Measuring and testing – Sampler – sample handling – etc. – Flow divider – deflector – or interceptor
Reexamination Certificate
1999-02-05
2001-06-12
Raevis, Robert (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
Flow divider, deflector, or interceptor
C073S864810
Reexamination Certificate
active
06244118
ABSTRACT:
The present invention relates to an apparatus for and a method of sampling material in a process system, in particular the on-line sampling of a flow of a liquid or powder.
Traditionally, a sample of material would have been removed during processing from a process system and then analyzed. It will be appreciated that techniques requiring the removal of material from a process system for separate analysis are both labor-intensive and time consuming.
More recently, techniques have been developed which allow material to be analyzed on-line. WO-A-96/12174 discloses an apparatus for the on-line analysis of material in a process system, specifically a reaction vessel. This apparatus comprises a probe, which is located in the reaction vessel and includes a chamber having openings through which material continuously passes, and optical measurement means for analyzing the material passing through the chamber. WO-A-96/24835 discloses an apparatus for the on-line analysis of material in a process system, specifically a tubular section. This apparatus comprises a tube having opposed transparent windows, a light source adjacent one window and a photo-detector adjacent the other window, whereby the composition of the material passing the windows is determined by the signals generated by the photo-detector. Whilst these on-line techniques are less labor-intensive and allow for a more rapid analysis of material, such techniques still exhibit a number of problems. Notably, where a probe is used to analyze a flow of material, it is often difficult to locate the probe in a region of the material which flows continuously and steadily. In fact, it is commonly found that the probe will be located in a region of the material which has a pulsed flow or is indeed stationary. It is also difficult to ensure that the probe is continuously surrounded by fresh material so that the on-going measurement is truly representative of the entire bulk of material. For many reasons, in these prior art techniques the same material can remain next to the probe which leads to the analysis throughout the process cycle as characterizing the entire bulk of material as having the same composition when in fact the position could be quite different.
It is thus a general aim of the present invention to provide an apparatus for and a method of periodically sampling material on-line which is representative of the entire bulk of material from which samples are taken.
It is a particular aim of the present invention to provide a sampling apparatus which ensures a stable interface between the material to be sampled and the measuring device. Where a flow of material is to be sampled, it is desirable to present a stationary sample to the measuring device.
A further aim of the present invention is to provide a sampling apparatus which allows material to be sampled and replaced with new material in a quick and efficient manner.
Accordingly, the present invention provides an apparatus for use in sampling material on-line in a process system, comprising: a sample collector including an upwardly-facing wall member of fixed position on which a sample of material is in use collected; a measuring device for talking measurements from a collected sample; and sample displacing means for displacing the collected sample from the sample collector so that the sample collector can receive a new sample of material. In preferred embodiments the process system is one of a process vessel or a tubular section.
By virtue of the configuration of the sampling apparatus of the present invention, a relatively simple construction is provided which avoids the need to remove material from the process system and allows for a stationary sample to be presented to the measuring device. The construction also allows for a collected sample from which measurements have been taken to be replaced both simply and rapidly. In addition, the configuration of the sampling apparatus of the present invention is such that it is in effect self-cleaning, thereby minimizing the down-time of the process system from which material is being sampled. Moreover, the sampling apparatus of the present invention allows for the use of any kind of measuring device which utilizes electromagnetic radiation.
In one embodiment the sample displacing means comprises a pressurized gas supply which in use is actuated to displace the collected sample.
As will be appreciated, this embodiment of the sampling apparatus of the present invention exhibits the particular advantage that sampling is achieved without requiring any moving parts or requiring the apparatus to introduce components into the material to be sampled which are electrically operated, thereby minimizing the risk of an explosion.
Preferably, the measuring device is non-destructive or partially destructive.
In one embodiment the measuring device is a spectroscopic measuring device and can be a reflectance, transflectance or transmission device. Preferably, the spectroscopic measuring device is one of an emission, absorbtion or scattering device. In preferred embodiments the spectroscopic measuring device is an x-ray spectrophotometer, an ultra-violet (UV) spectrophotometer, a visible (VIS) spectrophotometer, an infra-red (IR) spectrophotometer, a near infra-red (NIR) spectrophotometer, a raman spectrophotometer, a microwave spectrophotometer or a nuclear magnetic resonance (NMR) spectrophotometer.
In another embodiment the measuring device is a polarimeter.
In a preferred embodiment the measuring device includes a measurement probe and the sample collector is attached to the distal end of the measurement probe such as to be movable within the process system. This configuration is particularly useful when representative samples are not to be found adjacent the wall of a process system or if homogeneity is to be monitored at different locations within a process system.
In a preferred embodiment the sample collector is connected to a heating/cooling means so as to provide for temperature stabilization of the sample collector. Temperature stabilization can provide more reliable measurements where the measuring device is sensitive to variations in temperature or where, for example, the material to be sampled is a liquid which tends to boil, with the gas bubbles generated adversely affecting the measurement
The present invention also provides a method of sampling material on-line in a process system, comprising the steps of: collecting a sample of material in a sample collector, the sample collector including an upwardly-facing wall member of fixed position on which a sample of material is collected; taking measurements from the collected sample; and displacing the collected sample from the sample collector.
In a preferred embodiment the collected sample is displaced from the sample collector using a pressurized gas supply.
The present invention finds particular application in monitoring the characteristics, for example compositional changes, of pharmaceutical compositions typically in the form of powders, granules, pellets and tablets during preparation in fluidized beds. However, it will be appreciated that the present invention can equally be applied to other processes within the pharmaceutical industry, and indeed in non-pharmaceutical processes. Other processes to which the present invention can be applied are typically blender systems, powder transport devices, spray granulators, spray dryers and mixing/separation systems.
REFERENCES:
patent: 4640614 (1987-02-01), Roberts et al.
patent: 5750996 (1998-05-01), Drennen, III et al.
patent: 5992245 (1999-11-01), Takei et al.
patent: 3444013 (1985-06-01), None
patent: 0724145 (1996-07-01), None
patent: WO89/10548 (1989-11-01), None
patent: WO93/23731 (1993-05-01), None
patent: WO96/09528 (1996-03-01), None
patent: WO96/12174 (1996-04-01), None
patent: WO96/24835 (1996-08-01), None
patent: WO99/32872 (1999-01-01), None
Andersson Martin
Björn Ingela N
Folestad Staffan
Astrazeneca AB
Raevis Robert
White & Case LLP
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