Energy-saving technology in the elevator on the environmental transformation of coating line

Abstract: This paper introduces Hitachi Elevator solvent-based paints will be transformed into water-soluble paint electrostatic spraying electrostatic spraying process, the application of environmentally friendly raw materials and the coating produced by waste water, waste gas treatment.

Paper Keywords: coating line transformation, the elevator coating, Environmental Protection and energy saving, zero discharge waste water emissions
1 Introduction
Coating application is very common, can be said that painting is everywhere. Bring in people to enjoy the beauty of painting, while painting produced gas, waste water and waste but also to the survival of our planet environment pollution. The Elevator parts coating products require more coating components and larger, so use the paint more, with a corresponding coating exhaust byproducts, waste water and sludge is greater. to reduce waste emissions and protect the environment to achieve Environmental Protection coating, the world are working hard to explore with, Hitachi Elevator (China) Co., Ltd. in a highly responsible attitude to society to spend huge amounts of money into Environmental Protection work and achieved remarkable results.

Hitachi Elevator in China, Guangzhou, Shanghai and Tianjin have a manufacturing base, including Shanghai and Tianjin manufacturing base coating line in the beginning of the construction, Environmental Protection and energy conservation as the guiding ideology put into practice, the primer coating by electrophoresis, using water-based finish construction method of electrostatic spray paint, and paint line factory in Guangzhou was built in 2003, the spraying process is:
_ Transitional primer paint primer opposite the front spray paint, primer-class Ping-negative follow up painting spray paint a positive first-class Ping-Ping-curing varnish spray drying using a solvent-based paints, solvent-based paints are organic solvent as the carrier, itself contains more organic solvents, coating when the coating is also used to deploy and spraying cleaning solvent, so the spray drying process and the film will be a lot of VOC emissions. In order to reduce the environmental pollution caused by paint, to achieve Environmental Protection coating, the initial transformation of the transformation of the different options presented, Option One reference Hitachi Tianjin, Shanghai plant technology, this program due to transformation of a long cycle investment, the existing coating line can not use the basic equipment, affecting the production be denied. How to paint lines on the basis of the original effective transformation, transformation of painting line according to the company and guiding purpose: to Environmental Protection as the center, to reduce paint waste emissions, in particular, to reduce VOC emissions. from the technology, equipment and raw materials After several aspects of analysis and demonstration, the first from the source to reduce the generation and emission of pollutants, the former dealing with environmentally friendly materials, the use of solvent-based paints to water-based spray paint spraying, coating line equipment on the existing effective reform to meet the water spraying conditions, and improving and increasing the corresponding Environmental Protection facilities, with minimum capital investment, the shortest time to ask the successful completion of the transformation of the transformation, detailed in Figure 1.


2 using environmentally friendly raw materials
2.1 Pre-treatment processes
Pre-treatment is the treatment for painting must be processes, processing methods and the use of more types of chemicals, its main role is to increase the adhesion and the protective coating. Degreasing agent's main role is to remove the oil surface of the part , commonly used is the alkaline degreasing agent, degreasing degreasing agent mechanism is the surface of the part of the oil occurred with saponification, emulsification reaction and pro-surfactant hydrophilic surface of the oil to get rid of the principle of the oil, commonly used phosphate, silicate salt, alkali and surfactant mixture composition, surface adjusting agent's role is dealing with the formation of phosphate nuclei, the phosphate coating is more compact, has been using colloidal titanium salt, phosphate, phosphate processing technology is used primarily for increase its corrosion resistance, the use of zn-Ni ~ Mn containing cationic phosphating metal treatment solution. due to the production of elevator products ladder types, models are more parts need to paint the larger dimensions, the first treatment processes will generated waste water, sludge and other waste, including waste water containing phosphorus easily lead to eutrophication, zinc, nickel and other heavy elements are generally more difficult to get rid of the wastewater treatment process, sludge containing iron phosphate, zinc phosphate, etc., The waste water, waste treatment costs high, if the treatment effect not likely to cause secondary pollution. is easy to do on the discharge of waste water, waste treatment standards, reduce waste water, waste water emissions and reduce the salt content of heavy metal ions and to the following measures: pre-treatment device using a continuous transmission from automatic sprinkler ways to enhance production efficiency, shorten time of treatment processes, components, increased use of vertical suspension means the handling capacity per unit time, spray washing by counter-current mode, to ensure the quality of irrigation under the premise of reducing the amount of water, degreasers degreasing agent of low temperature to reduce the phosphorus content and phosphorus content of gas, the surface modifier used to reduce the replacement of long-term adjustment of the number of agents, phosphate using phosphate-free phosphate is different from the previous common Zinc phosphate treatment, the formation of various types of metal nano-metal oxide film, the film exhibits a blue-yellow and purple, the color due to thickness of coating, materials and treatment conditions vary, no phosphorus, nickel, manganese heavy metals, temperature treatment, sewage treatment to reduce the load, is a new Environmental Protection material, the oxide layer of rust resistance and film adhesion with the conventional zinc phosphate coating is comparable. coating line generated by pre-treatment process waste is mainly washed and washed 3 1 2 stations that generate a small amount of overflow water and solid waste phosphate residue, overflow water discharge to the wastewater treatment station for processing, phosphate residue of Japan presses for three-treatment by the press hazardous waste after the recall, the former dealing with energy saving measures in Figure 2.


2.2 The use of water paint spraying process
Water-based coating is a water carrier, mainly by water-based resins, fillers, solvents and additives composition, through color, mixing, grinding the mixture formation processes in Europe and other developed countries due to environmental regulations and the application of more more than the application of waterborne coatings in China has just started, mainly small car plant in the coating with water-based primer and paint (varnish is still oil paint.)
Hitachi Elevator (China) Co., Ltd. used spray primer, paint and varnish are all made of water-based coatings, mainly by the performance of water-based acrylic resin, amino resin, pigment, solvent, deionized water and additives composition of the original paint has been tested and VOC content of less than 50g/kg, deployment and change color paint all use clean water. using electrostatic coating spray equipment, construction, wide range of conditions, ambient temperature not less than 5 ��, relative humidity not more than 95% of the environmental conditions can be spray, environmental conditions, most of the country can meet its requirements. use water-based paint curing temperature decreased after the transform the use of solvent-based paint before the curing temperature (165 ~ 5) ��, Use water-based paint curing temperature (145 ~ 5) oC. According to statistics, the higher the curing temperature, the greater the amount of gas consumed, curing temperature dropped from 160clC 140 ��, per hour can save gas 20m. to be of special note is water-based varnish coatings currently in the elevator industry is not a precedent for the practical application of electrostatic spraying, because the role is to improve the varnish coating the surface gloss, decorative and increase its scratch resistance, water-based varnish applications in early, there is The problem is caused by water-based varnish resin itself low solid content, after the wet film spraying the wetting and flow SUI poor, low coating fullness, can be worse in the construction of, especially after the wet film thickness of coating difficult to determine, the Department of coating after drying corner prone to blisters and pin holes, to the promotion and application of water-based varnish to bring a degree of difficulty. In order to solve the above-mentioned water-based varnish problem, from the electrostatic spraying process by adjusting the screw on cup rotation speed gun, spray pressure, paint viscosity and paint spit water volume, by improving on the formula from the coating, leveling agent, solvent, defoamer and resin components, etc., after repeated adjustment test, and ultimately achieve the application requirements for the successful application of water-based varnish laid the foundation.

3 with three spray a baking the wet-wet process
Primers specific electrostatic spraying process is leveling through natural conditions directly after spraying paint, spray paint and then after leveling varnish. Wet-wet spraying of the biggest advantages is to save energy than normal spray a baking process of a energy savings of about 50%. waterborne paint wet-wet process with respect to the wet-wet oil paint spraying process more difficult, because the primer's primary role is protective, the primary role is to paint decorative, wet-wet technology primer is dry rate and spraying process parameters must be controlled within a certain range, or reverse osmosis will cause paint to finish, the film is not enough sag, and defects such as film thickness, due to solvent-based paint before the transformation according to the environment adjusted for changes in the conditions to adjust the evaporation rate of diluent components to control the rate of the paint film is dry, and water-based paint thinner is water, not like oil paint thinner by adjusting the ingredients as to adjust the table dry rate. to meet the water wet-wet paint spraying process requirements, by adjusting the composition of water-based paint and coating process parameters to meet the requirements of this spraying process.


4 spraying equipment modification
4.1 The transformation of the central system for the paint
Transformation of the former for the paint coating line with the central system, which uses a set of primer for the paint spray booth equipment, paint spray booth for sharing a paint device, use a central system for the paint coating to facilitate deployment of the benefits, coating application viscosity stability, savings in manpower, but there is color change and cleaning difficulties, from the central room for the paint to the painting room of the pipe longer, increasing maintenance costs and other shortcomings. using electrostatic spraying water-based paint, paint must be available for the transformation of the system to meet the water electrostatic paint spraying needs.

(1) solvent-based paints for paint systems
Transformation of the former uses a central system for the paint, primer, paint and varnish the paint bucket for all placed in a room for paint, and paint for the paint room and the distance between the far.

Central for the paint systems for paint barrels from the pipe to the spray chamber made of stainless steel pipes, high pressure due to piston distance for Qi, and there is reflux pipeline, due to transformation of the former uses a solvent-based paints, paint than the resistance itself, large, for the 40 ~ 100MD,, so the paint itself is not conductive, the use of water-based paint, in his own conduct electricity, but the gun high-voltage discharge along the pipeline, it is necessary for the original paint system transformation.

(2 ice coatings for paint systems
Conductive water-based paint itself, but the gun high-voltage discharge along the pipeline, it is necessary for effective insulation system for the paint. To meet the insulation requirements, each individual spray booth for paint to increase, the reduced supply pipe to the spray paint distance of the gun, in principle, for water-based paint coating pipe as short as possible, but considering the convenience of operation, in the space and equipment layout of the permit, as short as possible as well.

Increase the track sprayer 4.2 Primer
To ensure product quality, improve parts of the painting negative bending bit rate and coating efficiency, reduce waste and emissions, increased complement automatic tracking machine instead of spray components of artificial fill bit negative bending spray, saving manpower, protection the human health.

Auto touch-up painting track machine, you can detect the location of spraying components and implementation of automatic tracking spraying, spraying the corners bit special to make up for electrostatic spray painting the corners bit rate of the phenomenon is not high, the working principle is detected by the air spray gun parts arrive , the lifts run synchronously with the conveyor, while reciprocating spray gun start.

Water-based automatic spraying machine electrostatic voltage generator set built-in, spray air pressure of not more than 0.1MPa, painted more than 75%, can be part of the spray width and length of the implementation of the detection and automatic spraying, thus saving the paint.

4.3 The use of vortex-type water curtain spray booth water
Water vortex-type water curtain spray booth shown in Figure 3.



Water vortex-type water curtain spray booth spray booth by the body, ventilation system, water circulation system, water curtain, the vortex into the bottom ash handling system and the spray body. Spray chamber body external dimensions: 5500mmx4800mmx5100mm, the front fitted with large glass windows, the other three walls made of stainless steel frame, stainless steel mosaic.

After the primary air supply system is to filtered air and a spray chamber to the top of the grading room, then through the secondary filter after the pressure chamber were evenly to the spray booth, exhaust system is to rule out the paint produced over-spray fog, produced specifically for the over-spray paint sprayer mist, after a strong exhaust fan and water pumping power of the vortex curtain of water vortex plate after mixing, paint residue and water soluble VOC solvent to the painting room of people circulating water, insoluble in water, VOC is discharged into the activated carbon treatment plant, air supply volume according to the following formula to determine the size: p = 3600FV (F for the operating area of ​​the floor area, m, V is wind speed, m / s), the general required to maintain positive pressure spray room, spray booth to ensure a clean environment.

Spray booth curtain panels from the bottom ash handling system, gas and water separation chamber and vortex panels, curtain panels and vortex should be noted that the gap between plate and rotating plate curtain lowest gap with circular pool water, or remove the mist results will be worse. After treatment, the exhaust gas vortex separator into the room, water vapor and not the net addition to the mist again separated, with VOC emissions is the exhaust. separator chamber retaining plate width and angle with a mist of water particles and the impact effect of the exhaust flow on diffusion speed and directly affects the paint mist separator capture rate and the rate should also be noted. mist spray booth is completely separate exhaust gas treatment effect directly affect the follow-up.

Links to Research Papers Download http://www.hi138.com 5 Environmental Protection Equipment
Environmental Protection on the coating process from raw materials and reduce waste emissions, and emissions is much lower than the national standards, but Hitachi Elevator (China) Co., Ltd. in a highly responsible attitude to society, while the use of environmentally friendly coating, the coating installation of wastewater generated in the production process, waste gas and waste residue are carried out effectively addressed.

After spraying water-based paint on a small amount of VOC emissions from the activated carbon adsorption treatment, paint, waste water and domestic wastewater generated by wastewater reuse after treatment (see Figure 4). Here's painting generated waste water, waste gas and waste residue described in detail for reference .
5.1 Waste gas treatment equipment
5.1.1 Waste gas treatment control
(1) across the board with PLC control, the situation can be monitored exhaust gas treatment (show process, fault alarm.) Two kinds of automatic and manual control mode, the automatic control mode, press the auto-start button, the system will be the order of automatically put into operation, the manual control mode, the device can be independently activated. if failure occurs, can be sound and light alarm. in the gas export concentration detection device installed, when the emissions exceed the value of its provisions, it can be automatically de- go along with the police.

(2) adsorption function. Activated carbon adsorption unit designed for dual-layer adsorption tank, when a tank saturated adsorption, desorption can be, and can start another adsorption adsorption, which can be recycled repeatedly, effective absorption of organic emissions. The size of tank and activated carbon adsorption amount is based on the amount of exhaust to its design, its processing speed Zuihao not more than lm / s. In order to prevent Huoxing Tan poisoning, should be equipped with watertight dust filter.

(3) desorption. When the post-activated carbon saturated organic matter, cease to inhalation of organic waste gas, through the activated carbon bed up into the steam stripping, activated carbon in the organic matter from the out, that is, desorption. Can restore its activity in the activated carbon, that is regeneration. desorption of organic waste through the post into a liquid after the condenser for recycling, reuse and can be activated carbon to adsorption.

5.1.2 Waste gas treatment process
Waste gas treatment process shown in Figure 5.



5.2 Wastewater Treatment
(1) 100% recycling of waste water points that
The main source of wastewater plant is the production of wastewater and domestic wastewater, including wastewater is mainly the production of skim coating, phosphating, painting, and after washing produce wastewater, sewage mainly from the canteen, toilets and sanitary cleaning. Overall design of the factory is no sewage plant outfall. in the production and living waste water generated during the wastewater treatment equipment after the standard is lower than tap water after it is called in the water, the water used in factories as part of the green, flushing, road cleaning and maintenance fish, part of the depth of the treated water back through the coating line used to be 100% recycled instead of foreign emissions.

(2) wastewater treatment process
Wastewater treatment process shown in Figure 6.


6 Conclusion
(1) the project implementation difficulties and harvest. Water-based primer, paint and varnish wet-wet spraying process and the corner bit up painting machine automatically track the successful application of environmentally friendly water-based paint in the same time, the coating produced The by-product of wastewater, waste gas processing, to achieve a coating wastewater, waste gas of zero emissions, set an example for environmental spraying.

(2) comply with environmental safety requirements. Spraying water-based paint production line application of the project is mainly based on the transformation of environmental considerations, oil paint itself contains 20% to 30% of the organic solvent used in paint thinner to be used, the deployment ratio paint: thinner = 1.0:0.5, the main component of solvents and thinners are alcohols, ethers, esters and a mixture of benzene, etc., most of these substances are toxic, paint spraying and drying process in the most volatile in the into the atmosphere, causes environmental pollution, harm to human body. And, after using water-based paint, which itself contains only 5% to 10% of the alcohol and other organic solvents, and deployment time by spraying water, alcohol is completely soluble in water, in spray paint mist over the course of adsorption by the curtain most soluble in water, emissions of organic solvents greatly reduced compared with oil-based paint, the effective protection of the environment. while water-based paint does not belong to dangerous goods, not combustion and explosion, the use of security.

(3) With the introduction of national environmental policies and the improvement of people's environmental awareness, water based coating applied will be universal attention, but also encourage the development of energy conservation in line with national industrial policy.

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