Application of traditional Chinese medicine in the

2022-08-26
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Application of traditional Chinese medicine in the treatment of paint waste

during the paint spraying process, it is determined that the concentration of paint mist and organic solvent discharged from the paint booth is 300 ~ 200mg/m3. The production of paint mist and organic solvent gas brings secondary pollution, which directly affects the surface quality of painted objects and the health of operators. In order to further enhance the efficiency of products and damage the surrounding air and environment, people have designed wet paint mist treatment equipment and its supporting paint mist coagulant, so that the paint mist removal effect can reach 95%, effectively protecting the environment

nowadays, the coating workshop has advanced waste paint treatment technology. Generally, each paint booth is equipped with a separate waste paint treatment system, and the paint booth adopts venturi type. Adopt advanced system tank and suspension tank slag scraper; The system tank has the function of automatic water replenishment, which is set according to the actual demand; Automatically replenish water to the cleaning room and airtight seal room and reduce the dust in the paint booth; It can automatically increase the dosage according to different performance settings of the paint; The standby tank is set to facilitate the reversal of the system tank and reduce the discharge of circulating water during maintenance. The process parameters of waste paint treatment in the coating workshop are completely set, controlled and monitored by the computer emos system. At the same time, the emos system has the functions of setting, control, display, alarm and recording, and can upload the data to the central control room. The system tank operation display and dosing station display are shown in Figure 1 and Figure 2

application of agents in waste paint treatment

1 Paint mist coagulant

after selecting a suitable paint mist coagulant, it can effectively control the phenomenon that the paint adheres to the interior of equipment, pipelines and pump bodies, resulting in blockage of water and gas paths, making the paint mist purification system unable to operate normally. The paint mist condenses into crisp lumps in the water, floats on the water surface, and is salvaged regularly to ensure the normal operation of the equipment. Good paint mist coagulant needs to be diluted 3 ~ 5 times with water and mixed evenly before use. Paint mist coagulant should be added to the pump suction leading to the spray room through the metering pump

2. The high polymer flocculant

hydraulic source is used to supply high-pressure oil to the servo system

the high polymer flocculant is diluted 300 ~ 500 times with water and used after mixing evenly. The high polymer flocculant should be dripped at the suction port of the suspension pump or at the backwater torrent. The pH value of circulating water should be kept between 7.5 and 9. Paint mist coagulant and macromolecule flocculant should be added evenly from each shift of production to the end of each shift of production

3. The purpose of painting circulating water treatment paint mist coagulant

a large amount of paint mist and organic solvent gas are produced in the painting process, which affects the health of personnel and pollutes the surrounding air and environment. The paint mist and organic solvent discharged from the spray room are 300 ~ 200mg/m3, and the removal rate of organic solvent and paint mist can reach 95% after using coagulant. If the coagulant is not used, the paint will adhere to the equipment, pipeline and pump body if it is not coagulated, resulting in the blockage of water and gas paths, making the purification equipment unable to operate normally. After adding the coagulant, the paint will be condensed into soft lumps and float on it, which can effectively inhibit the growth of bacteria and algae in the circulating water, reduce the suspended solids in the water, and maintain the purity of water quality

Figure 1 system slot operation display

4 Reaction mechanism

the effect of adding flocculant: it has a good interception effect on paint mist; It has a good adsorption and destruction effect on the intercepted paint mist, including the resin and solvent, and can make the paint agglomerate into blocks; Most of the agglomerated slag floats upward, which is convenient for slag discharge

in order to make the coagulant play the above role, paint mist coagulant usually contains inorganic alkali, salt and a series of other substances. This mixture and the solvent, resin and pigment in the paint will carry out a series of complex physical and chemical reactions, of which the most important reaction is saponification reaction. Saponification reaction can effectively destroy the paint structure, eliminate viscosity, and produce a kind of soap substance that is insoluble in water and non sticky. The coagulant contains surfactant, which can act with the bubble film to make small bubbles form large bubbles, which are easy to break on the water surface, so as to achieve the purpose of defoaming. Excessive coagulant can produce too much foam. When the foam exceeds a certain amount, the equipment will not work. Adding coagulant reasonably can avoid producing too much foam. A certain amount of foam is needed, and a small amount of foam can effectively accelerate the effect of the agent on the paint, and make the paint residue float on the water. The paint mist coagulant also contains metal corrosion inhibitor to prevent the corrosion of chemical agents on pipelines, pumps and other equipment. Too low pH value will have a corrosive effect on the equipment. The control of pH value is mainly achieved by inorganic alkali. If the pH value is too low, the saponification reaction cannot be carried out, the paint cannot be damaged, and the viscosity cannot disappear, which will corrode the equipment; If the pH value is too high, there will be "excessive damage", and the paint will be dispersed into small particles, which will not form a block, but form a colloidal suspension, and the water content of the slag is too large. According to the observation, it is the best to control the pH value between 7 and 8

5. Dosing location

choosing the best dosing location can maximize the role of the drug, avoid drug waste, and save costs. The coagulant should be at the pump suction of the clean water pump. The drugs can be better dispersed in the water after being stirred by the pump blade to give full play to its maximum effect. Flocculant should be added at the backwater torrent or at the suction of slag making pump

6. Dosing method

before adding drugs, first understand the production status of the day, and then master the overspray of paint. The overspray volume of rotating cup is 25% - 30%, and that of manual spray is 60% - 70%. It is also necessary to master the amount of paint used in a single car. The coagulant is added according to 10% - 20% of the overspray. The measurement system will automatically reset, that is, the dosage = the amount of paint used in a single car × Overspray volume × (10%~20%)。

Figure 2: analysis of abnormal phenomena in dosing station

1 Reasons and solutions for incomplete removal of paint viscosity:

(1) the pH value is low, so it is necessary to add flake alkali and adjust the pH value to 7 ~ 8

(2) the dosage of paint mist coagulant is insufficient, so it is necessary to check whether the pipeline of the dosing system is blocked or the storage barrel is insufficient

(3) when the output suddenly increases, it is necessary to know the output of the spray room in time and adjust the dosage

(4) when the on-site operating conditions change, it is necessary to check whether there are abnormal conditions on the operation site

2. Reasons and solutions for paint residue not floating up:

(1) the pH value is low, so it is necessary to add flake alkali and adjust the pH value to 7 ~ 8

(2) the dosage is low, and the paint residue is not dispersed more effectively. It is necessary to increase the flow of paint mist coagulant to make it reach a certain concentration in circulating water

(3) the low flow or concentration of polymer flocculant makes the paint residue unable to coagulate and float up, so it is necessary to adjust the flow or concentration of polymer flocculant

3. The floating rate of paint residue is low

due to the low content of polymer flocculant in the water and the turbid water quality, the flow or concentration of polymer flocculant needs to be adjusted in the suspension and circulating water of paint residue

4. Reasons and solutions for turbidity of circulating water:

(1) often turbidity is the same as the low floating rate of paint residue. It is necessary to first increase the concentration of paint mist gel in water, and then adjust the flow or concentration of polymer flocculant

(2) occasionally muddy, when the paint residue left in the cleaning spray room returns to the circulating water, it takes several times to increase the flow of polymer flocculant in a short time

5. Bubble

causes and solutions:

(1) the pH value is high, and the flow of polymer flocculant needs to be increased

(2) the suspended solids in circulating water are high, so it is necessary to increase the flow of polymer flocculants

(3) the dosage of paint mist gel is high, so it is necessary to reduce or temporarily stop adding paint mist coagulant, appropriately increase the flow of polymer flocculant, and fill it normally after the bubbles disappear

(4) the dosage of polymer flocculant is too high, so it is necessary to reduce or temporarily stop adding polymer flocculant, and fill it normally after the bubbles disappear

(5) when the output is large, the dosage is also large, and the production is suddenly cut off, but the drugs are still being added. The addition of high molecular flocculant should be reduced or temporarily stopped, and it should be added normally after the bubbles disappear

(6) the circulating water contains unidentified substances, so it is necessary to detect the physical and chemical indicators of the water quality or replace the fresh water

6. The volume and taste of circulating water are relatively large

due to the color change in the spray room and the cleaning of the rotating cup or spray gun, it is necessary to increase the flow of paint mist gel agent to effectively disperse and wrap the solvent. (end)

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