EP2841858A2

EP2841858A2 - Transportable package having a cold box, low-temperature air separation plant and method for producing a low-temperature air separation plant

Info

Publication number: EP2841858A2
Application number: EP13716961.1A
Authority: EP
Inventors: Stefan Lochner; Augustin Rampp
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2012-04-27
Filing date: 2013-04-09
Publication date: 2015-03-04
Also published as: WO2013159868A2; CN104272046A; DE102012008415A1; WO2013159868A3; US20150096327A1

Abstract

The invention relates to a transportable package for a low-temperature air separation plant which has a main heat exchanger (2a, 2b, 2c) for cooling feed air (1) and a double column (5) for separating the cooled feed air, wherein the double column (5) has a high-pressure column and a low-pressure column that are arranged above one another. The transportable package has a cold box (20, 400), in the interior of which accessories of the double column (5), in particular pipelines (7, 11, 12) and valves, are arranged, but not the double column and not the main heat exchanger, wherein the transportable package has connections for joining the pipelines to the double column and to the main heat exchanger. Moreover the invention relates to a low-temperature air separation plant and to a method for producing a low-temperature air separation plant using this transportable package.

Description

description

Transportable package comprising a cold box, cryogenic air separation plant and method of manufacturing a cryogenic air separation plant

The invention relates to a transportable package for a cryogenic air separation plant according to the preamble of patent claim 1.

Such modular transportable units making up an air separation plant are generally referred to as a "packaged unit" (PU) and are described, for example, in US 2007199344 A1 or US 5461871.

Methods and devices for cryogenic separation of air in general are known, for example, from Hausen / Linde, Tiefftemperaturtechnik, 2nd edition 1985, Chapter 4 (pages 281 to 337). The distillation column system in the invention comprises a two-column system for nitrogen-oxygen separation with high-pressure column and low-pressure column, which are arranged one above the other, (a so-called double column). Between the two columns, a main capacitor is usually arranged, which is designed as a condenser evaporator and are in heat exchanging connection via the high pressure column and low pressure column. It may, in addition to the columns for nitrogen-oxygen separation further devices for recovering high purity products and / or other air components, in particular of noble gases have, for example an argon production with crude argon column and optionally with pure argon column and / or a krypton-xenon recovery.

The term "condenser-evaporator" refers to a heat exchanger in which a first condensing fluid stream undergoes indirect heat exchange with a second evaporating fluid stream. Each condenser evaporator has a

Liquefaction room and an evaporation room on that off

Condensing passages or evaporation passages exist. In the liquefaction space, the condensation (liquefaction) of a first fluid flow is performed, in the evaporation space the evaporation of a second fluid flow. Evaporation and liquefaction space are formed by groups of passages that are in heat exchange relationship with each other.

A "main heat exchanger" serves to cool on-air in indirect

Heat exchange with recycle streams from the distillation column system. It can be composed of a single or several parallel and / or serially connected

Heat exchanger sections may be formed, for example, from one or more plate heat exchanger blocks. A "cold box" is here understood to mean an insulating casing which comprises a heat-insulated interior completely with outer walls; in the interior of equipment to be isolated parts are arranged, for example, one or more

Separation columns and / or heat exchangers. The insulating effect can be through

corresponding configuration of the outer walls and / or be effected by the filling of the gap between system parts and outer walls with an insulating material. In the latter variant, a powdery material such as perlite is preferably used. Both the distillation column system for nitrogen-oxygen separation of a cryogenic air separation plant and the main heat exchanger and other cold plant parts must be enclosed by one or more cold boxes. The outer dimensions of the coldbox usually determine the transport dimensions of the package in prefabricated systems. The "height" of a coldbox is understood to mean the dimension in the vertical direction in relation to the orientation of the coldbox in plant operation; the "cross section" is the area perpendicular to it (horizontal). During transport, the height of the coldbox determines the transport length, the cross section the transport height and width.

PUs are manufactured in a factory that is regularly far away from the site of the air separation plant. This allows extensive prefabrication and thus a minimization of the manufacturing effort at the site, where often prevail much more difficult conditions. The prefabricated package or several prefabricated packages are transported from the factory to the site, the coldbox package with one or more Trennsäuleh in horizontal arrangement. There are restrictions on the length and width of the packages for such transports. So far, this technology has only been used in medium-sized air separation plants, if the columns are at least partially lined up with ordered packings equipped, because packed columns usually require a greater height than floor columns. Larger systems with packed columns are created with a lower degree of prefabrication; In particular, the coldbox is only on

Site built. Alternatively, only conventional

Rectified soils used; Although this allows a relatively high capacity per

Height of the columns, but causes a compared to pack columns noticeably increased energy consumption.

The invention has for its object to make a transportable package of the type mentioned so that it is particularly applicable for cryogenic air separation plants of a capacity for which no prefabrication of the column cold box as a whole was possible.

This object is solved by the characterizing features of claim 1.

In the invention, a special pipe box is used, which is prefabricated separately from the double column box and the main heat exchanger box. By outsourcing some, preferably all piping and valves, which are usually housed in the double column box, the column box can be made correspondingly narrower. Thus, a double column system with a relatively high capacity, which has hitherto forced a construction site production, can be prefabricated as PU. The coldbox of the transportable package designed as a piping box

Claim 1 contains at least one, preferably two or more or all of the components listed below:

- Raw oxygen line from the high pressure column in the low pressure column

- LIN line in front of the high pressure column or the main condenser to the low pressure column

- Liquid air line to the high pressure column and / or low pressure column

- GAN line from the head of the low-pressure column to the subcooling countercurrent and / or to the main heat exchanger - Unrecessickstoff-line from an intermediate point of the low pressure column to

Subcooling countercurrent and / or to the main heat exchanger

- Valve for the relaxation of raw LOX from the high pressure column in the

Low-pressure column

- LIN line from the high pressure column or the liquefaction space of the main condenser to the low pressure column

- Product line (s) from the double column to a supercooling countercurrent and / or main heat exchanger

- Any other line that goes over the subcooling countercurrent

- Each line leading from the argon box to the double column box and vice versa, for example the argon transition line (s) between low pressure column and

Rohargonsäule, the lines to and from the top condenser of the crude argon column and optionally to and from the top condenser of the pure argon column

- Valve (s) for each of the above lines, if applicable

For example, contains the cold box of the transportable package (the piping box) no separation column, so no crude argon column; no mixing column and so on.

Alternatively, the coldbox of the transportable package contains at least one argon column, ie a crude argon column or a pure argon column, a mixing column, a krypton-xenon column or a pure oxygen column. For example, the coldbox could contain the pure argon column as the only separation column; Since this is extremely slim and requires less space than the piping would still be considered as

Designate piping box (just with pure argon column).

The cold box of the portable package (the tubing box) of the invention may include a subcooling countercurrent.

A "subcooling countercurrent" is a unit separate from the main heat exchanger and serves to subcool one or more liquids from one of the columns of the nitrogen column distillation column distillation system or even from a mixing column countercurrent to one or more cold gaseous recycle streams or warm up. These reflux streams come from a column of the distillation column system (in the case of two-column or multi-column systems, generally from the low-pressure column). For example, in a subcooling countercurrent , cooled liquid streams (for example the low pressure column) are relaxed with the boiling point of a column at higher pressure (for ^'example, the high pressure column of a two-column system) into a lower pressure column as close as possible to the boiling point of which the lower Pressure level corresponds. The amount of steam (Flash) is minimized during the relaxation from the higher to the lower pressure. If liquid oxygen from a low-pressure column is fed through the subcooling countercurrent before being fed into a mixing column, it is heated inversely in order to come as close as possible to the boiling point below the - usually higher - pressure of the mixing column. In return, the cold return streams, which come from the columns at the tem- perature, are heated at the lower pressure. Since these streams go into the main heat exchanger, the process air in the high-pressure column is also warmer, that is, it is closer to the tau temperature. The proportion of pre-liquefied air is minimized. However, the cold box of the transportable package (the piping box) of the invention preferably contains no further heat exchanger for exchanging sensible heat beyond the supercooling countercurrent, in particular the heat exchanger

Main heat exchanger. However, the piping box can contain one or more heat exchangers for exchanging latent heat, for example a condenser-evaporator which serves for cooling or heating a separation column. Alternatively, the box contains no heat exchanger other than the subcooling countercurrent.

In a specific embodiment of the invention, the coldbox of the

portable package a Rohargonsäule having a top condenser, which is designed as a condenser-evaporator. The coldbox could be referred to in this case as combined piping and argon box.

The crude argon column can be formed in one part as shown in EP 377117 B2 = US Pat. No. 5,019,145 or in several parts, for example in two parts, as shown in EP 628777 B1 = US Pat. No. 5,426,946. In multi-part design, all parts are preferably arranged in the cold box. In addition, a pure argon column can be arranged in the combined pipeline and argon box. The invention also relates to a cryogenic air separation plant having a first transportable plant part, in which a double column is arranged, wherein the Poppelsäule has a high pressure column and a low pressure column, the

and a second cold box formed as part of a package according to any one of claims 1 to 5, wherein the pipes of the second cold box are connected to the double column and the argon system, if present.

The first transportable plant part comprises in a first variant a first

Coldbox, in which the double column is arranged.

In a second variant, the first part of the plant comprises the double column without a cold box, that is to say without an insulating covering. In this case, the completely pre-fabricated in the interior double column is transported as a substantially cylindrical component lying on the site and there provided with the insulating sheath (cold box).

The coldbox of the second part of the plant is referred to below as the "second coldbox". The system also preferably has a main heat exchanger box, another coldbox, in which the main heat exchanger is arranged. The

Main heat exchanger box is manufactured separately from the first and the second coldbox and transported to the place of installation. When argon is to be recovered and the second coldbox is not configured as an argon box, the cryogenic air separation plant may also include a third coldbox containing a crude argon column having a top condenser configured as a condenser-evaporator. The third coldbox is also called Argonbox and is separate from the first and second coldbox and from the main heat exchanger box.

The crude argon column can be formed in one part, as shown in EP 3771 17 B2 = US Pat. No. 5,019,145, or in several parts, for example in two parts, as shown in EP 628777 B1 = US Pat. No. 5,426,946. With multi-part training, all parts are in the third coldbox arranged. In addition, a pure argon column can be arranged in the third cold box.

The evaporation space of the top condenser of the crude argon column is preferably connected via a two-phase pipeline to the low-pressure column and the two-phase pipeline is designed so that during operation of the cryogenic air separation plant both gas and liquid from the evaporation space of the top condenser in the low pressure column flow. The corresponding pipeline can go through the second coldbox.

Here you can save height for otherwise required distributor and collector in the low pressure column. To minimize the height of packing columns, the gas and the liquid from the argon system are fed in at the same point. Compared to a separate feed in different places is a

Saved distributor, which costs about one meter height. With particularly critical transport length, this variant can offer advantages, although it is technically unfavorable.

The invention also relates to a method for producing a

Cryogenic air separation plant according to claims 9

and 10, respectively, in which the transportable package described above is used. The cleaning unit is designed, for example, as a molecular sieve adsorber. Alternatively, the air can also be cleaned in a switchable heat exchanger (revex or regenerator); in this case, cleaning unit and

Main heat exchanger formed by the same apparatus.

Preferably, the invention is used in air separation plants, which for obtaining more than 2,000, preferably more than 9,000 Nm ³ / h oxygen product and less than 35,000 Nm ³ / h, preferably less than 29,000 Nm ³ / h

Oxygen product are designed. In particular, argon can be recovered as another product.

The invention and further details of the invention are explained in more detail below with reference to two embodiments schematically illustrated in the drawing. Hereby show: Figure 1 shows a first embodiment of the invention with a pure

Piping box and

Figure 2 shows a second embodiment with a combined pipeline and

Argonbox.

In Figure 1, atmospheric air is compressed in an air compressor and cleaned in a cleaning device (both are not shown in the drawing). The purified feed air is cooled in a main heat exchanger against product streams to about dew point. The main heat exchanger consists in the example of three parallel plate heat exchanger blocks 2a, 2b, 2b, the one

common cold box, the main heat exchanger box 10 are arranged.

In general, the main heat exchanger can also consist of one block or of one, two, three or more blocks. These can be connected in parallel or divided according to their function, for example in a high-pressure exchanger and a low-pressure exchanger.

Via a connecting pipe 3, the cooled air is introduced into a cold box 20, which is referred to below as a piping box. Within the Rohleitungsbox 20, the air is continued in pipelines and optionally via valves and finally introduced via a line in a double column 5.

Alternatively, the air flows directly from the main heat exchanger box 10 into the column box 30; the pipeline box 12 then contains no gaseous feed air conduit.

The double column 5 is arranged in a further cold box 30, the column box.

Products and intermediates of the double column are introduced via a plurality of connecting lines 6 (only indicated in the drawing) in the pipeline box 20 and there further piping and / or system parts, which in

Cryogenic air separation plants are common, such as valves or a

Subcooling countercurrent supplied, which are arranged in the pipeline box. In the exemplary embodiment, the pipeline box contains in particular the following components:

- Liquid air line 7

- Subcooling countercurrent 8 - Turbine 9, in which liquid is separated upstream of a expansion turbine

- GAN line 1 1 for gaseous nitrogen from the low-pressure column

- Unreactic nitrogen line 12 for gaseous impure nitrogen from the

Low-pressure column

(The impurity nitrogen line 12 and the GAN line 1 1 go from the

Piping box 20 directly into the main heat exchanger box 10 (this is in the

Drawing not shown). Not directly illustrated in the drawing are the conduits that lead from the argon box to the column box, but all or substantially all of them are also located in the box. These include the lines for the fluids flowing liquid to the evaporation space of the overhead condensers of the pure and the crude argon column and for the gaseous and optionally liquid return streams from there, and the argon transition lines, so the Einssatzleitung for

Rohargonsäule and the return line from the crude argon column in the low pressure column.

In addition, the piping box contains all lines that are assigned to the column box and that would be located in the column box in conventional systems.

Via a plurality of connecting lines 13 and 14 (in the

Drawing only indicated), the return streams of the system (product streams and / or residual streams) from the pipeline box 20 are introduced into the main heat exchanger box 10 and - after warming in the main heat exchanger 2a, 2b, 2c - withdrawn in hot from the main heat exchanger 10.

In the embodiment, moreover, argon is recovered by passing an argon-containing stream from the double column 5 via the piping box and line 15 into another cold box 40 formed as an argon box. The argon box 40 contains a one-piece crude argon column 41 for argon-oxygen separation with overhead condenser (not shown) and a pure argon column 42 for argon-nitrogen separation.

The argon product and the residual fractions of argon recovery are over

Connecting lines 16 (only indicated in the drawing) back into the Piping box 20 passed and then continue to flow as return streams 15 to

Main heat exchanger box.

Alternatively, the argon box can also be omitted.

The pipeline box can be completely prefabricated, that is to say one builds a projecting shelter with operating platforms, which does not limit the transportability. All actuators of the valves can be installed during transport. These and any instrumentation including transmitters can be mounted, as well as measurement leads from the transmitter to the digital I / O card of the digital process control system. The prefabricated pipeline box has a central bus connection, where it is centrally connected to the site

Process control system is connected. All instrument air lines and impulse lines, cables, etc. can already be wired or connected in the factory.

The completely prefabricated pipe box can already be tested in the factory. The operating level can be closed again for transport. Each of the boxes 10, 20, 30 40 can have its own statics. Connections between the boxes (such as insulated boxes around pipes going from one box to another) may be flexible or rigid. In addition to the statics of each individual box, you can deliberately combine the steel construction of the boxes to further improve the statics through static coupling.

for example, by own carriers, which can also be used as a condition for inspections.

Figure 2 shows a second embodiment of the invention with a combined piping and argon box 400. Except for the components of the tubing box 20 of Figure 1, this combined box 400 contains the crude argon column 41, in the concrete example without pure argon column. Alternatively, a pure argon column could additionally be located in the combined piping and argon box 400. Incidentally, the structure of the system corresponds to that described in FIG.

Claims

claims

1. Transportable package for a cryogenic air separation plant having a main heat exchanger (2a, 2b, 2c) for cooling of feed air (1) and a double column (5) for decomposing the cooled feed air, wherein the double column (5) has a high pressure column and a Having low pressure column, which are arranged one above the other,

characterized in that the transportable package comprises a coldbox (20, 400) in the interior of which accessory parts of the double column (5), in particular pipes (7, 11, 12) and valves, are arranged, but not the double column and not the main heat exchanger , wherein the transportable package connections for the connection of the pipes with the double column and the

Main heat exchanger has.

Package according to claim 1, characterized in that the coldbox (20, 400) contains no separation column.

Package according to claim 1 or 2, characterized in that the coldbox (20, 400) contains a subcooling countercurrent (8).

Package according to claim 3, characterized in that the cold box (20, 400) contains no further heat exchanger for exchanging sensible heat beyond the subcooling countercurrent (8).

Package according to one of claims 1 to 4, characterized in that the coldbox (400) contains a crude argon column (41) having a top condenser, which is designed as a condenser-evaporator.

Cryogenic air separation plant with

- A first transportable system part (30) in which a double column (5) is arranged, wherein the double column (5) has a high pressure column and a low pressure column, which are arranged one above the other, and with

- A second transportable plant part (20, 400), which is designed as a package according to ei of claims 1 to 5, - Wherein the pipes (7, 1 1, 12) of the second part of the plant (20, 400) with the

Double column (5) are connected.

7. cryogenic air separation plant according to claim 6, comprising a third cold box (40) containing a crude argon column (41) having a top condenser, which is designed as a condenser-evaporator.

8. cryogenic air separation plant according to claim 7, wherein the

Evaporation space of the top condenser is connected via a two-phase pipe to the low pressure column and the two-phase pipe is designed so that during operation of the cryogenic air separation plant both gas and liquid flow from the evaporation space of the top condenser in the low pressure column. 9. A method for producing a cryogenic air separation plant according to any one of claims 6 or 7, wherein

the first transportable installation (30) is produced as a transportable package and transported to the installation site,

the second transportable installation part (20) is produced as a transportable package according to one of claims 1 to 5 and transported to the installation site,

- The piping of the second portable system part (20) on

Installation site with the double column (5) of the first portable system part (30) are connected and

- The double column (5) at the site with an air compressor for compressing feed air, with a cleaning unit for compressed feed air and with a main heat exchanger (2a, 2ab, 2c) for cooling purified feed air (1) is connected.

10. The method of claim 9, further comprising

- A third coldbox (40) manufactured as a portable package and the

Site is transported, with the third coldbox (40)

Pipe connections and a crude argon column (41), which has a top condenser, which is designed as a condenser-evaporator and

- At least a portion of the pipe connections of the third cold box (40) am

Site to be connected to pipes of the second coldbox (20).