Process and apparatus for purifying gas |
|||||||
| 申请号 | US3615199D | 申请日 | 1967-11-09 | 公开(公告)号 | US3615199A | 公开(公告)日 | 1971-10-26 |
| 申请人 | WELLMAN LORD INC; | 发明人 | TERRANA JACK D; MILLER LEO A; | ||||
| 摘要 | Apparatus and process for preventing plugging of a reactor used in a system involving reaction between components, e.g. SO2, in a gas and a salt solution, e.g. a sulfite solution which is close to its saturation point, while avoiding substantial dilution of the sulfite solution to produce a spent bisulfite solution from which the bisulfite is subsequently separated and decomposed to release sulfur dioxide. Examples of sulfites include potassium, cesium, or rubidium sulfites. The apparatus includes a reaction zone having at least one, or more contact trays which are sprayed from beneath with the aqueous salt solution, e.g. sulfite solution. An entrainment zone above the trays can be used to advantage and this involves a woven mesh contact material which is sprayed from both sides with the salt solution to remove entrained materials from the gas leaving the reactor. Also, particulate solid or liquid-soluble gaseous contaminants can be removed from the gas before contacting it with the sulfite solution by contacting it with a fluid-permeable, impingement target in the presence of a concurrently flowing liquid stream which is also contacting the target. It is desirable to prevent plugging of the gas inlet opening to the reactor by using a bonnet arranged over the gas inlet opening. | ||||||
| 权利要求 | 2. The process of claim 1 wherein the metal sulfite solution is substantially saturated and is sprayed against substantially the entire undersurface of said tray at a rate of about 0.1 to 0.4 g.p.m. per 2,000 c.f.m. of gas. 3. The process of claim 1 wherein about 5 to 25 percent of said solution containing metal sulfite fed to the reaction zone is provided by said spraying. 4. A process for separating sulfur dioxide from a sulfur-dioxide-containing gas having a temperature of about 150* to 400* F., by reaction with an aqueous solution containing dissolved metal sulfite having a concentration close to its saturation point to produce the corresponding bisulfite in a reaction zone including at least one fluid permeable, open, liquid holdup-type contact tray, comprising providing a layer of said sulfite solution on said tray, passing solution from said layer downwardly from said tray, conducting said gas upwardly in the reaction zone and through said tray and said layer to react sulfur dioxide of the gas with said metal sulfite to produce the corresponding bisulfite without entrainment of substantial amounts of said solution in the components of said gas passing upwardly from said tray and said layer of solution, spraying the undersurface of said tray in the area through which said gas passes through said tray with an aqueous solution containing said dissolved metal sulfite, the amount of said solution so sprayed being sufficient to substantially maintain salt contacting the surface of said tray in solution and alleviate plugging of said tray, removing said metal bisulfite from the reaction zone, heating said removed metal bisulfite which may be present in the form of pyrosulfite, to produce sulfur dioxide. 5. The process of claim 4 wherein the rate of flow of the solution of metal sulfite through the reaction zone is about 0.1 to 20 g.p.m. per 2000 c.f.m. of gas, of which about 0.1 to 0.4 g.p.m. per 2,000 c.f.m. is sprayed against the undersurface of the tray. 6. The process of claim 5 wherein the superficial velocity of the gas through the reaction zone is above about 1.5 f.p.s. 7. The process of claim 5 wherein the reaction zone temperature is below about 230* F. 8. The process of claim 7 wherein the sulfite solution conducted to the reaction zone contain about 30 to 75 percent solids of which at least about 50 percent is potassium sulfite with the balance being essentially potassium bisulfite, and the aqueous solution of potassium bisulfite produced in the reaction zone contains about 40 to 75 weight percent solids of which about 5 to 60 weight percent is potassium bisulfite and the balance essentially potassium sulfite. 9. The process of claim 4 wherein the reaction zone temperature is less than about 190* F., the solution of metal sulfite contains about 40 to 65 weight percent solids of which above about 75 percent is potassium sulfite with the balance being essentially potassium bisulfite and the solution of potassium bisulfite produced in the reaction zone contains about 45 to 65 weight percent solids of which essentially 10 to 50 percent is potassium bisulfite with the balance being essentially potassium sulfite. 10. The process of claim 9 wherein the aqueous potassium sulfite solution contains a oxidation inhibitor to inhibit the reaction of sulfite ion and oxygen. 11. The process of claim 4 wherein the gaseous effluent from said layer is conducted in a generally upward direction in an entrainment zone and through a fluid-permeable, woven mesh contact material which is inert to the reactants, spraying a liquid against gas inlet and outlet sides of the contact material, the amount of the liquid so sprayed serving to maintain the material wet and remOve entrained droplets in the SO2-lean gas from the reaction zone. 12. The process of claim 11 wherein the liquid sprayed against said contact material is an aqueous solution of metal sulfite and, after use in the entrainment zone, is provided as a portion of the feed in the reaction zone; the rate of flow of metal sulfite solution to the reaction zone is about 0.1 to 20 g.p.m. per 2,000 c.f.m. of gas and about 40 to 60 percent of the flow is first sprayed against the contact material. 13. The process of claim 4 wherein the SO2-containing gas is preliminarily scrubbed to remove sulfur trioxide in said gas and, if present, particulate solid components, comprising conducting the gas at a temperature of about 150* to 800*F. in a generally upwardly direction in a scrubbing zone to and through a substantially horizontally disposed, fluid-permeable, impingement target having a discontinuous surface for retention of entrained solids in the gas passing to the target cocurrently with said gas and aqueous liquid to contact, wet and flush the target and remove from the gas sulfur trioxide and particulate solids, if present in the gas, recovering resulting liquid from below said target, and conducting resulting purified SO2-containing gas to the reaction zone. 14. The process of claim 13 wherein the gas introduced into the scrubbing zone contains from about 0.001 to less than about 5 mole percent SO2, from about 0.001 to 0.01 mole percent SO3, particulate solid components including from about 0.001 to 60 grains of fly ash per cubic foot of gas, and is at a temperature from about 150* to 600* F.; and the liquid used in the scrubbing zone is water and is conducted to the target in the form of a spray. 15. The process of claim 4 wherein plugging of the gas inlet to the reactor by particulate solids in the SO2-containing gases is alleviated by introducing the gas into the reactor through an inlet in a sidewall of the reactor, in a generally upward direction with respect to the horizontal and into the free space of the reactor away from the inlet wall thereof, the upward direction and position of the point of introduction preventing scrubbing liquid in the reactor from contacting the upper edge of the gas inlet. 16. The process of claim 15 wherein the angle at which the gases are introduced is about 5* to 60* above the horizontal. The process of claim 16 wherein the gases are introduced into the reactor at least one inch from the inlet wall thereof. |
||||||
| 说明书全文 | |||||||
QQ群二维码
意见反馈
意见反馈