Pipe orifice annealing technique for all-glass vacuum thermal-collecting tube

Abstract

The annealing process of mouth in all glass vacuum heat collecting pipe is baking and exhausting air immediately after fusing and sealing the mouths of both inner pipe and outer pipe of the heat collecting pipe. The pipe mouth annealing temperature and time are dependent on the glass material and stress, and for high boron silica glass, the pipe mouth annealing temperature is 570 deg.c and the annealing time is 3-4 min. There are two sets of heater and two sets of temperature controller separately for annealing and baking and exhausting air.

Description

technical field [0001] The invention relates to an all-glass vacuum heat collecting tube (hereinafter referred to as heat collecting tube) nozzle annealing process, which belongs to the technical field of solar energy production. Background technique [0002] Nozzle annealing is an important step in the production of heat collecting tubes. The purpose is to eliminate the permanent stress generated when the inner tube and the outer tube are welded and sealed, and improve the mechanical strength of the heat collecting tube. It is widely used in the process of heat collecting tube production. The production process is to anneal the nozzles in a horizontal gas annealing furnace immediately after the nozzles of the inner tube and the outer tube are sealed, and then bake and exhaust. [0003] The use of this production process is due to the difficulty in controlling the gas pressure and composition, resulting in fluctuations in the annealing temperature between 550 and 650°C, resu...

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Problems solved by technology

[0003] The use of this production process is due to the difficulty in controlling the gas pressure and composition, resulting in fluctuations in the annealing temperature between 550 and 650°C, resulting in inconsistent annealing effects; and the temperature of the inner tube and the outer tube is difficult to match, resulting in poor annealing effect of the inner tube, and some There are still stress residues that affect the mechanical strength of the heat collecting tube

In addition, only the nozzle is locally heated, and the temperature gradient with other positions reaches 600°C, so it cannot be annealed as a whole, and it is also not conducive to product quality tracking and automatic transformation of the production process.

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