JPS5910972B2 - How to operate blast furnace gas purification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for increasing the recovery pressure energy of a blast furnace top pressure recovery facility.

In recent years, high-pressure operation has been adopted for blast furnaces, and in order to effectively utilize energy, top pressure recovery equipment has been installed to recover energy from these high-pressure blast furnace gases.

Incidentally, the gas generated from the blast furnace is purified and reused as fuel such as combustion gas in the hot stove, but in general, the gas purification equipment for high pressure blast furnaces equipped with top pressure recovery equipment is the Machihen Throat. A wet type dust collector (Venturi scrubber) is used.

However, in order to achieve the cleanliness required for using blast furnace gas as fuel (less than 5K/N), this method requires a very large pressure drop as described below, and as a result, the furnace top pressure decreases. Recovery rate will be low.

Therefore, the present invention aims to improve the recovery efficiency of the furnace top pressure by achieving a predetermined dust collection efficiency with as little pressure loss as possible.

Generally, if you want to improve the dust collection performance of a Venturi scrubber, the larger the pressure loss (the faster the flow velocity at the throat), the better.

On the other hand, the dust collection performance of an electrostatic precipitator becomes better as the gas pressure increases.

That is, since the charging voltage is proportional to the density of the gas, the gas pressure becomes larger than the charging voltage.

As the charging voltage increases, the dust collection force (Coulomba) increases.
becomes large (in this case, the viscosity of the gas that impedes the movement of the duct has little effect on the gas pressure.

). From the above results, when the gas pressure increases, the dust movement resistance hardly changes, but only the Coulomb force increases, so the dust collection performance improves.

Therefore, the present invention aims to increase the recovery pressure energy of the furnace top pressure recovery equipment by installing both a venturi scrubber and an electrostatic precipitator in series, and using both properly depending on the gas pressure to take advantage of the advantages of each. be.

First of all, when pressure is recovered using top pressure recovery equipment, when the pressure at the top of the furnace exceeds the pressure difference that is self-consumed to operate the top pressure recovery equipment, the equipment is operated and pressure recovery is performed. It is done.

Normally, the furnace is operated at a pressure at the top of the furnace of about 1.0K9/cdG.

Therefore, in the present invention, at the furnace top pressure (1.0 Kg/cdG or more) where pressure is recovered by operating the pressure recovery equipment, the pressure loss is small, and as mentioned above, the higher the gas pressure, the better the dust collection performance. The purpose is to collect dust using an electric precipitator, which improves dust collection.

However, in the Venturi scrubber located in the preceding process, the throat valve is fully opened and water is only sprayed to cool the gas and to roughly collect dust.

By doing this, not only the pressure loss is extremely reduced, but also the charging characteristics are stabilized by cooling, so the dust collection performance is stabilized and no unnecessary electricity flows.

Moreover, by cooling, the incoming log gas volume becomes smaller, and as a result, the electrostatic precipitator becomes more compact.

By the way, in the case of an electrostatic precipitator, as mentioned above, there is a drawback that the dust collection performance deteriorates when the gas pressure is low.

That is, in order to obtain a cleanliness of 51 IIV'Nm3 under each furnace top pressure, the residence charging time is as follows, but as the pressure decreases, the time increases significantly, and the equipment cost increases accordingly. This means that it will rise dramatically.

Therefore, in the present invention, the furnace top pressure is in a low furnace top pressure range in which the furnace top pressure is not recovered, for example, the furnace top pressure is 1. Below OKf/crlG, the Venturi scrubber reduces the necessary pressure loss and exerts its dust collection function, and works with the electrostatic precipitator located in the subsequent process to achieve the desired exit dust content, for example 5/IIg/Nm.
The aim is to achieve a score of 3 or less.

(In this case, the furnace top pressure is normally controlled by the furnace top pressure control valve 3 as shown in Fig. 2, but it can also be controlled by the throat section of the venturi scrubber A located in the previous process. Naturally, since the control valve 3 can be omitted, it is advantageous in terms of cost.

) To explain the method of the present invention as described above using a graph (see Fig. 1), for example, if the furnace top pressure recovery start pressure is 1. 0K
g/tst G is a Venturi scrubber (hereinafter v
．． We will explain how to use the wet electrostatic precipitator (hereinafter referred to as WET-EP).

WE T -E in the furnace top pressure range (furnace top pressure less than 1.0 Kg/crlG) where the furnace top pressure recovery equipment is not operated.
Since the dust collection efficiency of P becomes worse as the furnace top pressure decreases, the prefix v. v. by closing the movable damper of S and increasing the pressure loss. The purpose is to increase the dust collection efficiency of V.S and ensure overall dust collection efficiency (in this case, since the furnace top pressure recovery equipment is not in operation,
There is no problem even if the pressure drop is increased.

). On the other hand, the furnace top pressure 1. It is desirable to minimize the pressure drop required for dust collection in the range where furnace top pressure recovery equipment of 0 Kg/crlG or higher is operated, and for this reason, V. By fully opening the S movable damper and only injecting water, the V.S. S Operate to minimize pressure loss.

As part of the dust collection at this time, v. Since S has coarse dust collection performance in addition to the cooling effect of water injection, dust collection efficiency as shown in Figure 1 can be obtained, and most of the dust collection efficiency is that of WET-EP.
The desired overall dust collection efficiency can be achieved.

By the way, the equipment for carrying out the method of the present invention is as follows:
For example, the one shown in FIG. 2 a+b+c is provided.

In the device shown in FIG. 2a, the venturi scrubber A and the electrostatic precipitator B that constitute the present invention are configured as separate bodies,
Moreover, the electrostatic precipitator B has a vertical shape.

In the figure, 1 is the blast furnace, 2 is the dust catcher, and 3 is the blast furnace.
4 is a furnace top pressure control valve, and 4 is a furnace top pressure recovery equipment.

Further, 5 is a dust collecting plate, 6 is a discharge electrode, and 7 is a water level control valve.

FIG. 2b shows the same structure as that shown in FIG. 2a (Venturi scrubber A and electrostatic precipitator B are constructed separately, but electrostatic precipitator B is constructed horizontally).

The device shown in FIG. 2C has a Venturi scrubber A and an electrostatic precipitator B integrated into one body.

The results of implementing the method of the present invention using the apparatus configured as described above are shown below.

As described above, according to the method of the present invention, the operating pressure is increased by more than 20% compared to the conventional two-stage venturi one-type method (Table 1).

In addition, the installation space is small.

Further, when a commonly used two-stage venturi type is modified to the method of the present invention, it is very easy to modify it due to its structure.

That is, it is possible to install an electrostatic precipitator by making full use of the primary venturi scrubber and by making use of the mist separator part of the secondary penturi scrubber at the subsequent stage.

Furthermore, at high pressures, the throat flow velocity of the Venturi scrubber is slowed down, which greatly reduces throat wear.
It became possible to reduce the amount of material used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of the method of the present invention, and FIGS. 2 a, b, and C are explanatory diagrams of an apparatus for carrying out the method of the present invention. A: Venturi scrubber, B: Electrostatic precipitator, 1: Blast furnace, 2: Dust catcher, 3: Furnace top pressure control valve, 4
: Furnace top pressure recovery equipment, 5: Dust collection plate, 6: Discharge electrode, 7: Water level control valve.

Claims (1)

[Claims] 1 The gas generated from a blast furnace equipped with blast furnace top pressure recovery equipment is
A wet dust collection section with a round throat and an electrostatic dust collection section. In the cleaning method, in the furnace top pressure range where gas is passed to the furnace top pressure recovery equipment, the variable throat of the wet dust collection section is opened almost fully, and only water is sprinkled with almost no pressure drop to cool and cool the generated gas. Rough dust collection is performed, and generated gas is collected in an electrostatic precipitator located in the subsequent process, and dust is collected in both dust collectors only in the furnace top pressure range where gas is not passed to the furnace top pressure recovery equipment. A method for operating a blast furnace gas purification facility, characterized by achieving a desired dust collection efficiency.