JPH062888B2 - Blast furnace gas recovery device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a blast furnace gas recovery apparatus, and more particularly to a blast furnace gas recovery apparatus provided with a cleaning device capable of removing a corrosive component of a blast furnace gas with a necessary minimum amount of cleaning water. .

[Conventional technology]

FIG. 1 is a schematic process diagram showing a dust removal process of blast furnace gas discharged from the blast furnace. The blast furnace gas discharged from the blast furnace 2 is roughly dust-removed by a dust remover 4, and is further cleaned by a wet dust remover including a venturi scrubber 6, a mist separator 8, a butterfly valve 10 and the like surrounded by a dotted line, and a part of the exhaust gas turbine 12 To recover the pressure energy and the rest is sent to the blast furnace gas main via the septum valve 14.

In recent years, for the purpose of increasing the amount of recovered power, the dust removal method has been switched from the wet type to the dry type as disclosed in Japanese Patent Publication No. 46-3842. That is, as shown in FIG. 1, instead of the conventional venturi scrubber 6, a bag filter 16
It has come to be supplied to the exhaust gas turbine 12 via the dry type dust removing device as described above.

By switching from the wet type to the dry type, the corrosive components contained in the blast furnace gas have been removed by the wet type, but are not removed by the dry type and remain, thus causing a problem of corroding the blast furnace gas piping system.

[Problems to be solved by the invention]

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a blast furnace gas recovery apparatus having a blast furnace gas cleaning apparatus capable of efficiently removing a corrosive component in a blast furnace gas.

[Means and Actions for Solving Problems]

The gist of the present invention is as follows. That is, in a blast furnace gas recovery device having a dust remover, a dry dust remover, and an exhaust gas turbine, a gas cleaning tower is provided at a stage subsequent to the exhaust gas turbine, and a corrosive component concentration measuring device is provided at an inlet or an outlet of the gas cleaning tower. It is a blast furnace gas recovery device characterized by being provided.

The details of the present invention will be described with reference to the embodiment shown in FIG. A gas cleaning tower 18 is provided downstream of the exhaust gas turbine 12 and the septum valve 14, and subsequently, an outlet gas pipe 20 and a blast furnace gas main pipe 22 are provided. The outlet pipe 20 is provided with a corrosive component concentration measuring device 24 for blast furnace gas, and a computing device 26 for inputting a measurement signal. Further, a pump 28 for inputting an output signal from the calculator 26, a water supply pipe 30 to the gas cleaning tower 18, and a spray 32. A drain pipe 34 from the gas cleaning tower 18 is provided. The pump 28 is a variable speed type or a variable blade type and can adjust the amount of water.

The amount of cleaning water in the gas cleaning tower 18 may be increased or decreased according to the amount of passing gas as disclosed in JP-A-53-13242, but this method is sufficient because the corrosive components in the blast furnace gas fluctuate. Since it is not possible to cope with this, the present invention also takes this point into consideration.

Next, the cleaning method of the present invention in the above apparatus will be described.
Since the composition of blast furnace gas fluctuates, a corrosive constituent concentration measuring device
Measure the corrosive components, pH, etc. of the drain of blast furnace gas. The measurement position is on the outlet side of the gas cleaning tower 18 in FIG. 2, but may be on the inlet side in some cases. However, since the corrosive component is high on the inlet side and the corrosive component concentration measuring device 24 is corroded, the outlet side is preferable.

The measured value from the corrosive component concentration measuring device 24 is input to the calculator 26, and the calculator 26 calculates the required pump control signal from the deviation from the preset value input in advance. The calculation may be either proportional calculation or PID calculation.

The pump control signal is input to the pump 28, and the pump 28 cleans with the minimum amount of cleaning water at which the corrosive component concentration in the blast furnace gas reaches a set value. Since the corrosive component in the blast furnace gas is surely removed by the device of the present invention, the corrosion of the blast furnace gas main pipe can be prevented and the power cost of the gas cleaning tower 18 can be reduced.

〔Example〕

The blast furnace gas of 600,000 Nm ³ / hr passed through the exhaust gas turbine was recovered using the cleaning apparatus of the present invention shown in FIG. The inner diameter of the gas cleaning tower 18 is 10 m.

The pH value of the drain of the blast furnace gas in the outlet gas pipe 20 of the gas cleaning tower was preset to 5.5, and the pH value at that location was measured by a corrosive component concentration measuring instrument. This measured value is input to the calculator, which outputs a pump control signal to the pump 28 to increase the amount of wash water when the pH measured value is less than 5.5, and outputs a signal to decrease the amount of wash water when it exceeds 5.5. After that, the amount of washing water for the pump 28 was controlled.

During the cleaning by the device of the present invention, the HCl of the drain in the blast furnace gas is introduced at the inlet and the outlet of the gas cleaning tower 18 at intervals of 30 minutes.
Was analyzed and the results are shown in FIGS. 3 and 4.

In Fig. 3, the HCl concentration at the inlet fluctuates greatly from 4 to 25 ppm, whereas in Fig. 4, the HCl concentration at the outlet is a constant value of about 2 ppm.
It can be seen that the present invention reliably removes the corrosive components. Therefore, it was possible to prevent corrosion of the piping and equipment of the blast furnace gas supply system in the latter stage.

On the other hand, changes in the amount of cleaning water in the gas cleaning tower during cleaning are shown in FIG. 5, and it can be seen that the amount of cleaning water changes following the changes in the inlet HCl concentration in FIG. Further, since the concentration is constant in FIG. 4, it is clear that the amount of water is the minimum required. Compared with the case where the amount of water is fixed at 600 T / hr, it is about 200 which corresponds to the shaded area in Fig. 5.
This means that the power cost for the water volume of T / hr has been reduced.

〔The invention's effect〕

As is apparent from the above-mentioned embodiment, the present invention provides a gas cleaning tower at the latter stage of the exhaust gas turbine and a corrosive component concentration measuring instrument at the inlet or outlet of the gas cleaning tower, and controls the amount of cleaning water according to the corrosive component concentration to I was able to increase the effect.

(B) Corrosion components in the blast furnace gas were reliably removed to prevent corrosion of the blast furnace gas piping system.

(B) The amount of washing water in the gas washing tower was reduced to the necessary minimum amount and the electricity cost was reduced.

[Brief description of drawings]

FIG. 1 is a schematic process diagram showing a dust removal process of blast furnace gas, FIG. 2 is a sectional view showing a cleaning apparatus according to an embodiment of the present invention, and FIG. 3 is HCl in a blast furnace gas at a gas cleaning tower inlet in an embodiment of the present invention. FIG. 4 is a diagram showing changes in concentration, FIG. 4 is a diagram showing changes in HCl concentration in the blast furnace gas at the outlet of the gas washing tower in the embodiment of the present invention, and FIG. 5 is an amount of washing water in the gas washing tower in the embodiment of the present invention. It is a diagram showing the change of. 2 ... Blast furnace, 4 ... Dust remover 12 ... Exhaust gas turbine, 16 ... Bag filter 18 ... Gas cleaning tower, 24 ... Corrosion component concentration measuring instrument 26 ... Computing device

Claims (1)

[Claims] 1. A blast furnace gas recovery apparatus comprising a dust remover, a dry dust remover, and an exhaust gas turbine, wherein a gas cleaning tower is provided at a stage subsequent to the exhaust gas turbine, and a concentration of a corrosive component at an inlet or an outlet of the gas cleaning tower. A blast furnace gas recovery device, which is provided with a measuring device.