Solar-biomass complementary thermal energy supply system

Abstract

A thermal energy supply system, including: a solar concentrating device, a solar storage tank including a first heat exchanger and a second heat exchanger, a biomass power station including a biomass boiler, a central refrigeration and ice maker, and a central hot water supply tank. The solar concentrating device is connected to the solar storage tank. The inlet of the first heat exchanger of the solar storage tank is connected to the outlet of a feedwater pump of the biomass boiler. The outlet of the first heat exchanger is connected to the inlet of a water feeding system of the biomass boiler. The inlet pipe of the second heat exchanger of the solar storage tank is connected to the outlet pipe of a water purification plant. The outlet of the second heat exchanger is connected to a thermal energy input pipe of the central refrigeration and ice maker.

Claims

1. An energy supply system, comprising: a) a solar concentrating device; b) a solar storage tank, the solar storage tank comprising a first heat exchanger and a second heat exchanger; c) a biomass power station, the biomass power station comprising a biomass boiler; d) a central refrigeration and ice maker; and e) a central hot water supply tank; wherein the solar concentrating device is connected to the solar storage tank via pipes; an inlet of the first heat exchanger of the solar storage tank is connected to an outlet of a feedwater pump of the biomass boiler; an outlet of the first heat exchanger is connected to an inlet of a water feeding system of the biomass boiler; an inlet pipe of the second heat exchanger of the solar storage tank is connected to an outlet pipe of a water purification plant; an outlet of the second heat exchanger is connected to a thermal energy input pipe of the central refrigeration and ice maker; and cooling water in the central refrigeration and ice maker absorbs released thermal energy produced by the central refrigeration and ice maker and converges with hot water from a waste heat collector disposed in a flue of the biomass boiler, and confluent hot water is transported to the central hot water supply tank.

2. The system of claim 1, wherein the solar storage tank comprises two media for heat exchange and two cycles; the two media are a heat storage medium and circulating water; the heat storage medium is heat conduction oil or molten salt disposed in the solar storage tank; and in use, the heat conduction oil or molten salt is driven by a high temperature pump to the solar concentrating device where the heat conduction oil or molten salt is heated by solar energy; the heated heat conduction oil or molten salt returns to the solar storage tank and releases heat energy; part of the heat energy heats the circulating water from the feedwater pump of the biomass boiler via the first heat exchanger, and the heated circulating water is introduced to the biomass boiler; another part of the heat energy heats the circulating water from the water purification plant via the second heat exchanger, and the heated circulating water is introduced to the central refrigeration and ice maker.

3. The system of claim 2, wherein the central refrigeration and ice maker is a lithium-bromide absorption-type refrigerator or an evaporation refrigerator.

4. The system of claim 2, wherein the molten salt is a binary nitrate system.

5. The system of claim 4, wherein the binary nitrate system comprises between 40% and 90 wt. % of NaNO.sub.3 and between 10% and 60 wt. % of KNO.sub.3.

6. The system of claim 2, wherein the molten salt is a ternary nitrate system.

7. The system of claim 6, wherein the ternary nitrate system comprises between 5% and 10 wt. % of NaNO.sub.2, between 30% and 70 wt. % of NaNO.sub.3 and between 20% and 65 wt. % of KNO.sub.3.

8. The system of claim 1, wherein the solar storage tank comprises three media for heat exchange and two cycles; the three media are a heat storage medium, a heat transfer medium, and circulating water; and in use, the heat storage medium is molten salt disposed in the solar storage tank; the heat transfer medium is heat conduction oil disposed in a solar heat exchanger; the heat conduction oil is driven to the solar concentrating device where the heat conduction oil is heated by solar energy; the heated heat conduction oil returns to the solar storage tank and exchanges heat energy with the molten salt via the solar heat exchanger; part of the heated molten salt heats the circulating water from the feedwater pump of the biomass boiler via the first heat exchanger, and the heated circulating water is introduced to the biomass boiler; another part of the heated molten salt heats the circulating water from the water purification plant via the second heat exchanger, and the heated circulating water is introduced to the central refrigeration and ice maker.

9. The system of claim 8, wherein the central refrigeration and ice maker is a lithium-bromide absorption-type refrigerator or an evaporation refrigerator.

10. The system of claim 8, wherein the molten salt is a binary nitrate system.

11. The system of claim 10, wherein the binary nitrate system comprises between 40% and 90 wt. % of NaNO.sub.3 and between 10% and 60 wt. % of KNO.sub.3.

12. The system of claim 8, wherein the molten salt is a ternary nitrate system.

13. The system of claim 12, wherein the ternary nitrate system comprises between 5% and 10 wt. % of NaNO.sub.2, between 30% and 70 wt. % of NaNO.sub.3 and between 20% and 65 wt. % of KNO.sub.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a solar-biomass complementary thermal energy supply system in accordance with one embodiment of the invention;

(2) FIG. 2 is a schematic diagram of a solar storage tank comprising two media and two cycles; and

(3) FIG. 3 is a schematic diagram of a solar storage tank comprising three media and two cycles.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) For further illustrating the invention, experiments detailing a solar-biomass complementary thermal energy supply system are described below. It should be noted that the following examples are intended to describe and not to limit the invention.

(5) As shown in FIG. 1, the invention provides a solar-biomass complementary thermal energy supply system, comprising: a solar concentrating device, a solar storage tank comprising a first heat exchanger and a second heat exchanger, a biomass power station comprising a biomass boiler, a central refrigeration and ice maker, and a central hot water supply tank, wherein the solar concentrating device is connected to the solar storage tank via pipes; an inlet of the first heat exchanger B1 of the solar storage tank is connected to an outlet of a feedwater pump of the biomass boiler; an outlet of the first heat exchanger B1 is connected to an inlet of a water feeding system of the biomass boiler; an inlet pipe of the second heat exchanger B2 of the solar storage tank is connected to an outlet pipe of a water purification plant; an outlet of the second heat exchanger B2 is connected to a thermal energy input pipe of the central refrigeration and ice maker; cooling water in the central refrigeration and ice maker absorbs released thermal energy produced by the central refrigeration and ice maker and converges with hot water from a waste heat collector disposed in a flue of the biomass boiler, and the confluent hot water is transported to the central hot water supply tank.

(6) FIG. 2 is a schematic diagram of a solar storage tank comprising two media and two cycles.

(7) The heat storage medium 1a disposed in the solar storage tank heat 1 is conduction oil or molten salt. The heat conduction oil or molten salt is driven by a high temperature pump 2a through a high temperature valve 2b to the solar concentrating device where the heat conduction oil or molten salt is heated by solar energy. The heated heat conduction oil or molten salt returns to the solar storage tank and releases heat energy. Part of the heat energy heats the circulating water from the feedwater pump of the biomass boiler via the first heat exchanger B1, and the heated circulating water is introduced to the biomass boiler. 3a represents the feedwater pump of the biomass boiler, and 3b represents an outlet valve of the feedwater pump.

(8) Another part of the heat energy heats the circulating water from the water purification plant via the second heat exchanger B2, and the heated circulating water is introduced to the central refrigeration and ice maker. The central refrigeration and ice maker is a lithium-bromide absorption-type refrigerator or an evaporation refrigerator. Preferably, the heat conduction oil is a mixture of 23.5 wt. % of biphenyl and 72.5 wt. % of diphenyl oxide. The molten salt is a mixture of NaNO.sub.3 and KNO.sub.3, or a mixture of NaNO.sub.2, NaNO.sub.3 and KNO.sub.3.

(9) FIG. 3 is a schematic diagram of a solar storage tank comprising three media and two cycles.

(10) The three media are a heat storage medium, a heat transfer medium, and circulating water. The heat storage medium 1a is molten salt disposed in the solar storage tank 1. The heat transfer medium is heat conduction oil disposed in a solar heat exchanger A. The heat conduction oil is driven by a high temperature pump 2a through a high temperature valve 2b to the solar concentrating device where the heat conduction oil is heated by solar energy. The heated heat conduction oil returns to the solar storage tank and exchanges heat energy with the molten salt via the solar heat exchanger A. Part of the heated molten salt heats the circulating water from the feedwater pump of the biomass boiler via the first heat exchanger B1, and the heated circulating water is introduced to the biomass boiler. 3 represents the feedwater pump of the biomass boiler, and 3a represents an outlet valve of the feedwater pump.

(11) When the solar-biomass complementary thermal energy supply system in FIG. 3 runs smoothly, part of the heated molten salt heats the circulating water from the water purification plant via the second heat exchanger B2, and the heated circulating water is introduced to the central refrigeration and ice maker. When the solar storage tank malfunctions for a long time, the molten salt tends to froze and block the pipes, and thus, superheated steam is introduced to the second heat exchanger B2 to solve the problem of freezing and blocking.

(12) To maximize the complementarity of the biomass energy and solar thermal power generation and reduce the waste heat discharge of the system, a waste heat collector is disposed in the flue of the biomass boiler, and a hot water output pipe of the waste heat collector is connected to the central hot water supply tank. Cold water absorbs the waste heat of the exhaust gas of the biomass boiler and the discharged heat energy from the central refrigeration and ice maker and transforms into hot water, which is collected by the central hot water supply tank to supply hot water for a low carbon industrial park.

(13) The solar concentrating device (employing parabolic trough type evacuated collector tubes, Fresnel type evacuated collector tubes, or tower type solar heat boiler) comprises a heat conduction medium, which absorbs the solar energy and then flows into the solar storage tank with high temperature. In the solar storage tank, the heat conduction medium undergoes the heat exchange and then has low temperature. The heat conduction medium is driven by a high temperature pump and functions as a circulating thermal medium between the solar concentrating device and the solar storage tank. The solar storage tank comprises another cycle, that is, water medium-vapor cycle. Specifically, condenser water from a turbine is confluent with softened water from a chemical water workshop in a deaerator for oxygen removal. The mixed water is driven by the feedwater pump and flows into the heat exchanger in the solar storage tank for heat exchange whereby absorbing heat energy and raising the temperature, and is then introduced to the steam drum of the biomass boiler for steam generation.

(14) The heat conduction medium flowing through the solar concentrating device is heat conduction oil.

(15) The heat conduction oil is a mixture of 23.5 wt. % of biphenyl and 72.5 wt. % of diphenyl oxide, which presents solid at the temperature of below 12 C., presents liquid but has high viscosity and poor fluidity at the temperature of between 12 and 50 C., and tends to thermally decompose at the temperature of exceeding 405 C. In general, the temperature of the mixture is controlled at between 50 and 395 C. for heat conduction.

(16) Preferably, the molten salt is a binary nitrate system comprising NaNO.sub.3 and KNO.sub.3, for example, between 40% and 90 wt. % of NaNO.sub.3 and between 10% and 60 wt. % of KNO.sub.3.

(17) The binary nitrate system presents solid at the temperature of below 295 C., presents liquid at the temperature of between 295 and 565 C., and tends to thermally decompose at the temperature of exceeding 565 C. In general, the temperature of the mixture is controlled at between 295 and 550 C. for heat conduction.

(18) When the weight percentage of the components of the binary nitrate system varies, so do the temperature characteristics.

(19) Preferably, the molten salt is a ternary nitrate system comprising NaNO.sub.2, NaNO.sub.3, KNO.sub.3, for example, between 5% and 10 wt. % of NaNO.sub.2, between 30% and 70 wt. % of NaNO.sub.3 and between 20% and 65 wt. % of KNO.sub.3.

(20) The ternary nitrate system presents solid at the temperature of below 180 C., presents liquid at the temperature of between 180 and 500 C., and tends to thermally decompose at the temperature of exceeding 500 C., and decompose quickly at the temperature of exceeding 550 C. In general, the temperature of the mixture is controlled at between 180 and 500 C. for heat conduction.

(21) When the weight percentage of the components of the ternary nitrate system varies, so do the temperature characteristics.

(22) In summary, the thermal energy supply system of the invention makes full use of the complementarity of the biomass energy and solar energy for central cool supply, ice supply and heat supply, so that the clean solar energy and biomass energy can be recycled for three consecutive times, thereby maximizing the utilization of energy. The solar-biomass complementary thermal energy supply system can be used in a low carbon industrial park for power generation, cooling and ice generation, and hot water generation.

(23) While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.