Hydrothermal Conversion Process

• US 20150361372A1
• Filed: 06/08/2015
• Published: 12/17/2015
• Est. Priority Date: 06/11/2014
• Status: Active Grant

• Current Assignee: Alireza Shekarriz
• Original Assignee: Alireza Shekarriz
• Inventors: Shekarriz, Alireza
• Granted Patent: US 9,695,093 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C05F 11/00 Other organic fertilisers
• CPC Class Codes: C05F 17/00 Preparation of fertilisers characterised by biological or biochemical treatment steps, e.g. composting or fermentation
• CPC Class Codes: C05F 7/00 Fertilisers from waste water, sewage sludge, sea slime, ooze or similar masses
• CPC Class Codes: C10L 1/00 Liquid carbonaceous fuels
• CPC Class Codes: C10L 2290/06 Heat exchange, direct or indirect
• CPC Class Codes: C10L 2290/148 of steam
• CPC Class Codes: C10L 2290/26 Composting, fermenting or anaerobic digestion fuel components or materials from which fuels are prepared
• CPC Class Codes: C10L 2290/58 Control or regulation of the fuel preparation of upgrading process
• CPC Class Codes: C10L 5/445 Agricultural waste, e.g. corn crops, grass clippings, nut shells or oil pressing residues
• CPC Class Codes: C10L 5/447 Carbonized vegetable substances, e.g. charcoal, or produced by hydrothermal carbonization of biomass
• CPC Class Codes: C10L 9/086 Hydrothermal carbonization
• CPC Class Codes: Y02A 40/20 Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02P 20/129 Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 20/145 the feedstock being materials of biological origin
• CPC Class Codes: Y02W 30/40 Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse

Abstract

A hydrothermal conversion process includes a mixing step wherein an aqueous slurry of a solid feedstock material with a steam stream to produce a reaction mixture having a temperature of at least 160° C. and which is at a pressure sufficient to keep water as a subcooled liquid. The process is fast and effective, requires only simple equipment and is highly energy-efficient. The process is also readily scalable, can be operated continuously or semi-continuously and can be tailored to produce carbonized solids or liquefaction products, all of which typically have increased economic value compared with the starting materials.

Claims

1. A hydrothermal conversion process wherein a particulate solid organic feedstock is reacted with water at a temperature of at least 160°

at a superatmospheric pressure sufficient to maintain the water in subcooled liquid state to produce one or more hydrothermal conversion products selected from a) a carbonized solid and b) at least one liquefaction product, wherein

1) an aqueous slurry of particles of the organic feedstock in liquid water and having a temperature of up to 100°

C. is mixed under elevated pressure with a steam stream, under conditions such that upon mixing all or a portion of the steam condenses and a reaction mixture having a temperature of at least 160°

C. is formed at a pressure such that water including the condensed steam remains as a subcooled liquid;

2) the reaction mixture is maintained at a temperature of at least 160°

C. and at a temperature sufficient to maintain water including the condensed steam as a subcooled liquid for a period of time sufficient to produce the one or more hydrothermal conversion products; and

then

3) recovering the one or more hydrothermal conversion products.

2. The process of claim 1 wherein steps 1) and 2) each are performed under plug flow conditions.

3. The process of claim 1 wherein steps 1) and 2) each are performed in a pipe reactor.

4. The process of claim 1 wherein steps 1) and 2) are performed in an apparatus comprising

a) a mixing zone in which the aqueous slurry of particles is mixed with the steam stream to produce the reaction mixture;

b) at least two reaction zones each separately in fluid communication with the mixing zone via a flow path and

c) distribution means for distributing a reaction mixture produced in the mixing zone among the reaction zones;

wherein the distributor includes valving means for selectively opening and closing the flow path to each of the reaction zones for selectively opening the flow path to one or more of the reaction zones while simultaneously closing the flow path to at least one other reaction zone.

5. The process of claim 1 wherein the step of mixing the aqueous slurry with the steam stream is performed in a mixing zone by injecting the steam stream through one or more nozzles or bubblers into a pipe that contains the slurry.

6. The process of claim 1 wherein the reaction performed in step 2) is exothermic, waste heat from the exothermic reaction is captured and the captured waste heat is used to preheat the aqueous slurry prior to introducing the aqueous slurry into step 2).

7. The process of claim 1 wherein in step a), the reaction mixture attains a temperature of at least 160°

C. within 10 seconds of mixing the steam with the aqueous slurry.

8. The process of claim 1 wherein heat of vaporization released upon the condensation of steam in step 1) at least partially heats the reaction mixture.

9. The process of claim 8 wherein the temperature of the steam stream is at or below the reaction temperature formed upon mixing the steam stream and the aqueous slurry in step 1).

10. The process of claim 1 wherein the reaction time in step 2) is 10 to 1000 seconds.

11. The process of claim 1 wherein step c) includes a step of depressurizing the reaction mixture such that at least a portion of the subcooled liquid water becomes converted to gas.

12. The process of claim 1 wherein the organic feedstock includes one or more of municipal sewage, agricultural sewage, plant tissue, animal tissue, microbial biomass and a sludge produced by microbial digestion of an agricultural product, an agricultural waste, or municipal or agricultural sewage.

13. The process of claim 1, wherein the aqueous slurry contains 0.1 to 10% by weight of organic feedstock particles.

14. The process of claim 1, wherein the hydrothermal conversion product includes a carbonized solid.

15. The process of claim 14 wherein the carbonized solid has an oxygen:

carbon atomic ratio of less than 0.2, a nitrogen;

carbon atomic ratio of less than 0.2 and a hydrogen;

carbon atomic ratio of <

1.2.

16. The process of claim 1, wherein the hydrothermal conversion product includes a liquefaction product.

17. The process of claim 16 wherein the liquefaction product has an oxygen:

carbon atomic ratio of less than 0.6, a nitrogen;

carbon atomic ratio of less than 0.5 and a hydrogen;

carbon atomic ratio of <

1.5.

18. The hydrothermal conversion process of claim 1 wherein step 1 is performed by:

1-a) pressurizing an aqueous slurry of the organic feedstock particles in liquid water to a pressure of at least 608 kPa at temperature of up to 100°

C.;

1-b) separately forming pressurized steam at a temperature of at least 160°

C.; and

1-c) mixing the aqueous slurry and pressurized steam under elevated pressure to form a reaction mixture, whereby upon the mixing the steam condenses and heats the reaction mixture to a temperature of at least 160°

C., wherein the elevated pressure is sufficient to maintain water including the condensed steam as a subcooled liquid.

19. A process for treating municipal or agricultural sewage, comprising the steps of

A. treating the sewage in a microbial digester to produce a microbial digestion product that includes biogas and a sludge, where the sludge contains solid organic matter dispersed in an aqueous phase,

B. separating biogas from the sludge;

and

C. converting the sludge to a hydrothermal conversion product according to the process of claim 1, in which the sludge forms all or a part of the particulate solid organic feedstock.

20. A hydrothermal conversion process wherein a particulate solid organic feedstock is reacted with water at a temperature of at least 160°

at a superatmospheric pressure sufficient to maintain the water as a subcooled liquid to produce one or more hydrothermal conversion products selected from a) a carbonized solid and b) at least one liquefaction product, wherein

1) an aqueous slurry of particles of the organic feedstock in liquid water is preheated in a heat exchanger to a temperature of up to 140°

under sufficient pressure to keep the water in the liquid aggregate state;

2) the preheated aqueous slurry is introduced into a reactor in which the slurry is heated to a temperature of at least 160°

C. under sufficient pressure to keep the water as a subcooled liquid and then maintained under such conditions of temperature and pressure for a period of time sufficient to produce a reaction product mixture containing water and the one or more hydrothermal conversion products;

3) withdrawing the reaction product mixture from the reactor;

4) passing at least a portion of the reaction product mixture through the heat exchanger to provide energy for heating the aqueous slurry in step

     1), whereby such portion of the reaction product mixture is cooled;

5) prior to or after step

     4), depressurizing the reaction product mixture such that at least a portion of the liquid water becomes converted to a gas and the reaction mixture separates into a gas phase and a liquid phase that may include at least one dispersed solid hydrothermal conversion product;

6) recovering one or more hydrothermal conversion products from the liquid phase.