Evaluation of thermodynamic models used for wet gas compressor design

Abstract

Big investments are done in developing wet gas compression technology. The reasons behind these investments are the need to improve the recovery from old reservoirs and the need to make small reservoirs economically profitable.This work will use a model with the software NeqSim in order to simulate a wet gas compressor and evaluate the sensitivity of performance evaluation to the Equation of State used. It will be easier to evaluate how much the data provided by vendors will effectively represent the real compressor's performance in the needed operating conditions. Then it is needed to know how much the work required from the compressor is influenced by the Equation of State used for the evaluation.When it comes to the compressor work estimation, a maximum of 3% of deviation has been identified. According to the API 617 [32], this deviation is considered acceptable.The deviation in estimating the compressor outlet temperature is maximum 2 K and it depends on the composition of the fluid and the pressure of operation. For the polytropic efficiency instead, the highest deviation is 2%. Again, according to the standard API 617, a deviation up to 2% is considered acceptable.Furthermore, this work will highlight the parameters that require higher accuracy when dealing with wet gas compressor performance evaluation. Thus, any equation of state able to give reasonable accuracy in these parameters will be expected to give accurate results in compressor's performance evaluation.Finally, in conjunction with the preliminary work of this thesis [3], it has been possible to identify the Cubic Plus Association (CPA) equation of state as more suitable for wet gas calculations than Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) Equations of State.