JPS58185784A - Method for preventing scattering and diffusion of harmful material by air curtain formed by circulating air flow - Google Patents

Abstract

PURPOSE:To prevent the expansion in scattering of harmful material effectively with an air curtain formed between a blow port and a suction port, by providing the suction port and the blow port so as to face each other, connecting the ports to a duct, providing a fan at the intermediate thereof and circulating air flow. CONSTITUTION:A suction port 1 and a blow port 2 are installed so as to face each other. The port 1 and the port 2 are connected by means of a duct 3, and a fan 4 is installed at the intermediate thereof. When the fan 4 is driven, circulating air flow is generated over the entire part of the system, and an air curtain 5 is formed between the port 2 and the port 1. The scattering and diffusion of a harmful material 6' from a source 6 generating harmful material is shielded by the curtain 5 and joins with the air flow, whereby the scattering thereof to the outside is prevented from spreading.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing the scattering and diffusion of harmful substances by means of an air curtain formed by circulating air currents.

2. Description of the Related Art Conventionally, various methods and devices have been devised and installed for each type of harmful substance as a method for preventing the scattering and dispersion of harmful substances from their sources, thereby maintaining a good work environment and preventing the generation of pollution. Items that require local ventilation, such as electrolytic tanks (plating tanks, electrolytic degreasing tanks, alumite tanks, etc.), pickling tanks, etc., degreasing equipment using organic solvents, draining equipment using Freon, and drying equipment used in metal surface treatment. The conventional methods have the following problems. In order to maintain a good work environment, if local exhaust is designed with a sufficient controlled wind speed, (1) the exhaust air volume and cost will be large;
2) The large amount of substances taken out actually increases the scattering and dispersion of harmful substances. (3) If the distance from the suction port is 1wz or more, it will be difficult to maintain a controlled wind speed even if the suction landscape is increased, so even if the local exhaust is a double-sided suction type, if the distance from the suction port exceeds 1wz, it will be difficult to maintain a controlled wind speed. How to design local exhaust ventilation for large tanks, etc. For large tanks, there is a round method in which an air curtain is added to the normal local exhaust method, but since this air volume and local exhaust air volume are all exhaust air volume, the processing equipment is large, and in-factory air conditioning is almost cost-effective. It was impossible. Regarding the above, the inventor has provided the following advice to the parties involved. (1) Do not place the suction port too close to the source. (For example, in normal electrolytic cells, the distance between the suction port and the liquid level is often 50 to 100X, but if you have this, make it larger. If possible, make it 300X or more) The local exhaust system of a large tank should be used in case of harmful substances. In order to prevent workers from directly inhaling harmful substances if they are not completely discharged, the hazardous substances are formed in a dug-out or raised-bed shape, etc. to prevent them from flowing towards the worker's face in case of an emergency, considering the weight of the harmful substances. I'll make sure it doesn't. (3)
The layout should be designed taking into account the direction of the overall airflow, including ventilation and air conditioning in the factory, so that even if hazardous substances are scattered or diffused, the flow will flow in the direction where there are no workers. etc. However, even with these efforts, it is still difficult to adequately address the problems described above with local exhaust ventilation methods. The present invention appropriately addresses the above-mentioned problems; it maintains a better working environment, reduces the amount of harmful substances taken out, and even if it is discharged outdoors, the air volume is much smaller than in the past, so it It is possible to reduce air conditioning costs (or air conditioning can be installed in factories where air conditioning could not be installed due to the cost because the exhaust volume is too large, or it is possible to handle hazardous substances in clean rooms etc.) This invention relates to a method for preventing the scattering and diffusion of harmful substances by means of an air curtain formed by circulating air currents. This will be explained in detail below with reference to the drawings.

FIG. 1 is a basic conceptual diagram of the present invention. The suction port 1 and the blowout port 2 are installed facing each other. Suction port 1 and outlet port 20
are connected by a duct 3, and a blower 4 is installed between them. By operating the blower 4, a circulating air flow is generated throughout the system, and an air curtain 5 is formed between the outlet 2 and the inlet 1. Ru. The harmful substances scattered outside 6' from the harmful substance generation source 6 are blocked by the covering air curtain and merge therewith, so that they are not scattered and diffused to the outside. This circulating air volume is smaller than the exhaust air volume for suction only. Also, if a side plate is provided between the blowout port 2 and the suction port 1, the air curtain will be further stabilized. (This is the same for the suction type hoods that are currently available.
- If the tank weight is approximately 700%, the suction hood must be approximately 150% longer on one side than the length of the cypress, or it will be difficult to maintain a controlled air velocity at some corners of the cypress. In other words, if the tank length is 1000%, it is approximately 1
Requires 300% length suction hood. The inventor has often noted this issue in the metal surface treatment industry, but it has not often been put to use in equipment. ) When the pressure of the part 7 covered by the air curtain is almost the same as the pressure outside the air curtain, there is a kind of equilibrium state in which the same airflow circulates, and near the suction opening, the air curtain air volume is equal to the suction air volume. In proportion to this, there is almost no turbulence, so there is almost no phenomenon in which harmful substances 6 are brought out, unlike in the case of a normal local exhaust inlet. The air curtain is now acting as a lid. If the worker's side is on the outlet 2 side, the working environment will be even better. However, if harmful substances evaporate and diffuse so strongly that they cannot be suppressed by normal diffusion prevention equipment (for example, when using a cooling pipe system to prevent the diffusion of fluorocarbons in a 70-ton dryer), if this condition continues, the circulation will continue. Since the concentration in the airflow is gradually increasing, countermeasures are needed to prevent this. Also, in the case of electrolytic mist, etc., many of them are able to withstand collisions with the duct during circulation, but if possible, it is better to remove (or collect) the mist without contaminating the inside of the duct.

FIG. 2 is a conceptual diagram that incorporates measures to remove harmful substances contained in circulating air currents in addition to the basic concept. A harmful substance removal (or recovery) device 8 is provided at an appropriate location in the duct 3 connecting the suction port 1 and the blowout port 2. This device does not require consumables or replacement parts (e.g., filters, activated carbon, etc.), since the air volume is smaller than in the case of normal suction type local exhaust ventilation, but because it allows the entire amount of circulating air to pass through. desirable. For example, there are cooling fin filters for eliminator-1 organic solvents for mist generated by electrolysis, and the like. And what is removed can be reused. For example, the amount of mist collected during chrome plating p-
These include fluffing liquid, Tri-Clean whose diffused content was recovered from the Tri-Clean cleaning equipment, and Freon whose diffused content was collected from the Freon drainer and drying equipment.

By the method described above, it is possible to almost prevent the scattering and diffusion of harmful substances. However, if the harmful substances have strong evaporation power and strong dissipation power (e.g. fluorocarbons, etc.), or if the shape of the item disturbs the air curtain greatly when taking it in and out, it is necessary to use an air curtain to maintain a good working environment. Since the air volume is higher than the air volume of the

Figure 3 is a conceptual diagram including the above measures.

A circulation duct 3 and a branch duct 9 are provided between the blower 4 and the outlet 2, and if necessary, a damper 10° 10' for adjusting the air volume is provided in each duct. Excretes part of the circulating Qi to the outside. If necessary, a hazardous substance treatment device 11 (for example, an activated carbon adsorption device for organic solvents, or a scrubber for hazardous mist generated by the electrolytic cell) is provided in the middle. (In this case, the air volume of external exhaust is much smaller than the air volume of normal local exhaust, so the processing equipment requires less space (and cost), and in-factory air conditioning is also cost-effective. (A good working environment can be created.) When a part of the circulating air is discharged to the outside in this way, a difference is created between the air volume of the air curtain coming out from the outlet and the amount of air entering through the suction port, which causes the air to flow outside. The exhausted air volume is absorbed around the suction port as a part to eliminate the diffusion pressure of harmful substances or as a supplementary air flow 12 from outside.For this reason, an air flow in the same direction as the air curtain is formed above the air curtain. Even the disturbance caused by the air curtain that removes insects when items are put in and taken out is absorbed through the suction port, making it possible to maintain a good work environment.Also, the slit in the air outlet can be made to have an adjustable structure. Alternatively, you can provide a separate air outlet 14 that faces roughly the same direction as the air outlet and can be opened and closed, and if necessary, provide a separate air inlet 15, and adjust these appropriately with a damper etc. to adjust the air curtain's wind speed. In addition, by changing the direction of the wind, it becomes a very effective method of preventing the scattering and dispersion of harmful substances, which has been difficult to achieve with conventional local exhaust ventilation.The details are described below.

As shown in Fig. 4, when the object to be treated 13 is pulled up and released outside after the treatment is completed, if harmful substances are to be scattered or diffused from the object to be treated, a device should be installed near the source. It has been difficult to eliminate these harmful substances using local exhaust ventilation systems. Examples of such cases are often seen in plating, alumite, organic solvent degreasing, etc., but the most severe case is large-scale hard chrome plating. In this case, the size of the object 13 to be treated ranges from 1 m to several meters, and it is pulled out of the tank after treatment, and the object 13' itself also has a liquid temperature of 50 to 60 m.
Since the temperature is almost the same as 0°C, harmful substances are evaporated from the surrounding area. Also, since the chrome plating solution is washed away with water in this state, droplets containing harmful substances are scattered around. The only way to dissipate the harmful substances that were dispersed in this way was to vent them outside through general ventilation. In the present invention, the following measures can be taken. That is, apart from the air outlet 2, a separate air outlet 14 facing approximately the same direction is provided. This may be done by making the slit of the outlet 1 variably adjustable. The key is to adjust these things so that the suction air volume does not decrease (it may increase), the air curtain's air speed is slow, and the object 13' that has been pulled up is soft and gentle. good. If the object 13' to be treated ahead of this airflow is large and necessary, another suction port 15 is provided and a tambar 17.17 for changing the wind direction is provided.
By adjusting the air curtain 1, the wind speed can be reduced.
6 can be formed.

If workers work near the air outlet, there is almost no danger of them coming into contact with the hazardous substances that will spread out. Furthermore, untreated harmful substances are almost never discharged outdoors without passing through the treatment equipment. When washing with water or the like is finished and the liquid containing harmful substances has been washed away from the object to be treated and there is no longer any risk of the harmful substances scattering, each adjustment section may be operated so that the air curtain returns to its normal state. Further, although each adjustment part may be done manually, it is easy to electrify or mechanize it, so the operation is extremely simple and can also be automated.

Incidentally, in the example shown in FIG. 3 and the example shown in FIG. 4, outdoor discharge may be carried out using a different system as follows.

This method has the disadvantage that an extra exhaust fan is required compared to the above-mentioned methods, but it has the advantage that a switching device or the like is not necessary or simple. FIG. 5 is a conceptual diagram showing a separate system for outdoor discharge.A separate suction port 15 is provided above and parallel to the suction port 1, in addition to the device forming the air curtain. If there is a separation between the suction port 1 and the separate suction port 15, the gap is appropriately covered with a board or the like. A discharge-only duct 18 is connected to the separate suction port 15, and a harmful substance processing device 11 and an exhaust-only exhaust fan 19 are provided in the middle for exhausting air. In this case, the exhaust fan 19 is made into a type that can change the air volume by changing the rotation speed, etc.
In normal cases, the supplementary airflow 12 is only exhausted, and it is even more effective to increase the exhaust amount when the object to be treated is pulled up. The air blower 4 in the circulation system may also be of an air volume switching type, so that the air volume may be reduced to make the air curtain feel softer when the object to be treated is pulled up.

[Brief explanation of the drawing]

Fig. 1 is a basic conceptual diagram of the present invention, Fig. 2 is another conceptual diagram developed from the basic conceptual diagram, and Figs. 3, 4, and 5 are further conceptual diagrams. The codes inside are 1:
Inlet 2: Outlet 3: Duct 4: Blower 5:
Air curtain 6: Hazardous substance generation s6': Hazardous substance scattered and diffused portion 7: Covered part 8: Hazardous substance removal (or collection) device 9 bifurcated duct) 10.10': Damper for adjusting air volume 11; Hazardous substance treatment Device 12: Replenishment airflow 1-2 Workpiece 13': Pulled up workpiece
14: Another outlet 15: Another inlet 16: Air curtain with low wind speed 17. 17': Damper for switching wind direction 18: Exhaust-only duct 19: Exhaust-only exhaust fan 〇 Patent applicant Toshiharu Nakai

Claims (1)

[Claims] 1) The V& inlet and the outlet are installed facing each other, the inlet and the outlet are connected by a duct, and a blower is provided between them to circulate the airflow, thereby making it possible to connect the outlet and the outlet. The air curtain formed between the suction ports covers the source of harmful substances and eliminates them. How to prevent scattering. 2) A device for removing (or collecting, etc.) harmful substances is provided in the middle of the duct connecting the suction port and the blowout port, and the suction port and the blowout port as described in claim 1 are installed facing each other.
The inlet and the outlet are connected by a duct, and a blower is provided between them to circulate the airflow, so that the air curtain formed between the outlet and the inlet covers the source of harmful substances, A method to prevent the scattering and diffusion of hazardous substances. 3) By discharging a part of the circulating airflow to the outside through the branch duct outside the outlet (or, if necessary, discharging the harmful substances to the outside after treating them with a hazardous substance processing device), The suction port and the blowout port according to claim 1 are connected by a duct, and a blower is provided between them to circulate and maintain the air current, thereby increasing the suction air volume as well as the curtain air volume. A method of preventing the scattering and dispersion of harmful substances by covering the source of harmful substances with an air curtain formed between the outlet and the suction port. 4) Make the slit of the air outlet adjustable, or add a separate air outlet facing roughly the same direction as the air outlet that can be opened and closed, and if necessary, create a separate air inlet and adjust these appropriately using a damper, etc. The air inlet and the outlet are installed facing each other, and the inlet and the outlet are connected to the duct. A method in which the air curtains are connected to each other and a blower is installed between them to circulate the airflow, thereby covering the source of harmful substances with an air curtain formed between the outlet and the inlet, thereby preventing the scattering and dispersion of harmful substances.