Abstract: A radiation-heated fluidized-bed reactor and a process for producing high-purity polycrystalline silicon by using this reactor are provided. In this reactor, a heater device (14) is a radiation source for thermal radiation which is arranged outside the inner reactor tube and as a cylinder around the heater zone, without being in direct contact with the inner reactor tube. The inner reactor tube is designed in such a manner that it uses thermal radiation to heat the silicon particles in the heating zone to a temperature which is such that the reaction temperature is established in the reaction zone.

Abstract: A disc slide conveys pure granules or dusts, and can be mounted between a feed pipeline and a discharge pipeline. The disc slide comprises a casing which includes a valve seat comprising two sealing discs and a shut-off element, which is held movably therein and is in the form of a slide plate, and an actuation element for the slide plate. The valve seat and the slide plate are provided with a surface made from silicon or quartz glass or consist of these materials.

Abstract: A gastight shut-off device (1) which can be fitted between a supply pipeline (2) and a discharge pipeline (3), in the form of a ball valve, includes a housing (4), a housing flow passage with an inlet section (5) and an outlet section (6), a shut-off ball (7) with a shut-off ball flow passage (8), the shut-off ball (7) being mounted in the housing (4), if appropriate by means of two sealing rings (9, 10), and an actuating drive (11) for the shut-off ball (7); and inlet section (5) is designed in such a manner that it reaches into the shut-off ball flow passage (8), which is designed in such a manner that, in the event of the ball valve closing through rotation of the shut-off ball (7), that part of the inlet section (5) which reaches into the shut-off ball flow passage (8) is accommodated in a slot in the shut-off ball.