How to choose filter element in large industrial waste gas treatment plant?
Complete selection scheme of filter element in industrial large-scale waste gas treatment plant
Firstly, it is divided into two mainstream adsorption filter elements: granular activated carbon (GAC/honeycomb carbon), compressed activated carbon rod (CTO) and activated carbon fiber ACF (carbon fiber filter element), and then it is matched with pre-primary/intermediate effect filtration, and the selection is based on exhaust gas conditions, air volume, pollutants and operation and maintenance costs.
1. Step 1: First, distinguish the core working conditions of exhaust gas (core basis for selection).
1. Type of waste gas pollutants
1) High-concentration macromolecular pollutants (paint mist, oil fume, resin volatilization, high-boiling solvent, heavy oil, dust sludge)
Macromolecule oil mist and viscous substances are easy to block micropores, so it is forbidden to use ACF carbon fiber filter only, because the fiber pores are fine, which is easy to block and quickly fail; Preferential granular carbon, honeycomb activated carbon+pre-glass fiber oil filter.
2) Low-and medium-concentration small-molecule VOC (benzene, toluene, xylene, ethyl acetate, acetone, formaldehyde)
Both kinds of charcoal can be used; Granular carbon separation with large air volume and low cost; Trace waste gas, high precision and low wind resistance to select ACF.
3) Acidic/alkaline waste gas (pickling, electroplating, pickling tank, acid-base volatilization)
Choose washable modified carbon+polypropylene skeleton filter element to avoid ordinary carbon pulverization when it meets acid and alkali; The acid and alkali resistance of ACF is better than that of ordinary granular carbon.
4) contains dust, particulate matter, welding smoke and polishing dust.
Multi-stage filtration must be pre-arranged, otherwise any carbon filter element will quickly plug holes: primary effect G4→ intermediate effect F6/F8→ oil blocking filter, and then enter the activated carbon layer.
2. Air volume and equipment size (key of large waste gas plant)
Extra large air volume (more than 10,000m/h, large painting, printing and plastic factories):
Honeycomb activated carbon blocks, granular carbon beds and large carbon boxes are the main ones, and batch carbon fiber filter elements are not recommended; ACF has a small single processing capacity, and the cost of mass use is extremely high.
Medium and small air volume (500–5000m/h, laboratory, small-scale coating and injection molding):
ACF carbon fiber folding filter element can be selected, which occupies a small area and is convenient to replace.
3. Exhaust gas temperature
Normal temperature waste gas ≤60℃: ordinary carbon filter element can be used;
Drying waste gas at high temperature of 60-120℃: heat-resistant modified activated carbon and glass fiber support ACF are selected, and plastic skeleton filter element is prohibited;
High temperature > 120℃: catalytic combustion and RCO/RTO are used instead of carbon adsorption filter element.
4. Humidity and water vapor
High humidity waste gas (waste gas after water washing, printing and dyeing, food cooking):
Ordinary granular carbon is easy to powder and agglomerate when it meets water, and the pressure drop soars; Waterproof impregnated honeycomb carbon or waterproof ACF fiber filter element is preferred.
Comparison of scenarios in which the second and third types of carbon filter elements are suitable for large waste gas plants.
1. Granular activated carbon/honeycomb activated carbon (preferred for large waste gas mainstream)
Applicable scenario (core of large-scale waste gas treatment station)
Large painting factory, painting assembly line, vehicle painting room, furniture painting waste gas;
Large printing plant, ink workshop, plastic injection molding, rubber vulcanization high concentration VOC；;
Centralized deodorization of large-scale cooking fume in catering, centralized deodorization of garbage station and sewage station;
Large-scale centralized waste gas treatment station with air volume ≥ 10,000 m/h and multi-workshop unified waste gas collection.
superiority
The single machine has a large loading capacity, a long replacement cycle and the lowest processing cost per ton;
Strong resistance to oil pollution and macromolecular viscous pollutants, not easy to block quickly;
It can be regenerated by hot air desorption, and the carbon can be reused, which is suitable for continuous production plants;
The wind resistance of honeycomb carbon is much lower than that of granular carbon bed, and the energy consumption of fan is lower.
Short board
The equipment occupies a large area and the labor intensity of replacement is high; The removal efficiency of trace low concentration waste gas is average.
2. Compressed activated carbon CTO carbon rod filter (small equipment, rarely used alone for large waste gas)
Mostly used for small-scale finishing treatment at the end of equipment, but not for main treatment:
Small single machine waste gas, laboratory fume hood and small coater end deodorize, and large waste gas factory is only used as post-position deep fine filtration auxiliary.
3. ACF activated carbon fiber filter (carbon fiber filter)
Applicable scenarios (large waste gas is only subjected to supporting fine treatment, not primary adsorption)
Deep purification of trace residual VOC after treatment by main equipment;
Low-concentration organic waste gas from electronics factory, photovoltaic and pharmaceutical clean workshop;
Small closed production line, laboratory waste gas, fume hood;
It needs low wind resistance, fast adsorption and no secondary pollution of carbon powder.
The reason why it is not suitable for that main treatment of large-scale waste gas
Under the same air volume, the procurement cost is 3-8 times that of honeycomb carbon, and the use cost of large factory buildings is extremely high;
Fiber micropores are fine, and high concentration of paint mist and oil stain will quickly block the filter element and scrap it in a few days;
The total adsorption capacity of a single filter element is small, and hundreds of filter elements are needed for tens of thousands of air volume, so the labor cost of replacement is huge.
Three, large waste gas standard filtration configuration (graded filtration, prolong the service life of carbon)
It is forbidden for large waste gas to directly enter the activated carbon filter element, and it must be intercepted by stages to reduce carbon loss;
Primary filtration: G4 non-woven filter bag, which can intercept large particles of dust and paint residue;
Secondary intermediate filtration: F6/F8 glass fiber filter cartridge/filter bag, fine dust and dry smoke;
Three-stage oil-blocking filtration: glass fiber oil-blocking cotton, PTFE coated filter cartridge, intercepting paint mist, lampblack and liquid oil droplets;
Main adsorption layer: honeycomb activated carbon/granular carbon bed (the main body deals with high concentration VOC);
Optional post-fine filtration: ACF carbon fiber filter (deep removal of trace odor, high standard emission requirements).
IV. Direct Scheme for Selection of Large Waste Gas Plants in Different Industries
Large painting/furniture painting factory (high paint fog, high VOC)
Main filtration: honeycomb activated carbon block; Pre-position: coated filter cartridge+multi-stage oil-repellent cotton; ACF is not used as the main filter, and only a small amount of ACF is placed after the emission requirements are extremely high.
Large printing, plastic and coating plants (medium and high concentration solvents)
The large-volume carbon box is filled with particles/honeycomb carbon, and a desorption regeneration system is provided; ACF carbon fiber filter is installed at the end of high-clean workshop to deeply deodorize.
Electroplating, pickling and chemical waste gas (acid and alkali+trace VOC)
Acid and alkali resistant modified honeycomb carbon with waterproof ACF filter core; All filter elements are made of PP/glass fiber corrosion-resistant skeleton.
Centralized deodorization of large-scale food, slaughter and garbage (high humidity and complex odor)
Waterproof impregnated honeycomb activated carbon, pre-washing spray+dehumidification section, without ordinary granular carbon (easy to agglomerate).
Centralized waste gas from electronics, semiconductors and pharmaceuticals (low concentration and high cleanliness requirements)
The main honeycomb carbon is roughly treated, and the whole row of ACF folded carbon fiber filter elements at the end prevent carbon powder from floating into the workshop.
Five, the selection of key criteria (quick self-examination)
Air volume > 8000m/h, high oil pollution and high paint mist, pursuing low-cost continuous operation → honeycomb/granular activated carbon as the mainstay.
Air volume < 5000m/h, low concentration of clean waste gas, strict emission standards and small space → ACF carbon fiber filter.
There is a lot of dust and oil mist: pre-filtration must be added, and it is forbidden to directly apply carbon filter elements.
Factory produces continuously for 24 hours and needs to be recycled: honeycomb carbon is given priority, and the regeneration cost is much lower than ACF.
Centralized waste gas treatment with limited budget and multiple workshops: giving up large area ACF and using only a small amount at the end.
Six, avoid pit points
Don't use all carbon fiber filter elements in the main treatment of large-scale waste gas: the operating cost and the replacement of labor unions have risen sharply;
ACF can not be used alone for oily waste gas, and the fiber is easily blocked by oil film and fails within one week.
Waterproof modified carbon is used for high humidity waste gas, and ordinary carbon is pulverized in water, causing fan blockage;
The discharge can only meet the standard, without excessive use of high-end ACF, which increases the operating cost.
