Absorption sulfuric acid manufacture

Absorption spectra, 23 3 of fats and oils, 10 822-823 of polymethine dyes, 20 506-512 Absorption spectroscopy, infrared reflection, 24 114-116 Absorption towers, in sulfuric acid manufacture, 23 779 Absorptive probes, 11 150 ABS polymers, 10 205-207. See also ABS (acrylonitrile-butadiene-styrene) materials... 

DOT safety regulations, 25 337 Double absorption process, for sulfuric acid manufacture, 23 769 Double absorption sulfuric acid plants, 23 774... 

Fig. 25.9. Schematic flow diagram of a double absorption contact process for sulfuric acid manufacture.

In the manufacture of sulfuric acid, the SO2 is first catalytically oxidized, to SO3 which is then absorbed into a H2SO4-H2O-SO3 solution (absorption directly into H2O is not feasible because a mist forms with SO3 that cannot be absorbed). An absorption tower is usually composed of various kinds of packing, but sometimes trays are used as in a distillation column. For sulfuric acid manufacture the steel tower is lined with acid proof masonry, and chemical stoneware is used for the packing. A tower might be 7 or 8 m in diameter and absorb 1,000 tons per day of SO3. Absorption towers are used to retrieve many other gases from the vapor phase into the liquid phase (not necessarily water). 

Procedures, General Design Concept, Choice of Solvent, Selection of Column Diameter, Physical Absorption, Solvent Absorption, Natural Gas Dehydration, Gas Drying, Sulfuric Acid Manufacture, Formaldehyde Absorption, Absorption with Chemical Reaction, Cracked Gas Scrubbing, Amine Systems, Hot Carbonate Systems, Multicomponent Absorption, Reboiled Absorbers, Example Problem, Notation, References... 

Phosphate fertilizer complexes often have sulfuric and phosphoric acid production facilities. Sulfuric acid is produced by burning molten sulfur in air to produce sulfur dioxide, which is then catalytically converted to sulfur trioxide for absorption in oleum. Sulfur dioxide can also be produced by roasting pyrite ore. Phosphoric acid is manufactured by adding sulfuric acid to phosphate rock. The... 

The contact process was invented by Phillips in England in 1831 but was not used commercially until many years later. Today 99% of all sulfuric acid is manufactured by this method. It was developed mainly because of the demand for stronger acid. All new contact plants use interpass absorption, also known as double absorption or double catalysis. This process will be described in detail in Fig. 2.3. 

Oleum Manufacture. To produce fuming sulfuric acid (oleum), S03 is absorbed in one or more special absorption towers irrigated by recirculated oleum. Because of oleum vapor pressure limitations the amount of S03 absorbed from the process gas is typically limited to less than 70%. Because absorption of S03 is incomplete, gas leaving the oleum tower must be processed in a nonfuming absorption tower. 

Sulfur Dioxide to Sulfur Trioxide Process. The manufacture of sulfuric acid involves the oxidation of elemental sulfur to SO2, followed by the catalytic oxidation of SO2 to SO3 over vanadium pentoxide. The next step involves the absorption of SO3 with water to form H2SO4. The SO2 oxidation reaction to... 

Ethyl Alcohol and Higher Alcohols. Two general processes exist for hydrating olefins to alcohols. The first is by absorption of olefins in inorganic acids, primarily sulfuric acid, followed by hydrolysis of the intermediate ester. The second process is the direct catalytic hydration of the olefin. The literature on these processes, especially as applied to ethanol and 2-propanol manufacture, is well covered in the general works listed above, and especially by Brooks (22). German work on the catalytic hydration of olefins is described by Kammermeyer and Carpenter (55). The preparation of amyl alcohols via chlorination of pentanes and hydrolysis of the halides is described by Kenyon (56). 

Hence, the industrial preference for manufacturing fuming sulfuric acid was in the range 20-25% free SO3. This needs removal of exothermic heat of heat of dilution together with heat of absorption of SO3 by specially designed coolers. Some plants have a gas heated oleum boiler for boiling the 25% oleum to produce pure SO3 vapor. 

Unlike 25% oleum, 65% oleum can be manufactured only by use of pure SO3 gas evaporated out of 25% oleum in a boiler heated by energy available in the hot gases of the contact sulfuric acid plant - refer to the block diagram in Chap. 1. The pure SO3 vapors are sent to the 65% oleum tower with facilities for cooling the heat generated due to exothermic absorption as well as dilution by addition of 25% oleum. A level contfoller is provided to maintain the tank level in the circulation boot. 

Apart from the benefits of the high pressure mixing of SO3 with water to produce sulfuric acid, the proposed cold process for the manufacture of sulfuric acid has also been conceived to avoid the complexity of requiring a sulfur furnace and the related heat recovery system, the multipass static converter, counter current heat exchangers, the interpass absorption tower (IPAT), drying tower (DT), final absorption tower (FAT), mist eliminators, acid coolers, and alkali scrubber. The resulting plant is, as a result, of much lower cost in equipment and land use. 

Nitrogen compounds must be absorbed in several chemical and related processes, the most important of which is the absorption of nitrogen peroxide in water for the manufacture of nitric acid. Absorption of nitrous gases also takes place in the lead-chamber process used for the production of sulfuric acid, in the metallurgical industries where metals are treated with nitric acid, and in the purification of several tail gases. 

In the industrial process used today to manufacture salicylic acid, dry sodium phenoxide obtained from phenol and soda is contacted with C02 under 0.5 MPa and at temperatures around 373 K. After absorption of approximately one molar equivalent of C02, the temperature is raised and held at 423—433 K for several hours to fulfill the reaction [16]. The final technical-grade salicylic acid is obtained after successive purification steps and, eventually, upon acidification with sulfuric or hydrochloric acid (Figure 5.1). 

Fillers. The buffering action of an alkaline filler is necessary to ensure permanence in filled paper. Retained alkalinity in the paper as it ages would resist any drop in pH that might result from absorption of either carbon dioxide or sulfur dioxide from the air. Acidic fillers, such as certain types of clay, accelerate the aging process. Calcium carbonate is an ideal filling material for permanent paper as well as for some grades not requiring permanency. In fact, the work of Barrow made the use of calcium carbonate a requirement in the manufacture of permanent book papers (1). 

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