Comparison of PID and MPC controllers for continuous stirred tank reactor (CSTR) concentration control

Continuous Stirred Tank Reactor (CSTR) is amajorarea in process, chemical and control engineering. In this paper, PID and MPC controllers are designed for CSTR in order to analyze the output concentration of the system by comparing the two proposed systems using Matlab/Simulink. Comparison have been made using two desired concentration input (Random reference and step) signals with and without input side disturbance (Flow rate error). The simulation result shows that the continuous stirred tank reactor with MPC controller have better response in minimizing the overshoot and tracking the desired concentration for the system without input disturbance and with the effect of the disturbance makes the continuous stirred tank reactor with MPC controller output with small fluctuations and still better than the continuous stirred tank reactor with PID controller. Finally the comparative analysis and simulation results prove the effectiveness of the continuous stirred tank reactor with MPC controller

Design strategy and process optimization for reactors with continuous transport of an immobilized enzyme

In order to operate a process which uses immobilized enzymes at constant conversion and constant capacity, the refreshment of the enzyme must be continuous. In this paper, two reactor types with continuous refreshment of the biocatalyst are discussed: the stirred tank and the multistage fluidized bed. A method is presented for dimensioning a reactor in such a way that the costs for the conversion of substrate to product are minimized. These costs are calculated as the sum of the biocatalyst consumption and overall reactor costs.\ud \ud In contrast with the stirred-tank reactor, the multistage fluidized bed can be operated at a non-uniform temperature. For the glucose isomerase process, an optimal temperature gradient results in a small reduction in the biocatalyst consumption (±5%). It is concluded that, in general, a temperature gradient will only favour the economy of processes with relatively expensive biocatalysts.\ud \ud Compared with conventional reactor types, such as the continuous stirred-tank reactor and the fixed-bed reactor, the multistage fluidized-bed reactor can improve the economy of an enzyme-catalysed reaction significantly

Pemodelan Dinamik dan Pengendalian Proses Stirred Tank Heater Menggunakan Sistem Dinamik

Stirred tank heater digunakan dalam proses kimia untuk memanaskan fluida hingga mencapai suhu yang diinginkan. Prinsip pemanasan pada stirred tank heater adalah dengan mengalirkan fluida pemanas dalam koil atau jaket pemanas. Suhu fluida proses dijaga dengan mengendalikan laju alir fluida pemanas. Pengendalian suhu stirred tank heater dengan algoritma PID (proportional-integral-derivatif) dilakukan menggunakan model dinamik proses yang diturunkan dari persamaan neraca massa dan energi. Pemodelan dinamik dan pengendaliannya menggunakan metode sistem dinamik dengan bantuan perangkat lunak ithinkTM. Hasil simulasinya menunjukkan bahwa pengendali yang dipasang dapat menangani Perubahan setpoint dan gangguan hingga ±15% secara baik

Production of xylanolytic enzymes by Aspergillus terricola in stirred tank and airlift tower loop bioreactors

Fungi producing high xylanase levels have attracted considerable attention because of their potential industrial applications. Batch cultivations of Aspergillus terricola fungus were evaluated in stirred tank and airlift bioreactors, by using wheat bran particles suspended in the cultivation medium as substrate for xylanase and b-xylosidase production. In the stirred tank bioreactor, in physical conditions of 30°C, 300 rpm, and aeration of 1 vvm (1 l/min), with direct inoculation of fungal spores, 7,475 U/l xylanase was obtained after 36 h of operation, remaining constant after 24 h. In the absence of air injection in the stirred tank reactor, limited xylanase production was observed (final concentration 740 U/l). When the fermentation process was realized in the airlift bioreactor, xylanase production was higher than that observed in the stirred tank bioreactor, being 9,265 U/l at 0.07 vvm (0.4 l/min) and 12,845 U/l at 0.17 vvm (1 l/min) aeration rate.Fundação para a Ciência e a Tecnologia (FCT)CNPq (Brasil)FAPESP (Brasil

Design and Scale-Up of Production Scale Stirred Tank Fermentors

In the bio/pharmaceutical industry, fermentation is extremely important in pharmaceutical development, and in microbial research. However, new fermentor designs are needed to improve production and reduce costs of complex systems such as cultivation of mammalian cells and genetically engineered micro-organisms. Traditionally, stirred tank design is driven by the oxygen transfer capability needed to achieve cell growth. However, design methodologies available for stirred tank fermentors are insufficient and many times contain errors. The aim of this research is to improve the design of production scale stirred tank fermentors through the development of dimensionless correlations and by providing information on aspects of fermentor tanks that can aid in oxygen mass transfer. This was accomplished through four key areas. Empirical studies were used to quantify the mass transfer capabilities of several different reactors. Computational fluid dynamics (CFD) was used to assess the impact of certain baffle and impeller geometries. Correction schemes were developed and applied to the experimental data. Dimensionless correlations were created from corrected experimental data to act as a guide for future production scale fermentor design. The methods for correcting experimental data developed in this research have proven to be accurate and useful. Furthermore, the correlations found from the corrected experimental data in this study are of great benefit in the design of production scale stirred tank fermentors. However, when designing a stirred tank fermentor of a different size, further experimentation should be performed to refine the correlations presented

Monoclonal Antibody Production Via Fluidized Bioreactor Technology

Monoclonal antibodies (mAbs) are biologically identical antibodies created by homogenous immune cells originating from the same parent cell. MAbs target a specific epitope of an antigen on a cell’s surface, allowing it to neutralize the antigen. This unique characteristic has made them a key tool in the biopharmaceutical industry for the production of therapeutic drugs. One of these drugs is Rituxan® (rituximab), a mAb drug for the treatment of various cancers and autoimmune diseases. Currently, most mAb products are grown via cell suspension technology in stirred tank bioreactors. However, we have found that by using an integrated bioprocessing model, including conventional cell suspension culture tanks and fluidized bioreactor technology, overall product yield per day is increased by about 7-fold for the production of Rituxan®. Additionally, an economic analysis shows the fluidized bioreactor process is more profitable. Furthermore, though it requires a higher initial investment than the stirred tank process, the differential present worth of the fluidized bioreactor process in comparison to the stirred tank process is $13 billion. Overall, for the production of Rituxan®, the use of fluidized bioreactor technology is a more productive and lucrative process than the conventional stirred tank process

Effect of the wavy tank wall on the characteristics of mechanical agitation in the presence of a Al2O3-water nanofluid

The enhancement of the heat transfer in the stirred tank is a much-desired objective for accelerating certain physical and chemical parameters in the industrial field. From this basis, an attempt is made in this paper to investigate the effect of the wavy wall of a stirred tank on the hydrodynamic, thermal, and energetic behavior of an Al2O3-Water nanofluid. The stirred tank has a flat bottom, and it is equipped with an anchor stirrer. A hot temperature has been imposed on the tank wall, and the agitator has been assumed adiabatic, where the nanofluid has a cold temperature at the initial instant. The laminar flow was governed by the equations that describe the forced convection, and it was solved by the finite element method. The numerical simulation results showed a considerable acceleration in the heat transfer inside the stirred tank by increasing the amplitude of the wavy wall and increasing the nanoparticle concentration. However, there has been a remarkable increase in the stirring power number. This contribution aims to increase thermal efficiency, especially in the chemical and petrochemical fields, to obtain a better yield of certain chemical reactions and mass transfer depending on the heat

Continuous reactive crystallization of pharmaceuticals using impinging jet mixers

For reactive crystallization of pharmaceuticals that show a rapid reaction rate, low solubility of active pharmaceutical ingredient and hence a large supersaturation, it was found in a recent study that a process design which integrates an impinging jet mixer and batch stirred tank produces high quality crystals. The current investigation examines if the short processing time of reactive crystallization permits the impinging jet mixer—stirred tank design to be modified to operate in a continuous mode. The new design combines an impinging jet mixer for feed introduction and reaction with a continuous stirred tank reactor (CSTR) and tubular reactor for crystal growth. A study of reactive crystallization of sodium cefuroxime (an antibiotic), using first a 1L CSTR then scaling to a 50L CSTR, found that the new design produces crystals of higher crystallinity, narrower particle size, and improved product stability, than batch crystallizers

Protein refolding in an oscillatory flow reactor

We demonstrate that an oscillatory flow reactor is a viable reactor for protein refolding via direct dilution. The mixing characteristics of the oscillatory flow reactor are well described and controllable and, importantly, can be scaled-up to process scale without a loss of mixing efficiency. This makes the oscillatory flow reactor an attractive alternative to conventional stirred-tank reactors for process-scale renaturation