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Theoretical and Experimental Investigation of Biogas Production Reactor Performance

Ghofrani Isfahani, Parisa | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53408 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shahrokhi, Mohammad; Vossoughi, Manouchehr
  7. Abstract:
  8. Due to the high cost and destructive effects of fossil fuels, the biogas production as a renewable and environmentally friendly fuel attracted much attention. In this regard, several targets are considered in this research. First, in order to increase of biogas production yield and accelerating the rate limiting steps in anaerobic digestion of wheat straw (lignocellulosic feedstock), the effect of additives containing trace elements (Fe and Ni) in form of nanoparticles and their salts was investigated through batch experiments. The results showed that addition of nanoparticles or salts resulted in the increase of methane production rate during the first 4 days of experiments. Then, a suitable and comprehensive model was selected to describe the dynamic behavior of an anaerobic digestion process and afterwards a proper controller was proposed to control the operating conditions. The performance of proposed control strategy was studied via simulation. The process outputs are methane production rate and total volatile fatty acids concentration and the manipulated variable is the feed flowrate. Control system is preferential type (override). If the total volatile fatty acids concentration exceeds from a predetermined level, in order to keep the system stable the total volatile fatty acids concentration will be controlled instead of methane flowrate. Simulation results confirmed the successful performance of the proposed controller. In the next step, an anaerobic bioreactor was designed, constructed and a supervisory controller was proposed to enhance biogas production and control the process experimentally. The performance of controller was investigated in the presence of external severe disturbances. The proposed controller receives the total volatile fatty acids concentration and the methane production trend to calculate the set-point of the inner control loop. The supervisory controller could successfully improve the methane production rate and keep the reactor stable against external severe disturbances.

  9. Keywords:
  10. Anaerobic Digestion ; Controller Design ; Nanoparticles ; Biogas Production ; Methane Production ; Volatile Fatty Acids Concentration ; Biofuel

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