Internal compression air separation coupling liquid-air energy storage system and control method

Abstract

The internal compression air separation coupling liquid-air energy storage system comprises an air compressor, an air supercharger and an expansion machine which are sequentially connected in series, and further comprises a lower tower, and the expansion machine is further connected with a first gaseous inlet of the lower tower in series; the main heat exchanger and the liquid-air-liquid separator are sequentially connected in series, the other outlet of the compressor and the other outlet of the air supercharger are both connected with an inlet of the main heat exchanger, and a gas outlet and a first liquid outlet of the liquid-air-liquid separator are connected with a second gas inlet and a liquid inlet of the lower tower respectively; the liquid-air energy storage inlet valve, the liquid-air storage tank, the liquid-air low-temperature pump and the liquid-air energy storage outlet valve are sequentially connected with a second liquid outlet of the air-liquid separator in series, and the liquid-air energy storage outlet valve is circularly connected with an inlet of the air-liquid separator. The whole system does not need to be started frequently during operation, continuous operation can be achieved, meanwhile, the storage efficiency reaches 95%, and losses are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid-air energy storage, and in particular relates to an internal compression air separation coupled liquid-air energy storage system and a control method. Background Art

[0002] The energy consumption of traditional internal compression air separation units is mainly concentrated in the air compressor and booster. Energy storage requires secondary conversion and utilization, the unit energy density is low, the liquid air energy storage conversion efficiency is low (the overall conversion efficiency is less than 50%), the operating pressure is high, there are frequent startups, and it cannot operate for a long time, and the overall economic efficiency is poor. Summary of the Invention

[0003] In response to the above problems, the purpose of the present invention is to provide an internal compression air separation coupled liquid-air energy storage system and control method to solve the problems of low energy conversion efficiency, high operating pressure, frequent startup, long-term operation and poor economy of the existing system.

[0004] To achieve the above-mentioned purpose, the technical solutions adopted by the present invention include:

[0005] An internal compression air separation coupled liquid-air energy storage system comprises an air compressor, an air booster and an expander connected in series in sequence, and a lower tower, wherein the expander is also connected in series with the first gaseous inlet of the lower tower; further comprising a main heat exchanger and a liquid-air-liquid separator connected in series in sequence, wherein the other outlet of the compressor and the other outlet of the air booster are both connected to the inlet of the main heat exchanger, and the gaseous outlet and the first liquid outlet of the liquid-air-liquid separator are respectively connected to the second gaseous inlet and the liquid inlet of the lower tower; further comprising a liquid-air energy storage inlet valve, a liquid-air storage tank, a liquid-air cryogenic pump and a liquid-air energy storage outlet valve connected in series with the second liquid outlet of the air-liquid separator, wherein the liquid-air energy storage outlet valve is cyclically connected to the inlet of the air-liquid separator.

[0006] Preferably, it also includes an APC control module, and the first liquid level sensor and the second liquid level sensor are respectively provided on the lower tower and the liquid air storage tank; the APC control module is connected to the air compressor, the air booster, the expander, the liquid air energy storage inlet valve, the liquid air energy storage outlet valve, the first liquid level sensor and the second liquid level sensor.

[0007] A method for controlling internal compression air separation coupled with liquid-air energy storage is based on the internal compression air separation coupled with liquid-air energy storage system disclosed in the present application. During power valley periods, the load commands of the air compressor, air booster and expander are reduced. When the liquid level of the lower tower is higher than a preset peak value, the liquid-air energy storage inlet valve is opened and the liquid-air energy storage outlet valve is closed at the same time. During power peak periods, the load commands of the air compressor, air booster and expander are increased. When the liquid level of the lower tower is lower than a preset valley value, the liquid-air energy storage inlet valve is closed and the liquid-air energy storage outlet valve is opened at the same time.

[0008] Compared with the prior art, the advantages of the present invention are:

[0009] (1) The present invention relates to an internal compression air separation coupled liquid air energy storage system and control method, which utilizes the peak-valley electrical difference to adjust the load of the air compressor, air booster and expander, affecting the expansion volume of the lower tower, thereby generating a large amount of cold liquid air. During the peak period, the liquid air in the external liquid air storage tank is returned to the lower tower to reduce the load of the booster; during the valley period, the load of the air compressor, air booster and expander is increased, generating a large amount of liquid air to be stored in the liquid air storage tank; the entire process does not require frequent startup and can operate continuously, while the storage efficiency reaches 95%, greatly reducing losses.

[0010] (2) The present invention provides an internal compression air separation coupled liquid-air energy storage system and control method. The internal compression air separation coupled liquid-air energy storage solves the problem of no secondary conversion and utilization of energy storage. The unit energy density is large and the utilization efficiency is higher than other forms of energy storage currently available. The conversion efficiency of this patent is above 95%.

[0011] (3) The internal compression air separation coupled liquid-air energy storage system and control method of the present invention provide valuable energy, while reducing energy consumption and pollution emissions, creating a friendly environment, reducing production and operation costs, and improving corporate benefits; at the same time, it fills another form of liquid-air energy storage, saving energy and reducing emissions.

[0012] (4) The present invention provides an internal compression air separation coupled liquid air energy storage system and control method. The upstream air separation unit coupled with liquid air energy storage has a more economical and energy-saving per cubic meter oxygen production consumption than traditional air separation. The per cubic meter oxygen production consumption is reduced by 0.5%. Through measurement and estimation, it is estimated that the air separation unit can save 1 million yuan in electricity costs for every 30,000 cubic meters of oxygen produced.

[0013] (5) The present invention provides an internal compression air separation coupled liquid-air energy storage system and control method, which introduces an APC control module and can automatically couple with the upstream air separation device to achieve unmanned operation, greatly improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 It is a structural schematic diagram of the internal compression air separation coupled liquid-air energy storage system of the present invention.

[0016] The symbols in the figure represent:

[0017] 1. Air compressor, 2. Air booster, 3. Expander; 4. Main heat exchanger; 5. Liquid-air-liquid separator; 6. Lower tower; 7. Liquid-air energy storage inlet valve, 8. Liquid-air cryogenic pump; 9. Liquid-air storage tank; 10. Liquid-air energy storage outlet valve, 11. First liquid level sensor, 12. Second liquid level sensor, 13. APC control module. DETAILED DESCRIPTION

[0018] The invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0019] It should be noted that the directional terms mentioned in this article, such as "inner cavity", "inner periphery", "inner wall" and "outside", are consistent with the specific directions on the paper in the drawings of the specification or the corresponding directions of the space shown in the drawings; all components and equipment in the present invention, unless otherwise specified, are all components and equipment known in the prior art.

[0020] Example

[0021] This embodiment discloses an internal compression air separation coupled liquid-air energy storage system, comprising an air compressor 1, an air booster 2, and an expander 3 connected in series, and a lower tower 6, wherein the expander 3 is also connected in series with the first gaseous inlet of the lower tower 6; a main heat exchanger 4 and a liquid-air-liquid separator 5 connected in series, wherein the other outlet of the compressor 1 and the other outlet of the air booster 2 are both connected to the inlet of the main heat exchanger 4, and the gaseous outlet and the first liquid outlet of the liquid-air-liquid separator 5 are respectively connected to the second gaseous inlet and the liquid inlet of the lower tower 6; a liquid-air energy storage inlet valve 7, a liquid-air storage tank 9, a liquid-air cryogenic pump 8, and a liquid-air energy storage outlet valve 10 connected in series with the second liquid outlet of the air-liquid separator 5, wherein the liquid-air energy storage outlet valve 10 is cyclically connected to the inlet of the air-liquid separator 5;

[0022] A portion of the air generated by the upstream air separation unit due to variable load is purified by the air compressor 1 to remove impurities and moisture and compressed to produce pressurized gas. A portion of the pressurized gas is transported to the air booster 2 for further pressurization to produce secondary pressurized gas. A portion of the secondary pressurized gas is cooled by the expander 3 and enters the main heat exchanger 4 and then sent to the first gaseous inlet of the lower tower 6, where it exchanges heat with the reflux liquid oxygen in the cold box in the lower tower 6 to obtain rich liquid air. At the same time, another portion of the pressurized gas and another portion of the secondary pressurized gas are respectively transported from the other outlet of the compressor 1 and the other outlet of the air booster 2 to the main heat exchanger 4 for heat exchange to obtain high-pressure liquid air. The high-pressure liquid air enters the air-liquid separator 5 for pressure reduction and gas-liquid separation to obtain gas-phase low-temperature air and low-pressure liquid air. The gas-phase low-temperature air is transported from the gaseous outlet of the liquid-air-liquid separator 5 to the second gaseous inlet of the lower tower 6 for air separation rectification, and the low-pressure liquid air is transported from the first liquid outlet of the liquid-air-liquid separator 5 to the liquid inlet of the lower tower 6 for rectification, and separation is carried out by participating in mass transfer and heat exchange.

[0023] During the power valley period, the load commands of the air compressor 1, the air booster 2 and the expander 3 are reduced. When the liquid level of the lower tower 6 is higher than the preset peak value, the liquid air storage inlet valve 7 is opened and the liquid air storage outlet valve 10 is closed at the same time. That is, the excess low-pressure liquid air peak generated by the air-liquid separator 5 is stored in the liquid air storage tank 9; during the power peak period, the load commands of the air compressor 1, the air booster 2 and the expander 3 are increased. When the liquid level of the lower tower 6 is lower than the preset valley value, the liquid air storage inlet valve 7 is closed and the liquid air storage outlet valve 1 is opened at the same time. 0, that is, the low-pressure liquid air stored in the liquid air storage tank 9 circulates into the air-liquid separator 5 for gas-liquid phase separation, and the liquid air generated at the valley value is transported together with the liquid air produced normally to the liquid inlet of the lower tower 6 for distillation, that is, the liquid air generated at the valley value participates in the distillation and separation of the lower tower to complete the energy storage production task, thereby reducing the production load of the air compressor 1, the air booster 2 and the expander 3, and reducing the proportion of peak and valley electricity distribution; the whole process does not require frequent startup and can operate continuously, and the storage efficiency reaches 90%, which greatly reduces the loss.

[0024] This embodiment uses the peak-valley electrical difference to adjust the load of the air compressor 1, the air booster 2 and the expander 3, affecting the expansion volume of the lower tower 6, thereby generating a large amount of cold liquid air. During the peak period, the liquid air in the external liquid air storage tank 9 is returned to the lower tower 6 to reduce the load of the booster; during the valley period, the load of the air compressor 1, the air booster 2 and the expander 3 is increased, generating a large amount of liquid air to be stored in the liquid air storage tank 9.

[0025] This embodiment further includes an APC control module 13. A first liquid level sensor 11 and a second liquid level sensor 12 are respectively provided on the lower tower 6 and the liquid-air storage tank 9. The APC control module 13 is signal-connected to the air compressor 1, the air booster 2, the expander 3, the liquid-air energy storage inlet valve 7, the liquid-air energy storage outlet valve 10, the first liquid level sensor 11, and the second liquid level sensor 12. The APC control module of this embodiment is a conventionally known APC control system that can automatically couple with the upstream air separation unit, enabling unmanned operation and improving efficiency.

[0026] At the same time, when the internal compression air separation coupled liquid air energy storage system of the present application is applied, the unit consumption of oxygen production per cubic meter of the upstream air separation unit coupled with liquid air energy storage is more economical and energy-saving than traditional air separation, and the unit consumption of oxygen production per cubic meter is reduced by 0.5%. Through calculation, it is estimated that the air separation unit saves 1 million yuan in electricity costs for every 30,000 cubic meters of oxygen production.

[0027] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0028] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0029] In addition, the various different implementation methods disclosed in this solution can also be arbitrarily combined, as long as they do not violate the ideas of this disclosure, they should also be regarded as the contents of the invention of this disclosure.

Claims

1. An internal compression air separation coupled liquid-air energy storage system, characterized in that: The system comprises an air compressor (1), an air booster (2) and an expander (3) connected in series, and further comprises a lower tower (6), wherein the expander (3) is connected in series with a first gaseous inlet of the lower tower (6); It also includes a main heat exchanger (4) and a liquid-air-liquid separator (5) connected in series, wherein the other outlet of the compressor (1) and the other outlet of the air booster (2) are both connected to the inlet of the main heat exchanger (4), and the gaseous outlet and the first liquid outlet of the liquid-air-liquid separator (5) are respectively connected to the second gaseous inlet and the liquid inlet of the lower tower (6); The invention also comprises a liquid-air energy storage inlet valve (7), a liquid-air storage tank (9), a liquid-air cryogenic pump (8) and a liquid-air energy storage outlet valve (10) which are sequentially connected in series with the second liquid outlet of the air-liquid separator (5); the liquid-air energy storage outlet valve (10) is cyclically connected to the inlet of the air-liquid separator (5).

2. The internal compression air separation coupled liquid-air energy storage system according to claim 1, characterized in that: It also includes an APC control module (13), and the lower tower (6) and the liquid empty storage tank (9) are respectively provided with a first liquid level sensor (11) and a second liquid level sensor (12); The APC control module (13) is connected to the air compressor (1), the air booster (2), the expander (3), the liquid-air energy storage inlet valve (7), the liquid-air energy storage outlet valve (10), the first liquid level sensor (11), and the second liquid level sensor (12).

3. A method for controlling internal compression air separation coupled liquid-air energy storage, characterized in that: Based on the internal compression air separation coupled liquid-air energy storage system according to claim 1 or 2; During the power valley period, the load commands of the air compressor (1), the air booster (2) and the expander (3) are reduced. When the liquid level of the lower tower (6) is higher than a preset peak value, the liquid-air energy storage inlet valve (7) is opened and the liquid-air energy storage outlet valve (10) is closed at the same time. During the peak period of electricity, the load commands of the air compressor (1), the air booster (2) and the expander (3) are increased. When the liquid level of the lower tower (6) is lower than a preset valley value, the liquid-air energy storage inlet valve (7) is closed and the liquid-air energy storage outlet valve (10) is opened at the same time.

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