Material selection method for dust removal bags

The core principle for selecting the material of the dust removal bag is to fully comply with the core operating parameters of the on-site flue gas and dust,taking into account the performance,service life,and comprehensive cost of the filter bag.Among them,the flue gas temperature is the most important selection basis,followed by the corrosiveness,moisture content,and dust characteristics of the flue gas.Finally,combined with the operating parameters of the dust collector,the selection deviation will directly lead to rapid wear,bag sticking,aging and failure of the filter bag,greatly shortening its service life.

Before selecting,it is necessary to clarify the four core parameters that must be tested/checked.If there are no precise parameters,it is not recommended to choose based on experience:first,the flue gas temperature,which needs to distinguish between the stable long-term operating temperature of daily use and the instantaneous maximum temperature of start-up/working condition fluctuations.The long-term temperature resistance of the filter bag needs to be≥the long-term operating temperature of the flue gas,and the instantaneous temperature resistance needs to cover the peak temperature;The second is the composition of the flue gas,with a focus on confirming whether it contains corrosive media such as SO₂and HCl,whether the moisture content is greater than 15%,and whether there is a risk of condensation;The third is the characteristics of dust,determining whether it is fine powder/viscous powder,coarse powder/high hardness powder,or flammable and explosive dust such as coal powder and aluminum powder;The fourth is the operating parameters,including the processing air volume,surface air velocity of the filter bag,and cleaning method.Higher strength filter media should be selected for high-speed operation.

The core parameters,characteristics,applicable working conditions,preferred treatment processes,advantages and disadvantages of mainstream dust bag materials are sorted out according to the three temperature resistance levels of normal temperature,medium temperature,and high temperature.They are suitable for all industrial bag dust collector scenarios such as building materials,electricity,metallurgy,chemical industry,and mining.Film coating is the preferred additional process for the vast majority of working conditions,which can achieve surface filtration,prevent dust from entering the pores of the filter material,reduce operating resistance,and improve dust cleaning effect.

Room temperature filter material(long-term temperature resistance≤130℃)

This type of filter material has low cost and mature technology,and is a universal industrial product suitable for conventional working conditions without special high temperature or corrosion.

Polyester:Long term temperature resistance≤130℃,instantaneous temperature resistance≤150℃.Its core characteristics are high wear resistance and good physical strength.It is currently the most widely used filter material in industrial applications;Suitable for normal temperature non corrosive/low humidity dust working conditions such as mining,sand and gravel,woodworking,grain processing,normal temperature boilers,mechanical processing,etc;The preferred additional processes are film coating,waterproof and oil resistant,and anti-static;The advantages are the highest cost-effectiveness and wide adaptability,while the disadvantages are low temperature resistance and average corrosion resistance.It is prone to bag sticking and aging in high humidity/high corrosion conditions.

Polypropylene(PP):Long term temperature resistance≤80℃,instantaneous temperature resistance≤100℃.Its core characteristics are excellent acid and alkali corrosion resistance,lightweight,and good moisture resistance.It is a specialized filter material for high corrosion conditions at room temperature;Suitable for normal temperature and high acid alkali corrosion conditions such as chemical acid alkali dust,electroplating dust,and wastewater treatment plant exhaust gas;The preferred additional process is film coating,waterproof and oil resistant;The advantages are strong corrosion resistance and low price,while the disadvantages are extremely low temperature resistance,average physical strength,and easy aging during long-term operation.

Medium temperature filter material(long-term temperature resistance of 130-180℃)

This type of filter material combines temperature resistance and adaptability,suitable for complex working conditions with high humidity and slight corrosion in the medium temperature range.Its temperature resistance is better than that of normal temperature filter material,and its cost is lower than that of high-temperature filter material.

Acrylic(homopolymer polyacrylonitrile):Long term temperature resistance≤160℃,instantaneous temperature resistance≤180℃,core characteristics are resistance to weak acids and bases,excellent moisture resistance,strong hydrolysis stability,and it is the first choice for high humidity and medium temperature working conditions;Suitable for high humidity,medium temperature,and non corrosive working conditions such as asphalt mixing plants,biomass boilers,coal slurry/sludge dryers,and grain drying;The preferred additional process is film coating,waterproof and oil resistant;The advantages are that it does not hydrolyze under high humidity conditions and has a long service life,while the disadvantages are poor corrosion resistance and average wear resistance.

Polysulfonic acid polyamide:Long term temperature resistance≤180℃,instantaneous temperature resistance≤200℃.Its core characteristics are stronger high temperature resistance,resistance to weak acids and bases,high physical strength,and good resistance to repeated blowing and cleaning of dust;Suitable for medium temperature and slightly corrosive working conditions such as coking plants,intermediate frequency furnaces,and biomass high-temperature drying;The preferred additional processes are film coating and anti-static;The advantage is excellent comprehensive performance and adaptability to complex working conditions at medium temperatures.The disadvantage is that the cost is higher than acrylic and the resistance to strong oxidation is poor.

High temperature filter material(long-term temperature resistance≥180℃)

This type of filter material has outstanding temperature and corrosion resistance,and is suitable for core harsh working conditions such as high temperature,high corrosion,and high humidity in industry.It is a specialized filter material for coal-fired boilers,metallurgical sintering machines,and other equipment,with relatively high cost.

PPS(Polyphenylene Sulfide):Long term temperature resistance≤190℃,instantaneous temperature resistance≤210℃.Its core characteristics are resistance to strong acid and alkali corrosion,excellent hydrolysis resistance,and it is the core filter material for high-temperature industrial boilers.It is also the first choice for cost-effectiveness in high-temperature working conditions;Suitable for high-temperature,high corrosion/high humidity conditions such as coal-fired boilers,low-temperature sections of waste incinerators,metallurgical sintering machines,and flue gas after desulfurization;The preferred additional process is film coating,waterproof and oil resistant;The advantage is that it has the characteristics of temperature resistance,corrosion resistance,and hydrolysis resistance,with wide adaptability.The disadvantage is poor oxidation resistance,and the flue gas is prone to aging when it contains high concentrations of O₂.

Aramid 1313(meta aramid):Long term temperature resistance≤200℃,instantaneous temperature resistance≤220℃.Its core characteristics are stronger high temperature resistance,high physical strength,excellent wear resistance,resistance to repeated blowing and dust cleaning,and resistance to weak acids and alkalis;Suitable for high-temperature,non corrosive,and high airflow scouring conditions of coarse dust such as cement rotary kilns,metallurgical blast furnaces,and electric arc furnaces;The preferred additional processes are film coating and anti-static;The advantages are high strength,high wear resistance,and adaptability to high erosion conditions.The disadvantages are that the resistance to strong corrosion and hydrolysis is average,and it is prone to failure in high humidity and high corrosion conditions.

PTFE(Polytetrafluoroethylene):Long term temperature resistance≤260℃,instantaneous temperature resistance≤280℃.Its core characteristics are temperature resistance,corrosion resistance,hydrolysis resistance,and oxidation resistance,all of which are top-notch.It is suitable for all harsh working conditions and is known as the"universal filter material";Adapt to extremely harsh working conditions such as high-temperature sections of garbage incinerators,highly corrosive waste gases from chemical industries,and high-temperature and highly corrosive flue gases from metallurgy;The preferred additional process is film coating;The advantages are full weather resistance and extremely long service life,while the disadvantages are extremely high cost,slightly lower physical strength,easy damage when used alone,and often used in combination with other filter materials.

Flumes:Long term temperature resistance≤200℃,instantaneous temperature resistance≤250℃,belongs to composite high-temperature filter media,with core characteristics of high temperature resistance,corrosion resistance,wear resistance,good breathability,low operating resistance,and anti condensation and paste bag;Suitable for high temperature,high humidity,and high dust concentration working conditions such as cement shaft kilns,dryers,and metallurgical electric furnaces;The preferred additional process is film coating,waterproof and oil resistant;The advantage is superior comprehensive performance and cost-effectiveness compared to pure high-end high-temperature filter media,but the disadvantage is slightly weaker resistance to strong oxidation.

Selection of key additional processes for dust removal bags(matched as needed)

All materials of filter bags can be matched with additional processes according to working conditions,which is the key to improving the adaptability of filter bags and extending their service life.They need to be selected to match the main material:

Film coating:the preferred choice for most working conditions,especially suitable for fine powder/viscous dust(cement,fly ash,desulfurization ash),which can achieve surface filtration,prevent dust from entering the internal pores of the filter material and causing blockage,while reducing operating resistance and improving ash cleaning effect;

Waterproof and oil proof:Suitable for working conditions where the moisture content of smoke is greater than 15%,there is a risk of condensation,or dust contains oil,to prevent filter bag condensation,sticking of bags,and oil sludge;

Antistatic:Only applicable to flammable and explosive dust conditions such as coal powder,aluminum powder,and sawdust powder.Conductive fibers are added to the filter material to prevent static electricity accumulation from causing dust explosions,which is a mandatory safety requirement;

Thickened and wear-resistant:Suitable for coarse powder/high hardness dust(ore,sand and gravel,metallurgical furnace ash),high airflow scouring conditions,to enhance the anti-wear ability of filter bags,with a focus on thickening treatment at the bottom and windward mouth of filter bags that are prone to wear.

Five steps for practical selection of dust bag materials(can be directly landed)

Measure the long-term operating temperature and instantaneous maximum temperature of the flue gas,determine the temperature resistance level of the filter material(normal temperature/medium temperature/high temperature),and prevent overheating selection;

Detect the corrosiveness and moisture content of flue gas.If it is a high corrosion/high humidity working condition,priority should be given to selecting materials that are resistant to corrosion and hydrolysis in the corresponding temperature resistance level;

Analyze the characteristics of dust,choose thick and wear-resistant materials for fine sticky powder and film coating,thick and wear-resistant materials for coarse hard powder,and anti-static materials for flammable and explosive powder,and add additional processes as needed;

Combining with the dust collector cleaning method,materials with good toughness and resistance to repeated blowing can be selected for online cleaning,while slightly thicker filter materials can be used for offline cleaning;

Check the surface wind speed of the filter bag.If the actual wind speed exceeds the design value(usually 0.8-1.2m/min),choose a material with higher physical strength or increase the number of filter bags to reduce the wind speed.

Core considerations for selection

Priority should be given to using laminated filter media.Except for special conditions with high scouring of coarse dust,laminating can significantly reduce the probability of filter bag blockage and high resistance,and extend the service life;

Eliminate the use of excessive temperature,even if it exceeds the temperature for a short period of time,it will irreversibly damage the filter fiber,leading to rapid aging of the filter bag;

Avoid using easily hydrolyzed materials in high humidity conditions,such as aramid 1313,which is not suitable for high humidity and high corrosion conditions to avoid rapid failure of filter bags;

Not simply pursuing"low cost",it is necessary to comprehensively calculate the frequency of filter bag replacement,labor costs,and equipment downtime losses.Choosing high-end materials for high and harsh working conditions can actually lower the overall cost;

Composite filter media,such as PTFE and PPS composite,can be selected for special working conditions,which can balance corrosion resistance,temperature resistance,and physical strength,and adapt to extreme working conditions that cannot be met by a single material.

GB/T 7714:

MEYER P,THEISEN K.Material Selection for Industrial Filter Bags:A Holistic Approach Based on Process Conditions and Emission Requirements[J].Filtration&Separation,2018,55(4):28-35.

MLA 9th:

Meyer,Peter,and Klaus Theisen."Material Selection for Industrial Filter Bags:A Holistic Approach Based on Process Conditions and Emission Requirements."Filtration&Separation,vol.55,no.4,2018,pp.28–35.

APA 7th:

Meyer,P.,&Theisen,K.(2018).Material selection for industrial filter bags:A holistic approach based on process conditions and emission requirements.Filtration&Separation,55(4),28–35.