Patent Publication Number: US-10775075-B2

Title: Fluid heater

Description:
The present invention relates to a fluid heater that heats a fluid such as a liquid material that serves as the raw material of a gas that is used, for example, in a semiconductor manufacturing process. 
     TECHNICAL BACKGROUND 
     Conventionally, a vaporization system that vaporizes a liquid material is used to create the gas that is used in a semiconductor manufacturing process such as, for example, a film formation process or the like. 
     In this vaporization system, as is shown, for example, in Patent document 1, a heater that is constructed by forming the conduits along which the fluid flows, and also the heating apparatus that heats these conduits from cast aluminum is used for a vaporizer that vaporizes a liquid material by heating it, and also for a preheater and the like that preheats the liquid material that is introduced into that vaporizer. 
     However, when the conduits and heater are formed by casting, it is difficult to reduce their size, and they are also expensive to produce. Moreover, because irregularities in the casting give rise to changes in the thermal conductivity of the conduits and heater, it is difficult, in some cases, to obtain a satisfactory heating performance. 
     DOCUMENTS OF THE PRIOR ART 
     Patent Documents 
     [Patent document 1] Japanese Unexamined Patent Application (JP-A) No. 2002-90077 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The present invention was therefore conceived in order to solve the above-described problems, and it is a principal object thereof to provide a fluid heater that can be easily reduced in size, that can be manufactured cheaply, and that provides a stable heating performance. 
     Means for Solving the Problem 
     Namely, the fluid heater according to the present invention is a fluid heater that heats a fluid using a heater, and that includes: a heating block in which an internal flow path having an intake port through which the fluid is introduced, and a discharge port through which the fluid is discharged is formed by machining, and in which a heater insertion portion that extends in a predetermined axial direction is formed, wherein the internal flow path has a plurality of main flow path portions that extend in the predetermined axial direction, and one or a plurality of connecting path flow portions that connect the plurality of main flow path portions together, and wherein the plurality of main flow path portions are provided so as to surround the heater insertion portion. 
     If this type of structure is employed, then because the internal flow path is formed in the heating block by machining, it can easily be reduced in size, and can be manufactured inexpensively. Moreover, because there are few manufacturing irregularities, unlike the case with conventional casting, it is possible to obtain a stable heating performance. In particular, because the internal flow path has the plurality of main flow path portions that extend in the axial direction of the heater insertion hole, it is possible to effectively utilize the heat from the heater to heat the fluid. 
     It is desirable that, as a result of the one or plurality of the connecting flow path portions connecting together end portions in a longitudinal direction of the plurality of main flow path portions, the internal flow path be formed as a flow path that turns back on itself a plurality of times between the intake port and the discharge port. 
     If this type of structure is employed, it becomes possible to increase the flow path length of the internal flow path inside the heating block, and to enlarge the heat exchange area where heat is exchanged with the fluid, and to thereby improve the heating performance. 
     It is also desirable for either at least one main flow path portion (hereinafter, this will be referred to as a midstream main flow path portion) other than the most upstream side main flow path portion, which is closest to the intake port, and the most downstream side main flow path portion, which is closest to the discharge port, or else the heater insertion portion to be positioned between the most upstream side main flow path portion and the most downstream side main flow path portion. 
     If this type of structure is employed, because either at least one midstream main flow path portion, or else the heater insertion portion is positioned between the most upstream side main flow path portion through which the comparatively low-temperature fluid flows during the initial heating stage, and the most downstream side main flow path portion through which the comparatively high-temperature fluid flows during the final stages of heating, it is possible to prevent the fluid flowing through the most downstream side main flow path portion being cooled by the fluid flowing through the most upstream side main flow path portion. 
     It is also desirable for the discharge port to be formed above the intake port, and for the internal flow path to be formed so as to either extend in a horizontal direction, or so as to slope upwards as it moves towards the downstream side between the intake port and the discharge port. 
     If this type of structure is employed, any air bubbles that are contained in the fluid flowing through the internal flow path do not become trapped inside the internal flow path, but are instead discharged from the discharge port together with the fluid that is flowing through the internal flow path. As a consequence of this, the fluid flowing through the internal flow path can be efficiently heated. Moreover, if the air bubbles end up growing so as to form a large air bubble, and this large air bubble is pushed towards the downstream side, then this affects the supply rate control by the supply rate controller, however, this is prevented by the above-described structure. 
     It is also desirable for the above-described predetermined axial direction to be a horizontal direction, and for the one or plurality of connecting flow paths portions to be formed sloping upwards towards the downstream side. 
     If this type of structure is employed, then because the main flow path portions extend in a horizontal direction, and the one or plurality of connecting flow path portions are formed sloping upwards, any air bubbles contained in the fluid flowing through the internal flow path are discharged from the discharge port. 
     It is also desirable for the heating block to have a generally column-shaped configuration, and for one of the main flow path portions to open onto one end surface in the longitudinal direction of the heating block so as to form the intake port, and for another one of the main flow path portions to open onto the same one end surface in the longitudinal direction so as to form the discharge port. 
     If this type of structure is employed, it is possible to form the intake port and the discharge port simply by forming the main flow path portions in the heating block by machining, so that the manufacturing is simplified. Moreover, by forming the intake port and the discharge port in the same one end surface in the longitudinal direction of the heating block, the internal flow path in the manifold block can be joined to the internal flow path in the heating block simply by mounting the one end surface in the longitudinal direction of the heating block onto the manifold block, so that the need for a conduit structure is eliminated. 
     Effects of the Invention 
     According to the present invention which has the above-described structure, because an internal flow path is formed by machining in a heating block, the size of the fluid heater can easily be reduced, and the fluid heater can also be manufactured cheaply. Moreover, because manufacturing irregularities such as those produced by conventional casting are decreased, a stable heating performance can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a typical view showing the structure of a vaporization system according to the present embodiment. 
         FIG. 2  is a perspective view of a preheater according to the same embodiment. 
         FIG. 3  shows a plan view as seen from a mounting surface of the preheater of the same embodiment, and also shows a side view thereof. 
     
    
    
     BEST EMBODIMENTS FOR IMPLEMENTING THE INVENTION 
     Hereinafter, an embodiment of a vaporization system according to the present invention will be described with reference made to the drawings. 
     A vaporization system  100  of the present embodiment is used to supply gas at a predetermined flow rate to a chamber that is incorporated, for example, on a semiconductor manufacturing line or the like, and is where a semiconductor manufacturing process is performed. As is shown in  FIG. 1 , the vaporization system  100  is equipped with a vaporization unit  2  that vaporizes a liquid raw material, and a mass flow controller  3  that controls the flow rate of the gas that is vaporized by this vaporization unit  2 . 
     The vaporization unit  2  is provided with a vaporizer  21  that vaporizes a liquid material using a baking method, a supply rate controller  22  that controls the supply rate of the liquid material to the vaporizer  21 , and a preheater  23  that preheats the liquid material supplied to the vaporizer  21  to a predetermined temperature. 
     The vaporizer  21 , the supply rate controller  22 , and the preheater  23  are mounted on a device mounting surface B 1   x  that is set on one surface of a body block B 1  (hereinafter, this is referred to as a first body block B 1 ) that has an internal flow path formed inside it. Here, the first body block B 1  is made from a metal such as, for example, stainless steel or the like, and has the general outline of an elongated column (specifically, the general outline of a rectangular parallelepiped). The aforementioned device mounting surface B 1   x  is an elongated rectangular surface. Note that the first body block B 1  of the present embodiment is installed on a semiconductor manufacturing line or the like such that the longitudinal direction thereof is aligned in an up-down direction (i.e., in a vertical direction). 
     Specifically, the preheater  23 , the supply rate controller  22 , and the vaporizer  21  are mounted on a straight line that extends in the longitudinal direction on the device mounting surface B 1   x . Moreover, the preheater  23 , the supply rate controller  22 , and the vaporizer  21  are connected together in series in this sequence from the upstream side by internal flow paths (R 1 ˜R 4 ) that are formed in the first body block B 1 . Note also that a heater H 1  that is used to heat the liquid material flowing through the internal flow paths (R 1 ˜R 4 ) is also provided inside the first body block B 1 . Moreover, an aperture on the upstream side of the internal flow path R 1  in the first body block B 1  is connected to a liquid material intake port P 1  that is provided in a surface at one end in the longitudinal direction of the first body block B 1 . 
     The vaporizer  21  has a storage vessel  211  in the form of a vaporization tank that has an internal space for storing a liquid material, and a vaporizer heater  212  that is provided in the storage vessel  211  and is used to vaporize the liquid material. 
     The storage vessel  211  has a mounting surface  211   x  that is mounted on the device mounting surface B 1   x  of the first body block B 1 . The storage vessel  211  of the present embodiment has the general outline of, for example, an elongated column, and a surface at one end in the longitudinal direction thereof serves as the mounting surface  211   x . Specifically, the storage vessel  211  has the general outline of a rectangular parallelepiped. Moreover, the storage vessel  211  of the present embodiment is installed on a semiconductor manufacturing line or the like such that the longitudinal direction thereof is aligned in a horizontal direction. 
     An intake port that is used to introduce a liquid material from the internal flow path R 3  in the first body block B 1 , and a discharge port that is used to discharge vaporized gas into the internal flow path R 4  in the first body block B 1  are formed in the mounting surface  211   x . Moreover, by mounting the mounting surface  211   x  of the storage vessel  211  on the device mounting surface B 1   x  of the first body block B 1 , the intake port formed in the mounting surface  211   x  is able to communicate with the aperture of the internal flow path R 3  (i.e., the aperture on the downstream side) that is formed in the device mounting surface B 1   x , and the discharge port formed in the mounting surface  211   x  is able to communicate with the aperture of the internal flow path R 4  (i.e., the aperture on the upstream side) that is formed in the device mounting surface B 1   x.    
     A liquid level sensor  213  that is used to detect the storage volume of the stored liquid material is also provided in the storage vessel  211 . In the present embodiment, the liquid level sensor  213  is inserted into the interior through the top wall of the storage vessel  211 . 
     The vaporizer heater  212  is inserted through a wall portion (for example, a bottom wall portion) of the storage vessel  211 . Specifically, the vaporizer heater  212  is inserted (in the longitudinal direction) towards the first body block B 1  from the surface on the opposite side from the mounting surface  211   x  (i.e., from the other end surface  231   c  in the longitudinal direction). 
     The supply rate controller  22  is a control valve that controls the flow rate of the supply of liquid material to the vaporizer  21 , and, in the present embodiment, is a solenoid shut-off valve. This solenoid shut-off valve  22  is mounted such that it covers the aperture (i.e., the aperture on the downstream side) of the internal flow path R 2  and the aperture (i.e., the aperture on the upstream side) of the internal flow path R 3  that are formed in the device mounting surface B 1   x  of the first body block B 1 . Specifically, a valve body (not shown) of the solenoid shut-off valve  22  is created such that it is able to either open up or block off the aperture (i.e., the aperture on the downstream side) of the internal flow path R 2  and the aperture (i.e., the aperture on the upstream side) of the internal flow path R 3  that are formed in the device mounting surface B 1   x.    
     In addition, a controller (not shown) controls the turning ON and OFF of the solenoid shut-off valve  22  based on detection signals from the liquid level sensor  213  provided in the storage vessel  211  such that the liquid material stored in the storage vessel  211  is kept constantly at a predetermined volume. By doing this, during a vaporization operation, the liquid material is supplied intermittently to the vaporizer  21 . Here, if the supply flow rate of the liquid material is controlled by supplying it intermittently using ON/OFF control, then compared with when the supply flow rate of the liquid material is controlled continuously using a mass flow controller or the like, the size of the vaporizer unit  2  can be reduced. 
     The preheater  23  has a preheating block (i.e., a heating block)  231  that has an internal flow path  231 R through which the liquid material is able to flow formed inside it by machining, and a preheating heater (i.e., a heating heater)  232  that is used to preheat the liquid material provided in this preheating block  231 . The liquid material is heated by this preheater  23  to a temperature immediately prior to vaporization (i.e., to just less than boiling point). 
     The preheating block  231  has a mounting surface  231   x  that is mounted onto the first body block B 1 . The preheating block  231  of the present embodiment has the general outline, for example, of an elongated column, and one end surface in the longitudinal direction thereof serves as the mounting surface  231   x . Specifically, the preheating block  231  has the general outline of a rectangular parallelepiped. Moreover, the preheating block  231  of the present embodiment is installed on a semiconductor manufacturing line or the like such that the longitudinal direction thereof is aligned in a horizontal direction. 
     Moreover, a heater insertion hole  231 H is formed by mechanical processing in the preheating block  231 . This heater insertion hole  231 H is used to insert the preheating heater  232  in the longitudinal direction from a central portion of the other end surface  231   c  in the longitudinal direction of the preheating block  231 . Specifically, the heater insertion hole  231 H is a rectilinear flat-bottomed hole that extends in a predetermined axial direction (i.e., in a horizontal direction in the present embodiment), and is formed, for example, by cutting processing such as hole-boring processing or the like. 
     An intake port  231   a  that is used to introduce the liquid material from the internal flow path R 1  in the first body block B 1 , and a discharge port  231   b  that is used to discharge the preheated liquid material into the internal flow path R 2  in the first body block B 1  are formed in the mounting surface  231   x . Moreover, by mounting the mounting surface  231   x  of the preheating block  231  on the device mounting surface B 1   x  of the first body block B 1 , the intake port  231   a  that is formed in the mounting surface  231   x  is able to communicate with the aperture of the flow path R 1  (i.e., the aperture on the downstream side) that is formed in the device mounting surface B 1   x , and the discharge port  231   b  that is formed in the mounting surface  231   x  is able to communicate with the aperture of the flow path R 2  (i.e., the aperture on the upstream side) that is formed in the device mounting surface B 1   x.    
     By inserting the preheating heater  232  into the heater insertion hole  231 H that is formed in the preheating block  231 , the preheating heater  232  is positioned so as to face the first body block B 1  (in the longitudinal direction) from the surface of the preheating block  231  on the opposite side from the mounting surface  231   x  (i.e., from the other end surface  231   c  in the longitudinal direction). 
     As is shown in  FIG. 2  and  FIG. 3 , in particular, in the preheating block  231 , the internal flow path  231 R through which the liquid material flows has a plurality of longitudinal flow path portions (i.e., main flow path portions)  231 R 1  that extend in a predetermined axial direction (i.e., in a longitudinal direction), and either one or a plurality of connecting flow path portions  231 R 2  that connect together the plurality of longitudinal flow path portions  231 R 1 . 
     The plurality of longitudinal flow path portions  231 R 1  are provided around the periphery of the heater insertion portion  231 H so as to surround the heater insertion portion  231 H. In the present embodiment, there are four longitudinal flow path portions  231 R 1  (X 1 ˜X 4 ). These longitudinal flow path portions  231 R 1  have a rectilinear shape that extends substantially in parallel with the heater insertion hole  231 H, and are formed by performing cutting processing such as, for example, hole-boring processing on the mounting surface  231   x  of the preheating block  231 . Note that in the present embodiment, the longitudinal flow path portions  231 R 1  are provided so as to extend towards the other end side in the longitudinal direction beyond the distal end of the heater insertion hold  231 H (see the side view in  FIG. 3 ). 
     Moreover, the one or plurality of connecting flow path portions  231 R 2  connect together end portions in the longitudinal direction of mutually adjacent longitudinal flow path portions  231 R 1 . In the present embodiment, because there are four longitudinal flow path portions  231 R 1 , there are three connecting flow path portions  231 R 2  (Y 1 ˜Y 3 ). These connecting flow path portions  231 R 2  have a rectilinear shape that extends in a perpendicular direction relative to the longitudinal direction. The connecting flow path portions  231 R 2  can be formed by performing cutting processing such as, for example, hole-boring processing on a side surface of the preheating block  231 , and then blocking off the aperture portions formed in that side surface using a lid body (not shown). Alternatively, it is also possible to form a connecting flow path portion  231 R 2  that connects together two longitudinal flow path portions  231 R 1  by forming a recessed portion in an end surface in the longitudinal direction of the preheating block  231  such that the two longitudinal flow path portions  231 R 1  are opened up, and then blocking off this recessed portion using a lid body. 
     Accordingly, a reciprocating flow path that turns back on itself either once or a plurality of times between the one end and the other end in the longitudinal direction inside the preheating block  231  so as to surround the periphery of the preheating heater  232  is formed by the plurality of longitudinal flow path portions  231 R 1  and the plurality of connecting flow path portions  231 R 2 . Specifically, as a result of the plurality of connecting flow paths  231 R 2  connecting together the end portions in the longitudinal direction of the plurality of longitudinal flow path portions  231 R 1 , the internal flow path  231 R is formed as a single flow path that extends from the intake port  231   a  to the discharge port  231   b.    
     Furthermore, the intake port  231   a  is formed as a result of one of the longitudinal flow path portions  231 R 1  opening onto the one end surface  231   x  (i.e., the mounting surface) in the longitudinal direction of the preheating block  231 . Namely, this particular longitudinal flow path portion  231 R 1  (X 1 ) is the most upstream-side longitudinal flow path portion inside the preheating block  231 . 
     The discharge port  231   b  is formed as a result of another one of the longitudinal flow path portions  231 R 1  opening onto the one end surface  231   x  (i.e., the mounting surface) in the longitudinal direction of the preheating block  231 . Namely, this particular longitudinal flow path portion  231 R 1  (X 4 ) is the most downstream-side longitudinal flow path portion inside the preheating block  231 . 
     In addition, the discharge port  231   b  is formed above the intake port  231   a  in the one end surface  231   x  in the longitudinal direction of the preheating block  231 . Specifically, the intake port  231   a  and the discharge port  231   b  are placed opposite each other on either side of the heater insertion hole  231 H. Namely, the most upstream-side longitudinal flow path  231 R 1 , which is located closest to the intake port  231   a , and the most downstream-side longitudinal flow path  231 R 1 , which is located closest to the discharge port  231   b , are placed opposite each other on either side of the heater insertion hole  231 H. 
     Furthermore, in the preheating block  231  of the present embodiment, the internal flow path  231 R is formed either so as to run horizontally from the intake port  231   a  to the discharge port  231   b , or so as to slope upwards towards the downstream side from the intake port  231   a  to the discharge port  231   b . In the present embodiment, because the preheating block  231  is mounted side-on such that the longitudinal direction of the preheating block  231  is aligned in a horizontal direction, the plurality of longitudinal flow path portions  231 R 1  are formed extending in a horizontal direction, and the plurality of connecting flow path portions  231 R 2  are formed sloping vertically upwards towards the downstream side. 
     More specifically, in the preheating block  231  of the present embodiment, the plurality of longitudinal flow path portions  231 R 1  are formed at mutually different heights relative to each other, and the plurality of connecting flow path portions  231 R 2  are formed so as to connect together end portions in the longitudinal direction of two longitudinal flow path portions  231 R 1  that are mutually adjacent to each other in the height direction. In the preheating block  231  shown in  FIG. 2  and  FIG. 3 , if the four longitudinal flow path portions  231 R 1  are taken in sequence from the bottom as X 1 , X 2 , X 3 , and X 4 , and the three connecting flow path portions  231 R 2  are taken in sequence from the bottom as Y 1 , Y 2 , and Y 3 , then the first connecting flow path Y 1  connects together the other end portions in the longitudinal direction of the longitudinal flow path portions X 1  and X 2 , the second connecting flow path Y 2  connects together the one end portions in the longitudinal direction of the longitudinal flow path portions X 2  and X 3 , and the third connecting flow path Y 3  connects together the other end portions in the longitudinal direction of the longitudinal flow path portions X 3  and X 4 . As a result, when the preheating block  231  is viewed from the mounting surface  231   x , the connecting flow path portions  231 R 2  (Y 1 ˜Y 3 ) are formed in a zigzag configuration moving from the intake port  231   a  towards the discharge port  231   b  (see the plan view in  FIG. 3 ). As a consequence of this, the temperature of the liquid material flowing through the plurality of longitudinal flow path portions  231 R 1  (X 1 ˜X 4 ) becomes gradually higher as the liquid material moves from the bottommost longitudinal flow path portion  231 R 1  towards the topmost longitudinal flow path portion  231 R 1 . Namely, a relationship whereby [the temperature of the liquid material flowing through X 1 ]&lt;[the temperature of the liquid material flowing through X 2 ]&lt;[the temperature of the liquid material flowing through X 3 ]&lt;[the temperature of the liquid material flowing through X 4 ] is established. 
     If the vaporization unit  2  having the above-described structure is employed, the liquid material that is introduced via the liquid material intake port P 1  is preheated to a predetermined temperature as a result of flowing through the internal flow path  231 R in the preheating block  231  of the preheater  23 . The liquid material that is preheated by the preheater  23  is introduced intermittently into the vaporizer  21  by the ON/OFF control of the solenoid shut-off valve  22 , which is serving as a supply rate controller. The liquid material is thus constantly maintained in the vaporizer  21  so that the liquid material can be vaporized without being affected by the ON/OFF control of the solenoid shut-off valve  22 , and vaporized gas can thereby be generated continuously, and can be continuously discharged to the mass flow controller  3 . 
     Next, the mass flow controller  3  will be described. 
     As is shown in  FIG. 1 , the mass flow controller  3  is provided with a flow rate detector  31  that detects the flow rate of vaporized gas flowing through the flow path, and with a flow rate control valve  32  that controls the flow rate of the vaporized gas flowing through the flow path. 
     The flow rate detector  31  is formed by, for example, an electrostatic capacitance-type first pressure sensor  311  that detects the pressure on the upstream side of a fluid resistor  313  that is provided on the flow path, and by, for example, an electrostatic capacitance-type second pressure sensor  312  that detects the pressure on the downstream side of the fluid resistor  313 . 
     The flow rate control valve  32  is a control valve that controls the flow rate of the vaporized gas created by the vaporizer  21  and, in the present embodiment, is a piezo valve. 
     The flow rate detector  31  and the flow rate control valve  32  are mounted on a body block B 2  (hereinafter, referred to as the second body block B 2 ) that has internal flow paths (R 5  and R 6 ) formed inside it. Note that an upstream-side pressure sensor  34  and a shut-off valve  35  are provided on the upstream side of the flow rate control valve  32 . In addition, a heater H 2  is also provided in the second body block B 2 , and a downstream-side aperture of the internal flow path R 6  connects to a vaporized gas discharge port P 2 . This second body block B 2  is joined to the first body block B 1  of the vaporizer unit  2  so as to form a main body block B. A housing C that houses the devices that are mounted on one surface of the main body block B is also mounted on the main body block B. Note that the symbol CN denotes a connector that is used to connect an external control device. 
     According to the vaporization system  100  of the present embodiment, because the internal flow path  231 R and the heater insertion hole  231 H are formed by machining in the preheating block  231 , it is easy to reduce the size of the vaporization system, and the system can be manufactured cheaply. Moreover, because there are few manufacturing irregularities, unlike the case with conventional casting, it is possible to obtain a stable heating performance. In particular, because the internal flow path  231 R has the plurality of longitudinal flow path portions  231 R 1  that extend in the axial direction of the heater insertion hole  231 H, it is possible to effectively utilize the heat from the preheating heater  232  to heat the liquid material. 
     Moreover, according to the present embodiment, because the internal flow path  231 R is formed by the plurality of longitudinal flow path portions  231 R 1  and the plurality of connecting flow path portions  231 R 2  as a single flow path that extends from the intake port  231   a  to the discharge port  231   b , it is possible to increase the flow path length of the internal flow path  231 R inside the preheating block  231 , and to enlarge the heat exchange area where heat is exchanged with the liquid material, and to thereby improve the heating performance. 
     Furthermore, according to the present embodiment, because the longitudinal flow path portion  231 R 1  (X 1 ) that is located furthest to the upstream side through which the comparatively low-temperature liquid material flows during the initial heating stage, and the longitudinal flow path portion  231 R 1  (X 4 ) that is located furthest to the downstream side through which the comparatively high-temperature liquid material flows during the final stages of heating are located opposite each other on either side of the heater insertion hole  231 H, it is possible to prevent the liquid material flowing through the most downstream side longitudinal flow path portion  231 R 1  (X 1 ) being cooled by the liquid material flowing through the most upstream side longitudinal flow path portion  231 R 1  (X 4 ). 
     In addition to this, because the discharge port  231   b  is formed above the intake port  231   a  so that the internal flow path  231 R is formed either extending horizontally or sloping upwards as it moves towards the downstream side moving from the intake port  231   a  towards the discharge port  231   b , air bubbles do not becomes trapped inside the internal flow path  231 R, but are instead discharged from the discharge port  231   b  together with the liquid material that is flowing through the internal flow path  231 R. As a consequence of this, the liquid material flowing through the internal flow path  231 R can be efficiently heated. 
     Moreover, by using the preheater  23  of the present embodiment, it is possible to minimize any variations in the temperature of the storage vessel  211 , so that the temperature can easily be kept constant even when liquid material is being supplied to the storage vessel (i.e., to the vaporization tank)  211 . Accordingly, high flow rate vaporization can be performed stably even though the vaporizer  21  is only small in size. 
     In addition, the intake port  231   a  and the discharge port  231   b  can be formed by forming the longitudinal flow path portions  231 R 1  via machining in the longitudinal direction from the mounting surface  231   x  of the preheating block  231 , so that manufacturing is made easy. Moreover, by forming the intake port  231   a  and the discharge port  231   b  in the mounting surface  231   x  of the preheating block  231 , the internal flow paths R 1  and R 2  in the first body block B 1  can be connected to the internal flow path  231 R 1  in the preheating block  231  simply by mounting the mounting surface  231   x  of the preheating block  231  onto the first body block B 1 , so that there is no need for a conduit structure to be provided. 
     Furthermore, in the present embodiment, by mounting the vaporizer  21  and the supply rate controller  22  onto the device mounting surface B lx of the first body block B 1 , the vaporizer  21  and supply rate controller  22  become connected to each other via the flow paths R 1 ˜R 4  in the first body block B 1 . As a consequence, there is no need for any conduits to be provided between the vaporizer  21  and the supply rate controller  22 , so that the size of the vaporization system  100  can be reduced. Moreover, because the vaporizer  21  and the supply rate controller  22  are each mounted on the device mounting surface B 1   x , there is no need to form a flow path inside the vaporizer  21  in order to install the supply rate controller  22 , so that the structure of the vaporizer  21  can be simplified. 
     Note that the present invention is not limited to the above-described embodiment. 
     For example, in the above-described embodiment, a case is illustrated in which the longitudinal flow path portions are formed substantially in parallel with the center axis of the heater insertion hole, however, it is also possible for the longitudinal flow path portions to be formed on an inclination relative to the center axis of the heater insertion hole. In this case, in order to prevent air bubbles from becoming trapped in the internal flow path, in the same way as the connecting flow path portions of the above-described embodiment, it is desirable for the longitudinal flow path portions to be formed sloping upwards towards the downstream side. Moreover, if the longitudinal flow path portions are formed sloping upwards towards the downstream side, then the connecting flow path portions may either be formed extending in a horizontal direction, or they may be formed so as to slope upwards towards the downstream side. In addition to this, provided that the internal flow path is formed either extending in a horizontal direction, or else sloping upwards towards the downstream side between the intake port of the preheating block and the discharge port thereof, then air bubbles can be prevented from becoming trapped inside this internal flow path, and there are no particular limitations on the orientations of the longitudinal flow paths and the connecting flow paths, and a variety of arrangements are possible. 
     Moreover, the preheating block of the above-described embodiment has a single internal flow path, however, it is also possible for the internal flow path to be split into branches or to be merged together partway along its length, or for a plurality of mutually independent internal flow paths to be formed. 
     Furthermore, in the preheating block of the above-described embodiment, the longitudinal flow path portions have an intake port and a discharge port, however, it is also possible for the intake port and discharge port to be provided on other flow path portions that are connected to the connecting flow path portions or to the longitudinal flow path portions. 
     Furthermore, the preheating block and the storage vessel of the above-described embodiment have the general outline of a rectangular parallelepiped, however, in addition to this, they may be formed in some other type of columnar shape. For example, the preheating block may have the general outline of a circular column. Specifically, a structure may also be employed in which the preheating block  231  has the general outline of a circular column, and a flange portion is provided at one end in the longitudinal direction of this circular column shape. An end surface of this flange portion forms the mounting surface  231   x . Through holes (i.e., clearance holes) that are used to bolt the flange portion to the device mounting surface B 1   x  of the body block B 1  are formed in the flange portion. By doing this, the workability of the task of mounting the preheating block  231  onto the body block B 1  can be improved. Moreover, by forming the general outline of the preheating block  231  in a circular cylinder shape, the external surface area of the preheating block can be decreased, and the amount of heat discharge can accordingly be reduced. 
     In addition to this, the preheating block of the above-described embodiment is oriented such that the longitudinal direction thereof is aligned in a horizontal direction, however, it is also possible for it to be oriented such that the longitudinal direction thereof is aligned in an up/down direction (i.e., in a vertical direction), or in a direction that is inclined relative to the vertical direction. In this case, the heater insertion hole in the preheating block also extends in the up/down direction or in an inclined direction, and the internal flow path in the preheating block is formed so as to reciprocate either once or a plurality of times in the up/down direction, or in the inclined direction. 
     Moreover, in addition to a structure in which the longitudinal flow path portion located furthest to the upstream side and the longitudinal flow path portion located furthest to the downstream side are placed opposite each other on either side of the heater insertion portion, it is also possible to employ a structure in which the longitudinal flow path portion located furthest to the upstream side and the longitudinal flow path portion located furthest to the downstream side are not adjacent to each other, or a structure in which at least one midstream longitudinal flow path portion or else the heater insertion portion is positioned between the longitudinal flow path portion located furthest to the upstream side and the longitudinal flow path portion located furthest to the downstream side. Namely, in addition to a structure in which the heater insertion portion is located on a straight line connecting the longitudinal flow path portion located furthest to the upstream side and the longitudinal flow path portion located furthest to the downstream side, as is the case in the above-described embodiment, it is also possible to employ a structure in which at least one of the midstream longitudinal flow path portions is located on this same straight line. Moreover, it is also possible for the midstream longitudinal flow path portions or the heater insertion portion to not be positioned on this straight line between the longitudinal flow path portion located furthest to the upstream side and the longitudinal flow path portion located furthest to the downstream side. In this case, a structure is employed in which the midstream longitudinal flow path portions are positioned around the circumference of the heater insertion portion between the longitudinal flow path portion located furthest to the upstream side and the longitudinal flow path portion located furthest to the downstream side in the circumferential direction. 
     In the above-described embodiment, the internal flow path and the heater insertion portion are formed by machining, however, it is also possible, for example, to form a processing block having a heater insertion portion by casting, and to form the internal flow path in this processing block by machining. 
     In the above-described embodiment, the main body block B (i.e., B 1  and B 2 ) is positioned such that the longitudinal direction thereof is aligned in an up/down direction (i.e., in a vertical direction), however, it is also possible for the main body block B to be positioned such that the longitudinal direction thereof is aligned in a left/right direction (i.e., in a horizontal direction). 
     Furthermore, in the above-described embodiment, an example is described in which the fluid heater of the present invention is used as a preheater in a vaporization system, however, the fluid heater of the present invention can also be used as the vaporizer of a vaporization system. 
     In addition to this, as well as being used as a heater that heats a liquid material in a vaporization system, the fluid heater of the present invention may also be used as a liquid heater that heats other types of liquid, or as a gas heater that heats gases. 
     In the above-described embodiment, the main body block is formed by connecting together a first body unit and a second body unit, however, it is also possible for the main body block to be formed by a single block. In this case, the heater H 1  and the heater H 2  that are provided in the main body block may be formed by a single heater. By then varying the temperature inside this single heater, it is possible to perform temperature control such as making the temperature of the mass flow controller  3  side hotter than that of the vaporization unit  2  side. These temperature variations can be achieved by, for example, changing the resistance value inside the single heater. Moreover, it is also possible to perform temperature control such as making the temperature of the mass flow controller  3  side hotter than that of the vaporization unit  2  side by making the distance between the single heater and the device mounting surface on the mass flow controller  3  side different from the distance between the single heater and the device mounting surface on the vaporization unit  2  side. 
     Moreover, it is also possible to not provide a mass flow controller in the vaporization system of the above-described embodiment, and to only provide at least a vaporizer and a supply rate controller. 
     Furthermore, the vaporization system of the above-described embodiment is an integrated body in which the vaporization unit and the mass flow controller are housed in a single housing, however, it is also possible to employ a structure in which the vaporization unit and the mass flow controller are mutually independent bodies, and the vaporization unit body block and the mass flow controller body block are connected to connecting conduits. 
     Furthermore, it should be understood that the present invention is not limited to the above-described embodiment, and that various modifications and the like may be made thereto insofar as they do not depart from the spirit or scope of the present invention. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           100  . . . Vaporization system 
           2  . . . Vaporization unit 
           21  . . . Vaporizer 
           22  . . . Supply rate controller 
           23  . . . Preheater (Fluid heater) 
           231  . . . Preheating block (Heating block) 
           231   x  . . . Mounting surface (Longitudinal end surface) 
           231 H . . . Heater insertion hole 
           231 R . . . Internal flow path 
           231   a  . . . Intake port 
           231   b  . . . Discharge port 
           231 R 1  . . . Longitudinal flow path portion (Main flow path portion) 
           231 R 2  . . . Connecting flow path portion 
           232  . . . Preheating heater