TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: The system (s1) comprises: a disproportionation system in which trichlorosilane is converted to silane, and a fluidized bed reactor in which silane is decomposed to produce polycrystalline silicon; a conveying apparatus for conveying trichlorosilane from the hydrogenation reactor to the disproportionation system, a conveying apparatus for conveying silane from the disproportionation system to the fluidized bed reactor, a conveying apparatus for conveying trichlorosilane from the chlorination reactor to the disproportionation system, and a conveying apparatus for conveying silicon tetrachloride from the disproportionation system to the hydrogenation reactor; a separation system to which hydrogen, hydrogen chloride, silicon tetrachloride and trichlorosilane are introduced to separate hydrogen, hydrogen chloride and the chlorosilanes; and a conveying apparatus for conveying trichlorosilane and silicon tetrachloride from the separation system to the disproportionation system, a conveying apparatus for conveying hydrogen chloride from the separation system to the chlorination reactor, a conveying apparatus for conveying hydrogen from the separation system to the hydrogenation reactor, a conveying apparatus for conveying hydrogenated gas from the hydrogenation reactor to the separation system, and a conveying apparatus for conveying chlorinated gas from the chlorination reactor to the separation system. The disproportionation system comprises: a first distillation column for separating silicon tetrachloride into a bottoms fraction and to separate dichlorosilane and trichlorosilane into an overhead fraction; a second distillation column for separating trichlorosilane into a bottoms fraction and dichlorosilane into an overhead fraction; a first disproportionation reactor for producing a first disproportionation reactor product gas comprising dichlorosilane and silicon tetrachloride; and a second disproportionation reactor for producing a second disproportionation reactor product gas comprising silane and trichlorosilane; and a third distillation column for separating silane into an overhead fraction and trichlorosilane into a bottoms fraction. The separation system comprises: a chlorosilane separator for separating trichlorosilane and silicon tetrachloride from hydrogen and hydrogen chloride; and a hydrogen separator for separating hydrogen from hydrogen chloride. The chlorosilane separator is a vapor-liquid separator. The hydrogen separator is a vapor-liquid separator or a bubbler. The system (s1) comprises a stripper column to remove light end impurities prior to introduction of silicon tetrachloride and trichlorosilane into the disproportionation system.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The trichlorosilane is introduced into a disproportionation system to produce silicon tetrachloride and silane; silane produced from the disproportionation system is introduced into a fluidized bed reactor to produce polycrystalline silicon and an effluent gas comprising hydrogen and unreacted silane; and trichlorosilane produced from the chlorination reactor is introduced into the disproportionation system to produce silicon tetrachloride and silane. The disproportionation system comprises a first distillation column, a second distillation column, a third distillation column, a first disproportionation reactor and a second disproportionation reactor, and the method involves: introducing trichlorosilane and silicon tetrachloride produced from the chlorination reactor and dichlorosilane produced from the first disproportionation reactor into the first distillation column to separate silicon tetrachloride into a bottoms fraction and to separate dichlorosilane and trichlorosilane into an overhead fraction; introducing the overhead fraction produced from the first distillation column into the second distillation column to separate trichlorosilane into a bottoms fraction and dichlorosilane into an overhead fraction; introducing the bottoms fraction produced from the second distillation column into the first disproportionation reactor to produce a first disproportionation reactor product gas comprising dichlorosilane and silicon tetrachloride, and is introduced into the first distillation column; introducing the overhead fraction produced from the second distillation column into the second disproportionation reactor to produce a second disproportionation reactor product gas comprising silane and trichlorosilane; introducing the second disproportionation reactor product gas into the third distillation column to separate silane into an overhead fraction and trichlorosilane into a bottoms fraction; introducing the bottoms fraction produced from the third distillation column into the second distillation column; and introducing the overhead fraction produced from the third distillation column into the fluidized bed reactor to produce polycrystalline silicon. The bottoms fraction produced from the first distillation column is introduced into the hydrogenation reactor to produce trichlorosilane and hydrogen chloride. The silicon tetrachloride and hydrogen are introduced into the hydrogenation reactor to produce a hydrogenated gas comprising trichlorosilane, hydrogen chloride, unreacted hydrogen and unreacted silicon tetrachloride; the hydrogenated gas being introduced into a separation system to separate trichlorosilane and unreacted silicon tetrachloride from hydrogen and unreacted hydrogen chloride; and the trichlorosilane and unreacted silicon tetrachloride being introduced into the disproportionation system. The chlorinated gas is introduced into a stripper column to remove light end impurities prior to introduction into the disproportionation system. Preferred Components: The chlorinated gas comprises trichlorosilane, silicon tetrachloride, hydrogen and unreacted hydrogen chloride, where the chlorinated gas is introduced into the separation system. The ratio of hydrogen chloride added as a make-up to the amount of hydrogen chloride circulating within the closed-loop process is less than 1:10, less than 1:20, less than 1:50, less than about 1:100, 1:250 to 1:10 or 1:100 to 1:20. The ratio of hydrogen gas added as a make-up to the amount of hydrogen circulating in the closed-loop process is less than 1:10, less than 1:20, less than 1:50, less than 1:100, 1:250 to 1:10 or 1:100 to 1:20. The molar ratio of chlorine added as a make-up to polycrystalline silicon product that is produced is less than 2:1, less than 1:1, less than 1:1.2, less than 1:1.5, less than 1:2, less than 1:2.5, 2:1 to 1:5 or 1:1 to 1:5. The molar ratio of hydrogen added as a make-up to polycrystalline silicon product that is produced is less than 1:1, less than 1:2, less than 1:3, less than 1:5, less than 1:10, 1:1 to 1:20 or 1:2 to 1:10. EXAMPLE - No suitable example given.