Efficiency and heat losses of indirect water bath heater installed in natural gas pressure reduction station; evaluating a case study in Iran

Indirect fired water heaters are typically used to raise the temperature of fluids such as natural gas. Without heaters, gas freezing (because of Joule-Thomson effect) can occur, while it is passing through the pressure reduction installation, damaging valves and instrumentation, or even causing gas supply interruption. At present, water-bath heater is widespread used for gas industry to heat the natural gas. Its large size, the need for water reposition, its low thermal efficiency and large heat losses from flue gas (exhaust) are the main operational problems of the traditional equipment. In this paper energy calculations in all parts of a typical heater have been considered. Then main energy losses, specially from chimney was calculated and then the heater efficiency was obtained. As a case study, one city gate station (CGS) located in Shahrekord city with nominal capacity of 120,000 SCMH has been considered. Based on statistical data collected from station during one year, calculations showed that more than 38% of combustion energy will be lost through the stack and into the ambient. It also has been observed that about 2% of losses is from the heater surfaces. The heater efficiency of this test case is less than 47%. The total energy losses from stack and surfaces in the year under study were 4667Gj and overall gas consumption for burners was 411000m³ which approximately costs about 137000$.

Keywords:

Energy losses , gas pressure reduction station , Stack losses , efficiency