unbleached pulp production from the digesters in a paper plant

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Thank you for your response.What is required is that we have a continuous digester wherein we feed bamboo & wood chips continuously at a certain feed rate alongwith chemicals and after around four and half hours the cooked pulp would be disharged to the blow tank which is also continuous.In the discharge line we have a magnetic flow meter and consistency transmitter alogwith control valve to maintain the consistency at around 10.5%.I would like to know the normal industrial practice of specifying the daily production whether they are relying on the above two instruments or coming from the finished product.Hope now it must be clear.I appreciate if you can indicate reliable consistency transmitters for pulp application.

Hello, in the paper mill I work at we use 15 batch type digesters to produce pulp. they are set up to cook a load about every 45 minutes from load up to blow. When we are running well we will have a digester blowing about every 20 minutes some where in the 15 digesters. Our digesters are 40'tall, 14' diameter and they start with a 2" wall thickness. The tank has a coned bottom and a spherical head design. We basically put wood chips into through the top 30" capping valve, white liquor goes in the top through a 6" stainless nozzle. 150 lb. steam is introduced from the bottom 12" blow nozzle. When the cook is complete a valve in the 12" "blow" piping near bottom of the digester opens and the pressure of the steam pushes or "blows" as we say it the cooked pulp through the pipe into a blow tank in which the pulp goes to the bottom and the vapor rises and goes through a vent pipe to an accumulator tank. The pulp is then sent on to the washers to have the chemicals washed out of it and from there through a series of refiners to the paper machine head box. Most of the chemicals used and generated from the pulping process are recovered at each stage to be refined and re-used. This is the basics of unbleached pulp production at our mill. bleached pulp is much the same except they have a extra bleaching stage.

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