燃气输配毕业设计外文翻译--为了未来的发展，液化天然气工艺处理过程中应该注意的问题(编辑修改稿)

燃气输配毕业设计外文翻译--为了未来的发展，液化天然气工艺处理过程中应该注意的问题(编辑修改稿)内容摘要：

iciency in a simple cycle configuration. This efficiency loss can be overe with bined cycle, but in simple or bined cycle the result is usually a higher capital cost. The implementation of an allelectric drive configuration is even more difficult at reduced economies of scale where the use of larger lower cost turbines bees problematic due to difficulties managing the dynamic response to electrical load changes spread across fewer units. In the end though, the choice of an allelectric drive configuration is condensed to a trade off between a higher capital cost and the increased plant availability that electric motors can achieve. Compressors Compressors exhibit a very high economy of scale. Refrigerant pression costs are primarily a function of the number of pressor cases needed. Consequently, it is important to minimize the number of pressor cases. Likewise it is important to limit the required rotor diameter of the centrifugal pressor wheels to stay within the capabilities of multiple vendors. This requires limiting the volumetric flow rate feeding these pressors through reduced refrigerant circulation or higher refrigerant suction pressure. Again the dual mixed refrigerant process allows the process designer the 6 flexibility to optimize the pressor inlet suction volumetric rate to maximize throughput within the design capability of at least four suppliers. Heat Exchangers Cryogenic heat exchanger costs are primarily related to the surface area supplied. There will always be a tradeoff between exchanger area and pressor power to reach a minimum overall cost. Spiral Wound Heat Exchangers (SWHEs) are the standard cryogenic heat transfer equipment for the base load LNG industry. SWHEs have an excellent service record in LNG service。 however, they are expensive, have long delivery times, and are limited to two manufacturers. Another option is to use brazed aluminum heat exchangers (BAHXs), which have a lower cost per unit area than SWHEs, and can be aggregated easily into blocks of surface area to meet large heat transfer requirements effectively. BAHXs also easily acmodate sidestreams which allow refrigerant systems with multiple pressurelevels to be readily incorporated. BAHXs have been demonstrated in LNG service in cascade processes and smaller mixed refrigerant processes. BAHXs are built in small units (cores) typically manifolded together and insulated in a cold box. A typical design would require about 30 cores to provide the exchanger area needed for a 3 MTPA LNG train. These exchangers are available from five manufacturers. Having multiple vendors ensures not only petitive prices, but also flexibility in acquiring the exchangers in time to meet the project schedule. PROCESS SELECTION What would an ideal liquefaction process look like? It would be a DMR process such as shown in Figure 2 below for low specific power consumption and flexibility to optimize pressor design. Including multiple levels of cooling in the warm mixed refrigerant circuit allows more flexibility to meet pressors volumetric limitations. ExxonMobil has synthesized these traits with known liquefaction processes, adding our own proprietary optimizations resulting in this configuration. 7 Figure 2 ExxonMobil DMRBAHX Process Schematic It would utilize BAHX exchangers to provide: • Multiple manufacturers for cost and schedule benefits, • Economic scale up over a wide range of throughputs, • Ease of modularization The BAHX exchangers would be protected from operational and design problems associated with multiphase maldistribution by effecting refrigerant separation at each pressure level of the warm refrigerant and feeding only liquids to the BAHX cores while bypassing the vapor back to the pression system. It would utilize gasturbinedriven centrifugal pressors large enough to capture the economy of scale available but small enough to ensure that multiple pressor vendors are capability of supplying the sizes needed. The results of our LNG process research applying these principles to a potential LNG development are shown in Figure 3.。