Steam generating device and steam generating method

Abstract

To suppress the generation of droplets in steam which is supplied to a device using steam.SOLUTION: A steam generator comprises: a steam generation part for generating steam; a flow rate control part for adjusting a flow rate of liquid supplied to the steam generation part; a steam detection part having a droplet collection part for collecting and evaporating droplets in steam which is supplied from the steam generation part; a pressure acquisition part for acquiring upstream-side steam pressure supplied to the steam detection part from the steam generation part at an upstream side rather than the droplet collection part; and a steam temperature acquisition part for acquiring temperature of steam in the steam detection part. When the upstream-side steam pressure is equal to or higher than preset first pressure, the flow rate control part reduces the flow rate of the liquid supplied to the steam generation part. When the upstream-side steam pressure is lower than the first pressure and the temperature acquired by the steam temperature acquisition part is equal to or higher than preset first temperature, the flow rate control part increases the flow rate of the liquid supplied to the steam generation part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steam generating device and a steam generating method. [Background technology]

[0002] SOECs (Solid Oxide Electrolyzer Cells) are known that produce hydrogen by electrolyzing high-temperature steam (see, for example, Patent Document 1). In the hydrogen production device described in Patent Document 1, steam preheated by heat exchange with 900°C heat supplied from a nuclear reactor, which is an external heat source, is supplied to the SOEC. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-90425 Summary of the Invention [Problem to be solved by the invention]

[0004] If the water vapor supplied to an SOEC contains liquid droplets, the droplets adhere to the hot wall surface and instantaneously vaporize. The volume of the vaporized droplets increases by approximately 1,000 times. This instantaneous vaporization of the droplets causes sudden fluctuations in the pressure inside the SOEC. These pressure fluctuations may cause pulsation in the device generating the water vapor and the pump delivering the water, which is the raw material for the water vapor. Furthermore, if the amount of water vapor inside the SOEC becomes unstable due to the instantaneous vaporization of the droplets, this may damage the SOEC electrodes, etc. In this regard, Patent Document 1 does not take into consideration the impact of droplet vaporization inside the SOEC. This issue of droplet vaporization is a common issue not only in the field of SOECs but also in all devices that use vaporized liquids.

[0005] The present invention has been made to solve at least part of the above-mentioned problems, and has an object to suppress the generation of droplets in steam supplied to a device that uses the steam. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, a steam generating device is provided. This steam generating device includes a steam generating unit that generates steam by heating a liquid, a flow rate control unit that adjusts the flow rate of the liquid supplied to the steam generating unit, a steam detection unit having a droplet collecting unit that collects and evaporates droplets in the steam supplied from the steam generating unit, and the steam detection unit discharges steam that has passed through the droplet collecting unit, a pressure acquisition unit that acquires an upstream steam pressure, which is the vapor pressure supplied from the steam generating unit to the steam detection unit, upstream of the droplet collecting unit, and a steam temperature acquisition unit that acquires the temperature of the steam in the steam detection unit, and the flow rate control unit reduces the flow rate of the liquid supplied to the steam generating unit when the upstream steam pressure is equal to or greater than a predetermined first pressure, increases the flow rate of the liquid supplied to the steam generating unit when the upstream steam pressure is less than the first pressure and the temperature acquired by the vapor temperature acquisition unit is equal to or greater than a predetermined first temperature, and does not change the flow rate of the liquid supplied to the steam generating unit when the upstream vapor pressure is less than the first pressure and the temperature acquired by the vapor temperature acquisition unit is less than the first temperature.

[0008] According to this configuration, steam generated in the steam generating unit flows into the steam detecting unit. Liquid droplets contained in the steam that flows into the steam detecting unit are vaporized into steam by the liquid droplet collecting unit. Therefore, as the steam generated in the steam generating unit passes through the steam detecting unit, the amount of liquid droplets in the steam is reduced. As a result, the generation of liquid droplets in the steam supplied to a device (e.g., an SOEC) that uses the steam discharged from the steam detecting unit can be suppressed. Therefore, damage to the device due to the instantaneous vaporization of liquid droplets contained in the steam can be suppressed. Furthermore, the liquid droplet collecting unit evaporates the liquid droplets contained in the steam, thereby increasing the vapor pressure in the steam detecting unit. When the vapor pressure acquired by the pressure acquiring unit is equal to or greater than the first pressure, the flow rate of liquid droplets supplied to the steam generating unit is reduced. Here, the evaporation of liquid droplets by the liquid droplet collecting unit occurs because liquid that has not vaporized into steam exists in the steam generating unit. In this case, according to this configuration, the flow rate control unit reduces the flow rate of the liquid supplied to the steam generating unit, thereby suppressing the expansion rate of the two-phase region in the steam generating unit and suppressing the generation of liquid droplets due to an increase in the superheat of the heat transfer surface. This stabilizes the flow rate of steam generated by the steam generating unit. Furthermore, when the vapor pressure acquired by the pressure acquiring unit is less than the first pressure and the temperature of the steam in the steam detecting unit acquired by the steam temperature acquiring unit is equal to or higher than the first temperature, the flow rate of the liquid supplied to the steam generating unit increases. When the temperature in the steam generating unit is equal to or higher than the first temperature, the two-phase region in the steam generating unit shrinks and the gas phase region expands. In this case, with this configuration, by increasing the flow rate of the liquid supplied to the steam generating unit, steam above the saturation temperature can be discharged from the steam generating unit while maintaining the gas phase region in the steam generating unit. This improves the ability to track the steam flow rate required by the device that uses the steam discharged from the steam detecting unit.

[0009] (2) In the steam generating device of the above aspect, the pressure acquisition unit may include an upstream pressure acquisition unit that acquires the upstream vapor pressure, and a downstream pressure acquisition unit that acquires a downstream vapor pressure, which is the vapor pressure discharged from the vapor detection unit, downstream of the droplet collection unit. Instead of adjusting the flow rate of the liquid in accordance with a comparison between the upstream vapor pressure and the first pressure, the flow rate control unit may reduce the flow rate of the liquid supplied to the steam generating unit when a pressure difference obtained by subtracting the downstream vapor pressure from the upstream vapor pressure is equal to or greater than a predetermined second pressure, increase the flow rate of the liquid supplied to the steam generating unit when the pressure difference is less than the second pressure and the temperature acquired by the steam temperature acquisition unit is equal to or greater than a predetermined first temperature, and not change the flow rate of the liquid supplied to the steam generating unit when the pressure difference is less than the second pressure and the temperature acquired by the steam temperature acquisition unit is less than the first temperature. According to this configuration, the flow rate of the liquid supplied to the vapor generating unit is increased or decreased using the pressure difference obtained by subtracting the downstream vapor pressure downstream of the droplet collecting unit from the upstream vapor pressure, instead of the upstream vapor pressure upstream of the droplet collecting unit. The upstream vapor pressure and the downstream vapor pressure change depending on the influence (e.g., back pressure) of the device connected downstream of the vapor detecting unit. In this configuration, the flow rate of the liquid supplied to the vapor generating unit is controlled based on the pressure difference between the upstream vapor pressure and the downstream vapor pressure, which is not influenced by the device. As a result, this configuration can further suppress the expansion rate of the two-phase region in the vapor generating unit and suppress the generation of droplets due to an increase in the superheat of the heat transfer surface. In addition, while maintaining the gas phase region in the vapor generating unit, it is possible to further improve the ability to follow the steam flow rate required by the device that uses the steam discharged from the vapor detecting unit.

[0010] (3) In the steam generating device of the above aspect, the flow control unit may use the pressure difference to calculate the amount of droplets evaporated by the droplet collecting unit, and use the calculated amount of droplets to calculate the flow rate of the reduced liquid to be supplied to the steam generating unit. With this configuration, the liquid does not vaporize in the vapor generating unit and flows into the vapor detecting unit as droplets, and the amount of vaporized droplets is calculated by the droplet collecting unit. With this configuration, the liquid is supplied to the vapor generating unit at a reduced flow rate equivalent to the calculated amount of droplets, so the amount of droplets discharged from the vapor generating unit can be reduced.

[0011] (4) According to another aspect of the present invention, a steam generating device is provided. This steam generating device includes a steam generating unit that generates water vapor by heating a liquid, a flow rate control unit that adjusts the flow rate of the liquid supplied to the steam generating unit, and a steam detection unit having a droplet collecting unit that collects and evaporates droplets in the steam supplied from the steam generating unit, the steam detection unit discharging water vapor that has passed through the droplet collecting unit, a steam temperature acquisition unit that acquires the temperature of the water vapor in the steam detection unit, and a collecting unit temperature acquisition unit that acquires the temperature of the droplet collecting unit, wherein the flow rate control unit may reduce the flow rate of the liquid supplied to the steam generating unit when the temperature acquired by the collecting unit temperature acquisition unit is equal to or lower than a predetermined second temperature, increase the flow rate of the liquid supplied to the steam generating unit when the temperature acquired by the collecting unit temperature acquisition unit exceeds the second temperature and the temperature acquired by the steam temperature acquisition unit is equal to or higher than a predetermined first temperature, and not change the flow rate of the liquid supplied to the steam generating unit when the temperature acquired by the collecting unit temperature acquisition unit exceeds the second temperature and the temperature acquired by the steam temperature acquisition unit is lower than the first temperature. According to this configuration, droplets contained in the steam that flows into the steam detection unit are vaporized into steam by the droplet collection unit. Therefore, as the steam generated in the steam generation unit passes through the steam detection unit, the amount of droplets in the water vapor is reduced. As a result, the generation of droplets in the steam supplied to a device that utilizes the steam discharged from the steam detection unit is suppressed, thereby suppressing damage to the device due to the instantaneous evaporation of droplets contained in the steam. Furthermore, as the droplet collection unit evaporates the droplets contained in the steam, the temperature of the droplet collection unit decreases. When the temperature of the droplet collection unit acquired by the collection unit temperature acquisition unit is equal to or lower than the second temperature, the flow rate of droplets supplied to the steam generation unit decreases. In this case, with this configuration, the flow rate of liquid supplied to the steam generation unit decreases, thereby reducing the amount of droplets discharged from the steam generation unit and stabilizing the flow rate of steam generated from the steam generation unit. Furthermore, when the temperature of the droplet collection unit exceeds the second temperature and the temperature of the steam in the steam detection unit is equal to or higher than the first temperature, the flow rate of liquid supplied to the steam generation unit increases. This allows steam at or above the saturation temperature to be discharged from the steam generating unit while maintaining a gas phase region within the steam generating unit, thereby improving the ability to track the steam flow rate required by the device that uses the steam discharged from the steam detecting unit.

[0012] (5) The steam generating device of the above aspect may further include a steam utilization unit located downstream of the steam detection unit, wherein the steam generating unit is supplied with liquid water to generate water vapor, and the steam utilization unit generates hydrogen using water vapor discharged from the steam detection unit at a higher temperature than the steam detection unit. According to this configuration, liquid water is supplied to the steam detection unit, and water vapor is supplied to the steam detection unit. The steam utilization unit generates hydrogen at a higher temperature than the steam detection unit using the water vapor discharged from the steam detection unit. In this configuration, the steam detection unit, which is in the medium temperature range and has a lower temperature than the steam utilization unit, vaporizes the liquid droplets in the water vapor. As a result, water droplets do not flow into the steam utilization unit, which reduces damage to the steam utilization unit caused by the instantaneous evaporation of water droplets within the steam utilization unit.

[0013] (6) In the steam generating device of the above aspect, the droplet collecting section may be a mesh having a plurality of openings arranged so as to intersect with the flow direction of water vapor within the steam detecting section, and the length of the openings may be equal to or less than the average mist diameter of the spray flow and equal to or greater than the maximum length calculated from the allowable pressure loss from the steam generating section to the steam utilizing section. With this configuration, the mesh opening length of the droplet collection unit is less than the average mist diameter of the spray, so droplets in the spray come into contact with the mesh and vaporize. Meanwhile, the mesh opening length is greater than the maximum length calculated from the allowable pressure loss from the steam generation unit to the steam utilization unit, so the pressure loss for steam passing through the droplet collection unit is an allowable value. As a result, with this configuration, the droplet collection unit is formed within the steam detection unit within the pressure loss allowable by design and within the range in which droplets in the spray vaporize.

[0014] The present invention can be realized in various forms, for example, in the form of a steam generation device, a water vapor generation device, a hydrogen production system, an SOEC, a steam generation method, a water vapor generation method, a system including these devices, a computer program for executing these devices, a server device for distributing this computer program, a non-transitory storage medium storing the computer program, etc. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram of a steam generating device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional schematic view of a steam generating section. [Figure 3] FIG. 3 is an explanatory diagram of the temperature of the wall surface in the state shown in FIG. 2. [Figure 4] FIG. 1 is an explanatory diagram of the expansion of the two-phase region and the generation of water droplets. [Figure 5] FIG. 10 is a schematic cross-sectional view of the steam generating section after the water supply flow rate is reduced. [Figure 6] FIG. 6 is an explanatory diagram of the temperature of the wall surface in the state shown in FIG. 5. [Figure 7]FIG. 2 is an explanatory diagram of the relationship between the required steam amount of the steam utilization section and the length of the two-phase region. [Figure 8] FIG. 1 is an explanatory diagram of the relationship between the flow direction distance in a two-phase region and the proportion of water vapor. [Figure 9] 2 is a flowchart of a steam generating method according to the present embodiment. [Figure 10] FIG. 10 is an explanatory diagram of the change over time in the amount of steam generated when the required amount of steam increases. [Figure 11] FIG. 10 is an explanatory diagram of the change over time in the amount of steam generated when the required amount of steam increases. [Figure 12] FIG. 10 is a block diagram of a steam generating device according to a second embodiment. [Figure 13] FIG. 2 is an explanatory diagram of an average mist diameter. [Figure 14] 10 is a flowchart of a steam generating method according to a second embodiment. [Figure 15] FIG. 10 is a block diagram of a steam generating device according to a third embodiment. [Figure 16] 10 is a flowchart of a steam generating method according to a third embodiment. [Figure 17] FIG. 10 is an explanatory diagram of the change over time in the amount of steam generated when the required amount of steam increases. DETAILED DESCRIPTION OF THE INVENTION

[0016] First Embodiment 1. Steam generator configuration: 1 is a block diagram of a steam generating device 100 according to one embodiment of the present invention. The steam generating device 100 of this embodiment generates hydrogen in a steam utilization unit 30 using high-temperature steam generated in a steam generating unit 10 by heating water. In the steam generating device 100 of this embodiment, a liquid droplet collecting unit 41 provided in a steam detecting unit 40 evaporates water droplets in the steam supplied from the steam generating unit 10. The water vapor discharged from the steam detecting unit 40 after passing through the liquid droplet collecting unit 41 flows into the steam utilization unit 30, where hydrogen is generated.

[0017] As shown in FIG. 1, the steam generating device 100 includes a pump 70, a flow rate adjusting unit 20, a steam generating unit 10, a steam detecting unit 40, a steam utilizing unit 30, a steam temperature sensor (steam temperature acquiring unit) 60, an upstream pressure sensor (upstream pressure acquiring unit) 50, and an ECU (Electronic Control Unit) 90 that controls each part of the steam generating device 100.

[0018] The pump 70 supplies liquid water to the flow rate adjustment unit 20. The flow rate adjustment unit 20 is a valve that opens and closes under the control of the ECU 90. The flow rate adjustment unit 20 adjusts the supply flow rate, which is the flow rate of water supplied from the pump 70, and supplies the water to the steam generation unit 10. The steam generation unit 10 generates steam by heating the liquid water supplied from the flow rate adjustment unit 20. The steam generation unit 10 is a cylindrical metal pipe. Water passes through the cylindrical pipe. Heat applied from outside the pipe is exchanged with the water passing through the pipe, causing the water to evaporate and change into steam. Within the pipe, a liquid phase region, a two-phase region (liquid and gas phases), and a gas phase region are formed in this order from the upstream side, which is the side of the flow rate adjustment unit 20. Details of each phase region within the pipe will be described later.

[0019] The water vapor generated by the steam generating unit 10 is supplied to the steam detecting unit 40. As shown in FIG. 1, the steam detecting unit 40 includes a droplet collecting unit 41 that collects and evaporates water droplets in the supplied water vapor. The steam detecting unit 40 is a cylindrical metal pipe. The water vapor supplied from the steam generating unit 10 passes through the cylindrical pipe. A metal mesh serving as the droplet collecting unit 41 formed on the cross section of the pipe is disposed midway along the pipe. In other words, the mesh serving as the droplet collecting unit 41 is disposed perpendicular to the flow direction of the water vapor within the steam detecting unit 40 (the direction of the arrow in FIG. 1). The mesh has a plurality of square openings. The water vapor that passes through the droplet collecting unit 41 within the steam detecting unit 40 is discharged toward the steam utilizing unit 30. In this embodiment, the temperature within the steam detecting unit 40 is maintained at a temperature of 120 degrees Celsius (°C) or higher and 130 degrees Celsius (°C) or lower.

[0020] The steam utilization unit 30 of this embodiment is an SOEC that generates hydrogen using water vapor discharged from the steam detection unit 40. The steam utilization unit 30 is located downstream of the steam detection unit 40. The temperature of the steam utilization unit 30 is 300°C or higher, which is higher than the temperature of the steam detection unit 40. The portion indicated by the solid line in FIG. 1 is composed of piping through which water vapor flows.

[0021] The steam temperature sensor 60 detects a steam temperature T1, which is the temperature of water vapor supplied from the steam generating unit 10 to the steam detecting unit 40. In other words, the steam temperature sensor 60 detects the steam temperature T1 inside the steam detecting unit 40. The upstream pressure sensor 50 detects the water vapor pressure (upstream steam pressure) P supplied from the steam generating unit 10 to the steam detecting unit 40 upstream of the droplet collecting unit 41.

[0022] The ECU 90 acquires a required steam amount, which is the amount of water vapor requested by the steam utilization unit 30. The ECU 90 controls the flow rate adjustment unit 20 using the acquired required steam amount, thereby controlling the supply flow rate from the flow rate adjustment unit 20 to the steam generation unit 10. The ECU 90 also acquires a steam temperature T1 detected by the steam temperature sensor 60 and a water vapor pressure P detected by the upstream pressure sensor 50. The ECU 90 changes the supply flow rate from the flow rate adjustment unit 20 to the steam generation unit 10 using the acquired steam temperature T1 and water vapor pressure P. When the detected water vapor pressure P is equal to or greater than a first pressure Pc serving as a preset threshold, the ECU 90 reduces the supply flow rate to the steam generation unit 10. The ECU 90 reduces the supply flow rate by slowing down the rate of change of the supply flow rate to the steam generation unit 10. When the detected water vapor pressure P is less than the first pressure Pc, the ECU 90 determines whether the detected steam temperature T1 is equal to or greater than a first temperature Tc1 serving as a preset threshold. The ECU 90 increases the supply flow rate to the steam generating unit 10 when the detected water vapor pressure P is less than the first pressure Pc and the detected steam temperature T1 is equal to or greater than the first temperature Tc1. The ECU 90 increases the supply flow rate by increasing the rate of change of the supply flow rate to the steam generating unit 10. When the detected water vapor pressure P is less than the first pressure Pc and the detected steam temperature T1 is less than the first temperature Tc1, the ECU 90 does not change the supply flow rate to the steam generating unit 10, but maintains the supply flow rate before the change. Note that the ECU 90 and the flow rate adjusting unit 20 in this embodiment correspond to a flow rate control unit.

[0023] 2. Relationship between steam pressure and steam temperature and the two-phase region in the steam generating section 10: The length of the two-phase region in the steam generating section 10 is related to the water vapor pressure P detected by the upstream pressure sensor 50 and the steam temperature T1 detected by the steam temperature sensor 60. Figure 2 is a cross-sectional schematic diagram of the steam generating section 10. Figure 2 illustrates the state change of water when the water vapor pressure P detected by the upstream pressure sensor 50 is equal to or greater than the first pressure Pc. As shown in Figure 2, water supplied to the steam generating section 10 vaporizes into steam by passing through, from the pump side, a liquid phase region, a two-phase region where liquid water and steam coexist, and a gas phase region. From the upstream pump 70 side, the water undergoes the following flow patterns: bubbly flow, slug flow, annular flow, and spray. The temperature of the wall surface 11 forming the cylindrical space of the steam generating section 10 differs between the liquid and two-phase regions and the gas phase region, as indicated by the type of hatching in Figure 2. In this embodiment, it is assumed that the heat flux in the two-phase region is constant and the heat transfer coefficient of the wall surface 11 in the two-phase region is uniform.

[0024] FIG. 3 is an explanatory diagram of the temperature of the wall surface 11 in the state shown in FIG. 2. In FIG. 3, the temperature of the wall surface 11, which changes depending on the flow direction distance from the inlet on the pump 70 side of the steam generating unit 10 to the outlet on the steam detecting unit 40 side, is shown by a solid line. The temperature of the water flowing into the steam generating unit 10 rises from the inlet temperature to the saturation temperature and then to the superheated steam temperature. The temperature of the wall surface 11 rises as the water temperature rises and the water changes phase. When the supply flow rate to the steam generating unit 10 increases, the temperatures in the two-phase region and the gas phase region of the wall surface 11 differ depending on the amount of steam generated. Therefore, in the region where the two-phase region expands and the gas phase region changes to a two-phase region due to an increase in the supply flow rate to the steam generating unit 10, the degree of superheat of the heat transfer surface, which is the difference between the temperature of the wall surface 11 and the saturation temperature, increases. Thereafter, the temperature of the wall surface 11 assumes a temperature distribution similar to that when the amount of steam is large.

[0025] Figure 4 is an explanatory diagram of the expansion of the two-phase region and the generation of water droplets AD. Figure 4 shows a schematic enlarged view of part A in Figure 2. As shown in Figure 4, a portion of the liquid film WT adhering to the wall surface 11 evaporates into water vapor through heat exchange via the wall surface 11. On the other hand, when the supply flow rate to the steam generating section 10 increases, expanding the two-phase region within the steam generating section 10, the water temperature changes faster than the temperature of the wall surface 11, which has a large time constant, due to the large heat capacity of the wall surface 11. During this transitional state, where the supply flow rate increases from a low to an increased state, a two-phase flow consisting mainly of annular flow forms on the heat transfer surface, which was in a high-temperature gas-phase region before the supply flow rate increase. This results in a liquid film evaporation mode with a high degree of surface superheat. In this liquid film evaporation mode, water evaporation is achieved by balancing evaporation from the wide interface with the surface superheat in the two-phase region due to the low thermal resistance of the thin liquid film WT. However, in the transition state, when a liquid film WT is formed on the high-temperature wall surface 11 in the gas-phase region, nucleate boiling occurs in the thin liquid film WT, and a local vapor film forms between the wall surface 11 and the liquid film WT. As a result, as shown in Figure 4, the liquid film WT breaks up and vaporizes into water droplets AD in the flow path, which are then discharged together with water vapor from the steam generating section 10. In other words, the expansion of the two-phase region in the steam generating section 10 increases the number of water droplets AD contained in the water vapor.

[0026] When water droplets AD in the water vapor supplied to the vapor detection unit 40 come into contact with the droplet collection unit 41 and vaporize, the water vapor pressure inside the vapor detection unit 40 increases. The ECU 90 of this embodiment reduces the supply flow rate to the vapor generation unit 10 when a certain amount or more of water droplets AD are vaporized by the droplet collection unit 41, based on the first pressure Pc. This reduces the two-phase region inside the vapor generation unit 10, and suppresses the generation of water droplets AD inside the steam generation unit 10.

[0027] 5 is a schematic cross-sectional view of the steam generating section 10 after the water supply flow rate has been reduced. When the supply flow rate to the steam generating section 10 is reduced, the amount of water vapor generated in the steam generating section 10 decreases, and as shown in FIG. 5, the two-phase region in the steam generating section 10 shrinks.

[0028] FIG. 6 is an explanatory diagram of the temperature of the wall surface 11 in the state shown in FIG. 5. In FIG. 6, the temperature of the wall surface 11, which changes according to the flow direction distance after the two-phase region in the steam generating section 10 has been reduced, is shown by a solid line. Also in FIG. 6, the temperature of the wall surface 11 before the two-phase region is reduced as shown in FIG. 3 is shown by a dashed line. In the state shown in FIG. 6, where the supply flow rate increases from a low state, the supply flow rate to the steam generating section 10 decreases, so the two-phase region is reduced and changes from the two-phase region to a gas phase region, and the superheat of the heat transfer surface increases gradually. Thereafter, the temperature of the wall surface 11 becomes the temperature distribution when the steam amount is small.

[0029] The ECU 90 of this embodiment increases the supply flow rate to the steam generating unit 10 when the steam temperature T1 supplied to the steam detecting unit 40 is equal to or higher than a first temperature Tc1, which is a threshold value. This expands the two-phase region in the steam generating unit 10 and increases the amount of water vapor generated by the steam generating unit 10. The increase in the amount of water vapor improves responsiveness when the amount of steam required by the steam utilizing unit 30 increases.

[0030] 7 is an explanatory diagram of the relationship between the required steam amount Fs,t of the steam utilization unit 30 and the length of the two-phase region. The amount of water vapor generated by the steam generation unit 10 is determined by the length of the two-phase region. Therefore, as shown in FIG. 7, in this embodiment, the ECU 90 controls the supply flow rate using the first pressure Pc and the first temperature Tc1 as thresholds, thereby controlling the length of the two-phase region in the steam generation unit 10 to be between x1 and x2.

[0031] Figure 8 is an explanatory diagram of the relationship between the flow direction distance in the two-phase region and the proportion of water vapor. Figure 8 shows the ratio of the liquid quality, which represents the proportion of water vapor in the two-phase region, to the liquid quality, which represents the proportion of liquid water, which changes depending on the flow direction distance in the two-phase region. In Figure 8, the steam quality Q when the distance along the flow direction in the two-phase region is x1 G1 And Liquid Quality Q L1 In addition, in Fig. 8, the steam quality Q when the flow direction distance of the two-phase region is expanded from x1 to x2 is shown by the dashed line. G2 And Liquid Quality Q L2 and are shown by solid lines.

[0032] In this embodiment, when the water vapor pressure P detected by the upstream pressure sensor 50 is equal to or greater than the first pressure Pc, the ECU 90 calculates the flow rate change rate ΔFl, which is the rate of change for reducing the supply flow rate Fl, using x1 and x2 shown in Figure 8 according to the following equation (1).

number

[0033] 3. Steam generation flow: Fig. 9 is a flowchart of the steam generation method of this embodiment. In the steam generation flow shown in Fig. 9, first, the ECU 90 acquires the required steam amount Fs,t from the steam utilization unit 30 (step S1). The ECU 90 controls the flow rate adjustment unit 20 to supply water to the steam generation unit 10 at a flow rate corresponding to the acquired required steam amount Fs,t (step S2). By controlling the flow rate of water supplied to the steam generation unit 10, the length of the two-phase region in the steam generation unit 10 changes.

[0034] The ECU 90 acquires the steam temperature T1 detected by the steam temperature sensor 60 and the water vapor pressure P detected by the upstream pressure sensor 50 (step S3). The ECU 90 determines whether the water vapor pressure P is equal to or greater than the first pressure Pc (step S4). If it is determined that the water vapor pressure P is equal to or greater than the first pressure Pc (step S4: YES), the ECU 90 reduces the supply flow rate Fl of water supplied to the steam generating unit 10 (step S5), and the processing from step S3 onwards is performed again. The ECU 90 supplies the supply flow rate Fl to the steam generating unit 10 at a rate of change obtained by subtracting the flow rate change rate ΔFl calculated by the above formula (1) from the rate of change of the supply flow rate Fl of the steam generating unit 10.

[0035] If it is determined in the processing of step S4 that the water vapor pressure P is less than the first pressure Pc (step S4: NO), the ECU 90 determines whether the steam temperature T1 is equal to or higher than the first temperature Tc1 (step S6). If it is determined that the steam temperature T1 is equal to or higher than the first temperature Tc1 (step S6: YES), the ECU 90 increases the supply flow rate Fl to the steam generating unit 10 (step S7), and the processing from step S3 onwards is performed again. The ECU 90 supplies the supply flow rate Fl to the steam generating unit 10 at a rate of change obtained by adding the flow rate change rate ΔFl to the rate of change of the supply flow rate Fl of the steam generating unit 10.

[0036] In the process of step S6, if it is determined that the steam temperature T1 is less than the first temperature Tc1 (step S6: NO), the ECU 90 determines whether or not the steam amount Fs,t required from the steam utilization unit 30 has changed (step S8). If it is determined that the steam amount Fs,t required has changed (step S8: YES), the process from step S1 onwards is carried out.

[0037] If it is determined in the process of step S8 that the required steam amount Fs,t has not changed (step S8: NO), the ECU 90 determines whether or not to terminate the generation of steam (step S9). If it is determined that the generation of steam should be terminated (step S9: YES), the ECU 90 terminates the generation of steam, and the steam generation flow ends. The ECU 90 terminates the generation of steam when the request signal disappears from the required steam amount Fs,t, or when the operation of the steam generating device 100 is stopped. If it is determined in the process of step S9 that the generation of steam should not be terminated (step S9: NO), the processes from step S3 onward are performed.

[0038] 4.Effects: 10 and 11 are diagrams illustrating the change over time in the steam generation rate Fg when the required steam rate Fs,t increases. When the supply flow rate Fl to the steam generating unit 10 changes in accordance with the required steam rate Fs,t of the steam utilization unit 30, the steam generation rate Fg generated in the steam generating unit 10 changes. Fig. 10 shows the changes over time in the supply flow rate Fl, the steam generation rate Fg, and the water vapor pressure P when the required steam rate Fs,t changes from a low state to a high state.

[0039] As shown in FIG. 10 , when the required steam volume changes from a low state to a high state at time T0, the supply flow rate Fl and the steam generation rate Fg begin to increase under the control of the ECU 90. When the supply flow rate Fl to the steam generating unit 10 increases, the two-phase region expands within the steam generating unit 10, which may result in unvaporized water droplets AD within the steam generating unit 10. When water vapor containing water droplets AD flows into the steam detecting unit 40, the water droplets AD come into contact with the droplet collecting unit 41 and vaporize. As a result, the water vapor pressure P momentarily increases, as shown in region AR1 of FIG. 10 . In this embodiment, when the water vapor pressure P is equal to or greater than the first pressure Pc, the ECU 90 reduces the supply flow rate Fl to the steam generating unit 10 by the flow rate change rate ΔFl, below the supply flow rate Fl determined from the required steam volume Fs,t. As a result, as shown in region AR2 of FIG. 10 , the rate of increase of the supply flow rate Fl temporarily decreases, and the water vapor pressure P is suppressed to be less than the first pressure Pc. That is, evaporation of the water droplets AD in the droplet collecting section 41 is suppressed.

[0040] Figure 11 shows the change in steam temperature T1 over time when the required steam volume Fs,t changes in the same way as in Figure 10. As shown in Figure 11, after time T0, the supply flow rate Fl to the steam generating section 10 increases, and the amount of heat required to generate steam in the steam generating section 10 increases. As a result, the steam temperature T1 begins to decrease. In the states shown in Figures 10 and 11, the amount of steam generated transitions from a low state to a high state, so the steam temperature T1 is equal to or higher than the first temperature Tc1.

[0041] As described above, in the steam generating device 100 of this embodiment, the steam detection unit 40 includes a droplet collection unit 41 that collects and evaporates water droplets in the supplied water vapor. The ECU 90 reduces the flow rate of water supplied to the steam generating unit 10 when the vapor pressure detected by the upstream pressure sensor 50 is equal to or greater than a first pressure Pc, which is a preset threshold. The ECU 90 increases the flow rate of water supplied to the steam generating unit 10 when the detected vapor pressure is less than the first pressure Pc and the temperature of the water vapor detected by the steam temperature sensor 60 is equal to or greater than a first temperature Tc1. When the detected vapor pressure is less than the first pressure Pc and the detected temperature of the water vapor is less than the first temperature Tc1, the ECU 90 does not change the flow rate of water supplied to the steam generating unit 10 but maintains the flow rate before the change. Therefore, in the steam generating device 100 of this embodiment, water droplets AD contained in the water vapor that flows into the steam detection unit 40 are evaporated into water vapor by the droplet collection unit 41. Therefore, when the water vapor generated in the steam generating unit 10 passes through the steam detecting unit 40, the amount of water droplets AD in the water vapor is reduced. As a result, the generation of water droplets AD in the water vapor supplied to the steam utilizing unit 30, which utilizes the water vapor discharged from the steam detecting unit 40, can be suppressed. Therefore, damage to the steam utilizing unit 30 due to the instantaneous evaporation of water droplets AD contained in the water vapor can be suppressed. Furthermore, the water vapor pressure P in the steam detecting unit 40 increases when the liquid droplet collecting unit 41 evaporates the water droplets AD contained in the water vapor. When the water vapor pressure P detected by the upstream pressure sensor 50 is equal to or greater than the first pressure Pc, the flow rate of water droplets AD supplied to the steam generating unit 10 is reduced. Here, the evaporation of water droplets AD by the liquid droplet collecting unit 41 occurs due to the presence of liquid water that has not evaporated into water vapor in the steam generating unit 10. In this case, in this embodiment, the supply flow rate Fl to the steam generating unit 10 is reduced, thereby suppressing the expansion rate of the two-phase region in the steam generating unit 10 and suppressing the generation of water droplets AD due to an increase in the degree of superheat of the heat transfer surface. This stabilizes the flow rate of water vapor generated by the steam generating unit 10. Furthermore, when the water vapor pressure P is less than the first pressure Pc and the steam temperature T1 in the steam detecting unit 40 detected by the steam temperature sensor 60 is equal to or higher than the first temperature Tc1, the supply flow rate Fl to the steam generating unit 10 increases.When the steam temperature T1 is equal to or higher than the first temperature Tc1, the two-phase region within the steam generating unit 10 is shrinking and the gas phase region is expanding. In this case, if the steam temperature T1 is set to be equal to or higher than the saturation temperature, the supply flow rate Fl to the steam generating unit 10 increases, thereby ensuring the gas phase region within the steam generating unit 10 and allowing steam at temperatures above the saturation temperature to be discharged from the steam generating unit 10. This improves the ability of the steam utilization unit 30, which utilizes the steam discharged from the steam detection unit 40, to follow the required steam amount Fs,t.

[0042] The steam generating device 100 of this embodiment also includes a steam utilization unit 30 that generates hydrogen using water vapor discharged from the steam detection unit 40. The steam utilization unit 30 is disposed downstream of the steam detection unit 40. The temperature of the steam utilization unit 30 is higher than the temperature of the steam detection unit 40. Therefore, in this embodiment, the steam detection unit 40, which has a medium temperature range that is lower than the temperature of the steam utilization unit 30, vaporizes the water droplets AD in the water vapor. As a result, the water droplets AD do not flow into the steam utilization unit 30, and damage to the steam utilization unit 30 that would be caused by the instantaneous vaporization of the water droplets AD within the steam utilization unit 30 can be suppressed.

[0043] In this embodiment, the steam generating unit 10, the steam detecting unit 40 including the droplet collecting unit 41, and the steam utilizing unit 30 are configured separately. When the droplet collecting unit 41 is disposed within the steam generating unit 10, the collection temperature of the water droplets AD is lowered (boiling point + α). As a result, water droplets AD that are not vaporized by the droplet collecting unit 41 may accumulate in the droplet collecting unit 41 and block the flow path, which may prevent the generation of water droplets AD from being detected as vapor pressure. Furthermore, if the water droplets AD fall due to their own weight and return to the part of the steam generating unit 10 where water vapor is being generated, this may cause instability in the amount of steam generated. On the other hand, when the droplet collecting unit 41 is disposed within the steam utilizing unit 30, the temperature of the droplet collecting unit 41 becomes higher (≧300°C), and the difference between the wall temperature within the steam utilizing unit 30 and the saturated steam temperature becomes larger (≧200K). As a result, the walls near the high-temperature droplet collection unit 41 are more likely to be covered with water vapor generated by the evaporation of water droplets AD, making it more likely that the Leidenfrost phenomenon, which inhibits the collision of water droplets AD with the wall surface, will occur. In this regard, in this embodiment, the steam detection unit 40 including the droplet collection unit 41 is configured independently from both the steam generation unit 10 and the steam utilization unit 30. This allows the temperature of the droplet collection unit 41 to be adjusted to an appropriate temperature level (120°C to 130°C) separately from the steam generation unit 10 and the steam utilization unit 30. As a result, it is possible to avoid the rebound of water droplets AD due to the formation of a steam film on the wall surface within the steam detection unit 40. It is also possible to suppress instability in the amount of steam generated in the steam generation unit 10. It is also possible to detect water droplets AD that are generated in response to fluctuations in the required steam volume.

[0044] When the droplets AD are vaporized by the droplet collecting unit 41, the pressure rises rapidly due to vapor pressure. If the droplet collecting unit 41 is disposed within the steam generating unit 10, the increased pressure propagates to the pump 70 via the liquid phase in the two-phase flow region as the pressure rises. In this embodiment, the steam detecting unit 40 including the droplet collecting unit 41 and the steam generating unit 10 are configured separately. This creates a gas phase space between the steam generating unit 10 and the steam detecting unit 40, thereby suppressing the influence of pressure propagation to the pump 70. On the other hand, if the droplet collecting unit 41 is disposed within the steam utilizing unit 30, the amount of steam supplied to the steam utilizing unit 30 temporarily increases due to the vaporization of the droplets AD. If the amount of steam supplied becomes unstable due to the vaporization of the droplets AD during load fluctuations in the steam utilizing unit 30, this may cause damage to the steam utilizing unit 30 (for example, electrode deterioration due to insufficient steam volume at a high steam utilization rate, or carbon extrusion during reforming due to insufficient steam volume). In this regard, by configuring the vapor detection unit 40 including the droplet collection unit 41 as an independent unit different from both the vapor generation unit 10 and the vapor utilization unit 30, the spatial volume can mitigate the temporary pressure increase caused by the vaporization of the water droplets AD. Also, the influence of the vaporization of the water droplets AD on the pressure propagation to the vapor generation unit 10, the pump 70, and the vapor utilization unit 30 can be suppressed.

[0045] Second Embodiment 12 is a block diagram of a steam generating device 100a of the second embodiment. The steam generating device 100a of the second embodiment is different from the steam generating device 100 of the first embodiment in that it includes a condenser 80 and a downstream pressure sensor 55 and in the control content of the ECU 90a. Therefore, in the second embodiment, a description of the same configuration and control as in the first embodiment will be omitted, and only the configuration and control different from the first embodiment will be described.

[0046] As shown in FIG. 12, the steam generating device 100a includes a condenser 80 that cools air containing water vapor not used in the steam utilization unit 30 to condense the water, and a downstream pressure sensor 55 that detects the water vapor pressure in the steam detection unit 40. The downstream pressure sensor 55 detects the water vapor pressure (downstream steam pressure) discharged from the steam detection unit 40 downstream of the droplet collection unit 41. The condenser 80 separates the condensed unused water from the condensed air and discharges them to the outside. The unused water is circulated to the pump 70. The upstream pressure sensor 50 and the downstream pressure sensor 55 correspond to pressure acquisition units.

[0047] In the second embodiment, instead of adjusting the supply flow rate Fl in response to a comparison between the upstream water vapor pressure P detected by the upstream pressure sensor 50 and the first pressure Pc, the ECU 90a changes the supply flow rate Fl in response to a pressure difference ΔP between the upstream water vapor pressure P and the downstream water vapor pressure detected by the downstream pressure sensor 55. When the pressure difference ΔP is equal to or greater than a preset second pressure ΔPc, the ECU 90a reduces the supply flow rate Fl to the steam generating section 10. When the pressure difference ΔP is less than the second pressure ΔPc and the steam temperature T1 is equal to or greater than the first temperature Tc1, the ECU 90a increases the supply flow rate Fl to the steam generating section 10. When the pressure difference ΔP is less than the second pressure ΔPc and the steam temperature T1 is less than the first temperature Tc1, the ECU 90a does not change the supply flow rate Fl to the steam generating section 10, but maintains the supply flow rate Fl before the change.

[0048] The ECU 90a of the second embodiment uses the pressure difference ΔP to calculate the amount of water evaporated by the droplet collection unit 41. The ECU 90a uses the calculated amount of water to calculate the supply flow rate Fl after reduction to the steam generation unit 10. When the pressure difference ΔP is equal to or greater than the second pressure ΔPc, the ECU 90a supplies the supply flow rate Fl to the steam generation unit 10 at a rate of change obtained by subtracting the flow rate change rate ΔFl, as in the above embodiment. The pressure difference ΔP is expressed by the following equation (2). Also, the amount of steam passing through the steam detection unit 40 F s is expressed as the following equation (3).

[0049]

number

number

[0050] By removing the flow velocity u from the above formulas (2) and (3), the amount of water vapor F (mmol / s) of the water droplets AD vaporized by the droplet collecting portion 41 is expressed as in the following formula (4).

number

[0051] Regarding the above formula (4), by integrating the amount of water vapor ΔF of water droplets AD vaporizing in a short period as shown in the following formula (5), the supply flow rate ΔF is obtained, which is the decrease in the supply flow rate Fl equal to the amount of water droplets AD vaporizing during the control time Δt. l (t) can be calculated.

number

[0052] In the second embodiment, the mesh opening length (diameter) d of the droplet collecting portion 41 is trp is equal to or less than the average mist diameter d1 of the water droplets AD of the spray flow. trpis set to be equal to or greater than the maximum length d2 calculated from the pressure loss allowable from the steam generating section 10 to the steam utilizing section 30.

[0053] Fig. 13 is an explanatory diagram of the average mist diameter d1. Fig. 13 shows a schematic cross-sectional view of a part of the steam generating unit 10. In the second embodiment, the average mist diameter of the water droplets AD contained in the spray flow is defined as d1, and the steam flow velocity of the water droplets AD is defined as u. s The average mist diameter d1 (m) is calculated using the following empirical formula (6):

[0054]

number

[0055] From the maximum length d2 and the above formula (2), the pressure loss ΔP of the vapor detection unit 40 is calculated. trp is expressed as the following equation (7).

number

[0056] In addition, the pressure loss ΔP of the steam generating section 10 eva and the pressure loss ΔP of the steam utilization section 30 use Using the above, the total pressure loss ΔP from the steam generating section 10 to the steam utilizing section 30 is sup is expressed as the following equation (8).

number

[0057] In the above formula (8), the total pressure loss ΔP sup is set as the allowable pressure loss, the opening length d trp In other words, in the second embodiment, the opening length d of the mesh that is the droplet collecting portion 41 is equal to or less than the maximum length d2 calculated from the above formula (7). trp is set to be equal to or smaller than the average mist diameter d1 calculated by the above formula (6) and equal to or larger than the maximum length d2 calculated by the above formula (7).

[0058] Fig. 14 is a flowchart of the water vapor generation method of the second embodiment. The processes of steps S11 to S12 and steps S18 to S21 in the water vapor generation flow shown in Fig. 14 are the same as the processes of steps S1 to S2 and steps S6 to S9 in the water vapor generation flow (Fig. 9) of the first embodiment. Therefore, the processes of steps S13 to S17 in the water vapor generation flow shown in Fig. 14 that differ from the first embodiment will be described.

[0059] 14, when the flow rate adjusting unit 20 is controlled to supply water to the steam generating unit 10 (step S12), the ECU 90a acquires the steam temperature T1, the upstream water vapor pressure P detected by the upstream pressure sensor 50, and the downstream water vapor pressure detected by the downstream pressure sensor 55 (step S13). The ECU 90a calculates the pressure difference ΔP by subtracting the downstream water vapor pressure from the upstream water vapor pressure P (step S14).

[0060] The ECU 90a determines whether the calculated pressure difference ΔP is equal to or greater than the second pressure ΔPc (step S15). If it is determined that the pressure difference ΔP is equal to or greater than the second pressure ΔPc (step S15: YES), the ECU 90a calculates the supply flow rate ΔF supplied to the steam generating unit 10 using the above formula (5). l The ECU 90a controls the flow rate adjusting unit 20 to calculate the calculated supply flow rate ΔF from the supply flow rate Fl (step S16). lThe supply flow rate Fl at a rate of change obtained by reducing the flow rate change rate ΔFl obtained by dividing (t) by the control time is supplied to the steam generating unit 10, and the processing from step S13 onwards is performed again.

[0061] As described above, in the second embodiment, the upstream pressure sensor 50 detects the water vapor pressure P supplied from the steam generating unit 10 to the steam detecting unit 40 upstream of the liquid droplet collecting unit 41. The downstream pressure sensor 55 detects the water vapor pressure (downstream steam pressure) discharged from the steam detecting unit 40 downstream of the liquid droplet collecting unit 41. Instead of adjusting the supply flow rate Fl in accordance with a comparison between the upstream water vapor pressure P detected by the upstream pressure sensor 50 and the first pressure Pc, the ECU 90a changes the supply flow rate Fl in accordance with the pressure difference ΔP between the upstream water vapor pressure P and the downstream water vapor pressure detected by the downstream pressure sensor 55. When the pressure difference ΔP is equal to or greater than a preset second pressure ΔPc, the ECU 90a reduces the supply flow rate Fl supplied to the steam generating unit 10. Therefore, in the steam generating device 100a of the second embodiment, the flow rate of water supplied to the steam generating unit 10 is increased or decreased using a pressure difference ΔP obtained by subtracting the water vapor pressure downstream of the droplet collecting unit 41 from the water vapor pressure P upstream of the droplet collecting unit 41, instead of the water vapor pressure P upstream of the droplet collecting unit 41. The upstream water vapor pressure P and the downstream water vapor pressure change depending on the state (e.g., back pressure) of the steam utilizing unit 30 connected downstream of the steam detecting unit 40. In the second embodiment, the supply flow rate Fl to the steam generating unit 10 is controlled depending on the pressure difference ΔP, which is not affected by the steam utilizing unit 30. As a result, the expansion rate of the two-phase region in the steam generating unit 10 can be further suppressed, and the generation of water droplets AD due to an increase in the degree of superheat on the heat transfer surface can be suppressed. Furthermore, the ability of the steam utilizing unit 30 to follow the required steam volume can be further improved while maintaining the gas phase region in the steam generating unit 10.

[0062] Furthermore, the ECU 90a of the second embodiment calculates the amount of water evaporated by the droplet collection unit 41 using the pressure difference ΔP. The ECU 90a uses the calculated amount of water to calculate the reduced supply flow rate Fl of water to be supplied to the steam generation unit 10. Therefore, in the second embodiment, the amount of water droplets AD that flow into the steam detection unit 40 as water droplets AD without being vaporized in the steam generation unit 10 and are vaporized by the droplet collection unit 41 is calculated. In the second embodiment, water whose flow rate has been reduced to correspond to the calculated amount of water droplets AD is supplied to the steam generation unit 10, so the amount of water droplets AD discharged from the steam generation unit 10 can be suppressed.

[0063] The length (diameter) d of the mesh opening of the droplet collecting portion 41 of the second embodiment trp is equal to or less than the average mist diameter d1 of the water droplets AD of the spray flow. trp is set to be equal to or greater than the maximum length d2 calculated from the pressure loss allowable from the steam generating section 10 to the steam utilizing section 30. Therefore, in the second embodiment, the mesh opening length d trp is less than the average mist diameter d1 of the spray, the water droplets AD of the spray come into contact with the mesh and evaporate. trp is the allowable pressure loss ΔP from the steam generating section 10 to the steam utilizing section 30 sup Since the length is equal to or longer than the maximum length d2 calculated from the above, the pressure loss ΔP trp is an allowable numerical value. As a result, in the second embodiment, the liquid droplet collecting section 41 is formed within the vapor detecting section 40 within a range in which the pressure loss is equal to or less than the allowable design value and in which the water droplets AD in the spray flow evaporate.

[0064] Third Embodiment 15 is a block diagram of a steam generating device 100b of the third embodiment. The steam generating device 100b of the third embodiment differs from the steam generating device 100 of the first embodiment in that it includes a collection section temperature sensor (collection section temperature acquisition section) 50b instead of the upstream pressure sensor 50. Therefore, in the third embodiment, a description of the same configuration and control as in the first embodiment will be omitted, and only configurations and controls different from those in the first embodiment will be described.

[0065] 15 detects a trapping section temperature T2, which is the temperature of the droplet trapping section 41. In the third embodiment, an ECU 90b changes the supply flow rate Fl to the steam generating section 10 using the trapping section temperature T2 and a steam temperature T1 detected by a steam temperature sensor 60. The ECU 90b reduces the supply flow rate Fl to the steam generating section 10 when the trapping section temperature T2 is equal to or lower than a preset second temperature Tc2. The ECU 90b increases the supply flow rate Fl to the steam generating section 10 when the trapping section temperature T2 exceeds the second temperature Tc2 and the steam temperature T1 detected by the steam temperature sensor 60 is equal to or higher than a first temperature Tc1. When the trapping section temperature T2 exceeds the second temperature Tc2 and the steam temperature T1 is lower than the first temperature Tc1, the ECU 90b does not change the supply flow rate Fl to the steam generating section 10, but maintains the supply flow rate Fl before the change. The supply flow rate Fl and the flow rate change rate ΔFl to be increased or decreased are the same as those in the first embodiment.

[0066] Fig. 16 is a flowchart of the water vapor generation method of the third embodiment. The processes of steps S31 to S32 and steps S35 to S39 in the water vapor generation flow shown in Fig. 16 are the same as the processes of steps S1 to S2 and steps S6 to 9 in the water vapor generation flow (Fig. 9) of the first embodiment, respectively. Therefore, the processes of steps S33 to S34 in the water vapor generation flow shown in Fig. 16 that differ from the first embodiment will be described.

[0067] 16, when the flow rate adjusting unit 20 is controlled to supply water to the steam generating unit 10 (step S32), the ECU 90b acquires the collection unit temperature T2 of the droplet collecting unit 41 and the steam temperature T1 (step S33). The ECU 90b determines whether the detected collection unit temperature T2 is equal to or lower than the second temperature Tc2 (step S34). If it is determined that the collection unit temperature T2 is equal to or lower than the second temperature Tc2 (step S34: YES), the ECU 90b supplies the supply flow rate Fl to the steam generating unit 10 at a rate of change obtained by subtracting the flow rate change rate ΔFl calculated by the above formula (1) from the rate of change of the supply flow rate Fl of the steam generating unit 10 (step S35), and the processing from step S33 onwards is performed again.

[0068] FIG. 17 is an explanatory diagram of the change over time in the steam generation rate Fg when the required steam rate increases. FIG. 17 also shows the change over time in the trapping unit temperature T2 when the required steam rate Fs,t changes, as in FIGS. 10 and 11 . As shown in FIG. 17 , when the supply flow rate Fl to the steam generating unit 10 increases after time T0, the two-phase region expands in the steam generating unit 10, and unvaporized water droplets AD may be generated in the steam generating unit 10. When water vapor containing water droplets AD flows into the steam detecting unit 40, the water droplets AD come into contact with the droplet collecting unit 41 and vaporize. As a result, as shown in region AR3 in FIG. 17 , the vaporization of the water droplets AD causes an instantaneous drop in the trapping unit temperature T2. In the third embodiment, when the trapping unit temperature T2 is equal to or lower than the second temperature Tc2, the ECU 90b reduces the supply flow rate Fl supplied to the steam generating unit 10 to a value lower than the supply flow rate Fl determined from the required steam rate Fs,t. As a result, as shown in area AR3 in Fig. 17, the rate of increase of the supply flow rate Fl temporarily decreases, and the collection part temperature T2 is maintained higher than the second temperature Tc2. That is, the evaporation of the water droplets AD in the droplet collection part 41 is suppressed.

[0069] As described above, the collector temperature sensor 50b of the third embodiment detects the temperature of the droplet collector 41. The ECU 90b changes the supply flow rate Fl to the steam generating section 10 using the detected collector temperature T2 of the droplet collector 41 and the vapor temperature T1. The ECU 90b reduces the supply flow rate Fl to the steam generating section 10 when the collector temperature T2 is equal to or lower than a preset second temperature Tc2. The ECU 90b also increases the supply flow rate Fl to the steam generating section 10 when the collector temperature T2 exceeds the second temperature Tc2 and the vapor temperature T1 is equal to or higher than the first temperature Tc1. When the collector temperature T2 exceeds the second temperature Tc2 and the detected vapor temperature T1 is lower than the first temperature Tc1, the ECU 90b does not change the supply flow rate Fl to the steam generating section 10, but maintains the supply flow rate Fl before the change. Therefore, in the third embodiment, water droplets AD contained in the water vapor that flows into the steam detection unit 40 are vaporized into water vapor by the droplet collection unit 41. As a result, the amount of water droplets AD in the water vapor is reduced when the water vapor generated in the steam generation unit 10 passes through the steam detection unit 40. This suppresses the generation of water droplets AD in the water vapor supplied to the steam utilization unit 30, thereby suppressing damage to the steam utilization unit 30 due to the instantaneous evaporation of water droplets AD contained in the water vapor. Furthermore, the temperature of the droplet collection unit 41 decreases as the droplet collection unit 41 evaporates the water droplets AD contained in the water vapor. When the collection unit temperature T2 detected by the collection unit temperature sensor 50b is equal to or lower than the second temperature Tc2, the supply flow rate Fl supplied to the steam generation unit 10 is reduced. In this case, the reduction in the supply flow rate Fl to the steam generation unit 10 reduces the amount of water droplets AD discharged from the steam generation unit 10, stabilizing the flow rate of water vapor generated by the steam generation unit 10. Furthermore, when the collection unit temperature T2 exceeds the second temperature Tc2 and the steam temperature T1 in the steam detection unit 40 is equal to or higher than the first temperature Tc1, the supply flow rate Fl to the steam generation unit 10 increases. This allows water vapor at or above the saturation temperature to be discharged from the steam generation unit 10 while maintaining a gas phase region in the steam generation unit 10. As a result, the ability of the steam utilization unit 30 to follow the required steam volume Fs,t can be improved.

[0070] <Modifications of the above embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0071] <Variation 1> In the first to third embodiments described above, examples of the steam generating devices 100, 100a, and 100b were described. However, the steam generating device can be modified within a range in which the supply flow rate Fl to the steam generating unit 10 can be increased or decreased using any one of the water vapor pressure P, the pressure difference ΔP, and the collection unit temperature T2. The medium that the steam generating unit 10 changes from a liquid to a gas is not limited to water; any known substance can be used. While the steam generating device 100 includes the pump 70 and the steam utilization unit 30, at least one of the pump 70 and the steam utilization unit 30 may be omitted. In this case, the steam generating device of the modified example may receive liquid from another device or may supply steam discharged from the steam detection unit 40 to another device. The steam utilization unit 30 may be a device that utilizes water vapor other than an SOEC. As shown in FIG. 1 , the steam utilization unit 30 is disposed in the pipe connecting the steam generating unit 10 and the steam detection unit 40. However, for example, the steam utilization unit 30 may be disposed upstream of the droplet collection unit 41 within the steam detection unit 40.

[0072] In the first embodiment, the ECU 90 increases or decreases the supply flow rate Fl to the vapor detection unit 40 by controlling the rate of change using the flow rate change rate ΔFl. However, the method of increasing or decreasing the supply flow rate Fl can be modified. For example, when the water vapor pressure P is equal to or greater than the first pressure Pc, the ECU 90 may decrease the supply flow rate Fl by a predetermined amount from the current supply flow rate Fl. The temperature of the vapor detection unit 40 in the first embodiment is 120°C or higher and 130°C or lower, but may be lower than 120°C or higher than 130°C. The temperature of the steam utilization unit 30 in the first embodiment is 300°C or higher, but may be lower than 300°C. The temperature of the vapor detection unit is preferably higher than the temperature of the steam generation unit. Furthermore, the temperature of the steam utilization unit is preferably higher than the temperature of the vapor detection unit. In this case, if the steam utilization unit is defined as a high-temperature unit, the vapor detection unit can be rephrased as a medium-temperature unit that is lower in temperature than the high-temperature unit and higher in temperature than the steam generation unit.

[0073] <Variation 2> The ECU 90a of the second embodiment calculates the supply flow rate ΔF calculated by the above equations (2) to (5) in accordance with the pressure difference ΔP and the steam temperature T. l However, the supply flow rate Fl to the steam generating unit 10 may be increased or decreased using a flow rate determined by other methods. For example, the ECU 90a may control the supply flow rate Fl using the flow rate change rate ΔFl, as in the first embodiment.

[0074] The droplet collecting portion 41 of the second embodiment has a length d trp In the above example, the mesh is formed with multiple squares each having a square shape, but the diameter can be deformed within a range that allows droplets to evaporate and pass through. The droplet collection unit may be a mesh with openings (or through holes) other than a square, or a material other than a mesh. For example, if the openings are rectangular, the average value of the longitudinal diameter and the lateral diameter can be used as the opening length. For example, if the openings are diamond-shaped, the average value of the two diagonals can be used as the opening length. For example, if the openings are hexagonal, the length of the diagonal can be used as the opening length. For example, if the openings are circular, the inner diameter of the circle can be used as the opening length. The droplet collection unit may be selected depending on the material of the medium passing through the vapor detection unit 40. The droplet collection unit is arranged perpendicular to the flow direction as described above, but can be deformed within a range that allows droplets to be collected. The droplet collection unit may be a plurality of different meshes arranged within the vapor detection unit 40.

[0075] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate. [Explanation of symbols]

[0076] 10...Steam generating section 11...Wall surface of steam generating section 20...Flow rate adjusting unit (flow rate control unit) 30...Steam utilization section 40...Vapor detection unit 41...Droplet collection section 50...Upstream pressure sensor (pressure acquisition unit) 50b...Collection unit temperature sensor (collection unit temperature acquisition unit) 55...Downstream pressure sensor (pressure acquisition unit) 60...Steam temperature sensor (steam temperature acquisition unit) 70...Pump 80...Condenser 100, 100a, 100b...Steam generating device AD…Water droplets AR1,AR2,AR3…area d1...Average mist diameter d2: Maximum length calculated from pressure loss d trp …Opening length (diameter) F…Flow rate ΔFl...Flow rate change rate Fl,ΔF l (t)…supply flow rate Fs,t…Required steam amount P...Water vapor pressure (upstream vapor pressure) ΔP…Pressure difference Pc...First pressure T1: Steam temperature T2…Collection part temperature Tc1…1st temperature Tc2…Second temperature WT…Liquid film Δt: Control time

Claims

1. 1. A steam generating device comprising: a steam generating unit that generates steam by heating a liquid; a flow rate control unit that adjusts the flow rate of the liquid supplied to the vapor generating unit; a vapor detection unit having a droplet collection unit that collects and evaporates droplets in the vapor supplied from the vapor generation unit, the vapor detection unit discharging the vapor that has passed through the droplet collection unit; a pressure acquisition unit that acquires an upstream vapor pressure, which is a vapor pressure supplied from the vapor generation unit to the vapor detection unit, at a position upstream of the droplet collection unit; a steam temperature acquisition unit that acquires the temperature of the steam in the steam detection unit; Equipped with The flow rate control unit When the upstream vapor pressure is equal to or higher than a predetermined first pressure, a flow rate of the liquid supplied to the vapor generating unit is reduced; increasing a flow rate of the liquid supplied to the vapor generating unit when the upstream vapor pressure is lower than the first pressure and the temperature acquired by the vapor temperature acquiring unit is equal to or higher than a predetermined first temperature; A steam generating device that does not change the flow rate of liquid supplied to the steam generating unit when the upstream steam pressure is less than the first pressure and the temperature acquired by the steam temperature acquisition unit is less than the first temperature.

2. 10. The steam generating device according to claim 1, The pressure acquisition unit an upstream pressure acquisition unit that acquires the upstream steam pressure; a downstream pressure acquisition unit that acquires a downstream vapor pressure, which is the pressure of vapor discharged from the vapor detection unit, downstream of the droplet collection unit; and Instead of adjusting the flow rate of the liquid in accordance with the comparison between the upstream vapor pressure and the first pressure, the flow rate control unit: reducing a flow rate of the liquid supplied to the vapor generating unit when a pressure difference obtained by subtracting the downstream vapor pressure from the upstream vapor pressure is equal to or greater than a predetermined second pressure; increasing a flow rate of the liquid supplied to the steam generating unit when the pressure difference is less than the second pressure and the temperature acquired by the steam temperature acquisition unit is equal to or higher than the first temperature; A steam generating device that does not change the flow rate of the liquid supplied to the steam generating unit when the pressure difference is less than the second pressure and the temperature acquired by the steam temperature acquisition unit is less than the first temperature.

3. 3. The steam generating device according to claim 2, The flow rate control unit Calculating the amount of droplets evaporated by the droplet collector using the pressure difference; The vapor generating device calculates the reduced flow rate of the liquid to be supplied to the vapor generating section using the calculated amount of droplets.

4. 1. A steam generating device comprising: a steam generating unit that generates steam by heating a liquid; a flow rate control unit that adjusts the flow rate of the liquid supplied to the vapor generating unit; a vapor detection unit having a droplet collection unit that collects and evaporates droplets in the vapor supplied from the vapor generation unit, the vapor detection unit discharging the vapor that has passed through the droplet collection unit; a steam temperature acquisition unit that acquires the temperature of the steam in the steam detection unit; a collecting unit temperature acquisition unit that acquires the temperature of the droplet collecting unit; Equipped with The flow rate control unit When the temperature acquired by the collection unit temperature acquisition unit is equal to or lower than a preset second temperature, a flow rate of the liquid supplied to the vapor generation unit is reduced; increasing a flow rate of the liquid supplied to the vapor generating unit when the temperature acquired by the collection unit temperature acquisition unit exceeds the second temperature and the temperature acquired by the vapor temperature acquisition unit is equal to or higher than a predetermined first temperature; A steam generating device that does not change the flow rate of liquid supplied to the steam generating section when the temperature acquired by the collection section temperature acquisition section exceeds the second temperature and the temperature acquired by the steam temperature acquisition section is less than the first temperature.

5. The steam generating device according to any one of claims 1 to 4, further comprising: a steam utilization unit disposed downstream of the steam detection unit, the steam generating unit is supplied with liquid water and generates steam; The steam utilization unit generates hydrogen using water vapor discharged from the steam detection unit at a higher temperature than the steam detection unit.

6. 6. The steam generating device according to claim 5, the droplet collecting section is a mesh having a plurality of openings and arranged so as to intersect with the direction of vapor flow in the vapor detecting section, A steam generating device, wherein the length of the opening is equal to or less than the average mist diameter of the spray flow and equal to or greater than the maximum length calculated from the allowable pressure loss from the steam generating section to the steam utilizing section.

7. 1. A method for generating steam, comprising: a steam generating step in which the steam generating unit generates steam by heating the liquid; a flow rate control step of adjusting the flow rate of the liquid supplied to the vapor generating unit; a vapor detection step of discharging the vapor that has passed through a droplet collection unit that collects and evaporates droplets in the vapor supplied from the vapor generation unit; a pressure acquiring step of acquiring an upstream steam pressure, which is a steam pressure supplied from the steam generating unit to the droplet collecting unit, on the upstream side of the droplet collecting unit; a steam temperature acquisition step of acquiring a temperature of the steam supplied to the droplet collecting unit; Equipped with The flow rate control step includes: When the upstream vapor pressure is equal to or higher than a predetermined first pressure, a flow rate of the liquid supplied to the vapor generating unit is reduced; increasing a flow rate of the liquid supplied to the vapor generating unit when the upstream vapor pressure is lower than the first pressure and the temperature acquired in the vapor temperature acquisition step is equal to or higher than a predetermined first temperature; a flow rate of the liquid supplied to the steam generating section is not changed when the upstream steam pressure is less than the first pressure and the temperature acquired by the steam temperature acquisition process is less than the first temperature.

8. 1. A method for generating steam, comprising: a steam generating step in which the steam generating unit generates steam by heating the liquid; a flow rate control step of adjusting the flow rate of the liquid supplied to the vapor generating unit; a vapor detection step of discharging the vapor that has passed through a droplet collection unit that collects and evaporates droplets in the vapor supplied from the vapor generation unit; a steam temperature acquisition step of acquiring a temperature of the steam supplied to the droplet collecting unit; a collecting unit temperature acquisition step of acquiring the temperature of the droplet collecting unit; Equipped with The flow rate control step includes: When the temperature acquired in the collecting unit temperature acquisition step is equal to or lower than a predetermined second temperature, a flow rate of the liquid supplied to the vapor generating unit is reduced; increasing a flow rate of the liquid supplied to the vapor generating section when the temperature acquired in the collecting section temperature acquiring step exceeds the second temperature and the temperature acquired in the vapor temperature acquiring step is equal to or higher than a predetermined first temperature; A steam generation method in which the flow rate of the liquid supplied to the steam generation section is not changed when the temperature acquired in the collection section temperature acquisition process exceeds the second temperature and the temperature acquired in the steam temperature acquisition process is less than the first temperature.

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