METHOD FOR OPERATING A FLUIDIZED BED APPARATUS AND FLUIDIZED BED APPARATUS

Abstract

The present invention relates to a method for operating a fluidized bed apparatus and to a fluidized bed apparatus, the method comprising the following steps: providing particulate metal to a reaction chamber of a fluidized bed reactor, providing an oxidizing agent to a fluidizing bottom of the fluidized bed reactor such that particulate matter comprising the particulate metal is fluidized, wherein the particulate metal reacts with the oxidizing agent to particulate metal oxide, withdrawing particulate metal oxide from the reaction chamber, storing the withdrawn particulate metal oxide, providing particulate metal oxide to the reaction chamber of the fluidized bed reactor, providing a reducing agent containing gas to the fluidizing bottom of the fluidized bed reactor such that particulate matter comprising the particulate metal oxide is fluidized, wherein the particulate metal oxide reacts with the reducing agent to particulate metal, withdrawing the particulate metal from the reaction chamber, storing the withdrawn particulate metal.

Claims

1. A method for operating a fluidized bed apparatus, comprising the following steps: 1a) Providing particulate metal to a reaction chamber of a fluidized bed reactor, 1b) Providing an oxidizing agent or water steam to a fluidizing bottom of the fluidized bed reactor such that particulate matter comprising the particulate metal is fluidized, wherein the particulate metal reacts with the oxidizing agent to particulate metal oxide or with the water steam to particulate metal oxide and gaseous hydrogen, 1c) Withdrawing particulate metal oxide from the fluidized bed reactor, 1d) Storing the withdrawn particulate metal oxide, 2a) Providing particulate metal oxide to the reaction chamber of the fluidized bed reactor, 2b) Providing a reducing agent containing gas to the fluidizing bottom of the fluidized bed reactor such that particulate matter comprising the particulate metal oxide is fluidized, wherein the particulate metal oxide reacts with the reducing agent to particulate metal, 2c) Withdrawing the particulate metal from the fluidized bed reactor, 2d) Storing the withdrawn particulate metal.

2. The method according to claim 1, wherein the reducing agent gas comprises hydrogen gas as reducing agent.

3. The method according to claim 1, comprising the following steps: Operating an electrolysis unit to produce oxygen and hydrogen gas, Providing the produced hydrogen gas as the reducing agent to the reaction chamber of the fluidized bed reactor in step 2b).

4. The method according to claim 3, comprising the following step: Storing the produced oxygen and providing the stored oxygen to the reaction chamber of the fluidized bed reactor in step 1b).

5. The method according to claim 1, wherein reaction gases after separation from the particulate matter is withdrawn and provided to the fluidizing bottom.

6. The method according to claim 1, wherein in step 1a) or 1b) the temperature is temporarily raised at least locally to cause an exothermic combustion reaction of the particulate metal with the oxygen.

7. A fluidized bed apparatus, comprising a fluidized bed reactor having a reaction chamber for particulate matter, a fluidizing bottom with at least one gas inlet for an operating gas to fluidize the particulate matter, a particulate metal storage connected to the fluidized bed reactor for storing particulate metal withdrawn from the fluidized bed reactor, a particulate metal oxide storage connected to the fluidized bed reactor for storing particulate metal oxide withdrawn from the fluidized bed reactor, a reducing agent supply connectable to the fluidizing bottom of the fluidized bed reactor, and an oxidizing agent supply or water steam supply connectable to the fluidizing bottom of the fluidized bed reactor.

8. The fluidized bed apparatus according to claim 7, having a recirculation line for reaction gases, the recirculation line being connectable to the fluidizing bottom.

9. The fluidized bed apparatus according to claim 7, wherein the reducing agent supply and the oxidizing agent supply and preferably the recirculation line are connectable to the same or to different nozzles of the fluidizing bottom.

10. The fluidized bed apparatus according to claim 7, wherein the particulate metal oxide storage vessel is connected to a returning line connecting a particulate matter separator and the reaction chamber.

11. The fluidized bed apparatus according to claim 7, wherein the particulate metal storage is connected to the reaction chamber above the fluidizing bottom.

12. The fluidized bed apparatus according to claim 7, wherein the fluidized bed apparatus comprises an ignition device embodied to at least locally raise the temperature to cause an exothermic combustion reaction of the particulate metal with oxidizing agent.

13. The fluidized bed apparatus according to claim 7, wherein a particulate matter separator is associated with a reaction chamber outlet.

14. The fluidized bed apparatus according to claim 7, comprising an electrolysis unit for producing hydrogen gas and oxygen, the electrolysis unit having a hydrogen outlet for the produced hydrogen gas and an oxygen outlet for the produced oxygen, wherein the hydrogen outlet is connectable to the gas inlet of the fluidized bed reactor and wherein preferably the oxygen outlet is connected to an oxygen storage vessel, which oxygen storage vessel is connectable to the gas inlet of the fluidized bed reactor.

15. The fluidized bed apparatus according to claim 7, wherein the particulate metal is of the following group: Iron (Fe), Zinc (Zn), Alkali metal, in particular Magnesium (Mg).

Description

[0049] The invention and the technical background will now be explained with regard to the FIGURE, which shows an exemplary embodiment of the invention.

[0050] The apparatus depicted in the FIGURE comprises a fluidized bed reactor 1 which has a reaction chamber 2 and a fluidizing bottom 8 with a plurality of nozzles 17. The nozzles 17 embody a gas inlet 4 for providing an operation gas to the reaction chamber 2. The reaction chamber 2 can be provided with particulate matter, which is fluidized by the gas provided through nozzles 17.

[0051] The reaction chamber 2 has at its upper end a reaction chamber outlet 6, through which a mixture of particulate matter and reaction gases enters a particulate matter separator 13, in which the reaction gases are separated from the particulate matter. The reaction gases may leave the particulate matter separator 3 through the top and be led to further processing, wherein a recirculation line 16 is connected to the respective outlet line. The particulate matter may leave the particulate matter separator 13 through returning line 18, which leads to the bottom of the reaction chamber 2.

[0052] A particulate metal oxide storage vessel 10 is connected to the returning line 18, wherein particulate matter may be withdrawn from the returning line 18 to the particulate metal oxide storage vessel 10 or wherein particulate matter from the particulate metal oxide storage vessel 10 may be fed to the returning line 18 and from there to the reaction chamber 2.

[0053] Furthermore, a particulate metal storage vessel 9 is provided, which is connected to a reaction chamber inlet 7 at the bottom of the reaction chamber 2, wherein particulate matter from the reaction chamber 2 can be withdrawn to the particulate metal storage vessel 9 or wherein particulate matter from the particulate metal storage vessel 9 can be fed into the reaction chamber 2. Alternatively, the metal storage vessel 9 may be connected to returning line 18. Furthermore, an inert gas (such as N.sub.2) may be provided to the metal storage vessel 9.

[0054] A first group of nozzles 17 of the fluidizing bottom 8 is connected to an oxidizing agent supply 12. A further group of nozzles 17 is connected to a reducing agent supply 11 and an even further group of nozzles 17 is connected to a water steam source 20.

[0055] Additionally, an electrolysis unit 13 is embodied, which hydrogen outlet 14 is connected to the reducing agent supply 11 and which oxygen outlet 15 is connected to an oxygen storage vessel 19, which in turn is connected to the oxidizing agent supply 12. The recirculation line 16 is connected to the third group of nozzles 17 but may also be connected to any other group of nozzles.

[0056] When there is a surplus of electrical energy from renewable energy sources, the electrolysis unit 13 is operated to produce oxygen and gaseous hydrogen, wherein the oxygen is stored in the oxygen storage vessel 19. The hydrogen is supplied via the reducing agent supply 11 to the respective group of nozzles 17. At the same time particulate metal oxide from the particulate metal oxide storage vessel 10 is provided to the reaction chamber 2. The particulate matter comprising particulate metal oxide within the reaction chamber 2 is fluidized by the hydrogen, wherein a reduction reaction of the hydrogen with the particulate metal oxide takes place, so that particulate metal is produced. The particulate metal can be withdrawn via the reaction chamber inlet 7 to the particulate metal storage vessel 9. Accordingly, electrical energy is stored in solid form within the particulate metal.

[0057] If the stored energy shall be recovered, the particulate metal is fed from the particulate metal storage vessel 9 into the reaction chamber 2 and an oxidizing agent is supplied through the oxidizing agent supply 12 and its respective nozzles 17, wherein oxygen stored in oxygen storage vessel 19 may be added. The particulate matter comprising the particulate metal within the reaction chamber 2 is fluidized by the provided oxidizing agent, wherein the temperature of the fluidized bed is locally raised by an ignition device 5 in order to start an oxidation reaction. The particulate metal oxide produced in this oxidation process may be withdrawn from returning line 18 towards the particulate metal oxide storage vessel 10.

[0058] In a further process application water steam may be provided through the respective nozzles 17 into the reaction chamber 2, wherein the particulate metal provided from the particulate metal storage vessel 9 may react in the fluidized state to particulate metal oxide and hydrogen, which hydrogen can be withdrawn for further processing.

[0059] The present invention suggests that the same fluidized bed reactor 1 is once operated as reduction reactor, for example if there is a surplus of electrical energy, and is later run as oxidation reactor, when energy or hydrogen is needed.