Volume SH 7: Part
1 On-line Level Measurement Techniques
This part outlines the
techniques available for level measurement in the process
industries and relates to all aspects of material state.
The appendices give a ready guide to potential users
as to the sources of manufacturers and more relevant
applications in wet solids handling. The survey has
been restricted to those sources which can give a remote
signal output, whether electrical or pneumatic, rather
than local visual indication only. The part is being
updated to include suppliers’ details and products
offered in North America and Europe.
Volume SH 7: Part
2 On-line Viscosity and other Rheological Techniques
This part
describes the various types of commercially-available
(and obsolete) on-line instruments to measure viscosity
or consistency. The term consistency is used when an
instrument is unable to measure absolute viscosity.
A brief description of each viscometer type together
with its advantages, limitations and application areas
is given. Although more generally used with polymers,
on-line rheometers, as distinct from viscometers, which
measure rheological properties other than viscosity
(e.g., complex dynamic viscosity and normal stress)
are also described. This was done as the rheological
property in question may be more sensitive to changes
in, for instance, slurry composition. An overview of
the different on-line instruments which have been built
in-house is also given.
Factors
influencing viscometer selection such as operating temperature,
operating pressure, flow condition at the required measuring
point, and shear rate range to be covered by the instrument
are discussed.
Despite
the wide instrument availability, industrial application
of on-line viscosity and rheological measurement for
process control is not as widespread as expected. This
report outlines the fundamental reasons for this and
discusses how this problem might be addressed. Some
case studies on the successful application of on-line
viscometers/rheometers in slurry/paste service are described.
Volume SH 7: Part
3 Slurry Flowmeters
The
objective of this part is to guide a potential user
in the selection installation and operation of flowmeters
for dirty liquid and slurry applications and to provide
sufficient information for the user to carry out fruitful
discussions with manufacturers. The selection procedure
is illustrated by a flow chart and is both simple and
flexible. The report has been designed in such a way
that it provides a comprehensive guide for the user
who is unfamiliar with flowmeters as well as a fast
selection procedure, condensed to a few pages, for the
experienced engineer.
Volume SH 7: Part
4 On-line Densitometers
This part covers gravimetric
methods, radiometric absorption, vibrating tube techniques,
Coriolis force mass flowmeters, and, in the case of
coarse particle settling slurries, the counter flowmeter
or "U-loop". In addition, to direct measurement
of slurry density on-line, there are several inferential
techniques for moisture content in slurries, including
the use of electrical conductivity and capacitance,
optical methods, ultrasonic techniques, viscometric
methods, and the adaptation of specific designs of volumetric
flowmeters.
Volume SH 7: Part
5 Selection of On-line Viscometers
This part
provides a coherent logical methodology to selecting
an on-line viscometer for a slurry/paste application.
Guidance on the installation and operation of on-line
viscometers is also given. The report is based on Part
2 and information derived from viscometer users and
suppliers. The first four sections provide a brief guide
to the various types of on-line viscometers that are
commercially available and deals with the key parameters
governing the viscometer selection process. Section
5 provide the methodology, including flow charts, for
obtaining a shortlist of suitable on-line viscometers
for the application under consideration. Section 6 gives
some guidance on the discussions that should take place
with the potential supplier(s) of the shortlisted viscometers.
Section 7 outlines the various considerations for viscometer
installation and operation. Section 8 describes the
trials that should be taken to confirm the viscometer
selection. Section 9 gives a worked example on the use
of this guide. Appendix A gives the viscometer specification
data sheet to be used in conjunction with Section 5.
Appendix B is a comprehensive listing of suppliers of
commercial on-line viscometers/rheometers together with
address, telephone and facsimile details.
Volume SH 7: Part
6 Selection Guide for Level Measurement
This part will provide
a selection guide based on the updated survey of level
measurement methods outlined in Part 1
Volume SH 7: Part
7 Passive Acoustic Emission Monitoring applied to Slurry
Systems
This part
reviews the potential of the technique of monitoring
industrial processes using acoustics. This is a proven
and extremely powerful measurement technique. In particular
systems based upon the interpretation of much higher
frequency structure borne acoustic emissions (AE) at
typically 50 kHz to 1 MHz can offer numerous advantages
over conventional techniques, often offering totally
unique monitoring opportunities.
The monitoring
of process conditions using AE is not new. The use of
acoustic emissions to monitor chemical reactions dates
back 15 years, whilst the interpretation of AE measurements
using advanced pattern recognition methods has been
successfully used for over 8 years. However, with the
advancement of the power of the common PC, the use of
AE data for industrial monitoring applications is becoming
increasingly viable, with an increasing number of commercial
systems now on the market and many more research and
development applications currently being considered.
It is widely
accepted that for many monitoring applications, the
AE technique can offer many advantages over conventional
instrumentation. For many users, the most advantageous
feature of passive AE monitoring is the truly non-invasive
clamp-on nature of the instrumentation, enabling externally
applied sensors to ‘listen’ to process conditions
occurring within non-accessible plant and machinery.
Another
main advantage is the potential of the calibrated AE
system to replace difficult periodic manual sampling
operations with continuous process monitoring capabilities,
thereby offering obvious benefits in terms of system
optimisation.
Other advantages
are afforded in supervisory monitoring applications,
where the simplest AE system can be used to detect a
change from a desired steady state condition, thereby
drawing attention to a potential problem and alerting
an operator to provide the necessary intelligence to
be able to diagnose any process problems. For example,
a continuous steady state process may be adversely affected
by unwanted variations in any of a number of parameters,
including:
- Material composition
- Flowrates
- Particle size distributions
- Density changes
- Temperature
- Pressure etc.
On the
other hand, a non-intelligent AE system could simply
detect that something significant had changed because
the process now sounded ‘different’.
This state
of the art review details the current practice of Acoustic
Emission (AE) monitoring and provides a brief outline
of the wide range of possible applications in order
to highlight the tremendous capabilities of the technique,
particularly for slurry monitoring applications.
In the
near future, it is expected that the use of passive
acoustic emission will become much more widespread as
the results of the numerous current ongoing evaluations
produce real process monitoring successes and in so
doing, draw further attention to the method whilst also
revealing the most suitable applications for this technique.
At this stage it is likely that the form of the AE monitoring
instrumentation will also change, to become less like
general purpose evaluation equipment and to evolve into
more dedicated products targeting specific process applications.
