Methodology Development of a Flexible and Operable Energy Integrated Distillation Columns (original) (raw)

Methodology Development for Designing Energy Efficient Distillation Column Systems

Distillation is the primary separation process widely used in the industrial chemical processing. Although it has many advantages, the main drawback is its large energy requirement, which can significantly influence the overall plant profitability. However, the large energy requirement of these processes can be systematically reduced by using driving force and energy integration methods. This paper presents a methodology development for designing energy efficient distillation column systems based on those two methods. Accordingly, the proposed methodology consists of four hierarchical steps. In the first step, the systems of distillation column for multicomponent separation is designed based on the conventional distillation column design method. Then, the conventional distillation columns systems design is improved in terms of energy saving by using driving force method in the second step. It is expected in the third step that the distillation columns systems design can be further improved in terms of energy saving by using energy integration method. Finally, the distillation column systems design is evaluated in in terms of economic performance. By applying the proposed methodology, it is possible to make an early assumption on type of distillation column systems design that is the best in terms of energy saving and cost.

Sustainable Integrated Process Design and Control for an Extractive Distillation Column System

2014

The objective of this paper is to develop a sustainable integrated process design and control methodology for a distillation column system. The sustainable integrated process design and control problem for a distillation column system is typically formulated as a mathematical programming (optimization with constraints) problem, and solved by decomposing it to six sequential hierarchical sub-problems: (i) pre-analysis, (ii) design analysis, (iii) controller design analysis, (iv) sustainability analysis, (v) detailed economics analysis and (vi) final selection and verification. The results through case study of benzene-toluene separation process shows the proposed methodology is capable to find the optimal solution that satisfies design, control, sustainability and economic criteria in a simple and efficient way.

Comprehensive process investigation methodology for energy-integrated distillation

Computer Aided Chemical Engineering, 2007

A comprehensive process investigation/design methodology is presented that combines economic, control, and environmental features. The methodology is presented on the case study of energy integrated distillation columns separating ternary hydrocarbon mixtures of different ease of separations. The economic features involve capital and operating costs; the controllability investigations are based on the evaluation of frequency dependent features and dynamic simulations; the environmental evaluation counts for the CO 2 emissions. The results show that the heat integrated scheme is practically the best selection from every point of view.

The Design and Optimization of Distillation Column with Heat and Power Integrated Systems

Gas Processing Journal, 2013

Based on two integration steps, an optimization framework is proposed in this work for the synthesis and design of complex distillation sequence. The first step is to employ heat integration in sequence and reduce the heat consumption and total annual cost of the process. The second one is to increase the exergetic efficiency of sequence by generating power in implemented expanders in sequence. The profit of power generation directly affects the operating cost of the process and decreases the total annual cost. In each step, the target is to minimize the objective function of total annual cost. A simulator is used to simulate the equipment's specification and formulate the objective function of cost. Results from employing these two integration steps for the considered case study show the advantages of such a complex distillation sequence with heat integration and power generation. The results represent a very high improvement for the sequence Indirect since the properties of the intake flow to the process are in a way that in this sequence not only do we have a high freedom for carrying out heat integration, but a large amount of power is also produced between the columns due to having high flow rate flows between the columns.

Process control for energy integrated distillation schemes

Computers & Chemical Engineering, 1998

Two energy integrated distillation schemes for the separation of three different ternary mixtures of four typical feed compositions have been rigorously investigated and compared to the best conventional two-column distillation scheme. The two energy integrated schemes are: the heat integrated two column system and the fully thermally coupled distillation column (FTCDC), also known as Petlyuk column. The comparison of the

Control structure selection for energy integrated distillation column

Journal of Process Control, 1998

This paper treats a case study on control structure selection for an almost binary distillation column. The column is energy integrated with a heat pump in order to transfer heat from the condenser to the reboiler. This integrated plant configuration renders the possible control structures somewhat different from what is usual for binary distillation columns. Further the heat pump enables disturbances to propagate faster through the system. The plant has six possible actuators of which three must be used to stabilize the system. Hereby three actuators are left for product purity control. An MILP screening method based on a linear state space model is used to determine economically optimal sets of controlled and manipulated variables. The generated sets of inputs and outputs are analysed with frequency dependent relative gain array (RGA), relative disturbance gain (RDG) and condition number (CN) to determine the best structure in terms disturbance rejection and setpoint tracking. The pairing and controller design are implemented and evaluated through nonlinear simulation. The suggested control structure is also qualitatively compared to a control structure applied experimentally. ~£)

Modelling and control of heat-integrated distillation columns: An industrial case study

Heat integration is essential for reducing the energy consumption of process industries. However, it may render the dynamic operation more interactive and difficult to control. This paper compares the implications of heat integration in controllability and performance in energy reduction. The assessment, both on open loop and closed loop, was carried out based on an industrial case study and compared to a modified case without heat integration. Although the heat integrated system displayed a certain deterioration of controllability, the control system made possible an efficient operation. To this goal, different control systems were tested, from a decentralized control system to a model predictive controller. The type of controller used in the process barely influenced the performance of the process since the aim was exclusively to ensure the regulation of the process to fixed setpoints. As a final remark, large energy savings were obtained through heat integration design, thereby demonstrating the attractiveness of heat integration, and its appropriateness also in terms of dynamic performance.

Economic and controllability investigation and comparison of energy-integrated distillation schemes

Chemical and Biochemical Engineering Quarterly, 2003

Five different energy-integrated distillation schemes: two direct sequences with forward or backward heat integration (DQF, DQB), the Petlyuk or dividing wall system (SP), and two sloppy separation sequences with forward or backward heat integration (SQF, SQB) are investigated for the separation of a ternary mixture from economic and controllability points of view and compared to the non-integrated conventional direct separation scheme. The economic study shows that the optimal DQB has the highest total annual cost (TAC) saving: 37%. SQF and SQB have 34% and 33% TAC savings, respectively. The controllability analysis, based on steady state indices, shows that the control loops of DQF and DQB have less interactions than in the case of the other energy-integrated schemes studied. The dynamic investigations also prove that DQF and DQB show similar controllability features than the non-integrated conventional scheme. Although the SQF and SQB have good economic features but their control...

Retrofit design of an energy integrated distillation system

Periodica Polytechnica Chemical Engineering, 2007

This work presents the retrofit design of an industrial N, Ndimethylformamid (DMF)-water separation system originally consisting of three heat-integrated distillation columns. Our task was to examine how the capacity of the separation system could be increased by 42.8%. If necessary an unused onsite extra distillation column was available for the project. The performance of the existing distillation system and of various increased-capacity structures have been studied using rigorous process simulation. Our study shows that the required capacity increase can be attained by adding the extra distillation column only when replacing the column internals of the original columns and when installing a new structured packing also into the available extra column. Replacing the column internals is expected to result in better controllability, too.

Heat integrated process design for pressure swing distillation columns

2019

Reduction of overall operating energy required in a chemical plant at the designed production rate is a highly sought goal at present. Due to the higher operational costs of distillation units in a chemical plant, there is an urgency to design and demonstrate advance ‘greener’ and ‘innovative’ processes to ensure sustainability. The objective of reducing the energy consumption in distillation processes is being considered at the utmost priority. The present work highlights the efforts to design and implement separation process consisting of distillation columns using heat integration concept. Instead of relying on the other traditional or new methods of separation, we envision saving energy via implementing heat integrations in a pressure swing distillation process for separating Tetrahydrofuran-water azeotropic mixture through the presented case study. The significant feature of this work includes evaluation of the most important design variable that is, operating pressure for high...