# US 10,195,565 B2 · Removal of hydrogen sulfide and sulfur recovery from a gas stream by catalytic direct oxidation and claus reaction

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- Number: US 10,195,565 B2
- Document ID: US10195565B2
- Status: Granted
- Kind: B2
- Application number: 15/539,257
- Filed: 2015-12-23
- Published: 2018-01-11
- Granted: 2019-02-05
- Earliest claimed: 2014-12-24
- Assignees: Prosernat
- Applicants: Prosernat
- Inventors: Michael Heisel; Benoit Mares
- Web page: https://patentgrep.com/patent/US10195565B2

## CPC

- B01D 53/8612: {Hydrogen sulfide}
- B01D 53/52: Hydrogen sulfide
- B01D 53/869: {Multiple step processes}
- B01D 53/90: Injecting reactants
- C01B 17/0404: {by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process}
- C01B 17/0413: {characterised by the combustion step}
- C01B 17/0426: {characterised by the catalytic conversion}
- C01B 17/0447: {Separation of the obtained sulfur}
- C10L 3/103: {Sulfur containing contaminants}
- B01D 2251/11: Air
- B01D 2255/20707: Titanium
- B01D 2255/2092: Aluminium
- B01D 2257/30: Sulfur compounds
- B01D 2257/304: Hydrogen sulfide
- B01D 2257/308: Carbonoxysulfide COS
- B01D 2258/05: Biogas
- C10L 2290/58: Control or regulation of the fuel preparation of upgrading process
- C10L 2290/60: Measuring or analysing fractions, components or impurities or process conditions during preparation or upgrading of a fuel
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS

## Abstract

A process for the removal of hydrogen sulfide and sulfur recovery from a H2S-containing gas stream by catalytic direct oxidation and Claus reaction through two or more serially connected catalytic reactors, wherein a specific control of the oxygen supplement is operated. The control and improvement of the process is obtained by complementing, in each major step of the process, the H2S-containing gas stream by a suitable flow of oxygen, namely before the H2S-containing gas stream enters the Claus furnace, in the first reactor of the process and in the last reactor of the process. Especially in application in a SubDewPoint sulfur recovery process the H2S/SO2 ratio is kept constant also during switch-over of the reactors R1 and R by adding the last auxiliary oxygen containing gas directly upstream the last reactor R so that the H2S/SO2 ratio can follow the signal of the ADA within a few seconds.

## Claims

### Claim 1

A process for the removal of hydrogen sulfide (H2S) from a H2S-containing gas stream through two or more serially connected catalytic reactors, which process comprises:
a) mixing the H2S-containing gas stream with a main oxygen-containing gas stream to obtain a gas stream containing both H2S and oxygen,
b) introducing the obtained gas stream containing both H2S and oxygen into a furnace whereby a gas stream depleted in H2S is obtained,
c) transferring the gas stream depleted in H2S to a sulfur condenser to obtain a gas stream depleted in sulfur,
d) introducing the gas stream depleted in sulfur, optionally together with a first auxiliary oxygen-containing gas stream, into a first catalytic reactor R1 containing a catalyst system which catalyzes the Claus reaction of H2S with sulfur dioxide (SO2), the hydrolysis of COS and CS2 and optionally direct oxidation of H2S with oxygen to sulfur, said reactor being operated at a maximum temperature TR1max between 290 and 350° C., whereby a gas stream depleted in H2S is obtained,
e) transferring the gas stream depleted in H2S to a sulfur condenser to obtain a gas stream depleted in sulfur,
f) optionally introducing the gas stream depleted in sulfur obtained from reactor R1 through a series of reactors and condensers, each reactor containing a catalyst system which catalyzes the Claus reaction of H2S with sulfur dioxide (SO2) before reaching a last reactor R of the process,
g) introducing the gas stream depleted in sulfur together with a last auxiliary oxygen-containing gas stream into the last catalytic reactor R containing a catalyst system which catalyzes the Claus reaction of H2S with sulfur dioxide (SO2) and the direct oxidation of H2S with oxygen to sulfur, said reactor being operated at a maximum temperature TRmax below the maximum temperature TR1max of reactor R1, whereby a gas stream depleted in H2S is obtained,
h) optionally transferring the gas stream depleted in H2S to a sulfur condenser to obtain a gas stream depleted in sulfur,
i) measuring the volumetric ratio of H2S/SO2 at the exit of the last catalytic reactor R,
wherein
the flow rate of oxygen in the main oxygen-containing gas stream and in the optional auxiliary oxygen-containing gas streams represents 96 to 99.9 vol. % of the total flow rate of the oxygen supplemented in the process,
the flow rate of oxygen in the last auxiliary oxygen-containing gas stream represents 0.1 to 4 vol. % of the total flow rate of the oxygen supplemented in the process, and
wherein the flow rate of oxygen in the last auxiliary oxygen-containing gas stream is adjusted depending on the value of the volumetric ratio of H2S/SO2 measured at the exit of the last catalytic reactor R in i) so that the volumetric ratio of H2S/SO2 measured in i) remains between 1.9 and 2.2.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the flow rate of oxygen in the last auxiliary oxygen-containing gas stream is increased when the value of the volumetric ratio of H2S/SO2 measured in i) is above 2, and is decreased when the volumetric ratio of H2S/SO2 measured in i) is below 2.0.

### Claim 3 (depends on 1)

The process according to claim 1, wherein, in a), the flow rate of oxygen in the main oxygen-containing gas stream and in the optional auxiliary oxygen-containing gas streams is calculated so that the volumetric ratio of H2S in the H2S-containing gas stream/O2 in the oxygen-containing gas stream be above the stoichiometric value of the reactions operated in the furnace of 2.

### Claim 4 (depends on 3)

The process according to claim 3, wherein the volumetric ratio of H2S in the H2S-containing gas stream/O2 in the main oxygen-containing gas stream is maintained at 2.002 to 2.5 during the whole process.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the furnace is operated at a temperature of 900° C. to 1400° C.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the gas stream depleted in sulfur obtained in c) further passes through a heater located between the condenser of c) and the reactor R1 of d).

### Claim 7 (depends on 1)

The process according to claim 1, wherein the flow rate of oxygen in the first auxiliary oxygen-containing gas stream is adjusted to ensure that the maximum temperature TR1max in reactor R1 remains between 290 to 350° C.

### Claim 8 (depends on 7)

The process according to claim 7, wherein the temperature TR1max in reactor R1 is maintained between 290 to 350° C.

### Claim 9 (depends on 1)

The process according to claim 1, wherein the catalyst system of reactors R1 and R comprises at least one catalyst that is titanium dioxide (TiO2), cobalt molybdenum, nickel molybdenum, iron, Al2O3, or a mixture thereof.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the reactor R1 comprises two catalytic sections:
a first section containing a first catalyst suitable for direct oxidation of H2S and/or hydrolysis of COS and/or CS2, operated as an adiabatic bed without cooling at a maximum temperature TR1max, and
a second section containing a second catalyst suitable for Claus reaction of H2S, operating as a pseudo-isotherm bed with an internal heat exchanger where the outlet temperature TR1o is not higher than TR1max but is higher than the dew point of the sulfur.

### Claim 11 (depends on 1)

The process according to claim 1, wherein the gas stream depleted in sulfur obtained in e) further passes through a heater located between the condenser of e) or f) and the reactor R of g).

### Claim 12 (depends on 1)

The process according to claim 1, wherein the volumetric ratio of H2S/SO2 at the exit of the last reactor R is maintained from 1.9 to 2.2 during the whole process.

### Claim 13 (depends on 1)

The process according to claim 1, wherein the reactor R is composed of two catalytic sections:
a first section containing a first catalyst suitable for direct oxidation of H2S, operated as an adiabatic bed without cooling at a maximum temperature TRmax from 180 to 240° C., and
a second section containing a second catalyst suitable for Claus reaction of H2S, operating as a pseudo-isotherm bed with an internal heat exchanger where the outlet temperature TRo is higher than water dew point and lower than sulfur dew point.

### Claim 14 (depends on 1)

The process according to claim 1, wherein the operating conditions between the serially connected reactors are switched, and the gas flow is also switched so that the previous last reactor R is operated in the conditions of previous reactor R1, thus becoming new reactor R1, and the previous first reactor R1 is operated in the conditions of previous reactor R, thus becoming new reactor R.

### Claim 15 (depends on 1)

The process according to claim 1, wherein the volumetric ratio of H2S/SO2 at the exit of the new last catalytic reactor R reaches the desired value between 1.9 and 2.2 within 1 seconds to 2 minutes during the whole process.

### Claim 16 (depends on 1)

The process according to claim 1, having a sulfur recovery efficiency above 99 vol. % based on the initial amount of H2S present in the H2S-containing gas stream treated.

### Claim 17 (depends on 1)

The process according to claim 1, wherein if oxygen demand in the last auxiliary oxygen-containing gas stream is higher than 2.5 vol. % of the total flow rate of the oxygen supplemented in the process a signal is sent to the main oxygen-containing gas stream to increase the flow rate of oxygen in the main oxygen-containing gas stream in proportion.

### Claim 18 (depends on 1)

The process according to claim 1, wherein if oxygen demand in the last auxiliary oxygen-containing gas stream is lower than 1.5 vol. %, of the total flow rate of the oxygen supplemented in the process a signal is sent to the main oxygen-containing gas stream to decrease the flow rate of oxygen in the main oxygen-containing gas stream in proportion.

### Claim 19 (depends on 10)

The process according to claim 10, wherein the first catalyst is TiO2 and the second catalyst is Al2O3.

### Claim 20 (depends on 13)

The process according to claim 13, wherein the first catalyst is TiO2 and the second catalyst is Al2O3.

### Claim 21 (depends on 15)

The process according to claim 15, wherein reaches R reaches the desired value after the switch of the reactors by adjustment of the flow rate of the last auxiliary oxygen-containing gas stream.