Technical viability of environmentally compliant small-scale energy from waste systems

Bokhari, Iftikhar (2021) Technical viability of environmentally compliant small-scale energy from waste systems. PhD thesis, University of Lincoln.

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Technical viability of environmentally compliant small-scale energy from waste systems
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Item Type:Thesis (PhD)
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Abstract

The continuous increase in domestic and commercial waste generation has an adverse impact on the environment and on human health. Possible ways to address this issue is to use waste for energy generation using the incineration process. This study shows how an incinerator is designed, modelled, developed, built and tested for estimating the maximum available energy from a range of waste streams. It also highlights the need to balance the disposal of waste in a manner which is sustainable. There is also a need to be as compliant as possible with meeting emission requirements, whilst maintaining a sufficient throughput of waste that can be incinerated efficiently. A modified energy-based method for calculating the improvement potential in a waste-to-energy plant has been developed. Thermal destruction of the real waste products was compared with corresponding theoretical process. The range of waste investigated included, refuse derived fuel, minimised solid waste, animal waste and biomass. A custom designed solid-waste prototype incinerator was used to investigate improvements in the system when applied to a much larger industrial scale application. Modifications considered included there-arrangement of ambient air inlets and changes to the internal structures of a primary chamber and a review of burner specification. Modelling and simulations were performed using the ANSYS software. The results showed that the method developed for testing and burning of waste model was more accurate than the previous models for estimating the maximum available energy in waste material. The proposed model incorporates all the major elemental constituents and the physical composition of the solid waste. Moreover, the results obtained from the higher heating value model show good correlation between the values measured and are comparable with previous models. The thermal insulation used in the MB1 model thermal insulation thermal efficiency ranged from 80% in the chimney stack, 94% in the secondary chamber to 96% in the primary chamber compared to the ambient temperature during normal operations. The use of additional ambient air supplied by a variable inlet fan enabled the waste fuel to be combusted more efficiently and retain higher operating temperatures in the primary and secondary chambers which reduced the amount of fossil fuel required for the incinerator operation. This allowed the recording of data for burn rates for each type which other manufacturers are unable to provide. A large upscaled Moving Grate was also modelled to burn 700kg/hr of RDF and where actually it burnt 430kg/hr. This allowed the integration of Organic Rankine Cycle (ORC) generators to provide electricity and heat to offset the parasitic load. For burning of 200kg/h with a calorific value of 15MJ/kg can drive one ORC generator providing approximately 70kWe power. For burning 1000kg/h of approximately generating 351kWe of electrical power.

Keywords:incineration, waste disposal, Sustainability, energy production
Subjects:F Physical Sciences > F310 Applied Physics
Divisions:College of Science > School of Mathematics and Physics
ID Code:49500
Deposited On:23 May 2022 10:34

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