Optimizing Steam and Condensate Systems: A Case Study

Optimization of Steam & Condensate systems in any continuous-process plant results in substantial reduction in purchased energy cost. During periods of natural gas price hikes, this would benefit the plant in controlling their fuel budget significantly. If planned well, the energy cost savings efforts could also give the spin-off benefit of waste water reduction from the plant. This paper highlights the efforts taken by the management of a medium sized petroleum refinery in Mid-West USA. This site has two sections of process units with tank farms located in between them. The refinery uses its own process off-gases and purchases additional natural gas to fire its Boilers and process heaters. Steam is also generated from the exhaust gases of the process heaters. An optimization study was conducted at this refinery site during Sep – Nov 2006, to identify opportunities to reduce the energy cost, to improve the steam system’s reliability, and to reduce the waste water loading to the treatment plant. The study identified 8 energy and water use optimization opportunities that would result in a total cost savings of $ 2.67 million annually. The initial estimates indicated that all the projects recommended by the study would have simple payback periods of less than 2 years. The plant management decided to pursue 3 of the 8 recommendations and completed Basic Engineering design during early 2007. The management is interested in pursuing the other identified energy savings opportunities also upon implementing the initial 3 projects. Upon implementing all the identified projects by the study, the refinery’s energy use is expected to reduce by 89,900 MMBtu/yr & Water usage would reduce by 38,900 kGals/yr. The reduction of hot condensate dumping to the waste water pond is also expected to save the bug-life in the waste water pond. This case study is a good example and motivation for all the engineers and managers, who are responsible for maintaining the efficiency and reliability of the steam systems in their plants