JP2018155417A - Flash steam generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flash steam generator capable of supplying flash steam of high dryness.SOLUTION: A flash steam generator 30 includes a flash tank 31 for re-evaporating recovered steam drain D1 and separating it into flash steam S3 and hot water W3, a drain recovering line L31 for recovering the steam drain D1 to the flash tank 31, an initial drain discharge line L35 for discharging the steam drain D1 from the drain recovering line L31, temperature detection means 36 detecting a temperature of the steam drain D1, circulation passage switching means 32 composed of a plurality of control valves including at least an initial drain discharge valve V35 disposed on the initial drain discharge line L35, and control means 37 controlling the circulation passage switching means 32. The control means 37 opens the initial drain discharge valve V35 when a detection temperature of the drain temperature detection means 36 is a first set temperature or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flash steam generator.

  Conventionally, as shown in Patent Documents 1 and 2, a flash steam generator is used by being incorporated in a steam system, and collects steam drain (steam condensed water) discharged from a high-pressure steam utilization facility in a flash tank, The recovered steam drain is re-evaporated in a flash tank to separate it into flash steam and hot water, and the flash steam is supplied to a low-pressure steam utilization facility.

JP 2012-7762 A JP 2009-198038 A

  The initial flow portion (initial drain) of the steam drain discharged at the time of cold start of the high-pressure steam utilization facility is contaminated with the effluent from the facility (for example, iron eluted from the heat exchanger). Since it is in a low temperature state with a small amount of heat available, it has little utility value. For this reason, when the initial drain flows into the flash tank, it is discharged from the inside of the can.

  However, since the low-temperature drain is difficult to re-evaporate, the pressure inside the can of the flash tank does not rise, and the drain may not be discharged well. In particular, when a large amount of initial drain flows, drain discharge failure occurs and the inside of the can tends to become full. As a result, when high-temperature drain flows and flash vapor is generated, there is a problem that the dryness of the flash vapor decreases due to carry-over of the accumulated drain.

  Then, an object of this invention is to provide the flash steam generator which can supply flash steam with a high dryness.

  The present invention relates to a flash tank for re-evaporating the recovered steam drain to separate it into flash steam and hot water, a drain recovery line for recovering the steam drain to the flash tank, and steam for supplying the flash steam from the flash tank. An air supply line; a drain discharge line for discharging hot water from the flash tank; a bypass line for bypassing the steam drain to the flash tank; an initial drain discharge line for discharging the steam drain from the drain recovery line; A steam supply valve provided in the air supply line; a drain discharge valve provided in the drain discharge line; a bypass valve provided in the bypass line; and an initial drain discharge valve provided in the initial drain discharge line. A flow path switching means comprising a plurality of control valves; A drain temperature detecting means for detecting the temperature of the steam drain flowing into the recovery line or flowing through the drain recovery line; and a control means for controlling the flow path switching means, wherein the control means detects the drain temperature. When the detected temperature of the means is equal to or lower than the first set temperature, the initial drain discharge valve is opened.

Furthermore, the present invention preferably comprises the following configuration.
[2] The control means closes the initial drain discharge valve when the temperature detected by the drain temperature detection means is equal to or higher than a second set temperature higher than the first set temperature.

[3] The flow path switching means further includes an inlet valve provided in the drain recovery line, and the control means closes the inlet valve when the initial drain discharge valve is opened.

[4] Line pressure detection means for detecting the pressure in the drain recovery line upstream of the inlet valve is provided, and the control means, when the detected pressure of the line pressure detection means is greater than a set pressure The bypass valve provided in the bypass line is opened.

  ADVANTAGE OF THE INVENTION According to this invention, the flash steam generator which can supply flash steam with high dryness can be provided.

1 is a schematic configuration diagram of a steam system incorporating a flash steam generator according to an embodiment of the present invention. It is a flowchart which concerns on the operation control of a flash steam generator. It is a flowchart which concerns on control of the initial drain discharge valve which comprises a flow path switching means. It is a flowchart which concerns on control of the steam feed valve which comprises a flow path switching means, and control of a steam booster. It is a flowchart which concerns on control of the drain discharge valve which comprises a flow path switching means. It is a table which shows the ON / OFF state of a flow switch, the relationship of water level determination, and the opening setting value of a drain discharge valve. It is a flowchart which concerns on control of the bypass valve which comprises a flow path switching means. It is a flowchart which concerns on control of the bypass valve which comprises a flow path switching means. It is a flowchart which concerns on control of the blow valve which comprises a flow path switching means. It is a flowchart which concerns on control of the inlet valve which comprises a flow path switching means. It is a flowchart which concerns on control of the inlet valve which comprises a flow path switching means.

  Hereinafter, an embodiment of a flash steam generator according to the present invention will be described with reference to the drawings. The flash steam generator according to the present invention is used by being incorporated in a steam system that uses steam as a heat medium in various production facilities.

<Steam system>
FIG. 1 is a schematic configuration diagram of a steam system in which a flash steam generator according to an embodiment of the present invention is incorporated. As shown in FIG. 1, the steam system 1 includes a steam boiler device group 10, a steam header 12, a high-pressure steam utilization facility 13, a low-pressure steam utilization facility 14, a flash steam generator 30, and a steam booster 15. The water supply tank 40 is provided. The steam system 1 includes a first steam line L11, a second steam line L12, a third steam line L13, a fourth steam line L14, a fifth steam line L15, a first drain line L21, 2 drain line L22, 3rd drain line L23, 4th drain line L24, boiler feed water line L41, and makeup water line L52 are provided.

  The steam boiler apparatus group 10 includes, for example, a plurality of steam boiler apparatuses 11, 11,... Having a multi-tubular small once-through boiler structure, and a supply source of high-pressure steam S1 (for example, 0.5 to 2 MPa steam). It will be. The steam boiler device 11 heats the boiler water in the water pipe while burning gas fuel or oil fuel with a burner, and generates high-pressure steam S1. In the steam boiler device group 10, steam supply is performed by controlling the number of operating steam boiler devices 11 and the combustion states (for example, high combustion state, middle combustion state, low combustion state, and stopped state) of each steam boiler device 11. The amount can be adjusted.

  The first steam line L <b> 11 is a conduit for supplying high-pressure steam S <b> 1 manufactured by the steam boiler device 11 to the steam header 12. The steam header 12 is a facility for collecting high-pressure steam S1 produced by a plurality of steam boiler apparatuses 11, 11,... At one place and absorbing variations in steam pressure between the boilers. The high-pressure steam S1 collected in the steam header 12 is distributed toward a plurality of steam utilization facilities (load equipment).

  The second steam line L12 is a conduit for supplying the high-pressure steam S1 collected in the steam header 12 to the high-pressure steam utilization facility 13. The high-pressure steam utilization facility 13 is a facility that utilizes the high-pressure steam S1 supplied from the steam header 12 as a heat medium. Examples of the high-pressure steam utilization equipment 13 include production equipment such as a dryer in a cleaning factory and a fryer in a food processing factory.

  The third steam line L13 is a pipe line for reducing the pressure of the high-pressure steam S1 collected in the steam header 12 to low-pressure steam S2, and supplying the low-pressure steam S2 to the low-pressure steam utilization facility 14. The third steam line L13 is provided with a pressure reducing valve V11 in order to obtain a low pressure steam S2 (for example, 0.1 to 0.4 MPa steam) having a required pressure from the high pressure steam S1. The low-pressure steam utilization facility 14 is a facility that uses the low-pressure steam S2 supplied via the pressure reducing valve V11 or the low-pressure steam S2 supplied via the steam booster 15 described later as a heat medium. The low-pressure steam utilization equipment 14 includes, for example, production equipment such as a continuous washing machine in a cleaning factory and a steamer in a food processing factory.

  The fourth steam line L <b> 14 is a pipeline for increasing the pressure of the flash steam S <b> 3 generated by the flash steam generator 30 to the low pressure steam S <b> 2 and supplying the low pressure steam S <b> 2 to the low pressure steam utilization facility 14. The upstream end of the fourth steam line L14 is connected to the steam outlet (reference numeral omitted) of the flash steam generator 30. The downstream end of the fourth steam line L14 is connected to the third steam line L13 on the downstream side of the pressure reducing valve V11. A steam booster 15 is provided in the fourth steam line L14 in order to obtain low pressure steam S2 (for example, 0.1 to 0.4 MPa steam) having a required pressure from the flash steam S3. As the steam booster 15, for example, a screw type compressor can be used. This steam booster 15 is driven by a drive command signal and a stop command signal transmitted from the control unit 37 (described later) of the flash steam generator 30. Be controlled.

  In the fourth steam line L14, a vacuum breaker valve V12 is provided on the suction side of the steam booster 15, and a check valve V13 is provided on the discharge side of the steam booster 15. The vacuum breaker valve V12 is a valve mechanism that raises the suction side to atmospheric pressure by performing an intake operation when the suction side of the steam booster 15 becomes negative pressure. While the operation of the flash steam generator 30 is stopped, the steam is condensed by the heat radiation and cooling of the fourth steam line L14 (and the air supply line L31), and the suction side of the steam booster 15 tends to be negative pressure. When the steam pressure booster 15 is a screw compressor, if the suction side has a negative pressure, foreign matter may be caught in the liquid seal portion between the screw teeth due to the backflow of the low-pressure steam S2. Therefore, in this embodiment, the vacuum breaker valve V12 is provided to prevent the suction side of the steam booster 15 from entering a negative pressure state. The check valve V13 is a valve mechanism that prevents the low-pressure steam S2 from flowing back to the steam booster 15 by closing when a flow opposite to the set direction occurs.

  The low-pressure steam utilization facility 14 is supplied with the low-pressure steam S2 derived from the steam boiler device group 10 and the low-pressure steam S2 derived from the flash steam generator 30. Therefore, in the steam system 1, as the supply amount of the low-pressure steam S2 derived from the flash steam generator 30 is increased, the supply amount of the low-pressure steam S2 derived from the steam boiler device group 10 is reduced, and energy saving of the entire system is achieved. Be able to.

  The first drain line L <b> 21 is a conduit for collecting the steam drain D <b> 1 generated in the high-pressure steam utilization facility 13 in the water supply tank 40. A steam trap 21 is provided on the steam outlet side of the high-pressure steam utilization facility 13. The steam trap 21 is a device that separates the steam drain D1 from the high-pressure steam S1 and automatically discharges it. The first drain line L21 is laid with a horizontal pipe (or inclined descending pipe) from the steam trap 21 to the vicinity of the water supply tank 40, and then is extended with a vertical pipe from above the water supply tank 40. Submerged in the water storage area.

  When the first drain line L21 collects the steam drain D1 in the water supply tank 40, the flow path is opened by a bypass valve V36 (described later), while the steam drain D1 is flushed by the flash steam generator 30 (described later). When collecting in the tank 31, the flow path is blocked by the bypass valve V36. Therefore, the first drain line L21 functions as a bypass line that bypasses the steam drain D1 with respect to the flash tank 31.

  Further, above the water supply tank 40, an exhaust port (reference numeral omitted) is provided on the upper surface of the horizontal pipe of the first drain line L21 to take out the flash steam S4 generated in the process of circulation of the steam drain D1. The exhaust port is connected to a fifth steam line L15 including a rising piping portion, a horizontal piping portion, and a falling piping portion. That is, the fifth steam line L15 is a pipe branching from the first drain line L21. An exhaust valve V14 is provided in the horizontal piping portion of the fifth steam line L15. The terminal of the falling piping part of the 5th steam line L15 is connected to the non-water storage area | region of the water supply tank 40, or is connected to a water storage area | region through a silencer. As will be described later, by opening the exhaust valve V14 in synchronism with the opening of the bypass valve V33, the steam drain D1 that has been two-phased into hot water and flash steam has a hot water portion through the first drain line L21. On the other hand, the steam part (S4) is recovered in the water supply tank 40 through the fifth steam line L15.

  The second drain line L22 is a conduit for introducing the steam drain D1 generated in the high-pressure steam utilization facility 13 into the flash steam generator 30. The second drain line L22 branches from the first drain line L21, and the downstream end is connected to the drain inlet (reference numeral omitted) of the flash steam generator 30.

  The third drain line L <b> 23 is a conduit for collecting the hot water W <b> 3 discharged from the flash steam generator 30 into the water supply tank 40. The third drain line L23 has an upstream end connected to a hot water outlet (reference numeral omitted) of the flash steam generator 30, and a downstream end joined the first drain line L21.

  The fourth drain line L <b> 24 is a conduit for discarding the hot water W <b> 3 blown down from the flash steam generator 30 and the steam drain D <b> 1 to the drain pit 50. The fourth drain line L <b> 24 has an upstream end connected to a blow outlet (reference numeral omitted) of the flash steam generator 30, and a downstream end opened to the atmosphere toward the drain pit 50.

  The boiler feed water line L41 is a conduit for supplying boiler steam supply water W2 in which makeup water W1 and warm water W3 (or steam drain D1) are mixed to the steam boiler apparatus 11. The upstream end of the boiler water supply line L41 is connected to the water supply tank 40. The downstream end of the boiler water supply line L41 is connected to each steam boiler apparatus 11, 11,... Via a branch line. The feed water tank 40 is an open-air tank that stores boiler feed water W <b> 2 supplied to the steam boiler device 11. A supply water line L42 is connected to the water supply tank 40, and supply water W1 (for example, softened water) is supplied.

<Flash steam generator>
The flash steam generator 30 includes a flash tank 31, a drain recovery line L31, a steam supply line L32, a drain discharge line L33, a blow line L34, an initial drain discharge line L35, and a flow path switching means 32 (inlet Steam supply valve V32; Drain discharge valve V33; Blow valve V34; Initial drain discharge valve V35; Bypass valve V36) and in-can water level detection means 33 (first water level detector 33A; second water level detector 33B) ), Can pressure detection means 34 (first pressure sensor 34A; first pressure switch 34B), line pressure detection means 35 (second pressure sensor 35A; second pressure switch 35B), and drain temperature detection means 36 ( Temperature sensor) and control means 37.

  The flash tank 31 is a pressure vessel (hereinafter also simply referred to as “can”) for re-evaporating the recovered steam drain D1 and separating it into flash steam S3 and hot water W3. Since the flash tank 31 is a container that holds a liquid that exceeds the boiling point at atmospheric pressure, the flash tank 31 is manufactured so as to be compatible with a small pressure container defined in Article 1-6 of the Ordinance for Enforcement of the Industrial Safety and Health Act. Connected to the upper part of the flash tank 31 is a safety valve V37 (relief valve) for releasing the pressure when the in-can pressure rises abnormally.

  The flash tank 31 is provided with a first water level detector 33A and a second water level detector 33B as an in-can water level detecting means 33 for detecting the in-can water level. Each of the water level detectors 33A and 33B has a water level detection cylinder, and the upper and lower parts of the water level detection cylinder are connected to the upper and lower parts of the flash tank 31 via a communication pipe, respectively. Inside the two water level detection cylinders, five float switches are arranged with different heights, and the water level in the can of the flash tank 31 can be detected stepwise. The set water level detected by the first water level detector 33 </ b> A has two levels of low water level L and high water level H in order from the bottom. On the other hand, the set water level detected by the second water level detector 33B is in three stages of the lower limit water level LL, the middle water level M, and the upper limit HH in order from the bottom. That is, by using both the water level detectors 33A and 33B in combination, it is possible to detect five set water levels that satisfy the relationship of lower limit water level LL <low water level L <middle water level M <high water level H <upper limit water level HH. The detected water level (contact signal) of each of the water level detectors 33A and 33B is transmitted to the control means 37 as a detection signal.

  Further, the flash tank 31 is provided with a first pressure sensor 34A and a first pressure switch 34B as the can internal pressure detecting means 34 for detecting the can internal pressure (pressure in the gas phase portion). The first pressure sensor 34A continuously detects the internal pressure of the flash tank 31 within a predetermined measurement range. The first pressure switch 34B detects whether or not the pressure inside the can of the flash tank 31 has reached a preset upper limit pressure. For example, the first pressure switch 34B is a detection switch in which the contact signal is turned on when the detected pressure is equal to or higher than the upper limit pressure, and the contact signal is turned off when the detected pressure is lower than the upper limit pressure. The detected pressures (including contact signals) of the first pressure sensor 34A and the first pressure switch 34B are transmitted to the control means 37 as detection signals. The detection of the upper limit pressure by the first pressure switch 34B is used, for example, to issue an alarm for an abnormal pressure in the can due to a closed failure of the air supply valve V32.

  The drain recovery line L31 is a conduit for recovering the steam drain D1 flowing into the second drain line L22 from the first drain line L21 to the flash tank 31. The upstream end of the drain recovery line L31 is a drain inlet (reference number omitted) of the apparatus. The downstream end of the drain recovery line L31 is connected to the body of the flash tank 31. In the drain recovery line L31, in order from the upstream side, a second pressure sensor 35A (line pressure detection means), a temperature sensor 36 (drain temperature detection means), an inlet valve V31, a second pressure switch 35B (line pressure detection means), A strainer 38 is provided.

  The second pressure sensor 35A continuously detects the pressure in the pipe line of the drain recovery line L31 within a predetermined measurement range. The second pressure switch 35B detects whether or not the in-pipe pressure of the drain recovery line L31 has reached a preset upper limit pressure. The second pressure switch 35B is, for example, a detection switch that turns on the contact signal when the detected pressure is equal to or higher than the upper limit pressure and turns off the contact signal when the detected pressure is lower than the upper limit pressure. The temperature sensor 36 continuously detects the temperature of the steam drain D1 flowing through the drain recovery line L31 in a predetermined measurement range. The detected pressure (including the contact signal) of the second pressure sensor 35A and the second pressure switch 35B and the detected temperature of the temperature sensor 36 are transmitted to the control means 37 as detection signals. The detection of the upper limit pressure by the second pressure switch 35B is used, for example, to issue an alarm for abnormal pressure in the pipeline due to clogging of the strainer 38.

  The inlet valve V <b> 31 is a control valve (for example, a proportional control type electric valve) that constitutes the flow path switching unit 32, and is controlled by a drive signal from the control unit 37. The strainer 38 is a device for filtering solids such as iron rust contained in the steam drain D1.

  The steam supply line L32 is a conduit for supplying the flash steam S3 from the flash tank 31 to the fourth steam line L14. The upstream end of the steam supply line L32 is connected to the top of the flash tank 31. The downstream end of the steam supply line L32 is a steam outlet (reference number omitted) of the apparatus. In the steam supply line L32, a vacuum break valve V38 and a steam supply valve V32 are provided in this order from the upstream side.

  The vacuum breaker valve V38 is a valve mechanism that raises the inside of the can to atmospheric pressure by performing an intake operation when the inside of the can of the flash tank 31 becomes negative pressure. While the operation of the flash steam generator 30 is stopped, the inside of the can tends to be negative due to condensation of the flash steam S3 accompanying heat radiation and cooling of the flash tank 31. When the steam supply valve V32 is a ball type motor-operated valve, if the pressure in the can becomes negative, foreign matter may be caught in the seat valve seat or the seat valve seat may be deformed due to the backflow of the flash steam S3. is there. Therefore, in this embodiment, by providing the vacuum break valve V38, the inside of the can of the flash tank 31 is prevented from being in a negative pressure state. The steam supply valve V <b> 32 is a control valve (for example, a proportional control type electric valve) that constitutes the flow path switching unit 32, and is controlled by a drive signal from the control unit 37.

  The drain discharge line L33 is a conduit for sending the hot water W3 in the flash tank 31 (steam drain D1 after separating the flash steam S3) to the third drain line L23. The upstream end of the drain discharge line L33 is connected to the bottom of the flash tank 31. The downstream end of the drain discharge line L33 is a drain outlet (reference numeral omitted) of the apparatus. That is, the hot water W3 separated in the flash tank 31 is collected in the feed water tank 40 through the third drain line L23 and the first drain line L21, and then reused as a part of the boiler feed water W2. . The drain discharge line L33 is provided with a drain discharge valve V33 and a check valve V39 in order from the upstream side.

  The drain discharge valve V <b> 33 is a control valve (for example, a proportional control type electric valve) constituting the flow path switching unit 32, and is controlled by a drive signal from the control unit 37. The check valve V39 is a valve mechanism that prevents the warm water W3 from flowing back to the flash tank 31 by closing when a flow opposite to the set direction occurs.

  The blow line L34 is a conduit for sending the hot water W3 in the flash tank 31 (steam drain D1 after separating the flash steam S3) to the fourth drain line L24. The upstream end of the blow line L34 is branched from the drain discharge line L33 on the upstream side of the drain discharge valve V33. The downstream end of the blow line L34 is a blow outlet (reference numeral omitted) of the apparatus. The blow line L34 is provided with a blow valve V34. The blow V 34 is a control valve (for example, a proportional control type electric valve) that constitutes the flow path switching unit 32, and is controlled by a drive signal from the control unit 37.

  The initial drain discharge line L35 is a conduit for discharging the steam drain D1 flowing into the drain recovery line L31. The upstream end of the initial drain discharge line L35 is branched from a drain recovery line L31 between the temperature sensor 36 and the inlet valve V31. The downstream end of the initial drain discharge line L35 is gathered in the blow line L34 on the downstream side of the blow valve V34. The blow line L35 is provided with a blow valve V35. The blow valve V <b> 35 is a control valve (for example, a two-position control type electric valve) that constitutes the flow path switching unit 32, and is controlled by a drive signal from the control unit 37.

  In the first drain line L21 functioning as a bypass line for the flash tank 31, a bypass valve V36 is provided between the branch position of the second drain line L22 and the connection position of the fifth steam line L15. This bypass valve V 36 is provided outside the flash steam generator 30, but is a control valve (for example, a proportional control type electric valve) constituting the flow path switching means 32, and is driven by a drive signal from the control means 37. Be controlled. The bypass valve V <b> 36 is opened when a part or all of the steam drain D <b> 1 discharged from the steam trap 21 is collected in the feed water tank 40 without flowing into the flash steam generator 30.

  As described above, the flow path switching means 32 includes the control valves of the inlet valve V31, the steam supply valve V32, the drain discharge valve V33, the blow valve V34, the initial drain discharge valve V35, and the bypass V36, and the fluid in the apparatus. It is configured as a multi-valve mechanism that can switch the flow path to a required state.

  The control means 37 controls the flow path switching means 32, the steam booster 15, the exhaust valve V14 and the like using physical quantity information (pressure, water level, temperature) in the system acquired from sensors. The control means 37 is comprised by the programmable logic controller (PLC) which can perform sequence control, for example. In the memory area of the PLC, in addition to various programs, setting data for control input in advance and detection data during operation by sensors are stored. Hereinafter, the control operation of the flash steam generator 30 will be described in detail. As described above, the set water level used for determining the water level in the can has a relationship of lower limit water level LL <low water level L <middle water level M <high water level H <upper limit water level HH. Further, the set pressure used for the determination of the internal pressure of the can is the relationship of the first set pressure P1 <the second set pressure P2 <the third set pressure P3 <the fourth set pressure P4, and the set pressure used for determining the drain temperature. The temperature has a relationship of first set temperature T1 <second set temperature T2.

[A] Operation Control FIG. 2 is a flowchart relating to operation control of the flash steam generator 30 by the control means 37. In this control, the control means 37 acquires the detected water levels of the first water level detector 33A and the second water level detector 33B as the in-can water level. Step ST0 indicates that the bypass valve V36 is fully open when the apparatus is not powered on. In this state, the steam drain D1 discharged from the steam trap 21 is collected in the water supply tank 40 through the first drain line L21. When the power is turned on in step ST0, the control means 37 moves to step ST1 and executes the startup preparation process. In the start-up preparation process, the initial drain discharge valve V35 is fully closed, the steam supply valve V32 is fully closed, the drain discharge valve V33 is fully opened, the blow valve V34 is fully closed, and the inlet valve V31 is fully closed. Normally, each of the valves V31 to V35 is controlled to a predetermined opening / closing state when the apparatus is stopped. However, considering the case where the valve is manually operated while the apparatus is stopped, the valves V31 to V35 are set to the predetermined opening / closing state by the startup preparation process. It is resetting. In addition, the opening degree of each valve V31-V35 will be 0% for fully closed, and 100% for fully opened. When the operation switch is turned on in step ST1, the control means 37 starts an operation process consisting of steps ST2 to ST6.

  Now, when the apparatus stop time reaches a certain length, the steam in the can is condensed by the heat radiation and cooling of the flash tank 31, and the pressure in the can is lowered. Although the can internal pressure is maintained at atmospheric pressure or higher due to the presence of the vacuum breaker valve V38, the condensate discharge pressure decreases, so the water level in the can may increase before the apparatus is started. Therefore, the control means 37 determines whether or not the water level in the can is higher than the high water level H in step ST2. When it is determined YES in step ST2 (in-can water level ≧ H), in order to discharge the condensed water in the can and lower the water level, the control unit 37 proceeds to step ST3 and executes a standby process. In the standby process, the control means 37 controls the steam supply valve V32 to be fully closed, the drain discharge valve V33 to be fully open, the inlet valve V31 to be fully open, and the bypass valve V36 to be fully closed. Thereby, introduction of steam drain D1 and discharge of condensed water are promoted, and the water level in the can is lowered.

  In step ST4 following step ST3, the control means 37 determines whether or not the internal water level is equal to or higher than the intermediate water level M. If YES in step ST5 (in-can water level ≧ M), since the in-can water level is in the process of lowering, the control means 37 continues the standby process in step ST3. On the other hand, if NO (in-can water level <M) is determined in step ST4, the water level in the can is sufficiently lowered, so that the standby process is canceled, and the control unit 37 returns to the process in step ST2.

  If it is determined in step ST2 that NO (water level in the can <H), the control unit 37 proceeds to step ST5. In step ST5, the control means 37 performs control (FIG. 3) of the initial drain discharge valve V35 described later. In step ST6 following step ST5, control of a steam supply valve V32 (FIG. 4), control of a steam booster 15 (FIG. 4), control of a drain discharge valve V33 (FIGS. 5 and 6), and a bypass valve V36 described later. (FIG. 7, FIG. 8), blow valve V34 control (FIG. 9), and inlet valve V31 control (FIG. 10) are executed in parallel. When each control in step ST7 ends, the control means 37 returns to the process in step ST2.

  When the operation switch is turned off during the execution of the operation process, the control unit 37 proceeds to step ST7 and stops the steam booster 15. In step ST8 following step ST7, the control means 37 executes a stop process. In the stop process, the initial drain discharge valve V35 is fully closed, the steam supply valve V32 is fully closed, the drain discharge valve V33 is fully opened, the blow valve V34 is fully closed, the inlet valve V31 is fully closed, and the bypass valve V36 is fully opened. To do. When the operation switch is turned off in step ST8, the control means 37 proceeds to step ST0 and maintains the fully open bypass valve V36.

[B] Control of Initial Drain Discharge Valve V35 FIG. 3 is a flowchart relating to control of the initial drain discharge valve V35 by the control means 37. In this control, the control means 37 acquires the temperature detected by the temperature sensor 36 as the drain temperature. In step ST11, the control unit 37 determines whether or not the drain temperature is equal to or lower than a first set temperature T1 (for example, 90 ° C.). If YES in step ST11 (drain temperature ≦ T1), since the steam drain D1 discharged from the steam trap 21 is at a low temperature, the control unit 37 proceeds to step ST12 and sets the opening of the initial drain discharge valve V35. Control to 100% (fully open).

  The initial flow portion (initial drain) of the steam drain D1 discharged at the time of cold start of the high-pressure steam utilization facility 13 has almost no merit due to the recovery due to contamination by the effluent and the amount of heat that can be reused. Therefore, when it is determined that the drain temperature is equal to or lower than the first set temperature T1, the control unit 37 opens the initial drain discharge valve V35 so that the steam drain D1 does not flow into the flash tank 31. Thereby, the low temperature steam drain D1 flowing in through the second drain line L22 is discharged to the drain pit 50 through the drain discharge line L35 and the fourth drain line L24.

  If NO (drain temperature> T1) is determined in step ST11, the control unit 37 proceeds to step ST13. In step ST13, the control means 37 determines whether or not the drain temperature is equal to or higher than a second set temperature T2 (for example, 95 ° C.) higher than the first set temperature T1. If NO (drain temperature <T2) is determined in step ST13, since the drain temperature has not increased sufficiently, the control unit 37 proceeds to step ST14 and maintains the opening of the initial drain discharge valve V35 at 100%. . On the other hand, if YES in step ST13 (drain temperature ≧ T2), the drain temperature has increased sufficiently. Therefore, the control unit 37 proceeds to step ST15 and sets the opening of the initial drain discharge valve V35 to 0% (all Closed). Thereby, collection | recovery of the vapor | steam drain D1 to the flash tank 31 comes to be permitted.

  When this control is executed, it is preferable to control the initial drain discharge valve V35 and the inlet valve V31 to be interlocked (see control of the inlet valve V31 described later). When the opening degree of the initial drain discharge valve V35 is controlled to 100% (fully open) in step ST12, the opening degree of the inlet valve V31 is controlled to 0% (fully closed). Thereby, even if the low temperature steam drain D1 is discharged during the operation of the apparatus due to additional activation of a plurality of installed high temperature steam utilization facilities 13, the inflow to the flash tank 31 is prevented.

  Further, when executing this control, it is preferable to control the bypass valve V36 in accordance with the inflow amount of the steam drain D1 (see control of the bypass valve V36 described later). When the detected pressure of the second pressure sensor 35A is equal to or higher than a predetermined set pressure, the opening degree of the bypass valve V36 is controlled to 100% (fully open). Thereby, even if a large amount of steam drain D1 flows in during the operation of the apparatus due to additional activation of a plurality of high-temperature steam utilization facilities 13 installed, the discharge time can be shortened.

[C] Control of Steam Supply Valve V32; Control of Steam Booster 15 FIG. 4 is a flowchart relating to control of the steam supply valve V32 and control of the steam booster 15 by the control means 37. In this control, the control means 37 acquires the detected pressure of the first pressure sensor 34A as the in-can pressure. In step ST21, the control means 37 determines whether or not the can internal pressure is equal to or lower than a second set pressure P2 (for example, 0.1 MPa). If YES in step ST21 (can internal pressure ≦ P2), since the discharge pressure of the hot water W3 from the flash tank 31 is not secured, the control means 37 moves to step ST22 and the steam booster 15 Stop. And the control means 37 transfers to step ST23, and controls the opening degree of the steam supply valve V32 to 0% (fully closed). As a result, an increase in the can internal pressure is promoted.

  In this control, when stopping the steam booster 15 with the closing of the steam supply valve V32, the control means 37 transmits a stop command signal to the steam booster 15 in step ST22 after a predetermined time (for example, After 20 seconds), a close command signal is transmitted to the steam supply valve V32 in step ST23. In the operation control, the same processing is performed in step ST7 and step ST8. The steam booster 15 normally has a characteristic that the screw rotor is free-run stopped due to inertia after receiving the stop command signal, but the steam supply valve V32 is closed while the valve body is braked after receiving the close command signal. . Therefore, if the stop command signal and the stop command signal are output at the same time, a time lag occurs from when the steam supply valve V32 is completely closed until the steam booster 15 is completely stopped, during which the suction side of the steam booster 15 is negative pressure. Become. As described above, when the steam booster 15 is a screw compressor, if the suction side becomes negative pressure, foreign matter may be caught in the liquid seal portion between the screw tooth grooves due to the backflow of the low-pressure steam S2. Therefore, in this embodiment, the suction side of the steam booster 15 is in a negative pressure state by delaying the timing of transmitting the stop command signal to the steam supply valve V32 from the timing of transmitting the stop command signal to the steam booster 15. Is prevented.

  If it is determined in step ST21 that NO (in-can pressure> P2), the control means 37 proceeds to step ST24. In step ST24, the control means 37 determines whether or not the can internal pressure is equal to or higher than a third set pressure P3 (for example, 0.2 MPa) higher than the second set pressure. If YES in step ST24 (can internal pressure ≧ P3), since the discharge pressure of the hot water W3 from the flash tank 31 is sufficiently ensured, the control means 37 moves to step ST25 to transfer steam. The opening degree of the air valve V32 is controlled to 100% (fully open). Then, the control means 37 moves to step ST26 and drives the steam booster 15. Thereby, the supply of the flash steam S3 to the low-pressure steam utilization facility 14 is permitted.

  If NO (in-can pressure <P3) is determined in step ST24, the control means 37 proceeds to step ST27 and considers the possibility that the discharge pressure of the hot water W3 from the flash tank 31 is not sufficiently secured. The opening degree of the air valve V32 is adjusted. Specifically, the opening degree of the steam supply valve V32 is proportionally controlled so that the opening degree is 0% when the pressure inside the can is P2, and the opening degree is 100% when the pressure inside the can is P3. Adjust the amount. As a result, a decrease in the can internal pressure is suppressed, and the discharge pressure of the hot water W3 is ensured. Then, the control means 37 moves to step ST26 and drives the steam booster 15.

  In the operation control, since the initial drain discharge control in step ST2 is performed and then the process proceeds to step ST6 including this control, the second set temperature T2 (for example, The steam drain D1 having a high temperature of 95 ° C. or higher flows into the flash tank 31. As a result, the increase in the internal pressure of the can is promoted, and the flash tank 31 is immediately in a state where the discharge pressure of the hot water W3 is ensured. As a result, it becomes easy to keep the water level in the can within an appropriate range, and it is possible to prevent the flash steam S3 having a reduced dryness from being carried over due to carry-over of the hot water W3.

[D] Control of Drain Discharge Valve V33 FIG. 5 is a flowchart relating to control of the drain discharge valve V33 by the control means 37. FIG. 6 is a table showing the relationship between the on / off state of the float switch and the water level determination in the first water level detector 33A and the second water level detector 33B, and the opening setting value of the drain discharge valve V33. In this control, the control means 37 acquires the detected water level of both water level detectors 33A and 33B as the in-can water level W. Further, when executing this control, an opening set value corresponding to each water level stored in the control means 37 is used.

  As shown in the upper part of FIG. 6, when all five float switches are off, the water level determination is W <LL, and the control means 37 recognizes that the in-can water level W is lower than the lower limit water level LL. The notation “0% (fixed)” indicates that the opening degree is fixed at 0% (fully closed). When only the lowermost float switch is on, the water level determination is LL ≦ W <L, and the control means 37 recognizes that the in-can water level W is the lower limit water level LL. The notation of “10% (LL)” indicates that the opening setting value of the lower limit water level LL is 10%. When the two float switches are on from below, the water level determination is L ≦ W <M, and the control means 37 recognizes that the in-can water level W is the low water level L. The notation “50% (L)” indicates that the opening setting value of the low water level L is 50%. When the three float switches are on from below, the water level determination is M ≦ W <H, and the control means 37 recognizes that the in-can water level W is the middle water level M. The notation “100% (M)” indicates that the opening setting value of the middle water level M is 100%. When the four float switches are on from below, the water level determination is H ≦ W <HH, and the control means 37 recognizes that the in-can water level W is the high water level H. The notation “100% (H)” indicates that the opening setting value of the high water level H is 100%. When all five float switches are on, the water level determination is HH ≦ W, and the control means 37 recognizes that the in-can water level W exceeds the upper limit water level HH. The notation “100% (fixed)” indicates that the opening degree is fixed at 100% (fully open).

  The flowchart in FIG. 5 is for when the water level rises, and in step ST31, the control means 37 determines whether or not the in-can water level W is equal to or higher than the lower limit water level LL. If NO (W <LL) is determined in step ST31, the control unit 37 proceeds to step ST32, and whether or not the first set time t1 (for example, 10 seconds) has elapsed in the state where the in-can water level W <LL. Judging. If it is determined YES in step ST32 (t1 elapses while W <LL), the control unit 37 proceeds to step ST33 and controls the opening of the drain discharge valve V33 to 0% (fixed). On the other hand, if it is determined NO in step ST32 (returns to W ≧ LL without elapse of t1), the control unit 37 proceeds to step ST34 and controls the opening of the drain discharge valve V33 to 10% (LL).

  If YES in step ST31 (W ≧ LL), the control unit 37 proceeds to step ST35 and determines whether or not the in-can water level W is equal to or higher than the low water level L. If NO (W <L) is determined in step ST35, the control unit 37 proceeds to step ST36 and controls the opening degree of the drain discharge valve V33 to 10% (LL).

  If YES (W ≧ L) is determined in step ST35, the control unit 37 proceeds to step ST37 and determines whether the in-can water level W is equal to or higher than the middle water level M. If NO (W <M) is determined in step ST37, the control unit 37 proceeds to step ST38 and controls the opening of the drain discharge valve V33 to 50% (L).

  If YES (W ≧ M) is determined in step ST37, the control unit 37 proceeds to step ST39 and determines whether or not the in-can water level W is higher than the high water level H. If NO (W <H) is determined in step ST39, the control unit 37 proceeds to step ST40 and controls the opening degree of the drain discharge valve V33 to 100% (M).

  If YES (W ≧ H) is determined in step ST39, the control unit 37 proceeds to step ST41 and determines whether or not the in-can water level W is equal to or higher than the upper limit water level HH. If NO (W <HH) is determined in step ST41, the control unit 37 proceeds to step ST42 and controls the opening degree of the drain discharge valve V33 to 100% (H). Subsequently, the control unit 37 proceeds to step ST43, and determines whether or not a second set time t2 (for example, 10 seconds) has elapsed in a state where W ≧ H. If it is determined in step ST43 that YES (t2 has elapsed while W ≧ H), the control unit 37 proceeds to step ST3 (FIG. 2) and executes standby processing. On the other hand, if it is determined NO in step ST43 (changes to W <H without elapse of t2), the control unit 37 ends the process.

  If YES (W ≧ HH) is determined in step ST41, the control unit 37 proceeds to step ST44 and controls the opening of the drain discharge valve V33 to 100% (fixed). Subsequently, the control unit 37 proceeds to step ST45, and determines whether or not a third set time t3 (for example, 10 seconds) has elapsed in a state where the in-can water level W ≧ HH. If it is determined as YES in step ST45 (t3 elapses while W ≧ HH), the control unit 37 proceeds to step ST46, issues an alarm, and proceeds to step ST7 (FIG. 2). That is, when the state where the in-can water level W exceeds the upper limit water level HH continues, the control means 37 controls to stop the apparatus. On the other hand, if it is determined NO in step ST45 (change to W <HH without elapse of t3), the control unit 37 ends the process.

  After shifting from step ST43 to standby processing, the drain discharge valve V33 is controlled to be fully opened, so that the water level in the can is lowered. As shown in the lower part of FIG. 6, when the three float switches are turned on from below (water level determination M ≦ W <H), the control means 37 recognizes that the water level W in the can is the middle water level M, and the drain discharge valve The opening degree of V33 is controlled to 100% (M). Thereafter, when the discharge of the hot water W3 further proceeds and the two float switches are turned on from below (water level determination L ≦ W <M), it is determined NO in step ST4, and the opening degree of the drain discharge valve V33 is 100% (M ) Is released in a controlled state.

  When the water level in the can rises after the standby is canceled and the water level determination is M ≦ W <H, the opening degree of the drain discharge valve V33 is controlled to 100% (M) as it is. On the contrary, when the water level in the can is lowered after the standby is canceled and the water level determination is LL ≦ W <L, the opening degree of the drain discharge valve V33 is controlled to 50% (L), which is one step lower. When the water level in the can rises while the opening degree of the drain discharge valve V33 is controlled to 50% (L) and the water level determination is L ≦ W <M, the opening degree of the drain discharge valve V33 remains unchanged. It is controlled to 50% (L). On the other hand, when the water level in the can drops while the opening degree of the drain discharge valve V33 is controlled to 50% (L) and the water level determination is W <LL, the opening degree of the drain discharge valve V33 is 0. % (Fixed).

  As described above, in this control, when it is determined that the second set time t2 has elapsed with the in-can water level W being equal to or higher than the high water level H (YES in step ST43), standby processing (step ST3 in FIG. 3) is executed. It is supposed to be. In the standby processing, since the steam supply valve V32 is controlled to be fully closed, even if the hot water W3 is likely to carry over due to the rise of the water level in the can, the flash steam S3 having a reduced dryness is supplied. Can be prevented.

  In this control, when it is determined that the in-can water level W is lower than the low water level L (NO in step ST35), the control means 37 controls the opening of the drain discharge valve V33 to 10% without setting it to 0%. It has become. Further, in this control, when it is determined that the water level W in the can has returned to the lower limit water level LL or more without passing the first set time t1 (NO in step ST32), the opening degree of the drain discharge valve V33 is set to 0%. It is designed to be controlled to 10%. That is, in this control, except for special circumstances, the opening degree of the drain discharge valve V33 is controlled in a range that is not less than the minimum set opening degree that is not fully closed, so that the warm water W3 is continuously discharged. . Thereby, the raise of the water level in a can is suppressed and the carry over of warm water W3 is prevented. Further, even if the inflow amount of the steam drain D1 increases rapidly and the water level in the can rises, the opening degree of the drain discharge valve V33 is increased stepwise starting from the minimum setting opening degree 10%. The water level in the can can be lowered to an appropriate range.

  By operating the drain discharge valve V33 so as not to be fully closed, the amount of the steam drain D1 held in the can is kept to a minimum, but this is also effective in suppressing the vibration of the first drain line L21. . In the case where the vibration of the first drain line L21 is likely to occur, the recovery amount of the steam drain D1 is limited by controlling the bypass valve V36 from the fully closed state to the fully opened state in order to forcibly lower the water level in the can of the flash tank 31. This is the case (two-position control example shown in FIG. 7). In this case, at the moment when the bypass valve V36 is opened, in addition to the re-evaporation of the steam drain D1 discharged from the steam trap 21, the re-evaporation of the steam drain D1 in the flash tank 31 occurs at the same time. Tends to flow toward the water supply tank 40 at a stretch. As a result, the first drain line L21 vibrates vigorously due to the flow of the flash vapor at a high flow rate, which may cause damage to the piping due to the impact. Therefore, the operation is performed so as to keep the amount of the vapor drain D1 in the can to be minimized, so that the amount of reevaporation in the flash tank 31 is reduced. Thereby, since the rapid outflow of the flash vapor generated when the bypass valve V36 is controlled from fully closed to fully open is alleviated, vibration of the first drain line L21 is suppressed.

[E] Control of bypass valve V36 (example of 2-position control)
FIG. 7 is a flowchart relating to the control of the bypass valve V36 by the control means 37. In this control, the control unit 37 acquires the detected pressure of the first pressure sensor 34A as the in-can pressure, and the control unit 37 acquires the detected water levels of both the water level detectors 33A and 33B as the in-can water level. Further, the control unit 37 acquires the detected pressure of the second pressure sensor 35A as the line pressure. In step ST51, the control means 37 determines whether or not the control state of the initial drain discharge valve V35 is an opening degree of 100%. When it is determined YES in step ST51 (the initial drain discharge valve V35 is fully open), the control means 37 proceeds to step ST52 in order to evaluate the inflow amount of the steam drain D1.

  In step ST52, the control unit 37 determines whether or not the line pressure is equal to or higher than the set pressure PL. If YES in step ST52 (line pressure ≧ PL), there is a possibility that the drain discharge from the initial drain discharge line L35 may not catch up, so the control means 37 moves to step ST54 and the opening degree of the bypass valve V36. Is controlled to 100% (fully open). Thereby, the discharge route of the steam drain D1 is added.

  If NO (line pressure <PL) is determined in step ST52, the control unit 37 proceeds to step ST53 and determines whether or not the water level in the can is lower than the high water level H. If it is determined in step ST53 that NO (in-can water level ≧ H), the flash steam S3 having a reduced dryness may be sent due to carry-over of the hot water W3, so the control unit 37 proceeds to step ST54. Thus, the opening degree of the bypass valve V36 is controlled to 100% (fully open). Thereby, the inflow amount of the steam drain D1 to the flash tank 31 is reduced, and the lowering of the in-can water level is promoted.

  If YES in step ST53 (the water level in the can <H), the control unit 37 proceeds to step ST55 and determines whether the pressure in the can is lower than a fourth set pressure P4 (eg, 0.44 MPa) higher than the third set pressure. Judge whether or not. If NO (can internal pressure ≧ P4) is determined in step ST55, the internal pressure of the can has increased to near the maximum operating pressure of the flash tank 31, so the control means 37 proceeds to step ST54 and the opening degree of the bypass valve V36. Is controlled to 100% (fully open). Thereby, the inflow amount of the steam drain D1 to the flash tank 31 is reduced, and the decrease in the can internal pressure is promoted.

  If YES in step ST55 (can internal pressure <P4), the control means 37 proceeds to step ST56 and determines whether or not the water level in the can is lower than the middle water level M. If NO (in-can water level ≧ M) is determined in step ST56, the control unit 37 proceeds to step ST57 and maintains the opening degree of the bypass valve V36 at 100% in order to promote the lowering of the in-can water level.

  If it is determined as YES in step ST56 (water level in the can <M), the control unit 37 proceeds to step ST58 and determines whether or not the pressure in the can is less than a third set pressure P3 (for example, 0.34 MPa). If NO (in-can pressure ≧ P3) is determined in step ST58, the control unit 37 proceeds to step ST57 and maintains the opening degree of the bypass valve V36 at 100% in order to promote the decrease in the in-can pressure. On the other hand, if YES in step ST58 (can internal pressure <P3), since the can internal pressure and the water level in the can are within the appropriate ranges, the control unit 37 proceeds to step ST59 and sets the opening of the bypass valve V36 to 0. % (Fully closed).

  By the way, when the bypass valve V36 is controlled from the fully closed state to the fully open state and the recovery amount of the steam drain D1 is limited as in this control, there is a concern that the first drain line L21 may vibrate due to the above-described causes. . Therefore, when the opening degree of the bypass valve V36 is controlled to 100%, it is preferable to simultaneously open the exhaust valve V14 of the fifth steam line L15. Since the steam drain D1 is smoothly discharged from the first drain line L21 by letting a part of the flash steam generated by the pressure reduction of the steam drain D1 to the fifth steam line L15, the vibration of the first drain line L21 is effective. Is suppressed.

[E '] Control of bypass valve V36 (proportional control example)
The control of the bypass valve V36 by the control means 37 may employ proportional control other than the two-position control shown in FIG. FIG. 8 is a flowchart relating to proportional control of the bypass valve V36. In this control, the control means 37 acquires the detected pressure of the first pressure sensor 34A as the in-can pressure. Moreover, the control means 37 acquires the detected water level of both the water level detectors 33A and 33B as the water level in the can. In step ST61, the control means 37 determines whether or not the control state of the initial drain discharge valve V35 is the opening degree 100%. If YES in step ST61 (initial drain discharge valve V35 is fully open), control means 37 proceeds to step ST62 in order to evaluate the inflow amount of steam drain D1.

  In step ST62, the control means 37 determines whether or not the line pressure is equal to or higher than the set pressure PL. If YES in step ST62 (line pressure ≧ PL), there is a possibility that the drain discharge from the initial drain discharge line L35 may not catch up, so the control means 37 moves to step ST64 and the opening degree of the bypass valve V36. Is controlled to 100% (fully open). Thereby, the discharge route of the steam drain D1 is added.

  When it is determined NO (line pressure <PL) in step ST62, the control unit 37 proceeds to step ST63 and determines whether or not the water level in the can is lower than the high water level H. If it is determined in step ST63 that NO (in-can water level ≧ H), the flash steam S3 having a reduced dryness may be sent due to carry-over of the hot water W3, so the control unit 37 proceeds to step ST64. Thus, the opening degree of the bypass valve V36 is controlled to 100% (fully open). Thereby, the inflow amount of the steam drain D1 to the flash tank 31 is reduced, and the lowering of the in-can water level is promoted. The opening degree 100% is also the maximum set opening degree (high select) of proportional control.

  If YES in step ST63 (the water level in the can <H), the control unit 37 proceeds to step ST65 and determines whether or not the water level in the can is less than the lower limit water level LL. If YES in step ST63 (in-can water level <LL), in order to increase the inflow amount of the steam drain D1, the control means 37 proceeds to step ST66 and controls the opening degree of the bypass valve V36 to 20%. As a result, the water level in the can is recovered and the generation of the flash steam S3 is promoted. The opening 20% is also the minimum set opening (low select) for proportional control.

  If it is determined NO in step ST65 (in-can water level ≧ LL), the control unit 37 proceeds to step ST67 and determines whether or not the in-can pressure is less than a fourth set pressure P4 (for example, 0.44 MPa). If NO (in-can pressure ≧ P4) is determined in step ST67, the can-inside pressure has increased to near the maximum working pressure of the flash tank 31, so the control means 37 proceeds to step ST64 and the opening degree of the bypass valve V36. Is controlled to 100% (fully open). Thereby, the inflow amount of the steam drain D1 to the flash tank 31 is reduced, and the decrease in the can internal pressure is promoted.

  If YES in step ST67 (can internal pressure <P4), the control unit 37 proceeds to step ST68 and determines whether the internal pressure in the can is less than a third set pressure P3 (for example, 0.34 MPa). If YES in step ST68 (can internal pressure <P3), the internal pressure of the can is in the proper range, so the control unit 37 proceeds to step ST66 and controls the opening degree of the bypass valve V36 to 20%. On the other hand, if NO (in-can pressure ≧ P3) is determined in step ST68, the control unit 37 proceeds to step ST69 and adjusts the opening degree of the bypass valve V36 in order to promote the decrease in the in-can pressure. Specifically, the opening of the bypass valve V36 is set to the can internal pressure so that the opening is 20% when the can internal pressure is the third set pressure P3 and the opening is 100% when the can internal pressure is the fourth set pressure P4. Based on the proportional control, the inflow amount of the steam drain D1 is adjusted. As a result, the internal pressure of the can is maintained in an appropriate range, and high-quality flash steam S3 having a high dryness can be stably supplied.

  The range of the opening degree in the proportional control is set in consideration of vibration suppression of the first drain line L21 communicating with the water supply tank 40. When the bypass valve V36 is controlled from the fully closed state to the fully opened state and the recovery amount of the steam drain D1 is limited as in the two-position control shown in FIG. 7, the first drain line L21 vibrates due to the above-described causes. There are concerns. In view of this, the bypass valve V36 is controlled to be equal to or higher than the lower limit opening, and is constantly circulated through the first drain line L21 while generating a small amount of flash steam from the steam drain D1. Thereby, since the rapid outflow of the flash steam generated when the bypass valve V36 is controlled to be fully opened is reduced, the vibration of the first drain line L21 is suppressed.

[F] Control of Blow Valve V34 FIG. 9 is a flowchart relating to control of the blow valve V34 by the control means 37. In this control, the control means 37 acquires the detected pressure of the first pressure sensor 34A as the in-can pressure. Moreover, the control means 37 acquires the detected water level of both the water level detectors 33A and 33B as the water level in the can. In step ST71, the control means 37 determines whether or not the water level in the can is less than the middle water level M. If YES in step ST71 (the water level in the can <M), the control means 37 moves to step ST72 because there is no possibility that the flash steam S3 having a reduced dryness will be sent due to carry-over of the hot water W3. Then, the opening degree of the blow valve V34 is controlled to 0% (fully closed).

  If it is determined in step ST71 that NO (in-can water level ≧ M), the control unit 37 proceeds to step ST73, and determines whether or not the in-can pressure is less than a second set pressure P2 (for example, 0.1 MPa). If NO (in-can pressure ≧ P2) is determined in step ST73, since the discharge pressure of the hot water W3 from the flash tank 31 is sufficiently secured, the control means 37 proceeds to step ST72 and the blow valve The opening degree of V34 is controlled to 0% (fully closed).

  If YES in step ST73 (can internal pressure <P2), the control unit 37 proceeds to step ST74 and determines whether or not the water level in the can is lower than the high water level H. If YES in step ST74 (the water level in the can <H), there is no possibility that the hot water W3 carries over, so the control means 37 proceeds to step ST75 and sets the opening of the blow valve V34 to 0% (all Keep it closed.

  If it is determined in step ST74 that NO (in-can water level ≧ H), the control means 37 proceeds to step ST76, and the can-internal pressure is lower than the second set pressure P2 and lower than the first set pressure P1 (for example, 0.05 MPa). Determine whether or not. If NO (in-can pressure ≧ P1) is determined in step ST76, since the discharge pressure of the hot water W3 from the flash tank 31 is sufficiently secured, the control means 37 proceeds to step ST75 and the blow valve The opening of V34 is kept 0% (fully closed).

  If YES in step ST76 (can internal pressure <P1), since the discharge pressure of the hot water W3 from the flash tank 31 is not sufficiently ensured, the control means 37 moves to step ST77 and the blow valve The opening degree of V34 is controlled to 100% (fully open). Thereby, in addition to the discharge of the warm water W3 from the drain discharge valve V33, the warm water W3 is also discharged from the blow valve V34, and the water level in the can can be maintained in an appropriate range.

[G] Control of inlet valve V31 (proportional control example based on can internal pressure)
FIG. 10 is a flowchart relating to proportional control based on the pressure inside the can of the inlet valve V31 by the control means 37. In this control, the control means 37 acquires the detected pressure of the first pressure sensor 34A as the in-can pressure. In step ST81, the control means 37 determines whether or not the control state of the initial drain discharge valve V35 is an opening degree of 100%. If YES in step ST81 (the initial drain discharge valve V35 is fully open), the control means 37 moves to step ST83 to prevent the low temperature steam drain D1 from flowing into the flash tank 31, and opens the inlet valve V31. The degree is controlled to 0% (fully closed).

  If it is determined NO in step ST81 (the initial drain discharge valve V35 is fully closed), the control unit 37 proceeds to step ST82, and determines whether or not the can internal pressure is equal to or higher than a second set pressure (for example, 0.1 MPa). . If YES in step ST82 (can internal pressure ≧ P2), the air pressure of the flash steam S3 may exceed the suction upper limit pressure of the steam booster 15. Therefore, the control unit 37 proceeds to step ST83 and enters the inlet. The opening degree of the valve V31 is controlled to 0% (fully closed). As a result, the flow of the steam drain D1 into the flash tank 31 is interrupted, and the decrease in the pressure inside the can and thus the supply pressure of the flash steam S3 is promoted.

  If it is determined in step ST82 that NO (in-can pressure <P2), the control unit 37 proceeds to step ST84. In step ST83, the control means 37 determines whether or not the can internal pressure is equal to or lower than a first set pressure P1 (for example, 0.05 MPa). If YES in step ST84 (can internal pressure ≦ P1), the air pressure of the flash steam S3 may fall below the suction lower limit pressure of the steam booster 15, so the control means 37 proceeds to step ST85 and enters the inlet. The opening degree of the valve V31 is controlled to 100% (fully open). As a result, the inflow amount of the steam drain D1 into the flash tank 31 is maximized, and the increase in the internal pressure of the can and hence the supply pressure of the flash steam S3 is promoted.

  If NO (in-can pressure> P1) is determined in step ST84, the control means 37 proceeds to step ST86 to stabilize the opening pressure of the inlet valve V31 in order to stabilize the supply pressure of the flash steam S3 to the steam booster 15. adjust. Specifically, the opening of the inlet valve V31 is set to the can internal pressure so that the opening is 0% when the can internal pressure is the first set pressure P1, and the opening is 100% when the can internal pressure is the second set pressure P2. Proportional control is performed based on this to adjust the air supply pressure of the flash steam S3. As a result, the suction pressure of the steam booster 15 is maintained in an appropriate range, and stable supply of the low-pressure steam S2 becomes possible.

[G ′] Control of inlet valve V31 (example of proportional control based on water level in can)
The control of the inlet valve V36 by the control means 37 is preferably based on the can internal pressure shown in FIG. 10 in order to maintain the suction pressure within an appropriate range when the steam booster 15 is installed. However, when the steam booster 15 is not installed, control based on the water level in the can can be employed. When this control is adopted, both the water level detectors 33A and 33B are preferably changed to a water level sensor (for example, a capacitive level sensor) that can continuously detect the water level in the can.

  FIG. 11 is a flowchart relating to proportional control based on the water level in the can of the inlet valve V31 by the control means 37. In this control, the control means 37 acquires the water level detected by the water level sensor as the water level in the can. In step ST91, the control means 37 determines whether or not the control state of the initial drain discharge valve V35 is an opening degree of 100%. If YES in step ST91 (the initial drain discharge valve V35 is fully open), the control means 37 moves to step ST92 to prevent the low temperature steam drain D1 from flowing into the flash tank 31, and opens the inlet valve V31. The degree is controlled to 0% (fully closed).

  If it is determined NO in step ST91 (the initial drain discharge valve V35 is fully closed), the control unit 37 proceeds to step ST93 and determines whether or not the water level in the can is the middle water level M or higher. If YES in step ST93 (in-can water level ≧ M), since the in-can water level tends to increase, the control unit 37 proceeds to step ST94 and controls the opening of the inlet valve V31 to 10%. Thereby, the inflow amount of the steam drain D1 to the flash tank 31 is reduced, and the carry over of the hot water W3 is prevented. In addition, this opening degree 10% is also the minimum setting opening degree (low select) of proportional control.

  If it is determined in step ST93 that NO (in-can water level <M), the control means 37 proceeds to step ST95. In step ST95, the control means 37 determines whether or not the water level in the can is lower than the lower limit water level LL. If YES in step ST95 (the water level in the can <LL), the storage amount of the steam drain D1 may be lost. Therefore, the control unit 37 proceeds to step ST96 and sets the opening of the inlet valve V31 to 100% (fully open). ) To control. Thereby, the inflow amount of the steam drain D1 to the flash tank 31 is maximized, and the generation of the flash steam S3 is promoted. The opening degree 100% is also the minimum setting opening degree (proper selection) of proportional control.

  When it is determined NO in step ST95 (in-can water level ≧ LL), the control means 37 moves to step ST97 and adjusts the opening degree of the inlet valve V31 in order to stabilize the inflow amount of the steam drain D1. Specifically, the opening degree of the inlet valve V31 is proportionally controlled based on the water level in the can so that the opening degree is 10% when the water level in the can is the middle water level M and 100% when the water level in the can is the lower limit water level LL. Then, the inflow amount of the steam drain D1 is adjusted. As a result, the water level in the can is maintained in an appropriate range, and it is possible to supply the flash steam S3 at a stable flow rate.

  According to the flash steam generator 30 according to the present embodiment, the following effects can be exhibited.

  In the flash steam generator 30 of the present embodiment, the control unit 37 opens the initial drain discharge valve V35 when the temperature detected by the temperature sensor 36 is equal to or lower than the first set temperature T1. Thereby, even if a large amount of initial drain flows from the high-pressure steam utilization facility 13, it is discharged from the initial drain discharge line L35, so that the inside of the can is not filled with water. As a result, when the high-temperature steam drain D1 is collected and the flash steam S3 is generated, the retained drain does not carry over, so the dryness of the flash steam S3 can be increased.

  Further, in the flash steam generator 30 of the present embodiment, the control means 37 sets the initial drain discharge valve V35 when the temperature detected by the temperature sensor 36 is equal to or higher than the second set temperature T2 higher than the first set temperature T1. Close. As a result, the high-temperature steam drain D1 can be selectively introduced into the flash tank 31, so that the pressure inside the can quickly rises and the discharge pressure of the hot water W3 is secured. As a result, the water level in the can can be maintained within an appropriate range, and carryover of the accumulated drain can be prevented.

  Moreover, in the flash steam generator 30 of this embodiment, the control means 37 closes the inlet valve V31, when opening the initial drain discharge valve V35. Thereby, since the inside of the can is not filled with the low temperature initial drain, the temperature does not decrease when the high temperature steam drain D1 is received. As a result, the flash steam S3 can be generated promptly after the start of receiving the high-temperature steam drain D1.

  In the flash steam generator 30 of the present embodiment, the control unit 37 opens the bypass valve V36 when the detected pressure of the second pressure sensor 35A is equal to or higher than the set pressure. In other words, the control means 37 is configured when the inflow amount of the steam drain D1 is excessive or the pressure in the pipe line of the drain recovery line L31 is increased due to the back pressure being applied to the initial drain discharge line L35. Guides a part of the steam drain D1 from the first drain line L21 (bypass line) to the water supply tank 40. As a result, it is possible to smoothly discharge the low temperature steam drain D1 from the steam trap 21, and to shorten the time until the generation of the flash steam S3.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. Although the modification of the flash steam generator 30 is described below, this invention is supported by the said embodiment thru | or modification.

<Temperature sensor position change>
If the temperature sensor 36 (drain temperature detection means) can detect the temperature of the steam drain D1 before flowing into the flash tank 31, it can be installed in another position instead of the drain recovery line L31. For example, the temperature sensor 36 may be installed in the first drain line L21 or the second drain line L22 near the steam trap 21. Even when the temperature of the steam drain D1 before flowing into the drain recovery line L31 is detected, the control of the initial drain discharge valve V35 can be performed without any trouble.

<Simplification of hot water discharge valve and omission of water level control>
When the water level in the can of the flash tank 31 can be maintained within a predetermined range (lower limit water level LL to high water level H) by proportional control of the bypass valve V36 (FIG. 8), the drain discharge valve V33 is used as a control valve. Alternatively, a manual valve can be used. The water level control by the drain discharge valve V33 can be omitted by replacing the drain discharge valve V33 with a manual valve. In this case, the drain discharge valve V33, which is a manual valve, is used after being adjusted to a valve opening corresponding to a minimum setting opening (for example, 20%) which is a low select of proportional control.

<Omission of steam booster>
When the amount of steam used in the low-pressure steam utilization facility 14 is relatively small and the flash rate in the flash tank 31 (the weight of flash steam generated from 1 kg of steam drain) can be kept low, the pressure of the flash steam S3 can be increased. Thus, the steam booster 15 can be omitted. When the steam booster 15 is omitted, the vacuum breaker valve V12 used for protection thereof may be omitted. Further, the proportional control of the inlet valve V31 based on the can internal pressure shown in FIG. 10 is also unnecessary.

<Other variations>
In the above embodiment, the flow path switching means 32 is composed of five control valves including the inlet valve V31, the steam supply valve V32, the drain discharge valve V33, the blow valve V34, the initial drain discharge valve V35, and the bypass valve V36. However, the number of control valves can be increased or decreased without departing from the spirit of the invention. For example, when there is no steam booster 15 and it is not necessary to adjust the suction pressure, the inlet valve V31 may be reduced.

  In the above embodiment, the water level detectors 33A and 33B in which five float switches are incorporated have been described as the in-can water level detection means 33. However, a water level detector (for example, a capacitive water level sensor or an ultrasonic water level sensor) that continuously detects the water level may be provided as the in-can water level detection means 33, and a water level detector of a stage detection type. And a continuous detection type water level detector may be provided.

  In the above embodiment, the flash steam generator 30 includes one flash tank 31, but the flash tank 31 is not limited to one and may include a plurality of flash tanks. In that case, the initial drain discharge line L35 and the initial drain discharge valve V35 may be provided for each flash tank, or may be provided one by one for the entire flash steam generator.

DESCRIPTION OF SYMBOLS 1 Steam system 10 Steam boiler apparatus group 11 Steam boiler unit 12 Steam header 13 High pressure steam utilization equipment 14 Low pressure steam utilization equipment 15 Steam booster 21 Steam trap 30 Flash steam generator 31 Flash tank 32 Distribution path switching means 33 Detection of water level in can Means 33A First water level detector 33B Second water level detector 34 Can pressure detection means 34A First pressure sensor 34B First pressure switch 35 Line pressure detection means 35A Second pressure sensor 35B Second pressure switch 36 Drain temperature detection means ( Temperature sensor)
37 Control means 38 Strainer 40 Water tank 50 Drain pit L11 1st steam line L12 2nd steam line L13 3rd steam line L14 4th steam line L15 5th steam line L21 1st drain line (bypass line)
L22 2nd drain line L23 3rd drain line L24 4th drain line L31 Drain recovery line L32 Steam supply line L33 Drain discharge line L34 Blow line L35 Initial drain discharge line L41 Boiler feed line L42 Supply water line V11 Pressure reducing valve V12 Vacuum break Valve V13 Check valve V14 Exhaust valve V31 Inlet valve V32 Steam supply valve V33 Drain discharge valve V34 Blow valve V35 Initial drain discharge valve V36 Bypass valve V37 Safety valve V38 Vacuum break valve V39 Check valve D1 Steam drain S1 High pressure steam S2 Low pressure steam S3 Flash steam W1 Make-up water W2 Boiler feed water W3 Hot water

Claims (4)

A flash tank that re-evaporates the recovered steam drain and separates it into flash steam and hot water;
A drain recovery line for recovering steam drain into the flash tank;
A steam supply line for supplying flash steam from the flash tank;
A drain discharge line for discharging hot water from the flash tank;
A bypass line for bypassing the steam drain to the flash tank;
An initial drain discharge line for discharging steam drain from the drain recovery line;
A flow path switching means comprising one or more control valves including at least an initial drain discharge valve provided in the initial drain discharge line;
A drain temperature detecting means for detecting the temperature of the steam drain flowing into the drain recovery line or flowing through the drain recovery line;
Control means for controlling the distribution path switching means,
The said control means opens the said initial drain discharge valve, when the detected temperature of the said drain temperature detection means is below 1st preset temperature, The flash steam generator characterized by the above-mentioned. The said control means closes the said initial drain discharge valve, when the detected temperature of the said drain temperature detection means is more than 2nd setting temperature higher than 1st setting temperature. Flash steam generator. The flow path switching means further includes an inlet valve provided in the drain recovery line,
The flash steam generator according to claim 2, wherein the control means closes the inlet valve when the initial drain discharge valve is opened. Line pressure detecting means for detecting the pressure in the drain recovery line upstream of the inlet valve,
4. The flash steam generator according to claim 3, wherein the control means opens a bypass valve provided in the bypass line when the detected pressure of the line pressure detecting means is equal to or higher than a set pressure.

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