Apparatus for and method of processing a slurry containing organic components

Abstract

The invention relates to an apparatus (1) for processing a slurry containing organic components, such as biomass, having a water contents of at least 50%, comprising a heat exchanger (7) to heat the slurry and a reactor (8) to convert at least a part of the organic components in the slurry, wherein at least one of the heat exchanger (7) and the reactor (8) comprises one or more pipes (7A; 8A). At least one transport screw (15) is accommodated in the pipe (7A; 8A) or at least one of the pipes (7A; 8A).

Claims

1. An apparatus for processing a slurry containing organic components, having a water content of at least 50 wt %, comprising: a high pressure zone and a high pressure pump to pressurize water in the slurry to supercritical conditions in the high pressure zone; wherein the high pressure zone includes a heat exchanger configured to heat the slurry and a reactor comprising one or more pipes and configured to receive the heated slurry and convert at least a part of the organic components in the slurry to a gaseous product, wherein at least one transport screw has an open center and is accommodated in the one or more pipes of the reactor, and wherein the open center of the at least one transport screw provides an unobstructed path for the slurry or at least the water in the slurry to flow through the respective pipe.

2. The apparatus according to claim 1, wherein the heat exchanger and the reactor each comprise one or more pipes and a heat exchanger transport screw is accommodated in at least one pipe of the heat exchanger.

3. The apparatus according to claim 2, wherein a transport screw is accommodated in all the pipes of the heat exchanger and of the reactor.

4. The apparatus according to claim 1, wherein the at least one transport screw in the reactor comprises a plurality of screws, and wherein some screws each have an open center.

5. The apparatus according to claim 1, wherein the at least one transport screw in the reactor comprises a helical element.

6. The apparatus according to claim 5, wherein the at least one transport screw in the reactor comprises a screw ribbon.

7. The apparatus according to claim 1, wherein the at least one transport screw in the reactor includes a catalyst.

8. The apparatus according to claim 1, comprising at least one motor configured to drive the at least one transport screw in the reactor.

9. The apparatus according to claim 8, comprising a high pressure zone, encompassing at least the reactor and the heat exchanger, wherein the at least one motor is located outside the high pressure zone.

10. The apparatus according to claim 9, wherein the high pressure zone is sealed and the at least one motor is magnetically coupled to the at least one transport screw in the reactor.

11. The apparatus according to claim 1, where the at least one transport screw in the reactor comprises two transport screws with opposite helicity.

12. The apparatus according to claim 1, wherein an outer diameter of the at least one transport screw in the reactor is in a range from 0% to 15% smaller than an inner diameter of a pipe in which the at least one transport screw is accommodated.

13. The apparatus according to claim 1, comprising a solids trap, the at least one transport screw in the reactor extending through or over the solids trap.

14. A method of processing a slurry containing organic components having a water content of at least 50 wt %, comprising: increasing a pressure and a temperature of the slurry to bring water in the slurry to a supercritical state in a high pressure zone using a high pressure pump, the high pressure zone encompassing a heat exchanger and a reactor having a pipe with a screw having an open center; converting at least a part of the organic components in the pressurized and heated slurry in the reactor to gaseous product; and transporting solids settling from the slurry through the pipe by the screw, wherein the open center of the screw provides an unobstructed path for the slurry or at least the water in the slurry to flow through the pipe.

15. The method according to claim 14, wherein increasing the pressure and temperature is carried out in a transport pipe and the slurry is transported through the transport pipe by a second screw accommodated in the transport pipe.

16. The apparatus of claim 1 wherein the at least one transport screw comprises a plurality of screws, each screw having an open center.

17. The apparatus of claim 1 wherein the at least one transport screw comprises a plurality of screws, each screw having a helical element.

18. The apparatus of claim 1 wherein the at least one transport screw comprises a plurality of screws, each screw comprising a screw ribbon.

19. The apparatus of claim 1 wherein the at least one transport screw comprises a plurality of screws, each screw including a catalyst.

20. The apparatus of claim 1 wherein the at least one transport screw comprises a plurality of screws, and wherein an outer diameter of each screw is in a range from 0% to 15% smaller than an inner diameter of a pipe in which each screw is accommodated.

21. An apparatus for processing a slurry containing organic components having a water content of at least 50 wt %, comprising: a high pressure zone and a high pressure pump to pressurize water in the slurry to supercritical conditions in the high pressure zone; wherein the high pressure zone includes a heat exchanger to bring the water in the slurry to a supercritical state and a reactor configured to receive the slurry in the supercritical state and to convert at least a part of the organic components in the slurry to gaseous product, wherein the reactor comprises one or more pipes; a solids trap; and at least one transport screw being accommodated in at least one pipe of the reactor, wherein the at least one transport screw has an open center for the flow of water that extends through or over the solids trap.

Description

(1) The invention will now be explained in more detail with reference to the figures, which schematically show an embodiment according to the present invention.

(2) FIG. 1 is a flow diagram of an embodiment of an apparatus/method for hydrothermal conversion, e.g. supercritical water gasification, in accordance with the present invention.

(3) FIG. 2 is a schematic cross-section of an apparatus comprising a transport screw according to the present invention.

(4) FIG. 1 shows a system 1 for processing a slurry containing organic components, such as biomass, having a water contents of at least 50%, comprising a solid-liquid separator 2, such as a screw press, filter press, centrifuge, or dryer, to dewater the feed slurry and a tank 3 for holding the dewatered slurry. The tank is connected to a pump 4 which in turn is connected to or integrated with a heat exchanger 5 for adding residual heat to the slurry. Downstream from the heat exchanger 5 are a high-pressure pump 6 and a heat exchanger 7 to pressurize and heat the water in the slurry to supercritical or near-supercritical conditions.

(5) In the present example, the heat exchanger comprises one or more counter-current pipe-in-pipe heat exchanger sections 7A, e.g. two, four or more pipe-in-pipe heat exchanger sections, extending horizontally and parallel to one another and connected in series. Downstream from the pump 6 and heat exchanger 7 is a further heat exchanger, which serves as a reactor 8. In the present example, the reactor comprises one or more pipes 8A, e.g. two pipes 8A, which are externally heated.

(6) The downstream end of the reactor and optionally also of the heat exchanger 7 is connected to a solids trap 9 to remove solids, such as inorganics and/or precipitated minerals and salts, from the system.

(7) As indicated by a solid line 10 in FIG. 1, the downstream end of the reactor 8 is connected to the outer pipe of the heat exchanger 7, to provide counter-current heat exchange between the (relatively hot) converted slurry and the (relatively cold) slurry before conversion. The outer pipes of the heat exchanger 7 are connected to gas-liquid separator 12, to separate the gaseous products from the liquid.

(8) As shown in more detail in FIG. 2, a transport screw, in this example a screw ribbon 15, is accommodated in all the pipes 7A, 8A of the heat exchanger 7 and of the reactor 8.

(9) The system further comprises a high pressure zone, encompassing at least the reactor 8 and the heat exchanger 7 and a motor 16 located outside the high pressure zone. The motor is connected, via a transmission 17, which can be located in the high or low pressure zone, to all transport screw ribbons 15 to drive them all in the same direction of rotation. To ensure transport of the solids in the flow direction of the slurry (indicated by arrows), in this example the helicity of the screws changes from one screw to the next.

(10) During operation, in an example, wet biomass (manure) having a water content of 90% is dewatered by means of a screw press 2 to a water content of 70% (totals solids 30%) and the thickened and viscous slurry is fed to the tank 3. From there, the slurry is pumped (at 1000 liters/hour) to the heat exchanger 5 and mixed with water to a water content of 75% and a volume of 2000 nL/h. The slurry is then pressurized and heated (240-250 bar, and 370-390° C.) and fed to the reactor, where the slurry is further heated (to 550-600° C.) to convert at least a part of the organic components in the slurry to gaseous product, e.g., hydrogen and methane. During heating and conversion and both in the subcritical state and in the supercritical state, solids settling from the slurry are continuously transported through the pipes 7A, 8A by means of the screws 15, which rotate at e.g. 5 to 10 rpm, and into the solids trap 9. The water is fed to the heat exchanger 7 to recover high temperature heat, i.e. to heat the colder upstream slurry. After leaving the heat exchanger (at 2000 nL/h, 240-250 bar, and 250-300° C.), the liquid is fed to the gas/liquid separator to allow the gaseous product to escape and to enable collection. The solids trap is emptied at regular intervals.

(11) The method and system according to the present invention enable continuous processing of feedstocks with a relatively high contents of organic components and/or solids, while reducing the risk of clogging and/or lengthening maintenance intervals for cleaning the heat exchanger and/or reactor pipes and/or improving heat exchange between the viscous, high solids, relatively cold slurry in the inner pipes with the relatively hot fluid in the outer pipes.

(12) The invention is not restricted to the above-described embodiments, which can be varied in a number of ways within the scope of the claims. For instance, the screw may comprise a pipe with a series of openings in its wall and with a helical element, e.g. a wire, wound around and attached, e.g. welded, to it. The screw can be made of metal or, e.g., of a synthetic material, such as an engineering polymer. In another example, the screw has a solid centre.