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

Abstract

The invention discloses an energy storage heat exchange process for high-temperature nitrogen-oxygen separation. Compressed air is heated to 500-1100 DEG C and then enters a high-temperature nitrogen-oxygen separator containing a perovskite ceramic gas separation membrane; separated heat N2 / O2 is subjected to heat storage through a ceramic heat storage type heat exchanger and is used for heating compressed air, so that heat collection and recycling are realized, and the energy consumption problem of the perovskite ceramic gas separation membrane in practical application is effectively improved; and a ceramic heat storage material of the ceramic heat storage type heat exchanger is improved to better adapt to the rapid cooling and rapid heating working condition.

Description

Technical Field

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

[0002] Perovskite ceramic gas separation membranes show significant advantages in the field of nitrogen-oxygen separation. Based on the oxygen ion-electron mixed conduction characteristics, at high temperatures of 500-1100°C, oxygen-nitrogen separation is achieved by utilizing the oxygen concentration gradient on both sides of the membrane, with 100% oxygen selective permeability. In the prior art, ceramic membranes can produce more than 99% pure nitrogen and pure oxygen in experiments. Due to its high temperature resistance, strong chemical stability, and high mechanical strength, it can work stably in complex environments such as high temperatures and corrosive gases, with high separation efficiency, and has application prospects in scenarios such as chemical production.

[0003] However, perovskite ceramic gas separation membranes also have deficiencies. On the one hand, the preparation cost is high. The complex preparation process and special equipment requirements, such as high-temperature sintering, increase the cost and limit its large-scale application. On the other hand, its flux is relatively lower than that of organic membranes. To process the same gas volume, a larger area of membrane components is required, increasing the equipment volume and cost. At the same time, its working conditions are harsh, and the high-temperature operation consumes too much energy, seriously restricting its popularization in the actual application of nitrogen-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-oxygen separation, which can effectively improve the energy consumption problem of perovskite ceramic gas separation membranes in actual applications, and also solves the durability problem under the conditions of rapid cooling and heating by improving the ceramic heat storage material of the ceramic regenerative heat exchanger.

[0005] To achieve the above object, the present invention provides an energy storage heat exchange process for high-temperature nitrogen-oxygen separation, including: high-temperature nitrogen separated from high-temperature nitrogen-oxygen is used to exchange heat with compressed air through three groups of juxtaposed ceramic regenerative heat exchangers to achieve continuous and uninterrupted high-temperature nitrogen-oxygen separation.

[0006] Further, in the continuous and uninterrupted high-temperature nitrogen-oxygen separation of the three groups of juxtaposed ceramic regenerative heat exchangers, one group of ceramic regenerative heat exchangers is used to release heat to heat the compressed air; one group of ceramic regenerative heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; one group of ceramic regenerative heat exchangers is on standby after absorbing the heat brought by the high-temperature nitrogen; the three groups rotate to achieve continuous and uninterrupted high-temperature nitrogen-oxygen separation.

[0007] Further, 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 high-temperature nitrogen and oxygen is used to heat the compressed air through a shell-and-tube 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 as follows: 20% - 30% of the compressed air is electrically heated to 500°C - 1100°C after passing through a shell-and-tube heat exchanger; 70% - 80% of the compressed air is electrically heated to 500°C - 1100°C after passing through a ceramic regenerative heat exchanger; The compressed air is combined to 100% and enters a high-temperature nitrogen and oxygen separator for nitrogen and oxygen separation at 500°C - 1100°C; The separated high-temperature oxygen is used to heat the compressed air through a shell-and-tube heat exchanger, and then electrically heated to the 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 the reaction temperature of 500°C - 1100°C.

[0010] The separated high-temperature nitrogen passes through a ceramic regenerative heat exchanger and stores heat therein; three groups of ceramic regenerative heat exchangers are arranged in parallel, one group of ceramic regenerative heat exchangers is used to absorb the heat brought by high-temperature nitrogen; one group of ceramic regenerative heat exchangers is on standby after absorbing the heat brought by high-temperature nitrogen; the three groups rotate to achieve continuous high-temperature nitrogen and oxygen separation.

[0011] Furthermore, the regenerator used in the ceramic regenerative heat exchanger is a ceramic heat storage material with a honeycomb structure or a porous structure. The use of a honeycomb structure or a porous structure for the ceramic heat storage material can increase the surface area and optimize the heat exchange efficiency. The ceramic heat storage material has many advantages, such as high melting point, high heat capacity, good chemical stability, adjustable thermal conductivity, good high-temperature resistance, high pressure resistance, environmental protection, non-toxicity, and long service life, and can be well applied to the energy storage heat exchange process of high-temperature nitrogen and oxygen separation in the present invention. The ceramic heat storage material is cordierite; more specifically, the ceramic heat storage material is 150×150×150mm (43×43 holes) cordierite.

[0012] Furthermore, the high-temperature nitrogen and oxygen separator uses a perovskite ceramic gas separation membrane. When the oxygen concentration difference gradient exists inside and outside the membrane at a temperature higher than 500 - 1100°C, the oxygen transfer process can be continuously carried out.

[0013] It should be noted that N2 accounts for 78% and O2 accounts for 21% in the air. More hot N2 is separated by the high-temperature nitrogen-oxygen separator than hot O2. Considering the relatively small flow rate of hot O2, the ceramic regenerative heat exchanger has higher heat exchange efficiency, high pressure resistance, and cost control of the entire system compared to the shell-and-tube heat exchanger. The present invention sets three groups of ceramic regenerative heat exchangers to absorb and store the heat brought by hot N2 and heat 70%-80% of the compressed air, and sets a shell-and-tube heat exchanger to heat 20%-30% of the compressed air through hot O2. When the flow rate of hot O2 is adjusted to the large operating condition, a ceramic regenerative heat exchanger can also be selected.

[0014] Furthermore, a nitrogen content detection device is added during the discharge process of the nitrogen coming out of the ceramic regenerative heat exchanger. In the early stage of the energy storage heat exchange process, when the nitrogen purity does not meet the standard, the nitrogen is directly discharged; when the nitrogen purity meets the standard, it is collected.

[0015] In the energy storage heat exchange process of high-temperature nitrogen-oxygen separation of the present invention, the compressed air is heated to 500-1100°C and then enters a high-temperature nitrogen-oxygen separator containing a perovskite ceramic gas separation membrane; the separated hot N2 stores heat through three groups of ceramic regenerative heat exchangers and heats the compressed air, realizing the collection and recycling of heat, and effectively improving the energy consumption problem of the perovskite ceramic gas separation membrane in practical applications.

[0016] On the other hand, considering the fast heat exchange speed of the ceramic regenerative heat exchanger, which requires rapid cooling and heating, the durability of the cordierite ceramic material is not sufficient to support the system for longer uninterrupted operation; it is necessary to further improve the thermal shock resistance of the regenerator in the ceramic regenerative heat exchanger. The present invention also provides a self-made ceramic heat storage material.

[0017] Furthermore, the preparation method of the ceramic heat storage material is as follows: mix corundum, kaolin, molybdenum trioxide, and spodumene evenly and ball mill for 2-6 h; add an aqueous solution of polyvinyl alcohol and granulate to obtain a blank; the blank is subjected to clay kneading, aging, extrusion molding, and cutting honeycomb holes to obtain a ceramic blank; after drying and removing water, it is heated to 900-1000°C at a rate of 10°C / min and then continued to be heated to 1500-1650°C at a rate of 3°C / min, and held at 1600-1650°C for 20-40 min; then it is naturally cooled to 1300-1450°C and held at 1300-1450°C for 80-120 min; and naturally cooled to room temperature to obtain the product.

[0018] The preparation method of the ceramic heat storage material is as follows: by weight, 70-75 parts of corundum, 21-25 parts of kaolin, 1-4 parts of molybdenum trioxide, and 1-4 parts of spodumene are mixed and then put into a ball mill tank for ball milling for 2-6 h; 1-6 parts of an aqueous polyvinyl alcohol solution are added, and granulation is carried out to obtain a blank; the blank is kneaded and aged under vacuum conditions, and then extruded and formed, and honeycomb holes are cut to obtain a ceramic blank; after microwave drying and shaping and hot air drying to remove water, the temperature is raised to 900-1000 °C at a rate of 10 °C / min, and then continued to be raised to 1500-1650 °C at a rate of 3 °C / min, and kept warm at 1600-1650 °C for 20-40 min; then it is naturally cooled to 1300-1450 °C and kept warm at 1300-1450 °C for 80-120 min; it is naturally cooled to room temperature to obtain the product.

[0019] Ball milling parameters: the ball-to-material ratio is 10:1 (mass ratio), zirconia balls (diameter 10 mm), the rotation speed is 200-600 rpm, and the ball milling time is 4-8 h.

[0020] The concentration of the aqueous polyvinyl alcohol solution is 2-25 wt%.

[0021] The kneading time each time is 4-12 min and the rotation speed is 20-100 rpm.

[0022] Using a corundum-based ceramic material as a high-temperature ceramic heat storage body is more stable at high temperatures compared with cordierite ceramics, and the attenuation of thermal shock resistance with temperature fluctuations is smaller, having better thermal shock resistance and being able to better adapt to the rapid cooling and heating conditions of the present invention. Description of the Drawings

[0023] Figure 1 is the process flow diagram of the energy storage heat exchange for high-temperature nitrogen-oxygen separation; Figure 2 is the process flow diagram of adding a nitrogen content detection device during the discharge of nitrogen coming out of the ceramic regenerative heat exchanger; Figure 3 is the switching process flow diagram of three groups of ceramic regenerative heat exchangers in Example 3; Reference numerals in the drawings: 11, 15, 21, 25, 31, 35, 14, 16, 24, 26, 34, 36 are valves, 12, 22, 32 are ceramic regenerative heat exchangers, 13, 23, 33, 5 are electric heaters, 4 is a high-temperature nitrogen-oxygen separator with a perovskite ceramic gas separation membrane, 6 is a shell-and-tube heat exchanger, 7 is a check valve, 8 is a check valve. Detailed Embodiments Example 1

[0024] The energy storage heat exchange process for high-temperature nitrogen-oxygen separation includes: The flow rate is 105 Nm 3Compressed air at 20°C with a flow rate of / h is heated to 900°C by an electric heater 5 after passing through a shell-and-tube heat exchanger 6; The compressed air with a flow rate of 245 Nm 3 / h and at 20°C is heated to 900°C by an electric heater 13 after passing through a ceramic regenerative heat exchanger 12; 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; After merging the above compressed air, it enters a high-temperature nitrogen-oxygen separator 4 for nitrogen-oxygen separation; The separated high-temperature oxygen heats the compressed air through the shell-and-tube heat exchanger 6, and then is heated to 900°C by an electric heater, realizing the recycling of heat; The separated high-temperature nitrogen stores heat in a ceramic regenerative heat exchanger 32 after passing through it; After the ceramic regenerative heat exchanger 32 stores heat for 120 s, valves 36 and 35 are closed, and valves 26 and 25 are opened, so that the separated high-temperature nitrogen stores heat in a ceramic regenerative heat exchanger 22 after passing through it; After the ceramic regenerative heat exchanger 22 stores heat for 120 s, valves 26, 25, 11, and 14 are closed, and valves 31 and 34 are opened. Compressed air at 20°C with a flow rate of 245 Nm 3 / h is heated to 900°C by an electric heater 33 after passing through a ceramic regenerative heat exchanger 32. Three sets of ceramic regenerative heat exchangers are arranged in parallel. One set of ceramic regenerative heat exchanger is used to heat the compressed air with the heat absorbed from the high-temperature nitrogen (i.e., releasing heat); one set of ceramic regenerative heat exchanger stores the heat from the high-temperature nitrogen for standby (i.e., absorbing heat); one set of ceramic regenerative heat exchanger is in the standby state; The three sets rotate to achieve continuous high-temperature nitrogen-oxygen separation.

[0025] Table 1 Stable operating parameters of the shell-and-tube heat exchanger

[0026] Table 2 Stable operating parameters of the inlet of the ceramic regenerative heat exchanger

[0027] Table 3 Stable operating parameters of the outlet of the ceramic regenerative heat exchanger

[0028] Stable operating state: 120-second fixed cycle: 0 - 120 seconds: Valves 11, 14, 35, 36 are open, and valves 15, 16, 21, 24, 25, 26, 31, 34 are closed; At this time, the ceramic regenerative heat exchanger 12 releases heat, the ceramic regenerative heat exchanger 22 is on standby, and the ceramic regenerative heat exchanger 32 stores heat.

[0029] 120 - 240 seconds: Valves 15, 16, 21, 24 are open, and valves 11, 14, 25, 26, 31, 34, 35, 36 are closed; At this time, the ceramic regenerative heat exchanger 12 stores heat, the ceramic regenerative heat exchanger 22 releases heat, and the ceramic regenerative heat exchanger 32 is on standby.

[0030] 240 - 360 seconds: Valves 25, 26, 31, 34 are open, and valves 11, 14, 15, 16, 21, 24, 35, 36 are closed; At this time, the ceramic regenerative heat exchanger 12 is on standby, the ceramic regenerative heat exchanger 22 stores heat, and the ceramic regenerative heat exchanger 32 releases heat.

[0031] State rotation: Only one group absorbs heat, one group releases heat, and one group is on standby in each cycle to avoid heat interruption.

[0032] Compressed air parameters: Total flow rate: 350 Nm³ / h (105 Nm³ / h passes through the shell-and-tube heat exchanger, and 245 Nm³ / h passes through the regenerative heat exchanger).

[0033] Initial temperature: 20°C.

[0034] Target reaction temperature: 900°C.

[0035] Air density: 1.293 kg / Nm³.

[0036] Specific heat capacity of air at constant pressure: c p = 1.005 kJ / (kg·K) Heat exchanger performance: Shell-and-tube heat exchanger: Preheats 30% of the compressed air (105 Nm³ / h) from 20°C to 505°C, and the heat transfer amount is 18 kW.

[0037] Regenerative heat exchanger: Preheats 70% of the compressed air (245 Nm³ / h) from 20°C to 850°C, and the heat recovery efficiency ≥ 95%.

[0038] Electric heating efficiency: η 电加热 = 90%.

[0039] Energy consumption of traditional process (without heat recovery)

[0040] Energy consumption for directly electrically heating all compressed air from 20°C to 900°C:

[0041] Mass flow rate m : 350 Nm³ / h × 1.293 kg / Nm³ = 452.55 kg / h.

[0042] Temperature rise Δ T : 900 °C - 20 °C = 880 °C.

[0043] E (traditional) = 452.55 × 1.005 × 880 / (0.9 × 3600) = 113.6 kW Energy consumption of traditional process (shell-and-tube heat exchanger)

[0044] Path of shell-and-tube heat exchanger (30% flow rate): Temperature after preheating: 505 °C.

[0045] Temperature rise required for electric heating: 900 °C - 505 °C = 395 °C.

[0046] Mass flow rate: 105 Nm³ / h × 1.293 = 135.77 kg / h.

[0047] Energy consumption: E 间壁30% = 135.77 × 1.005 × 395 / (0.9 × 3600) = 16.63 kW Path of shell-and-tube heat exchanger (70% flow rate): Temperature after preheating: 550 °C.

[0048] Temperature rise required for electric heating: 900 °C - 550 °C = 350 °C.

[0049] Mass flow rate: 245 Nm³ / h × 1.293 = 316.79 kg / h.

[0050] Energy consumption: E 间壁70% = 316.79 × 1.005 × 350 / (0.9 × 3600) = 34.39 kW Total actual energy consumption: E (shell-and-tube) = E 间壁30% + E 间壁70% = 16.63 + 34.39 = 51.02 kW Actual energy consumption of the technical solution of the present invention:

[0051] Path of shell-and-tube heat exchanger (30% flow rate): Temperature after preheating: 505 °C.

[0052] Temperature rise required for electric heating: 900 °C - 505 °C = 395 °C.

[0053] Mass flow rate: 105 Nm³ / h × 1.293 = 135.77 kg / h.

[0054] Energy consumption: E 间壁 = 135.77×1.005×395 / (0.9×3600) = 16.63 kW Regenerative heat exchanger path (70% flow rate): Temperature after preheating: 850 °C

[0055] Temperature rise by electric heating required: 900 °C - 850 °C = 50 °C

[0056] Mass flow rate: 245 Nm³ / h × 1.293 = 316.79 kg / h

[0057] Energy consumption: E 蓄热 = 316.79×1.005×50 / (0.9×3600) = 1.6 kW Total actual energy consumption: E (Example 1) = E 间壁 + E 蓄热 = 16.63 + 1.6 = 18.23 kW Comparative analysis: Direct energy saving value 1: ΔE = E (traditional) - E (Example 1) = 113.6 kW - 18.23 kW = 95.37 kW Energy saving rate 1 = ΔE / E (traditional) × 100% = 95.37 / 113.6 × 100% = 83.95% Direct energy saving value 2: ΔE = E (partition wall) - E (Example 1) = 51.02 kW - 18.23 kW = 32.79 kW Energy saving rate 2 = ΔE / E (partition wall) × 100% = 32.79 / 51.02 × 100% = 64.27% Through the energy storage heat exchange process (partition wall type + three groups of parallel regenerative heat exchangers), compared with directly discharging high-temperature nitrogen and oxygen, the energy consumption can be saved by about 95.37 kW, and the energy saving rate reaches 83.95%; compared with using a partition wall heat exchanger, the energy consumption can be saved by about 32.79 kW, and the energy saving rate reaches 64.27%. The energy storage heat exchange process of the present invention has significant energy saving advantages in high-temperature nitrogen-oxygen separation.

[0058] Moreover, the significance of increasing heat exchange lies not only in reducing energy consumption. Since hot nitrogen and hot oxygen cannot be directly used and need to be cooled to room temperature to enter the daily use stage, without heat exchange, condensers or radiators need to be added, which will increase the overall system cost and construction scale. Example 2

[0059] It is basically the same as Example 1, with the only difference being that: During the discharge process of the nitrogen gas coming out of the ceramic regenerative heat exchanger, a nitrogen content detection device is added. In the early stage of the energy storage heat exchange process, when the nitrogen purity does not meet the standard, the nitrogen gas is directly discharged; when the nitrogen purity meets the standard, it is collected. The specific process is as Figure 2 。 Example 3

[0060] Based on the overall equipment of Example 1, this example supplements the valve group switching method and the automation unit: Thermocouples are added at the inlets and outlets of the three groups of the ceramic regenerative heat exchangers 12, 22, and 32 in the first example respectively.

[0061] The temperature difference at both ends of each regenerator is used to calculate the heat storage percentage η of the regenerator in real time; the calculation formula of η is stored in the programmable logic controller PLC; The calculation formula of the heat storage percentage η is: During the endothermic state (hot nitrogen gas passes through the regenerator):

[0062] During the exothermic state (compressed air passes through the regenerator):

[0063] Among them, η is the heat storage percentage; T out is the temperature at the outlet of the regenerator; T in is the temperature at the inlet of the regenerator; T target is the target temperature of the regenerator, which is usually 900 °C in this example.

[0064] During the endothermic state: Since the inlet temperature is greater than the outlet temperature most of the time and is equal at the limit, so is used to obtain a positive percentage. When η is 0, it indicates that the heat storage of the regenerator is low, and when η rises to 1, it indicates that the regenerator is in a high-temperature state close to full load.

[0065] During the exothermic state: Among them, η = 1 indicates that the regenerator is in a high-temperature state close to full load; when η drops to 0, it indicates that the available heat has been exhausted.

[0066] Each group of regenerators can only be in the following three mutually exclusive states: exothermic, endothermic, and standby.

[0067] That is, it always satisfies: Exothermic regenerator: Endothermic regenerator: Standby regenerator = 1:1:1.

[0068] Such as Figure 3 The switching steps of the three groups of the ceramic regenerative heat exchangers include: The system performs a power-on self-check. By default, one heat accumulator is set to heat release, one heat accumulator is set to heat absorption, and one heat accumulator is set to standby. At this time, preheating is first performed on the heat accumulator that needs to execute heat release. After the heat accumulator is preheated to η = 0.9, the heat release operation is performed. When the heat release operation is performed for the first time, the heat accumulator that performs the standby operation is preheated to η = 0.9 and then continues to standby; The PLC collects the temperatures at the inlet and outlet of the heat accumulator through a thermocouple every 1 s and updates the heat storage percentage η; The system rotates the heat accumulators according to the situation of η. The rotation criterion is as follows: 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 determined to be full, and the PLC commands it to retreat to standby; When a heat accumulator is in the heat release role and η≤0.15, or the outlet temperature has dropped below 100 °C, it is determined that the heat is insufficient, and the PLC commands it to perform the heat absorption operation; When a heat accumulator retreats from the heat absorption state to the standby state, another heat accumulator in the standby state performs the heat release operation.

[0069] Among them, when the heat absorption heat accumulator actively retreats to standby, the heat release heat accumulator automatically switches to the heat absorption heat accumulator; when the heat release heat accumulator actively switches to the heat absorption operation, the heat absorption heat accumulator automatically retreats to standby.

[0070] Under the conditions of a rated flow rate of 350 standard cubic meters per hour and a target temperature of 900 °C, the closed-loop system operates for 24 hours; The average time for each complete role cycle of the three heat accumulators is about 630 seconds, which is much higher than 120 seconds in the simple timing mode, significantly reducing the number of mechanical actions of the five-port three-position electric butterfly valve; The five-port three-position electric butterfly valve, thermocouple, differential pressure transmitter, and Siemens S7-1500 programmable logic controller required in this embodiment can all be obtained through industrial product procurement channels. Those skilled in the art can implement the continuous, efficient, and low-impact three-tower heat storage rotation control process without any reference inference according to the above complete steps and thresholds. Embodiment 4

[0071] It is basically the same as Embodiment 1, except that the heat storage body in the ceramic regenerative heat exchanger is replaced with a 150×150×150 mm (43×43 holes) ceramic heat storage material instead of 150×150×150 mm (43×43 holes) cordierite.

[0072] The preparation method of the 150×150×150 mm (43×43 holes) ceramic heat storage material is as follows: Mix 70 parts of corundum, 25 parts of kaolin, 1 part of molybdenum trioxide, and 4 parts of spodumene, then put them into a ball mill jar and ball mill for 5 h; add 4 parts of an aqueous solution of polyvinyl alcohol, and granulate to obtain a blank; under the condition of 0.08 MPa, knead the blank 3 times, let it age for 24 h, then form honeycomb holes through extrusion molding and cutting to obtain a ceramic blank; after microwave drying and shaping, and hot air drying to remove water, heat it at a rate of 10 °C / min to 1000 °C, then continue to heat it at a rate of 3 °C / min to 1650 °C, and keep it at 1650 °C for 30 min; then cool it naturally to 1450 °C and keep it at 1450 °C for 90 min; cool it naturally to room temperature to obtain the product.

[0073] Ball milling parameters: The ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the aqueous solution of polyvinyl alcohol is 5 wt%; The kneading time for each time is 10 min and the rotation speed is 50 rpm; After extrusion molding, cut it into blocks of 165×165×165 mm, and then cut out 43×43 holes with a hole width of 3×3 mm. After the ceramic blank undergoes drying, sintering, and natural cooling, the size is approximately 150×150×150 (43×43 holes); Microwave drying and shaping is carried out at 1000 W and 2450 MHz for 10 min; Hot air drying is carried out at 105 °C for 10 h. Example 5

[0074] It is basically the same as Example 1, with the only difference being that the heat storage body in the ceramic regenerative heat exchanger is replaced by the 150×150×150 mm (43×43 holes) ceramic heat storage material from the 150×150×150 mm (43×43 holes) cordierite.

[0075] The preparation method of the 150×150×150 mm (43×43 holes) ceramic heat storage material is as follows: Mix 70 parts of corundum, 25 parts of kaolin, 2 parts of molybdenum trioxide, and 3 parts of spodumene, then put them into a ball mill jar and ball mill for 30 min; add 4 parts of an aqueous solution of polyvinyl alcohol, and granulate to obtain a blank; under the condition of 0.08 MPa, knead the blank 3 times, let it age for 24 h, then form honeycomb holes through extrusion molding and cutting to obtain a ceramic blank; after microwave drying and shaping, and hot air drying to remove water, heat it at a rate of 10 °C / min to 1000 °C, then continue to heat it at a rate of 3 °C / min to 1650 °C, and keep it at 1650 °C for 30 min; then cool it naturally to 1450 °C and keep it at 1450 °C for 90 min; cool it naturally to room temperature to obtain the product.

[0076] Ball milling parameters: ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the polyvinyl alcohol aqueous solution is 5 wt%; Each time the clay kneading time is 10 min and the rotation speed is 50 rpm; After extrusion molding, it is cut into blocks of 165×165×165 mm, and then 43×43 holes are cut, with a hole width of 3×3 mm. After the ceramic blank is dried, sintered, and naturally cooled, the size is 150×150×150 (43×43 holes); Microwave drying and shaping is carried out at 1000 W and 2450 MHz for 10 min; Hot air drying is carried out at 105 °C for 10 h. Example 6

[0077] It is basically the same as Example 1, the only difference being that: the heat storage body in the ceramic regenerative heat exchanger is replaced by a 150×150×150 mm (43×43 holes) ceramic heat storage material from a 150×150×150 mm (43×43 holes) cordierite.

[0078] The preparation method of the 150×150×150 mm (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 then put into a ball milling tank for ball milling for 30 min; 4 parts of polyvinyl alcohol aqueous solution are added, and the blank is obtained through granulation; the blank is kneaded 3 times under the condition of 0.08 MPa and aged for 24 h, and then honeycomb holes are formed through extrusion molding and cutting to obtain a ceramic blank; after microwave drying and shaping and hot air drying to remove water, it is heated to 1000 °C at a rate of 10 °C / min and then continued to be heated to 1650 °C at a rate of 3 °C / min, and kept at 1650 °C for 30 min; then it is naturally cooled to 1450 °C and kept at 1450 °C for 90 min; and naturally cooled to room temperature to obtain it.

[0079] Ball milling parameters: ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the polyvinyl alcohol aqueous solution is 5 wt%; Each time the clay kneading time is 10 min and the rotation speed is 50 rpm; After extrusion molding, it is cut into blocks of 165×165×165 mm, and then 43×43 holes are cut, with a hole width of 3×3 mm. After the ceramic blank is dried, sintered, and naturally cooled, the size is 150×150×150 (43×43 holes); Microwave drying and shaping is carried out at 1000 W and 2450 MHz for 10 min; Hot air drying is carried out at 105 °C for 10 h. Example 7

[0080] It is basically the same as Example 1, except that: the heat storage body in the ceramic regenerative heat exchanger is replaced by a 150×150×150 mm (43×43 holes) ceramic heat storage material from a 150×150×150 mm (43×43 holes) cordierite.

[0081] The preparation method of the 150×150×150 mm (43×43 holes) ceramic heat storage material is as follows: Mix 70 parts of corundum, 25 parts of kaolin, 4 parts of molybdenum trioxide, and 1 part of spodumene and put them into a ball mill jar for ball milling for 30 min; add 4 parts of polyvinyl alcohol aqueous solution, and granulate to obtain a blank; knead the blank 3 times under the condition of 0.08 MPa and age for 24 h, then form honeycomb holes by extrusion molding and cutting to obtain a ceramic blank; after microwave drying and shaping and hot air drying to remove water, heat it up to 1000 °C at a rate of 10 °C / min and then continue to heat it up to 1650 °C at a rate of 3 °C / min, and keep it at 1650 °C for 30 min; then cool it naturally to 1450 °C and keep it at 1450 °C for 90 min; cool it naturally to room temperature to obtain it.

[0082] Ball milling parameters: ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the polyvinyl alcohol aqueous solution is 5 wt%; The kneading time each time is 10 min and the rotation speed is 50 rpm; After extrusion molding, cut it into a block of 165×165×165 mm, and then cut out 43×43 holes with a hole width of 3×3 mm. After the ceramic blank is dried, sintered, and cooled naturally, the size is 150×150×150 (43×43 holes); Microwave drying and shaping is drying at 1000 W and 2450 MHz for 10 min; Hot air drying is drying at 105 °C for 10 h.

[0083] Control Example 1 It is basically the same as Example 1, except that: the heat storage body in the ceramic regenerative heat exchanger is replaced by a 150×150×150 mm (43×43 holes) ceramic heat storage material from a 150×150×150 mm (43×43 holes) cordierite.

[0084] The preparation method of a 150×150×150 mm (43×43 holes) high-temperature resistant ceramic regenerator is as follows: Mix 70 parts of corundum, 25 parts of kaolin, and 5 parts of molybdenum trioxide, then put them into a ball mill jar and ball mill for 30 min; Add 4 parts of an aqueous polyvinyl alcohol solution, and granulate to obtain a blank; Knead the blank 3 times under the condition of 0.08 MPa for 10 min each time at a rotation speed of 50 rpm, let it age for 24 h, then form honeycomb holes through extrusion molding and cutting to obtain a ceramic blank; After microwave drying and shaping, and hot air drying to remove water, heat it at a rate of 10 °C / min to 1000 °C, then continue to heat it at a rate of 3 °C / min to 1650 °C, and keep it at 1650 °C for 30 min; Then cool it naturally to 1450 °C and keep it at 1450 °C for 90 min; Cool it naturally to room temperature to obtain the product.

[0085] Ball milling parameters: The ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the aqueous polyvinyl alcohol solution is 5 wt%. Each kneading time is 10 min and the rotation speed is 50 rpm; After extrusion molding, cut it into a block of 165×165×165 mm, and then cut out 43×43 holes with a hole width of 3×3 mm. After the ceramic blank undergoes drying, sintering, and natural cooling, the size is 150×150×150 (43×43 holes); Microwave drying and shaping is carried out at 1000 W and 2450 MHz for 10 min; Hot air drying is carried out at 105 °C for 10 h.

[0086] Control Example 2 It is basically the same as Example 1, with the only difference being that the regenerator in the ceramic regenerative heat exchanger is replaced with a 150×150×150 mm (43×43 holes) ceramic heat storage material instead of 150×150×150 mm (43×43 holes) cordierite.

[0087] The preparation method of a 150×150×150 mm (43×43 holes) ceramic heat storage material is as follows: Mix 70 parts of corundum, 25 parts of kaolin, and 5 parts of spodumene, then put them into a ball mill jar and ball mill for 30 min; Add 4 parts of an aqueous polyvinyl alcohol solution, and granulate to obtain a blank; Knead the blank 3 times under the condition of 0.08 MPa for 10 min each time at a rotation speed of 50 rpm, let it age for 24 h, then form honeycomb holes through extrusion molding and cutting to obtain a ceramic blank; After microwave drying and shaping, and hot air drying to remove water, heat it at a rate of 10 °C / min to 1000 °C, then continue to heat it at a rate of 3 °C / min to 1650 °C, and keep it at 1650 °C for 30 min; Then cool it naturally to 1450 °C and keep it at 1450 °C for 90 min; Cool it naturally to room temperature to obtain the product.

[0088] Ball milling parameters: ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the polyvinyl alcohol aqueous solution is 5 wt%; Each time the clay kneading time is 10 min and the rotation speed is 50 rpm; After extrusion molding, it is cut into blocks of 165×165×165 mm, and then 43×43 holes are cut, with a hole width of 3×3 mm. After the ceramic blank is dried, sintered, and naturally cooled, the size is 150×150×150 (43×43 holes); Microwave drying and shaping is carried out at 1000 W and 2450 MHz for 10 min; Hot air drying is carried out at 105 °C for 10 h. Example 8

[0089] It is basically the same as Example 1, with the only difference being that: the heat storage body in the ceramic regenerative heat exchanger is replaced by a 150×150×150 mm (43×43 holes) ceramic heat storage material from a 150×150×150 mm (43×43 holes) cordierite.

[0090] The preparation method of the 150×150×150 mm (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 part of zinc stearate are mixed and then put into a ball milling tank for ball milling for 30 min; 4 parts of polyvinyl alcohol aqueous solution are added, and the blank is obtained through granulation; the blank is kneaded 3 times under the condition of 0.08 MPa and aged for 24 h, and then honeycomb holes are formed through extrusion molding and cutting to obtain a ceramic blank; after microwave drying and shaping and hot air drying to remove water, it is heated to 1000 °C at a rate of 10 °C / min and then continued to be heated to 1650 °C at a rate of 3 °C / min, and kept at 1650 °C for 30 min; then it is naturally cooled to 1450 °C and kept at 1450 °C for 90 min; and naturally cooled to room temperature to obtain.

[0091] Ball milling parameters: ball-to-material ratio is 10:1, zirconia balls (diameter 10 mm), rotation speed 500 rpm, ball milling time 5 h; The concentration of the polyvinyl alcohol aqueous solution is 5 wt%; Each time the clay kneading time is 10 min and the rotation speed is 50 rpm; After extrusion molding, it is cut into blocks of 165×165×165 mm, and then 43×43 holes are cut, with a hole width of 3×3 mm. After the ceramic blank is dried, sintered, and naturally cooled, the size is 150×150×150 (43×43 holes); Microwave drying and shaping is carried out at 1000 W and 2450 MHz for 10 min; Hot air drying is carried out at 105°C for 10 h.

[0092] Test Example 1 In the energy storage heat exchange system of the present invention, the heat storage material needs to frequently undergo cycles of high temperature and rapid cooling, forming a severe temperature gradient. Due to its large brittleness and high thermal expansion coefficient, ceramic materials are prone to crack initiation and propagation due to the accumulation of thermal stress under rapid temperature changes, ultimately leading to material fracture or structural collapse. Through thermal shock resistance tests, parameters such as the strength loss rate and crack propagation degree of materials after thermal shock can be quantified, directly reflecting their durability under actual working conditions.

[0093] Thermal shock resistance performance test The test is carried out 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 appropriately adjusted: the test temperature is changed to 1100°C, the three-point bending stress test is not carried out during the test process, and after 30 thermal shock cycles, the bending strength of the sample is tested using an electronic universal testing machine (model WDW100, loading speed 0.5 mm / min).

[0094] Test samples are prepared respectively with reference to the preparation methods in the examples / control examples. It should be noted that after extrusion molding, they are cut into blocks of 125 mm × 70 mm × 70 mm, and there is no need to cut the honeycomb holes; the final size of the samples is approximately 114 mm × 70 mm × 70 mm.

[0095] Bending strength loss rate S σ = ( σ 0 - σ 30 ) / σ 0 × 100% σ 0 is the original bending strength, σ 30 is the bending strength after 30 thermal shock tests.

[0096] Table 4 Thermal shock resistance performance test

[0097] Compared with the cordierite of Example 1, the thermal shock resistance of the high-temperature resistant ceramic heat storage bodies of Examples 4 - 8 is better. The reason is that the high-temperature resistant ceramic heat storage bodies of Examples 4 - 8 are made of corundum-based materials, which are more stable at high temperatures compared to cordierite ceramics, and the attenuation of thermal shock resistance with temperature fluctuations is smaller.

[0098] Examples 4-7 studied the synergistic effect of molybdenum trioxide and spodumene. Practice has proved that when the dosage ratio of molybdenum trioxide to spodumene is 3:2, the heat shock resistance of the prepared high-temperature resistant ceramic regenerator is the best. Excessive molybdenum trioxide content may lead to excessive glass phase, weakening the high-temperature strength; excessive spodumene content may introduce too many low-melting phases, reducing the thermal stability of the material. The addition of molybdenum trioxide can improve the thermal conductivity (by promoting heat transfer at grain boundaries), while the low thermal expansion characteristics of spodumene inhibit the accumulation of thermal stress. The 3:2 ratio of the two may achieve the best balance between thermal conductivity and thermal expansion, maximizing the resistance to crack propagation and forming a more uniform composite structure.

[0099] In Example 8, zinc stearate was added to the formula instead of conventional stearic acid and sodium stearate; the main consideration was that zinc stearate significantly improved the high-temperature resistance, structural density, and thermal shock resistance of the ceramic regenerator through its high-temperature stable decomposition products ZnO, optimized sintering behavior, and processing lubrication effect, while avoiding potential defects introduced by sodium ions. The preferred specific embodiments of the present invention have been described in detail above.

[0100] Test Example 2 Creep resistance is the ability of a ceramic material to resist slow plastic deformation under high temperature and constant stress, which is crucial for heat storage materials operating at high temperature for a long time. During long-term high-temperature service, creep can cause changes in material dimensions, a decrease in strength, and even fracture. Creep resistance directly affects the service life and safety of the heat storage system.

[0101] Creep Resistance Test The experiment was carried out using the method of GB / T 5073-2022 Refractory Materials - Compressive Creep Test Method.

[0102] The test samples were prepared with reference 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 the diameter of the cut central hole was 14 mm; the final sample size was approximately a cylinder with a diameter and height of 55 mm, with a hole in the center (diameter about 12 - 13 mm).

[0103] A cylinder with a diameter and height of 50 ± 0.5 mm and a through hole in the center (diameter 12 - 13 mm) was placed in the furnace as specified, and a load was applied to the specimen at room temperature. When the temperature was below 1000 °C, the heating rate was 10 °C / min; when the temperature was above 1000 °C, the heating rate was 4 - 5 °C / min. After reaching the experimental temperature (1500 °C), it was held for 50 h. The load was 0.2 MPa. The creep rate was calculated according to the following formula: P(%)=(L 50 -L0) / L i ×100% In the formula: P - creep rate; L i- Original height of the specimen, mm; L o - Height of the specimen at the start of constant temperature, mm; L 50 - Height of the specimen after 50 hours of constant temperature, mm.

[0104] Table 5 Creep resistance performance

[0105] The high-temperature performance of cordierite ceramics is relatively weak and the creep resistance is poor. In Examples 4-8, a corundum-spodumene-molybdenum trioxide composite system with corundum as the main body is adopted, which combines the high-temperature stability of corundum and the fluxing effects of molybdenum trioxide and spodumene to form a denser grain boundary structure, effectively inhibiting grain boundary slip at high temperatures and effectively improving the creep resistance.

[0106] Among the high-temperature ceramic regenerators of Examples 4-8, the high-temperature ceramic regenerator of Example 6 is the best. The possible reason is that when the ratio of molybdenum trioxide to spodumene is 3:2, the two form a more stable composite phase. The increase in the content of molybdenum trioxide enhances the grain boundary pinning effect, but an excessive amount may lead to the formation of a brittle phase at the grain boundaries, reducing the strength instead. The appropriate reduction of spodumene balances the amount of liquid phase formed and avoids the weakening of grain boundaries caused by excessive liquid phase. Experimental data show that the creep rate of Example 6 is the lowest, indicating that when the ratio of molybdenum trioxide to spodumene is 3:2, the best balance is achieved between inhibiting grain boundary slip and optimizing the density.

[0107] It should be understood that those of ordinary skill in the art can make many modifications and variations without creative efforts based on the concept of the present invention. Therefore, all technical solutions that can be obtained by those skilled in the art in this technical field through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. Energy storage heat exchange process for high-temperature nitrogen-oxygen separation, characterized in that: The high-temperature nitrogen separated from compressed air through a high-temperature nitrogen-oxygen separator containing a perovskite ceramic gas separation membrane exchanges heat with the compressed air through three sets of juxtaposed ceramic regenerative heat exchangers, achieving continuous and uninterrupted high-temperature nitrogen-oxygen separation.

2. The energy storage heat exchange process for high-temperature nitrogen-oxygen separation according to claim 1, characterized in that: In the continuous and uninterrupted high-temperature nitrogen-oxygen separation by three sets of juxtaposed ceramic regenerative heat exchangers, one set of ceramic regenerative heat exchangers is used to release heat to heat the compressed air; one set of ceramic regenerative heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; one set of ceramic regenerative heat exchangers is on standby after absorbing the heat brought by the high-temperature nitrogen; the three sets rotate to achieve continuous and uninterrupted high-temperature nitrogen-oxygen separation.

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

4. The energy storage heat exchange process for high-temperature nitrogen-oxygen separation as claimed in claim 1 or 2, characterized in that: The high-temperature oxygen separated from high-temperature nitrogen-oxygen separation heats the compressed air through a shell-and-tube heat exchanger, and then is electrically heated to the reaction temperature of 500°C - 1100°C; Or, the high-temperature oxygen separated from high-temperature nitrogen-oxygen separation heats the compressed air through a ceramic regenerative heat exchanger, and then is electrically heated to the reaction temperature of 500°C - 1100°C.

5. The energy storage heat exchange process for high-temperature nitrogen-oxygen separation as claimed in claim 4, characterized in that: 20% - 30% of the compressed air passes through a shell-and-tube heat exchanger and then is electrically heated to the reaction temperature of 500°C - 1100°C; 70% - 80% of the compressed air passes through a ceramic regenerative heat exchanger and then is electrically heated to the reaction temperature of 500°C - 1100°C; The compressed air is combined to 100% and enters the high-temperature nitrogen-oxygen separator for nitrogen-oxygen separation at 500°C - 1100°C; The separated high-temperature oxygen heats the compressed air through a shell-and-tube heat exchanger, and then is electrically heated to the reaction temperature of 500°C - 1100°C; The separated high-temperature nitrogen passes through a ceramic regenerative heat exchanger and stores the heat therein; for three sets of juxtaposed ceramic regenerative heat exchangers, one set of ceramic regenerative heat exchangers is used to absorb the heat brought by the high-temperature nitrogen; one set of ceramic regenerative heat exchangers is on standby after absorbing the heat brought by the high-temperature nitrogen; the three sets rotate to achieve continuous and uninterrupted high-temperature nitrogen-oxygen separation.

6. The energy storage heat exchange process for high-temperature nitrogen-oxygen separation according to claim 5, characterized in that: The ceramic heat storage material used in the ceramic regenerative heat exchanger is in a honeycomb structure or a porous structure.

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

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

9. The energy storage heat exchange process for high-temperature nitrogen-oxygen separation according to claim 6, characterized in that: The preparation method of the ceramic heat storage material is to mix corundum, kaolin, molybdenum trioxide, and spodumene evenly and then ball mill for 2 - 6 h; add an aqueous solution of polyvinyl alcohol, and obtain a blank after granulation; the blank is subjected to pugging, aging, extrusion molding, and cutting honeycomb holes to obtain a ceramic blank; after drying and removing water, it is heated at a rate of 10°C / min to 900 - 1000°C and then continued to be heated at a rate of 3°C / min to 1500 - 1650°C, and held at 1600 - 1650°C for 20 - 40 min; then it is naturally cooled to 1300 - 1450°C and held at 1300 - 1450°C for 80 - 120 min; and naturally cooled to room temperature to obtain the product.

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