英语翻译Online Monitoring and Control in the Wet-End Loads from

英语翻译
Online Monitoring and Control in the Wet-End
Loads from the DIP plant those additives should be used.To keep the optimum charge level in the DIP line the fixing agent has to be dosed according to a continuous cationic demand measurement of the filtrate in the thick stock .To optimize polymers in the flotation processed and to get the highest efficiency of wet strength resin defoamer chemical should be controlled online on a lowest possible level.
Example 3
In mills which produce consumer tissue using mixed furnish and producing many different grades felt deposit problems are daily occurrence.To find out the origin of stickies mills usually invest a lot of manpower over time.Applying online charge control in white water provides ready access to information about the driving parameters of the process.Increased,up to date process knowledge results in much less deposits.Additionally,reduction of wet-end chemicals is most likely.
The chemistry of different grades is reflected by the varying charge level in the white water.This is driven by furnish ratios and the different amounts of WSR and dyes needed for the production of specific grades A continuous cationic demand signal allows the operator to adjust the process quickly to the new process situation.A database established over time will help to provide a guideline for the operators for every single grade.Cationic demand variations within one grade reflect the quality variation of the incoming furnish This allows the purely on demand usage of fixing agents.Label paper production with extreme variation in broke quality would be a typical example for this type of application .
Due to the favourable market position in board production the interest in wet-end control equipment is rising.Historically,the focus was only on drainage improvement on the wire and in the press section,as the bottleneck is uaually found in drying capacities.Today,with lower basis weight productions and increasing demand on board properties this focus in shifting.At lower basis weghts retention control strategies are implemented and closed-loop control of retention aids are becoming srate of the art for fast-running machines.Reduced fibre quality and increase of recycled pulp result in reduced sheet quality and an increased demand in strategic chemical additives.Therefore,classical charge control for fixing agents in the thick stock area becomes more common as it has been in use already for many years in fine paper and newsprint production.
Defoamer dosage is considered to be a cheap investment .For every machine there is an optimum air content level concerning energy savings through pumps,de-watering properties of the pulp and efficiency of chemical additives.
After this optimum value has been detected it needs to be maintained.This is only possible by measuring the free and dissolved gas content in the white water and head box(流浆箱).Closed-loop control of defoamer chemicals in board is very straightforward and relatively easy to implement .
Of course,multiple layer machines make wet-end control more complex.The need to focus on major layers to achieve the best possible payback is obvious.To find out the best online control strategy for a certain board machine all aspects of the process should be analysed.
With a mutek DFR-04 lab unit the effect of various defoamers on drainage can easily be tested.For optimum performance of retention and drainage aids a MutedRET-20 Rerention Inline and a Mutek DRA-50 Drainage Analyzer are best installed directly in the headbox and white water.

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