scholarly journals A TITO Control Strategy to Increase Productivity in Uncertain Exothermic Continuous Chemical Reactors

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 873
Author(s):  
Ricardo Aguilar-López ◽  
Juan Luis Mata-Machuca ◽  
Valeria Godinez-Cantillo
Keyword(s):  
Control Strategy ◽  
Chemical Reactor ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Optimal Controller ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank ◽  
Continuous Chemical

In this manuscript, a two-input two-output (TITO) control strategy for an exothermic continuous chemical reactor is presented. The control tasks of the continuous chemical reactor are related to temperature regulation by a standard proportional-integral (PI) controller. The selected set point increases reactor productivity due to the temperature effect and prevents potential thermal runaway, and the temperature increases until it reaches isothermal operating conditions. Then, an optimal controller is activated to increase the mass reactor productivity. The optimal control strategy is based on a Euler-Lagrange framework, in which the corresponding Lagrangian is based on the model equations of the reactor, and the optimal controller is coupled with an uncertainty estimator to infer the unknown terms required by the proposed controller. As a benchmark, a continuous stirred tank reactor (CSTR) with a Van de Vusse chemical reaction is considered as an application case study. Notably, the proposed methodology is generally applicable to any continuous stirred tank reactor. The results of numerical experiments verify the satisfactory performance of the proposed control strategy.

scholarly journals Effect of nitrogen loading rate and alkalinity on partial nitritation in a continuous stirred tank reactor

2021 ◽  
Vol 27 (1) ◽  
pp. 200573-0
Author(s):  
Daehee Choi ◽  
Thanh Phuong To ◽  
Wonsang Yun ◽  
Dongjin Ju ◽  
Keugtae Kim ◽  
...  
Keyword(s):  
Loading Rate ◽  
Nitrogen Loading ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Ammonium Oxidation ◽  
Continuous Stirred Tank Reactor ◽  
Partial Nitritation ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank

In order to achieve an appropriate effluent ratio of ammonium and nitrite as an influent of the anaerobic ammonium oxidation process, the optimum conditions for the partial nitritation in a continuous stirred tank reactor (CSTR) were investigated using real reject water. Hydraulic retention time (HRT) and influent alkalinity (HCO3-)/NH4+-N ratio were major factors that greatly influenced the partial nitritation. As a result of continuous operation, ammonium conversion efficiency (ACE) and effluent nitrite to ammonium ratio (NAR) could be achieved at the HRT of 19 h corresponding to 0.71 kg/m3/d of nitrogen loading rate (NLR). Thereafter, the influent HCO3-/NH4+-N ratio was adjusted from 0.5 to 2, and as a result, the optimum partial nitritation efficiency was maintained when the influent HCO3-/NH4+-N ratio was one. The suitability of the determined operating conditions was verified in a CSTR over 30 d of operation time.

scholarly journals Investigation and Modeling of Gas-Liquid Mass Transfer in a Sparged and Non-Sparged Continuous Stirred Tank Reactor with Potential Application in Syngas Fermentation

Fermentation ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 75 ◽  
Author(s):  
Kan Liu ◽  
John R. Phillips ◽  
Xiao Sun ◽  
Sayeed Mohammad ◽  
Raymond L. Huhnke ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Syngas Fermentation ◽  
Mass Transfer Limitation ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Working Volume ◽  
Continuous Stirred Tank

Syngas (mixture of CO, H2 and CO2) fermentation suffers from mass transfer limitation due to low solubility of CO and H2 in the liquid medium. Therefore, it is critical to characterize the mass transfer in syngas fermentation reactors to guide in delivery of syngas to the microorganisms. The objective of this study is to measure and predict the overall volumetric mass transfer coefficient, kLa for O2 at various operating conditions in a 7-L sparged and non-sparged continuous stirred-tank reactor (CSTR). Measurements indicated that the kLa for O2 increased with an increase in air flow rate and agitation speed. However, kLa for O2 decreased with the increase in the headspace pressure. The highest kLa for O2 with air sparged in the CSTR was 116 h−1 at 600 sccm, 900 rpm, 101 kPa, and 3 L working volume. Backmixing of the headspace N2 in the sparged CSTR reduced the observed kLa. The mass transfer model predicted the kLa for O2 within 10% of the experimental values. The model was extended to predict the kLa for syngas components CO, CO2 and H2, which will guide in selecting operating conditions that minimize power input to the bioreactor and maximize the syngas conversion efficiency.

scholarly journals Gain Scheduled Multivariable Control of a Continuous Stirred Tank Reactor

2019 ◽  
Vol 9 (1S3) ◽  
pp. 95-100
Keyword(s):  
Mimo Systems ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Single Input Single Output ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Highly Nonlinear ◽  
Decentralized Controllers ◽  
Continuous Stirred Tank

Most chemical reactors, representing Multi-Input Multi-Output (MIMO) systems, are highly nonlinear and require complex control than single-input single-output (SISO) systems. In the present work, the system is linearized around different operating points. As linear design strategies are intended to work in linear regions, they are employed to evaluate local controller parameters. Decentralized controllers using constant detuning factor and decoupling controllers using static decouplers are designed. A gain scheduler is developed to deal with changes in operating conditions. The performances are evaluated by simulating the nonlinear equations of the system. Decentralized controllers cannot mitigate the interactions due to its structure possessing single loop. It is exhibited that the decoupling controllers offer better control for tracking of desired set point and rejection of load disturbances than those of decentralized controllers. The superiority of the suggested controller has been portrayed by performing simulation study on a Continuous Stirred Tank Reactor (CSTR).

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