Reducing wind and increasing concentration is to take away volatile solvents with the least amount of air, which is undoubtedly the only way for economic and applicable VOCs treatment scheme. In a closed environment, if the odor in the workshop is not considered, as long as the total exhaust air volume can be controlled, no more complex technology is needed.
However, workshop odor must also be controlled. In the past, a lot of ground exhaust air was used to control the odor, but the exhaust gas also needs VOCs treatment, which constitutes a new problem. How to control the odor in the workshop in the most economical way? It can be subdivided into several small topics, such as the source of odor generation, the way of odor diffusion, the purpose of odor control, etc.
Question 1: reducing wind and increasing concentration is a good way. But at present, there are requirements for occupational diseases. The smell of the workshop should not be strong. If there is no in-situ ventilation of the workshop, will the workshop smell strong?
Answer: to reduce the leakage of the oven, the ink tank and ink barrel should be closed as far as possible, reduce the workshop (or local) ambient temperature, to avoid large windage near the printing plate, and the ground ventilation is appropriate.
This is a system engineering, and if used properly, it can also help to reduce solvent waste. In particular, the use of ink stick greatly increases the agitation effect and increases the volatilization rate. But shielding must take into account the safety (material problems caused by static electricity and other effects), especially now the use of open ink tray is very large. In addition, the setting of the wind path will also affect the smell. If it is not set properly, the wind path is not smooth, and the taste will be extremely high.
The mutual influence between the two devices cannot be avoided, so it is suggested to separate them. However, it involves the specific requirements of customers and the convenience of goods delivery. Therefore, we are also exploring other ways, such as the air inlet and outlet linkage and micro pressure control of the two devices to reduce the mutual influence. In addition, there are various specific placement methods, such as face-to-face (printing machine side operation surface), single row discharge, etc It's also different.
Question 2: are the closed-loop ink supply system, automatic inking system and cavity type transparent isolation of ink bucket scraper of soft package gravure printing equipment worth exploring and drawing lessons from?
Answer: it is said that it is not suitable for gravure printing. Especially the plate roller with shallow net. But there are advantages, can avoid flying ink, the scene smell will be small, but the price is also expensive.
Question 3: at present, with the speed of 150 meters, width of 1 meter, conventional gravure printing, controlling the odor of unorganized volatile workshop, without considering the interference of environmental factors, how much floor air extraction is required per unit at least?
For example: the earliest Fuji was 30 cubic meters per minute per color, which was 1800, but this 10 color floor row needed 18000, about 11kw fan. If the ink groove was well sealed, I think it could be less than 1000. If it was lower, it was estimated that the odor would run to the garage.

Answer: it's difficult to accurately evaluate. Huanbaojia can control the odor to the original level with the air volume of 3000-5000. This is closely related to the layout of the workshop and equipment status. There are too many influencing factors, so we can only adjust measures to local conditions. 3000-5000 is used as the ground exhaust air to extract the odor of the workshop, and then as the inlet air of ESO. The location and method of extraction have great influence on the effect of odor elimination.

Question 4: what are the most important influencing factors of odor?
answer:
1. Oven design does not overflow, less exposed wet ink.
2. The less ink on the ink, the smaller the wet ink area.
3. The cover plate of the ink groove is well sealed and the odor is less.
4. The extraction position and air volume are appropriate
5. The tank needs to be covered on site.
Odor control is mainly in large printing unit. Of course, if the whole printing unit is closed to reduce mutual interference, odor control is better. But if you don't understand, it will cause increased odor and even safety risk.
Question 5: 3000-5000 is used as the ground exhaust air to extract the odor of the workshop, and then as the inlet air of ESO. So, how much negative pressure fresh air per unit?
Answer: 3000-5000 is used as the ground exhaust air to extract the odor of the workshop, and then as the inlet air of ESO. The negative pressure fresh air of each unit of the oven is 300 ~ 500. The total exhaust air volume of ten color machine is 6000 ~ 10000, which is closely related to the design and manufacture level of oven and odor control requirements. Because the total amount of ground exhaust air is much smaller than the original, it needs a lot of efforts to achieve the same level of odor control. The location of the exhaust is critical.
We believe that it is very difficult to control the average 500 + 500 on the existing models, which will eventually cause a lot of peculiar smell in the workshop. If it's a small layout unit or it's OK, the large layout should be enlarged. In other words, if the evaporation capacity of solvent in the unit oven is less than 10 kg / h, the air volume is OK. If the evaporation capacity reaches 30, 50 and 80 kg / h, the odor exhaust and main oven exhaust should be increased.
Question 6: is it feasible to cool the ink (barrel) through a refrigerator and cool the temperature of the ink and plate to below 20 ℃ (but not lower than the air dew point)?
Viewpoint 1:
Will hot film encounter cold ink affect printing quality?
The first one was to make a interlayer under the ink tank, then to do a cold water bath, and finally to change the small heat exchanger
There is no air conditioning workshop, condensate will flow into the ink, in addition to summer solvent volatilization, its temperature is lower than the solvent
Point 2:
In this way, it can reduce the unorganized volatilization of solvent, and also reduce the shallow dot dry plate, so that the printing layer feeling is better, and there is no need to make too many solvent formulations for quick drying, medium drying and slow drying. Summer ink cooling can reduce the amount of fugitive volatilization by at least half. A variety of ink cooling devices have been prepared to launch. It is better to install air conditioning in the workshop to lower the air humidity slightly, so that the temperature of the ink can be further reduced after the dew point of the air is reduced, and condensation water is not precipitated.
Question 7: if the workshop is equipped with air conditioning, the cost of air conditioning is another problem. If it is fresh air emission, the power of the air conditioner is certainly better; if the ground exhaust air enters the circulation, the temperature of the air conditioner is low, and after entering the circulation, the electricity cost of equipment heating is increased.
answer:
Air conditioning must be equipped. The workshop mainly uses dehumidification, and the temperature does not need to be lowered too low, otherwise it will consume a lot of electricity. Now there is an air conditioning equipment with dehumidification priority, which is very suitable for printing workshop.
In summer, if the workshop temperature is adjusted to 29-30 ℃, the dew point is controlled at 20 ℃, and the relative humidity is about 50%, people feel comfortable, there is no condensate precipitation, the moisture content of the air is moderate, no static electricity is generated, and the air conditioning power consumption is not much, fresh air dehumidification air conditioning with dehumidification priority and sensible heat exchange function of inlet and outlet air can be adopted.
The ceiling of printing workshop should be reduced as much as possible, and other useless space should be closed and separated as far as possible, so as to make the workshop space as small as possible, which is beneficial to saving the electricity cost of air conditioning and the organization and flow of air flow.
Discussion summary
The high cost of exhaust air treatment limits the total amount of exhaust air, including ground exhaust air. After losing the simple means of using large amount of exhaust air to treat workshop odor, the treatment of workshop odor becomes a technical activity.
From the source of odor, the natural volatilization outside the oven such as ink tank and oven leakage are the two main reasons. The structure design and pressure control of the oven are the two key factors to control the leakage of the oven.
In the application process of ESO, we found that the design and manufacturing level of ovens of different manufacturers in different periods differ greatly, and the cost of maintaining the micro negative pressure at the feed inlet is more than twice. For good equipment, 300 air volume can effectively control the leakage; for poor equipment, 800 more exhaust air can not obtain the overall negative pressure, and the leakage is difficult to control, and when the exhaust air volume is large, it will bring tension Negative effects of overprint. From this point of view, it proves once again the old saying that "cheap goods are not good goods, but goods are three points more expensive".
Ink tank and other drying oven outside the natural volatilization, using some simple covering method can achieve a more significant effect, it is recommended that we all try. However, we should be prepared to be resisted because of the inconvenience to workers. Don't give up easily. We'd better give some extra rewards and guidance.
From the many methods we have tried, the air distribution effect in the control workshop is the best, and the investment is relatively low. However, the disadvantage is that the design is difficult due to the different situations of each company, and it is difficult to get the ideal effect only by imagination.
If the workshop space is too large and the air distribution is difficult to implement, the horizontal runner can be considered for internal circulation treatment.
The existing gravure press oven level determines that leakage is inevitable. The design level of the oven of gravure press needs to be improved urgently. Strict requirements should be put forward to the manufacturers for ordering new equipment, so as to avoid paying heavy costs in the follow-up. The old equipment is troublesome and the leakage is serious. Now we have to pay the price.
Under the same leakage air volume, the total amount of solvent leakage in the oven can be reduced because the concentration of ESO increases step by step in the air reducing device. This is the unique comparative advantage of ESO, but it is still difficult to completely solve the problem, and other auxiliary means such as air distribution must be adopted.
The key is that the users should understand the interests and put forward requirements for the machinery factory; after the machinery factory attaches importance to it, the progress will be very fast.
We have calculated before that the comprehensive cost of 10000 air volume per year may be as high as 1 million yuan. Whether the accuracy is high enough or not, it at least indicates that "air is very expensive". We should pay attention to how to use the least air to remove all volatile solvents.
Foreign mature technology is to use high-quality runner processing, but whether it is a one-time investment or long-term operation costs are too high, we should be able to use a more intelligent way to solve the problem.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
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