JPS6048614B2 - Effective recovery method for blast furnace gas energy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for effectively recovering top gas energy of a blast furnace.

As shown in Fig. 1, for example, a conventional method of recovering the top gas energy of a blast furnace is as follows.
In the method of generating electricity by guiding the blast furnace gas that has passed through the dust catcher (from the blast furnace a) and the bench lily scrubber c to the expansion turbine e, 1. Because it is cooled, power generation is mainly based on the pressure of the blast furnace gas, and therefore the energy recovered is low.

Similarly, as shown in Fig. 2, part of the blast furnace gas that has exited the primary ventilary scrubber c is combusted in a combustor i, and the blast furnace gas that has passed through the septum valve d and the secondary ventilary scrubber f is combined with the expanded blast furnace gas. In the method of mixing the blast furnace gas before entering the turbine e, thereby raising the temperature of the blast furnace gas and increasing the recovered power, the combustor i must be specially installed between the expansion turbine e and the ventilary scrubber, and the combustion Since the calorie content of the blast furnace gas going to the gas holder g is reduced, the amount that can be burned in the combustor i is limited, and although the recovered energy is higher than the method shown in Figure 1, There were drawbacks such as a decline in the fuel value of blast furnace gas. In addition, as shown in Figure 3, the high-pressure blast furnace gas is removed before the septum valve d, and after combustion in the hot blast furnace j, a part of the exhaust gas is introduced into the blast furnace gas main pipe before entering the expansion turbine e. There is a method to increase the recovered power by mixing it with high-pressure and high-temperature gas, but like the method shown in Figure 2, it lowers the blast furnace gas calorie, and because of this, the entire amount of hot blast furnace exhaust gas cannot be used. Most of it is thrown down the chimney. Furthermore, in order to introduce gas into the 5 blast furnace gas main pipes via the hot stove j with this method, it is necessary to compensate for the pressure drop during that time, ignoring the cost of pressurizing equipment and operation. I can't afford it. In addition to recovering energy using the conventional expansion turbine for recovering furnace top pressure, the present invention makes it possible to effectively utilize the energy contained in the hot blast furnace exhaust gas, and at the same time reduce the calories of the blast furnace gas going to the gas holder. The purpose of this project is to provide an effective recovery method for blast furnace gas energy that does not cause waste. For this reason, the configuration of the present invention is such that, in blast furnace equipment equipped with an expansion turbine for top pressure recovery, an expansion turbine for exhaust gas energy recovery is installed in the combustion exhaust gas line of the hot blast furnace, and an expansion turbine for exhaust gas energy recovery is installed in the combustion exhaust gas line of the hot blast furnace. A bypass pipe and a bypass valve are auxiliary installed in the line, and the furnace top gas discharged from the blast furnace is purified at high pressure, and a part of it is sent from the high pressure section before the expansion turbine for recovering the furnace top pressure. The combustion gas is guided into the hot blast furnace with the pressure drop minimized and combusted under high pressure, and the high pressure and high temperature energy of the combustion gas is recovered by the exhaust gas energy recovery expansion turbine. The feature is that the exhaust gas is guided into the chimney after being expanded by an expansion turbine. An embodiment of the present invention will be described below with reference to FIG.

In Figure 4, 1 is the blast furnace, 2 is the dust catcher, and 3 is the blast furnace.
5 is an expansion turbine for recovering furnace top pressure, 6 is a septum valve, 7 is a blast furnace gas line for hot blast combustion, and 8 is a hot blast furnace.

That is, the hot blast furnace-combustion blast furnace gas line 7 is connected before the septum valve 6, which is the furnace top pressure control device. on the other hand,
After the exhaust gas line 9 of the hot blast stove 8, an expansion turbine 10 for exhaust gas energy recovery is installed coaxially with a generator 16. Depending on how the surplus energy is used, the air compressor 11 for combustion in the three-heat stove 8 may be installed coaxially. A bypass pipe 22 and a bypass valve 13 are auxiliary installed in the exhaust gas line 9 before the inlet of the turbine 10, and are used for starting and stopping the turbine 10, or in an emergency. The exhaust gas line exiting the turbine 10 from the previous four tons is connected to the chimney 14 after merging with the same line from the bypass valve 13 . When the air compressor 11 is installed coaxially with the turbine 10, the air compressor 11 is connected to the combustion air line 20 of the hot air stove 8 through the combustion air line 12, and switched as necessary. A valve 19 switches the supply of combustion air. Note that 15 is a gas holder, 17 is a generator, 18 is a cutoff valve, and 21 is a speed regulating valve. In the blast furnace gas energy recovery apparatus configured as shown in FIG. 4, it is of course possible to generate electricity by driving the generator 17 by the expansion turbine 5 for recovering furnace top pressure, as in the conventional case. Is there an expansion turbine 1 on the hot blast stove 8 side for exhaust gas energy recovery? Since it is provided, the following effect is obtained.

That is, when the turbine 10 is stopped, the exhaust gas after being combusted in the hot air stove 8 is discharged from the chimney 14 through the bypass valve 137 and, if necessary, through the pressure reducing valve by closing the regulating valve 21 and the shutoff valve 18. be discharged. When the turbine is driven, the bypass valve 13 is closed, the cutoff valve 18 and the speed regulating valve 21 are opened, the turbine 10 is started, and after steady rotation, power is input from the generator 16 to the power supply line to generate electricity. On the other hand, the high-pressure air for combustion in a hot stove can be made by using air from the combustion air line 20 bypassed from the compressed air line of a blast furnace blower (not shown), but as shown in the figure, exhaust gas energy Recovery turbine 1
When 0 is stopped, compressed air from the blast furnace blower is used,
When the turbine 10 enters steady operation, the switching valve 19 is switched, and the combustion air is passed through the combustion air line 12 from the combustion air compressor 11 which is directly connected to the turbine 10 and is driven at the time.
Another method is to supply compressed air. Therefore, if the arrangement is as shown in FIG. 4, after the expansion turbine 10 for exhaust gas energy recovery starts operating, the furnace top pressure recovery turbine 5 and
Two turbines will generate electricity simultaneously. Therefore, the present invention provides blast furnace equipment equipped with an expansion turbine for top pressure recovery, in which an expansion turbine for exhaust gas energy recovery is installed in the combustion exhaust gas line of a hot blast furnace, and the line of the expansion turbine for exhaust gas energy recovery is installed. A bypass pipe and a bypass valve are auxiliary installed in the blast furnace, and the furnace top gas discharged from the blast furnace is cleaned at high pressure, and a part of it is taken from the high pressure section before the expansion turbine for recovering the furnace top pressure. , the combustion gas is guided into the hot blast furnace with a minimum pressure drop and combusted under high pressure, and the high pressure and high temperature energy of the combustion gas is recovered by an expansion turbine for energy recovery, and the exhaust gas is recovered by an expansion turbine for energy recovery. Since this method guides the exhaust gas into the chimney after it expands, it has the following effects.

First, by increasing the pressure of high-temperature exhaust gas from a hot blast stove, which has traditionally been used only for preheating combustion air or preheating fuel gas, the entire amount is directly recovered as energy using an expansion turbine. The energy of the hot blast furnace exhaust gas can be used more effectively. Second,
Since it can be operated in conjunction with a conventional top pressure recovery turbine, it is possible to recover more energy than conventionally recovered by the top pressure recovery turbine alone. Thirdly, the blast furnace exhaust gas that is combusted in the hot blast furnace and used for power generation etc. is discharged from the chimney in the same way as conventional hot blast furnace exhaust gas is handled, and therefore it is not mixed with the blast furnace gas that is not combusted, so it is stored in the gas holder. There is no need to reduce the calorie content of the blast furnace gas, and therefore there is no need to increase the amount of expensive gas such as coke oven gas used for calorie enrichment. Fourth, because the turbine outlet is directly connected to the chimney, the outlet pressure of the expansion turbine for exhaust gas energy recovery can be lower than that of a conventional furnace top pressure recovery turbine, so more output can be extracted. Moreover, even if the outlet pressure is lowered, the inlet temperature is high, so there is no need to worry about freezing of the outlet gas.

[Brief explanation of the drawings] Fig. 1 is an explanatory diagram of an example of a conventional blast furnace gas energy recovery method, Fig. 2 is another explanatory diagram, Fig. 3 is another explanatory diagram, and Fig. 4 is another explanatory diagram. 1 is an explanatory diagram of an embodiment of the present invention. 1...Blast furnace, 2...Dust catcher, 3...
Primary bench lily scrubber, 4...Secondary bench lily scrubber, 5...Furnace top pressure recovery expansion turbine, 6
...Septum valve, 7.Blast furnace gas line for hot blast furnace combustion, 8..Hot blast furnace, 9..Exhaust gas line, 10.
...Expansion turbine for exhaust gas energy recovery, 11...
・Combustion air compressor, 12... Combustion air line, 1
3... Bypass valve, 14... Chimney, 15... Gas holder, 16, 17... Generator, 18... Shutoff valve,
19...Switching valve, 20...Combustion air line, 21
...Governing valve, 22...Bypass pipe.

Claims (1)

[Claims] 1 In blast furnace equipment equipped with an expansion turbine for top pressure recovery, an expansion turbine for exhaust gas energy recovery is installed in the flue gas win of the hot blast furnace, and an auxiliary bypass pipe is installed in the line of the expansion turbine for exhaust gas energy recovery. A state in which a bypass valve is provided, and the top gas discharged from the blast furnace is purified while remaining at high pressure, and a portion of it is taken from the high pressure section in front of the expansion turbine for recovering top pressure, thereby minimizing the pressure drop. The combustion gas is guided into the hot stove and burned under high pressure, and the high pressure and high temperature energy of the combustion gas is recovered by the expansion turbine for exhaust gas energy recovery, and after being expanded by the expansion turbine for exhaust gas energy recovery. An effective method for recovering blast furnace gas energy, which is characterized by guiding exhaust gas into the chimney.