Method for producing silicic acid with variable thickening
A process for production of silica having variable thickening wherein a) a product stream I containing at least a vaporous, hydrolysable and/or oxidizable silicon compound, b) a product stream II containing oxygen and c) a product stream III containing at least a combustible gas are made to react, where d) a feed port in a pipepiece A, the pipepiece A containing one or more static mixing elements, is used to import product stream I into product stream II, or vice versa and thereby create product stream IV, then e) a feed port in a pipepiece B, the pipepiece B containing one or more static mixing elements, is used to import product stream III in product stream IV and thereby create product stream V, f) product stream V leaving pipepiece B is imported into a reaction chamber, ignited therein and reacted in a flame, and g) the resultant solid material is separated off.
1. A process for production of silica having variable thickening, the process comprising reacting:
a) a product stream I comprising at least one silicon compound selected from the group consisting of a vaporous silicon compound, a hydrolysable silicon compound, and an oxidizable silicon compound,
b) a product stream II comprising oxygen, and
c) a product stream III comprising a combustible gas,
wherein the process comprises:
importing product stream I into product stream II, or importing product stream II into product stream I, through a feed port in a first pipe piece A to create product stream IV, wherein the first pipe piece A comprises at least one static mixing element;
importing product stream III into product stream IV, through a feed port in a second pipe piece B to create product stream V, wherein the second pipe piece B comprises at least one static mixing element;
importing product stream V leaving the second pipe piece B into a reaction chamber, igniting the reaction chamber, and reacting the product stream V in a flame; and
separating solids resulting from igniting the reaction chamber and reacting the product stream V in the flame,
wherein V B is a velocity with which the product stream III comprising a combustible gas is imported into the product stream IV, wherein V B is at least 50 Nm/s.
2. The process according to claim 1 , wherein the at least one static mixing element of the first pipe piece A and of the second pipe piece B is designed as a flange mixer.
3. The process according to claim 2 , wherein the flange mixer has a single punctiform feed port.
4. The process according to claim 1 , wherein V B is a velocity with which the product stream III comprising a combustible gas is imported into the product stream IV, and V A is a velocity of the product stream IV at a point of importing the product stream III comprising a combustible gas, wherein V B /V A is at least 4.
5. The process according to claim 1 , wherein V A is a velocity of the product stream IV at a point of importing the product stream III comprising a combustible gas, wherein V A is at least 15 Nm/s.
6. The process according to claim 1 , wherein L A /D A is =2 to 20, where L A =length of pipepiece A, and D A =internal diameter of the first pipe piece A.
7. The process according to claim 1 , wherein L B /D B is =2 to 20, where L B =length of pipepiece B, and D B =internal diameter of the second pipe piece.
8. The process according to claim 1 , wherein an amount of oxygen is at least sufficient to convert the at least one silicon compound and the combustible gas.
9. The process according to claim 1 , wherein the at least one silicon compound is selected from the group consisting of SiCl 4 , CH 3 SiCl 3 , (CH 3 ) 2 SiCl 2 , (CH 3 ) 3 SiCl, (CH 3 ) 4 Si, HSiCl 3 , (CH 3 ) 2 HSiCl, CH 3 CH 2 CH 2 SiCl 3 , Si(OC 2 H 5 ) 4 , Si(OCH 3 ) 4 , and mixtures thereof.
10. The process according to claim 1 , further comprising introducing a product stream VI comprising oxygen and/or steam into the reaction chamber.
11. The process according to claim 1 , further comprising cooling a reaction mixture leaving the reaction chamber to form a cooled reaction mixture and treating the cooled reaction mixture with steal before separating the solids.