Gas Research Institute

Crystatech, Inc.

Electric Power Research Institute Incorporated

Urs Corporation

Southern California Edison Company

Radian Corporation

Sumx Corporation

David W DeBerry

William A Steen

Jennifer L Paradis

John E Currie

Gary M Blythe

Dennis Dalrymple

Timothy W Trofe

Kevin S Fisher

Alfred Viehbeck

Judith Gres DeBerry, Legal Representative

An improvement in the method for preventing re-emissions of mercury from a wet flue gas desulfurization (FGD) system by addition of an additive to the FGD scrubber liquor which interacts in the system scrubber with mercury present in the flue gas to curtail the mercury re-emissions; the mercury re-emissions are reduced to substantially zero by use of an additive selected from one or more members of the group consisting of a dithiol, a dithiolane, and a thiol having a single thiol group and either an oxygen or a hydroxyl group.

Method for preventing re-emission of mercury from a flue gas desulfurization system

Generally, the present invention provides a method and apparatus for removing a vapor phase contaminant from a gas stream, thereby reducing the concentration of the vapor phase contaminant in the gas stream. In one embodiment, the present invention provides a method for removing a vapor phase contaminant from a gas stream, comprising contacting a gas stream comprising a vapor phase contaminant with a first side of a membrane; sorbing the vapor phase contaminant using the membrane; reacting the vapor phase contaminant into an reacted form of the vapor phase contaminant; transporting the reacted form of the vapor phase contaminant through the membrane to a second side of the membrane; contacting the second side of the membrane with a liquid; and dissolving the reacted form of the vapor phase contaminant into the liquid. Methods for making a membrane comprising a metal for use in the present invention is also described.

Reactive membrane process for the removal of vapor phase contaminants

A process for removing H S from a gaseous stream, wherein the gaseous stream is flowed through an absorber vessel where the stream is contacted with a sorbing liquor comprising a nonaqueous solvent containing dissolved sulfur, a tertiary amine base having sufficient strength and concentration to drive the reaction between H S sorbed by the liquor and the dissolved sulfur to form a nonvolatile polysulfide which is soluble in the sorbing liquor, and a solubilizing agent for maintaining the solubility of polysulfide intermediates which may otherwise separate. The dissolved nonvolatile polysulfide in the sorbing liquor is converted to sulfur which remains dissolved in the liquor by contacting the liquor with oxidizing sulfur dioxide. The sorbing liquor following the oxidation of the polysulfide is cooled to a temperature at which the liquor is at or above saturation with respect to the dissolved sulfur. At least part of the dissolved sulfur in the saturated liquor is converted to solid particulate sulfur at a point downstream of the absorber vessel, and the solid sulfur is separated from the liquor.

Process for removing hydrogen sulfide from gas streams which include or are supplemented with sulfur dioxide, by scrubbing with a nonaqueous sorbent

A process is provided for the removal of hydrogen sulfide out of a gaseous stream ( ), such as a natural gas, by contacting the hydrogen sulfide containing gas with a sorbing liquid ( ) containing a tertiary amine so that the hydrogen sulfide is sorbed into the liquid in absorber ( ) and transferring the sorbing liquid/hydrogen sulfide mixture to a reactor ( ) where the tertiary amine promotes the conversion of the hydrogen sulfide into polysulfide via reaction with sulfur; transferring the polysulfide solution from the reactor ( ) to a regenerator ( ) where polysulfide is converted into elemental sulfur via reaction with air ( ); transferring at least a portion of the solution ( ) containing elemental sulfur, as well as sulfate and thiosulfate species, into a mixture ( ) where it is contacted with gaseous ammonia which reacts with the sulfate and thiosulfate species to produce ammonium sulfate and ammonium thiosulfate which are removed from the solution while the remaining portion of solution ( ) is transferred to a sulfur recovery unit ( ). That portion of the solution which has been subjected to ammonium sulfate and ammonium thiosulfate removal is rejoined with that portion of the solution ( ) being forwarded to sulfur recovery unit ( ). The solution from the sulfur recovery unit ( ) is recycled back to the absorber ( ).

Regeneration method for process which removes hydrogen sulfide from gas streams

In a known process and system wherein hydrogen sulfide is removed from a gaseous stream, using a non-aqueous scrubbing liquor which can be an organic solvent for elemental sulfur such as a phenylxylyl ethane in which are dissolved sulfur and a reaction-promoting amine base such as a tertiary amine, sulfur dioxide is added to the sulfur-amine nonaqueous sorbent (or advantage is taken of SO which may already be present in the gas stream) to obtain better H S removal, lower chemical degradation rates, and lower rates of formation of byproduct sulfur salts such as sulfates.

Process for removing hydrogen sulfide from gas streams which include or are supplemented with sulfur dioxide

A system for removing hydrogen sulfide from a gaseous stream such as one of natural gas. A sour gas stream containing H.sub.2 S is contacted with a nonaqueous, water-insoluble sorbing liquor which comprises an organic solvent for elemental sulfur, dissolved elemental sulfur, an organic base to promote the reactions, and an organic solubilizing agent an agent suitable for maintaining the solubility of polysulfide intermediates which may otherwise separate when they are formed during operation of the process. Hydrogen sulfide (H.sub.2 S) gas is sorbed into this liquor and then reacts with the dissolved sulfur in the presence of the base to form polysulfide molecules. The solution is then sent to a reactor where sufficient residence time is provided to allow the polysulfide forming reactions to reach the desired degree of completion. From the reactor, the solution flows to a regenerator where the solution is oxidized (e.g., by contact with air), forming dissolved elemental sulfur and water. The temperature of the solution is then lowered, forming sulfur crystals, which are easily removed by gravity settling, filtration, centrifuge, or other separation method. Enough sulfur remains dissolved in the solution following removal of the sulfur crystals that when this solution is reheated and returned to the absorber a sufficient amount of sulfur is present to react with the inlet H.sub.2 S gas.

System for removal of hydrogen sulfide from a gas stream

A process and system for removing hydrogen sulfide from a gaseous stream such as one of natural gas. A sour gas stream containing H.sub.2 S is contacted with a nonaqueous, water-insoluble sorbing liquor which comprises an organic solvent for elemental sulfur, dissolved elemental sulfur, an organic base to promote the reactions, and an organic solubilizing agent an agent suitable for maintaining the solubility of polysulfide intermediates which may otherwise separate when they are formed during operation of the process. Hydrogen sulfide (H.sub.2 S) gas is sorbed into this liquor and then reacts with the dissolved sulfur in the presence of the base to form polysulfide molecules. The solution is then sent to a reactor where sufficient residence time is provided to allow the polysulfide forming reactions to reach the desired degree of completion. From the reactor, the solution flows to a regenerator where the solution is oxidized (e.g., by contact with air), forming dissolved elemental sulfur and water. The temperature of the solution is then lowered, forming sulfur crystals, which are easily removed by gravity settling, filtration, centrifuge, or other separation method. Enough sulfur remains dissolved in the solution following removal of the sulfur crystals that when this solution is reheated and returned to the absorber a sufficient amount of sulfur is present to react with the inlet H.sub.2 S gas.

Process for removal of hydrogen sulfide from a gas stream

A method and apparatus for the removal of hydrogen sulfide (H.sub.2 S) from gaseous streams, particularly concentrations of H.sub.2 S lower than 100 ppm. The invention is particularly useful for removing H.sub.2 S from natural gas. The invention involves contacting a gaseous stream containing hydrogen sulfide with a sorbent solution comprising a substantially non-aqueous solvent having a low vapor pressure and a high donor number, such as dimethyl sulfoxide, a concentration of a polyvalent reducible metal ion in an oxidative state sufficient to oxidize the hydrogen sulfide to form at least one soluble sulfur compound, such as Fe.sup.3+, and a counter-ion for the metal ion, such as Cl.sup.- ; and regenerating the oxidative state of the metal ion reduced by the hydrogen sulfide.

Composition and process for the removal of hydrogen sulfide from gaseous

A process and system for removal of hydrogen sulfide from a hydrogen sulfide-containing gaseous stream comprising contacting the hydrogen sulfide-containing gaseous stream with a nonaqueous phase sorbent under conditions suitable for forming a hydrogen sulfide-laden sorbent and a clean gaseous stream. The hydrogen sulfide-laden sorbent is mixed with an aqueous phase redox coupled, regenerating the nonaqueous phase sorbent, reducing the aqueous phase redox couple, and forming sulfur. The sulfur is separated from the mixture. The reduced aqueous phase redox couple is extracted from the mixture and regenerated with an oxidizing agent or electrochemical cell.

Double loop liquid-liquid H.sub.2 S removal process

A solid electrochromic film is used on a semiconductor electrode in a display device permitting the user to write on the display using a light pen. Additional elements, including arrangement of the semiconductor electrodes transversely with respect to counter-electrodes, or providing an electrochromic film on the counter-electrodes, further enhance the versatility of the display device.

Photoelectrochromic display

An apparatus and method for removing oxides of nitrogen and sulfur from flue gases. The apparatus comprises an enclosure wherein the flue gases are washed with a scrubbing solution, preferably containing ferrous chelates and sulfite ions, and an electrochemical cell for regenerating the spent scrubbing solution. The electrochemical cell preferably comprises a plurality of cathode and anode compartments separated by ion transfer membranes. The spent scrubbing solution is regenerated by passing the solution through the cathode compartments of the electrochemical cell. The regeneration process involves the removal of the sulfate ions from the scrubbing solutions through the ion transfer membranes and the reduction of the nonreactive ferric chelate to the reactive ferrous chelate.

Ferrous ion scrubbing of flue gas

Methods and apparatus are disclosed herein for measuring the electrical conductivity of unknown fluid solutions. A constant current DC pulse having a very fast rise time is supplied to a test cell containing the unknown solution. By sampling the voltage across the test cell just prior to the application of the pulse and at a predetermined time during the application of the constant current pulse, a voltage difference is obtained which may be interpreted in terms of the conductivity of the unknown solution.

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Austin, TX, United States of America

David W DeBerry