Subsea gas compression and pumping technologies have been identified as a solution for accessing gas reservoirs that may be otherwise either inaccessible or economically unfeasible to drill. Subsea stations offer a fast-track development solution with flexible, multi-phase deployment, and other inherent advantages whilst filling this application. Pumping stations require a significant amount of process equipment improvements and integration solutions; however, we will focus here on the rotating machinery, process pumps in specific. In the present research, all available operator or manufacturer's reports and published papers are reviewed and a criterion is developed for subsea pump selection base on: The conventional subsea separation system is compared to a multi-phase pumping one. All applicable types of subsea pumps including Helico-Axial (HAP), Twin Screw Pump (TSP) and Electrical Submersible Pump (ESP) are compared. All parameters in pump type selection such as Gas Volume Fraction (GVF), water cut, differential pressure, head, flow rate, fluid viscosity, RPM, sand content, water depth, Opex, Capex, reliability and asset life is discussed. Material selection as a critical part of the pump selection is studied thoroughly.

Why can even the most reliable turbomachinery get tripped up? In some cases, it's all about bad vibrations--literally. This paper explores the challenges one site had with repeated centrifugal compressor trips caused by high vibration over a period of 25 days. It outlines the troubleshooting attempts made to remedy this issue, it's root cause, and the resulting solution. This issue occurred at a site with a train configuration of gas turbine driven centrifugal compressors. After 48 hours of its first startup, the machine tripped due to high vibration at the compressor drive end. Initial attempts to fix the problem included checking the vibration probe gap voltage setting, as well as swapping vibrations probes. After these tasks were completed, the site again attempted to run the machine. 48 hours later, it tripped again. During this time, the vibration gradually increased, staying above the alarm of 50 microns and tripping at 70 microns. The trip setting was increased to 75 microns, but after restarting, the unit continued to trip due to high vibrations. All components were removed and thoroughly examined. Clearances were measured per the standard checklist. The condition of the couplings was found to be normal. The journal bearing pads had minor scratches. The thrust bearing pads were not affected by the failure. Alignment readings were found to be normal. However, residual unbalance was found on the rotor. This residual unbalance was found to be the root cause of the tripping issue. The journal bearing clearances were thus adjusted from 0.17 mm to 0.13 mm. It was also advised to perform high speed balancing checks in the manufacturer's facility. The lube oil inlet pressure was adjusted to meet the requirements for the new bearing clearance. Adjusting the bearing clearance, along with the adjustments in lube oil inlet pressure, resulted in improved vibration readings. This case study provides the detailed analysis of the root cause of the frequent trips as well as the process that was followed to fix the problem.

This is a case study explaining the failure of an inlet nozzle to a Main Cryogenic Heat Exchanger (MCHE) used in a LNG plant, causing the refrigeration compressors to be in shutdown for 6 weeks. This resulted in loss of LNG production. The failure analysis of the nozzle indicated the cause of failure was Mercury embrittlement that is made of Aluminum, which caused flange leakage. Main Cryogenic Heat Exchanger (MCHE) is made of aluminum and part of refrigeration process in a LNG plant MR (mixed refrigerant) loop. The Mercury embrittlement is a form of liquid metal embrittlement (LME) and a complex metal fracture mechanism that occurs without any warning indications. Mercury embrittlement, being a significant problem in LNG Plants using aluminum MCHE, have led to number of major plant incidents worldwide. Mercury is always present in natural gas feed stocks, sometimes in quantities sufficient to cause severe attack and failure of Aluminum heat exchanger. To avoid Mercury embrittlement failure in aluminum heat exchanger tight limits have been placed on allowable mercury levels in natural gas passing through Aluminum heat exchanger. The natural gas is pretreated with mercury removal units before entering the refrigeration units in a typical LNG plant. Root cause of this failure is identified as the failure of mercury removal units to remove the mercury efficiently. In this case study, Different type of mechanisms has been highlighted by which the mercury degrades the aluminum heat exchanger that includes LME, Amalgamation and Amalgam Corrosion. The importance of mercury removal units in LNG plants is emphasized. Different types of mercury removal technology are explored and discussed. This case study Introduce the newly developed high activity mercury removal absorbents that allows greater flexibility in the design of LNG plants. These absorbents allow for smaller beds, which coupled with new reactor designs improve savings in compression costs. It is now possible to locate the mercury removal units upstream of the main gas processing plant and thus avoid mercury emissions and contamination of any co-produced Natural Gas Liquids (NGL) in a LNG plant.

Turbo machineries are considered as one of the most critical equipment in oil, gas and petrochemical plants which needs highly safe and reliable operation. Generally, turbomachineries will be driven by Electric motor or steam turbine or gas turbine in process plant which depends upon the application. This case study represents an experience on complex turbo machinery driver misalignment which is electric motor. In this specific case, electric motor drives Gearbox and centrifugal compressor. Centrifugalcompressor is used for process gas pressurisation. This misalignment was observed between electric motor and gearbox. Electric motors are basically electrical machines which converts electric energy into mechanical energy. So, they are used as driver to drive gearboxes, compressors or pumps and other machines. These machineries have rotating parts at hot at high speed. While units are in new installation phase, machinery alignment shall be performed between the driver and driven machineries. Unlike other rotating machines, electric motors have high thrust clearance. During operation rotor will come to magnetic centre. Prior to the installation of coupling solo run will be performed on the motor to evaluate the performance of motor and to ensure the magnetic centre.