Measuring and testing – Sampler – sample handling – etc. – Withdrawing through conduit or receptacle wall
Patent
1996-08-05
1998-05-19
Williams, Hezron E.
Measuring and testing
Sampler, sample handling, etc.
Withdrawing through conduit or receptacle wall
7386381, 7386481, 73 6456, G01N 110
Patent
active
057538301
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and system for continuous sampling of material mixtures for the purpose of analyzing same. Examples of such material mixtures are particles contained in a liquid, such as fiber suspensions, such as papermaking pulps. The present invention, however, can also be applied to other mixtures of particles, liquids and gases. The sampling can be carried out from a space, for example a conveying pipe, or from a tank holding the material mixture.
BACKGROUND OF THE INVENTION
During analysis of the properties of papermaking pulp it is normally of great importance to obtain accurate measuring results, thus requiring that the concentration be both constant and known. Examples of such properties which are to be analyzed are the content of various impurities, the shives content, dewatering capacity (freeness), and fiber appearance and properties.
Certain analytical methods require very low concentrations compared with the normal pulp concentration in the process. One example thereof is image analysis of fiber properties, where the dilution demand can be 1:1000 or even higher.
During continuous sampling this has made it necessary to employ very long conveying times thereby delaying the measuring results or requiring a large consumption of clean dilution water. One method of successfully dealing with these problems would be to reduce the pipe diameter in the sampling equipment. This possibility, however, is restricted by the risk of plugging, especially when both the concentration and the dilution demand are high at the same time.
Additional problems arise due to the fact that the sample taken, besides being diluted, must also be mixed to a uniform concentration before it can be analyzed.
SUMMARY OF THE INVENTION
In accordance with the present invention, these and other problems have now been solved by the invention of a method for sampling a mixture of flowable materials which comprises tapping a minor portion of the mixture, circulating the tapped portion of the mixture continuously through a circuit, diluting the circulating tapped portion of the mixture in order to dilute the tapped portion to provide a diluted stream having a predetermined concentration, and recycling a portion of the diluted stream to the mixture of flowable materials.
In accordance with one embodiment of the method of the present invention, recycling of a portion of the diluted stream comprises adjustably recycling the predetermined portion of the diluted stream to the mixture of flowable materials.
In accordance with another embodiment of the method of the present invention, the method includes continuously measuring the predetermined concentration and controlling the diluting of the circulating tapped portion of the mixture based thereon.
In accordance with the apparatus of the present invention, apparatus is provided for sampling a mixture of flowable materials comprising a sample receiving tap for tapping a minor portion of the mixture, a circuit for continuously circulating the tapped portion of the mixture from the sample receiving tap to an exit point associated with the sample receiving tap, a pump for pumping the tapped portion of the mixture through the circuit, and dilution feed means for controllably feeding a dilution liquid into in order to dilute the tapped portion of the mixture to provide a diluted stream having a predetermined concentration at the exit point.
In accordance with one embodiment of the apparatus of the present invention, the apparatus includes a sample analyzer for analyzing the diluted stream in the circuit.
In accordance with another embodiment of the apparatus of the present invention, the exit point is adjustably located with respect to the sample receiving tap.
In accordance with another embodiment of the apparatus of the present invention, the apparatus includes valve means in the circuit for controlling the flow of the tapped portion of the mixture in the circuit.
In accordance with the present invention, a solution is provided to the above-
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Fayyaz Nashmiya
Sunds Defibrator Industries AB
Williams Hezron E.
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