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Selective Catalytic Reduction (SCR) Catalyst Replacement

Selective Catalytic Reduction (SCR) is a means of reducing NOx emissions from high sulphur coal fired conventional boilers by converting nitrogen oxides (NOx) with the aid of a catalyst into N2 and water. Most SCR’s are installed upstream of the air preheater and downstream of the economizer. SCR catalyst is made of ceramic material that is a mixture of carrier and active components, and is typically arranged in a series of two to four layers. As catalyst activity declines, the catalyst layer is replaced on a rotating basis, starting with the top layer. The goal is to maximize catalyst effectiveness and utilization.

To assist utilities in extending the useful life of catalyst, IGS designs and engineers premium popcorn ash screens which filter out large particle ash (LPA), a serious and often overlooked problem in the SCR maintenance routine.

Integrated Global Services also assists utilities in the replacement of the catalyst layers.  One recent project involved the replacement of the top layer of modules, each module weighing close to 3,000 lbs.  Work was performed close to 100’ in elevation with two 8 man crews per shift. Hoisting expertise was critical to a safe operation. The catalyst modules were protected from poor ambient weather during handling and lifting.  IGS completed the project safely and in record time.