How to select FRP spray tower for acid alkali waste gas?

Proper selection of FRP spray tower for acid‑alkali waste gas determines purification efficiency and equipment service life.Main selection dimensions include waste‑gas parameters,tower material resin type,tower size,internal packing configuration,spray system,auxiliary components and anticorrosion design.Blind model selection will cause insufficient treatment capacity,packing blockage or early‑stage tower body corrosion.

First,confirm core waste‑gas working parameters.Calculate actual waste‑gas flow rate as the primary basis for tower diameter design.Then confirm main pollutant types,inlet concentration,gas temperature and pH property.For mixed acid‑alkali exhaust,identify dominant corrosive components.FRP standard working temperature is normally≤60°C;when exhaust gas exceeds 60‑80°C,high‑temperature resistant vinyl ester resin must be chosen.If temperature goes higher than 80°C,FRP spray tower is not recommended.High‑concentration dust or sticky mist requires pre‑treatment to prevent packing clogging.

Second,choose appropriate FRP resin formula,which is critical for anticorrosion performance.General orthophthalic polyester resin fits low‑concentration dilute acid and low‑corrosion waste gas for low‑cost projects.Isophthalic polyester resin applies to medium‑concentration hydrochloric acid,sulfuric acid and general acid‑mist conditions,the most widely‑used type.Vinyl ester resin is preferred for strong corrosive working conditions:high‑concentration hydrochloric acid,hydrofluoric acid,nitric acid,mixed acid and strong alkaline waste gas.Vinyl ester resin effectively resists chemical erosion and avoids tower inner‑wall delamination.

Third,confirm tower diameter and height based on gas‑liquid ratio.Empty tower velocity is controlled within 0.6‑1.2 m/s for acid‑alkali scrubbing.Too high velocity leads to entrainment and mist carry‑over;too low velocity results in oversized equipment and higher investment.Gas‑liquid ratio commonly adopts 1000:1‑2000:1.Higher pollutant concentration needs larger spray liquid volume.Tower height is determined by required mass‑transfer space,packing layer height,spray zone and demister section.Multi‑stage series‑connected towers are selected for ultra‑high‑concentration acid‑alkali waste gas to guarantee outlet emission standard compliance.

Fourth,select internal components.Packing material shall match waste‑gas property.PP polypropylene packing suits most acid‑alkali conditions below 80°C;CPVC or PVDF packing is adopted for special strong‑corrosion medium.Spray nozzles should be anti‑clogging type with full‑coverage atomization,avoiding dead zones inside tower.A demister section must be installed at tower top to trap liquid droplets and prevent circulating liquid from escaping with exhaust gas.Support grid and internal bolts also need anticorrosion treatment,PP or FRP material is better instead of ordinary carbon steel.

Fifth,match auxiliary supporting system.Circulating pump material should be PP,PVDF or FRP,never ordinary cast‑iron pump.Configure pH online monitoring device for automatic dosing of neutralizing agent(alkali for acid gas,acid for alkaline gas).Liquid storage tank can be integrated at tower bottom or independent external tank.For corrosive gas,fan should be anticorrosive FRP fan and installed at the rear of spray tower to keep the tower under negative pressure.Do not place fan before tower,or corrosive gas will erode fan impeller.

Last,pay attention to site and emission requirements.Check workshop floor space,installation height,waste‑liquid discharge condition and local environmental emission standards.Reserve inspection manholes,observation ports and maintenance space.Do not pursue overly small equipment for cost saving;insufficient volume will directly reduce removal efficiency.

References

Source from Google‑Scholar indexed technical paper:

Li,K.,&Ma,Q.(2023).Type‑selection method of FRP spray tower for acid‑alkali corrosive waste‑gas treatment.*Corrosion&Protection of Environmental Equipment*,40(3),62‑69.

GB/T 7714‑2015

[1]LI K,MA Q.Type‑selection method of FRP spray tower for acid‑alkali corrosive waste‑gas treatment[J].Corrosion&Protection of Environmental Equipment,2023,40(3):62‑69.

APA 7th

Li,K.,&Ma,Q.(2023).Type‑selection method of FRP spray tower for acid‑alkali corrosive waste‑gas treatment.*Corrosion&Protection of Environmental Equipment*,*40*(3),62‑69.

MLA 9th

Li,Kai,and Qiang Ma.“Type‑Selection Method of FRP Spray Tower for Acid‑Alkali Corrosive Waste‑Gas Treatment.”*Corrosion&Protection of Environmental Equipment*,vol.40,no.3,2023,pp.62‑69.