Thermal energy storage system with steam generator having feedback control
An energy storage system converts variable renewable electricity (VRE) to continuous heat at over 1000° C. Intermittent electrical energy heats a solid medium. Heat from the solid medium is delivered continuously on demand. An array of bricks incorporating internal radiation cavities is directly heated by thermal radiation. The cavities facilitate rapid, uniform heating via reradiation. Heat delivery via flowing gas establishes a thermocline which maintains high outlet temperature throughout discharge. Gas flows through structured pathways within the array, delivering heat which may be used for processes including calcination, hydrogen electrolysis, steam generation, and thermal power generation and cogeneration. Groups of thermal storage arrays may be controlled and operated at high temperatures without thermal runaway via deep-discharge sequencing. Forecast-based control enables continuous, year-round heat supply using current and advance information of weather and VRE availability. High-voltage DC power conversion and distribution circuitry improves the efficiency of VRE power transfer into the system.
1. A thermal energy storage system, comprising:
a thermal storage assemblage including a plurality of thermal storage blocks configured to store thermal energy obtained using an input energy supply from an energy source, at least some of the thermal storage blocks including multiple radiation cavities and multiple fluid flow slots;
a fluid movement device configured to move a fluid through the thermal storage blocks and discharge the stored thermal energy from the thermal storage blocks into the fluid;
a once-through steam generator configured to receive the fluid from the thermal storage blocks and to exchange heat from the fluid with water from a water source to produce steam; and
a control system configured to:
measure a value indicating steam quality of the steam; and
based on the measured value, control a flow rate of the fluid received by the steam generator.
2. The thermal energy storage system of claim 1 , further comprising one or more instruments configured to detect the value indicating steam quality of the steam, and wherein the control system is configured to measure the value by interfacing with the instruments.
3. The thermal energy storage system of claim 2 , wherein the one or more instruments are configured to detect an inlet flow velocity of water at an inlet of the steam generator and an outlet flow velocity of steam at an outlet of the steam generator.
4. The thermal energy storage system of claim 2 , further comprising a vapor-liquid separator configured to separate the steam into a liquid component and a vapor component,
wherein the one or more instruments are configured to detect a liquid component heat value and a vapor component heat value.
5. The thermal energy storage system of claim 1 , wherein the control system is configured to measure an inlet flow velocity of water at an inlet of the steam generator and an outlet flow velocity of steam at an outlet of the steam generator.
6. The thermal energy storage system of claim 1 , further comprising a vapor-liquid separator configured to separate the steam into a liquid component and a vapor component,
wherein the control system is configured to measure a liquid component heat value and a vapor component heat value.
7. The thermal energy storage system of claim 1 , further comprising an adjustable fluid restricting device,
wherein the control system is configured to send control signals to the adjustable fluid restricting device based on the measured value.
8. The thermal energy storage system of claim 7 , wherein the adjustable fluid restricting device comprises a louver or a valve.
9. The thermal energy storage system of claim 1 , wherein, if the measured value of steam quality indicates a decrease in steam quality, the control system is configured to increase a flow rate of the fluid.
10. The thermal energy storage system of claim 1 , wherein the control system is configured to:
prior to measuring the value indicating steam quality, receive a target steam parameter;
obtain an inlet water temperature at an inlet of the steam generator; and
based on the target steam parameter and the inlet temperature, determine an initial flow rate for the fluid received by the steam generator.
11. The thermal energy storage system of claim 10 , wherein the target steam parameter comprises a target steam quality or a target steam delivery rate.
12. The thermal energy storage system of claim 10 , wherein the control system is configured to obtain the inlet water temperature by measuring the inlet water temperature.
13. The thermal energy storage system of claim 1 , wherein the energy source is a source of intermittent availability.
14. The thermal energy storage system of claim 1 , wherein the fluid is heated by one or more resistive heating elements.
15. The thermal energy storage system of claim 14 , wherein the fluid comprises a gas.
16. The thermal energy storage system of claim 1 , wherein the fluid movement device comprises one or more blowers.
17. The thermal energy storage system of claim 1 , wherein at least some of the radiation cavities and some of the fluid flow slots are configured to define fluid pathways through the thermal storage blocks.
18. The thermal energy storage system of claim 17 , further comprising:
a plurality of heater elements positioned within the thermal storage assemblage and adjacent to at least said some of the radiation cavities,
wherein each of the plurality of heater elements is configured to heat at least one of the thermal storage blocks via energy radiated into multiple ones of the radiation cavities and onto surfaces that bound respective radiation cavities.
19. A method of storing and delivering thermal energy, the method comprising:
receiving input energy from an energy source;
storing thermal energy obtained using the input energy in a thermal storage assemblage that includes a plurality of thermal storage blocks, at least some of the thermal storage blocks including multiple radiation cavities and multiple fluid flow slots;
moving a fluid through the thermal storage blocks to heat the fluid;
delivering the heated fluid to a once-through steam generator configured to generate steam by exchanging heat from the fluid with water from a water source;
obtaining steam quality value of the steam; and
based on the steam quality value, providing a feedback signal for adjusting a rate of delivering the heated fluid to the steam generator.
20. The method of claim 19 , wherein obtaining the steam quality value comprises:
separating the steam into liquid phase and vapor phase components; and
independently monitoring heat of the liquid phase and vapor phase components.
21. The method of claim 19 , wherein obtaining the steam quality value comprises:
measuring an outlet flow velocity of the steam at an outlet of the steam generator; and
measuring an inlet flow velocity of the water at an inlet of the steam generator.
22. The method of claim 19 , wherein providing the feedback signal comprises providing the signal to a controllable element configured to adjust a flow rate of the fluid through the thermal storage blocks.
23. The method of claim 22 , wherein the controllable element comprises a louver or a valve.
24. The method of claim 19 , further comprising, prior to obtaining the steam quality value of the steam:
receiving a target parameter for the steam;
obtaining an inlet water temperature at an inlet of the steam generator; and
based on the target steam parameter and the inlet temperature, determining an initial rate for delivering the heated fluid to the steam generator.
25. The method of claim 24 , wherein receiving the target parameter comprises receiving a target steam quality or a target steam delivery rate.
26. The method of claim 24 , wherein obtaining the inlet water temperature comprises measuring the inlet water temperature.
27. The method of claim 19 , wherein the energy source is a source of intermittent availability.
28. The method of claim 19 , wherein the energy source comprises a solar energy source or a wind-powered energy source.
29. The method of claim 19 , wherein the fluid is heated by one or more resistive heating elements.
30. The method of claim 29 , wherein the fluid comprises a gas.