Waste Gas Treatment in Cigarette Packaging Printing Industry

Characteristics of Printing Equipment in the Cigarette Packaging Industry

1. Intaglio printing machine

The cigarette pack printing roll concave machine generally has 8-12 colors; The low-speed printing machine has a speed of 100-120m/min, consumes 30-50kg/h of ink and solvent per hour, and has a total exhaust volume of 25000-30000m ³/h; The high-speed printing machine has a speed of 150-180m/min, consumes 40-60kg/h of solvent per hour, and has a total exhaust volume of 35000-40000m ³/h;
(Calculated by ink volume on printing area: 120m/min × 0.92m × 60min/h × 2.5g/㎡ ÷ 38%=44kg/h)

3. Single gravure printing machine

A single sheet gravure printer generally has one color and uses UV ink. The ink contains 2% ethanol and cyclohexanone solvents. The planned capture and exhaust air volume is 2500m ³/h, and the exhaust gas concentration is 50-100mg/m ³;
Due to the presence of a large amount of UV curable resin in UV ink, it is not possible to adsorb and concentrate it.
Solution:
1. After being captured, it is directly sent into RTO incineration as organized waste gas;
2. Use UV photolysis+activated carbon adsorption/desorption device.
Sometimes when printing UV ink, a switching valve needs to be installed in the pipeline for different processing conditions;

5. Offset press

Offset printing machines generally have 6-9 colors, with 2-3 colors using soy ink and 3-4 colors using UV ink. The planned capture and exhaust air volume for each color is 2000m ³/h;
When printing soybean oil ink, the concentration of VOCS exhaust gas is 50-150mg/m ³ (including car wash water), and other unorganized exhaust gases are concentrated in the zeolite wheel and then incinerated in RTO;
When printing UV ink, the handling method is:
1. After being captured, it is directly sent into RTO incineration as organized waste gas;
2. Use UV photolysis+activated carbon adsorption/desorption device.
Sometimes when printing UV ink, a switching valve needs to be installed in the pipeline for different processing conditions;

Analysis of Waste Gas in the Cigarette Packaging Industry

1. Offset printing machines, single concave printing machines, and screen printing machines generally use UV ink, which contains a large amount of photocurable resin and is easy to cure on zeolite concentrated rotary molecular sieves, causing blockage of the rotary molecular sieves. Therefore, this part is treated with UV photolysis+activated carbon adsorption/desorption process to meet the standards and then discharged through the chimney. The heat source of activated carbon desorption is heat exchange with RTO purification exhaust and supplementary electric heating or zeolite concentrated rotary hot air heat exchanger or RTO high-temperature air;
2. The cigarette label gravure printing machine has the characteristics of large exhaust volume and low concentration. Even after equipment modification to reduce air and increase concentration, the concentration is still not high, and it affects the dryness and solvent residue of the gravure printing machine. Therefore, both organized and unorganized collection are sent to the zeolite concentration rotary wheel for treatment;
   The water pine paper printing machine has no organization, and the exhaust concentration in the ink mixing room and hazardous waste room is correspondingly low. Therefore, it is also passed into the zeolite concentration wheel for adsorption and concentration treatment. The purified clean gas is discharged through the chimney to meet the standard.
   Due to the fact that the adsorption efficiency of the zeolite concentration wheel is highest when the temperature is ≤ 40 ℃ and the relative humidity is ≤ 70%, an additional surface cooling device (such as a water containing cooling tower) is added for higher temperatures to ensure that the temperature and relative humidity of the exhaust gas are in the optimal state.
   The desorption heat of zeolite concentration wheel comes from the rotary valve type regenerative oxidation furnace (RTO);
3. The water pine paper printing machine has a large exhaust volume and a high concentration of VOCs in the exhaust gas. Therefore, the hot air system of the printing machine is modified with LEL to reduce exhaust and increase exhaust gas concentration. The collected exhaust gas is sent to the rotary valve type thermal storage oxidation furnace (RTO) for direct combustion. After combustion, clean air is discharged through the chimney to meet the standard.

Management route of water pine paper printing machine

Water pine paper printing machine or gravure printing machine oven LEL air reduction and thickening

LEL principle of reducing wind and increasing concentration

Principle and explanation of LEL air reduction and thickening for water pine paper printing machine or gravure printing machine oven

characteristic:

1. The system is linked and controlled with the printing machine operation, which is more energy-efficient.
2. The exhaust air volume of the whole machine is automatically controlled by negative pressure.
3. The exhaust valves of each group are linked with the signal of the color group fan.
4. The opening of the air valve can be adjusted through the human-machine interface to ensure that the negative pressure of the oven does not blow air.
5. The LEL sensor ensures concentration safety.
6. High end products come with automatic ink volume analysis, which can automatically adjust the opening of the air valve to achieve energy conservation and emission reduction.

Principle and technical characteristics of box type LEL for reducing wind and increasing concentration

Workshop unorganized partition plan

Unorganized dispersion points of production equipment

As shown in the above figure, the unorganized exhaust gas emission points of the rolling machine include: exhaust gas brought out when the material film leaves the oven, exhaust gas leaked out due to poor sealing of the oven, exhaust gas evaporated from the ink tray, exhaust gas evaporated from the ink tank, and exhaust gas evaporated from the solvent turnover container;
Methods to reduce unorganized exhaust emissions from rolling machines:

• 1) Add a suction duct to the discharge port of the oven, and the absorbed exhaust gas is introduced into the organized exhaust gas circulation system of the oven;
• 2) Strictly establish negative pressure in the oven, add a windproof flange at the outlet of the oven guide roller, and improve the sealing strip of the oven;
• 3) Cover the ink tray, ink tank, and seal the solvent turnover container;
• 4) Maintain a constant temperature of 26 ℃ and a constant humidity of 55% in the workshop;

Production equipment without organized collection partitions

Classic Cases