CN113175686B - Preheating method of molten salt heat storage system based on gas heat storage oxidation - Google Patents
Preheating method of molten salt heat storage system based on gas heat storage oxidation Download PDFInfo
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- CN113175686B CN113175686B CN202110500824.5A CN202110500824A CN113175686B CN 113175686 B CN113175686 B CN 113175686B CN 202110500824 A CN202110500824 A CN 202110500824A CN 113175686 B CN113175686 B CN 113175686B
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- 150000003839 salts Chemical class 0.000 title claims abstract description 145
- 238000005338 heat storage Methods 0.000 title claims abstract description 48
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 32
- 230000003647 oxidation Effects 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 12
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 65
- 239000003546 flue gas Substances 0.000 claims abstract description 65
- 239000007789 gas Substances 0.000 claims abstract description 51
- 238000002156 mixing Methods 0.000 claims abstract description 20
- 238000006243 chemical reaction Methods 0.000 claims abstract description 19
- 238000003860 storage Methods 0.000 claims abstract description 7
- 238000002485 combustion reaction Methods 0.000 claims abstract description 5
- 239000000843 powder Substances 0.000 claims description 52
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 claims description 40
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical group [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 32
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 32
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 20
- 235000010288 sodium nitrite Nutrition 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 16
- 235000010333 potassium nitrate Nutrition 0.000 claims description 16
- 239000004323 potassium nitrate Substances 0.000 claims description 16
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 16
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 16
- 238000012360 testing method Methods 0.000 claims description 13
- 238000000227 grinding Methods 0.000 claims description 12
- 239000000654 additive Substances 0.000 claims description 8
- 230000000996 additive effect Effects 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- 239000000428 dust Substances 0.000 claims description 8
- 238000007710 freezing Methods 0.000 claims description 8
- 230000008014 freezing Effects 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- 235000010344 sodium nitrate Nutrition 0.000 claims description 8
- 239000004317 sodium nitrate Substances 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000001938 differential scanning calorimetry curve Methods 0.000 claims description 4
- 238000005265 energy consumption Methods 0.000 claims description 4
- 238000002474 experimental method Methods 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 239000011812 mixed powder Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 235000017550 sodium carbonate Nutrition 0.000 claims description 4
- 239000008247 solid mixture Substances 0.000 claims description 4
- 238000005303 weighing Methods 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 claims description 2
- 230000000704 physical effect Effects 0.000 claims 1
- 238000005086 pumping Methods 0.000 claims 1
- 238000009826 distribution Methods 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 4
- 238000009423 ventilation Methods 0.000 description 6
- 239000003245 coal Substances 0.000 description 5
- 238000000605 extraction Methods 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/0034—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
- C09K5/08—Materials not undergoing a change of physical state when used
- C09K5/10—Liquid materials
- C09K5/12—Molten materials, i.e. materials solid at room temperature, e.g. metals or salts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L15/00—Heating of air supplied for combustion
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/0034—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material
- F28D2020/0047—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material using molten salts or liquid metals
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/14—Thermal energy storage
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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Abstract
The invention relates to a preheating method of a molten salt heat storage system based on gas heat storage oxidation, which comprises the following steps: preheating: mixing low-concentration gas discharged by a gas pump station with air, then introducing the mixed gas into a preheating device for preheating, introducing the mixed gas into a combustion chamber of a heat storage oxidation device for oxidation reaction after preheating to the reaction starting temperature, and generating high-temperature flue gas during reaction; step two, heat storage: then introducing the high-temperature flue gas into a molten salt heat exchanger, reversing the flow direction of the high-temperature flue gas and molten salt, and transferring heat between the high-temperature flue gas and the molten salt by depending on the difference between the flow speed of the high-temperature flue gas and the moving speed of reaction heat waves, namely exchanging heat with low-temperature molten salt from a low-temperature molten salt tank; the storage and reasonable distribution utilization of heat energy are realized, the waste of heat energy is effectively avoided, the utilization rate of heat energy is improved, energy sources are saved, and the atmospheric environment is protected.
Description
Technical Field
The invention belongs to the technical field of gas heat storage, and relates to a preheating method of a molten salt heat storage system based on gas heat storage oxidation.
Background
The low-concentration gas in the coal mine is the most main emission source of the gas in the coal mine, and is emptied in large quantity for a long time due to the lack of an effective utilization way, so that the remarkable greenhouse effect trend and energy waste are caused, and the low utilization rate of the coal bed gas in China is also an important reason. Statistical data show that the total quantity of gas extracted in China in 2017 is 128 billion cubic meters, the utilization quantity is 49 billion cubic meters, and the utilization ratio is only about 38%.
The low-concentration gas is subjected to oxidation reaction in the heat storage oxidation device to release heat, wherein a part of heat is used for maintaining the balance of the self heat of the oxidation device and outputting the redundant heat in the form of high-temperature flue gas, the residual heat of the high-temperature flue gas is large, resources are wasted due to long-term emission, and non-negligible thermal pollution is caused to the atmospheric environment, so that the development of heat storage materials for comprehensive and effective utilization of heat energy is very important.
The ventilation air methane heat-storage oxidation system comprises a ventilation air methane inlet pipe communicated with an outlet of a coal mine air shaft, at least 2 gas heat-storage oxidation devices sequentially communicated with the ventilation air methane inlet pipe, and a flue gas outlet pipe sequentially communicated with the oxidation devices, wherein an air inlet valve and an air outlet valve are respectively arranged between the ventilation air methane inlet pipe and each oxidation device, the ventilation air methane heat-storage oxidation system further comprises a flue gas extraction pipe and an air suction pump I communicated with the flue gas extraction pipe and used for extracting flue gas in a first oxidation device I, an air suction valve is arranged between the flue gas extraction pipe and each oxidation device, and a preheating device is arranged in the oxidation device I which is only closest to the outlet of the coal mine air shaft.
The above patent has the advantages of reaching the joint preheating starting of the ventilation air methane heat storage oxidation system, reducing the repeated configuration of the preheating device and saving a large amount of investment and energy, but also has defects, such as: the device can not store the available high-temperature flue gas heat after the gas is oxidized, and further can not realize the reasonable distribution of heat energy, so that the heat energy recycling efficiency is lower.
Disclosure of Invention
In view of the above, the present invention provides a preheating method for a molten salt heat storage system based on gas heat storage oxidation.
In order to achieve the purpose, the invention provides the following technical scheme:
the preheating method of the molten salt heat storage system based on the gas heat storage oxidation comprises the following steps:
preheating: mixing low-concentration gas discharged by a gas pump station with air, then introducing the mixed gas into a preheating device for preheating, introducing the mixed gas into a combustion chamber of a heat storage oxidation device for oxidation reaction after preheating to the reaction starting temperature, and generating high-temperature flue gas during reaction;
step two, heat storage: then introducing the high-temperature flue gas into a molten salt heat exchanger, reversing the flow direction of the high-temperature flue gas and the molten salt, and transferring heat between the high-temperature flue gas and the molten salt by depending on the difference between the flow speed of the high-temperature flue gas and the moving speed of a reaction heat wave, namely exchanging heat with the low-temperature molten salt from a low-temperature molten salt tank, heating and melting the low-temperature molten salt to obtain the high-temperature molten salt, and finally injecting the high-temperature molten salt into the molten salt tank for storage;
step three, heat release: and in the energy consumption peak period, a high-temperature heat release molten salt pump is started, high-temperature molten salt is injected into a hot air heat exchanger to exchange heat with hot air passing through an air preheater to obtain high-temperature hot air, and then the high-temperature hot air is mixed with cold air from a mixing fan to obtain the hot air suitable for preventing the shaft from freezing.
Preferably, the temperature of the high-temperature flue gas in the heat storage in the second step is 850-950 ℃, the temperature of the flue gas is reduced to 200-260 ℃ after the flue gas passes through the molten salt heat exchanger, and then the flue gas is sent to an energy utilization area for use;
and a 800kW molten salt electric heater is arranged beside the molten salt heat exchanger for standby and is used for heating molten salt when high-temperature flue gas is insufficient.
Preferably, cold air needs to be preheated in the heat release in the third step, hot air is pumped out from a high-temperature air main pipeline in the heat storage system to be used as a heat source to preheat the cold air, the cold air is preheated to 130 ℃ and then sent to a heat exchanger to exchange heat with molten salt, high-temperature air at 350 ℃ is obtained, and then the high-temperature air is mixed with cold air of the mixing and blending fan, so that hot air at 40-50 ℃ suitable for preventing freezing of a shaft is obtained.
Preferably, after the preheating device is started in the first preheating step, the incoming mixed gas is preheated, and then the temperature of the preheating device is raised to 600-1000 ℃, so that the gas with the methane concentration of more than 0.3% in the mixed gas is completely consumed.
Preferably, before heat storage in the second step, the high-temperature flue gas is introduced into the filter, dust and impurities in the high-temperature flue gas are removed, and meanwhile, a detector is arranged at an exhaust pipe of the filter to detect the dust and impurities in the discharged high-temperature flue gas.
Preferably, the molten salt comprises 95% of base salt and 5% of additive in total mass fraction.
Preferably, the base salt comprises 53 percent of potassium nitrate, 7 percent of sodium nitrate and 40 percent of sodium nitrite in total mass fraction, and the additive is sodium carbonate.
Preferably, the preparation method of the molten salt is as follows:
s11, weighing 50.35% of potassium nitrate, 6.65% of sodium nitrate, 38% of sodium nitrite and 5% of sodium carbonate in percentage by weight for later use;
s12, sequentially putting the weighed potassium nitrate, sodium nitrite and sodium carbonate into a grinder, and after grinding is finished, putting the potassium nitrate powder, the sodium nitrite powder and the sodium carbonate powder into a mixer for fully mixing to obtain mixed salt powder, namely the molten salt.
Preferably, the thermal property experiment is performed on the molten salt powder after S12, and the specific steps are as follows:
s21, placing the mixed salt powder into a crucible, then placing the crucible into a muffle furnace for heating, wherein the temperature of the muffle furnace is initially set to 350 ℃, if the mixed salt powder reaches a molten state, keeping the temperature of the mixed salt powder at 350 ℃ for 3 hours, and if the mixed salt powder does not reach the molten state, heating to 500 ℃ and keeping the temperature until the mixed salt powder is completely molten;
s22, taking out the completely molten mixed salt from the muffle furnace, cooling at room temperature, putting the solid mixture into grinding equipment for fully grinding after cooling, obtaining mixture powder again, testing the mixed powder by using a differential scanning calorimeter, and obtaining a DSC curve chart after testing.
Preferably, in the thermal property test, the mixed salt powder is protected by nitrogen so that sodium nitrite in the mixed salt powder is not oxidized by contacting with oxygen.
The invention has the beneficial effects that: through preheating, heat-retaining and exothermic three flow, can preheat low concentration gas, make it unanimous with reaction temperature, and then improve reaction efficiency, then carry out the heat transfer through the high temperature flue gas that will react and fused salt, store it in fused salt when heat energy is excessive, at last when heat energy is not enough, release the heat energy in the high temperature fused salt, realize the storage and the rational distribution utilization of heat energy, the waste of heat energy has effectively been avoided, the utilization ratio of heat energy is improved, the energy has been practiced thrift simultaneously, the atmospheric environment has been protected.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For a better understanding of the objects, aspects and advantages of the present invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a block flow diagram of the present invention;
FIG. 2 is a DSC chart of the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustration only and not for the purpose of limiting the invention, shown in the drawings are schematic representations and not in the form of actual drawings; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore the terms describing the positional relationship in the drawings are only used for illustrative purposes and are not to be construed as limiting the present invention, and the specific meaning of the terms described above will be understood by those skilled in the art according to the specific circumstances.
Please refer to FIGS. 1-2
Example 1
The preheating method of the molten salt heat storage system based on the gas heat storage oxidation comprises the following steps:
preheating: mixing low-concentration gas discharged by a gas pump station with air, then introducing the mixed gas into a preheating device for preheating, introducing the mixed gas into a combustion chamber of a heat storage oxidation device for oxidation reaction after preheating to the reaction starting temperature, and generating high-temperature flue gas during the reaction;
step two, heat storage: then introducing the high-temperature flue gas into a molten salt heat exchanger, reversing the flow direction of the high-temperature flue gas and molten salt, and transferring heat between the high-temperature flue gas and the molten salt by depending on the difference between the flow speed of the high-temperature flue gas and the moving speed of a reaction heat wave, namely exchanging heat with low-temperature molten salt from a low-temperature molten salt tank, heating and melting the low-temperature molten salt to obtain high-temperature molten salt, and finally injecting the high-temperature molten salt into the molten salt tank for storage;
step three, releasing heat: and during the energy consumption peak period, starting a high-temperature heat release molten salt pump, injecting high-temperature molten salt into a hot air heat exchanger to exchange heat with hot air passing through an air preheater to obtain high-temperature hot air, and then mixing the high-temperature hot air with cold air from a mixing fan to obtain the hot air suitable for preventing the shaft from freezing.
In this embodiment, preferably, the temperature of the high-temperature flue gas in the heat storage in the step two is 950 ℃, and after passing through the molten salt heat exchanger, the temperature of the flue gas is reduced to 240 ℃, and then the flue gas is sent to an energy utilization area for use;
set up a 800 kW's fused salt electric heater by fused salt heat exchanger as reserve, be used for heating the fused salt when high temperature flue gas is not enough.
In this embodiment, preferably, in the third step of heat release, cold air needs to be preheated, hot air is pumped from a main high-temperature air pipeline in the heat storage system to be used as a heat source to preheat the cold air, the cold air is preheated to 130 ℃ and then sent to a heat exchanger to exchange heat with molten salt, high-temperature air at 350 ℃ is obtained, and then the high-temperature air is mixed with cold air of a mixing fan, so that hot air at 50 ℃ suitable for preventing freezing of a shaft is obtained.
In this embodiment, preferably, after the preheating device is turned on in the first preheating step, the entering mixed gas is preheated, and then the temperature of the preheating device is raised to 1000 ℃, so that the gas with the methane concentration of more than 0.3% in the mixed gas is completely consumed.
In this embodiment, preferably, before the heat storage in the second step, the high-temperature flue gas is introduced into the filter to remove dust and impurities in the high-temperature flue gas, and meanwhile, a detector is arranged at an exhaust pipe of the filter to detect the dust and impurities in the discharged high-temperature flue gas.
In this embodiment, preferably, the molten salt comprises 95% of the base salt and 5% of the additive by mass.
In this embodiment, preferably, the base salt includes 53% potassium nitrate, 7% sodium nitrate and 40% sodium nitrite by mass, and the additive is sodium carbonate.
In this embodiment, preferably, the molten salt is prepared as follows:
s11, weighing 50.35 percent of potassium nitrate, 6.65 percent of sodium nitrate, 38 percent of sodium nitrite and 5 percent of sodium carbonate in percentage by total weight for later use;
s12, sequentially putting the weighed potassium nitrate, sodium nitrite and sodium carbonate into a grinder, and after grinding is finished, putting the potassium nitrate powder, the sodium nitrite powder and the sodium carbonate powder into a mixer for fully mixing to obtain mixed salt powder, namely the molten salt.
In this embodiment, preferably, the thermal property test is performed on the molten salt powder after S12, and the specific steps are as follows:
s21, placing the mixed salt powder into a crucible, then placing the crucible into a muffle furnace for heating, wherein the temperature of the muffle furnace is initially set to 350 ℃, if the mixed salt powder reaches a molten state, keeping the temperature of the mixed salt powder at 350 ℃ for 3 hours, and if the mixed salt powder does not reach the molten state, heating to 500 ℃ and keeping the temperature until the mixed salt powder is completely molten;
s22, taking out the completely molten mixed salt from the muffle furnace, cooling at room temperature, putting the solid mixture into grinding equipment for full grinding after cooling, obtaining mixture powder again, finally testing the mixed powder by using a differential scanning calorimeter, and obtaining a DSC curve chart after the test is finished.
In the present example, it is preferable that the mixed salt powder is protected with nitrogen gas in the thermophysical property test so that sodium nitrite in the mixed salt powder is not oxidized by contact with oxygen gas.
Example 2
The preheating method of the molten salt heat storage system based on gas heat storage oxidation comprises the following steps:
preheating: mixing low-concentration gas discharged by a gas pump station with air, then introducing the mixed gas into a preheating device for preheating, introducing the mixed gas into a combustion chamber of a heat storage oxidation device for oxidation reaction after preheating to the reaction starting temperature, and generating high-temperature flue gas during reaction;
step two, heat storage: then introducing the high-temperature flue gas into a molten salt heat exchanger, reversing the flow direction of the high-temperature flue gas and the molten salt, and transferring heat between the high-temperature flue gas and the molten salt by depending on the difference between the flow speed of the high-temperature flue gas and the moving speed of a reaction heat wave, namely exchanging heat with the low-temperature molten salt from a low-temperature molten salt tank, heating and melting the low-temperature molten salt to obtain the high-temperature molten salt, and finally injecting the high-temperature molten salt into the molten salt tank for storage;
step three, releasing heat: and in the energy consumption peak period, a high-temperature heat release molten salt pump is started, high-temperature molten salt is injected into a hot air heat exchanger to exchange heat with hot air passing through an air preheater to obtain high-temperature hot air, and then the high-temperature hot air is mixed with cold air from a mixing fan to obtain the hot air suitable for preventing the shaft from freezing.
In this embodiment, preferably, the temperature of the high-temperature flue gas in the heat storage in the second step is 850 ℃, and after passing through the molten salt heat exchanger, the temperature of the flue gas is reduced to 250 ℃, and then the flue gas is sent to an energy utilization area for use;
a800 kW molten salt electric heater is arranged beside the molten salt heat exchanger for standby, and is used for heating molten salt when high-temperature flue gas is insufficient.
In this embodiment, preferably, in the third step of heat release, cold air needs to be preheated, hot air is pumped from a main high-temperature air pipeline in the heat storage system to be used as a heat source to preheat the cold air, the cold air is preheated to 130 ℃ and then sent to a heat exchanger to exchange heat with molten salt, high-temperature air at 350 ℃ is obtained, and then the high-temperature air is mixed with cold air of a mixing fan, so that hot air at 45 ℃ suitable for preventing freezing of a shaft is obtained.
In this embodiment, preferably, after the preheating device is turned on in the first preheating step, the incoming mixed gas is preheated, and then the temperature of the preheating device is raised to 850 ℃, so that the gas with the methane concentration of more than 0.3% in the mixed gas is completely consumed.
In this embodiment, preferably, before the heat storage in the second step, the high-temperature flue gas is introduced into the filter to remove dust and impurities in the high-temperature flue gas, and meanwhile, a detector is arranged at an exhaust pipe of the filter to detect the dust and impurities in the discharged high-temperature flue gas.
In this embodiment, preferably, the molten salt comprises 95% of the base salt and 5% of the additive by mass.
In this embodiment, preferably, the base salt includes 53% potassium nitrate, 7% sodium nitrate and 40% sodium nitrite by mass, and the additive is sodium carbonate.
In this embodiment, preferably, the molten salt is prepared as follows:
s11, weighing 50.35 percent of potassium nitrate, 6.65 percent of sodium nitrate, 38 percent of sodium nitrite and 5 percent of sodium carbonate in percentage by total weight for later use;
s12, sequentially putting the weighed potassium nitrate, sodium nitrite and sodium carbonate into a grinder, and after grinding is finished, putting the potassium nitrate powder, the sodium nitrite powder and the sodium carbonate powder into a mixer for fully mixing to obtain mixed salt powder, namely the molten salt.
In this embodiment, preferably, the thermal property test is performed on the molten salt powder after S12, and the specific steps are as follows:
s21, placing the mixed salt powder into a crucible, then placing the crucible into a muffle furnace for heating, wherein the temperature of the muffle furnace is initially set to 350 ℃, if the mixed salt powder reaches a molten state, keeping the temperature of the mixed salt powder at 350 ℃ for 3 hours, and if the mixed salt powder does not reach the molten state, heating to 500 ℃ and keeping the temperature until the mixed salt powder is completely molten;
s22, taking out the completely molten mixed salt from the muffle furnace, cooling at room temperature, putting the solid mixture into grinding equipment for full grinding after cooling, obtaining mixture powder again, finally testing the mixed powder by using a differential scanning calorimeter, and obtaining a DSC curve chart after the test is finished.
In the present example, it is preferable that the mixed salt powder is protected with nitrogen gas in the thermophysical property test so that sodium nitrite in the mixed salt powder is not oxidized by contact with oxygen gas.
The working principle and the using process of the invention are as follows:
this molten salt heat-storage system preheating method based on gas heat accumulation oxidation, through preheating, heat-retaining and exothermic three flow, can preheat low concentration gas, make it unanimous with reaction temperature, and then improve reaction efficiency, then carry out the heat transfer through the high temperature flue gas that will react and the fused salt, store it in fused salt when heat energy is excessive, when heat energy is not enough at last, release the heat energy in the high temperature fused salt, realize the storage and the rational distribution utilization of heat energy, the waste of heat energy has effectively been avoided, the utilization ratio of heat energy has been improved, simultaneously, the energy has been practiced thrift, the atmospheric environment has been protected.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (1)
1. The preheating method of the molten salt heat storage system based on the gas heat storage oxidation is characterized by comprising the following steps: the method comprises the following steps:
preheating: mixing low-concentration gas discharged by a gas pump station with air, then introducing the mixed gas into a preheating device for preheating, introducing the mixed gas into a combustion chamber of a heat storage oxidation device for oxidation reaction after preheating to the reaction starting temperature, and generating high-temperature flue gas during the reaction;
step two, heat storage: then introducing the high-temperature flue gas into a molten salt heat exchanger, reversing the flow direction of the high-temperature flue gas and the molten salt, and transferring heat between the high-temperature flue gas and the molten salt by depending on the difference between the flow speed of the high-temperature flue gas and the moving speed of a reaction heat wave, namely exchanging heat with the low-temperature molten salt from a low-temperature molten salt tank, heating and melting the low-temperature molten salt to obtain the high-temperature molten salt, and finally injecting the high-temperature molten salt into the molten salt tank for storage;
step three, heat release: when the energy consumption peak period is over, a high-temperature heat release molten salt pump is started, high-temperature molten salt is injected into a hot air heat exchanger to exchange heat with hot air passing through an air preheater to obtain high-temperature hot air, and then the high-temperature hot air is mixed with cold air from a mixing fan to obtain hot air suitable for preventing a shaft from freezing;
the temperature of the high-temperature flue gas in the heat storage in the step two is 850-950 ℃, the temperature of the flue gas is reduced to 200-260 ℃ after the flue gas passes through the molten salt heat exchanger, and then the flue gas is sent to an energy utilization area for use;
a 800kW molten salt electric heater is arranged beside the molten salt heat exchanger for standby, and is used for heating molten salt when high-temperature flue gas is insufficient;
preheating cold air during heat release in the third step, pumping hot air from a high-temperature air main pipeline in a heat storage system to serve as a heat source to preheat the cold air, preheating the cold air to 130 ℃, sending the cold air to a heat exchanger to exchange heat with molten salt to obtain 350 ℃ high-temperature air, and mixing the 350 ℃ high-temperature air with cold air of the mixing fan to obtain 40-50 ℃ hot air suitable for preventing freezing of a shaft;
after the preheating device is started in the preheating in the first step, preheating the entering mixed gas, and then raising the temperature of the preheating device to 600-1000 ℃ to ensure that the gas with the methane concentration of more than 0.3% in the mixed gas is completely consumed;
before heat storage in the second step, high-temperature flue gas is introduced into a filter, dust impurities in the high-temperature flue gas are removed, and meanwhile a detector is arranged at an exhaust pipe of the filter to detect the dust impurities in the discharged high-temperature flue gas;
the molten salt comprises 95% of base salt and 5% of additive in total mass fraction;
the base salt comprises 53 percent of potassium nitrate, 7 percent of sodium nitrate and 40 percent of sodium nitrite in total mass fraction, and the additive is sodium carbonate;
the preparation method of the molten salt comprises the following steps:
s11, weighing 50.35% of potassium nitrate, 6.65% of sodium nitrate, 38% of sodium nitrite and 5% of sodium carbonate in percentage by weight for later use;
s12, sequentially putting the weighed potassium nitrate, sodium nitrite and sodium carbonate into a grinder, and after grinding is finished, putting the potassium nitrate powder, the sodium nitrite powder and the sodium carbonate powder into a mixer for fully mixing to obtain mixed salt powder, namely the molten salt;
and after S12, performing a thermophysical property experiment on the molten salt powder, wherein the thermophysical property experiment comprises the following specific steps:
s21, placing the mixed salt powder into a crucible, then placing the crucible into a muffle furnace for heating, wherein the temperature of the muffle furnace is initially set to 350 ℃, if the mixed salt powder reaches a molten state, keeping the temperature of the mixed salt powder at 350 ℃ for 3 hours, and if the mixed salt powder does not reach the molten state, heating to 500 ℃ and keeping the temperature until the mixed salt powder is completely molten;
s22, taking out the completely molten mixed salt from the muffle furnace, cooling at room temperature, putting the solid mixture into grinding equipment for full grinding after cooling, obtaining mixture powder again, testing the mixed powder by using a differential scanning calorimeter, and obtaining a DSC curve chart after testing;
in the thermal physical property experiment, nitrogen is used for protecting the mixed salt powder, so that sodium nitrite in the mixed salt powder is not in contact with oxygen to be oxidized.
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