JP2015015081A - Heating device for corrosive liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device which is compact, capable of raising the temperature of a liquid in a short time and further capable of heating a corrosive liquid continuously supplied at a fixed flow rate to a fixed temperature.SOLUTION: The heating device configured to heat a corrosive liquid comprises a heater unit 1 and a heat insulation member 2 surrounding the heater unit 1 and including an inlet 21 and an outlet 22 for the liquid. The heater unit 1 includes: ceramic plates 12 and 13 formed from a compound material containing C or SiC and a heating element 11 for heating air-tightly provided inside. A channel 23 is provided which communicates to the inlet 21 and the outlet 22 and at least once spirally turns around the heater unit 1.

Description

  The present invention relates to a heating device for heating a corrosive liquid.

  An operation in which a corrosive liquid is heated to a predetermined temperature and then used is performed in various chemical processes. For example, an alkaline corrosive liquid such as an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution, or an acidic corrosive liquid such as sulfuric acid, hydrochloric acid, or phosphoric acid is heated and then added to the reactant to increase the reaction rate. Things have been done. Moreover, in the pretreatment process and the etching process of metal plating, the treatment speed is increased by heating the chemicals to be used in advance.

  As a heating device for such a corrosive liquid, for example, as shown in Patent Document 1, a heater is wound around a pipe made of a corrosion-resistant member such as a fluororesin tube or quartz to warm the liquid flowing in the pipe. Is used. Alternatively, as shown in Patent Document 2, a heater is arranged around a liquid container having excellent corrosion resistance to heat the entire container, thereby heating the liquid in the container, or as shown in Patent Document 3, a liquid container A device is used in which a heater is placed inside the container to heat the liquid in the container.

Japanese Patent No. 3911723 Japanese Patent Laid-Open No. 06-098828 JP 2005-005075 A

  However, since the technique of Patent Document 1 uses a material having low thermal conductivity such as fluororesin as a piping material, the outer diameter of the piping in contact with the heating unit is increased or the piping is made to compensate for this. It is necessary to increase the length, and there is a problem that the size of the heating device becomes too large compared to the flow rate flowing in the pipe. Further, in the techniques of Patent Documents 2 and 3, since the liquid to be heated is received in a container having a predetermined capacity and heated in a batch system, the amount that can be heated at one time is limited and has a certain temperature. It was not suitable for continuous production of hot liquids. It is also difficult to keep the temperature of the liquid in the container uniform.

  The present invention has been made in view of such a conventional problem, and is more compact than a conventional heating device, can raise the temperature of a liquid in a short time, and is continuously supplied at a constant flow rate. It aims at providing the heating apparatus which can heat a corrosive liquid to fixed temperature.

  In order to achieve the above object, a heating device provided by the present invention is a heating device that heats a corrosive liquid, and includes a heater unit, a heat insulating member that surrounds the heater unit and includes an inlet and an outlet for the liquid. The heater unit includes a ceramic body made of SiC or a composite material containing SiC, and a heating heating element provided in an airtight manner therein, and communicates with the inlet and the outlet, and the heater unit It is characterized in that a flow path that spirally spirals around is provided.

  According to the present invention, the liquid can be heated in a short time in a compact manner, and the corrosive liquid continuously supplied at a constant flow rate can be heated to a constant temperature.

It is a typical perspective view of the heating apparatus of embodiment of this invention. It is a longitudinal cross-sectional view of one specific example of the heater unit included in the heating apparatus of the present invention. It is a front view of one specific example of the heating device of the present invention. It is a longitudinal cross-sectional view of the heating apparatus of FIG. It is an arrow line view when the heating apparatus of FIG. 3 is cut | disconnected by VV. It is an arrow line view when the heating apparatus of FIG. 3 is cut | disconnected by VI-VI. It is sectional drawing which shows the specific example of the flow path provided in the heating apparatus of this invention. It is a longitudinal cross-sectional view of the other specific example of the heating apparatus of this invention.

  First, embodiments of the present invention will be listed and described. The heating device of the present invention is a heating device that heats a corrosive liquid, and includes a heater unit and a heat insulating member that surrounds the heater unit and includes an inlet and an outlet for the liquid. A ceramic body made of SiC or a composite material containing SiC, and a heating heating element provided in an airtight manner therein, communicated with the inlet and the outlet and spirally around the heater unit at least once. A swirling flow path is provided. With this configuration, the heating device itself can be made compact and the temperature of the liquid can be raised in a short time, and the corrosive liquid continuously supplied at a constant flow rate can be heated to a constant temperature.

  In the heating device of the present invention, it is preferable that the channel groove is formed on the side of the heat insulating member that contacts the ceramic plate. Thereby, a flow path can be formed easily and at low cost. Moreover, an auxiliary heat insulating member may be provided around the heat insulating member, and a gap may be provided between the heat insulating member and the auxiliary heat insulating member. Thereby, it becomes possible to obtain higher heat insulation performance.

  Next, a specific example of the heating apparatus for corrosive liquid according to the present invention will be described with reference to FIG. The heating apparatus shown in FIG. 1 is a heating apparatus that receives and heats corrosive liquid continuously supplied at a constant flow rate into the apparatus, and heats the heater unit 1 that is heated in contact with the corrosive liquid. The heat insulating member 2 surrounds the entire surface of the heater unit 1. As shown in FIG. 2, the heater unit 1 includes a heating element 11 and ceramic plates 12 and 13 formed in two plates sandwiching the heating element 11, and the heating element 11 is flexible. The airtight member 14 is hermetically sealed.

  The elements constituting the heating device will be described more specifically. The heating element 11 included in the heater unit 1 is not particularly limited in shape or structure, but a metal sheath heater is used. Alternatively, it is preferable to use a metal resistance heating element covered with an electrical insulator sheet. This is because these are simple and easy to handle. In the case of a metal sheath heater, a heating element such as nichrome wire is inserted into a metal sheath such as stainless steel, and a high-purity powder of an inorganic insulator having good thermal conductivity such as magnesium oxide is compactly filled in the gap. Is preferred.

  On the other hand, in the case of a metal resistance heating element coated with an electrical insulator sheet, nickel, stainless steel, silver, tungsten, molybdenum, chromium, or an alloy of at least one of these metals is used as the material of the metal resistance heating element. Is preferred. Of these, stainless steel and nichrome are preferred. This is because, for example, stainless steel or nichrome can form a resistor circuit pattern with relatively high accuracy by performing processing such as etching on a metal foil. In addition, stainless steel and nichrome are preferable in that they are inexpensive and have oxidation resistance, so that they can withstand long-term use even at high operating temperatures.

  The material of the electrical insulator sheet that covers the above-described metal resistance heating element is preferably one having heat resistance in addition to electrical insulation, such as mica, polyimide, silicone resin, epoxy resin, phenol resin. And so on. Among these, when a resin is used, a filler may be dispersed in the resin so that heat generated by the metal resistance heating element made of the metal foil can be transferred to the ceramic plate more smoothly. This is because the thermal conductivity of the silicone resin or the like can be increased by dispersing the filler in the resin. The filler material is not particularly limited as long as there is no reactivity with the resin. For example, a material such as boron nitride, aluminum nitride, alumina, or silica can be used.

  The ceramic plates 12 and 13 sandwiching the heating element 11 are made of SiC or a composite material such as SiSiC containing SiC in order to provide corrosion resistance against corrosive liquids, and the shape is not particularly limited. From the viewpoint of cost and ease of manufacture, it is desirable that the plate is composed of two substantially identically shaped flat plates as shown in FIG. In one or both of these two flat plates, a recess 15 having a size capable of accommodating the heating element 11 for heating described above is provided on the surfaces facing each other.

  One or both of these two flat plates are further provided with an annular groove 16 so as to surround the entire circumference of the recess 15, where O is thicker or thicker than the depth of the groove 16. A flexible airtight member 14 such as a ring or gasket is fitted. The two ceramic plates 12 and 13 are overlapped so as to sandwich the heating heating element 11 and the airtight member 14 mounted, and these two ceramic plates 12 and 13 are coupled with a fastening member such as a screw (not shown). Thus, the heater unit 1 is obtained.

  Since the flexible airtight member 14 surrounding the heating element 11 is compressed by the ceramic plates 12 and 13 due to the coupling by the fastening member, the heating element 11 is externally corrosive environment. Is hermetically sealed. Since the airtight member 14 is in contact with the corrosive liquid, the material used is, for example, Viton (registered trademark), Kalrez (registered trademark), or other fluorine resin such as PTFE or PFA.

  As shown in FIGS. 3 to 6, the heat insulating member 2 is provided so as to surround the entire surface of the heater unit 1 described above. The shape of the heat insulating member 2 is not particularly limited, but is preferably a similar shape as if the heater unit 1 is made one size larger. Thereby, a compact heating device can be realized as a whole. A liquid inlet 21 through which liquid is supplied to both ends of the heat insulating member 2 and a liquid outlet 22 through which heated liquid is discharged are provided.

  A liquid flow path 23 communicating with the inlet 21 and the outlet 22 is formed between the heater unit 1 and the heat insulating member 2. Specifically, the inner wall of the flow path 23 is defined by the surface of the heater unit 1 and the surface of the heat insulating member 2 facing the heater unit 1 so that the channel 23 can be heated while in contact with the corrosive liquid. The flow path 23 spirals around the surface of the heater unit 1 at least once. Thereby, the heat of the heater unit 1 can be efficiently transferred to the fluid. FIG. 1 schematically shows a state in which the fluid is spirally swirled around the heater unit 1 in the longitudinal direction of the heater unit 1 with arrows, and FIGS. A flow path formed so as to swirl around the unit 1 four times spirally in the longitudinal direction is shown.

  The flow path 23 between the heater unit 1 and the heat insulating member 2 may be formed by providing a groove on the surface of the heater unit 1 as shown in FIG. 7 (a), or as shown in FIG. 7 (b). In this way, it may be formed by providing a groove on the inner surface of the heat insulating member 2. Or you may form by providing a groove | channel in both as shown in FIG.7 (c). Since resin has better processability and costs are considerably reduced compared to ceramics, when using a heat insulating member 2 made of resin, it contacts the ceramic plate 1 in the heat insulating member 2 as shown in FIG. It is preferable to provide a groove only on the inner surface side.

The material of the heat insulating member 2 provided with the fluid inlet 21 and the outlet 22 is not particularly limited as long as it has corrosion resistance. However, SiSiC, SiC, Si ₃ N ₄ , ceramics such as quartz, PTFE, A fluororesin such as PFA is preferred. Of these, fluororesins are more preferred because they have good processability, are easy to weld, and are corrosion resistant to most chemicals. The heat insulating members 2 are preferably integrally molded or welded together with the same material in order to ensure hermeticity, and also in this respect, a fluororesin is preferable. In the case of ceramics that are difficult to weld, it is preferable that the connection is made so that liquid does not leak outside by airtight sealing with an airtight member such as an O-ring. In this case, the material of the hermetic member is not particularly limited as long as it has corrosion resistance. In addition to Viton (registered trademark) and Kalrez (registered trademark), fluorine resins such as PTFE and PFA can be used.

  As thickness of the heat insulation member 2, 2 mm or more is preferable from a viewpoint of favorable heat insulation, 5 mm or more is more preferable, and 10 mm or more is the most preferable. By increasing the thickness of the heat insulating member in this manner, the outer surface temperature of the heating device can be kept low, energy can be saved, and the influence of the heating device on the surrounding environment can be minimized. However, if it is too thick, the device itself may be too bulky or heavy, and handling may be difficult.

  When the thickness of the heat insulating member 2 cannot be increased due to such a restriction, an auxiliary heat insulating member 3 is provided around the heat insulating member 2 and a gap is formed between the heat insulating member 2 and the auxiliary heat insulating member 3 as shown in FIG. 31 may be provided. The auxiliary heat insulating member 3 can be supported by providing a columnar support member 32 between the heat insulating member 2 and the auxiliary heat insulating member 3 at an appropriate location. There are no particular restrictions on the optimal thickness distribution and spacing of the heat insulating member 2 and auxiliary heat insulating member 3, but the thickness of the heat insulating member 2 is about 2 to 5 mm and the space 31 is about 3 to 15 mm. If the thickness of 3 is about 2 to 5 mm, the entire apparatus can be made compact and lightweight, which is preferable.

  As mentioned above, although the specific example was given and demonstrated about the heater of this invention, this invention is not limited to the specific example which concerns, It can implement in the various aspects of the range which does not deviate from the main point of this invention. That is, the technical scope of the present invention extends to the claims and their equivalents.

[Example 1]
An experiment for heating a fluid by manufacturing a heating apparatus as shown in FIGS. Specifically, two ceramic plates made of Si ₁₀ SiC _{90 having} a rectangular plate shape of 150 mm long × 50 mm wide × 10 mm thick were prepared. A concave portion having a length of 100 mm, a width of 30 mm, and a depth of 1.05 mm for storing a heating element to be described later is provided at a substantially central portion on one side of one of these two ceramic plates, and further encloses the periphery of the recess. As described above, a groove having a width of 2.4 mm and a depth of 1.8 mm for fitting an airtight member to be described later was formed. The inner dimensions of this groove were 105 mm long x 35 mm wide. The other of the two ceramic plates was provided with a through hole for passing a power supply cable for the heating element.

  Two sheets of silicone resin (thermal conductivity 5 W / mm / K) having a length of 100 mm × width of 30 mm × thickness of 0.5 mm were used for the electrical insulator sheet. The silicone resin used was a boron nitride filler dispersed therein. For the metal resistance heating element, a stainless steel foil of 95 mm in length, 25 mm in width and 0.05 mm in thickness, on which a circuit pattern was formed by etching, was prepared, and two power feeding cables were attached to the electrodes by spot welding. . In this way, a heating heating element 11 made of a metal resistance heating element covered with an electrical insulator sheet was produced.

  As the airtight member 14, an O-ring made of Viton having an inner size of 105 mm × width 35 mm × thickness 2 mm was prepared. The hermetic member 14 and the heating element 11 for heating described above are fitted in the recesses and grooves formed in the ceramic plate, respectively, and the two ceramic plates are sandwiched between the hermetic member 14 and the heating element 11 for heating. Superimposed. At that time, the two power supply cables were taken out from the heater unit 1 through an airtight state through a through hole provided in one ceramic plate. These two ceramic plates were joined with four stainless steel bolts (M4 length 25) coated with PTFE and four stainless steel nuts coated with Teflon. Since the position and method of connection by these bolts and nuts were performed in a normal manner, the description thereof will be omitted. Thus, the heater unit 1 was produced.

  Next, as the heat insulating member 2, one rectangular parallelepiped member made of PTFE having a length of 165 mm, a width of 60 mm, and a height of 30 mm was prepared. A rectangular flat plate made of PTFE having a width of 50 mm, a height of 20 mm, and a thickness of 4 mm is formed by processing a hollow portion having a width of 50 mm, a height of 20 mm, and a depth of 161 mm from one end portion in the longitudinal direction of the rectangular parallelepiped member. Was made. Then, on the inner wall of this hollow portion, a single flow path 23 that spirally turns four times in the longitudinal direction as shown in FIGS. 4 to 6 was formed. The spiral flow path 23 was formed so that one groove having a width of 25 mm and a depth of 1 mm extended from one end to the other end in the longitudinal direction of the space formed when the cavity was covered. Thereby, when the heater unit 1 is installed so that the central portion in the longitudinal direction of the space coincides with the central portion in the longitudinal direction of the space, the inlet side formed respectively at both ends in the longitudinal direction of the heat insulating member 2 The flow path 23 can be communicated with the space 24 and the outlet side space 25.

  A through-hole with an inner diameter of 6 mm was drilled in the central part of the wall surface corresponding to the end of the cavity, and a through-hole with an inner diameter of 6 mm was drilled in the central part of a rectangular flat plate serving as a lid for the cavity. Then, a PTFE tube having an outer diameter of 8 mm, an inner diameter of 6 mm, and a length of 20 mm was joined to each of these through holes by welding to form a liquid inlet 21 and a liquid outlet 22. Then, the heater unit 1 described above is inserted into the cavity, and is fixed at a position where the central portions coincide with each other as described above, and the inlet of the cavity is closed by a lid welded with the PTFE tube described above by welding. . Thus, the heating apparatus provided with one flow path in which the liquid inlet 21, the inlet side space 24, the flow path 23, the outlet side space 25, and the liquid outlet 22 are communicated in this order was completed. .

  In order to confirm the performance of this heating device, a heating test was conducted when water was continuously supplied at 1 L / min. Specifically, 25 ° C. water is continuously supplied at a flow rate of 1 L / min to the liquid inlet 21 of the liquid heating device in which the temperature of the entire apparatus is 25 ° C. Power was supplied to the metal resistance heating element so that the heat generation amount was 2 kW. Then, the temperature of the water at the fluid outlet 22 and the surface temperature of the heating device after 5 seconds, 10 seconds, 20 seconds, 60 seconds, 10 minutes, 60 minutes, 12 hours and 24 hours from the start of power feeding were measured. . The results are shown in Table 1 below.

  As can be seen from Table 1 above, the temperature of the fluid outlet 22 reached 55 ° C. in a very short time of 10 seconds after the start of power supply, and then maintained that temperature for 24 hours or more. Further, the surface temperature of the heating apparatus hardly increased until 60 minutes, and stabilized at around 36.3 ° C. after 12 hours or more.

  Next, after the power supply to the metal resistance heating element is stopped and the apparatus is allowed to cool to 25 ° C., a current is applied to the metal resistance heating element so that the heating value is 4 kW instead of 2 kW. An experiment was conducted in which water was heated in the same manner as described above except that the sample was poured. The results are shown in Table 2 below.

  As can be seen from Table 2 above, the temperature of the fluid outlet 22 reached 85 ° C. in a relatively short time of 20 seconds after the current started to flow, and then maintained that temperature for more than 24 hours. Further, the surface temperature of the heating device did not rise so much until 60 minutes, and stabilized at around 67.4 ° C. after 12 hours or more had elapsed.

  Next, 24 hours after the start of power supply, the supply of water to the heating device was stopped and the power supply to the metal resistance heating element was stopped, and this state was left for 60 minutes. After 60 minutes, 25 ° C. water was continuously supplied to the heating device again at a flow rate of 1 L / min, and at the same time, 4 kW of power was supplied to the metal resistance heating element. The results are shown in Table 3 below.

  As can be seen from Table 3 above, the temperature was stabilized at 85 ° C. in a short time of only 2 seconds after the start of power supply, and the surface temperature was stabilized at about 67.4 ° C. As can be seen by comparing the results of Table 2 and Table 3, it took 20 seconds for the temperature to stabilize in the case of Table 2 because the heater unit alone has a heat capacity, so that it reaches a stable temperature. In Table 3, it is considered that the outlet temperature was stabilized in only 2 seconds because the heater unit alone was already close to a stable temperature. Thus, the liquid heating apparatus of the present invention can be heated to a target temperature in a very short time.

[Example 2]
An experiment was conducted in which a heating apparatus having an auxiliary heat insulating member as shown in FIG. The same heater unit 1 and heating member 2 as in Example 1 were used. As the auxiliary heat insulating member 3 provided around the heating member 2, a hollow rectangular parallelepiped box-shaped body made of PTFE having an inner dimension of 185 mm × width 80 mm × height 50 mm × thickness 2 mm is prepared, and further, a PTFE diameter 5 mm X 24 cylindrical support members 32 having a length of 10 mm were prepared. Four of these support members 32 are arranged approximately evenly on the outer wall 6 surface of the heat insulating member 2 of the heating device used in Example 1 to form a gap 10 mm apart between the heat insulating member 2 and the auxiliary heat insulating member 3. . Thus, the heating apparatus provided with the auxiliary heat insulating member 3 was completed.

  In order to confirm the performance of this heating device, a heating test was conducted when water was continuously supplied at 1 L / min. Specifically, 25 ° C. water is continuously supplied at a flow rate of 1 L / min to the liquid inlet 21 of the liquid heating device whose overall temperature is 25 ° C., and at the same time, 4 kW is supplied to the metal resistance heating element. Power was supplied so that the amount of heat generated was reached. Then, the water temperature at the fluid outlet 22 and the surface temperature of the auxiliary heat insulating member 3 after 5 seconds, 10 seconds, 20 seconds, 60 seconds, 10 minutes, 60 minutes, 12 hours and 24 hours from the start of power supply It was measured. The results are shown in Table 4 below.

  As can be seen from Table 4 above, the temperature reached 85 ° C. in a relatively short time of 20 seconds from the start of power supply, and then maintained that temperature for 24 hours or more. Further, the surface temperature of the auxiliary heat insulating member 3 did not rise until 60 minutes and stabilized at 26.1 ° C. after 12 hours or more had elapsed. As can be seen by comparing Table 4 and Table 2 of Example 1, the use of the auxiliary heat insulating member could significantly suppress the increase in surface temperature. This is considered to be because the gap between the heat insulating member and the auxiliary heat insulating member contributed to heat insulation as an air heat insulating layer.

DESCRIPTION OF SYMBOLS 1 Heater unit 2 Heat insulation member 3 Auxiliary heat insulation member 11 Heating element 12 for heating, 13 Ceramic plate 14 Airtight member 15 Recess 16 Groove 21 Liquid inflow port 22 Liquid outflow port 23 Flow path 24 Inlet side space 25 Outlet side space 31 Void 32 Support Element

Claims (3)

  A heating device for heating a corrosive liquid, comprising a heater unit and a heat insulating member surrounding the heater unit and having an inlet and an outlet for the liquid, and the heater unit is SiC or a composite material containing SiC And a heating passage that is hermetically provided inside the ceramic body, and is provided with a flow path that communicates with the inlet and the outlet and that spirals around the heater unit at least once. Heating device.   The heating device according to claim 1, wherein a groove of the flow path is formed on a side of the heat insulating member that contacts the ceramic body.   The heating apparatus according to claim 1 or 2, wherein an auxiliary heat insulating member is provided around the heat insulating member, and a gap is provided between the heat insulating member and the auxiliary heat insulating member.

Images