Due to the constantly growing environmental concerns about global warming, there is immense pressure on the coal-to-liquids (CTL) industry to lower carbon dioxide emissions. This study evaluates the cogeneration of electricity and process steam, using coal and nuclear heat obtained from a High Temperature Gas Cooled Reactor (HTGR) such as a Pebble Bed Modular Reactor (PBMR), for the use in a CTL plant. Three different cogeneration processes were investigated to resolve what influence nuclear cogenerated electricity and process steam would have on the carbon dioxide emissions and the unit production cost of electricity and process steam. The first process investigated utilises coal as combustion medium and an extraction/condensing steam turbine, together with the thermodynamic Rankine cycle, for the cogeneration of electricity and process steam. This process was used as a basis of comparison for the nuclearbased cogeneration processes. The second process investigated utilises nuclear heat generated by a HTGR and the same power conversion system as the coal-based cogeneration system. Utilising a HTGR as a heat source can decrease the carbon dioxide emissions to approximately zero, with a 91.6% increase in electricity production cost. The last process investigated is the nuclear-based closed cycle gas turbine system where a gas turbine and Brayton cycle is coupled with a HTGR for the cogeneration of electricity and process steam. It was found on technical grounds that this process would not be viable for the cogeneration of electricity and process steam. The unit production cost of electricity and process steam generated by each process were determined through an economic analysis performed on each process. Overall it was found that the CTL industry could benefit a great deal from utilising nuclear heat as a heat source. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.

Due to the constantly growing environmental concerns about global warming, there is immense pressure on the coal-to-liquids (CTL) industry to lower carbon dioxide emissions. This study evaluates the cogeneration of electricity and process steam, using coal and nuclear heat obtained from a High Temperature Gas Cooled Reactor (HTGR) such as a Pebble Bed Modular Reactor (PBMR), for the use in a CTL plant. Three different cogeneration processes were investigated to resolve what influence nuclear cogenerated electricity and process steam would have on the carbon dioxide emissions and the unit production cost of electricity and process steam. The first process investigated utilises coal as combustion medium and an extraction/condensing steam turbine, together with the thermodynamic Rankine cycle, for the cogeneration of electricity and process steam. This process was used as a basis of comparison for the nuclearbased cogeneration processes. The second process investigated utilises nuclear heat generated by a HTGR and the same power conversion system as the coal-based cogeneration system. Utilising a HTGR as a heat source can decrease the carbon dioxide emissions to approximately zero, with a 91.6% increase in electricity production cost. The last process investigated is the nuclear-based closed cycle gas turbine system where a gas turbine and Brayton cycle is coupled with a HTGR for the cogeneration of electricity and process steam. It was found on technical grounds that this process would not be viable for the cogeneration of electricity and process steam. The unit production cost of electricity and process steam generated by each process were determined through an economic analysis performed on each process. Overall it was found that the CTL industry could benefit a great deal from utilising nuclear heat as a heat source. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.

An existing furnace oil fired boiler is used to supply process steam to an instant tea manufacturing factory. The instant tea is manufactured the Broken Mixed Fannings (BMF) through extraction and other required processes. The average steam consumption of the plant is 6000 kg/h at 10 barg pressure. During the process, tea waste is generated at a nominal rate of 50,000 kg/day, about 2000 kg/h at around 70% MC content on wet basis. At the moment this waste tea is either dumped in the surrounding area by spending money or sent to landfilling purposes, which create environmental issues.   The tea waste coming out at 70% MC wet basis, is looked at to press through continuous belt press to reduce the moisture content to about 55% on wet basis. The water removed from this pressing process is sent to effluent treatment plant at the factory. The output from the belt press is sent to a steam operated  The average generation of tea waste from the instant tea manufacturing process process is about 2000 kg/h, after pressing in the belt press an output rate of about 1,400 kg/h at 55% MC. This amount of tea waste at 55% MC is sent to a rotary steam tube dryer and the MC is reduced from 55% to 30% and the output rate from the steam tube dryer is about 857 kg/h. The amount of steam consumed by the rotary steam tube dryer at 6 barg pressure is 760 kg/h. Then the tea waste from the rotary tube dryer is mixed with firewood of 30% MC and fed to the boiler to generate process steam, out of which 857 kg/h steam at 6 barg pressure is sent back to the rotary steam dryer. From tea waste alone, a steam amount of 2,472 kg/h can be supplied after giving steam to the rotary steam dryer. The balance steam amount of 3,528 kg/h for the process requirement is supplied by burning additional firewood at 30% MC content. The tea waste fuel and firewood in combination have an overall moisture content of 30% on wet basis. The boiler is rated at 10,000 kg/h F & A 100 deg C with an actual generating capacity of about 9000 kg/h at 10 barg operating pressure at 70 deg C feed water temperature. By implementing the combination of belt press, rotary steam tube dryer and firewood boiler in place of the existing furnace oil fired boiler, an annual monetary saving of 168 Mn SLR/year can be achieved with a simple payback period of 21 months which is a highly feasibly project.

This master’s thesis deals with design of technological system for heating and process steam generation. The source of energy is a cogeneration unit. The thesis is divided into several parts. The first part is design of technological system and description. The second part is realized stoichiometric calculation and the thermal balance of steam boiler. The main part of thesis is design of the waste heat steam boiler. The thermal calculation, aerodynamic calculation, hydraulic calculation and strength calculation were made. The thesis also includes the drawing of designed waste heat steam boiler.