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US 6,332,949 B1Granted
Method for upgrading used sulfuric acids
AssigneeBayer Aktiengesellschaft
InventorsHeiko Beckhaus, Jürgen Münnig, Wolfgang Lorenz, Karl Schumacher
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Abstract
A process for concentrating spent sulphuric acids particularly sulphuric acids which arise during the nitration of hydrocarbons with nitric acid in the presence of sulphuric acid, wherein single- or multi-stage concentration is effected under vacuum.
Claims2
A process for concentrating spent sulfuric acid comprising
- a) feeding spent sulfuric acid to an evaporator,
- b) heating the spent sulfuric acid to a temperature that is sufficient to cause evaporation of water under subatmospheric pressure and to form a gas phase, which is loaded with water vapor and additionally contains sulfuric acid, and to form a concentrated bottom product,
- c) bringing the gas phase above the bottom product into contact with an aqueous phase that is provided at a rate that ranges from about 10 to about 1000 kg/hour of aqueous phase, per 1000 kg/hour of vapors, wherein the sulfuric acid contained in the gas phase is absorbed by the aqueous phase and a second gas phase, which is substantially free from sulfuric acid is obtained, and wherein the aqueous phase is provided by injection into the gas phase below a demister in co-current flow with the gas phase, and
- d) returning the aqueous phase from c), which contains sulfuric acid, to the bottom in the form of drops which are formed on a demister which is mounted above the bottom.
1 more element
A process for concentrating spent sulfuric acid comprising:
- a) feeding spent sulfuric acid to an evaporator,
- b) heating the spent sulfuric acid to a temperature that is sufficient to cause evaporation of water under subatmospheric pressure ranging from about 5 to about 950 mbar to form a gas phase, which is loaded with water vapor and additionally contains sulfuric acid, and to form a concentrated bottom product,
- c) bringing the gas phase above the bottom product into contact with an aqueous phase that is provided at a rate that ranges from about 10 to about 1000 kg/hour of aqueous phase, per 1000 kg/hour of vapors, wherein the sulfuric acid contained in the gas phase is absorbed by the aqueous phase and a second gas phase, which is substantially free from sulfuric acid is obtained, and wherein the aqueous phase is provided by injection into the gas phase below a demister in co-current flow with the gas phase, and
- d) returning the aqueous phase from c), which contains sulfuric acid, to the bottom in the form of drops which are formed on a demister which is mounted above the bottom.
1 more element
Dependencies are inferred from the claim text.