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Abstract

This study investigates the performance of a hybrid turboexpander and fuel celi (HTEFC) system for power recovery at natural gas pressure reduction stations. Simulations were created to predict the performance of various system configurations.

Natural gas is transported at high pressure across large distances. The pressure of the natural gas must be reduced before it is delivered to the consumer. Natural gas pressure reduction is typically achieved using pressure reduction throttling valves. In a limited number of cases pressure reduction is achieved using a turboexpander. This method has the added bonus of power generation. There is a considerable temperaturę drop associated with the turboexpander process. Preheating is reąuired in many cases to avoid undesirable effects of a Iow outlet temperaturę. This preheating is typically done using gas fired boilers. The hybrid system developed by Enbridge and Fuel Celi Energy is a new approach to this problem. In this system a Molten Carbonate Fuel Celi (MCFC) running on natural gas is used in conjunction with the turbinę to preheat the gas and provide additional Iow emission electrical power

Various system configurations were simulated and factors affecting the overall performance of the systems were investigated. Power outputs, fuel reąuirements and efficiencies of various system configurations were found using typical gas flow variation data. The simulation was performed using input data from the current city gate pressure reduction station operated by Utilities Kingston. Using the data provided by Utilities Kingston the performance of various potential HTEFC system configurations were compared. This thesis illustrates the benefits of