JPH0119051B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides equipment for recovering the temperature/pressure energy possessed by the gas by an expansion gas turbine after passing generated gas discharged from the top of a blast furnace through a dry gas cleaning device. Depending on the furnace conditions, the temperature of the generated gas in a blast furnace can sometimes reach an abnormally high temperature for a short period of time, and this paper relates to a method for controlling and stabilizing the gas temperature before entering the gas turbine.

The temperature of the gas generated in a blast furnace is usually about 100 to 200°C, but it can exceed 800°C in a short period of time. In contrast, conventionally, the generated gas is cooled and purified using a wet gas purification device using water, and the gas temperature after gas purification is always in a saturated state of approximately 50°C. Therefore, gas sensible heat was not subject to recovery.

In recent years, consideration has been given to using a dry type gas purifier instead of the conventional wet type gas purifier to prevent the temperature of the gas from decreasing, and to recover the temperature/pressure energy possessed by the gas as electric power using an expansion gas turbine.
However, unless appropriate measures are taken against abnormal temperature fluctuations in the generated gas, equipment may be damaged and energy cannot be recovered stably.

Therefore, in case of abnormally high temperature of generated gas, the temperature of the gas at the top of the furnace before energy recovery is detected and water is injected at the top of the furnace as a countermeasure after the fact, and the gas temperature is lowered by the heat of vaporization of the water. We are trying to protect each device. But if you do it like this,
When gas containing moisture comes into contact with low-temperature piping on the downstream side, it is cooled and creates drainage, which causes dust to stick inside the pipes.Furthermore, depending on the type and type of dry gas purifier, it may become saturated. There are some things that are not suitable for processing close gases. That is, during gas cleaning, the gas reaches the dew point and wets the dust collection element, making it impossible to remove the collected dust, resulting in a significant reduction in the dust collection function.

The present invention has been developed in view of these points, and is a method for controlling the temperature of the generated gas using a heat storage device and a water injection device when energy is recovered by a gas turbine from the generated gas discharged from the top of a blast furnace. In the method, after the generated gas from the top of the furnace is brought into contact with a material having a large heat capacity of the heat storage device, water injection is performed based on the result of predictive calculation based on the heat capacity characteristics of the heat storage device and the temperature change of the generated gas before contact. The present invention relates to a method for controlling the temperature of generated gas, characterized in that the temperature of the gas guided to the gas turbine is controlled by injecting water into the generated gas using a device.

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

As shown in FIG. 1, the gas generated in the blast furnace main body 1 is guided via the furnace top gas 2 to a dry type gas purifying heat storage device 3 such as a gravel bed type, where the generated gas After removing the dust contained therein, the clean gas pipe 4 guides the gas through a gas turbine 6 arranged in parallel with a septum valve 5 to a gas holder 7, and delivers it to a user (not shown) as fuel gas, etc. I'm trying to use it.

Furthermore, in order to cope with the short-term abnormal temperature rise of the generated gas, a furnace top temperature detection end 8 is provided in the blast furnace top gas pipe 2 to detect the abnormal temperature rise of the gas, and the signal is sent via the controller 9. Cooling water is sent to the electric valve 10, and is injected from a water spray nozzle 11 provided in the clean gas pipe 4 on the upstream side of the gas turbine 6, thereby preventing an abnormal rise in temperature of the clean gas.

Normally, the temperature of the generated gas discharged from the blast furnace body 1 is maintained at a substantially constant temperature between 100 and 200 degrees Celsius, but if gas is blown inside the blast furnace, High-temperature gas exceeding 800℃ may flow. In such a case, gravel (sand-like substance) with a large heat capacity as a filter filled in the gas purifying heat storage device 3 is heated by the high temperature gas, and once absorbs the thermal energy of the gas and stores the heat. During this process, the gas is cooled. Then, when the generated gas temperature returns to the normal level, the heated gravel has a higher temperature, so the gas is heated until the temperatures are balanced.

Therefore, at the outlet of the gas purification heat storage device 3, the temperature change at the inlet section is as shown by the solid line A in FIG. Moreover, temperature changes appear with a slight delay. That is, a change in the clean gas temperature appears after a time delay after the start of the change in the furnace top gas temperature. The degree of equalization of the clean gas temperature and the degree of delay in the change time are determined by the heat storage capacity and heat transfer characteristics of the gravel in the gas clean heat storage device 3. Therefore, the change in the inlet gas temperature of the gas clean heat storage device 3 Based on the state, changes in the outlet gas temperature can be predicted to some extent by theoretical calculations.

Therefore, by detecting the furnace top gas temperature at the furnace top temperature detection end 8 and performing calculation and control using the controller 9, the amount of water blown from the water spray nozzle 11 is automatically adjusted according to the temperature change of the clean gas. Thus, the temperature of the gas entering the gas turbine 6 can be kept substantially constant, thus ensuring safe operation of the gas turbine.

It should be noted that the present invention is not limited only to the above-mentioned embodiments, and can function in the same way even if a heat storage device is provided separately from the gas purifying device.
The temperature at the top of the furnace may be directly detected by the furnace top temperature detection end, various types of gravel may be used, and various other changes may be made without departing from the gist of the present invention. , etc., of course.

According to the above-described method for controlling the generated gas temperature of the present invention, the following excellent effects can be achieved.

(i) It is possible to stably recover the thermal energy possessed by the generated gas discharged from the blast furnace.

(ii) Since there is a time lag in temperature changes, the time in between is used to respond, so there is no response delay and overcooling can be prevented.

(iii) Since the cooling water is injected downstream of the gas purification heat storage device, there is no concern that it will affect the dust collection efficiency of the gas purification heat storage device, and it is possible to prevent dust from sticking inside the pipes due to drain.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus for implementing the method of the present invention, and FIG. 2 is a diagram showing temperature changes of generated gas. 1 is a blast furnace main body, 2 is a furnace top gas pipe, 3 is a gas clean heat storage device, 4 is a clean gas pipe, 6 is a gas turbine,
8 is a furnace top temperature detection end, 9 is a controller, and 11 is a water nozzle.

Claims (1)

[Claims] 1 In a method of controlling the temperature of the generated gas using a heat storage device and a water injection device when energy is recovered from the generated gas discharged from the top of a blast furnace using a gas turbine, the generated gas from the top of the blast furnace is After contacting with a substance with a large heat capacity, a water injection device injects water into the generated gas based on the result of predictive calculation based on the heat capacity characteristics of the heat storage device and the temperature change of the generated gas before contact, and the gas turbine is injected with water. A method for controlling the temperature of generated gas, characterized by controlling the temperature of the gas being introduced.