TH11247B - Improved wet separation method and solution for the removal of sulfur oxide from combustion exhaust - Google Patents

Abstract

Sulfur oxide (SOx) is extracted from the fluid combustion exhaust. Thicker of white limestone with water characteristics with more high efficiency and with economical both in cost and value. Operating expenses In a counter flow white limestone wet separator in a single-loop open chamber, the exhaust flow rate is greatly increased, while the L / G value and time exist in The reaction tank is reduced. The concept of an improved precipitator, new spacing and nozzle placement, and the use of hydrocyclones to separate smaller limestone particles. White from the gypsum by-product and in the transfer of the particles through another cycle Will bring up these advantages The white limestone is further reduced to very fine particles, for example, about 8 microns or less. It contains particles greater than 99% by weight smaller than 44 microns, and are introduced into the slurry for extraction, which is exposed to SOx-rich exhaust emissions, although the pH value is reduced. down The reaction of the slurry for extraction was also maintained through the Stimulate the hydrocyclone to operate continuously to insure the molar ratio of the contained compound. Calcium to sulfur-containing compounds is approximately 1.3 to 1, while still Able to maintain a low load of non-reactive solids and chlorides, the hydrocyclone removes large particles of calcium sulfate and creates a current for conduction. Through another cycle of calcium carbonate and inactive solids Which flows out in quantities as Required for keeping the contents of non-reactive solids and chloride at low levels.

Claims (4)

1. Wet separation process with counter flow white limestone in open-loop tower. Single for SOx concentration reduction in exhaust gas consists of (a) conduction of the exhaust gas flow contained in the SOx upward through the tower for vertical extraction with a total flow velocity of 4.5 m. (B) Water droplets of aqueous slurry of calcium carbonate, calcium sulfate, dissolved calcium and inert solid. That are small and fine Into the section for extraction Vertically inside the tower to make contact with the exhaust gas as it flows downward through the tower in a Which flows against the flow of exhaust gas for absorption of SOx from exhaust gas The PH value of the slurry when imported into the extraction chamber ranged from approximately 5.0 to approximately 6.3. It is supplied by spray nozzles arranged in two to three levels, with a lower pitch of approximately 2 m, and the direction of flow from nearby nozzles alternates between up and down. Below (c) Deposition of slurry containing dissolved SOx into the reaction tank after contact with flue gas (d) The condensed slurry from the reaction after average dwell time has passed. Less than about 8 hours had passed, but it was sufficient to allow the reaction of calcium-dissolved SOx. The dissolved and crystal growth of calcium sulphate reached median diameter by water. It is at least twice as heavy as the calcium carbonate added as a feeder (e). The condensed slurry removed from the reaction tank is processed to result in a The conduction current through another cycle is rich in fine particles of calcium carbonate, with a median diameter of approximately 8 microns or less, and the mole ratio of calcium-containing compounds to compounds with Sulfur is at least 1.3, and another stream is rich in relatively large particles of calcium sulphate particles of the diameter. The median center by weight at least 25 microns (f). Emissions rich in calcium sulfate particles for the removal of previously dissolved SOx in the slurry. And return the main part of the current for conduction Another cycle rich in calcium carbonate and low in calcium sulfate returns to the process and (g) the introduction of new calcium carbonate into the system in sufficient quantities to Maintain the pH of the slurry in the reaction tank to the range 5.0 to 6.3 and for the It was removed and not further cycles, as well as dissolved and reacted with the adsorbed SOx in the liquid phase in fraction for extraction by fine-grained calcium carbonate. The median particle size was less than approximately 10 microns in weight. 2. Process according to claim 1, where fine calcium carbonate was introduced as a feed additive. The feeder had a median particle size by weight less than approximately 8 microns at the time of ingestion. 3. Process according to claim 1, where the tower consisted of a flow-conductor separator. One pass acts to reduce the amount of liquid droplets to a minimum. And deviate on the direction of The flow of the exhaust gas goes from a vertical to a direction which results in a utilization of the eliminator. Small droplets in the vertical effectively. Where the separator of the carrier consists of a sheet Single-flow separator Each of these plates has been installed for the formation. As an assembly kit And each of the aforementioned sheet is tilted at an angle to the vertical. Vertically small And the separator of the above acts in deflecting the direction of the gas flow. The exhaust is at least 30 degrees from the vertical axis of the tower. 5. Process according to claim 1, where the slurry is removed from the reaction tank. It is then passed to the hydrocyclone for separation. 6. Process according to claim 1, where part of the slurry in the stream is used for separation. This is another cycle which is fed back to the reaction tank with a solid concentration of less than 10%. 7. Process according to claim 6, where the mole ratio of the calcium-containing compound. The sulfur-containing compound in the current for further cycles is approximately 1.4 more than 1.4. 8. The process of claim 6, where the current for further cycles, consists of The suspended solids were less than 5%. 9. Process according to claim 1 where the median size of the calcium carbonate particles in the reaction tank was within the range of 2 to approximately 6 microns and the particle size of the calcium carbonate in the reaction tank. Median by weight of granular calcium carbonate At the time of feeding, it is approximately less than 8 microns, with 99% particles smaller than 44 microns in weight. Accept Maintained within the range from approximately 5.8 to approximately 6.3 1 1. Process according to claim 1, where the molar ratio of the calcium-containing compound The sulfur-containing compound in the current for further cycle conduction is approximately 1.4 higher, and the current for further cycle conduction contains less than 5% 1 suspended solid. 2. Process according to claim 1, where air is delivered to the tower for extraction for Oxygen delivery for ionic oxidation of bisulfite and sulfite 1 3. Process according to claim 1, where median particle size by weight of calcium The carbonate in the slurry droplets introduced into the extraction section is 6 microns or smaller.1 4. Process according to claim 1 where the average residence time in the reaction tank is less than six hours.