JPH10253286A - Distributor for heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a pressure loss and the consequent increase in power by assembling a plurality of posts at a proper interval while allowing the passage space of a fluid to remain between plates in a distributor that is arranged at the exit or entrance part of the fluid in a corrugate fin type heat exchanger. SOLUTION: A distributor is arranged at either the outlet or entrance part of a fluid in a corrugate fin type heat exchanger and is formed to secure a sufficient pressure resistance strength that can fully withstand a restriction force on assembling by posts S that are assembled between a pair of plates P and P with an arbitrary interval. More specifically, the posts S function as a beam between the plates P and P being arranged at both edges and support a restriction force from upper and lower directions. Also, the posts S have much improved pressure resistance strength as compared with a conventional corrugate plate and the mounting gap, namely the passage space of a fluid, can be sufficiently wide, thus suppressing a pressure loss at the distributor part as much as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributor for a corrugated fin type heat exchanger, and more particularly to a distributor for suppressing a flow resistance of a fluid in the distributor and reducing a pressure loss of a fluid in the entire heat exchanger. With respect to the improved distributor, the distributor can be effectively used, for example, as a distributor for a main heat exchanger used for exchanging heat between a return gas and raw material compressed air in an air separation facility. Therefore, in the following description, as an example, the description will be made mainly for a case where the invention is applied to a main heat exchanger provided in an air separation facility. However, the present invention is not limited to this, and a pressure loss reduction as described later is performed. The effect can be similarly applied to other heat exchangers.

[0002]

2. Description of the Related Art An air separation method for separating air into nitrogen gas and oxygen gas is used in a wide range of fields such as steelmaking, chemicals, and electronics. Various studies have been conducted on such an air separation method for the purpose of improving separation efficiency, lowering running costs, improving operation stability, and the like.

FIG. 1 is a flowchart illustrating a known air separation facility. The raw air passes through an air filter 1, a raw air compressor 2, a cooler 3, and the like, is converted into air having a desired pressure, temperature, and humidity (hereinafter, may be referred to as compressed air), and is guided to a molecular sieve adsorber 6. The molecular sieve adsorber 6 shown in FIG.
Inside, the moisture, carbon dioxide gas, hydrocarbon gas and the like in the compressed air are almost completely removed by the adsorption action of zeolite and the like. The compressed air led out from the adsorber 6 through the pipe 6a is led to the main heat exchanger 7, where it is cooled to near the liquefaction point by heat exchange with a return gas, which will be described later.
Into the lower part of the lower tower 8a.

The compressed air introduced into the lower tower 8a is
A is rectified and separated while ascending in a, and is taken out from the upper portion of the lower column 8a as a low boiling point nitrogen-rich liquid (liquid nitrogen) 9,
On the other hand, in the lower part, a high boiling point oxygen-rich liquid 10 is stored (hereinafter sometimes referred to as a coarse distillation step). The nitrogen-rich gas in the upper part is guided to the main condenser 8b by the line 13, where it is liquefied and descends along the line 14 to return to the upper part of the lower column 8a.
The nitrogen-rich liquid in the upper part of the lower tower 8a is led to the top of the upper tower 8c via the supercooler 12 by the pipe 15.

[0005] On the other hand, the oxygen-rich liquid 10 is guided from a pipe 25 to a middle stage of the upper tower 8c via the subcooler 12. From the middle stage of the lower tower 8a, liquid nitrogen in the middle stage of the rough distillation process is guided from the pipe 11 to the upper stage of the upper tower 8c via the supercooler 12. As described above, the low-temperature liquid nitrogen and oxygen-rich liquid 10 introduced from the middle, upper, and top portions of the upper tower 8c and descending in the upper tower 8c undergo mass transfer with the gas rising in the upper tower 8c. The rectification proceeds by being performed.

[0006] By repeating these steps, nitrogen gas is separated at the top of the upper tower 8c. on the other hand,
Liquid oxygen is stored in the lower part of the upper tower 8c, and oxygen gas is extracted from slightly above the liquid level. These gases are returned to the main heat exchanger 7 from the pipes 16 and 17 as the return gas, and exchange heat with compressed air derived from the molecular sieve adsorber 6 to utilize the cold. Later, it is commercialized as nitrogen and oxygen.

At this time, a part of the compressed air derived from the adsorber 6 is branched before being introduced into the main heat exchanger 7, and is compressed by the pressurizer 5a on the inlet side of the expansion turbine 5. From the main heat exchanger 7, is cooled on the high-temperature side of the main heat exchanger 7, is extracted from the middle thereof, is returned to the expansion turbine 5, and is further cooled by being adiabatically expanded, and then cooled in the upper tower. 8c is introduced to the middle stage. Further, from a position slightly lower than the upper part of the upper tower 8c, the roughly separated exhaust gas is extracted via the pipe 20 and is returned from the subcooler 12 via the main heat exchanger 7 as heat exchange gas. After the cold is used, the exhausted nitrogen gas after the heat exchange is supplied to the adsorber 6 through the heater 29 for regeneration, and is used for the regeneration of the molecular sieve in the adsorber 6, and the excess exhausted nitrogen gas is supplied to the pipe 21. The cooling water supplied to the evaporative cooler 4 is used to cool the cooler 3 and is discharged after cooling. After regeneration heating of the adsorber 6, which was cooled by supplying the exhaust nitrogen gas into the adsorber 6 after regeneration heating by switching the valves V _1, V _2, completing the handoff preparation for the adsorption step. The adsorber 6
Exhaust nitrogen gas used for the regeneration of methane is sequentially discharged out of the system.

The main heat exchanger disposed in such an air separation device is a corrugated fin (a plain fin, a herringbone fin, a perforate fin, a louver fin, a serrate fin, etc.) in order to enhance heat exchange efficiency.
As a main heat exchange member, assembling the units having distributors attached to the outlet side and the inlet side of each fluid in a multi-stage manner, and flowing the fluids to be mutually heat-exchanged to the adjacent units by counterflow. It is configured to perform heat exchange.

For example, FIGS. 6A to 6D show corrugates.
It is a schematic explanatory view illustrating a fin-type heat exchange unit,
Distributor according to the four fluids undergoing heat exchange
Types of heat exchange units A with different inlet and outlet flow paths₁ 
~ A_Four Which are superimposed next to each other
Thus, the main heat exchanger A is configured. these
In the figure, HE is a heat exchange part, and Da, Db, Dc, Dd.
And D₁ , D_Two , D _Three , D_Four Indicates distributor
And the outlet and inlet sections by each of these distributors.
Are formed at different positions, for example, heat exchange
Unit A₁ , A_Two , A_Four The nitrogen gas, oxygen gas and
Exhaust nitrogen gas flow path, heat exchange unit A _Three The compressed air of
Flow passages, which are stacked adjacent to each other.
Assemble them as shown in Figs.
The main heat exchanger A is attached with a heater H.

Here, the distributor is provided for uniformly distributing the fluid entering from the inlet to the heat exchange section HE composed of wide and fine pitch corrugated fins in each unit. For example, as shown in FIGS. 6 and 7, the fluid can be distributed and introduced in the width direction of the heat exchange section by a corrugated plate having a coarse pitch, or the fluid can be collected and discharged from the width direction of the heat exchange section. Is configured.

However, in such a conventional main heat exchanger,
The flow direction of the fluid is changed particularly at the outlet side distributor portion of each heat exchange unit, and each fluid flows in a state where the flow path is narrower than the heat exchange portion HE. Inevitable. If such pressure loss occurs in the return gas, particularly in the flow path of exhaust gas or nitrogen gas, which has a particularly high flow rate, it has a noticeable adverse effect on the operating pressure of the entire air separation device for the reasons described below, The power of the air compressor must be considerably increased.

On the other hand, in such an air separation facility,
It is known that the power of the air compressor immediately becomes the power performance of the device, but the lower the outlet pressure of the air compressor, the lower the power of the air compressor and the higher the performance of the device as a whole. Various studies have been made as a means for improving performance in a direction of lowering the outlet pressure of the air compressor.

That is, according to the results of experiments conducted by the present inventors, the pressure of the discharge line was set to, for example, 0.1 kg / c.
Reducing m ² G reduces the air compressor outlet pressure by about 0.3
This leads to a reduction of 5 kg / cm ² G. In this, a main condenser 8b is provided in an air separation facility, in which heat exchange is performed between oxygen at the bottom of the upper rectification column and nitrogen at the top of the lower column, where oxygen-nitrogen is exchanged. This is because the differential pressure in the low-pressure system is related to the differential pressure in the high-pressure system due to the boiling point under each pressure.

For example, the boiling point of oxygen at the bottom of the rectification column is
For example, at -1.4 ° C. at about 1.4 kg / cm ² A, this oxygen is -178 at 5.4 kg / cm ² A at the top of the lower tower.
Although it is evaporated by nitrogen at 2 ° C. (that is, oxygen is evaporated by nitrogen and nitrogen is condensed), the pressure of oxygen at the bottom of the rectification column is reduced by about 0.1 kg / cm ² A to about 1.3 kg / cm 2. ^{At 2} A, the temperature is -180.7 ° C. and evaporates with nitrogen at -179 ° C. at 5.05 kg / cm ² A at the top of the lower tower. That is, the outlet pressure from the low pressure system, that is, the upper tower, is set to 0.
If the pressure is reduced by 1 kg / cm ² A, the inlet pressure of the high-pressure system, that is, the lower tower, is reduced by 0.35 kg / cm ² A (5.4-5.05 kg / cm ² A).

As is clear from this, in order to reduce the outlet pressure of the air compressor at the time of performing the air separation method, the pressure of the high-pressure system (that is, the inlet line to the rectification column) must be reduced. It is more effective to suppress the pressure of the low-pressure system (that is, the extraction line from the upper tower of the rectification tower) than to suppress the pressure, that is, to reduce the pressure loss of the low-pressure system as much as possible when performing the air separation method. Greatly contributes to power reduction. And
Among the pressure losses occurring in the extraction line of the low-pressure system,
The pressure loss occurring in the main heat exchanger part accounts for a considerable proportion, and reducing the pressure loss in the main heat exchanger is due to the reduction in the operating pressure of the low pressure system of the air separation equipment and, consequently, the feed air compressor. This greatly contributes to power reduction.

However, in the conventional main heat exchanger as described above, the flow direction of the fluid is changed at the outlet distributor portion of each heat exchange unit, and the flow path is narrower than the heat exchange portion HE. Since each fluid flows in the state, a large pressure loss is unavoidable during this time. If such a pressure loss occurs in the return gas, especially in the flow path of exhaust gas or nitrogen gas, which has a particularly high flow rate, it has a significant adverse effect on the operating pressure of the air separation device as a whole, and the power of the raw material air compressor is reduced. You have to raise it considerably.

The pressure loss occurring in such a distributor section is not limited to the distributor of the main heat exchanger provided in the above-described air separation facility, but may be, for example, a corrugated fin-type heat exchanger provided in other chemical equipment or air conditioning equipment. This also occurs in the case of a distributor for an exchange.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a corrugated fin type including a main heat exchanger provided in an air separation facility. In order to reduce the pressure loss that cannot be avoided in heat exchangers and the accompanying increase in power,
It is an object of the present invention to reduce as much as possible the pressure loss at the distributor, which is the largest cause of the pressure loss generated in the corrugated fin type heat exchanger.

[0019]

A distributor according to the present invention which can solve the above-mentioned problems is a distributor arranged at an outlet or an inlet of a fluid in a corrugated fin type heat exchanger, The gist lies in that a plurality of columns are assembled at appropriate intervals between the plates, leaving a space for fluid passage. In the distributor, an assembling interval of the columns assembled between the respective plates is set so that a pressure loss in the distributor portion is more effectively reduced. The pitch is preferably about 3 to 15 times the corrugated pitch in the fin portion. The support may be rod-shaped, but a plate-shaped support is most preferable in consideration of the workability of molding and assembly. Also, this support may be assembled separately from the plate by welding the both ends to the plates on both sides, or one end of the support may be integrally formed with one plate, and the other end may be formed. Assembling by welding to the other plate is also effective.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the distributor of the present invention is arranged at the outlet or inlet of a fluid in a corrugated fin type heat exchanger. It is constituted by assembling a plurality of pillars at appropriate intervals while leaving them. The distributor provided in the conventional corrugated fin type heat exchanger is:
As described above, it is considered essential to uniformly distribute the fluid entering from the inlet of the heat exchanger to the heat exchanger HE composed of corrugated fins having a wide width and fine pitch in each unit. For example, as shown in FIGS. 6 and 7 and the like, a structure in which a corrugated plate having a coarse pitch is interposed between plates and assembled is used. In this type of distributor, a large portion is formed in this portion as described above. It is inevitable that pressure loss will occur.

However, the inventors of the present invention have conducted various studies, and found that in the distributor, if a certain length is secured in the fluid flow direction, the gap between the plates can be maintained without disposing the corrugated plate inside. It was confirmed that the fluid was sufficiently distributed only by keeping the hollow state.
However, when assembling a heat exchanger with a large number of heat exchange units to which a distributor is attached, a large clamping force acts between the plates constituting the distributor, so that a pressure resistance sufficient to withstand the clamping force is applied. It is essential to ensure strength.

That is, it is considered effective to design the distributor with a focus on the pressure resistance rather than the fluid distribution function, on the premise that a sufficient fluid passage space is secured. However, in the conventional distributor of a type in which a corrugated plate is sandwiched between plates, the pressure resistance of the corrugated plate is not sufficient.Therefore, even if the pitch is increased to lower the passage resistance, there is naturally a limit. An increase in pressure loss at the corrugated plate was inevitable.

On the other hand, according to the present invention, based on the result of confirmation that the distribution of fluid in the distributor can be sufficiently ensured without special consideration, the pressure resistance between the plates, which is particularly required at the time of assembly, is improved. It was completed as a result of an improvement study with a focus on, for example, as shown in FIG.
The pillars S are assembled at arbitrary intervals between Ps, and the pillars S can secure a pressure resistance enough to withstand the binding force at the time of assembly. That is, the support S functions as a beam between the plates P disposed at both ends thereof, and supports the restraining force applied in the vertical direction of the drawing. And since such a pillar has a superior pressure resistance compared with the conventional corrugated plate, it is possible to take a sufficiently large mounting interval, that is, it is possible to take a sufficiently large fluid passage space. As a result, the pressure loss at the distributor portion can be suppressed as much as possible.

As described above, the present invention is characterized in that the struts S are assembled at appropriate intervals between the plates P and P to increase the pressure resistance, and the most significant feature is obtained.
Any shape or structure may be used, and it is effective to assemble it as a rod-shaped support with a cross section of round or rectangular from the viewpoint of securing the passage space for the fluid. In the case of the column, the operation of joining both ends of the column by brazing between the plates P becomes extremely complicated, which not only increases the production cost but also makes mass production difficult. Therefore, in consideration of manufacturing cost, productivity, and the like, it is advantageous to use a plate-shaped support S as shown in FIG. 2 and assemble it between the plates P, P by a known means such as brazing. . At this time, as shown in FIG. 3, a method of integrally forming one plate P and a plate-shaped support S by a drawing method or the like, and a method of joining another plate P to the other end of the support S is employed. Then, the positioning and fixing of the column S can be performed very easily, so that such a structure can be said to be the most practical one in view of the easiness of manufacture.

However, since the present invention is characterized in that the pressure resistance between the plates is enhanced by the columns as described above, the specific shape and structure of the columns are not limited, and other shapes such as a rod shape or the like may be used. Of course, it is also possible to use a structural support. When a plate-shaped support is used, the plate-shaped support is not only linear, but also curved in the fluid flow direction as shown in FIG. 4 to reduce the flow resistance, or as shown in FIG. It is also possible to drill any size and any number of holes W through which fluids can diverge from one another.

Although it is advantageous to reduce the pressure loss, it is advantageous to set the interval between the columns S as wide as possible as long as the required pressure resistance can be ensured. However, the present inventors have confirmed that the effect of reducing the pressure loss is effective. In order to demonstrate
If the plate-like supports are assembled at intervals of about 3 to 15 times the fin pitch of the corrugated fins constituting the heat exchange section (for example, reference numeral HE in FIGS. 6 and 7) of the applied heat exchange unit, the heat exchange It has been found that the pressure loss in the unit can be sufficiently reduced. Thus, if the installation interval is excessively wide exceeding 15 times, the pressure resistance strength tends to be insufficient or the support must be excessively thick. On the other hand, if the support installation interval is less than 3 times, This is because the pressure resistance can be sufficiently increased, but it is difficult to obtain a satisfactory pressure loss reduction effect.

By the way, the corrugated fin type heat exchanger
The relationship between design pressure, pitch and plate thickness in the following equation
Can be t_p = P_t √ (P / 200σa) t_p : Separate sheet thickness, P_t : Pitch, P: Pressure
Force, σa: allowable stress of material (normal Al alloy is 2.3) Sheet thickness used for corrugated fin for heat exchanger
Is usually 1 mm and σa is 2.3.
Force 1.0kg / cm^Two Pitch P when G _t On
From the notation, P_t = T_p /√(P/200σa)=1.0/√(1.0/200·2.3)=21.4m
m.

On the other hand, in order to secure the strength to withstand the load when the heat exchange unit is assembled by brazing, it must satisfy the buckling resistance (P _cr ) calculated by the following equation. During buckling strength ^{_{(P cr) = 4π 2 EI}} / l 2, I = tl 3/12 ( wherein, E: elastic modulus, I: sectional secondary moment, l:
Fin height t: Indicates fin plate thickness)

Now, two types of corrugated fins of the same material, of the same fin height and of different plate thicknesses (therefore E and l)
The same), when determining the formula of the seat of each column strength P _Cr1, P _Cr2, becomes as the following equation, when the fin thickness is _{t 1: P Cr1 = [4π} 2 · E · (t 1 · l ^3/1
2) / l ^3)] When the fin thickness is _{t 2: P Cr2 = [4π} 2 · E · (t 2 · l 3/1
Than 2) / l ^3)] the above _{equation, P Cr1 / P Cr2 = t} 1 / t 2 is derived. Further, under the condition that the same buckling strength is ensured, there is a substantially proportional relationship between the fin pitch (P) and the fin plate thickness (t), so that t ₁ / t ₂ = P _t1 / P _t2 Holds.

Then, for example, 4.2 m generally used as a corrugated fin of a main heat exchanger for an air separator.
The thickness of the m-pitch fin is 0.4 mm, and the design fin pitch is 21.4 m when the thickness is 1 mm as described above.
m, these values are substituted into the above equation to determine the fin plate thickness for obtaining the buckling strength that can withstand the load at the time of assembling: 4.2 / 0.4 = 21.4 / t, That is, t ≒ 2 mm is derived. As a result, the fin thickness is 2 mm at the 21.4 pitch, but it is possible to secure a larger flow path area than that of the fin thickness of 0.4 mm at the 4.2 pitch.

On the other hand, the fin pitch of a normal corrugated fin used for a heat exchanger is Max: 4.2 m.
Since m and Min are 1.4 mm, considering these values, it is preferable to use the reinforcing column for securing the buckling strength against the load at the time of brazing by the reinforcing column provided in the distributor. When the mounting interval is determined, the minimum value is the Max / min ratio of the fin pitch, that is, 4.2 /
1.4 (= 3 times), and the maximum value is the ratio (ie, 21.4) of the corrugated fin pitch to the set fin pitch (ie, 21.4) with respect to the Min value (1.4).
/1.4=15 times), and the preferable minimum pitch interval of the reinforcing columns = 4.2 / 1.4.
= 3 times, preferred maximum pitch spacing of reinforcement columns = 21.4 / 1.
4 = 15 times. That is, by setting the mounting interval of the reinforcing columns in the distributor portion to be 3 to 15 times the fin pitch in the heat exchange section, sufficient buckling strength can be secured without alienating the fluid flow. Will be.

The constituent material of the distributor according to the present invention is not particularly limited, and stainless steel, copper and its alloys, aluminum and its alloys can be arbitrarily selected and used. Aluminum alloys are the most common, considering the brazing properties at the time.

As described above, in the present invention, the distributor provided in the corrugated fin type heat exchanger has a structure in which reinforcing columns are assembled between the plates with a particular focus on improving the pressure resistance required for the assembly and fixing. By doing so, the pressure loss can be reduced without substantially affecting the strength and fluid distribution performance when assembling the heat exchange unit, and as a result, the fluid introduced into the heat exchanger can be reduced. The feed driving force can be reduced, and the operating power cost and the like of the heat exchange device can be suppressed. Therefore, the distributor of the present invention can significantly reduce the running cost when operating a heat exchanger used in various other fields as well as a main heat exchanger provided in an air separation facility as shown in FIG. 1, for example. Can contribute.

[0034]

The present invention is configured as described above. By using this distributor, the pressure and the fluid distribution performance at the time of assembling the heat exchange unit can be reduced without substantially affecting the fluid distribution performance. The loss can be reduced, and the driving force for feeding the fluid introduced into the heat exchanger can be reduced, which can contribute to the reduction of running costs including the operating power cost of the heat exchanger.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an air separation facility as one use form of a heat exchanger with a distributor of the present invention.

FIG. 2 is a partially cutaway perspective view illustrating a distributor according to the present invention.

FIG. 3 is a partially cutaway perspective view illustrating another distributor according to the present invention.

FIG. 4 is a partially cutaway perspective view illustrating still another distributor according to the present invention.

FIG. 5 is a partially cutaway perspective view illustrating still another distributor according to the present invention.

FIG. 6 is a schematic front view illustrating a heat exchange unit constituting a main heat exchanger for an air separation facility.

FIG. 7 is a partially cutaway view showing an assembled state of the heat exchange unit.

FIG. 8 is a schematic view illustrating a main heat exchanger in which a header is attached to an inlet / outlet of a fluid.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Air filter 2 Raw material air compressor 3 Cooler 4 Evaporative cooler 5 Expansion turbine 6 Molecular sieve adsorber 7 Main heat exchanger 8 Rectification tower 8a Lower tower 8b Main condenser 8c Upper tower 9 Nitrogen rich liquid 10 Oxygen rich liquid 29 regeneration heater U, U 'heat exchange unit _{D 1, D 2, D 3} , D 4, D 5 distributor F corrugated fin P plate S strut W hole

Claims (5)

[Claims] 1. A distributor arranged at an outlet or an inlet of a fluid in a corrugated fin type heat exchanger, wherein a plurality of columns are appropriately spaced between respective plates while leaving a fluid passage space. Distributor for heat exchangers, characterized by being assembled in the above. 2. The distributor according to claim 1, wherein the spacing between the columns is 3 to 15 times the corrugated pitch of the corrugated fins constituting the heat exchange section of the corrugated fin heat exchanger. 3. The distributor according to claim 1, wherein the support is a plate-like member. 4. The distributor according to claim 2, wherein one end of the support is integrally formed with one plate and the other end is welded to the other plate. 5. The distributor according to claim 2, wherein both ends of said column are welded to plates on both sides.