Energy-saving air separation device of double-tower rectification oxygenation tower

Abstract

The utility model relates to the technical field of air separation, in particular to an energy-saving air separation device of a double-tower rectification oxygenation tower, which comprises an air filter, an air compressor and a purifier which are connected in sequence, a cooler of the air compressor takes 7-13 DEG C industrial chilled water as a cooling medium, and the purifier comprises two adsorbers which are connected in parallel. The purifier is connected with a cold box, a heat exchanger is arranged in the cold box, air discharged from the purifier enters the heat exchanger, the heat exchanger is communicated with a lower tower, an upper tower is arranged on the upper portion of a condensation evaporator, the lower tower is arranged at the bottom of the condensation evaporator, and lower tower backflow liquid is jointly provided by the condensation evaporator and an auxiliary cold condensation evaporator; the lower tower is communicated with an auxiliary condensation evaporator, nitrogen extracted from the lower tower is condensed in the auxiliary condensation evaporator to serve as reflux of the lower tower, and the rest of nitrogen is reheated by the heat exchanger, then is discharged out of the cold box and enters a pressurizing end of an expansion machine to be further pressurized. The device is small in occupied area and low in energy consumption.

Description

Technical Field

[0001] The utility model relates to the technical field of air separation, in particular to an energy-saving air separation device of a double-tower rectification and oxygenation tower. Background Art

[0002] An air separation unit is a device used to separate different components in the air, and is usually used to produce industrial gases such as nitrogen, oxygen, and argon. In industrial production, air separation units usually require a lot of energy to operate, so how to save energy and optimize and improve their application efficiency has become an important topic.

[0003] Conventional air separation units use 32°C circulating cooling water as the cooling medium. After the compressed air is cooled to 40°C, it enters a precooling system such as a precooling unit or an air cooling tower. The precooling system generally includes power equipment such as pumps and refrigeration units, which occupies a large area and has high operating costs for the entire air separation unit.

[0004] The existing air separation device directly vents the contaminated nitrogen gas without recycling it, which results in high energy consumption. Utility Model Content

[0005] In order to solve the above problems, the utility model provides an energy-saving air separation device with double-tower rectification and oxygenation towers, which saves floor space, has low operating costs, and can recover polluted nitrogen.

[0006] The technical solution of the utility model is to provide an energy-saving air separation device with a double-tower rectification and oxygenation tower, comprising an air filter, an air compressor and a purifier connected in sequence, the cooler of the air compressor is provided with a heat exchange channel for supplying 7-13°C industrial chilled water as a cooling medium, the purifier comprises two parallel adsorbers for facilitating alternating adsorption, the purifier is connected to a cold box, a heat exchanger is provided in the cold box, the air going out of the purifier enters the heat exchanger, the heat exchanger is connected to a lower tower, an upper tower is provided on the upper part of the condenser evaporator, and a lower tower is provided at the bottom of the condenser evaporator. The reflux liquid of the lower tower is provided by the condenser evaporator, a part of the gaseous nitrogen at the top of the lower tower enters the condenser evaporator to be condensed into liquid nitrogen as the reflux of the lower tower, and at the same time, the latent heat of condensation is released to evaporate the oxygen-rich liquid air / liquid oxygen on the other side of the condenser evaporator, which becomes the heat source for the distillation of the upper tower and the oxygen tower, and another part of the nitrogen is extracted from the lower tower, and the lower tower is connected to the auxiliary condenser evaporator. The nitrogen extracted from the lower tower is condensed in the auxiliary condenser evaporator as the reflux of the lower tower, and the remaining nitrogen is reheated by the heat exchanger and then leaves the cold box to enter the booster end of the expander.

[0007] Furthermore, the adsorber is a vertical container, and the adsorbent in the adsorber is a double-layer bed structure of molecular sieve and alumina.

[0008] Furthermore, the boosting end of the expander is connected to the nitrogen product outlet of the cold box, and the nitrogen can be pressurized to 0.8 MPa.

[0009] Furthermore, a channel is provided at the bottom of the upper tower for oxygen-rich liquid air to enter the oxygen tower for distillation. The oxygen-rich liquid air at the bottom of the upper tower enters the oxygen tower for distillation after throttling, and product oxygen-rich gas is obtained at the bottom of the oxygen tower.

[0010] Furthermore, the expansion end of the expander is connected to a heat exchanger, and the heat exchanger is used to reheat the contaminated nitrogen. The heat exchanger is provided with a channel connecting the purifier and the air compressor. A part of the reheated contaminated nitrogen is used as the regeneration gas and cold blowing gas of the purifier, and the rest of the contaminated nitrogen flows to the air compressor, is mixed with the raw air, and continues to the next process.

[0011] Furthermore, a channel is provided at the bottom of the oxygen tower for conveying oxygen-enriched gas with a purity of ≥90% to the heat exchanger.

[0012] Furthermore, the adsorbers are connected in parallel and then in series with an electric heater. When one adsorber is heated by the oxygen-rich gas from the cold box and then regenerated and cold-blown, the other adsorber performs adsorption, and the two adsorbers are automatically switched alternately.

[0013] Furthermore, the purifier is a skid-mounted structure.

[0014] Beneficial effects:

[0015] 1. The cooler of the conventional air compressor uses 32℃ circulating cooling water as the cooling medium. After the compressed air is cooled to 40℃, it enters the precooling system such as the precooling unit or air cooling tower. The precooling system usually contains power equipment such as pumps and refrigeration units, which occupies a large area and has a high overall cost. The cooler of the air compressor of the utility model uses 7-13℃ industrial chilled water as the cooling medium. After the compressed air is cooled to 15-20℃, it directly goes to the molecular sieve purification system, eliminating the precooling system, saving the floor space of the device, and reducing the operation and maintenance costs of the entire device by 10%.

[0016] 2. The utility model provides the nitrogen gas leaving the cold box as a nitrogen product by setting an expander to increase the pressure by 1 to 2 barg. Compared with the air separation unit without an expander, the air separation unit of the utility model also meets the nitrogen pressure required by the user, but the exhaust pressure of the air compressor is relatively low, which is equivalent to reducing the overall energy consumption of the device, and the power consumption can be reduced by 5%.

[0017] 3. In the utility model, after the reheated dirty nitrogen gas leaves the cold box, a part of it is used as the regeneration gas and cold blowing gas for the molecular sieve purification system, and the rest is not vented, but is led to the air compressor inlet pipe to merge with the raw air and continue to participate in the following process. After this part of the dirty nitrogen gas is mixed with the air, the load of the purifier adsorbent is reduced, the power consumption of the regeneration heating furnace is saved, and the power consumption can be reduced by 5%.

[0018] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0019] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the teachings of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or approximately identical component shown in each figure may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the utility model will be described by way of example and with reference to the accompanying drawings, in which:

[0021] Figure 1 It is a structural schematic diagram of an energy-saving air separation device with double-tower rectification and oxygenation towers according to the utility model.

[0022] Description of the accompanying drawings: 1-air filter; 2-air compressor; 3-purifier; 4-adsorber; 5-electric heater; 6-heat exchanger; 7-upper tower; 8-lower tower; 9-condenser evaporator; 10-oxygen tower; 11-auxiliary condenser evaporator; 12-expander DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0024] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0027] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0028] Conventional air separation units use 32°C circulating cooling water as the cooling medium. After the compressed air is cooled to 40°C, it enters a precooling system such as a precooling unit or an air cooling tower. The precooling system generally includes power equipment such as pumps and refrigeration units, which occupies a large area and has high operating costs for the entire air separation unit.

[0029] The existing air separation device directly vents the contaminated nitrogen gas without recycling it, which results in high energy consumption.

[0030] Based on the above questions, please refer to Figure 1 As shown, the utility model embodiment provides an energy-saving air separation device of a double-tower rectification and oxygenation tower 10, comprising an air filter 1, an air compressor 2 and a purifier 3 connected in sequence, the cooler of the air compressor 2 is provided with a pipeline for supplying 7-13°C industrial chilled water as a cooling medium, the purifier 3 comprises two parallel adsorbers 4, which are convenient for alternating adsorption, the purifier 3 is connected to a cold box, a heat exchanger 6 is provided in the cold box, the air out of the purifier 3 enters the heat exchanger 6, the heat exchanger 6 is connected to the lower tower 8, the upper part of the condenser evaporator is provided with the upper tower 7, and the bottom of the condenser evaporator 9 is provided with a lower tower 8. The reflux liquid of the lower tower 8 is provided by the condenser evaporator 9. A part of the gaseous nitrogen at the top of the lower tower 8 enters the condenser evaporator 9 and is condensed into liquid nitrogen as the reflux of the lower tower 8. At the same time, the latent heat of condensation is released to evaporate the oxygen-rich liquid air / liquid oxygen on the other side of the condenser evaporator 9, which becomes the heat source for the distillation of the upper tower 7 and the oxygen tower 10. Another part of the nitrogen is extracted from the lower tower 8. The lower tower 8 is connected to the auxiliary condenser evaporator 11. The nitrogen extracted from the lower tower 8 is condensed in the auxiliary condenser evaporator 11 as the reflux of the lower tower 8. The remaining nitrogen is reheated by the heat exchanger 6 and then leaves the cold box and enters the expander 12.

[0031] The cooler of the conventional air compressor 2 uses 32°C circulating cooling water as the cooling medium. After the compressed air is cooled to 40°C, it enters the pre-cooling system such as the pre-cooling unit or the air cooling tower. The pre-cooling system usually contains power equipment such as pumps and refrigeration units, which occupies a large area and has a high overall cost. The cooler of the air compressor 2 of the utility model uses 7-13°C industrial chilled water as the cooling medium. After the compressed air is cooled to 15-20°C, it directly goes to the molecular sieve purification system, eliminating the pre-cooling system, saving the floor space of the device, and reducing the operation and maintenance costs of the entire device by 10%.

[0032] In some embodiments of the present invention, the adsorber 4 is a vertical container, and the adsorbent in the adsorber 4 is a double-layer bed structure of molecular sieve and alumina, which can efficiently purify the air and ensure the adsorption effect.

[0033] In some embodiments of the utility model, the boosting end of the expander 12 is connected to the nitrogen product outlet of the cold box, and the nitrogen can be pressurized to 0.8MPa. By setting the expander 12, the nitrogen out of the cold box is pressurized by 1 to 2 barg and provided to the user as a nitrogen product. Compared with the air separation device without the expander booster, the air separation device of the utility model: the nitrogen pressure that meets the user's needs is also met, but the exhaust pressure of the air compressor 2 is relatively low, which is equivalent to reducing the overall energy consumption of the device, and the power consumption can be reduced by 5%.

[0034] In some embodiments of the utility model, the bottom of the upper tower 7 is provided with a channel for oxygen-enriched liquid air to enter the oxygen tower 10 for rectification. The oxygen-enriched liquid air at the bottom of the upper tower 7 enters the oxygen tower 10 for rectification after throttling, and the product oxygen-enriched gas is obtained at the bottom of the oxygen tower 10. The purity of the oxygen-enriched gas produced at the bottom of the oxygen tower 10 is ≥90%.

[0035] In some embodiments of the present invention, the expander 12 is connected to the heat exchanger 6, and the heat exchanger 6 is used to reheat the contaminated nitrogen gas. The heat exchanger 6 is provided with a channel connecting the purifier 3 and the air compressor 2. A part of the reheated contaminated nitrogen gas is used as the regeneration gas and cold blowing gas of the purifier 3, and the rest of the contaminated nitrogen gas flows to the air compressor 2, mixes with the raw air, and continues to the next process.

[0036] In some embodiments of the present invention, a channel is provided at the bottom of the oxygen tower 10 for transporting oxygen-enriched oxygen with a purity of ≥90% to the heat exchanger 6 .

[0037] In some embodiments of the utility model, the adsorber 4 is connected in parallel and then in series with an electric heater 5. When one adsorber 4 is heated by the oxygen-rich gas from the cold box and then regenerated and cold-blown, the other adsorber 4 performs adsorption. The two adsorbers 4 are automatically switched alternately, which greatly improves the working efficiency.

[0038] In some embodiments of the present invention, the purifier is a skid-mounted structure, and the pipelines of the two adsorbers are integrated, which eliminates the complicated process of on-site installation of valves, instruments, and pipelines, and saves the floor space of the device.

[0039] The working principle of the utility model is as follows: after the raw air is filtered by the air filter 1 for impurities, it is compressed to 0.8MPa(G) by the air compressor 2, cooled to about 20℃ by the chilled water, and enters the purifier 3. The air is freed of H2O, CO2, C2H2 and other hydrocarbons in the purifier 3, and the dew point of the air leaving the purifier is lower than -65℃, and the CO2 content is less than 1ppm. The adsorber 4 of the purifier 3 is composed of two vertical containers. When one adsorber 4 is regenerated and cold-blown after being heated by the heater with the oxygen-rich gas from the cold box, the other adsorber 4 is adsorbed, and the two adsorbers 4 are automatically switched. The adsorbent adopts a molecular sieve and alumina double-layer bed structure.

[0040] The processed air from the purifier 3 enters the heat exchanger 6 in the cold box, and is cooled to a dew point by the refluxed product oxygen-rich gas, nitrogen gas, and polluted nitrogen gas and other low-temperature gases in the heat exchanger 6. The air close to the dew point enters the lower tower 8, and exchanges heat and mass with the reflux liquid of the lower tower 8 in the lower tower 8, and pure nitrogen is obtained at the top of the lower tower 8, and oxygen-rich liquid air is obtained at the bottom of the lower tower 8.

[0041] The reflux liquid of the lower tower 8 is provided by the condenser evaporator disposed between the lower tower 8 and the upper tower 7. A part of the gaseous nitrogen at the top of the lower tower 8 enters the condenser evaporator 9 to condense into liquid nitrogen as the reflux of the lower tower 8, and at the same time releases the latent heat of condensation to evaporate the oxygen-rich liquid air / liquid oxygen on the other side of the condenser evaporator 9, which becomes the heat source for the distillation of the upper tower 7 and the oxygen tower 10; another part of the nitrogen is extracted from the lower tower 8, condensed in the auxiliary condenser evaporator 11 as the reflux of the lower tower 8; the rest of the nitrogen is reheated by the heat exchanger 6 and then leaves the cold box, enters the boosting end of the expander 12, boosts the pressure to 0.8MPa(G) and is sent to the user.

[0042] The oxygen-rich liquid air at the bottom of the upper tower 7 is throttled and then enters the oxygen tower 10 for rectification, and the product oxygen-rich air is obtained at the bottom of the oxygen tower 10. As the product of the rectification, the oxygen-rich air with a purity of ≥90% is produced at the bottom of the oxygen tower 10, and is reheated by the heat exchanger 6 and then discharged from the cold box.

[0043] The dirty nitrogen gas at the top of the upper tower 7 enters the expander 12 for expansion, providing the required cooling capacity for the air separation unit. After expansion, the dirty nitrogen gas and air are reheated in the heat exchanger 6 and then discharged from the cold box. Part of the reheated dirty nitrogen gas is used as the regeneration gas and cold blowing gas of the purifier 3, and the rest is not vented, but is led to the air compressor inlet pipeline to merge with the raw air and continue to participate in the next process.

[0044] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. An energy-saving air separation device with a double-tower rectification and oxygenation tower, characterized in that: The invention comprises an air filter, an air compressor and a purifier connected in sequence. The cooler of the air compressor is provided with a heat exchange channel for supplying 7-13°C industrial chilled water as a cooling medium. The purifier comprises two adsorbers connected in parallel for facilitating alternating adsorption. The purifier is connected to a cold box, and a heat exchanger is provided in the cold box. The air discharged from the purifier enters the heat exchanger, and the heat exchanger is connected to a lower tower. An upper tower is provided on the upper part of the condenser evaporator, and a lower tower is provided at the bottom of the condenser evaporator. The reflux liquid of the lower tower is supplied by the condenser evaporator. It is provided that part of the gaseous nitrogen at the top of the lower tower enters the condenser evaporator to be condensed into liquid nitrogen as the reflux of the lower tower, and at the same time releases the latent heat of condensation to evaporate the oxygen-rich liquid air / liquid oxygen on the other side of the condenser evaporator, which becomes the heat source for the distillation of the upper tower and the oxygen tower, and another part of the nitrogen is extracted from the lower tower, and the lower tower is connected to the auxiliary condenser evaporator, and the nitrogen extracted from the lower tower is condensed in the auxiliary condenser evaporator as the reflux of the lower tower, and the remaining nitrogen is reheated by the heat exchanger and then leaves the cold box and enters the boosting end of the expander.

2. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 1 is characterized in that: The adsorber is a vertical container, and the adsorbent in the adsorber is a molecular sieve and alumina double-layer bed structure.

3. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 1 is characterized in that: The boosting end of the expander is connected to the nitrogen product outlet of the cold box, and the nitrogen can be pressurized to 0.8 MPa.

4. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 1 is characterized in that: The bottom of the upper tower is provided with a channel for oxygen-rich liquid air to enter the oxygen tower for distillation. The oxygen-rich liquid air at the bottom of the upper tower enters the oxygen tower for distillation after throttling, and the product oxygen-rich air is obtained at the bottom of the oxygen tower.

5. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 1 is characterized in that: The expansion end of the expander is connected to a heat exchanger, and the heat exchanger is used to reheat the contaminated nitrogen. The heat exchanger is provided with a passage connecting the purifier and the air compressor. A part of the reheated contaminated nitrogen is used as the regeneration gas and cold blowing gas of the purifier, and the rest of the contaminated nitrogen flows to the air compressor, is mixed with the raw air, and continues to the next process.

6. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 4 is characterized in that: The bottom of the oxygen tower is provided with a channel for conveying oxygen-enriched oxygen with a purity of ≥90% to the heat exchanger.

7. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 2 is characterized in that: The adsorbers are connected in parallel and in series with an electric heater. When one adsorber is heated by the oxygen-rich gas from the cold box and then regenerated and cold-blown, the other adsorber performs adsorption, and the two adsorbers are automatically switched alternately.

8. The energy-saving air separation device of the double-tower rectification and oxygenation tower according to claim 1 is characterized in that: The purifier is a skid-mounted structure.

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