Limestone advantages

There have been a number of cell designs tested for this reaction. Undivided cells using sodium bromide electrolyte have been tried (see, for example. Ref. 29). These have had electrode shapes for in-ceU propylene absorption into the electrolyte. The chief advantages of the electrochemical route to propylene oxide are elimination of the need for chlorine and lime, as well as avoidance of calcium chloride disposal (see Calcium compounds, calcium CHLORIDE Lime and limestone). An indirect electrochemical approach meeting these same objectives employs the chlorine produced at the anode of a membrane cell for preparing the propylene chlorohydrin external to the electrolysis system. The caustic made at the cathode is used to convert the chlorohydrin to propylene oxide, reforming a NaCl solution which is recycled. Attractive economics are claimed for this combined chlor-alkali electrolysis and propylene oxide manufacture (135). 

Drying Fhiidized-bed units for drying solids, particularly coal, cement, rock, and limestone, are in general acceptance. Economic-considerations make these units particularly attrac tive when large tonnages of solids are to be handled. Fuel requirements are 3.3 to 4.2 MJ/kg (1500 to 1900 Btu/lb of water removed), and total power for blowers, feeders, etc., is about 0.08 kWh/kg of water removed. The maximum-sized feed is 6 cm (IV2 in) X 0 coal. One of the major advantages of this type of dryer is the close control of conditions so that a predeterminea amount of free moisture may be left with the solids to... 

Fluidized-bed noncatalytic reactors. Fluidized beds are also suited to gas-solid noncatalytic reactions. All the advantages described earlier for gas-solid catalytic reactions apply here. As an example, limestone (principally, calcium carbonate) can be heated to produce calcium oxide in a fluidized-bed reactor according to the reaction... 

One of the major advantages of fluidised bed combustion of coal is that it is possible to absorb the sulphur dioxide formed. Generally limestone or dolomite is added and thus breaks up in the bed to yield calcium oxide or magnesium and calcium oxide, which then react with the sulphur dioxide as follows ... 

In addition to Ni catalysts, Lee and Park explored some unconventional catalysts, such as limestone, dolomite, and iron ore, in a fluidized bed reactor to carry out SR of kerosene and bunker oil. H2 yields from SR of bunker oil over various catalysts (temperature = 800°C, bed height = 10 cm, superficial gas velocity = 20 cm/sec, and S/C = 1.6) were sand (20%), iron ore (29%), commercial Ni catalyst (89%), limestone (93%), and dolomite (76%). Limestone as a SR catalyst looked very promising, but H2 yields over a limestone catalyst decreased over time due to elutriation of fines during the reaction. A fluidized-bed reactor was advantageous for reforming of higher hydrocarbons, due to its ability to replace coked catalyst with fresh catalyst during operation. 

The limestone powd with sp surface of 3000cm2 /g absorbed heat not only by its own temp rise, but also by thermal dissocn. Its lack of hygroscopic ty is another advantage. Wnereas the brisance of Dynamite contg limestone and AN decreases about 20% on damp storage for 500 hr, that of Dynamite contg limestone alone,... 

H. Wanzke, Z ement-Kalk-Gips 19, 121-23 (1966) CA 65, 3659(1966) [The advantages of the use of ANC expls (where C stands for carbon) in large-diameter borehole blasting are discussed. The expts were carried out in a limestone quarry with a daily ourput of... 

To take advantage of rising oil prices, many oil companies have increased production from older leases over the past several years. In 1975, Continental Oil Co. (now Conoco Inc ) began a program to maximize production from the Big Lake field, Reagan County, TX. The field was the discovery field of the Permian Basin region and has been on production since 1923. Production has been primarily from the Grayburg limestone, at... 

A fluidized bed combustion system (FBC) is one that has a high temperature (1500 F to 1600 F) inert material, such as sand, ash, or limestone, occupying the bottom of the chamber.14 Figure 2-3 illustrates a typical fluidized bed boiler. Limestone, either as primary bed material, or as an addition, provides the additional advantage of S02 scrubbing.14,15 The advantage of fluidized bed combustion over the other 3 boiler types is that the fluidization of the inert bed material allows fuels with higher moisture and ash content to be burned, and still yield nearly complete combustion. Further, SOx control is easily and efficiently accomplished. The bed material is fluidized by one of two methods as described below. 

---