共查询到20条相似文献,搜索用时 0 毫秒
1.
Moon Yong Lee Dae Woong Choi Young Han Kim 《Korean Journal of Chemical Engineering》2009,26(3):631-635
An approximate procedure for the estimation of operational variables in fully thermally coupled distillation columns (FTCDCs)
using two pseudo-pinch points of the feed and side draw trays is proposed, and its performance is examined with two example
processes. The estimates from the proposed procedure show some 20% error compared with the results of rigorous simulation
using commercial design software, the HYSYS. In addition, the relation between vapor flow rate and composition at one stage
above the feed tray-required in the estimation of operational variables of the FTCDC-is analyzed to give information for the
selection of the feed tray composition. A preliminary evaluation of operational variables helps to screen unrealizable design
obtained often from iterative trial procedures employing the mathematical programming. 相似文献
2.
Young Han Kim 《Korean Journal of Chemical Engineering》2000,17(5):570-573
A dynamic simulation of a fully thermally coupled distillation column is conducted for the design of a possible operation
scheme, and its performance is examined with an example process of butanol isomer ternary system. The outcome of the dynamic
simulation indicates that the column can be operated by using a 3 × 3 control structure. The structure consists of three controlled
variables of the compositions of overhead, bottom and side products and three manipulated variables of the flow rates of reflux
and steam and liquid split ratio between a main column and a prefractionator.
This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between
August 19 and 21, 1999. 相似文献
3.
An industrial scale hexane process is designed for the implementation of a fully thermally coupled distillation column (FTCDC).
A semi-rigorous material balance and Peng-Robinson equilibrium relation are utilized in the structural design. The operational
design is conducted with a commercial design program, the HYSYS. The design outcome of the structural design indicates it
to be comparable with the practical system of a conventional two-column arrangement in field operation, which shows the effectiveness
of the design procedure implemented here. The procedure is good for the system of many components found from actual field
applications. In addition, an investigation of the energy requirement of the FTCDC and a conventional system shows that an
energy saving of 34.1% is available with the FTCDC. 相似文献
4.
Aromatic compounds are yielded from naphtha reforming in a petrochemical plant, and the products are separated with binary
distillation columns for benzene, toluene, xylene and heavy components in sequence. In this study, the first three columns
of the fractionation process in the naphtha reforming unit are replaced with an extended fully thermally coupled distillation
column (EFTCDC) also known as the extended Petlyuk column. An industrial-sized application of the EFTCDC is examined to compare
the performance of the column with a conventional system. From a structural design giving the optimum structure of the column,
a practical column structure is derived and used in the HYSYS simulation to find the optimal operation condition for a given
set of product specifications. The EFTCDC gives an energy saving of 9.7% over a conventional three-column process. In addition,
it is proved that the design procedure is good for an industrial process of 18 components. 相似文献
5.
Moon Yong Lee Su Yeung Jeong Young Han Kim 《Korean Journal of Chemical Engineering》2008,25(6):1245-1251
A modified fully thermally coupled distillation column (FTCDC) for operability improvement is utilized in a gas concentration
process. The column consists of a prefractionator and two separated main columns having high distillation efficiency and flexible
control structure. The operability of the proposed column is evaluated by examining the open-loop dynamic responses of step
input variations with the HYSYS simulation. The simulation result indicates that the modified system can give better control
than the original FTCDC. The energy saving and reduction of construction cost are discussed, and the ease of vapor flow manipulation
and the elimination of a compressor in the vapor transfer are also evaluated as possible improvements. 相似文献
6.
Juan Gabriel Segovia-Hernández Adrián Bonilla-Petriciolet Luis Ignacio Salcedo-Estrada 《Korean Journal of Chemical Engineering》2006,23(5):689-698
The Petlyuk distillation system has been considered with special interest because of the high energy savings it can provide
with respect to the operation of sequences based on conventional columns. The original design of the Petlyuk structure, however,
shows two interconnections that seem to affect its operational and controllability properties. To overcome this problem, two
alternate structures have been suggested that use unidirectional flows of the vapor or liquid interconnecting streams. In
this work, a comparative analysis of the control properties of the Petlyuk column and the alternate arrangements with unidirectional
interconnecting flows is presented. Through a singular value decomposition analysis, it is shown that the alternate schemes
provide better theoretical controllability properties than the Petlyuk system. Closed loop tests using proportional-integral
controllers were also carried out, and the results showed that, in most of the cases considered, the alternate arrangements
improved the dynamic responses of the Petlyuk column. Such arrangements, therefore, show promising perspectives for its practical
consideration. 相似文献
7.
The thermally coupled distillation column systems can save energy and capital cost compared with traditional distillation columns. Since the thermally coupled column system was introduced, the design concerns have been peeped out due to more degrees of freedom. This paper introduces a new design method that can be used to determine the structure of thermally coupled distillation column systems, namely the number of stages in all sections of the column system. The design method employs the approximate group methods. To explore the design performance of the proposed design method, three feed systems are analyzed to investigate its usefulness. The design procedure gives the optimum structure for a given ternary separation; with given product specifications various design methods can yield approximately the same results. Like structure designs, the optimal internal flow distributions are examined. The results indicate that the method works well for a variety of process conditions. 相似文献
8.
Maryam Ghadrdan 《Chemical Engineering Research and Design》2011,89(8):1382-1391
The objective of this paper is to study the Kaibel distillation column from an operability point of view. Two different objectives, namely minimizing energy requirement at fixed product purities and maximizing product purities with a fixed boilup are considered. We have visualized the objective functions for the two cases as a function of operational degrees of freedom and conclude that operation with fixed product purities is the more difficult case from control point of view. 相似文献
9.
Valve trays are becoming popular in the chemical process industries owing to their flexibility to handle a wide range of vapor
throughputs. Using the rigorous rate based model, the importance of the non-equilibrium approach is demonstrated for a typical
extractive distillation process in a Glitsch V-1 valve tray column. Simulation results based on an in-house developed code
indicated that the rate based model predictions for a valve tray column operation showed significant differences relative
to the equilibrium model. Even small errors in product purities translated into nonoptimal feed stage locations and inaccurate
number of stages required. The counter-intuitive effect of high reflux ratio on separation is explained. 相似文献
10.
11.
Filipe Soares Pinto Roger Zemp Megan Jobson Robin Smith 《Chemical engineering science》2011,(13):2920
In this paper a methodology for thermodynamic analysis and distillation column ‘targeting’ is presented, with emphasis on the use of side condensers and side reboilers. Research in the past has been towards the establishment of a heat distribution curve, showing the way in which heat can be added or extracted across the different column sections. One major disadvantage of these profiles is that they refer to reversible columns, and cannot be used effectively to target for modifications in a real column.The main feature of the proposed methodology is the introduction of a minimum driving force, defined in terms of exergy loss distribution of the existing column, to set realisable targets for side reboiling/condensing in real columns, resulting in considerable energy savings. In addition to providing realisable targets, the new approach also provides the design engineer with information about the best location to place a side exchanger, and the required additional column modifications. The methodology can be applied using conventional column models in commercial process simulation programs, but can be significantly simplified by using reboiled and refluxed absorber models in a bespoke program. Simulation results for modified designs set by the new approach, for binary and multicomponent separations, verify the feasibility of the targets. This contrasts with previous approaches, which result in temperature shifts and heat load penalties after placing side reboilers/condensers, thus requiring additional simulation time and experienced judgement. 相似文献
12.
Jiangpeng Ma Mingyao Li Haisheng ChenKejin Huang Ningning WeiChunying Xia 《Chemical Engineering Research and Design》2013
The externally heat-integrated double distillation columns (EHIDDiC) is a newly proposed scheme featuring complete heat integration between the rectifying section of a high pressure distillation column (HPDC) and the stripping section of a low pressure distillation column (LPDC). In terms of its structural characteristics, three decentralized control systems are devised, which avoid using the pressure difference between the HPDC and LPDC as a manipulated variable and ease consequently the interaction between the control loops involved. While the first one attempts to control the composition of the blended top products of the HPDC and LPDC, the second one the composition of their blended bottom products, thereby simplifying the control structure from 4 × 4 to 3 × 3 system. The third one focuses on the simplified EHIDDiC with only three heat exchangers between the HPDC and LPDC (S-EHIDDiC) and their heat duties are employed as a combined manipulated variable. These control systems are evaluated in terms of the separation of a binary mixture of benzene and toluene and it is found that they outperform exclusively the conventional control system with the pressure difference as a manipulated variable. Both the top-mixed and bottom-mixed control systems appear to be superior to the one for the S-EHIDDiC and conventional double-effect distillation column, implying the advantages of the simplified design of decentralized control systems. The obtained results are considered to be of general significance and can be used to guide the design and operation of the EHIDDiC (S-EHIDDiC). 相似文献
13.
Ramona M. Dragomir 《Chemical engineering science》2005,60(16):4377-4395
It is well known that reactive distillation offers benefits by integrating distillation and reaction within a single unit. While there are procedures available for the synthesis of non-reactive distillation processes and of reaction-separation systems, the design of reactive distillation columns is still a challenge. This work presents a new synthesis and design methodology for hybrid reactive distillation columns, featuring both reactive and non-reactive sections; reactive equilibrium is assumed. The approach is based on graphical techniques; therefore it is restricted to systems with two degrees of freedom according to Gibbs phase rule. The design method allows rapid and relatively simple screening of different reactive distillation column configurations. The results are useful for initialising more rigorous calculations. The methodology is illustrated for MTBE and ethyl formate production. 相似文献
14.
Xingxing ZhangKejin Huang Haisheng ChenShaofeng Wang 《Computers & Chemical Engineering》2011,35(10):2017-2033
In terms of separation of a binary mixture of ethylene and ethane, three configurations of externally heat-integrated double distillation columns (EHIDDiCs), including a symmetrical EHIDDiC (S-EHIDDiC), an asymmetrical EHIDDiC (A-EHIDDiC), and a simplified asymmetrical EHIDDiC (SA-EHIDDiC), are compared with respect to aspects related to process design and controllability. It has been found that the A-EHIDDiC and SA-EHIDDiC are superior to the S-EHIDDiC in terms of thermodynamic efficiency as well as in terms of process dynamics and controllability. As for the comparison between the A-EHIDDiC and SA-EHIDDiC, the latter shows somewhat comparable behaviors with the former in terms of process design and controllability. These results demonstrate that the asymmetrical configuration should generally be favored over the symmetrical one for the development of the EHIDDiC. It is feasible to approximate external heat integration using three heat exchangers between the high- and low-pressure distillation columns involved. 相似文献
15.
Fernando Israel Gomez-Castro Vicente Rico-Ramirez Juan Gabriel Segovia-Hernandez Salvador Hernandez 《Chemical Engineering and Processing: Process Intensification》2010
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
16.
The fundamental dynamic behaviour of a middle-vessel continuous distillation column is studied in this paper. The interaction between the middle vessel (MV) design and control parameters is identified by means of a linear analysis. Transfer functions relating the dynamics of the product composition responses to changes in the disturbance inputs and manipulated inputs are derived. The role of the MV holdup and MV level controller gain in altering the product composition responses is identified. It is shown that the MV level controller gain can significantly affect the control performance when feed flow disturbances must be compensated for. However, it has a much lower impact in the control performance when feed composition disturbances need to be rejected; in this case, exploiting the “buffering” effect of the MV is more important for control. The analysis is carried out in detail for a LV control configuration, and is subsequently extended to an “on-demand” DB configuration. Finally, simple guidelines for the choice of the MV level controller gain and MV holdup are provided. 相似文献
17.
Kyu Suk Hwang Byoung Chul Kim Young Han Kim 《Korean Journal of Chemical Engineering》2010,27(4):1056-1062
A modified fully thermally coupled distillation column replacing the conventional distillation system is introduced, and its performance is experimentally evaluated for the stable operation of the column. The existing distillation system is modified to an energy-efficient distillation column for the reduction of investment cost and energy requirement. The experiment is conducted for the separation of methanol, ethanol and n-propanol mixture using a 4-in sieve tray column. The temperatures at seven different locations of the column are measured to monitor the column operation, and the measurements indicate that the column is stably operable. The stable operation proves that neither compressor nor pump is necessary for the vapor or liquid flow between tray sections. The experimental result is compared with that of the HYSYS simulation to show how satisfactory the separation is. The modeling of temperature variation provides a successful prediction of the temperature variation. 相似文献
18.
19.
Optimum design of Petlyuk and divided-wall distillation systems using a shortcut model 总被引:1,自引:0,他引:1
Nelly Ramírez-Corona Arturo Jiménez-Gutiérrez Angel Castro-Agüero Vicente Rico-Ramírez 《Chemical Engineering Research and Design》2010
An optimization approach for fully thermally coupled distillation systems for the separation of ternary mixtures is presented. The thermally coupled schemes considered here can be implemented in the form of the original Petlyuk arrangement (with an external prefractionator) or the modified Kaibel arrangement (in the form of a divided-wall column). The approach uses a shortcut design method that allows the system to be modeled as a nonlinear programming problem. Given the practical interest in divided-wall column arrangements, special attention is given in this work to this type of structure. Several cases of study are presented to show the applicability of the proposed approach. 相似文献
20.
José A. Caballero Ignacio E. Grossmann 《American Institute of Chemical Engineers》2013,59(4):1139-1159
The design of thermally coupled distillation sequences explicitly including the possibility of divided wall columns (DWC) is described. A DWC with a single wall can be considered thermodynamically equivalent to a fully thermally coupled (FTC) subsystem formed by three separation tasks (a Petlyuk configuration in the case of three‐component mixtures). It is shown how to systematically identify all the sequences of separation tasks that can produce configurations that include at least a DWC. Feasible sequences that explicitly include DWCs are enforced through a set of logical relationships in terms of Boolean variables. These logical relationships include as feasible alternatives from conventional columns (each column must have a condenser and a reboiler) to FTC systems (only one reboiler and one condenser in the entire system). A comprehensive disjunctive programming formulation for finding the optimal solution is presented. The model is based on the Fenske, Underwood Gilliland equations. However, the disjunctive formulation allows easily the use of any other shortcut, aggregated or even rigorous model without modifying much the structure of the model. Two illustrative examples illustrate the procedure. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1139–1159, 2013 相似文献