JP2012145006A - Thermo compressor and seawater desalination system provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermo compressor with improved performance.SOLUTION: The thermo compressor is provided with a tubular suction chamber 1 where driven steam flows in an axial direction, and a nozzle 4 positioned inside the suction chamber, equipped with a tubular wall, and which supplies motive steam to the suction chamber. The driven steam S1 is flowed through an outer space A between the outer periphery of the nozzle and the inner wall face of the suction chamber and through the inner space B of the nozzle. The nozzle includes a flow channel through which the motive steam S2 passes. The flow channel is formed in a circular shape that continues inside the wall, extends in the axial direction, and opens on the downstream side.

Description

  The present invention relates to a thermocompressor and a seawater desalination apparatus including the same.

  As a steam ejector proposed conventionally, there exists a thing of patent document 1, for example. This steam ejector has a cylindrical intake chamber, and a diffuser having a wide hem is connected to one end portion of the intake chamber via a throat portion having a small diameter. A cylindrical steam nozzle is coaxially disposed inside the intake chamber. When driving steam is supplied to the steam nozzle, the driving steam is ejected from the intake chamber toward the throat portion, and is discharged through the diffuser. At this time, in the intake chamber, the driven steam is sucked and discharged from the diffuser together with the driving steam. Thus, this steam ejector functions as a pump for evacuation.

JP 2002-130200 A

  However, when the steam ejector as described above is used as, for example, a salmon compressor of a seawater desalination apparatus, the increase in discharge pressure greatly affects the size of the heat transfer area of the evaporator of the seawater desalination apparatus. Improvement is an issue. That is, there is room for improvement when a conventional steam ejector is used as a thermocompressor, and improvement in performance has been desired.

  The present invention is for solving the above-described problems, and an object thereof is to provide a thermocompressor capable of improving performance.

  A thermocompressor according to the present invention includes a cylindrical suction chamber in which driven steam flows in an axial direction, a nozzle that is disposed inside the suction chamber, has a cylindrical wall, and supplies driving steam to the suction chamber The driven steam flows through an outer space between the outer peripheral surface of the nozzle and the inner wall surface of the suction chamber and an inner space of the nozzle, and the driving steam passes through the nozzle. The flow path is formed in an annular shape that is continuous inside the wall, and extends in the axial direction so as to open on the downstream side thereof.

  According to this configuration, a nozzle having a continuous annular opening is disposed inside the suction chamber for flowing the driven steam, and the driving steam having an annular flow is discharged from the nozzle. Therefore, the driven steam flowing on the outer peripheral surface and the inner peripheral surface of the annular flow can be effectively pulled, and the flow velocity can be increased. In particular, the driving steam discharged in an annular shape is in contact with both the driven steam flowing in the external space between the nozzle and the suction chamber and the driven steam flowing in the internal space of the nozzle. Effects can be obtained. First, since the driven steam flowing in the internal space of the nozzle is entirely surrounded by the driving steam, a larger traction force acts on the driving steam flowing in the external space. As a result, the driven steam flowing in the internal space tends to have a higher flow velocity. Thus, when the flow velocity is increased, the pressure is lower than that of the driven steam flowing in the external space. At this time, the driven steam flowing in both spaces is separated by the annular driving steam, so that they are in contact with each other. I can't. As a result, the driven steam flowing in the internal space maintains a balanced pressure with the driven steam flowing in the external space, and thus the flow area is reduced. In particular, in the conventional thermocompressor, since the suction chamber has a tapered shape, the flow area of the driven steam is reduced. However, in the present invention, the flow is further increased by the above mechanism. The cross-sectional area can be reduced. As a result, the increase in flow velocity and pressure is increased, and the driven steam can be effectively compressed.

  Furthermore, since the contact area between the driving steam and the driven steam is large, the momentum of the driving steam is quickly transmitted to the driven steam, and the flow velocity of the driving steam itself decreases. This increases the cross-sectional area of the flow and keeps the pressure in equilibrium with the driven steam flowing through the internal space. Here, if the driven fluid is not a vapor but a liquid, the driving vapor discharged into the liquid (driven fluid) is considered to pull the liquid (driven fluid) in the axial direction. At the same time, it is considered that most of the driving steam is condensed. Therefore, unlike the present invention, there is no effect of separation of the driven fluid by the driving steam, and there is no effect of change in the flow cross-sectional area of the driving steam and the driven fluid. I don't play.

  The flow path inside the nozzle can be formed as follows. That is, the flow path has a narrowed portion in which the radial length gradually decreases as it goes from the upstream side in the axial direction to the downstream side, and the radial length as it goes from the upstream side in the axial direction to the downstream side. An opening portion that gradually increases in length and communicates with the opening, and a connecting portion that communicates the narrowed portion and the opening portion in the axial direction can be formed.

  In this way, the driving steam can reach the speed of sound at the connecting portion while being compressed by the constriction. And since the opening part which continues after that is the end, the cross-sectional area of drive steam increases gradually, As a result, it becomes possible for the flow velocity to exceed the speed of sound (it reaches about 3 times the speed of sound). When such high-speed driving steam exceeding the speed of sound comes into contact with the driven steam in the suction chamber, the driven steam can be pulled and compressed while changing the flow cross-sectional area without being mixed with each other effectively.

  The nozzle wall can be produced by various methods.For example, a cylindrical outer cylinder and a diameter smaller than the outer cylinder, and a gap is formed in the radial direction in the internal space of the outer cylinder. It is comprised with the cylindrical inner cylinder arrange | positioned, and the said clearance gap can form a flow path. For example, the formation of the narrowed portion and the open portion as described above is difficult in cutting, but can be easily formed by arranging the outer cylinder and the inner cylinder at a predetermined interval.

  In the thermocompressor, the shape of the suction chamber is not particularly limited, and may be a form in which the diameter becomes narrower toward the tip or a form in which the diameter is constant. For example, a diffuser whose length in the radial direction gradually increases from the upstream side in the axial direction to the downstream side, and a suction chamber and a throat portion that communicates the diffuser in the axial direction are further provided, and the suction chamber The length in the radial direction is gradually reduced from the upstream side in the axial direction to the downstream side, and the length can be connected to the throat.

  Further, the seawater desalination apparatus according to the present invention comprises any one of the above-described thermocompressors and a plurality of utility cans arranged in series from upstream to downstream while heating and evaporating seawater supplied from outside. The steam is supplied from the thermocompressor to the uppermost effect can among the plurality of effect cans, and the steam heated and evaporated by each effect can is sequentially supplied to the effect cans on the downstream side. The steam generated by the effect can located downstream is supplied to the thermocompressor as driven steam.

  According to the thermocompressor according to the present invention, it is possible to improve both the discharge pressure and the amount of suction steam and improve the performance.

It is sectional drawing which shows one Embodiment of the thermocompressor which concerns on this invention. It is an expanded sectional view of the suction chamber of the thermocompressor shown in FIG. 3 is a cross-sectional view taken along line AA in FIG. 4 is a partially enlarged sectional view of FIG. It is a schematic block diagram of the multiple effect type seawater desalination apparatus using the thermocompressor of FIG. It is a partial cross section figure of the thermocompressor concerning an example. It is sectional drawing of the thermocompressor which concerns on a comparative example.

  Hereinafter, an embodiment in which a thermocompressor according to the present invention is applied to a multi-effect seawater desalination apparatus will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a thermocompressor applied to this apparatus.

  First, the thermocompressor according to this embodiment will be described. As shown in FIG. 1, this thermocompressor has a cylindrical suction chamber 1 that mixes sucked driven steam S1 and driving steam S2 and discharges them downstream, and downstream of the suction chamber 1. On the side, the throat 2 and the diffuser 3 formed in a cylindrical shape are connected in this order. As will be described later, the diameter of the end portion on the downstream side of the suction chamber 1 gradually decreases, and the throat portion 2 is connected to this end portion. The throat portion 2 has a constant diameter and a short axial length, and a diffuser 3 is attached to an end portion on the downstream side. The diffuser 3 has a taper-like diameter that increases toward the downstream, and is longer in the axial direction than the throat 2. With such a configuration, the driven steam S1 and the driving steam S2 are mixed in the suction chamber 1 to become a mixed steam S3, and this mixed steam S3 is discharged to the outside through the throat 2 and the diffuser 3.

  Next, the suction chamber 1 will be described with reference to FIGS. 2 is an enlarged sectional view of the suction chamber, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a partially enlarged sectional view of FIG. As shown in FIG. 2, a nozzle 4 that discharges driving steam S <b> 2 is disposed inside the suction chamber 1. In the suction chamber 1, the driven steam S1 is sucked from the suction port 11 on the left side of FIG. From the suction port 11 to the downstream side, the inner diameter is constant up to the portion where the nozzle 4 is disposed, but the inner diameter is tapered from the downstream side slightly smaller than the tip of the nozzle 4. It is connected to the throat 2.

  The nozzle 4 is formed in a cylindrical shape and is arranged so as to be coaxial with the axis L of the suction chamber 1. The suction chamber 1 is supported by a supply pipe 5 extending in the radial direction from the inner wall surface of the suction chamber 1. A flow path 41 through which the driving steam S2 passes is formed inside the cylindrical wall constituting the nozzle 4, and the supply pipe 5 described above is connected to the rear end portion of the flow path 41, and the driving steam S2 Is supplied into the flow path 41. The flow path 41 is formed in a continuous annular shape along the wall of the nozzle 4, extends in the axial direction, and has an opening 42 at the downstream end of the nozzle 4. Further, as shown in FIG. 4, when viewed in the cross section shown in FIG. 4, the flow path 41 has a constant radial width d at the connection portion with the supply pipe 5, but from here to the downstream side. It is changing. That is, the narrowed portion 412 whose width in the radial direction is tapered from the connecting portion 411, the connecting portion 413 having a constant width communicating with the narrowed portion 412, and the tapered width from the connecting portion 413 toward the downstream side. It is comprised with the open part 414 which becomes large. The opening 414 is connected to the opening 42 at the nozzle end described above.

  Such a nozzle 4 is formed by combining an outer cylinder 401 and an inner cylinder 402 in order to easily form the flow path 41. The outer cylindrical body 401 is formed in a cylindrical shape, and has an inner peripheral surface corresponding to the outer wall surface of the flow path 41. On the other hand, the inner cylindrical body 402 is formed in a cylindrical shape having a smaller diameter than the outer cylindrical body 401, and the outer peripheral surface has a shape corresponding to the inner wall surface of the flow path 41. Thereby, a gap formed when the inner cylinder 402 is coaxially inserted into the outer cylinder 401 constitutes the flow path 41. Further, the supply pipe 5 described above is fixed to the rear end portion of the outer cylindrical body 401 so as to penetrate the wall of the outer cylindrical body 401. Further, a fixing flange 46 is provided at the rear end of the outer cylinder 401. On the other hand, the inner cylinder 402 is also provided with a fixing flange 47 at the rear end, and is arranged so as to contact the rear end of the flange 46 of the outer cylinder 401. And these flanges 46 and 47 are fixed with the volt | bolt 48, and the outer cylinder 401 and the inner cylinder 402 are fixed fixedly.

  Next, the operation of the thermocompressor configured as described above will be described. First, the driving steam S <b> 2 is supplied to the flow path 41 of the nozzle 4 through the supply pipe 5. The supplied driving steam S2 is compressed by passing through the constricted portion 412 of the flow path 41, and then released from the compression through the connecting portion 413 and the opening portion 414. Therefore, from the nozzle opening 42, High-speed steam is discharged.

  On the other hand, the driven steam S1 is introduced from the rear end of the suction chamber 1. The driven steam S <b> 1 flows downstream while passing through the two spaces of the outer space A between the outer peripheral surface of the nozzle 4 and the inner wall surface of the suction chamber 1 and the inner space B of the nozzle 4. The driven steam S1 is discharged from the suction chamber 1 while increasing the flow velocity while being sucked downstream by the discharged driving steam S2.

  More specifically, since the driving steam S2 discharged from the nozzle 4 receives the viscous resistance of the driven steam S1 from both the inner space B side and the outer space A side, the cross-sectional area of the flow of the driving steam S2 is enlarged. Then, the driven steam S1 is pulled on both sides described above. At this time, the driven steam S1 flowing in the external space A has its outer peripheral surface in contact with the inner wall surface of the suction chamber 1 and receives resistance, but the inner peripheral surface is pulled by the driven steam S1 and the flow velocity increases. To do. On the other hand, the driven steam S1 flowing through the inner space A is pulled by the driving steam S2 that surrounds the entire outer periphery thereof, but does not receive the resistance as the driven steam S1 flowing through the outer space A. The flow rate is further increased. Along with this, the pressure decreases, so that the cross-sectional area of the flow of the driving steam S2 surrounding it increases and the flow velocity also increases. At this time, since the driven steam S1 flowing through both spaces A and B is separated by the annular driving steam S2, they are in a state where they cannot contact each other. As a result, the flow area of the driven steam S1 flowing through the internal space B is reduced in order to maintain a pressure balance with the driven steam S1 flowing through the external space A. That is, in the suction chamber 1, exchange of momentum is performed between the driving steam and the driven steam. By the mechanism as described above, the driven steam S1 is sucked so as to increase the flow velocity and pressure, is discharged from the suction chamber 1 while being mixed with the driving steam S2, and flows to the throat 2.

  Since the diameter of the downstream side of the suction chamber 1 becomes smaller, the driving steam and the driven steam become higher in the process of being discharged from the suction chamber 1. The mixed steam S3 that has passed through the throat 2 enters the diffuser 3, but the diameter of the diffuser 3 increases as it goes downstream. Is discharged. That is, the velocity component is converted into the pressure component from the throat 2 to the diffuser 3, and compression is performed.

  As described above, according to the present embodiment, the nozzle 4 having the annular opening 42 is disposed inside the suction chamber 1 through which the driven steam S <b> 1 flows, and the driving steam S <b> 2 that forms an annular flow is supplied from the nozzle 4. I am trying to discharge. Therefore, the driven steam S1 flowing on the outer peripheral surface and the inner peripheral surface of the annular flow can be effectively pulled and the flow velocity can be increased.

  Next, a multiple seawater desalination apparatus using the thermocompressor will be described. FIG. 5 is a schematic configuration diagram of a multi-effect seawater desalination apparatus. As shown in the figure, the seawater desalination apparatus itself is a known apparatus, and in this example, a four-effect system having four effect cans is shown. First, seawater is sent into a condenser, and the temperature is raised by condensing the steam sent from the four effects. And the seawater which passed through the capacitor | condenser is supplied to each effect can. For example, seawater supplied to the first effect can is heated and evaporated by heated steam. The generated steam enters the heating section tube of the second effect can, and the supplied seawater is heated and evaporated. In this process, a part of the steam is condensed into fresh water. Thus, the steam generated in the previous effect can is utilized for heating and evaporation of seawater.

  By the way, the feature of this seawater desalination apparatus is that the above-described thermocompressor is used. That is, the driven steam S1 supplied to the thermocompressor is the steam discharged in the fourth effect, and the heated steam as the driving steam S2 is supplied to the thermocompressor to make the driven steam S1 into a high pressure and to have one effect. To supply. That is, in general, the four-effect steam supplied only to the condenser is supplied to the thermocompressor.

  Here, if the intake steam amount / heated steam amount = suction ratio, the amount of steam to be sucked is a design factor determined by each system design, but there is a limit to the capacity of the thermocompressor. If the suction ratio is 1, the steam introduced into the 1-effect heating unit is 2 when the heating steam is 1, so that 8 distilled water is obtained in the 4-effect system. In this case, the temperature of one effect is influenced by the ability of the thermocompressor in addition to the viewpoint of scale prevention, and the limit is around 65 ° C.

  In order to operate as described above, for example, when a device with GOR (distilled water amount / heated steam amount: Gain output Ratio) = 8 is designed, if there is a thermocompressor with a suction ratio of 1, a 4-effect system is possible. For example, assuming that the temperature for one effect is 65 ° C. and the temperature for the fourth effect is 50 ° C., the operating temperature difference for each effect is (65−50) / 4 effect = 3.75 ° C. On the other hand, when there is no thermocompressor, eight utilities are required to design a device with GOR = 8. Even at this time, if the operating temperature for one effect is 65 ° C., the temperature difference between each effect is 3.75 / 2 = 1.875 ° C., and the heat transfer area of the heating section for each effect is approximately doubled. Let's go. Here is the important role of the thermocompressor. At this time, if the compression capacity of the thermocompressor is maintained at the suction ratio 1 and can reach 68 ° C., the difference is only 3 ° C., but the temperature difference between the effects is (68-50). ) /4=4.5° C. Therefore, the heat transfer area is 3.75 / 4.5 = 0.8333, which can be reduced by about 17%. Further, when a device with GOR = 10 is required, a 5-effect system is required for a thermocompressor with a suction ratio of 1, but if a thermocompressor with a suction ratio of 1.5 is used, a 4-effect system is sufficient, and about 20 % Heat transfer area can be reduced.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the seawater desalination apparatus described above, steam generated in the fourth effect is supplied to the thermocompressor as driven steam, but steam generated in other effects can also be used.

  Examples of the present invention will be described below. However, the present invention is not limited to the following examples.

  As an example, as shown in FIGS. 1 to 6, a thermocompressor equivalent to that shown in the above embodiment was used, and as a comparative example, a thermocompressor shown in FIG. 7 was used. Although FIG. 7 omits the description of the throat and the diffuser, it is the same as FIG. And these were driven and the cross-sectional area, pressure, temperature, etc. of the flow were measured. The suction ratio was 1.4. The results are as shown in Table 1 below.

  As described above, in this example, the comparison was made with the suction ratio = 1.4. However, in the example and the comparative example, a difference occurred in the throat that passed through the suction chamber. That is, the driving steam has a lower flow velocity, a larger flow cross-sectional area, and a higher pressure. And the tendency of such a pressure is the same also in a diffuser exit. On the other hand, it is considered that the same effect can be obtained even when the inhalation ratio is other than 1.4. Moreover, even if the temperature range is a low range other than this, or a high range exceeding 100 ° C., it is considered that the same effect can be obtained. In addition, when the compression temperature difference is made the same, the suction ratio can be made higher than that of the nozzle of the comparative example, and it is obvious that it can be derived from the unique effect of the annular nozzle as in the embodiment. Thus, since the thermocompressor of the present embodiment compresses low-pressure steam using driving steam, this effect can be applied to various devices unexpectedly in a seawater desalination apparatus. For example, the same effect can be obtained with a heat transfer device having a smaller heat transfer area.

DESCRIPTION OF SYMBOLS 1 Suction chamber 4 Nozzle 401 Outer cylinder body 402 Inner cylinder body 41 Flow path 412 Narrow part 413 Connection part 414 Opening part 42 Opening A External space B Internal space S1 Driven steam S2 Driven steam S3 Mixed steam

Claims (5)

A cylindrical suction chamber in which driven steam flows in the axial direction;
A nozzle that is disposed inside the suction chamber, has a cylindrical wall, and supplies driving vapor to the suction chamber;
The driven steam flows in the outer space between the outer peripheral surface of the nozzle and the inner wall surface of the suction chamber, and the inner space of the nozzle,
The nozzle has a flow path through which the driving steam passes, and the flow path is formed in an annular shape that is continuous inside the wall, and is formed to extend in the axial direction and open downstream thereof. The thermocompressor. The flow path of the nozzle is
A constricted portion that gradually decreases in length in the radial direction from the upstream side to the downstream side in the axial direction;
An opening that gradually increases in length in the radial direction from the upstream side to the downstream side in the axial direction and leads to the opening;
A connecting portion for communicating the narrowed portion and the open portion in the axial direction;
The thermocompressor according to claim 1, comprising: The wall constituting the nozzle is
A cylindrical outer cylinder,
A cylindrical inner cylinder having a diameter smaller than that of the outer cylinder and arranged in a radial direction in the inner space of the outer cylinder, and
The thermocompressor according to claim 1 or 2, wherein the gap forms the flow path. A diffuser whose length in the radial direction gradually increases from the upstream side to the downstream side in the axial direction;
A throat that communicates the suction chamber and diffuser in the axial direction;
Further comprising
The thermostat according to any one of claims 1 to 3, wherein the suction chamber is connected to the throat part with a radial length that gradually decreases from the upstream side to the downstream side in the axial direction. compressor. The thermocompressor according to any one of claims 1 to 4,
While heating and evaporating seawater supplied from the outside, a plurality of effect cans arranged in series from upstream to downstream side, and
With
Among the plurality of effect cans, steam is supplied from the thermo compressor to the effect can in the uppermost stream,
The steam evaporated by heating in each of the effect cans is configured to be sequentially supplied to the effect cans on the downstream side,
A seawater desalination apparatus configured to supply steam generated by the effect can located downstream to the thermocompressor as driven steam.

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