JP3331416B2 - Air liquefaction separation apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air liquefaction separation apparatus and method, and more particularly, to liquefied rectification separation of raw air compressed by a raw air compressor using a double rectification column and a crude argon column to obtain crude argon. The present invention also relates to an air liquefaction / separation apparatus having a system for purifying the crude argon with an argon purification facility, and then liquefying and separating the crude argon with a high-purity argon column to collect high-purity argon.

[0002]

2. Description of the Related Art Generally, in the production of argon, oxygen gas containing about 10 to 12% of argon and a trace amount of nitrogen is extracted as a raw material gas from the middle stage of the upper column of a double rectification column of an air liquefaction separator, and this is extracted as crude argon. A step of introducing into a column for rectification to obtain crude argon having a purity of 95% or more, and returning the obtained crude argon to normal temperature, introducing the crude argon into an argon purification facility, and reacting the contained oxygen with hydrogen to produce water. And purifying the purified argon, cooling the purified argon again and introducing it into a high-purity argon column, and liquefying it to remove nitrogen and hydrogen to obtain high-purity argon. (See JP-A-60-126572).

[0003] In the above process, the crude argon flowing from the crude argon column to the argon purifying equipment is returned to room temperature by heating, and the equipment for cooling the purified argon flowing from the argon purifying facility to the high-purity argon column is composed of two components. An argon heat exchanger for heat exchange is used.

In the air liquefaction / separation apparatus having such an argon sampling system, the argon heat exchanger heats or cools the crude argon and the purified argon to a predetermined temperature when the apparatus is in a steady operation. As such, its specifications are set.

[0005] However, when the flow rates of the crude argon and the purified argon in the argon heat exchanger are different from those in the steady operation, for example, when the apparatus is started, the double rectification column on the raw air supply side sequentially approaches the steady operation state. Therefore, when the crude argon from the crude argon column starts to be led out of the cold box through the argon heat exchanger, the argon purification equipment has not yet entered the steady operation, and the purified argon has not been introduced into the argon heat exchanger. Time has come.

That is, since the crude argon may be discharged outside the cold box at a low temperature without being heated by the purified argon, conventionally, the crude argon is provided at the crude argon outlet side of the argon heat exchanger. A heater for heating the raw air is provided, and a flow path of crude argon is provided in a main heat exchanger for cooling the raw air to heat the raw air.

[0007]

However, in the case where a heater is installed on the crude argon outlet side of the argon heat exchanger, the heater is bothersomely installed for only one time at the time of starting the apparatus, and heating is performed. There is a problem in that the connection between a heat source (utility) and the consumption of the utility affects the manufacturing cost and the operating cost of the device.

When the main heat exchanger is provided with a flow path for crude argon, it is not necessary to install special equipment such as the above-mentioned heater. In the case where it is necessary to divide the heat exchanger blocks, it is necessary to provide the same amount of heat exchange in each heat exchanger block. In addition, it is necessary to provide an inlet and an outlet header for introducing and leading crude argon into and out of the flow path, and a pipe connected thereto.

Therefore, the configuration of the main heat exchanger becomes extremely complicated, which raises the problem of increasing the manufacturing cost.

Accordingly, an object of the present invention is to provide an air liquefaction separation apparatus and method that can solve the above-mentioned problem without providing any special equipment and with the addition of simple piping.

[0011]

In order to achieve the above-mentioned object, an air liquefaction / separation apparatus of the present invention comprises a double rectification column, a crude argon column, an argon purification facility, a high-purity argon column, and a raw air compressor. The raw material air compressed and cooled by the main heat exchanger is liquefied and rectified and separated in a double rectification column and a crude argon column,
In an air liquefaction separator provided with an argon purifying facility and a system for purifying high-purity argon by purifying with a high-purity argon column, crude argon flowing from the crude argon column to the argon purifying facility, To the argon heat exchanger for exchanging heat with the purified argon heading toward the upstream, and branching between the raw material air compressor and the main heat exchanger. A part of the compressed raw material air is introduced into the argon heat exchanger. It is characterized by providing a path to be performed.

Further, in the air liquefaction separation method of the present invention, the raw material air compressed by the raw material air compressor is cooled by the main heat exchanger and liquefied and separated by the double rectification column and the crude argon column. in Argo <br/> emission purification equipment and high purity cryogenic air separation process in the argon column by hand purified collecting the high purity argon, and crude argon toward the argon purification equipment from the crude argon column, high-purity argon purification equipment While exchanging heat with the purified argon heading for the argon column in the argon heat exchanger, depending on the temperature of the crude argon at the argon heat exchanger outlet , a part of the raw air compressed by the raw air compressor ,
It is characterized in that it is branched before being introduced into the main heat exchanger and is introduced into the argon heat exchanger.

The feed air derived from the argon heat exchanger is supplied to the lower tower of the double rectification column or an introduction system to the lower tower, an upper system of the double rectification column or an introduction system to the upper tower. The crude argon column is introduced into either the condenser or the introduction system to the condenser.

[0014]

According to the above configuration, when purified argon, which is a warm fluid, does not flow into the argon heat exchanger, such as when the apparatus is started, a part of the raw air compressed by the raw air compressor is replaced with the argon heat exchanger. , The crude argon can be heated to a predetermined temperature without providing a special device such as a heater.

Further, even when the apparatus is large and the main heat exchanger is composed of a plurality of heat exchanger blocks, the flow rate of the crude argon in the argon heat exchanger is much smaller than that of the raw air, and one heat exchanger is used. Since it can be manufactured with an exchanger, piping and the like do not become complicated.

Further, the raw air heated with the crude argon is sufficiently cooled by the crude argon, so that the raw air can be combined with the raw air cooled by the main heat exchanger and introduced into the separation step.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings. First, FIG. 1 shows the first embodiment of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic system diagram of the air liquefaction separation apparatus which shows an Example, and a raw material air compressor 1, a refinement installation 2, a main heat exchanger 3, a double rectification column 4, and the same as what has a conventional argon collection system.
A crude argon column 5, an argon heat exchanger 6, an argon purification facility 7, a high-purity argon column 8, and the like are provided.

The raw material air is compressed by the raw material air compressor 1, and after removing impurities such as moisture and carbon dioxide in a purifying facility 2 using an adsorber or the like, the main heat in the cold box 9 is passed through a pipe 11. It is introduced into the exchanger 3.

The main heat exchanger 3 is composed of a plurality of heat exchanger blocks 3a, 3a.
2. Flow evenly through each heat exchanger block 3a via the collecting pipe 13, exchange heat with the low-temperature return gas, and cool to near the saturation temperature.

The cooled raw material air is introduced from a pipe 14 into the lower tower 4a of the double rectification column 4, and is subjected to a well-known rectification operation in the double rectification column 4 to carry out oxygen gas, nitrogen gas, liquefied oxygen, and liquefied nitrogen. And each is collected from a pipe (not shown) as needed.

An oxygen gas containing about 10 to 12% of argon and a small amount of nitrogen is extracted from a pipe 15 provided in the middle of the upper column 4b of the double rectification column 4, and be introduced. This argon-containing oxygen gas is separated into crude argon having a purity of 95% or more and liquefied oxygen by rectification in the crude argon column 5, and the liquefied oxygen accumulated at the bottom of the column is returned to the middle stage of the upper column by the pipe 16.

On the other hand, the crude argon extracted from the upper part of the crude argon tower 5 into the pipe 17 is introduced into the argon heat exchanger 6 and heat-exchanges with the purified argon described later in the crude argon flow path 6a, thereby to perform a heat exchange. The temperature is raised to room temperature, taken out of the cold box 9 by a pipe 18, and introduced into the argon purification equipment 7.

In the argon purification equipment 7, a well-known purification step is performed in which hydrogen is added according to the amount of oxygen contained in the crude argon, and oxygen is converted into water and removed.

The purified argon from which oxygen has been removed is supplied to tube 19
Is again introduced into the cold box 9 and enters the argon heat exchanger 6. This purified argon is introduced into the purified argon flow path 6b of the argon heat exchanger 6 at a substantially normal temperature, and is led out of the crude argon of the pipe 17 and the high-purity argon tower 8 by the pipes 20 and 21. Channel 6
After being cooled by the recovered hydrogen or the purge gas flowing through c and 6d, it is introduced into the lower part of the high-purity argon column 8 through the pipe 22. The high-purity argon separated by the rectification operation in the high-purity argon column 8 is extracted from the pipe 23 as a product.

As is well known, a pipe 24 for discharging oxygen-enriched liquefied air is provided at the bottom of the lower column 4a of the double rectification column 4.
The oxygen-enriched liquefied air led out to the pipe 24 is depressurized by the pressure reducing valves 25a and 25b,
The gas is introduced into the upper part of the upper column 4b or the condenser 5a of the crude argon column 5 through the pipe 6 and the pipe 27. The crude argon tower 5
The condenser 5a is provided with a pipe 28 for introducing the liquid and the evaporative gas in the condenser 5a to the upper tower 4b. further,
Such an air liquefaction / separation apparatus is usually provided with an expansion turbine for appropriately maintaining the amount of cooling in the system, and partially derives a gas from a raw air system or a high pressure system such as the lower tower 4a. After a part of the cold is recovered by the heat exchanger, it is expanded by the expansion turbine to generate cold, and the expanded low-pressure gas is introduced into a low-pressure system such as the upper tower 4b.

The argon heat exchanger 6 in the present embodiment is provided with a path for introducing a part of the room temperature raw air compressed by the raw air compressor 1 and purified by the purification equipment 2. I have. This path includes a pipe 31 branched from the pipe 11 and a flow control valve 32 provided in the pipe 31.
, A compressed air flow path 6 e of the argon heat exchanger 6, and a pipe 33 that joins the raw air after being led out of the argon heat exchanger 6 to the pipe 14.

The flow rate control valve 32 is controlled by a temperature support controller (TIC) 34 provided in the pipe 18 of the crude argon outlet in the argon heat exchanger 6.
The flow rate of the raw air flowing through the branch pipe 31 is adjusted according to the temperature of the crude argon derived from the cold box 9.

That is, when the temperature of the crude argon in the pipe 18 becomes lower than the predetermined temperature, the TIC 34 detects the temperature drop and opens the flow control valve 32 to supply the raw air to the compressed air of the argon heat exchanger 6. It is configured to be introduced as a warm fluid into the flow path 6e.

Therefore, unlike when the apparatus is started, purified argon as a warm fluid does not flow to the argon heat exchanger 6,
Even during the period when the crude argon cannot be sufficiently heated, a part of the raw air is introduced into the argon heat exchanger 6 as a warm fluid, so the crude argon extracted from the cold box 9 and introduced into the argon purification equipment 7 is It can be heated to a predetermined temperature.

With the above configuration, there is no need to provide special equipment such as a heater or the like, and it is not necessary to provide complicated piping in the main heat exchanger 3. Further, since the heat load of the argon heat exchanger 6 is less than one-hundredth of that of the main heat exchanger 3, the argon heat exchanger 6 requires a large number of heat exchanger blocks 3a as the main heat exchanger 6. Even in a large-sized device, the argon heat exchanger 6 requires one small heat exchanger.
Since it is enough to prepare the base, the piping for introducing the raw material air can also be implemented by providing only one pipe for introduction and derivation, and the flow rate is small, so a small-diameter pipe can be used.
A small valve can also be used as the flow control valve 32.

As a result, the manufacturing cost of the apparatus can be reduced as compared with the prior art, and a utility for heating the crude argon is not required, so that the cost for the piping for the utility and the consumption can be reduced.

On the other hand, in the main heat exchanger 3, a part of the raw material air is branched to the argon heat exchanger 6, so that the flow rate is reduced.
Is less than one-hundredth of the heat load of the main heat exchanger 3 and the amount of branching is small, so that there is no problem.

Here, in the first embodiment, the raw air derived from the argon heat exchanger 6 is supplied to the pipe 14 as a high-pressure system.
The raw material air can be introduced into each part of the low-pressure system according to the pressure. In the following description, the same elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

First, the second embodiment shown in FIG. 2 is provided with a pipe 41 for directly introducing the raw air from the argon heat exchanger 6 into the upper tower 4b. In the third embodiment shown in FIG. 3, the raw material air led out of the argon heat exchanger 6 is supplied to the pipe 2 for introducing the oxygen-enriched liquefied air after the pressure reduction into the upper tower 4b.
6 is provided with a pipe 42 to be joined. FIG.
In the fourth embodiment, a pipe 43 is provided for joining the raw air derived from the argon heat exchanger 6 to the pipe 28 extending from the crude argon condenser 5a to the upper tower 4b.

Further, as in the fifth embodiment shown in FIG.
In the case of an apparatus provided with a pipe 45 for introducing the gas derived from the expansion turbine 44 to the upper tower 4b, a pipe 46 for joining the raw material air derived from the argon heat exchanger 6 may be provided in the pipe 45.

In addition, as shown in FIGS. 6 and 7, a pipe 47 for introducing directly into the condenser 5a of the crude argon column 5, a pipe 27 for introducing oxygen-enriched liquefied air into the condenser 5a, or the like is provided.
May be provided so that the raw air from the argon heat exchanger 6 is introduced into the crude argon condenser 5a.

The flow rate of the raw air in the argon heat exchanger 6 is controlled by the flow control valve 32 on the inlet side of the heat exchanger 6 as described above. The same operation can be performed even when the flow control valve 49 is provided.

As shown in FIGS. 2 to 7, the feed air from the argon heat exchanger 6 is supplied to the upper column 4b or the upper column 4b of the double rectification column 4 operated at a lower pressure than the feed air.
Into the pipe 26, the pipe 28 from the crude argon condenser 5a to the upper tower 4b, or the pipe 45 from the expansion turbine 44 to the upper tower 4b, or to the crude argon condenser 5a or the condenser 5a. Tube 27 which is the introduction system of
, It is possible to set the pressure of the raw air from the argon heat exchanger 6 low.

That is, as shown in the first embodiment,
The raw material air derived from the argon heat exchanger 6 is separated into the double rectification column 4
Lower tower 4a and pipe 1 for introducing raw material air into lower tower 4a
In the case where the raw material air is introduced into the raw material air 4, it is possible to effectively liquefy and separate the raw material air from the argon heat exchanger 6 into oxygen and nitrogen similarly to other raw material air. Care must be taken to cope with the reduced pressure loss, and the flow path area of the argon heat exchanger 6 must be increased, and the diameters of the front and rear piping and valves must also be increased.

On the other hand, if the raw material air from the argon heat exchanger 6 is made into a low pressure system as described above, there is almost no need to consider the pressure loss through the argon heat exchanger 6, and the flow rate control valve 32, the flow area of the argon heat exchanger 6 can be reduced, the size of the heat exchanger 6 can be reduced, and the diameter of the front and rear pipes and valves can be reduced. it can.

At this time, since the raw material air led out of the argon heat exchanger 6 is not introduced into the lower tower 4a, the product yield decreases, but the amount of the raw air introduced into the argon heat exchanger 6 is reduced. In most cases, when the warm fluid in the argon heat exchanger 6 at the time of starting the apparatus is insufficient, the operation can be almost close to zero if a predetermined amount of purified argon, which is a warm fluid, flows into a steady operation and the warm fluid flows. The reduction in yield is of little concern.

For example, the raw material air amount is 128000 Nm ³ /
For h of the apparatus, feed air maximum amount required argon heat exchanger 6 during device activation is about 1000 Nm ³ / h, at the time of steady operation becomes sufficient at about 50 to 60 nm ³ / h. Therefore, the amount of the raw material air not introduced into the lower tower 4a during the steady operation is 0.05% or less of the whole, so that the decrease in the oxygen yield is also 0.01% or less, which is smaller than the error of a general flow meter. Become. That is, even if a part of the raw air is always branched to the argon heat exchanger 6, the decrease in the yield is in a negligible range and does not cause any problem.

The configuration of the air liquefaction / separation apparatus is not limited to the above-described embodiment, but may be appropriately optimized according to the state of collecting oxygen and nitrogen other than high-purity argon. In addition, the flow rate of the raw air in the argon heat exchanger can be set arbitrarily, and may be set to zero during a steady operation. Furthermore, the route of the raw material air after derivation of the argon heat exchanger can be arbitrarily set, and may be branched into a plurality of portions and introduced into different portions, or may be discharged after being joined to an exhaust gas system. In such a case, it may be introduced at the entrance side.

[0044]

As described above, according to the present invention,
In an air liquefaction / separation unit that produces high-purity argon, even when purified argon, which is a warm fluid for heating crude argon in an argon heat exchanger, does not flow, crude argon can be used without installing special equipment or complicated piping. Can be heated to a predetermined temperature, whereby the manufacturing cost of the apparatus and the operating cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a first embodiment of an air liquefaction / separation apparatus of the present invention.

FIG. 2 is a system diagram of a main part showing a second embodiment in the same manner.

FIG. 3 is a system diagram of a main part similarly showing a third embodiment.

FIG. 4 is a system diagram of a main part of the fourth embodiment.

FIG. 5 is a system diagram of a main part, similarly showing a fifth embodiment.

FIG. 6 is a system diagram of a main part showing a sixth embodiment in the same manner.

FIG. 7 is a system diagram of a main part showing a seventh embodiment in the same manner.

[Explanation of symbols]

1 ... raw material air compressor, 2 ... purification equipment, 3 ... main heat exchanger,
4 Double rectification column, 4a Lower column, 4b Upper column, 5 Crude argon column, 5a Condenser, 6 Argon heat exchanger, 7
Argon purification equipment, 8 high purity argon tower, 9 cold box, 32 flow control valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25J 1/00-5/00

Claims (5)

(57) [Claims] 1. A double rectification column, a crude argon column, an argon purification facility, a high-purity argon column, and compressed by a raw material air compressor.
Feed air cooled by the main heat exchanger
Liquefaction and separation in a Gon tower
In an air liquefaction / separation apparatus provided with a system for purifying and purifying high-purity argon with a high-purity argon column, crude argon flowing from the crude argon column to the argon purification facility, and purified argon traveling from the argon purification facility to the high-purity argon tower. And an argon heat exchanger for exchanging heat with the raw material air compressor.
Before some of the branches to compressed feed air between the main heat exchanger
An air liquefaction / separation apparatus characterized in that a path for introducing into the argon heat exchanger is provided. 2. The method according to claim 1, wherein a path is provided for introducing the raw material air discharged from the argon heat exchanger to a lower column of the double rectification column or an introduction system to the lower column. Air liquefaction separator. 3. The method according to claim 1, wherein a path is provided for introducing the raw material air derived from the argon heat exchanger to an upper column of the double rectification column or an introduction system to the upper column. Air liquefaction separator. 4. A path is provided for introducing the raw material air led out of the argon heat exchanger into a condenser of the crude argon column or an introduction system to the condenser.
An air liquefaction separation device as described. 5. The raw material air compressed by the raw material air compressor is mainly used.
Cooled by heat exchanger and liquefied by double rectification column and crude argon column
Release, further hand to argon purification equipment and high purity argon column
In the air liquefaction separation method of purifying and collecting high-purity argon, crude argon flowing from the crude argon column to the argon purification facility and purified argon flowing from the argon purification facility to the high-purity argon tower are heated by an argon heat exchanger. A part of the raw air compressed by the raw air compressor is branched and introduced into the argon heat exchanger according to the temperature of the crude argon at the outlet of the argon heat exchanger. Air liquefaction separation method.