Recovery of Waste Heat from Pyrolysis Reactor

Abstract

Fossil fuels are non-renewable sources of energy and the rate of consumption of fossil fuel is increasing as the world’s population and living standards of peoples is increasing. Globally average usage of the oil is around 11 billion tons per year and with this usage value the rate at which the reserves of crude oil is decreasing is around 4 billion tons per year.at this rate of depletion oil reserves will soon get vanished. Due to the threat of depletion of fossil fuels and increase of demand of energy a renewed interest has been developed for alternative fuel and one of the most important alternative fuel is pyrolysis oil. Pyrolysis oil is a kind of liquid fuel generated by a process called pyrolysis process this process involve thermal decomposition of large molecular weight organic molecules into small molecular weight organic molecules by supplying heat from some external source followed by condensation. Waste tyres can be used as feed in pyrolysis reactor and the oil obtained from the pyrolysis process of these waste tyres will be called as tyre pyrolysis oil. The energy that is obtained by combustion of these pyrolysis oil is greater than the value of energy supplied as heat during the pyrolysis process also pyrolysis oil has high heating value and less Sulphur, content.

During pyrolysis process a large amount of heat get wasted through convection and radiation from the pyrolysis reactor. Recovery of this waste heat increases the overall efficiency of the process to a large extent. The waste heat can be recovered using a suitable heat transfer fluid flowing around the pyrolysis reactor with a suitable flow rate. Different HTF have different properties due to which maximum temperature attained by different fluids is also different. The max temperature attained by the heat transfer fluid and the time at which the steady state reached depends on type of HTF used and also on the flow rate. The recovered heat can be used for commercial as well industrial purpose for e.g., HTF can be used can be used for domestic water heating, in industries the energy recovered by HTF can be used for air preheating as well as for feed water heating in thermal power plants. The amount of the energy recovered that can be used for useful purpose depends on the average temperature of the HTF until steady state and also on the time in which steady state is reached. Higher the average temperature of HTF higher is the quality of energy that is recovered and higher percentage of the heat recovered can be used for useful purpose. Higher the time to reach steady state directly indicate time for which energy is available for use.