TW202117249A - Process and system for the cryogenic separation of air - Google Patents

Abstract

The invention relates to a method for low-temperature air separation, wherein an air separation system (100) is used which has a column system (10) comprising a high pressure column (11), which is supplied with condensed and cooled air, an intermediate pressure column (12), a low pressure column (13) and an argon column (14). A condensate is formed from head gas of the high pressure column (11), with the evaporation or partial evaporation of a first liquid which is taken from the high pressure column (11) and expanded to an evaporation pressure level between the first and the second pressure levels, and said condensate is fed back in part or in full to the high pressure column (11). Upon evaporation of the first liquid, a first gas is formed which is re-condensed in part or in full to the first pressure level and fed back into the high pressure column (11). The condensate is furthermore formed from the head gas of the high pressure column (11) according to the present invention with evaporation or partial evaporation of a second liquid which is taken from the intermediate pressure column (12) and condensed to the evaporation pressure level between the first and the second pressure levels, wherein a second gas is formed upon evaporation of the second liquid, which second gas is expanded in part or in full to the second pressure level and fed back into the intermediate pressure column (11). The invention also relates to a corresponding air separation system (100).

Description

Air cryogenic separation method and equipment

The present invention relates to a method for low-temperature separation of air and a corresponding equipment as described in the preamble of the independent claim.

The production of liquid or gaseous air products by low-temperature separation of air in air separation equipment is a conventional technology and is described in H.-W. Häring (Hrsg.), Industrial Gases Processing, Wiley-VCH, 2006, especially the paragraph 2.2.5, "Cryogenic Rectification".

The air separation equipment has a rectification tower system. Traditionally, the rectification tower system can be formed as a double-tower system, especially the classic Linde double-tower system, but can also be formed as a three-tower or multi-tower system. In addition to the rectification tower used to obtain liquid and/or gaseous nitrogen and/or oxygen (ie nitrogen and oxygen separation rectification tower), it can also be set up to obtain other air components (especially krypton, xenon and/or argon) And other rare gases) distillation tower. Among them, the terms "rectification" and "distillation" and "column" and "tower" or related compound terms are often used as synonyms.

The rectification towers of the above rectification tower system are operated at different pressure levels. The conventional two-tower system has a so-called high-pressure tower (also called a pressure tower, an intermediate pressure tower or a lower tower) and a so-called low-pressure tower (also called an upper tower). High-pressure towers usually operate at a pressure level of 4 bar to 7 bar, especially about 5.3 bar. Low pressure towers generally operate at a pressure level of 1 bar to 2 bar, especially about 1.4 bar. Under certain circumstances, higher pressure levels can also be used in the two rectification columns. The pressure given here and below is the absolute pressure at the top of the tower.

The terms high pressure tower, medium pressure tower, and low pressure tower will be used for certain towers of the air separation plant described in this article. These terms are intended to define the functions of the towers with the corresponding names, but they are not based on the narrow definitions adopted in the professional literature for the towers of traditional air separation plants. The meaning of these terms can be derived from the following description.

The present invention includes the cryogenic separation of air according to the so-called SPECTRA process, which is described in EP 2 789 958 A1 and further patent documents cited in the case. Simply put, it is a single-tower process. The SPECTRA process can achieve high nitrogen yields, and the original intention of its research and development is to obtain gaseous pressurized nitrogen. Here, the reflux sent to the tower (the only tower in the simplest case) is provided by condensing the gas at the top of the tower. So far it is still a normal operation. However, in the heat exchanger used to condense the top gas, the SPECTRA process uses fluid from the same tower for cooling. The part of the fluid used for cooling is returned to the rectification tower after being used for cooling and thus evaporating by means of a (cold) compressor. In this way, a very favorable air factor (Luftfaktor) can be achieved, that is, a large amount of product can be obtained for each amount of air.

In the technical solution of the SPECTRA process, other towers can be provided to obtain other air components such as pure or high-purity oxygen and argon. The result is a correspondingly improved SPECTRA process that includes additional towers, but it usually has the following commonality: like the classic SPECTRA process, the top gas of one tower is condensed while using the same tower fluid to form The liquid that is sent to the tower is refluxed, and the fluid evaporates in the process and is returned to the tower. The tower operating in this way can be the tower with the highest working pressure in the equipment, as is the case in the present invention.

CN 108036584 A discloses a method for producing high-purity nitrogen, oxygen and liquid oxygen by separating air at a low temperature and a corresponding equipment. Fully consider different factors to achieve stable, high-efficiency and energy-saving operation of the equipment.

The purpose of the present invention is to improve the SPECTRA process described above and below in more detail, especially in terms of energy consumption.

In this context, the present invention proposes a method for low-temperature separation of air and a corresponding equipment with the characteristics of independent claims. The technical solutions are subsidiary items and the topics explained below.

Before describing the features and advantages of the present invention, some basic principles of the present invention will be explained in detail and the terms used below will be defined.

The equipment used in the air separation plant is described in the cited professional literature, for example, in the Häring case (see above) in paragraph 2.2.5.6 "Apparatus". Taking into account the terminology used in the framework of this application, if the following definitions are not different, please refer to the cited professional literature.

In the terminology used in this case, liquids and gases may be rich or poor in one or several components, where "rich" can mean at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99%. Mole content, weight content or volume content, "lean" can represent up to 25%, 10%, 5%, 1%, 0.1% or 0.01% mole content, weight content or volume content. The term "dominant" can be equated with the definition of "rich". In addition, liquids and gases may enrich or deplete one or several components, where these terms refer to the initial liquid or initial gas content used to obtain the liquid or gas. Taking the initial liquid or initial gas as a reference, if the liquid or gas contains at least 1.1 times, 1.5 times, 2 times, 5 times, 10 times, 100 times or 1000 times the content of the corresponding component, it is called "enrichment". If the liquid or gas contains at most 0.9 times, 0.5 times, 0.1 times, 0.01 times or 0.001 times the content of the corresponding component, it is called "exhaustion". For example, if "oxygen", "nitrogen" or "argon" is mentioned, it also refers to a liquid or gas rich in oxygen or nitrogen but not necessarily composed of oxygen, nitrogen or argon only.

This application uses the terms "pressure level" and "temperature level" to characterize pressure and temperature. This is to show that precise pressure and temperature values are not required to describe the corresponding pressure and temperature in the corresponding equipment when implementing the concept of the present invention. However, these pressures and temperatures usually fluctuate within a specific range of 1%, 5%, or 10% above and below the average value. The corresponding pressure level and temperature level can be in a disjoint range or an overlapping range. For example, the pressure level especially includes unavoidable or foreseeable pressure loss. The same is true for temperature levels. The pressure level given here in bar is absolute pressure.

If "expander" is mentioned, it generally refers to a conventional turboexpander. In particular, these expanders can also be coupled with compressors. Such compressors may especially be turbo compressors. The corresponding combination of turbo expander and turbo compressor is also commonly referred to as a "turbocharger." In a turbocharger, the turbo expander and the turbo compressor are mechanically coupled, wherein the coupling can be achieved by means of the same rotation speed (for example, through a common shaft) or different rotation speed (for example, through its own transmission device). In this case, the term "compressor" is used generally. "Cold compressor" here refers to the compression of a fluid stream that is provided far below 0°C, especially below -50°C, -75°C or -100°C and to a temperature level below -150°C or -200°C machine. The corresponding fluid flow is especially cooled to the corresponding temperature level by the main heat exchanger (see below).

The "main air compressor" is used to compress all the air that is supplied to the air separation equipment and is separated there. In one or several other compressors, such as booster compressors, which can be set as appropriate, only a part of the air that has been compressed in the main air compressor is further compressed. Correspondingly, the "main heat exchanger" of the air separation plant is a heat exchanger used at least for cooling the predominant part of the air supplied to the air separation plant and separated there. This system takes place at least partly in the countercurrent of the material flow derived from the air separation plant. In the terminology used in this case, the material flow or "product" "derived" from the air separation equipment in this way is the fluid that no longer participates in the internal circulation of the equipment, but is continuously drawn from the internal circulation of the equipment.

The "heat exchanger" used within the framework of the present invention can adopt a conventional design. The heat exchanger is used for indirect heat transfer between at least two fluid streams, such as countercurrent to each other, for example between a hot pressurized air stream and one or several cold fluid streams, or a cool liquid air product Between one or several hot or hotter (or cooler as the case may be) fluid streams. The heat exchanger can be composed of a single heat exchanger section or several parallel and/or series heat exchanger sections (for example, one or several plate heat exchanger blocks). For example, it is a plate heat exchanger (Plate Fin Heat Exchanger in English). This type of heat exchanger has "channels", which are formed as separate fluid passages containing heat exchange surfaces, and are combined in parallel and separated by other channels to form a "channel group". The heat exchanger is characterized in that heat exchange is performed between two flow media (ie, at least one fluid flow to be cooled and at least one fluid flow to be heated) at a certain point in time in the heat exchanger.

"Condensing evaporator" refers to a heat exchanger capable of indirect heat exchange between the first condensing fluid stream and the second evaporating fluid stream. Any condensing evaporator has a liquefaction chamber and an evaporation chamber. The liquefaction chamber and the evaporation chamber have a liquefaction channel or an evaporation channel. The first fluid stream is condensed (liquefied) in the liquefaction chamber, and the second fluid stream is evaporated in the evaporation chamber. The evaporation chamber and the liquefaction chamber are composed of a group of channels that have a heat exchange relationship with each other.

Relative spatial terms such as "upper", "lower", "above", "below", "above", "below", "side", "side by side", "vertical" and "horizontal" are related here The spatial orientation of the tower of the air separation plant during normal operation. Two towers or other components are "stacked". Here, it means that the upper end of the lower device part of the two device parts and the lower end of the upper device part of the two device parts are at the same or lower ground height, and The projections of the two device parts in the horizontal plane overlap each other. In particular, two device parts are precisely stacked and arranged, which means that the axes of the two device parts extend on the same vertical straight line. However, the axes of the two device parts do not have to be stacked accurately and vertically, but can also be relatively offset, especially in the following situations: the smaller diameter of the two device parts (such as towers or tower parts) and the cooling system are required. The distance between the box plate sleeves is as large as the distance between another device component with a larger diameter and the cold box plate sleeve.

Like other low-temperature air separation methods, the aforementioned SPECTRA process (see below) also cools compressed and pre-purified air to a temperature suitable for rectification. The air can be partially liquefied by this. Next, the air is fed into the tower and where it is rectified in the aforementioned manner using the conventional SPECTRA process under the conventional pressure of a classic high-pressure tower to obtain a top product enriched with nitrogen relative to the atmosphere and a liquid relative to the atmosphere enriched with oxygen. The bottom product.

There is also a corresponding rectification column in the method proposed by the present invention, but it can be operated at a higher pressure, and the rectification column is here formed by a column called a high-pressure column. In addition, as a component of the air separation equipment used within the framework of the present invention, there is also a tower that operates as a low-pressure tower at a slight super-atmospheric pressure level and a tower between the high-pressure tower and the low-pressure tower. Medium-pressure tower operating at pressure level.

High-pressure tower, low-pressure tower and medium-pressure tower are mainly used to obtain oxygen-enriched nitrogen-enriched air products within the framework of the present invention (the top gas of the high-pressure tower is provided as a nitrogen pressurized product under corresponding pressure, and the bottom liquid can be extracted from the low-pressure tower As a pure oxygen product), the other towers used in the present invention are used to obtain argon, so they are called argon towers. Like the argon column in a classic air separation plant, this argon column takes a side stream from the low pressure column as feed. Among them, the term "side flow" refers to neither the bottom area (that is, the area below the bottom partition) nor the top area (that is, the area above the uppermost partition), but from both The fluid flow between (ie between two corresponding separating devices), such as separating trays or packing areas (Packungsbereich).

Air separation equipment with a double column system and a so-called crude argon column and a so-called refined argon column are usually used to obtain argon. An example is shown in Figure 2.3A of the Häring case (see above), and is described in the paragraph "Rectification in the Low-pressure, Crude and Pure Argon Column" from page 26 and in the paragraph from page 29 "Cryogenic Production of Pure Argon". If the relevant rectification column adopts the corresponding design, in principle, the argon column can also be discarded in the corresponding equipment. In this case, pure argon can be extracted from a crude argon column or a similar column that is generally slightly lower than the fluid traditionally transferred to the refined argon column, where the upper separation area is used to separate the remaining impurity components. The argon column used within the framework of the present invention can basically operate like a conventional crude argon column (or a crude argon column modified accordingly) in the prior art. The design of the corresponding argon column can especially be equipped with the corresponding number of trays. Features and advantages of the present invention

The present invention generally proposes a method for low-temperature air separation, in which an air separation device with a tower system is used, and the tower system includes a high-pressure tower, an intermediate-pressure tower, a low-pressure tower, and an argon tower. As mentioned above, the operation mode of the high-pressure tower used within the framework of the present invention is basically the same as that used in the traditional SPECTRA process.

The high-pressure tower, medium-pressure tower and low-pressure tower used within the framework of the present invention are further characterized by their respective working pressure levels. The specific value will be explained below. Within the framework of the present invention, the high-pressure tower operates at a pressure level much higher than that of the traditional high-pressure tower. Within the framework of the present invention, the nitrogen product can be extracted from the high-pressure tower in this way, and the nitrogen product can be directly provided at the corresponding pressure level, and then no cold compression or hot compression is required. Therefore, within the framework of the present invention, from the perspective of equipment and safety technology, the provision of corresponding nitrogen pressurized products is much easier than that of classic air separation equipment.

Therefore, the present invention benefits from the advantages of the conventional SPECTRA process. However, different from the traditional SPECTRA process, the present invention also realizes the production of oxygen-enriched air products and argon-enriched air products, for which the aforementioned other towers are required.

Generally speaking, within the framework of the present invention, the high-pressure tower operates at a first pressure level, the medium-pressure tower operates at a second pressure level lower than the first pressure level, and the low-pressure tower operates at a lower pressure level than the first and second pressure levels. Run on the third pressure level. Among them, the medium-pressure tower and the low-pressure tower can also be combined in the traditional double-tower style of the air separation equipment within the framework of the present invention. Among them, the heat exchanger for condensing the gas at the top of the medium-pressure tower can also be arranged in the bottom layer of the low-pressure tower.

The double-tower system used in traditional air separation equipment is composed of a high-pressure tower and a low-pressure tower, and the high-pressure tower in the aforementioned sense is arranged below the low-pressure tower. Within the framework of the present invention, the same applies to medium-pressure towers (arranged below the low-pressure tower) and low-pressure towers (arranged above the intermediate-pressure tower). However, the present invention is limited to this type of arrangement of double columns or double towers. To be precise, the two towers (medium-pressure tower and low-pressure tower) can also be formed into two separate towers. The condenser that connects the medium-pressure tower and the low-pressure tower by heat exchange can also be arranged outside the low-pressure tower.

Within the framework of the present invention, the medium-pressure tower is usually operated at a pressure level consistent with the traditional high-pressure tower of the air separation plant. The working pressure level of the low-pressure tower is also consistent with the conventional working pressure level of the classic low-pressure tower.

The present invention constitutes a variant of the conventional SPECTRA process. Within the framework of the present invention, the gas at the top of the high-pressure column forms a condensate while evaporating or partially evaporating the first liquid, which is extracted from the high-pressure column and expanded to the medium. The evaporation pressure level between the first and second pressure levels. The evaporating pressure level can usually be 3 bar to 7 bar. Therefore, the expansion is carried out in the form of a partial expansion to a superatmospheric pressure level, allowing further expansion to a lower pressure level.

The formed condensate is partially or completely returned to the high pressure column as reflux. A part of the corresponding condensate can also be derived from the corresponding equipment as a liquid nitrogen-enriched air product. When the first liquid is evaporated, a first gas is formed, which is partially or completely recompressed to the first pressure level and sent back to the high pressure column. This is an important feature of the SPECTRA process. The first liquid extracted from the high-pressure column is processed accordingly within the framework of the present invention. The first liquid may specifically be the liquid extracted from the high-pressure column at some theoretical or actual trays above the bottom layer, in other words, from the high-pressure column in the form of side flow. Liquid discharged from the tower.

As disclosed in the patent documents cited above, the classic SPECTRA process processes other material streams from the high-pressure tower accordingly, which is usually not the case within the framework of the present invention. Within the framework of the present invention, the top gas of the high-pressure column forms a top condensate when the second liquid is evaporated or partially evaporated. The second liquid is extracted from the medium-pressure column and compressed to a level between the first and second pressure levels. The evaporation pressure level between the time. In the process of condensing the top gas, a second gas is formed when the second liquid is evaporated, and the second gas is partially or completely expanded to a second pressure level and sent back to the medium pressure column.

That is, the present invention forms two material cycles, one is the material cycle experienced by the first liquid from the high pressure column, and the second is the second material cycle experienced by the liquid from the medium pressure column. The first cycle is still consistent with the SPECTRA process, and the second cycle used in the present invention is novel compared to the prior art.

In order to bring the second liquid from the medium pressure column to the vaporization pressure level, a pump is usually provided, which applies pressure to the second liquid in a liquid state. The first liquid from the high-pressure column is usually a side stream from the high-pressure column, and the second liquid from the medium-pressure column is formed when the bottom liquid is used.

The second liquid from the medium-pressure tower does not have to be all returned to the medium-pressure tower. In a technical solution of the present invention (this will be described with reference to formula 1 in the attached drawings), the following is set: part of the second gas formed when the second liquid is evaporated is not sent to the medium pressure tower, but In particular, it is further expanded in an expander coupled with a compressor, and finally exported from the air separation device, the compressor is used to compress the first gas.

Regarding the function of the tower used in the present invention, it is emphasized once again: to provide the high-pressure tower with compressed and cooled input air. This does not rule out that other towers are also provided with air accordingly; but in the case of the high-pressure tower used in the present invention, this is always the case.

In the advantageous technical solution of the present invention, the bottom liquid from the high-pressure column expands from the first pressure level to the second pressure level and is sent to the medium-pressure column. Even the traditional SPECTRA process using other towers is generally not the case; to be precise, in such traditional processes, the corresponding material stream formed by using the bottom liquid will also be used as a coolant to condense the top gas of the corresponding tower.

In the advantageous technical solution of the method proposed by the present invention, the side stream of the liquid extracted from the high-pressure column is partially or completely expanded from the first pressure level to the second pressure level, and is sent under the condition that the liquid part and the gas part are formed. Go for phase separation treatment. Among them, the liquid part can be separated in particular partly or completely in a low pressure column, and the gas part can be separated partly or completely in a medium pressure column. A special technical solution of this process includes: the side stream extracted from the high pressure column or the part of the side stream expanded from the first pressure level to the second pressure level is sent to the medium pressure column for phase separation, in the medium pressure column , The liquid part is deposited in a liquid-blocking container or deposited on a separating tray, and the gas part is directly transformed into a gaseous phase. In this way, the liquid part can be partially or completely extracted from the medium pressure column again, and sent to the low pressure column, and the liquid part is separated in the low pressure column. The gas part remains in the medium pressure column and is separated there.

As mentioned above, within the framework of an advantageous technical solution of the present invention, the argon column used basically works in the manner of a traditional argon column of an air separation plant. This means that within the framework of the present invention, the argon-enriched side stream is also extracted from the low pressure column, wherein at least a part of the second stream from the low pressure column is sent to the argon column. The argon-enriched side stream particularly has a higher argon content than the side stream present at the top or bottom of the low pressure column. This side stream is extracted from the low pressure column on a favorable area basically known in the field of air separation plants.

Within the framework of the present invention, it is advantageous to transfer only a part of the side stream to the argon column instead of directly sending the side stream to the argon column. This is advantageously achieved by providing the side stream partially or completely to the oxygen column, forming a stream enriched in argon relative to the side stream in the oxygen column, and sending this stream partially or completely to the argon column In this way, part of the side stream from the low pressure column is sent to the argon column.

Within the framework of an advantageous technical solution of the present invention, the argon column works with a top condenser. This only means that the gas at the top of the argon column forms a condensate with partial vaporization of the liquid, and this condensate is partly or completely returned to the argon column. Among them, the liquid in which the top gas of the argon column forms a condensate due to partial evaporation is advantageously extracted from the medium pressure column within the framework of the present invention, which is another fundamental difference from the conventional process. As an alternative, the gas formed during partial evaporation and/or the remaining liquid during partial evaporation can be partially or completely sent to the low-pressure column.

It is basically known from the SPECTRA process that an expander coupled to a compressor can be used within the framework of the present invention. Therefore, a compressor can be used to recompress the first gas or the portion of the first gas that is recompressed to the first pressure level and sent back to the high-pressure tower. The compressor is mechanically coupled with the expander, and the expander is used for In order to expand the other part of the second gas that has not been sent back to the medium pressure column.

The present invention also relates to an air separation equipment. For specific features, please refer to the corresponding independent claim. Regarding the further features, technical solutions and preferred implementations of this type of equipment, please refer to the above description of the method of the present invention and its advantageous technical solutions. Such air separation equipment is advantageously used to implement the methods described above with different technical solutions.

The present invention will be described in detail below with reference to the accompanying drawings, which illustrate the air separation equipment according to the technical solution of the present invention.

FIG. 1 illustrates an air separation device according to a particularly preferred embodiment of the present invention in the form of a highly simplified schematic diagram of the process flow, which is indicated by 100 as a whole.

The air separation plant 100 illustrated in FIG. 1 penetrates the filter 101 and sucks air from the atmosphere generally designated A here by the main air compressor 102, which in particular adopts a multi-stage design and With intercooler. After being recooled in the heat exchangers 103 and 104, the input air flow a formed in this way is cooled in a direct contact cooler 105 operating with water W, and then supplied to the adsorption device 106.

After the input air stream a is dried in this way and carbon dioxide is substantially removed, the input air stream is provided to the main heat exchanger 107. The input air flow a is taken from the main heat exchanger near the cold end of the main heat exchanger, and in the example illustrated here, the input air flow is basically provided to the high-pressure tower 11 of the tower system as a whole indicated by 10 . The parts not separately shown in the figure can be branched out via a bypass when needed.

A part of the top stream b of the high-pressure column 11 can be led out from the air separation plant 100 as a gaseous pressurized nitrogen product in the form of a stream c. The corresponding pressurized nitrogen products are again labeled C1 and C2. In the example illustrated here, the part of the top stream b that is not led out from the air separation device in this way is provided to the heat exchanger or condenser 108 in the form of the material stream d, and is basically Condensation. A part of the corresponding condensate can be returned to the high-pressure column 11 as a liquid reflux in the form of a stream e. The other part is extracted in the form of flushing stream P. If necessary, liquid nitrogen E can also be fed into the equipment 100 in the manner illustrated here. The other part can be supercooled in the supercooler 109 in the form of a material flow f and discharged from the device as a liquid nitrogen product F. The part used for supercooling and branched out downstream of the subcooler 109 is led out from the equipment as residual gas, which will be explained below with reference to other material flows.

In the illustrated example, the bottom stream g of the high-pressure tower 11 is used to feed the medium-pressure tower 12 of the tower system 10. To this end, the bottom stream g is cooled in the main heat exchanger 107 and then sent to the medium pressure column above the bottom layer or above some of the divided trays located above the bottom layer.

The side stream h from the high-pressure column 11 is used as a further feed for the medium-pressure column, and the side stream expands into the medium-pressure column 12. The gas formed in this way remains in the medium pressure column 12; the liquid in the form of the material stream i is at least partially extracted from the medium pressure column 12 directly below the feed point, and passes through the subcooler 110 before being sent into The low pressure tower 13 of the tower system 10.

The side stream k extracted from the high pressure column is first used to operate the heat exchanger 108. This side stream is further cooled in the main heat exchanger 107 before being supplied to the heat exchanger 108. Partial expansion occurs at this time. Downstream of the heat exchanger 108, a portion of the corresponding vaporized fluid may be discharged into the atmosphere A. The other part (here still shown as the material flow k) is optionally recompressed in the compressor 111 after being combined with other material flows, which is mechanically coupled to the expander 112 and is further reduced by the dissipative brake brake. The material stream k can be fed into the high-pressure column 11 again in this way. The further cooling capacity for the heat exchanger 108 is provided by the bottom stream I of the medium pressure column 12. To this end, the bottom flow is brought to the required pressure level in the heat exchanger 108 by the pump 113.

After the material stream I has evaporated in the heat exchanger 108, it is heated in the main heat exchanger 107 in the form of a first partial stream m and is at least partially expanded in the expander 112. This material flow will then be led out of the device, in particular together with the part of the top stream b from the high-pressure column that is used for cooling in the subcooler 109. The other part n of the bottom stream evaporated in the heat exchanger 108 from the medium pressure column 12 is returned to the medium pressure column 12.

The air separation device 100 also includes an argon column 14, the argon column is finally fed by the low pressure column 13 or a side stream o extracted from the low pressure column 13 as the feed. However, in the illustrated example, the side stream o is not directly transferred to the argon column 14, but first transferred to the upper part 15a of the oxygen column designated by 15 as a whole. In the upper part 15a, the stream o or the fluid transferred in this way to the upper part 15a is further enriched with argon and depleted of oxygen, so that the corresponding stream p can be transferred from the top of the upper part 15a to the argon column 14. The bottom liquid from the argon column 14 is returned to the upper part 15a of the oxygen column by a pump not separately labeled here.

The oxygen tower 15 including the upper part 15a and the lower part 15b is operated by the bottom evaporator 151. The bottom evaporator 151 and the bottom evaporator 131 arranged in the bottom of the low pressure column 13 are respectively used to condense the top gas of the medium pressure column 12, and the top gas is extracted from the medium pressure column in the form of the material flow q. The condensing part, which is not separately and individually shown here, is basically used as the reflux sent to the medium-pressure column 12 and the low-pressure column 13.

A material stream r is drawn from the top of the low-pressure column 13, and the material stream is heated in the form of impure oxygen and then discharged into the atmosphere or used for other purposes.

The oxygen streams s and t are extracted from the bottom of the low-pressure column 13, where the oxygen stream s is internally compressed in a pump not separately labeled and can be used to provide the corresponding internally compressed product S. The oxygen stream t can then be heated and can be discharged from the device or into the atmosphere. As shown here in the form of the associated symbol X, a part can be returned to the low pressure column 13.

The argon tower 14 whose top is cooled by the top condenser 141 can be used to provide a liquid argon stream u, which can be provided as an internally compressed argon product U after being temporarily stored in the storage tank system T, for example. A part of it can also be stored in the storage tank T1 for a long time and discharged from the equipment in a liquid state, for example.

In the example illustrated here, the material stream v is used to cool the top condenser 141 of the argon column 14. The material stream is extracted from the medium pressure column 12 in liquid form at some trays above the bottom layer and sent to the argon condenser 141 in the evaporation chamber. The evaporated and unevaporated parts here can be returned to the low pressure column as shown in the figure.

As shown here in the form of corresponding fluid arrows, the upper part 15a and the lower part 15b of the oxygen tower 15 are fluidly coupled to each other. The argon-depleted and oxygen-enriched fluid is transferred from the upper part 15a to the lower part 15b and is further rectified there. In this way, the pure oxygen stream w can be extracted from the bottom of the oxygen tower 15 or from the lower part of the oxygen tower, and the pure oxygen stream can also be discharged as a high-purity oxygen product W via the corresponding storage tank system t2 or t3 to be separated from the air in the form of internal compression. Equipment 100. The other material flows illustrated here and their specific processing in the air separation plant 100 can be directly obtained from the drawings.

10: Tower system 11: High-voltage tower 12: Medium pressure tower 13: Low pressure tower 14: Argon Tower 15: Oxygen Tower 15a: upper part 15b: lower part 100: Air separation equipment 101: filter 102: main air compressor 103: Heat Exchanger 104: heat exchanger 105: Direct contact cooler 106: Adsorption device 107: main heat exchanger 108: Condenser/heat exchanger 109: Subcooler 110: Subcooler 111: Compressor 112: Expander 113: Pump 131: bottom evaporator 141: Top condenser/argon condenser 151: bottom evaporator A: Atmosphere a: Input air flow b: top stream C1: Pressurized nitrogen products C2: Pressurized nitrogen products c: material flow d: Material flow E: Liquid nitrogen e: material flow F: Liquid nitrogen products f: material flow g: underlying stream h: side stream I: bottom flow/material flow i: material flow k: side flow/material flow m: first diversion n: another part o: side flow/material flow P: flush flow p: material flow q: material flow r: material flow S: Internal compression product s: oxygen flow T: storage tank system T1: storage tank t: oxygen flow t2: storage tank system t3: storage tank system U: Internally compressed argon product u: liquid argon flow v: material flow W: water/high purity oxygen product w: pure oxygen flow X: Associate

[Figure 1] The air separation plant according to the technical solution of the present invention is illustrated in the form of a simplified process flow diagram.

10: Tower system

11: High-voltage tower

12: Medium pressure tower

13: Low pressure tower

14: Argon Tower

15: Oxygen Tower

15a: upper part

15b: lower part

100: Air separation equipment

101: filter

102: main air compressor

103: Heat Exchanger

104: heat exchanger

105: Direct contact cooler

106: Adsorption device

107: main heat exchanger

108: Condenser/heat exchanger

109: Subcooler

110: Subcooler

111: Compressor

112: Expander

113: Pump

131: bottom evaporator

141: Top condenser/argon condenser

151: bottom evaporator

A: Atmosphere

a: Input air flow

b: top stream

C1: Pressurized nitrogen products

C2: Pressurized nitrogen products

c: material flow

d: Material flow

E: Liquid nitrogen

e: material flow

F: Liquid nitrogen products

f: material flow

g: underlying stream

h: side stream

I: bottom flow/material flow

i: material flow

k: side flow/material flow

m: first diversion

n: another part

o: side flow/material flow

P: flush flow

p: material flow

q: material flow

r: material flow

S: Internal compression product

s: oxygen flow

T: storage tank system

T1: storage tank

t: oxygen flow

t2: storage tank system

t3: storage tank system

U: Internally compressed argon product

u: liquid argon flow

v: material flow

W: water/high purity oxygen product

w: pure oxygen flow

X: Associate

Claims (9)

A method of low-temperature separation of air, in which, -Use an air separation plant (100) with a tower system (10), which includes a high-pressure tower (11), an intermediate-pressure tower (12), a low-pressure tower (13) and an argon tower (14), -The high-pressure tower (11) operates at a first pressure level, the medium-pressure tower (12) operates at a second pressure level lower than the first pressure level, and the low-pressure tower (13) operates at a pressure lower than the second pressure level. The pressure level runs on the third pressure level, -Provide compressed and cooled air for the high-pressure tower (11), and -The top gas of the high-pressure tower (11) forms a condensate when the first liquid is evaporated or partially evaporated, and the first liquid is extracted from the high-pressure tower (11) and expanded to a level between the first and second pressures And the condensate is partially or completely returned to the high-pressure column (11), wherein the first gas is formed when the first liquid is evaporated, and the first gas is partially or completely recompressed to the The first pressure level and sent back to the high-pressure tower (11), It is characterized by -The gas at the top of the high-pressure tower (11) forms a condensate when the second liquid is evaporated or partially evaporated, and the second liquid is extracted from the medium-pressure tower (12) and reaches between the first and second pressure levels Between the evaporation pressure level, and -When the second liquid is evaporated, a second gas is formed, and the second gas is partially or completely expanded to the second pressure level and sent back to the medium pressure tower (11). The method according to claim 1, wherein the bottom liquid from the high pressure column (11) expands from the first pressure level to the second pressure level and is sent to the medium pressure column (12). The method according to claim 1 or 2, wherein the side stream of the liquid extracted from the high pressure column (11) is partially or completely expanded from the first pressure level to the second pressure level, and the liquid part and the gas are formed In some cases, it is sent to a phase separation treatment, wherein the liquid is partially or completely separated in the low pressure column (13), and the gas is partially or completely separated in the medium pressure column (12). The method according to claim 3, wherein the side stream extracted from the high pressure column (11) or the part of the side stream expanded from the first pressure level to the second pressure level is sent to the medium pressure column (12) Perform phase separation, in which the liquid part is partially or completely extracted from the medium pressure column (12) again, and sent to the low pressure column (13), and the gas part is left in the medium pressure column (13). Tower (12). The method according to any one of the preceding claims, wherein the argon-enriched side stream is extracted from the low pressure column (13), wherein at least a part of the side stream from the low pressure column (13) is sent to the argon Tower (14). The method according to claim 5, wherein a part of the side stream from the low pressure column (13) is sent to the argon column (14) in the following manner: the side stream is partially or completely supplied to the oxygen column (15) A material stream enriched with argon relative to the side stream is formed in the oxygen column, and the material stream is partially or completely transferred to the argon column (14). The method according to any one of the preceding claims, wherein the top gas of the argon column (14) forms a condensate in the case of partial evaporation of liquid, and the condensate is partially or completely returned to the argon column (14) ), wherein the liquid that forms the condensate from the top gas of the argon column (14) due to partial evaporation is extracted from the medium-pressure column (12), or among them, the gas and/or part of the gas formed during partial evaporation The liquid remaining during evaporation is partially or completely sent to the low pressure column (13). The method according to any one of the preceding claims, wherein a compressor is used to recompress the first gas or the first gas to the first pressure level and send it back to the high-pressure tower (11) Part of the recompression is performed, and the compressor is mechanically coupled with an expander, and the expander is used to expand another part of the second gas that has not been sent back to the intermediate pressure column (11). An air separation equipment (100) has a tower system (10), the tower system includes a high pressure tower (11), an intermediate pressure tower (12), a low pressure tower (13) and an argon tower (14), wherein the air separation equipment ( 100) is constructed to be used for: -Operate the high-pressure tower (11) at a first pressure level, operate the medium-pressure tower (12) at a second pressure level lower than the first pressure level, and operate at a pressure lower than the first and second pressure levels Operate the low pressure tower (13) at the third pressure level, -Provide compressed and cooled air for the high-pressure tower (11), -In the case of evaporating or partially evaporating the first liquid, the top gas of the high-pressure tower (11) is formed into a condensate, and the first liquid is extracted from the high-pressure tower (11) and expanded to a pressure between the first and second pressures The evaporation pressure level between the levels, and the condensate is partially or completely returned to the high-pressure column (11), and the first gas formed when the first liquid is evaporated is partially or completely recompressed to the first pressure Level and sent back to the high-pressure tower (11), It is characterized by components, which are constructed for: -Evaporate or partially evaporate the second liquid so that the top gas of the high-pressure column (11) forms a condensate, the second liquid is extracted from the medium-pressure column (12) and compressed to a level between the first and second pressures The evaporation pressure level between the evaporating pressure level, the second gas formed when evaporating the second liquid is partially or completely expanded to the second pressure level and sent back to the medium pressure tower (11).

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