Two-Train Catalytic Gasification Systems

• US 20090324458A1
• Filed: 06/26/2009
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Abandoned Application

• Current Assignee: Sure Champion Investments Limited
• Original Assignee: GreatPoint Energy, Inc.
• Inventors: Robinson, Earl T., Lau, Francis S., Dodson, Dwain
• Application Number:
  US12/492,467
• Publication Number:
  US 20090324458A1
• Time in Patent Office: Days
• US Class Current: 422/187
• CPC Class Codes: C10J 2200/09 Mechanical details of gasifiers not otherwise provided for, e.g. sealing means
• CPC Class Codes: C10J 2300/0903 Feed preparation
• CPC Class Codes: C10J 2300/0906 Physical processes, e.g. shredding, comminuting, chopping, sorting
• CPC Class Codes: C10J 2300/093 Coal
• CPC Class Codes: C10J 2300/0973 Water
• CPC Class Codes: C10J 2300/0986 Catalysts
• CPC Class Codes: C10J 2300/1662 to methane (SNG) production of synthetic natural gas C10L3/08
• CPC Class Codes: C10J 2300/1671 with the production of electricity
• CPC Class Codes: C10J 2300/1675 making use of a steam turbine
• CPC Class Codes: C10J 2300/1687 with steam generation
• CPC Class Codes: C10J 2300/169 with water treatments treatment of water in general or water purification C02F
• CPC Class Codes: C10J 2300/1807 Recycle loops, e.g. gas, solids, heating medium, water
• CPC Class Codes: C10J 2300/1823 for synthesis gas
• CPC Class Codes: C10J 2300/1853 Steam reforming, i.e. injection of steam only
• CPC Class Codes: C10J 2300/1884 with one stream being synthesis gas
• CPC Class Codes: C10J 3/00 Production of combustible gases containing carbon monoxide from solid carbonaceous fuels destructive distillation processes C10B
• CPC Class Codes: C10J 3/30 Fuel charging devices
• CPC Class Codes: C10J 3/482 Gasifiers with stationary fluidised bed
• CPC Class Codes: C10J 3/721 Multistage gasification, e.g. plural parallel or serial gasification stages
• CPC Class Codes: C10K 1/002 Removal of contaminants
• CPC Class Codes: C10K 1/004 : Sulfur containing contaminants, e.g. hydrogen sulfide
• CPC Class Codes: C10K 1/005 : Carbon dioxide
• CPC Class Codes: C10K 1/006 : Hydrogen cyanide
• CPC Class Codes: C10K 1/007 : of metal compounds
• CPC Class Codes: C10K 1/101 : with water only
• CPC Class Codes: C10K 1/102 : containing free acid
• CPC Class Codes: C10K 1/103 : alkali- or earth-alkali- or NH4 salts or inorganic acids derived from sulfur
• CPC Class Codes: C10K 1/14 : organic
• CPC Class Codes: C10K 1/143 : containing amino groups
• CPC Class Codes: C10K 1/16 : with non-aqueous liquids
• CPC Class Codes: C10K 1/165 : at temperatures below zero degrees Celsius
• CPC Class Codes: C10K 1/20 : by treating with solids; Regenerating spent purifying masses separation by adsorption B01D53/02; separation by chemical reaction B01D53/34; refining of hydrocarbon oils with acids C10G17/02, C10G27/02, C10G29/12
• CPC Class Codes: C10K 1/32 : with selectively adsorptive solids, e.g. active carbon
• CPC Class Codes: C10K 3/04 : reducing the carbon monoxide content , e.g. water-gas shift [WGS]

Abstract

Systems for converting a carbonaceous feedstock into a plurality of gaseous products are described. The systems include, among other units, two separate gasification reactors to convert a carbonaceous feedstock in the presence of an alkali metal catalyst into the plurality of gaseous products including at least methane. Each of the gasification reactors may be supplied with the feedstock from a single or separate catalyst loading and/or feedstock preparation unit operations. Similarly, the hot gas streams from each gasification reactor may be purified via their combination at a heat exchanger, acid gas removal, or methane removal unit operations. Product purification may comprise trace contaminant removal units, ammonia removal and recovery units, and sour shift units.

Claims

1. A gasification system to generate a plurality of gases from a catalyzed carbonaceous feedstock, the system comprising:

(a) a first and a second gasifying reactor unit, wherein each gasifying reactor unit independently comprises;

(A1) a reaction chamber in which a catalyzed carbonaceous feedstock and steam are converted to (i) a plurality of gaseous products comprising methane, hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide and unreacted steam, (ii) unreacted carbonaceous fines and (iii) a solid char product comprising entrained catalyst;

(A2) a feed inlet to supply the catalyzed carbonaceous feedstock into the reaction chamber;

(A3) a steam inlet to supply steam into the reaction chamber;

(A4) a hot gas outlet to exhaust a hot first gas stream out of the reaction chamber, the hot first gas stream comprising the plurality of gaseous products;

(A5) a char outlet to withdraw the solid char product from the reaction chamber; and

(A6) a fines remover unit to remove at least a substantial portion of the unreacted carbonaceous fines that may be entrained in the hot first gas stream;

(b) (1) a single catalyst loading unit to supply the catalyzed carbonaceous feedstock to the feed inlets of both the first and second gasifying reactor units, or

(2) a first and a second catalyst loading unit to supply the catalyzed carbonaceous feedstock to the feed inlets of the first and second gasifying reactor units,

wherein each catalyst loading unit independently comprises,

(B1) a loading tank to receive one or more carbonaceous particulates and to load a catalyst onto the particulates to form the catalyzed carbonaceous feedstock; and

(B2) a dryer to thermally treat the catalyzed carbonaceous feedstock to reduce moisture content;

(c) (1) when only the single catalyst loading unit is present, a single carbonaceous material processing unit to supply the carbonaceous particulates to the loading tank of the single catalyst loading unit, or

(2) when the first and second catalyst loading units are present, (i) a single carbonaceous material processing unit to supply the carbonaceous particulates to the loading tanks of both the first and second catalyst loading units, or (ii) a first and a second carbonaceous material processing unit to supply the carbonaceous particulates to the loading tanks of the first and second catalyst loading units,

wherein each carbonaceous material processing unit independently comprises;

(C1) a receiver to receive and store a carbonaceous material; and

(C2) a grinder to grind the carbonaceous material into the carbonaceous particulates, the grinder in communication with the receiver;

(d) (1) a single heat exchanger unit to remove heat energy from the hot first gas streams from both the first and second gasifying reactor units to generate steam and produce a single cooled first gas stream, or

(2) a first and a second heat exchanger unit to remove heat energy from the hot first gas stream from the first and second gasifying reactor units to generate steam, a first cooled first gas stream and a second cooled first gas stream;

(e) (1) when only the single heat exchanger unit is present, a single acid gas remover unit to remove at least a substantial portion of the carbon dioxide and at least a substantial portion of the hydrogen sulfide from the single cooled first gas stream, to produce a single acid gas-depleted gas stream comprising at least a substantial portion of the methane, at least a substantial portion of the hydrogen and, optionally, at least a portion of the carbon monoxide from the single cooled first gas stream, or

(2) when the first and second heat exchanger units are present, (i) a single acid gas remover unit to remove at least a substantial portion of the carbon dioxide and at least a substantial portion of the hydrogen sulfide from the first cooled first gas stream and the second cooled first gas stream, to produce a single acid gas-depleted gas stream comprising at least a substantial portion of the methane, at least a substantial portion of the hydrogen and, optionally, at least a portion of the carbon monoxide from both of the first and second cooled first gas streams, or (ii) a first and a second acid gas remover unit to remove at least a substantial portion of the carbon dioxide and at least a substantial portion of the hydrogen sulfide from the first and second cooled first gas stream to produce a first acid gas-depleted gas stream and a second acid gas-depleted gas stream, wherein the first and second acid gas-depleted gas streams together comprise at least a substantial portion of the methane, at least a substantial portion of the hydrogen and, optionally, at least a portion of the carbon monoxide from the first and second cooled first gas streams;

(f) (1) when only the single acid gas-depleted stream is present, a single methane removal unit to separate and recover at least a substantial portion of the methane from the single acid gas-depleted gas stream to produce a single methane-depleted gas stream and a single methane product stream, wherein the single methane product stream comprises at least a substantial portion of the methane from the single acid gas-depleted gas stream, or

(2) when the first and second acid gas-depleted gas streams are present, (i) a single methane removal unit to separate and recover at least a substantial portion of the methane from the first and second acid gas-depleted gas streams to produce a single methane-depleted gas stream and a single methane product stream, or (ii) a first and a second methane removal unit to separate and recover at least a substantial portion of the methane from the first and second acid gas-depleted gas streams to produce a first methane-depleted gas stream and a first methane product stream, and a second methane-depleted gas stream and a second methane product stream, wherein the first and second methane product streams together comprise at least a substantial portion of the methane from the first and second acid gas-depleted gas streams; and

(g) (1) a single steam source to supply steam to the steam inlets of the first and second gasifying reactor units, or

(2) a first and a second steam source to supply steam to the steam inlets of the first and second gasifying reactor units.

2. The system according to claim 1, wherein the system further comprises one or more of:

(h) a trace contaminant removal unit between a heat exchanger unit and an acid gas remover unit, to remove at least a substantial portion of one or more trace contaminants from the single cooled first gas stream, or, when present, one or more of the first and second cooled first gas streams, wherein the single cooled first gas stream or the one or more of the first and second cooled first gas streams further comprise one or more trace contaminants comprising one or more of COS, Hg and HCN;

(i) a reformer unit to convert a portion of the single methane product stream, or when present, at least a portion of one or more of the first and second methane product streams into a syngas;

(j) a methane compressor unit to compress at least a portion of the single methane product stream, or when present, one or more of the first and second methane product streams;

(k) a carbon dioxide recovery unit to separate and recover carbon dioxide removed by the single acid gas remover unit, or when present, one or more of the first and second acid gas remover units;

(l) a sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the single acid gas remover unit, or when present, one or more of the first and second acid gas remover units;

(m) a catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product, and recycle at least a portion of the recovered catalyst to the single catalyst loading unit, or when present, one or more of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of the single methane-depleted gas stream, or when present, at least a portion of one or more of the first and second methane-depleted gas streams, to at least one or more of the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat the steam in or from the single steam source, or when present the first steam source and/or second steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source, or when present the first steam source and/or the second steam source; and

(r) a sour shift unit between a heat exchanger and an acid gas remover unit, to contact a cooled first gas stream with an aqueous medium under conditions suitable to convert at least a portion of carbon monoxide in the cooled first gas stream to carbon dioxide.

3. The system according to claim 1, wherein the system comprises:

(a) the first and second gasifying reactor units;

(b) the first and second catalyst loading units;

(c) the single carbonaceous material processing unit;

(d) the first and second heat exchanger units;

(e) the first and second acid gas remover units;

(f) the first and second methane removal units; and

(g) the single steam source.

4. The system according to claim 3, wherein the system further comprises one or more of:

(h) a first and a second trace contaminant removal unit between the first and second heat exchanger units and the first and second acid gas remover units, to remove at least a substantial portion of one or more trace contaminants from the first and second cooled first gas streams;

(i) a single reformer unit to convert a portion of one or both of the first and second methane product streams into a syngas;

or a first and a second reformer unit to convert a portion of the first and second methane product streams into a syngas;

(j) a single methane compressor unit to compress at least a portion of one or both of the first and second methane product streams;

or a first and a second methane compressor unit to compress at least a portion of the first and second methane product streams;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the first and second acid gas remover units;

or a first and a second carbon dioxide recovery unit to separate and recover carbon dioxide removed by the first and second acid gas remover units;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the first and second acid gas remover units;

or a first and a second sulfur recovery unit to extract and recover sulfur removed by the first and second acid gas remover units;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

or a first and a second catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion the solid char product from the first and second gasifying reactor units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of one or both of the first and second methane-depleted gas streams to one or both of the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) a first and a second sour shift unit between the first and second heat exchanger units and the first and second acid gas remover units, to convert at least a portion of carbon monoxide in the first and second cooled first gas streams to carbon dioxide.

5. The system according to claim 3, wherein the system further comprises one or more of:

(h) a first and a second trace contaminant removal unit between the first and second heat exchanger units and the first and second acid gas remover units, to remove at least a substantial portion of one or more trace contaminants from the first and second cooled first gas streams;

(i) a single reformer unit to convert a portion of one or both of the first and second methane product streams into a syngas;

or a first and a second reformer unit to convert a portion of the first and second methane product streams into a syngas;

(j) a single methane compressor unit to compress at least a portion of one or both of the first and second methane product streams;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the first and second acid gas remover units;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the first and second acid gas remover units;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of one or both of the first and second methane-depleted gas streams to one or both the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) a first and a second sour shift unit between the first and second heat exchanger units and the first and second acid gas remover units, to convert at least a portion of carbon monoxide in the first and second cooled first gas streams to carbon dioxide.

6. The system according to claim 1, wherein the system comprises:

(a) the first and second gasifying reactor units;

(b) the single catalyst loading unit;

(c) the single carbonaceous material processing unit;

(d) the single heat exchanger unit;

(e) the single acid gas remover unit;

(f) the single methane removal unit; and

(g) the single steam source.

7. The system according to claim 6, wherein the system further comprises one or more of:

(h) a single trace contaminant removal unit between the single heat exchanger unit and the single acid gas remover unit, to remove at least a substantial portion of one or more trace contaminants from the single cooled first gas stream;

(i) a single reformer unit to convert a portion of the single methane product stream into a syngas, or a first reformer unit and a second reformer unit to convert a portion of the single methane product stream into a syngas;

(j) a single methane compressor unit to compress at least a portion of the single methane product stream;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the single acid gas remover unit;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the single acid gas remover unit;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to the single catalyst loading unit;

or a first and a second catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying reactor units, and recycle at least a portion of the recovered catalyst to the single catalyst loading unit;

(n) a gas recycle loop to recycle at least a portion of the single methane-depleted gas stream to one or both the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source; and

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) a single sour shift unit between the single heat exchanger unit and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the single cooled first gas streams to carbon dioxide.

8. The system according to claim 1, wherein the system comprises:

(a) the first and second gasifying reactor units;

(b) the first and second catalyst loading units;

(c) the first and second carbonaceous material processing units;

(d) the single heat exchanger unit;

(e) the single acid gas remover unit;

(f) the single methane removal unit; and

(g) the single steam source.

9. The system according to claim 1, wherein the system comprises:

(a) the first and second gasifying reactor units;

(b) the first and second catalyst loading units;

(c) the single carbonaceous material processing unit;

(d) the single heat exchanger unit;

(e) the single acid gas remover unit;

(f) the single methane removal unit; and

(g) the single steam source.

10. The system according to claim 8, wherein the system further comprises one or more of:

(h) a single trace contaminant removal unit between the single heat exchanger unit and the single acid gas remover unit to remove at least a substantial portion of one or more trace contaminants from the single cooled first gas stream;

(i) a single reformer unit to convert a portion of the single methane product stream into a syngas, or a first reformer unit and a second reformer unit to convert a portion of the single methane product stream into a syngas;

(j) a single methane compressor unit to compress at least a portion of the single methane product stream;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the single acid gas remover unit;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the single acid gas remover units;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

or a first and a second catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying reactor units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of the single methane-depleted gas stream to the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) single sour shift unit between the single heat exchanger unit and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the single cooled first gas streams to carbon dioxide.

11. The system according to claim 9, wherein the system further comprises one or more of:

(h) a single trace contaminant removal unit between the single heat exchanger unit and the single acid gas remover unit to remove at least a substantial portion of one or more trace contaminants from the single cooled first gas stream;

(i) a single reformer unit to convert a portion of the single methane product stream into a syngas, or a first reformer unit and a second reformer unit to convert a portion of the single methane product stream into a syngas;

(j) a single methane compressor unit to compress at least a portion of the single methane product stream;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the single acid gas remover unit;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the single acid gas remover units;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

or a first and a second catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying reactor units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of the single methane-depleted gas stream to the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) single sour shift unit between the single heat exchanger unit and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the single cooled first gas streams to carbon dioxide.

12. The system according to claim 1, wherein the system comprises:

(a) the first and second gasifying reactor units;

(b) the first and second catalyst loading units;

(c) the single carbonaceous material processing unit;

(d) the first and second heat exchanger units;

(e) the single acid gas remover unit;

(f) the single methane removal unit; and

(g) the single steam source.

13. The system according to claim 12, wherein the system further comprises one or more of:

(h) a single trace contaminant removal unit between the first and second heat exchanger units and the single acid gas remover unit to remove at least a substantial portion of one or more trace contaminants from the first and second cooled first gas streams;

or a first and a second trace contaminant removal unit between the first and second heat exchanger units and the single acid gas remover unit to remove at least a substantial portion of one or more trace contaminants from the first and second cooled first gas streams;

(i) a single reformer unit to convert a portion of the single methane product stream into a syngas, or a first reformer unit and a second reformer unit to convert a portion of the single methane product stream into a syngas;

(j) a single methane compressor unit to compress at least a portion of the single methane product stream;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the single acid gas remover unit;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the single acid gas remover units;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

or a first and a second catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion the solid char product from the first and second gasifying reactor units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of the single methane-depleted gas stream to one or both of the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) a single sour shift unit between the first and second heat exchangers and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the first and second cooled gas streams into a syngas, or a first and a second sour shift unit between the first and second heat exchanger units and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the first and second cooled first gas streams to carbon dioxide.

14. The system according to claim 1, wherein the system comprises:

(a) the first and second gasifying reactor units;

(b) the single catalyst loading unit;

(c) the single carbonaceous material processing unit;

(d) the first and second heat exchanger units;

(e) the single acid gas remover unit;

(f) the single methane removal unit; and

(g) the single steam source.

15. The system according to claim 14, wherein the system further comprises one or more of:

(h) a single trace contaminant removal unit between the first and second heat exchanger units and the single acid gas remover unit to remove at least a substantial portion of one or more trace contaminants from the first and second cooled first gas streams;

or a first and a second trace contaminant removal unit between the first and second heat exchanger units and the single acid gas remover unit to remove at least a substantial portion of one or more trace contaminants from the first and second cooled first gas streams;

(i) a single reformer unit to convert a portion of the single methane product stream into a syngas, or a first reformer unit and a second reformer unit to convert a portion of the single methane product stream into a syngas;

(j) a single methane compressor unit to compress at least a portion of the single methane product stream;

(k) a single carbon dioxide recovery unit to separate and recover carbon dioxide removed by the single acid gas remover unit;

(l) a single sulfur recovery unit to extract and recover sulfur from the hydrogen sulfide removed by the single acid gas remover units;

(m) a single catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion of the solid char product from the first and second gasifying units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

or a first and a second catalyst recovery unit to extract and recover at least a portion of the entrained catalyst from at least a portion the solid char product from the first and second gasifying reactor units, and recycle at least a portion of the recovered catalyst to one or both of the first and second catalyst loading units;

(n) a gas recycle loop to recycle at least a portion of the single methane-depleted gas stream to one or both of the first and second gasifying reactor units;

(o) a waste water treatment unit to treat waste water generated by the system;

(p) a superheater to superheat steam in or from the single steam source;

(q) a steam turbine to generate electricity from at least a portion of the steam supplied by the single steam source; and

(r) a single sour shift unit between the first and second heat exchangers and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the first and second cooled gas streams into a syngas, or a first and a second sour shift unit between the first and second heat exchanger units and the single acid gas remover unit, to convert at least a portion of carbon monoxide in the first and second cooled first gas streams to carbon dioxide.

16. The system according to claim 2, wherein the system comprises (r) and a trim methanator between an acid gas remover unit and a methane removal unit.

17. The system according to claim 2, comprising at least (k), (l) and (m).

18. The system according to claim 2, wherein the system comprises (k), and the system further comprises a carbon dioxide compressor unit to compress the recovered carbon dioxide.

19. The system according to claim 7, wherein the system comprises (r) and a trim methanator between an acid gas remover unit and a methane removal unit.

20. The system according to claim 7, comprising at least (k), (l) and (m).

21. The system according to claim 7, wherein the system comprises (k), and the system further comprises a carbon dioxide compressor unit to compress the recovered carbon dioxide.

22. The system according to claim 15, wherein the system comprises (r) and a trim methanator between an acid gas remover unit and a methane removal unit.

23. The system according to claim 15, comprising at least (k), (l) and (m).

24. The system according to claim 15, wherein the system comprises (k), and the system further comprises a carbon dioxide compressor unit to compress the recovered carbon dioxide.

25. The system according to claim 1, wherein the system produces a product stream of pipeline-quality natural gas.