Abstract: Oxygen enriched gas to Claus furnace or catalytic reactor is diluted with a process derived dilute H.sub.2 S or SO.sub.2 stream to prevent excessie temperature rise due to use of the oxygen enriched gas.

Abstract: Sulfur is recovered from an acid gas stream comprising hydrogen sulfide by successively reducing the hydrogen sulfide in a thermal reaction zone, a first position Claus catalytic conversion zone operated above the sulfur deposition point, and a second position Claus catalytic conversion zone operated under conditions effective for producing and depositing elemental sulfur on the catalyst. Periodically, the reactor in the second position is switched to the first position, the reactor in the first position having previously been preconditioned thereby avoiding a temporary increase in emissions after switching.

Abstract: Oxygen enriched gas to Claus furnace or catalytic reactor is diluted with a process derived dilute H.sub.2 S or SO.sub.2 stream to prevent excessive temperature rise due to use of the oxygen enriched gas.

Abstract: A regeneration effluent stream containing ammonia from an adsorptive Claus reactor is processed to produce a stream enriched in ammonia and an ammonia-lean regeneration effluent stream. The stream enriched in ammonia is processed to reduce the concentration of ammonia therein.

Abstract: The Claus process gas is cooled in a condenser to condense most of the sulfur vapor in solid form. The gas leaving the condenser is then further cooled to condense water without producing substantially any sulfur in an undesirable form. The resulting gas of reduced water content is useful in Claus reaction, particularly the low temperature Claus reaction in which the product sulfur is adsorbed on the catalyst.

Abstract: The Claus process gas is cooled in a condenser to condense most of the sulfur vapor in solid form. The gas leaving the condenser is then further cooled to condense water without producing substantially any sulfur in an undesirable form. The resulting gas of reduced water content is useful in Claus reaction, particularly the low temperature Claus reaction in which the product sulfur is adsorbed on the catalyst.

Abstract: Claus plant tail gas is treated to further reduce sulfur content by hydrogenating all sulfur compounds to hydrogen sulfide, pressurizing the resulting stream and cooling to reduce water content therein, and removing hydrogen sulfide from the resulting stream of reduced water content.

Abstract: Claus process sulfur recovery can be improved by performing a Claus conversion under low temperature and low water concentration conditions. The process treats a feed stream containing sulfur compounds by converting all sulfur compounds in the stream to a single sulfur species, reducing water content to low water concentrations, creation of a Claus reaction mixture, and then low temperature catalytic conversion to sulfur and water.

Abstract: An apparatus and process are provided for recovering and utilizing heat emanating from the shell of a thermal reactor in a sulfur recovery plant. Air is allowed to pass between the metal shell of a thermal reactor and an insulating jacket that partially encloses the shell. As the air exits through an opening at the top of the insulating jacket it is collected by a collection hood located above the thermal reactor. The collected air is then forced into the inlet of the thermal reactor where it is mixed with acid gas and thereby the heat emanating from the thermal reactor is recirculated to heat the reaction zone.

Abstract: Vaporized elemental sulfur is recovered from a gaseous stream by cooling said stream in a first heat exchanger to condense elemental sulfur and then cooling said stream in a second heat exchanger to solidify the remaining elemental sulfur. The plugging of the heat exchanger is avoided by switching the operating conditions of the two exchangers and reversing the sequence of the flow through these two heat exchangers. The process and apparatus are especially useful in treating the tail gas and the intermediate streams in the Claus process or in the modified Claus process.Instead of reversing the flow, the plugging can be avoided by using two two-zone heat exchangers. One of the heat exchangers is operated to effect the condensation of elemental sulfur in the first zone and melting the solidified sulfur deposited in the second zone. The second heat exchanger is operated to effect condensation of sulfur in the first zone and solidification of sulfur in the second zone.

Abstract: Ammonium compounds deposited on catalyst in a sulfur recovery facility are removed by passing a hot regeneration stream in contact with the catalyst to produce a regeneration effluent stream containing ammonia followed by combustion or catalysis to reduce the concentration of ammonia in the regeneration effluent stream.

Abstract: An improved method of regenerating a low temperature Claus catalyst bed having elemental sulfur deposited on the catalyst involving initially using a moderately hot effluent gas (typically 600.degree. to 650.degree. F.) from the first conventional Claus reactor to warm up the low temperature Claus reactor and remove deposited sulfur and after the outlet temperature of said low temperature reactor reaches a value high enough to decompose COS and CS.sub.2 (typically 600.degree. to 650.degree. F.), supplementing the moderately hot first conventional Claus reactor effluent gas with hot (typically 1000.degree. to 1200.degree. F.) waste heat boiler effluent such that the temperature of the regenerating catalyst bed can be elevated to about 700.degree. F. or higher. The intentional temperature excursion to about 700.degree. F. during catalyst regeneration improves the degree of regeneration of the catalyst bed, promotes higher catalyst activity and extends the catalyst life.

Abstract: Claus-type processes used in the past to recover sulfur from low H.sub.2 S acid gas, in the presence of hydrocarbon or other impurities which are harmful to the Claus catalyst, have required the use of straight-through operation with the burning of supplemental fuel gas to maintain the required combustion temperature in the furnace. A method for conserving the amount of additional fuel gas required involving utilization of the excess heat of combustion to preheat the acid gas and oxygen-containing streams to a temperature in excess of 600.degree. F prior to combustion is described. Additional energy savings are achieved by preheating the Claus tail gas effluent prior to incineration.

Abstract: Proper reheat gas temperature is maintained in a sulfur plant operation at a high turn-down ratio by providing parallel flow paths in the boiler and withdrawing portions of the hot products from each of the flow paths and mixing with first condenser effluent to bring the gas to reaction temperature. This maintains the optimum temperature and flow rate of reheat gas at high turn-down ratios.

Abstract: An improved method for further removal of sulfur from the tail gas of a conventional Claus plant by the use of a Cold Bed Adsorption process involving the specific improvement of maintaining at all times the lead Claus reactor of a series of such reactors at sufficiently high temperatures to promote hydrolysis of COS and CS.sub.2 and then utilizing part or all of the hot effluent gases of this lead reactor to regenerate the sulfur-fouled Cold Bed Adsorption catalyst by passing the hot stream through the fouled reactor, removing the deposited sulfur and then returning the stream to the Claus plant at a point essentially immediately downstream from where it was originally withdrawn. Such a method is useful in maintaining ultra-high sulfur conversion levels on a commercial scale.

Abstract: Refinery or similar streams containing NH.sub.3 are processed in a sulfur plant having separate burners for the NH.sub.3 -containing acid gas stream and for the NH.sub.3 -free acid gas stream. A sampling device is provided for continuously or periodically sampling the combustion products from the unit burning the NH.sub.3 -containing gas. The H.sub.2 S/SO.sub.2 ratios at this sample point and in the sulfur plant tail gas are used to control the operation of the system.