Techno-economic studies of environmentally friendly Brayton cycles in the petrochemical industry

摘要

Brayton cycles are open gas turbine cycles extensively used in aviation andindustrial applications because of their advantageous volume and weightcharacteristics. With the bulk of waste exhaust heat and engine emissionsassociated, there is need to be mindful of environmentally-friendliness of theseengine cycles, not compromising good technical performance, and economicviability.This research considers assessment of power plants in helicopters, and aeroderivativeindustrial gas turbines combined-heat-and-power (ADIGT-CHP) in thepetrochemical industry. Thus, it consists of two parts: part A focuses onperformance analysis of helicopter gas turbines, while part B entails technoeconomicand environmental risk assessment of ADIGT-CHP in thepetrochemical industry. The investigation encompasses comparativeassessment of simple cycle (SC) and advanced gas turbine cycle optionsincluding the component behaviours and the environmental and economicanalysis of the systems. The advanced cycles considered include: recuperated(RC), intercooled (IC), intercooled-recuperated (ICR), and low pressurecompressor zero-staged (LPC-ZS), cycles.The helicopter engines are analysed and subsequently converted to small-scaleADIGT engines. Also, modelling combined-heat-and-power (CHP)performances of small-scale (SS), and large-scale (LS) ADIGT engines isimplemented. More importantly, a large part of the research is devoted todeveloping a techno-economic model for assessing, predicting, and comparingviability of simple and advanced cycle ADIGT-CHP in the petrochemicalindustry in terms of net present value (NPV), internal rate of return (IRR), andsimple payback period (SPBP). The techno-economic performances of theADIGT-CHP cycles are measured against the conventional case of grid powerplus on-site boiler. Besides, risk and sensitivity of NPV with respect to uncertainchanges in grid electricity cost, gas fuel cost, emission cost, and electricityexport tariff, are investigated. Two case studies underlie the development of thetechno-economic model. One case study demonstrates the application of themodel for large-scale (LS) ADIGT-CHP, and the other for small-scale (SS)ADIGT-CHP, all in the petrochemical industry. By so doing, techno-economicand environmental risk analysis framework (a multi-disciplinary preliminarydesign assessment tool comprising performance, emissions, economic, and riskmodules) is adapted to ADIGT-CHP in the petrochemical industry, which is theaim of this research.The investigation and results led to the conclusions that advanced cyclehelicopter and ADIGT engines exhibit higher thermal efficiencies than simplecycle, and that savings exist in operational costs of ADIGT-CHP above theconventional case. Thus, for both SS ADIGT-CHP, and LS ADIGT-CHP cases,all ADIGT-CHP cycles are profitable than the conventional case. For LS ADIGT-CHP category, the IC ADIGT-CHP is the most profitable, whereas for SSADIGT-CHP category, the RC ADIGT-CHP is the most profitable. Thecontribution to knowledge of this research is the development of a technoeconomicmodel for assessing, predicting, and comparing viability of simple andadvanced cycle ADIGT-CHP in the petrochemical industry in terms of NPV,SPBP, and IRR over the conventional case of grid power plus on-site boiler. Asecond contribution is the derivation of simple and advanced cycle small-scaleADIGT and ADIGT-CHP from helicopter engines.Cont/D.