초록 ▼

The present invention relates to a process and apparatus for processing agricultural waste to make alcohol and/or biodiesel. The agricultural wastes are subjected to anaerobic digestion which produces a biogas stream containing methane, which is subsequently reformed to a syngas containing carbon mo

The present invention relates to a process and apparatus for processing agricultural waste to make alcohol and/or biodiesel. The agricultural wastes are subjected to anaerobic digestion which produces a biogas stream containing methane, which is subsequently reformed to a syngas containing carbon monoxide and hydrogen. The syngas is converted to an alcohol which may be stored, sold, used, or fed directly to a reactor for production of biodiesel. The solids effluent from the anaerobic digester can be further utilized as slow release, organic certified fertilizer. Additionally, the wastewater from the process is acceptable for immediate reuse in agricultural operations.

대표청구항 ▼

1. A method for treating agricultural wastes comprising:anaerobic digesting a mixture of at least agricultural waste and water to yield solids and a biogas including methane and carbon dioxide;reforming the biogas including methane and carbon dioxide to a syngas including carbon monoxide and hydroge

1. A method for treating agricultural wastes comprising:anaerobic digesting a mixture of at least agricultural waste and water to yield solids and a biogas including methane and carbon dioxide;reforming the biogas including methane and carbon dioxide to a syngas including carbon monoxide and hydrogen in a steam reformation process;converting the syngas containing carbon monoxide and hydrogen to methanol in an alcohol conversion process;contacting at least a portion of the methanol with natural fats and/or oils in a transesterification reactor to form glycerine and methyl esters; andseparating the glycerine from the methyl ester. 2. The method according to claim 1, wherein the anaerobic digesting compriss digesting concentrated agricultural waste having a solids content of greater than about 4-8% that is heated prior to digestion. 3. The method according to claim 1, wherein prior to anaerobic digestion, the agricultural waste is concentrated up to about 30% solids, the concentrated agricultural waste then is contacted with water to produce an agricultural waste stream having a solids content from about 4% to about 8%. 4. The method according to claim 1, wherein the anaerobic digesting has a retention rime of less than about 30 days. 5. The method according to claim 1, wherein the agricultural waste is comprised primarily of animal manures. 6. The method according to claim 1, wherein the biogas produced by anaerobic digestion is purified to form a cleaned biogas stream prior to reforming. 7. The method according to claim 6, wherein the biogas is purified by passing the gas through a solvent vessel to remove entrained H 2 S. 8. The method according to claim 7, wherein the biogas is purified by:separating entrained moisture from the biogas by passing the gas through an inlet separator;compressing the separated gas in a feed gas compressor to form a compressed gas stream; andremoving hydrogen sulfide in a hydrogen sulfide absorber wherein the compressed gas stream is contacted with methyldiethanolamine to produce a cleaned biogas stream. 9. The method according to claim 1, wherein reforming the biogas comprises:heating the biogas;reforming the biogas by mixing the heated biogas with steam in the presence of a catalyst to form a hot syngas stream; andcooling the hot syngas stream to form a syngas stream. 10. The method according to claim 9, wherein the syngas stream comprises about 69 mol% hydrogen, about 13 mol % carbon dioxide, and about 17 mol % carbon monoxide. 11. The method according to claim 1, wherein converting the syngas to methanol comprises:compressing the syngas to form a hot, compressed syngas stream;converting the hot, compressed syngas into methanol in a methanol converter to form a hot methanol stream; cooling the hot methanol stream to form a condensed methanol stream; andseparating condensed methanol from gas in a methanol separator. 12. The method according to claim 11, wherein additional carbon dioxide is not added to convert the syngas into methanol. 13. The method according to claim 11, wherein the methanol converter is a catalytic reactor containing a catalyst selected from ZnO—Cr 3 O 3 and CuO—ZnO—Al 2 O 3 . 14. The method according to claim 1, wherein at least a portion of the solids remaining after anaerobic digestion are removed and treated to form fertilizer. 15. A system for treating agricultural waste comprising:an anaerobic digestion apparatus to digest agricultural waste and create solids and a biogas;a biogas reformation apparatus to reform the biogas into a syngas comprising carbon monoxide and hydrogen;and an alcohol conversion apparatus to convert the carbon monoxide and hydrogen into methanol;transesterification reactor to react at least part of the methanol with natural fats and/or oils to form glycerine and methyl esters; anda separation apparatus to separate the glycerine from the methyl esters. 16. The system according to claim 15, further comprising a biogas purif ication system, the biogas purification system comprising:an inlet separator to separate entrained moisture from the biogas;a feed gas compressor to compress the separated gas and to form a compressed gas stream; anda hydrogen suit tie absorber to remove hydrogen sulfide by contacting the compressed gas stream with methyldiethanolamine to produce a cleaned biogas scream. 17. The system according to claim 15, wherein the biogas reformation apparatus comprises:a heater to heat the biogas;a reformer to reform the biogas by mixing the heated biogas with steam in the presence of a catalyst to form a hot syngas stream; anda heat exchanger to cool the hot syngas scream with compressed air to form a syngas stream and a hot air stream. 18. The system according to claim 17, wherein the biogas reformation apparatus further includes an electricity generating apparatus. 19. The system according to claim 18, wherein the electricity generating apparatus comprises:a compressor to compress the hot air stream from the heat exchangera turbine engine connected to the compresseor and to an electrical generator by a common shaft;a combustion apparatus connected to the compressor and turbine engine to provide hot compressed air to the turbine engine; andan electrical generator connected to the turbine engine by the common shaft. 20. The system according to claim 15, further comprising a distillation unit to distill the methanol product. 21. The system according to claim 20, wherein the distillation unit comprises a two-column distillation system comprising:a product cooler to heat the methanol with a product methanol stream;a tapping column to remove lights, the topping column comprising a column reflux condenser, and a purge condenser; anda refining column to produce a product methanol stream, the refining column comprising at least a refining reflux condenser.