Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/10—Devices for withdrawing samples in the liquid or fluent state
  • G01N1/20—Devices for withdrawing samples in the liquid or fluent state for flowing or falling materials
  • G01N1/2035—Devices for withdrawing samples in the liquid or fluent state for flowing or falling materials by deviating part of a fluid stream, e.g. by drawing-off or tapping
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials

Definitions

• the present invention relates to an apparatus and a method for permeability measurement, said apparatus is provided f .sampling a suspension passing through a pipe, particularly a fibrous suspension, and comprises a sampling cylinder housing attachable round an opening made in the wall of th pipe, the housing being open towards the interior of the pipe and accommodating concentrically an axially displace- able sampling cylinder, adapted for taking a suspension sample from the pipe for the purpose of determining its permeability or freeness level and also the permeability of a sample impoverished of fines or smaller fibre fragmen
• Drainage transmitters or meters provided so far usually ha a very complicated structure, which results in expensive service, as well as the installation of these meters in a pulp line requiring special arrangements. Due to this the weight of this type of meter rarely falls below 50 kg, whi makes dismantling the meter more difficult when it is to b cleaned, for example. Other problems with this kind of met is that they are easily blocked up by fibers remaining fro the fiber suspension after sampling. These meters moreover lack the possibility of determining the permeability of the long fiber portion of the pulp sample.
• the present invention has the object of providing a draina rate transmitter of the kind mentioned in the introduction, which is substantially distinguished in that the sampling piston has a cylindrically formed through-hole at right angles to its longitudinal direction, the hole forming a sample chamber, such that when the sampling piston is in i retracted position inside the housing the chamber is in register with at least one hole of substantially the same diameter in the cylindrical surface of the housing, for connecting to it a preferably cylindrical casing defining a mixing and dilution chamber r in which there is an agitat ing or mixing device, the casing being provided with two opposing openings, of which one has the same diameter as the hole in the cylindrical surface of the housing and the ' other has a shape affording sealing connection to an end wall member carrying a screening plate, said member being provided with a drainage collection duct under the screeni plate for conveying measuring water passing through a fibr bed formed on the screening plate to measuring means for determining the drainage properties of the sample taken, a also of a sample which has been completely or partially liberated from smaller fibre fragments
• the present invention also relates to a method of determin ing the permeability,. particularly in a fibre suspension the method being substantially distinguished in that smalle fibre fragments in a pulp sample introduced into the measuring or mixing chamber, after filtering against the screening plate and subsequent permeation of water during one or more pressure drops, possibly after slushing by agitation of the pulp bed built up aginst the screening plate between the different measurements, are removed by once again bringing the pulp bed into suspension by slushi with the aid of the mixing or agitating means and a simultaneously applied flow of water, after which the fib suspension, substantially impoverished of fine material, once again filtered against the screening plate after .terminated agitation, the permeability of the pulp bed formed once again being measured during one or more press drops, possibly with intermediate slushing and reformatio of the bed.
• the drainage rate transmitter 1 illustrated on the drawin includes a cylindrical sampling piston housing 4, fixable an opening 3 made in a pipe 2 or a vessel with agitated contents.
• the housing 4 concentrically accommodates a sampling position and a retracted position with the aid o a piston rod means 7 attached to its outer end portion 6, the piston rod being associated with a pneumatic cylinder
• these holes are also preferably cylindrically formed and of the same diameter as the chamb 9.
• the upper hole 10 continues into a space 13 defined by a cylindrical wall 14 of the same diameter as the hole 10 and by an end wall 12.
• the space 13, hole 10, sample chamb 9 and hole 11 thus form a continuous chamber, such as to avoid dead spaces which can give rise to collections of fibres from different samplings.
• a measuring water nozzle 15 opens out into the space 13, and the nozzle is in
• O ⁇ IPI communication with a water supply via a valve 16.
• the space 13 is in communication with an outlet 17 via a hole in the end wall 12, this communication being regulated by an outle valve 18.
• the piston rod 7 may be exchanged for two mutually parallel partial piston rods, or attached, as illustrated on the drawing, to the outward end portion 6 of the piston 5 at a point situated at a distance from the axi of the piston 5.
• the drainage rate transmitter in accordance with the presen invention is suitably used for sampling suspensions which have a concentration of about 1-10%, and for the cases wher the permeability of a sample, liberated from smaller fib fragments is to be determined.
• the lower hole 11 of the housing 4 opens out into a mixing and dilution chamber 35 formed by a casing 32 which has two opposing openings 33, 34, of which the upper 33 fits sealingly into the hole 11 and the lower 34 is adapted to seal against an end member 2 carrying a screening plate 22.
• the end member 23 includes a drainage collecting duct 24 arranged under the screening plate 22, the duct opening out conically in the area under the screening plate.
• the duct 24 is in communication with a measuring glass 26 containing tw electrodes 27, 28, and in an area directly under its conica portion is connected to a flushing water supply via a valve 29.
• the measuring glass 26 may be emptied via an outlet 31 and an outflow control valve 30.
• the length of the casing 32 may be varied with a variation in the volume of the mixing chamber as a result. Dilution of the suspension sample may be carried out to give it a suitable concentration level with the aid of the variation in volume of the mixing chamber 35 between the housing 4 and end member 23. The intention with the dilution is to arrive at a concentration level in the sample where the pulp flocking properties, are reduced, and also to facilitate separation of smaller fibre fragments.
• the pulp sample With higher concentrations the pulp sample is usually -heavily flocked, which affects the measurement procedure, since waterways are formed between the flocks, causing th measuring water to flow in the waterways between the flock and in turn cause an unsteady output signal, which may giv a faulty measuring result.
• the measuring result is considerably improved when the pulp is diluted down to abo 0,8% or lower, with the aid of a mixing and dilution chamb of appropriate volume.
• a mixing or agitating propeller 36 in the mixing chamber 35 for mixing during the dilution of t sample to the desired concentration and also for achieving sufficient turbulence for taking away the fine fraction there is a mixing or agitating propeller 36 in the mixing chamber 35, the propeller being driven by a motor 37.
• the revolutionary speed of the motor and the implementation of the propeller 36 are such that during the simultaneous introduction of measuring water at a suitable pressure such large shearing forces may be achieved at the screening plat 22 that a pulp plug is not formed. Short fibre fragments ca thus be separated by passing through the perforations in th screening plate 22.
• the measuring prodedure in accordance with the present invention and using the equipment described hereinbefore, when the suspension sample has a pulp concentration of abou 1-10%, or when measurement of the drainability properties o the entire pulp as well as those of the long fibre content takes place, is performed in the following manner: A. Sampling
• the pneumatic cylinder 8 is activated so that the sampling piston 5 is thrust into the pipe 2 simultaneously as the outflow control valve 30 under the measuring glass 26 and outlet valve 18 are open and the flushing water valve 29, measuring water valve 16 and dewatering valve 25 under the screening plate 22 are closed.
• the mixing chamber 35 which also serves as a measure chamber, is filled with water to the bottom edge of the piston 5.
• Supe fluous water runs out through a vent 38 in the outer end portion of the housing 4.
• the smaller fibre fragments and fine material are separate by the valves being put into the operational state as in item C while the propeller 36 is still activated. There ar thus obtained sufficiently large shearing forces to preven the formation of a fibre bed.
• the perforations in the screening plate 22 therefore allow passage of fine materia which is thus removed from the sample.
• Measurement Measurement according to item D is carried out on the samp impoverished of fine material.
• the pressure can be varied, if so required and a new measurement carried out at a different pressure.
• This measurement can be carried out with or without an intermediate slushing according to item E.
• the measuring values now obtained are subsequently compared with the measuring value or values obtained according to item D to determine the content of fine fraction in the pulp suspension.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biochemistry (AREA)
• Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Hydrology & Water Resources (AREA)
• Dispersion Chemistry (AREA)
• Sampling And Sample Adjustment (AREA)
• Paper (AREA)

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Family Applications (1)

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Citations (6)

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• 1983
  • 1983-05-11 SE SE8302719A patent/SE436602B/sv not_active IP Right Cessation
• 1984
  • 1984-05-11 DE DE8484902108T patent/DE3482056D1/de not_active Expired - Lifetime
  • 1984-05-11 US US06/694,389 patent/US4635470A/en not_active Expired - Lifetime
  • 1984-05-11 EP EP84902108A patent/EP0168403B1/en not_active Expired
  • 1984-05-11 WO PCT/SE1984/000177 patent/WO1984004591A1/en not_active Ceased
  • 1984-05-11 JP JP59502018A patent/JPS60501270A/ja active Granted
• 1985
  • 1985-06-10 FI FI852310A patent/FI81912C/fi not_active IP Right Cessation

Patent Citations (6)

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