Corrosion is one of the most challenging and costly issues seen across all markets worldwide. Billions of dollars are spent dealing with the effects and in the prevention of corrosion. Engineers are tasked with the job of designing in such a way that minimizes the effects of corrosion. Luckily there are many high performance materials and systems for engineers to utilize in their efforts to combat the effects of corrosion. Cost and material availability must be weighed against long term performance of a system. Air pollution control engineers must consider the following design criteria when designing wet scrubbing equipment:king.com.
- Technical performance: Does the unit consistently meet the specified air cleaning efficiency?
- Reliability: What are its weaknesses and how can we protect against damage or failure?
- Outage: How much of an outage can be tolerated without loss and how quickly can the unit be repaired or replaced?
- Cost: What is the most cost effective system? Every air scrubber application must be analyzed carefully and technical performance standards must be met.
In many cases today, a whole plant may be forced to shut down if an air pollution control device fails. The engineer selecting an air control device has to make a judgement on how much corrosion can be tolerated and how much of a problem the operator will have in restoring normal operations when corrosion becomes intolerable. Corrosion in a wet scrubber can cause the plastic random packing to become brittle, weaken internals, erode the column shell and damage monitoring equipment. Since we are usually collecting potentially corrosive substances with a wet scrubber, we must be especially careful about the application and selection of materials.
There are many different highly corrosion resistant metals and plastics to consider when selecting materials of construction for a system. These higher performing materials can extend the life of a system but also be very expensive. This trade-off between cost and reliability may cause problems and may lead to a full scale economic analysis to show exactly what is gained from the extra investment in corrosion resistance materials.
Engineers must address several essential questions regarding wet scrubbers and corrosion. First, What affect will corrosive compounds in the scrubbing liquid have on the system and what must be done to assure reliability of service? Secondly, Will the pH of the liquid stabilize at an acceptable point or will it continually drop if nothing is don to correct it? And lastly, Can the liquid be treated with chemicals for removal of devolved gases or can the particulate mater be filtered out? The answers to these questions will have to be found for each scrubber and be incorporated in the design. In effect, all of the components of the system including the piping, pumps, tanks, instrumentation, plastic random packing and internals must be designed for the intended service.
In order to address their customer’s concerns regarding their wet scrubbers and corrosion, KemFlo offers their plastic random packing in a variety of high performance resins. Kemflo’s Tripacks, Pall Rings and Plastic Saddles are offered in Polypropylene, Polypropylene NSF, Polypropylene Glass Filled, Polyvinylchloride PVC, CPVC, Kynar PVDF, Tefzel ETFE, Teflon PFA, and Halar resins. For more information please visit www.kempac-packing.com.