Dear Luca,

Wheat gluten can be conveyed pneumatically.

see:

Schenckprocess

http://www.accuratefeeders.com/FoodBrochure.pdf

Issues in pneumatic conveying are, as usually, the flowing properties of the product and additional requirements for the food industry, s.a. stainless steel equipment and/or nitrogen as conveying gas.

For your product, the associated technological issues can best be solved by a company, experienced in manufacturing these installations for the food industry.

Trying to build an installation without sufficient experience is not recommended.

Best regards ■

Dear Luca,

Because this is an existing installation, it is possible to do some investigation.

How long has the installation been operating and since when is the sedimentation/caking problem existing?

If the problem manifested just a short while ago, are there any known changes in the process, the gluten or the equipment?

Has the shown layer reached the maximum thickness?

The picture shows caking along the pipe wall.

Possible causes:

-The gluten is sticky and glues to the pipe wall

-The gas velocity is too low, whereby the wall velocity is not high enough to keep the gluten particles in suspension. A layer of gluten deposit formed at the bottom of the pipe could also indicate that.

-The gluten is sticky and forms agglomerations of gluten particles, which will have a higher suspension velocity than the original particles. A higher suspension velocity requires a higher gas velocity.

A recalculation of the installation could indicate also some causes.

Therefore a description of the installation is required as well as the particle density, bulk density and the particle size of the gluten.

Best regards ■

Originally Posted by LBa77

Thank you.

The system is already installed

It's normal this layering?

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

The layering (material's build-up) on the hopper wall is most likely due to lack of mass flow in the hopper. In mass flow, all of the material, across the entire cross-section of the hopper, is in motion when the flow of the material out of the hopper is started. There are no static zones. For mass flow design, it is important that the hopper design is based on the flow properties of the material, such as the angle of internal friction and the angle of wall friction. Build-up on the wall can be reduced by using a slick internal surface.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com ■

Is the picture showing:

- a conveying pipe? Which I assume.

- a hopper cone?

Mr. Luca, please clarify

Best regards ■

Dear Luca,

As the picture is showing a pneumatic conveying pipe section to the screen, it cannot be a problem with “lack of mass flow in the hopper”.

Again:

A recalculation of the installation could indicate also some causes.

Therefore a description of the installation is required as well as the particle density, bulk density and the particle size of the gluten.

Have you checked that there is no moisture condensation in your pneumatic conveying system?

Best regards ■

Originally Posted by LBa77

Thank you.

The system is already installed

It's normal this layering?

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Dear Sir,

From your limited information about whether this coating problem is in conveying pipelines or in storage hoppers, I had responded assuming that the problem was in hoppers. But now as it looks like that your problem is in pipelines my response is:

Coating of the conveyed material along the internal surface of conveying lines is quite common for some materials when the conveying velocity is not high enough. This is because of velocity is not the same across the entire cross-section of the pipe but is highest at the geometric center and lowest along the wall. The contour of the velocity is parabolic. Velocity at the wall can be 20 % lower than at the center. This coating occurs more often in the beginning of the pipeline because the material is still accelerating in this zone. Material's properties such as its compressive strength are the main reason.

To solve your problem, you may try increasing the conveying velocity, or by conveying a brittle material after conveying gluten.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com ■

Very typical of lean phase system build up of very fine hydroscopic powder in conveying pipes.

There are two possible reasons for the build up.

1. Wet conveying air from roots blower.

2. Low solids loading ratio.

Solution is simply use dense phase conveying. The conveying air should be dried to +3 deg C

and the plugs sliding on the pipe will keep it clean. ■