Improving thermal performance of water bath heaters in natural gas pressure drop stations

One of the main components of a natural gas pressure drop station is the water bath heater (also known as line heater) that preheats the gas flow before its pressure is reduced through a throttling process. A major problem of this kind of heater is its low thermal efficiency, which is roughly 40–50%, making natural gas pressure drop station an exergy destructive point in the gas transmission system. This study proposes the use of a twisted flow disturber through the gas coil within the water bath heater to increase the rate of heat transfer from water to the coil, and subsequently increasing the thermal efficiency of the heater. This process is numerically simulated for a real water bath heater in a case study gas station in Iran to observe and analyze the effects of employing this type of flow disturber. The nominal capacity of the case study heater is 1000 m3/hr of gas to be heated up. The results show that the flow disturber might improve the average Nusselt number of the gas flow through the coil by about 20%, increasing the thermal efficiency of the heater and reducing its fuel consumption.