Sulfite slurry

Oxidizer Column The oxidizer column is where the calcium sulfite slurry is reacted with air to form the by-product calcium sulfate. Air compressors are used to supply the oxidation air. In addition, the proper pH is maintained to sustain the... 

J. Vanderschuren, Modeling of dilute sulfur dioxide absorption into calcium sulfite slurries, Chem. Eng. 

Laboratory data compiled at the request of the SO,-recovery design group (results of filtration of zinc sulfite slurry on an Oliver rotary vacuum filter) are as follows ... 

The sulfite oxidation rate in hold tanks of antipollution scrubbers is central to flue gas desulfurization technology. The accurate description of the rate of disappearance of sulfite slurry particles (from the scrubber liquor) bears upon both process selection and economics. This article will describe a mathematical model for a semi-batch, stirred tank reactor in which S(IV) anions, sulfite and bisulfite, are reacted with dissolved oxygen gas at saturation. Experimental work to secure several physical parameters and to verify the... 

Gladkii(16) at the State Scientific Research Institute of Industrial and Sanitary Gas Cleaning at Moscow did work on the three-phase calcium sulfite slurry oxidation system, finding that the liquid phase oxidation (pH 3.6-6) is first order with respect to the sulfite species. He pointed out, on the basis of pH versus time data from his semi-batch reaction, that the slurry oxidation had different periods in which either reaction kinetics or solid-liquid mass transfer controlled the oxidation rate. He also presented an omnibus empirical correlation between pH, temperature, and the liquid phase saturation concentration of calcium sulfite solution for predicting the slurry oxidation rate. The catalytic effect of manganese... 

Wang, C. C., "Experiments and Modeling of Calcium Sulfite Slurry Oxidation," M.S. Thesis, University of Virginia... 

Sodium Benzenesulfonate. Benzenesulfonic acid prepared continuously in a cascade series of six 2,000-gal cast-iron vessels is fed to a neutralizer system. Sodium sulfite slurry from reaction (3) is fed into the neutraliza tion tank at a constant rate while the benzenesulfonic acid flow is regulated to keep the reaction mixture distinctly acid. Sulfur dioxide is liberated [Eq. (2)] and piped for acidification of sodium phenoxide [Eq. (4)], and some is sent to another plant for purification and liquefaction. 

In the double alkali nonregenerative procedure, flue gas is scrubbed with a soluble alkali such as sodium sulfite, which is subsequeutly regenerated with lime to form insoluble calcium sulfite after whieh disposal of the calcium sulfite slurry occurs, and the spent absorbent, sodium bisulfite, is regenerated by thermal means ... 

The absorption of sulfur dioxide in alkaline (even weakly alkaline) aqueous solutions affords sulfites, bisulfites, and metabisulfites. The chemistry of the interaction of sulfur dioxide with alkaline substances, either in solution, slurry, or soHd form, is also of great technological importance in connection with air pollution control and sulfur recovery (25,227,235—241). Even weak bases such as 2inc oxide absorb sulfur dioxide. A slurry of 2inc oxide in a smelter can be used to remove sulfur dioxide and the resultant product can be recycled to the roaster (242). 

A variation of the n on regen erabi e absorption is the spray dry process. Time slurry is sprayed through an atomizing nozzle into a tower where it countercurtendy contacts the flue gas. The sulfur dioxide is absorbed and water in the slurry evaporated as calcium sulfite-sulfate collects as a powder at the bottom of the tower. The process requires less capital investment, but is less efficient than regular scmbbing operations. 

Another procedure utilizes a slurry of sodium sulfite, produced by the reaction of soda ash with sulfur dioxide, which is digested with excess sulfur until all of the sulfite is used up ... 

Stirred-slurry operation, 120-123 holdup, axial dispersion, 122-123 mass transfer, 120-122 reactors, 80 Subcooling, 236-238 inlet, 261 Subreactors, 363 Sulfite-oxidation, 300-301 Summerfield, combustion equation, 44-43 Surface-active agents, 327-333 experiment, 327-329 theory, 329-333... 

Nowadays economy and ecology render the reuse of the sulfite solution increasingly important. Normally the scrubber liquor is recovered as dilution water directly in the neutralization of sulfonation plant or in the slurry preparation unit of synthetic detergent plants. In some special cases, when the presence of sulfites is incompatible with the slurry composition, it is possible to install as optional a sulfite oxidation unit. This oxidation takes place with atmospheric air. 

The fluid loss and thickening time characteristics of the cement slurry is altered, either by increasing the molecular weight of the lignin by cross-linking with formaldehyde or epichlorohydrin or by adding agents such as sodium sulfite, sodium metasilicate, sodium phosphate, and sodium naphthalene sulfonate. 

Sodium hydrosulfite is produced through the Formate process where sodium formate solution, sodium hydroxide, and liquid sulfur dioxide reacted in the presence of a recycled stream of methanol solvent. Other products are sodium sulfite, sodium bicarbonate, and carbon monoxide. In the reactor, sodium hydrosulfite is precipitated to form a slurry of sodium hydrosulfite in the solution of methanol, methyl formate, and other coproducts. The mixture is sent to a pressurized filter system to recover sodium hydrosulfite crystals that are dried in a steam-heated rotary drier before being packaged. Heat supply in this process is highly monitored in order not to decompose sodium hydrosulfite to sulfite. Purging is periodically carried out on the recycle stream, particularly those involving methanol, to avoid excessive buildup of impurities. Also, vaporized methanol from the drying process and liquors from the filtration process are recycled to the solvent recovery system to improve the efficiency of the plant. 

Bischoff A flue-gas desulfurization process. A slurried mixture of lime and limestone is sprayed into the gas in a spray tower. The calcium sulfite in the product is oxidized by air to calcium sulfate. Used in Europe in the 1980 s. Lurgi Bishoff is a part of the Lurgi group. The process is offered by Lentjes, Germany, a subsidiary of Lurgi. 

Desox A flue-gas desulfurization process in which limestone slurry absorbs the sulfur dioxide, forming calcium sulfite. This is then oxidized to saleable gypsum ... 

Howden An early flue-gas desulfurization process using a lime or chalk slurry in wooden grid-packed towers. The calcium sulfate/sulfite waste product was intended for use in cement manufacture, but this was never commercialized. The key to the process was the use of a large excess of calcium sulfate in suspension in the scrubbing circuit, which minimized the deposition of scale on the equipment. The process was developed by Imperial Chemical Industries and James Howden Company in the 1930s and operated for several years at power stations at Fulham, London, and Tir John, South Wales, being finally abandoned during World War II. British Patents 420,539 433,039. 

The throw-away processes with aqueous slurries of lime or limestone as the scrubbing media are the most extensively installed processes. These processes create a waste sludge containing calcium sulfite, calcium sulfate, fly ash, unreacted alkali, and other minor dissolved species in the free water contained in the sludge. Since flue gas contains oxygen, some of the dissolved sulfur dioxide is oxidized, and calcium sulfate is formed. 

Several power plants have been equipped with dual alkali processes. These are throw-away processes with two liquid loops. In one common process, the scrubbing liquid is a clear solution of sodium sulfite. The absorption of sulfur dioxide converts the sodium sulfite to sodium bisulfite. In the regeneration loop, an alkali such as lime slurry is added the sodium sulfite solution is regenerated and a mixture of calcium sulfite and calcium sulfate is precipitated. The slurry is... 

Several plants have been equipped with processes that use an aqueous slurry of magnesium sulfite and magnesium oxide as the scrubbing material. Sulfur dioxide is absorbed, and a mixture of magnesium sulfite and magnesium sulfate is precipitated. 

Figure 8 shows the effects of dissolved sulfite concentration and slurry flow rate on SO2 removal as predicted by Equation 10 for the TCA with 15 inches of spheres and a scrubber... 

Figure 8. S01 removal as a function of dissolved sulfite concentration and slurry...

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