化工节能中的热泵精馏工艺流程分析

介绍了几种典型的精馏热泵流程 ,分析了它们的特点、应用条件及节能效果 ,供进行热泵精馏可行性设计时参考。     

中间再沸式热泵甲醇精馏节能及经济分析

典型的年产60万t甲醇双效精馏流程能耗较大,为此提出了中间再沸式热泵精馏方案。采用Aspen-Plus化工流程模拟软件,以能耗最低为目标函数,对甲醇中间再沸式热泵精馏进行了模拟与分析,得到了合适的工艺参数。模拟结果表明:在满足生产要求的条件下中间再沸式热泵精馏相比于双效精馏系统,节能48.34%,运行费用节约24.14%。每年可节省运行费用1 056万元。     

MVR热泵精馏处理回收稀DMAC水溶液

针对稀DMAC水溶液中DMAC的回收,提出了三种机械蒸汽再压缩(MVR)热泵精馏方案,即MVR-常规两塔精馏工艺、三级MVR单塔精馏工艺和三级MVR三塔精馏工艺.采用Aspen Plus化工流程模拟软件,以能耗最低为目标函数,对以上三种工艺方案分别进行了模拟与优化,得到了每种热泵精馏方案合适的工艺参数和设备参数.研究结果表明:与常规单塔精馏工艺相比,以上三种MVR热泵精馏工艺节能分别为81.7％、69.9％和90.3％;因此就节能而言,采用三级MVR三塔精馏工艺为最佳;基于综合经济效益评价,MVR-常规两塔精馏工艺为处理本体系的最佳精馏工艺.     

热泵精馏在气分装置丙烯塔中的应用

在气分装置的丙烯精馏中应用热泵精馏技术可以显著降低装置的能耗。本文通过Aspen HYSYS软件,对惠州炼油二期中70万t/年气体分馏装置的丙烯塔进行流程模拟。采用三种不同的蒸汽加压式热泵精馏方式:塔顶气体压缩式,分割式和塔釜液体闪蒸再沸式进行模拟,并将模拟得到的能耗与原有常规双塔精馏的能耗进行比较。结果表明,采用塔釜液体闪蒸再沸式热泵精馏的节能效率最高,经济性最好。     

回收DMF的多效热泵精馏工艺研究

针对传统DMF回收工艺存在的高能耗问题,提出多效热泵精馏回收DMF工艺流程。在建立多效热泵精馏的能量平衡模型的基础上,利用ASPEN PLUS软件中的RADFRAC模块和UNIQUAC热力学计算模型,对该回收工艺进行模拟优化计算,确定各种工艺的最佳操作条件。在计算结果的基础上,对提出的各种工艺过程进行技术经济分析,以综合经济效益最佳为目标函数,确定了DMF回收的最佳多效热泵精馏工艺流程。     

高效节能的热泵技术

简要介绍了几种典型的热泵精馏和热泵干燥流程,并对其应用、特点及节能效果进行了讨论。     

MTO丙烯精馏塔能耗与经济性对比分析

MTO丙烯精馏塔的作用是将丙烯和丙烷进行分离,生产聚合级丙烯。该塔系具有如下特点:丙烯和丙烷的相对挥发度很小;塔顶和塔釜温差小;回流比高;塔板数多;塔顶冷凝器和塔釜再沸器的热负荷很大,能耗较高。为降低丙烯精馏塔能耗,可采用热泵精馏流程或常规精馏余热利用流程。采用Pro II9.0流程模拟软件,对丙烯精馏塔常规精馏流程与热泵精馏流程分别进行了模拟,比较分析两种流程的能耗和经济性。结果表明,常规精馏流程采用余热利用后节能91.31%,比热泵精馏流程低52.50%;操作费用节约87.06%,比热泵精馏流程低44.78%;两种流程在设备投资方面较接近。在选择流程时,应根据项目实际情况进行综合比较,并考虑整个装置的能量综合利用。当装置内部或周围副产大量低温热时,可考虑采用余热利用流程;当装置内部或周围无大量低温热时,可考虑采用热泵精馏流程。     

热泵技术在精馏中的应用

介绍间接式、塔顶气体直接压缩式、分割式、塔釜液体闪蒸再沸式、蒸汽喷射式和吸收式等几种典型的热泵精馏流程,分析了它们的特点、应用条件及节能效果,指出发展、应用热泵技术所必须注意的问题及一般原则.     

氨水吸收式热泵一种通用模拟方法研究

用联立方程法对单级氨水吸收式热泵的性能进行了模拟研究.联立方程组包括物性方程、各部件传热传质方程以及质量和能量守恒关系式.模拟结果表明,联立方程法具有收敛速度快、灵活性高的特点.还分析了发生温度、冷却温度和精馏温度对系统性能的影响,模拟结果与文献得到的结果相比,吻合很好.     

乙酸仲丁酯全流程模拟与能效分析

选取制备乙酸仲丁酯的全流程工艺作为研究对象,从系统层面研究热泵与反应分隔壁精馏塔集成构型在整厂过程设计与能量优化方面的影响与解决方案。利用反应精馏与共沸分离手段,构建稳态模型以获取高纯度目标产品;同时基于夹点分析方法对全流程进行能量分析,从系统综合角度出发指导换热网络的合成。研究结果可为乙酸仲丁酯全流程构建提供新的设计思路和节能方案。     

Performance optimization of a diabatic distillation-column by allocating a sequential heat-exchanger inventory

A diabatic distillation model is improved and the effects of the allocation of a heat-exchanger inventory on the diabatic-distillation performance are taken into account. Minimizing the entropy-production rate of the diabatic distillation column is taken as the optimization objective and the allocations of the heat-exchanger inventory on each tray in the diabatic distillation column are optimally redistributed under the condition of the fixed total heat-exchanger inventory. The optimal performance of the diabatic distillation column is obtained. The diabatic distillation model is meaningful for the design and optimization of diabatic distillation plant.     

甲醇汽油的馏程特性研究

低比例甲醇汽油的馏程特性试验研究结果表明:当甲醇含量不大于30%时,甲醇汽油的10%馏出温度普遍低于汽油;M5、M10甲醇汽油的50%馏出温度与汽油变化不大,M15、M20、M30甲醇汽油的50%馏出温度比90#汽油明显降低;甲醇汽油的90%馏出温度与90#汽油变化不大.甲醇含量不大于10%的甲醇汽油具有满意驾驶特性的馏程特性,含量不大于30%的甲醇汽油有较好的适用性.     

Using thermally coupled reactive distillation columns in biodiesel production

Production of methyl dodecanoate (biodiesel) using lauric acid and methanol with a solid acid catalyst of sulfated zirconia is studied by using two distillation sequences. In the first sequence, the methanol recovery column follows the reactive distillation column. In the second sequence, the reactive distillation and methanol recovery columns are thermally coupled. Thermally coupled distillation sequences may consume less energy by allowing interconnecting vapor and liquid streams between the two columns to eliminate reboiler or condenser or both. Here we study the thermally coupled side-stripper reactive distillation and eliminate the condenser of the reactive distillation column. Both the sequences are optimized by using the thermal and hydraulic analyses of the Column Targeting Tools of Aspen Plus simulator. Comparisons of the optimized sequences show that in the thermally coupled sequence, the energy consumption is reduced by 13.1% in the reactive distillation column and 50.0% in the methanol recovery column. The total exergy losses for the columns are reduced by 281.35 kW corresponding to 21.7% available energy saving in the thermally coupled sequence. In addition, the composition profiles indicate that the thermally coupled reactive distillation column operates with the lower concentration of water in the reaction zone which reduces catalytic deactivation.     

利用分子蒸馏技术再生废旧润滑油的应用

利用分子蒸馏技术再生废旧润滑油,是将废旧润滑油经过过滤,进入真空薄膜蒸馏脱除轻质组分汽柴油,剩余组分经分子蒸馏进行润滑油基础油的分离和重质杂质组分分离。分子蒸馏是远离沸点的分离,它优越于传统蒸馏利用沸点差来分离,它是在高真空技术发展基础上的一个创新技术。采用分子蒸馏技术再生废旧润滑油,润滑油基础油收率高。     

Modeling and optimization of a solar driven membrane distillation desalination system

The desalination technology using membrane distillation driven by solar energy is a feasible solution for reducing the energy cost. A dynamic simulation model for a solar driven membrane distillation desalination system (SMDDS) is developed on the Aspen Custom Modeler^® (ACM) platform for the system performance and optimization study. The rigorous model for the spiral-wound air gap membrane distillation (SP-AGMD) module takes into account the heat and mass transfer resistances associated with each composing layer. The effects of adopting different objective functions, solar radiation conditions, thermal storage tank configurations, as well as the flowrates of the membrane distillation module and the thermal storage tank on the optimized performance are reported. Simple thermal storage tank and lower flowrate of the membrane distillation module are advantageous to higher water production rate. A control system using conventional PI (Proportional/Integral) controllers is proposed and the water production rate can reach about 87% of the optimal result for clear sky operation.     

Performance analysis of solar ethanol distillation

Continuous solar ethanol distillation systems having flat-plate and evacuated heat pipe solar collectors are constructed to study their performances and economic viability. The mathematical model of each main component is carried out and the system simulation is developed. The simulated outputs express a reasonable agreement with the experimental results within 14% accuracy. From the simulation, start up with 10% alcohol concentration, the production cost of 80% alcohol concentration from the distillation system of which the yield at 12,500 l/year is evaluated. With the economic analysis, the results show that the use of solar distillation systems appear to be economical compared to the conventional distillation system using fuel oil as heat source. The minimum production cost of the system is 0.39 US$/l.     

Transient analysis of heat pump assisted distillation systems. 2 Column and system dynamics

A model to simulate the transient behaviour of a heat pump assisted distillation column is presented. The packed bed distillation column is treated as a distributed parameter system with time and space as independent parameters. The column modelling using appropriate basic equations, their application to binary systems, the solution scheme to the model equations and the distillation column simulation algorithm are described. The heat pump simulation algorithm is then coupled with this algorithm and the column transient behaviour with and without heat pump assist is obtained. The results are compared with earlier steady state data in the literature.     

Heat pump assisted distillation. II: Matching an external heat pump to a fractional distillation system

The problems in matching an external mechanical vapour compression heat pump to a distillation process in heat pump assisted distillation are discussed. There are four main design parameters to consider when selecting a working fluid for the heat pump, of which only two are independent. Various arrangements for imperfectly matched systems are presented, including the use of a two stage heat pump. A number of other factors which affect the choice of a heat pump assisted distillation system, including economic factors, are also considered.     

煤的太阳能干馏的可行性及干馏炉的设计探讨

论述了太阳能作为煤干馏的高温热源是可行的,通过传热分析综合评述,阐明了新型的太阳能干燥馏炉的优点及实际应用中需要解决的问题。     

Synthetic natural gas (SNG) liquefaction processes with hydrogen separation

The fact that synthetic natural gas (SNG) contains hydrogen has a great impact on its liquefaction process. Aiming to produce liquefied natural gas (LNG) from SNG, hydrogen separation from SNG through cryogenic processes is studied. A new separation method combining distillation and flash is developed, resulting in higher liquefaction rate than that of distillation under same operating parameters. Process simulations are performed by combining one liquefaction part (a nitrogen expansion process or a mixed refrigerant one) and one distillation part (direct flash, atmospheric distillation, pressurized distillation or the new separation method). Compared to direct flash, distillation can reduce the hydrogen content of products to a very low level, increasing the temperature of products by 8 °C and reducing the unit power consumption by 3%; and, compared to the other three separation ways, the new separation method reduces the unit power consumption by 7–10%. Both nitrogen expansion and SMR liquefaction processes can be integrated with hydrogen separation, but power consumptions for SMR processes are less than those for nitrogen expansion ones.