Condensation Induced Water Hammer: Principles and Consequences

An explosion occurred in the boiler room of a food processing plant as the steam generation system was coming online after a maintenance shutdown. The explosion shattered the case of the condensate return pump fatally injuring an employee, while another employee was burned by the escaping steam. The low-pressure saturated steam needed for the food processing plant was generated in a heat exchanger that used high-pressure exhaust steam from the turbine of a power plant. The resulting condensate was collected in a tank and pumped back to the power plant for reuse. The conclusion of the incident investigation was that the pump was destroyed by a condensation induced water hammer (CIWH) generated in the condensate return line; in this phenomenon, a volume of hot steam can get trapped by subcooled liquid, generating high-pressure shock waves when it rapidly collapses due to condensation. A CIWH can be devastating and, in this case, shattered the cast iron case of the pump and resulted in a workplace fatality. Understanding the physical principles behind CIWH is fundamental in preventing its occurrence and the losses associated with it. These principles are reviewed as part of the explosion's root-cause investigation, and recommendations are provided for the prevention of CIWH.