JP4602940B2 - Induction heating steam generator - Google Patents

Description

  The present invention relates to an induction heating type steam generator that generates steam by heating water with a heating element that generates heat by induction heating.

  As an induction heating type steam generating apparatus in which water is generated by a heating element that generates heat by induction heating and steam is generated, the one disclosed in Patent Document 1 is already known. The configuration of the once-through steam generator disclosed in Patent Document 1 is shown in FIGS. 7 is a longitudinal sectional view, and FIG. 8 is a plan sectional view taken along line VIII-VIII in FIG.

  As is apparent from FIGS. 7 and 8, the conventional induction heating steam generator includes a plurality of heating elements 13 each consisting of a small number of spheres or cylindrical magnetic conductive materials each having a size of several centimeters at most. A conductor having a cooling water flow passage 22 around a heating vessel 1 constituted by housing a heating tube 15 constituted by a thin tube of non-magnetic and non-conductive heat-resistant material such as ceramic or heat-resistant glass in a heat-resistant protective vessel 10. The configured heating coil 2 is disposed, and a plurality of annular rings electrically closed at the upper and lower end portions and the intermediate outer peripheral portion of the heating coil 2 in order to prevent leakage of magnetic flux generated by the heating coil 2. A shield coil 3 composed of conductors 31 to 34 is installed. Each conductor of this shield coil 3 is electrically closed and is composed of an annular conductor having a vapor flow passage inside. The steam flow passages of the annular conductors are sequentially connected in series by a connecting pipe 35. The gap between the heat-resistant container 10 and the heating tube 15 is filled with a heat insulating material 10a so as to reduce heat radiation from the heating container 1 to the outside.

  The water supply pipe 41 is connected to the inlet pipe 25 of the cooling water passage 22 of the lowermost coil conductor 21 of the heating coil 2, and the outlet pipe 26 of the cooling water flow passage 22 of the uppermost coil conductor 21 is connected to the lower part by the connection pipe 42. It connects with the cover body 17 which comprises a water supply header part. The steam extraction pipe 14 drawn out from the lid body 16 constituting the upper steam header section is connected to the steam-water drum 5 installed outside the heating container 1.

  The water supply pipe 51 is drawn out from the air / water drum 5, connected to the connection pipe 42 connected to the lower lid 17, and water is supplied from the drum 5 to the water supply header portion of the heating container 1. The amount of water in the heating container 1 is adjusted so as to always maintain a predetermined water level L so that the heating body 13 is not exposed from the water. Further, the steam pipe 52 drawn from the steam drum 5 is connected to the inlet pipe 3d of the steam flow passage of the uppermost annular conductor 31 of the shield coil 3, and connected to the outlet pipe 3c of the steam flow passage of the lowermost annular conductor 34. The superheated steam supply pipe 62 is connected. The superheated steam supply pipe 62 is extended to a place where a load that requires steam is installed, and supplies steam S ′ to the load.

  In order to generate steam, high-frequency AC power of about 10 to 30 kHz is supplied to the heating coil 2 from a high-frequency AC power supply device (not shown). Then, water W is supplied from a water source such as a water storage tank 41 to the inlet pipe 25 of the cooling water flow passage 22 formed inside the conductor 21 of the heating coil 2 through the water supply pipe 41. This water flows through the cooling water flow passage 22 of the heating coil 2 and is injected from the outlet pipe 26 through the connection pipe 42 to the water supply header formed by the lid 17 at the lower part of the heating container 1.

  When high-frequency power is supplied to the heating coil 2, Joule heat is generated by the current and resistance flowing in the coil conductor 21, and each heating tube 15 in the heating container 1 is filled by the high-frequency magnetic field generated by the induction heating coil 2. Eddy currents are respectively generated in the heating bodies 13 made of small pieces of the magnetic conductive material, and Joule heat is generated by the currents. The water W supplied to the heating container 1 is preheated by cooling the coil conductor 21 in the process of flowing through the cooling water flow passage in the heating coil 2 and supplied to the water supply header portion of the heating container 1 as hot water. Is done. The water supplied to the heating pipe 15 from here comes into contact with the heating body 13 composed of a number of pieces of magnetic conductive material filled therein in each heating pipe, and is heated by the heat generated by the heating body to be steam S. As a result, the inside of the heating pipe is raised and gathered in the steam header portion formed by the lid 16 at the top of the heating container 1.

  The steam in the upper steam header portion of the heating container 1 is sent to the steam drum 5 through the steam take-out pipe 14. Since the steam sent to the steam-water drum 5 is wet steam containing moisture, the steam and moisture (condensed liquid component) are separated in the steam-water drum 5 and stored in the drum 5. Then, the steam from which moisture has been removed is guided to the inlet pipe 3d of the steam flow path of the annular conductor 31 at the upper end of the shield coil through the steam pipe 52, and flows through the steam flow paths of the four annular conductors (31 to 34). Then flows to the superheated steam supply pipe 62 connected to the outlet pipe 3c of the annular conductor 34 at the lower end.

The shield coil 3 cancels out the magnetic flux leaking to the outside of the heating coil 2 by the magnetic flux generated by the circulating current generated by the magnetic flux generated by the heating coil 2 in each annular conductor, and suppresses the leakage of the magnetic flux to the outside. To work. The circulating current flowing in each annular conductor naturally generates Joule heat due to the resistance of the conductor itself, but the steam S is reheated in the process of flowing through the steam flow passage in the shield coil 3 and the superheated steam S ′. It becomes. The superheated steam S ′ generated in this way is carried to the installation site of the load that uses the steam by the superheated steam supply pipe 62.
JP 2006-064358 A

  In such a conventional apparatus, a heating container composed of small pieces of conductive material is filled in a heating container composed of a non-magnetic and non-conductive heat-resistant material, and the heating element is heated by electromagnetic induction, Since the water passed through is heated by the heat of the heating element to generate steam, the steam can be generated relatively efficiently.

By the way, the current i flowing by electromagnetic induction in the heating body 13 made of a columnar piece of conductive material placed in a high-frequency magnetic field flows in a direction perpendicular to the applied magnetic flux. In particular, as shown in FIG. 4B, when the axial direction of the heating element 13 is inclined with respect to the magnetic flux Φ, both ends of the magnetic field in the magnetic field of the heating element, in particular, the corners at both ends. There is a property that the current i flows more concentrated in the part. For this reason, the corner | angular part of the heating body 13 becomes a high temperature point where temperature is abnormally high.
Also, in the case of a heating body composed of spherical small pieces, as shown in FIG. 4 (c), the current i concentrates and flows near the center of the spherical heating body 13, so that the vicinity of the center is a hot spot. Become.
This phenomenon is the same even when the length of the heating body is increased. However, as shown in FIG. 4A, in the case of the elongated heating body 13a, since the length is long, the heating body covers almost the entire length. The current i flows in a relatively uniform manner, and the temperature distribution of the heating element 13a is made uniform compared to the small heating element.

  In the conventional apparatus, since the heating body consisting of small pieces of short length was filled in the heating container or the heating tube, the posture of the heating body could not be kept constant, and the high temperature point at the corner A large number of heating bodies come into contact with the inner wall of the heating container or heating tube.

  When such a hot spot at the corner of the heating element contacts the inner wall of the heating vessel or the heating tube, the temperature of the heating vessel or the heating tube is locally increased in this portion, and the temperature distribution on the vessel wall is not good. It becomes uniform and a large thermal stress strain is generated on the container wall of the heating container, and in the worst case, there is a risk that the heating container or the heating tube constituted by the heat-resistant material is broken.

  In order to eliminate such a risk, the present invention prevents the hot spots at the corners of the heating body contained in the heating container or the heating pipe of the steam generator from coming into contact with the inner wall of the heating container and the heating pipe. It is an object of the present invention to provide an induction heating steam generator configured.

In order to solve such problems, the present invention inserts a heating body made of a conductive material into a non-magnetic and non-conductive cylindrical heat-resistant container through which water flows, and the outer periphery of the heating container An induction heating type steam generator that inductively heats the heating body by a high frequency magnetic field applied by a heating coil provided in the heating coil and heats the water in the heating container by the induction heating body to generate steam. A plurality of heat-resistant non-magnetic and non-conductive heating tubes are accommodated in the heating container, and the heating body is formed of an elongated rod-shaped conductive material, and the heating body is placed in each heating tube. , the axial direction in the same direction as the direction of the magnetic flux of the high-frequency magnetic field, at a gap which becomes water passage between and between each other and the heating pipe inserted disposed a plurality dispersion, and the heating tube The heating element inside has a lower end at the lower end of the heating tube. The positional relationship is fixed and held by fixing the bonded mounting plate, it is characterized in that it has to be connected and fixed to each other by coupling by mutually connecting plate upper end.

In the present invention, it is important that the heating body is separated from the inner wall of the heating tube by 1 mm or more so that the heating body and the heating tube do not come into contact with each other. Then, a plurality of grooves extending in the axial direction are uniformly distributed on the outer peripheral surface of the heating body, the cross section is made uneven, and the depth of the grooves is set to a depth greater than the penetration depth of the high-frequency magnetic field. it can.

  According to the present invention, a heating body made of a conductive material is inserted into a heat-resistant non-magnetic and non-conductive cylindrical heating container through which water flows, and the heating body is connected to the outer periphery of the heating container. In an induction heating type steam generator in which water is heated by induction heating with a high frequency magnetic field applied from the heating vessel and water in the heating container is heated by the heated heating body, the heating body is formed into an elongated rod-shaped conductive material. The rod-shaped heating body is inserted into the heating container in such a manner that the axial direction of the heating body is the same as the direction of the magnetic flux of the high-frequency magnetic field. The temperature distribution of the heating element to be stored is made more uniform than that of the conventional heating element with a small piece, the generation of a high temperature point is eliminated, and the heating container is not locally heated by the heating element. The temperature distribution of the container wall is Manner homogenized by strain local thermal stress of the container wall of the heating vessel by is reduced, risk of breakage is reduced.

  In this case, if the heating body is separated from the inner wall of the heating container by 1 mm or more so that the heating body does not contact the inner wall of the heating container, the container wall of the heating container can be almost completely prevented from being heated locally. The risk of breakage due to the thermal stress of the container can be almost completely avoided.

  And, by providing a plurality of axially extending grooves on the outer peripheral surface of the rod-shaped heating body, the surface of the heating body becomes uneven, and the peripheral length of the outer peripheral surface of the heating body can be lengthened. Since the resistance value of the flowing path can be increased, the amount of heat generated by the heating element can be increased. And since the surface area of a heating body can be expanded by making the surface uneven | corrugated shape, there also exists an effect which can improve the heat transfer from the heating body to the water heated.

  Embodiments of the present invention will be described based on examples shown in the drawings.

  1 and 2 show an induction heating type steam generator according to an embodiment of the present invention. 1 is a longitudinal sectional view thereof, and FIG. 2 is a plan sectional view taken along line II-II of FIG. FIG. 1 shows a longitudinal section cut in the longitudinal direction not at the center of the apparatus but at the position of the line II in FIG.

The main configuration of the embodiment of the present invention shown in FIGS. 1 and 2 is the same as that of the conventional device shown in FIGS. 7 and 8. Therefore, the same components as those of the conventional device are denoted by the same reference numerals, Detailed description is omitted.
In this embodiment, the difference from the above-described conventional apparatus is that the heating tube 15 made of a non-magnetic and non-conductive heat-resistant glass tube or ceramic tube or the like housed in the heat-resistant vessel 10 constituting the main body portion of the heating vessel. The heating body 13a accommodated in the inside is not composed of a small piece of magnetic conductive material, but is composed of an elongated rod-shaped magnetic conductive material.

  In each heating tube 15, a plurality of elongated rod-shaped heating bodies 13 a are dispersedly inserted with a gap of 1 mm or more so as not to contact the inner wall of the heating tube 15. The heating element 13a is inserted into the heating tube 15 in parallel with the direction of the magnetic flux of the high frequency magnetic field to which the axial direction is applied. Each heating body 13 a has an upper end that extends substantially to the same height as the upper end of the heating coil 2. Thereby, a linear gap running in the axial direction of the heating tube 15 is formed between the heating tube and the plurality of rod-shaped heating bodies 13a inserted therein and between the heating bodies in each heating tube 15, It becomes the water flow passage 15e.

As is clear from FIG. 3 (a) showing a part of the heating body 13a and the heating tube 15 in an enlarged manner, the lower end of each heating body 13a is fixed to the heating tube 15 in order to keep the positional relationship fixed. The fixing plate 15a connected to the lower end is fixed by fixing means such as a screw 15c. A large number of through-holes 15d are provided in the mounting plate 15a in order to communicate the water flow passage 15e in the heating tube 15 with the steam and water header portions formed by the upper and lower lids 16 and 17 of the heating container 1, respectively. Is provided.
As shown in FIG. 3B, the upper ends of the heating elements 15a are connected to each other by screwing to the connecting plate 15b.

  The steam generating apparatus of the present invention configured as described above generates steam as follows in the same manner as the conventional apparatus.

First, high frequency AC power of about 10 to 30 kHz is supplied to the heating coil 2 from a high frequency AC power supply device (not shown). Then, water W is supplied from a water source such as a water storage tank 41 to the inlet 25 of the cooling water flow passage 22 formed in the conductor 21 of the heating coil 2 through the water supply pipe 41. This water flows through the cooling water flow passage 22 of the heating coil 2 and is injected from the outlet 26 into the heating pipe 15 through the connection pipe 42 from the water supply header portion formed by the lid 17 at the lower part of the heating container 1. The amount of water in the heating tube 15 is kept at a substantially constant amount below the upper end of the heating body 13a so that the water splashed in consideration of splashing due to boiling of the water wets the entire heating body 13a. . In addition, although the height direction of the whole apparatus becomes large, you may make it keep the water quantity in the heating pipe | tube 15 to the substantially constant quantity which the whole heating body 13a immerses.
When high frequency power is supplied to the heating coil 2, Joule heat is generated by the current and resistance flowing through the coil conductor 21, and is inserted into each heating tube 15 in the heating container 1 by the high frequency magnetic field generated by the induction heating coil 2. Eddy currents are respectively generated in the thin bar-shaped magnetic conductive material heating bodies 13a, and Joule heat is generated by the currents. The water W supplied to the heating container 1 is preheated by cooling the coil conductor 21 in the process of flowing through the cooling water flow passage in the heating coil 2 and supplied to the water supply header portion of the heating container 1 as hot water. Is done. The water supplied from here to the heating tube 15 comes into contact with the heating body 13a made of a large number of elongated rod-like magnetic conductive materials in the process of flowing through the flow passage 15e formed in the gap between the heating bodies 13a. It is heated by the heat generated by the heating body, becomes steam S, rises in the heating tube, and collects in the steam header portion formed by the lid body 16 at the top of the heating container 1.

  The steam in the upper steam header portion of the heating container 1 is sent to the steam-water drum 5 through the steam take-out pipe 14, and moisture (condensed liquid) is separated from the wet steam containing moisture in the steam-water drum 5. Stored within. The steam from which moisture has been removed is guided to the inlet pipe 3d of the steam flow passage of the annular conductor 31 at the upper end of the shield coil 3 through the steam pipe 52, and is connected to the four annular conductors (31 to 34) via the connection pipe 35. The steam flow passage flows in series to the superheated steam supply pipe 62 connected to the outlet pipe 3c of the annular conductor 34 at the lower end.

  The shield coil 3 cancels out the magnetic flux leaking to the outside of the heating coil 2 by the magnetic flux generated by the circulating current generated by the magnetic flux generated by the heating coil 2 in each annular conductor, and suppresses the leakage of the magnetic flux to the outside. To work. The circulating current flowing in each annular conductor naturally generates Joule heat due to the resistance of the conductor itself, but the steam S is reheated in the process of flowing through the steam flow passage in the shield coil 3 by this heat, and the superheated steam S ′. It becomes. The superheated steam S ′ generated in this way is transported to the installation location of the load that uses the steam by the superheated steam supply pipe 62.

In the present invention, since the heating body 13a housed in the heating tube 15 is formed of an elongated rod-like magnetic conductive material, the heating body 13a is indicated by an arrow i in FIG. Such an induced current is generated. The current i flowing through the heating element 13a is accompanied by a phenomenon of concentrating at the corners at the upper and lower ends. However, since the length is long, the current flowing through the intermediate part of the heating element 13a is distributed almost evenly, and therefore concentrated. The current is reduced. For this reason, generation | occurrence | production of the abnormally high high temperature point is suppressed for each heating body 13a in the heating tube 15. FIG.
According to the heating experiment conducted by the inventors, it has been confirmed that the temperature at the high temperature point of the heating element 13 made of a conventional columnar piece is a high temperature of 340 ° C. or higher. In the case of the rod-shaped heating body 13a, there is no such high temperature portion, and the temperature of the entire heating body is distributed fairly uniformly.

  In this invention, in order to prevent the elongated rod-shaped heating body 13a from contacting the inner wall of the heating tube 15, it is inserted with a gap of 1 mm or more. When the heating body 13a is inserted into the heating pipe 15 at such an interval, even if an abnormal high temperature point occurs in the heating body 13a, the flow passage 15e formed between the heating body 13a and the heating pipe 15 is used. The heat of the heating body 13a is transmitted to the heating tube 15 through the water flowing through the inside. For this reason, since the tube wall of the heating tube 15 does not become a temperature higher than the temperature of the water heated therein, it does not become a remarkably high temperature locally. The temperature is equal. Therefore, there is almost no thermal stress strain applied to the heating tube, and there is no risk of the heating tube being damaged during operation, and the safety of the apparatus is improved.

  Further, in the present invention, in order to increase the effective electrical resistance of the heating body 13a to increase the heat generation amount and to increase the heat transfer efficiency from the heating body to the water to be heated to increase the heating efficiency, FIG. As shown, the groove 13g running in the axial direction is provided on the outer periphery of the heating body 13a so as to be evenly distributed in a plurality of circumferential directions, and the outer peripheral surface of the heating body 13a can be made uneven. In this case, the heating body 13a is preferably made of a magnetic conductive material.

  When a high-frequency magnetic field in which the magnetic flux direction is the same as the axial direction of the conductor is applied to the rod-shaped conductor, the current flowing through the conductor due to the skin effect flows near the surface of the conductor. This phenomenon becomes more prominent when the conductor has magnetism. For example, when a 20 kHz high frequency magnetic field is applied to a magnetic stainless steel bar having a relative permeability of 500 and a resistivity of 60e-8 Ωm, the current i flowing to the bar extends from the surface of the bar to a depth of 0.12 mm. Flowing. For this reason, when the depth of the groove 13g provided on the outer periphery of the heating body 13a is 0.12 mm or more, the current flowing near the surface of the heating body 13 as shown by the dotted arrow in FIG. Since the path is bent in a zigzag shape by the groove, the distance through which the current flows becomes long and the substantial resistance increases, so that the heat generation amount of the heating element can be increased. That is, the heat generation amount can be increased by setting the depth of the groove 13g of the heating element 13a to a depth not less than the penetration depth determined by at least the frequency of the applied high-frequency magnetic field and the physical properties of the bar. . The cross-sectional shape of the groove may be a triangle or a quadrangle, and the resistance value can be changed by appropriately selecting the shape and depth of the groove, so that the degree of freedom in design increases.

  At the same time, by using a rod-shaped heating element 13a having a groove on the outer periphery and having an uneven outer peripheral surface, the contact area between the heating element and water heated thereby increases, Since heat transfer is enhanced, the heating efficiency of water in the steam generator can be improved by using the heating body 13a provided with a number of grooves 13g on the outer periphery.

It is a longitudinal cross-sectional view which shows the structure of the induction heating type steam generator of the Example of this invention. FIG. 2 is a plan sectional view taken along line II-II in FIG. 1. (A) is the fragmentary sectional view which expands and shows the joint part of the lower end of the heating body in the Example of this invention, (b) is a fragmentary perspective view which expands and shows the joint part of the upper end of a heating body. It is an operation explanatory view of this invention, (a) is a current distribution figure of a heating object in this invention, and (b) is a current distribution figure of a heating object in a conventional device. (A) is a top view which shows the heating body used for this invention, (b) is a perspective view which shows the heating body used for this invention. It is operation | movement explanatory drawing of this invention. It is a longitudinal cross-sectional view which shows the structure of the conventional induction heating type steam generator. It is a plane sectional view of a VIII-VIII line in FIG.

1: heating container, 13a: heating element, 13g: groove, 15: heating tube, 2: heating coil, 3
: Shield coil, W: water, S: steam, S ': superheated steam.

Claims (3)

A heating body made of a conductive material is inserted into a non-magnetic and non-conductive cylindrical heat-resistant container through which water flows, and the heating is performed by a high-frequency magnetic field applied by a heating coil provided on the outer periphery of the heating container. In an induction heating steam generator that heats the body and heats the water in the heating container with the induction heating body to generate steam , the heat-resistant non-magnetic material in the heating container. A plurality of non-conductive heating tubes are accommodated, and the heating body is formed of an elongated rod-shaped conductive material. The heating body is arranged in each of the heating tubes, the axial direction of which is the direction of the magnetic flux of the high-frequency magnetic field. in the same direction, at a gap which becomes water passage between and between each other and the heating pipe inserted disposed a plurality dispersion, and heating element in the heating tube, the lower end each of the heating tubes By adhering to the mounting plate connected to the lower end, Fixed holding the location relationship, induction heating steam generator being characterized in that so as to be fixedly connected to each other by coupling by mutually connecting plate upper end. Wherein the inserted the heating body to heat pipe away from the vessel wall of the heating tube 1mm or more, the induction heating according to claim 1, characterized in that the heating body is prevented from contacting the vessel wall of the heating tube Steam generator. A plurality of strips extending in the axial direction are provided on the outer peripheral surface of the heating body in a distributed manner so that the cross section of the heating body is uneven, and the depth of the strips is greater than the penetration depth of the high-frequency magnetic field. The induction heating steam generator according to claim 1 or 2,

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