JPH07256040A - Exhaust gas treatment apparatus - Google Patents

Abstract

PURPOSE:To enable operation extremely conserved in energy without supplying air subjected to cleaning control in an exhaust gas treatment apparatus purifying the exhaust gas produced from a semiconductor manufacturing apparatus to discharge the same to the outside. CONSTITUTION:An inverter 15 changing the number of rotations of a blower 8 corresponding to the amt. of polluted air inputted from a primary introducing port 1 and a flow rate resistance variable mechanism 10 increasing and decreasing the opening area of a throat part 3 by the expansion and contraction of an outer enclosing part are provided. The wind velocity due to the exhaustion of polluted air is made constant by controlling the exhaust capacity of the blower 8 by the inverter 5 and the flow rate of the throat part by the flow rate resistance veriable mechanism 10 to efficiently remove dust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust treatment apparatus for exhausting air containing harmful gas or dust generated from a semiconductor manufacturing apparatus, and more particularly to a venturi scrubber type for contacting the air with water or a chemical solution to remove contaminants. Exhaust treatment device.

[0002]

2. Description of the Related Art Generally, an epitaxial growth apparatus and a CVD apparatus, which are semiconductor manufacturing apparatuses, generate waste gas containing harmful gas and dust during operation. This waste gas had to be purified and exhausted outside the factory for environmental protection. Further, although there are various devices for purifying this waste gas and exhausting it outdoors, an exhaust treatment device called a venturi scrubber type which removes pollutants by contacting with water or a chemical liquid has been mainly used.

FIG. 3 is a schematic view of an exhaust treatment apparatus showing an example of the prior art. Conventionally, a venturi scrubber type exhaust treatment device of this type, as shown in FIG. 3, is a primary inlet for introducing untreated air (hereinafter referred to as primary air) containing harmful gas or dust generated from a manufacturing device. 1, a venturi tower 20 having a throat portion 3 having one end having a narrowed channel cross-sectional area and an outlet at the other end, a nozzle 6 disposed upstream of the throat portion 3 for injecting a cleaning liquid, and this nozzle 6 A demister 7 for removing water from waste air discharged from the discharge port by performing cleaning and dust collection processing by elastic collision or diffusion adhesion of fine particles due to gas-liquid contact between the cleaning liquid sprayed from the primary air and the primary air; The blower 8 which discharges the purified air from the air outlet 9 to the atmosphere was provided.

The cleaning liquid 4 stored in the lower portion of the Venturi tower 20 was pumped up by the pump 5 and supplied to the nozzle 6. Further, on the upstream side of the Venturi tower 20, a secondary air inlet and a damper for adjusting the intake amount of this secondary air so that air (hereinafter referred to as secondary air) from the room where the manufacturing apparatus is placed can be introduced. Two were provided.

This exhaust treatment device is designed so that the exhaust air velocity in the throat section 3 is constant in order to efficiently remove and collect dust. However, the flow rate of waste gas generated from a manufacturing apparatus is not always constant but rather fluctuates significantly. Therefore, in order to make the wind speed in the throat section 3 constant, the flow rate of the secondary air from the secondary air inlet is adjusted by the damper 2 so that the exhaust air speed in the throat section 3 becomes constant.

[0006]

In the above-mentioned conventional exhaust treatment apparatus, although the wind speed of the throat part can be kept constant while making up for the lack of primary air with secondary air, the blower is required to obtain the exhaust air speed. You will always be forced to operate at full rating. As a result, the electric power consumed by this blower was enormous. Further, the introduction of the secondary air unnecessarily takes air whose temperature, humidity and cleanliness are controlled from the room where the manufacturing apparatus is placed, and throws it out of the room. The cost is wasted.

There is a method of providing a wind speed adjusting means in order to keep the wind speed constant even if the flow rate of the introduced air becomes insufficient. For example, it is disclosed in Japanese Examined Patent Publication No. 1-17967. This method is a method of transporting dressed particles,
This is a method in which the cone-shaped member is moved in the housing axial direction of the opening of the housing to increase or decrease the opening area according to the amount of air introduced to make the wind speed at the opening constant.

However, when this technique is applied to this exhaust treatment device, the throat part 3 mechanically slides on each other such as a cone, a mechanism part for guiding the cone in one direction, or a spring for applying a preload. Therefore, a fine mechanical dust is generated from the rubbing of the sliding mechanism component, and the fine dust blocks the blowout hole of the nozzle 6, so that the cleaning liquid cannot be sufficiently supplied and the efficiency of the gas-liquid contact with the pretreatment air is reduced. The problem is that it deteriorates the dust removal and collection efficiency. Further, there is a problem that the cleaning liquid containing an acidic or alkaline chemical causes a chemical reaction to these mechanical parts, impairing the strength of the mechanical parts and shortening the life. Further, in a semiconductor device manufacturing plant, when explosive gas such as silane is mixed with primary air such as epitaxial growth, silane may explode due to electric discharge caused by rubbing of mechanical parts. I'm out.

Therefore, it is an object of the present invention to provide an exhaust treatment device which can be operated with extremely low energy consumption without supplementing the cleanly controlled air.

A feature of the present invention is that a contaminated air is introduced from one end side and discharged from the other end side, and a throat portion having a narrowed flow passage cross-sectional area is provided in the middle of the air exhaust path. The venturi tower has, an exhaust device arranged on the exhaust side of the venturi tower, a nozzle arranged on the upstream side of the throat part for injecting a cleaning liquid, and an enclosure part without a mechanical member sliding with each other. A flow resistance variable mechanism that expands or contracts the flow path cross-sectional area of the throat portion, an anemometer that measures the wind speed in the exhaust path of the throat portion, and the flow resistance variable mechanism based on the measurement value of the anemometer. Is an exhaust treatment device including a size of an outer peripheral portion of the device and a control device that controls the exhaust capacity of the exhaust device. Further, it is preferable that the variable flow resistance mechanism is a container member having a flexible outer cover whose expansion or contraction is caused by internal pressure. Further, it is desirable to provide means for changing the exhaust capacity of the exhaust device according to the flow rate of the polluted air.

[0010]

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

FIG. 1 is a schematic view of an exhaust treatment apparatus showing an embodiment of the present invention. As shown in FIG. 1, this exhaust treatment device has a flow rate resistance variable mechanism 10 that increases or decreases the opening area of the throat portion 3 by expanding or contracting the opening portion.
A valve 12 for supplying high-pressure air to the inside of the flow resistance variable mechanism 10 to inflate the surrounding portion of the flow resistance variable mechanism 10; A valve 13 for contracting the outer part,
A control device 14 for controlling the opening and closing of the valves 12 and 13 according to the wind speed value of the throat part 3 by the anemometer 11;
An inverter 15 for controlling the motor speed of the blower 8 is provided in order to change the exhaust capacity of the blower 8 in accordance with the flow rate of the secondary air, and the secondary air inlet and damper in the room, which are provided in the conventional example, are eliminated. That is. Otherwise, it is the same as the conventional example.

Here, the flow rate resistance variable mechanism 10 is, for example, a balloon-shaped member, which is arranged at substantially the center of the opening of the throat portion 3 and is supported by a high pressure air pipe. The outer cover is made of a flexible material that is strong against acid or alkali. Examples of this material include fluororubber and chlorinated polyethylene rubber. And, preferably, the surface of the outer coat is coated with a conductive paint so that electric charges are not accumulated.

The motor of the blower 8 has an inverter 1
5 is connected, which controls the rotation speed of the motor by changing the frequency so that the wind speed of the throat section 3 becomes a desired wind speed according to the flow rate of the primary air. In other words, when the amount of primary air is small, the motor is rotated at a speed equal to or less than the rated value to save power. Further, it is desirable to use a small anemometer 11 provided in the throat section 3 so as not to affect the conductance. For example, a pressure sensor that measures wind speed with wind pressure is appropriate. In addition, one method is to arrange a plurality of pieces as necessary to improve the wind speed accuracy and calculate the average as a wind speed value.

Next, the operation of this exhaust treatment device will be described. First, assuming the maximum amount of the primary air introduced from the primary inlet 1 in advance, the rotation speed of the motor of the blower 8 is set to the inverter 15 so that the wind speed in the throat section 3 reaches a desired value by the amount. Set with. Then, the blower 8 is operated at the set rotation speed to introduce the primary air from the primary inlet 1. As a result, the primary air is subjected to cleaning and dust collection treatment by gas-liquid contact with the cleaning liquid sprayed from the nozzle 6 in the path of the throat section 3, and the cleaning liquid falls to the bottom of the Venturi tower 20 and is subjected to the dust removal processing. The water is removed through the demister 7 and is discharged to the atmosphere through the air outlet 9. On the other hand, the cleaning liquid 4 accumulated at the bottom of the Venturi tower 20 is pumped up by the pump 5 and supplied to the nozzle 6.

While continuing such an operation,
When the wind speed of the throat portion 3 is lower than the desired value, the control device 14 sends a signal to the valve 12 for introducing high-pressure air to open the valve 12 and supply air to the variable flow resistance mechanism 10 to expand it. This reduces the opening cross-sectional area of the throat portion 3 and increases the wind speed of the throat portion 3. When the desired wind speed is reached, the valve 12 is closed and the supply of high pressure air is stopped.

On the contrary, when the wind speed of the throat section 3 is faster than the desired value, the control device 14 sends a signal to the valve 13 for extracting high-pressure air to open the valve 13 so that the air in the variable flow resistance mechanism 10 is supplied. Pull out and shrink. This increases the cross-sectional area of the throat portion 3 and increases the throat portion 3
When the desired wind speed is reached, the valve 13 is closed. In this way, while constantly monitoring the anemometer 11, the wind speed of the throat section 3 is kept constant and dust is efficiently removed. If the primary air amount increases more than expected during operation and cannot be controlled by the variable flow resistance mechanism 10, the rotation speed of the motor of the blower 8 is increased to keep the wind speed constant.

FIG. 2 is a schematic diagram of an exhaust treatment apparatus showing another embodiment of the present invention. In this exhaust treatment device, the flow rate resistance variable mechanism 16 is formed into a tire tube shape, and an outer frame 17 for fixing the outer side of the tube body is provided. Valve 1
By opening 2, the tube body bulges inward so as to narrow the inner diameter of the throat portion 3. Also, opening the valve 13 causes the tube body to shrink,
When the inside pressure is normal pressure, the throat part 3
It is flush with the inner wall of the. The variable flow resistance mechanism 1
Since the side surface of No. 0 is easily subjected to wind pressure, it is necessary to radially woven the reinforcing fiber wire into the outer skin of the side surface so as not to bend and to increase the rigidity.

Flow resistance variable mechanism 16 in this embodiment
Is a mechanism for directly squeezing the opening of the throat portion 3, so that the wind velocity change sensitivity with respect to the increase or decrease of the flow resistance can be obtained higher than that in the case of simply disposing the conical member in the flow path as in the above-mentioned embodiment. There is an advantage that more precise control can be performed.

[0019]

As described above, according to the present invention, the means for changing the exhaust capacity of the exhaust device according to the input polluted air volume and the flow rate without the sliding mechanism in the exhaust passage of the throat part. A variable mechanism that changes the resistance is provided, and even if the amount of polluted air that is input changes, the exhaust capacity varying means and the flow rate varying means keep the wind speed of the polluted air exhausted at the throat constant, thereby efficiently removing dust. As a result, it is no longer necessary to suck and dispose of secondary air that is cleanly controlled and costly as in the prior art, and the exhaust device is not continuously operated at a high rating due to the suction. Therefore, according to the present invention, there is an effect that energy saving operation can be performed.

Further, there is an effect that the duct for introducing the secondary air, the damper and the like which are additionally provided for introducing the secondary air are unnecessary, and the cost of installation work of the exhaust treatment device can be reduced. Furthermore, in the variable flow resistance mechanism, the flow resistance can be changed without having a mechanism that slides on each other, so there is no risk of problems such as dust generation due to friction or violence due to sparks.

[Brief description of drawings]

FIG. 1 is a schematic view of an exhaust treatment device showing an embodiment of the present invention.

FIG. 2 is a schematic view of an exhaust treatment device showing another embodiment of the present invention.

FIG. 3 is a schematic diagram of an exhaust treatment device showing a conventional example.

[Explanation of symbols]

 1 Primary Inlet 2 Damper 3 Throat 4 Cleaning Liquid 5 Pump 6 Nozzle 7 Demister 8 Blower 9 Outlet 10, 16 Flow Rate Variable Mechanism 11 Anemometer 12, 13 Valve 14 Controller 15 Inverter 17 Outer Frame

Claims (3)

[Claims] 1. A venturi tower having polluted air introduced from one end side and discharged from the other end side, and having a throat portion having a narrowed flow passage cross section in the middle of an exhaust path of the air, and the exhaust of the venturi tower. Of the throat portion by expanding or contracting the outer portion without providing an exhaust device disposed on the side of the throat portion, a nozzle disposed on the upstream side of the throat portion for injecting a cleaning liquid, and a mechanism member that slides with each other. A flow resistance variable mechanism that increases or decreases the flow path cross-sectional area, an anemometer that measures the wind speed in the exhaust path of the throat portion, and the size of the outer portion of the flow resistance variable mechanism is controlled by the measurement value of this anemometer. An exhaust treatment device comprising: a control device. 2. The exhaust treatment device according to claim 1, wherein the variable flow rate resistance mechanism is a container member having a flexible outer cover whose expansion or contraction is caused by internal pressure. 3. The exhaust treatment device according to claim 1, further comprising means for changing an exhaust capacity of the exhaust device.