Why don’t you get your material tested for internal and wall friction angle and determine the suitable cone angle? Mass flow cone might be an expensive option but then will make your life easy.

If you want to use a silo discharge aids then vibrator is not the only option. Aeration can be good if this grade of gypsum is fluidisable. Ultrasonic techniques are also available. ■

www.primasonics.com for cleaner

As far as cone angle is concerned my experience is irrelevant

it is material specific. ■

dear Mall,

Try some membrane pulse valves (as used for puling self cleaning filters) mounted against the cone on a welding socket.

This easy to mount, even when the silo is full.

Or just tap the pulse air of from a nearby filter.

Easy to do at very low cost and the result is clear at the same moment.

Done this before in cement bins

success

teus ■

dear Sir,

Please find attached a file containing a word document showing a sketch of the application of membrane pulse valves for the fluidization of material in a silocone.

Hope the drawing explains itself

teus ■

sorry I made a mistake.

Again

Attachments

silocone (ZIP)

■

Dear Mall,

We have encountered several problems such as your application in various sectors. We have solved their problems and give exact solutions without modifying the geometry of the silos.

We are manufacturing the air cannon systems and delivered over 7000 units to different sectors, such as cement, gypsum, coal, copper and several hard to handle material applications.

It eliminates these clogging, sticking and rat holing problems occuring inside the silos, bins, hoppers. It does not blow continuous air instead introduces an air shock for a very short instant and sweeps all the material in between walls and material surface. It prevents compaction due to vibrating effect.

For detailed information please look to our web site www.yunel.com. or contact with us.

Thanks for your inquiry,

Best Regards,

Ufuk YUNEL

(M.Sc. Mining Eng; M.B.A)

Sales Coordinator

YUNEL LTD., STI

Address: Esat Cad. No 42/12 Kucukesat 06660 Ankara - Turkey

Tel: +90 312 4193285

fax: +90 312 4193289

e-mail: sales@yunel.com ■

Dear Mall,

The valves are the normal membrane valves used in filter pulse systems under exactly the same conditions.

I used 1.5 inch membrane valves, mounted in a 1.5 inch sockets, welded to the cone.

(The hole was drilled after the socket was welded to the cone and just before mounting the valves).

The timer was set at an interval of approx. 1 to 1.5 minutes (for one valve) and at a pulse length of 0.2 sec

Pressure was set at approx. 6 bar(o)

Best regards

teus ■

dear Mall,

Have a look at

www.airsweepsystems.com

They have the sysytem professionally available for the market.

The site gives nice pictures that explain the function very well.

success

teus ■

Primasonics Acoustic cleaners have been employed to prevent material hang ups and prevent both 'ratholing' and 'bridging' in silos & hoppers in over 40 countries worldwide.

It could be well worth your time taking a look at the following link -

http://www.primasonics.com/acousticcleanersrange.htm

On that site you will also find silo questionnaire which you can complete on line or download.

Alternatively you may contact me for advice on -

sound@primasonics.com

Donald F Cameron

Primasonics International Limited ■

Hiya,

Don't ever confuse the real world with that of applied engineering mathematics.

A 45 deg hopper is a common place to start, as it is suitable for many products, provided that they act like golf balls.

Others say, no, no - that will never do. Look at this clear plastic model containing dried silicone sand particles. See how one end will show a nice, smooth hour-glass flow, while the other end will show rats running after Tom and Jerry.

In my experience gypsum is a powder. It will cake if it gets moisture in it. It can even stick to surfaces upside down. It behaves differently if it is flowing, or has stood static, during a plant shut-down, for several weeks.

From one point of view you don't want a cone at the bottom at all. You want a staight wall cylinder sitting on an apron feeder. that way you can shear the whole cross-section at once, and the weight of the product will collapse any bridges.

No. You can't do that. Why not? Because it will never be approved. It has never been done that way before, and besides, it will cost too much money. Ahh - the root of all evil - money, money, money, ain't if funny, it's a rich man's world.

If you have to funnel your powder, try to keep it flowing. And don't let it stand. That means the funnel should only be used for transitions, and should be purged out after the end of flow.

Capich?

Have fun - Sgt John.Rz

www.latviantourists.com.au ■

Hello tq,

Many times plants have this problem and find there are many types of things to try, the first big decision is cost. Is the problem large enough to invest in changing the vessel design? One way toa pproach it is to try lower cost solutions first before making a big structural change. In this case with the 45 degree slope, I would recomend lining the sloped surface with UHMW and installing Sword Nozzles with Air cannons. These Sword Nozzles fire compressed air via this sword and fluidizes the material. With concrete walls as you mentioned, vibrators would not be a good solution in my opinion. The vibration may cause stress cracks in the structure and the mass of the structure would require a lot of force output from a vibrator of this type. See attached image.

Good Luck.

Lou Gutierrez

Clean Plant Engineering

Attachments

swordJPEG:forum_attachments/file_container/sword.jpg (BMP)

■

A vibrator manufacturer is NAVCO in the USA.

www.navco.org

They have a variety of types of vibrators. ■

Dear Mall,

When you are referring to " the blow pipe ", that is in fact just a welding socket, welded against the steel cone of the bin.

That can best be done perpendicular to the surface of the cone.

You can send me an e-mail through the forum if you click on my name or "profile"

It is then may be easier to exchange drawings.

bes regards

teus ■

Dear Mall,

The socket plus the membrane valve are watertight.

Water cannot enter from the outside.

If undried compressed air is used for pulsing, some condensation can occur,

but does not necessarily cause clogging/

The material flow inside the cone should remove caked material

In case of clogging, unscrew the membrane valve and unplug the hole.

best regards

teus ■