JPH09209009A - Method for preventing damage of recovering turbine in furnace top gas pressure recovering power generation and continuous monitoring device for dust concentration and mist concentration in wet gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage of a recovering turbine at the time of executing the furnace top gas pressure recovering power generation by newly providing a method for measuring concns. of mist and dust in wet gas containing the mist and the dust. SOLUTION: At the time of introducing the wet gas containing the remaining dust and the mist obtd. by removing the dust in the furnace top gas by a venturi scrubber into the furnace top gas pressure recovering turbine, in the remaining dust recovering process wherein a part of the wet gas is sampled at this side of the turbine and the sampled gas is passed through a drain pot 9 to recover the mist, then passed through a filter 10, the mist concn. is detected from the mist quantity and the gas flow rate per unit time stored in a drain pot 9, and the dust concn. is detected from the gas differential pressure at the inlet side and the outlet side of the filter 10 and the gas flow rate. Thus when at least one side of these mist concn. and the dust concn. is abnormally increased, the wet gas is allowed to flow into a bypass tube detouring the recording turbine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing damage to a recovery turbine in blast furnace top pressure recovery power generation and a continuous monitoring apparatus for dust and mist concentrations in blast furnace wet gas used in this method.

[0002]

2. Description of the Related Art Gas generated in a blast furnace is used as a fuel for hot blast stoves, coke ovens, heating furnaces, boilers, etc., and is passed through a recovery turbine especially for the purpose of recovering the furnace top pressure. So-called blast furnace top pressure recovery power generation is also performed. In any case, it is necessary to remove a large amount of dust contained in the gas before use.
Dust was removed by a dry method or a wet method.

That is, in the dry type dust removal, as shown in FIG. 1, the gas from the blast furnace 1 is first passed through a dust remover 2 to separate and settle coarse particles of dust, and then to a bag filter 3 to remove fine dust. Remove it. And the dust remover 2
Also, the dry gas from which dust has been removed by the bag filter 3 is passed through the recovery turbine 4 to be used for furnace top pressure recovery power generation. Reference numeral 5 is a bypass pipe for bypassing the recovery turbine 4 and passing gas when the recovery turbine 4 is inspected or when the furnace top pressure changes abnormally.

On the other hand, in the wet dust removal, as shown in FIG. 2, the gas from the blast furnace 1 is first passed through a dust remover 2 to separate and set coarse particles of dust and then to a venturi scrubber 6 to remove fine dust. Since the venturi scrubber 6 has excellent dust removing ability and gas with high cleanliness is obtained, wet dust removing is often used.
Then, the wet gas from which dust has been removed by the venturi scrubber 6 is passed through the recovery turbine 4 to be used for furnace top pressure recovery power generation in the same manner as in the dry system.

By the way, since it is impossible to completely remove dust by the dust remover 2 and the bag filter 3 or the venturi scrubber 6, it is natural that residual dust is contained in the dry or wet gas. For example, if the gas whose residual dust concentration is abnormally increased due to the filter clogging of the bag filter 3 or the inner cylinder of the venturi scrubber 6 is passed through the recovery turbine 4 as it is,
It was a problem that a large amount of dust damages the turbine.

[0006]

To solve this problem, in principle, the property of the gas is constantly monitored, and when the above-mentioned abnormality occurs, the bypass pipe is used to bypass the bypass line. It is possible to prevent the introduction of gas into the recovery turbine by flowing the gas into the recovery turbine.

In the case of the dry gas, the dust concentration in the gas can be easily measured by using, for example, a contact charging type measuring instrument. However,
In wet gas, mist is inevitably mixed when passing through the venturi scrubber 6. Therefore, in a contact charging type measuring instrument used in dry gas, when a wet gas containing mist is targeted, an electric current proportional to dust concentration is obtained. No value is output, so
Cannot be applied. Moreover, in the case of wet gas,
Because of the inclusion of mist, the concentration of this mist also needs to be monitored. This is because a large amount of mist as well as a large amount of dust damages the recovery turbine. Therefore, in spite of the fact that it is necessary to measure the concentration of mist and dust specific to wet gas, no suitable measuring method has been known so far.

Therefore, in the present invention, by newly providing a method for measuring the concentration of mist and dust in a wet gas containing mist and dust, the cleanliness is maintained when performing blast furnace top pressure recovery power generation. It is an object of the present invention to propose a method for preventing damage to the recovery turbine by selectively introducing only wet gas into the recovery turbine. Another object of the invention is also advantageously adapted to the above method,
It is intended to provide a continuous monitoring device for dust and mist concentration in blast furnace wet gas.

[0009]

The present invention introduces a wet gas containing residual dust and mist obtained by removing dust in a furnace top gas with a venturi scrubber into a furnace top pressure recovery turbine. A part of the wet gas is sampled before the recovery turbine, and the sampling gas is first passed through a drain pot to recover mist and then passed through a filter to recover residual dust. Detects the mist concentration from the mist amount and gas flow rate per hour, and detects the dust concentration from the gas pressure difference and gas flow rate between the inlet side and the outlet side of the filter, and at least one of these mist concentration and dust concentration Top pressure of blast furnace characterized by flowing wet gas into bypass pipe bypassing recovery turbine when abnormal increase It is damage prevention method of recovery turbine in the recovery power.

Further, in the above method, a drain line for removing mist in the wet gas and a filter for removing dust are arranged in a sampling line for introducing a wet gas containing dust and mist, and the drain pot is provided with the drain pot. A detector for the amount of accumulated mist, a detector for the gas pressure difference between the inlet side and the outlet side of the filter, and a gas flow meter are installed, and based on the detection values from each detector and flow meter, the mist concentration and dust are detected. Calculate the concentration,
Further, it is possible to use a continuous monitoring device for dust and mist concentration in the wet gas, which is provided with a calculator for notifying an abnormal increase in mist concentration and dust concentration.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION According to the method of the present invention, in the furnace top pressure recovery power generation using the wet gas shown in FIG. 2, in the wet gas sampled from the gas inlet side of the recovery turbine 4 as shown in FIG. This is achieved by providing a continuous monitoring device 7 for the dust and mist concentrations of

That is, the continuous monitoring device 7 collects wet gas from the inlet side of the recovery turbine 4 as shown in FIG.
A drain pot 9 for removing mist in the wet gas, a filter 10 for removing the dust, and a gas flow meter 11 are arranged in sequence from upstream to downstream in the sampling line 8 which is finally returned to the outlet side of the recovery turbine 4. In addition, a level meter 12 and a solenoid valve 13, which are detectors for the amount of mist accumulated in the drain pot 9, and a gas differential pressure detector 14 on the inlet side and the outlet side of the filter 10 are provided.

In the continuous monitoring device 7, the collected wet gas is first passed through the drain pot 9 to recover most of the mist. Here, when the level meter 12 detects that the amount of mist collected in the drain pot 9 reaches a predetermined amount, the solenoid valve 13 is opened to discharge the drain collection tank 15. Then, the calculator 16 calculates the mist concentration based on the time until a predetermined amount of mist is accumulated in the drain pot 9 and the gas flow rate value measured by the flow meter 11.

Next, the gas from which mist has been removed is passed through the filter 10, and the differential pressure of the gas between the inlet side and the outlet side of the filter is detected by the differential pressure detector 14, and this detected value and the flow meter
Based on the gas flow rate value measured in 11 and in the calculator 16,
Calculate the dust concentration according to the following equation (1). ΔP = φ ・ k ・ Q ² ---- (1) where ΔP: Gas differential pressure φ: Filter resistance coefficient k: Constant Q: Gas flow rate

Here, as shown in FIG. 5, the filter resistance coefficient φ is constant regardless of the amount of dust in the initial stage when dust is not collected in the filter, but is collected in the filter thereafter. It increases in proportion to the amount (concentration) of dust. In addition, the gas differential pressure ΔP also increases in proportion to the concentration of dust collected by the filter. Therefore,
The relational expression (2) holds. d (ΔP) / dt = (dφ / dt) · k · Q ² ---- (2) Then, by rearranging the above equation (2), the following equation (3) can be derived. dφ / dt = d (ΔP) / dt ・ (k ・ Q ² ) ^-1 ---- (3)

If the dust concentration in the wet gas is a constant value, the filter resistance coefficient increases with a constant slope as shown by the solid line in FIG. 6, but the dust in the wet gas is abnormal due to an abnormality such as a venturi scrubber. As the concentration increases, for example, the filter resistance coefficient has a steeply increasing slope as shown by the dotted line in FIG. If this is shown by the left side of the above equation (3), that is, the time differential value of the filter resistance coefficient, the increase of the filter resistance coefficient is as shown in FIG. 7. For example, when the normal dust concentration changes, a When the dust concentration doubles, the time differential value of the filter resistance coefficient becomes the b value. Therefore, by using the time differential value of the filter resistance coefficient as an index, it is possible to grasp the fluctuation of the dust concentration. This calculation is also performed by the calculator 16.

When the mist concentration and dust concentration detected according to the above procedure increase abnormally, for example, the information from the calculator 16 is displayed as a signal, and a plurality of on-off valves provided in the gas path are displayed according to the signal information. The operation is stopped, the introduction of the gas to the recovery turbine 4 is stopped, the wet gas is introduced to the bypass pipe 5, and the recovery turbine 4 is bypassed to prevent the recovery turbine from being damaged.

[0018]

According to the present invention, the concentration of mist and dust in a wet gas containing mist and dust is detected, and an abnormal increase in the concentration is reliably detected. Since it is possible to avoid introducing high-grade gas to the recovery turbine side,
It is possible to significantly extend the life and inspection period of the recovery turbine.

[Brief description of drawings]

FIG. 1 is a schematic view showing dry type dust removal.

FIG. 2 is a schematic diagram showing wet dust removal.

FIG. 3 is an explanatory diagram showing a path of a wet gas equipped with the continuous monitoring device of the present invention.

FIG. 4 is an explanatory diagram showing a continuous monitoring device of the present invention.

FIG. 5 is a diagram showing a relationship between a dust amount and a filter resistance coefficient.

FIG. 6 is a diagram showing an increasing slope of a filter resistance coefficient.

FIG. 7 is a diagram showing a time differential value of a filter resistance coefficient.

[Explanation of symbols]

 1 blast furnace 2 dust remover 3 bag filter 4 recovery turbine 5 bypass pipe 6 venturi scrubber 7 continuous monitoring device 8 sampling line 9 drain pot 10 filter 11 flow meter 12 level meter 13 solenoid valve 14 differential pressure detector 15 drain recovery tank 16 calculator 17 Drain collection tank

Claims (2)

[Claims] 1. A wet gas containing residual dust and mist, obtained by removing dust in the furnace top gas with a venturi scrubber, is introduced into a furnace top pressure recovery turbine to recover a part of the wet gas. Sampling before the turbine, this sampling gas is first passed through a drain pot to collect mist, and then passed through a filter to collect residual dust, and the amount of mist and gas flow rate per unit time accumulated in the drain pot. The mist concentration is detected from the filter, and the dust concentration is detected from the gas pressure difference and gas flow rate between the inlet side and the outlet side of the filter, and when at least one of these mist concentration and dust concentration increases abnormally, the recovery turbine A collector for blast furnace top pressure recovery power generation characterized by flowing wet gas through a bypass pipe that bypasses the How to prevent bottle damage. 2. A drain line for removing mist in the wet gas and a filter for removing dust are arranged in a sampling line for introducing a wet gas containing dust and mist, and a detector for detecting the amount of mist accumulated in the drain pot. , A gas pressure difference detector on the inlet side and outlet side of the filter and a gas flow meter are installed respectively, and the mist concentration and dust concentration are calculated based on the detection values from each detector and the flow meter, and A continuous monitoring device for dust and mist concentrations in wet gas, which is equipped with a computing unit that notifies an abnormal increase in mist concentration and dust concentration.