Computer programs are only a means to calculate the pressure drop in a conveying pipeline. But besides pressure drop, many other factors must be considered if a conveying system is to operate successfully. This is where expertise and experience comes in. Buying a computer program and plugging in the numbers do not guarantee success unless the user has expertise in pneumatic conveying or gets help from people who have this expertise.

I have written several articles on successful design of a conveying system. I can send a pdf copy if any body is interested.

Users can also get this information from books written by experts like Dr. David Mills.

Regards,

A. T. Agarwal

Consulting Engineer

polypcc@aol.com ■

Ahmed

I have had recent e-mail corresponmdence with Nasser Ismaeil of ECC on what I believe is the same subject you are asking about.

I have provided Nasser with insight and information and now it is time to formalize a working relationship in order to move forward. ■

My article "Theory and Design of Pneumatic Conveying Systems" gives all of the calculation methods that are needed to design a pneumatic conveying system. This article will be published this month. All you need is some basic knowledge of Excel to run the calculations. This information is free. After its publication, I will be able to send a copy to any one who requests it.

Regards,

A. T. Agarwal

Consulting Engineer

Pneumatic Conveying Consulting Services

polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Ordinay Portland Cement is manufactured to close limits and as so much data is available for the material, reliable computer programs are possible and further testing is not necessary. For OPC conveyed through rubber hose or oil well cement conveyed through regular pipeline, for example, where little data is available, testing would be recommended. Testing would always be recommended for any untried material.

68 m3/h of free air at 1.7 bar gauge should be just right for 140 tonne/h of cement in a 250 mm bore pipeline. If 120 tonne/h is being achieved through a 250 mm bore pipeline, a step up to 300 mm bore about 2/3rds of the way along should see an improvement to at least 140 tonne/h. ■

Two-thirds along the length of the pipeline is in terms of the equivalent length of the pipeline and takes account of sections of vertical lift and bends, as well as horizontal pipeline. 2/3rds is just a very approximate figure. It will need to be calculated to get it right for maximum improvement. The critical thing is that the velocity at entry to the larger 300 mm bore section of pipeline should not be lower than that at the start of the pipeline with the 250 mm bore pipe. The further down the line (towards the discharge end) you make it the safer you will be (if you are just going to make a guess) but the percentage improvement will decrease. ■

Dear Grundos 2004

You may recall we offered you a proposal for our services to provide a complete design recview of your situation and offer our technical recommendations which included the possibility of stepping the pipeline if that is an appropriate remedy for your problem.

Incorrectly stepping a conveying line will create more problems than you have originally if you get it wrong on the short side and conceiveably can offer no benefits or minimal benefits if you are too conservative on the long side. ■

Dear Ahmed,

I have already given you the results of my calculations based on the line layout that you sent me. Dr. Mills advice is about the same except that the 300 mm step is needed about 1/3 distance from the end point of the conveying line to get the 140 tph rate. But make sure that you don't have a feed limit.

Regards,

A. T. Agarwal

Consulting Engineer

Pneumatic Conveying Consulting LLC

polypcc@aol.com ■

As previously stated, and in agreement with Dr. Mills, I believe the existing compressor has sufficent capability to acheive the rate. I believe there are other problems which limit his capacity.

When a line is stepped as is being suggested in this case, the complete line from the step point to the discharge end must be increased, meaning any diverter valvers on top of the silo bank must also be changed. I believe in this case, there are (4) 250mm valves which would have to be changed as well.

The costs of such a change out can be quite high and in this case, even if the line is stepped as suggested, the higher rate could very well still not be acheived. ■

Depending on the frequency which you change directions, you may want to consider a 300mm WYE fitting with manually operated line blinds to isolate the leg not being used. Line blinds can also be automated if you need to frequently change destinations. ■

It is not imperative to change the diverter valves. Keeping them as they are is another option with a somewhat longer 300 mm line.

Regards,

A. T. Agarwal

Consulting Engineer

Pneumatic Conveying Consulting Services

Email: polypcc@aol.com

Ph and fax: 304 346 5125 ■

Hello, I am very interested in that article. I would appreciate it if you can mail me the copy at skjuan@gmail.com

Thanks. ■

Dear Sir,

Iam interested in getting a copy of your article.

Please send it on info@deeptiair.com

Regards,

Gautam

Originally Posted by Amrit Agarwal

My article "Theory and Design of Pneumatic Conveying Systems" gives all of the calculation methods that are needed to design a pneumatic conveying system. This article will be published this month. All you need is some basic knowledge of Excel to run the calculations. This information is free. After its publication, I will be able to send a copy to any one who requests it.

Regards,

A. T. Agarwal

Consulting Engineer

Pneumatic Conveying Consulting Services

polypcc@aol.com

Ph and Fax: 304 346 5125

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