JPS61118156A - Wet dust collector - Google Patents

Abstract

PURPOSE:To perform the dust collecting of high performance in low pressure drop and to maintain the dust collection performance for a long period by making the intervals of dust collecting polar plates of a vertical wet segment type electrical dust collecting parts the specified value and above. CONSTITUTION:A vertical wet segment type preliminary charge part 10, a venturi dust collecting part 20 and a vertical wet segment type electrical dust collecting part 30 are successively provided from the upstream of gas stream to the lowerstream. The intervals of dust collecting polar plates of the electrical dust collecting part 30 are made to >=450mm. By this method, high-performance dust collection is performed at low pressure loss for the dust-laden gas of >=1.0kg/cm<2> (gage pressure) gas pressure and the dust collection performance is maintained for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a wet dust collector, and particularly to a wet dust collector.
The present invention relates to a wet type dust collector for dust-containing gas having a gas pressure (gauge pressure) of tpb2 or higher.

(Prior art) A wet precipitator with a variable throat (
A venturi scrubber (hereinafter referred to as a venturi scrubber) is used. This method has excellent business performance, but the cleanliness required to use blast furnace gas as fuel, for example 5 m
g/Nm'' or less required a large pressure drop.

For example, in Japanese Patent Publication No. 59-6886, there is a proposal to improve dust collection efficiency by combining a venturi scrubber (hereinafter referred to as ■s) and a rotating P-type electrostatic collector section (hereinafter referred to as We). However, because ■s is operated with a low pressure drop, there is a large amount of gas and dust at the printing inlet (this has been pointed out to be the main cause of deterioration over time).

(Problems to be Solved by the Invention) The present invention provides a compact wet-type dust collector that performs high performance collection with low pressure loss and maintains dust collection performance over a long period of time.

(Means for Solving the Problems) The present invention is a vertical wet type segment in which a charging box in which a ground electrode is arranged in the form of a segment and a discharge electrode is provided is arranged in the form of a segment)! A pre-charging section, a venturi dust collecting section having at least one variable throat, and a vertical wet segment type electric collecting section are sequentially arranged from the upstream to the downstream side of the gas flow, and the vertical wet segment type The spacing between the collector plates in the electrical collector section is
Gauge pressure characterized by having reached Sakaki in 450 days or more 1.
This is a wet type layer equipment for dust-containing gas that has a gas pressure of 0Kf/m" or more.

The gas generated from blast furnaces contains a large amount of unburned carbon (soot). Currently, after this gas is dedusted in a two-stage vS, pressure energy is recovered in a top pressure recovery power generation facility (hereinafter referred to as TRT) and reused as fuel. However, the soot that takes 9 minutes to form dust has poor hydrophilicity.
In addition, since the specific gravity is small, the two-stage vsS requires a high water injection rate and a high pressure loss, resulting in extremely high running costs for water treatment equipment and a decrease in the amount of TRT recovery energy.

The present inventors focused on the low specific resistance of the generated gas soot, and conducted tests using a wet electrostatic precipitator, and found that when the gas amount is stable due to dual charging, the dust collection performance is stable. However, when cleaning the dust collection electrode and when the furnace condition is unstable (changes in gas amount and temperature), the dust collection performance deteriorates and the T
A problem occurred with RT. For this reason, as a countermeasure against poor confectionery performance when cleaning the dust collection electrodes, we researched a structure that allows constant cleaning and found that it is sufficient to set the distance between the dust collection electrodes at 450 squares or more.

Conventional EP has a narrow collecting electrode interval of 200 to 300 m, and when cleaning the collecting electrodes between these electrodes, water droplets are drawn toward the discharge electrode by electric force, causing bridging discharge and unstable charging. Become.

In order to avoid this, it is necessary to provide an R section extending in the direction from the discharge electrode at the lower end of the dust collection pole, which has the disadvantage of poor cross-sectional efficiency.

According to the experiments conducted by the present inventors, there is a close relationship between the spark starting voltage and the dust collection electrode spacing, and FIG. 4 is obtained. That is, it has been found that if the distance between the dust collecting electrodes is set to 450 f1 or more, the charging can be stabilized even during cleaning without providing the above-mentioned R section at the lower end of the dust collecting pole. Also, the amount of washing water is 0.4 t/Hr/m ~ 2. Ot
The charge became stable between /Hr/m.

Next, we investigated the causes of performance decline during unstable furnace conditions.

The main reasons were the short gas residence time in the EP and the increased inlet abdominal content. As this countermeasure, E
A method of increasing P could be considered, but it was determined that the gas amount increase rate would be too large and unrealistic, so a combination of vS and EP was studied. As has been reported in various reports, the combination of vS and EP has the advantage that the throat pressure drop of vsS increases when the gas amount suddenly changes, resulting in better storm performance and less dust at the EP inlet on the downstream side. ing.

As a result, it was found that the final performance was satisfied until the gas amount increased to a certain extent even if the EP residence time was shortened.

However, this combination cannot compensate for the performance degradation caused by unstable furnace conditions in the case of DR, and only the pressure drop of vS becomes large.
I couldn't find any merit in it as an art book.

Next, we focused on the fact that the preliminary load 'kame vs.vs' had low pressure loss and good performance, and experimented with the combination of Ep+vs, but the result was the same as before. However, it was confirmed that precharging has a large effect on the dust aggregation effect and strengthening of hydrophilicity, and has a large effect on reducing the pressure loss of vS.

Based on the above findings, it was confirmed that the precharging + VS + EP method has low pressure loss and high stability in dust collection performance.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an overall explanatory diagram of the present invention. In the figure, 1 artificial gas pipe, 2 preload mechanism, 3 discharge electrode, 4 ground electrode, 5
Casing, 6 water sprinkler, 7 water level detection control device, 8 population information board, 9VS variable throat, 13 throat water supply device,
11 Industrial gas pipe, 12 Charging device, 144 M pole, 15 Casing, 17 Industrial dust cleaning device, 18 Gas rectifier, 19
A water level detection device, 25 water level control device, and 21 gas outlet pipe are shown.

The wet-type sales collection device of the present invention includes a wet-type precharging section 10, a VS section 20 having a variable throat, an electric droplet section 30, and a water level detection side m section 40-1, 40-2. Blast furnace gas is
For example, gauge pressure 1. The soot in the gas is introduced from the inlet gas pipe l into the wet precharging section 10 under a pressurized state of 817 an" or more, but the soot in the gas is charged and collected due to the precharging, and the hydrophilicity of the soot is changed. Same as above.

Next, in the 78 part 20, high dust collection efficiency is obtained with low pressure loss due to the hydrophilicity of soot and the zero prefecture enlargement effect.

The electric collecting unit 30 of the present invention is composed of a dust collection box arranged in a segment shape. This example will be explained with reference to FIG. FIG. 2 is a view taken along the line A-A' in FIG.

In the dust collecting box of the present invention, the sub dust collecting electrode plate 4-2 is arranged in a connecting straight line toward the cylinder center point ratio, and the main dust collecting electrode plate 4-1 is arranged on a concentric circle with the cylinder center. with a discharge electrode 5 in the center.
will be established.

Since the present invention is a cylindrical casing 15, the main pipe 17-1 of the cleaning device is disposed on the outer periphery of the casing, and the branch pipe 17-1 is arranged on the outer periphery of the casing.
2 can be installed on the sub-collection electrode plate 4-2 via a frame. However, in the electric nesting section 30 of the present invention, since the electrode plate spacing is designed to be 4501111 or more, it is possible to continuously pass the washing water to the electrode plates at all times.

According to the present invention, the dust-containing gas is removed by the 78 parts, then subjected to a rectifying action by the gas rectifier 18, and introduced into the dust collecting box. The dust collection plate of the dust collection box is designed to be more than 450 degrees,
Since the cleaning water is constantly passed through, the water is completely neutralized and then collected from the outlet gas pipe 21 to the outside of the system.

Pre-charging section 1o and EP section 3 of the wet electric business type device of the present invention
Water level detection control units 40-1 and 40-2 are respectively provided in 0 to obtain a dust collection effect. This method is not particularly limited.

FIG. 3 shows another embodiment of the invention. In the figure, the pre-charging section 1O is partially constructed concentrically with the electrical concentration section 3°. Since the 78 part 20 is disposed at the outlet of the pre-charging part 10 and the whole is housed inside the casing 15, it is extremely compact. .

As described above, in the present invention, the precharging section 10, the 78 section 20, and the EP section 30 are sequentially arranged from the upstream side to the downstream side of the gas flow, so that the charging performance is stabilized with low pressure loss. is understood by the following.

The precharging causes charging and agglomeration of the soot, which improves the hydrophilicity of the soot. As a result, the water injection rate of vs is lowered, the energy for spraying water at increased speed is reduced, and the hydrophilicity of soot allows dust collection performance to be obtained with low pressure loss due to the agglomeration and thickening effect. However, due to the low pressure drop, some of the unagglomerated micro dust comes out without colliding and adhering to the throat mist while remaining charged (However, since this micro dust is already charged, it is The rate of dust collection at the bottom becomes faster, and the collection performance improves.The above phenomenon becomes more noticeable when the amount of gas increases compared to other methods.

The reason for this is that the improvement in hydrophilicity and aggregation enlargement due to charging of soot, which are useful for improving the collection ability of VS, occur within a retention time of the order of several tens of seconds, so the precharging effect is hardly affected by the increase in gas volume. . As a result, the QWM performance of ■S does not improve with a fixed throat when the gas amount increases, even though the pressure drop increases.

Rather, it is more advantageous in terms of operation (power cost of the booster blower) to increase the opening area of the variable throat so that the pressure drop does not increase rapidly when the gas amount increases, and to not improve the vS outlet dust content so much. As a result, the residence time of the final stage EP is shortened, and low pressure drop and high performance can be ensured by controlling the amount of dust at the vsS outlet to the extent that the dust collection performance does not deteriorate.

Next, Table 1 shows a comparison between the method of the present invention and other methods.

As is clear from the above table of Table 1, the method of the present invention is capable of producing a low pressure loss and a low outlet content, but furthermore, the following points were confirmed by the inventors' experimental studies.

In the case of pre-charging unit + electric condenser unit 10vS, when the amount of gas increases, the dust collection performance of the pre-charging unit 10 air collection area decreases. However, since the hydrophilicity of soot due to charging remains, it has the effect of reducing the water injection rate of VS, but the amount of fine soot increases, so VS
It is necessary to increase the pressure drop and increase the surface area of the fine mist to maintain a chance of collision between the mist and soot, and as a result, a high pressure drop is required.

In addition, in the pre-charging section and electrostatic precipitator section, in order to stabilize charging, water should be sprayed uniformly over the cross section of the gas passage.

do not have. This is because the coal water is gently washed from near the collecting pole and flows over the fruit plate as nutrient water, so the surface area that comes into contact with the gas is small and the gas cooling effect is small. Because it cannot be overcome.

On the other hand, in the case of the vS-two-vehicle charged electrostatic precipitator, when the gas amount increases, the vS pressure drop increases, and ■S performance is the same as above, but the residence time of some air becomes shorter and the performance decreases. . Since the VS is placed on the upstream side, the gas cooling effect is good, but since the hydrophilicity of soot is poor, a high water injection rate is required, which increases the energy of accelerated spraying of water and increases the pressure drop.

As a result, the vS performance also improves, but the residence time in the electrostatic precipitator becomes shorter, so the performance deteriorates. As a result, the total dust collection performance can be maintained up to about 20% of the gas amount, but when the amount exceeds this, the performance deteriorates.

(Effects of the invention) The wet dust collector of the present invention performs high performance collection and concealment with low pressure loss.
and maintain dust collection performance over the long term. It has great industrial effects, such as realizing a compact, electronic equipment that has a furnace top pressure control function, silencing function, and dust collection function as required, and always exhibiting stable dust collection performance.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the present invention, Fig. 2 is a view from the 8-A' arrow in Fig. 1, Fig. 3 is a detailed explanatory diagram of the present invention, and Fig. 4 is a diagram showing the spark starting voltage and dust collection. This is a diagram showing the pole spacing. 3: Discharge wire 4: Ground electrode 9: Variable throat 10: Pre-charging section 20: VS section 20: EP section Fig. 2 Fig. 3

Claims (1)

[Claims] A vertical wet segment type precharging section in which a grounding electrode is arranged in the form of segments and a charging box provided with a discharge electrode is arranged in the form of segments, and a Venturi dust collection section having at least one variable throat. and a vertical wet segment type electrostatic precipitator are arranged sequentially from the upstream to the downstream side of the gas flow, and the interval between the collecting electrode plates of the vertical wet segment type electrostatic precipitator is 45.
Gauge pressure 1.0 characterized by being configured to be 0 mm or more
A wet type dust collector for dust-containing gas that has a gas pressure of more than kg/cm^2.