Companies, using pneumatic conveying installations in their production process, ask for the design for new installations or, when they have trouble with their existing installation a re-calculation-based solution.
The technical department of most companies do not understand fully the theoretical and physical background of pneumatic conveying. The experience, which the technical department has, is often misinterpreted for this theoretical and physical background and therefore is not fully understanding how a pneumatic conveying system operates.
The main operational characteristics are the safety factor against sedimentation/choking, which is depending on the design pressure at the selected airflow and safety factor of the selected airflow against the location on the Zenz curve at a selected mass flow.
A pneumatic conveying design requires a number of input variables which are necessary to execute a meaningful calculation.
Many calculation requirements from companies are often the based on limited input data:
-Capacity.
-Horizontal length.
-Vertical length.
-Number of bends.
-Material name.
-Bulk density.
Even less understandable are the companies that supply the design input data including the pipe diameter and give the SLR.
In short, users approach pneumatic conveying as a commercial issue, where the designers approach pneumatic conveying as a mathematical/technological matter.
However, the amount of the required input data is much more than that:
-Capacity.
-Geometric drawing of the installation
-Horizontal length.
-Vertical length.
-Number of bends.
-Bend radius
-Material name.
-Material special properties. (Maximum temperature, hygroscopic, abrasiveness, chemical properties, explosive)
-Existing installation. (In this case the operational- and the technical data are used for the verification of the pneumatic conveying characteristics of the material. In many cases, the company cannot supply these data, as they do not know them.)
Asking for the missing information, sometimes results in silence or the wrong feed back. Followed by an ongoing communication.
Involving the technical operator was almost never possible because he was too low in the organization’s management hierarchy.
Equal problems occur when the data of an existing installation must be gathered.
Pneumatic conveying users and -suppliers also tend to communicate at a different level.
Example of communication:
A yard builds a cement/barit/bentonite conveying system on board an offshore rig.
On most rigs a 6” pipeline is installed with lengths ranging from 50m to 175m with a standard airflow.
After installing the contract capacity is found to be 80 tons/hr. and tests resulted in lower performance rates.
Calculation shows that the maximum capacity (just before choking) for the longest pipeline is approx. 50 tons/hr. to 55 tons/hr. at the longest pipeline.
The customer is not pleased and holds the yard to the contract.
The yards ordered the pressure tanks to a sub-contractor and requires a solution.
The tank sub-contractor manufactured the tanks according to the yard’s specification but is willing to assist in looking for a solution and asks another office to execute the calculations and to find a solution.
However, the 6” pipeline is already at the maximum of its conveying capacity and that the only solution to reach the contract capacity is a bigger pipeline and compressor.
This alternative is not accepted by the yard.
Then the questions are coming back from the yard:
-Can we increase the pressure?
-Can we increase the airflow?
(Questions which should have been asked before designing and building)
The answer to those questions to the yard is that a few tons might be gained by a higher pressure and/or airflow at the risk of frequent choking but never reaching the required contract capacity.
The yard informs then that the compressors can deliver 8 barg and that should be enough to reach the required capacity. Why is that not possible? (The communication becomes a bit less pleasant).
More calculations and explanations are submitted with the same results.
After that the communication dies out and eventually stops.
Such a process can last easily for 2 to 3 months.
In this example the yard seems not (willing) to understand that a pipeline has a maximum conveying capacity.
If that was true, there would be no need for bigger pipelines for higher capacities.
The result of this knowledge and communication problem is that there are unfortunately pneumatic conveying installations operating un-efficiently, not meeting operational requirements or not at all.
Although this thread is a bit discouraging, there are a few successful pneumatic conveying engineers in the world who are approaching pneumatic conveying in a mathematical way, supported by developed algorithms and in relation to their own test laboratories and executed field installations.
The problem is that these companies are doing this for a living. ■
Designing a pneumatic conveying installation.
Companies, using pneumatic conveying installations in their production process, ask for the design for new installations or, when they have trouble with their existing installation a re-calculation-based solution.
The technical department of most companies do not understand fully the theoretical and physical background of pneumatic conveying. The experience, which the technical department has, is often misinterpreted for this theoretical and physical background and therefore is not fully understanding how a pneumatic conveying system operates.
The main operational characteristics are the safety factor against sedimentation/choking, which is depending on the design pressure at the selected airflow and safety factor of the selected airflow against the location on the Zenz curve at a selected mass flow.
A pneumatic conveying design requires a number of input variables which are necessary to execute a meaningful calculation.
Many calculation requirements from companies are often the based on limited input data:
-Capacity.
-Horizontal length.
-Vertical length.
-Number of bends.
-Material name.
-Bulk density.
Even less understandable are the companies that supply the design input data including the pipe diameter and give the SLR.
In short, users approach pneumatic conveying as a commercial issue, where the designers approach pneumatic conveying as a mathematical/technological matter.
However, the amount of the required input data is much more than that:
-Capacity.
-Geometric drawing of the installation
-Horizontal length.
-Vertical length.
-Number of bends.
-Bend radius
-Material name.
-Material special properties. (Maximum temperature, hygroscopic, abrasiveness, chemical properties, explosive)
-Bulk density.
-Particle density
-Particle size (distribution)
-Particle shape.
-Particle temperature.
-Particle suspension velocity.
-Ambient conditions (pressure, temperature, RH, altitude above sea level)
-Feeder type.
-New installation.
-Existing installation. (In this case the operational- and the technical data are used for the verification of the pneumatic conveying characteristics of the material. In many cases, the company cannot supply these data, as they do not know them.)
Asking for the missing information, sometimes results in silence or the wrong feed back. Followed by an ongoing communication.
Involving the technical operator was almost never possible because he was too low in the organization’s management hierarchy.
Equal problems occur when the data of an existing installation must be gathered.
Pneumatic conveying users and -suppliers also tend to communicate at a different level.
Example of communication:
A yard builds a cement/barit/bentonite conveying system on board an offshore rig.
On most rigs a 6” pipeline is installed with lengths ranging from 50m to 175m with a standard airflow.
After installing the contract capacity is found to be 80 tons/hr. and tests resulted in lower performance rates.
Calculation shows that the maximum capacity (just before choking) for the longest pipeline is approx. 50 tons/hr. to 55 tons/hr. at the longest pipeline.
The customer is not pleased and holds the yard to the contract.
The yards ordered the pressure tanks to a sub-contractor and requires a solution.
The tank sub-contractor manufactured the tanks according to the yard’s specification but is willing to assist in looking for a solution and asks another office to execute the calculations and to find a solution.
However, the 6” pipeline is already at the maximum of its conveying capacity and that the only solution to reach the contract capacity is a bigger pipeline and compressor.
This alternative is not accepted by the yard.
Then the questions are coming back from the yard:
-Can we increase the pressure?
-Can we increase the airflow?
(Questions which should have been asked before designing and building)
The answer to those questions to the yard is that a few tons might be gained by a higher pressure and/or airflow at the risk of frequent choking but never reaching the required contract capacity.
The yard informs then that the compressors can deliver 8 barg and that should be enough to reach the required capacity. Why is that not possible? (The communication becomes a bit less pleasant).
More calculations and explanations are submitted with the same results.
After that the communication dies out and eventually stops.
Such a process can last easily for 2 to 3 months.
In this example the yard seems not (willing) to understand that a pipeline has a maximum conveying capacity.
If that was true, there would be no need for bigger pipelines for higher capacities.
The result of this knowledge and communication problem is that there are unfortunately pneumatic conveying installations operating un-efficiently, not meeting operational requirements or not at all.
Although this thread is a bit discouraging, there are a few successful pneumatic conveying engineers in the world who are approaching pneumatic conveying in a mathematical way, supported by developed algorithms and in relation to their own test laboratories and executed field installations.
The problem is that these companies are doing this for a living. ■
Teus