Updating a cement plant

The cement industry has a long and storied history in the Lehigh Valley with some of the country’s earliest cement manufacturing taking place right here.   

With concrete being the most widely used construction material on earth, it is no surprise that the need to produce cement, a critical component in concrete, would be ever increasing.   

As production at cement plants continued to increase over the generations, so did technological advancements, which resulted in larger and more complex systems being created for cement manufacturing.  Now, cement manufacturing facilities are truly an engineering marvel in the size and scope of the equipment needed for modern cement production.   

These plants operate in tough conditions and even the largest and most advanced equipment succumbs to the millions of tons of raw materials that can run through them each year.   

The maintenance and eventual repair of the equipment poses its own engineering challenges, especially when key pieces of equipment need to be replaced.  For those situations, it takes an experienced team of multi-discipline engineers to tackle the problem from evaluating solutions, engineering complex modifications, and working closely with construction contractors to carefully plan a project.   

ZAP Engineering and Construction Services, a Colorado based company with a soon to open, Bethlehem, Pennsylvania office, undertook a project in which a cement plant required the replacement of heat exchanging cyclones in the preheater tower. 

The design process started with an evaluation of the tower structure with the aim of determining the structural constraints and determining how structural design codes and standards have changed since the tower was built, requiring a complete and detailed analysis of the tower to determine the structural limitations for the cyclones.  

From this model it was determined that before the new, larger refractory lined vessels could be installed in the tower that structural reinforcement would be required to bring the preheater tower into compliance with current building codes, including seismic and wind requirements.   

After the completion of the structural analysis and determination of the structural limitations as they applied to the cyclones and the inlet and outlet ducts, the process team was brought in to analyze the existing cyclones and connecting ductwork.   

As part of the replacement of the cyclones, ZAP was also asked to evaluate advancing the design to increase the cyclone efficiency of which the operational evaluation identified gas velocities and pressure drop as key improvement areas. 

The design process commenced with taking a 3D scan of the project area.  At the completion of this process a CFD model of the existing stage 2 to stage 1 risers, stage 1 cyclones and stage 1 exit ducts was developed.   

The new cyclones and ducts were to have refractory lining to provide wear resistance and insulation protection to the steel.  The refractory design would add weight to the vessel and was therefore limited in thickness by the structural limitations of the tower.   

As the needs of the project grew, so did the complexity of the modification which engaged all engineering disciplines to come up with an integrated solution.   

This final solution integrated the needs of the installation contractor who was actively engaged in the planning aspects of the project. 

The installation of the new cyclones and ducts was a challenging portion of this project and involved the demolition of the concrete tower roof, removal of two concrete roof beams as well as the old ducts and cyclones.   

It was decided to use a single contractor for the fabrication, demolition and installation. This gave the contactor the freedom to fabricate the cyclones and ducts in a manner that not only met the design criteria but aided in installation.  

The plant had a very tight shutdown window of 21 days during which the demolition of the old cyclones and installation of the new could occur. This required careful planning and sequencing to ensure that the schedule was met without any compromise to safety or quality of the finished product. 

These types of large, complex engineering projects are becoming more common across the heavy industrial space as the growing base of aging heavy industrial equipment that needs repair and upgrades.   

It takes a high level of competence and teamwork amongst an engineering team that spans disciplines to successfully execute it in a safe and effective manner. 

Jeff Kutz is vice president of East Coast Engineering for ZAP Engineering & Construction Services