首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
Biodiesel fuel has been shown as a clean energy alternative to petroleum diesel. Conventional biodiesel production involves the use of catalyst, which implies high energy consumptions for the separation of both the catalyst and the by-products of the reaction, including those of the undesirable reaction of saponification. Recently, a process involving the use of short-chain alcohols at supercritical conditions has been proposed (Saka-Dadan process); one of the main advantages of that process is that it avoids the need for a catalyst as well as the occurrence of the saponification reaction. However, although the process requires less pieces of equipment than the conventional one, its energy requirements are still high, making biodiesel fuel more expensive than petroleum diesel. This work proposes the use of reactive distillation and thermally coupled reactive distillation configurations to produce biodiesel fuel by the supercritical methanol method. First-order kinetics is used to represent the esterification reaction, obtaining high conversions in a single shell. Both of the configurations proposed reduce energy requirements when compared to the conventional (Saka-Dadan) process. Calculations were also performed to estimate CO2 emissions, thermodynamic efficiency and cost. The thermally coupled reactive distillation configuration shows to be the best alternative in terms of energy consumption, CO2 emissions and thermodynamic efficiency. Further, cost estimations also show that the use of a thermally coupled scheme considerably reduces both utilities and capital costs.  相似文献   

2.
Biodiesel fuel represents an interesting alternative as a clean and renewable substitute of fossil fuels. A typical biodiesel production process involves the use of a catalyst, which implies high energy consumptions for the separation of the catalyst and the by-products of the reaction, including those of undesirable side reactions (such as the saponification reaction). A recently proposed process involves the use of short-chain alcohols at supercritical conditions, avoiding the use of a catalyst and the occurrence of the saponification reaction. This process requires fewer pieces of equipment than the conventional one, but its high energy requirements and the need of special materials that support the reaction conditions makes the main product, biodiesel fuel, more expensive than petroleum diesel. In this work, a modification of the supercritical process for the production of biodiesel fuel is proposed. Two alternatives are proposed. The process involves the use of either reactive distillation or thermally coupled reactive distillation. Simulations have been carried out by using the Aspen One™ process simulator to demonstrate the feasibility of such alternatives to produce biodiesel with methanol at high pressure conditions. A design method for the thermally coupled system is also proposed. Both systems have been tested and the results indicate favorable energy performance when compared to the original scheme. Furthermore, the thermally coupled system shows lower energy consumptions than the reactive distillation column.  相似文献   

3.
磷钨酸铋催化合成油酸甲酯   总被引:1,自引:0,他引:1  
以磷钨酸铋为催化剂,对油酸和甲醇反应合成油酸甲酯进行了研究,考察了反应时间、催化剂用量、醇酸摩尔比、催化剂重复使用性等因素对油酸甲酯收率的影响.实验结果表明反应的最佳条件为:油酸用量为0.1 mol,醇酸摩尔比为1.4,催化剂磷钨酸铋用量为1.5 g,反应时间为4h,酯收率达93.4%,催化剂重复使用五次催化性能未见明...  相似文献   

4.
连续反应精馏合成乙酸异丙酯   总被引:6,自引:0,他引:6  
许前会  张秋荣 《辽宁化工》2003,32(12):510-511,514
以乙酸和异丙醇为原料通过连续反应精馏合成乙酸异丙酯,实验研究了影响反应的因素,结果表明最佳合成条件为:酸醇比1:1.2,回流比3,异丙醇的进料流量2mL/min,硫酸用量为乙酸体积的2%,乙酸异丙酯的最大收率为92.5%。  相似文献   

5.
    
A simulation study of n‐butyl acetate production with the [Hpy][HSO4] ionic liquid catalyst was performed. Due to the lack of phase equilibrium data, the binary interaction parameters of the NRTL model for ionic liquid and reactive species were calculated by the COSMO‐RS technique. A reactive distillation process with recycled ionic liquid stream was proposed, and the column configuration was optimized by minimization of the total annual capital. The novel process is considerably efficient and economic compared to the traditional reactive distillation process of nonionic liquids. With the steady‐state parameters, a plant‐wide control structure was further developed to evaluate the robustness of the control system by exerting the disturbances of feed flow rate and feed composition. Dynamic simulation results suggest that the control scheme with a composition controller is timely and effective.  相似文献   

6.
    
An integrated reactive distillation process for biodiesel production is proposed. The reactive separation process consists of two coupled reactive distillation columns (RDCs) considering the kinetically controlled reactions of esterification of the fatty acids (FFA) and the transesterification of glycerides with methanol, respectively. The conceptual design of the reactive distillation columns was performed through the construction of reactive residue curve maps in terms of elements. The design of the esterification reactive distillation column consisted of one reactive zone loaded with Amberlyst 15 catalyst and for the transesterification reactive column two reactive zones loaded with MgO were used. Intensive simulation of the integrated reactive process considering the complex kinetic expressions and the PC-SAFT EOS was performed using the computational environment of Aspen Plus. The final integrated RD process was able to handle more than 1% wt of fatty acid contents in the vegetable oil. However, results showed that the amount of fatty acids in the vegetable oil feed plays a key role on the performance (energy cost, catalyst load, methanol flow rate) of the integrated esterification–transesterification reactive distillation process.  相似文献   

7.
    
Acid functionalization of multi-walled carbon nanotubes (F-MWCNTs) using a mixture of HNO3 and H2SO4 (1:3, v:v) was used as support materials for the adsorption of Candida rugosa lipase (CRL) as nanoconjugates (CRL-MWCNTs) for producing methyl oleate. To evaluate the competency of the CRL-MWCNTs nanoconjugates, parameters viz. reaction time, surfactant as well as thermostability and reusability were investigated. The characterization of CRL-MWCNTs nanoconjugates using Fourier transform infrared spectroscopy, Field Scanning Electron Microscopy and Transmission Electron Microscopy revealed successful attachment of CRL onto the F-MWCNTs. Utilization of CRL-MWCNTs nanoconjugates resulted in a higher acid conversion in the synthesis of methyl oleate (79.85% at 11 h of reaction time) when compared with the free CRL i.e. an approximately 1.5-fold improvement over the free CRL. The highest percentage of esterification (83.62%) was observed following the use of nonionic surfactant when compared with the anionic and cationic ones. The CRL-MWCNTs nanoconjugates could be used up to 5 cycles, retaining 50% of its residual activity. Since the preparation of the CRL-MWCNTs nanoconjugates was facile and cheap while producing reasonable yield, the CRL-MWCNTs nanoconjugates developed here were found as promising biocatalysts for the production of methyl oleate.  相似文献   

8.
    
The higher feedstock and processing costs for biodiesel production can be reduced by applying reactive distillation (RD) in transesterification process. The effects of reboiler temperature, amount of KOH catalyst, methanol to oil molar ratio and residence time on the methyl ester purity were determined by using a simple laboratory-scale RD packed column. The results indicated that from the empty column, the system reached the steady state in 8 h. Too high reboiler temperature and the amount of catalyst introduce more soap from saponification in the process. The optimal operating condition is at a reboiler temperature 90 °C, a methanol to oil molar ratio of 4.5:1.0, KOH of 1 wt.% respect to oil and 5 min of residence time in the column. This condition requires the fresh feed methanol 25% lower than in the conventional process and produces 92.27% methyl ester purity. Therefore this RD column can be applied in small or medium biodiesel enterprise.  相似文献   

9.
We describe a hierarchy of methods, models, and calculation techniques that support the design of reactive distillation columns. The models require increasingly sophisticated data needs as the hierarchy is implemented. The approach is illustrated for the production of methyl acetate because of its commercial importance, and because of the availability of adequate published data for comparison. In the limit of reaction and phase equilibrium, we show (1) the existence of both a minimum and a maximum reflux, (2) there is a narrow range of reflux ratios that will produce high conversions and high purity methyl acetate, and (3) the existence of multiple steady states throughout the entire range of feasible reflux ratios. For finite rates of reaction, we find (4) that the desired product compositions are feasible over a wide range of reaction rates, up to and including reaction equilibrium, and (5) that multiple steady states do not occur over the range of realistic reflux ratios, but they are found at high reflux ratios outside the range of normal operation. Our calculations are in good agreement with experimental results reported by Bessling et al., [Chemical Engineering Technology 21 (1998) 393].  相似文献   

10.
本文通过实验测定了工业生产条件范围内,甲基丙烯酰胺(MAM)与甲醇(MeOH)水溶液在硫酸存在的条件下酯化反应生成甲基丙烯酸甲酯(MMA)的反应动力学数据。反应条件为:70-90℃,MAM:MeOH:H2O:H2SO4=1:2:3:1.7mol/molγ-丁内酯(γ-B.L)为均相剂。  相似文献   

11.
    
This paper designs an entrainer combined with a sidedraw to enhance the reactive distillation (RD) process of isopropyl acetate (IPAc). Acetic acid (HAc) reacts with isopropanol (IPOH) to generate IPAc and water (H2O). The ratio of IPAc to H2O in the products of esterification is smaller than that in the minimum boiling IPAc–IPOH–H2O azeotrope, resulting in a mass of organic phase reflux to remove the surplus H2O from the top of the RD column. This process consumes a high amount of energy. For better energy efficiency, a feasible design flowsheet includes an RD column, a stripper, a top decanter, a middle decanter, and a sidedraw stream to intensify the azeotropic separation where an entrainer is introduced to carry out the surplus water from the middle of the RD column in the form of a liquid phase. The key design variables in the proposed flowsheet are determined to obtain a minimal total annual cost (TAC). As a result, an optimal process design is drawn out while satisfying the stringent specifications for product purity. These results show that the energy requirements of the IPAc system can be decreased by 27.55%.  相似文献   

12.
Reactive distillation has been established for different processes, for example, the production of MTBE and TAME. Numerous publications have shown experimental and theoretical results of such etherification processes. The present paper deals with a theoretical background for an esterification process. The investigations will be carried out with the quaternary system consisting of n‐butanol, butyl acetate, acetic acid and water. For this system, not often used in literature, the chemical equilibrium constant and a suitable reaction kinetic has to be found. The different singular points will be checked and the kind of singularity will be determined. Residue curve maps will show the shape of simulations from different starting points. The differences between a simple distillation process and a reactive distillation process will be demonstrated.  相似文献   

13.
2-Methylpropylacetate synthesis via catalytic distillation   总被引:1,自引:0,他引:1  
The paper deals with a 2-methylpropylacetate synthesis process development. The process is based on esterification of acetic acid with 2-methylpropanol by the reactive distillation method. A column in which separation of the reaction products takes place together with esterification in catalytic active separation packing is utilized in this process. Computer simulation of catalytic distillation has been performed to study the process and to evaluate the pilot plant experimental data. KATAPAK® S structural packing was used in the reaction zone, while stripping and rectifying sections of the column were packed by CY® packing. A good agreement between the simulation results and pilot plant data has been achieved.  相似文献   

14.
工业硫酸催化酯化合成生物柴油性能的研究   总被引:1,自引:0,他引:1  
以各种植物油厂的下脚油、高脂肪酸厂的废弃产物和甲醇为原料,以工业硫酸为催化剂,催化合成生物柴油。考察了醇油体积比、催化剂用量、反应时间以及温度对酯化率的影响,确定了最佳反应条件:醇油体积比1∶1,催化剂用量0.6g,反应温度65~75℃,反应时间6h。在此条件下,酯化率达到95.5%。将产物进行常压蒸馏、水洗,得到柴油粗产品。再将柴油粗产品在-0.095~-0.085MPa真空度下减压蒸馏精制,收集170~210℃范围内的馏分。其精制所得产品酸值低,且收率高达90%以上。制得的生物柴油的基本性质如密度、黏度、闪点等基本符合美国现有的生物柴油标准,且与石化矿物柴油性质接近。  相似文献   

15.
反应精馏制苯甲酸苄酯的研究   总被引:2,自引:0,他引:2  
研究开发了由对苯二甲酸二甲酯生产过程中副产物粗苯甲酸甲酯酯交换制备苯甲酸苄酯的反应精馏工艺。在酯过量情况下,通过正交实验,确定了最佳工艺条件,并考察了催化剂用量、酯醇比和反应温度三因素对苄酯收率的影响。与间歇釜式反应相比,反应精馏技术用于苯甲酸甲酯醇解制苯甲酸苄酯大大提高了酯过量下的反应收率。  相似文献   

16.
Esterification of raw lactic acid from fermentation broth and then hydrolysis of lactate ester in reactive distillation column is an effective process for purification of lactic acid. Reactive distillation for hydrolysis of methyl lactate is studied. First, the thermodynamic properties and reaction kinetics are analyzed; then the reactive distillation column is designed based on the objective function total annual cost. The effects of tray number of rectifying section, tray number of reactive section, and feed location on the total annual cost are investigated. And a dual-temperature control structure is proposed for the optimal reactive distillation column, and the results show that it works quite well for this hydrolysis system.  相似文献   

17.
Comparative control study of ideal and methyl acetate reactive distillation   总被引:2,自引:0,他引:2  
The control of an ideal reactive distillation column is compared with that of a similar, but somewhat different, real chemical system, the production of methyl acetate. Similarities and differences are observed. Three control structures are evaluated for both systems. A control structure with one internal composition controller and one temperature controller provides effective control of both systems for both high and moderate conversion designs. A two-temperature control structure is effective when the system is overdesigned in terms of number of reactive trays, holdup and/or catalyst load. Direct control of product purity for the high-conversion/high-purity design is difficult because of system nonlinearity and interaction. Tray temperature control avoids the nonlinearity problem.  相似文献   

18.
High dependence on fossil fuel has caused increase of carbon dioxide concentration in the atmosphere. The actual political trends are towards an increased use of renewable fuels from agricultural origin. One of the main products of the European biorefineries is biodiesel. The main reaction involved in biodiesel synthesis produces a large amount of glycerol as by-product. Two aspects are arising in this respect: the glycerol obtained as residue and the food conversion to fuel. This paper deals with the revalorization of the residual glycerol stream to obtain triacetin (glyceryl triacetate), the lightest comestible oil. The application of glycerol as raw material to produce triacetin is not new. The goal of this paper is to check the feasibility of this transformation in an efficient integrated continuous process which is suitable for processing high quantities of glycerol. A kinetic model was determined experimentally for the production of triacetin from glycerol and acetic acid in the absence of catalyst. The results showed that by process integration of the reaction and distillation in the same unit (reactive distillation), a more sustainable process can be developed. The proposed configuration output is checked by rigorous simulation.  相似文献   

19.
徐丹  陈可娟 《当代化工》2015,(4):661-663,666
试验研究了以棕榈酸化油与甲醇为原料,在催化剂(浓硫酸)的作用下,通过酯化反应制备生物柴油。采用单因素试验和正交优化试验,考察反应温度、搅拌速率、醇油摩尔比和催化剂用量(与原料油质量比)对酯化反应收率的影响。确定最佳反应条件为反应温度为55℃,搅拌速率为200 r/min,醇油摩尔比为7:1,催化剂用量为2.0%,且在该条件下酯化效率为93.9%。  相似文献   

20.
Process intensification through reactive distillation (RD) could be successfully applied to the esterification of long-chain fatty acids, which is a crucial step in the biodiesel synthesis. While previous literature reports are mainly focused on the esterification of short- to medium- fatty acids, oleic acid has been chosen as an example of a long chain one and different RD configurations were simulated and compared. The configuration with top external recycle proved to be the best solution since it allows the reaction to be conducted under a large methanol excess, even though the column is fed with stoichiometric reactants.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号