JPS63117126A - Blast furnace gas fired gas turbine plant - Google Patents

Abstract

PURPOSE:To effectively utilize the sensible heat of exhaust gas by connecting the exhaust gas pipe of a gas turbine through directional control valves to the combustion air supply pipe of an air-heating furnace and a hot blast supply pipe to a blast furnace respectively. CONSTITUTION:The exhaust gas pipe 14 of a gas turbine 6 is connected through directional control valves 21, 21a to the combustion air supply pipe 18 of an air-beating furnace 25 and a hot blast supply pipe 17 to a blast furnace respectively. When the exhaust gas of said gas turbine 6 can not be supplied as the combustion air for the air-heating furnace 25, it is mixed into the hot blast to the blast furnace by opening said directional control valve 21a for its use. Thus the sensible heat of the exhaust gas can be effectively utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blast furnace gas-fired gas turbine plant.

[Conventional technology]

Exhaust gas from gas turbines that use conventional blast furnace gas is directly emitted into the atmosphere. However, since the oil crisis, energy-saving measures have progressed dramatically, and combined-type gas turbine power generation has been developed and is now commonly used. As shown in Figure 2, this is a system in which exhaust gas from a gas turbine 6 is guided to a boiler 7 to generate steam, the steam drives the steam turbine 2, and the sensible heat of the exhaust gas is recovered as electricity in a steam cycle using a waste heat boiler. It is.

Techniques related to this combined system have already been put into practical use, such as in Japanese Patent Laid-Open Nos. 58-57027 and 58-57012. In order to improve the heat recovery efficiency of this technology, there is a case where a fluidized bed boiler is used as an exhaust heat boiler to improve thermal efficiency, as disclosed in Japanese Patent Laid-Open No. 56-52512.

However, all of these technologies utilize the heat of exhaust gas and recover it as steam, which is recovered using electricity as a steam cycle, and their thermal efficiency is extremely low.

[Problem that the invention seeks to solve]

Conventional technology for blast furnace gas-fired gas turbine plants has a problem of poor thermal efficiency because heat is recovered as a steam cycle.

The present invention aims to solve the above-mentioned problems and proposes a blast furnace gas-fired gas turbine plant that effectively utilizes the sensible heat of combustion exhaust gas of the turbine to save energy.

[Means for solving problems]

The present invention solves the above-mentioned problems and is applied to a blast furnace gas-fired gas turbine plant, and employs the following technical means. That is, the exhaust gas piping of the gas turbine was connected to the combustion air supply piping of the hot blast furnace combustion chamber and the hot air supply piping to the blast furnace, respectively, via switching valves.

[Effect]

The exhaust gas of a blast furnace gas-fired gas turbine is a high-temperature exhaust gas of around 500° C., and the exhaust gas tonne contains about 15% of unburned oxygen.

A blast furnace hot blast furnace burns blast furnace or coke oven gas, and uses the heat storage method to preheat the combustion air of the hot blast furnace using the exhaust gas from that time and a heat exchanger.

The present invention is characterized in that by using exhaust gas from a gas turbine as combustion air for a hot stove, the sensible heat of the exhaust gas can be recovered as is, and unburned oxygen is also used as combustion air. It is something to do.

If the amount of oxygen is insufficient, appropriate measures such as replenishing air or enriching oxygen gas may be taken.

The basic process diagram of the present invention is shown in FIG.
are connected to the combustion air supply pipe 18 of the hot blast furnace 25 and the hot air supply pipe 17 of the blast furnace 19, respectively.

The high-temperature, unburned exhaust gas of the gas turbine 6 is sent to the combustion chamber 20 of the hot air stove 25 via the gas turbine exhaust gas pipe 14 and the combustion air supply pipe 18, and mixed with the fuel gas sent from the fuel gas supply pipe 15. and burn it. In this case, the combustion air temperature in the conventional example was 150°C, but the combustion air temperature in the present invention is a high temperature of about 500°C, although the oxygen content is slightly thinner, so combustion is extremely efficient.
The sensible heat burns the fuel, and the sensible heat of the exhaust gas is brought into the heat storage chamber 13. Therefore, by using a mixed gas of coke oven gas and blast furnace gas, the fuel gas is reduced to 140.00 ONm3/). (from 120.OO
It was possible to save on ONm3/H.

Also, the combustion air fan 26 (indicated by the dotted line) could be shut down.

The exhaust gas from the gas turbine at this time was 250°00ONm.
Since 3/H with an oxygen content of 12% was used as the entire combustion air, the conventional combustion air amount was not required, and the power cost of the combustion air fan 26 could be reduced accordingly.

In addition, in the present invention, when the exhaust gas of the turbine cannot be supplied as combustion air due to a problem with the equipment of the hot blast stove 25, or when there is a surplus of exhaust gas due to the operating status of the hot blast stove 25, the switching valve 21a is opened and supplied to the hot air supply pipe 17 for blowing blast furnace air via a booster compressor 23, so that it can be mixed with high temperature hot air of usually 1000 to 1200°C and supplied. In this case, the increase in power cost for installing the booster 23 is as follows:
There is no problem because it is combined with the reduction in power costs in step 4.

〔Example〕

Table 1 shows a comparison of operation data between the embodiment of the present invention and the conventional example. As seen from the results, the gas turbine plant efficiency has increased from 45% to 30% due to the loss of steam turbine output.
%, but the fuel gas in the hot stove was 20.00ONm.
3/H1! I was able to make an appointment. In order to compare this on the same basis, if we were to supply this to another power generation plant and convert it into electricity, it would be possible to generate 12,0OOKW of electricity, so the total output of the gas turbine and steam turbine would be 40.0OOKW.
For KW, the above 12,0OOKW is added to the current gas turbine output of 30.0OOKW, and the difference is 2,0OOKW.
This results in an increase in output, and overall increases energy usage efficiency. Furthermore, if you take into account the power savings of 300 kW from the combustion air fan, the effect becomes even greater.

〔Effect of the invention〕

The blast furnace gas-fired gas turbine plant of the present invention has the following excellent effects on improving the energy supply and demand efficiency of a steelworks.

Since the exhaust gas of the gas turbine at around 0,500° C. is directly supplied as combustion air to the hot blast stove, it is possible to reduce the fuel input to the hot blast stove and the power cost of the conventional combustion air fan. Therefore, the sensible heat of the combustion exhaust gas of the turbine can be effectively utilized without installing a new steam turbine or boiler.

■If the turbine exhaust gas cannot be supplied as combustion air due to a problem with the hot blast furnace equipment, or if there is surplus exhaust gas due to the operating status of the hot blast furnace, it will be mixed with the hot air for blowing the blast furnace and supplied. Since a switching valve is provided so that the exhaust gas sensible heat of the turbine can be effectively recovered and used.

[Brief explanation of the drawing]

FIG. 1 shows a basic process diagram of the present invention, and FIG. 2 shows a general process diagram of a conventional combined system. 1... Gas compressor 2... Steam turbine 3...
- Generator (gas turbine) 4...Air compressor 5...Combustor 6...Gas turbine 7...Exhaust heat recovery boiler 8...Chimney
11... Generator (steam turbine) 12... Steam inlet valve 13... Regenerator chamber 14... Gas turbine exhaust gas piping 15... Fuel gas supply piping 16... Blowing air supply piping

Claims (1)

[Scope of Claims] 1. In a blast furnace gas-fired gas turbine plant, the exhaust gas pipe of the gas turbine is connected to the combustion air supply pipe of the hot blast furnace combustion chamber and the hot air supply pipe to the blast furnace, respectively, via a switching valve. A blast furnace gas-fired gas turbine plant featuring: