Dear Pablonici,

If you know basic Excel, you can use the calculation method given in detail in my article "Theory and Design of Pneumatic Conveying Systems". It was published in the April 2005 issue of Powder Handling and Processing magazine and is available free on request to me.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Dear Amrit,

may i have your article:Theory and Design of Pneumatic Conveying Systems?

Regards

■

my email: kevinjcg@163.com

thank you for your consideration

■

Dear Pablonici

With resspect to your original question concerning materials for the piping system, I would suggest you can use ordinary steel pipe for the straight horizontal and vertical runs. For the elbows, short radius elbows are recommended and using wear resistant materials of construction will provide an extra level of availability.

Also, immediately downstream of any elbow, use a section of abrasion resistant pipe for a minimum of 10 diameters and more preferably up to 20 diameters. This is the zone where turbulence occurs after a bend as the material recovers it's relationship with the air stream.

Choices can include hardened steel pipe, spun cast pipe, ceramic lined pipe, etc.

Keep the conveying velocities to a minimum and consider stepping the pipe line at the terminal end to reduce the over-all velocity profile. ■

The most reliable method is to measure the flow rate BEFORE it goes into the conveying system.

In many of the systems we have designed, we suggest the use of solids flowmeters to accurately measure the flow rate. They can be slaved to variable speed belts, screw feeders or flow control gates to increase / decrease flow rates as necessary.

Depending on the type of line charger being used into the pneumatic line, approximations of the flow rate can be made based on displacement of rotary airlock rotors and efficiencies, pressure tank volumetric capacities or screw pump displacements and rpms.

Regards ■

Before you begin to put material into the pipeline, run with air only and record the empty line pressure drop.

Each time you end the conveying, the empty line pressure drop should go back to that same value when the line has purged clean. If the empty line pressure gets higher, that is a sign you have material building up in the pipe and not totally cleaning out. ■

Dear Amrit:

firstly,thanks of your email reply, I am a student of Qingdao university of science & technology (Shandong province, China), my major is pneumatic conveying, from the forum,I get more information ,this is helpful to my study, and i think your aritle Theory and Design of Pneumatic Conveying Systems which is very useful to my thesis, may I have your aritle?

email:jcgjcg168@163.com

■

Safety is always then ultimate concern In this case, it is primarily related to the "fines" and "dust", not the actual coarse coal itself.

The majority of the systems in which we have been involved use air for the conveying systems but care is given to all fabrications and machinings to have no ledges or pockets where fines and dust can accumulate. If dust is left to be idle for any period of time, then use of an inert gas is recommended.

Typically the equipment is desigend to meet the relevant code requirements in your specific plant. For example, the NFPA has requirements for equipment design to contain explosive pressures. I'm not familiar with your specific location, but you should check with your insurance underwriters as many times, the insurance carrier will dictate what codes must be followed. ■

You should follow NFPA Standards 68 or 69 to design your coal handling systems for preventing and protecting your plant and personnel against dust explosions created by coal dust. Coal dust is an explosive material and in the presence of oxygen and a strong enough ignition source it will lead to a deflagration. Pressure containment and use of inert atmospheres are generally more expensive methods than pressure relief and pressure suppression. Being a long time process engineer in this technology area, I will be glad to help you out.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

dear friend .

many people are handling your kind of coal , ask arrownd , arrange for a visit. and everything will be clear.

steel mills in general can be very cooperative in safety related issues.

Inerting is not that expensive , over pressure design is ..

I personally do not like explosion venting as a prime solution.

I always think that explosion prevention is the way to go.

Again look arrownd and see an existing installation , PET coke installations abound

you might like to look at them , and get cost figures too...

regards

Marco ■

NFPA Standard 69 requires inerting, i.e., oxygen concentration in air, by weight, reduced from 21% to less than 8% provided the MIE (Minimum Ignition Energy) of the dust is less than 10 millijoules. These dusts are considered to be highly explosive, therefore, NFPA Standard 68, (Explosion Venting) is not recommended for them. Inerting would require an expensive closed loop conveying system unless the inert gas that is used for conveying is so cheap that it can be released to the atmosphere. But if your dust has an MIE of less than 10 mJ, you have no option but to use NFPA 69.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

EXPENSIVE RETURN LOOP?.

I TOUGHT YOU WERE INJECTING INTO A FLUE GASSES DUCT .

EVEN IF THEY ARE INJECTING TO THE FURNACE INTO THE MELTED BATH THERE IS NO RETURN LOOP , THEY HAVE TO DUMP THE CONVEYING GAS AND GENERATE NEW . SOMETIMES THE PICKUP FOR THE COMPRESSOR COULD BE FED FROM THE STACK. BUT YOU MIGHT NEED TO CLEAN IT AND REMOV THE EXCESS WATER.

I BELIEVE THAT YOU CAN CONVEY WITH NORMAL AIR IF THE NITROGEN AND OXIGEN ARE NO PROBLEM IN YOUR DESTINATION.

JUST KEEP YOUR SILOS INERTED, AND MASS FLOW IF YOU CAN. IF YOU CANNOT THEN USE EXPANDED FLOW SILOS , MANY CEMENT PLANTS THAT USE PET USE EXPANDED FLOW SILOS , THAT WAY THEY SAY THEY GET AWAY FROM THE LARGE CONES OF MASS FLOW SILOS.

SOME STEEL MILS CONVEYING SYSTEMS DO NOT DUMP INTO THE FURNACE BUT TO A SERIES OF STORAGE SILOS , AND SOME USE PROCESS GAS AS CONVEYING MEDIA, THEN THEY MUST COOL AND CLEAN AND THEN CLOSE THE LOOP TO THE COMPRESSOR

WHAT YOU DESCRIBE HERE GOES TO A FLUE LINE, THE LIME FOR REDUCING THE EXPLOSIVITY HAS BEEN USED BEFORE I BELIEVE ,

I HAVE LITTLE EXPERIENCE USING LIME FOR THAT PURPOSE

BUT IT IS MORE COMMONLY USED WHEN THE COAL IS INJECTED INTO THE FURNACE , TO WORK IN THE SLAG.

HAVE FUN.

MARCO ■

Dear Amrit,

may i have your article:Theory and Design of Pneumatic Conveying Systems?

my email: yuyonghua@163.com

Regards ■