| 摘要 |
Sulphate waste or other sulphur-containing material is passed into a cracker 2 where sulphur dioxide is formed, the necessary heat being generated by burning a carbon-containing fuel. Oxygen-rich gas, preferably pure oxygen, is used to support the combustion and a gas mixture including, after drying, more than 16% by volume of sulphur dioxide and at least 30% by volume of carbon dioxide. Typically the gas mixture includes at least 60% by volume of carbon dioxide and at least 25% by volume of sulphur dioxide (after drying). The mole ratio of the mixture is adjusted by addition of oxygen-rich gas through passage 20 upstream of a catalytic converter. Typically the mole ratio of the gas mixture entering the first stage 24 of the converter 22 has a mole ratio of sulphur dioxide to oxygen greater than three to one. In each stage of the converter 22 reaction takes place between sulphur dioxide and oxygen to form sulphur trioxide which is absorbed to form sulphuric acid. Oxygen is also added between the first and second stages and typically the second and third stages of the converter. High production rates of sulphuric acid for a given size of converter and from low valve sulphur-containing materials are made possible. |
