Name: THIAGO DE FREITAS HULLE SANT'ANNA
Type: MSc dissertation
Publication date: 09/07/2021
Advisor:
Name |
Role |
|---|---|
| ROGÉRIO RAMOS | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| MARCIO FERREIRA MARTINS | Internal Examiner * |
| ROGÉRIO RAMOS | Advisor * |
Summary: The safety of devices and equipment subjected to pressure is directly associated with the dimensioning and correct functioning of a safety valve. For that, it is necessary to evaluate its performance. This work develops and tests methodologies for flow testing, seeking to follow the main standards, in addition to developing a simplified mathematical model that estimates the lift and flow of safety valves that operate with compressed air and atmospheric back pressure.. Four different methodologies were developed to control and carry out the flow capacity test: I) Powered and controlled by the compressor; II) Manually controlled from control valve; III) Automatically controlled with pressure setpoint; and IV) Automatically controlled with flow setpoint. These methodologies were tested on two completely different valves. A mathematical model was developed based on the theory of compressible flow in a convergent nozzle and it had its estimated values compared with three different valves in terms of lift and discharge flow. As for the methodologies, it was observed that Methodology I presents the highest flow variability due to the compressor cycles, Methodologies II, III and IV present values very close to each other, with a maximum deviation of 2.03% and 5.11% in relation to the average of the three methodologies, for the two valves tested. Of these, the execution time of Methodology III stands out, which is less than the others and the IV obtained less variability of the flow. For validation of the experimental apparatus and Methodology III, a valve certified according to the standards of The American Society of Mechanical Engineers (ASME) was tested and a flow rate of 0.95% above the flow stamped on the valve was obtained. The mathematical model, on the other hand, showed a difference between the estimated disk elevation and the experimental elevation of a maximum of 3.94% and a minimum of 0.60%. For the flow rate the mathematical model the maximum difference of 7.36% and minimum of 2.09% in relation to the experimental one.
