Optimization of design and operation of anaerobic digestion reactors

Abstract

The sustainable provision of bio-methane plays a key role in the future energy supply and is a promising environmentally friendly solution for waste processing. With rising number and size of biogas power plants process optimization is a vital task. Consequently, in this thesis a 6000 [L/d] swine waste feed into anaerobic digestion reactor will be degraded into biogas, which thesis aim is to optimize process with numerical models and programming skills to run multiple input variables in order to solve optimization problem. Objective functions for optimization are economic revenue and net present value of process with optimization variables of reactor volume and temperature. Mathematical model for process is (Hill, 1983) method, which is a dynamic simulation model for anaerobic fermentation of biodegradable material. Also more mathematical model for temperature and volume has been made with physical rules such as energy balance and mass transfer. Economic analyses starts with cost estimation for equipment based on pilot reactor and market prices, and then time value of money has been included in calculation. The results contain measurement of payback ability for anaerobic digestion process in various financial criteria (such as internal rate of return); furthermore thesis results indicates an applicability of numerical algorithms in economic optimization performance in anaerobic digestion process where outcome of thesis could be a measurement standard for profitability of different process designs. Finally it is concluded that estimations for process equipment are playing a vital rule in economic performance; therefore cost estimation must be based on more precise data sources. General revenue and internal rate of return shows clear financial feasibility of process and optimization shows sensible added profits in cash flow diagrams.