INTRODUCTION

Tube & Shell types of heat exchangers have their design procedure defined in ASME & TEMA Standards. But in some cases, the equipment are designed as per ASME Standards alone (e.g. Heat Exchanger for Air-cooled processing fluid). So such design needs FEA assistance in order to decide whether the design is safe or not ??

Process equipment manufacturer from India & Abroad approached ANALYZER to seek assistance in evaluating the design of their newly developed heat exchangers for a particular application to multiple loading conditions using simulation techniques & provide the solution in case of any observed failure either stress failure or tube to tube sheet weld failure.

FEA WORKFLOW

• Design parameters & material properties extraction for Heat exchanger geometry
• Preparing FEA Model for Heat Exchanger with complete structured Hexahedral Mesh.
• Solving the FEA Model & Result extraction
• Performing the weld qualification calculations for a tube to tube sheet welds.
• Preparing an easy to understand report for the performed FEA.

CHALLENGES

• Preparing complete structural hexahedral mesh without losing small geometrical details.
• Optimizing the mesh count in case of bigger heat exchangers
• Modeling the weld between tube & tube sheet.

THE SOLUTION

The heat exchanger was analyzed for different loading conditions as per Table 5.3 of ASME BPVC Sec. VIII Div. 2 using Finite Element Analysis in ANSYS APDL Solver. Stress Linearization has been carried out at various locations. The tube to tubesheet weld qualifications was performed for the weld. The results showed that the induced stresses were well within the acceptable limits as per guidelines. Also, the load at the weld junction is found to be much below the allowable limit. Hence, the structure’s design was predicted to behave safely during operation without premature failure.

BENEFITS

• Actual behavior of heat exchanger for the different load conditions is evaluated.
• Reduced manufacturing time
• The most critical component of heat exchanger tube sheet is also evaluated for its strength.