Wet electrofilters

We have considerable experience and expertise in the field of gaseous emission treatment, specifically for the installation of wet electrostatic filters, a technology considered to be at the forefront of organic and inorganic dust and mist removal. Let’s take a closer look at what this is all about: the basic structure of an electrostatic filter (a filter designed to separate solid and liquid particles from the gaseous flow) consists of two electrodes: a discharge electrode, which is rigid and specially shaped with sharp points that intensify the electric field, and a collection electrode connected to the ground, which is generally tubular in shape. When a very high potential difference is applied to these electrodes, the intense electric field created gives rise to a process of ionisation of the gas molecules, the so-called “corona effect”. The ions produced by the corona effect migrate towards the electrodes of opposite sign and collide with the dust particles flowing parallel to the electrodes, transferring charges onto them. An electrical force is thus exerted on the charged particles immersed in the electric field, directing all of them towards the collecting electrode.

Wet electrofiltration

Wet electrofiltration technology is an improvement on the system described above and has the advantage of combining the removal of the coarse fraction of dust with a preliminary washing treatment. This leads to the removal of the remaining micronic and submicronic fraction, which is responsible for the visual effect of opacity (fog) that usually appears as a dense, blue smoke that remains visible for long distances.
By introducing, on the other hand, a pre-washing section, the subsequent electrofiltration section is avoided by fouling with coarse particles, with obvious advantages in terms of cleanliness and abatement efficiency of the system. In addition, a high quantity of micro-droplets (humidified gas) is dragged into the subsequent electrofiltration phase, favouring the interception of finer particulates.

The recirculation water, used in the flue gas pre-washing section and for the periodic washing of the collector pipes, is accumulated in the bottom tank and then pumped back into the circuit; since its polluting load progressively increases over time, it is necessary to either purge it periodically or install a section of the plant dedicated to its continuous treatment. This second option involves various chemical-physical treatments aimed at precipitating/sedimenting the polluting load of the water.

Example of application of wet electrofiltration

In some examples you can see the effectiveness of flue gas purification with wet electrofiltration technology, in others on the right-hand side, the flue gas passes through the electrofilter with the high-voltage transformer switched off, i.e. without purification. The persistence of the plume, perceptible from a long distance, will be clearly visible, due to the presence in the fumes of particulate matter and oil mists with concentrations above 150 mg/Nmc. In other examples on the left-hand side, the fumes pass through the electrofilter with the high-voltage transformer switched on, carrying out the purification. Only a small amount of water vapour is visible at the flue, with a concentration of particulate matter and oil mist of only 5 mg/Nmc. In this specific case, we guarantee in the sales contract the abatement of particulate matter and oil mist for values less than or equal to 10 mg/Nmc

Characteristics

High abatement efficiency of oil mists, VOCs and solid particulate matter down to 0.1 μm: efficiency values close to 99% can be achieved
Extremely low pressure drop
Limited maintenance operations (no mechanical moving parts, only periodic cleaning required)
Limited fouling problems, both because there is pre-washing and because the collector tubes are large diameter and continuously cleaned by the liquid film of condensation; the system is therefore self-cleaning
Low energy consumption compared to other abatement technologies

Fields of application

Our plants can be complemented, if necessary, by coarser particulate abatement systems through the installation of cyclones, Venturi jets and sprinkler or plate scrubbers entirely designed and manufactured by Fidia Engineering. In addition, tube-electrode cooling systems can be installed, usually consisting of a plate heat exchanger and cooling tower.

Textile sector: abatement of particulate and oily mists present in fumes from thermofixing stenter and various heat treatments
Energy sector: reatment of flue gases from waste incineration and waste-to-energy plants (abatement of acid mists, heavy metals, silicates), from industrial low-fuel boilers (drying and combustion of grape marc and olive pomace, drying and combustion of wood residues in the production of pellets, production of energy and steam from renewable biomasses), from waste and biomass gasification plants, from coal production and processing plants
Cement and lime industry: abatement of particulate matter contained in emissions from rotary kilns and grinding mills
Wood and HD Fiberboard industry: abatement of wood dust and organic combustion products contained in fumes from wood biomass furnaces
Steel and metallurgical sector: separation of metal dusts and acid mists contained in fumes from smelting and roasting furnaces for copper, zinc, pyrites, etc..
Petrochemical sector (refineries): abatement of dusts, sulphuric mists, hydrocarbons
Metal crushing sector: dust and hydrocarbon abatement
Plastic foam and/or PVC or resin coating production sector

Pilot plant

We have the ELT C-012 wet (pilot) electrofilter with high efficiency in the abatement of submicron particles (organic and inorganic mists). Efficiency values close to 99% can be achieved. Volume flow rate of treated air (maximum): 2,000 Nm3/h (max. 130° C).
Manufactured by us entirely in AISI 304, complete with internal flushing section (rod desk tubes), gas distribution grid, flushing ramps, emission electrodes and 6” collection tubes, self-supporting, automatically programmable internal section flushing, high emission rigid electrodes, automatic V/I ratio adjustment and discharge optimisation, possibility of cooling with electrode tube liner, flushing of insulators, interlocking key safety system.

View project

Here below some of works

69018

The plant treats the gaseous emissions from the kilns for drying and combustion of grape marc (rich in dust, oily mists, VOCs). The aspirations from the ovens are fed into the lower section of the wet electrofilter, after treatment with dry cyclones and a washing tower. The system also significantly reduces olfactory nuisance.

Distillery Sector

View project

57518

Wet electrofilters

The plant treats the gaseous emissions from the drying machines and thermo-fixing of the color on the fabrics (Rameuse) and from the printing machines (over 10 machines in total): the aspirations coming from the production department are fed into the lower section of the electrofilter. humid. This involves a pre-washing phase followed by an electrostatic collection section.

Textile industry

View project

50012

Wet electrofilters

For the removal of oily mists, organic particulate VOCs and olfactory nuisances contained in the fumes coming from the grinding mills of metal scrap, the installation of the wet electrofilter has allowed the plant to treat the gaseous emissions coming from the furnaces for drying the olive pomace (rich in dust, oily mists, VOCs). The aspirations from the ovens are fed into the lower section of the wet electrofilter, after treatment with dry cyclones and a wet scrubber. The plant provides an optional chemical-physical treatment of the washing water. The system also significantly reduces olfactory nuisance

Sansificio sector

View project

42310

Wet electrofilters

For the removal of oily mists, organic particulate VOC and nuisances For the removal of oil mists, organic particulate VOC and olfactory nuisances contained in the fumes coming from the grinding mills of metal scrap, the installation of the wet electrofilter has allowed to increase in significantly the dust abatement yields of the existing flue gas line, consisting of a dry cyclone separator, a Venturi jet and a wet scrubber. Thanks to the lower pre-wash section, a further reduction of the volatile organic compounds present in the effluent was achieved.

Mechanical field

View project