WINNING the paper chase

The on-going investigation by the European Commission into allegations of price fixing between European paper manufacturers only serves to illustrate the pressure the pulp and paper industry is under to stay competitive.

In an industry which is highly capital intensive and a new mill can cost over £200 million - the price of an ethylene cracker - investors demand maximum return and plants are therefore operational 24 hours a day. This makes the industry highly sensitive to demand fluctuations as adequate profit margins are vital to maintain inward investments which translate to technological advantage.

The alleged market sharing cartel was created during 1989 and 1995, just when the consumption of paper and board in the UK fell for the first time since 1982. The Paper Federation of Great Britain (PFGB) admits it is a constant battle for the industry to maintain production at a level which permits it to retain both market share and profitability.

However, on paper the industry appears healthy with the value of sales of print paper consumed in 1997 at around £3 billion. On a European scale this leaves the industry with a turnover of £28 billion, just short of consumer electronics at £32 billion. Demand for paper shadows the rate of general economic activity and in the last 10 years consumption has almost doubled. In this respect the industry is at the mercy of the availability and the cost of three necessary commodities: water, energy and pulp.

Despite changes in traditional use of paper due to the growing use of paperless communication, the PFGB still forecasts growth. David Pryke of the Institute of Paper predicts, `the use of paper will maintain a steady increase in volume, but I think inevitably new technologies will come on stronger and stronger even as the months go by.'

Efficiency, however, continues to govern production costs. Over the last 20 years water usage has been reduced by 70 per cent due to increased internal recycling. In the last 10 years energy consumption has been reduced by 30 per cent due to improvements in energy efficiency, machine performance, improved boiler efficiencies and a move to combined heat and power (CHP) which, according to the PFGB, is at least twice as efficient as conventional fossil fuel power stations.

Recent developments in rules regarding own-generation have led to renewed interest in CHP and the industry is enjoying new opportunities in power generation.

Deregulation of public fuel utilities has also helped the industry negotiate energy costs through better competition and cogeneration schemes, but the PFGB believes there is still scope to cut fuel bills further, particularly through an awaited dividend resulting from the privatisation of electricity.

There are a number of techniques available which, although they are on a micro scale, if combined will have cumulative effects on profitability.

One technology facilitating a plant's internal efficiency is membranes.

Membrane separation processes provide a physical barrier that is permeable to one liquid phase and not another. The product can be retained or allowed to permeate the membrane depending on its properties. To do this a driving force is required, in this case pressure. Flow through the membrane tube maintains filtration efficiency by keeping retentate in suspension or solution, reducing blockage.

Steve Morris, PCI Membranes' forest products specialist says, `it depends on the application but you might be looking at replacing membranes every year or two. You design the plant so that it stops at certain concentration levels, preventing blockage.'

This technology is ideally suited to solving separation problems in the pulp and paper industry. Steve Morris believes environmental regulations are an opportunity and tend to increase people's level of interest, ultimately helping the industry.

`The first thing people look at is trying to close the loop and prevent the effluent in the first place. You are doing two things. You are treating your effluent and you are actually getting something back. The economics of using a membrane plant require that you have to have product recovery to be viable, recovery is a capital cost.'

Typically, membrane technology has a number of cost saving applications; COD/BOD, colour and toxicity removal from bleach effluent; deresining of pulp wash water; debarking water for colour/COD removal; whitewater treatment for water recycling and toxicity removal; deinking effluent for colour removal; concentration of fibreboard; recovery of spent sulphite liquor for lignosulphate fractionation; concentration of sulphite liquor prior to alcohol production; recovery of coating materials from effluent streams.

Different applications need different membranes so an optimum membrane solution must be engineered for a particular site.

`With every pulp and paper mill you have very site specific conditions. What is economic to do in one place is not necessarily true in another. The difficulty is actually repeatability.'

Systems are based on tubular membranes for liquids containing suspended or colloidal materials, spiral wound membranes for clear liquors and ceramic membranes for high temperature long-life applications.

Control valve diagnostics also have an important part to play in increasing paper mill profitability, whether as part of a defined, lower cost maintenance strategy or in order to reduce process variability by improving the performance of a control valve.

Entech, a Canadian process control company specialising in the paper industry, sampled 230 valves that had diagnostic checks carried out on them. Poor control valve performance caused increased variability in 30 per cent of the loops Entech tested, illustrating the need for tighter control.

From the random sample of valves that had diagnostic checks carried out 5 per cent showed no malfunction whatsoever and did not need attention; overhauling these would have been a waste of money. 37 per cent needed only minor adjustment, 27 per cent needed repairs that could be performed without removal and 31 per cent needed repairs that required removal.

John Weet, customer support specialist at Fisher Rosemount put costs to these percentages and found that if a plant runs a preventative maintenance programme with a typical annual shutdown of two weeks, there is the potential to reduce overall valve maintenance costs by 50 per cent by adopting a different strategy.

`There has been a move toward predictive strategies as research has shown the costs to be five times less than a preventative strategy,' says John Weet. For an effective maintenance programme, it is necessary to run a diagnostic check, where a signal is sent to an I/P converter or positioner.

Measurements are taken of signal, pneumatic pressures and valve travel, which are then used to plot graphs of signal variation. When all data is collected it is used to generate valve performance signatures.

Fisher Rosemount's FieldVue digital valve controllers (see fluids handling section p43) are digitally communicating microprocessor-based pneumatic instruments, giving access to information using HART protocol. The controller receives feedback of the valves position and actuator pressure.

This gives the user all of the information necessary for predictive maintenance at the time when it is essential. Users can identify and eliminate sources of variability as well as being able to predict failure.

Recycled fibre (RCF) is a commodity traded between UK Paper and adjacent New Thames Paper Mill in Kemsley. RCF pulp is piped directly to the Kemsley mill where it provides a cost effective alternative to virgin paper pulp.

Johnathan Scott, UK Paper production engineer says that for the RCF plant, the mass flow of RCF pulp is a key performance indicator used for calculating yield - the amount of pulp produced from waste paper. Small shifts in yield greatly affect profits and the New Thames Mill accounts for the consumption of the majority of the RCF plant's output. Accurate measurement of flow is therefore vital.

`Three electromagnetic meters were originally installed in the line connecting the plants. We used the values from one meter, used one as spare, and the other for consistency measurement, to provide mass flow for RCF in both plants. Unacceptable discrepancies of five per cent between the two value were common.'

Measurement of paper pulp is difficult because of the noise generated by the fluid in the meter tube. The frequency of the noise is usually similar to the electrical signal generated by the flow.

Two 200mm Admag AE flowmeters from Yokogowa were installed between the plants. Because the correct solution was critical, UK Paper's engineers insisted they were supplied with process guarantees. Yokogowa's dual frequency system overcame the noise generated by the pulp. The tough ceramic lining helped increase accuracy. Stability of readings quickly became apparent after start-up.

`Both Admags gave highly reproducable readings. The output of one meter is used in the calculations by both the RCF Plant and Thames New Mill.'

While the PFGB relies on macro economic solutions to cutting costs and maintaining market share by lobbying Government and creating consensus within the industry, engineering solutions are still finding ways to improve overall efficiency.

Whether it is by product recovery leading to closed loop plants, analysing maintainance strategies or improving product accountancy with advanced equipment, there is still room for improvement. PE