Dear Darkhe,

I understand that you want to convey raw material for cement production pneumatically.

The first thing to establish is whether the raw material is pneumatically conveyable.

Wet raw material or dry raw material?

Particle size?

Basic raw material or the mix of raw materials?

Material (particle) density?

Bulk density?

This information is at least required to calculate a pneumatic conveying system.

Then the issue of a screw feeder system of a double pressure tank system can be addressed.

For the time being, search this forum for the term “screw feeder” and you will probably find most of the answers to your questions.

Have a nice day

Teus ■

Hi - seems like a study is required

You should contact the main suppliers for their prelim, offers.

The decision on which system rest with a few factors - costs - CAPEX and OPEX plus site constriants eg tank system willrequire some head room for the feed side.

The other alternative is mechanical eg airslides/elevator - low power per tonne but higher costs.

Only when you look at these in detail, will the answer be clearer ie no one system rules for all cases esp. when power costs vary

Cheers

James ■

Dear Darkhe,

For this raw material pneumatic conveying is feasible. But instead of one conveying line you will probably need multiple lines, in parallel, because of the very high conveying rate of 200 tons/hr. To reduce cost, these lines can have a common source to supply conveying air. Feed to the conveying line can be a blow tank or a rotary valve.

The other option is to use a mechanical system such as a bucket elevator and a belt conveyor.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Dear darkhe,

I did a preliminary calculation.

Material: raw material for cement production

Particle size: 80 micron

Bulk density: 1400 kg/m3

Particle density: 3100 kg/m3

v-suspension: 2.26 m/sec

Product loss factor 1.7 times of cement.

Pipeline diameter: 336 mm / 387 mm (14”/16”)

Compressor displacement: 1.416 m3/sec

The calculated capacity estimates are:

Double tank system (Tank volume= 18m3 , material volume=14 m3)

Pipeline capacity = 240 tons/hr at 2.5 bar

System capacity = 203 tons/hr at 2.5 bar

System energy consumption 1.34 kWh/ton

Screwfeeder

Capacity = 200 tons hr at 1.7 bar

System energy consumption 1.76 kWh/ton

I do not see the necessity for a multiple pipeline system, unless you want some redundancy.

Consider this calculation as an indication only.

For guaranteed performance, you need to consult experienced suppliers of those systems.

Best regards

Teus ■

Dear Darkhe,

In my above post I missed answering your question about using a Screw Pump. I think that a Screw Pump is not suited to your material because it will not provide an air lock.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Dear Amrit,

I visited the website of FL Schmidt and found the following link:

http://www.flsmidth.com/NR/rdonlyres...inyonHPUMP.pdf

In this brochure, FLS states tha the FK pump handles cement raw materials.

Have a nice day

Teus ■

Dear Teus,

Screw pumps must provide a positive seal between the feed and discharge ends to prevent back flow of conveying gas. For this purpose the screw is designed with a differential pitch so arranged as to compress the conveyed material. Thats why the main application of screw pumps is for conveying fluidizable materials such as cement.

It may be possible to make some changes to the standard screw pumps for conveying coarse materials. I would like to know what these changes are.

Thanks,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Dear Amrit,

Using the Geldart classification for 80 microns and 3100 kg/m3, cement raw material is on the boundary between Group A and Group B.

Group A is easily fluidized and Group B is sand like and bubbling fluidizable.

When you stated “that a Screw Pump is not suited to your material because it will not provide an air lock”, I just checked it on the website of FLS.

If FLS claims that it is possible, I believe them, although the conditions for proper operation are not mentioned.

I suppose that adapting a screw pump for a certain material can be done by changing the characteristics of the screw, some of them being the pitch ratio, fluidizing at the screw intake or limiting the back pressure.

Therefore it is so important to contact manufacturers about their products as they have the experience.

Have a nice day

Teus ■

Dear Darkhe,

The screw pump “250 mm unknown source pump with 240 mm screw dia” could well be a FK250 pump (Fuller Kinyon).

I have no experience with handling cement raw material, however, I suspect that raw material could be more abrasive and less fluidizable.

Therefore, I strongly advise you to contact FLS, Bethlehem, PA, USA for getting the right information and proposals.

Moreover, because you already have the piping installed, which fixes for a certain amount the required compressor volume and filter size, they can estimate the capacity and pressure for you.

Another company to consider is IBAU Hamburg.

Do not go on your own steam!

Take good care

Teus ■

Dear Darkhe,

In my opinion it is risky to make decisions for a project based on discussions in this Forum.

Also, most vendors will always push their own products. But decisions should be based on biased-free information.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Charleston, WV, USA

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Good Day

There are / have been MANY installations of screw pumps (FLS, IBAU, CPAG) handling materials which are not considered Class A or Class B materials

1/8" limestone and coal have been conveyed into fluid bed boilers and in the early days of atmospheric fluid beds, 1/4" coal was conveyed

The non return "flapper" valve on the discharge of the screw acts to help prevent blow back, by controlling discharge line pressures, etc., blow back can be mitigated

Most of those applications use constant pitch screws as compression screws can break the material and on some products can increase required horsepower although the screw power requirement is more influenced by the discharge pressure it is pumping against

It is not surprising that contacting some vendors about reusing existing equipment go with no response because they want to sell you new equipment.

We have helped our clients built many systems out of "used" and "existing" equipment

What you cannot do is rely on typical screw conveyor calculations for trying to determine the screw pump capacity as they act as completely different animals

Darkhe -- send me an email to my address below so I have your direct email and I may be able to provide you with some specific information for your problem at hand ■

Dear Dark,

The bulk density has only a slight influence on the calculations in bends and in case of sedimentation.

As the calculations in your case were only indicative, the given results are still within the stated inaccuracy.

Have a nice day

Teus ■