One. VOCs Became the World Public Hazard
The definition for Volatile Organic Compounds in China is the organic compounds whose saturated steam pressure at normal temperature is higher than 70 Pa and boiling point at ordinary pressure is below 260 degrees, or at 20 degree all volatile organic compounds and steam pressure is higher than or equal to 10 Pa at 20 degrees. VOCs includes type of aliphatic components, aromatic, alcohols, aldehyde, ketone, esters, organic acid, halocarbon, oxygen-containing organic compounds, sulfur-containing and nitrogenous organic compounds.
VOCs is harmful to health and environment which covers as following;
1. Most VOCs is poison and fetor which can make people suffer from accumulation respiratory disease, sometimes will cause emergency poisoning or even die at a sudden high concentration level. Some VOCs like benzopyrene and chloroethylene can led to cancer.
2. VOCs will have photochemical reaction that produces ozone, PAN, alcohols and some other photochemical fume which may lead to secondary pollution, irritate human eyes and breathing system, harmful to human health, and might put people in a danger situation if living in a high concentration VOCs environment. Meanwhile VOCs is harmful to crops growth, or even killing crops. Photochemical pollution has happened in Los Angeles, Yanshan district in Beijing, Xigu district in Lanzhou and some other areas.
3. Most VOCs is flammable and combustible. It may cause fire and explosion at a high concentration VOCs emission. In recent years, it happens now and then that fire and explosion caused by VOCs.
4. Some VOCs might break ozone sphere.
Two. VOCs Treatment Policy Tighten
Due to VOCs has serious harm to health and environment, developed countries changed the law constantly, meanwhile China also introduced VOCs series law and regulations, intended to lower the VOCs emissions concentration limitation. In 2013, China published “the Action Plan on Air Pollution Prevention and Control” (ten articles). The “Environmental Protection Law “which effected on January 1st,2015 is the strictest environmental protection law ever, it shows how strong the environment protection and treatment is from many angles.
On January 1st,2018, “Environmental Protection Tax Law “and Environmental Protection Tax Law Enforcement Regulation” came into effect, meaning enterprise need pay tax instead of fee for VOCs pollution emission. The tax law refined 19 kinds of volatile organic compound as the pollution which need pay the tax, meanwhile clarified the pollution equivalent criterion and specific applicable tax amount. In July 2018, the State Council published “Three-year Action Plan for Winning the Blue-Sky Battle” (for short “Three-year Action plan” No. 22, State Council publish in 2018).
In June 2020, ecological environment ministry published “Year 2020 Exhaust Organic Compound Persist Treatment Strategy “. It requires high attention of ecological environment ministry to regard VOCs persist treatment as the priority task to win the blue-sky battle; ecological environment ministry should also change the strengthen direction of organization and operation, monitor, law enforcement, personnel, funding and some other points to VOCs persist treatment action, strengthening the cooperation and coordination with related department, industry associations and some others to form work resultant force. Meanwhile local government and industry have announced related law and regulations regarding VOCs waste gas emissions, as a result, the VOCs emission concentration and total load limitation decreased day after day.
Three. VOCs Treatment Technology Difficulties
The waste protection and treatment for VOCs requires refined and normative treatment technology; however, the complicated components , volatility & uncertainty of emission concentration and load of VOCs lead to complicated VOCs treatment system which make it difficult to reach the emission standard. Current skill may easily result in unqualified emission. There is potential risks and secondary pollution by using active carbon adsorption way; sharp decrease in the waste water amount by using water uptake; low efficiency and ozone production by using photocatalysis; dioxin, oxynitride and other secondary waste production by burning chloride and nitrogen-containing compound.
Even for epoxide compound, low-boiling halocarbon, nitrogen and sulfur compound still have no feasible skill to deal with, which makes the enterprise lose the confidence on VOCs treatment and feel difficult to do it. The form 1.1 have listed the comprehensive comparison of current VOCs treatment skill theory, application range and pros & corns. Photo-catalytic oxidation treatment skill is low efficient, plasma treatment skill has the potential safely risks and happened many times of safety accident which will not repeat again here.
Four. VOCs Treatment Technology Statement
Assessment of Varity Exhaust Gas Treatment Project
Treatment Method | RTO Burn Method | Soak-up Method | Biolysis Method | Absorption Method | Condensation Method |
Technique Therapy | In the rotary valve heat storage catalyzed burn equipment, firstly workers use the heat storage and heat release performance of cordierite-mullite polyphase material to heat the unreacted organic exhaust gas so as to have catalyzed and oxidizing reaction at heat storage & catalyzed combined materials, then the VOCs in the air will convert to carbon dioxide and water, meanwhile release the reaction heat, then reaction gas will transfer the heat energy to heat storage material and release out the gas whose temperature is more 20 to 30 degrees than the inlet gas. | Adapting water, alkali liquor or other solvent absorbent to transfer the pollutant to liquid phase; physical soak-up force is vapor-liquid saturated steam pressure difference; Chemical soak-up force is chemical reaction and saturated steam pressure. | Adapting recycled water flow to get pollutant in the malodorous gas dissolved into the water, then cultivate microorganism in water culture bed to degrade the pollution in the water to be non-poison and less harmful compound. | Adapting efficient absorbent whose inner pore structure is powerful and with huge specific surface area therapy to absorb microorganism gas molecule in the activated carbon pool | Adapting cooling method to lower the vapor steam pressure of pollutant in the exhaust gas, thus to achieve pollutant condensation and separation |
Air Volume& Concentration | high air volume, low concentration | medium-high air volume, medium-high concentration | high air volume, low concentration | medium-high air volume, medium-low concentration | medium-low air volume, medium-high concentration |
Efficiency | heat recycle rate reach 90%; organic purification rate reach about 95% | good design can guarantee the treatment rate above 90% or even more | Effectively control the microorganism active deodorization rate 80-90%; if microorganism active decrease, so as the deodorization efficiency; deodorization purification effect is not stable; also specific cultivate needed | Preliminary absorption rate reaches above 90 %; it need regeneration after a certain period of time | good design can guarantee the treatment rate above 90% or even more |
Element | be able to deal with butanone, ethyl acetate, n-butyl acetate, butyl cellosolve , MIBK; Organic matter concentration range is above 500mg/m³ | It has big treatment range; water-soluble pollutant can use water or alkali liquor as the absorption; water-soluble weak pollutant can design the absorption which can be dissolved; acid gas can use alkali as the absorption | Need cultivate obligated microorganism to deal with one or several gas whose characters are similar | Suitable for low concentration, strong air volume fetor; has relatively affect to alcohol and fat | Suitable for medium-high concentration, medium-low air volume exhaust gas, especially suitable for tank field exhaust gas or compound with nitrogen, halogen and sulphur |
Lifetime | whole set of control system usage lifetime is above 3 to 5 years, equipment lifetime is above 10 years and no need maintenance | whole set of control system usage lifetime is above 3 to 5 years, equipment lifetime is above 10 years and no need maintenance | difficult to maintain and need add medicament frequently; need control the PH value, temperature and so on | efficient absorbent can operate in a long period | function is simple and equipment lifetime is over 10 years, maintenance no needed |
Operation Cost | purification skill is reliable and stable which need rely on natural gas or other flammable substances whose operation cost is very high | purification skill is reliable and stable, has little daily maintenance, only need access to electricity to be working, operation and maintenance cost is low | maintenance cost is high, need always add medicament so as to keep the medicament activation, recycle | efficient absorbent can be reused | operation cost is moderate, there is no secondary pollution, achieve resource recycle |
Investment |
relatively high | low | relatively high | low | low |
Safety | with some potential safety risk | high safety | high safety | with some potential safety risk | high |
Pollution | There is secondary pollution when dispose compound with nitrogen, sulfur and halogen component | there is secondary pollution | easy to have sludge and sewage | there is secondary pollution | easy to have secondary pollution |
Therefore, we need refine and deeply research VOCs treatment technology, to satisfy VOCs with different component reaching the emission standard, to lower the investment and operation cost, as well as to meet the safety requirement. Besides, there is relatively high value in the component of VOCs emission, if we can develop suitable resourcing recycle technology regarding to different VOCs and achieve the low-cost resourcing recycle of component, while satisfying the social efficiency, achieving economic efficient, it will be happily accepted by VOCs emission enterprise and bared marketing.
Are you looking for reliable vacuum system solution?
Company address: No. 67, Feiying Road, Binjiang Development Zone, Jiangning District, Nanjing
Tel: 025-86211588
Enterprise Email: apump@apump.com.cn
400-888-6662
©2021 Nanjing Vacuum Pump Factory Co., Ltd. Recordation number: Su ICP No. 2022028646-1
