The degradation of engine oil and its influence on the formation of intake valve deposits is being discussed in this paper. Degraded samples of oil were prepared using a stationary engine testbed while deposition studies were performed using a bench top simulator. The degree of degradation, as indicated by the amount of polymeric, oxidized and oxidative products, increases as the engine oil is used over a period of time. The rate of degradation, however, varies depending on the quality of base oil and the type of additives used. It was observed that the degraded oil played an important role in the formation of inlet valve deposits.

Growing concern on global warming directly related to CO2 emissions is steering the implementation of carbon capture and storage (CCS). With Malaysia having an estimated 37 Tscfd (Trillion standard cubic feet) of natural gas remains undeveloped in CO2 containing natural gas fields, there is a need to assess the viability of CCS implementation. This study performs a techno-economic analysis for CCS at an offshore natural gas field in Malaysia. The framework includes a gas field model, revenue model, and cost model. A techno-economic spreadsheet consisting of Net Present Value (NPV), Payback Period (PBP), and Internal Rate of Return (IRR) is developed over the gas field’s production life of 15 years for four distinctive CO2 capture technologies, which are membrane, chemical absorption, physical absorption, and cryogenics. Results predict that physical absorption solvent (Selexol) as CO2 capture technology is most feasible with IRR of 15% and PBP of 7.94 years. The output from the techno-economic model and associated risks of the CCS project are quantified by employing sensitivity analysis (SA), which indicated that the project NPV is exceptionally sensitive to gas price. On this basis, the economic performance of the project is reliant on revenues from gas sales, which is dictated by gas market price uncertainties.

Natural gas produced from many major reservoirs can contain significant amounts of carbon dioxide (CO2) and must be treated to meet typical specifications for pipelines or liquefaction plant feed. The treatment process selected was low temperature CO2 distillation which involve high pressure operation and formation of highly concentrated CO2 streams. Pressure protection for high pressure, low temperature and high CO2 systems have been challenging to date because of potential solid CO2 formation during pressure let down and the consequent plugging. Blowdown or depressuring of process equipment during an emergency or planned shutdown is a critical process safety operation. It may be necessary in the event of fire, leak, pipe rupture or other hazardous situations, as well as for planned shutdown. Devices such as blowdown valves, relief valves, restriction orifices, rupture disks, and safety valves transfer the potentially hazardous content of process equipment to a safe lower-pressure location or to the flare/vent system for controlled combustion or safe venting. To ensure blowdown will be executed safety and effectively, a number of design concerns must be addressed such as low temperature solid CO2 identification and Minimum Design Metal Temperature (MDMT) for piping and equipment material selection. Rapid depressurizing and gas expansion can potentially put equipment at risk of brittle fracture if the temperature goes below its ductile-brittle transition temperature of the selected material and potential plugging due to solid CO2 formation. In addition, the entire pressure relief system including safety valves, relief orifices, flare piping and knockout drums, must be sufficiently sized to handle the flowrates that occur during blowdown, in addition to the piping and capacity of the flare/vent system. Accurate prediction on the minimum vessel wall temperature during blowdown is important for selecting the appropriate construction material, for reducing overdesign and consequently lowering project cost. Similarly, having an accurate prediction of the maximum flow rate during blowdown reduces overdesign associated with the relief valve/network, without compromising on safety. The paper will address the potential of solid CO2 formation based on proprietary software for blowdown and proposed some mitigation plan with respect to solid CO2 formation within the process piping and equipment.