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VOCs sources are complex, involving many industries, large quantities and wide areas, including petrochemical, chemical, industrial painting, packaging and printing industries, and...

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One factory one policy working idea?

VOCs sources are complex, involving many industries, large quantities and wide areas, including petrochemical, chemical, industrial painting, packaging and printing industries, and a variety of substances, common components include hydrocarbons, esters, alcohols, ketones, amines and so on. At the same time, the production process of different industries is very different, and the exhaust gas emission air volume and concentration have different emission conditions such as continuity and intermittency, and the emission characteristics are complex and changeable. Therefore, the traditional methods and concepts of SO2 and NOx governance are difficult to solve the current VOCs pollution control problem, and it is necessary to solve the VOCs governance problem through a more refined and personalized technical approach, and one plant one program has become the best choice.

Atmosphere 53 document: Implementation of the \"one plant, one policy\" system

In the \"Comprehensive Treatment Plan for Volatile organic Compounds in Key Industries\" issued by the Ministry of Ecology and Environment in June 2019 (No. 53), it was clearly proposed to further implement the fine control of VOCs and implement the \"one plant, one policy\" system.

Implement the \"one plant, one policy\" system. Local governments should strengthen assistance and guidance for enterprises, organize experts to provide professional technical support for local enterprises with large pollutant emissions, strictly check, guide enterprises to prepare feasible pollution control plans, clarify the emission reduction requirements for the whole process of raw and auxiliary materials replacement, process improvement, unorganized emission control, waste gas collection, and pollution control facilities construction, and measure investment costs and emission reduction benefits. Provide technical services for enterprises to effectively carry out VOCs comprehensive management. Key regions should organize local enterprises with large VOCs emissions to carry out the \"one plant, one policy\" program preparation work, and basically complete by the end of June 2020; We will carry out post-assessment work on the effectiveness of governance in a timely manner, and the subsidy policies introduced by various localities should be closely linked to the effect of emission reduction. We will encourage local governments to carry out mandatory cleaner production audits in key industries.

VOCs \"one factory, one policy\" development preliminary situation

March 2014 (Shanghai)

Shanghai issued the \"Carry out the pollution control work of key Enterprises with VOCs emissions in the City\

July 2016 (Guangdong Province)

The Guangdong Provincial Department of Ecology and Environment issued the Notice on the \"One Plant and One policy\" governance work of key supervision enterprises of volatile organic Compounds from fixed pollution sources, requiring the formal promotion of one plant and one policy of VOCs governance. At present, Guangdong has accumulated rich experience in this field.

August 2016 (Suzhou)

Suzhou Municipal Bureau of Ecological Environment issued the \"Petroleum refining, petrochemical and synthetic resin industry enterprises to prepare VOCs\" One plant and one policy \"upgrading plan, officially promoting one plant and one policy work in Suzhou.

August 2019 (National level)

The \"Comprehensive treatment Plan for volatile organic Compounds in key Industries\" issued by the Ministry of Ecology and Environment (No. 53 in the Atmosphere [2019]) requires that key regions should organize local enterprises with large VOCs emissions to carry out the \"one plant and one policy\" program preparation work, which will be basically completed by the end of June 2020.

June 2020 (nationwide)

As of the end of the day, in addition to the above provinces and cities, more than 100 cities in Shandong, Zhejiang, Sichuan, Fujian and other places have successively carried out VOCs \"one plant, one policy\" emission reduction plan preparation and management work, VOCs emission reduction \"one plant, one policy\" work has been gradually promoted nationwide.

The \"Technical Guide for the preparation of One Plant and one Policy for the Comprehensive treatment of Volatile Organic Compounds\" group standard was approved and the national soliciting units to participate in the compilation

VOCs one plant one program writing logic

Preparation of volatile organic compounds \"one plant, one policy\

What should be included in a complete and standardized \"one factory, one policy\" program?

What are the common problems in the solution and the recommended changes?

Let's take a look at it in detail, and first talk about the main points of the outline of a factory and a policy:

VOCs key enterprises \"one factory, one policy\" outline

Write steps, Outlines and key points

I. Overview of the enterprise

It should include enterprise profile (i.e. enterprise name, enterprise address, industry, production time, main products, production scale, contact information, etc.), plant layout (i.e. layout of main production facilities and auxiliary facilities, such as production workshop, production line, sewage station, cooling water system, etc.), and storage and transportation of dangerous goods, raw materials and finished products, etc. The geographical location of the plant and the layout of the plant are attached.

Second, the production process

(A) production process. This paper mainly introduces the production process of the enterprise and the main links of VOCs emission, with the production process flow chart and VOCs emission node of the enterprise.

(2) Product output. Describe the company's main product types, production capacity and output in the latest year. If the products or intermediate products produced by different production workshops and production lines are different, the product output of each production workshop and production line should be provided separately. The painting industry should focus on the production capacity and situation of painting, leveling and drying processes.

(3) the amount of raw and auxiliary materials. According to the production process, the main types of raw materials and the amount of the previous year should be described in detail by the production section, and the scale of raw and auxiliary materials should be attached.

Enterprises involving the use of organic solvents should explain the type, VOCs content and dosage of organic solvents (including paints and coatings) in each section.

Enterprises with storage tanks should explain the number of storage tanks, the type of storage tanks (including horizontal, arch, internal floating roof, external floating roof), the type of liquid stored and its annual storage capacity, explain the maintenance of storage tanks, and can be attached with pictures.

Chemical enterprises should explain the number of sealing points of pipelines, valves, pumps, compressors, pressure relief valves, connection ports, open pipes, sampling connection ports and other devices, describe the maintenance of sealing points (such as whether there is damage, etc.), whether to carry out leak detection maintenance (LDAR) and other related work. Enterprises with chemical equipment should explain the opening and closing conditions of chemical equipment, emptying methods, and whether they are equipped with recycling and purification devices. Enterprises with monitoring of the emptying process should provide monitoring concentrations.

Chemical enterprises with sewage treatment facilities should provide sewage treatment methods, whether to cover, open area and whether there is waste gas treatment information.

Third, VOCs production and pollution link and control status

(1)VOCs generation source analysis. Petrochemical and chemical enterprises should analyze the organic liquid storage tank and blending volatilization loss, organic liquid loading and unloading volatilization loss, equipment static and dynamic sealing point leakage, waste water treatment process escape, combustion flue gas, torch discharge, circulation cooling system release, abnormal working conditions discharge, accident discharge, sampling process, process unorganized discharge, process organized discharge and other links of emission. Enterprises using solvents should explain all aspects of VOCs emissions in the process of solvent storage and use.

At the same time, it should explain the management level of the production line, the closed state of the production device and the production workshop, and the exhaust gas collection situation of the production line outlet, and attach the production workshop site photos.

(2)VOCs control status. The quantity and height of the discharge ports in each workshop of the enterprise, the types of the main pollutants discharged, the collection of the discharge ports of the enterprise and the sources of the waste gas are explained. Describes the treatment facilities of the discharge ports of each workshop, including treatment technology, equipment model, manufacturer, service life, types of pollutants to be treated, and maintenance of treatment facilities.

Test or online monitor emissions from organized outfalls (before and after treatment if there is a treatment setting) to assess pollutant emissions and their compliance. The detection\/monitoring species should include non-methane total hydrocarbons, benzene, toluene, xylene, tritoluene and other major VOCs species, while the operation status of waste gas treatment facilities should be synchronously monitored (treatment efficiency), and the detection or online monitoring report should be used as an attachment.

Note: activated carbon adsorption device should provide activated carbon replacement frequency and disposal method, combustion method VOCs treatment device should provide fuel, combustion temperature and other combustion conditions, need to regularly replace the adsorbent, catalyst or absorption liquid, need to provide detailed purchase and replacement ledger, provide a copy of the purchase invoice.

Fourth, VOCs emissions accounting

Based on the scale data of production and operation activities in the previous year, the VOCs emissions were calculated according to the prescribed estimation method. For materials involving VOC emissions, prepare a material balance diagram (table), and general solvent use enterprises should do material balance.

5. VOCs comprehensive management plan that has been (to be) implemented

(1) Source control plan

1, low volatile raw material adjustment

The surface coating industry encourages the use of water-based coatings, high-solid coatings, powder coatings, UV-curable coatings, etc., and limits the use of solvent-based coatings;

The coatings, inks and adhesives manufacturing industry encourages the expansion of the production scale of low-solvent, low-toxicity and low-volatility coatings;

Alcohol (no benzene, no ketone) inks and water-based inks in the packaging and printing industry replace solvent-based inks, and UV coatings with high solid content are used to print iron cans.

2. Process adjustment

Encourage enterprises in the VOCs emission contribution of production links to the relatively clean industry transfer, phasing out VOCs emissions of large production links;

The surface painting industry promotes the use of electrostatic spraying, high-flow low-pressure spray gun and other coating processes with high painting efficiency;

Coating, ink and adhesive production industry to increase the sealing rate of production equipment and production process, grinding, painting and other production equipment edge sealing rate requirements ≥90%, encourage the use of closed integrated production technology;

Packaging and printing industry to promote the use of solvent-free composite process instead of dry composite process.

(2) Process control plan

Should strengthen the storage, loading and unloading, use of the process of tightness, unorganized waste gas should be collected, the collection rate is not less than 90%.

The organic chemical industry should strengthen the overhaul and maintenance of valves, flanges, pump and compressor seals, pressure relief equipment and other equipment, establish leak repair technology (LDAR), and develop leak repair plans, and implement them regularly.

(3) End treatment plan

Organize the VOCs governance of each production workshop and process link of the enterprise, and formulate and implement the technical plan of governance for the workshops and links without governance facilities;

Where there are existing treatment facilities but they do not meet the requirements of national and provincial volatile organic matter emission standards, technical specifications and treatment technical guidelines, technical reform plans shall be formulated and implemented;

Existing treatment facilities and in line with the relevant technical specifications, emissions supervision should be strengthened, and the establishment of enterprise VOCs environmental management information ledger as required.

(4) Daily supervision plans

1, establish the enterprise VOCs management account

Establish a VOCS-related information management ledger for each enterprise and update it annually, and the VOCs governance facility must be maintained in accordance with the method provided by the manufacturer, and fill in the main information and maintenance records. Such as: activated carbon adsorption desorption device should provide activated carbon replacement frequency and disposal method, combustion method VOCs treatment device should provide fuel, combustion temperature and other combustion conditions.

2, put forward the enterprise VOCs emission self-examination plan

Each enterprise should put forward a self-inspection plan for VOCs emission links and treatment facilities. The organic chemical industry should strengthen the overhaul and maintenance of cooling towers, valves, flanges, pump and compressor seals, pressure relief equipment and other equipment, establish leak repair technology (LDAR), and develop leak repair plans.

Solvent applicable industries should establish VOCs solvent management ledger and treatment facility management ledger and update them regularly. The solvent management stamp records the name, manufacturer, model, purchased amount and usage of raw and auxiliary materials such as paint, diluent, curing agent and cleaning agent every month. Common problems in the preparation process are summarized as follows:

Frequently asked questions and Suggestions

Note: Shanghai VOCs2.0 version \"One factory, one policy preparation\" outline

As we all know, at the beginning of March this year, the Shanghai Municipal Bureau of Ecological Environment issued VOCs2.0 version of the one plant one policy outline requirements, specifically to adopt the \"program development technology assessment tracking and promotion\" three-stage progressive technical route, the enterprise according to the VOCs comprehensive management \"one plant one plan (2.0)\" outline requirements to prepare the plan and organize the implementation. It can be compared to find that the overall outline is similar to the above VOCs1.0 version, but the VOCs2.0 version especially focuses on the content requirements of \"VOCs comprehensive emission reduction\

The following is the outline of VOCs comprehensive management \"One plant one plan (2.0)\" :

Common ten industries VOCs waste sources and characteristics

VOCs \"One factory one plan\" preparation can be referred to

The following summarizes the VOCs generation sources and characteristics of the top ten VOCs emission industries in the electronics industry, pharmaceutical industry, paint manufacturing, ink manufacturing, adhesive manufacturing, wood processing, furniture manufacturing, transportation equipment manufacturing, leather manufacturing, and footwear industry, and focuses on the VOCs pollution sources and emissions chapter in the VOCs one-plant-one-program preparation. In particular, the compilation of the chapter of VOCs one-plant-one-solution 2.0 version currently implemented in Shanghai has a great reference role. In addition, VOCs engineering governance solutions for these industries also have targeted reference.

First, the electronics industry

The types of electronic products mainly include electronic special materials, electronic components, printed circuit boards, semiconductor devices, display devices and optoelectronic devices, electronic terminal products in six categories. Although these six categories of products belong to the electronic products manufacturing industry, due to their different production processes, different raw and auxiliary materials, the emission of characteristic pollutants and their concentrations are not the same.

Electronic special materials

Electronic special materials are specific materials used in the manufacture of semiconductor integrated circuits, various electronic components (including active and passive components, laser devices, optical communication devices, light-emitting diode devices, liquid crystal display devices and other electronic basic products).

ccl

The production process of copper clad plate is a waterless process, except for cooling water, inspection and testing departments will produce a small amount of sewage, other production processes will not produce sewage. The pollutants produced in the production process are mainly in the waste gas, which mostly comes from the volatilization of organic solvents such as acetone and toluene.

② Electronic copper foil

The main pollutants in the exhaust gas of electronic copper foil production are sulfuric acid fog and a small amount of benzene.

③ Quartz crystal rod (sheet)

A small amount of VOCs is produced in the cutting process of quartz rod and wafer processing due to the volatilization of diesel oil.

resistance paste

The resistance paste is mainly composed of conductive phase (functional phase), bonding phase (glass phase) and organic carrier. The main pollutants in production waste gas are VOCs and dust.

electronic components

Electronic components generally include: capacitors, resistors, potentiometers, inductors, electronic transformers, hybrid integrated circuits, control components, sensitive components, sensors, etc.

organic dielectric capacitor

VOCs exhaust gas is produced when organic dielectric capacitor paper is painted and capacitor surface is coated.

aluminium electrolytic capacitor

Aluminum electrolytic capacitors should be polished in the preparation stage, and a small amount of dust will be produced when the edge burrs are removed. Aluminum foil corrosion will produce hydrochloric acid gas, cutting will produce a small amount of dust.

tantalum electrolytic capacitor

During the sintering process of tantalum electrolytic capacitor and the welding of anode and cathode leads, VOCs exhaust gas is produced.

mica capacitor

During the production of mica capacitors, VOCs exhaust gas is generated during the aging process.

thin-film resistor

Thin film resistance should be polished in the production preparation stage, and a small amount of dust will be produced when the edge burrs are removed. The surface is coated with VOCs exhaust gas.

glass glaze resistor

In the production process of glass shaft resistor, VOCs waste gas is produced in the preparation of organic carrier, screen printing, drying and sintering and welding of outlet end.

⑦ Metal foil resistor

A small amount of VOCs exhaust gas is produced in the process of gluing and sticking foil in the production of metal foil resistor.

inductor

When the inductor is prepared, VOCs will be produced, including anhydrous ethanol, acetone, a small amount of xylene, etc. Waste gas and dust are produced in the soldering process.

electronic transformer

The electronic transformer has VOCs exhaust gas generated during dispensing and baking.

Printed Circuit Board (PCB)

Printed circuit board is an indispensable accessory in electronic equipment. According to the different number of wire graphic layers in the printed board, there are single-sided (only one layer of line), double-sided (with two-layer line) and multi-layer (with more than three layers of line), rigid and flexible boards have different layers.

semiconductor device

① Discrete devices, integrated circuits

The main processes of NPN triode, one of the most common bipolar tubes, are: oxidation, photolithography, N-type epitaxy, base diffusion, emission diffusion, Al metallization, chemical vapor deposition (CVD) passivation layer and other steps. The process is similar to that of IC production.

Integrated circuit manufacturing can be roughly divided into individual \"units\

Because the semiconductor process has high requirements for the cleanliness of the operation room, fans are usually used to extract various types of exhaust gas volatilized in the process, so the exhaust gas emission of the semiconductor industry has the characteristics of large exhaust volume and small emission concentration. These emissions can be divided into four main categories: acidic gases, alkaline gases, organic gases and toxic gases.

Acid and alkali exhaust gases mainly come from diffusion, CVD, CMP and etching processes, which use acid and alkali cleaning solutions to clean the wafer. At present, the most common cleaning solvent used in semiconductor manufacturing processes is a mixture of hydrogen peroxide and sulfuric acid. The waste gas produced in these processes includes volatile gases such as sulfuric acid, hydrofluoric acid, hydrochloric acid, nitric acid and phosphoric acid, and the alkaline gas is ammonia.

Organic waste gas mainly comes from photolithography, development, etching and diffusion processes, in these processes to use organic solution (such as isopropyl alcohol) to clean the surface of the wafer, its volatilization of the exhaust gas is one of the sources of organic waste gas: At the same time, the photoresist (photoresist) used in the photolithography, etching and other processes contains volatile organic solvents, such as butyl acetate, etc., which are also volatilized into the atmosphere during the wafer treatment process, and are another source of VOCs waste gas.

The toxic exhaust gas mainly comes from crystal epitaxy, dry etching and CVD processes, in which a variety of high-purity special gases are used to treat wafers, such as silane (SiH4), phosphane (PH3), carbon tetrafluoride (CF4), borane, boron trichloride, etc. Some of the special gases are toxic, asphyxiating and corrosive.

package

Packaging refers to the series of steps from the cutting of a single chip on a chip to the final packaging.

The waste gas produced by the packaging process is relatively simple, mainly acidic gas, epoxy resin and dust. Acid waste gas is mainly produced in electroplating and other processes. The baking waste gas is produced in the baking process after grain pasting and sealing. In the process of chip cutting, the scribing machine produces exhaust gas containing trace amount of sand dust.

Display devices and optoelectronic devices

From the point of view of pollution, the representative product of display devices is TFT-LCD (thin film transistor liquid crystal display device), and the representative product of optoelectronic devices is LED optoelectronic devices.

(1)TFT-LCD

The complete TFT-LCD production process mainly includes three parts: Array engineering (Array), color film engineering (CF) and box engineering (Cell).

②领导

Electronic terminal product

The production process of electronic terminal products mainly includes printed circuit boards (commonly known as board cards), assembly (board level assembly), machine assembly and product commissioning.

The main potential pollutants from the exhaust gas emissions of the electronic end product manufacturing industry are tin and tin compounds, lead and lead compounds and VOCs (benzene series and ethanol, isopropyl alcohol, acetone, etc.).

2. Pharmaceutical industry

The pharmaceutical industry belongs to the fine chemical industry, which is characterized by many production varieties, long production processes, large types and quantities of raw materials used, and low utilization rate of raw materials, resulting in a large amount of \"three wastes\" generated in the production process of the pharmaceutical industry, complex waste components, and serious pollution hazards. Pharmaceutical processes often need to use organic solvents to separate and extract drugs, so VOCs is one of the most important atmospheric pollutants in the pharmaceutical industry.

According to the production process, pharmaceutical can be divided into fermentation class, extraction class, chemical synthesis class, preparation class, biological engineering class and Chinese medicine class.

zymogen

Fermentation drugs mainly include: antibiotics, vitamins, amino acids and other classes. China has a complete range of antibiotics, the main dominant varieties are penicillin, streptomycin, tetracycline, chloramphenicol, oxytetracycline and other products.

The waste gas produced in the production process of fermentative drugs mainly includes fermentation tail gas, solvent-containing waste gas, dust-containing waste gas, acid-base waste gas and fetid gas produced by waste water treatment equipment. The main components of fermentation exhaust (including fermenter disinfection and sterilization exhaust) are air and carbon dioxide, while containing a small amount of medium material and the smell of mycelium when bacteria begin to produce antibiotics in the late fermentation period.

The organic solvent waste gas (such as toluene, ethanol, formaldehyde, acetone, etc.) produced by the production process of separation, extraction and refining is the main source of organic waste gas pollution.

Chemical synthesis

Its main varieties are synthetic antibacterial drugs (such as quinolones, sulfonamides, etc.), anesthetics, sedative hypnotics (such as barbiturates, benzodiazepines, carbamates, etc.), anti-epileptic drugs and other 16 types of nearly a thousand varieties.

The main waste gas pollution sources of chemical synthesis pharmaceutical enterprises include: organic non-condensing gas produced by distillation, evaporation and concentration section; The waste gas of organic solvent produced by synthesis reaction, separation and extraction process; The use of hydrochloric acid, ammonia water to adjust the pH value of the acid and alkali waste gas; Dust from crushing and drying; Foul-smelling gas from sewage treatment plants.

The main atmospheric pollutants in the chemical synthesis process include particulate matter, inorganic substances such as hydrogen chloride and ammonia, as well as organic raw materials and organic solvents used in chemical synthesis, such as benzene, toluene, chlorobenzene, chloroform, acetone, aniline, dimethyl sulfoxide, ethanol, methanol, formaldehyde, etc.

Extract class

Various basic substances (such as amino acids, peptides and proteins, enzymes, nucleic acids, sugars, lipids, etc.) that play an important physiological role in the organism are extracted, separated, and purified to produce drugs.

The air pollutants in the extraction production process mainly come from the dust generated during cleaning, crushing, drying and packaging. Solvents commonly used in the extraction section include water, dilute salt, dilute alkali, dilute acid, dilute acid, organic solvent (such as ethanol, acetone, trichloromethane, trichloroacetic acid, ethyl acetate, oxalic acid, acetic acid, etc.), which will involve the volatilization of organic solvent in the process of extraction, precipitation, crystallization, and in the process of acid hydrolysis, alkaline hydrolysis, isoelectric point precipitation, and pH mediation.

bioengineering

The use of microorganisms, parasites, animal toxins, biological tissues, etc., the use of modern biotechnology methods (mainly genetic engineering technology, etc.) to produce polypeptide and protein drugs, vaccines and other drugs, including genetic engineering drugs, genetic engineering vaccines, cloning engineering drugs and so on.

The waste gas of bioengineering production process mainly comes from the use of solvents, including toluene, ethanol, propanol, acetone, formaldehyde and acetonitrile, etc. The main stains are the exhaust air of bottle washing, solvent extraction, peptide synthesizer, laboratory exhaust, and drug dust in the preparation process. The fermentation process also produces a small amount of cellular respiration gas, mainly CO2 and N2.

Chinese medicine

With medicinal plants and medicinal animals as the main raw materials, according to the national pharmacopoeia, the production of TCM decoction pieces and Chinese patent medicine various dosage forms.

Among them, the core process is the extraction, separation and concentration of active ingredients. According to different solvents, it can be divided into water extraction and solvent extraction, in which solvent extraction is mainly ethanol extraction.

The waste gas from the production of proprietary Chinese medicine is mainly the drug dust produced by the process of crushing medicinal materials and the volatilization of some VOCs used in the pharmaceutical process, such as ethanol.

Pharmaceutical preparations

The active ingredients and excipients of drugs are mixed, processed and formulated to form various dosage forms of drugs. According to the dosage form, drugs can be divided into solid preparations, injections and other preparations. The main pollution source of waste gas in the production of solid preparation and injection is dust.

The atmospheric pollutants in the pharmaceutical industry mainly come from the production process of chemical apis, and the output of the top 20 chemical apis accounts for more than 80% of the total output of 24 chemical apis. Therefore, it is important to control the volatile substances involved in the top 20 varieties.

The top 20 organic solvents used by pharmaceutical companies

Third, paint manufacturing

The main raw materials in the production of coatings include the following parts: film forming substances (base materials), solvents, pigments, additives.

(1) Film forming substance: also known as the base material, is the main substance that makes the coating firmly attached to the surface of the coated object to form a continuous film. Commonly used film forming materials include alkyd\/polyester resin, phenolic\/amino resin, epoxy resin, acrylic resin, polyurethane, vinyl resin, cellulose resin, natural and synthetic rubber and other 18 categories.

(2) Solvent: mainly includes organic solvents and water, its main role is to dissolve or disperse the base material into a viscous liquid for paint construction. A coating variety can use either a single solvent or a mixture of solvents.

(3) Pigments: insoluble fine solid particles dispersed in paint, divided into coloring pigments and physical pigments, mainly used for coloring, providing protection, decoration and cost reduction; Including inorganic pigments, organic pigments, metal pigments, pearlescent pigments and luminous pigments, most of the inorganic pigments.

(4) Additives: Additives in the storage of paint, construction process and the performance of the formed paint film has an irreplaceable role. Commonly used additives are leveling agent, thickener, surfactant, plasticizer, drier, curing agent, antifouling agent, paint stripper and so on.

Coating types can be divided into solvent, water-based and powder type.

solvent based coating

The main resins used in coatings are alkyd resin, amino resin, acrylic resin, phenolic resin, epoxy resin, polyurethane resin and so on.

water-based paint

Compared with solvent-based coatings, water-based coatings mainly replace a large amount of solvents with water. Because water replaces the solvent, the washing process usually uses water, which increases the water reuse process but reduces the solvent use.

powder coating

Powder coatings are usually composed of polymers, pigments, additives and other mixed grinding processing. The preparation method of powder coating can be roughly divided into dry method and wet method. The dry method is mainly melt mixing method. The wet process includes evaporation, spray drying and precipitation. Evaporation method is to configure solvent-based coating, and then use thin film evaporation, vacuum distillation and other methods to remove the solvent to get solid coating, and then through powder, screening and classification to get powder coating, mainly acrylic resin based powder coating production, the use of more film evaporator and planetary screw extruder; Spray drying method is to configure solvent-based coating, grind, color, and then spray dry granulation or granulation in liquid precipitation to obtain powder coating.

Four, ink manufacturing

The ink is mainly composed of color, bonding material, additives and other components.

China's ink enterprises mainly printing ink, the industry usually according to the printing method will be divided into lithography ink, gravure ink, flexographic ink, relief ink, etc., which is based on lithography ink (offset ink) and gravure ink, the two kinds of ink production accounted for 60% of the total output, flexographic ink accounted for 7%, screen ink accounted for about 7%.

offset ink

Offset printing ink is the representative of slurry ink, platform machine relief ink, screen ink and iron printing ink are slurry ink. Based on the characteristics of pigment filter cake, pulp ink production process can be divided into dry production and wet production.

intaglio ink

Gravure ink is a typical liquid ink, flexographic ink and news ink are liquid ink, viscosity is very small. Usually there is no need to pre-mix, but direct sanding or ball milling. According to the characteristics of solvent use, it can usually be divided into water-based ink and solvent-based ink, and water-based ink is formed by using water or alcohol-based solvents.

Five, adhesive manufacturing

There are many kinds of adhesives with different compositions, but they all take adhesives as the main components, and are made of curing agent, plasticizer, diluent, filler and auxiliary.

Solvent-based adhesive

The process exhaust gas in the reactor is condensed by the condenser at the top of the device, and the condensate flows back into the reactor. The exhaust pipe of non-condensing gas is another emission source of VOCs exhaust gas. The packaging method adopts the general goods splashing filling, and the packaging mouth has a certain open mouth. This is the third source of VOCs emissions.

Water-based adhesive

The production process of water-based adhesives is usually formed by emulsion polymerization, that is, water is used as the external phase, and the monomer is dispersed in the water phase through micelles and increased solution occurs in the case of emulsifier or surfactant and full agitation. By adding a water-soluble initiator (such as potassium persulfate, etc.), once heated, the initiator begins to decompose and produce free radicals, which then causes polymerization or copolymerization of monomers in the micelle.

Hot cement

Under normal circumstances, the preparation of hot melt adhesive is to first heat the reactor to a certain temperature, and put the raw materials into the reactor in turn according to the feeding order. After heating and stirring evenly, if necessary, it should be vacuumed and filled with nitrogen to reach the rubber throat and discharge the material into the extruder. After the extruder, the rubber strip is pulled synchronously to the underwater pelletizer.

6. Wood processing

Wood processing industry, including sawn timber processing, veneer processing and wood-based panel manufacturing. Wood processing is mainly divided into sawn timber, wood chips, veneer processing and other wood processing of wood processing; Wood-based board manufacturing includes plywood, fiberboard, particleboard, etc.

In the wood processing industry, VOCs emissions are mainly based on wood-based panel manufacturing. The raw materials used in the production of wood-based panels include wood raw materials and non-wood annual and perennial plant fiber raw materials, which are the main raw materials constituting wood-based panels; It also includes a bonding material - adhesive used for recombining fibrous raw materials and bonding together to form artificial plates; And a variety of auxiliary materials added to give different properties of artificial plates, including water repellent, curing agent, flame retardant, anti-corrosion and anti-mold agent, filler and so on. Organic solvents commonly used in wood processing enterprises include: urea aldehyde (resin), phenolic (resin), formaldehyde, melamine and benzene series.

The VOCs exhaust gas in the wood-based panel processing industry mainly comes from the following links :(1) The emission of plywood VOCs is mainly in the veneer drying process and the process of gluing, sizing and hot pressing; (2) Particle board is mainly formaldehyde produced in the process of coating, hot pressing and sawing; (3) MDF organic waste gas mainly includes organic waste gas generated by hot grinding pulping process, organic matter generated by sizing and fiber drying process, and organic waste gas generated by fiberboard hot pressing process.

Seven, furniture manufacturing

In the furniture manufacturing industry, the output of wood furniture, metal furniture and upholstered furniture is the largest (accounting for about 95% of the total output of furniture). Furniture with major components made of wood or wood-based panel materials; Furniture with main parts made of metal materials; The main parts of upholstered furniture are generally made of elastic materials and soft materials.

The main VOCs emissions of furniture manufacturing enterprises are produced in the process of painting and coating, and common organic compounds include: benzene, toluene, xylene, butyl acetate, acetone, butanol, methyl isobutyl ketone, butyl alkyd.

8. Transportation equipment manufacturing

The largest VOCs production link in the manufacturing process of transportation equipment is the coating process. The base coating generally uses cathode electrophoresis coating, middle coating, surface coating a small number of enterprises use water-based coating, most of the solvent-based coating.

automobile making

Air pollutants are emitted in the process of electrophoretic primer drying, medium coating, color coating and varnish spraying and drying. 50% comes from medium paints, paints and varnishes, and 30% comes from cleaning solvents. Body sealing and wax spraying process due to PVC and protective wax curing rate is high, not volatile, pollutant emissions are relatively small. In the process of medium paint, color paint and varnish, about 80 to 90% are discharged in the spray booth and leveling room, and 10 to 20% are discharged in the drying room.

shipbuilding

Bicycle manufacturing

Air pollutants are emitted in the process of spraying primer, top paint and drying. In the process of spraying drying stage, about 65 to 70% of emissions in the spray painting section, 20 to 30% of emissions in the drying section.

Nine, leather products manufacturing

Leather products manufacturing includes leather clothing manufacturing, leather bags (bags) manufacturing, leather gloves and leather decorative products manufacturing, other leather products manufacturing and other categories, the pollutants produced in the production process are mainly air pollutants. Among them, the air pollutants emitted by the production of luggage are more serious.

The organic waste gas produced by the leather products manufacturing industry mainly comes from the bonding, drying, cleaning and other processes, and the characteristic pollutants are methyl ethyl ketone, acetone, ethyl acetate and so on. Due to the differences in the raw and auxiliary materials used by various enterprises and the technological processes adopted, possible pollutants also include n-hexane, dichloromethane, dichloroethane, trichloroethylene, isopropyl alcohol, etc.

10. Shoe industry

The shoemaking production process mainly includes the processing of the upper and the processing of the sole, and then the assembly line forming.

The main pollutants are organic waste gas, and the main processes that produce organic waste gas are:

(1) When printing the upper trademark, the organic waste gas produced by the volatilization of the ink, the main component of the ink is the color, the diluent is generally benzene, alkane and ketone, and the organic solvent component volatilizes into the surrounding environment during the mimeo drying process;

(2) The exhaust gas generated by the high-frequency pressing process of the upper material, and the exhaust gas generated by the high-frequency leather belongs to the category of malodorous gases.

(3) Shoe material EVA(ethylene-vinyl acetate copolymer), MD(or PHYLON) foaming process, TPR(thermoplastic rubber), PVC(polyvinyl chloride) injection molding heating conditions produced organic waste gas, the gas is a polymer heat molecular degradation, release monomer oligomers, degradation and temperature, heating time related, The main components of organic waste gas are monomer oligomers and olefin.

(4) solvent-based paint is generally used in the sole spray painting process. The mixture of the organic component aromatic resin and benzene solvent is mainly used for the spray painting of PVC, plastic, rubber and other materials. All benzene solvents are volatilized into the atmosphere during use.

(5) The adhesive used in the middle sole bonding and the viscose forming process of the upper sole, the solvent used in the initial adhesive is benzene, and then toluene is used as the solvent. There are also polyurethane adhesives that use ketone esters as solvents. Due to the high content of organic solvents in the adhesive, it is the most organic exhaust gas emission in the shoemaking process.

According to the relevant person in charge of the Chengdu Ecological Environment Bureau, this is an innovative measure for differentiated management and control of heavy pollution weather emergency emission reduction proposed by the Ministry of Ecology and Environment in 2019 in combination with the reality of 31 key industries across the country.

Relevant key industry enterprises involved in the development of heavy pollution weather emergency emission reduction plans in combination with their own industry characteristics, production conditions, production processes and pollution emissions. Among them, enterprises whose performance level of heavy pollution weather has reached class A are exempted from stopping and limiting production during the emergency period of heavy pollution weather, and Class B enterprises reduce the proportion of stopping and limiting production.

\"This will play a positive role in accelerating the green development of enterprises, promoting the upgrading of industry standards, and promoting high-quality economic development.\" The person in charge said that the ecological environment department in conjunction with the Ministry of economy and information technology, to guide enterprises in accordance with the national \"Heavy pollution weather key industries emergency emission reduction measures to formulate technical guidelines\

The measures are detailed to specific production lines, production process links, and production equipment. After the program is verified by experts that it meets the conditions of \"operability, detection and verification\

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