Distillation and Absorption McCabe Thiele Method

Click on image

Fuente: IngMisaelUPT

Simulación en Aspen Plus Partición de una Torre de Destilación Propano-Propileno

Simulación en Aspen PLUS sobre la partición de una Torre de Destilación para la separación de propano-propileno por destilación de alta presión [Figura 17.5 Henley & Seader 2000], recreada anteriormente en Hysys 7.2.

Ver también: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |

Columnas de Destilación Térmicamente Acopladas Petlyuk Método Corto para su Diseño

Clic en la imagen

Multi Effect Batch Distillation Pilot Plant at the University of Stellenbosch

Click on image

Multi Effect Batch Distillation (MEBAD) pilot plant constructed at the University of Stellenbosch to demonstrate the real world application of a neurocontrol methodology. This study formed part of a Ph.D. thesis "A neurocontrol paradigm for intelligent process control using evolutionary reinforcement learning, Alex van Eck Conradie, University of Stellenbosch (2004)"

Fuente: Alexconradie

Batch Reactors and Batch Distillation Dynamic Modelling by John E. Edwards

Batch processes are used extensively in the manufacture of relatively small volume products with relatively high value. These processes are frequently carried out in production facilities intended for multi-purpose use.

The achievement of stable and reproducible operating conditions is important in order to achieve the required product purity, yield and cycle times to satisfy the commercial requirements and relevant regulatory authorities.

Batch processes are inherently transient in nature and the capability to demonstrate dynamically the adequacy of the equipment design and performance provides a powerful design tool. Dynamic modelling can prevent costly mistakes prior to start up. Once a process model signature has been validated against real plant performance the dynamic model can be used as a diagnostic tool to identify operating problems.

This paper reviews the basic techniques for dynamic modelling the process and control of batch reactors and batch distillation systems using the Chemstations integrated range of software which is supported by an extensive component physical property database and thermodynamic options.

The power of this database is demonstrated below where the relative merits of the heat transfer fluids under consideration can be rapid ly presented without wasting design time.
These plots alert the designer to the benefits and disadvantages of the respective fluids which otherwise could be missed. For example note the difference in liquid specific heats between water and thermal fluids being a ratio factor varying from 2.8 to 1.8, quite significant...

Download article:

Batch Column Configurations for Extractive Distillation by Haydn I. Furlonge

Studies reported in the literature have shown that cyclic operation can be better than conventional operating policies. It was also demonstrated that the number of cycles, lengths of the total reflux periods and maximum reflux drum holdup are important decision variables which affect the performance of the operation. However, only simplified models have been used in simulation and optimisation. The use of more detailed models, which capture column dynamics more accurately, is required to verify the results obtained so far. Possible future research may also:

◘ optimise cyclic operation (involving more than one cycle per product cut) for the separation of multicomponent mixtures into multiple distillate cuts ;

◘ explore the effect of combining operating policies ;
◘ apply the cyclic policy to the middle vessel and multivessel column configurations;

Operating Policies Batch Distillation by Haydn I. Furlonge

The manner in which a column is operated, i. e. the choice of values for the operating decision variables ( e. g. reflux ratio), defines the operating policy. Conventional operating policies for batch distillation include constant reflux ratio, constant distillate composition and optimal reflux ratio operation. A less conventional policy is cyclic peration.
These policies are described below:

Constant reflux ratio

The reflux ratio is fixed at a pre-defined value which results in a variable distillate composition. The reflux ratio may also be varied in a piecewise-constant manner, whereby a different (constant) reflux ratio is used for each product cut.

Constant distillate composition
The distillate composition is held constant during the operation by varying the reflux ratio using a controller.

Optimal reflux ratio

The reflux ratio profile used is optimal with respect to a particular objective function ( e. g. profit) and set of constraints (e. g. product purity).

Cyclic operation
Comprises repetition of the following steps which make up one cycle (see Figure 1.2):

1. Flling-up

• low reflux to the column
• no distillate withdrawal
• holdup in the reflux drum increases to a pre-specified level

2. total reflux

• reflux flowrate is equal to the vapour flowrate through the condenser, so that the reflux drum holdup remains constant
• no distillate withdrawal

3. dumping

• low reflux to the column
• distillate is withdrawn
• reflux drum holdup decreases

The above operating policies apply primarily to a regular batch distillation column.

However, in principle, all column configurations may be operated under any one of these policies.It should be noted that it may be possible to combine two or more of these operating policies for a given separation. From an operational point of view, the simplest operating policy is the constant reflux ratio policy.

Apart from the reflux ratio, there are other operating decision variables such as the reboiler heat duty and condenser pressure. The choice of these depends on the properties of the mixture being separated as well as on economic considerations.