Dear Piechbi,

Assuming from the bulk density of 950 kg/m3, you are referring to hydrated lime (Ca(OH)2.

The particle density is then approx. 2200 kg/m3.

Assuming an average particle size of 6500 micron (6.5 mm), the suspension velocity of a particle becomes 17.2 m/sec.

Assuming a pipe diameter for your installation of 154 mm (6”), the preliminary calculation results are as follows:

Capacity 39 tons/hr at 2 bar (excluding time required for changing kettles)

Compressor volume = 1.55 m3/sec # 92 m3/min (To prevent sedimentation in the beginning of the pipeline)

SLR = 7.8

Air velocities from 33 m/sec to 86 m/sec

Power 277 kW

Energy consumption 7 kWh/ ton.

To reach approx 70 tons/hr, an 8” pipeline with a 165 m3/min compressor would be required.

The conclusion is that pneumatic conveying is not feasible due to the big particle size, leading to a high suspension velocity and consequently to very high air volumes and velocities.

A similar project in the past for burned lime, which was built, gave the same conclusion for the pressure conveying part.

In addition, it was noticed that the deterioration of the lime was very high, which explained the high material loss factor.

Have you already asked for a vendor’s opinion?

Are you already those trains pneumatically, and if so, what are the operational data? A more accurate calculation is then possible, as the lime conveying properties can then be derived.

Have nice day

Teus ■

I think that a suitable pneumatic conveying system can be designed but the main problem may be the free flow of this material from the hoppers into the bottom 5 inch dia pipeline if we supply all of the conveying air to the top of the hoppers.

To solve this problem, most of the conveying air should be supplied to the beginning of the pipeline.

To minimize particle attrition, conveying velocity should be reduced by using a stepped pipeline.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Dear Piechbi,

The material density of quick lime (CaO) is approx 3350 kg/m3, instead of 2200 kg/m3 for hydrated lime. (Wikipedia)

Although, because of the irregular shape, the particle density can be lower and the drag factor can be rather high.

I expect that the suspension velocity will be approx. between 15 and 17 m/sec.

This results in calculation outputs similar to the outputs already given.

It is not stated that pneumatic conveying of quick lime is impossible.

It is possible and it has been done before.(Suction and pressure)

However the pressure conveying proved not to be economic and was later on replaced by a conveyor belt.

The particle deterioration was so high that the conveying equipment in the plant where the quick lime was processed could not handle the high amount of generated fines, for which that equipment was not designed.

Transporting the quicklime in a powdery form of 100 to 200 microns would make your project feasible.

Have a nice day

Teus ■

Good Day

The fully optimized use of a pressure differential rail car is typically limited because of the discharge size of the pipe manifold on the car.

When the conveying distances are long or the desired capacity is high, the discharge line needs to very quickly be expanded into a larger line size. The problem of course becomes the issue of velocity as the car's manifold piping can only pass so much air.

On a recent project, the unloading of fly ash from a PD car with a 5" discharge connection was limited to approximately 4-6 hours due to the small line size all the way to the silo. By connecting the 5"discharge line on the car to a larger pipe diameter and providing the necessary make up air through an air management system and pipe augmentor, we were able to empty that same PD rail car in just over an hour.

Your situation sounds like it can benefit from a similar approach ■