidity coal having a high moisture content can be effectively dried in the mill 2 using the high-temperature air 8b, and can be burned in the combustor 1a of the boiler. Further, since the high-temperature air 8b is used instead of the conventional exhaust gas, the oxygen concentration is sufficiently high, and there is no possibility that the combustion of the pulverized coal in the burner section will be adversely affected. That is, as compared with the prior art, the oxygen concentration in the pulverized coal ignition region near the burner is increased, and as a result, the combustion of the pulverized coal can be promoted.

It should be noted that the present invention is not limited to the above-described embodiments and examples, and it is needless to say that various changes can be made without departing from the gist of the present invention.

[0014]

As described above, the high-humidity coal combustion facility of the present invention can effectively dry and burn high-moisture high-content coal using high-temperature air, and can substitute for exhaust gas. Since high-temperature air is used, the oxygen concentration in the pulverized coal ignition region near the burner is increased, and excellent effects such as not adversely affecting the combustion of the pulverized coal in the burner portion are obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a high-humidity coal combustion facility according to the present invention.

FIG. 2 is a configuration diagram of a burner for pulverized coal.

FIG. 3 is a configuration diagram of a conventional pulverized coal combustion facility.

FIG. 4 is a configuration diagram of a conventional high-humidity coal combustion facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler 1a Combustor (burner) 2 Coal crusher (mill) 3 Gas-air heat exchanger (GAH) 4 Push-in blower (FDF) 5 Induction blower (IDF) 6 Stack 7a Pulverized coal nozzle 7b Secondary air duct 8a High temperature Exhaust gas 8b High-temperature air 10 Heat exchanger (rotary regeneration heat exchanger)

Claims (2)

[Claims] A high-humidity air supply system comprising a heat exchanger (10) for preheating air to a high temperature with high-temperature exhaust gas from a boiler (1), and supplying the preheated high-temperature air to a coal crusher (2). Combustion equipment for coal splitting. 2. The high-humidity coal combustion facility according to claim 1, wherein the heat exchanger is a regenerative heat exchanger.