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Covey G.,Covey Consulting Pty Ltd
Appita Annual Conference | Year: 2010

Biorefineries are often seen as analogous to oil refineries, but in reality they will probably have a quite different scope as they will produce a narrower range of liquid fuels but a much broader range of chemicals and solid products. Further, whereas oil is taken from the ground and then all taken to oil refineries for processing, the logistics of moving ligno-cellulose from its point of growth to the bio-refinery will be much more complicated. To this must be added difficulties such as competition for land use and conservation issues. This paper will discuss how these factors might be addresses and how integration might be achieved at all levels in the chain from forests to finished products.

Harvey A.L.,Covey Consulting Pty Ltd
Fibre Value Chain Conference and Expo 2015: Pulp and Paper Bioenergy Bioproducts | Year: 2015

Co-generation or simultaneous production of electrical power and steam is well established in the paper industry. High pressure steam from the boiler drives a turbine coupled to an electrical generator and the exhaust steam is used to provide heating for the paper mill dryer train. The efficiency of the combined cycle may be in the range of 65-75% whereas the efficiency of power generation alone is of the order of 30-35%. LII Since energy costs are a considerable percentage of operating costs of paper mills, it is worth considering further methods to improve thermal efficiency of the combustion aspects of the steam generator, particularly the use of combustion gases from the boiler to extract more heat to itnproe the thermal efficiency. First costs of plant are reduced with co-generation or combined cycle systems compared with costs for separate electrical poer and steam generation systems. Co-generation reduces pollution due to its increased efficiency compared with separate plants for electrical power generation and steam generation. Also reliability of electrical supply is essential in paper mill operation and co-generation provides a high reliability power supply for paper or pulp mill operations.

Patterson R.,Covey Consulting Pty Ltd
Fibre Value Chain Conference and Expo 2015: Pulp and Paper Bioenergy Bioproducts | Year: 2015

Covey consulting has been involved in the design and commissioning of several successful steam storage installations over the past 25 years. These have all been of the "Ruth Accumulator" or variable pressure type, which are typically installed to protect the steam generation plant from rapid load swings. Steam storage devices are an old concept which is rarely seen these days. Modern gas fired boilers can generally tolerate rapid load swings without unacceptable cost in efficiency and emissions. However solid fuel fired boilers coupled to large and rapid load swings can still be a serious problem, leading to loss of efficiency and unacceptable emissions. The accumulators we have been involved with have had to do with coal- fired and recovery boilers coupled to batch pulp digcstcrs. All started up and worked reliably for many years. Our intention in this presentation is to explain how these devices work, and to provide practical methodology which would allow an engineer to carry out sizing and design. We have used real numbers, and typical data to this end.

Covey G.,Covey Consulting Pty Ltd
Appita Journal | Year: 2010

An attempt is made to show how sunk costs should be treated objectively and simple examples of how failures to do this can result in poor financial decisions are presented. A mining company investing AUD 3 million in sinking a deep mine shaft to exploit mineral deposit should accept an offer of AUD 200,000 irrespective of the cost of sinking the shaft to position a geo-monitoring equipment in a deep hole. To buy an equipment for AUD 100,000 one should either complete the original purchase for an additional outlay or a sunk cost of AUD 70,000. A company spending AUD 50 million to build a production facility adopted a new technology to build a new plant costing AUD 50 million while dealing with the sunk cost of the original investment. The problem of low throughput loss making plant of the company can be resolved by the expenditure of a AUD 1 million after which the plant will be able to generate a profit of AUD 0.7 million/year.

Harvey A.L.,Covey Consulting Pty Ltd | Harvey R.M.C.A.,Covey Consulting Pty Ltd
Fibre Value Chain Conference and Expo 2014: Pulp and Paper Bioenergy Bioproducts | Year: 2014

Biomass in the form of wood residues or many other forms is co-fired with refuse derived fuel (RDF) and burned with coal as a way of reducing the carbon footprint and utilising biomass materials to provide extra heat for steam or electricity generation. The variable properties of biofuels, fuel handling, feeding, fouling, slagging and superheater corrosion are challenges not present in simple coal fired systems and must be overcome. Variable moisture content makes a fundamental difference to the biomass heating value. Circulating fluidised bed (CFB) furnaces have proved very well suited for heat and power production for a wide range of co-fired biofuels and municipal refuse or coal.

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