Tetra has published a series of guides which are available for ordering.
Inspection is part of routine maintenance for any Heat Recovery Steam Generator (HRSG). Visual inspections are performed at regular intervals in accordance with the requirements of regulatory bodies and insurers.Inspection is part of routine maintenance for any Heat Recovery Steam Generator (HRSG). Visual inspections are performed at regular intervals in accordance with the requirements of regulatory bodies and insurers.
A selection of technical papers available for reference.
Selected papers, presentations and articles from major industry conferences and events.
With over 30 years of experience in power and industrial steam generation services, Tetra Engineering has along history of projects.
Tetra was engaged by a client to perform a finite element analysis of the HP Bypass valve reducer, using measured displacements as input. Results from a strain gauge/displacement survey showed a large strain effect occurring during the start-up of the boiler. Initially, both the left and right side strain gauges on the reducer showed compressive strain. During the start something triggered the reducer to experience tensile strain that differed in its intensity between left and right. The purpose of the study was to try to simulate the observed strain fields and determine the root cause.
A Tetra Senior Engineer visited a south east asian power plant site to make an assessment of the commissioning situation. The EPC engaged Tetra as they considered that their site work was being delayed due to lack of progress by the IPP to perform their scope of work.There was significant lack of communication between the two parties as well as discrepancies in the scope of work, which lead to schedule delays and cause of mutual blaming between parties.
Tetra was hired by a client to investgate the remaning life of the HEP on 3 units of a thermal power station. The plant intended to operate the units for another 100,000 hours. The scope of work entailed a piping stress analysis of the main steam and hot reheat lines, thermal stress analysis of the SH header outlet/main steam line and remaining life assessment (creep, fatigue, creep-fatigue) of critical areas based on inspection history and results from the pipe stress/finite element analysis. The figure shows time-dependent stresses and temperatures during start up.
During the shutdown of the unit at night, the HP bypass was kept open to maintain a vacuum in the steam turbine condenser in order to guarantee a faster start the next morning. Therefore, a small quantity of high pressure steam from the HP drum was flowing through the SH on the way to the HP bypass valve. The small HP steam flow takes the path of least resistance and only goes through tubes on one side of the unit, affecting their temperature. The temperature of the tubes on the other side change differently and a temperature difference of around 80°C can be seen 2 hours after shutdown. The CCGT owner engaged Tetra Engineering to investigate the impact of these resultant cyclic loads on the fatigue life of the tube to header welds. The study concluded that the temperature difference of 80°C between different tubes does not cause high enough fatigue stresses alone to be considered critical
