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根据乙烯装置中的用冷需求,将乙烯装置的深冷分离过程分为变温冷却过程和定温冷凝过程,变温冷却过程指的是裂解气的预冷过程,定温冷凝过程指的是乙烯装置中各塔塔顶冷凝器中的换热;分析了乙烯-丙烯复叠制冷系统的换热集成曲线,可知在裂解气的预冷阶段,冷热物流换热温差大。提出一种组合制冷系统,它集成了纯工质复叠制冷和混合冷剂制冷,其中的多元混合冷剂制冷系统为乙烯深冷分离的变温换热过程提供冷量。并用Aspen Plus软件对混合冷剂系统进行建模,使用遗传算法优化,优化结果表明在替代原制冷系统6895.5 kW冷量负荷的情况下,功耗降低521.6 kW,节能14.7%。 相似文献
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混合冷剂压缩机是整个工艺流程的关键设备,压缩机能否正常达到工况直接决定产品的品质及运行的能耗。针对低浓度含氧煤层气深冷液化混合冷剂制冷单元能安全有效的提供冷源,本文着重介绍离心压缩机组工作原理、工艺流程、控制系统配置及组成,并对机组的定气量/气压、防喘振控制方案及控制难点进行详细阐述。 相似文献
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研究某百万吨级乙烯装置所采取的乙烯产品外送方案,发现乙烯产品外送方案对乙烯制冷压缩机、丙烯制冷压缩机的功率有着显著的影响.不同的乙烯产品外送方式对应乙烯装置不同的公用工程消耗、能耗、设备投资和操作运行费用.通过对比,得到了最优化的乙烯产品外送方案,实现乙烯装置的经济效益和市场竞争力的提高. 相似文献
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压缩机工作时,当负荷降低到一定程度时,会产生剧烈的喘振现象。喘振会严重损坏机体,产生严重后果。旨在模拟催化裂化富气压缩机喘振及其控制,由于喘振产生的时间很短,与催化裂化运行时间相差数千倍,所以要在两个不同尺度时间下进行模拟。本文基于压缩系统机理模型在UniSim中开发了一个适用于压缩机主动控制的模型,同时为克服主动执行机构在压缩机稳定区带来的附加损耗,针对压缩机喘振现象设计了切换控制方案,在压缩机喘振时采用主动控制进行喘振控制,而在稳定工况点则取消主动控制作用。最后将该方案应用于压缩机双时间尺度模拟中,并从不同的时间尺度下对比了喘振控制对催化裂化过程的影响,整个过程验证了方案的有效性以及该方案可以同时解决防喘振控制使压缩机无法在高性能区工作和主动执行机构所带来的能耗增加的问题。 相似文献
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Liquefied natural gas (LNG) is the most economical way of transporting natural gas (NG) over long distances. Liq-uefaction of NG using vapor compression refrigeration system requires high operating and capital cost. Due to lack of systematic design methods for multistage refrigeration cycles, conventional approaches to determine op-timal cycle are largely trial-and-error. In this paper a novel mixed integer non-linear programming (MINLP) model is introduced to select optimal synthesis of refrigeration systems to reduce both operating and capital costs of an LNG plant. Better conceptual understanding of design improvement is illustrated on composite curve (CC) and exergetic grand composite curve (EGCC) of pinch analysis diagrams. In this method a superstruc-ture representation of complex refrigeration system is developed to select and optimize key decision variables in refrigeration cycles (i.e. partition temperature, compression configuration, refrigeration features, refrigerant flow rate and economic trade-off). Based on this method a program (LNG-Pro) is developed which integrates VBA, Refprop and Excel MINLP Solver to automate the methodology. Design procedure is applied on a sample LNG plant to illustrate advantages of using this method which shows a 3.3% reduction in total shaft work consumption. 相似文献
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Sung Gun Lee Sang il Han Yoon Sup Byun Kyu Suk Hwang Young Han Kim Dongil Shin En Sup Yoon 《Korean Journal of Chemical Engineering》2005,22(4):503-511
As boiler plants which supply steam and heat into chemical plants become larger in scale and more complicated, accidents caused
by the wrong understanding and erroneous operations are increasing. In this paper, we present a computer-aided system that
should prevent such mistakes and synthesize operating procedures for start-up of steam boiler plants: 1) This system generates
a goal tree by generalizing and classifying the operational situations hierarchically, and uses the relationship between an
operation and a function to search for primitive operations in the lowest level of the goal tree. 2) It simulates changes
in operational situations caused by the action of primitive operations with heuristic knowledge of transition relationships
between operational situations. 3) It determines the priority of low-level operational situations and primitive operations
by referring to the database on hazardous situations and properties. We have applied the developed system to a large-scale
boiler plant to demonstrate its effectiveness. 相似文献
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Myung Wook Shin Dongil Shin Soo Hyoung Choi En Sup Yoon 《Korean Journal of Chemical Engineering》2008,25(1):7-12
Proper handling of boil-off gas (BOG) significantly affects the operational efficiency as well as the safety of the whole
LNG gasification plant. Due to the not well-known inherent dynamics, it has been suspected that the BOG compressors are being
operated at too much capacity, unnecessarily consuming too much energy. An empirical model is proposed for the estimation
of the boil-off rate (BOR) in an LNG storage tank, based on the specification supplied by the LNG storage tank manufacturer.
By using the BOR model, an optimal operation algorithm is proposed for a safe and energy-saving BOG compressor operation,
which minimizes the power consumption while preparing against the potential failure of one of the operating compressors. Case
study results indicate that the energy consumption could be reduced by a half of the conventional method, by increasing the
tank pressure while the safety is maintained. The proposed method is expected to be able to contribute to improving the efficiency
of the whole gasification plant operation and control without tempering the safety requirements. 相似文献
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天然气的预处理和液化是海上天然气利用前的两个关键环节。选取变压吸附分离法(PSA)作为浮式LNG预处理流程的工艺方法,选择新型CO2预冷空气膨胀液化流程作为浮式LNG天然气液化的工艺方法,并对以上预处理和液化流程进行了模拟计算与分析。结果表明,采用双层吸附剂变压吸附(PSA)预处理流程能耗低,全气体运行避免了液体吸收剂随波浪晃动的缺点,可以满足海上天然气预处理的要求;CO2预冷空气膨胀液化流程在预冷剂及制冷剂循环过程中,没有液体的产生,安全性高;以上预处理和液化流程适应于海上晃动的LNG平台。 相似文献
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针对液化天然气(LNG)接收站的蒸发气体(BOG)再冷凝工艺系统能耗偏高的问题,对现有BOG再冷凝系统进行了工艺流程优化。通过对BOG压缩机入口温度、BOG压比及物料比等影响BOG再冷凝工艺能耗的主要运行参数的分析,提出了利用高压LNG预冷增压后的BOG,降低BOG压缩机压比的工艺流程。优化后的BOG再冷凝工艺较原工艺可节约BOG压缩机能量消耗32. 5%,且优化后的流程改善了LNG下游管网输气峰、谷负荷波动时的操作弹性,有较好的调峰功能。 相似文献
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乙烯装置的分离过程要在低温下进行,由乙烯制冷系统提供所需冷量。乙烯制冷系统为封闭式循环,独立于分离单元之外。将乙烯分离单元与制冷系统同时优化,能有效提高装置用能效率。复叠式制冷级数是当前乙烯工业中使用最为广泛的制冷技术。本文针对乙烯分离过程和配套的复叠制冷系统,采用Aspen Hysys进行模拟并进行(火用)分析,发现系统主要的(火用)损失发生在换热与压缩两部分,其占总(火用)损失的83%,为节能的重点。进而通过夹点技术对冷剂配置进行分析,发现-56℃以上各温位的冷量配置不合理,远超过理论最小值,-56℃以下各温位的冷量基本达到理论最小值。提出了采用多股流换热器的换热网络理论设计方法,并对冷剂进行重新配置,该理论方案可以降低丙烯制冷压缩机约30%的功耗,并节约部分乙烯制冷压缩机功耗,显著降低了乙烯深冷分离能耗。 相似文献
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在百万吨级前脱乙烷流程的乙烯装置裂解气压缩机工艺系统中进行了凝液汽提工艺的研究。模拟计算了凝液汽提塔在裂解气压缩机第四与五段之间时裂解气压缩、分离和制冷系统的变化情况,考察了该塔塔压的变化对这些系统的影响。研究结果表明,应用凝液汽提塔可降低脱乙烷塔塔底温度13℃以上,减少低压蒸汽消耗量,不会增加乙烯制冷压缩机的功率,但增加裂解气压缩机和丙烯制冷压缩机的功率,使综合能耗有所上升;凝液汽提塔塔压对低压蒸汽消耗量的影响较大,而对裂解气压缩机、丙烯和乙烯制冷压缩机的功率影响较小,当塔压为0.9MPa时,综合能耗最低。当凝液汽提塔被设置在裂解气压缩机第四与五段之间时,不建议在新建前脱乙烷流程的乙烯装置中应用它。 相似文献
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压缩机工作时,当负荷降低到一定程度时,会产生剧烈的喘振现象。喘振会严重损坏机体,产生严重后果。催化裂化装置中,为避免压缩机的喘振,通常采用大功率压缩机使其稳定工作,常带来固定投资高、操作费用大等问题。通过采用主动控制,可以扩大压缩机的稳定工作范围,并使压缩机工作在高性能区,因此本文在选型时选择一个比实际较小的压缩机来实现压缩机的工作,虽然其结果可能使压缩机大部分时间工作于喘振区,但通过主动控制作用可以使其稳定工作,同时还可以达到减小压缩机的投资费用和操作费用的目的。文中分别对控制方案、控制算法进行了详细的描述,最后通过实际案例验证了该方案的可行性和有效性。 相似文献