【正文】 ditions. 4 SMR Single Mixed Refrigerant C3MR Propane precooled Mixed Refrigerant C3MRN2 Propane precooled Mixed Refrigerant plus Nitrogen expander cycle Cascade Pure propane, ethylene, and methane DMRSWHE Dual Mixed Refrigerant with single pressure levels and SWHEs DMRBAHX Dual Mixed Refrigerant with multiple pressure levels and BAHXs TMR Triple Mixed Refrigerant Figure 1 Process Specific Power Comparison In general, mixed refrigerant processes are more efficient than pure po nent processes and additional cycles improve efficiency. However, both of these efficiency improvements e at the expense of increased process plexity. Another factor that plicates the picture above is that it only considers a process parison and not a refrigerant pressor or driver parison. Differences in pressor efficiency, the need for a speedincreasing gear, or driver efficiency can overwhelm some of the differences shown. Considerations for the generation and distribution of electric power for motor driven LNG processes can further plicate the parison. The LNG industry is changing in a number of areas that can also impact the selection of the best liquefaction process. While stickbuilt LNG plants are still the norm, modularization of LNG facilities are more attractive for offshore applications or where labor costs are very high and/or productivity is low. Modular construction is routinely applied for offshore oil processing. However, oil processing is much simpler than LNG production and process selection is generally not an important consideration. All these factors point to the need for more pact, lighter mechanical designs. Another important future consideration is the increasing need to reduce greenhouse gas emissions. Aeroderivative gas turbine drivers are an obvious choice for higher thermal efficiency or modular application but are not available in sizes as large as industrial gas turbines. Consequently, a process suitable for large 95 MW industrial gas turbines may not be well suited for a 35 MW aeroderivative gas turbine. Combinedcycle power generation is another option for achieving increased thermal efficiency and can be adapted to any of these processes, but is not well suited for modular construction or for offshore application due to the additional weight of motors, generators and distribution equipment as well as limited aeroderivative gas turbine choices for very large (100MW) power generators. The value of thermal efficiency can also bee a more important process selection criterion when the feed gas to the LNG plant is relatively expensive or supply is limited. An efficient process can allow for a reduced cost development plan through a lower gas rate, or extend the gas production plateau from the reservoir to make a more profitable project. 5 IMPACT OF EQUIPMENT COSTS Our process research paring liquefaction processes has demonstrated that the primary difference in the costs for the different liquefaction processes is the choice of equipment utilized. Process licensors tailor their process to make it capital and thermally efficient given the owners39。 工藝比較 液化天然氣的工藝過程往往受到具體功率（即火車做功除以壓縮機(jī)做功）的高度影響，這顯然是一個(gè)重要的參數(shù)，因?yàn)橹评鋲嚎s機(jī)在一輛液化天然氣火車上是最 12 大的成本和最大的能源消耗體。調(diào)整自己的過程，使其資本和熱效率的過程中協(xié)議業(yè)主的編好和約束 ， 然而，他們總不能在最后的分析中控制成本（包括設(shè)備及安裝）。在許多情況下，這些其它領(lǐng)域不能聚合成一個(gè)大 工程 的各種原因有：一些商業(yè)利益的調(diào)整、為了更困難的資源而等待降低開發(fā)成本、或者是 附近 LNG 工程 資源正在進(jìn)行中。通過使用釬焊鋁熱交換器和雙混合制冷劑，使壓縮機(jī)和驅(qū)動器達(dá)到最佳匹配，由此產(chǎn)生的過程將會有一個(gè)更低的功耗要求，并且 有 一個(gè)比傳統(tǒng)技術(shù)更低的資本成本 ， 釬焊鋁熱交換器的 DMR 過程表 明一個(gè)單位耗資有優(yōu)勢。一個(gè)有效率的進(jìn)程可以通過較低的氣量或者是從氣 13 田中擴(kuò)大天然氣生產(chǎn)平臺來考慮降低成本，以此使工程更有利可圖 ?？紤]到將來有限的氣體資源能夠支持這些大型火車，將需要 找到新的方法以更小的生產(chǎn)來維持成本的優(yōu)勢，做到這一點(diǎn)的一種方法就是選擇一個(gè)過程，以提高工程的執(zhí)行力，這個(gè)過程提高最大的靈活性去利用壓縮機(jī)，熱交換器，并且和許多競爭的供應(yīng)商一起控制。 preferences and constraints. However, they do not always have control over the cost (both equipment and installation) in the final analysis. Gas Turbines Gas turbine costs exhibit a reasonably high economy of scale. Large industrial gas turbines are the least expensive, but their cost advantage is lost in a modular or offshore environment due to their large weight and space requirements. Therefore, aeroderivative based designs will be more attractive. How