JP7124591B2 - steam generator - Google Patents

Description

The present invention relates to a steam generator.

Conventionally, as a steam generator, a highly energy-efficient steam generator that can generate steam without using fuel has been proposed in order to enable efficient recovery of waste heat energy generated in factories, etc. It is

For example, Patent Document 1 discloses a steam generator capable of generating steam using hot water of relatively low temperature as a heat source. A steam generator with an and tube evaporator has been proposed. According to the shell-and-tube evaporator, for example, jacket cooling water (about 91°C) of a gas engine is passed through the tube as a heat source, and water of about 82°C is sprayed on the tube inside the pressure vessel. This allows the gas engine to drive the generator and generate steam at the same time. In this case, by forming a thin liquid film on the surface of the tube, steam can be generated even if the difference between the temperature of the heat source flowing through the tube and the temperature of the sprayed water is relatively small at about 9°C. .
In addition, such a steam generator is provided with a heat exchanger for preheating the make-up water by exchanging heat between the jacket cooling water after the heat is used in the evaporator and the make-up water before being supplied to the evaporator. Therefore, the waste heat of the jacket cooling water, which is the heat source, is used more efficiently.

JP 2014-62663 A

By the way, in a factory or the like where a steam generator is used, jacket cooling water exceeding 100° C. may be generated as a heat source. In such a case, the jacket cooling water after heat utilization in the evaporator is introduced into the heat exchanger while still exceeding 100°C. As a result, the make-up water may be overheated and boiled inside the heat exchanger. If the make-up water boils inside the heat exchanger, the heat transfer surface of the heat exchanger will become wet and dry, and the corrosive ions (chloride ions, etc.) contained in the make-up water will locally concentrate. occur. Wetting and drying of the heat transfer surface can lead to failure due to thermal fatigue. On the other hand, local concentrations of corrosive ions can lead to corrosion failure. In particular, when a plate-type heat exchanger or the like with high heat transfer efficiency is used, the make-up water is likely to boil inside the heat exchanger.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a steam generator that can prevent makeup water from boiling inside a heat exchanger that preheats the makeup water.

The present invention includes an evaporator in which a tube for circulating a heat source fluid and a spray nozzle for spraying boiler water onto the tube are arranged inside a container, and a water header which is arranged below the evaporator and stores boiler water. a water spray line for supplying boiler water in the water header to the spray nozzle; a water spray pump provided in the water spray line; a blow line for discharging the boiler water from the water header; a provided blow valve, a heat source fluid supply line that supplies heat source fluid to the tube, a heat source fluid discharge line that discharges the heat source fluid that has flowed through the tube, and a makeup water line that supplies makeup water to the water header. a make-up water pump provided in the make-up water line; a heat exchanger for exchanging heat between the heat source fluid flowing through the heat source fluid discharge line and make-up water flowing through the make-up water line; and the make-up water line and a control means for controlling the flow rate of the make-up water so that the flow rate detected by the flow rate detection means does not fall below a preset minimum flow rate. The flow rate refers to a steam generator set to a flow rate such that the temperature of make-up water after heat exchange is less than 100°C even when heat is exchanged with a heat source fluid exceeding 100°C in the heat exchanger .

Further, the steam generator further includes water level detection means for detecting the water level of the water header, and the control means controls the flow rate to be greater than the minimum flow rate when the water level detected by the water level detection means is less than a first set water level. The flow rate of makeup water is controlled so that makeup water is supplied at a first set flow rate, and when the water level detected by the water level detection means is equal to or higher than the first set water level, the flow rate is smaller than the first set flow rate and the minimum The flow rate of makeup water is controlled so that makeup water is supplied at a second set flow rate larger than the flow rate, and when the water level detected by the water level detection means is equal to or higher than the second set water level higher than the first set water level, It is preferable to open the blow valve.

Further, the steam generator further comprises water level detection means for detecting the water level of the water header, and the control means controls the target water level, which is a preset water level detected by the water level detection means within a range not lower than the minimum flow rate. When the flow rate detected by the flow rate detection means reaches the minimum flow rate, the blow valve is preferably opened.

Further, the present invention includes an evaporator in which a tube for circulating a heat source fluid and a spray nozzle for spraying boiler water to the tube are arranged inside a container, and an evaporator arranged below the evaporator to store the boiler water. a water header, a water spray line that supplies boiler water in the water header to the spray nozzle, a water spray pump provided in the water spray line, a blow line that discharges boiler water from the water header, and the blow a blow valve provided in a line, a heat source fluid supply line that supplies heat source fluid to the tube, a heat source fluid discharge line that discharges the heat source fluid that has flowed through the tube, and a make-up water that supplies make-up water to the water header. a make-up water pump provided in the make-up water line; a heat exchanger that exchanges heat between a heat source fluid flowing through the heat source fluid discharge line and make-up water flowing through the make-up water line; Make-up water temperature detection means for detecting the temperature of make-up water flowing out of the heat exchanger; A proportionally controllable valve arranged in the heat exchanger, and a control that controls the opening of the valve so that the pressure of the make-up water flowing through the heat exchanger exceeds the saturated vapor pressure at the temperature detected by the make-up water temperature detection means. and a steam generator comprising:

Further, the steam generator includes pressure detection means for detecting the pressure of the makeup water flowing through the heat exchanger, and the control means controls the pressure detected by the pressure detection means to be the temperature detected by the makeup water temperature detection means. It is preferable to control the degree of opening of the valve so as to exceed the saturated vapor pressure at .

Further, the steam generator includes boiler water temperature detection means for detecting the temperature of the boiler water, internal pressure detection means for detecting the pressure inside the evaporator, makeup water temperature detection means for detecting the temperature of the makeup water, wherein the control means further comprises an antifreeze control unit that operates the steam generator in an antifreeze mode when activation of the steam generator is stopped, and the antifreeze control unit includes ( i) driving the makeup water pump when the temperature detected by the makeup water temperature detection means is equal to or lower than a preset lower limit temperature, or when the water level detected by the water level detection means is less than the preset lower limit water level, ii) when the water level detected by the water level detecting means is equal to or higher than the lower limit water level, the temperature detected by the boiler water temperature detecting means is equal to or lower than the lower limit temperature, and the pressure detected by the internal pressure detecting means is equal to or lower than a preset lower limit pressure; and (iii) opening the blow valve when the water level detected by the water level detecting means is equal to or higher than the upper limit water level higher than the lower limit water level.

According to the steam generator of the present invention, it is possible to prevent the make-up water from boiling inside the heat exchanger that preheats the make-up water.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the steam generator which concerns on 1st Embodiment of this invention. It is a perspective view which shows the can body part which consists of several evaporation tanks which concern on 1st Embodiment. FIG. 3 is a cross-sectional view in the width direction of the evaporation tank according to the first embodiment, which is a cross-sectional view taken along the line XX of FIG. 2; FIG. 3 is a cross-sectional view in the depth direction of the evaporation tank according to the first embodiment, and is a cross-sectional view taken along the line YY of FIG. 2; It is a figure which shows the structure of the steam generator which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the steam generator which concerns on 3rd Embodiment of this invention.

Preferred embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a diagram showing the overall configuration of a steam generator according to a first embodiment of the present invention.
The steam generator 1 of the first embodiment uses a heat source fluid such as waste hot water generated in a factory or the like to generate low-pressure steam.

As shown in FIGS. 1 to 3, the steam generator 1 includes a can body 2, a steam lead-out part 24 provided in the can body 2, a tube group 100 arranged inside the can body 2, and a spray nozzle. It includes a nozzle 23 and a control device 90 as control means. In addition, the steam generator 1 includes a heat source fluid supply line L1, a heat source fluid discharge line L2, a steam lead-out line L3, a water spray line L4, a continuous blow line L5 and a concentrated blow line L6 as blow lines, and a supply line. A water line L7, a bypass line L8, and a feed water heat exchanger 3 as a heat exchanger are provided. "Line" is a generic term for lines such as channels, routes, and pipelines through which fluid can flow.

The can body part 2 includes a plurality of evaporation tanks 21 as evaporators, one water header 22 and a water level sensor 27 . A plurality of evaporation tanks 21 are configured by pressure vessels and generate steam respectively.
A water header 22 is arranged below the plurality of evaporation tanks 21 . The water header 22 stores boiler water supplied to the evaporation tank 21 . Boiler water that has not turned into steam inside the evaporation tank 21 is recovered in the water header 22 .

The water level sensor 27 is water level detection means for detecting the water level of the boiler water stored in the water header 22 . In this embodiment, the water level sensor 27 is configured as a level switch including a cylindrical main body 271 and a plurality of electrode rods 272 arranged inside the main body 271 . The body 271 is positioned at the same height as the water header 22 . A lower end portion of the main body 271 is connected to a lower end portion of the water header 22 via a water spray line L4, which will be described later. Also, the upper end of the main body 271 is connected to a steam lead-out line L3, which will be described later. As a result, the water level inside the cylindrical main body 271 becomes equal to the water level of the boiler water in the water header 22 . In this embodiment, the water level sensor 27 has three electrode rods 272L, 272M, 272H with different lengths.

The steam outlet 24 is provided above each of the plurality of evaporation tanks 21 . The steam lead-out part 24 leads out the steam generated in the evaporation tank 21 .

A tube group 100 is composed of a plurality of tubes 101 . A plurality of tubes 101 constituting the tube group 100 are arranged to extend horizontally inside the evaporation tank 21 . Hot water as a heat source fluid flows inside these tubes 101 .

The spray nozzle 23 is arranged above the tube group 100 . The spray nozzle 23 sprays boiler water toward the tube group 100 .
Specific configurations of the can body portion 2, the steam outlet portion 24, the tube group 100, and the spray nozzle 23 will be described later.

The heat source fluid supply line L1 supplies hot water as a heat source fluid to the tube group 100 . The upstream side of the heat source fluid supply line L1 is connected to a waste heat source that supplies hot water. The downstream side of the heat source fluid supply line L<b>1 is connected to one end side of some tubes 101 among the plurality of tubes 101 forming the tube group 100 .

The heat source fluid discharge line L2 flows through the tube group 100 and discharges hot water used as a heat source to the outside. The upstream side of the heat source fluid discharge line L<b>2 is connected to the other end side of some of the tubes 101 among the plurality of tubes 101 forming the tube group 100 .

The steam lead-out line L3 leads out the steam generated in the evaporation tank 21 . The upstream side of the steam outlet line L3 is connected to the steam outlet section 24 . The downstream side of the steam lead-out line L3 is connected to an ejector, a steam compressor, etc. (not shown). A vapor pressure sensor 31 as internal pressure detecting means is arranged in the vapor lead-out line L3. The vapor pressure sensor 31 can detect the pressure inside the evaporation tank 21 by detecting the vapor pressure inside the vapor lead-out line L3.

The water spray line L4 connects the water header 22 and the spray nozzles 23 and supplies boiler water stored in the water header 22 to the spray nozzles 23 . A water spray pump 41 and a boiler water temperature sensor 42 as boiler water temperature detection means are arranged in the water spray line L4.
The water spray pump 41 pumps up boiler water stored in the water header 22 to the spray nozzles 23 . The boiler water temperature sensor 42 detects the temperature of boiler water flowing through the water spray line L4.

A continuous blow line L5 and a concentrated blow line L6 branch from the water spray line L4. A continuous blow line L5 and a concentrated blow line L6 drain a portion of boiler water stored in the water header 22 . A blow valve 51 and a blow valve 61 are arranged in the continuous blow line L5 and the concentrated blow line L6, respectively. In this embodiment, the blow valve 51 and the blow valve 61 are composed of electromagnetic valves.

The makeup water line L7 connects the water header 22 and a makeup water tank or the like (not shown) that stores makeup water. The makeup water line L7 supplies makeup water to the water header 22 . The makeup water line L7 is provided with a makeup water pump 71, a check valve 72, a makeup water flow rate sensor 73 as flow rate detection means, and a makeup water temperature sensor 74 as makeup water temperature detection means.
The make-up water pump 71 boosts the pressure of make-up water supplied from a make-up water tank or the like and supplies it to the inside of the water header 22 . The check valve 72 blocks the backflow of makeup water to the upstream side of the makeup water line L7, and prevents the supply of makeup water to the water header 22 through the makeup water line L7 when water pressure equal to or higher than a predetermined pressure is received. allow.
The make-up water flow rate sensor 73 is arranged between the make-up water pump 71 and the check valve 72, and detects the flow rate of make-up water flowing through the make-up water line L7.
The make-up water temperature sensor 74 is arranged near the inlet of the feed water heat exchanger 3 in the make-up water line L7 and detects the temperature of the make-up water introduced into the feed water heat exchanger 3 .

The bypass line L8 connects the heat source fluid supply line L1 and the heat source fluid discharge line L2, and bypasses the hot water flowing through the heat source fluid supply line L1 to the heat source fluid discharge line L2 without passing through the tube group 100. A three-way valve 81 is arranged at the connecting portion between the bypass line L8 and the heat source fluid supply line L1. The three-way valve 81 switches the flow path of hot water flowing through the heat source fluid supply line L1 to the tube group 100 side or the bypass line L8 side.

The feed water heat exchanger 3 exchanges heat between hot water flowing through the heat source fluid discharge line L2 and makeup water flowing through the makeup water line L7. As a result, the make-up water supplied to the water header 22 is preheated by the hot water flowing through the heat source fluid discharge line L2. In this embodiment, the feed water heat exchanger 3 is configured by a plate heat exchanger.

The control device 90 includes a storage section and a control section. The control device 90 controls the operation of the steam generator 1 by controlling various valves and the like based on information stored in the storage unit and information detected by various sensors. The details of the control of the steam generator 1 by the controller 90 will be described later.

Next, the configurations of the can body 2, the steam outlet 24, the tube group 100 and the spray nozzle 23 will be described with reference to FIGS. 2 to 4. FIG.
FIG. 2 is a perspective view showing the can body portion 2 of the first embodiment. FIG. 3 is a diagram showing one evaporation tank 21 in a cross-sectional view taken along line XX of FIG. FIG. 4 is a cross-sectional view taken along line YY of FIG. 2, showing one evaporation tank 21. As shown in FIG.

In this embodiment, the can body part 2 includes four evaporation tanks (evaporators) 21 and one water header 22 .
As shown in FIGS. 2 and 3, the evaporation tank 21 is a rectangular parallelepiped whose length (height) in the height direction HD and length (width) in the width direction WD are shorter than the length (depth) in the depth direction LD. formed into shape. A plurality of evaporation tanks 21 are connected in the width direction WD.

The water header 22 is arranged below the center region of the evaporation tank 21 in the depth direction LD. In this embodiment, the water header 22 is formed in a cylindrical shape extending across the width direction WD of the plurality of evaporation tanks 21 .

The above evaporation tank 21 and water header 22 are connected via a plurality of pipes 26 . More specifically, the upper ends of the plurality of pipes 26 are connected to the lower surfaces of the plurality of evaporation tanks 21, respectively. Also, the lower ends of the plurality of pipes 26 are connected to the upper portion of the peripheral surface of the water header 22 .

The vapor outlet part 24 is provided in the central region of the evaporation tank 21 in the width direction WD and in the central region of the evaporation tank 21 in the depth direction LD.

The tube group 100 consists of a plurality of tube units 110 . Each of the tube units 110 extends in the depth direction LD of the evaporation tank 21 and is composed of a plurality of tubes 101 arranged in a plurality of rows and columns.

The tube unit 110 includes an upper unit 110a arranged on the upper stage and a lower unit 110b arranged below the upper unit 110a. In this embodiment, the tube group 100 has three upper units 110a and three lower units 110b.
Further, as shown in FIG. 4, two adjacent tube units 110 among the plurality of tube units 110 (in this embodiment, an upper unit 110a and a lower unit 110b located below the upper unit 110a) are A plurality of tubes 101 form a connecting tube unit composed of U-shaped tubes curved in a U-shape. In this embodiment, the tube group 100 is composed of three sets of connecting tube units.

Next, the flow of hot water in tube group 100 will be described. In this embodiment, the tube group 100 is composed of three sets of connecting tube units. The tube group 100 and the evaporation tank 21 are joined at both ends of the U-shaped tube 101 (that is, at the end opposite to the U-shaped portion). Specifically, the tip of the tube 101 is inserted into the tube hole of the end plate (tube plate) of the evaporation tank 21, and the leakage is stopped by seal welding.
A case body 25 to which the heat source fluid supply line L1 and the heat source fluid discharge line L2 are connected is provided at the end of the evaporation tank 21 to which the tube 101 is joined. This case body 25 functions as a distribution header or collection header for the tube unit 110 .

The hot water supplied from the heat source fluid supply line L1 is introduced into the tube group 100 via the case body 25, and the hot water flowing through the tube group 100 passes through the case body 25 to the heat source fluid discharge line L2. discharged from
A partition is provided inside the case body 25 to separate the upper unit 110a and the lower unit 110b. Also, in the lower unit 110b, a partition is provided to separate the lower unit 110b into which hot water is introduced from the heat source fluid supply line L1 and the other two lower units 110b. Furthermore, in the upper unit 110a, a partition is provided to separate the upper unit 110a connected to the heat source fluid discharge line L2 from the other two upper units 110a.

As shown in FIG. 2, the hot water supplied from the heat source fluid supply line L1 passes through the case body 25 and passes through one of the three lower units 110b (in this embodiment, the bottom unit 110b shown in FIGS. 2 and 3). It is introduced into the lower unit 110b) on the right side. The hot water introduced into the lower unit 110b flows through the lower unit 110b toward the back in the depth direction LD, and then flows toward the front through the upper unit 110a that constitutes the lower unit 110b and the connecting tube unit. The hot water that has flowed through the upper unit 110a is then introduced into the adjacent upper unit 110a (central upper unit 110a shown in FIGS. 2 and 3) via the case body 25. FIG. Then, the hot water that has flowed through the central upper unit 110a flows through the central lower unit 110b, passes through the case body 25 again, and passes through the lower unit 110b (the leftmost unit shown in FIGS. 2 and 3) adjacent to the central lower unit 110b. is introduced into the lower unit 110b). After flowing through the leftmost lower unit 110b and upper unit 110a, the hot water is discharged through the case body 25 and the heat source fluid discharge line L2.

A plurality of spray nozzles 23 are arranged at predetermined intervals in the depth direction LD of the evaporation tank 21 in the center region of the evaporation tank 21 in the width direction WD. In the present embodiment, two spray nozzles 23 are arranged on the far side and the front side of the steam lead-out portion 24 . The spray angle of the spray nozzle 23 is wide and close to 180°.

The steam generator 1 of this embodiment operates as follows.
First, hot water as a heat source is supplied from the waste heat source to the tube group 100 (tube 101) through the heat source fluid supply line L1. Hot water supplied to the tube group 100 flows through the inside of the evaporation tank 21 .
On the other hand, inside the evaporation tank 21 , boiler water is sprayed from the spray nozzle 23 toward the tube group 100 . Also, the inside of the evaporation tank 21 is maintained at a negative pressure (eg, -0.043 MPaG). As a result, the hot water flowing through the tube 101 loses heat by the sprayed boiler water, is lowered in temperature, and is discharged through the heat source fluid discharge line L2.

A thin liquid film is formed on the surface of the tube 101 through which hot water flows by spraying boiler water from the spray nozzle 23 . In this way, in a state where the negative pressure is maintained, a thin liquid film is formed on the surface of the tube 101, so that there is a temperature difference between the hot water flowing through the tube 101 and the boiler water sprayed by the spray nozzle 23. Steam can be efficiently generated even when is relatively small.

The steam generated inside the evaporation tank 21 is led out from the steam lead-out part 24 and supplied to the ejector, the steam compressor, etc. through the steam lead-out line L3.
Boiler water that has not turned into steam inside the evaporation tank 21 is stored in the water header 22 . The boiler water stored in the water header 22 is pumped up to the spray nozzles 23 by the water spray pump 41 through the water spray line L4 and sprayed onto the tubes 101 again.

A continuous blow line L5 and a concentrated blow line L6 drain the boiler water stored in the water header 22 . The continuous blow line L5 constantly discharges boiler water at a constant rate with respect to the supply water amount by repeatedly opening and closing the blow valve 51 at predetermined closing and opening times. The concentration blow line L6 monitors the concentration of the boiler water stored in the water header 22 by an electrical conductivity sensor (not shown), and when the concentration exceeds the upper limit concentration, the blow valve 61 is opened and the lower limit concentration is detected. When it becomes less than the blow valve 61 is closed.

When the amount of boiler water circulating between the water spray line L4 and the water header 22 decreases (when the water level detected by the water level sensor 27 falls below a predetermined water level), the water header 22 is Make-up water is supplied to The make-up water sent from a water supply tank or the like is, for example, about 5 to 30°C. The low-temperature makeup water sent from the makeup water line L7 is preheated in the feed water heat exchanger 3 by heat exchange with hot water flowing through the heat source fluid discharge line L2.

Here, in a factory or the like where the steam generator 1 is used, jacket cooling water exceeding 100° C. may be generated as a heat source. In such a case, the jacket cooling water (hot water) after heating the boiler water in the evaporation tank 21 is introduced into the feed water heat exchanger 3 while still exceeding 100°C. Then, the make-up water may be overheated inside the feed water heat exchanger 3 and boil.
In particular, when the amount of steam used is small and the flow rate of makeup water to the water header 22 is low, it is difficult to avoid overheating of the makeup water. If the make-up water boils inside the feed water heat exchanger 3, the heat transfer surface of the feed water heat exchanger 3 may become wet and dry, and corrosive ions (such as chloride ions) contained in the make-up water may locally concentration occurs. Wetting and drying of the heat transfer surface can lead to failure due to thermal fatigue. On the other hand, local concentrations of corrosive ions can lead to corrosion failure. In particular, when a plate-type feed water heat exchanger 3 with high heat transfer efficiency is used, the make-up water is likely to boil inside the feed water heat exchanger 3 .

Moreover, when the steam generator 1 is installed outdoors, it is necessary to take measures against freezing in winter. That is, if the operation of the steam generator 1 continues in a low temperature environment, the boiler water held in the steam generator 1 may freeze, so the boiler water is prevented from freezing. Countermeasures are required. The steam generator 1 includes a water header that stores boiler water and a plurality of paths (pipes) through which the boiler water flows. Therefore, when these tanks and pipes are heated by, for example, heaters, many heaters are required, which increases the initial cost and running cost of the steam generator 1 .

Therefore, the control device 90 in the steam generator 1 of the first embodiment prevents boiler water from freezing without separately installing a feed water control unit 91 that prevents the make-up water from boiling in the feed water heat exchanger 3 and a heater or the like. It is configured including an anti-freezing control unit 92 .

[Water supply controller]
The feed water control unit 91 controls the flow rate of the make up water so that the flow rate of the make up water flowing inside the feed water heat exchanger 3 (that is, the flow rate detected by the make up water flow rate sensor 73) does not fall below a predetermined minimum flow rate. . Specifically, even if the heat source fluid introduced into the feed water heat exchanger 3 is at the upper limit temperature (for example, 120° C.) allowed by the device specifications, the control device 90 has a replenishment temperature after heat exchange. A flow rate at which the water temperature is less than 100° C. is set as the minimum flow rate. The water supply controller 91 controls the output of the makeup water pump 71 so that the detected flow rate of the makeup water flow rate sensor 73 does not fall below the set minimum flow rate. As a result, as the minimum flow rate, even when heat exchange is performed with a heat source fluid exceeding 100 ° C., by setting the flow rate so that the temperature of the make-up water after heat exchange is less than 100 ° C., the feed water heat exchange It is possible to prevent the make-up water from boiling inside the container 3. - 特許庁

Output control of the make-up water pump 71 may be configured such that, for example, an AC motor is used as the pump drive motor, and the AC motor is controlled by variable voltage variable frequency control (VVVF control) using an inverter device. By changing the drive frequency or drive voltage of the AC motor using the PID algorithm so that the detected flow rate of the makeup water flow rate sensor 73 converges to a reference flow rate that exceeds the minimum flow rate, the makeup water flow rate does not fall below the minimum flow rate. can be kept intact.

Output control of the supplementary water pump 71 may be configured such that, for example, the pump drive motor is a brushless DC motor and the DC motor is controlled at variable speed by pulse width modulation (PWM). By changing the duty ratio of the drive voltage pulse of the DC motor using the PID algorithm so that the detected flow rate of the make-up water flow rate sensor 73 converges to the reference flow rate that exceeds the minimum flow rate, the make-up water flow rate exceeds the minimum flow rate. It can be maintained in a state that does not fall below.

By the way, when the amount of steam used is small and the amount of steam generated in the plurality of evaporation tanks 21 is small, if the make-up water is supplied to the feed water heat exchanger 3 so as not to fall below the minimum flow rate, the water level of the water header 22 may rise too high.
Therefore, the water supply control unit 91 controls the flow rate of makeup water and the blow amount of boiler water based on the water level detected by the water level sensor 27 .

Specifically, the controller 90 is set with a first set flow rate that is greater than the minimum flow rate and a second set flow rate that is less than the first set flow rate and greater than the minimum flow rate. Then, when the water level detected by the water level sensor 27 is less than the first set water level (for example, when the water level is less than the M water level where the electrode rod 272L is ON and the electrode rods 272M and 272H are OFF), the water supply control unit 91 sets the first set water level. The output of the makeup water pump 71 is controlled so that the makeup water is supplied at the flow rate. Further, when the water level detected by the water level sensor 27 is equal to or higher than the first set water level (for example, when the water level is equal to or higher than the M water level at which the electrode rods 272L and 272M are ON and the electrode rod H is OFF), the water supply control unit 91 2. Control the output of the make-up water pump 71 so that make-up water is supplied at the set flow rate. Furthermore, the water supply control unit 91 controls the water level sensor 27 when the water level detected by the water level sensor 27 is equal to or higher than the second set water level higher than the first set water level (for example, when the electrode rods 272L, 272M, and 272H are all turned ON and is equal to or higher than the H water level). , causes the blow valve 51 to open.
As a result, when the water level of the water header 22 is controlled step by step using a plurality of electrode rods 272, while adjusting the flow rate of the make-up water according to the water level of the water header 22, when the water level rises, By supplying makeup water while opening the blow valve 51, the steam generator 1 is operated while maintaining the minimum flow rate.

[Anti-freezing control part]
Next, anti-freezing control by the anti-freezing control section 92 will be described.
The anti-freezing control unit 92 controls the steam generator 1 in a state in which the steam generator 1 is powered on but is not activated (for example, when the steam generator 1 is in a shutdown state or in a standby state). 1 in antifreeze mode.

Regarding anti-freezing control by the anti-freezing control unit 92 , a lower limit temperature and a lower limit pressure are set in the control device 90 .
The anti-freezing control unit 92 detects when the detection temperature of the makeup water temperature sensor 74 is below the set lower limit temperature (for example, when the temperature of the makeup water stagnating in the makeup water line L7 is less than 3° C.), or when the water level sensor 27 When the detected water level is less than the set lower limit water level (for example, less than the M water level where the electrode rod 272L is ON and the electrode rods 272M and 272H are OFF), the makeup water pump 71 is driven. As a result, when the temperature of the make-up water remaining in the pipe drops while the steam generator 1 is not activated, it is determined that there is a risk of freezing, and water supply is forcibly started. Further, by supplying water when the water level of the water header 22 is lowered regardless of the temperature of the supplementary water, the waiting time until the start of steam supply after the start command is shortened.

In addition, the anti-freezing control unit 92 determines that the water level detected by the water level sensor 27 is equal to or higher than the lower limit water level (for example, if the water level is equal to or higher than the M water level at which the electrode rods 272L and 272M are ON and the electrode rod H is OFF), and the boiler water temperature When the temperature detected by the sensor 42 is below the lower limit temperature and the pressure detected by the vapor pressure sensor 31 is below the set lower limit pressure, the water spray pump 41 is driven. As a result, the boiler water is allowed to flow while ensuring the protection of the water spray pump 41 and the safety of the boiler body 2 when there is a risk of freezing of the boiler water remaining in the device.

Furthermore, when the water level detected by the water level sensor 27 reaches the upper limit water level higher than the lower limit water level (for example, when the electrode rods 272L, 272M, and 272H are all ON and above the H water level), the anti-freezing control unit 92 Valve 51 is opened. As a result, when the water level rises during anti-freezing control, the water level of the water header 22 is maintained within an appropriate range by opening the blow valve 51 .

According to the steam generator 1 of the first embodiment described above, the following effects are obtained.

When a heat source fluid having a temperature exceeding 100° C. is introduced into the feed water heat exchanger 3, the make-up water may boil inside the feed water heat exchanger 3 if the flow velocity of the make-up water becomes low. Therefore, the steam generator 1 includes a feed water heat exchanger 3 that exchanges heat between the heat source fluid flowing through the heat source fluid discharge line L2 and the water flowing through the makeup water line L7, and the It includes a make-up water flow rate sensor 73 that detects the flow rate of water, and a control device 90 (water supply control section 91). The water supply controller 91 also controls the flow rate of makeup water supplied to the water header 22 so that the flow rate detected by the makeup water flow rate sensor 73 does not fall below a preset minimum flow rate. As a result, the minimum flow rate is set so that the temperature of the make-up water after heat exchange is less than 100°C even when heat is exchanged with the heat source fluid exceeding 100°C in the feed water heat exchanger 3. Thus, the make-up water can be prevented from boiling inside the feed water heat exchanger 3 .

The steam generator 1 is configured including a water level sensor 27 . The water supply controller 91 controls the flow rate of makeup water so that makeup water is supplied to the water header 22 at a first set flow rate larger than the minimum flow rate when the water level detected by the water level sensor 27 is below the first set water level. Control is performed so that when the water level detected by the water level sensor 27 becomes equal to or higher than the first set water level, makeup water is supplied to the water header 22 at a second set flow rate that is smaller than the first set flow rate and larger than the minimum flow rate. When the water level detected by the water level sensor 27 reaches or exceeds a second set water level higher than the first set water level, the blow valve 51 is opened. As a result, when the water level of the water header 22 is controlled by stepwise water level detection means using a plurality of electrode rods 272, while adjusting the flow rate of the makeup water according to the water level of the water header 22, the water level By supplying make-up water while opening the blow valve 51 when the flow rate becomes high, the steam generator 1 is operated while maintaining the minimum flow rate. Therefore, it is possible to prevent the make-up water from boiling inside the feed water heat exchanger 3 .

The steam generator 1 includes a water spray pump 41 , a boiler water temperature sensor 42 , and a steam pressure sensor 31 that detects the pressure inside the evaporation tank 21 . The control device 90 includes an anti-freezing control section 92, and the anti-freezing control section 92 performs the following controls (i) to (iii).
(i) When the temperature detected by the makeup water temperature sensor 74 is equal to or lower than the lower limit temperature, or when the water level detected by the water level sensor 27 is below the lower limit water level (below the M water level), the makeup water pump 71 is driven.
(ii) When the water level detected by the water level sensor 27 is equal to or higher than the lower limit water level (the M water level or higher), the temperature detected by the boiler water temperature sensor 42 is equal to or lower than the lower limit temperature, and the pressure detected by the steam pressure sensor 31 is equal to or lower than the lower limit pressure, water The spray pump 41 is driven.
(iii) When the water level detected by the water level sensor 27 is equal to or higher than the upper limit water level (H water level or higher), the blow valve 51 is opened.
As a result, in the operation (i), the make-up water staying inside the make-up water line L7 and the feed water heat exchanger 3 is forced to flow and is prevented from freezing. Further, in the operation (ii), the boiler water remaining in the device such as the water header 22 is forcibly flowed to prevent freezing. Also, in the operation of (iii), the water level of the water header 22 is maintained within an appropriate range. Therefore, when the steam generator 1 is stopped or on standby, frozen water can be prevented, and the heat source fluid can be supplied to quickly generate steam when there is a start command.

[Second embodiment]
Next, a steam generator 1A according to a second embodiment of the present invention will be described with reference to FIG. The steam generator 1A of the second embodiment differs from that of the first embodiment in the control of the water supply controller 91A. In the description of the second and subsequent embodiments, the same reference numerals are given to the same components, and the description thereof will be omitted or simplified.

In the second embodiment, the makeup water line L7 includes a motor valve 75 as pressure adjustment means, a second makeup water temperature sensor 76 as makeup water temperature detection means, and a makeup water pressure sensor 77 as pressure detection means. , are further arranged.
The motor valve 75 is arranged on the secondary side of the feed water heat exchanger 3 in the make-up water line L7. The motor valve 75 is a valve that can proportionally control the flow rate by adjusting the opening degree, and adjusts the pressure of the make-up water flowing through the feed water heat exchanger 3 by changing the opening degree.

The second make-up water temperature sensor 76 is arranged on the secondary side of the feed water heat exchanger 3 in the make-up water line L7. In this embodiment, the second makeup water temperature sensor 76 is arranged between the feed water heat exchanger 3 and the motor valve 5 . A second make-up water temperature sensor 76 detects the temperature of make-up water flowing out of the feed water heat exchanger 3 .
The make-up water pressure sensor 77 is arranged on the secondary side of the feed water heat exchanger 3 in the make-up water line L7. In this embodiment, the make-up water pressure sensor 77 is arranged between the feed water heat exchanger 3 and the motor valve 5 . The make-up water pressure sensor 77 detects the pressure of make-up water flowing through the feed water heat exchanger 3 .

In the second embodiment, the feed water controller 91A controls the opening of the motor valve 75 so that the pressure of the feed water flowing through the feed water heat exchanger 3 exceeds the saturated vapor pressure at the temperature detected by the second make up water temperature sensor 76. to control. Specifically, the water temperature and the saturated vapor pressure are associated and stored in the controller 90A. Then, the water supply control unit 91 calculates the saturated vapor pressure value of the makeup water corresponding to the detected temperature based on the detected temperature of the second makeup water temperature sensor 76, and the pressure detected by the makeup water pressure sensor 77 is calculated. The opening of the motor valve 75 is adjusted so as to exceed the saturated vapor pressure value. As a result, the pressure of the make-up water flowing into the feed water heat exchanger 3 can be made higher than the saturated vapor pressure corresponding to the temperature of the make-up water at the outlet of the feed water heat exchanger 3 . Therefore, it is possible to prevent the make-up water from boiling inside the feed water heat exchanger 3 .

The control of the opening degree of the motor valve 75 is not limited to the method described above. For example, the relationship between the opening of the motor valve 75 and the pressure of the make-up water is experimentally obtained in a state in which the make-up water is supplied at a predetermined flow rate, and the correspondence between the water temperature and the saturated vapor pressure is used to determine the make-up water and the degree of opening of the motor valve 75 at which the pressure of the make-up water exceeding the saturated vapor pressure can be obtained at that temperature may be associated and stored in the control device 90A (storage unit).
In this case, the water supply controller 91A controls the motor valve 75 based on the detected temperature of the second replenishing water temperature sensor 76 so that the opening degree corresponds to the detected temperature. This makes it possible to prevent the makeup water from boiling with a simple configuration that does not use the makeup water pressure sensor 77 .

When controlling the opening of the motor valve 75, the water supply controller 91A may also control the output of the makeup water pump 71 so that the flow rate of the makeup water is maintained.

According to the steam generator 1A of the second embodiment described above, in addition to the effects similar to those of the first embodiment, the following effects are also obtained.

When a heat source fluid having a temperature exceeding 100° C. is introduced into the feed water heat exchanger 3, the make-up water may boil inside the feed water heat exchanger 3 if the flow velocity of the make-up water becomes low. Therefore, the feed water control unit 91A controls the opening of the motor valve 75 so that the pressure of the make up water flowing through the feed water heat exchanger 3 exceeds the saturated vapor pressure at the temperature detected by the second make up water temperature sensor 76 . As a result, the pressure of the make-up water flowing into the feed water heat exchanger 3 can be made higher than the saturated vapor pressure corresponding to the temperature of the make-up water at the outlet of the feed water heat exchanger 3 . Therefore, it is possible to prevent the make-up water from boiling inside the feed water heat exchanger 3 .

[Third embodiment]
Next, a steam generator 1B according to a third embodiment of the invention will be described with reference to FIG. The steam generator 1B of the third embodiment differs from the first embodiment in that a water level sensor 27B that continuously detects the water level of the water header 22 is used as water level detection means. For the water level sensor 27B, for example, a capacitive water level sensor or a pressure sensor can be used.

In the third embodiment, the water level controller 91B controls the flow rate of makeup water so that the water level of the water header 22 reaches the set target water level. Here, the water level control unit 91B controls the flow rate of the make-up water so that the water level detected by the water level sensor 27B becomes a preset target water level within a range not lower than the minimum flow rate. Then, the blow valve 51 is opened when the detected flow rate of the makeup water flow rate sensor 73 reaches the minimum flow rate.

Further, the water level control unit 91B closes the blow valve 51 when the flow rate detected by the makeup water flow rate sensor 73 exceeds the minimum flow rate by a predetermined amount while the blow valve 51 is open. As a result, when the water level of the water header 22 is controlled by proportional control that controls the flow rate of make-up water according to the deviation between the target water level and the detected water level, the blow valve 51 is opened and the boiler water in the water header 22 is controlled. By adjusting the storage amount of , water level control is performed without making the flow rate of make-up water less than the minimum flow rate. Therefore, since the steam generator 1B is operated while maintaining the minimum flow rate, it is possible to prevent the make-up water from boiling inside the feed water heat exchanger 3.

Although preferred embodiments of the steam generator of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be modified as appropriate.
For example, in the first to third embodiments, the temperature of the boiler water is detected by the boiler water temperature sensor 42 arranged in the water spray line L4, but the present invention is not limited to this. For example, a boiler water temperature sensor may be arranged in the water header 22 to detect the temperature of the boiler water.

Further, in the first to third embodiments, the can body part 2 includes a plurality of evaporation tanks 21 and one water header 22, but the present invention is not limited to this. That is, the can body part 2 may be constructed by one evaporating tank and one water header, or the evaporating tank 21 and the water header 22 may be constructed by an integrated container. INDUSTRIAL APPLICABILITY The present invention can be suitably applied to a steam generator equipped with a so-called shell-and-tube evaporator.

1, 1A, 1B steam generator 3 feed water heat exchanger (heat exchanger)
21 Evaporation tank (evaporator)
22 water header 23 spray nozzle 27 water level sensor (water level detection means)
27B water level sensor (water level detection means)
31 vapor pressure sensor (internal pressure detection means)
41 water spray pump 42 boiler water temperature sensor (boiler water temperature detection means)
51 blow valve 71 make-up water pump 73 make-up water flow rate sensor (flow rate detection means)
74 make-up water temperature sensor (make-up water temperature detection means)
75 motor valve (pressure adjusting means)
76 second makeup water temperature sensor (makeup water temperature detection means)
77 make-up water pressure sensor (pressure detection means)
90, 90A, 90B Control device (control means)
101 tube L1 heat source fluid supply line L2 heat source fluid discharge line L4 water spray line L5 continuous blow line (blow line)
L7 make-up water line

Claims (6)

an evaporator in which a tube for circulating a heat source fluid and a spray nozzle for spraying boiler water on the tube are arranged inside a container;
a water header disposed below the evaporator and storing boiler water;
a water spray line that supplies boiler water in the water header to the spray nozzle;
a water spray pump provided in the water spray line;
a blow line for discharging boiler water from the water header;
a blow valve provided in the blow line;
a heat source fluid supply line that supplies heat source fluid to the tube;
a heat source fluid discharge line for discharging the heat source fluid that has flowed through the tube;
a make-up water line that supplies make-up water to the water header;
a makeup water pump provided in the makeup water line;
a heat exchanger that exchanges heat between the heat source fluid flowing through the heat source fluid discharge line and the make-up water flowing through the make-up water line;
Flow rate detection means for detecting the flow rate of makeup water flowing through the makeup water line;
A control means for controlling the flow rate of makeup water so that the flow rate detected by the flow rate detection means does not fall below a preset minimum flow rate,
The minimum flow rate is set to a flow rate at which the temperature of make-up water after heat exchange is less than 100°C even when heat is exchanged with a heat source fluid exceeding 100°C in the heat exchanger. . Further comprising water level detection means for detecting the water level of the water header,
The control means is
controlling the flow rate of makeup water so that makeup water is supplied at a first set flow rate larger than the minimum flow rate when the water level detected by the water level detection means is less than the first set water level;
Flow rate of make-up water so that make-up water is supplied at a second set flow rate smaller than the first set flow rate and larger than the minimum flow rate when the water level detected by the water level detection means is equal to or higher than the first set water level. to control the
2. The steam generator according to claim 1, wherein the blow valve is opened when the water level detected by the water level detection means is equal to or higher than a second set water level higher than the first set water level. Further comprising water level detection means for detecting the water level of the water header,
The control means is
controlling the flow rate of make-up water so that the water level detected by the water level detection means reaches a preset target water level within the range not below the minimum flow rate;
2. The steam generator according to claim 1, wherein the blow valve is opened when the flow rate detected by the flow rate detection means reaches the minimum flow rate. an evaporator in which a tube for circulating a heat source fluid and a spray nozzle for spraying boiler water on the tube are arranged inside a container;
a water header disposed below the evaporator and storing boiler water;
a water spray line that supplies boiler water in the water header to the spray nozzle;
a water spray pump provided in the water spray line;
a blow line for discharging boiler water from the water header;
a blow valve provided in the blow line;
a heat source fluid supply line that supplies heat source fluid to the tube;
a heat source fluid discharge line for discharging the heat source fluid that has flowed through the tube;
a make-up water line that supplies make-up water to the water header;
a makeup water pump provided in the makeup water line;
a heat exchanger that exchanges heat between the heat source fluid flowing through the heat source fluid discharge line and the make-up water flowing through the make-up water line;
make-up water temperature detection means for detecting the temperature of make-up water flowing out of the heat exchanger;
pressure regulating means for regulating the pressure of make-up water flowing through the heat exchanger, the proportionally controllable valve located on the secondary side of the heat exchanger ;
and a control means for controlling the degree of opening of the valve so that the pressure of the make-up water flowing through the heat exchanger exceeds the saturated vapor pressure at the temperature detected by the make-up water temperature detection means. A pressure detection means for detecting the pressure of make-up water flowing through the heat exchanger,
5. The steam generator according to claim 4, wherein the control means controls the degree of opening of the valve so that the pressure detected by the pressure detection means exceeds the saturated vapor pressure at the temperature detected by the makeup water temperature detection means. Boiler water temperature detection means for detecting the temperature of boiler water;
internal pressure detection means for detecting the pressure inside the evaporator;
makeup water temperature detection means for detecting the temperature of makeup water;
a water level detection means for detecting the water level of the water header;
further comprising
The control means is
further comprising an anti-freeze control unit that operates the steam generator in an anti-freeze mode when activation of the steam generator is stopped,
The anti-freeze control unit is
(i) driving the makeup water pump when the temperature detected by the makeup water temperature detection means is equal to or lower than a preset lower limit temperature, or when the water level detected by the water level detection means is less than the preset lower limit water level;
(ii) When the water level detected by the water level detection means is equal to or higher than the lower limit water level, the temperature detected by the boiler water temperature detection means is equal to or lower than the lower limit temperature, and the pressure detected by the internal pressure detection means is equal to or lower than a preset lower limit pressure. to drive the water spray pump,
(iii) The steam generator according to claim 1 or 4 , wherein the blow valve is opened when the water level detected by the water level detection means is equal to or higher than the upper limit water level higher than the lower limit water level.

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