Application of water reheating system for waste heat recovery in NG pressure reduction stations, with experimental verification

In this study, to recover a part of the waste energy from an indirect water bath heater (IWBH) of a natural gas (NG) pressure reduction station, the use of a water reheating system (WRs) is studied. The proposed plan involves a gas-water heat exchanger (G-WHE) installed on the chimney of the heater. The cooler water of IWBH circulates through a pump into the G-WHE. The proposed plan was implemented at one of the IWBHs of the city gate station (CGS) in Shahrekord, Iran, and the results were analyzed. The results show that the proposed plan reduces the fuel consumption of the heater by about 45%. As a result, the energy and exergy efficiencies of the station increase by about 80% and 100%, respectively. Economic analysis also indicates that the capital reverse factor for such a station is about 1.3 years. Studies were also conducted to reduce the pressure loss in gas and water streams of the G-WHE. Accordingly, the best designs for this heat exchanger (HE) are also presented. For designing an optimal HE, minimizing the pressure drop and weight, optimizing the interrelated angle of the tubes, and some other parameters are also considered.