JP2020046142A - Steam supply system - Google Patents

Abstract

To provide a steam supply system capable of achieving stable supply of steam even when pressure of steam ejected from an ejector becomes low.SOLUTION: A steam supply system 1 comprises: an ejector 30 which is provided in a connection part between a main steam supply line L1 supplying first steam, and a sub steam supply line L2 supplying second steam, and which sucks the second steam with the first steam as drive fluid; and a suction steam valve 50 provided in the sub steam supply line L2. A second steam generation device 20 comprises an evaporation unit 21 having a steam generation part 211 and a water storage part 212, and control means 90. The water storage part 212 has set water levels including at least a low water level L, an intermediate water level M and a high water level H. During driving the ejector 30, the control means 90 (i) closes the suction steam valve 50 when a detected water level is less than the low water level L, and (ii) opens the suction steam valve 50 when a detected water level is the intermediate water level M or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steam generator that generates low-pressure steam and a steam supply system that includes an ejector that pressurizes the low-pressure steam.

  BACKGROUND ART Conventionally, there has been proposed a steam generator that generates low-pressure steam (for example, steam having a pressure of less than 0.2 MPa) by using exhaust heat generated in a factory or the like (for example, see Patent Document 1). The low-pressure steam generated by the steam generator is combined with the high-pressure steam (e.g., steam of 0.8 MPa or more) generated by a once-through boiler or the like, and the medium-pressure steam (e.g., 0.2 MPa to 0.7 MPa) is added. There has also been proposed a steam supply system for supplying steam (load) to a load device (for example, see Patent Document 2).

JP-A-2005-206492 JP 2015-102258 A

  In the steam supply system proposed in Patent Literature 2, low pressure steam is increased to medium pressure steam by using low pressure steam as suction steam and using high pressure steam as driving steam using an ejector. In such a steam supply system, the pressure of the ejected steam from the ejector fluctuates due to a change in the amount of steam used in the load equipment, so that the water level of the boiler water stored in the water header of the steam generator fluctuates greatly. There was a case.

  For example, when the amount of steam used in the load equipment increases and the pressure of the steam discharged from the ejector decreases, the flow rate of the driving steam increases, and the suction amount of the low-pressure steam increases rapidly. If the steam generation amount of the steam generation device can follow the suddenly increased suction amount, the water level of the water header tends to decrease. Further, when the amount of steam generated by the steam generator cannot follow the suddenly increased suction amount, the pressure of the evaporator (evaporation tank) tends to decrease. If the water level of the water header or the pressure of the evaporator is too low, the output of steam and the degree of dryness are reduced, and stable steam supply may not be performed.

  Therefore, an object of the present invention is to provide a steam supply system that can realize stable supply of steam even when the pressure of the steam discharged from the ejector is reduced.

  According to the present invention, a first steam generator for generating a first steam, a second steam generator for generating a second steam having a lower pressure than the first steam, and the first steam generator are generated by the first steam generator. A main steam supply line for supplying a first steam to a load device, a sub-steam supply line for supplying a second steam generated by the second steam generator to the main steam supply line, and a main steam supply line An ejector provided at a connection portion between the main steam supply line and the sub-steam supply line, wherein the ejector sucks the second steam using the first steam as a driving fluid, and a drive steam valve provided on the main steam supply line on a primary side of the ejector. , A suction steam valve provided in the sub-steam supply line, wherein the second steam generator includes a vapor generation unit having a steam generation unit connected to the sub-steam supply line, and a water storage unit; Water level detecting means for detecting the water level of the water storage section, a drain line for discharging the stored water from the water storage section, a drain valve provided in the drain line, the drive steam valve, the suction steam valve, and the drain valve Control means for controlling the water level, the water storage section has at least a set water level including a low water level, a medium water level, and a high water level, and the control means controls the driving steam valve to an open state. (E) closing the suction steam valve when the detected water level of the water level detecting means is lower than the low water level; and (ii) closing the suction steam valve when the detected water level of the water level detecting means is higher than the medium water level. And a steam supply system for opening the suction steam valve.

  Further, the steam supply system includes: first pressure detecting means for detecting a pressure of the second steam generated by the steam generating unit; and temperature detecting means for detecting a temperature of the stored water. (Ii) closing the drain valve when the detected water level of the water level detecting means is equal to or higher than the middle water level and the detected pressure of the first pressure detecting means is lower than the first set pressure; It is preferable that the suction steam valve be opened when the temperature is equal to or higher than the middle water level, the temperature detected by the temperature detecting means is higher than a set temperature, and the pressure detected by the first pressure detecting means is higher than zero.

  The control means controls the drive steam valve to an open state to drive the ejector, and (iii) opens the drain valve when the water level detected by the water level detection means is higher than or equal to a high water level; iv) When the water level detected by the water level detection means is lower than the high water level, the drain valve is preferably closed.

  The control means controls the drive steam valve to an open state to drive the ejector, and (iii) closes the suction steam valve when the water level detected by the water level detection means is equal to or higher than a high water level. (Iv) Preferably, when the water level detected by the water level detecting means is lower than the high water level, the drain valve is closed and the suction steam valve is opened.

  Further, the steam supply system includes: first pressure detecting means for detecting a pressure of the second steam generated by the steam generating unit; and temperature detecting means for detecting a temperature of the stored water. (Iv) closing the drain valve when the detected water level of the water level detecting means is lower than the high water level and the detected pressure of the first pressure detecting means is lower than the first set pressure; It is preferable that the suction steam valve be opened when the temperature is equal to or higher than the middle water level, the temperature detected by the temperature detecting means is higher than a set temperature, and the pressure detected by the first pressure detecting means is higher than zero.

  The steam supply system further includes second pressure detection means for detecting a discharge-side steam pressure of the ejector, wherein the control means controls the drive steam valve to be open to drive the ejector, (iii) It is preferable that the drain valve be opened when the detected pressure of the second pressure detecting means exceeds a second set pressure and the detected water level of the water level detecting means is higher than or equal to a high water level.

  In addition, the second steam generator includes a tube through which a heat source fluid flows, and an evaporator in which a spray nozzle for spraying boiler water into the tube is disposed inside the container; and a boiler disposed below the evaporator. An evaporation unit having a water header in which water is stored, a water spray line for supplying boiler water in the water header to the spray nozzle, a water spray pump provided in the water spray line, and boiler water from the water header. A drain line that discharges water, a drain valve provided in the drain line, a makeup water line that supplies makeup water to the water header, and a flow rate adjusting unit that adjusts a flow rate of the heat source fluid flowing through the tube. Preferably, it is provided.

  The second steam generator includes an evaporation unit including a flash tank for re-evaporating the collected steam drain to separate the second steam and hot water, and a drain recovery line for collecting steam drain to the flash tank. It is preferable that a drain line for discharging hot water stored in the flash tank and a drain valve provided for the drain line be provided.

  According to the present invention, it is possible to provide a steam supply system capable of realizing stable steam supply even when the pressure of the steam discharged from the ejector is reduced.

It is a figure showing the whole steam supply system composition concerning a 1st embodiment of the present invention. It is a flowchart which shows the flow of the water level control including the standby control of the 2nd steam generator in the steam supply system of 1st Embodiment, and is a flowchart which mainly shows the flow of a process at the time of a low water level. It is a flowchart which shows the flow of the water level control including the standby control of the 2nd steam generator in the steam supply system of 1st Embodiment, and is a flowchart which shows the flow of a process at the time of a high water level. It is a flowchart which shows the flow of the water level control containing the standby control of the 2nd steam generator in the steam supply system of 1st Embodiment, and is a flowchart which shows the flow of the processing of warm-up control. It is a flowchart which shows the flow of the water level control which concerns on the modification of 1st Embodiment, and is a flowchart which shows the flow of a process at the time of a high water level. It is a figure showing the whole steam supply system composition concerning a 2nd embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of the steam supply system according to the first embodiment of the present invention.

  As shown in FIG. 1, the steam supply system 1 includes a first steam generator 10 that generates high-pressure steam as first steam, a second steam generator 20 that generates low-pressure steam as second steam, , A main steam supply line L1 for supplying high-pressure steam to the load device 100, a sub-steam supply line L2 for supplying low-pressure steam to the main steam supply line L1, and a connection portion between the main steam supply line L1 and the sub-steam supply line L2. And a drive steam valve 40 provided in the main steam supply line L1, a suction steam valve 50 provided in the sub-steam supply line L2, and a control device 90 as control means. In this specification, “line” is a general term for lines such as flow paths, paths, and conduits through which fluid can flow.

  The first steam generator 10 generates high-pressure steam (for example, steam of 0.8 MPa or more) as first steam. In the present embodiment, the first steam generator 10 includes a plurality of small once-through boilers 11, a steam header 12 for collecting steam generated by the plurality of small once-through boilers 11, and a plurality of small once-through boilers 11 And a collective steam line 13 for supplying the high-pressure steam generated in the above to the steam header 12.

  The second steam generator 20 generates low-pressure steam (for example, steam of 0.2 MPa or less) as the second steam. In the present embodiment, the second steam generator 20 is a shell-and-tube type evaporation that generates low-pressure steam by evaporating boiler water using a relatively low-temperature heat source fluid such as waste hot water generated in a factory or the like. It is composed of a vessel.

  As shown in FIG. 1, the second steam generator 20 includes an evaporating unit 21, a heat source fluid supply line L3, a heat source fluid discharge line L4, a water spray line L5, a makeup water line L6, and a bypass line L7. , A constant-rate blow line L8 and a concentration blow line L9 as drainage lines.

  The evaporating unit 21 forms a main body of the second steam generator 20. The evaporating unit 21 includes an evaporator 211 as a steam generating part, a water header 212 as a water storage part, and a water level sensor 28.

The evaporator 211 includes a pressure vessel in which a tube 215 and a spray nozzle 216 are arranged, and generates low-pressure steam.
The tube 215 extends in the horizontal direction inside the evaporator 211. More specifically, a plurality of tubes 215 are arranged inside the evaporator 211 at predetermined intervals in the horizontal direction, and a plurality of tubes 215 are also arranged at predetermined intervals in the height direction. Inside the tube 215, hot water as a heat source fluid flows.
The spray nozzle 216 is disposed above the tube 215 inside the evaporator 211. The spray nozzle 216 sprays boiler water toward the tube 215.

  The evaporator 211 is provided with a safety valve 214. When the pressure inside the evaporation unit 21 exceeds a predetermined pressure, the safety valve 214 releases steam to the outside to reduce the pressure inside the evaporation unit 21.

  The water header 212 is arranged below the evaporator 211. In the water header 212, make-up water supplied from the make-up water line L6 is stored as boiler water (reserved water), and boiler water (retained water) that has not turned into steam inside the evaporator 211 is stored. . The evaporator 211 and the water header 212 are connected via a pipe 213.

  The water level sensor 28 is a water level detection unit that detects the level of boiler water stored inside the water header 212. In the present embodiment, the water level sensor 28 is configured as a level switch including a cylindrical main body 281 and a plurality of electrode rods 282 arranged inside the main body 281. The main body 281 is arranged at a position at the same height as the water header 212. The lower end of the main body 281 is connected to the lower end of the water header 212 via the water spray line L5. The upper end of the main body 281 is connected to a sub-steam supply line L2 described later. Thereby, the water level inside the cylindrical main body 281 becomes equal to the water level of the water header 212.

  In the present embodiment, the water level sensor 28 includes four electrode rods 282L, 282M, 282H, 282HH having different lengths. The electrode rod 282L detects the low water level L of the water header 212. The electrode rod 282M detects the middle water level M of the water header 212. The electrode rod 282H detects the high water level H of the water header 212. The electrode rod 282HH detects an extremely high water level HH of the water header 212. By the combination of ON / OFF of each electrode rod, the water header 212 of the present embodiment is set in five stages of lower water level L, lower water level L or higher, middle water level M or higher, high water level H or higher, and ultra high water level HH or higher. Water level is detected.

The combination of ON / OFF of the electrode bar at each set water level is as follows.
◎ Less than low water level L: all electrode rods 282L, 282M, 282H, 282HH are OFF
◎ Low water level L or higher (less than middle water level M): electrode rod 282L is ON; electrode rods 282M, 282H, 282HH are OFF
◎ Middle water level M or higher (less than high water level H): electrode rods 282L and 282M are ON; electrode rods 282H and 282HH are OFF
◎ High water level H or higher (less than ultra high water level HH): electrode rods 282L, 282M, 282H are ON; electrode rod 282HH is OFF
◎ Ultra high water level HH or more: all electrode rods 282L, 282M, 282H, 282HH are ON

  The heat source fluid supply line L3 supplies the tube 215 with hot water as a heat source. The upstream side of the heat source fluid supply line L3 is connected to a waste heat source that supplies hot water. The downstream side of the heat source fluid supply line L3 is connected to one end side of the tube 215.

  The heat source fluid discharge line L4 circulates through the tube 215 and discharges hot water used as a heat source to the outside. The upstream side of the heat source fluid discharge line L4 is connected to the other end of the tube 215.

The water spray line L5 connects the water header 212 and the spray nozzle 216, and supplies the boiler water stored in the water header 212 to the spray nozzle 216. In the water spray line L5, a water spray pump 23 and a boiler water temperature sensor 24 as temperature detecting means are arranged.
The water spray pump 23 pumps up the boiler water stored in the water header 212 to the spray nozzle 216. The boiler water temperature sensor 24 detects the temperature of the boiler water flowing through the water spray line L5.

  The makeup water line L6 connects the water header 212 with a makeup water tank or the like (not shown) storing makeup water, and supplies makeup water to the water header 212. A makeup water pump 27 is arranged on the makeup water line L6. The makeup water pump 27 supplies makeup water supplied from a makeup water tank or the like to the water header 212.

  The bypass line L7 connects the heat source fluid supply line L3 and the heat source fluid discharge line L4. A hot water three-way valve 22 as a flow rate adjusting means is disposed at a connection portion between the bypass line L7 and the heat source fluid supply line L3. The hot water three-way valve 22 adjusts the opening degree to adjust the flow rate of the hot water flowing from the heat source fluid supply line L3 to the tube 215 and the flow rate of the hot water flowing to the bypass line L7.

  The constant rate blow line L8 and the concentration blow line L9 branch off from the water spray line L5. The constant rate blow line L8 and the concentration blow line L9 drain a part of the boiler water stored in the water header 212. On the constant rate blow line L8 and the concentration blow line L9, a constant rate blow valve 25 and a concentration blow valve 26 as drain valves are disposed, respectively.

  According to the above-described second steam generator 20, first, hot water serving as a heat source is supplied to the tube 215 through the heat source fluid supply line L3. The hot water supplied to the tube 215 flows inside the evaporator 211. On the other hand, inside the evaporator 211, boiler water is sprayed from the spray nozzle 216 toward the tube 215. Further, the inside of the evaporator 211 is maintained at a negative pressure (for example, about -0.04 MPa). As a result, the hot water flowing through the tube 215 is deprived of heat by the sprayed boiler water to lower the temperature, and is discharged through the heat source fluid discharge line L4.

  Further, a thin liquid film is formed on the surface of the tube 215 through which the hot water flows, by spraying boiler water from the spray nozzle 216. As described above, the thin liquid film is formed on the surface of the tube 215 in the state where the pressure is maintained at the negative pressure, so that the temperature difference between the hot water flowing through the tube 215 and the boiler water sprayed by the spray nozzle 216. Is relatively small, it is possible to efficiently generate low-pressure steam.

The low-pressure steam generated inside the evaporator 211 is led out from the sub-steam supply line L2.
Boiler water that has not become steam inside the evaporator 211 is stored in the water header 212. The boiler water stored in the water header 212 is pumped up to the spray nozzle 216 by the water spray pump 23 through the water spray line L5, and sprayed on the tube 215 again.

  The constant rate blow line L8 and the concentration blow line L9 drain the boiler water stored in the water header 212. The constant-rate blow line L8 constantly discharges a fixed percentage of the boiler water with respect to the make-up water amount by repeatedly opening and closing the constant-rate blow valve 25 with a predetermined valve closing time and a valve opening time. The concentration blow line L9 monitors the concentration of the boiler water stored in the water header 212 by an electric conductivity sensor (not shown), and when the concentration exceeds the upper limit concentration, opens the concentration blow valve 26 and sets the lower limit concentration. When the temperature falls below the predetermined value, the concentration blow valve 26 is closed.

  When the boiler water circulating between the water spray line L5 and the water header 212 decreases (for example, when the detection position of the water level sensor 28 is lower than the middle water level M), the replenishment water pump 27 is driven to replenish. Supply water is supplied to the water header 212 from the water line L6.

The main steam supply line L1 connects the first steam generator 10 (steam header 12) and the load device 100. The main steam supply line L1 supplies the high-pressure steam generated by the first steam generator 10 to the load device 100.
The base end of the sub-steam supply line L2 is connected to the second steam generator 20 (evaporator 211), and supplies the low-pressure steam generated by the second steam generator 20 to the main steam supply line L1.

The ejector 30 is provided at a connection portion between the main steam supply line L1 and the sub steam supply line L2. The ejector 30 uses the high-pressure steam flowing through the main steam supply line L1 as a drive fluid (drive steam) to suck the low-pressure steam supplied from the sub-steam supply line L2.
The ejector 30 includes a driving steam inlet 31, a suction steam inlet 32, and a discharge steam outlet 33. In the present embodiment, the main steam supply line L1 is divided into an upstream main steam supply line L11 and a downstream main steam supply line L12, and the drive steam inlet 31 of the ejector 30 is The downstream end of the steam supply line L11 is connected, and the discharge steam outlet 33 is connected to the upstream end of the downstream main steam supply line L12. The front end side of the sub-steam supply line L2 is connected to the suction steam inlet 32.

  The drive steam valve 40 is provided on the upstream main steam supply line L11. The drive steam valve 40 is configured by a motor valve whose opening can be adjusted, and adjusts the opening to adjust the flow rate of high-pressure steam (drive steam) flowing through the main steam supply line L1.

  The suction steam valve 50 is provided in the sub-steam supply line L2. The suction steam valve 50 is also configured by a motor valve whose opening can be adjusted, and adjusts the opening to adjust the flow rate of low-pressure steam (suction steam) flowing through the sub-steam supply line L2.

  In the present embodiment, a second steam pressure sensor 80 as a second pressure detecting means and a pressure regulating valve 60 are arranged in the main steam supply line L1. The second steam pressure sensor 80 is arranged on the downstream main steam supply line L12, and detects the pressure of steam on the discharge side of the ejector 30. The pressure regulating valve 60 is disposed downstream of the second steam pressure sensor 80 in the downstream main steam supply line L12. The pressure adjusting valve 60 adjusts the pressure of the steam supplied to the load device 100 to a predetermined pressure.

  Further, a first steam pressure sensor 70 as first pressure detecting means is disposed in the sub steam supply line L2. The first steam pressure sensor 70 can detect the pressure inside the evaporator 211 by detecting the steam pressure inside the sub-steam supply line L2.

  The control device 90 includes a storage unit and a control unit. The control device 90 performs various operations based on information stored in the storage unit and information detected by various sensors such as the boiler water temperature sensor 24, the water level sensor 28, the first steam pressure sensor 70, and the second steam pressure sensor 80. The operation of the entire steam supply system 1 is controlled by controlling a pump, a valve, and the like.

  According to the above steam supply system 1, the high-pressure steam generated by the first steam generator 10 flows through the main steam supply line L1, flows into the ejector 30 from the drive steam inlet 31, and is used as drive steam. The low-pressure steam generated by the second steam generator 20 flows through the sub-steam supply line L2, and is sucked into the ejector 30 from the suction steam inlet 32. Then, medium-pressure steam of about 0.2 to 0.4 MPa is discharged from the ejector 30, and is supplied to the load device 100 through the downstream main steam supply line L12.

  Here, in the steam supply system, the pressure of the steam discharged from the ejector fluctuates due to a change in the amount of steam used in the load device, so that the level of the boiler water stored in the water header of the second steam generator is reduced. There was a case where it fluctuated greatly.

  For example, when the amount of steam used in the load equipment increases and the pressure of the steam discharged from the ejector decreases, the flow rate of the driving steam increases, and the suction amount of the low-pressure steam increases rapidly. If the amount of steam generated by the second steam generator can follow the suddenly increased suction amount, the water level of the water header is likely to decrease. Further, when the amount of steam generated by the second steam generator cannot follow the rapidly increased suction amount, the pressure of the evaporator tends to decrease. If the water level of the water header or the pressure of the evaporator is too low, the effective suction head (NPSH) is lowered, and cavitation occurs in the water spray pump that circulates and sprays the boiler water, which may lead to failure. When the second steam generator is stopped to protect the water spray pump, it takes time to restart the steam generation, and it becomes impossible to supply a stable steam.

  Therefore, the control device 90 of the present embodiment supplies the generated low-pressure steam to the main steam supply line L1 without stopping the generation of steam in the second steam generation device 20 according to the water level of the water header 212. By performing the standby control for controlling, stable supply of steam is realized without stopping the second steam generator 20.

Hereinafter, standby control of the second steam generator 20 in the present embodiment will be described.
In the steam supply system 1, when the medium-pressure steam is normally supplied to the load device 100, the high-pressure steam is supplied from the first steam generator 10 to the main steam supply line L <b> 1, and the second steam generator 20. Supplies low-pressure steam to the sub-steam supply line L2. In this state, the drive steam valve 40 and the suction steam valve 50 are opened to drive the ejector 30, and the low-pressure steam is sucked using the high-pressure steam supplied from the upstream main steam supply line L11 to the ejector 30 as the drive steam, and Medium-pressure steam is discharged to the side main steam supply line L12 and supplied to the load device 100.

[Control at low water level]
In this state, when the water level detected by the water level sensor 28 becomes lower than the low water level L (when the electrode rods 282L, 282M, 282H, and 282HH are all turned off), the control device 90 turns on the second steam generator 20. The suction steam valve 50 is closed without stopping the operation. Accordingly, the supply of the low-pressure steam to the main steam supply line L1 is stopped, so that the water pressure in the second steam generator 20 is maintained while preventing the water level of the water header 212 from further lowering.

  Then, when the detected water level of the water level sensor 28 is equal to or higher than the middle water level M in a state where the suction steam valve 50 is closed (the electrode rods 282L and 282M are ON; the electrode rods 282H and 282HH are OFF). ), The suction steam valve 50 is opened. Thereby, when the water level of the water header 212 recovers, the supply of the low-pressure steam is immediately restarted.

More specifically, when the detected water level of the water level sensor 28 is equal to or higher than the middle water level M in a state where the suction steam valve 50 is closed, the control device 90 sets the detection pressure of the first steam pressure sensor 70 in advance. It is determined whether the pressure is lower than the first set pressure P1 which is a positive pressure. Then, when the detected pressure is lower than the first set pressure P1, the fixed-rate blow valve 25 is closed (if closed, the close is maintained). If the detected pressure is equal to or higher than the first set pressure P1, the fixed-rate blow valve 25 is opened (permitting the opening and closing operations to be repeated).
Thereafter, the control device 90 determines that the water level detected by the water level sensor 28 is equal to or higher than the middle water level M, the detection temperature of the boiler water temperature sensor 24 is equal to or higher than the preset temperature T1, and the detection pressure of the first steam pressure sensor 70 is zero. In the above case, the suction steam valve 50 is opened. Thereby, the suction steam valve 50 can be opened in a state where the water level of the water header 212 is recovered, the boiler water is heated to a predetermined temperature, and the pressure of the evaporator 211 is not a negative pressure. Steam supply is resumed.

[Control at high water level]
Further, the control device 90 controls the drive steam valve 40 to be in the open state, and when the ejector 30 is being driven, when the water level detected by the water level sensor 28 becomes higher than the high water level H (the electrode rods 282L, 282M, and 282H are turned on). When the electrode rod 282HH is turned off), the constant-rate blow valve 25 is opened, and when the water level detected by the water level sensor 28 becomes lower than the high water level H (the electrode rods 282L and 282M are turned on; When it is turned off), the constant rate blow valve 25 is closed.
Here, it is preferable that the control device 90 opens the constant-rate blow valve 25 and closes the suction steam valve 50, closes the constant-rate blow valve 25, and opens the suction steam valve 50. Thereby, the water level of the water header 212 can be appropriately controlled, and by closing the suction steam valve 50 when the water level of the water header 212 rises, the dryness of the low-pressure steam supplied to the main steam supply line L1 can be reduced. Reduction is prevented.

  More specifically, when the control device 90 has reached the high water level H or more and opened the constant-rate blow valve 25 and closed the suction steam valve 50, when the water level detected by the water level sensor 28 has become lower than the high water level H, the control device 90 sets the first steam pressure. It is determined whether the pressure detected by the sensor 70 is lower than the first set pressure P1. Then, when the detected pressure is lower than the first set pressure P1, the constant rate blow valve 25 is closed. Thereafter, the control device 90 determines whether the water level detected by the water level sensor 28 is equal to or higher than the middle water level M, the detection temperature of the boiler water temperature sensor 24 is equal to or higher than the set temperature T1, and the detection pressure of the first steam pressure sensor 70 is equal to or higher than zero. Then, the suction steam valve 50 is opened.

  Further, the control device 90 controls the drive steam valve 40 to be in the open state and drives the ejector 30 so that the detected pressure of the second steam pressure sensor 80 exceeds the second set pressure P2 set in advance, and When the water level detected by the water level sensor 28 becomes equal to or higher than the high water level H, the constant rate blow valve 25 may be opened. Thus, when the low pressure steam is not sufficiently sucked in the ejector 30 due to the increase in the pressure on the secondary side of the ejector 30 and the water level of the water header 212 rises, the water level is forcibly reduced. .

  Next, a specific control flow of the second steam generator 20 in the steam supply system 1 of the present embodiment will be described with reference to FIGS. FIGS. 2 to 5 are flowcharts showing the flow of water level control including standby control of the second steam generator 20 in the steam supply system 1. In the control of the second steam generator 20 described below, the spraying of the boiler water from the spray nozzle 216 and the supply of the hot water to the tube 215 are continued unless otherwise described. Has been done.

  In the steam supply system 1, when the medium-pressure steam is being supplied to the load device 100, the drive steam valve 40 and the suction steam valve 50 are opened to drive the ejector 30, and the ejector 30 is moved from the upstream main steam supply line L <b> 11. The low-pressure steam is sucked using the high-pressure steam supplied to the as a driving steam, the medium-pressure steam is discharged to the downstream main steam supply line L12, and is supplied to the load device 100.

  In this case, as shown in FIG. 2, in step ST1, the control device 90 determines whether the water level detected by the water level sensor 28 is equal to or higher than the middle water level M. If this determination is YES, the process proceeds to step ST21 (see FIG. 3) or step ST20 (see FIG. 5). If the determination is NO, the process moves to step ST2.

  In step ST2, the control device 90 outputs an operation command to the makeup water pump 27, and starts supplying makeup water to the water header 212. Then, the process proceeds to step ST3.

  In step ST3, the control device 90 keeps the state in which the water level detected by the water level sensor 28 is lower than the low water level L for a predetermined time (for example, 30 seconds) in a state where the supply water is supplied by the make-up water pump 27. Is determined. If this determination is YES (the state where the water level is below the low water level L despite the supply of makeup water to the water header 212 being continued), the process proceeds to step ST4. If the determination is NO, the process returns to step ST1.

  In step ST4, the control device 90 closes the suction steam valve 50 and stops the supply of the low-pressure steam to the main steam supply line L1. Then, the process proceeds to step ST5.

  In step ST5, the control device 90 determines whether the water level detected by the water level sensor 28 is equal to or higher than the middle water level M. If this determination is YES (when the water level has recovered), the process proceeds to step ST6. When the determination is NO (when the water level has not recovered), the process proceeds to step ST11.

In step ST6, the control device 90 determines whether the pressure detected by the first vapor pressure sensor 70 is lower than the first set pressure. If this determination is YES, the process proceeds to step ST7. If the determination is NO, the process moves to step ST8.
In step ST7, the control device 90 closes the constant rate blow valve 25, and the process proceeds to step ST9.

  In step ST8, the control device 90 opens the constant-rate blow valve 25 and lowers the water level of the water header 212, thereby lowering the pressure inside the evaporator 211. Then, the process returns to step ST6.

  In step ST9, control device 90 performs warm-up control (see FIG. 4, described later), and the process proceeds to step ST10.

  In step ST10, the control device 90 opens the suction steam valve 50 and restarts the supply of the low-pressure steam to the main steam supply line L1. Then, the process returns to step ST1.

  On the other hand, if the determination in step ST5 is NO, in step ST11, control device 90 determines whether or not the state in which the water level detected by water level sensor 28 is lower than the low water level has continued for a predetermined time (for example, 60 seconds). Is determined. If this determination is YES, the process moves to step ST12. If the determination is NO, the process returns to step ST5.

  In step ST12, the control device 90 issues a warning regarding the low water level state, and completes the process.

  Next, the process of the control device 90 when it is determined in step ST1 that the water level detected by the water level sensor 28 is equal to or higher than the middle water level M will be described with reference to FIG.

  In step ST21, the control device 90 determines whether or not the water level detected by the water level sensor 28 is equal to or higher than the high water level H. If this determination is YES, the process moves to step ST22. If the determination is NO, the process returns to step ST1 in FIG.

  In step ST22, the control device 90 outputs an operation stop command to the makeup water pump 27, and stops the supply of makeup water. Then, the process proceeds to step ST23.

  In step ST23, the control device 90 determines whether or not the state in which the water level detected by the water level sensor 28 is equal to or higher than the high water level H has continued for a predetermined time (for example, 30 seconds). When this determination is YES (when the high water level state continues), the process proceeds to step ST24. If the determination is NO, the process returns to step ST1.

  In step ST24, the control device 90 closes the suction steam valve 50 and stops the supply of the low-pressure steam to the main steam supply line L1. Then, the process proceeds to step ST25.

In step ST25, the control device 90 opens the constant rate blow valve 25 to lower the water level of the water header 212. Then, the process proceeds to step ST26.
In step ST26, the control device 90 determines whether the water level detected by the water level sensor 28 is lower than the high water level H. If this determination is YES (if the water level has dropped), the process proceeds to step ST27. When the determination is NO (when the water level has not yet dropped), the process proceeds to step ST32.
In step ST27, control device 90 determines whether or not the detected pressure of first vapor pressure sensor 70 is less than first set pressure P1. If this determination is YES, the process proceeds to step ST28. If the determination is NO, the process moves to step ST29.
In step ST28, control device 90 closes constant rate blow valve 25, and the process proceeds to step ST30.

  In step ST29, the control device 90 opens the constant-rate blow valve 25 and lowers the water level of the water header 212, thereby lowering the pressure inside the evaporator 211. Then, the process returns to step ST27.

  In step ST30, control device 90 performs warm-up control (see FIG. 4, described later), and the process proceeds to step ST31.

  In step ST31, the control device 90 opens the suction steam valve 50 and restarts the supply of the low-pressure steam to the main steam supply line L1. Then, the process returns to step ST1.

  On the other hand, if the determination in step ST26 is NO, in step ST32, control device 90 determines whether or not the state in which the water level detected by water level sensor 28 is equal to or higher than the extremely high water level has continued for a predetermined time (for example, 60 seconds). Is determined. If this determination is YES, the process proceeds to step ST33. If the determination is NO, the process returns to step ST26.

  In step ST33, the control device 90 issues a warning regarding the ultra-high water level state, and completes the process.

Next, the flow of warm-up control by the control device 90 will be described with reference to FIG.
The warm-up control means that the pressure inside the evaporator 211 is kept within a predetermined range without stopping the operation (that is, without stopping the generation of steam) in the second steam generator 20, and the low-pressure steam Refers to control for maintaining a state in which the supply of water is possible.

  In the present embodiment, when the constant-rate blow valve 25 is closed in step ST7 and when the constant-rate blow valve 25 is closed in step ST28, the control device 90 performs warm-up control.

  In this case, in step ST41, the control device 90 determines whether or not the detected pressure of the first vapor pressure sensor 70 is lower than the first set pressure P1. If this determination is YES, the process proceeds to step ST42. If the determination is NO, the process is completed.

  In step ST42, the control device 90 adjusts the opening of the hot water three-way valve 22 so that the pressure detected by the first steam pressure sensor 70 becomes a predetermined target pressure. Adjust the flow rate. The opening degree of the hot water three-way valve 22 is adjusted by feedback control using a PI or PID algorithm. Then, the process proceeds to step ST43.

In step ST43, the control device 90 determines whether or not the water level detected by the water level sensor 28 is equal to or higher than the middle water level M. If this determination is YES, the process proceeds to step ST44. If the determination is NO, the process returns to step ST43.
In step ST44, control device 90 determines whether or not the detected temperature of boiler water temperature sensor 24 is equal to or higher than set temperature T1 (for example, 100 ° C.). If this determination is YES, the process proceeds to step ST45. If the determination is NO, the process returns to step ST43.
In step ST45, control device 90 determines whether or not the detected pressure of first vapor pressure sensor 70 is equal to or greater than zero. If this determination is YES, the warm-up control is completed, and the process proceeds to step ST10 or ST31. If the determination is NO, the process returns to step ST43.

FIG. 5 shows a modified example of the processing of the control device 90 when it is determined in step ST1 that the water level detected by the water level sensor 28 is equal to or higher than the middle water level M described in FIG.
This modification differs from the processing in FIG. 3 in that a step of determining the pressure of the steam on the secondary side of the ejector 30 is provided before step ST21 in FIG. The other processing is the same as the processing in FIG. 3, so the same reference numerals are used and the description is omitted.

  In this case, in step ST20, control device 90 determines whether or not the detected pressure of second vapor pressure sensor 80 exceeds a second set pressure P2 set in advance. If this determination is YES, the process proceeds to step ST21. If the determination is NO, the process returns to step ST1.

According to the steam supply system 1 of the present embodiment described above, the following effects can be obtained.
The steam supply system 1 includes a first steam generator 10 for generating high-pressure steam, a second steam generator 20 for generating low-pressure steam, a main steam supply line L1 for supplying high-pressure steam, and a main steam supply line for supplying low-pressure steam. An ejector provided at a connection portion with the sub-steam supply line L2 for supplying to L1 and configured to suction low-pressure steam using high-pressure steam as a driving fluid, and a suction steam valve provided on the sub-steam supply line L2. . The second steam generator 20 includes an evaporator unit 21 having an evaporator 211 and a water header 212, a water level sensor 28 for detecting the water level of the water header 212, and a constant rate blow line L8 for discharging stored water from the water header 212. And a constant-rate blow valve 25 provided in the constant-rate blow line L8, and a control device 90. Then, the control device 90 controls the drive steam valve 40 to the open state and drives the ejector 30, and (i) closes the suction steam valve 50 when the water level detected by the water level sensor 28 is lower than the low water level L; ii) When the water level detected by the water level sensor 28 is equal to or higher than the middle water level M, the suction steam valve 50 is opened. By closing the suction steam valve 50 when the water level of the water header 212 is lowered, the generated low-pressure steam is not sucked by the ejector 30, and the water level is further lowered due to the consumption of the boiler water. Is prevented. Further, since the generation of steam is not stopped, the pressure of the steam inside the evaporator 211 is maintained. Therefore, by opening the suction steam valve 50, the supply of the low-pressure steam can be restarted quickly, so that a stable steam supply can be realized.

  The controller 90 closes the constant rate blow valve 25 when (ii) the detected water level of the water level sensor 28 is equal to or higher than the middle water level M and the detected pressure of the first vapor pressure sensor 70 is lower than the first set pressure P1; When the detected water level of the sensor 28 is equal to or higher than the middle water level M, the detected temperature of the boiler water temperature sensor 24 is equal to or higher than the set temperature T1, and the detection pressure of the first steam pressure sensor 70 is equal to or higher than zero, the suction steam valve 50 is opened. . Thereby, the suction steam valve 50 can be opened in a state where the water level of the water header 212 is recovered, the boiler water is heated to a predetermined temperature, and the pressure of the evaporator 211 is not a negative pressure. Steam supply can be resumed.

  When the pressure of the steam on the secondary side of the ejector 30 increases, the low-pressure steam generated by the second steam generator 20 is not sucked, and the boiler water is not consumed. When the consumption of the boiler water in the second steam generator 20 decreases, the level of the boiler water stored in the second steam generator 20 rises. When the water level of the boiler water rises, the dryness of the generated low-pressure steam decreases, leading to a decrease in steam quality. Therefore, the control device 90 controls the drive steam valve 40 to the open state and drives the ejector 30. (iii) When the detected water level of the water level sensor 28 is equal to or higher than the high water level H, the control device 90 closes the suction steam valve 50 and sets a constant rate. (Iv) When the water level detected by the water level sensor 28 is lower than the high water level H, the blow rate valve 25 is closed and the suction steam valve 50 is opened. As a result, the water level of the water header 212 can be controlled to an appropriate range, and when the water level of the water header 212 rises, the suction steam valve 50 is closed to dry the low-pressure steam supplied to the main steam supply line L1. Can be prevented from decreasing.

  The control device 90 controls the drive steam valve 40 to be in the open state and drives the ejector 30, while the detected pressure of the second steam pressure sensor 80 exceeds the second set pressure P2 set in advance and the water level sensor 28 When the detected water level becomes higher than the high water level H, the constant rate blow valve 25 is opened. Thus, when the low-pressure steam is not sufficiently sucked in the ejector 30 due to the increase in the pressure on the secondary side of the ejector 30 and the water level of the water header 212 rises, the water level is forcibly reduced. be able to.

  Next, a steam supply system 1A according to a second embodiment of the present invention will be described with reference to FIG. The steam supply system 1A of the second embodiment differs from the first embodiment in the configuration of the second steam generator 20A. In the description of the second embodiment, the same components are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

  In the second embodiment, the second steam generator 20A is configured by a flash steam generator. The flash steam generator collects the steam drain (steam condensed water) discharged from the high-pressure steam utilization equipment in a pressure vessel, re-evaporates the collected steam drain inside the pressure vessel, and separates it into low-pressure steam and hot water. I do.

  As shown in FIG. 6, the second steam generator 20A includes a flash tank 21A constituted by a pressure vessel, a water level sensor 28A for detecting the level of hot water inside the flash tank 21A, and a steam drain to the flash tank 21A. A drain recovery line L5A for recovery, a drainage line L8A for discharging hot water stored in the flash tank 21A, and a drainage valve 25A provided in the drainage line L8A are provided.

  The flash tank 21A re-evaporates the collected steam drain to separate it into low-pressure steam and hot water. That is, the flash tank 21A functions as an evaporation unit having a steam generation unit and a water storage unit. The base end of the sub-steam supply line L2 is connected to the upper part of the flash tank 21A.

  The water level sensor 28A detects the level of warm water stored inside the flash tank 21A. The water level sensor 28A includes a main body and a plurality of electrode rods disposed inside the main body, and detects at least the low water level L, the middle water level M, and the high water level H, as in the first embodiment. I do.

  The drain recovery line L5A connects a steam trap provided in a high-pressure steam utilization facility (not shown) to the flash tank 21A, and supplies steam drain discharged from the high-pressure steam utilization facility to the flash tank 21A.

  The drain line L8A has a base end connected to the bottom of the flash tank 21A, and discharges hot water stored in the flash tank 21A. The drain valve 25A is provided in the drain line L8A, and adjusts the flow rate of warm water discharged from the drain line L8A. Since the hot water separated in the flash tank 21A is substantially pure water, it can be used as makeup water (boiler feed water) for the first steam generator 10.

  In the steam supply system 1A of the second embodiment, in the flash tank 21A, low-pressure steam separated from the steam drain is supplied from the sub-steam supply line L2 to the main steam supply line L1. Then, the same control as in the first embodiment is performed based on the level of the hot water stored in the flash tank 21A.

  According to the steam supply system 1A of the second embodiment, the same effects as those of the first embodiment can be obtained.

Although the preferred embodiments of the steam supply system of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately changed.
For example, in a modified example of the first embodiment, the pressure detected by the second steam pressure sensor 80 exceeds the preset second set pressure P2 while the ejector 30 is driven by controlling the drive steam valve 40 to the open state. When the water level detected by the water level sensor 28 is higher than the high water level H, the constant-rate blow valve 25 is opened and the suction steam valve 50 is closed, but the invention is not limited to this. That is, when the detected pressure of the second vapor pressure sensor 80 exceeds the second set pressure P2 set in advance and the detected water level of the water level sensor 28 becomes higher than or equal to the high water level H while driving the ejector 30. Alternatively, the constant-rate blow valve 25 may be opened while the suction steam valve 50 is opened.

1,1A Steam supply system 10 First steam generator 20, 20A Second steam generator 21 Steam unit 21A Flash tank (steam unit)
22 Hot water three-way valve (flow control means)
23 spray water pump 24 temperature sensor (temperature detecting means)
25 Constant blow valve (drain valve)
25A drain valve 26 Concentration blow valve (drain valve)
28, 28A water level sensor (water level detection means)
Reference Signs List 30 ejector 40 drive steam valve 50 suction steam valve 60 steam pressure regulating valve 70 first steam pressure sensor (first pressure detecting means)
80 second vapor pressure sensor (second pressure detecting means)
90 Control device (control means)
211 Evaporator (steam generator)
212 water header (water reservoir)
215 Tube 216 Spray nozzle L1 Main steam supply line L2 Sub-steam supply line L3 Heat source fluid supply line L4 Heat source fluid discharge line L5 Water spray line L5A Drain recovery line L6 Make-up water line L8 Constant blow line (drain line)
L8A drain line L9 Concentration blow line (drain line)

Claims (8)

A first steam generator for generating a first steam;
A second steam generator for generating a second steam having a lower pressure than the first steam;
A main steam supply line for supplying the first steam generated by the first steam generator to a load device;
A sub-steam supply line that supplies the second steam generated by the second steam generator to the main steam supply line,
An ejector provided at a connection portion between the main steam supply line and the sub-steam supply line, for sucking a second steam using the first steam as a driving fluid;
A drive steam valve provided on the main steam supply line on the primary side of the ejector,
A suction steam valve provided in the sub-steam supply line,
The second steam generator,
A vapor generation unit connected to the sub-steam supply line, and an evaporation unit having a water storage unit,
Water level detection means for detecting the water level of the water storage section,
A drain line for discharging stored water from the water storage unit,
A drain valve provided in the drain line,
The drive steam valve, the suction steam valve, and control means for controlling the drain valve,
The water storage unit has a set water level including at least a low water level, a medium water level, and a high water level,
The control means controls the drive steam valve to an open state to drive the ejector, and (i) closes the suction steam valve when a water level detected by the water level detection means is lower than a low water level; (ii) A) a steam supply system for opening the suction steam valve when the water level detected by the water level detection means is equal to or higher than the middle water level. First pressure detecting means for detecting the pressure of the second steam generated by the steam generating unit;
Temperature detection means for detecting the temperature of the stored water,
(Ii) closing the drain valve when the detected water level of the water level detecting means is equal to or higher than the middle water level and the detected pressure of the first pressure detecting means is lower than a first set pressure; The suction steam valve is opened when the detected water level of the means is equal to or higher than the middle water level, the detected temperature of the temperature detecting means is equal to or higher than a set temperature, and the detected pressure of the first pressure detecting means is equal to or higher than zero. The steam supply system as described.   The control means controls the drive steam valve to be open to drive the ejector, and (iii) opens the drain valve when the water level detected by the water level detection means is equal to or higher than a high water level; (iv) The steam supply system according to claim 1, wherein the drain valve is closed when a water level detected by the water level detection unit is lower than a high water level.   The control means controls the drive steam valve to an open state to drive the ejector. (Iii) When the water level detected by the water level detection means is equal to or higher than a high water level, the control means closes the suction steam valve and discharges the water. 4. The steam supply system according to claim 3, wherein the valve is opened; and (iv) when the water level detected by the water level detection means is lower than the high water level, the drain valve is closed and the suction steam valve is opened. First pressure detecting means for detecting the pressure of the second steam generated by the steam generating unit;
Temperature detection means for detecting the temperature of the stored water,
(Iv) closing the drain valve when the detected water level of the water level detecting means is lower than the high water level and the detected pressure of the first pressure detecting means is lower than a first set pressure; The suction steam valve is opened when the detected water level of the means is equal to or higher than the middle water level, the detected temperature of the temperature detecting means is equal to or higher than a set temperature, and the detected pressure of the first pressure detecting means is equal to or higher than zero. The steam supply system as described. A second pressure detecting means for detecting a discharge-side steam pressure of the ejector;
The control means controls the drive steam valve to be in an open state to drive the ejector. (Iii) The detection pressure of the second pressure detection means exceeds a second set pressure and the detection of the water level detection means The steam supply system according to claim 3, wherein the drain valve is opened when a water level is equal to or higher than a high water level. The second steam generator,
An evaporator having a tube through which a heat source fluid flows, and a spray nozzle for spraying boiler water onto the tube; and an evaporator having a water header disposed below the evaporator and storing the boiler water. Unit and
A water spray line for supplying boiler water in the water header to the spray nozzle,
A water spray pump provided in the water spray line,
A drain line for discharging boiler water from the water header,
A drain valve provided in the drain line,
A makeup water line for supplying makeup water to the water header,
The steam supply system according to any one of claims 1 to 6, further comprising a flow rate adjusting unit configured to adjust a flow rate of the heat source fluid flowing through the tube. The second steam generator,
An evaporation unit comprising a flash tank for re-evaporating the collected steam drain to separate it into second steam and hot water;
A drain collection line for collecting steam drain in the flash tank,
A drain line for discharging hot water stored in the flash tank,
The steam supply system according to claim 1, further comprising: a drain valve provided in the drain line.

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