At present, the biggest problem that plagues all gravure printing enterprises is the environmental protection problem. How to effectively control the huge amount of organic waste gas generated by the gravure printing machine, how to treat the exhaust gas containing a large amount of various solvents directly discharged when the ink is dried in the printing unit oven. It is an industry-wide problem, and all kinds of related end-management technologies are being vigorously promoted. The market is full of flowers and is complicated and complicated. In this regard, combined with his own many years of practice, the author published a review of gravure printing on the end treatment of exhaust gas in the October 2016 issue of Printing Technology magazine. This article is an extension, simply on the details of the oven.
This article discusses the characteristics of the gravure oven exhaust gas and how the company itself optimizes the wind reduction. The purpose is to reduce the total amount of exhaust gas emitted from the oven and increase the concentration of exhaust gas through various technical measures. The main measure is to recycle the hot air of the oven, and change the exhaust gas directly discharged from the original oven to the rapid and real-time detection of the concentration of the exhaust gas, and recycle the hot air part of the exhaust gas that can be safely reused. Hot air reuse can achieve the purpose of energy saving and consumption reduction, while reducing wind and thickening will lay a good foundation for future waste gas treatment.
However, in this regard, the entire gravure industry has not attracted enough attention, reached consensus and took corresponding actions. At present, only a few suppliers have begun to integrate globally, such as Guangzhou Environmental Protection's ESO, such as heat pumps will use hot air for reuse. And quantify the data into the exhaust, such as few companies started to use the LEL system to achieve hot air reuse, but the author believes that based on the current environmental pressure, oven optimization is already urgent, need gravure companies to fully understand, immediately start action, its The importance is even greater than the last paragraph.
Here, according to my own practice, I will make some suggestions on the details of the oven hot air reuse, and share with you. At the same time, because this is a systematic project, only each enterprise fully understands itself, makes overall improvement, and combines relevant industry technologies. Work hard to be better.
Existing gravure oven exhaust gas exhaust situation
Generally, a gravure printing machine, if there is no ground suction under the ink tank, the basic conditions of the oven exhaust gas in the production of typical products are as follows:
1. The air volume of the main exhaust air is generally: 20000-50000 cubic meters / hour,
2. The main exhaust air solvent emissions are generally: 20-80 kg / hour,
3. The main exhaust air concentration is generally: 0.5-2 g / m3,
Above, if considering the amount of exhausting the bottom of the volatile solvent exhaust under the ink tank of the printing unit, such as a 10-color machine, the bottom exhaust gas will be between 10,000 and 20,000 cubic meters per hour, and the bottom row concentration will be 0.3- 1 g / m3, gravure ink tank seal enclosure is good, such as European and American printing presses, this air volume will be smaller. However, a large number of domestically used or domestic gravure printing machines are used in China, which are generally too large.
If the two exhaust gases and the ventilation exhaust are combined, the concentration of the exhaust gas will be lower and it will be more difficult to treat.
Existing gravure oven drying problems
The oven design of the existing gravure printing machine is generally old and has remained unchanged for decades. In the gravure oven air volume and heat control, there is great waste, especially the excessive air volume, which is the biggest obstacle to the current exhaust gas treatment. Unreasonable is mainly reflected in the following aspects that cannot be effectively controlled. It is proposed here, and it is expected that relevant parties will work together to explore and improve, and hope to find a better control method suitable for domestic gravure printing machine, which can realize the drying of gravure oven. The dry energy can automatically match different working conditions to achieve intelligent, environmentally friendly and safe drying with minimum air volume, minimum heat and maximum concentration discharge (under safe conditions).
1. Maximum speed , the gravure oven design is configured according to the maximum speed to configure the drying air volume and heat, but in actual production, it rarely opens to the maximum speed, the production speed and the drying configuration do not match, and the low speed also uses the large air volume to cause the air volume. And a huge waste of heat.
2. The largest layout , the gravure oven design is configured according to the full-page printing to configure the drying air volume and heat, but in actual production, the general gravure printing products are generally 1-2 units, and many printings with very little ink loading The unit also uses the full version of the air volume and heat to dry, the amount of ink on the plate and the drying configuration do not match, resulting in a huge waste of air volume and heat.
3. The maximum width and gravure oven design are configured according to the maximum width to configure the drying air volume and heat. However, in actual production, the wide-format gravure printing machine produces narrow-width products, and the gravure oven hot air knife currently The width cannot be adjusted, but if there are multiple presses, the wide and narrow products can be allocated relatively reasonably.
4. Layout distribution , at present, each layout of gravure products is personalized and fixed, but the current drying system can not match the hot air and heat according to the position of ink and the amount of ink. The gravure has not yet seen viable. The solution, but in the future UV ink can be achieved by LED independent lamp bead source drying.
Generally, most oven designers only consider the drying quality of the product, and the quality of the drying system itself is considered very little, so even if there is a lot of waste, it is difficult to detect. Drying should be the integration of environmental protection, energy consumption and product quality, the best match, to achieve intelligent, environmentally friendly, safe drying. Of course, there are other related factors, such as the same drying air volume and heat, the selection of good quality, good release inks and solvents, will also reduce emissions.
Existing gravure oven to reduce wind and optimize
1. Reducing the wind, in view of the above unreasonable situation, it is recommended that the gravure printing enterprises immediately start to implement various types of wind reduction that can be landed according to the specific conditions of their own factories, that is, hot air reuse. For details, see the following four.
2. Strengthen the sealing of the oven,
(1) Minimize the inlet and outlet vents, such as adjusting the small gap or considering the gas seal inlet and outlet, reducing the unorganized fresh air.
(2) At the inlet and outlet of the oven, the lowest and upper hot air knives should be inclined inner mouth to avoid high-speed hot air overflow.
(3) Minimize the length of the wet film with bare ink before the imprinting into the oven, such as dropping the oven.
(4) Fully guarantee the sealing of the oven after the joint is closed, and check and replace the aging sealant strip.
(5) Check the connection of each oven and hot air system to the oblique or soft connection to ensure no leakage.
(6) Minimize the gap between the guide roller shaft and the oven. Check the seal of the stationary semi-axis guide roller. The through-axis guide roller is recommended to reduce the gap with the magnetic paste.
3. Improve the sealing envelope of the printing unit ink tank, minimize the area of ​​bare ink, reduce the waste of unorganized exhaust gas, reduce solvent consumption, improve the workshop environment, and stabilize product quality (empirical data, 10 colors 167 meters per minute, plus The lid reduces the volatilization by about 10 kg per hour). At present, it is possible to expose only 5 cm of the front and back of the press roll, and all others are covered. The most convenient way to increase the concentration of exhaust gas is to increase the speed and the second is to increase the ink tank cover. However, most of the gravure printing enterprises now have insufficient understanding and cooperation, or they are unwilling to try. From the perspective of the department, it is not conducive to operation. Increasing the difficulty of management and cleaning, etc., however, the current gravure environmental protection has forced the enterprise to the end of life, which requires all departments of the enterprise to cooperate to the greatest extent unconditionally, in order to protect the future market position of the enterprise.
4. The printing unit will not be closed in and out of the air damper, and the hot air system will be exited. Otherwise, the unit air damper will not be closed, and the main fan will extract and discharge the cleaning gas of the workshop, increase the exhaust gas volume and fan power consumption, dilute the exhaust gas concentration, and increase the processing difficulty. .
5. Reduce or cancel the ground discharge. If the airflow in the printing workshop is well organized, the printing unit is sealed and enclosed. Under the condition of no smell, the air volume of the ground exhaust can be reduced by half, such as 500 cubic meters per hour, and the ground can also be exhausted. The exhaust air is fresh air and sent back to the air inlet of the oven hot air unit.
6. Improve the control of the main fan, stop production and stop the wind. Now there are employees and even the main fan during the meal, heating does not stop, resulting in unnecessary consumption of heating energy, but also increase the energy consumption of waste gas treatment. It is recommended that qualified enterprises consider strengthening energy management and establish Energy assessment, quantifying energy consumption, linking production and energy consumption.
7. Improve the main fan for manual or automatic wind pressure frequency conversion control, to achieve on-demand air extraction, to achieve a few colors to pump a few colors of exhaust gas. The current unreasonable phenomenon is that, for example, a 10-color machine, whether it is a single color or a 10-color production, the main fan is generally the largest.
8. Regularly maintain the entire air duct system to ensure that there is no damage, leakage, blockage, etc., and regularly test the air leakage of the duct system.
9. Improve the sealing and enclosing of the printing workshop, comprehensively consider the HVAC, bottom row, oven in and out, organize and configure the most reasonable airflow.
Makeup Blender Brush,Blending Brush,Eyeshadow Blending Brush,Blend Brush
DONGGUAN YACAI COSMETICS CO.,LTD. , https://www.yacaicosmetic.com