The heated pipes in the receivers are contained in a beam composed of metal cladding and glass. The receiver beam glass are hung in a glass overhead position. By design, the glass must be as thin as possible and with the least reflection as possible. The intent of the receiver is to receive as much light as possible in order to heat the pipes and boil the water efficiently.
A large quantity of receiver’s glass were spontaneously breaking reducing drastically the yield of the solar plant creating long downtime periods.
Background
The concentrated solar power (CSP) plant is the largest solar thermal power plant in Asia and the largest in the world using the linear Fresnel reflective technology.
The 125 Megawatts power is to be generated from 35 Solar Steam Generators (SSG). The Compact Linear Fresnel reflector (CLFR) solar steam generator uses rows of flat mirrors to reflect sunlight onto a linear receiver above the mirror field. The SSG receivers are oriented North/South following the length. The mirrors are setup to track the sun from East to West. Water flows through tubes in the receivers. The concentrated sunlight boils the water in the tubes, generating high pressure superheated steam sent to a generating station.
Solution
Investigation:
A full potential glass breakage investigation was performed on site. nCLO3URE’s engineers identified several potential sources of breakage such as:
- Glass edge damages
- Sharp body impact
- Glass and fixing design
- Quality of fixing material and workmanship
- Excessive loads and structure movements
- Inclusions in glass
- Extenuating circumstances
Testing:
Tension/compression stress was measured in the tempered glass on site using ASTM C 1279-136 Standard Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully Tempered Flat Glass Procedure A using a Grazing Angle Surface Polarimeter (GASP)
