Crystallizer, bicarbonator

Impurities remain in the brine solution and the sodium bicarbonate crystallizes and is filtered from the hquor. The bicarbonate is then converted to carbonate by heating ... 

A quantity of sodium bicarbonate crystals has the following sieve analysis... 

Braga, D., D Oria, E., Grepioni, F., Mota, F., Novoa, J. J., Rovira, C., 0-H...0 interactions involving doubly charged anions Charge compression in carbonate- bicarbonate crystals. Chem. Eur. J. 2002, 8, 1173-1180. 

A simple change in physical properties also can be achieved by crystallization. In the process of making soda ash, referred to earlier, the sodium bicarbonate crystals are subjected to heat that causes the release of carbon dioxide and produces low-density sodium carbonate crystals. The density of these crystals is incompatible with their use in glass manufacture, but a more acceptable crystal can be obtained by contacting the sodium carbonate crystals with water to form crystalline sodium carbonate monohydrate. Drying the resulting crystals removes the water of hydration and produces a dense product that is acceptable for glass manufacture. 

The precipitated bicarbonate crystals are centrifuged and then dried at low temperature to avoid reversion to carbonate. Sodium bicarbonate also can be obtained by solution mining of natural sodium bicarbonate (nahcolite). In the mining procedure, pairs of well are sunk, warm water is pumped down one well, and dissolved sodium bicarbonate solution is pumped up from the other well. Solid sodium bicarbonate subsequently is crystallized from... 

An aqueous solution containing 7.00 wt% sodium carbonate and a gas stream containing 70.0 mole% CO2 and the balance air are fed to the reactor. All of the sodium carbonate and some of the carbon dioxide in the feed react. The gas leaving the reactor, which contains the air and unreacted CO2, is saturated with water vapor at the reactor conditions. A liquid-solid slurry of sodium bicarbonate crystals in a saturated aqueous solution containing 2.4 wt% dissolved sodium bicarbonate and no dissolved CO2 leaves the reactor and is pumped to a filter. The wet filler cake contains 86 wi% sodium bicarbonate crystals and the balance saturated solution, and the filtrate is also saturated solution. The production rate of solid crystals is 500 kg/h. 

When heated to about 50°C, sodium bicarbonate begins to dissociate into carbon dioxide, sodium carbonate, and water on heating to 250-300°C, for a short time, sodium bicarbonate is completely converted into anhydrous sodium carbonate. However, the process is both time- and temperature-dependent, with conversion 90% complete within 75 minutes at 93°C. The reaction proceeds via surface-controlled kinetics when sodium bicarbonate crystals are heated for a short period of time, very fine needle-shaped crystals of anhydrous sodium carbonate are formed on the sodium bicarbonate surface. ... 

The aqueous solution is cooled and filtered to remove any excess coke, coke ash, or fly ash. After filtration, the solution is precarbonated with pure carbon dioxide recovered from the decomposer. Final carbonation occurs in the bicarbonator-crystallizer with carbon dioxide from the reducer off-gas. Gases evolved from both the precarbonator and the... 

The product from the bicarbonator-crystallizer is a sodium carbonate-sodium bicarbonate slurry which is decomposed to produce a sodium carbonate solution for return to the scrubber to provide pure carbon dioxide for the precarbonator. This completes the regeneration cycle and closes the loop for the total ACP system. The technology involved is a combination of a unique reducer and aqueous chemical processing, most of which is commercially proved. 

Detection reagents can also be applied to the layer as a vapor, as mentioned above for iodine. Other reagents delivered to the layer by vapor exposure include t-butyl hypochlorite and HCl, both of which form fluorescent derivatives with a variety of compounds. The Analtech vapor-phase fluorescence (VPF) visualization chamber provides detection of compounds such as sugars, lipids, steroids, flavonoids, and antibiotics by induced fluorescence after heating the sealed chamber, containing the plate and ammonium bicarbonate crystals, on a hotplate to a temperature that decomposes the salt to ammonia. 

As previously stated, a 40% solution has been found to be too concentrated for commercial use in some cases because of its tendency to form a slurry of bicarbonate crystals if the solution is cooled at any point in the circuit. In the presence of bicarbonate slurry, carbon steel cases and impellers of pumps were found to last only a few hours. Reduction of the solution concentration to below 30% eliminates this severe erosion however, stainless steel (type 316) impellers, case rings, and throat bushings are recommended in pumps handling the K2CO3 solution as a further safety measure (Buck and Leitch, 1958). 

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