Impurity removal plays a crucial role in natural gas processing operations. Raw gas streams typically contain a number of impurities, such as water, H2S, CO2, and volatile organics (among others) that must be removed before gas can enter downstream processing equipment. This is achieved through a series of steps, many of which rely on the proper selection of heat transfer fluids in order to be effective.
A number of factors will come into play when choosing a heat transfer fluid for a particular process. One of the biggest determinants, however, is the temperature range in which the processing facility will have to operate. The operating range of a heat transfer fluid is defined as the range between the pumpability point and the maximum bulk fluid operating temperature. Proper fluid selection is especially critical in facilities exposed to cold temperatures due to the fact that at the pumpability point, the fluid can become too viscous for pumps to maintain adequate flow, leading to a number of costly issues that can increase maintenance requirements and reduce efficiency.
The maximum bulk fluid operating temperature is also important because it plays a critical role in the heat transfer fluid’s ability to withstand thermal degradation. When choosing a heat transfer fluid, operators should avoid options that have maximum bulk fluid operating temperatures below the bulk heat transfer fluid temperature required by the process.
Most of the heat transfer fluids used in gas processing applications today are mineral oil based or synthetic. Diesel and kerosene are sometimes used in petrochemical processes, however they typically have low flashpoints and autoignition points, which creates a need for the implementation of additional safety measures. Both diesel and kerosene are also more volatile than mineral oil and/or synthetic heat transfer fluids, and as a result, they often require frequent replacement/addition due to evaporation.
After a heat transfer fluid has been selected, routine testing should be conducted to determine if the fluid is effectively maintaining its original chemical properties. Doing so will ultimately ensure that impurity removal remains safe and efficient, and that gas processing equipment is adequately protected over time.