Abstract: A process for the selective removal and recovery of sulfur dioxide from effluent gases is disclosed. The sulfur dioxide is recovered in a sulfur dioxide absorption/desorption cycle which utilizes a liquid solvent to selectively absorb sulfur dioxide from the effluent gas. The liquid solvent includes an organic phosphorous compound selected from phosphate triesters, phosphonate diesters, phosphinate monoesters and mixtures thereof. Preferably, the liquid solvent includes phosphonate diesters of the formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are independently aryl or C.sub.1 to C.sub.8 alkyl. The organic phosphonate diesters are substantially water immiscible, the solubility of water in the organic phosphonate diester being less than about 10 weight percent at 25.degree. C., and have a vapor pressure less than about 1 Pa at 50.degree. C. In accordance with a preferred embodiment, the liquid solvent include dibutyl butyl phosphonate.

Abstract: The concentration of sulfuric acid exiting a countercurrent SO.sub.3 absorber is controlled by controlled addition of water vapor to the SO.sub.3 -containing process gas stream entering the absorber. The novel means of concentration control is useful for control of the acid concentration gradient in an SO.sub.3 absorption process and apparatus for high temperature absorption, so as to achieve high temperature absorption heat recovery while minimizing corrosion and formation of acid mist.

Abstract: An improved process for the recovery of high grade energy from a contact sulfuric acid manufacturing process. Improvements include: injection of steam between an intermediate catalyst stage and a heat recovery absorption tower and/or a heat exchanger for transfer of heat from conversion gas to high pressure boiler feed water; use of a condensing economizer for recovery of the vapor phase energy of formation of sulfuric acid from a wet conversion gas; and use of heat recovery system absorption acid for preheating air to a sulfur burner, the heat transferred to the combustion air being recovered at high pressure and temperature in a waste heat boiler.

Abstract: An improved process for the recovery of high grade energy from a contact sulfuric acid manufacturing process. Improvements include: injection of steam between an intermediate catalyst stage and a heat recovery absorption tower and/or a heat exchanger for transfer of heat from conversion gas to high pressure boiler feed water; use of a condensing economizer for recovery of the vapor phase energy of formation of sulfuric acid from a wet conversion gas; and use of heat recovery system absorption acid for preheating air to a sulfur burner, the heat transferred to the combustion air being recovered at high pressure and temperature in a waste heat boiler.

Abstract: An improved process for manufacture of sulfuric acid by catalytic oxidation of wet sulfur dioxide gas. Wet conversion gas is contacted with sulfuric acid in a heat recovery stage to effect absorption and generate the heat of absorption. Wet gas having a mole ratio of sulfur trioxide to water vapor of at least 0.95 is introduced into the heat recovery stage at a temperature above the dew point of the gas. Sulfuric acid is introduced into the heat recovery absorption stage at a temperature of at least about 170.degree. C. and a concentration between about 98.5% and about 99.5%. The sulfuric acid stream as discharged from the absorption stage is at a temperature of at least about 190.degree. C. and has a concentration between about 99% and about 100%. The heat of absorption is recovered from the discharge absorption acid stream in useful form by transfer of heat to another fluid in a heat exchanger, the another fluid being heated to a temperature of at least about 140.degree. C.

Abstract: A method and apparatus for the recovery of heat from a sulfuric acid process are provided. Sulfur trioxide is absorbed into hot concentrated sulfuric acid, acid having a concentration greater than 98% and less than 101% and a temperature greater than 120.degree. C., in a heat recovery tower and the heat created by the exothermic reaction is recovered in a useful form in a heat exchanger. Gas leaving the primary heat recovery absorption zone is cooled by contact with sulfuric acid in a secondary absorption and cooling zone located above the primary absorption zone in the tower.

Abstract: A substantially cylindrical mist eliminator bed element for use in removal of liquid aerosols from a moving gas stream by flowing the gas stream through the element. The element comprises a first fiber bed for collection of aerosol particles, and a second fiber bed adjacent the first fiber bed for preventing reentrainment of liquid in the gas stream. The element is adapted to be oriented with respect to a substantially horizontal flow of aerosol containing gas so that adjacent surfaces of the fiber beds are substantially vertical, the first fiber bed being upstream of the second fiber bed with respect to the flow of gas. The first fiber bed comprises a bed of fibers having a mean diameter of at least about 10 microns packed to a substantially uniform bed voidage of 85% to 98%, the mean fiber diameter, bed voidage and distribution of fibers in the first bed being such as to provide for collection of the droplets of liquid aerosol from an aerosol containing gas.

Abstract: A method and apparatus for controlling anodic protection of a heat exchanger using two reference electrodes disposed at opposite ends of the heat exchanger.

Abstract: A method and apparatus for the recovery of heat from a sulfuric acid process are provided. Sulfur trioxide is absorbed into hot concentrated sulfuric acid, acid having a concentration greater than 98% and less than 101% and a temperature greater than 120.degree. C., in a heat recovery tower and the heat created by the exothermic reaction is recovered in a useful form in a heat exchanger.

Abstract: A method and apparatus for the recovery of heat from a sulfuric acid process are provided. Sulfuric trioxide is absorbed into hot concentrated sulfuric acid, acid having a concentration greater than 98% and less than 101% and a temperature greater than 120.degree. C., in a heat recovery tower and the heat created by the exothermic reaction is recovered in a useful form in a heat exchanger.

Abstract: This invention provides a method of removing heat from the process gas in a sulfuric acid plant having interpass and final absorption towers by indirect heat exchange with a liquid without condensing acidic vapors from said process gas. The method comprises installing first and second economizers, the second economizer having first and second sections for liquid flow. The process gas flow through the first economizer before passing through the interpass absorption tower and through the second economizer before passing through the final absorption tower. A liquid flows through the first and second economizers for indirect heat exchange with the process gas, the liquid passing sequentially through the second section of the second economizer, the first economizer, and the first section of the second economizer.