Patent Application: US-201314063808-A

Abstract:
a rheometer for measuring non - newtonian fluids is disclosed . the rheometer includes capillaries with piezometers therein , a pump , flow control valves , flow , density , and speed meters , and a controller . the rheometer has application in providing for online measurements of parameters including viscosity and yield stress in mining suspensions based upon laminar transportation of the suspensions by the capillaries .

Description:
a preferred embodiment of this invention consists of a box ( 1 ) containing a suspension , a very small part of this suspension is diverted to the rheometer by means of a positive displacement pump ( 2 ). connected to the pump outlet ( 2 ) is a distribution piece ( 5 ) which powers three vertical capillaries ( 6 ) of different diameters , the power is given alternately to each of the capillaries , that is , the three capillaries ( 6 ) are not measured simultaneously . in each of the three capillaries ( 6 ) six piezometers ( 7 ) are installed in pairs and at three different heights in the capillary in order to have redundancy . three capillaries ( 6 ) of different diameter are used , to have a greater number of points on the rheological curve . between the positive displacement pump ( 2 ) and the distribution piece ( 5 ), a density meter ( 4 ) and a flow meter ( 3 ) are installed to measure density and flow of the fluid sample to be measured before reaching the piezometers ( 7 ). the capillaries outlet can be connected directly to the box ( 1 ) or other receptacle . once the measurement at each capillary is finished , these are purged with a cleaning system ( 15 ) and exhaust valves ( 14 ) to prevent particulate matter accumulation on the walls of capillaries . in each of the capillaries , the suspension speed ( v ( r )) is measured , ( 13 ) using for such purpose instruments such as sonar , ultrasound ( mapping of upd ultrasonic pulses and usv spectroscopy ), nuclear magnetic resonance ( nmr ), and nmr images ( nmri ). with the pressure drop data measured with the piezometers ( 8 ) plus density and flow , viscosity ( μ ) and yield stress ( τ o ) can be determined from an analysis algorithm specially designed for the extraction of information and analysis described below . the invention includes a microcontroller ( 9 ) which controls the components of the rheometer , collects data , and executes their processing , calculating the values of rheological variables and performing due corrections to the phenomena associated to complex suspensions ( entrance effects , wall effects , and temporary effects ), the microcontroller ( 9 ) is in the electrical house of the equipment and usually very close to it . the data obtained by this microcontroller ( 9 ) are sent by cable or wirelessly to the house where a server ( 10 ) is found , which processes the data for the management and administration of the operation variables . angular deformation speed ( end point ), stress , viscosity , and yield stress are calculated on the microcontroller , which has a software that controls the duration of the measurement , cleaning of the capillary ( 6 ) of a certain radius r , and the opening and closing of valves ( 12 ) ( 14 ) and ( 15 ) of the capillaries ( 6 ). the information obtained will be stored in a historical database ( 11 ) of the operation installed on a server ( 10 ). historical data can be analyzed through a platform for such purpose , and deployment of online information can be incorporated into flowcharts ( flowsheet ) of the operation as another parameter . the database in the server stores historical data for statistical and trend analysis in different periods ( hours , shifts , days , months , etc . ), and these data are displayed in trend curves with warning criteria in cases of unexpected variations . the server ( 10 ) may be accessed from the control room of the operation , and by any authorized network user . measurement will be performed alternately in each capillary ( 6 ). measurement of flow and density will be continuous . before starting the operation , representative samples are taken for laboratory analysis on rheology , granulometry or any other relevant parameter . as mentioned above , the proposed rheometer , and the information obtained by it , works in conjunction with an analysis algorithm to finally obtain the viscosity values ( μ ) and the yield stress ( τo ). the analysis algorithm includes all necessary corrections to remove parasitic effects . in general , these effects will be calibrated depending on the quality of the suspension . the method for the use of the algorithm described , using the rheometer and explained based on fig3 showing one of the capillaries , involves : at three different heights of each of the capillaries ( 6 ) groups are arranged with two piezometers ( pz k1 , pz red k1 ), ( pz k2 , pz red k2 ), ( pz k3 , pz red k3 ), the second piezometer of each group ( superscript red ) is used should the other fail . the index k indicates the kth capillary . b ) in each group of two piezometers ( pz k1 , pz red k1 ), ( pz k2 , pz red k2 ), ( pz k3 , pz red k3 ), a pressure measurement will be obtained ( p 1k , p red 1k ), ( p 2k , p red 2k ), ( p 3k , p red 3k ) using only one of each pair . the subscript k indicates the capillary and red indicates redundancy . c ) in each capillary there will be six measurements on pressure differences ( δp 12k , δp 23k , δp 31k ) and ( δp red 12k , δp red 23k , δp red 31k ). the superscript red indicates a measurement of redundancy and the subscript k indicates the capillary . d ) distances between each group of two piezometers are known ( pz k1 , pz red k1 ), ( pz k2 , pz red k2 ), ( pz k3 , pz red k3 ), which are called δl 1 , δl 2 and δl 3 , in general , for the three capillaries , these distances will be δl 1k , δl 2k and δl 3k , where k indicates the capillary , 1 indicates the distance between pz k1 and pz k2 , 2 indicates the distance between pz k2 and pz k3 , and 3 indicates the distance between pz k3 and pz k1 of capillary k . e ) with pressure values measured in the three groups of two piezometers ( pz k1 , pz red k1 ), ( pz k2 , pz red k2 ), ( pz k3 , pz red k3 ) and the distances between them δl 1k , δl 2k and δl 3k , pressure gradients are calculated for each pair of piezometers of the capillaries : where p ′ ijk corresponds to the pressure gradient of capillary k between piezometers j and i . f ) with element v ( r ), speed profile v ( r ) is measured , this measurement is used to correct the flow rate due to wall effects . g ) pressure corrections are made for entrance effects and wall sliding where δp e is the pressure drop for entrance effects , δp p measured by piezometers , and q p is the flow modification for wall effects . h ) now shear stresses are calculated using the corresponding diameter and pressure gradients i ) average speed is calculated , with the flow rates and diameter m ) valve of capillary 2 is opened , and then valve of capillary 1 is closed and capillaries 1 and 3 are purged . n ) steps a ) to l ) are carried out for capillary 2 . o ) valve of capillary 3 is opened , then valve of capillary 2 is closed and capillary 2 is purged . p ) steps a ) to l ) are carried out for capillary 3 . q ) with this new amount of data , entrance and wall effects are rechecked and a new apparent rheogram is calculated . r ) data are displayed in trend curves , with warning criteria in cases of unexpected variations . s ) a statistical analysis is performed of the control period ( hours , shift , week , months , years ). d . bonn & amp ; m . m . denn , 2009 , science 324 , 12 jun . 2009 h . yamaguchi , 2008 , “ fluid mechanics and its applications ”, volume 85 , springer science + business media b . v . y . y . hou & amp ; h . o . kassim , 2005 , rev . sci , instrum . 76 , 101101 . j . mewis & amp ; n . j . wagner , 2009 , advances in colloid and interface science 147 - 448 . s . k . kawatra & amp ; a . k . bakshi , 1998 ; min . & amp ; metall proc . 15 ( 4 ), november z . y . wang et al ., 2010 , alche journal , 56 ( 6 ), june . s . h . chiu et al . 1999 , polymer degradation and stability , 64 ( 2 ), pages 239 - 242 q . d . nguyen et al ., 2000 , min . pro . err . met . rev . 20 . pp . 75 - 91 di 1 : us2002088953 ; dual riser / dual capillary viscometer for newtonian and non - newtonian fluids , kennet kensey et al , di 2 : us6182503 ; on - line 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