JPS58221313A - Utilization of waste gas from gas turbine - Google Patents

Abstract

PURPOSE:To minimize the waste gas from a gas turbine conventionally dissipated into the atmosphere by a method wherein the oxygen from a supply source other than the waste gas from the gas turbine makes up for the insufficient volume of oxygen due to said gas. CONSTITUTION:An air supply duct 10 provided on a blower 11 is entirely connected to waste gas duct 4 provided between a bypass duct 5 and a tube heating furnace such as a thermal cracking furnace for producing ethylene or a burning unit 9 such as a boiler. A gas turbine 2a with small capacity can supply itself with the oxygen volume required for normal operation of the burning unit 9 or less. The atmospheric air is supplied for the burning unit 9 making up for the insufficient volume of oxygen supplied from the gas exhausted from the gas turbine 2. Besides the burnt and exhausted gas from a tube heating furnace or boiler may be utilized effectively circulating the calories conventionally dissipated into the atmosphere in a combustion chamber by means of heat exchanging with the burning air in an preheating chamber 14. This preheated air may be introduced into said exhaust gas duct 4 making up for the insufficient volume of oxygen for burning said unit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of effectively utilizing high temperature exhaust gas having a high residual oxygen concentration.

Generally, industrial gas turbines are widely used to drive rotating equipment such as generators or compressors. The temperature of the exhaust gas discharged from this gas turbine is 400 to 600.
The amount of heat it retains is as high as ``C'' (1), which is by no means small.Also, the residual oxygen concentration in this exhaust gas is relatively high at 13 to 17% by volume, so this exhaust gas is By using it in place of combustion air in a type heating furnace or boiler, it becomes possible to recover the amount of heat held in the exhaust gas and use it effectively.

That is, as shown in FIG. 1, air is taken into the gas turbine 2 through the air intake duct 1, fuel is supplied to the gas turbine 2 through the fuel supply pipe 3, and the exhaust gas is sent to one or two turbines through the exhaust gas duct 4. By guiding the exhaust gas to the combustion device 9 such as the above-mentioned tube heating furnace or boiler and using the exhaust gas as combustion air, it becomes possible to recover and effectively utilize the amount of heat held in the exhaust gas.

In addition, a branch duct 5 is branched from the exhaust gas duct 4 in order to release all or part of the gas turbine exhaust gas to the atmosphere when the combustion device 9 such as the tube heating furnace or boiler is stopped or operated at low load. An exhaust stack 7 is connected to the pipe. The amount of exhaust gas (2) supplied to the combustion device 9 and the amount of exhaust gas supplied to the exhaust stack 7 are determined by the damper 6.
6a.

However, the load on the combustion device 9, such as the tube heating furnace or boiler, is not always constant, and the amount of oxygen required for combustion is also not constant. Therefore, the amount of exhaust gas containing oxygen in excess of the amount required by the combustion device 9 such as a tube heating furnace, boiler, etc. during normal operation, that is, the maximum amount necessary or an amount with sufficient margin, is supplied to the combustion device 9. A large gas turbine that can be supplied is required.

For this purpose, excess gas turbine exhaust gas in excess of the amount used as normal combustion air in the combustion device 9, such as a tube heating furnace or boiler, must be discharged from the exhaust stack, and the gas turbine exhaust gas is discharged into the atmosphere. The heat contained in exhaust gas is not utilized and is wasted.

In particular, when gas turbine exhaust gas is supplied to multiple tube heating furnaces or combustion devices such as boilers, if some of them are out of operation, the amount of heat dissipated into the atmosphere without being utilized effectively (3) is It will not have much of a negative impact on the atmosphere.

The present invention was developed and completed in order to solve these conventional problems.

That is, the present invention employs a small-capacity gas turbine that supplies an amount of oxygen that is equal to or less than the amount of oxygen required for combustion during normal operation of a combustion device such as a tube heating furnace or boiler,
The present invention is characterized in that the amount of oxygen that is insufficiently supplied in the exhaust gas of the gas turbine is supplemented from a supply source other than the gas turbine exhaust gas.

According to the present invention, not only can gas turbine exhaust gas, which has conventionally been emitted into the atmosphere, be almost completely eliminated during normal operation or low-load operation of a combustion device such as a tube heating furnace or boiler, but also Equipment costs can also be reduced by using a small-capacity gas turbine.

Hereinafter, the apparatus used when carrying out the method of the present invention will be explained.

(4) ” FIG. 2 is a schematic diagram of an apparatus used when carrying out the present invention, in which the air supply duct 10 provided in the blower 11 is connected to the middle of the exhaust gas duct 4, that is, the branch duct 5.
Compared to the conventional device (see Fig. 1), the exhaust gas duct 4 is connected to a combustion device 9 such as a tube heating furnace such as a pyrolysis furnace for ethylene production or a boiler. It's new. The blower 11 is provided with an air intake duct 13 equipped with a damper 12.

On the other hand, as the gas turbine 2a, a small-capacity gas turbine is used that supplies the amount of oxygen required for combustion during normal operation of the combustion device 9, such as a tube heating furnace or boiler, or an amount less than that.

Note that other equipment that is the same as the conventional equipment is given the same reference numeral and the explanation thereof is omitted.

Thus, the gas turbine exhaust gas discharged from the gas turbine 2a is supplied to the combustion device 9 through the exhaust gas duct 4. On the other hand, the blower (5) 11 is driven, and the air taken in from the atmosphere by the blower 11 is supplied from the air supply duct 10 to the combustion device 9 via the exhaust gas duct 4, and is discharged from the gas turbine 2a. The deficiency in the amount of oxygen supplied by the exhaust gas is compensated for.

Oxygen other than gas turbine exhaust gas is not limited to atmospheric oxygen, and may be used as long as there is an available #I element. Furthermore, as shown in FIG. 3, the air taken in from the atmosphere may be preheated using exhaust heat from the combustion device 9.

That is, as shown in FIG. 3, the air passing through the air supply duct 10 is preheated by the combustion exhaust gas discharged from the combustion device 9 through the exhaust gas duct 15 using the air preheater 14. . The combustion exhaust gas from the tube heating furnace or the boiler exchanges heat with combustion air in the air preheater 14, so that the heat dissipated into the atmosphere is circulated to the combustion chamber and effectively utilized. This residual heated air is introduced into the exhaust gas duct 4 (6) from the gas turbine to compensate for the insufficient amount of oxygen for combustion in the 1ζ combustion device 9.

As described above, the present invention employs a small-capacity gas turbine that supplies the amount of oxygen required for combustion during normal operation of a combustion device such as a tube heating furnace or boiler, or an amount less than that. Since the amount of oxygen that would be insufficient in the exhaust gas (Q supply) is supplemented from a source other than gas turbine exhaust gas, conventional Not only can the gas turbine exhaust gas that was previously released be almost completely eliminated, but equipment costs can also be reduced by using a small-capacity gas turbine.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a conventional gas turbine exhaust gas utilization device, and FIGS. 2 and 3 are schematic diagrams of a gas turbine exhaust gas utilization device used when carrying out the method of the present invention. 2.2a... Gas turbine, 9... Combustion (7) Agent: Patent attorney Nobuo Ogawa - Patent attorney: Ken Noguchi Patent attorney: Kazuhiko Saishita (8) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] When supplying exhaust gas from a gas turbine as combustion air to a tube heating furnace, boiler, etc. or combustion device, the amount of oxygen required for combustion during normal operation of the tube heating furnace or boiler or other combustion device, or less. Utilization of gas turbine exhaust gas characterized in that a small-capacity gas turbine that supplies an amount of oxygen is adopted, and the amount of oxygen that is insufficiently supplied by the exhaust gas of the gas turbine is supplemented from a source other than the gas turbine exhaust gas. Method.