This work is focused on the diagnosis of behavior, from the point of view of control emissions and noise level, of a power Turbogas plant during the process of commissioning, to guarantee that its operation complies with national and international standards. The environmental diagnosis of the power plant was developed as part of the performance evaluation of the unit. The conditions of the unit evaluation include operation at base load and partial load, as well as time periods for load changes. The evaluated power plant consists of an aeroderivative gas turbine installed in a simple cycle, operating with a cooling system (chiller) installed in the urban zone of Mexico City. Therefore, it should comply with the legislation and regulations of the city concerning air pollution and allowed noise, besides the international standards established by the manufacturer. The study includes emissions measurements using a Continuous Emissions Monitoring System installed in-situ, previously calibrated and checked during and after the test which was found inside the permissible deviation of 3%. Measurements were recorded at intervals of 5 minutes during test periods of 110 minutes for each load and 45 minutes for load changes. On the other hand, noise pressure evaluation was carried out in near field as well as far field produced by the power plant during operation. Measurements were carried out by using precision instruments installed specifically for it. A temporary system for obtaining data was used to monitoring the environmental conditions every 30 seconds. It was possible to verify that the turbogenerator complies with all noise levels and contaminant emissions requirements and regulations according to the limits established by the manufacturer and national and international standards.

This paper provides an overview of a steam turbine low pressure blades failures induced by flow excitation and blades torsional vibrations due to sudden changes on the grid. The analysis include L-0 and L-1 blades failures of the 110 MW [1], 28 MW [2] and 35 MW [3] geothermal units induced by unstable flow due to operation at low load low vacuum, and L-0 blades failure of the 660 MW [4] nuclear unit due combined effect of a transient phenomenon provoked by sudden load changes on the grid and some low vacuum operation period. The failure initiation was registered at different zones of the blades depending on the case, and were localized at the blades cover segments, blade root and blade airfoil close to the platform. Laboratory evaluation of the blades fracture surface indicates the failure mechanism to be high cycle fatigue (HCF).

In order to evaluate the performance of new turbo gas power plants for putting in commercial operation, it was necessary to supervise, test and, if so the case, to approve the works of commissioning, operational and acceptance of all equipments and systems that constitute the power plant. All this was done with the aim of guaranteeing the satisfactory operation of these elements to accomplish the function for which they were developed. These activities were conducted at the request of the customer to confirm and observe that the evidence of the tests was carried out according to the specifications and international regulations. The putting into commercial operation activities were done in collaboration with the supplier and manufacturer of equipment, the client and the institution responsible for certification and approval of the plant. All this in a logical and chronological order for the sequence of commissioning tests, operation and acceptance. Commissioning tests were carried out on-site at normal operating conditions, according to the design and operation needs of each power plant of a group of 14. Once the commissioning tests were completely executed and in a satisfactory manner, operational tests of the plants were developed. This was done by considering that they must operate reliable, stable, safe and automatically, satisfying at least, one hundred hours of continuous operation at full load. After evaluating the operational capacity of the machine, it was necessary to determinate the quality of the plant by carrying out a performance test. Finally, it was verified if every unit fulfills the technical requirements established in terms of heat capacity of the machine, noise levels and emissions. As a result of this process, it is guaranteed to the customer that the turbo gas power plants, their systems and equipments, satisfy the requirements, specifications and conditions in agreement with the supplier and manufacturers referring to the putting into commercial operation of the plant.

This article presents the supervision and testifying process during the start of commercial operations of several turbogas plants generating electricity rate of 32 MW each fuelled by natural gas. Supervision and testifying process were conducted at the request of the customer to confirm and observe that the evidence of commissioning, testing and operation of acceptance tests were carried out as specified by international regulations, calling the outcome of each tests agree the applied rules. The work was done in collaboration with the supplier and manufacturer of equipment, the client and the institution responsible for certification and approval of the plant. All this according to a logical and chronological order for the sequence of tests commissioning, operation and acceptance. Tests for putting into service are carried out on-site at normal operating conditions, according to the design and operation needs of the plant. Once implemented in full and in a satisfactory manner, test operation of each plant was carried out considering that they must operate automatically, reliable, stable and secure, fulfilling at least, one hundred hours of operation at full load. After completed operation tests are conducted, acceptance testing on the power plant and integrated approach to assessing the quality of the product were accomplished. Finally, it was verified if each unit meets the technical requirements established in terms of thermal capacity of the machine, noise levels and emissions. As a result of this supervision and testifying process, it is guaranteed to the client that the power plants and all their equipment, comply with the requirements, conditions and specifications in agreement with the supplier, concerning test of putting into service, operational and acceptance tests.

A last stage turbine blades failure was experienced in two units of 660 MW. These units have one high-pressure turbine and two tandem-compound low-pressure turbines with 44-inch last-stage blades. The blades that failed were in a low pressure (LP) turbine connected to the high pressure (HP) turbine (LP1) and in LP turbine connected to the generator (LP2). The failed blades had cracks in their roots initiating at the trailing edge, concave side of the steeple outermost fillet radius. Laboratory evaluation of the cracking indicates the failure mechanism to be high cycle fatigue (HCF). The last-stage blades failure evaluation was carried out. The investigation included a metallographic analysis of the cracked blades, natural frequency test and analysis, blade stress analysis, unit’s operation parameters and history of events analysis, fracture mechanics and crack propagation analysis. This paper provides an overview of this failure investigation, which led to the identification of the blades torsional vibrations near 120 Hz and some operation periods with low load low vacuum as the primary contribution to the observed failure.

Steady-state analysis of heat transfer in a base-load power generation gas turbine was conducted by thermal conjugation inside and outside of the first stage nozzle, which consists of thermal convection and conduction by coupling of fluid flow and solid body. A computer CFD code was used to solve the problem. The principal issues of the work were concerned with three-dimensional behaviors of the temperature distribution of the nozzle vane, which are influenced by inlet gas flow conditions, internal cooling conditions and film cooling conditions. The numerical results of the effects of cooling flow rate and temperature on heat transfer rates in the nozzle are also presented. The paper focuses on the estimation of the temperature distribution on the nozzle vane by prediction of the thermal environment around the nozzle vane and heat conduction in the nozzle which is necessary to carry out the nozzle thermal load analysis and finally life assessment. Also, the evaluation of service induced degradation of cobalt base alloy FSX-414 of the nozzle, after 24000 hours of operation at high temperature is presented. The assessment includes the nozzle carbides precipitation and grain type and size characterization.