T. Takamatsu

Internally Heat-Integrated Distillation Columns: A Review

The heat-integrated distillation column to be addressed in this paper is a special distillation column that involves internal heat integration between the whole rectifying and the whole stripping sections. An overview of the research on this process is presented in this work. It covers from the thermodynamic development and evaluations to the practical design and operation investigations for the process. Comparative studies against conventional distillation columns are introduced and the results obtained show distinctively the substantial advantages in energy efficiency of the process over its conventional counterparts. Some relevant issues of process design and operation are to be stressed and the results of the first of its kind bench-scale plant experimentation are given in great detail. The application of internal heat integration principle to other distillation-related processes is also discussed in depth. These include heat integration within batch distillation columns, pressure-swing distillation columns that are used for the separation of pressure-sensitive binary azeotropes, and different distillation columns that have no connections at all. The prospects of the HIDiC and our future research work are then highlighted.

Operation of a bench-scale ideal heat integrated distillation column (HIDiC): an experimental study

Abstract Experimental study of an ideal heat integrated distillation column (HIDiC) is introduced in this work. It is found that the ideal HIDiC can be operated very smoothly, with no special difficulties compared with its conventional counterparts. The higher energy efficiency of the ideal HIDiC is confirmed by the bench-scale experiments. Reflux-free and/or reboil-free operations of the ideal HIDiC are also demonstrated to be feasible by the experiments.

Parameter analysis and optimization of ideal heat integrated distillation columns

Abstract Parametric analysis is performed for ideal heat integrated distillation columns (HIDiC) and comparative studies are made with conventional distillation columns. Implications of process design and operation variables are clarified and heuristics are provided for the effective process design. A generalized process configuration is suggested, which is demonstrated to have both higher energy efficiency and higher flexibilities than its original configuration. Simulation studies are conducted and the obtained results confirm the conclusion.

Operating an ideal heat integrated distillation column with different control algorithms

The operation of an ideal heat integrated distillation column is addressed. Five control strategies, namely, single loop composition control system, multi-loop composition control system, multivariable internal model control (IMC) system, modified multivariable IMC control (MIMC) system and nonlinear process model based control (NPMC) system, are design and applied to the process. Simulation results demonstrate that all the control systems are capable of keeping both end products on their specifications. The NPMC is the best one in the operation of the ideal HIDiC. It can very smoothly realize setpoint transition and efficiently counteract external disturbances. The MIMC ranks the second for the regulatory responses to feed composition disturbances have relative longer setting time. The next comes to the multi-loop composition control system. Although it works well for the operation of the ideal HIDiC, it produces relative larger oscillations and longer setting time in the system responses. The IMC can not compete with the multi-loop composition control system because it is extremely sensitive to operating condition changes. The single-loop composition control system is the worst one for the responses of the uncontrolled product is extremely sluggish.

Simulation oriented development of a new heat integrated distillation column and its characteristics for energy saving

Abstract So far, Process Systems Engineering (PSE) has contributed to the creation and improvement of new chemical production systems, by effective and rational combination of existing elementary production units and related information treatment parts, from both design and operational view points. However, it should not be forgotten that the structure of production units or information treatment parts are already fixed and given in many cases, when such methodologies are going to be applied to practical production systems. In this paper, we show that such production units or information treatment parts themselves should be newly created and synthesized from the viewpoint of the production system as the total, in order to create more rational production systems in the coming century. Next, the development of a new heat integrated distillation column, based on the above general concept, is reported and its characteristics of energy saving are discussed from a thermodynamic viewpoint. t;**

A New Configuration of Ideal Heat Integrated Distillation Columns (HIDiC)

Abstract A new configuration for ideal heat integrated distillation columns (HIDiC) is proposed by further heat integration between its overhead product and feed. This modification makes the ideal HIDiC more self-support and imposes fewer constraints to the environment. The added heat integration is different in nature from the one between the rectifying and the stripping sections. The latter is self-regulating, while the former is not. Open-loop integrating process is produced by the added heat integration, which makes the process more difficult to control than before. It is therefore extremely important to explore the interaction and tradeoff between process design and operation. Simulation studies are conducted to evaluate the process operation feasibility and it is found that the process can be well controlled through manipulations of pressure difference between the rectifying and the stripping sections and feed thermal condition.

Potential energy savings in ideal heat-integrated distillation column

An ideal Heat-Integrated Distillation Column (HIDiC), having no reboiler and no condenser, is constructed in such a manner that its rectifying and stripping sections are separated, while connected through a compressor and a throttling valve. Its manipulation is completed by exchanging heat between the two sections. The ideal HIDiC is expected to be more efficient than conventional columns, at the expense of some energy to raise the pressure of the rectifying section. In this paper, it is shown by thermodynamical consideration that the ideal HIDiC has a high potential of texergy loss reduction in the operation compared with conventional columns. The effects of feed and distillate composition, and relative volatility on energy saving characteristics are simulated in this paper, and the possibility of energy saving is found for feed compositions.

Evaluating control structures for a general heat integrated distillation column (general HIDiC)

Abstract The assessment of control configurations for a general HIDiC (an ideal heat integrated distillation column incorporated with a overhead condenser and bottom reboiler structure) is addressed in this work. It is found that the double ratio control configuration, (L/D, V/B) is still the best one among all the possibilities. Moreover, the pressure difference between the rectifying and the stripping sections and the feed thermal condition are expected to be consistent manipulative variables for the control of the general HIDiC. The control configuration, (pr-ps, q), appears to be a feasible one for the process operation. The performances of the general HIDiC can be substantially improved by employing efficient multivarible control algorithms.

A case study of HIDiC design and energy saving

Abstract The ideal Heat Integrated Distillation Column (HIDiC) has been studied by computer simulation and examination. Its concrete structure has been designed as for an example with the simulator for its operation and design. The performance of mass and heat transfer presumed on the simulation have been examined by test units. As a result, it is found that the ideal HIDiC appears to be practical applications, and it might save energy 30% more than conventional distillation columns.

Contributing to Reduction of CO2 Emissions Through Development of a Heat-Integrated Distillation Column

Publisher Summary This chapter introduces the development of a heat-integrated distillation column as a means of contributing to the reduction of CO2 emissions. The imperatives of global warming and sustainable development demand efficient energy utilization in all aspects of life. The chemical processing industry, as an intensive energy consumer, is a major contributor to CO2 emissions. It accounts for 25% of the energy consumed by industries overall, while the distillation process accounts for up to 50% of the energy consumed by this industry. To abate its impacts and achieve the targets designated by the Kyoto Protocol, the development of energy-efficient distillation processes has, potentially, a very important role. An energy-efficient heat-integrated distillation column (HIDiC) is developed in this work as a way to alleviate CO2 emissions. The process has evolved from the application of the heat-pump principle to a distillation process, leading to an internal heat integration between the whole rectifying and the whole stripping sections. Three candidate configurations have been proposed and analyzed for the practical process realization. The results from the operation of the first bench-scale plant and simulation studies demonstrate its substantial contribution to the reduction of CO2 emissions.