JP2940489B2 - Double tube coil type steam generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam generator, and is used for a reboiler, a multiple effect can, a regenerator of an absorption refrigerator, an ammonia absorption type concentrator, and the like.

[0002]

2. Description of the Related Art A reboiler for generating clean steam for medical use uses steam as a heating source and heats pure water with the steam. As its structure, a shell-and-tube type is widely used.

[0003]

The above-mentioned shell and tube type reboiler has a problem that the heat transfer is not sufficient due to the stagnation area of the liquid phase, and the number of processing steps is high and the cost is high. I have. SUMMARY OF THE INVENTION An object of the present invention is to provide a steam generator in which heat transfer is improved and the size of the device is reduced, and the number of processing steps is significantly reduced.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a structure in which a double pipe in which an inner pipe is inserted concentrically in an outer pipe is wound up in a coil shape and stands up. The first feature is that a heating fluid is caused to flow from above to below in a flow passage between the outer tube and the inner tube, and a fluid to be heated is caused to flow from below to above in the inner tube.

Further, according to the present invention, a double tube in which an inner tube is concentrically inserted into an outer tube is wound in a coil shape and erected, and a cross section of one or both of the outer tube and the inner tube is provided. A substantially elliptical shape, the major axis direction is set to the vertical direction, heating fluid in the flow passage between the outer tube and the inner tube,
A second feature is that the fluids to be heated are respectively circulated in the inner pipe.

The present invention also provides a plurality of double tubes in which an inner tube is concentrically inserted into an outer tube, and the plurality of double tubes are arranged in multiple stages in a vertical direction and wound in a coil shape. A third feature is that a heating fluid flows through a flow passage between the outer pipe and the inner pipe, and a fluid to be heated flows through the inner pipe.

Further, according to the present invention, a double tube in which an inner tube is concentrically inserted into an outer tube is wound in a coil shape and erected, and the coil diameter of the coil shape is gradually increased from one end to the other end. The fourth feature is that the heating fluid is flowed through the flow passage between the outer pipe and the inner pipe, and the fluid to be heated is flowed through the inner pipe.

The present invention also provides a double tube in which an inner tube is concentrically inserted into an outer tube and wound up in a coil shape to stand up, and a separator is installed in a center space of the coil shape. A fifth feature is that a downstream end of the fluid is communicated with the separator, and a heating fluid flows through a flow passage between the outer pipe and the inner pipe, and a fluid to be heated flows through the inner pipe.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A double pipe is constructed by concentrically inserting an inner pipe into an outer pipe, and the double pipe is wound up in a coil shape and erected. Heating fluid is caused to flow from the upper part to the lower part in the flow passage between the outer pipe and the inner pipe, and the fluid to be heated is made to flow from the lower part to the upper part in the inner pipe, thereby performing heat exchange between the two. Steam is used as the heating fluid, and pure water is used as the fluid to be heated.

A separator is provided in the central space of the coil shape, and a downstream end of the inner pipe communicates with the separator. The pure water is heated to become steam and flows into the separator. The vapor from which the droplets are separated by the separator is sent to an external steam-using device, and the separated droplets are returned from the bottom of the separator to the upstream end of the inner tube.

One or both of the outer tube and the inner tube have a substantially elliptical cross section, and the major axis direction is set in the vertical direction. That is, it is a vertically long elliptical shape. By doing so, when the steam as the heating fluid condenses, the condensed water is easily separated downward. Therefore, the water film formed on the outer wall surface of the inner tube can be made thinner, and it is possible to prevent heat transfer from being hindered by the water film.

The number of the double tubes may be one, but may be plural. The plurality of double tubes are arranged in multiple stages in the vertical direction and wound in a coil shape. With this structure,
The inclination angle of each double pipe can be made larger, and a high circulation ratio can be obtained only by natural circulation (2 or more).

[0013] The coil shape of the double tube may be a parallel coil shape having the same coil diameter from one end to the other end, but is formed by gradually increasing the coil diameter from one end to the other end. It can also be tapered. Although the double pipe is wound around a cylindrical mold and formed into a coil shape, the use of a tapered mold facilitates separation between the mold and the double pipe.

The double-tube coil type steam generator of the present invention can be applied to a reboiler, a multiple effect can, a regenerator of an absorption refrigerator, an ammonia absorption type concentrator, and the like.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an embodiment of the present invention, and FIG. 2 is a plan view thereof (line configuration omitted). The inner tube 3 is concentrically inserted into the outer tube 2 to form the double tube 1, and the double tube 1 is wound up in a coil shape and stands upright.
In the illustrated embodiment, two double tubes 1 are provided, arranged in multiple stages in the vertical direction, and wound in a coil shape. That is,
It has a configuration in which two double tubes 1 are alternately arranged in the vertical direction.

The heating fluid is caused to flow from above to below in the flow passage 4 between the outer pipe 2 and the inner pipe 3, and the fluid to be heated is caused to flow from below to upper in the inner pipe 3. Heat exchange between the two. Steam is used as the heating fluid, and pure water is used as the fluid to be heated. In order to maintain the quality of pure water as feed water, stainless steel having high corrosion resistance is used as the material of the inner pipe 3. As a material of the outer tube 2, a normal steel material such as STPG is used.

At the upstream end of the outer tube 2, an upper header 6 for the outer tube is provided.
Are connected to the downstream end of the outer tube 2 with the lower header 7 for the outer tube. A heating fluid supply line 8 is connected to the upper header 6 for the outer pipe, and an electric valve 9 for controlling the supply amount of the heating fluid is inserted into the heating fluid supply line 8. The upper header 6 for the outer pipe is provided with a pressure sensor 10 for detecting the pressure of the heating fluid (the pressure in the outer pipe 2). A discharge line 12 in which a steam trap 11 is inserted is connected to the outer pipe lower header 7 for discharging condensed water.

The upstream end of the inner pipe 3 is projected through the lower header 7 for the outer pipe to connect to the lower header 13 for the inner pipe. The downstream end of the inner pipe 3 is connected to the upper header 7 for the outer pipe. 6
And projecting therethrough to connect the upper header 14 for the inner tube. A water supply line 15 for supplying a fluid to be heated is connected to the lower header 13 for the inner pipe. The water supply line 15 exchanges heat with a water supply pump 16 and the discharge line 12 to recover heat from condensed water. A heater 17 is provided. On the other hand, the separator 5 for separating the droplets in the vapor is connected to the upper header 14 for the inner pipe via a communication pipe 18. The top of the separator 5 has a steam valve 19
Is connected to the steam line 20. Further, the separator 5 is provided with a pressure sensor 21 for detecting an internal pressure. A return pipe 22 is connected to the bottom of the separator 5, and one end of the return pipe 22 is connected to the lower header 13 for the inner pipe.
The separated water separated by the separator 5 is returned to the upstream end of the inner pipe 3 and circulated. The separator 5 is provided in a coil-shaped central space formed by the double pipe 1 to save space.

The cross section of the outer pipe 2 and the inner pipe 3 may be substantially circular, but as shown in FIG. 3, one or both of the cross sections of the outer pipe 2 and the inner pipe 3 are substantially elliptical. You can also. The elliptical shape is a vertically long elliptical shape, and its major axis direction is set to the vertical direction. By doing so, when the steam as the heating fluid is condensed, the condensed water is easily separated downward, and the water film formed on the outer wall surface of the inner pipe 3 can be thinned. Therefore, it is possible to prevent the heat transfer from being hindered by the water film.

The operation of the above embodiment will be described below. Pure water as the fluid to be heated (pressure about 2kg / cm ² )
Is supplied from the water supply line 15 into the inner pipe 3 through the lower header 13 for the inner pipe, and steam (pressure of about 5
kg / cm ² ) is supplied from the heating fluid supply line 8 to the inside of the outer tube 2, that is, to the flow passage 4 through the upper header 6 for the outer tube. The fluid to be heated rises while flowing spirally along the inner pipe 3, and the heated fluid descends while flowing spirally along the flow passage 4. Then, heat exchange is performed between the two through the wall surface of the inner pipe 3, and the pure water as the fluid to be heated is heated to become steam (clean steam). The steam flows tangentially into the separator 5 through the upper header 14 for the inner pipe and the connecting pipe 18, the droplets are separated by the centrifugal force of the swirling motion, and flows out from the steam line 20. The separated droplets return to the inner tube lower header 13 through the return tube 22.
On the other hand, the steam as the heating fluid is deprived of heat and becomes condensed water, and is discharged from the discharge line 12 via the outer pipe lower header 7. At this time, the discharged high-temperature condensed water exchanges heat with the feed water when passing through the feed water heater 17 so as to preheat the feed water (in addition, the flushing of the condensed water at the time of opening to the atmosphere is prevented. ).

Since the steam as the heating fluid is caused to flow in the axial direction of the inner tube 3 along the outer wall surface of the inner tube 3, the speed can be increased, and the condensed water is generated by the shearing force when the steam flows. The film becomes thin, and the thermal resistance can be reduced.
In addition, when the cross-sectional shapes of the outer pipe 2 and the inner pipe 3 are vertically long elliptical shapes, the condensed steam is easily separated downward, and the condensed water film on the outer wall surface of the inner pipe 3 can be particularly thinned. In addition, it is possible to prevent heat transfer from being hindered by the water film.

In the inner pipe 3, since pure water as a fluid to be heated boils and forms a two-phase flow while increasing the speed, the heat conductivity is good. Further, in the inner pipe 3, as shown by an arrow in FIG. 3, a secondary flow is generated due to the centrifugal force, and the fluid to be heated is a vertically separated flow, and the two-phase heat transfer is further promoted.

According to experiments, the heat transmission coefficient of the steam generator of the present invention is about 2800 kcal / m ² h ° C., which is about 40% higher than that of the conventional shell and tube type. Further, even if the temperature difference between the heating fluid and the fluid to be heated is low, there is a tendency to maintain a high heat transmission coefficient, and extremely excellent heat transfer performance can be obtained.

Further, by arranging a plurality of double tubes 1 in multiple stages in the vertical direction and winding them in a coil shape, the inclination angle of each double tube 1 can be further increased.
A high circulation ratio can be obtained only by natural circulation (2 or more). Therefore, the temperature in the pipe is made uniform, and the amount of self-evaporation increases with rapid load fluctuation. In addition, local corrosion and local concentration are also suppressed in water treatment in a pipe such as anticorrosion and scale adhesion.

The double pipe 1 of the present invention comprises an inner pipe 3 inside an outer pipe 2.
After being inserted and fixed, it is wound around a cylindrical mold to form a coil, so that the number of processing steps can be greatly reduced as compared with the conventional shell and tube type. Further, the weight can be reduced even in terms of weight. Further, the steam generator of the present invention has a small amount of water and a high safety, and is applicable to a high-temperature and high-pressure steam generator.

FIG. 4 shows another embodiment of the double tube 1 according to the present invention, in which the coil diameter is gradually increased from one end to the other end, and is formed in a tapered shape. This shape can be formed by making the mold around which the double pipe 1 is wound into a tapered shape, but has an advantage that the mold and the double pipe 1 can be easily separated. In the illustrated embodiment, the coil diameter is formed so as to gradually increase from the top to the bottom. Conversely, the coil diameter may be formed to gradually increase from the bottom to the top. The taper angle θ is set to about 5 to 60 °.

[0027]

As described above, according to the present invention, a double pipe having an inner pipe inserted concentrically inside an outer pipe is wound up in a coil shape and erected to form a flow passage between the outer pipe and the inner pipe. The heating fluid is allowed to flow downward from above, and the fluid to be heated is allowed to flow upward from below in the inner tube.The cross section of one or both of the outer tube and the inner tube is approximately By making the shape elliptical, the heat transfer performance can be significantly improved. Also at the time of manufacturing, the number of processing steps can be significantly reduced as compared with the conventional one.

By arranging a plurality of double pipes in multiple stages in the vertical direction and winding them in a coil shape, the inclination angle of each double pipe can be made larger, and high with only natural circulation. A circulation ratio can be obtained. By forming the coil shape such that the coil diameter is gradually increased from one end to the other end and is formed in a tapered shape, the mold and the double tube can be easily separated at the time of molding. By installing the separator in the central space of the coil shape, the overall configuration can be made compact and space can be saved.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a plan view of FIG. 2 (line configuration omitted);

FIG. 3 is an enlarged sectional view of a double pipe according to the present invention.

FIG. 4 is a front view showing another embodiment of the double pipe according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double pipe 2 Outer pipe 3 Inner pipe 4 Flow passage 5 Separator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-44901 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F22B 21/28 F22B 1/08 F22B 1 / 16

Claims (5)

(57) [Claims] 1. A double tube 1 in which an inner tube 3 is concentrically inserted into an outer tube 2 is wound up in a coil shape and erected, and a flow passage 4 between the outer tube 2 and the inner tube 3 is provided. A double-tube coil-type steam generator characterized in that a heating fluid is caused to flow downward from above and a fluid to be heated is caused to flow inside the inner pipe 3 from below to above. 2. A double tube 1 in which an inner tube 3 is inserted concentrically inside an outer tube 2 is wound up in a coil shape and erected, and one or both of the outer tube 2 and the inner tube 3 are provided. Has a substantially elliptical cross section, and its major axis direction is set in a vertical direction. A heating fluid is supplied to the flow passage 4 between the outer pipe 2 and the inner pipe 3, and a heated fluid is supplied to the inner pipe 3. A double-tube coil-type steam generator characterized by being distributed. 3. A plurality of double pipes 1 in which an inner pipe 3 is concentrically inserted into an outer pipe 2, and the plurality of double pipes 1 are arranged in multiple stages in a vertical direction and wound in a coil shape. A double-tube coil-type steam generator, wherein a heating fluid flows through a flow passage 4 between the outer pipe 2 and the inner pipe 3, and a fluid to be heated flows through the inner pipe 3. 4. A double tube 1 in which an inner tube 3 is concentrically inserted into an outer tube 2 is wound in a coil shape and erected, and the coil diameter of the coil shape is gradually increased from one end to the other end. A double-tube coil type wherein the heating fluid flows through the flow passage 4 between the outer tube 2 and the inner tube 3 and the fluid to be heated flows through the inner tube 3. Steam generator. 5. A double tube 1 in which an inner tube 3 is concentrically inserted into an outer tube 2 is wound in a coil shape and erected, and a separator 5 is installed in a center space of the coil shape. The downstream end of the pipe 3 is communicated with the separator 5, and the heating fluid is supplied to the flow passage 4 between the outer pipe 2 and the inner pipe 3 by the inner pipe 3.
A double-tube coil-type steam generator characterized in that a fluid to be heated is circulated inside the steam generator.