Energy storage heat exchange process for high-temperature nitrogen and oxygen separation

Abstract

This invention discloses an energy storage heat exchange process for high-temperature nitrogen and oxygen separation. Compressed air, heated to 500-1100°C, enters a high-temperature nitrogen and oxygen separator containing a perovskite ceramic gas separation membrane. The separated hot N2 / O2 is stored in a ceramic regenerative heat exchanger and used to heat the compressed air, collecting and recycling the heat. This effectively improves the energy consumption of the perovskite ceramic gas separation membrane in practical applications. Furthermore, by improving the ceramic heat storage material of the ceramic regenerative heat exchanger, the process is better adapted to the rapid cooling and heating conditions of the invention.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrogen and oxygen separation, and in particular to an energy storage heat exchange process for high-temperature nitrogen and oxygen separation. Background Art

[0002] Perovskite ceramic gas separation membranes demonstrate significant advantages in nitrogen and oxygen separation. Based on the mixed oxygen ion-electron conduction properties, they achieve oxygen-nitrogen separation at temperatures of 500-1100°C by exploiting the oxygen concentration gradient across the membrane, achieving 100% oxygen permselectivity. Currently available ceramic membranes have been shown to produce over 99% pure nitrogen and oxygen in experiments. Due to their high-temperature resistance, chemical stability, and mechanical strength, they operate stably in complex environments, such as those with high temperatures and corrosive gases, achieving high separation efficiency and promising applications in chemical production and other applications.

[0003] However, perovskite ceramic gas separation membranes also have drawbacks. Firstly, their high production cost, complicated processes, and specialized equipment requirements, such as high-temperature sintering, increase costs and limit their large-scale application. Secondly, their flux is lower than that of organic membranes, requiring larger membrane modules to process the same gas volume, increasing equipment size and cost. Furthermore, their demanding operating conditions and high-temperature operation consume excessive energy, severely restricting their widespread application in nitrogen and oxygen separation. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide an energy storage heat exchange process for high-temperature nitrogen and oxygen separation, which can effectively improve the energy consumption problem of perovskite ceramic gas separation membrane in practical applications, and also solve the durability problem under rapid cooling and heating conditions by improving the ceramic heat storage material of the ceramic heat storage heat exchanger.

[0005] To achieve the above objectives, the present invention provides an energy storage heat exchange process for high-temperature nitrogen and oxygen separation, including: the high-temperature nitrogen separated from the high-temperature nitrogen and oxygen is heat exchanged with compressed air through three sets of ceramic heat storage heat exchangers arranged in parallel, thereby achieving continuous and uninterrupted high-temperature nitrogen and oxygen separation.

[0006] Furthermore, in the uninterrupted high-temperature nitrogen and oxygen separation, three groups of ceramic thermal storage heat exchangers are arranged in parallel. One group of ceramic thermal storage heat exchangers is used to release heat to heat the compressed air; one group of ceramic thermal storage heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; and one group of ceramic thermal storage heat exchangers absorbs the heat brought by the high-temperature nitrogen and is kept as a standby. The three groups rotate to achieve uninterrupted high-temperature nitrogen and oxygen separation.

[0007] Furthermore, the compressed air coming out of the ceramic regenerative heat exchanger is electrically heated to 500°C-1100°C.

[0008] Furthermore, the high-temperature oxygen separated from the high-temperature nitrogen and oxygen is used to heat the compressed air through a partition heat exchanger, and then electrically heated to 500°C-1100°C.

[0009] More specifically, the energy storage heat exchange process for high-temperature nitrogen and oxygen separation is:

[0010] 20%-30% of the compressed air passes through the partition wall heat exchanger and is electrically heated to 500℃-1100℃;

[0011] 70%-80% of the compressed air passes through the ceramic regenerative heat exchanger and is electrically heated to 500℃-1100℃;

[0012] The compressed air is 100% after being combined and enters the high-temperature nitrogen and oxygen separator for nitrogen and oxygen separation at 500℃-1100℃;

[0013] The separated high-temperature oxygen is used to heat the compressed air through a partition heat exchanger, and then electrically heated to a reaction temperature of 500°C-1100°C; or, the separated high-temperature oxygen is used to heat the compressed air through a ceramic regenerative heat exchanger, and then electrically heated to a reaction temperature of 500°C-1100°C.

[0014] The separated high-temperature nitrogen passes through a ceramic thermal storage heat exchanger and stores heat in it; three groups of ceramic thermal storage heat exchangers are arranged in parallel, one group of ceramic thermal storage heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; one group of ceramic thermal storage heat exchangers absorbs the heat brought by the high-temperature nitrogen and is reserved for use; the three groups rotate to achieve uninterrupted high-temperature nitrogen and oxygen separation.

[0015] Furthermore, the heat storage element used in the ceramic thermal storage heat exchanger is a ceramic thermal storage material with a honeycomb or porous structure. Using a honeycomb or porous structure increases the surface area and optimizes heat exchange efficiency. Ceramic thermal storage materials offer numerous advantages, including a high melting point, high heat capacity, good chemical stability, adjustable thermal conductivity, excellent high-temperature resistance, high-pressure resistance, environmental friendliness, non-toxicity, and a long service life. These materials are well-suited for the high-temperature nitrogen-oxygen separation energy storage heat exchange process of the present invention. The ceramic thermal storage material is cordierite; more specifically, a 150×150×150 mm (43×43 pore) sheet of cordierite.

[0016] Furthermore, the high-temperature nitrogen and oxygen separator uses a perovskite ceramic gas separation membrane. When the temperature is higher than 500-1100°C and there is an oxygen concentration gradient inside and outside the membrane, the oxygen transfer process can be carried out continuously.

[0017] It should be noted that N2 accounts for 78% of the air and O2 accounts for 21%. The hot N2 separated by the high-temperature nitrogen and oxygen separator is more than the hot O2 separated. Taking into account that the hot O2 flow rate is relatively small, the ceramic thermal storage heat exchanger has higher heat exchange efficiency, high pressure resistance, and cost control of the entire system than the partition-type heat exchanger. The present invention sets three groups of ceramic thermal storage heat exchangers to absorb and store the heat brought by the hot N2 and heat 70%-80% of the compressed air, and sets the partition-type heat exchanger to heat 20%-30% of the compressed air with hot O2. When the hot O2 flow rate is adjusted to a large working condition, a ceramic thermal storage heat exchanger can also be used.

[0018] Furthermore, a nitrogen content detection device is added during the discharge process of the nitrogen discharged from the ceramic regenerative heat exchanger. In the early stage of the energy storage heat exchange process, if the nitrogen purity does not meet the standard, the nitrogen is directly discharged; when the nitrogen purity meets the standard, it is collected.

[0019] In the energy storage heat exchange process for high-temperature nitrogen and oxygen separation of the present invention, compressed air is heated to 500-1100°C and then enters a high-temperature nitrogen and oxygen separator containing a perovskite ceramic gas separation membrane; the separated hot N2 is stored in three groups of ceramic heat storage heat exchangers and used to heat the compressed air, thereby realizing the collection and recycling of heat, effectively improving the energy consumption problem of the perovskite ceramic gas separation membrane in practical applications.

[0020] On the other hand, given the high heat transfer rates of ceramic thermal storage heat exchangers, which require rapid cooling and heating, the durability of cordierite ceramic materials is insufficient to support the system's long-term, uninterrupted operation. Further improvements are needed to improve the thermal shock resistance of the thermal storage elements in ceramic thermal storage heat exchangers. This invention also provides a self-made ceramic thermal storage material.

[0021] Furthermore, the preparation method of the ceramic heat storage material is as follows: corundum, kaolin, molybdenum trioxide, and spodumene are uniformly mixed and ball-milled for 2-6 hours; a polyvinyl alcohol aqueous solution is added and granulated to obtain a blank; the blank is kneaded, aged, extruded, and honeycomb holes are cut to obtain a ceramic blank; after drying and dehydration, the temperature is raised to 900-1000°C at a rate of 10°C / min, and then further raised to 1500-1650°C at a rate of 3°C / min, and kept at 1600-1650°C for 20-40 minutes; then the temperature is naturally lowered to 1300-1450°C and kept at 1300-1450°C for 80-120 minutes; and naturally cooled to room temperature to obtain the product.

[0022] The preparation method of the ceramic heat storage material comprises the following steps: mixing 70-75 parts of corundum, 21-25 parts of kaolin, 1-4 parts of molybdenum trioxide, and 1-4 parts of spodumene by weight, and then placing the mixture in a ball mill for 2-6 hours; adding 1-6 parts of a polyvinyl alcohol aqueous solution, and granulating the mixture to obtain a blank; kneading the blank under vacuum conditions, aging the blank, and then extruding and cutting honeycomb holes to obtain a ceramic blank; drying the blank for shaping by microwave drying and removing water by hot air drying, and then heating the blank to 900-1000° C. at a rate of 10° C. / min, and then continuously heating the blank to 1500-1650° C. at a rate of 3° C. / min, and keeping the temperature at 1600-1650° C. for 20-40 minutes; then naturally cooling the blank to 1300-1450° C. and keeping the temperature at 1300-1450° C. for 80-120 minutes; and naturally cooling the blank to room temperature to obtain the ceramic blank.

[0023] Ball milling parameters: ball-to-material ratio of 10:1 (mass ratio), zirconia balls (diameter 10 mm), rotation speed 200-600 rpm, ball milling time 4-8 h.

[0024] The concentration of the polyvinyl alcohol aqueous solution is 2-25 wt %.

[0025] Each mud kneading time is 4-12 minutes and the rotation speed is 20-100rpm.

[0026] Compared with cordierite ceramics, the use of corundum-based ceramic materials as high-temperature resistant ceramic heat storage bodies is more stable at high temperatures, has less attenuation of thermal shock resistance with temperature fluctuations, has better thermal shock resistance, and can better adapt to the rapid cooling and heating conditions of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart for energy storage heat exchange for high-temperature nitrogen and oxygen separation;

[0028] Figure 2 This is a flow chart of a device for detecting nitrogen content in the discharge process of nitrogen coming out of a ceramic regenerative heat exchanger;

[0029] Figure 3 This is a switching flow chart of three groups of ceramic thermal storage heat exchangers in Example 3;

[0030] Figure numbers: 11, 15, 21, 25, 31, 35, 14, 16, 24, 26, 34, 36 are valves, 12, 22, 32 are ceramic heat storage heat exchangers, 13, 23, 33, 5 are electric heaters, 4 is a high-temperature nitrogen and oxygen separator containing perovskite ceramic gas separation membrane, 6 is a partition heat exchanger, 7 is a check valve, and 8 is a check valve. DETAILED DESCRIPTION Example 1

[0031] Energy storage heat exchange process for high-temperature nitrogen and oxygen separation, including:

[0032] Flow rate is 105Nm 3 / h, 20℃ compressed air passes through the partition heat exchanger 6 and is heated to 900℃ by the electric heater 5;

[0033] Flow rate is 245Nm 3 / h, 20℃ compressed air passes through the ceramic regenerative heat exchanger 12 and is heated to 900℃ by the electric heater 13; at this time, valves 11, 14, 35, and 36 are in the open state; valves 15, 16, 21, 24, 25, 26, 31, and 34 are in the closed state;

[0034] After the above compressed air is combined, it enters the high-temperature nitrogen and oxygen separator 4 for nitrogen and oxygen separation;

[0035] The separated high-temperature oxygen is used to heat the compressed air through the partition heat exchanger 6, and then electrically heated to 900°C to achieve heat recovery and utilization;

[0036] The separated high-temperature nitrogen passes through the ceramic regenerative heat exchanger 32 and stores heat therein; after the ceramic regenerative heat exchanger 32 stores heat for 120 seconds, valves 36 and 35 are closed, and valves 26 and 25 are opened, so that the separated high-temperature nitrogen passes through the ceramic regenerative heat exchanger 22 and stores heat therein; after the ceramic regenerative heat exchanger 22 stores heat for 120 seconds, valves 26, 25, 11, and 14 are closed, and valves 31 and 34 are opened, with a flow rate of 245 Nm 3 / h, 20°C compressed air passes through ceramic regenerative heat exchanger 32 and is heated to 900°C by electric heater 33. Three sets of ceramic regenerative heat exchangers are arranged in parallel: one set uses the heat from the absorbed high-temperature nitrogen to heat the compressed air (i.e., releases heat); one set absorbs the heat from the high-temperature nitrogen and remains in standby mode (i.e., absorbs heat); and one set is in standby mode. These three sets rotate to achieve uninterrupted high-temperature nitrogen and oxygen separation.

[0037] Table 1 Stable operating parameters of partition wall heat exchanger

[0038]

[0039] Table 2 Stable operating parameters of ceramic regenerative heat exchanger inlet air

[0040]

[0041] Table 3 Stable operating parameters of the ceramic thermal storage heat exchanger outlet gas

[0042]

[0043] Stable working state:

[0044] 120-second fixed cycle:

[0045] 0-120 seconds: valves 11, 14, 35, and 36 are open, and valves 15, 16, 21, 24, 25, 26, 31, and 34 are closed; at this time, the ceramic thermal storage heat exchanger 12 releases heat, the ceramic thermal storage heat exchanger 22 is on standby, and the ceramic thermal storage heat exchanger 32 stores heat.

[0046] 120-240 seconds: Valves 15, 16, 21, and 24 are opened, and valves 11, 14, 25, 26, 31, 34, 35, and 36 are closed; at this time, the ceramic thermal storage heat exchanger 12 stores heat, the ceramic thermal storage heat exchanger 22 releases heat, and the ceramic thermal storage heat exchanger 32 is on standby.

[0047] 240-360 seconds: Valves 25, 26, 31, and 34 are opened, and valves 11, 14, 15, 16, 21, 24, 35, and 36 are closed; at this time, the ceramic thermal storage heat exchanger 12 is on standby, the ceramic thermal storage heat exchanger 22 stores heat, and the ceramic thermal storage heat exchanger 32 releases heat.

[0048] State rotation: In each cycle, only one group absorbs heat, one group releases heat, and one group is on standby to avoid heat interruption.

[0049] Compressed air parameters:

[0050] Total flow rate: 350 Nm³ / h (105 Nm³ / h through the partitioning heat exchanger, 245 Nm³ / h through the regenerative heat exchanger).

[0051] Initial temperature: 20℃.

[0052] Target reaction temperature: 900°C.

[0053] Air density: 1.293 kg / Nm³.

[0054] Specific heat capacity of air at constant pressure: c p =1.005kJ / (kg\cdotpK)

[0055] Heat exchanger performance:

[0056] Partitioning heat exchanger: preheats 30% of compressed air (105 Nm³ / h) from 20°C to 505°C, with a heat transfer capacity of 18kW.

[0057] Regenerative heat exchanger: preheats 70% of compressed air (245 Nm³ / h) from 20°C to 850°C, with a heat recovery efficiency of ≥95%.

[0058] Electric heating efficiency: η 电加热 =90%.

[0059] Energy consumption of traditional process (without heat recovery)

[0060] Energy consumption for direct electric heating of all compressed air from 20°C to 900°C:

[0061]

[0062] Mass flow m :350Nm³ / h×1.293kg / Nm³=452.55kg / h.

[0063] Temperature rise T : 900℃−20℃=880℃.

[0064] E (traditional) = 452.55 × 1.005 × 880 / (0.9 × 3600) = 113.6 kW

[0065] Energy consumption of traditional process (partitioning wall heat exchanger)

[0066] Partitioning heat exchanger path (30% flow):

[0067] Temperature after preheating: 505℃.

[0068] Temperature rise required for electric heating: 900℃−505℃=395℃.

[0069] Mass flow rate: 105Nm³ / h×1.293=135.77kg / h.

[0070] Energy consumption: E 间壁30% =135.77×1.005×395 / (0.9×3600)=16.63kW

[0071] Partitioning heat exchanger path (70% flow):

[0072] Temperature after preheating: 550℃.

[0073] Temperature rise required for electric heating: 900℃−550℃=350℃.

[0074] Mass flow rate: 245Nm³ / h×1.293=316.79kg / h.

[0075] Energy consumption: E 间壁70% =316.79×1.005×350 / (0.9×3600)=34.39kW

[0076] Total actual energy consumption: E(partition wall) = E 间壁30% +E 间壁70%=16.63+34.39=51.02kW

[0077] Actual energy consumption of the technical solution of the present invention:

[0078] Partitioning heat exchanger path (30% flow):

[0079] Temperature after preheating: 505℃.

[0080] Temperature rise required for electric heating: 900℃−505℃=395℃.

[0081] Mass flow rate: 105Nm³ / h×1.293=135.77kg / h.

[0082] Energy consumption: E 间壁 =135.77×1.005×395 / (0.9×3600)=16.63kW

[0083] Regenerative heat exchanger path (70% flow):

[0084] Temperature after preheating: 850℃.

[0085] Temperature rise required for electric heating: 900℃−850℃=50℃.

[0086] Mass flow rate: 245Nm³ / h×1.293=316.79kg / h.

[0087] Energy consumption: E 蓄热 =316.79×1.005×50 / (0.9×3600)=1.6kW

[0088] Total actual energy consumption: E(Example 1) = E 间壁 +E 蓄热 =16.63+1.6=18.23kW

[0089] Comparative analysis:

[0090] Direct energy saving value 1: ΔE = E (conventional) - E (Example 1) = 113.6kW - 18.23kW = 95.37kW

[0091] Energy saving rate 1 = ΔE / E (traditional) × 100% = 95.37 / 113.6 × 100% = 83.95%

[0092] Direct energy saving value 2: ΔE = E (partition wall) - E (Example 1) = 51.02kW - 18.23kW = 32.79kW

[0093] Energy saving rate 2 = ΔE / E (partition wall) × 100% = 32.79 / 51.02 × 100% = 64.27%

[0094] The energy storage heat exchange process (partitioning with a partitioning heat exchanger and three parallel sets of regenerative heat exchangers) saves approximately 95.37 kW of energy compared to directly discharging high-temperature nitrogen and oxygen, achieving an energy saving rate of 83.95%. Compared to using partitioning heat exchangers, it saves approximately 32.79 kW of energy, achieving an energy saving rate of 64.27%. This energy storage heat exchange process offers significant energy-saving advantages in high-temperature nitrogen and oxygen separation.

[0095] Moreover, the significance of increasing heat exchange is not only to reduce energy consumption, because hot nitrogen and hot oxygen cannot be used directly and need to be cooled to room temperature before entering the daily use stage. If there is no heat exchange, a condenser or radiator will need to be added, which will increase the cost and construction scale of the entire system. Example 2

[0096] It is basically the same as Example 1, except that:

[0097] The nitrogen gas coming out of the ceramic heat storage heat exchanger is equipped with a nitrogen content detection device during the discharge process. In the early stage of the energy storage heat exchange process, if the nitrogen purity does not meet the standard, the nitrogen is directly discharged; when the nitrogen purity meets the standard, it is collected. The specific process is as follows Figure 2 . Example 3

[0098] This embodiment is based on the overall equipment of Example 1, and supplements the valve group switching mode and automation unit:

[0099] In the first embodiment, thermocouples are respectively provided at the inlet and outlet of the three groups of ceramic thermal storage heat exchangers 12 , 22 , and 32 .

[0100] The temperature difference between the two ends of each group of heat accumulators is used to calculate the heat storage percentage η of the heat accumulator in real time; the calculation formula of η is stored in the programmable logic controller (PLC);

[0101] The calculation formula of the heat storage percentage η is:

[0102] In the endothermic state (hot nitrogen passes through the regenerator):

[0103]

[0104] In the heat release state (compressed air passes through the heat accumulator):

[0105]

[0106] in,

[0107] η is the heat storage percentage; T out is the temperature at the outlet of the heat storage device; T in is the temperature at the heat storage inlet; T targetis the target temperature of the heat accumulator, which is usually 900°C in this embodiment.

[0108] In the endothermic state: Since the inlet temperature is greater than the outlet temperature most of the time, and equal to the limit, the , to obtain a positive percentage. When η is 0, it means that the heat storage is low, and η = rises to 1, indicating that the heat storage is in a high temperature state that is almost fully loaded.

[0109] In the heat release state: η = 1 indicates that the heat storage is in a high temperature state that is almost fully loaded; when η drops to 0, it indicates that the available heat is exhausted.

[0110] Each group of heat storage devices can only be in the following three mutually exclusive states: heat release, heat absorption and standby.

[0111] That is, always satisfy:

[0112] Heat-releasing heat storage device: heat-absorbing heat storage device: standby heat storage device = 1:1:1.

[0113] like Figure 3 The switching steps of the three groups of ceramic thermal storage heat exchangers include:

[0114] During the system power-on self-test, by default, one heat accumulator is set to release heat, one heat accumulator is set to absorb heat, and one heat accumulator is set to standby. At this time, the heat accumulator that needs to release heat is preheated first. After preheating to η of 0.9, the heat accumulator that is preheated will release heat. When the heat release operation is performed for the first time, the heat accumulator that is in standby mode is preheated to η of 0.9 and then continues to standby.

[0115] The PLC collects the temperature of the heat storage inlet and outlet through thermocouples every 1 second and updates the heat storage percentage η;

[0116] The system rotates the heat storage device according to the situation of η. The rotation criteria are as follows:

[0117] When a heat accumulator is in the heat absorption role and η ≥ 0.9, or the outlet temperature is greater than 850 ° C, it is judged to be full and the PLC makes it return to standby;

[0118] When a heat accumulator is in the heat release role and η≤0.15, or the outlet temperature is lower than 100℃, it is judged that the heat is insufficient and the PLC makes it perform the heat absorption operation;

[0119] When one heat accumulator retreats from the heat absorbing state to the standby state, the other heat accumulator in the standby state performs a heat releasing operation.

[0120] Among them, when the heat absorbing heat accumulator actively retreats to standby mode, the heat releasing heat accumulator automatically switches to the heat absorbing heat accumulator; when the heat releasing heat accumulator actively switches to heat absorbing operation, the heat absorbing heat accumulator automatically retreats to standby mode.

[0121] The closed-loop system was operated for 24 hours at a rated flow rate of 350 standard cubic meters per hour and a target temperature of 900°C;

[0122] The average time it takes for the three heat accumulators to complete a full cycle is approximately 630 seconds, much longer than the 120 seconds of the simple timing mode, significantly reducing the number of mechanical actions of the three-position five-way electric butterfly valve;

[0123] The three-position, five-way electric butterfly valve, thermocouple, differential pressure transmitter, and Siemens S7-1500 programmable logic controller required for this embodiment are all available through industrial product procurement channels. Those skilled in the art can implement a continuous, efficient, and low-impact three-tower thermal storage rotation control process by following the complete steps and thresholds described above without any inference. Example 4

[0124] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0125] The preparation method of 150×150×150mm (43×43 holes) ceramic heat storage material is as follows: 70 parts of corundum, 25 parts of kaolin, 1 part of molybdenum trioxide, and 4 parts of spodumene are mixed and put into a ball mill for 5 hours; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is used for shaping, hot air drying is used for dehydration, and then the temperature is raised to 1000℃ at a rate of 10℃ / min, and then the temperature is continued to be raised to 1650℃ at a rate of 3℃ / min, and kept at 1650℃ for 30 minutes; then the temperature is naturally lowered to 1450℃ and kept at 1450℃ for 90 minutes; and naturally cooled to room temperature.

[0126] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0127] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0128] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0129] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is approximately 150×150×150 (43×43 holes).

[0130] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0131] Hot air drying is performed at 105°C for 10 h. Example 5

[0132] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0133] The preparation method of 150×150×150mm (43×43 holes) ceramic heat storage material is as follows: 70 parts of corundum, 25 parts of kaolin, 2 parts of molybdenum trioxide, and 3 parts of spodumene are mixed and put into a ball mill for 30 minutes; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is used for shaping, hot air drying is used for dehydration, and then the temperature is raised to 1000℃ at a rate of 10℃ / min, and then the temperature is continued to be raised to 1650℃ at a rate of 3℃ / min, and kept at 1650℃ for 30 minutes; then the temperature is naturally lowered to 1450℃ and kept at 1450℃ for 90 minutes; and naturally cooled to room temperature.

[0134] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0135] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0136] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0137] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is 150×150×150 (43×43 holes).

[0138] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0139] Hot air drying is performed at 105°C for 10 h. Example 6

[0140] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0141] The preparation method of 150×150×150mm (43×43 holes) ceramic heat storage material is as follows: 70 parts of corundum, 25 parts of kaolin, 3 parts of molybdenum trioxide, and 2 parts of spodumene are mixed and put into a ball mill for 30 minutes; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is used for shaping, hot air drying is used for dehydration, and then the temperature is raised to 1000℃ at a rate of 10℃ / min, and then the temperature is continued to be raised to 1650℃ at a rate of 3℃ / min, and kept at 1650℃ for 30 minutes; then the temperature is naturally lowered to 1450℃ and kept at 1450℃ for 90 minutes; and naturally cooled to room temperature.

[0142] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0143] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0144] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0145] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is 150×150×150 (43×43 holes).

[0146] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0147] Hot air drying is performed at 105°C for 10 h. Example 7

[0148] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0149] The preparation method of 150×150×150mm (43×43 holes) ceramic heat storage material is as follows: 70 parts of corundum, 25 parts of kaolin, 4 parts of molybdenum trioxide, and 1 part of spodumene are mixed and put into a ball mill for 30 minutes; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is used to set the shape, hot air drying is used to remove water, and then the temperature is raised to 1000℃ at a rate of 10℃ / min, and then the temperature is continued to be raised to 1650℃ at a rate of 3℃ / min, and kept at 1650℃ for 30 minutes; then the temperature is naturally lowered to 1450℃ and kept at 1450℃ for 90 minutes; and naturally cooled to room temperature.

[0150] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0151] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0152] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0153] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is 150×150×150 (43×43 holes).

[0154] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0155] Hot air drying is performed at 105°C for 10 h.

[0156] Comparative Example 1

[0157] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0158] The preparation method of a 150×150×150mm (43×43 holes) high-temperature resistant ceramic thermal storage body is as follows: 70 parts of corundum, 25 parts of kaolin, and 5 parts of molybdenum trioxide are mixed and placed in a ball mill for 30 minutes; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is performed to shape, hot air drying is performed to remove water, and then the temperature is raised to 1000°C at a rate of 10°C / min, and then the temperature is continued to be raised to 1650°C at a rate of 3°C / min, and kept at 1650°C for 30 minutes; then the temperature is naturally lowered to 1450°C and kept at 1450°C for 90 minutes; and naturally cooled to room temperature.

[0159] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0160] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0161] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0162] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is 150×150×150 (43×43 holes).

[0163] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0164] Hot air drying is performed at 105°C for 10 h.

[0165] Comparative Example 2

[0166] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0167] The preparation method of 150×150×150mm (43×43 holes) ceramic heat storage material is as follows: 70 parts of corundum, 25 parts of kaolin, and 5 parts of spodumene are mixed and put into a ball mill for 30 minutes; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is used to set the shape, hot air drying is used to remove water, and then the temperature is raised to 1000℃ at a rate of 10℃ / min, and then the temperature is continued to be raised to 1650℃ at a rate of 3℃ / min, and kept at 1650℃ for 30 minutes; then the temperature is naturally lowered to 1450℃ and kept at 1450℃ for 90 minutes; and naturally cooled to room temperature.

[0168] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0169] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0170] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0171] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is 150×150×150 (43×43 holes).

[0172] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0173] Hot air drying is performed at 105°C for 10 h. Example 8

[0174] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic thermal storage heat exchanger is replaced by 150×150×150mm (43×43 holes) cordierite with 150×150×150mm (43×43 holes) ceramic heat storage material.

[0175] The preparation method of 150×150×150mm (43×43 holes) ceramic heat storage material is as follows: 70 parts of corundum, 25 parts of kaolin, 3 parts of molybdenum trioxide, 2 parts of spodumene, and 0.2 parts of zinc stearate are mixed and put into a ball mill for 30 minutes; 4 parts of polyvinyl alcohol aqueous solution are added and granulated to obtain a blank; the blank is kneaded 3 times under 0.08MPa conditions, aged for 24 hours, and then extruded and cut to form honeycomb holes to obtain a ceramic blank; microwave drying is used to set the shape, hot air drying is used to remove water, and then the temperature is raised to 1000℃ at a rate of 10℃ / min, and then the temperature is continued to be raised to 1650℃ at a rate of 3℃ / min, and kept at 1650℃ for 30 minutes; then the temperature is naturally reduced to 1450℃ and kept at 1450℃ for 90 minutes; and it is naturally cooled to room temperature.

[0176] Ball milling parameters: ball-to-material ratio of 10:1, zirconia balls (diameter 10 mm), speed 500 rpm, ball milling time 5 h;

[0177] The concentration of the polyvinyl alcohol aqueous solution is 5wt%;

[0178] Each mud kneading time is 10 minutes and the speed is 50 rpm;

[0179] After extrusion, the ceramic body is cut into blocks measuring 165×165×165mm, and then 43×43 holes are cut into the blocks, with a hole width of 3×3mm. After drying, sintering, and natural cooling, the size of the ceramic body is 150×150×150 (43×43 holes).

[0180] Microwave drying was performed at 1000W and 2450MHz for 10 min;

[0181] Hot air drying is performed at 105°C for 10 h.

[0182] Test Example 1

[0183] In the energy storage heat exchange system of the present invention, the thermal storage material undergoes frequent cycles of high temperature and rapid cooling, resulting in dramatic temperature gradients. Due to their brittleness and high coefficient of thermal expansion, ceramic materials are susceptible to thermal stress accumulation under rapid temperature changes, leading to crack initiation and propagation, ultimately causing material fracture or structural collapse. Thermal shock testing can quantify parameters such as the material's strength loss rate and crack propagation after thermal shock, directly reflecting its durability under actual operating conditions.

[0184] Thermal shock resistance test

[0185] The test was conducted with reference to Method 3 - Air Quenching Method in GB / T 30873-2014 Test Method for Thermal Shock Resistance of Refractory Materials, with some conditions / parameters adjusted appropriately: the test temperature was changed to 1100°C, the three-point bending stress test was not performed during the test, and after 30 thermal shock cycles, the flexural strength of the samples was tested using an electronic universal testing machine (Model WDW100, loading speed 0.5 mm / min).

[0186] The test samples were prepared by referring to the preparation methods in the examples / control examples. It should be noted that after extrusion molding, they were cut into blocks of 125 mm × 70 mm × 70 mm without cutting honeycomb holes; the final sample size was approximately 114 mm × 70 mm × 70 mm.

[0187] Bending strength loss rate S σ =( σ 0 - σ 30 ) / σ 0 ×100%

[0188] σ 0 is the original bending strength, σ 30 It is the bending strength after 30 thermal shock tests.

[0189] Table 4 Thermal shock resistance test

[0190]

[0191] Compared with the cordierite of Example 1, the high-temperature resistant ceramic thermal accumulators of Examples 4-8 have better thermal shock resistance. This is because the high-temperature resistant ceramic thermal accumulators of Examples 4-8 are made of a corundum-based material, which is more stable at high temperatures than cordierite ceramics, and their thermal shock resistance is less attenuated with temperature fluctuations.

[0192] Examples 4-7 investigate the synergistic effects of molybdenum trioxide and spodumene. A 3:2 ratio of molybdenum trioxide to spodumene demonstrates optimal thermal shock resistance in high-temperature ceramic thermal storage materials. Excessive molybdenum trioxide content can lead to an excess of glassy phase, weakening high-temperature strength; excessive spodumene content can introduce excessive low-melting-point phases, reducing the thermal stability of the material. Molybdenum trioxide improves thermal conductivity (by promoting heat transfer at grain boundaries), while spodumene's low thermal expansion suppresses thermal stress accumulation. A 3:2 ratio of molybdenum trioxide to spodumene achieves an optimal balance between thermal conductivity and thermal expansion, maximizing crack propagation resistance and forming a more uniform multiphase structure.

[0193] Example 8 adds zinc stearate to the formula instead of conventional stearic acid and sodium stearate. The main consideration is that zinc stearate significantly improves the high temperature resistance, structural density, and thermal shock resistance of the ceramic thermal accumulator through its high-temperature stable decomposition product ZnO, optimized sintering behavior, and processing lubrication effect, while avoiding the potential drawbacks of sodium ion introduction. The above describes the preferred embodiments of the present invention in detail.

[0194] Test Example 2

[0195] Creep resistance, the ability of ceramic materials to resist slow plastic deformation under high temperatures and constant stress, is crucial for thermal storage materials subject to long-term high-temperature operation. During long-term high-temperature service, creep can cause dimensional changes, strength loss, and even fracture. Creep resistance directly impacts the service life and safety of thermal storage systems.

[0196] Creep resistance test

[0197] The experiment was carried out using the GB / T 5073-2022 refractory material compressive creep test method.

[0198] The test samples were prepared by referring to the preparation methods in the examples / control examples. It should be noted that after extrusion molding, they were cut into cylinders with a diameter and height of 55 mm and a center hole with a diameter of 14 mm. The final sample size was approximately a cylinder with a diameter and height of 55 mm and a hole in the center (diameter of about 12-13 mm).

[0199] A cylinder with a diameter and height of 50 ± 0.5 mm and a central through hole (12-13 mm in diameter) was placed in a furnace as specified. A load was applied to the specimen at room temperature. The specimen was heated at a rate of 10°C / min below 1000°C and 4-5°C / min above 1000°C. After reaching the test temperature (1500°C), the specimen was held at that temperature for 50 hours. The load was 0.2 MPa. The creep rate was calculated using the following formula:

[0200] P(%)=(L 50 -L0) / L i ×100%

[0201] Where: P-creep rate; L i -Original height of the sample, mm; L o -Height of the sample at the beginning of constant temperature (mm); L 50 -Height of the sample after 50 hours of constant temperature, mm.

[0202] Table 5 Creep resistance

[0203]

[0204] Cordierite ceramics have relatively weak high-temperature performance and poor creep resistance. However, Examples 4-8 utilize a corundum-spodumene-molybdenum trioxide composite system, with corundum as the main component. This system combines the high-temperature stability of corundum with the fluxing effects of molybdenum trioxide and spodumene to form a denser grain boundary structure, effectively suppressing grain boundary sliding at high temperatures and significantly improving creep resistance.

[0205] Among the high-temperature resistant ceramic heat accumulators of Examples 4-8, the high-temperature resistant ceramic heat accumulator of Example 6 is the best. The possible reason is that when the ratio of molybdenum trioxide and spodumene is 3:2, the two form a more stable composite phase. Increasing the molybdenum trioxide content enhances the grain boundary pinning effect, but excessive content may lead to the formation of brittle phases at the grain boundaries, which in turn reduces the strength. An appropriate reduction in spodumene balances the amount of liquid phase generated, avoiding excessive liquid phase leading to grain boundary weakening. Experimental data show that the creep rate of Example 6 is the lowest, indicating that when the ratio of molybdenum trioxide and spodumene is 3:2, the best balance is achieved between suppressing grain boundary slip and optimizing density.

[0206] It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solution that can be derived by those skilled in the art based on the concepts of the present invention through logical analysis, reasoning, or limited experimentation based on the existing technology should be within the scope of protection defined by the claims.

Claims

1. Energy storage heat exchange process for high temperature nitrogen and oxygen separation, characterized by: The high-temperature nitrogen separated from the compressed air by the high-temperature nitrogen and oxygen separator containing the perovskite ceramic gas separation membrane is then heat-exchanged with the compressed air by three sets of parallel ceramic regenerative heat exchangers, achieving continuous and uninterrupted high-temperature nitrogen and oxygen separation. Three groups of ceramic thermal storage heat exchangers are arranged in parallel. During the uninterrupted high-temperature nitrogen and oxygen separation, one group of ceramic thermal storage heat exchangers is used to release heat to heat the compressed air; one group of ceramic thermal storage heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; and one group of ceramic thermal storage heat exchangers absorbs the heat brought by the high-temperature nitrogen and is kept in reserve. The three groups rotate to achieve uninterrupted high-temperature nitrogen and oxygen separation.

2. The energy storage heat exchange process for high-temperature nitrogen and oxygen separation according to claim 1, characterized in that: The compressed air coming out of the ceramic regenerative heat exchanger is electrically heated to a reaction temperature of 500°C-1100°C.

3. The energy storage heat exchange process for high-temperature nitrogen and oxygen separation according to claim 2, characterized in that: 20%-30% of the compressed air passes through the partition wall heat exchanger and is electrically heated to the reaction temperature of 500℃-1100℃; 70%-80% of the compressed air passes through the ceramic regenerative heat exchanger and is electrically heated to a reaction temperature of 500℃-1100℃; The compressed air is 100% after being combined and enters the high-temperature nitrogen and oxygen separator for nitrogen and oxygen separation at 500℃-1100℃; The separated high-temperature oxygen is used to heat the compressed air through a partitioning heat exchanger, and then electrically heated to the reaction temperature of 500°C-1100°C; The separated high-temperature nitrogen passes through a ceramic thermal storage heat exchanger and stores heat in it; three groups of ceramic thermal storage heat exchangers are arranged in parallel, one group of ceramic thermal storage heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; one group of ceramic thermal storage heat exchangers absorbs the heat brought by the high-temperature nitrogen and is reserved for use; the three groups rotate to achieve uninterrupted high-temperature nitrogen and oxygen separation.

4. The energy storage heat exchange process for high-temperature nitrogen and oxygen separation according to claim 3, characterized in that: The ceramic heat storage material used in the ceramic thermal storage heat exchanger is a honeycomb structure or a porous structure.

5. The energy storage heat exchange process for high-temperature nitrogen and oxygen separation according to claim 3, characterized in that: The high-temperature nitrogen and oxygen separator adopts a perovskite ceramic gas separation membrane.

6. The energy storage heat exchange process for high-temperature nitrogen and oxygen separation according to claim 4, characterized in that: The ceramic heat storage material is cordierite.

7. The energy storage heat exchange process for high-temperature nitrogen and oxygen separation according to claim 4, characterized in that: The preparation method of the ceramic heat storage material comprises the following steps: uniformly mixing corundum, kaolin, molybdenum trioxide and spodumene, and then ball milling the mixture for 2-6 hours; adding a polyvinyl alcohol aqueous solution, and granulating the mixture to obtain a blank; kneading the blank, aging, extruding and cutting honeycomb holes to obtain a ceramic blank; drying and removing water, heating the blank to 900-1000° C. at a rate of 10° C. / min, then continuously heating the blank to 1500-1650° C. at a rate of 3° C. / min, and maintaining the temperature at 1600-1650° C. for 20-40 minutes; then naturally cooling the blank to 1300-1450° C. and maintaining the temperature at 1300-1450° C. for 80-120 minutes; and naturally cooling the blank to room temperature to obtain the ceramic blank.

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