![]() ![]() Second-stage compressor, C16 limit notes:.Dry gas seal temperature limit: 250☏ (121☌).First-stage compressor, C51 limit notes:.Other compressor design constraints include: standard flow, divided by suction or discharge pressure. standard flow, with speed, efficiency and power actual flow, with speed and polytropic efficiency as parameters Gas compressor performance curves provide information about the predicted compressor performance. power turbine speed (two-shaft engine only). Gas turbine performance curves (ISO) provide nominal performance data for the gas turbine at site conditions ( Tables 2 and 3). Ambient reference conditions corresponding to ISO standards are: Specifications presented in Table 1 are for a two-stage, gas turbine-driven, single-shaft centrifugal compressor. The parameters and key assumptions for the compressor study are outlined below.īasis and assumptions. At flows lower than the stability point, the compressor initially shows a reduced capacity to generate head with reduced flow, until it experiences reverse flow-i.e., when the gas flows from the discharge side to the suction side. The operating range of the first-stage compressor is limited by maximum (9,500 rpm) and minimum (5,000 rpm) operating speeds, maximum available power, choke flow and stability (surge) limits. Second-stage HP compressor performance curve. First-stage LP compressor performance curve.įig. The gear ratio between the first (LP) stage and the second (HP) stage is 2.48.įig. The compressor performance curves of a two-stage export gas centrifugal compressor, operated at variable speeds, are shown in the head-flow characteristic in Fig. Therefore, model developers must adjust, refine, and validate their models with actual plant data to simulate more accurately the real process and events. However, there is always some level of uncertainty and inaccuracy due to the use of simplifications, assumptions and numerical calculations. ![]() ![]() Modern simulation software is useful for providing quick, reliable and cost-effective solutions to problems related to steady state and dynamic study. Compression operating conditions can be successfully selected by reading the compressor operating curve, which is based on compressor inlet pressure and gas flow. A compressor operating map is provided for selection of the compressor speed, operational stage(s), and recirculation parameters. However, the temperature of the compressor discharge also increases at reduced flow and higher speed therefore, the recycle is also required to maintain the compressor discharge temperature within a defined limit.Ī step-by-step approach is discussed 1 to check compressor performance by ascertaining the minimum possible suction pressure at various fixed flows. To meet the required export gas pressure, the speed of the compressor must be increased. The compressor operation becomes unstable due to reduced inlet pressure and reduced flow. Consequently, inlet pressure to the compressor is reduced. Compressor operation is challenged when the gas well reservoir pressure is reduced (due to reservoir depletion), and when the full well steam (FWS) water cut increases and the gas fraction in the FWS decreases. Normally, the export gas centrifugal compressor works well under constant inlet pressure. Therefore, an export gas compression system is required, with a centrifugal compressor being the most suitable for variable sales gas demand and near-constant export pressure. Produced gas pressure at the wellhead normally is not sufficient to allow export for sales and further treatment. Singh, Consultant, Kuala Lumpur, Malaysia This tends to maximize the number of simultaneous blocking i/o requests, which improves overall system throughput.Optimize compressor parameters for reduced inlet pressure and gas flow If the scheduler has to decide between scheduling between two processes, then all other things being equal, it will favor the process that is making blocking system calls more frequently. The goal is to get interactive processes to do a little bit of computation, make a blocking system call to request some data from a slow device, and then get rescheduled as soon as the data is returned. If the scheduler is doing a good job of guessing the time to the next blocking system call, then a large fraction of processes will actually voluntarily release the CPU by doing a blocking system call. Before the scheduler gives control to process X it sets up a timer that will interrupt at a time just slightly longer than process X's moving average. Roughly speaking, the scheduler is designed to estimate the moving average of the times between a process's blocking system calls. The scheduler is invoked after servicing every interrupt (keyboard, mouse, touchscreen, network, disk-transfer finished. I believe that in modern operating systems the time-slices are variable length.
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