Microwave reactor system with gas-solids separation

Patent metadata

Field	Value
Publication number	US-10308512-B2
Application number	US-201715725928-A
Country	US
Kind code	B2
Filing date	Oct 5, 2017
Priority date	Oct 6, 2016
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

Microwave chemical processing system having a microwave plasma reactor, and a multi-stage gas-solid separation system are disclosed. The microwave energy source has a waveguide, a reaction zone, and an inlet configured to receive the input material, and the input material is converted into separated components. The separated components include hydrogen gas and carbon particles. The multi-stage gas-solid separation system has a first cyclone separator to filter the carbon particles from the separated components, and a back-pulse filter system coupled to the output of the first cycle separator to filter the carbon particles from the output from the first cyclone separator.

First claim

What is claimed is:

1. A materials processing system, comprising:
an input material comprising a hydrocarbon gas;
a microwave plasma reactor comprising:
a microwave energy source;
a field-enhancing waveguide coupled to the microwave energy source, the field-enhancing waveguide having a first cross-sectional area and a second cross-sectional area, wherein the field-enhancing waveguide includes a field-enhancing zone between the first cross-sectional area and the second cross-sectional area, a plasma zone, and a reaction zone, and wherein the second cross-sectional area:
is smaller than the first cross-sectional area, and the field-enhancing zone has a decreasing cross-sectional area from the first cross-sectional area to the second cross-sectional area;
is farther away from the microwave energy source than the first cross-sectional area; and
extends along a reaction length that forms the reaction zone of the field-enhancing waveguide, wherein the microwave energy propagates in a direction along the reaction length; and

an inlet configured to receive the input material, wherein the input material flows through the inlet into the reaction zone;
wherein the plasma separates the input material into separated components, the separated components comprising hydrogen gas and carbon particles;

a multi-stage gas-solid separator system coupled to the microwave plasma reactor, the multi-stage gas-solid separator system comprising:
a first cyclone separator having an output, wherein the first cyclone separator filters the carbon particles from the separated components; and
a back-pulse filter system coupled to the output of the first cyclone separator, wherein the back-pulse filter system filters the carbon particles from the output from the first cyclone separator.

2. The system of claim 1 , wherein the input material comprises natural gas, and the flow rate of the input material into the reactor is greater than 5 slm.

3. The system of claim 1 , wherein the input material comprises bio-gas, and the flow rate of the input material into the reactor is greater than 5 slm.

4. The system of claim 1 , wherein the first cyclone separator and back-pulse filter system are heated to a temperature greater than 300° C.

5. The system of claim 1 , wherein a majority of the carbon particles filtered by the first cyclone separator are greater than 1 micron in size.

6. The system of claim 1 , wherein a majority of the carbon particles filtered by the back-pulse filter system are greater than 100 nm in size.

7. The system of claim 1 , wherein greater than 80% of the carbon particles are filtered by the first cyclone separator.

8. The system of claim 1 , wherein greater than 99% of the carbon particles are filtered after the separated components are filtered by the first cyclone separator and the back-pulse filter system.

9. The system of claim 1 , wherein the density of the carbon particles in the separated components produced by the microwave plasma reactor is less than 0.2 g/cm 3 .

10. The system of claim 1 , wherein the carbon particles comprise graphene and one or more other carbon allotropes in addition to graphene, wherein:
the graphene comprises up to 15 layers;
a ratio of carbon to other elements, except hydrogen, in the carbon particles is greater than 99%; and
a ratio of the graphene to the other carbon allotropes is greater than 5%.

11. The system of claim 1 , wherein the back-pulse filter system comprises:
a plurality of back-pulse filters, each back-pulse filter having i) a filtering state in which the back-pulse filter is filtering the separated components, and ii) a cleaning state in which the back-pulse filter is being cleared using a flow of gas through the back-pulse filter; and
a valve upstream of the plurality of back-pulse filters to switch each back-pulse filter between the filtering state and the cleaning state;
wherein the plurality of back-pulse filters is arranged in parallel such that a first back-pulse filter of the plurality of back-pulse filters can be in the cleaning state while other back-pulse filters of the plurality of back-pulse filters are in the filtering state.

12. The system of claim 1 , wherein the multi-stage gas-solid separator system further comprises a second cyclone separator between the first cyclone separator and the back-pulse filter system, wherein:
the first cyclone separator filters out a first fraction of the carbon particles in the separated components,
the second cyclone separator filters out a second fraction of carbon particles in the separated components, and
the back-pulse filter system filters out a third fraction of carbon particles in the separated components.

13. The system of claim 12 , wherein the median particle size of the particles in the first fraction is larger than the median particle size of the particles in the second fraction, and the median particle size of the particles in the second fraction is larger than the median particle size of the particles in the third fraction.

14. A process for producing carbon particles, comprising:
supplying pulsed microwave radiation through a waveguide having a length, the microwave radiation propagating in a direction along the waveguide;
providing a supply gas into the waveguide at a first location along the length of the waveguide, a majority of the supply gas flowing in the direction of the microwave radiation propagation;
generating a plasma in the supply gas in at least a portion of the length of the waveguide;
providing an input material into the waveguide at a second location downstream from the first location, a majority of the process gas flowing in the direction of the microwave propagation, wherein the input material comprises a hydrocarbon gas;
controlling an average energy of the plasma to convert the input material into separated components, wherein the separated components contain hydrogen gas and carbon particles; and
filtering the carbon particles from the hydrogen gas using a multi-stage gas-solid separator system, wherein the multi-stage gas-solid separator system comprises:
a first cyclone separator having an output; and
a back-pulse filter system, wherein:
the first cyclone separator filters the carbon particles from the separated components; and
the back-pulse filter system filters the carbon particles from the output from the first cyclone separator.

15. The process of claim 14 , wherein a temperature in the multi-stage gas-solid separator system is adjustable, and the temperature is adjusted to change the concentration of adsorbed hydrocarbons in the collected carbon particles.

16. The process of claim 14 , wherein the input material comprises natural gas, and the flow rate of the input material into the reactor is greater than 5 slm.

17. The process of claim 14 , wherein the input material comprises bio-gas, and the flow rate of the input material into the reactor is greater than 5 slm.

18. The process of claim 14 , wherein the density of the carbon particles is less than 0.2 g/cm 3 .

19. The process of claim 14 , wherein the carbon particles comprise graphene and one or more other carbon allotropes in addition to graphene, wherein:
the graphene comprises up to 15 layers;
a ratio of carbon to other elements, except hydrogen, in the carbon particles is greater than 99%; and
a ratio of the graphene to the other carbon allotropes is greater than 5%.

20. The process of claim 14 , wherein:
the back-pulse filter system comprises:
a plurality of back-pulse filters, each

Assignees

• Lyten Inc

Inventors

• Tanner David
• Cook Daniel
• Anzelmo Bryce H
• Kalluri Ranjeeth
• Stowell Michael W

Classifications

• B01J2219/00022

  Plants mounted on pallets or skids · CPC title

• H01J37/32229

  Waveguides · CPC title

• B01J2219/0894

  Processes carried out in the presence of a plasma · CPC title

• B01J2219/1248

  Features relating to the microwave cavity · CPC title

• B01D46/00

  Filters or filtering processes specially modified for separating dispersed particles from gases or vapours (filtering elements B01D24/00-B01D35/00; filtering material B01D39/00; their regeneration outside the filters B01D41/00) · CPC title