JP5217414B2 - Evaporator - Google Patents

Description

  The present invention relates to an evaporator.

Generally, an evaporator that heats a pipe through which a fluid to be heated flows is known (for example, see Patent Document 1).
JP-A-6-249450

  An object of the present invention is to provide an evaporator suitable for a heat source having a relatively low temperature level.

  According to an aspect of the present invention, there is provided a chamber, a pipe disposed in the chamber, through which a first fluid having heat flows, and a mechanism for supplying a second fluid to an outer surface of the pipe, and at least a part of the pipe And the mechanism in which the supply amount of the second fluid varies in the axial direction of the tube in the region.

  According to this aspect, the supply amount of the second fluid per unit length of the pipe is optimized over the entire pipe along the axial direction of the pipe, and as a result, the heat utilization efficiency is improved. Since the second fluid, which is the medium to be heated, flows outside the pipe, it is relatively easy to partially adjust the flow rate of the second fluid along the axial direction of the pipe. These provide an evaporator suitable for a heat source at a relatively low temperature level.

  Embodiments of the present invention will be described below with reference to the drawings. The X and Y axes attached to the drawings are two orthogonal axes in the horizontal plane, and the Z axis indicates the direction of gravity.

  FIG. 1 is a schematic cross-sectional view showing the evaporator 10. As shown in FIG. 1, the evaporator 10 includes a chamber 20, a heat exchange tube 40, and a spray mechanism 60. In the present embodiment, the evaporator 10 can include other elements such as a mist separator 80 as necessary. In the present embodiment, the medium to be heated is water.

  In the present embodiment, a supply source (heat source) (not shown) that supplies a fluid having heat is fluidly connected to the tube 40. In the present embodiment, the chamber 20 is fluidly connected to a water source (not shown). The spray mechanism 60 sprays water toward the tube 40. In other embodiments, the spray mechanism 60 can be fluidly connected directly to a source of water.

  In the evaporator 10, a fluid having heat flows through the tube 40, and water from the spray mechanism 60 is supplied to the outer surface of the tube 40. Through the tube 40, the heat of the thermal fluid is transferred to the water attached to the outer surface of the tube 40. On the outer surface of the tube 40, the heated water evaporates. That is, water evaporates outside the tube 40 in the internal space of the chamber 20. For example, the steam is discharged from an opening 22 provided in the chamber 20.

  The evaporator 10 having such a configuration can widen the water-steam interface as compared with a mode in which the medium to be heated (water) flows in the pipe. This is advantageous for evaporation processes using relatively low temperature level heat sources.

  Moreover, the evaporator 10 of such a form has the advantage that the pressure loss with respect to the flow of water or steam is small. By suppressing the change in the evaporation temperature caused by the pressure loss on the water side, the concern about the pinch temperature is suppressed, and the stability of the evaporation process is improved.

  Further, in the evaporator 10, since the medium to be heated (water) flows outside the tube 40, clogging due to the scale generated on the water side is unlikely to occur.

  The internal space of the chamber 20 can be made equal to the atmospheric pressure, which is advantageous for reducing the thickness and weight of the chamber 20. In the present embodiment, the internal pressure of the chamber 20 is, for example, about 0.1 MPa (1 atm). In the present embodiment, the internal pressure of the chamber 20 can be higher or lower than the atmospheric pressure. In the case of a negative pressure, the internal pressure can be, for example, about 0.09, 0.08, 0.07, or 0.06 MPa or less. In the case of high pressure, the internal pressure can be, for example, about 0.12, 0.14, 0.16, 0.2, 0.4, 0.8, 1.0, or 2.0 MPa or more.

  The outer shape of the chamber 20 can have a general cylindrical shape with rounded corners as needed. In the present embodiment, the axial direction of the cylindrical chamber 20 substantially coincides with the gravitational direction (Z direction). By providing the circumferential surface of the chamber 20 with corrugations or irregularities extending in the circumferential direction, the chamber 20 having a high pressure resistance can be formed using a relatively thin material. The chamber 20 formed of a thin material is advantageous for reducing the apparatus cost. For example, the thickness of the constituent member of the chamber 20 is 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, or 1 mm or less. In other embodiments, the cross-sectional shape of the chamber 20 can have a circular shape, an elliptical shape, a rectangular shape, or other shapes.

  The tubes 40 are arranged in a multistage layer in the chamber 20 along the axial direction (gravity direction) of the chamber 20. Header pipes 42 and 44 are provided in the chamber 20. The header pipes 42, 44 have a cylindrical shape extending along the axial direction of the chamber 20 and are spaced apart from each other.

  One end of the tube 40 of each layer is fluidly connected to the first header pipe 42, and the other end of the tube 40 of each layer is fluidly connected to the second header pipe 44. The high-temperature hot fluid supplied to the first header pipe 42 branches and flows through the tubes 40 of each layer. The thermal fluid from the tube 40 joins at the second header pipe 44. As a constituent member of the tube 40, a metal tube (for example, a copper tube or an aluminum tube) having a high thermal conductivity is preferably used.

  Further, the tube 40 includes a raw tube having a smooth surface, a netted tube having a net-like member disposed on the surface, a grooved tube having a large number of grooves formed on the surface, and a fin having a large number of fins provided on the surface. Any of the tubes may be used. By providing the nets, grooves, fins, and the like on the surface of the tube 40, the surface area of the tube 40 is increased and heat exchange is promoted. Further, the surface of the tube 40 may be subjected to a treatment suitable for heat exchange. At least a part of the surface of the tube 40 may be subjected to lyophilic treatment or lyophobic treatment. For example, the upper region of the surface of the tube 40 may be lyophilic and the lower region may be liquid repellent.

  2A, 2B, 2C, and 2D are plan views schematically showing a configuration example of the tube 40. FIG. 2A to 2D, the plane including the X direction and the Y direction (XY plane) substantially coincides with the horizontal plane.

  In FIG. 2A, the tube 40 has a plurality of line elements 51 extending along the X direction and aligned with each other along the Y direction, and a bending element 53 that fluidly connects the line elements 51 to each other. The line elements 51 may be substantially parallel to each other or non-parallel to each other. In FIG. 2A, the chamber 20 has a rectangular cross-sectional shape. The first header pipe 42 is disposed adjacent to one corner in the chamber 20. The second header pipe 44 is disposed adjacent to another corner in the chamber 20 that faces the corner adjacent to the first header pipe 42. For example, a tube having the line element 51 and the bending element 53 can be formed by using a bending process or a welding process. In each layer in the direction of gravity (Z direction), the tube 40 can have a similar shape.

  In FIG. 2B, the chamber 20 has a circular cross-sectional shape. Similar to FIG. 2A, the tube 40 includes a plurality of line elements 55 that extend along the X direction and are aligned with each other along the Y direction, and a bending element 57 that fluidly connects the line elements 51 to each other. The line elements 51 may be substantially parallel to each other or non-parallel to each other. The first header pipe 42 is disposed adjacent to the inner peripheral surface of the chamber 20. The second header pipe 44 is disposed at a position facing the first header pipe 42 and adjacent to the inner peripheral surface of the chamber 20. For example, a tube having the line element 55 and the bending element 57 can be formed by using a bending process or a welding process. In FIG. 2B, the line connecting the first header pipe 42 and the second header pipe 44 intersects the axis of the line element 55 of the tube 40. The bending element 57 of the tube 40 is disposed adjacent to the inner peripheral surface of the chamber 20. In each layer in the direction of gravity (Z direction), the tube 40 can have a similar shape.

  In FIG. 2C, the chamber 20 has a circular cross-sectional shape. The tube 40 has a curved element 59 extending in a spiral shape. The center of the spiral of the bending element 59 can generally coincide with the axis of the chamber 20. In other words, the elements of the tube 40 are arranged concentrically along the radial direction of the chamber 20. For example, the tube having the bending element 59 can be formed by using a bending process or a welding process. The first header pipe 42 is disposed near the axial center of the chamber 20. The second header pipe 44 is disposed adjacent to the inner peripheral surface of the chamber 20. In each layer in the direction of gravity (Z direction), the tube 40 can have a similar shape.

  In FIG. 2D, the tube 40 has a plurality of horizontal groups 40A and 40B arranged in the horizontal direction and through which water flows. Each horizontal group 40A, 40B has a plurality of line elements 51 that extend along the X direction and are lined up along the Y direction, and a bending element 53 that fluidly connects the line elements 51 to each other. The line elements 51 may be substantially parallel to each other or non-parallel to each other. In FIG. 2D, the chamber 20 has a rectangular cross-sectional shape. For example, a tube having the line element 51 and the bending element 53 can be formed by using a bending process or a welding process.

  Part of the thermal fluid from the first header pipe 42 flows through the horizontal group 40 </ b> A toward the second header pipe 44. Another part of the thermal fluid from the first header pipe 42 flows through the horizontal group 40 </ b> B toward the second header pipe 44. In a certain layer, since the flow path of the tube 40 is divided into a plurality of horizontal groups 40A and 40B, the axial length of the tube 40 from the first header pipe 42 to the second header pipe 44 within a predetermined region, that is, The heat exchange length can be made relatively short. Thereby, the temperature fall of the thermal fluid in the downstream area | region of the tube 40 in the case where the temperature of the thermal fluid which flows through the tube 40 changes with heat dissipation is suppressed. This is advantageous for suppressing a decrease in heat transfer in the downstream region of the tube 40.

  The plurality of horizontal groups of the tubes 40 may be arranged along any of the X direction, the Y direction, and the tilt direction. In other embodiments, the plurality of horizontal groups can be aligned along both the X and Y directions. The number of horizontal groups 40A and 40B is not limited to two. The number of horizontal groups can be 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more. Further, the horizontal groups 40A and 40B are not limited to the form shown in FIG. 2D, and various forms are applicable.

  In FIG. 2D, the tube 40 can have a similar shape in each layer in the gravitational direction (Z direction). The division | segmentation form of the tube 40 may differ between several layers of the tube 40. FIG. Alternatively, the tube 40 can have both a layer having a flow path divided into a plurality of horizontal groups and a non-divided layer.

  2A to 2D, at least a part of the tube 40 belonging to the next layer is located immediately below the tube 40 belonging to the highest layer. Similarly, the tubes 40 overlap at least partially between other two adjacent layers. In the present embodiment, almost all of the tubes 40 belonging to the next layer are located directly below the tubes 40 belonging to the higher layer. In other embodiments, a portion of the tube 40 can be offset from the position directly below it. That is, the arrangement position of the entire tube 40 (arrangement position of the line elements 51) may be substantially the same between two adjacent layers, or may be partially mismatched.

  The configuration of the tube 40 shown in FIGS. 2A to 2D is an example, and other configurations can be applied.

  Returning to FIG. 1, in the present embodiment, the number of layers of the tube 40 is set according to the device specifications. The number of layers can be 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more. Alternatively, the number of layers can be 15, 20, 25, 30, 35, 40, 45, or 50 or more.

  As shown in FIG. 1, the spray mechanism 60 includes a pump 62, a spray pipe 66 having a plurality of nozzles 64, and a supply pipe 68 that fluidly connects the pump 62 and the pipe 66. The pump 62 pumps up the water stored in the chamber 20 and sends the water to the spray pipe 66 through the supply pipe 68. Water comes out of the nozzle 64 of the pipe 66. Water dropped from the nozzle 64 of the pipe 66 adheres to the surface (outer surface) of the tube 40. The heat of the hot fluid in the tube 40 is transferred to the water attached to the surface of the tube 40, and a part of the water is evaporated in the chamber 20.

  The nozzle 64 may be a spray nozzle or a liquid column nozzle (for example, a hole). In the spray type, water can be spread over a relatively wide range. The liquid column type has an advantage that adjustment of the liquid column (adjustment of the diameter, flow rate, spatial density, etc. of the liquid column) is easy. A nozzle other than the spray type and the liquid column type may be used. A plurality of types of nozzles may be combined.

  The sprinkling pipe 66 includes an upper pipe 66A that supplies water toward the tube 40 belonging to the highest layer and intermediate pipes 66B, 66C, 66D,... That supply water toward the tube 40 belonging to another layer. .. and.

  In the present embodiment, water is supplied from the upper pipe 66A toward the outer surface of the tube 40 belonging to the uppermost layer. The remaining water evaporated in the uppermost tube 40 falls and adheres to the outer surface of the next tube 40. In addition to the water from the uppermost tube 40, water is supplied from the intermediate pipe 66B toward the outer surface of the tube 40 belonging to the next layer. Similarly, the water from the upper tube 40 and the water from the intermediate pipes 66C, 66D,... Are supplied to the outer surfaces of the tubes 40 belonging to the remaining layers.

  If the film thickness of water present on the outer surface of the tube 40 is smaller than the appropriate value, a portion that is not wetted on the outer surface of the tube 40 may occur. If the water film thickness is larger than the appropriate value, water may not easily evaporate from the outer surface of the tube 40. These are disadvantageous in terms of thermal efficiency. Proper spraying of water from the spray mechanism 60 results in high heat transfer and efficient steam generation.

  In this embodiment, the amount of water on the outer surface of the tube 40 in each layer is optimized by replenishing water from the intermediate pipes 66B, 66C, 66D,. The amount of water supplied from the intermediate pipes 66B, 66C, 66D,... To the tubes 40 belonging to the lower layer is set according to the amount of water evaporated from the outer surface of the tube 40 belonging to the higher layer. . For example, a certain amount of water is supplied from an intermediate pipe 66B, 66C, 66D,... To a certain middle layer tube 40 as compared with the amount of water evaporated in the upper layer tube 40. The As a result, partial thirst on the outer surface of the tube 40 is prevented. The water preferably evaporates on the outer surface of each layer of tube 40 supplied with the appropriate amount of water.

  In the present embodiment, one intermediate pipe 66B, 66C, 66D,... Is arranged for the two layers of the tube 40. That is, for every two layers of the tube 40, the intermediate pipes 66B, 66C, 66D,... Are arranged in the space between the layers. In other embodiments, intermediate piping can be placed in each space between the layers of tubes 40.

  Further, the spray pipe 66 (upper pipe 66A, intermediate pipes 66B, 66C, 66D,...) May be disposed away from the tube 40, or may be close to or in close contact with the tube 40. Since the sprinkling pipe 66 and the tube 40 have a tying structure and / or a close-contact structure, the nozzle 64 of the sprinkling pipe 66 is surely disposed immediately above the tube 40, and the nozzle 64 of the sprinkling pipe 66. Water adheres securely to the surface (outer surface) of the tube 40.

  FIG. 3 is a schematic diagram showing an example of the arrangement of the nozzles 64, and shows the positions of the nozzles 64 in a two-dimensional plane (horizontal plane). In FIG. 3, the nozzles 64 face the tube 40 and are spaced apart from each other. Each nozzle 64 can be located directly above any portion of the tube 40. Such an arrangement of the nozzle 64 ensures that the water from the pipe 66 falls onto the tube 40. It is preferable that as many nozzles 64 as possible be arranged at positions directly above the tube 40, but some of the nozzles 64 may be offset from positions directly above the tube 40.

  In the present embodiment, the spray mechanism 60 has a configuration in which the amount of water supply varies (different) in the axial direction of the tube 40 in at least a partial region of the tube 40. That is, the amount of water supplied from the spray mechanism 60 varies along the flow direction of the thermal fluid flowing through the tube 40 with respect to at least a part of the region of the tube 40. In this embodiment, the supply amount of water is relatively large in the upstream portion of the tube 40, and the supply amount of water is relatively small in the downstream portion of the tube 40.

  As shown in FIG. 3, the arrangement pitch of the nozzles 64 varies in the axial direction of the tube 40. Specifically, the nozzles 64 (water outlets) arranged on the upstream side of the thermal fluid in the tube 40 (portions close to the first header pipe 42) have a relatively narrow arrangement pitch, and the downstream side ( The nozzles 64 (water outlets) arranged in the portion close to the second header pipe 44 have a relatively wide arrangement pitch. In FIG. 3, when the amount of liquid sprayed by each nozzle 64 (the amount of liquid sprayed per time for a predetermined pressure) is substantially the same, the amount of water supplied is relatively large in the upstream portion of the tube 40, In the downstream part, the amount of water supplied is relatively small.

  FIG. 4 is a schematic diagram illustrating another example of the arrangement of the nozzles 64. As shown in FIG. 4, the types and / or characteristics of the nozzles 64 vary in the axial direction of the tube 40. Specifically, on the upstream side of the thermal fluid in the tube 40 (portion close to the first header pipe 42), a nozzle 64 (with a relatively large amount of sprayed liquid (spattered amount per time for a predetermined pressure)) ( A water outlet) is disposed, and a nozzle 64 (water outlet) having a relatively small amount of spray is disposed on the downstream side of the thermal fluid (portion close to the second header pipe 44). In FIG. 4, when the arrangement pitch of the nozzles 64 along the axial direction of the tube 40 is substantially uniform, the supply amount of water is relatively large in the upstream portion of the tube 40 and in the downstream portion. Water supply is relatively low.

  FIG. 5 is a schematic diagram illustrating another example of the spray mechanism 60. As shown in FIG. 5, the spray mechanism 60 includes a control device 70 that can change the supply amount of water at a plurality of positions in the axial direction of the tube 40. In FIG. 5, the spray pipe 66 and the nozzle 64 are grouped into a plurality of groups (nozzle groups 71A to 71D). The control device 70 includes a valve 72A for adjusting the amount and / or pressure of water supplied to the first nozzle group 71A, a valve 72B for adjusting the amount of water and / or pressure supplied to the second nozzle group 71B, and a third nozzle. A valve 72C for adjusting the amount and / or pressure of water supplied to the group 71C, a valve 72D for adjusting the amount and / or pressure of water supplied to the fourth nozzle group 71D, and a controller 74 for controlling the valves 72A to 72D Have

  In FIG. 5, the first nozzle group 71 </ b> A corresponds to the upstream side of the thermal fluid in the tube 40 (portion close to the first header pipe 42), and the fourth nozzle group 72 </ b> B corresponds to the downstream side of the thermal fluid ( Corresponding to the second header pipe 44). The controller 74 has a relatively large amount of liquid sprayed from the first nozzle group 71A per time, and the liquid spray amount decreases in the order of the second nozzle group 71B, the third nozzle group 71C, and the fourth nozzle group 71D. The valves 71A to 71D are controlled.

  The water supply from the spray mechanism 60 along the flow direction of the thermal fluid flowing in the tube 40 by using the one form shown in the examples of FIGS. 3 to 5 or the combination of two or more. The amount changes. That is, the spray mechanism 60 has a relatively large supply amount of water in the upstream portion of the tube 40 and a supply amount of water in the downstream portion of the tube 40 with respect to at least a part of the region of the tube 40. Water is supplied toward the tube 40 so as to be relatively small.

  In the present embodiment, the amount of water supplied varies in the axial direction of the tube 40 through which the thermal fluid flows with respect to at least a part of the region of the tube 40, so that the efficiency can be improved even with a heat source at a relatively low temperature level. Water can be evaporated. That is, the amount of water sprayed per unit length of the tube 40 is optimized over the entire axial direction of the tube 40, and as a result, the heat utilization efficiency is improved.

  When the temperature of the thermal fluid flowing through the tube 40 changes with heat dissipation, a relatively large amount of water is supplied to the outer surface portion of the tube 40 having a relatively high temperature, and the outer surface portion of the tube 40 having a relatively low temperature. A relatively small amount of water can be supplied. For example, when at least a part of the thermal fluid flowing through the tube 40 is a supercritical fluid or a gas, the temperature of the thermal fluid is likely to decrease relatively gradually with heat radiation. In accordance with the temperature change of the thermal fluid, the amount of water supplied for each portion of the tube 40 is optimized to provide high heat transfer and efficient steam generation.

  In the present embodiment, the profile of the amount of water supplied to the tube 40 can be changed for each layer. That is, the change in the amount of water supply in the axial direction with respect to the tube 40 belonging to the lower position can be set to be different from that for the tube 40 belonging to the higher position layer. Thereby, not only in the axial direction of the tube 40 but also in the gravity direction, the water supply amount per unit length of the tube 40 is optimized throughout the tube 40, and as a result, the heat utilization efficiency is improved.

  For example, in the tube 40 belonging to the highest layer, the supply amount of water in the axial direction is substantially constant, and in the tube 40 belonging to at least one other layer, the supply amount of water in the axial direction varies. It can be set to be. When a constant supply amount of water is supplied to the uppermost layer in the axial direction and the temperature of the thermal fluid flowing through the tube 40 changes with heat dissipation, the amount of water falling from that layer (supply amount−evaporation amount) is: Different in the axial direction. Correspondingly, in the lower layer, the spray mechanism 60 can supply a relatively large amount of water to a region where the amount of falling water is relatively small. Thereby, the water supply amount per unit length of the tube 40 is optimized, and as a result, the heat utilization efficiency is improved.

  Next, the result of analyzing the model according to the present embodiment will be described.

  In the model, a thermal fluid flows in the tube 40 (heat transfer tube), and water showered in the tube 40 evaporates outside the tube 40. The amount of heat transfer is calculated at the portion (unit length portion) of the tube 40 into which the thermal fluid first flows, and the temperature drop due to heat transfer (heat dissipation) and the amount of evaporation due to heat transfer (heat reception) on the water side are calculated. In the next unit length portion, the same heat transfer calculation is performed under the condition that the temperature-decreasing thermal fluid flows.

here,
NOMENCLATURE
A: Heat transfer area [m ² ]
C _p : Specific pressure specific heat [J / kg · K]
d: Heat transfer tube diameter [m]
F: Dirt factor [m ² K / W]
G: Mass flow rate [kg / s]
h: Enthalpy [J / kg]
N _u : Nusselt number N _u = α _i · d _i / λ [−]
KA _o : Thermal conductivity [W / K]
L: Heat transfer tube length [m]
P: Pressure [Pa]
P _r : Prandtl number P _r : = νρC _p / λ [−]
R _e : Reynolds number R _e = u · d _i / ν [−]
T: Temperature [° C]
u: Average pipe flow velocity [m / s]
W: Heat transfer [W]
X _o : Ratio of the wetted area on the outer surface of the heat transfer tube [−]
α: Heat transfer coefficient [W / m ² · K]
Γ: Flow rate on one side of sprayed water per unit length (liquid film flow rate) [kg / m · s]
λ: Thermal conductivity [W / m · K]
ξ: In-pipe friction coefficient [-]
ρ: Density [kg / m ³ ]
ν: Kinematic viscosity coefficient [m ² / s]
Subscript
evap: evaporation
f: Freon
i: In the pipe
n: Order of unit length in heat transfer tube
o: Outside the tube
s: water vapor
w: water

  The heat exchange amount W can be calculated from the equation (1).

W = KA _o X _o (T _f − T _w ) (1)

The heat transmissibility KA _o can be calculated from equation (2).

KA _o = 1 / (1 / α _o A _o + 1 / α _i A _i + ln (d _o / d _i ) / (2πλL) + F / A _i ) (2)
Here, heat transfer area A ₀ = πd _o L, A _i = πd _i L

Next, the extra-tube evaporation heat transfer coefficient α _o can be calculated from the empirical formula (3).

α _o = −1.18921 ・ 10 ⁷ Γ ² + 1.51564 ・ 10 ⁵ Γ + 8394 ・ ・ ・ ・ ・ ・ (3)
(Applicable range: Γ ≧ 0.005 kg / m · s)

On the other hand, it is possible to calculate the Nusselt number N _u from equation (4).

^{_{N u = 0.57 R e 0.8 P}} r 0.4 ······ (4)

The in-tube evaporation heat transfer coefficient α _i can be calculated from Equation (5), which is the Nusselt number definition equation.

N _u = α _i · d _i / λ (5)

  Next, the in-pipe friction coefficient ξ can be calculated from the Blasius equation of equation (6).

ξ = 0.092 ・ 4 ・ R _e ^−0.25・ ・ ・ ・ ・ ・ (6)

  The in-pipe pressure loss ΔP per unit length can be calculated as shown in Equation (7).

ΔP = ξ / 2 ・ ρ ・ u ²・ ΔL / d _i (7)

Here, when the pressure in a certain unit length portion in the heat transfer tube is P _n , the pressure P _{n + 1} in the next unit length portion can be calculated as in Expression (8).

P _{n + 1} = P _n −ΔP (8)

Further, the enthalpy h _n in a certain unit length portion of the heat transfer tube can be calculated from the physical property calculation formula as shown in the formula (9).

h _n = h (P _n , T _n ) (9)

Then, the enthalpy h _{n + 1} in the next unit length portion can be calculated as in equation (10).

_{h n + 1 = h n -} ΔW · (ΔL / u) / (π · d i 2/4 · ρ) ······ (10)

Then, the temperature T _{n + 1} in the next unit length portion can be calculated from the physical property calculation formula as shown in Formula (11).

T _{n + 1} = T (P _{n + 1} , h _{n + 1} ) (11)

Next, the evaporation amount ΔG _evap outside the _tube can be calculated as in equation (12).

ΔG _evap = ΔW · (ΔL / u) / (h _s −h _w ) (12)

  The analysis results based on the predetermined conditions are shown in FIG. 6, FIG. 7, FIG. 8, and FIG. FIG. 6 shows the average flow rate of the hot fluid in the tube along the axial direction of the tube. FIG. 7 shows the pressure in the tube along the axial direction of the tube. FIG. 8 shows the temperature in the tube along the axial direction of the tube. FIG. 9 shows the amount of evaporation (cumulative value) outside the tube along the axial direction of the tube. From the analysis results, it was confirmed that the model according to the present embodiment is suitable for steam generation in a heat source at a relatively low temperature level.

  FIG. 10 shows the amount of water supplied at each stage (= the amount supplied to the upper stage−the amount of evaporation at the upper stage) when a fixed amount of water is supplied in the axial direction to the first stage (topmost) tube. In this case, it has been found that the water supply amount decreases as the level goes down and the upstream side of the pipe. It was confirmed that the additional supply at the intermediate stage is effective for optimizing the supply amount because the water supply amount is too small to dry out.

  FIG. 11 is a schematic diagram showing an example of a steam generation system to which the evaporator 10 is preferably applied.

  In FIG. 11, the steam generation system S <b> 1 includes a heat pump 110 through which a working fluid (working medium, first fluid) flows, a supply unit 120 for a heated fluid (heated medium, second fluid), and a control device 70. . In the present embodiment, the fluid to be heated is water. The control device 70 comprehensively controls the entire system. The configuration of the steam generation system S1 can be variously changed according to the design requirements of the steam generation system S1.

  The heat pump 110 is a device that pumps heat from a low-temperature object and applies heat to the high-temperature object by a cycle including evaporation, compression, condensation, and expansion processes. A heat pump generally has the advantage of relatively high energy efficiency and, as a result, relatively low emissions of carbon dioxide and the like.

  In the present embodiment, the heat pump 110 includes a heat absorption part 111, a compression part 112, a heat radiation part (first heat radiation part 113A, second heat radiation part 113B), and an expansion part 114, which are connected via a conduit. Yes.

  In the heat absorption part 111, the working fluid flowing in the main path 115 absorbs heat from a heat source outside the cycle. In the present embodiment, the heat absorption unit 111 of the heat pump 110 absorbs atmospheric heat. The heat absorption part 111 of the heat pump 110 can also be configured to absorb heat (exhaust heat or the like) from an external device.

  The compression unit 112 compresses the working fluid using a compressor or the like. At this time, the temperature of the working fluid usually increases. The compression unit 112 has a structure for compressing the working fluid into a single stage or a plurality of stages. The number of compression stages is set according to the specifications of the steam generation system S1, and is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more. Among the various compressors such as an axial flow compressor, a centrifugal compressor, a reciprocating compressor, and a rotary compressor, a compressor suitable for compressing a working fluid is applied. Power is supplied to the compressor. The compression ratio (pressure ratio) of the compression unit 112 is set according to the specifications of the steam generation system S1.

  The heat radiating sections 113A and 113B have a conduit through which the working fluid compressed by the compression section 112 flows, and gives the heat of the working fluid flowing in the main path 115 to a heat source outside the cycle. In the present embodiment, the first heat radiating portion 113A and the second heat radiating portion 113B are arranged in that order along the flow direction of the working fluid. The number of heat radiation units is set according to the specifications of the steam generation system S1, and is 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 or more.

  The expansion unit 114 expands the working fluid using a pressure reducing valve, a turbine, or the like. At this time, the temperature of the working fluid usually decreases. When a turbine is used, power can be taken out from the expansion section 114, and the power may be supplied to the compression section 112, for example. As the working fluid used in the heat pump 110, various known heat media such as a chlorofluorocarbon medium, ammonia, water, carbon dioxide, and air are used according to the specifications and heat balance of the steam generation system S1.

  The supply unit 120 includes a heating unit 121, an evaporation unit 122, and a compressor 130.

  Heating unit 121 includes a conduit that is thermally connected to second heat radiating unit 113B of heat pump 110 and through which water from a supply source (not shown) flows. For example, the conduit of the heating unit 121 is disposed in contact with or adjacent to the conduit of the second heat radiating unit 113B. The 1st heat exchanger 141 is comprised including the heating part 121 and the 2nd thermal radiation part 113B. The first heat exchanger 141 may have a countercurrent heat exchange system in which a low-temperature fluid (water in the supply unit 120) and a high-temperature fluid (working fluid in the heat pump 110) flow in opposition. Alternatively, the first heat exchanger 141 may have a parallel flow type heat exchange method in which a high-temperature fluid and a low-temperature fluid flow in parallel. In the present embodiment, the conduit of the heating unit 121 is disposed inside the conduit of the second heat radiating unit 113B of the heat pump 110. In the heating unit 121, the temperature of the water in the supply unit 120 rises due to the heat transferred from the second heat radiating unit 113B of the heat pump 110. In other embodiments, the first heat exchanger 141 can employ another heat exchange structure. For example, the conduit of the second heat radiating portion 113B can be disposed on the outer peripheral surface of the conduit of the warming portion 121.

  The evaporation unit 122 includes the evaporator 10 shown in FIG. That is, the evaporation unit 122 includes the chamber 20 and the spray mechanism 60. The evaporation unit 122 can include other elements such as a mist separator 80 as required.

  In the present embodiment, a part of the conduit (heat exchange tube 40) of the first heat radiating portion 113 </ b> A of the heat pump 110 is disposed in the chamber 20. The spray mechanism 60 sprays water toward the tube 40.

  In the evaporation unit 122, the working fluid having heat flows through the tube 40, and water from the spray mechanism 60 is supplied to the outer surface of the tube 40. Through the tube 40, the heat of the thermal fluid is transferred to the water attached to the outer surface of the tube 40. On the outer surface of the tube 40, the heated water evaporates. That is, water evaporates outside the tube 40 in the internal space of the chamber 20. For example, the vapor is discharged to the outside through the duct 137 from the opening 22 provided in the chamber 20.

  Here, the temperature difference between the saturation temperature (boiling temperature) of water in the chamber 20 and the working fluid flowing through the tube 40 (the first heat radiating portion 113A) as the heat source is relatively small, for example, about 5 ° C. to 15 ° C., about 15 ° C to 25 ° C, 25 ° C to 35 ° C, 35 ° C to 45 ° C, 45 ° C to 55 ° C, 55 ° C to 65 ° C, 65 ° C to 75 ° C, 75 ° C to 85 ° C , About 85 ° C. to about 95 ° C., or about 95 ° C. or higher.

  As described above, the evaporation unit 122 having such a configuration can widen the water-steam interface as compared with a configuration in which the medium to be heated (water) flows in the pipe. This is advantageous for evaporation processes using relatively low temperature level heat sources.

  In such a steam generation system S1, the temperature of the water from the supply source rises to near the boiling point by the heat from the second heat dissipating part 113B of the heat pump 110 in the first heat exchanger 141. The warm water is supplied to the spray mechanism 60. In the chamber 20, the water changes phase and evaporates due to the heat from the first heat dissipating part 113 </ b> A of the heat pump 110.

  The energy efficiency of the boiler is generally about 0.7 to 0.8 (70 to 80%), whereas the coefficient of performance (COP) as the energy efficiency of the heat pump is generally 2.5 to 5. 0. The coefficient of performance of the heat pump changes according to the input / output temperature difference of the medium to be heated (water), and if the temperature difference is excessively large, the coefficient of performance (COP) may decrease. In this embodiment, depending on the state of the medium to be heated and the working fluid, the heat pump has a separate heating section (heat dissipating section), etc., so that the input / output temperature difference is suppressed and steam is generated with higher energy efficiency than the boiler. Can be generated. The supply temperature of water to the heating unit 121 is, for example, about 20 ° C., and the outlet temperature of water from the heating unit 121 (the inlet temperature of water to the evaporation unit 122) is, for example, about 90 to 95 ° C. The above numerical values are examples for understanding, and the present invention is not limited thereto.

  In addition, the number of the heat radiation part of the heat pump 110 and the evaporation part of the supply unit 120 is appropriately set according to the characteristics of the working fluid. Further, the heating unit 121 (second heat radiating unit 113B) can be omitted when the supply temperature of water from the supply source is relatively high.

  In the present embodiment, the sensible heat of water is mainly performed in the first heat exchanger 141 (heating unit 121), and the latent heat of water is mainly performed in the evaporation unit 122. Therefore, the first heat exchanger 141 including the second heat radiating unit 113B is in a form suitable for sensible heat exchange, and the heat exchange unit including the first heat radiating unit 113A, the evaporation unit 122, and the like is in a form suitable for latent heat exchange. Thus, the apparatus configuration is optimized, and in accordance with this, steam is generated through a preferable heating process. The steam from the steam generation system S1 is supplied to a predetermined external facility such as a manufacturing plant, a cooking facility, an air conditioning facility, a power plant, and the like.

  FIG. 12 is a schematic view showing another example of a steam generation system to which the evaporator 10 is preferably applied. In the following description, the same components as those in the system of FIG. 11 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  As shown in FIG. 12, in the steam generation system S <b> 2, the internal space of the chamber 20 of the evaporation unit 122 is sucked by the compressor 130 through the duct 123. The steam generated in the chamber 20 is guided to the compressor 130 through the duct 123.

  The compressor 130 is fluidly connected to the gas phase space of the chamber 20 via the duct 123 and the opening 22 of the chamber 20. As the compressor 130, various compressors such as an axial flow compressor, a centrifugal compressor, a reciprocating compressor, and a rotary compressor are applied, and those suitable for vapor compression are used. The compressor 130 compresses the steam from the chamber 20 and flows the pressurized steam downstream.

  Due to the suction action by the compressor 130, the internal space of the chamber 20 is decompressed. Control valves (such as a flow control valve) and the compressor 130 (not shown) are controlled so that the internal pressure of the chamber 20 is a negative pressure (negative pressure) that is lower than the atmospheric pressure. This control is performed based on a measurement result of a sensor (not shown) that measures the internal pressure of the chamber 20, for example.

  In the compressor 130 and / or the supply unit 120, a nozzle 135 that supplies water (hot water) to the steam is disposed as necessary. The arrangement position of the nozzle 135 is, for example, an inlet and / or an outlet of the compressor 130. When the compressor 130 is a multistage type, the nozzle 135 can be disposed between the stages of the compressor 130. The multistage compression structure of the compressor 130 is advantageous for increasing the temperature and pressure of steam. The compressor 130 can have a multiaxial compression structure in which the rotation speed corresponding to each of the multistage compression units is individually controlled. Alternatively, the compressor 130 can have a coaxial multistage compression structure. The compression ratio (pressure ratio) of each compression unit is set according to the specification of the steam generation system S2. For discharging the liquid from the nozzle 135, a power source such as a pump may be used, or a pressure difference between an inlet and an outlet of a conduit through which the liquid flows may be used.

  In the present embodiment, water from the supply source becomes steam at a relatively low pressure and low temperature when heated by the heat pump 110 (heat dissipating units 113A and 113B), and steam at a relatively high pressure and high temperature when compressed by the compressor 130. It becomes. That is, the water heated by the heat pump 110 is further heated by the compression by the compressor 130, thereby generating high-temperature steam of 100 ° C. or higher.

  FIG. 13 is a Ts diagram showing an example of a change in the state of water in the evaporation unit 122 and the compressor 130 shown in FIG. As shown in FIG. 13, after the temperature rises to near the boiling point, water undergoes a phase change while keeping the temperature constant. At this time, saturated steam d0 is generated in a state of negative pressure P0 that is lower than atmospheric pressure (P1 = 1 atm = about 0.1 MPa). The temperature of the saturated vapor d0 is lower than the normal boiling point, for example, about 90 ° C.

  Next, the saturated steam d0 becomes relatively high pressure and high temperature steam (superheated steam e2) by compression by the compressor 130 (see FIG. 12). That is, the steam rises in temperature with the compression. The pressure P2 of the superheated steam e2 is higher than atmospheric pressure, for example, 0.8 MPa.

  A saturated steam of about 160 ° C. can be obtained by cooling the superheated steam e2 of 0.8 MPa under a constant pressure (dashed line a in FIG. 12). Similarly, saturated steam d1 at about 100 ° C. can be obtained by cooling superheated steam at atmospheric pressure (about 0.1 MPa) under constant pressure. The above numerical values are examples for understanding, and the present invention is not limited thereto.

  By directly mixing liquid water or hot water into the cooling from superheated steam to saturated steam, the volume of steam is increased. In this case, for example, water or hot water is supplied to the steam at the outlet of the compressor 130.

  By optimizing the supply amount and timing of water or hot water, the change from the relatively low pressure and low temperature saturated steam d0 to the relatively high pressure and high temperature saturated steam d2 can be made more direct. For example, when an appropriate amount of water or hot water is supplied to the steam at the inlet of the compressor 130, the saturated steam d0 at the inlet of the compressor 130 changes to saturated steam d2 at the outlet of the compressor 130 (FIG. 12). Broken lines c1 (spray) and c2 (compression)). Alternatively, when an appropriate amount of water or hot water is supplied to the steam for each stage of the compressor 130 in the middle of the compressor 130, the saturated steam d0 at the inlet of the compressor 130 becomes saturated steam d2 at the outlet of the compressor 130. (Broken line b in FIG. 12). That is, by optimizing the combination of compression by the compressor 130 and cooling by water or hot water, steam close to saturation can be efficiently discharged from the compressor 130.

  Thus, in the steam generation system S2, both saturated steam and superheated steam can be easily generated by sequential heating by the heat pump 110 and the compressor 130. That is, the steam generation system S2 is highly flexible with respect to the steam specifications. The steam from the steam generation system S2 is supplied to a predetermined external facility such as a manufacturing plant, a cooking facility, an air conditioning facility, or a power plant.

  In the steam generation system S2, the compressor 130 supplements a part of the heating process for generating steam, so the heat pump 110 is used at a high COP. Therefore, the steam generation system S2 is expected to reduce the primary energy as a whole.

  In the steam generation system S2, the heat pump 110 further includes a bypass path 117 and a regenerator 118. The inlet end of the bypass path 117 is fluidly connected to a conduit between the first heat radiating part 113A and the second heat radiating part 113B in the main path 115 of the heat pump 110. An outlet end of the bypass path 117 is fluidly connected to a conduit between the second heat radiating portion 113 </ b> B and the expansion portion 114 in the main path 115. A flow rate control valve that controls the bypass flow rate of the working fluid can be provided at the inlet of the bypass path 117. In the bypass path 117, a part of the working fluid from the first heat radiating portion 113A bypasses the second heat radiating portion 113B and merges with the working fluid from the second heat radiating portion 113B before the expansion portion 114. The remaining working fluid from the first heat radiating portion 113A flows through the second heat radiating portion 113B, and the heat from the second heat radiating portion 113B is transmitted to the water in the supply unit 120.

  The regenerator 118 has a configuration in which a part of the conduit of the bypass path 117 and a part of the conduit of the main path 115 of the heat pump 110 (the conduit between the heat absorption unit 111 and the compression unit 112) are thermally connected. Have. For example, both conduits are placed in contact with or adjacent to each other. In the heat pump 110, the working fluid from the first heat radiating unit 113 </ b> A is hotter than the working fluid from the heat absorbing unit 111. In the regenerator 118, the working fluid from the first heat radiating part 113 </ b> A flowing through the bypass path 117 and the working fluid from the heat absorbing part 111 flowing through the main path 115 of the heat pump 110 exchange heat. By this heat exchange, the temperature of the working fluid in the bypass path 117 is lowered, and the temperature of the working fluid in the main path 115 is raised. The regenerator 118 may have a countercurrent heat exchange structure in which a low-temperature fluid (working fluid in the main path 115) and a high-temperature fluid (working fluid in the bypass path 117) flow in opposition. Alternatively, the regenerator 118 may have a parallel flow type heat exchange structure in which a high-temperature fluid and a low-temperature fluid flow in parallel.

  In the present embodiment, a part of the working fluid bypasses the first heat exchanger 141 via the bypass path 117, whereby the amount of working fluid flowing into the first heat exchanger 141 is controlled. The working fluid flowing through the bypass path 117 exchanges heat with the working fluid from the heat absorption unit 111 flowing through the main path 115 of the heat pump 110 in the regenerator 118. By this heat exchange, the temperature of the working fluid in the bypass passage 117 is lowered (for example, about 20 ° C.), and the temperature of the working fluid in the main passage 115 of the heat pump 110 is raised (for example, about 95 ° C.). Due to the increase in the input temperature of the working fluid to the compression unit 112, the power of the compression unit 112 is reduced. Note that the bypass amount of the working fluid is determined according to each physical property value (specific heat, etc.) of the fluid to be heated and the working fluid.

  In the present embodiment, the working fluid (for example, about 20 ° C.) in the bypass path 117 whose temperature has dropped in the regenerator 118 is in front of the expansion unit 114 and flows through the main path 115 of the heat pump 110. It merges with the working fluid from (second heat radiating portion 113B). As described above, the output temperature of the working fluid from the first heat exchanger 141 is set to be relatively low (for example, about 30 ° C.). The liquid-gas ratio of the working fluid is optimized by lowering the input temperature of the working fluid to the expansion unit 114. As a result, the heat source outside the cycle in the heat absorption unit 111 (medium flowing through the heat radiating pipe 191 of the cold heat supply device 90). Effectively absorbs heat.

  As described above, in the steam generation system S2, the working fluid after being used for water evaporation is used for warming water and regenerating the working fluid, so that the heat can be effectively used.

  In addition, the number of the heat radiation part of the heat pump 110 and the evaporation part of the supply unit 120 is appropriately set according to the characteristics of the working fluid. Further, the heating unit 121 (second heat radiating unit 113B) can be omitted when the supply temperature of water from the supply source is relatively high.

  The numerical value used in the above description is an example, and the present invention is not limited to this.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. The numerical value used in the above description is an example, and the present invention is not limited to this. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention. The present invention is not limited by the above description, but only by the appended claims.

It is a cross-sectional schematic diagram which shows an evaporator. It is a top view which shows the structural example of a tube typically. It is a top view which shows the structural example of a tube typically. It is a top view which shows the structural example of a tube typically. It is a top view which shows the structural example of a tube typically. It is a schematic diagram which shows an example of arrangement | positioning of a nozzle. It is a schematic diagram which shows another example of arrangement | positioning of a nozzle. It is a schematic diagram which shows another example of a spray mechanism. It is a figure which shows an analysis result. It is a figure which shows an analysis result. It is a figure which shows an analysis result. It is a figure which shows an analysis result. It is a figure which shows an analysis result. It is a schematic diagram showing an example of a steam generation system. It is the schematic which shows another example of a steam production | generation system. It is a Ts diagram which shows an example of the state change of water.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Evaporator, 20 ... Chamber, 22 ... Opening, 40 ... Tube, 42, 44 ... Header pipe, 60 ... Spraying mechanism, 62 ... Pump, 64 ... Nozzle, 66 ... Piping, 66A ... Upper piping (upper unit) , 66B, 66C, 66D ... intermediate piping (intermediate unit), 68 ... supply piping, 70 ... control device, 110 ... heat pump, 111 ... heat absorption section, 112 ... compression section, 113A, 113B ... heat radiation section, 114 ... expansion section, DESCRIPTION OF SYMBOLS 115 ... Main path | route, 117 ... Bypass path, 118 ... Regenerator, 120 ... Supply unit, 121 ... Heating part, 122 ... Evaporating part, 130 ... Compressor, 141, 142 ... Heat exchanger, 170 ... Control apparatus, S1 , S2 ... Steam generation system.

Claims (11)

A chamber;
A tube disposed in the chamber and having a shape in which a first fluid having heat flows and bent in a horizontal plane ;
A spraying mechanism for supplying a second fluid to an outer surface of the tube, and the spraying mechanism for varying a supply amount of the second fluid in an axial direction of the tube in at least a partial region of the tube. ,
The tube has a plurality of layers arranged along the direction of gravity,
The supply amount of the second fluid in the axial direction is set to the tubes belonging to each layer according to the evaporation amount of the tubes in the plurality of layers,
The dispersion liquid mechanism, an evaporator, characterized in Rukoto to have a control device which can change a supply amount of the second fluid at a plurality of positions in the axial direction of at least the tube. Wherein the control device, an evaporator according to claim 1, characterized in that is controlled in accordance with the supply amount of the second fluid to a temperature change of the first fluid. The spray mechanism is
A member through which the second fluid flows;
A plurality of outlets provided in the member, and the plurality of outlets in which an arrangement pitch in the axial direction of the pipe is changed;
The evaporator according to claim 1 or 2 , characterized by comprising: The dispersion liquid mechanism, an evaporator according to any one of claims 1 to 3, characterized in that it comprises a double several nozzles. The evaporator according to claim 4 , wherein the plurality of types of nozzles include a plurality of supply holes having different sizes. The spray mechanism includes an upper unit for supplying the second fluid to the pipe belonging to the highest layer and an intermediate unit for supplying the second fluid to the pipe belonging to another layer. evaporator according to any of claims 1 to 5 to. Wherein the control device, in accordance with the amount of evaporation of the second fluid from the outer surface of the tube which belongs to a layer of high position, the supply amount of the second fluid from the intermediate unit to said belonging to a layer of low position tube an evaporator according to claim 6, characterized in that the control. Change in the supply amount of the second fluid in the axial direction with respect to the tube which belongs to a layer of low position, any one of claims 1 to 7, characterized in that the different with respect to the belonging to a layer of high position tube The evaporator as described in. The supply amount of the second fluid in the axial direction is substantially constant in the tube belonging to the layer at a relatively high position, and the axial direction is at least in a region of the tube belonging to the layer at a relatively low position. evaporator according to any of claims 1 to 8 in which the supply amount of the second fluid are different from each other in. The tube evaporator according to any of claims 1 to 9, characterized in that it comprises a plurality of horizontal groups flowing arrangement and the second fluid respectively in the horizontal direction. The difference between the saturation temperature of the second fluid at a first temperature and said chamber of fluid claim 1, characterized in that less than about 5 ° C. greater than about 95 ° C. to claim 10 The evaporator as described in.

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