燃?xì)廨斉洚厴I(yè)設(shè)計(jì)外文翻譯--為了未來的發(fā)展，液化天然氣工藝處理過程中應(yīng)該注意的問題-wenkub
2023-06-17 22:33:43 本頁面
【正文】 een 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. By using BAHXs and a dual mixed refrigerant process to match the best fit of pressors and drivers available from multiple vendors, the resulting process will have a lower specific power requirement, and could have a lower capital cost than traditional technologies. The DMR process with brazed aluminum heat exchangers shows a unit cost advantage across a broad range of plant capacities and optimizes the tradeoffs of efficiency versus cost for a wide size range (36 MTPA) of 8 plants . EFFICIENT EXPANSION LNG plants have long benefited for profitable expansion trains, typically provided from the same large resource. While the number of discovered large fields available for multitrain development is shrinking, there is still the potential for economical expansion from nearby smaller resources. In many cases these other fields cannot be aggregated into one large project for a variety of reasons: difficulty aligning several mercial interests, waiting on reduced development costs for more difficult resources, or nearfield discoveries identified after the LNG project is underway. For all of these reasons it is desirable to have an easily expandable LNGplant. Treating refrigerant as a utility is a way to maximize the expandability and reliability of a multtrain facility. In this configuration all of the refrigerants that serve the same process function are bined into a single header and delivered as required to the LNG liquefaction sections. The refrigerant as a utility concept can be done with any liquefaction process, but is most suited for dual mixed refrigerants where the refrigerant return pressures can be higher resulting in smaller piping for distribution of refrigerant across the LNG plant. Figure 4 shows one such configuration 9 Treating refrigerant as a utility has several benefits: ? The trains do not necessarily need to be the same size, leading to customizable expansion to match mercial needs. ? All the refrigerants can be retuned to match changes in feed gas position to machinery limits as new gas supplies are brought online. ? Any spare capacity identified by testing after startup can be designed for and utilized during expansion. ? A mixtur
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