Fines capture and recycle system and uses thereof

1. A cyclone system wherein the cyclone system comprises:

a first stage cyclone having a first inlet and a first outlet, wherein the first inlet is connected to a fluidized-bed gasifier having two or more cyclone arranged in series, and receives a first gas-solid mixture from the gasifier and receives a first gas-solid mixture from the gasifier; a

first dipleg connected to the first stage cyclone for collecting a first solid particle fraction separated from the first gas-solid mixture;

a first loopseal connected to the first dipleg for receiving the first solid particle fraction;

a second stage cyclone having a second inlet and a second outlet, wherein the second inlet is in fluid communication with the first outlet and receives a second gas-solid mixture from the first stage cyclone;

a second dipleg connected to the second stage cyclone for collecting a second solid particle fraction separated from the second gas-solid mixture;

a combined dipleg connected to both the first loopseal and the second dipleg; and

a combined loopseal connected to the combined dipleg for receiving a mixture of the first and second solid particle fractions, and to the gasifier for feeding the mixture of the first and second solid particle fractions back to the gasifier.

2. The cyclone system of claim 1 , wherein the gasifier is a fluidized bed gasifier.

3. The cyclone system of claim 1 , wherein the first inlet is a half-volute inlet.

4. The cyclone system of claim 1 , wherein the second inlet is a tangential inlet.

5. The cyclone system of claim 1 , wherein the first loopseal comprises a first vertical downcomer connected to the first dipleg for receiving the first solid particle fraction, a first downwardly inclined segment downstream of the first vertical. downcomer, a first riser downstream of the first downwardly inclined segment, and a second downwardly inclined segment downstream of the first riser.

6. The cyclone system of claim 5 , wherein the combined dipleg is connected at a branch point of the combined dipleg to the second dipleg and the second downwardly inclined segment of the first loopseal.

7. The cyclone system of claim 1 , wherein the combined loopseal comprises a second vertical downcomer for receiving a mixture of the first and second solid particle fractions, a third downwardly inclined segment downstream of the second vertical downcomer, a second riser downstream of the third downwardly inclined segment, and a fourth downwardly inclined segment downstream of the second riser and connected back to the gasifier.

8. A method for capturing and recycling fines from a fluidized-bed gasifier, comprising: delivering a first gas-solid mixture from a gasifier to a first inlet of a first stage cyclone; separating the first gas-solid mixture into a second gas-solid mixture and a first solid particle fraction in the first stage cyclone; feeding the second gas-solid mixture from a first outlet of the first stage cyclone to a second inlet of a second stage cyclone and collecting the first solid particle fraction sequentially through a first dipleg connected to the first stage cyclone and a first loopseal connected to the first dipleg; separating from the second gas-solid mixture a second solid particle fraction in the second stage cyclone; collecting the second solid particle fraction through a second dipleg connected to the second stage cyclone; collecting a mixture of the first solid particle fraction from the first loopseal and the second solid particle fraction from the second dipleg sequentially through a combined dipleg connected to both the first loopseal and the second dipleg and a combined loopseal connected to both the combined dipleg and the gasifier; and feeding the mixture of the first and second solid particle fractions from the combined loopseal back to the gasifier.

9. A fluidized bed gasifier system, comprising: a fluidized bed gasifier, and a cyclone system having two or more cyclones arranged in series, wherein the cyclone system comprises: a first stage cyclone having a first inlet and a first outlet, wherein the first inlet is in fluid communication with the gasifier and receives a first gas-solid mixture from the gasifier; a first dipleg connected to the first stage cyclone for collecting a first solid particle fraction separated from the first gas-solid mixture; a first loopseal connected to the first dipleg for receiving the first solid particle fraction; a second stage cyclone having a second inlet and a second outlet, wherein the second inlet is in fluid communication with the first outlet and receives a second gas-solid mixture from the first stage cyclone; a second dipleg connected to the second stage cyclone for collecting a second solid particle fraction separated from the second gas-solid mixture; a combined dipleg connected to both the first loopseal and the second dipleg; and a combined loopseal connected to the combined dipleg for receiving a mixture of the first and second solid particle fractions, and to the gasifier for feeding the mixture of the first and secon.d solid particle fractions back to the gasifier.

10. The gasifier system of claim 9 , wherein the gasifier is a fluidized bed gasifier.

11. The gasifier system of claim 9 , wherein the first inlet is a half-volute inlet.

12. The gasifier system of claim 9 , wherein the second inlet is a tangential inlet.

13. The gasifier system of claim 9 , wherein the first loopseal comprises a first vertical downcomer connected to the first dipleg for receiving the first solid particle fraction, a first downwardly inclined segment downstream of the first vertical downcomer, a first riser downstream of the first downwardly inclined segment, and a second downwardly inclined segment downstream of the first riser.

14. The gasifier system of claim 13 , wherein the combined dipleg is connected at a branch point of the combined dipleg to the second dipleg and the second downwardly inclined segment of the first loopseal.

15. The gasifier system of claim 9 , wherein the combined loopseal comprises a second vertical downcomer for receiving a mixture of the first and second solid particle fractions, a third downwardly inclined segment downstream of the second vertical downcomer, a second riser downstream of the third downwardly inclined segment, and a fourth downwardly inclined segment downstream of the second riser and connected back to the gasifier.

16. A method for capturing and recycling fines, comprising: generating a first gas-solid mixture in a fluidized-bed gasifier, delivering the first gas-solid mixture from the gasifier to a first inlet of a first stage cyclone; separating the first gas-solid mixture into a second gas-solid mixture and a first solid particle fraction in the first stage cyclone; feeding the second gas-solid mixture from a first outlet of the first stage cyclone to a second inlet of a second stage cyclone and collecting the first solid particle fraction sequentially through a first dipleg connected to the first stage cyclone and a first loopseal connected to the first dipleg; separating from the second gas-solid mixture a second solid particle fraction in the second stage cyclone; collecting the second solid particle fraction through a second dipleg connected to the second stage cyclone; collecting a mixture of the first solid particle fraction from the first loopseal and the second solid particle fraction from the second dipleg sequentially through a combined dipleg connected to both the first loopseal and the second dipleg and a combined loopseal connected to both the combined dipleg and the gasifier; and feeding the mixture of the first and second solid particle fractions from the combined loopseal back to the gasifier.