FGD and DeNOx
NEWSLETTER       

                                                                                                                    February  2002
                                                                                                                          No. 286

Construction Engineering Tips for SCR Projects

Constructability encompasses a wide variety of practices that when incorporated into a project can improve productivity and, in most cases, reduce costs or project risks. Recognizing that construction costs for SCR projects can exceed 50 percent of total costs and given that labor and equipment are significant cost components, J. Hines, A. Kokkinos and D. Fedock of Babcock & Wilcox remind readers that it is prudent to design in a fashion that ensures the maximum efficiency of these valuable resources. 

Complicating matters has been the increased demand for construction, specifically boilermaker, services. Projections of the demand for construction labor are provided in Figure 1. However, the demand for boilermakers is not limited to the utility industry as shown in Figure 2.

Construction elements that should be paid attention to include:

·         Crane selection. The weight of the largest component is identi­fied and crane size is se­lected based on weight, site condi­tions, and economics.

·         Erection sequence. Once the sub-assemblies (mod­ules) are identified, the erection se­quence should be detailed on a drawing and distributed to the entire project team. Ordering should also be coordi­nated, because receiving material far in advance of the time required at the job or out of order only adds costs and burdens the job with additional material handling costs. 

·         Flues should be bottom-supported where possible, and ideally the identified modules will be self-supporting. This will minimize crane time.

·         The use of fit-up bolts between adjacent panels or modules helps.

·         Due to the extensive amount of work that is required inside the fluework and SCR reactor, large access doors assist in getting workers and equipment inside.

·         Assembly generally requires a significant amount of scaffolding.

·         It is also important to know the material type of any fluework being demolished. Some material may be brittle and thus require additional safety precautions. 

·         When the cut line location is critical, such as the location of the new tie-in point, dimensions and locations should be verified from a reliable source, such as a column line or other structural steel. 

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