dear Mr urwithdilip,

I made a preliminary single stage design calculation for a 6 km pipeline for approx. 80 tons/hr of flyash.

The result is :

-single pipeline diameter ---------------- = 0.453 m (18 inch)

-Air flow------------------------------------= 2.32 m3/sec

-pressure ------------------------------------= 2.5 bar(o)

-capacity -----------------------------------= 92 tons/hr

-Solid Loading ratio -----------------------= 8.84

-power --------------------------------------= 502 kW

-Energy consumption ---------------------= 5.46 kwh/ton

-Residence time of flyash in pipeline-----= 802 seconds

-Fly ash in pipeline under way -------------= 22 tons

-Re-number ------------------------------------= 3.46 10^5

DO NOT consider this calculation as the design, just as a first indication.

May be you should also consider other ways of transporting the fly ash. F.i. by truck

Specially the feeder installation should be designed with great care.

In case of a two tank system the airflow cannot stop unless there is a purge time of approx 12 minutes built in, which in its turn reduces the overall capacity to an unacceptable low level, or the installation has to be increased considerably.

May be a screw feeder is an option, with the disadvantage of considerable extra energy consumption.

Dividing the convey length into more sections would increase only the investment by a number of transfer stations, complicating the controls.

does anybody know of a really built installation of this size and the resulting performance data ?

Again, this could be the start of your feasibility study.

We are very much interested

success ■

A pnuematic capsule pipeline will allow you single stage conveying in a single pipe system for delivery of your fly ash to the fly ash dump.

The six kilometer distance and the 700,800 tons per year of fly ash are well within a capsule pipelines capabilities.

The Pnuetrans system uses low pressure air from one to five psi to move the capsules from a to b and B to a. The capsule trucks run on six pnuematic rubber tires spaced sixty degrees apart on each end of the capsule.

A capsule pipeline will only require on employee per million tons of material moved from point a to point b.

If a single pipe system is used coal could be brough to the power plant during a set period or during the flyash delivery

A straight single pipe system using Victaulic pipe clamps and victaulic grooved pipe will need:

985-20 foot long joints of victaulic grooved pipe

1970 Victaulic clamps and gaskets

40,000 wooden ties to mount and secure the pipe on the surface of the ground with one or two hops per tie depending on system design as a loop system could use the parallel mounting method.if the distance is straight.

40,000 or 80,000 pipe anchors for the pipe to secure the pipe to the wooden or concrete ties depending on the system-twin pipe or single pipe.

This estimate does not include sweep elbows for curves., large elevations etc.

A single pipe system will require only a loading and unloading station and possibly a booster station for additional air velocity to move the capsule trains from a to b or b to a depending entirely on the terrain encountered.

Capsule trains are configured anywhere from one individual capsule to a unit train of five capsules for transit of materials from a to b. depending on weight and volume of the material as you wish to over come the weight of the capsule itself with the load to eliminate the weight of the capsule or capsule train.

Pipe loading percentage is not an issue as you can have as many trains in the pipe as you wish for the movement of materials

The capsule pipeline system ofered by Pnuetrans operates on air pressure from (one to five PSI) .07031 kilograms per square centimeter to 1.75775 kilograms per square centimeter) attaining a velocity of the capsule trains of (twenty five miles per hour) (40.2325 kilometers per hour) or (.2778 meters per second) or greater if needed.

The capsule pipeline is self cleaning as the capsule trains push any dust in the pipe to the end of the system with the rubber discs attached to the capsules to block the air and push the capsules from one end of the tube to the other.

The exhaust air is filtered eliminating airborne pollution.

As you have stated you wish to transport the fly ash to opencast mines you can also move your coal from the mines using a twin pipe system or a single pipe loop system with the same capsule trains and an additional loading and unloading system.

You will also have the ability to generate electricity by using synchronus electric motors to allow the blowers to run in reverse/while xhausting the air in the pipe to generate electricity and return the electricity back into power grid.

For more information and the histoty of capsule pipelines

www.capsu.org this link will take you to an existing capsule pipeline in japan used by mitsubishi cement uses to transport limestone aggregate to a cement plant this system has been in use since 1983 and replaced a railroad and is buried in the old railroad bed.

google( Karasawa mine)

www.pnuetrans.net

For further information contact www.pnuetrans.net mr weaver has a link to a page where you can fill in all the necessary information and he will give you a free no obligation quote for a system. ■

Dear Teus

If the residence time of the fly ash in the pipeline is 802 seconds in a 6000 m long pipeline, the mean particle velocity will be about 7.5 m/s. This is dense phase conveying. You give the solids loading ratio as 8.84 for the fly ash and this is very much dilute phase conveying. Are the two compatible? ■

Dear David,

First I calculated the pipeline again and show now the table of velocities and pressure drops.

The fly ash is taken as 30 micron with a product density of 2260 kg/m3 , resulting in a floating velocity of 1.29 m/sec in atmospheric air.

5/5 92.0 tons/hr

Press: 25000

prod.loss.fact 0.00120

Part---------length-------v-air----v-product------press.drop----- v-wall/v-susp------sediment

----------------m----------m/sec-----m/sec----------mmWC

1 intake----1.0-----------5.2-------4.9 -------------159---------------3.4-----------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

2 pipe------1963.0-------6.6-------6.5-------------9722.-------------3.7------------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

3 bend ------------------- 6.6-------3.9-------------9725.

4 pipe------1963.0-------9.0-------8.9-------------16602-------------4.3-----------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

5 bend ------------------9.0---------5.3-------------16605.

6 pipe---------73.0------9.2--------9.1-------------16875.------------4.3------------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

7 d.tr---------------------9.2---------9.1-------------16875.

8 pipe-------1890.0-----12.8------12.7-------------22089------------5.1-----------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

9 bend-------------------12.9-------6.8--------------22092.

10 pipe-----------0.0-----12.9-------7.2-------------22096------------5.2 ------------?¡?¡ ?¡?¡?¡ ?¡?¡?¡

11 d.tr--------------------12.9--------7.2-------------22096.

12 pipe--------100.0-----16.2-------14.8------------24757-----------5.8 ------------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

13 bend------------------16.3---------8.8------------24761.

14 pipe ----------10.0----16.4------16.0------------24879------------5.8-------------?¡?¡?¡?¡?¡?¡?¡?¡?¡?¡

15 bend-------------------16.4-------10.1-----------24884.

16 outlet------------------ 16.4------10.1-----------24899.

17 filter---------------------0.5-----------------------25000

v-filter 0.49 m/min

No booster >

Length 6000 M

Residence time 802.44 sec

Power 502.kW

Energy consumption 5.46 kWh/ton

Fly-ash urwd

Re = 3.46

[ENTER] to continue

The air velocity in the pipe needs to be higher than a factor times the floating velocity, whereby the particles are kept in suspension.

This air velocity is lower when the pressure is higher, due to the higher air density under pressure.

In this long pipeline, the empty pipeline pressure is approx 1.4 bar(o), while the air resistance under conveying conditions is approx 0.4 bar.

A low loading ratio, causing a low pressure drop per meter, adds up to the 2.5 bar(o) conveying pressure over the 6 km.

Resume:

-low velocity is chosen as a factor x floating velocity

-low Solid Loading Ratio is necessary in respect to max pressure of 2.5 bar(o)

Dense phase or dilute phase should indicate two different regimes of pneumatic conveying and in that respect the two regimes are comparable.

Remains the definition of dense- and dilute phase.

One of my earlier threads was about this subject.

Attached you will find a document, describing the definition, that was proposed by Mr Awargal.

Best regards

teus

Attachments

zenz diagram (ZIP)

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Dear Experts,

I have been observing some of the Dense Phase Handling sytems installed here in India and i have noticed that the actual power consuption required for conveying is atleast 4 times than what the computer output shows or even what the Zenz curve shows .

Secondly The system is not very efficient when it comes to the of extraction of ash from some hopper in comparison to a Vacuum conveying system .

Any suggestions or comments ......

Regards ■

Gravity, Boyles and Charles law for gasses explains it all. ■

For a given conveying duty the power required for a dilute phase conveying system will be at least four times greater than that for a dense phase system, as mentioned above; this is common knowledge. So the demand for dense phase conveying is often made for anyone tendering for a system, and particularly for fly ash handling systems in India to my personal knowledge. There is, therefore, a lot of mis-information on the subject because systems manufacturing companies will claim that they will supply a dense phase conveying system even when they know that it is quite impossible, in order to get the job. Provided that the system works at the end of the day no one will bother to check and so the dense phase myth perpetuates.

Dense phase conveying, for materials that are capable of being conveyed in dense phase, requires a high pressure gradient in order to convey at the material concentration necessary to sustain dense phase conveying. This relates to fine powders with good air retention properties that will convey in dense phase in a sliding bed or fluidised bed mode of flow, such as cement and the fine grades of fly ash. To convey at a solids loading ratio of about 20, for example, will typically require a pressure gradient of about 5 mbar/m (10 psi per 100 ft). If you have a vacuum or low positive pressure system with a pressure drop capability of say 0.5 bar then you will not be able to convey more than about 100 m with a solids loading ratio (SLR) of 20. If you have 5 bar available with a positive pressure system you will be able to convey over 1000 m in a single bore line, and considerably more with a stepped pipeline.

If you convey at a much lower SLR you will be able to convey over very much longer distances. If you want to convey at much higher values of SLR, however, and hence very dense phase flow, you will be limited to much shorter conveying distances. Pressure gradient, therefore, is the key to conveying capability. ■

dear Sachin,

Obviously you have field information of operational pneumatic installations and corresponding computer calculations.

Assuming that the calculations do properly represent the installations, you must be able to find the source of the discrepancy.

It would be very interesting to learn from you how the installations, you refer to, are built and what their performances are and how the computer calculations predicted the performances.

If you can share that information, a lot can be learned.

dear Mr Mills,

In your article in Bulk and Solids Handling 1/2006 you proved that a vacuum- and pressure system are fully compatible as long as the pressure ratio is the same.

Pressure ratio = (abs begin pressure)/(abs end pressure)

Example:

Vacuum = 0.5 bar

pressure ratio = 1/0.5 = 2

Pressure = 1 bar

pressure ratio = 2/1 = 2

Then:

Convey length pressure system = Convey length vacuum system

SLR pressure system = SLR vacuum system

Power pressure system = Power vacuum system

Capacity pressure system = Capacity vacuum system

Actually: for a given distance and performance a compatible vacuum system and pressure system can be designed. Whether the vacuum system is still economical or practical is another issue.

This also implies that the calculations for vacuum- and pressure systems should use the same formulas and coefficients.

The only difference is the behavior of the air pump.

Now we have still have the problem of the definition of dense phase and dilute phase.

If you look at the previously attached file the definition proposed by Mr Agarwal is calculated, using ONE algorithm and results in a dense region and a dilute region.

How can the dense phase myth be busted?

best regards ■

Teus

If I recall correctly, you're a few years older than me, and if not, I apologize but for the better part of the 34 years I have spent in this industry, I have tried to support the development of a uniform terminology and definitions for the key terms we all use on a daily basis.

Back in the late 1980's, CEMA in the US organized a group of representatives form the major pneumatic conveying suppliers at that time and asked them to develop a "industry glossary". I was on that original committee. It was developed and printed in 1992 and used by some and as you would expect, ignored by others. It was very general and unfortunately was never updated or kept current as far as I know. I wouldn't be surprised if most engineers in the field today don't even know it exists. (I keep my copy right along slide my slide rule.)

As Dr. Mills so intuitively points out, as long as you have global suppliers competing for global business, they will say and do whatever is required to secure the business. Many suppliers actually have multiple technology / equipment capabilities and can offer the client truly the best solution for a given application. Others who are single product / technoloigy oriented will sell what they have and explain it as necessary to meet the purpose.

Many will say that the "dense phase myth" started in the late 1960's / early 1970's but if you go back to the original patent of the Fuller Kinyon Screw Pump, one of the claims is that it conveys material in a "dense stream" in the pipe line.

All we can do as academics and consultants is to keep trying to educate the users as best we can BEFORE they need us to correct a problem. But then again, that'some of us make our living.

Regards ■

dear Jack,

If you are younger than 63.5 years old, you are right, whereby I only spent 29 years in pneumatic conveying (starting in grain).

When I developed the theory of pneumatic conveying and the mathematical approach of calculating ( put into a computer program), I did not encounter a physical phenomena that related to dilute or dense phase.

It was in the forum that I noticed that many colleagues mentioned this conveying characterization .

Dense- or dilute is still not a problem in my calculations nor a distinctive difference that could appear in pneumatic conveying.

Calculating the volume loading ratio, almost all pneumatic conveying is dilute or lean phase.

Nevertheless, I was interested in what was meant by dense- or dilute phase and therefore I made a thread about it.

Mr Agarwal is the only member so far, who came with a verifiable ( in my opinion a rather academic ) definition..

As dense phase was introduced with the Fuller Kinyon Screw Pump, what was their definition?

And what was the definition according to the CEMA group in the late 1980’s?

As Dr Mills and you say, the dense phase and dilute phase is used as a commercial argument for salesmen (in a context as commercially opportune), may be this myth should be busted.

Awaiting interesting replies,

take care

teus ■

Teus

The CEMA Glossary of Pneumatic Conveying Terms defines dense Phase as follows... " A dense phase system is any pneumatic conveying system for which the conveying gas velocity is generally below the saltation velocity of the material being conveyed".

When Mr Fuller and Mr. Kinyon patented the first screw pump, I donot believe a specific definition existed for the term "dense phase", but if we go back to that time, (late 1929) - the pump was developed to convey pulverized coal and at that time, the "other" means was in a high air to material ratio system ( IE dilute phase) so I think they simply meant a system that wasn't dilute.

Cheers

Jack ■

Hi Jack,

The CEMA Glossary of Pneumatic Conveying Terms definition for dense Phase

( A dense phase system is any pneumatic conveying system for which the conveying gas velocity is generally below the saltation velocity of the material being conveyed) is more or less the same definition as proposed by Mr Agarwal.

The lowest pressure drop per meter of length at a given capacity as a function of the air velocity is also where the sedimentation starts. A lower air velocity is below the saltation velocity.

That region is also the where the energy consumption per ton conveyed is the lowest (remember that the pressure drop per meter of length is the lowest)

The energy consumption per conveyed ton increases when the velocity is decreased further or in other words, when the conveying regime is more into dense phase.

Also Mr Fuller and Mr Kinyon were right, because below the saltation velocity, the Solid Loading Ratio becomes higher. (more dense – less dilute)

In the case of this conveying pipeline of 6 km it appears that a low velocity (close to the saltation velocity) goes together with a low loading ratio.

Dense phase or dilute phase is now pipe length related.

Please comment my views.

teus.

PS Mr urwithdilip, did we help you in some way ? ■

I was also involved with a glossary of terms for pneumatic conveying, with the British Standards Institution in the 1980's. We also decided upon dense phase conveying relating to conveying with air velocities below the saltation velocity, at the feed point into the pipeline, recognising that it can change along the length of the pipeline.

I must take issue with Teus, however, with regard to energy consumption. An increase in energy is required for conveying at velocities above the saltation velocity, for all materials. The same is not always true for conveying at velocities below the saltation velocity, where this is possible. I appreciate that the Zenz diagram tells us that this is so, but I contend that this only holds true for pelletised materials that are conveyed in the plug flow mode of dense phase conveying. This is not the case for most powdered materials that are conveyed in the sliding bed or fluidised mode of dense phase conveying. I have found that energy consumption deceases with decrease in conveying air velocity in dense phase flow for materials such as barytes, bentonite, cement, fly ash and flour. It does, hoever, increase with materials such as pvc resin and terephthalic acid. ■

Dear Sir,

you have said that dense and dilute is defined only by the difference of pipe length ,material to be conveyed, pipe bore etc but what about the philosphy of conveying i.e continous conveying and batch conveying

Please Comment

Regards ■

sachin

the "philosophy" of conveying as you refer to it as either continuous or batch has no influence on the mode of conveying

dense or dilute can both be continuous or batch

Regards ■

Dear Mr Mills,

Thanks for your reply on the dense phase - dilute phase issue.

The British Standards Institution definition is consistent with the other definitions.

The dense phase myth can now be considered as busted, because now everybody understands the meaning of the various definitions, which are all built around the saltation velocity.

The energy consumption is actually the product of :

pressure drop per meter times airvolume.

As the airvolume decreases in dense phase, the pressure drop increases (SLR is increasing)

When the decrease in airvolume is overcompensated by the pressure drop increase,

the energy consumption starts to increase at lower air volumes in dense phase.

That happens quickly below the saltation velocity.

The additional comment of RPD illustrates that many people define the same conveying regions in different ways.

I strongly support the suggestion of RPD of defining sub sets of flow regimes.

Sincere salutations

teus ■

I respectfully suggest we all get together in Miorca to discuss and agree on the globally accepted terminology and definitions!!! ■

That sounds very warm and inviting due to the weather- Jack do you think that Punxatawney phil got into some wild wood flower as his prediction seems to be way off? ■

Whatever that little ol feller was drinking -- I want some!! ■

My least favorite explosive comes to mind AMFO/ANFO/Ammonium Nitrate fuel oil explosive.

The use of a tapered bottom pressurised vessel to move anfo prills in blast holes has its moments especially when the tank is near empty and the delivery hose hase a mind of its own due to the reduced prills and the excess compressed air for delivery of the prills.

hence the full tank and full hose delivery and when the tank is near empty TA DA lean phase delivery with a deliver hose that has a mind of its own if it is not restrained in the hole or by hand. ■

Dense/ Dilute who really knows...

Some people say that it deals with material to air ratios

other say it depends on the conveying velocity (average or exit, take your pick)

some people say it depends on the pressure at the material pickup point

one other way is the way the material is introduced into the conveying line.

For this application, 6 km, 80 TPH??? That is a long way and a lot of material (and air). It will take a massive amount of energy to convey it vacuum, dilute or dense. They will all be able to do it, if properly designed. But I doubt that you could find a manufacturer of a filter receiver large enough for vacuum or dilute phase (under 15 psig in my book), but I haven't done any calculations. If you are going to do it via pnematics dense phase (high pressure, lower velocities, high material to air ratio, and pressure vessels) is the way to go.

I look forward to seeing your process here in the US on Discovery on "Engineering Marvels". ■

I have worked on a feasibility study for an ash conveying system 3 km long and have compared the merit and demerits with mechanical conveying (pipe and belt conveyors). Pneumatic conveying lost on all aspects i.e. capital cost, energy consumption, maintenance costs, reliability. These kind of distances are not commercially feasible for pneumatic conveying systems. I won't even bother to go into lean / dense phase argument. ■

Dear Mr Walker Robbins,

In the previous discussion, we more or less figured out the definition of dense- and dilute pneumatic conveying.

Below or around the saltation velocity it is dense phase and above the saltation velocity it is named dilute phase.

Below or around the saltation velocity a system will operate at a relatively high Solid Loading Ratio for that installation.

The absolute value of that (dense phase) SLR is depending on the convey length and the applied pressure.

In fact this is also true for higher velocities then the saltation velocity, but then we call it dilute phase.

I feel comfortable with this definition, although the practical importance of this definition is not very high.

(Anyway, until now many people had different perceptions of dense- and dilute and nevertheless all pneumatic systems work)

A do believe Mr Mantoo that a pneumatic conveying system over 6 km at only 80 tons/hr

(3 bulktrucks/hr) will be an installation that will cost a lot of money per conveyed ton.

best regards

teus. ■

I do agree that a 6.000 m pneumatic conveying system can't compete against e.g. a pipe/belt conveyor in regard to operational costs. But for equipment/installation and maintenance costs the pneumatic conveying system is an interesting option.

I don't know any pneumatic conveying system (without intermediate stations) of this distance. But Moeller Materials Handling (Germany) has a reference for fly ash with a distance of 3.000 m and a capacity of approx. 70 t/h (double-pressure-vessel system with pipe-in-a-pipe technology) in Japan. Due to the installation situation it was not possible to use a belt/pipe conveyor and equipment/installation/maintenance costs would have been much higher.

I expect that 6.000 m need to be designed with an intermediate station but maybe 2 x 3.000 m will still be of interest for this application...? ■

Dear Mr Urwithdilip,

1) power consumption for 2 times 3 km instead of 1 time 6km will be the same or a bit more. (Nothing for nothing in physics).

Due to the increased complexity of the installation, the investment will be higher.( the two systems in series have to be synchronized or an intermediate surge bin is required)

2) I do not know.

3) 6km , 80 tons/hr.

3 bulk trucks of 30 tons each

(1 loading, 1 driving, 1 unloading)

success ■

Our partner company Macawber Beekay, based in Delhi, will be able to assist you in this matter. In the first instance you should contact Karan Gupta (Director) on +91 11 4222 4222 or email him at karan.gupta@mbl.in

I hope this helps with your query. ■

Peter Wypych publishes some good work on long distance transport of materials. One of his papers shows pulverised coal over 1.8 km at 24 tph in a 200mm pipe. The predicted pressure would be 2.7 barg with a flow of 60Sm3/min.

A simple calculation shows that if it was 80tph at 1.8 km the pressure would be 9.0 barg at 1.8 kM, or 30 barg at 6.0km, on the 200mm line. Changing the line to 450mm would suggest a pressure of about 5.8barg. Clydes own internal models predicts a pressure of about 6.0 barg, suggesting a supply pressure of about 8.5 barg. Hope this is helpful. ■

I will not go into technical detail / challenges of such system but just for curiosity with 450mm pipe from your Clyde model how much kw/hr this beast will consume? ■

Please see our website for flexible air slide systems. This system will do your project.

http://sciroccohose.com/index.html ■

Mr. Collins

Have you read the thread completely???

Have you a reference installation for the hose you offer in a similar size and capacity application?

I'd be very interested in seeing the particulars.

Regards ■

Dear Mr Rich Ellis,

If pneumatic conveying was that simple, just scaling up and down proportionally.

But it is not.

How about the gas velocities in your calculations?

Keep in mind that v-gas/v-suspension should be constant.

(The reason for stepped pipelines)

But v-gas/v-suspension = constant * SQRT(press+1)/(press+1)

Thus, with the same pipe diameter and the same gas volume, this ratio decreases with increasing pressure and is therefore not constant.

It could be that your installations for 9 and 30 bar will choke.

Please clarify.

Best regards

teus ■

Very late in the thread but here goes.

When I first came across the 'pipe in a pipe' system it seemed to be the answer to long distance conveying. It was used in different forms by competitors with the usual claims.

I was even poised with a spreadsheet to calculate suitable plug lengths...I was younger then.

Eighteen months ago I was working in Den Haag, oil & gas of course, & lo & behold the Johannes Moeller Tuboflow system was mentioned in case literature as the one to be avoided at all costs. Those boys are not short of cash so if they can't make 'em work..who can?■

I suggest you use Atlantic Blowers centrifugal blowers or even maybe their regenerative blowers for the transport of the ash. You can visit their website at

href="http://www.atlanticblowers.com" target="blank">www.atlanticblowers.com or you can e-mail them at

href="mailto:sales@atlanticblowers.com">sales@atlanticblowers.com.

Attachments

big-logo (JPG)

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Dear Sir.

I suggest that you could give us the details so that we could give you the best disposal.

We are Alstom sizhou . who is one of the best ones in the ash handling system in china ■