Ceramic particles for use in a solar power tower
Ceramic particles for use in a solar power tower and methods for making and using the ceramic particles are disclosed. The ceramic particle can include a sintered ceramic material formed from a mixture of a ceramic raw material and a darkening component comprising MnO as Mn 2+ . The ceramic particle can have a size from about 8 mesh to about 170 mesh and a density of less than 4 g/cc.
1. A method of generating power, the method comprising
disposing a solar receiver at or proximate to the top of a solar power tower;
receiving a solar radiation by one or more heliostats;
heating ceramic particles disposed inside the solar receiver using the solar radiation, the ceramic particles comprising:
a ceramic material formed from a mixture comprising a raw material and MnO, wherein the raw material comprises kaolin or bauxite or a mixture thereof, and wherein the ceramic material further comprises:
about 0.01 wt % to about 10 wt % MnO, and
about 0.01 wt % to about 10 wt % Mn 2 O 3 ;
oxidizing a portion of the MnO to Mn 2 O 3 by exposing the MnO to a temperature of about 100° C. to about 1,000° C. for a period of about 50 hours to about 5,000 hours; and
transferring heat from the heated ceramic particles to a heat exchange medium using a heat exchanger.
2. The method of claim 1 , wherein the heliostats are configured to track a solar source to reflect light onto the solar receiver.
3. The method of claim 2 , wherein the solar source is the sun.
4. The method of claim 1 , further comprising darkening the ceramic particles to a Munsell Value of less than 7.
5. The method of claim 4 , further comprising darkening the ceramic particles to a Munsell Value of less than 4.
6. The method of claim 1 , wherein the ceramic material further comprises about 0.1 wt % to about 20 wt % FeO.
7. The method of claim 6 , wherein the ceramic material further comprises about 0.1 wt % to about 20 wt % Fe 2 O 3 .
8. The method of claim 7 , further comprising shifting a portion of the FeO to Fe 2 O 3 .
9. The method of claim 1 , wherein the heat exchanger comprises a direct contact heat exchanger.
10. The method of claim 1 , further comprising collecting the cooled ceramic particles in one or more low temperature solids storage vessels.
11. The method of claim 10 , further comprising recycling the cooled ceramic particles to the solar receiver.
12. The method of claim 1 , wherein the temperature is about 200° C. to about 800° C.
13. The method of claim 1 , wherein the temperature is about 300° C. to about 700° C.
14. The method of claim 1 , wherein the temperature is about 400° C. to about 600° C.
15. The method of claim 1 , wherein the period is about 250 hours to about 2,500 hours.
16. The method of claim 1 , further comprising darkening the ceramic particles by a Munsell Value of about 0.1 to about 2.5.
17. The method of claim 16 , further comprising darkening the ceramic particles by a Munsell Value of about 0.3 to about 2.
18. The method of claim 1 , further comprising darkening the ceramic particles by a Munsell Value of about 0.5 to about 1.5.
19. The method of claim 1 , further comprising darkening the ceramic particles by a Munsell Value of about 0.7 to about 1.2.
20. The method of claim 1 , further comprising darkening the ceramic particles by a Munsell Value of about 0.7 to about 1.