Process and device for removal of H.sub.2 S

An apparatus for removing H.sub.2 S present at low concentration in a gas also containing 5 to 60% by volume of water vapor, which comprises in combination:

• a) means for cooling the H.sub.2 S-containing gas and for condensing the water vapor by cooling to a temperature below the dew point of the water, wherein substantially all of the water is condensed and separated, thereby forming a cooled H.sub.2 S-containing substantially free of the water,
• b) means for scrubbing the cooled H.sub.2 S-containing gas with an H.sub.2 -absorbent liquid which is free of the condensed water of step a), so that (i) an absorbent liquid charged with H.sub.2 S is formed and (ii) a purified gas substantially free of the water and H.sub.2 S is formed,
• c) means for maintaining the temperature of the absorbent liquid which is supplied to the scrubbing means below the dew point of the water present in the gas to be treated,
• d) means for contacting the purified gas with excess water including heated condensed water from a), said water heated by heating means wherein the heated condensed water is at a temperature for rehydrating the purified gas, so that the water content as water vapor corresponds to a mass flow rate of water substantially equal to the mass flow rate of the water present in the H.sub.2 S-containing gas, before cooling said gas, and
• e) means for removing excess water not necessary for adjustment of the water to correspond to the water present in the H.sub.2 S-containing gas before cooling said gas.

An apparatus for removing H.sub.2 S present at low concentration in a gas also containing 5 to 60% by volume of water vapor, which comprises, in combination:

• a) means for cooling the H.sub.2 S-containing gas and for condensing the water vapor by cooling to a temperature below the dew point of the water, wherein substantially all of the water is condensed and separated, thereby forming a cooled H.sub.2 S-containing gas substantially free of the water, said cooling means provided with a delivery conduit for the H.sub.2 S-containing gas in its lower part and having an exit for the gas in it upper part and an exit for the condensed water at the bottom,
• b) means for scrubbing the cooled H.sub.2 S-containing gas with an H.sub.2 S-absorbent liquid which is free of the condensed water in step a), so that (i) an absorbent liquid charged with H.sub.2 S is formed and (ii) a purified gas, substantially free of the water and H.sub.2 S is formed, which has an overhead exit for (ii) the purified gas, an entry for the H.sub.2 S-absorbent liquid in its upper part and, in its lower part, an exit for (i) the absorbent liquid charged with H.sub.2 S and a gas entry in its lower part for the cooled gas, said gas entry being connected to the gas exit of the cooling means,
• c) means for maintaining the temperature of the absorbent liquid which is supplied to the scrubbing means below the dew point of the water present in the gas to be treated,
• d) means for contacting the purified gas with excess water including the heated condensed water from a), said water heated by heating means wherein the heated condensed water is at a temperature for rehydrating the purified gas, and so that the water content as water vapor corresponds to a mass flow rate of water substantially equal to the mass flow rate of the water present in the H.sub.2 S-containing gas, before cooling said gas, which has an overhead exit for the rehydrated purified gas, an entry in its upper part for the condensed water from the cooling means and, in its lower part, an exit for the condensed water for cooling the H.sub.2 S-containing gas, and a gas entry in its lower part being in communication with the gas exit of the scrubbing means,
• e) means for removing excess water not necessary for the adjustment of the water to correspond to the water present in the H.sub.2 S-containing gas before cooling said gas, and
• f) means for regenerating and remploying (i) the absorbent liquid charged with H.sub.2 S, so that the H.sub.2 S-absorbent liquid is regenerating and reemploying for the scrubbing of the cooled H.sub.2 S-containing gas, having an overhead exit for an acidic gas, an entry for (i) the absorbent liquid charged with H.sub.2 S in its upper part and an exit for the regenerated H.sub.2 S-absorbent liquid at its bottom, and means for connecting the overhead exit of the regenerating means to a condenser, so that a conduit in the upper part of the condenser removes acidic gas and a conduit in the lower part of the condenser circulates that condensates to the upper part of the regenerating means, and means for connecting the regenerating means and the scrubbing means, so that the entry in the upper part of the regenerating means is connected to the exit in the lower part of the scrubbing means by a conduit on which is mounted a cold circuit of an indirect heat exchanger, and the exit in the lower part of the regenerating means is connected to the entry in the upper part of the scrubbing means by a conduit on which a hot circuit of the indirect heat exchanger is mounted.

An apparatus for removing H.sub.2 S present at low concentration in a gas also containing 5 to 60% by volume of water vapor, which comprises, in combination:

• a) means for cooling the H.sub.2 S-containing gas and for condensing the water vapor by cooling to a temperature below the dew point of the water, wherein substantially all of the water is condensed and separated, thereby forming a cooled H.sub.2 S-containing gas substantially free of the water.
• b) means for scrubbing the cooled H.sub.2 S-containing gas at a temperature below about 70.degree. C. with an H.sub.2 S-absorbent liquid which is free of the condensed water of step a), so that (i) an absorbent liquid charged with H.sub.2 S is formed and (ii) a purified gas substantially free of the water and H.sub.2 S is formed,
• c) means for contacting the purified gas with excess water including heated condensed water from a), said water heated by heating means wherein the heated condensed water is at a temperature for rehydrating the purified gas, so that the water content as water vapor corresponds to a mass flow rate of water substantially equal to the mass flow rate of water present in the H.sub.2 S-containing gas, before cooling said gas, and
• d) means for removing excess water not necessary for the adjustment of the water to correspond to the water present in the H.sub.2 S-containing gas before cooling said gas.

A process for the removal of H.sub.2 S present at low concentration in a gas also containing 5 to 60% by volume of water vapor, which comprises the steps of:

• a) cooling the H.sub.2 S-containing gas to a temperature below the dew point of the water, thereby condensing the water vapor, separating substantially all of the water and forming a cooled H.sub.2 S-containing gas, substantially free of the water,
• b) scrubbing the cooled H.sub.2 S-containing gas, substantially free of the water, at a temperature below about 70.degree. C. with an H.sub.2 S-absorbent liquid which is free of the condensed water of step a), forming (i) an absorbent liquid charged with H.sub.2 S and (ii) a purified gas, substantially free of water and H.sub.2 S,
• c) contacting the (ii) purified gas with an excess of water including heated condensed water from step a), the temperature of the heated condensed water being such that the purified gas is rehydrated, so that the water content as water vapor corresponds to a mass flow rate of water substantially equal to the mass flow rate of the water present in the H.sub.2 S-containing gas before cooling said gas and removing excess water not necessary for the adjustment of the water to correspond to that of the water present in the H.sub.2 S containing gas before cooling said gas, and
• d) incinerating the rehydrated purified gas prior to discharge into the atmosphere.