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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.

Patterson R.,Covey Consulting Pty Ltd | Covey G.,Covey Consulting Pty Ltd
Fibre Value Chain Conference and Expo 2014: Pulp and Paper Bioenergy Bioproducts | Year: 2014

Various types of transient flow can cause minor or major damage to pipework and associated equipment. Water hammer, caused by too rapid closing of a downstream valve is the most commonly encountered problem, but is not eh only cause. In the present case empty pipelines acting as surge chambers were able to cause massive oscillation of the fluid column. The problem could be resolved by comparatively simple measures.

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.

Covey G.,Covey Consulting Pty Ltd. | Shore D.,Covey Consulting Pty Ltd. | Harvey R.,Covey Consulting Pty Ltd. | Faber G.,Covey Consulting Pty Ltd.
Appita Annual Conference | Year: 2010

Commissioning is often the most difficult part of a capital project because although it is almost always possible to construct a plant, until it is complete there will always be some uncertainties about how a one-off system will behave. Unfortunately, planning for commissioning is rarely as thorough as for other stages of the project and there is always pressure to get the finished plant on-line as soon as possible. Further, in many organisations there are a limited number of people yvith experience of commissioning, because large projects are infrequent. Together these factors often lead to inefficient and even damaging strategies being applied. This paper discusses strategies and the development of skills that will usually result in more effective commissioning.

Allender B.,Covey Consulting Pty. Ltd. | Covey G.,Covey Consulting Pty. Ltd. | Shore D.,Covey Consulting Pty. Ltd.
Appita Annual Conference | Year: 2010

With increasing pressure on discharge quality and uncertainty of yvater supply in many parts of the world, the pressure to move towards effluent-free papermaking is increasing. The advantages of operating an effluent-free mill are that it requires no discharge licence, requires very little fresh water and can offer a product with good environmental credentials. Closure of a mill water system can result in a range of problems, the severity of which will depend on the nature of product being produced, the quality of the raw material and the degree of closure attempted. In most cases some additional treatment will be required before recycling the water. Commonly this will include at least one stage of biological treatment, but membrane processes, evaporation and other steps may also be required. Poorly applied, such processes can be very expensive and to be most cost effective the treatment process must be tailored to the needs of the mill and designed into the basic mill flow scheme. The types of problem that might be encountered are described and how these have been tackled in cases from mills employing very simple closure, through extensive biological treatment up to fully liquid effluent free mills.

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.

Harvey A.L.,Covey Consulting Pty. Ltd. | Harvey Reg.McA.,Covey Consulting Pty. Ltd.
Appita Annual Conference | Year: 2013

For cooling large volumes of water, cooling towers (CT) in their various forms are universally used. In oil refinery practice, large volumes of water are used for cooling distillation tower side streams or cuts of certain boiling ranges. [1] The overhead condenser for producing the reflux flow and product stream also requires large volumes of cooling water. Other refinery processes also require copious amounts of cooling water. Cooling towers reject low grade heat, tower water temperature differences tend to be in the range 8-12 C. In the case of high temperature water streams, in oil refineries, higher temperature water streams may be used to preheat boiler feedwater, heat exchanged with input process streams or may be cooled by using fan coil heat exchangers. Paper mills also require cooling water for various processes. In pulp mills these are to cool various liquid and vapour flows. The requirements for cooling water in paper mills are smaller but include vacuum pump sealing water. If a condensing turbine is installed, this will also require cooling water Cooling tower water must be properly dosed to stop build up of algae, bacteria etc. Legionaires disease is a well known problem with poorly treated CT water. Blowdown of a few percent is also required to control the build up of dissolved salts. In order to optimise cooling tower use, energy use particularly for fan operation or water supply needs to be minimised. Makeup water use should be optimised by minimising blowdown and spray and entrainment losses. Maintenance and cleaning of tower internals should be minimised by careful treatment of the recirculating water by dosing with a combination of pesticides. Fouling, Scaling and biological growths are all potential problems in cooling tower operation. These areas will be covered in this paper.

Covey G.,Covey Consulting Pty Ltd | Shore D.,Covey Consulting Pty Ltd | Harvey R.,Covey Consulting Pty Ltd | Faber G.,Covey Consulting Pty Ltd
Appita Annual Conference | Year: 2011

Many projects go well until they enter the commissioning phase and then even comparatively minor problems can cause a disproportionate amount of trouble and delay. The commissioning stage of the project is the time when delay is most expensive because the plant is paid for but is not yet producing an income. It is also the time when there is the most attention on the project and impatience from above can cause rash decisions to be made in an attempt to minimise the delay. If the commissioning experience is analysed after the event (which rarely happens) the reasons for the difficulties can usually be traced back to inadequate preparation for commissioning. This paper will cite various real-life problems that the authors have encountered and show how these might have been avoided, or at least reduced in severity by proper preparation. In every case, it is not simply a matter of 'being wise after the event'. With proper planning measures could have been in place to address the problem when it arose. The case studies will also include some for which proper planning in advance did result in avoidance of delays. These cases are often harder to identify because the problems that did not arise or which were solved promptly are simply not noticed or not documented by anyone. This can create difficulties in the next project because the measures which solved problems that did not cause much disruption can readily be omitted.

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.

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