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1521 views
09:01 Nov-04-1998
Arturo Macchi
Feasibility of ultrasonic NDT in a gas-liquid-solid fluidized bed

Hello!

My name is Arturo Macchi. I'm presently completing my Ph.D. at the University of British Columbia in
the department of Chemical Engineering. My Ph.D project is in the area of gas-liquid-solid fluidization.

The fluidized bed reactor contains a bed of particles which are fluidized (put in suspension) by
an upward flow of gas and liquid.

The experimental setup (gas-liquid-solid fluidized bed) is as follows:

· The column is made of acrylic: Outer Diameter = 12 inches, Inner Diameter = 11.5 inches,
Height = 72 inches.

· Liquid used: Glycerol-water solution;

· Gas used: Air;

· Solid used: Aluminum cylinders; diameter = 4 mm, length = 10 mm, density = 2790 kg/m3

· Operating conditions: Temperature = 20°C
Pressure = 1 atmosphere

It is important to mention that no reaction is taking place. I'm only interested in the flow
patterns (hydrodynamics) of the gas, solids and liquid.


I would like to use ultrasonic NDT to measure the concentration of bubbles and particles over the reactor
cross-section in a non-intrusive manner. The liquid is the continuous phase, while the gas bubbles and
solids are the dispersed phases. The solids and gas volumetric concentrations (holdups) are obtained
by measuring the transmission time difference and the attenuation (loss of intensity or amplitude) of an
ultrasonic pulse wave transmitted through the system with and without bubbles and particles.

The transducers can be placed at opposite sides just inside the column wall. The ultrasonic signal
would then have to travel over a distance of 11.5 inches. The ultrasonic NDT system would operate
in a through transmission mode. The information (time of flight, intensity) from the first signal only will
be used to determine the gas and solids holdups. The first signal corresponds to the strait path between
the transducers, while the other signals correpond to refractions and reflections. The speed of the data
acquisition does not have to be very quick (in the order of 10 to 100 Hz). The flow patterns are dynamic
in nature and I will be using the average of many signals sent of a certain time.

In our system, we expect the attenuation (scattering) of the ultrasonic pulse to be very high and a
potential limitation of the measuring technique. The fluidized bed runs at about 30 % solids holdup
and 20 % gas holdup. The bubbles are around 4 mm in diameter. Pevious researchers, have succesfully
performed similar experiments with much lower solids and gas holdups, 5% and 10 %, respectively. The
solid particles were also much smaller, in the order of 100 microns. They used transducers that
generate pulses in the order of 1 to 10 MHz. I would like to use transducers with a nominal frequency of
0.5 MHz with a very large bandwidth a very small pulse width.

In summary, the important question here is: "Is this measuring technique and the approach I described
feasible for our operating conditions?" If so, which companies can be of service and what type of NDT
equipment can be used.


Thank you for your time and effort!

Sincerely,

Arturo Macchi

P.S. Let me know if there are any ambiguities or anything missing in the information I provided.



 
05:37 Nov-04-1998

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
Re: Feasibility of ultrasonic NDT in a gas-liquid-solid fluidized bed

: In summary, the important question here is: "Is this measuring technique and the approach I described
: feasible for our operating conditions?" If so, which companies can be of service and what type of NDT
: equipment can be used.

I think you're on the right track in terms of using a low frequency through transmission approach, although as you have observed, this liquid/solid/gas medium is going to be extremely scattering. The center frequency wavelength of a 500 KHz broadband transducer will be about 3 mm in water, so your 4 mm bubbles and particles will be a major factor. This is the sort of research project where you won't know how well it will work until you try it. However, commercial NDT transducers are available down to at least 50 KHz (from us, and other companies as well), and at some low enough frequency you'll eventually blast through the complex medium. I'd suggest starting at 500 KHz and working downward until you see a useable signal. Low frequency, high gain pulser/receivers are also available.

One warning: at the very low frequencies and high gain levels that will be used here, you will see fairly significant wraparound wave components travelling circumferentially through the pipe wall if the transducers are coupled into the pipe. This noise could well be *much* higher in amplitude than the direct signal through the liquid. At the very least, you will have to cut a hole in the pipe so that transducer face is in contact with the liquid. It may also be necessary to put a wrap of blown foam or some similar acoustic insulator around the body of the transducer to eliminate unwanted coupling.

Good luck!

Tom Nelligan
Senior Applications Engineer, Panametrics, Inc.
http://www.panametrics.com


 
08:18 Nov-15-1998
qwert
Re: Feasibility of ultrasonic NDT in a gas-liquid-solid fluidized bed n the flow
: patterns (hydrodynamics) of the gas, solids and liquid.

:
: I would like to use ultrasonic NDT to measure the concentration of bubbles and particles over the reactor
: cross-section in a non-intrusive manner. The liquid is the continuous phase, while the gas bubbles and
: solids are the dispersed phases. The solids and gas volumetric concentrations (holdups) are obtained
: by measuring the transmission time difference and the attenuation (loss of intensity or amplitude) of an
: ultrasonic pulse wave transmitted through the system with and without bubbles and particles.

: The transducers can be placed at opposite sides just inside the column wall. The ultrasonic signal
: would then have to travel over a distance of 11.5 inches. The ultrasonic NDT system would operate
: in a through transmission mode. The information (time of flight, intensity) from the first signal only will
: be used to determine the gas and solids holdups. The first signal corresponds to the strait path between
: the transducers, while the other signals correpond to refractions and reflections. The speed of the data
: acquisition does not have to be very quick (in the order of 10 to 100 Hz). The flow patterns are dynamic
: in nature and I will be using the average of many signals sent of a certain time.
:
: In our system, we expect the attenuation (scattering) of the ultrasonic pulse to be very high and a
: potential limitation of the measuring technique. The fluidized bed runs at about 30 % solids holdup
: and 20 % gas holdup. The bubbles are around 4 mm in diameter. Pevious researchers, have succesfully
: performed similar experiments with much lower solids and gas holdups, 5% and 10 %, respectively. The
: solid particles were also much smaller, in the order of 100 microns. They used transducers that
: generate pulses in the order of 1 to 10 MHz. I would like to use transducers with a nominal frequency of
: 0.5 MHz with a very large bandwidth a verysmall pulse width.

: In summary, the important question here is: "Is this measuring technique and the approach I described
: feasible for our operating conditions?" If so, which companies can be of service and what type of NDT
: equipment can be used.

:
: Thank you for your time and effort!

: Sincerely,

: Arturo Macchi

: P.S. Let me know if there are any ambiguities or anything missing in the information I provided.




 
02:58 Nov-16-1998

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1197
Re: Feasibility of ultrasonic NDT in a gas-liquid-solid fluidized bed mm, length = 10 mm, density = 2790 kg/m3

: · Operating conditions: Temperature = 20°C
: Pressure = 1 atmosphere
:
: It is important to mention that no reaction is taking place. I'm only interested in the flow
: patterns (hydrodynamics) of the gas, solids and liquid.

:
: I would like to use ultrasonic NDT to measure the concentration of bubbles and particles over the reactor
: cross-section in a non-intrusive manner. The liquid is the continuous phase, while the gas bubbles and
: solids are the dispersed phases. The solids and gas volumetric concentrations (holdups) are obtained
: by measuring the transmission time difference and the attenuation (loss of intensity or amplitude) of an
: ultrasonic pulse wave transmitted through the system with and without bubbles and particles.

: The transducers can be placed at opposite sides just inside the column wall. The ultrasonic signal
: would then have to travel over a distance of 11.5 inches. The ultrasonic NDT system would operate
: in a through transmission mode. The information (time of flight, intensity) from the first signal only will
: be used to determine the gas and solids holdups. The first signal corresponds to the strait path between
: the transducers, while the other signals correpond to refractions and reflections. The speed of the data
: acquisition does not have to be very quick (in the order of 10 to 100 Hz). The flow patterns are dynamic
: in nature and I will be using the average of many signals sent of a certain time.
:
: In our system, we expect the attenuation (scattering) of the ultrasonic pulse to be very high and a
: potential limitation of the measuring technique. The fluidized bed runs at about 30 % solids holdup
: and 20 % gas holdup. The bubbles are around 4 mm in diameter. Pevious researchers, have succesfully
: performed similar experiments with much lower solids and gas holdups, 5% and 10 %, respectively. The
: solid particles were also much smaller, in the order of 100 microns. They used transducers that
: generate pulses in the order of 1 to 10 MHz. I would like to use transducers with a nominal frequency of
: 0.5 MHz with a very large bandwidth a very small pulse width.

: In summary, the important question here is: "Is this measuring technique and the approach I described
: feasible for our operating conditions?" If so, which companies can be of service and what type of NDT
: equipment can be used.

:
: Thank you for your time and effort!

: Sincerely,

: Arturo Macchi

: P.S. Let me know if there are any ambiguities or anything missing in the information I provided.




 
02:08 Feb-12-1999
Josseline Macchi
My name is Josseline Macchi
: Hello!

: My name is Josseline Macchi. I leave in France, at Rambouillet, at 50 kilometers of Paris. I'm searching the family's Macchi of the World. My grand-father Silvio Macchi was born in Swiss in 1888. His mother was born at Campomorone, 15 kilometers of Genova, his father was born at Biumo Superiore, near of Varese, in Italy.
The brother of my grand-father Achille has emigrated in 1920 at Los Angeles.
His work is in the Compagny of trains Amtrak.

I wait your answer.

Sincerely.

Josseline Macchi



 
07:03 Jun-07-2000
Federico Duarte Macchi
Re: My name is Josseline Macchi component. The President name is Luis Angel González Macchi.-

Now my sister and I are currently procured in the Italy Embassy, here in Paraguay, our Italian nationalization and Passport.-

This is all the information that I can get you about our family.

I hope that it could be useful for you.-

Best Personal regards,

Federico Duarte Macchi.-

PS.: Sorry for my bad English. Here in Paraguay our official language is the Spanish.-

My Nickname is Fredo.-


 
02:19 Jul-09-2001
Tony Macchi
Re: My name is Josseline Macchi Hello,

I'm not sure if I'm too late in responding, but my grandfather emigrated to New York in the early 1920s, from his family home in the village of Santa Marguerita near Palermo. He settled near Hartford Connecticut and there is now an extended Macchi family throughout the northeastern U.S. We still have family, including my grandfather's sister and her decendants living in the same village in Sicily.




 
02:33 Jul-09-2001
Joseph Pascente
My name is Josseline Macchi Why are we doing family searches on this forum?


 


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