Research and development
As well as using the latest heat exchanger thermal simulation software available on the market, Fives Cryo has developed its own software: ProSec. This software is the result of nearly 20 years' investment in R&D and tests validating the performance and operation of Fives Cryogenie heat exchangers. It is used for the thermal and hydraulic simulation of heat exchanger assemblies, taking into account their process environment. In addition to steady-state conditions, ProSec can simulate the operation of heat exchangers in transient conditions in order to assess the thermomechanical stresses and guarantee the equipment integrity.
A wide range of fin types is available for selection by Fives Cryo engineers, in order to reduce customer's total plant costs while ensuring full compliance with specifications. For this purpose, the fins are tested to measure their pressure drop and heat transfer characteristics. In particular, these tests are conducted on brazed fins so that the results obtained are truly representative of actual performances in the heat exchanger.
Furthermore, the quality of fins is guaranteed by measuring their pressure drop during manufacturing, in addition to conducting geometric and micrographic inspection.
Brazing is undeniably one the key phases of the heat exchanger manufacturing cycle, and the quality of the brazed matrix depends on the success of this phase.
Therefore, full control of this operation has always been considered by Fives Cryo as being of paramount importance.
To this end, the two vacuum brazing furnaces were equipped, one after the other, with a special regulating system in order to achieve real-time predictive control under stress of the brazing thermal cycle, by mapping the actual temperature of heat exchangers at every moment of the brazing operation. Further progress has been made more recently by developing new 3D software which can simulate the brazing thermal cycle in advance.
By integrating all the predictive regulating logic and all the equipment's design data, this package optimises all parameters, and, it can be used as early as during design phase.
Mechanical design and reliability
The mechanical design and engineering rules that we apply are based on design codes. Our mastery in the field of reliability is supported by our expertise in the local behaviour of the heterogeneous structure of brazed equipment. We are able to ensure equipment reliability and durable service thanks to our knowledge of local stresses.
The sensitive areas of each apparatus, typically the attachment of headers on the matrix, are subjected to pressure loads and thermal gradients. They can be verified by finite-element analysis using our PC Diam software. It is impossible to model our heterogeneous structures satisfactorily with conventional software. We therefore developed our own tools to process these complex models, as conventional software is unable to deal with them.
Pipes are the interface between our equipment and the rest of the customer's plant. To maximize the synergy of our design for our customers, we select the most efficient software and integrate our expertise in flexibility calculations at the design stage.
Transient thermomechanical simulation
After a given period of time, the system reaches a steady state which constitutes sufficient information as far as the process is concerned. But when changes in operating conditions occur, high temperature gradients may occur, generating thermomechanical stresses.
However, this type of computation is difficult to implement and entails determining thermomechanical stresses and their changes versus time, on the basis of the temperatures obtained in the transient thermohydraulic computation. The modeller we have developed (HomPass, Siteme) covers even the smallest details (fins, clearances, plates, orientations, etc.), and enables us to propose a design allowing for fluctuations of operating conditions.
Mechanical and thermal design
Our engineers and technicians work together to build equipment on the basis of customer specifications. They select the best possible thermohydraulic compromise to optimise heat exchange capacities, thermal performances, pressure drops, process-fin compatibility, equipment safety and overall dimensions. The mechanical design, based on customer specification and preliminary hydraulic studies, ensures performances in compliance with applicable codes and standards (ASME, PED, etc.), design conditions (earthquakes, wind, transport and handling), site installation requirements, customer interfaces, flexibility and thermal contractions, external loads and instrumentation.
To achieve this high level of excellence, Fives Cryo collaborates with exceptional partners : renowned universities and engineering schools, laboratories and clients, and the results obtained are properly validated: simulation computations, on-site measurements, continuous quality control and measurement of fin performances during manufacture.