As a gravure practitioner for many years, regarding the end treatment of gravure VOCs, the author starts from gravure user's point of view with some experiences and suggestions. It is courageous to discuss and share with you.

Gravure VOCs terminal treatment technology applications

From 2001 to 2007, there were many gravure VOCs end-treatment projects in some large and medium-sized cities nationwide. Most of them were "activated carbon adsorption + catalytic combustion", but most of these projects did not actually operate. The main purpose of the project was to meet the requirements of environmental impact assessment Emissions, not VOCs.

From 2007 to 2012, gravure enterprises of all sizes above and below started VOCs end-of-life management projects one after another, basically taking "recycling" as their main objective. For example, activated carbon (carbon fiber) adsorption + recycling was launched with three main purposes: economic recovery expected, , The initiative of enterprises to govern.

From 2012 to 2014, many gravure enterprises voluntarily launched VOCs end-of-pipe projects, but basically they still rely on "recycling" mainly because of the smog lock in the cities throughout the country. For the first time, the state has proposed to include VOCs in pollution prevention and control and gravure printing enterprises Environmental pressure surge.

Since 2015, the packaging and printing industry has been listed as a pilot VOC charging industry by the state. The gravure printing industry is under tremendous environmental pressure due to the large amount of organic solvents used in the production process. Based on the substantial charge of emission charges of VOCs, the gravure emission standards becoming increasingly stringent, and the possibility of automatic on-line continuous testing in the future, the mainstream VOCs end-effector technology in the entire gravure printing industry began to rapidly turn to combustion (RTO). In the same period, Large-scale gravure enterprises around the rapid promotion of large areas, but up to now, the actual operation is still relatively small, remains to be seen. However, many cities in the same period have put forward the requirements of a short period of time and quick treatment, forced by the situation, capital, and technology and market turmoil, etc., most of the gravure companies havetily chose the plasma, photocatalysis, catalytic combustion, photolysis and other investment in the few One hundred thousand temporary transitional measures are also a great waste.

Gravure VOCs terminal treatment options

Based on the current economic, technical, environmental protection, market conditions, I believe that gravure printing companies in the choice of end-treatment programs VOCs, we must pay attention to the following three aspects.

1. thoroughly

Gravure printing enterprises must find out the overall situation of VOCs emissions, concentrations, composition, etc., and take into account the plan, especially the waste gas volume, concentration and regularity at the entrance of the treatment facilities, which need to be repeatedly confirmed. This is the basis for all project design and operation and must be repeated confirm.

2. Lighten the wind and the scene closed

Optimize the structure of gravure machine oven, reduce, merge, concentrate exhaust gas, reduce emissions, control the total per-color exhaust gas is less than 1000m3 / min or less (but the oven internal air volume and air pressure remain unchanged) Reuse, automatic LEL hot air recycling and other measures to achieve. Concentration of exhaust gas concentration is generally greater than 2.5g / m3, to achieve self-sustaining concentration of RTO, after the operation of gravure printing companies only need to bear the cost of energy inverter fan. However, gravure oven oven design, involving the oven design, no organization to reduce the ink tank closed, the system insulation, drying principle, gravure process, hot air recycling, the need for research institutes, gravure printing machinery factory, hot air system integration Business, gravure enterprises such as multi-party co-ordination completed (domestic gravure printing machine on the Wan Taiwan, gravure printing machinery on the hundreds, but most of the drying system used foreign machinery plant 20 years ago, the system can truly co-ordinate development and design has not yet) , In order to achieve the purpose of effective drying at a given speed, minimum air flow, minimum heat, and maximum exhaust gas concentration (but with exhaust gas concentrations below safety). In this paper, I recommend gravure printing industry grading and energy efficiency grading logo, so that we can better from the beginning of the design of a comprehensive co-ordination, management of energy consumption, the use of energy consumption, and greatly promote the progress of the industry.

Site closure is an important measure to reduce unorganized emissions. Although there are few overseas countries, there are requirements in China that the relative closure of printing presses should be included in the schedule, except for the ink tank closed, the oven negative pressure and the ground ventilation canceled or combined.

3 carefully chosen

Based on the current environmental protection policies, management technologies and various complicated VOCs emissions of gravure printing enterprises, even if intaglio printing companies are really committed to VOCs management, it is extremely difficult to make effective and reasonable proposals in the short term. Many failures, especially the current practice of some gravure companies outsourcing VOCs directly to suppliers is extremely wrong. Gravure printing companies need to fully understand that even if the suppliers from the previous investigation, design, processing to the latter part of the installation, commissioning and full participation and cooperation, but for now, can ensure the success of the project, there are all kinds of uncertainties, so concave Indian enterprises should be carefully chosen.

In the following, based on the author's understanding and understanding of the current gravure VOCs end treatment technology, the following suggestions are given for your reference.

Option One: solvent recovery [not recommended]

The main problems are as follows:

(1) compliance

Recycling program Adsorption of a waste gas effluent discharge standards difficult, and the exhaust gas multi-component (such as alcohol) and the adsorbent material itself, the non-selectivity, making all kinds of different forms of exhaust gas at the same time meet the standard is very difficult, most of them require additional secondary VOCs treatment Facilities to achieve compliance.

(2) Safety

First, the solvent reuse process area requires water removal, odor removal, distillation, decoloration, purification and other operations. It belongs to Class A explosion-proof areas and needs to be far away from the production area. Purification processes similar to chemical processes have great potential safety hazards. In addition, whether to allow the factory to handle such recovery of solvents, local safety supervision, fire policy fuzzy; Second, the gravure exhaust composition is complex, in addition to solvents, and ink, varnish and other internal solvent composition, repeated back to the original gravure Pure solvent technology, there will be a variety of potential product quality risks, especially for food packaging, prone to solvent migration risk.

(3) Technology

At present, the application of single solvent or two-component solvent ink is not yet mature, gravure exhaust gas recovery is a mixed solvent, but also can not separate and purify the site to reuse, and if the company only 1 to 2 gravure machine exhaust emissions Amount, a few hundred tons a year, too small, not suitable for recycling.

(4) policy

Recycling solvents are defined as hazardous wastes in the country and need to be handled by qualified enterprises, making it more difficult to collect, store and transfer the recovered solvents, and the current re-refining and reusing of centralized transportation is not yet mature. In addition, with the current collection of VOCs sewage charges, the number of clear solvent recovery, the part transparent, gravure more pressure.

(5) economy

Recycling costs are basically acceptable, such as the cost of 1 yuan / kWh, steam costs 200 yuan / ton calculation, the cost of recovering 1 ton of solvent is about 1,500 yuan / ton (simply recover the cost of the solvent, such as purification but also increase 500 ~ 700 Yuan / ton). However, due to the recent sharp price cuts of petrochemical products, the value of recovery solvents will drop drastically. As a result, the market will quickly become smaller and the sale will be very difficult. In the past, it could be sold without purification. Do not pay for the sale of hazardous waste, hazardous waste treatment but also increase the cost of about 5,000 yuan / ton, a substantial increase in recycling costs.

Scenario 2: Runner concentration 【Not recommended】

The main problems are as follows:

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