On-off and PI Control of Methane Gas Production of a Pilot Anaerobic Digestion Reactor

Haugen, Finn; Bakke, Rune; Lie, Bernt

doi:10.4173/mic.2013.3.4

Cited by 5 publications

(8 citation statements)

References 26 publications

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“…In principle, reac is also a candidate as control variable since it has a clear impact on meth , but in [28] we argue why reac is not considered a usable control variable.…”

Section: Ad Reactor With Control Systemmentioning

confidence: 89%

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State Estimation and Model-Based Control of a Pilot Anaerobic Digestion Reactor

Haugen

Bakke

Lie

2014

Journal of Control Science and Engineering

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A state estimator and various model-based control systems have been designed for a real anaerobic digestion (AD) pilot reactor fed with dairy manure. The model used is a modified Hill model which is a relatively simple dynamical AD process model. The state estimator is an Unscented Kalman Filter (UKF) which uses only methane gas flow measurement to update its states. The model and the state estimates are used in different control systems. One of the control systems aims at controlling the methane gas flow to a setpoint. Simulations indicate that the setpoint tracking performance of a predictive control system is considerably better comparing with PI control, while disturbance compensation is not much better. Consequently, assuming the setpoint is constant, the PI controller competes well with the predictive controller. A successful application of predictive control of the real reactor is presented. Also, three different control systems aiming at retaining the reactor at an operating point where the volatile fatty acids (VFA) concentration has a maximum, safe value are designed. A simulation study indicates that the best control solution among the three alternatives is PI control based on feedback from estimated VFA.

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“…In principle, reac is also a candidate as control variable since it has a clear impact on meth , but in [28] we argue why reac is not considered a usable control variable.…”

Section: Ad Reactor With Control Systemmentioning

confidence: 89%

“…If oscillations can be tolerated, even the on-off controller should be considered. Using on-off controllers and PI controllers for meth control of the pilot reactor is discussed in detail in [28].…”

Section: Operational Objective and Control Strategymentioning

confidence: 99%

State Estimation and Model-Based Control of a Pilot Anaerobic Digestion Reactor

Haugen

Bakke

Lie

2014

Journal of Control Science and Engineering

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“…According to the discussion in Haugen et al (2013b) based on the results in Hill et al (1987), the range of S vfa for safe reactor operation is…”

Section: Optimization Variables and Their Constraintsmentioning

confidence: 96%

“…U ¼ 6:50 Á 10 4 ((J/d)/K)/m 2 is specific thermal conductivity of the reactor, assumed equal to that of the pilot reactor. In Haugen et al (2013b), U is denoted G s . V [m 3 ] is effective volume of reactor liquid.…”

Section: A4 Power Calculationsmentioning

confidence: 99%

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Optimal design and operation of a UASB reactor for dairy cattle manure

Haugen

Bakke

Lie

et al. 2015

Computers and Electronics in Agriculture

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a b s t r a c tOptimal design and operation of a planned full-scale UASB reactor at a dairy farm are determined using optimization algorithms based on steady state simulations of a dynamic AD process model combined with models of the reactor temperature and heat exchanger temperatures based on energy balances. Available feedstock is 6 m 3 /d dairy manure produced by the herd. Three alternative optimization problems are solved: Maximization of produced methane gas flow, minimization of reactor volume, and maximization of power surplus. Constraints of the optimization problems are an upper limit of the VFA concentration, and an upper limit of the feed rate corresponding to a normal animal waste production at the farm. The most proper optimization problem appears to be minimization of the reactor volume, assuming that the feed rate is fixed at its upper limit and that the VFA concentration is at its upper limit. The optimal result is a power surplus of 49.8 MWh/y, a hydraulic retention time of 6.1 d, and a reactor temperature of 35.9°C, assuming heat recovery with an heat exchanger, and perfect reactor heat transfer insulation. In general, the optimal solutions are improved if the ratio of the solids (biomass) retention time to the hydraulic retention time is increased.

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