Dear Amrit,

As I now understand, the iteration is done by adjusting the airflow in the calculation until the desired pickup velocity value is reached.

Thanks

Teus ■

Dear Amrit,

As I now understand, the iteration is done by adjusting the airflow in the calculation until the desired pickup velocity value is reached.

Thanks

Teus ■

hi every body;

i am working in a company that design meltshop and EAF. i am responsible for designing dedusting system. i have a lot of information, but i donot khnow from where i shoul start?

is there anybody that have same experience or knowledge to help me?

i would be so thankful

best pooyool ■

hi every body;

i am working in a company that design meltshop and EAF. i am responsible for designing dedusting system. i have a lot of information, but i donot khnow from where i shoul start?

is there anybody that have same experience or knowledge to help me?

i would be so thankful

best pooyool ■

Hi Mr. Agarwal,,

would you mind sending me a copy of your paper? I would appreciate it.

thanks,

Walker Robbins ■

Hi Mr. Agarwal,,

would you mind sending me a copy of your paper? I would appreciate it.

thanks,

Walker Robbins ■

Thanks to Mr. Amrit T. Agarwal for sending me a copy of the article.

I found it interesting and comprehensive article, it is well organized and very clearly explicate.

I'm taking now with the generation of my spreadsheets which will immediately be compared with data realiche I pitch, I will follow my post some more detailed consideration in this regard.

Regards.

------------------------------------------------------------------------------------------------------

Oliva Renato

Technical Office VIBA S.p.A. plastic chemical ■

Thanks to Mr. Amrit T. Agarwal for sending me a copy of the article.

I found it interesting and comprehensive article, it is well organized and very clearly explicate.

I'm taking now with the generation of my spreadsheets which will immediately be compared with data realiche I pitch, I will follow my post some more detailed consideration in this regard.

Regards.

------------------------------------------------------------------------------------------------------

Oliva Renato

Technical Office VIBA S.p.A. plastic chemical ■

Dear Amrit Agarwal

Thank you for sending me the article on "Theory and Design of Dilute

Phase Pneumatic Conveying Systems".

The method presented is a practical approach and I highly recommend it to any person seeking information on the design of dilute phase systems.

Best Regards,

Wannawuth T.

Wellroll Co., Ltd. ■

Dear Amrit Agarwal

Thank you for sending me the article on "Theory and Design of Dilute

Phase Pneumatic Conveying Systems".

The method presented is a practical approach and I highly recommend it to any person seeking information on the design of dilute phase systems.

Best Regards,

Wannawuth T.

Wellroll Co., Ltd. ■

Dear amrit sir

i was discussing with Mr TEUS

He sugested me to take a copy of the artical published by you

i am very much interested to study it

if you can give me a copy of that

waiting

Regards

Manthan Kothari. ■

Dear amrit sir

i was discussing with Mr TEUS

He sugested me to take a copy of the artical published by you

i am very much interested to study it

if you can give me a copy of that

waiting

Regards

Manthan Kothari. ■

Dear Mr Agarwal,

Thanks so much for the excellent article on pneumatic conveying. It is quite thorough and informative and will certainly help me in designing some transport systems.

Best regards,

Tom H

May, 2010 ■

Dear Mr Agarwal,

Thanks so much for the excellent article on pneumatic conveying. It is quite thorough and informative and will certainly help me in designing some transport systems.

Best regards,

Tom H

May, 2010 ■

Dear Dr. Agarwal

Thank you very much for sending me the article. It is very clear and informative. I have seen similar articles, but yours is by far the best.

In case you plan to write a similar article anytime, it would be nice to have some approximate data on pressure losses through feeding devices. That's something I haven't been able to find anywhere.

Regards,

Gustavo Sosa

gussosa@rontil.com

Mechanical Engineer

RONTIL S.A.

Montevideo, Uruguay ■

Dear Dr. Agarwal

Thank you very much for sending me the article. It is very clear and informative. I have seen similar articles, but yours is by far the best.

In case you plan to write a similar article anytime, it would be nice to have some approximate data on pressure losses through feeding devices. That's something I haven't been able to find anywhere.

Regards,

Gustavo Sosa

gussosa@rontil.com

Mechanical Engineer

RONTIL S.A.

Montevideo, Uruguay ■

Amrit,

Thanks for sending me the information from your article regarding pneumatic conveying design. I'm sure I will find it helpful.

Scott

WesLor Enterprises, Inc. ■

Amrit,

Thanks for sending me the information from your article regarding pneumatic conveying design. I'm sure I will find it helpful.

Scott

WesLor Enterprises, Inc. ■

Dear Amrit,

Thank you for sharing your paper. It is very clearly written and was a big help for me. If you have any other papers you wrote on the topic of pneumatic conveying I would read them with great interest.

Best regards

dr in. Piotr Weryski

MONTA Sp. z o.o.

Kosiarzy 35, PL-02-953 Warszawa

www.monta.pl ■

Dear Amrit,

Thank you for sharing your paper. It is very clearly written and was a big help for me. If you have any other papers you wrote on the topic of pneumatic conveying I would read them with great interest.

Best regards

dr in. Piotr Weryski

MONTA Sp. z o.o.

Kosiarzy 35, PL-02-953 Warszawa

www.monta.pl ■

dear all:

anyone has the copy of the articles?

could you send me to:zmjjohn@gmail.com

so many thanks and apprixiate. ■

dear all:

anyone has the copy of the articles?

could you send me to:zmjjohn@gmail.com

so many thanks and apprixiate. ■

Dear Amit

Thanks a lot for for ur Article

It is very helpful for me to design conveying system. If u any more information on sugar conveying pl send.

Thanking u

Dinesh Lodha

Email dbl@mbsugars.com ■

Dear Amit

Thanks a lot for for ur Article

It is very helpful for me to design conveying system. If u any more information on sugar conveying pl send.

Thanking u

Dinesh Lodha

Email dbl@mbsugars.com ■

Dear Kjordens,

The subject of the formation of streamers in pneumatic conveying of plastics is indeed a frequently emerging issue.

The assumed causes are many, however, never led to a real solution up till now.

I had the opportunity through this forum to calculate a number of existing plastic pneumatic conveying installations and found such a variety of conveying conditions where the formation of streamers occurred, that it was impossible to discover a correlation.

Many times, the conveying velocity is mentioned as the initiator, however, there were high velocity systems AND low velocity systems that showed the streamers problem.

Calculating the transferred energy into the pellets proved that the temperature rise is so little, that melting cannot be the cause.

The result of the pneumatic calculations made me to consider other phenomena.

Static electricity is a well-known effect in pneumatic conveying of plastics and could probably be a cause for bonding.

I posted my thoughts on the BulkBlog:

https://news.bulk-online.com/pneumat...conveying.html

I can recalculate your installations, if you like.

Have a nice day

Teus ■

Dear Kjordens,

The subject of the formation of streamers in pneumatic conveying of plastics is indeed a frequently emerging issue.

The assumed causes are many, however, never led to a real solution up till now.

I had the opportunity through this forum to calculate a number of existing plastic pneumatic conveying installations and found such a variety of conveying conditions where the formation of streamers occurred, that it was impossible to discover a correlation.

Many times, the conveying velocity is mentioned as the initiator, however, there were high velocity systems AND low velocity systems that showed the streamers problem.

Calculating the transferred energy into the pellets proved that the temperature rise is so little, that melting cannot be the cause.

The result of the pneumatic calculations made me to consider other phenomena.

Static electricity is a well-known effect in pneumatic conveying of plastics and could probably be a cause for bonding.

I posted my thoughts on the BulkBlog:

https://news.bulk-online.com/pneumat...conveying.html

I can recalculate your installations, if you like.

Have a nice day

Teus ■

Dear Amrit,

The summary of influencing conveying- and material parameters does not explain the physical mechanism of the formation of streamers.

As the streamers are monolithic and bigger than the original particles, there must be a way of bonding.

That solids velocity and a smooth pipe wall induce streamers, indicates that friction is responsible.

The theory is that the friction increases the temperature of the pellets up to the melting point and then the particles glue together.

However, I calculated that the temperature increase, due to friction is never high enough to reach that temperature. (Assuming not too high temperatures at the start of the conveying)

How do you explain the physical formation of streamers?

Assuming, you have read my BulkBlog article, I would very much appreciate your valued comments or additions.

Have a nice day

Teus ■

Dear Amrit,

The summary of influencing conveying- and material parameters does not explain the physical mechanism of the formation of streamers.

As the streamers are monolithic and bigger than the original particles, there must be a way of bonding.

That solids velocity and a smooth pipe wall induce streamers, indicates that friction is responsible.

The theory is that the friction increases the temperature of the pellets up to the melting point and then the particles glue together.

However, I calculated that the temperature increase, due to friction is never high enough to reach that temperature. (Assuming not too high temperatures at the start of the conveying)

How do you explain the physical formation of streamers?

Assuming, you have read my BulkBlog article, I would very much appreciate your valued comments or additions.

Have a nice day

Teus ■

You article is completely usefull to guide and design a proper dilute phase pneumatic conveying system, and introduce an easy way to develop and comprehensive spreadsheet.

Thanks for this article sent. ■

You article is completely usefull to guide and design a proper dilute phase pneumatic conveying system, and introduce an easy way to develop and comprehensive spreadsheet.

Thanks for this article sent. ■

Originally Posted by KJordens

...

I have a curiosity that your article does not seem to address. I work for a company that produces LLDPE and LDPE pellets. With the pneumatic conveying of these plastics we occasionally find fuzz, fines, and streamers with the product. I am curious to know what material properties of the LLDPE and LDPE would make them more or less prone to these problems. There is much lore within my industry about the effects of the product's density, melt index (an inverse indication of viscosity and/or molecular weight), etc., but I would like to separate the myths from the facts.

...

Thank you.

Dear KJordens,

Streamer creation in high speed pneumatic conveying is known to occur for all Polyofins like PP and PE, but was also observed for products like hot Polyamide chips.

The creation mechanism can be explained as follows:

During impact of a pellet with the pipe wall a microscopically small area of the pellet melts and leaves a speck of molten material on the pipe wall. Those small specks bond together and build the film like streamers. According to this a streamer is not created by one single pellet, but by the millions of pellets hitting the wall during conveying.

A streamer of 2m length, a width of 10mm and a thickness of 0.2mm can be easily seen in 1 ton of product, however, it accounts for less than 0.04ppm of the total mass. Predicting the occurrence of streamers with energetic balances might not help.

In a roughened pipe the streamers cannot grow as long as in a smooth pipe due to the “interrupted” surface of the pipe.

In a smooth pipe higher streamer creation and but less dust is observed, whereas in roughened pipes a higher content of fines and “fuzz” is found. Both mostly created during impingement of the pellets with the pipe wall.

In low velocity conveying at gas velocities below 10m/s the impact force of the pellet is not high enough to melt a surface spot. Thus no streamers occur in low velocity conveying.

“Harder” products tend to create less streamers, but at higher product temperatures also the harder products are prone to streamer creation.

To reduce streamer creation following can be done:

- reduce conveying speed as much as possible

- keep the product temperature as low as possible

- use roughened pipes (at the expense of a higher dust creation)

- reduce the number of conveying bends

- replace long radius bends with special diverting elements (Gamma Bend® or Pellbow® )

- keep the pipe wall cool (especially in areas with lots of sunshine)

- cool down the conveying gas (especially for LDPE with EVA)

In regard to bend technology an interesting article can be found under:

http://www.pelletroncorp.com/uploads...Systemsen.pdf

Best regards,

Sven ■

Originally Posted by KJordens

...

I have a curiosity that your article does not seem to address. I work for a company that produces LLDPE and LDPE pellets. With the pneumatic conveying of these plastics we occasionally find fuzz, fines, and streamers with the product. I am curious to know what material properties of the LLDPE and LDPE would make them more or less prone to these problems. There is much lore within my industry about the effects of the product's density, melt index (an inverse indication of viscosity and/or molecular weight), etc., but I would like to separate the myths from the facts.

...

Thank you.

Dear KJordens,

Streamer creation in high speed pneumatic conveying is known to occur for all Polyofins like PP and PE, but was also observed for products like hot Polyamide chips.

The creation mechanism can be explained as follows:

During impact of a pellet with the pipe wall a microscopically small area of the pellet melts and leaves a speck of molten material on the pipe wall. Those small specks bond together and build the film like streamers. According to this a streamer is not created by one single pellet, but by the millions of pellets hitting the wall during conveying.

A streamer of 2m length, a width of 10mm and a thickness of 0.2mm can be easily seen in 1 ton of product, however, it accounts for less than 0.04ppm of the total mass. Predicting the occurrence of streamers with energetic balances might not help.

In a roughened pipe the streamers cannot grow as long as in a smooth pipe due to the “interrupted” surface of the pipe.

In a smooth pipe higher streamer creation and but less dust is observed, whereas in roughened pipes a higher content of fines and “fuzz” is found. Both mostly created during impingement of the pellets with the pipe wall.

In low velocity conveying at gas velocities below 10m/s the impact force of the pellet is not high enough to melt a surface spot. Thus no streamers occur in low velocity conveying.

“Harder” products tend to create less streamers, but at higher product temperatures also the harder products are prone to streamer creation.

To reduce streamer creation following can be done:

- reduce conveying speed as much as possible

- keep the product temperature as low as possible

- use roughened pipes (at the expense of a higher dust creation)

- reduce the number of conveying bends

- replace long radius bends with special diverting elements (Gamma Bend® or Pellbow® )

- keep the pipe wall cool (especially in areas with lots of sunshine)

- cool down the conveying gas (especially for LDPE with EVA)

In regard to bend technology an interesting article can be found under:

http://www.pelletroncorp.com/uploads...Systemsen.pdf

Best regards,

Sven ■

Hello Sven,

The calculation of the streamer part is actually:

2 x 1*10^-1 x 0.2*10^-3 = 0.4*10^-5 = 4*10^-6 = 4 ppm (still very very low)

The mechanism of friction converted into heat, temperature and melting of pellets and shearing the molten part off from the pellet can be true, but I think is doubtful.

Friction = Friction coefficient * Normal force

Friction energy = Friction coefficient * Normal force * sliding velocity.

This friction energy must be rather low, because:

-friction coefficient is low

-Normal force is low

-sliding velocity is just a part of the particle velocity, because the velocity energy is partly converted into rotational energy.

The generated heat is proportionally to the friction energy and therefore also rather low.

Then the generated heat is dissipated between the particle and the steel pipe wall, whereby the pipe wall takes the majority of the heat, due to the much higher heat conductivity.

The remaining heat temperature must be sufficient to melt the contact area of the pellet to allow plastic deformation.

And then, the remaining friction energy must still be high enough to shear the molten part off from the pellet against the bonding forces.

The formed droplet is then cooled down by the pipe wall.

The next particle must then not only melt itself, but also the very well cooled solidified first droplet against the pipe wall to feed the streamer growth.

This friction mechanism looks like a bearing situation, where frictional energy is dissipated also.

This analogy makes it possible to test this phenomena outside the pneumatic conveying system, f.i. on a rotating disc or a plate where plastic pellets are impacted on under a certain angle and speed.

Is the theory supported by calculations and/or tests?

Mr Agarwal’s opinion on the physics of the formation of streamers is still pending.

Best regards

Teus ■

Hello Sven,

The calculation of the streamer part is actually:

2 x 1*10^-1 x 0.2*10^-3 = 0.4*10^-5 = 4*10^-6 = 4 ppm (still very very low)

The mechanism of friction converted into heat, temperature and melting of pellets and shearing the molten part off from the pellet can be true, but I think is doubtful.

Friction = Friction coefficient * Normal force

Friction energy = Friction coefficient * Normal force * sliding velocity.

This friction energy must be rather low, because:

-friction coefficient is low

-Normal force is low

-sliding velocity is just a part of the particle velocity, because the velocity energy is partly converted into rotational energy.

The generated heat is proportionally to the friction energy and therefore also rather low.

Then the generated heat is dissipated between the particle and the steel pipe wall, whereby the pipe wall takes the majority of the heat, due to the much higher heat conductivity.

The remaining heat temperature must be sufficient to melt the contact area of the pellet to allow plastic deformation.

And then, the remaining friction energy must still be high enough to shear the molten part off from the pellet against the bonding forces.

The formed droplet is then cooled down by the pipe wall.

The next particle must then not only melt itself, but also the very well cooled solidified first droplet against the pipe wall to feed the streamer growth.

This friction mechanism looks like a bearing situation, where frictional energy is dissipated also.

This analogy makes it possible to test this phenomena outside the pneumatic conveying system, f.i. on a rotating disc or a plate where plastic pellets are impacted on under a certain angle and speed.

Is the theory supported by calculations and/or tests?

Mr Agarwal’s opinion on the physics of the formation of streamers is still pending.

Best regards

Teus ■