JP5712636B2 - Once-through boiler - Google Patents

Description

  The present invention relates to a once-through boiler.

  As a boiler that generates steam, a once-through boiler including a can body in which a plurality of liquid pipes are connected between an upper header and a lower header is generally used. In the once-through boiler, steam generated by heating the liquid pipe is taken out from the upper header and sent to the load side. The steam taken out from the upper header is mixed with canned water, and the steam mixed with canned water becomes a steam with much moisture and poor quality.

Therefore, the once-through boiler is generally provided with a gas-liquid separator that separates a liquid component (mainly moisture) from the steam taken out from the upper header. If the liquid level in this gas-liquid separator (hereinafter also referred to as “separator liquid level”) is too high, canned water is likely to be entrained in the generated steam, and the degree of dryness of the steam is reduced. On the other hand, if the separator liquid level is too low, the ability of the gas-liquid separator is sufficiently exerted to obtain dry and high-quality steam, but it is also assumed that the liquid level in the liquid pipe is low.
When the liquid level in the liquid pipe is low, the position of bubbles generated in the liquid pipe is lowered. If a water film is not formed on the upper part of the liquid pipe, the upper part of the liquid pipe is overheated by the flame and melts.

  Therefore, the liquid level in the gas-liquid separator is kept constant in order to control the increase of the can water mixed with the generated steam and to control the liquid level in the liquid pipe to the extent that a water film is formed in the header part of the liquid pipe. The level is controlled to such a level.

  As a means for controlling the liquid level in the gas-liquid separator to a certain level, the liquid level (separator liquid level) in the gas-liquid separator is detected, and canned water is supplied into the liquid pipe based on the detected liquid level. A control method for turning the pump on and off is known. Such a separator liquid level control method sets the upper limit liquid level and the lower limit liquid level to the liquid level of the gas-liquid separator, turns off the feed pump when the upper limit liquid level is detected, and sets the lower limit liquid level. In this method, the liquid feed pump is turned on when detected, and the liquid level of the gas-liquid separator is always kept between the upper limit liquid level and the lower limit liquid level (see, for example, Patent Document 1).

In addition, if the liquid level in the gas-liquid separator is too high, the water accumulated in the gas-liquid separator is entrained by the steam, resulting in steam containing moisture, that is, steam with a low dryness. For this reason, the upper liquid level is set slightly lower than a liquid level that is high enough to prevent water accumulated in the gas-liquid separator from being entrained by the vapor (this liquid level is also called “dryness limit liquid level”). .
Thus, in the once-through boiler, the liquid level in the gas-liquid separator is controlled to a certain level.

JP 2003-294204 A

  By the way, in the once-through boiler, it is necessary to control the height of the liquid level in the liquid pipe of the can body (hereinafter also referred to as “liquid level in the can”) in accordance with the combustion amount of the burner. For example, when increasing the burn rate of the burner to increase the steam velocity, the liquid level in the can is lowered. On the other hand, when the burn rate of the burner is decreased to lower the steam speed, the liquid level in the can is increased.

However, the technique of controlling the separator liquid level constant according to the combustion amount of the boiler, that is, the evaporation rate, has the following problems, for example.
As described above, the separator liquid level is set slightly lower than the upper limit liquid level. If the burner combustion amount is rapidly increased, the separator liquid level becomes higher than the upper limit liquid level, and as a result, the dryness of the steam cannot be ensured. Therefore, it is necessary to burn the boiler while suppressing the rate of increase in the combustion amount (also referred to as “burning transition speed” or the like) so that the separator liquid level does not become higher than the upper limit liquid level.

  Therefore, when increasing the combustion amount of the boiler, it is difficult to increase the combustion amount of the boiler at a high increase rate. Therefore, it has been desired to increase the combustion amount of the boiler at a high increase rate.

  On the other hand, for example, when the liquid level in the gas-liquid separator is adjusted to a state where the vapor velocity is high, the upper limit liquid level in the gas-liquid separator is set low, and as a result, when the vapor velocity becomes low, that is, When reducing the combustion amount of the boiler, even if the liquid level in the gas-liquid separator is at the upper limit liquid level, there is a possibility that the upper part of the liquid pipe may be damaged by the flame.

  Therefore, when reducing the combustion amount of the boiler, it is difficult to reduce the combustion amount of the boiler with a high reduction rate. Therefore, it has been desired to reduce the combustion amount of the boiler with a high reduction rate.

  An object of the present invention is to provide a once-through boiler capable of increasing the combustion amount of a boiler with a high increase rate and reducing the combustion amount of the boiler with a high decrease rate.

The present invention relates to a can body in which a plurality of liquid pipes are connected between an upper header and a lower header, a burner that heats the liquid pipe with a variable combustion amount, and a combustion amount in the burner is controlled. Combustion amount control means, a gas-liquid separator connected between the upper header and the lower header, and a separator liquid for controlling a separator liquid level which is a liquid level in the gas-liquid separator The separator liquid level control means increases the separator liquid level when the combustion amount is increased by the combustion amount control means, and the separation when the rate of increase in the combustion amount is small. When the increase rate of the combustion amount is larger than the increase rate of the separator liquid level, the increase rate of the separator liquid level is increased, and when the combustion amount is decreased by the combustion amount control means, the separator liquid level is decreased. And the separator when the reduction rate of the combustion amount is small Than-position of reduced rate for once-through boiler to increase the reduction rate of the separator liquid level in the case of a large reduction rate of the combustion amount.

  Further, when the combustion amount control means increases the combustion amount, the time required for increasing the combustion amount is set so that the liquid amount in the liquid pipe becomes shorter than the time required for evaporation as the combustion amount increases. It is preferable to increase the combustion amount.

  Further, when the combustion amount control means increases the combustion amount, the time required for the increase in the combustion amount is such that the amount of liquid in the liquid pipe becomes longer than the time required for evaporation as the combustion amount increases. It is preferable to increase the combustion amount.

  Moreover, it is preferable that the lower limit value of the separator liquid level substantially coincides with the liquid level in the liquid pipe corresponding to the burner combustion amount corresponding to the lower limit value.

  In addition, the gas-liquid separator has a vertical cylindrical shape, a cylinder having a vapor outlet pipe at the top and a separation liquid outlet pipe at the bottom, and a horizontal cylinder, tangential to the peripheral side wall of the cylinder The steam inlet pipe connected to the steam inlet pipe, the steam introduced from the steam inlet pipe into the barrel, and the liquid separated by the swirling of the steam inside the barrel so as not to collide with each other. A guide plate provided in a steam introduction portion through which steam is introduced from the inlet pipe to the inside of the cylinder, and the guide plate so that the liquid does not jump up when the vapor introduced from the steam inlet pipe collides with the cylinder. It is preferable to have a lid plate disposed on the top of the.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to increase the combustion amount of a boiler with a high increase rate, the once-through boiler which can reduce the combustion amount of a boiler with a high reduction rate can be provided.

It is a schematic block diagram which shows the once-through boiler 1 of this embodiment. FIG. 3 is a partial cross-sectional front view showing a liquid level detection electrode rod 20 in the separator liquid level detection device 13 of the once-through boiler 1. 2 is a longitudinal sectional view showing a gas-liquid separator 2. FIG. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. 3 is a schematic perspective view showing an internal structure of the gas-liquid separator 2. FIG. It is a figure which shows typically the liquid level in each of the gas-liquid separator 2 and the can 10 in a high combustion mode. It is a figure which shows typically the liquid level in each of the gas-liquid separator 2 and the can 10 in a low combustion mode. It is a figure which shows typically the change of the liquid level in each of the gas-liquid separator 2 and the can 10 in a high combustion mode and a low combustion mode.

  Hereinafter, a once-through boiler 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a once-through boiler 1 of the present embodiment. FIG. 2 is a partial cross-sectional front view showing the liquid level detection electrode rod 20 in the separator liquid level detection device 13 of the once-through boiler 1.

As shown in FIG. 1, the once-through boiler 1 of the present embodiment includes a can body 10 in which a plurality of liquid pipes 3 are connected between an upper header 8 and a lower header 6, and the liquid pipe 3 is variable. A burner 24 heated by the combustion amount, a combustion amount control unit 25 as a combustion amount control means for controlling the combustion amount in the burner 24, and a gas-liquid connected between and communicated with the upper header 8 and the lower header 6. A separator 2 and a separator liquid level control unit 12 as a separator liquid level control means for controlling a liquid level (also referred to as “separator liquid level”) in the gas-liquid separator 2 are provided.
The “liquid pipe” is generally called a “water pipe”. The “gas / liquid separator” is also generally called a “gas / water separator”. The “liquid level” is also generally called “water level”.

  The can body 10 is connected to a plurality of liquid pipes 3 erected at predetermined intervals in the circumferential direction, and to the lower ends of the plurality of liquid pipes 3. Mainly water) is introduced and supplied to the plurality of liquid pipes 3. The lower header 6 is connected to the upper ends of the plurality of liquid pipes 3. The steam generated in the plurality of liquid pipes 3 is collected and the steam inlet pipe 7. And the combustion chamber 9 formed by being surrounded by a plurality of liquid pipes 3.

  The burner 24 heats the liquid pipe 3 with a variable combustion amount. In the present embodiment, the burner 24 steps the combustion amount into three stages of “high combustion mode” (output 100%), “low combustion mode” (output 20%), and “stop mode” (output 0%). And the liquid tube 3 is heated.

  The burner 24 is provided in the central part of the upper header 8 so that a flame can be emitted downward. The burner 24 is supplied with fuel and combustion air. By operating the burner 24, fuel is burned in the can 10. The combustion gas exchanges heat with the liquid (mainly water) inside each liquid pipe 3, and is discharged from a flue (not shown) as exhaust gas. During this time, the combustion gas exchanges heat with the liquid inside each liquid pipe 3 to heat the liquid inside each liquid pipe 3. Thereby, steam can be taken out from the upper header 8. The steam is sent to the gas-liquid separator 2, and after the dryness is improved, it is sent to a load side such as a steam use facility (not shown).

  The gas-liquid separator 2 performs gas-liquid separation on the steam discharged from the can body 10. The gas-liquid separator 2 is connected and communicated between the upper header 8 and the lower header 6. Details of the gas-liquid separator 2 will be described later.

A gas-liquid separator 2 is connected to the steam inlet pipe 7. The steam inlet pipe 7 is a pipe for sending steam to the load side via the gas-liquid separator 2, and is connected to the upper header 8.
The gas-liquid separator 2 and the lower header 6 are connected by a separation liquid outlet pipe 11. As a result, the liquid component (mainly moisture) separated from the vapor in the gas-liquid separator 2 is returned to the lower header 6 via the separation liquid outlet pipe 11.

  A separator liquid level detection device 13 is connected to the gas-liquid separator 2 via an upper communication pipe 27 and a lower communication pipe 28. The separator liquid level detection unit 13 is electrically connected to the separator liquid level control unit 12 via the liquid level detection unit 23 of the separator liquid level detection device 13.

  The separator liquid level detection device 13 detects the liquid level in the gas-liquid separator 2. The separator liquid level detection device 13 includes a metal container 19 connected to the gas-liquid separator 2, a liquid level detection electrode rod 20 attached to the container 19, and a liquid level detection unit 23. . As shown in FIGS. 1 and 2, the separator liquid level detection device 13 includes a metal container 19 connected to the gas-liquid separator 2 and a liquid level detection electrode portion 21 ( The liquid level (separator liquid level) in the gas-liquid separator 2 is detected by energizing between the gas and the liquid.

The container 19 communicates with the gas-liquid separator 2 via the upper communication pipe 27 and communicates with the separation liquid outlet pipe 11 via the lower communication pipe 28.
The liquid level detection electrode rod 20 is attached to the container 19. The liquid level detection electrode rod 20 is configured by forming an insulating coating 22 serving as a dielectric on the surface of the liquid level detection electrode portion 21.

  The liquid level detection unit 23 measures the electrostatic capacitance generated between the liquid level detection electrode unit 21 and the container 19 by energizing the liquid level detection electrode unit 21 and the container 19, and measures the static The electric capacity is converted into a liquid level, and the liquid level inside the container 19 is detected. The liquid level detection unit 23 transmits the detected liquid level to the separator liquid level control unit 12.

  The liquid level detection electrode bar 20 is an electrode bar for detecting the liquid level inside the container 19. The liquid level detection electrode rod 20 has an external power connection terminal portion 29 on one end side and a liquid level detection electrode portion 21 on the other end side. The liquid level detection electrode rod 20 is held in the container 19 via a cylindrical insulator 30. The external power connection terminal portion 29 is attached to the container 19 through the insulator 30 so as to protrude upward from the container 19. Further, the liquid level detection electrode portion 21 is attached to the container 19 so as to protrude inside the container 19 through the insulator 30.

  The liquid level detection electrode part 21 is formed from a stainless alloy. The insulating coating 22 is formed on the surface of the liquid level detection electrode unit 21 and becomes a dielectric. The insulating coating 22 is formed of an engineering plastic having high heat resistance, high pressure resistance, and chemical resistance.

  As the engineering plastic, a ketone synthetic resin material such as polyether ether ketone, polyether ketone, polyether ketone ketone, polyallyl ether ketone or the like is used, and polyether ether ketone having high heat resistance is particularly preferable.

  The liquid level detection unit 23 is mainly configured by a power source 34, a measurement circuit unit 35, and a liquid level detection circuit unit 36. The liquid level detection unit 23 is connected to the power supply circuit in which one of the power sources 34 is connected to the external power connection terminal 29 of the liquid level detection electrode rod 20 and the other side of the power source 34 is connected to the container 19. The position detection circuit unit 36 is connected.

The power source 34 is composed of an AC power source.
The measurement circuit unit 35 measures the capacitance between the liquid level detection electrode unit 21 and the container 19 by energization using the insulating coating 22 formed on the surface of the liquid level detection electrode unit 21 as a dielectric.
The liquid level detection circuit unit 36 includes a memory that stores a conversion relationship between a preset capacitance and a liquid level inside the container 19, and is measured by the measurement circuit unit 35 based on the conversion relationship. A program for converting the capacitance into the liquid level inside the container 19 is provided.

  Liquid supply (liquid supply) is not directly performed on the gas-liquid separator 2, the liquid inside the liquid pipe 3 of the can body 10 evaporates, and the liquid is in a wet vapor state. The gas-liquid separator 2 performs gas-liquid separation, so that the separated liquid (mainly water) is supplied.

Therefore, the separator liquid level control unit 12 mainly controls the amount of liquid supplied to the liquid pipe 3 of the can body 10 by a liquid supply amount control unit 18 (described later), and at the burner 24 by the combustion amount control unit 25. By controlling the combustion amount, the liquid level (increase / decrease) in the gas-liquid separator 2 is controlled.
A liquid supply amount control unit 18 and a combustion amount control unit 25 are electrically connected to the separator liquid level control unit 12. The separator liquid level control unit 12 is electrically connected to the liquid level detection circuit unit 36 of the liquid level detection unit 23, the in-can liquid level detection unit 26, the combustion amount detection unit 16, and the vapor pressure detection unit 17. ing.

The liquid supply amount control unit 18 supplies liquid to the lower header 6 of the can body 10 through the liquid supply tube 5 based on the instruction signal from the separator liquid level control unit 12. To control.
The combustion amount control unit 25 controls the burner 24 to increase or decrease the combustion amount based on the instruction signal from the separator liquid level control unit 12.
The separator liquid level control unit 12 increases the separator liquid level when the combustion amount control unit 25 increases the combustion amount, and also increases the separator liquid level when the combustion amount control unit 25 decreases the combustion amount. Decrease.

  In addition, when the combustion amount control unit 25 increases the combustion amount, the separator liquid level control unit 12 increases or decreases the increase rate of the separator liquid level according to the increase rate of the combustion amount. Further, when the combustion amount control unit 25 decreases the combustion amount, the separator liquid level control unit 12 increases or decreases the decrease rate of the separator liquid level according to the decrease rate of the combustion amount.

  For example, the separator liquid level control unit 12 has a lower combustion than the rate of increase in the combustion amount when shifting from the stop mode (output 0%) to the low combustion mode (output 20%) (stop → low combustion transition). When the rate of increase in the combustion amount in the transition from the mode (20% output) to the high combustion mode (100% output) is low (during the transition from low combustion to high combustion), the increase rate of the combustion amount is small, “stop → “In the transition from low combustion to high combustion” (100% −20% = 80), the increase rate of the combustion amount is larger than the increase rate of the separator liquid level in “low combustion transition” (20% −0% = 20%). %) Increase the separator liquid level increase rate.

  Similarly, the separator liquid level control unit 12 is higher than the rate of decrease in the combustion amount when shifting from the low combustion mode (output 20%) to the stop mode (output 0%) (from low combustion to stop). When the reduction rate of the combustion amount in the transition from the combustion mode (output 100%) to the low combustion mode (output 20%) (from high combustion to low combustion transition) is larger, the reduction rate of the combustion amount is small “low “High combustion → low combustion transition” (100% −20% = 100% −20%), which is larger than the reduction rate of the separator liquid level in “combustion → stop transition” (20% −0% = 20%) The reduction rate of the separator liquid level at 80% is increased.

  Further, when the combustion amount control unit 25 increases the combustion amount, the time required to increase the combustion amount is set so that the liquid amount in the liquid pipe 3 becomes longer than the time required for evaporation as the combustion amount increases. , Increase the amount of combustion. For example, when the combustion amount control unit 25 shifts from the low combustion mode to the high combustion mode (at the time of transition from low combustion to high combustion), the time required to increase the combustion amount, that is, the transition from the low combustion mode to the high combustion mode. The amount of combustion is increased so that the amount of time required (for example, 30 seconds) becomes longer than the amount of time required for evaporation (for example, 25 seconds) as the amount of combustion increases.

  Further, when the combustion amount control unit 25 increases the combustion amount, the time required to increase the combustion amount is set so that the liquid amount in the liquid pipe 3 becomes shorter than the time required for evaporation as the combustion amount increases. , Increase the amount of combustion. For example, when the combustion amount control unit 25 shifts from the low combustion mode to the high combustion mode (at the time of transition from low combustion to high combustion), the time required to increase the combustion amount, that is, the transition from the low combustion mode to the high combustion mode. The amount of combustion is increased so that the amount of time required (for example, 25 seconds) becomes shorter than the amount of time required for evaporation (for example, 30 seconds) as the amount of combustion increases.

  The in-can liquid level detection unit 26 is provided in communication with the upper header 8 and the lower header 6. The in-can liquid level detection unit 26 has a hollow container formed of a conductive material, and is connected to the upper header 8 at the upper part and to the lower header 6 at the lower part. On the upper wall of the in-can liquid level detection unit 26, upper portions of a plurality of electrode rods (not shown) having different lengths are respectively held via insulating materials (not shown). In this way, a plurality of electrode rods are inserted and held in the in-can liquid level detection unit 26 with their lower end portions having different height positions. The in-can liquid level detector 26 and the plurality of electrode bars constitute an electrode type liquid level detector.

  Each electrode rod is connected to the separator liquid level control unit 12, and the in-can liquid level detection unit 26 is grounded. Therefore, if each electrode rod has its lower end immersed in water, electrical continuity with the in-can liquid level detection unit 26 is ensured. Thereby, the separator liquid level control part 12 detects whether there is a liquid level in the lower end part of each electrode bar by the presence or absence of the electric current which flows into each electrode bar. And the separator liquid level control part 12 controls the once-through boiler 1 based on the presence or absence of the detection of the liquid level in a can by each electrode rod.

The combustion amount detection unit 16 detects the combustion amount of the burner 24 and transmits the detection signal to the separator liquid level control unit 12. In the detection of the combustion amount by the combustion amount detection unit 16, the “combustion amount” can be replaced with the amount of fuel supplied to the combustion device. Therefore, the fuel amount may be detected as the combustion amount.
The steam pressure detection unit 17 detects the steam pressure generated in the can 10 and transmits the detection signal to the separator liquid level control unit 12.

  Next, details of the configuration of the gas-liquid separator 2 will be described with reference to the drawings. FIG. 3 is a longitudinal sectional view showing the gas-liquid separator 2. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a schematic perspective view showing the internal structure of the gas-liquid separator 2.

  The gas-liquid separator 2 is a centrifugal separator, and, as shown in FIGS. 3 to 6, a vertically-oriented cylindrical barrel 115, a steam inlet pipe 7 provided on a peripheral side wall of the barrel 115, a barrel A steam outlet pipe 117 provided at the upper part of 115, a separation liquid outlet pipe 11 provided at the lower part of the cylinder 115, a guide plate 119 provided at a steam introducing portion from the steam inlet pipe 7 into the cylinder 115, and this guide A cover plate 120 provided on the upper portion of the plate 119 and a baffle plate 121 provided on the lower portion inside the trunk 115 are provided.

The body 115 has a cylindrical shape in which end plates 122 and 123 are provided at upper and lower openings. The trunk | drum 115 is arrange | positioned along the axis line in the up-down direction. The upper end plate 122 is formed in a gently spherical shape that bulges upward.
The steam outlet pipe 117 has a circular tube shape and is provided so as to extend upward at the center of the upper end plate 122. The lower end plate 123 is formed in a gentle spherical shape that bulges downward. At the center of the lower end plate 123, a circular separation liquid outlet pipe 11 is provided extending downward.

  The steam inlet pipe 7 has a cylindrical shape with a diameter smaller than that of the trunk 115 and is disposed along the axis thereof in the left-right direction. The steam inlet pipe 7 is connected to the peripheral side wall of the cylinder 115 at the center in the vertical direction of the cylinder 115. The steam inlet pipe 7 is connected to the peripheral side wall of the cylinder 115 by inserting one end of the steam inlet pipe 7 into the cylinder 115.

  One end of the steam inlet pipe 7 in the axial direction has an obliquely cut shape as shown in FIG. Specifically, one end portion in the axial direction of the steam inlet pipe 7 has a shape inclined backward as it goes to one end side in the axial direction.

  The steam inlet pipe 7 is connected to the peripheral side wall of the cylinder 115 by inserting one end portion of the inclined axis direction into the cylinder 115. At one end in the axial direction of the steam inlet pipe 7, the rear end of the peripheral side wall is disposed at the rear end of the peripheral side wall of the trunk 115. Specifically, in the steam inlet pipe 7, the outer surface of the inclined tip portion (the portion that extends most to the one axial end side due to the inclination) 125 is the rear inner peripheral surface of the central portion in the left-right direction of the trunk 115. Arranged in contact. In this state, the front end portion of the peripheral side wall is disposed at the center portion in the front-rear direction of the peripheral side wall of the trunk 115 at one end portion in the axial direction of the steam inlet pipe 7. Specifically, the inclined base end portion 126 in the steam inlet pipe 7 is disposed at the center in the front-rear direction of the peripheral side wall of the trunk 115.

Steam from the can 10 is introduced into the barrel 115 through the steam inlet pipe 7 in a tangential direction.
The steam outlet pipe 117 is a circular tube having a smaller diameter than that of the trunk 115, and its axis is arranged in the vertical direction. The lower end portion of the steam outlet pipe 117 is connected to the central portion of the end plate 122 on the upper side of the trunk 115.
The separation liquid outlet pipe 11 is an elongated circular tube having a diameter smaller than that of the trunk 115, and its axis is arranged in the vertical direction. The upper end portion of the separation liquid outlet pipe 11 is connected to the center portion of the end plate 123 on the lower side of the trunk 115.

  The guide plate 119 is a substantially rectangular plate material and is disposed with its plate surface facing forward and backward. As shown in FIG. 4, the guide plate 119 is curved so as to bulge backward. The vertical height of the guide plate 119 is the same as the outer diameter of the steam inlet pipe 7 as shown in FIG. The guide plate 119 is installed at a height corresponding to the steam inlet pipe 7.

  As described above, the guide plate 119 is curved so as to bulge backward in plan view. This curved shape is set as appropriate, but in the present embodiment, as shown in FIG. Specifically, the guide plate 119 is an inclined base end portion formed at one end portion in the axial direction of the steam inlet pipe 7 (a connection portion between the front end portion of the peripheral side wall of the steam inlet pipe 7 and the peripheral side wall of the trunk 115). From 126, it extends rearward as it goes inward of the trunk 115, and is then curved in an arc shape so as to wrap forward from the center in the left-right direction of the trunk 115. In the plan view shown in FIG. 4, the end portion on the extending side of the guide plate 119 has a shape corresponding to the wraparound from behind the separation liquid outlet pipe 11.

  The cover plate 120 is a substantially semicircular plate material, and is horizontally disposed on the upper end edge of the guide plate 119 with its plate surface facing up and down. Specifically, as shown in FIGS. 4 and 6, the cover plate 120 is provided on the rear half periphery of the trunk 115 in a plan view, and is provided to extend rearward from the upper end edge of the guide plate 119. In this way, as shown in FIG. 3, the cover plate 120 has a gap between the upper end portion of the guide plate 119 and the rear portion of the peripheral side wall of the trunk 115 at a height corresponding to the upper end portion of the peripheral side wall of the steam inlet pipe 7. It is provided in the rear half circumference part of the trunk | drum 115 so that it may block | close.

  The baffle plate 121 is a substantially disk-shaped plate material, and is horizontally disposed at a lower portion inside the trunk 115 with its plate surface facing up and down. Specifically, the baffle plate 121 has a disk shape having a slightly smaller diameter than the inner diameter of the trunk 115. Arc-shaped notches 134 are formed on the outer peripheral portion of the baffle plate 121 at equal intervals in the circumferential direction. In the present embodiment, four notches 134 are formed on the outer peripheral portion. On the bottom surface of the baffle plate 121, a plate material is erected in a cross shape and a leg portion 135 is provided. The lower end portion of the leg portion 135 has a shape corresponding to the arc of the lower end plate 123.

  Since the gas-liquid separator 2 has such a configuration, the baffle plate 121 can be stably held horizontally by the legs 135 at the upper portion of the lower end plate 123. In this way, the baffle plate 121 is provided at a position spaced slightly above the upper opening without blocking the upper opening of the separation liquid outlet pipe 11. Further, the upper and lower sides of the baffle plate 121 are communicated with each other by a notch 134 formed in the outer peripheral portion of the baffle plate 121.

  The once-through boiler 1 of the present embodiment controls (increases or decreases) the liquid level (separator liquid level) in the gas-liquid separator 2 as follows, for example. FIG. 7 is a diagram schematically showing liquid levels in the gas-liquid separator 2 and the can body 10 in the high combustion mode. FIG. 8 is a diagram schematically showing liquid levels in the gas-liquid separator 2 and the can body 10 in the low combustion mode. FIG. 9 is a diagram schematically showing changes in the liquid level in the gas-liquid separator 2 and the can body 10 in the high combustion mode and the low combustion mode.

  During the operation of the once-through boiler 1, the can water inside the liquid pipe 3 heated by the burner 24 evaporates. The steam thus generated is taken out from the upper header 8 and introduced into the gas-liquid separator 2 via the steam inlet pipe 7, and moisture (liquid component) in the steam is separated in the gas-liquid separator 2. . The separated water is sequentially returned to the lower header 6 via the separation liquid outlet pipe 11 while accumulating inside the gas-liquid separator 2.

  In the present embodiment, the liquid level detector 23 of the separator liquid level detector 13 detects the liquid level in the gas-liquid separator 2, and the in-can liquid level detector 26 is connected to the liquid tube 3 of the can body 10. The internal liquid level is detected, the combustion amount detection unit 16 detects the combustion amount in the burner 24, and the steam pressure detection unit 17 detects the steam pressure generated in the can 10. Various information signals detected by the liquid level detection unit 23, the in-can liquid level detection unit 26, the combustion amount detection unit 16, and the steam pressure detection unit 17 are transmitted to the separator liquid level control unit 12.

  The detection of the liquid level in the gas-liquid separator 2 by the separator liquid level detection device 13 is performed as follows. When current is passed between the external power connection terminal portion 29 of the liquid level detection electrode rod 20 and the container 19, it is formed on the surface of the liquid level detection electrode portion 21 when the liquid level detection electrode portion 21 is in contact with water. The insulating coating 22 thus made becomes a dielectric, and the contact portion of the liquid level detection electrode portion 21 that contacts water in the container 19 becomes a capacitor. Then, by energizing between the external power supply connection terminal portion 29 of the liquid level detection electrode rod 20 and the container 19, the capacitance between the liquid level detection electrode portion 21 and the container 19 is measured by the measurement circuit unit 35. The measured electrostatic capacity is converted into a liquid level by the liquid level detection circuit 36 and detected, and the change in the liquid level due to the change in the electrostatic capacity is detected in an analog manner.

The separator liquid level control unit 12 increases the separator liquid level when the combustion amount control unit 25 increases the combustion amount, and also increases the separator liquid level when the combustion amount control unit 25 decreases the combustion amount. Decrease position.
Specifically, the separator liquid level control unit 12 sends the liquid supply amount control unit 18 and the combustion amount control unit 25 to increase the separator liquid level when the combustion amount control unit 25 increases the combustion amount. The instruction signal is transmitted. Further, the separator liquid level control unit 12 instructs the liquid supply amount control unit 18 and the combustion amount control unit 25 to decrease the separator liquid level when the combustion amount control unit 25 decreases the combustion amount. Send a signal.

  As described above, according to the separator liquid level detection device 13, the change in the liquid level in the gas-liquid separator 2 can be detected in an analog manner. Therefore, the separator liquid level control unit 12 can adjust the liquid level steplessly, and therefore, can control the degree of dryness of the steam steplessly, and therefore can suppress drain water.

  The liquid supply amount control unit 18 controls the liquid supply amount by the liquid supply pump 4 based on the instruction signal from the separator liquid level control unit 12. The combustion amount control unit 25 controls the combustion amount in the burner 24 based on the instruction signal from the separator liquid level control unit 12.

When increasing the separator liquid level, the amount of liquid supplied to the can body 10 by the liquid supply pump 4 is increased and the amount of combustion in the burner 24 is increased. As a result, the liquid inside the liquid tube 3 of the can body 10 (schematically shown by right-down hatching in FIG. 7) evaporates, and the liquid (in FIG. As a result, the liquid level in the gas-liquid separator 2 (separator liquid level) increases to a liquid level H22 set slightly lower than the dryness limit liquid level H23. To do.
The difference h1 (= H22−H11) between the liquid level H22 and the liquid level H11 corresponds to the difference (P0−P1) between the pressure P0 inside the can 10 and the pressure P1 inside the gas-liquid separator 2.

  On the other hand, when decreasing the separator liquid level, the amount of liquid supplied to the can body 10 by the liquid supply pump 4 is decreased and the amount of combustion in the burner 24 is decreased. As a result, the liquid inside the liquid pipe 3 of the can body 10 (schematically indicated by right-down hatching in FIG. 8) evaporates, and the liquid (in FIG. 8) is introduced into the gas-liquid separator 2 in the state of wet steam. As a result, the liquid level in the gas-liquid separator 2 (separator liquid level) is a lower limit H21 (the upper part of the liquid pipe is not damaged by the flame caused by the burner 24). It decreases to <H22).

  At this time, as shown in FIG. 8, the lower limit value H21 of the separator liquid level and the liquid level (liquid level in the can) H12 in the liquid pipe 3 corresponding to the combustion amount of the burner 24 corresponding to the lower limit value H21 It almost agrees. Here, “substantially match” means that the difference between the lower limit value H21 of the separator liquid level and the liquid level (liquid level in the can) H12 in the liquid pipe 3 is within 100 mm, preferably within 50 mm. That means.

Here, with reference to FIG. 9, the movement of the liquid (water) between the liquid pipe 3 of the can 10 and the gas-liquid separator 2 will be schematically described.
Here, in the low combustion mode (output 20%), the liquid level of the can 10 (liquid level in the can) is H12, and the liquid level of the gas-liquid separator 2 (separator liquid level) is H21. To do.

  When shifting from the low combustion mode to the high combustion mode (output 100%) (at the time of transition from low combustion to high combustion), evaporation of the liquid inside the liquid pipe 3 proceeds more than the amount of liquid supplied to the can 10. The liquid level (in-can liquid level) of the can body 10 decreases from H12 to H11. Further, the liquid inside the liquid pipe 3 evaporates and moves to the gas-liquid separator 2 in the state of wet steam. Thereby, the liquid level (separator liquid level) of the gas-liquid separator 2 increases from H21 to H22 near the dryness limit liquid level H23.

  In other words, according to the once-through boiler 1 of the present embodiment, when the low combustion mode is shifted to the high combustion mode, the difference in the liquid level (separator liquid level) of the gas-liquid separator 2 (H22−H21) is accommodated. By using the space (volume) as a buffer space, the separator liquid level can be increased (H21 → H22) and the dryness of the vapor can be maintained. Therefore, according to the once-through boiler 1 of this embodiment, the combustion amount of the burner 24 can be increased at a high increase rate.

On the other hand, in the high combustion mode (output 100%), the liquid level (in-can liquid level) of the can body 10 is H11, and the liquid level (separator liquid level) of the gas-liquid separator 2 is H22. .
When shifting from the high combustion mode to the low combustion mode (output 20%) (at the time of transition from high combustion to low combustion), the liquid level of the can 10 (liquid level in the can) due to a decrease in the evaporation progress in the liquid inside the liquid pipe 3 The liquid is supplied to the can body 10 and the liquid level in the can increases from H11 to H12. In addition, the amount of liquid that moves inside the liquid pipe 3 to the gas-liquid separator 2 is reduced, whereby the liquid level of the gas-liquid separator 2 (separator liquid level) is the dryness limit liquid level H23. Decreases from H22 in the vicinity of H to lower limit H21.

  That is, according to the once-through boiler 1 of the present embodiment, when the high combustion mode is shifted to the low combustion mode, the difference (H22−H21) in the liquid level (separator liquid level) of the gas-liquid separator 2 is accommodated. An amount of liquid can be returned to the can 10. Thereby, the liquid level (liquid level in a can) of the can body 10 can be increased rapidly. Therefore, according to the once-through boiler 1 of this embodiment, it is possible to suppress the occurrence of a situation in which the upper portion of the liquid pipe 3 is damaged by a flame, and accordingly, it is possible to reduce the combustion amount of the burner 24 with a high reduction rate. it can.

According to the once-through boiler 1 of the present embodiment, for example, the following effects are exhibited.
In the once-through boiler 1 of this embodiment, the separator liquid level control unit 12 increases the separator liquid level when the combustion amount control unit 25 increases the combustion amount, and the combustion amount control unit 25 decreases the combustion amount. If so, reduce the separator level.
Thus, according to this embodiment, by controlling the increase / decrease in the separator liquid level, the dryness of the steam can be maintained, the drain water can be suppressed, and the burner 24 can be increased at a high rate of increase. The amount of combustion can be increased. Further, according to the present embodiment, it is possible to suppress the occurrence of a situation in which the upper portion of the liquid pipe 3 is damaged by a flame, and accordingly, it is possible to reduce the combustion amount of the burner 24 with a high reduction rate.

In the present embodiment, when the combustion amount control unit 25 increases the combustion amount, the separator liquid level control unit 12 increases or decreases the increase rate of the separator liquid level according to the increase rate of the combustion amount. When the combustion amount control unit 25 decreases the combustion amount, the separator liquid level control unit 12 increases or decreases the decrease rate of the separator liquid level according to the decrease rate of the combustion amount.
Therefore, according to the present embodiment, the effects of “the combustion amount of the burner 24 can be increased by the high increase rate” and “the combustion amount of the burner 24 can be decreased by the high decrease rate” described above. Can be further improved.

In the present embodiment, when the combustion amount control unit 25 increases the combustion amount, the time required to increase the combustion amount is the time required for the liquid amount in the liquid pipe 3 to evaporate with the increase in the combustion amount. The combustion amount is increased so as to be longer.
Therefore, according to the present embodiment, it is possible to more reliably suppress the possibility of a problem that the liquid accumulated in the gas-liquid separator 2 is accompanied by the vapor and the dryness of the vapor is lowered.

As shown in FIG. 8, in this embodiment, the lower limit value H21 of the separator liquid level and the liquid level (liquid level in the can) in the liquid pipe 3 corresponding to the combustion amount of the burner 24 corresponding to the lower limit value H21. This is almost the same as H12.
Therefore, according to the present embodiment, the space (volume) corresponding to the difference (H22−H21) in the liquid level (separator liquid level) of the gas-liquid separator 2 can be ensured to the maximum. The effect using the difference in separator liquid level (H22−H21) can be exhibited to the maximum.

  Further, in the present embodiment, the gas-liquid separator 2 has a vertically-oriented cylindrical shape, a cylinder 115 having a vapor outlet pipe 117 in the upper part and a separated liquid outlet pipe 11 in the lower part, and a horizontal cylinder-shaped cylinder. The steam inlet pipe 7 connected in a tangential direction to the peripheral side wall 115, the steam introduced from the steam inlet pipe 7 to the inside of the trunk 115, and the steam are separated by swirling inside the trunk 115. When the steam introduced from the steam inlet pipe 7 collides with the cylinder 115 and the guide plate 119 provided in the steam introduction portion where the steam is introduced from the steam inlet pipe 7 to the inside of the trunk 115 so as not to collide with the liquid. And a cover plate 120 disposed on the upper portion of the guide plate 119 so that the liquid does not splash up.

  Therefore, according to the present embodiment, the steam from the upper header 8 is introduced into the trunk 115 in the tangential direction via the steam inlet pipe 7. As a result, a swirling flow of steam is generated inside the barrel 115, and gas-liquid separation is performed. Specifically, the steam from the upper header 8 is wet saturated steam as a gas-liquid mixture. However, the vapor is swirled inside the trunk 115, and gas-liquid separation is performed by centrifugal force. That is, the liquid component is blown outward by the centrifugal force and dropped, and is sent to the lower header 6 via the separated liquid outlet pipe 11. On the other hand, the steam whose dryness is improved by such centrifugation is led out from the upper steam outlet pipe 117.

  In the gas-liquid separator 2, since the curved guide plate 119 is attached to the steam introduction portion from the steam inlet pipe 7 to the inside of the cylinder 115, the swirling of the steam inside the cylinder 115 is promoted. . In addition, the guide plate 119 suppresses collision between the steam introduced from the steam inlet pipe 7 into the cylinder 115 and the liquid (separated liquid) separated by the rotation of the steam inside the cylinder 115. To do. Further, the swirling of the steam and the separated liquid inside the cylinder 115 is not hindered by the guide plate 119.

  In the gas-liquid separator 2, a lid plate 120 is attached to an upper portion of the guide plate 119 in a steam introduction portion from the steam inlet pipe 7 to the inside of the trunk 115. Thereby, the splashing of the liquid when the steam introduced from the steam inlet pipe 7 collides with the trunk 115 is suppressed. Accordingly, it is possible to suppress the liquid resulting from the splashing from being mixed into the vapor after the gas-liquid separation by swirling.

  In the present embodiment, a baffle plate 121 is provided in the lower part inside the trunk 115. As a result, vortices are prevented from being generated when the liquid inside the cylinder 115 is discharged to the separation liquid outlet pipe 11. Therefore, drainage to the separation liquid outlet pipe 11 is smoothly performed, and the separation liquid is suppressed from being caught in the vapor discharged to the vapor outlet pipe 117.

As mentioned above, although preferred embodiment was described, this invention is not limited to embodiment mentioned above, It can implement with a various form.
For example, the gas-liquid separator is not limited to the gas-liquid separator 2 in the embodiment.

DESCRIPTION OF SYMBOLS 1 Cross-flow boiler 2 Gas-liquid separator 3 Liquid pipe 6 Lower header 7 Steam inlet pipe 8 Upper header 10 Can body 11 Separating liquid outlet pipe 12 Separator liquid level control part (separator liquid level control means)
13 Separator liquid level detection device 18 Supply amount control unit 24 Burner 25 Combustion amount control unit (combustion amount control means)
115 Body 117 Steam outlet pipe 119 Guide plate 120 Cover plate

Claims (5)

A can formed by connecting a plurality of liquid pipes between an upper header and a lower header, a burner for heating the liquid pipe with a variable combustion amount, and a combustion amount control means for controlling the combustion amount in the burner A gas-liquid separator connected between and communicated between the upper header and the lower header, and a separator liquid level control means for controlling a separator liquid level that is a liquid level in the gas-liquid separator; With
The separator liquid level control means increases the separator liquid level when the combustion amount is increased by the combustion amount control means, and is higher than the increase rate of the separator liquid level when the increase rate of the combustion amount is small. When the increase rate of the combustion amount is large, the increase rate of the separator liquid level is increased, and when the combustion amount is decreased by the combustion amount control means, the separator liquid level is decreased and the decrease rate of the combustion amount is small. A once-through boiler, wherein the reduction rate of the separator liquid level is increased when the reduction rate of the combustion amount is larger than the reduction rate of the separator liquid level . When the combustion amount is increased, the combustion amount control means performs combustion so that the time required for increasing the combustion amount is longer than the time required for evaporation in the liquid pipe as the combustion amount increases. The once- through boiler according to claim 1 , wherein the amount is increased. When the combustion amount is increased, the combustion amount control means performs combustion so that the time required for increasing the combustion amount is shorter than the time required for evaporation in the liquid pipe as the combustion amount increases. The once- through boiler according to claim 1 , wherein the amount is increased. The once-through boiler according to any one of claims 1 to 3 , wherein a lower limit value of the separator liquid level substantially coincides with a liquid level in the liquid pipe corresponding to a combustion amount of the burner corresponding to the lower limit value. The gas-liquid separator is
A cylinder having a vertical cylindrical shape, having a vapor outlet pipe at the top and a separation liquid outlet pipe at the bottom;
A steam inlet pipe that is laterally cylindrical and connected tangentially to the peripheral side wall of the barrel;
Steam is introduced from the steam inlet pipe into the cylinder so that the vapor introduced from the steam inlet pipe into the cylinder does not collide with the liquid separated by the rotation of the vapor inside the cylinder. A guide plate provided in a steam introduction part into which is introduced,
The so that steam introduced from the steam inlet pipe not spring upward liquid when colliding with the cylinder, according to any one of claims 1 to 4 having a cover plate which is disposed over the guide plates Once-through boiler.

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