Ethyl acetate preparation system based on solar phase change heat storage system

Abstract

The invention discloses an ethyl acetate preparation system based on a solar phase change heat storage system, and relates to the field of solar energy application. Comprising a phase change heat storage system, a photovoltaic power generation system, an ethanol and acetic acid preparation system and an ethyl acetate preparation system. When the phase change heat storage system stores heat, sunlight is irradiated on the linear Fresnel type collecting lens and is reflected on the heat collecting pipe, and heat is transferred to the fused salt; when the phase change heat storage system releases heat, the switch is turned off, the phase change material releases heat, and the heat is transferred to a required device; for the ethanol and acetic acid generation system, capturing carbon dioxide in the air to react with hydrogen to generate acetic acid and ethanol; when the ethyl acetate preparation system works, the phase change heat storage system provides a temperature required by reaction, ethanol and acetic acid react in the reaction device, a product is introduced into the distillation separation system, the phase change heat storage system is used for heating, and the product is distilled out. When the ethyl acetate is separated, the temperature and the pressure are accurately adjusted in an electric heating manner, so that the purity of the product is ensured.

Description

Technical Field

[0001] The present invention is an ethyl acetate preparation system based on a solar energy phase change heat storage system, and relates to the technical field of solar energy applications. Background Art

[0002] Molten salt has the advantages of high heat storage density, wide temperature range, low cost, environmental friendliness, etc., and is suitable for large-scale applications. The solar molten salt phase change technology is an efficient energy storage technology that combines solar thermal utilization and phase change heat storage, and is also widely used in various fields of production and life. In chemical production, high-temperature reactions are often involved, which require a large amount of heat energy. The traditional heat energy supply relies on fossil energy, with relatively high energy consumption and low efficiency. Therefore, in the field of chemical production, the phase change heat storage technology shows great application potential, which has the advantages of being clean and renewable.

[0003] Ethyl acetate is an organic compound with wide applications. For example, it can be used in the medical industry, food industry, industrial solvents, etc. It is also an important intermediate in many organic synthesis reactions, such as for the synthesis of acetoacetic ester and pharmaceutical intermediates; at the same time, it can also be used as a representative of lipid compounds to study the mechanism of esterification reactions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to overcome the problems of pollution, high energy consumption, low efficiency, etc. brought by the utilization of traditional heat energy in chemical production.

[0005] The present invention provides an ethyl acetate preparation system based on a solar energy phase change heat storage system, which mainly consists of a phase change heat storage system (1), a photovoltaic power generation system (2), an ethanol and acetic acid preparation system (3), an ethyl acetate preparation system (4), and a temperature and pressure monitoring system (5);

[0006] The phase change heat storage system (1) includes a linear Fresnel type concentrating heat collection device (11), a phase change heat storage device (13), and switches a (12) and b (14);

[0007] The described linear Fresnel concentrating and heat collecting device (11) consists of a linear Fresnel concentrator (11a) and a heat collecting tube (11b). The heat collecting tube (11b) is located at the focus point of the linear Fresnel concentrator (11a); the phase change heat storage device (13) is assembled with molten salt (132), a spiral heat exchange tube (131b), and an inner core (131a) in a box. The spiral heat exchange tube (131b) is wound around the inner core (131a), and the outer box of the spiral heat exchange tube is filled with molten salt (132); one end of the heat collecting tube (11b) is connected to the outlet end of the spiral heat exchange tube (131b) via switch a (12), and the inlet end of the spiral heat exchange tube (131b) is connected to the other end of the heat collecting tube (11b) via switch b (14) to form a first circulation loop. The pipeline of the first circulation loop is filled with heat-conducting oil;

[0008] The ethanol and acetic acid preparation system (3) includes an air collection box (32), a carbon dioxide adsorption device (35), a carbon dioxide collection device (37), an acetic acid fixed-bed reactor (38), a hydrogen storage tank (39), and an ethanol fixed-bed reactor (310). A first heating tube (114-1) is provided in the carbon dioxide adsorption device (35), a second heating tube (114-2) is provided in the acetic acid fixed-bed reactor (38), and a third heating tube (114-3) is provided in the ethanol fixed-bed reactor (310);

[0009] The ethyl acetate preparation system (4) includes an acetic acid collection box (41), an ethanol collection box (42), an ethyl acetate reactor (45), a distillation column I (47), a distillation column II (48), an ethyl acetate collection device (411), and a water tank (415). A fourth ribbed tube (114-4) is provided in the ethyl acetate reactor (45); resistance wires (23) are installed in both the distillation column I (47) and the distillation column II (48);

[0010] The photovoltaic power generation system (2) includes a photovoltaic panel (21), a power supply (22), a circuit switch (24), and a resistance wire (23);

[0011] The outlet end of the further spiral heat exchange tube (131b) is divided into two branches via switch c (15). One of the branches is connected to the inlet end of the first heating tube (114-1) via switch d (16). The outlet end of the first heating tube (114-1) is aggregated to switch f (18) via switch g (19). Switch f (18) is connected to the inlet end of the spiral heat exchange tube (131b) to form a second circulation loop; the other branch after switch c (15) is further divided into three branches. The first branch after switch c (15) is connected to the inlet end of the third heating tube (114-3) via switch u (317). The outlet end of the third heating tube (114-3) is aggregated to switch f (18) via switch i (111) to form a third circulation loop; the second branch after switch c (15) is connected to the inlet end of the second heating tube (114-2) via switch j (112). The outlet end of the second heating tube (114-2) is aggregated to switch f (18) via switch h (110) to form a fourth circulation loop; the third branch after switch c (15) is connected to the inlet end of the fourth finned tube (114-4) via switch k (113). The outlet end of the fourth finned tube (114-4) is aggregated to switch f (18) via switch e (17) to form a fifth circulation loop;

[0012] An air pump (31) is connected to the inlet of the air collection box (32). The outlet of the air collection box (32) is successively connected to the inlet end of the carbon dioxide collection device (37) via switch m (34), the carbon dioxide adsorption device (35), and switch n (36). The outlet end of the carbon dioxide collection device (37) is divided into two branches. One of the branches is connected to the acetic acid fixed bed reactor (38) via switch o (311), and the other branch is connected to the ethanol fixed bed reactor (310) via switch p (312); the hydrogen storage tank (39) is connected to the acetic acid fixed bed reactor (38) via switch q (313), and at the same time, the hydrogen storage tank (39) is connected to the ethanol fixed bed reactor (310) via switch r (314);

[0013] The inlet of the acetic acid collection tank (41) is connected to the acetic acid fixed bed reactor (38) via the switch s (315), and the outlet of the acetic acid collection tank (41) is connected to the inlet one of the ethyl acetate reactor (45) via the switch v (43); the inlet of the ethanol collection tank (42) is connected to the ethanol fixed bed reactor (310) via the switch t (316), and the outlet of the ethanol collection tank (42) is connected to the inlet two of the ethyl acetate reactor (45) via the switch w (44). The outlet of the ethyl acetate reactor (45) is connected to the inlet of the distillation column I (47) via the switch x (46). The outlet of the fraction one (acetic acid, temperature range 100 - 118 °C) of the distillation column I (47) is connected to the acetic acid collection tank (41) via the switch zc (414). The outlet of the fraction two (water, temperature range 78.5 - 100 °C) of the distillation column I (47) is connected to the water tank (415) via the switch za (412). The outlet of the fraction three (remaining coolant containing ethyl acetate and ethanol) of the distillation column I (47) is connected to the inlet of the distillation column II (48) via the switch y (49). The outlet of the fraction one (ethanol, temperature range 77 - 78.5 °C) of the distillation column II (48) is connected to the ethanol collection tank (42) via the switch zb (413). The outlet of the fraction two (ethyl acetate) of the distillation column II (48) is connected to the ethyl acetate collection device (411) via the switch z (410);

[0014] The photovoltaic panel (21) is sequentially connected to the power supply (22), the circuit switch (24), and the resistance wire (23) through the circuit for the resistance wire (23) to generate heat.

[0015] The acetic acid fixed bed reactor (38), the ethanol fixed bed reactor (310), the ethyl acetate reactor (45), the distillation column I (47), and the distillation column II (48) are respectively equipped with a temperature detection device T and a pressure detection device P. The temperature detection device T and the pressure detection device P are respectively electrically connected to the control system (51), and at the same time, the control system (51) is also electrically connected to the circuit switch (24);

[0016] Heat transfer oil flows in the first, second, third, fourth, and fifth circulation loop pipes for heat transfer, and the switches on these five circulation loops all have the function of a pump or are equipped with a pump as needed to provide the driving force for the heat transfer oil to flow.

[0017] The structures of the first heating pipe (114 - 1) to the fourth heating pipe (114 - 4) are all serpentine coiled pipes (114b), and at the same time, fins (114a) are evenly distributed on the outer surface of the serpentine coiled pipe (114b);

[0018] The carbon dioxide adsorption device (35) contains monoethanolamine absorption liquid for adsorbing carbon dioxide in the air. A switch l (33) is provided at one outlet of the carbon dioxide adsorption device (35);

[0019] The acetic acid fixed bed reactor (38), ethanol fixed bed reactor (310), and ethyl acetate reactor (45) contain the respective catalysts required.

[0020] Furthermore, switch g (19), switch d (16), switch e (17), switch i (111), switch u (317), switch k (113), switch j (112), and switch h (110) are respectively and electrically connected to the control system (51).

[0021] The temperature and pressure monitoring system (5) includes a temperature detection device T, a pressure detection device P, and a control system (51).

[0022] When the phase change heat storage system 1 stores heat, sunlight shines on the linear Fresnel condenser 11a and is reflected onto the heat collecting pipe 11b. The heat transfer oil flowing through the heat collecting pipe 11b transfers heat to the molten salt phase change material, and the phase change material molten salt 132 melts and absorbs heat; when the phase change heat storage system 1 releases heat, the switch of the heat storage pipeline is closed, the phase change material molten salt 132 solidifies and releases heat, and the heat transfer oil takes out the heat and transfers it to the ethanol and acetic acid generation system 3 and ethyl acetate preparation system 4 that are needed; for the ethanol and acetic acid generation system 3, it mainly captures carbon dioxide in the air and reacts with hydrogen under certain conditions to generate acetic acid and ethanol; when the ethyl acetate preparation system 4 starts to work, ethanol and acetic acid are provided by the reactant device, and the phase change heat storage system 1 provides the temperature required for the reaction. The reaction takes place in the reaction device where the catalyst has been added. Due to the incomplete reaction, the product is a mixture of ethanol, acetic acid, ethyl acetate, and water. The mixture is introduced into the subsequent distillation column. These substances have different boiling points and are heated using the heat of the phase change heat storage system. The temperature and pressure monitoring system 5 monitors the temperature and pressure and adjusts them in a timely manner so that the temperature is maintained at the boiling points of each substance, and the products are distilled and separated. The separated acetic acid and ethanol are returned to the corresponding substance collection boxes. When separating ethyl acetate, since the boiling point difference is not large, an electric heating method is used at this time to more precisely adjust the temperature and pressure to ensure the purity of the product.

[0023] The beneficial effects of the present invention are as follows:

[0024] ① Utilize the solar energy photothermal phase change heat storage system to provide heat for the preparation process of ethyl acetate, reducing energy consumption and costs.

[0025] ② Directly obtain the raw material carbon dioxide from the air, and the carbon dioxide adsorption liquid can be used repeatedly.

[0026] It has great significance for "low-carbon" environmental protection.

[0027] ③ Utilize the solar photovoltaic system to separate and purify the reaction products, achieving green and renewable. Description of the Drawings

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] Figure 1 is the main structure diagram of the present invention;

[0030] Figure 2 is a schematic diagram of the linear Fresnel type heat collection device of the present invention;

[0031] Figure 3 is the main view of the light rays of the linear Fresnel type heat collection device of the present invention;

[0032] Figure 4 is a schematic diagram of the internal pipeline of the phase change heat storage device of the present invention;

[0033] Figure 5 is the structure diagram of the resistance wire of the present invention.

[0034] Figure 6 is the pipeline diagram inside the heating device required by the present invention

[0035] The reference numerals in the figures are explained as follows: 11 - linear Fresnel type concentrating heat collection device; 11a - linear Fresnel type condenser; 11b - heat collection pipe; 12 - switch a; 13 - phase change heat storage device; 131a - inner core; 131b - spiral pipe; 132 - molten salt; 14 - switch b; 15 - switch c; 16 - switch d; 17 - switch e; 18 - switch f; 19 - switch g; 110 - switch h; 111 - switch i; 112 - switch j; 113 - switch k; 114 - heating pipe; 114a - fin; 114b - serpentine coil; 21 - photovoltaic; 22 - power supply; 23 - resistance wire; 24 - circuit switch; 31 - air pump; 32 - air collection box; 33 - switch l; 34 - switch m; 35 - carbon dioxide adsorption device; 36 - switch n; 37 - carbon dioxide collection device; 38 - acetic acid fixed bed reactor; 39 - hydrogen storage tank; 310 - ethanol fixed bed reactor; 311 - switch o; 312 - switch p; 313 - switch q; 314 - switch r; 315 - switch s; 316 - switch t; 317 - switch u; 41 - acetic acid collection box; 42 - ethanol collection box; 43 - switch v; 44 - switch w; 45 - ethyl acetate reactor; 46 - switch x; 47 - distillation column I; 48 - distillation column II; 49 - switch y; 410 - switch z; 411 - ethyl acetate collection device; 412 - switch za; 413 - switch zb; 414 - switch zc; 415 - water tank; 51 - control system. Specific embodiments

[0036] The present invention will be further elaborated in detail with reference to the accompanying drawings. The following drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the structural components related to the present invention.

[0037] As Figure 1 shown, an ethyl acetate preparation system based on a solar energy phase change heat storage system mainly consists of a phase change heat storage system 1, a photovoltaic power generation system 2, an ethanol and acetic acid preparation system 3, an ethyl acetate preparation system 4, and a temperature and pressure monitoring system 5. Figure 1 In the figure, P represents a pressure gauge and T represents a thermometer.

[0038] For the phase change heat storage system 1, during its operation, it is divided into a heat storage process and a heat release process. Heat storage process: Switch a12 and switch b14 are turned on, and other switches are turned off. Sunlight irradiates on the linear Fresnel condenser 11a and is concentrated and reflected onto the heat collection tube 11b. Heat transfer oil flows through the pipeline to transfer heat into the phase change heat storage device 13. The molten salt 132 in the phase change heat storage device absorbs heat and undergoes a phase change to store heat. The spiral heat exchange tube 131b can increase the heat exchange area and time between the heat exchange fluid and the molten salt 132, improving the heat exchange efficiency. Heat release process: Switch a12 and switch b14 are turned off, and the heat transfer oil flows out and in through switch c15 and switch f18 respectively to transfer the heat of the molten salt.

[0039] The photovoltaic power generation system 2 consists of a photovoltaic panel 21, a power supply 22, a resistance wire 23, and a circuit switch 24. The electricity generated by the photovoltaic panel 21 is stored in the power supply 22. When the switch 24 is closed, the power supply 22 discharges to the resistance wire 23 to generate heat, which is used for distillation column I 47 and distillation column II 48

[0040] For the ethanol and acetic acid preparation system 3, when collecting carbon dioxide in the air, the air pump 31 is turned on to extract air and store it in the air collection box 32. Further, when switch m34 is turned on, the air enters the carbon dioxide adsorption device 35. The carbon dioxide adsorption device 35 contains a monoethanolamine adsorption solution. After the adsorption is completed, switch m34 is turned off, switch l33 is turned on to remove the excess air, then switch l33 is turned off, and switches c15, d16, f18, and g19 are turned on. The heat transfer oil flows out from the phase change heat storage device 13 to transfer heat to the monoethanolamine absorption solution. The temperature is controlled at 100 - 120 °C through the pressure and temperature detection system 5. Carbon dioxide overflows from the monoethanolamine absorption solution, and when switch n36 is turned on, the carbon dioxide enters the collection device 37 for future use.

[0041] For the ethanol and acetic acid preparation system 3 described above, when preparing ethanol and ethyl acetate, turn on switch o311, switch p312, switch q313, and switch r314. The hydrogen in the carbon dioxide and hydrogen storage tank 39 enters the acetic acid fixed-bed reactor 38 and the ethanol fixed-bed reactor 310. Turn off switch o311, switch p312, switch q313, and switch r314, and turn on switch c15, switch j112, switch h110, switch f18, switch u317, and switch i111. The heat transfer oil flows out from the phase change heat storage device 13 to heat the acetic acid fixed-bed reactor 38 and the ethanol fixed-bed reactor 310. The pressure and temperature monitoring system 5 controls the flow rate of the fluid in the heat exchange fluid pipeline to adjust the temperature and pressure, controls the temperature of the generated acetic acid to be 150 - 200 °C and the pressure to be 3 - 5 MPa, and controls the temperature of the generated ethanol to be 200 - 300 °C and the pressure to be 5 - 10 MPa to ensure the normal progress of the reaction. After the reaction ends, turn on switch s315 and switch t316 to collect the acetic acid generated by the acetic acid fixed-bed reactor 38 and the ethanol generated by the ethanol fixed-bed reactor 310 into the acetic acid collection tank 41 and the ethanol collection tank 42 respectively.

[0042] For the ethyl acetate preparation system 4 described above, when preparing ethyl acetate, turn on switch v43 and switch w44. The acetic acid in the acetic acid collection tank 41 and the ethanol in the ethanol collection tank 42 enter the ethyl acetate reactor 45, and concentrated sulfuric acid is added as a catalyst for the reaction. Turn off switch v43 and switch w44, and turn on switch e17, switch k113, switch c15, and switch f18. The heat transfer oil extracts heat from the phase change heat storage device 13 to heat the formation reaction of ethyl acetate. The temperature and pressure monitoring system 5 monitors the temperature and pressure in the ethyl acetate reactor 45 and controls the temperature to be 70 - 80 °C by adjusting switch e17 and switch k113. When the reaction proceeds to a certain extent, turn on switch x46 to make the reaction product liquid enter the distillation column I 47, and close the circuit switch 24 so that Figure 5The resistance wire 23 shown operates to heat and generate a liquid. The generated liquid mainly contains water, ethanol, acetic acid, and ethyl acetate. Separation is carried out by taking advantage of their different boiling points. The temperature and pressure monitoring system 5 adjusts and controls the voltage to make the heating temperature of the resistance wire higher than 100°C and lower than 118°C, so that acetic acid can be separated out. By opening the switch zc414, the acetic acid separated by the distillation column I 47 enters the acetic acid collection tank 41 through the switch zc414. After the generated liquid condenses, the temperature and pressure monitoring system 5 adjusts and controls the voltage to make the heating temperature of the resistance wire lower than 100°C and higher than 78.5°C to separate out water. By opening the switch za412, the separated water enters the water tank 415. After the remaining generated liquid condenses, the switch y49 is opened, and the remaining generated liquid enters the distillation column II 48. The temperature and pressure monitoring system 5 precisely adjusts and controls the voltage to make the heating temperature of the resistance wire such that the heating temperature is lower than 78.5°C and higher than 77°C. Through rectification, the separated ethanol flows into the ethanol collection tank 42 through the switch zb413, and the rectified ethyl acetate enters the ethyl acetate collection device 411 through the switch z410.

[0043] In the above-mentioned process involving heat transfer oil heating, as Figure 6 shown, the heating pipe 114 is in a serpentine coil shape and is externally provided with fins 114a, which can improve the heat exchange efficiency.

[0044] Inspired by the above-described embodiments of the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An ethyl acetate preparation system based on a solar energy phase change heat storage system, characterized in that it mainly consists of a phase change heat storage system (1), a photovoltaic power generation system (2), an ethanol and acetic acid preparation system (3), an ethyl acetate preparation system (4), and a temperature and pressure monitoring system (5); The phase change heat storage system (1) includes a linear Fresnel type concentrating heat collection device (11), a phase change heat storage device (13), switch a (12), and switch b (14); The linear Fresnel type concentrating heat collection device (11) consists of a linear Fresnel type condenser (11a) and a heat collection pipe (11b), and the heat collection pipe (11b) is located at the focal point of the linear Fresnel type condenser (11a); the phase change heat storage device (13) is assembled with molten salt (132), a spiral heat exchange pipe (131b), and an inner core (131a) into a box body, the spiral heat exchange pipe (131b) is wound around the inner core (131a), and the outer box body of the spiral heat exchange pipe is filled with molten salt (132); one end of the heat collection pipe (11b) is connected to the outlet end of the spiral heat exchange pipe (131b) via switch a (12), and the inlet end of the spiral heat exchange pipe (131b) is connected to the other end of the heat collection pipe (11b) via switch b (14) to form a first circulation loop, and the pipeline of the first circulation loop is filled with heat conducting oil; The ethanol and acetic acid preparation system (3) includes an air collection box (32), a carbon dioxide adsorption device (35), a carbon dioxide collection device (37), an acetic acid fixed bed reactor (38), a hydrogen storage tank (39), and an ethanol fixed bed reactor (310). A first heating pipe (114-1) is provided in the carbon dioxide adsorption device (35), a second heating pipe (114-2) is provided in the acetic acid fixed bed reactor (38), and a third heating pipe (114-3) is provided in the ethanol fixed bed reactor (310); The ethyl acetate preparation system (4) includes an acetic acid collection box (41), an ethanol collection box (42), an ethyl acetate reactor (45), a distillation column I (47), a distillation column II (48), an ethyl acetate collection device (411), and a water tank (415), wherein a fourth ribbed pipe (114-4) is provided in the ethyl acetate reactor (45); resistance wires (23) are installed in both the distillation column I (47) and the distillation column II (48); The photovoltaic power generation system (2) includes a photovoltaic panel (21), a power supply (22), a circuit switch (24), and a resistance wire (23); The outlet end of the further spiral heat exchange tube (131b) is divided into two branches via switch c (15). One of the branches is connected to the inlet end of the first heating tube (114-1) via switch d (16). The outlet end of the first heating tube (114-1) is aggregated to switch f (18) via switch g (19), and switch f (18) is connected to the inlet end of the spiral heat exchange tube (131b) to form a second circulation loop. The other branch after switch c (15) is further divided into three branches. The first branch after switch c (15) is connected to the inlet end of the third heating tube (114-3) via switch u (317). The outlet end of the third heating tube (114-3) is aggregated to switch f (18) via switch i (111) to form a third circulation loop. The second branch after switch c (15) is connected to the inlet end of the second heating tube (114-2) via switch j (112). The outlet end of the second heating tube (114-2) is aggregated to switch f (18) via switch h (110) to form a fourth circulation loop. The third branch after switch c (15) is connected to the inlet end of the fourth finned tube (114-4) via switch k (113). The outlet end of the fourth finned tube (114-4) is aggregated to switch f (18) via switch e (17) to form a fifth circulation loop. An air pump (31) is connected to the inlet of the air collection tank (32). The outlet of the air collection tank (32) is sequentially connected to the inlet end of the carbon dioxide collection device (37) via switch m (34), the carbon dioxide adsorption device (35), and switch n (36). The outlet end of the carbon dioxide collection device (37) is divided into two branches. One of the branches is connected to the acetic acid fixed bed reactor (38) via switch o (311), and the other branch is connected to the ethanol fixed bed reactor (310) via switch p (312). The hydrogen storage tank (39) is connected to the acetic acid fixed bed reactor (38) via switch q (313), and at the same time, the hydrogen storage tank (39) is connected to the ethanol fixed bed reactor (310) via switch r (314). The inlet of the acetic acid collection tank (41) is connected to the acetic acid fixed bed reactor (38) via the switch s (315), and the outlet of the acetic acid collection tank (41) is connected to the inlet one of the ethyl acetate reactor (45) via the switch v (43); the inlet of the ethanol collection tank (42) is connected to the ethanol fixed bed reactor (310) via the switch t (316), and the outlet of the ethanol collection tank (42) is connected to the inlet two of the ethyl acetate reactor (45) via the switch w (44). The outlet of the ethyl acetate reactor (45) is connected to the inlet of the distillation column I (47) via the switch x (46). The outlet of the fraction one (acetic acid, temperature range 100 - 118 °C) of the distillation column I (47) is connected to the acetic acid collection tank (41) via the switch zc (414). The outlet of the fraction two (water, temperature range 78.5 - 100 °C) of the distillation column I (47) is connected to the water tank (415) via the switch za (412). The outlet of the fraction three (remaining coolant containing ethyl acetate and ethanol) of the distillation column I (47) is connected to the inlet of the distillation column II (48) via the switch y (49). The outlet of the fraction one (ethanol, temperature range 77 - 78.5 °C) of the distillation column II (48) is connected to the ethanol collection tank (42) via the switch zb (413). The outlet of the fraction two (ethyl acetate) of the distillation column II (48) is connected to the ethyl acetate collection device (411) via the switch z (410); The photovoltaic panel (21) is sequentially connected to the power supply (22), the circuit switch (24), and the heating wire (23) through a circuit for the heating wire (23) to generate heat; The acetic acid fixed bed reactor (38), the ethanol fixed bed reactor (310), the ethyl acetate reactor (45), the distillation column I (47), and the distillation column II (48) are respectively equipped with a temperature detection device T and a pressure detection device P. The temperature detection device T and the pressure detection device P are respectively electrically connected to the control system (51), and at the same time, the control system (51) is also electrically connected to the circuit switch (24); The acetic acid fixed bed reactor (38), the ethanol fixed bed reactor (310), and the ethyl acetate reactor (45) contain the respective required catalysts; The temperature and pressure monitoring system (5) includes a temperature detection device T, a pressure detection device P, and a control system (51).

2. The ethyl acetate preparation system based on a solar energy phase change heat storage system according to claim 1, characterized in that: the switches g (19), d (16), e (17), i (111), u (317), k (113), j (112), and h (110) are respectively electrically connected to the control system (51).

3. The ethyl acetate preparation system based on a solar energy phase change heat storage system according to claim 1, characterized in that: heat transfer oil flows in the first, second, third, fourth, and fifth circulation loop pipes for heat transfer, and the switches on these five circulation loops all have the function of a pump or are provided with a pump as needed to provide the driving force for the flow of the heat transfer oil.

4. The ethyl acetate preparation system based on a solar energy phase change heat storage system according to claim 1, characterized in that: the structures of the first heating pipe (114-1) to the fourth heating pipe (114-4) are all serpentine coiled pipes (114b), and at the same time, fins (114a) are evenly distributed on the outer surface of the serpentine coiled pipes (114b).

5. The ethyl acetate preparation system based on a solar energy phase change heat storage system according to claim 1, characterized in that: the carbon dioxide adsorption device (35) contains monoethanolamine absorbent solution for adsorbing carbon dioxide in the air. A switch l (33) is provided at an outlet of the carbon dioxide adsorption device (35).

6. The ethyl acetate preparation system based on a solar energy phase change heat storage system according to claim 1, characterized in that: the outlet of fraction one of the distillation column I (47) corresponds to the acetic acid outlet, and the temperature range is 100-118 °C; the outlet of fraction two of the distillation column I (47) corresponds to the water outlet, and the temperature range is 78.5-100 °C; the outlet of fraction three of the distillation column I (47) is the remaining coolant containing ethyl acetate and ethanol; the outlet of fraction one of the distillation column II (48) corresponds to the ethanol outlet, and the temperature range is 77-78.5 °C; the outlet of fraction two of the distillation column II (48) corresponds to the ethyl acetate outlet.

7. A working method of an ethyl acetate preparation system based on a solar energy phase change heat storage system according to any one of claims 1-6, characterized in that, When the phase change heat storage system (1) stores heat, sunlight shines on the linear Fresnel condenser (11a) and is reflected on the heat collecting pipe (11b). The heat-conducting oil flowing through the heat collecting pipe (11b) transfers heat to the molten salt phase change material, and the phase change material molten salt (132) melts and absorbs heat; when the phase change heat storage system (1) releases heat, the switches a (12) and b (14) of the heat storage pipeline are closed, and the phase change material molten salt (132) solidifies and releases heat. The heat-conducting oil takes out the heat and transfers it to the required ethanol and acetic acid generation system (3) and the ethyl acetate preparation system (4); for the ethanol and acetic acid generation system (3), it mainly captures carbon dioxide in the air and reacts with hydrogen under certain conditions to generate acetic acid and ethanol; when the ethyl acetate preparation system (4) starts to work, ethanol and acetic acid are provided by the reactant device, and the phase change heat storage system (1) provides the temperature required for the reaction. The reaction is carried out in the reaction device that has already added a catalyst. Due to the incomplete reaction, the product is a mixture of ethanol, acetic acid, ethyl acetate and water. The mixture is introduced into the subsequent distillation column. These substances have different boiling points and are heated using the heat of the phase change heat storage system. The temperature and pressure monitoring system (5) monitors the temperature and pressure and adjusts them in a timely manner so that the temperature is maintained at the boiling points of each substance, and the products are distilled and separated. The separated acetic acid and ethanol are returned to the corresponding substance collection boxes; when separating ethyl acetate, since the boiling point difference is not large, an electric heating method is used at this time to more precisely adjust the temperature and pressure to ensure the purity of the product.

8. The method according to claim 7, wherein For the phase change heat storage system 1, during operation, it is divided into a heat storage process and a heat release process. Heat storage process: Switch a (12) and switch b (14) are turned on, switch c (15) and switch f (18) are turned off. Sunlight shines on the linear Fresnel concentrator (11a) and is intensively reflected onto the heat collection tube (11b). Heat transfer oil flows through the pipeline to transfer heat into the phase change heat storage device (13). The molten salt (132) in the phase change heat storage device absorbs heat and undergoes a phase change to store heat. The spiral heat exchange tube (131b) can increase the heat exchange area and time between the heat exchange fluid and the molten salt (132), improving the heat exchange efficiency. Heat release process: Switch a (12) and switch b (14) are turned off. The heat transfer oil flows out and in through switch c (15) and switch f (18) respectively, transferring the heat of the molten salt out; The electricity generated by the photovoltaic panel (21) is stored in the power supply (22). When the switch (24) is closed, the power supply (22) discharges to the resistance wire (23) to generate heat, which is used for distillation column I (47) and distillation column II (48); For the ethanol and acetic acid preparation system (3), when collecting carbon dioxide in the air, the air pump (31) is turned on to extract air and store it in the air collection box (32). Further, switch m (34) is turned on, and the air enters the carbon dioxide adsorption device (35). The carbon dioxide adsorption device (35) contains a monoethanolamine adsorption solution. After the adsorption is completed, switch m (34) is turned off, switch l (33) is turned on to exhaust the excess air, and then switch l (33) is turned off. Switch c (15), switch d (16), switch f (18), and switch g (19) are turned on. The heat transfer oil flows out of the phase change heat storage device (13) and transfers heat to the monoethanolamine absorption solution. The temperature is controlled at 100 - 120 °C through the pressure and temperature detection system (5). Carbon dioxide overflows from the monoethanolamine absorption solution. Switch n (36) is turned on, and the carbon dioxide enters the collection device (37) for future use; The described ethanol and acetic acid preparation system (3), when preparing ethanol and ethyl acetate, turn on switch o (311), switch p (312), switch q (313), switch r (314). The hydrogen in the carbon dioxide and hydrogen storage tank (39) enters the acetic acid fixed bed reactor (38) and the ethanol fixed bed reactor (310). Turn off switch o (311), switch p (312), switch q (313), switch r (314), turn on switch c (15), switch j (112), switch h (110), switch f (18), switch u (317), switch i (111). The heat transfer oil flows out from the phase change heat storage device (13) to heat the acetic acid fixed bed reactor (38) and the ethanol fixed bed reactor (310). The pressure and temperature monitoring system (5) controls the flow rate of the fluid in the heat exchange fluid pipeline to adjust the temperature and pressure, controls the temperature of the generated acetic acid to be 150 - 200 °C and the pressure to be 3 - 5 MPa, controls the temperature of the generated ethanol to be 200 - 300 °C and the pressure to be 5 - 10 MPa to ensure the normal progress of the reaction. After the reaction ends, turn on switch s (315) and switch t (316) to collect the acetic acid generated by the acetic acid fixed bed reactor (38) and the ethanol generated by the ethanol fixed bed reactor (310) into the acetic acid collection tank (41) and the ethanol collection tank (42) respectively; The described ethyl acetate preparation system (4). When preparing ethyl acetate, switch v (43) and switch w (44) are turned on. Acetic acid in the acetic acid collection tank (41) and ethanol in the ethanol collection tank (42) enter the ethyl acetate reactor (45). At the same time, concentrated sulfuric acid is added as a catalyst for the reaction. Switch v (43) and switch w (44) are turned off, and switch e (17), switch k (113), switch c (15), and switch f (18) are turned on. The heat transfer oil extracts heat from the phase change heat storage device (13) to heat the formation reaction of ethyl acetate. The temperature and pressure monitoring system (5) monitors the temperature and pressure in the ethyl acetate reactor (45) and controls the temperature at 70 - 80 °C by adjusting switch e (17) and switch k (113). When the reaction proceeds for a period of time, switch x (46) is turned on, and the reaction product liquid enters the distillation column I (47). The circuit switch (24) is closed to make the resistance wire (23) work and heat the product liquid. The product liquid mainly contains water, ethanol, acetic acid, and ethyl acetate. Separation is carried out using their different boiling points. The temperature and pressure monitoring system 5 adjusts and controls the voltage to make the heating temperature of the resistance wire higher than 100 °C and lower than 118 °C to separate acetic acid. Switch zc (414) is turned on, and the acetic acid separated from the distillation column I (47) enters the acetic acid collection tank (41) through switch zc (414). After the product liquid condenses, the temperature and pressure monitoring system (5) adjusts and controls the voltage to make the heating temperature of the resistance wire lower than 100 °C and higher than 78.5 °C to separate water. Switch za (412) is turned on, and the separated water enters the water tank (415). After the remaining product liquid condenses, switch y (49) is turned on, and the remaining product liquid enters the distillation column II (48). The temperature and pressure monitoring system (5) precisely adjusts and controls the voltage to make the heating temperature of the resistance wire lower than 78.5 °C and higher than 77 °C. The separated ethanol is distilled and flows into the ethanol collection tank (42) through switch zb (413). The ethyl acetate obtained by rectification enters the ethyl acetate collection device 411 through switch z (410).

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