Innovations/Modifications in the technology for the manufacture of Sulphuric Acid
As the manufacture of sulfuric acid has increased over the years, plant designers, operators, and maintenance engineers have developed and improved the technology for its manufacture, leading to more efficient plants. These developments are briefly presen
- PDF / 104,647 Bytes
- 13 Pages / 439.37 x 666.142 pts Page_size
- 23 Downloads / 139 Views
Innovations/Modifications in the technology for the manufacture of Sulphuric Acid
5.1 Introduction As the manufacture of sulfuric acid has increased over the years, plant designers, operators, and maintenance engineers have developed and improved the technology for its manufacture, leading to more efficient plants. These developments are briefly presented as improvements/innovations in process, catalyst, plant equipment, etc.
5.1.1 Improvements in Process The old chamber process used oxides of nitrogen to oxidize SO2 to SO3. This process could not produce higher strengths of the product acid. It was replaced by the contact process where the SO2 was converted to SO3 by the platinized asbestos catalyst. The plants running on this process could produce sulfuric acid of 98.5% strength. The earlier version of this contact process was known as the single contact single absorption process as the SO2 was passed through the converter to produce SO3 which was then absorbed in a single absorption tower. Some of the innovations in this process were as follows. These were aimed at improving the degree of conversion and heat recovery while reducing the initial capital cost and the cost of production: 1. Use of atmospheric cooling ducts for hot gases. 2. Control of gas temperatures by air injections at appropriate places. 3. Control of gas temperatures by use of air pre-heaters (hot gas/air heat exchangers) with simultaneous recovery of heat as hot air. 4. Heat recovery as low pressure steam with use of (a) One boiler—only after sulfur burner (b) Two boilers—after sulfur burner and after first pass of converter (c) Two boilers + economisers—adding an economiser for further heat recovery (d) Same as above, while producing high pressure steam
N.G. Ashar and K.R. Golwalkar, A Practical Guide to the Manufacture of Sulfuric Acid, Oleums, and Sulfonating Agents, DOI 10.1007/978-3-319-02042-6_5, © Springer International Publishing Switzerland 2013
53
54
5 Innovations/Modifications in the Technology…
(e) HP steam—saturated (f) HP steam—superheated 5. Use of the HP steam for power generation directly or for steam driven equipment (air blower).
5.1.2 D ouble Contact Double Absorption DCDA Process with Variants In the earlier variants of the DCDA process, the SO2 was converted to SO3 by catalyst passes and the SO3 was then absorbed in the inter-pass absorption tower. The gases from the exit of the IPAT were again reheated to about 425–435 °C and subjected to more catalyst passes. This was done in accordance with the Le Chatelier’s principle for increasing the overall degree of conversion achieved. The process was indicated by the number of catalyst passes preceding the IPAT and following it: 1. (2 + 2) DCDA two catalyst passes preceding the IPAT and two passes following it. 2. (3 + 1) DCDA three catalyst passes preceding the IPAT and one pass following it. 3. (3 + 2) DCDA three catalyst passes preceding the IPAT and two passes following it. The DCDA process could be operated with a higher percentage SO2 in the converter in
Data Loading...
