US2379835A - Continuous flow apparatus for testing pulp freeness - Google Patents

Description

EY 3, w45- c. o. slsLER CONTINUOUS FLOW APPARATUS FOR TESTING PULP FREENESS Filed Feb. 5, 1944 Patented July 3, 1945 i CONTINUOUS FLOW APPARATUS FOR TESTING PULP FREENESS Charles Oland Sisler, Sault Ste. Marie, Ontario, Canada Application February 1944, Serial No. 521,247

6 Claims.

This invention relates vto apparatus for testing and recording pulp freeness or slowness The property of water drainage through a pulp slush suspended on a Woven wire or perforated plate is used in the paper or pulp board manufacturing process. Water drainage rate is also used as a means of evaluation of pulp quality or suitability for Various paper making requirements when a standard weight of pulp in suspension is drained of its contained water by means of a perforated plate or woven wire under standardized conditions. The resultant volume of, or time required .to reach a certain speciiied volume of drainage under fully standardized temperature, consistency and other conditions, is a measure of the respective freeness or sedimentation time for a given pulp.

At the present time this freeness or sedimentation test data, hereinafter called freeness,` is generally secured by .individual separate tests on samples removed from time to time from the pulp system. This invention relates to a machine into which is fed a continuous flow of the slush pulp to be tested and which delivers -the freeness test data continuously on a chart or by other means.

The object of this invention is to provide a simple and accurate means'for obtaining continuous immediate freeness data on pulp from a pulp production or prepara-tion system, thereby avoiding delay in securing this quality information.

With the above objects in view the invention consists of a horizontal or sloped belt of woven wire of suitable mesh and size, driven at a predetermined selected constant speed, upon which a constant volume per second of the pulp stock to be tested is uniformly fed and distributed.

The pulp sample is supplied to the machine from a commercial pulp regulator at a consistency common to :these types of regulators. Means are provided for either heating or cooling the water and the pulp stock within the mixer. A constant volume of the pulp sample is mechanically mixed with a vconstant volume of fresh water and fthe mixture controlled to a constant temperature, so that a constant volume per secon`d of constant temperature and consistency is permitted to flow through suitable ducts to a suitable slot or slice opening at .the head end of the wire belt.

The continuous drainage of water from the lm of pulp carried by the movingwire .belt is 4 all or part collected by a tray located beneath the Wire belt and thence conducted to asuitable volumetric measuring device, which continuously reports 0r records the ilow per unit of time in terms of pulp freeness. Means are provided for the continuous removal of the pulp lm at the end of vthe wire belt or close to Ithe point of its r has been previously regulated :to a uniform consistency by a commercial pulp consistency regulator from the pulp system to a constant level chamber 2 fitted with a suitable overoW opening 3 adjacent the top thereof, and an orifice 4 of suitable design in the -bottom thereof. A similarly designed chamber 5, larger than chamber 2 is provided in which a constant level of fresh wateris maintained, with an inlet pipe 6 and an overflow pipe l, and an orice of suitable design 8.

The preceding apparatus provides a constant volume discharge of pulp and Water from the orifices il and 8 respectively. The orices 4 and 8 consist of standard thin plates circular in shape, having a central hole and set into recesses in the bottoms of the tanks 2 and 5. These holes are so designed that a constant quantityper minute of stock and water passes through under the constant head conditions provided. The water and stock are collected by receivers 9 and Ill and conducted to a mixing chamber Ii, in which a mechanical agitator I 2 of suitable design. is driven by an electric motor I3 or other means. In the mixing chamber I I are located a heating or cooling coil I4 which is supplied with suitable refrigerant or heating fluids depending on whether it is necessary to heat or cool the pulp mixture. Automatically controlled means, comprising a thermometer bulb Il'la connected -by tube Mb to a valve It, areprovided so that a constant :tem-

perature will be maintained on the pulp mixture passing through lthe mixer. Standard temperature for freeness testing purposes is 20 C. Separate cooling and heating means or elements may be used.

From the mixing chamber III the mixture of pulp and water at a constant volume per second, constant temperature and consistency, is conducted by pipe I5 to the constant level headbox Il. I6 is an air vent on line I5. The headbox Il is suitably equipped with baiiles I9 to control vided in the wall 20 of locity. The width of as desired by means of a vertically adjustable driven by and smooth out the iiowing stock suspension. An overflow spout I8 ensures a constant level in the headbox I1. A slotted orice or slice I9 is proheadbox I1 from which the stock suspension is uniformly discharged in 5 a continuous ribbon the full width of the contan s eed wire mesh belt 2| at a constant ves t p the orifice I9 may be varied gate ISB. This stream of pulp suspension is 10 picked up and carried along by the belt which is moving at a constant predetermined rate of speed away from the slice opening at a speed more or less the same velocity as the stock being discharged. Deckle or guard straps 22 of suitable 15 material and design are arranged on each side of the wire belt to prevent side overilow of the pulp suspension. The wire belt 2I is carried by a series of supporting rolls 23 suitably placed and is guided and tightened by rolls represented 2o by 24 and 25. Suitable means for cleaning the wire belt 2I is provided by the steam or water shower pipe 26. Roll 21, known as a couch roll, is the only driven roll in the machine, being a belt, chain or gears from motor 28 25 or some other power source at a suitable speed.

The water drainage from the wire 2I is wholly or partially caught by a pan 29 and led from either or both sides of the machine by a pipe or pipes 30 to a measuring device such as a tank 3| 30 where it flows over a weir 32, and the now 1s recorded by a commercial type of level recorder.\ Such a device is indicated diagrammatically in Figure l, in which a diaphragm 33 is shown submerged in the liquid above the weir and connected with a recording device v31 having a rotating chart 33 and stylus 331i' for inscribing a I l record of iiquid1eve1hangesin the tank s l. The

VAlevel varies with the rate of ow, this flow representing the freeness of the stock passing through the machine. The recording instrument 1s so calibrated in conjunction with the iiow measuring device that it will record stock freeness directly. y A pan 34 having a drainage pipe 35 is provided 45 to catch and drain off the pulp and water mixture cleaned off the wire bythe spray from the shower pipe 26. Stock and water conductors bearing stock rejected from the machine and passing oil through the pipes at 3, I6, 30 and 35 can be piped 50 into a common return pipe and returned to the stock system for recovery.

In Figure 2 I have illustrated an alternative recording devic'e comprising a standard thin plate orice 36 in the pipe 30.. This is connected by 55 piping to a commercial diierential metering recorder which will continuously record the rate of iiow or liquid in the line 30 either in terms of gallons or other unit of measurement per hour, or direct in lterms or pulp freeness. 60

What I claim as my invention is:

l. Apparatus for continuous testing. of pulpv freeness,' comprising a mesh belt moving at a constant predetermined rate of speed, a constant level chamber for the stock, means for carrying a V continuous flow of sample pulp stock from a paper pulp system to said constant level chamber, means for adding liquid to the stock in predetermined volume, means for mixing the stock and liquid t0 70 provide a uniform` mixture, means for carrying the stock from the constant level chamber -to the mesh belt, means for collecting the liquid from the stock that passes through the mesh belt, means for carrying oi the liquid thus collectedin a continuous now, and means for measuring the rate of flow of such liquid in the latter means.

2. Apparatus for continuous testing of pulp freeness, comprising a pulp constant level chamber and a water constant level chamber, means for conducting sample pulp stock to be tested from 9, paper pulp system to the Lpulp .constant level chamber, means for conducting water to the water constant level chamber, a mixing chamber, means for conveying a constant volume of pulp and water from said constant level chambers to the mixing chamber, means in the mixing chamber for mixing the pulp and water, a mesh belt moving at a constant rate of speed, means through which the mixture ilows to said belt from the mixing chamber, means for collecting the liquid that passes through said belt, means for carrying of! the liquid thus collected in a continuous flow, and means for measuring the rate of flow of the liquid thus collected in the latter means.

3. Apparatus for continuous testing of pulp freeness, comprising a pulp constant level chamber and a water constant level chamber, means for conducting sample pulp stock to be tested from a paper pulp system to the pulp constant level chamber, means for conducting water to the water constant level chamber, a mixing chamber, means for conveying. a constant volume of pulp and water from saidconstant level chambers to the mixing chamber, means in the mixing chamber for mixing the pulp and water, means for maintaining the temperature of the mixing chamber at a substantially constant predetermined degree, a mesh belt moving at a constant rate of speed, means through which the mixture flows to said belt from the mixing chamber, means for collecting the liquid that passes through said belt, means for carrying oil the liquid thus collected in a continuous flow, and means for measuring the rate of ow of the liquid thus collected in the latter means.' l

4. :Apparatus for continuous testing of pulp freeness, comprising a pulp constant level chamber and a water constant level chamber, means for conducting sample pulp stock to be tested from a paper pulp'system to the pulp constant level chamber, means for conducting water to the water constant level chamber, a mixing chamber, means for conveying a constant volume of pulp and water from said constant level chambers to the mixing chamber, means in the mixing chamber `for mixing the pulp and water, a head box having baiiles therein, means through which the mixture from the mixing chamber flows to the head box, a mesh belt moving at a constant rate of speed, means through which the mixture ows yto said belt from the head box, means for collecting the liquid that passes through said belt,l means for carrying off the liquid thus collected in a continuous flow, and means for measuring the rate of ilow of the liquid thus collected in the latter means.

5. Apparatus for continuous testing of pulp freeness, comprising a pulp constant level chamber and a water constant level chamber, means for conducting sample pulp stock to.be tested from a paper pulp system machine to the pulp constant levelfchamber, means for conducting water to the water constant level chamber, a mixing chamber, means for conveying a constant volume of pulp and water ,from said constant level chambers to the mixing chamber. means in the mixing chamber for mixing lthe pulp and water, means for maintaining the temperature oi' the mixing chamber at a substantially constant predetermined degree, a head box having baliles therein, means through which the mixture from the mixing chamber ows to the head box, a. mesh belt moving at a constant rate of speed, means through which the mixture flows to said belt from the head box, means for collecting the liquid that passes through said belt, means for carrying off the liquid thus collected in a continuous flow, and means for measuring the iow of the liquid thus collected in the latter means.

6. Apparatus for continuous testing of pulp freeness, comprising a mesh belt moving at a constant predetermined rate of speed, a constant 3 level chamber for the stock, means for carrying a continuous now of sample stock from a paper pulp system `to said constant level chamber, means for mixing the stock to provide a uniform mixture, means foi-'bringing the stock to a predetermined temperature, means for carrying the stock from the constant level chamber tothe mesh belt, means for collecting the liquid from the stock that passes through the mesh belt, means for carrying oil' the liquid thus collected in a continuous flow, and means for measuring and recording the rate of Aflow in the latter means in terms of freeness.

CHARLES OLAND SISLER.

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