JPH0730997B2 - Condensing evaporator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a condenser / evaporator for exchanging heat between a liquid medium in a first fluid chamber and a gas fluid in a second fluid chamber, and particularly to an air liquefaction / separation device. In the condensing evaporator, the liquid medium introduced into the first fluid chamber, that is, liquefied oxygen introduced into the oxygen chamber, is efficiently boiled and evaporated, and is introduced into the gas fluid introduced into the second fluid chamber, that is, the nitrogen chamber. The present invention relates to a condensation evaporator suitable for efficiently condensing and liquefying nitrogen gas.

[Conventional technology]

Condensation evaporator used in the double rectification column of the air liquefaction separation device, as shown in JP-A-56-56592,
A so-called plate fin type heat exchanger in which the vertical direction is partitioned by a large number of parallel partition plates, and two chambers of an oxygen chamber which is a first fluid chamber and a nitrogen chamber which is a second fluid chamber are alternately and adjacently stacked. What is called is often used.

The oxygen chamber of such a plate fin type condensation evaporator is
A heat transfer plate is vertically arranged inside to form a large number of vertical evaporation channels, and the upper and lower ends of the evaporation channels are opened so that the lower end serves as an inlet for liquefied oxygen and the upper end is It serves as the outlet for the mixed flow of oxygen gas and liquefied oxygen. This oxygen chamber is filled with liquefied oxygen by immersing the entire condensation evaporator in the liquefied oxygen that accumulates in the bottom space of the upper tower. Exchange is performed, and a part thereof is evaporated to form bubbles of oxygen gas, which rises in the evaporation passage. The liquefied oxygen forms a circulation flow inside and outside the condensed vaporized gas due to the density difference between the liquefied oxygen, the oxygen gas, the gas-liquid mixed phase, and the liquefied oxygen outside the oxygen chamber.

One of the nitrogen chambers has a vertical heat transfer plate disposed outside the chamber whose four circumferences are closed to form a large number of vertical condensing passages, which are provided above and below the condensing passages. It is connected to the lower tower through the header. Then, nitrogen gas in the upper part of the lower tower is introduced from the upper header into the condensing channel as a downflow, and liquefied nitrogen condensed by performing heat exchange with liquefied oxygen in the condensing channel is led out from the lower header.

[Problems to be Solved by the Invention]

However, since the conventional condensing evaporator is used by immersing the whole in the liquefied oxygen in the bottom space of the upper tower, the condensing evaporator must function unless a large amount of liquefied oxygen is stored in the space. I couldn't. As a result, it takes a long time to start up the device, and the amount of oxygen released at the time of stoppage is large, resulting in loss of power costs and the like. In addition, there are major security issues in case of an emergency.

Further, due to the liquid depth of liquefied oxygen, the boiling point of liquefied oxygen in the lower part of the bottom space of the upper tower, that is, the lower part of the condenser evaporator is increased,
Liquefied oxygen flowing from the lower part of the oxygen chamber into the evaporation passage is in a supercooled state. Therefore, in the lower part of the oxygen chamber, the liquefied oxygen rising in the vaporization flow path must be heated to the boiling start temperature by convective heat transfer with low heat transfer efficiency, and the heat transfer efficiency of the flow path is reduced.

Furthermore, in the nitrogen chamber on the condensation side, the condensation flow path is formed in the vertical direction, and since the nitrogen gas does not condense and flows down,
In the lower part of the flow path, the amount of liquefied nitrogen increases, and a thick liquid film covers the surface of the heat transfer surface, which serves as a heat resistance layer and deteriorates the heat transfer performance. The above drawbacks are noticeable in high condenser evaporators.

Therefore, the present invention reduces the necessary amount of liquefied oxygen (liquid medium) on the oxygen chamber (first fluid chamber) side, reduces the influence of liquid depth of liquefied oxygen, and further reduces the influence of the nitrogen chamber (second fluid chamber). An object of the present invention is to provide a condensing evaporator in which the reduction in the heat transfer performance due to the condensate is reduced and the shape limitation on the heat transfer performance in the height direction is reduced.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention forms a first fluid chamber and a second fluid chamber alternately by a large number of vertical partition plates, and a liquid medium of the first fluid chamber and a second fluid chamber of the second fluid chamber. In a condensation evaporator that performs heat exchange with a gas fluid, in the first fluid chamber,
Arranging heat transfer plates in upper and lower stages to form multiple liquid medium flow paths,
At one end of the liquid medium flow path, a plurality of liquid reservoirs that communicate with the liquid medium flow path and introduce the liquid medium are provided in upper and lower multi-stages with the upper part opened, and the other end side of the liquid medium reservoir path is opened. On the other hand, in the second fluid chamber, a plurality of gas transfer passages are formed by arranging heat transfer plates in upper and lower stages, and a gas introduction passage is connected to the inlet side of the gas passage, and also a gas passage of the gas passage. To provide a condenser-evaporator, characterized in that discharge paths are connected to the outlet side, respectively.
Furthermore, the liquid medium flow path has an ascending slope from one end on the liquid reservoir side toward the open end at the other end, and also has a downward slope with respect to the horizontal direction in the flow direction of the gas fluid. And a discharge path for the liquid medium evaporated gas and the non-evaporated liquid medium is provided so as to be connected to the open end of the liquid medium flow path.

[Work]

By configuring the condensing evaporator as described above, the liquid medium is supplied to the liquid reservoir without immersing the condensing evaporator in the liquid medium, and the liquid medium flows from the liquid reservoir to the liquid medium passage of the first fluid chamber. Since it can be operated simply by introducing the medium, the condenser-evaporator can be operated with a smaller amount of liquid medium than before, and the boiling point rise due to the liquid depth of the liquid medium can be reduced, and the heat transfer performance can be reduced. The restriction in the upper height direction is eliminated, and the boiling evaporation efficiency can be improved. In addition, since the condensing flow passages of the second fluid chamber are arranged in a multi-stage vertically and are formed in a downward gradient toward the flow direction of the gas fluid, the gas fluid can be introduced substantially evenly in the vertical direction of the second fluid chamber. Since the length can be shortened, the restriction in the height direction of the condenser evaporator is also eliminated. Further, the liquid medium in the first fluid chamber can be efficiently heated.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in more detail with respect to an example in which the first fluid chamber is an oxygen chamber, the second fluid chamber is a nitrogen chamber, the liquid medium is oxygen, and the gas fluid is nitrogen.

First, in FIGS. 1 to 5, the condenser evaporator 1 is formed by stacking a plurality of oxygen chambers 3 and nitrogen chambers 4 alternately adjacent to each other by a large number of partition plates 2, 2 arranged in a vertical direction. ing.
Further, on one side of the condenser-evaporator 1, a liquefied oxygen introducing pipe 5 and a plurality of liquid reservoirs 7 communicating with the introducing pipe 5 through the through holes 6 are provided in upper and lower stages. The liquid reservoir 7 is formed in a box shape having an opening on the upper side and the oxygen chamber 3 side, and a notch weir 8 for overflow is formed at a part of the upper edge of the side wall.

The oxygen chamber 3 has side bars at both upper and lower ends.
A plurality of liquid medium flow paths 11, 11 are formed which are closed by 9, 9 and are provided with a heat transfer plate 10 such as a corrugation fin inside to open both ends. The liquid medium flow path 11 has one side communicating with the liquid reservoir 7 and has a climbing gradient from the liquid reservoir side to the open end of the other end. The liquid medium flow paths 11, 11 communicate with each other.

The liquefied oxygen LO is introduced from the liquefied oxygen introducing pipe 5 into the liquid reservoirs 7 and 7 in the upper and lower stages through the through holes 6 and 6, and from the liquid reservoir 7 to the liquid medium flow paths 11 and 11 in the oxygen chamber 3. be introduced. The liquefied oxygen LO in the liquid medium flow path 11 exchanges heat with the nitrogen gas GN in the nitrogen chamber 4 described later, and a part of it evaporates to oxygen gas GO, becoming a gas-liquid mixed flow and becoming a liquid medium flow path. Ascend toward the open end of 11. The gas-liquid mixed flow of the liquefied oxygen LO and the oxygen gas GO reaches the open end of the liquid medium flow path 11 and is separated here, the oxygen gas GO rises, and the liquefied oxygen LO flows down below the condensation evaporator 1. To do.

Further, the liquefied oxygen LO excessively supplied to the liquid reservoir 7 is successively accumulated from the notch weir 8 to the liquid reservoir 7 below. The liquefied oxygen LO flowing down from the lowermost liquid reservoir 7 and the tip of the liquid medium flow path 11 is pumped by a liquefied oxygen pump or a thermosiphon heat exchanger and circulated in the liquefied oxygen introducing pipe 5.

With this configuration, the amount of liquefied oxygen LO required to operate the condensing evaporator 1 is the amount that fills the oxygen chamber 3,
Since the amount accumulated in the liquid reservoirs 7 and 7 and the excessive circulation amount for preventing the concentration of acetylene and the like are sufficient, the amount of the condensation evaporator 1 is much smaller than the amount of the whole condensation evaporator 1 immersed as in the conventional case. Can drive. As a result, the start-up time of the air separation device can be shortened, the amount of refrigerant discharged when the device is stopped can be reduced, and security problems can be easily solved.

Further, since the pressure of the liquefied oxygen LO is released in each of the liquid reservoirs 7 and 7, the liquid depth of each liquid becomes small and the boiling point rise due to the liquid pressure can be suppressed, and the liquefied oxygen LO evaporates almost at the same time as flowing into the liquid medium flow passage 11. Boiling can be initiated.

The inclination angle of each liquid medium flow channel 11 is appropriately selected depending on the depth of the liquid reservoir 7 to be connected, the length of each flow channel 11, the amount of processing, and the like. Rather than being provided as a climb gradient, the levitation force of the bubbles of oxygen gas generated by evaporation can promote the flow of liquefied oxygen in one direction and improve the heat transfer efficiency. In addition, each liquid medium flow path 11,11
The amount of liquefied oxygen to be introduced into the liquid is the diameter of the liquefied oxygen introduction pipe 5 or the through hole 6, the depth of the liquid reservoir 7, the length or inclination of the liquid medium flow path 11,
This can be performed by adjusting the opening cross-sectional area and the like, and it is preferable to adjust so that the liquefied oxygen LO is uniformly introduced into the upper and lower liquid medium channels 11, 11. Further, the means for causing the liquefied oxygen LO to flow down from the respective liquid reservoirs 7, 7 to the lower liquid reservoir 7 is not limited to the notch weir 8 and can be performed by an overflow pipe or the like.

On the other hand, the nitrogen chamber 4, which is arranged adjacent to the oxygen chamber 3 via the partition plate 2, has four side bars 1 as shown in FIG.
The heat transfer plates 13 such as corrugation fins are closed in the interior of the chamber to form the condensing flow paths 14 and 14 which are a large number of gas flow paths whose both ends are open. A gas introduction passage 15 and a discharge passage 16 are provided so as to be connected to both sides of each.

The condensation channel 14 is liquefied nitrogen condensed in the condensation channel 14.
In order to discharge LN from the condensing flow path 14 and to flow it down, a gas introduction path
An appropriate downward slope is provided in the horizontal direction from the 15 side toward the discharge path 16. In addition, the gas inlet 15 and the outlet 16 on both sides of the nitrogen chamber 4 have inlet and outlet headers, respectively.
17, 18 are connected to introduce the nitrogen gas GN into the nitrogen chamber 4, and the liquefied nitrogen LN condensed in the condensation passage 14 is discharged.

The nitrogen gas GN is introduced into the respective condensation flow passages 14, 14 via the inlet header 17 and the gas introduction passage 15. The nitrogen gas GN introduced into the condensing channel 14 is the liquefied oxygen in the adjacent oxygen chamber 3.
Heat exchange with LO to condense and condense into liquefied nitrogen LN to condense flow path
It flows toward the discharge path 16 due to the downward slope of 14 and the discharge path 16
Is discharged through the outlet header 18. Also nitrogen gas GN
The non-condensed gas GX therein is discharged from the purge nozzle 19 provided at the upper part of the discharge path 16.

In this way, by forming a large number of condensing flow paths 14 having a downward slope in the nitrogen chamber 4 and introducing the nitrogen gas GN from one end of the condensing flow path 14 and leading out from the other end, the nitrogen chamber 4 vertical direction Since the amount of nitrogen gas introduced into each condensation passage 14 and the liquefied nitrogen condensed in the passage 14 can be made substantially the same, the film heat transfer coefficient can be made substantially the same in the vertical direction of the condensation evaporator 1. it can.

Therefore, since sufficient heat exchange can be performed with the liquefied oxygen LO under the oxygen chamber 3, the heat transfer performance by condensation evaporation can be maximized. Particularly in a large tall condensing evaporator, the length of the condensing channel 14 can be greatly shortened, and the thickness of the liquid film of liquefied nitrogen LN formed near the discharge channel 16 of each condensing channel 14 Since the thickness can be made thin, the decrease in heat transfer performance can be minimized. Further condensation channel
Since the cross-sectional area and the opening area of 14 can be increased, the condensation amount and flow resistance per condensation channel cross-sectional area can be reduced, and the heat exchange efficiency can be further improved. Further, by providing a liquid draining portion at a part of the opening end of the condensation flow path 14 opening to the discharge path 16, the liquefied nitrogen LN flowing down from the upper condensation flow path 14 is guided to the discharge path 16 and It is possible to prevent the opening end of the condensing channel 14 from being blocked by the liquid film.

Further, the gas introduction passage 15 and the discharge passage 16 can be appropriately provided with a reinforcing material or the like for improving pressure resistance, but both have low flow resistance of gas and liquid, and uniform distribution of gas and It is necessary to select the shape and layout in consideration of liquid drainage.

By forming the oxygen chamber 3 and the nitrogen chamber 4 in this way, it is possible to minimize the increase in the boiling point of the liquefied oxygen LO due to the liquid pressure on the oxygen chamber side and the decrease in the heat transfer characteristics due to the increase in the liquid film thickness on the nitrogen chamber side. Therefore, the entire heat transfer area of the condenser evaporator 1 can be used for boiling condensation heat transfer having high heat transfer characteristics. Moreover, since the heat transfer characteristics in the vertical direction can be made substantially the same, the height of the condenser evaporator 1 can be freely set, and the increase in the processing capacity can be dealt with by increasing the height. A large double rectification column can be manufactured without increasing the column diameter. Further, by improving the heat transfer characteristics, the temperature difference between the condensing side fluid and the evaporating side fluid can be reduced, so that the saturation pressure of the condensing side gas can be lowered, and the pressure of the gas fluid, that is, the source gas. The power cost of the compressor for compressing can be reduced.

Next, one embodiment in which the double rectification column of the condensation evaporator of the present invention is incorporated will be described with reference to FIGS. In the structure of each part of the condenser / evaporator, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

First, the condensing evaporator 20 shown in the present embodiment is formed by combining the two condensing evaporators 1 shown in the above embodiment so as to face each other. That is, as shown in FIG. 7, the oxygen chamber 21 is provided with liquid reservoirs 7, 7 on both sides of the condenser-evaporator 20 and an oxygen gas and liquefied oxygen discharge passage 22 is formed in the central portion. Further, the nitrogen chamber 23 forms a gas introduction passage 15 in the central portion between the condensing passages 11 and 11 facing each other, and discharge passages 16 and 16 are provided outside the both condensing passages 14 and 14, respectively. Headers 17 and 18 are connected to 16 and 16, respectively. Further, the gas introduction passage 15 is provided with a reinforcing member 24 such as a perforated corrugation fin having a large number of holes. When the condenser-evaporator 20 is tall, an inlet header is also provided on the upper part of the condenser-evaporator 20 to introduce the nitrogen gas GN into the gas introduction passage 15 so that the supply amount of the nitrogen gas GN can be increased or decreased. It can be made uniform.

The condensing evaporator 20 formed in this way, as in the conventional case,
The upper part of the partition 33 which separates the upper column 31 and the lower column 32 of the double rectification column 30 is arranged in the bottom space of the upper column 31, that is, liquefied oxygen LO from the upper column 31 and nitrogen from the lower column 32. It exchanges heat with the gas GN.

The supply of the liquefied oxygen LO to the condensation evaporator 20 is performed by flowing the liquefied oxygen LO from the lowermost tray 34 of the upper tower through the downflow pipe 35 and by circulating the liquefied oxygen LO through the liquid return pipe 36. It is performed by supplying the liquid to the liquid receiving box 37 provided in the. The liquefied oxygen LO supplied to the liquid receiving box 37 is supplied from the liquefied oxygen introducing pipes 5 on both sides of the condenser / evaporator 20 connected to the liquid oxygen LO to respective liquid reservoirs 7,
It is introduced into each liquid medium flow path 11, 11 via 7. The liquefied oxygen LO in the liquid medium flow path 11 is partially liquefied into oxygen gas GO in the same manner as in the above-described embodiment, and the liquefied oxygen LO flowing through both liquid medium flow paths 11 and 11 reaches the open end. The gas-liquid mixed flow of the oxygen gas GO and the oxygen gas GO is separated here, and the oxygen gas GO rises in the discharge passage 22 and a part of the oxygen gas GO is collected as a product. On the other hand, the liquefied oxygen LO flows down the discharge path 22, accumulates in the liquefied oxygen reservoir 38 below the condensation evaporator 20, and is circulated to the liquid return pipe 36 except for being led out from the pipe 39 and partly becoming a product.

On the other hand, the nitrogen gas GN in the upper part of the lower tower 32 rises up the introduction part 40a at the inner circumference of the introduction pipe 40 formed of a double pipe and is extracted from the nitrogen gas chamber from the inlet header 17 except that a part is collected as a product. twenty three
It is introduced into the respective condensation flow passages 14, 14 via the gas introduction passage 15 in the central portion. The nitrogen gas GN introduced into the condensing channel 14 condenses into liquefied nitrogen LN in the same manner as in the above embodiment, and flows toward the exhaust passages 16 on both sides of the nitrogen chamber 23. The liquefied nitrogen LN flows down the discharge passage 16, passes through the outlet header 18, and is led out of the pipe 41 through the lead-out portion 40b on the outer periphery of the introduction pipe 40. It becomes the reflux liquid of the tower 31 and the lower tower 32. The non-condensed gas GX is led out from the purge nozzles 19 and 19 as described above.

In this way, by arranging the liquid medium flow passages 11 and the condensation flow passages 14 of the two units of the condenser-evaporator 1 shown in the above-mentioned embodiment so as to face each other, the pipes for incorporating in the double rectification column 30 etc. It is possible to reduce the cost, and it is possible to reduce the cost of manufacturing and assembling.

The operation of the condenser evaporator 20 is performed by using the liquid level gauge 42, etc.
By measuring the amount of liquefied oxygen LO accumulated in the water, it can be performed in the same manner as the conventional method.

In the above description, the description is based on the evaporation and condensation by the heat exchange between liquefied oxygen and nitrogen gas in the air liquefaction separation, but the same effect is obtained when other liquid mediums and gas fluids are used. The effect can be obtained. The angle of the gradient of each flow path of the oxygen chamber and the nitrogen chamber, the shape of each of the other parts, and the like can be appropriately selected depending on the types and flow rates of the liquid medium and the gas fluid.

As a method of forming the gradients of the liquid medium flow channel and the condensation flow channel, the entire condensation evaporator in which these flow channels are horizontally arranged may be tilted.

〔The invention's effect〕

As described above, the condensing evaporator of the present invention supplies the liquid medium to the liquid reservoirs provided in the upper and lower stages, and introduces the liquid medium into the liquid medium passages provided in the upper and lower stages to evaporate the liquid medium. Therefore, the condenser evaporator can be operated with a small amount of liquid medium,
The start-up time can be shortened, the refrigerant loss at the time of stoppage can be reduced, the problem of safety can be solved, and the effect of the liquid depth can be reduced to improve the boiling-side electrothermal efficiency. In the second fluid chamber, a condensing channel having a downward gradient with respect to the horizontal direction toward the flow direction of the gas fluid is formed, and the gas fluid is introduced from one end and condensed to flow down in the other direction. Therefore, the gas fluid can be introduced substantially evenly in the vertical direction of the second fluid chamber, and the liquid medium in the lower portion of the first fluid chamber can be efficiently heated. Further, since the condensing flow path can be formed short, the liquid film of the condensate can be thinned, and the boundary film electrothermal coefficient on the condensing side can be improved.

Therefore, it is possible to maximize the heat transfer performance of both chambers, and it is particularly suitable for the condenser evaporator of a large air liquefaction separation device with a large amount of treatment, and downsizing of the entire device and reduction of operating power cost It is possible to reduce the power consumption of the product.

[Brief description of drawings]

1 to 5 show one embodiment of the condensing evaporator of the present invention. FIG. 1 is a sectional front view showing an oxygen chamber of the condensing evaporator, and FIG. 2 is a sectional front view also showing a nitrogen chamber. 3 and 4 are partially cutaway side views, FIG. 4 is likewise partially cutaway front view, FIG. 5 is likewise a sectional plan view, and FIGS. 6 to 9 are other embodiments of the present invention. FIG. 6 is a sectional front view showing a state in which a condensation evaporator is incorporated in a double rectification column, FIG. 7 is a sectional front view showing an oxygen chamber, and FIG. 8 is a sectional front view showing a nitrogen chamber. FIG. 9 and FIG. 9 are cross-sectional plan views showing a state of being incorporated in a double rectification column. 1,20 …… Condensation evaporator, 3,21 …… Oxygen chamber, 4,23 …… Nitrogen chamber, 7 …… Liquid reservoir, 11 …… Liquid medium passage, 14 …… Condensation passage, 15
...... Gas introduction path, 16 …… Discharge path, 22 …… Oxygen gas and liquefied oxygen discharge path, 30 …… Double rectification column, GN …… Nitrogen gas, GO
...... Oxygen gas, LN ...... liquefied nitrogen, LO ...... liquefied oxygen

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-56-56592 (JP, A) JP-A-56-130201 (JP, A) JP-A-63-187085 (JP, A) JP-B-40- 18206 (JP, B1) JP-B 49-37627 (JP, B1) JP-B 4-14269 (JP, B2) JP-B 6-68434 (JP, B2) Actual JP-61-42072 (JP, Y2) Actual public Sho 63-47831 (JP, Y2) Actual public Sho 63-49676 (JP, Y2)

Claims (3)

[Claims] 1. A first fluid chamber and a second fluid chamber are alternately formed by a large number of vertical partition plates, and heat exchange is performed between a liquid medium in the first fluid chamber and a gas fluid in the second fluid chamber. In the condenser-evaporator, heat transfer plates are arranged in the upper and lower stages in the first fluid chamber to form a plurality of liquid medium flow passages, and one end of the liquid medium flow passage communicates with the liquid medium flow passage to form a liquid medium. A plurality of liquid reservoirs for introducing the medium are provided in upper and lower multi-stages by opening the upper part, and the other end side of the liquid medium flow path is opened, while heat transfer plates are arranged in the upper and lower multi-stages in the second fluid chamber. To form a plurality of gas flow paths, the gas introduction path is connected to the inlet side of the gas flow path, and the discharge path is connected to the outlet side of the gas flow path. Evaporator. 2. The liquid medium flow path has a climbing gradient from one end on the liquid reservoir side to the open end on the other end, and the gas flow path extends in the flow direction of the gas fluid. The condenser evaporator according to claim 1, wherein the condenser evaporator has a downward slope with respect to the horizontal. 3. The condensing evaporator according to claim 1, wherein a discharge passage for the liquid medium evaporated gas and the non-evaporated liquid medium is provided so as to be connected to the open end of the liquid medium passage.