Calcium regeneration product

The calcium oxide product is supplemented with fresh limestone and returned to the fluidized bed. Two undesirable side reactions can occur in the regeneration of spent lime leading to the production of calcium sulfide ... 

Figure 7. Flowchart of hydrochloric acid regeneration circuit and calcium sulfate production...

Some products are precipitated from the fermentation broth. The insoluble calcium salts of some organic acids precipitate and are col-lec ted, and adding sulfuric acid regenerates the acid while forming gypsum (calcium sulfate) that constitutes a disposal problem. An early process for recovering the antibiotic cycloserine added silver nitrate to the fermentation broth to precipitate an insoluble silver salt. This process was soon obsolete because of poor economics and because the silver salt, when diy, exploded easily. 

RCE A flue-gas desulfurization process in which the sulfur dioxide is absorbed in aqueous magnesium hydroxide. The product is reacted with calcium chloride to produce gypsum, and the magnesium hydroxide is regenerated by treatment with dolomite. Developed by Refractories Consulting Engineering, Germany, and piloted in Austria. 

The same group also performed experiments with a continuous chromatographic reactor of the SMBR type [133,174]. The system used consisted of 12 columns with inner diameters of 5.4 cm and a length of 75 cm. Approximately 12 cycles were necessary for stabilization of the system. Complete inversion of sucrose even at feed concentrations of up to 55% w/v was achieved, while the product purity was over 90%. After prolonged usage, the system efficiency decreases due to the loss of the calcium ions from the matrix and a consequent decreased selectivity of the resin. However, this problem could be overcome by regeneration of the resin with calcium nitrate. 

Alkylation generates relatively low volumes of wastewater, primarily from water washing of the liquid reactor products. Wastewater is also generated from steam strippers, depropanizers, and debutanizers, and can be contaminated with oil and other impurities. Liquid process waters (hydrocarbons and acid) originate from minor undesirable side reactions and from feed contaminants, and usually exit as a bottoms stream from the acid regeneration column. The bottoms stream is an acid-water mixture that is sent to the neutralizing drum. The acid in this liquid eventually ends up as insoluble calcium fluoride. 

Most linear celluloses may be dissolved in solvents capable of breaking the strong hydrogen bonds. These solutions include aqueous solutions of inorganic acids, calcium thiocyanate, zinc chloride, lithium chloride, ammonium hydroxide, iron sodium tartrate, and cadmium or copper ammonium hydroxide (Schweitzer s reagent). The product precipitated by the addition of a nonsolvent to these solutions is a highly amorphous, regenerated cellulose. 

The process of removal of calcium by marine organisms in the water column is well known. Production of calcium carbonate by water column biological processes may be estimated from primary productivity and from the mean chemical composition of plankton. After death of the organisms and removal of the organic protective layer, the skeletons may undergo dissolution if they encounter water undersaturated with respect to their mineral composition. Active dissolution of calcium carbonate occurs mainly near the sediment-water interface in deep waters that are undersaturated with respect to both calcite and aragonite (see Chapter 4). Thus, calcium is regenerated from calcareous skeletons and, finally, only a small fraction of the initial production of these materials accumulates in sediments. An... 

Figure3. Illustration of the Unmixed Reforming process with calcium oxide. The process consists of three steps 1) Reforming 2) Air regeneration 3) Fuel regeneration. As the nickel is cycled between the oxide and the catalytically active metallic state, the calcium is cycled between the oxide and the carbonate, thus reducing the carbon dioxide concentration in the product hydrogen and effecting the transfer of chemical energy between the regeneration and reforming steps.

Sodium forms of zeolites X and Y are known to be Inactive for alkylation. Calcium Introduction (catalyst 1) has resulted In a catalyst with some activity. Selectivity of the sample was not high about 57% of the alkylate were octanes with a ratio of TfV to DW of 2 1. The yield and quality of the alkylate were Improved, If Na" " cations were replaced with cations of rare-earth elements (catalysts 2 and 3). Product yield for catalysts 2 and 3 were 86.0% and 77.5% respectively with a TMP content In C0-fractionof about 85%. Unfortunately the stabilities of these two catalysts were rather low In both cases, and alkylates yields and quality declined after 3 or 4 runs. For example the percentage of unsaturated hydrocarbons In the hydrocarbon product for catalyst 3 Increased from 18 up to 30%, and TMP concentration decreased to 35% after several runs. Catalyst 4 has proved to be the most active and stable catalyst and the yields and quality of alkylates obtained over It have been the same even after many reaction-regeneration cycles. Further Increase of calcium content In the catalyst (catalyst 5) deteriorated Its catalytic properties. 

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