  |
Thermoplastic Scrubber
Project Description
An aboveground welded thermoplastic scrubber had to be built in a draining piping system for gas waste products from a technological process. The vessel is equipped with a nozzle system for spraying liquid in the washing process for waste gas.
Technical data
Diameter 1800 mm
Height 4350 mm
Weight 750 kg
Program
SMART Modeller - ESA-Prima Win version 3.60 Modules
Linear static analysis of shells Intersections
Stability of shells
Intelligent document |
|
Experience
The design of thermoplastic process equipment, using the appropriate design parameters and material properties can be completed with a combination of hand calculations and computer run Finite Element Analysis (FEA). FEA is necessary to determine peak stresses at discontinuities, corner joints, and to verify strain limits etc. For a complete FEA analysis, which has to be executed for thermoplastic process equipment, a non-linear analysis should be accomplished. However, this is usually impractical due to time, lack of detailed material strength design data, and the relatively low allowable design stresses used.
Satisfactory designs have been consistently accomplished by using a linear elastic FEA approach and by using a constant on required years of durability dependent creep modulus value for the design allowable stresses. Measurements of fabricated thermoplastic structures indicate the linear elastic approach to be a viable and relatively accurate prediction of equipment stresses and deformations.
Conclusion
A complicated shape of thermoplastic vessels requires powerful tools for simplifying the creation of the geometry - intersections are a necessity. Several linear solutions of the structure, varying from creep modulus in relationship to the temperature, time of load exposition and reached stress level must be analysed. Each of the linear analysis must also be complemented by a stability check of the construction for the same creep modulus value.
Sometimes the stability analysis does not give the positive values of the critical factors, depending on the geometry, loads and supports. Then the geometrical non-linear analysis
must be used to find out the remaining load bearing capacity of the structure, several nonlinear analysis with regularly increased loads have to be performed till the collapse of the solver gives the critical load factor value. The number of equations solved normally varies between 100.000 - 1,000.000. So the requirements for a really fast solver are great, mostly the iterative solver is used. All mentioned features are included in ESAPrima Win software, the best solution for FEA of the thermoplastics vessels I have ever used. |
 |
