JP5454435B2 - Drain collection system - Google Patents

Description

  The present invention relates to a drain recovery system that recovers drain discharged from a load device that uses steam from a boiler as a heat source and supplies water to the boiler, and more specifically, opens the drain discharged from the load device to the atmosphere. The present invention relates to a closed-type drain recovery system that recovers water without supplying water to a boiler.

  Conventionally, in order to save boiler fuel costs and water, a drain recovery system has been proposed in which drain discharged from load equipment is recovered in a tank and reused. In this drain recovery system, the drain discharged from the load device is recovered in an open tank that is open to the atmosphere, and the boiler is supplied with drain of less than 100 ° C, and the drain discharged from the load device is discharged to the atmosphere. There is known a closed system in which a high-temperature and high-pressure drain of 100 ° C. or higher collected in a closed tank that is not opened to water is supplied to a boiler (see, for example, Patent Document 1). .

JP 2006-105442 A

  In the above-mentioned closed system, the drain pump that feeds the drain collected in the sealed tank to the boiler is required to have high temperature resistance that can be used at high temperatures and to take measures against cavitation in order to feed hot drain. For this reason, it becomes expensive, the initial cost when the closed drain recovery system is introduced is high, and the drain pump requires periodic maintenance, and the running cost is high.

  Further, the temperature of the drain is limited to the maximum use temperature of the drain pump, and there is a problem that high-temperature drain exceeding the maximum use temperature of the drain pump cannot be collected and supplied to the boiler.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a closed drain recovery system that eliminates the need for an expensive drain pump for supplying drain to a boiler.

  In order to achieve the above object, the drain recovery system of the present invention is configured as follows.

(1) The drain recovery system of the present invention is a closed-type drain recovery system that recovers drain discharged from a load device that uses steam from a boiler and supplies the boiler with water, and supplies the drain to the boiler. A closed water supply tank , a water supply pipe for connecting the water supply tank and the boiler, a water supply pipe for supplying water from the water supply tank to the boiler, the water supply tank and the boiler, and steam from the boiler. A steam introduction pipe for introducing water into the water supply tank, a drain supply pipe connected to the water supply tank directly or via a part of the water supply pipe for supplying drain to the water supply tank, and a discharge connected to the water supply tank A pressure release valve provided in the discharge pipe to reduce the pressure in the water supply tank, a steam introduction control valve provided in the steam introduction pipe, and the pressure And a control means for controlling the opening and closing of the open valve and the steam introduction control valve, and the water supply tank, installed as the water level in the water supply tank is higher than the water level in the boiler, the control means the when supplying the drain to the water supply tank, said reduced pressure without controlling the opening and closing of the pressure relief valve to the negative pressure of the water supply tank and lower than the pressure of the drain of the drain supply pipe, the drain supply When the drain is drawn from the pipe into the water supply tank and the drain is supplied from the water supply tank to the boiler, the steam introduction control valve is controlled to open and close so that the pressure in the water supply tank is equal to the pressure in the boiler. The steam of the boiler is introduced into the water supply tank so that the water is supplied from the water supply tank to the boiler according to the difference in level between the water level in the water supply tank and the water level in the boiler.

  According to the drain recovery system of the present invention, in a closed water tank installed so that the water level in the tank is higher than the water level in the boiler, the inside of the water tank is decompressed and the drain is drawn from the drain supply pipe. When supplying the drained water to the boiler, the pressure in the water supply tank is made equal to the pressure in the boiler, and the difference between the water level in the water supply tank and the water level in the boiler, that is, the water head difference (head difference). Since water is supplied, an expensive drain pump for supplying high-temperature drain recovered by the closed system to the boiler is not necessary. As a result, the initial cost and running cost when the closed type drain recovery system is introduced can be reduced, and the temperature of the drain water supplied to the boiler is not limited to the maximum operating temperature of the drain pump.

  According to this embodiment, the control means supplies drain to the water supply tank by controlling the opening and closing of the pressure release valve provided in the discharge pipe of the water supply tank and the steam introduction control valve provided in the steam introduction pipe. Sometimes, the opening and closing of the pressure release valve is controlled to depressurize the inside of the water supply tank and the drain is drawn into the water supply tank, and when water is supplied from the water supply tank to the boiler, the steam introduction control valve is opened and the water supply tank is opened. Steam can be introduced to make the pressure in the water supply tank equal to the pressure in the boiler, and water can be supplied from the water supply tank to the boiler by the head difference.

  (3) In another embodiment of the drain recovery system of the present invention, the drain recovery system includes a detection unit that detects a differential pressure between the pressure in the water supply tank and the drain pressure of the drain supply pipe, and the control unit includes the detection Based on the detection output of the means, the opening and closing of the pressure release valve is controlled.

  According to this embodiment, on the basis of the differential pressure between the pressure in the water supply tank and the drain pressure in the drain supply pipe, the opening and closing of the pressure release valve for reducing the pressure in the water supply tank is controlled. The amount of drain supplied from the drain supply pipe to the water supply tank can be adjusted.

  (4) In still another embodiment of the drain recovery system of the present invention, the drain recovery system further includes a rectifier that rectifies steam introduced from the steam introduction pipe into the water supply tank.

  According to this embodiment, since the steam introduced into the water supply tank is rectified by the rectification means to be an even flow, the steam introduced into the water supply tank disturbs the drain in the water supply tank and the lower drain and Heat exchange is suppressed, the drain interface is saturated, the pressure in the water supply tank is quickly made equal to the pressure in the boiler, and water supply to the boiler can be started.

  (5) In still another embodiment of the drain recovery system of the present invention, the system includes a sealed recovery tank that recovers drain discharged from the load device, and an open makeup water tank that is supplied with makeup water. The drain supply pipe connects the water supply tank and the recovery tank directly or through a part of the water supply pipe, and the discharge pipe connects the water supply tank and the makeup water tank.

  According to this embodiment, the drain discharged from the load device is temporarily collected in a closed type recovery tank, and is necessary from this recovery tank to the water supply tank via a drain supply pipe or a part of the drain supply pipe and the water supply pipe. Since an amount of drainage can be supplied, the water supply tank installed so that the water level is higher than the water level in the boiler can be made smaller than the recovery tank.

  (6) In another embodiment of the drain recovery system of the present invention, a plurality of the boilers are provided, and at least two of the water supply tanks are provided. When water is supplied from a certain water supply tank to the boiler, to another water supply tank When drain is supplied from the drain supply pipe and drain is supplied from the drain supply pipe to the certain water supply tank, water is supplied to the boiler from another water supply tank.

  According to this embodiment, when water is supplied from one tank of the two water supply tanks to a plurality of boilers, the drain can be supplied to the other tank, and the water supply to the boiler and the supply of the drain can be performed. Can be switched alternately, so there is no need to install a water tank for each boiler, and it is sufficient to install at least two water tanks.

  According to the drain recovery system of the present invention, the closed water tank is depressurized in the water tank to draw in the drain, and the drain drawn in the water tank is supplied with the pressure in the water tank. Equal to the pressure, water is supplied to the boiler by the difference in level between the water level in the water supply tank and the water level in the boiler, that is, the water head difference (head difference), so the high-temperature drain recovered by the closed system is supplied to the boiler. This eliminates the need for an expensive drain pump, reduces initial costs and running costs when a closed-type drain recovery system is installed, and limits the temperature of the drain water supplied to the boiler to the maximum operating temperature of the drain pump. There is no such thing as.

FIG. 1 is a diagram showing a configuration of a drain recovery system according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the drain recovery system of FIG. FIG. 3 is a diagram for explaining the function and effect of the dispersion plate in the water supply tank. FIG. 4 is a diagram showing rectifying means according to another embodiment of the present invention. FIG. 5 is a view showing a rectifying means according to still another embodiment of the present invention. FIG. 6 is a diagram showing a rectifying unit according to another embodiment of the present invention. FIG. 7 is a diagram showing a configuration of a drain recovery system according to another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing an example of the configuration of a closed drain recovery system according to an embodiment of the present invention.

  In the drain recovery system of this embodiment, the steam generated in the boiler 1 is supplied to a steam exchanger 3 that uses steam via a separator 2 and a steam pipe 3 and a branch steam pipe 30 branched from the steam pipe 3. Supplied to a plurality of load devices 4.

  Since the load device 4 uses the heat of the steam, the heat is deprived of heat and condensed to be drained and discharged from the load device 4.

  The drain discharged from the load device 4 is collected through a steam trap 5 in a collection tank 6 that is a sealed pressurized tank.

  In this embodiment, in order to supply the drain collected in the collection tank 6 to the boiler 1 without using a drain pump, a sealed water tank 7 is installed at a position above the boiler 1. ing.

  The water supply tank 7 is installed so that the water level in the water supply tank 7 is higher than the water level in the boiler 1, and the level difference between the water level in the water supply tank 7 and the water level in the boiler 1, as will be described later. To supply water to the boiler 1.

  The bottom of the water supply tank 7 and the boiler 1 are connected by a water supply pipe 8, and the water supply pipe 8 is provided with a first check valve 9 that prevents a back flow from the boiler 1.

  A drain supply pipe 10 connected to the bottom of the recovery tank 6 is connected between the water supply tank 7 of the water supply pipe 8 and the first check valve 9. That is, the drain supply pipe 10 is connected to the water supply tank 7 through a part of the water supply pipe 8.

  As another embodiment of the present invention, the drain supply pipe 10 may be directly connected to the water supply tank 7 without using the water supply pipe 8.

  The drain of the recovery tank 6 is supplied to the water supply tank 7 through the drain supply pipe 10 as described later. In the middle of the drain supply pipe 10, a first motor valve 11 and a first pressure sensor 12 for detecting the pressure of the drain are provided.

  One end of a preliminary water supply pipe 14 is connected to the water supply pipe 8 between the boiler 1 and the first check valve 9, and the other end of the preliminary water supply pipe 14 is connected to an open-type supply water tank 13. ing. The spare water supply pipe 14 is provided with a makeup water pump 15 and a check valve 50 from the upstream side, and when the water supply to the boiler 1 cannot be provided only by the water supply from the water supply tank 7, Water is supplied directly from the make-up water tank 13 to the boiler 1 through the auxiliary water supply pipe 14.

  A steam introduction pipe 16 branched from the steam pipe 3 is connected to the upper part of the water supply tank 7, and a second motor valve 17 as a steam introduction control valve is installed in the middle of the steam introduction pipe 16. Yes.

  One end of a discharge pipe 18 is connected to the upper part of the water supply tank 7, and the other end of the discharge pipe 18 is connected to the makeup water tank 13. A third motor valve 19 is provided in the middle of the discharge pipe 18 as a pressure release valve for reducing the pressure in the water supply tank 7. The water supply tank 7 is provided with a second pressure sensor 20 that detects the pressure in the water supply tank 7 and a water level sensor 31 that detects the water level of the drain in the water supply tank 7.

  The recovery tank 6 and the supply water tank 13 for supplying supply water to the recovery tank 6 are connected by a supply water pipe 21. The supply water pipe 21 and the second check valve are connected to the supply water pipe 21 from the upstream side. 23 is provided. Further, an exhaust pipe 24 for exhausting the flash vapor flashed and evaporated in the recovery tank 6 is connected to the upper portion of the recovery tank 6, and the exhaust pipe 24 is connected to the makeup water tank 13 via a primary pressure adjustment valve 25. Connected to the top of the. A replenishment pipe 26 for replenishing new water is connected to the lower portion of the replenishment water tank 13.

  The first pressure sensor 12 of the drain supply pipe 10 and the second pressure sensor 20 of the water supply tank 7 constitute detection means, and each detection output is given to a control unit 27 as control means. The control unit 27 is further provided with a detection output of a water level sensor 31 provided in the water supply tank 7 and a water supply signal corresponding to the presence or absence of a water supply request from the boiler 1. The control unit 27 controls the opening and closing of the first to third motor valves 11, 17 and 19 based on these detection outputs and the water supply signal.

  Specifically, when there is no water supply request from the boiler 1, the control unit 27 opens (ON) the first motor valve 11 of the drain supply pipe 10 when the water supply tank 7 is not full, and the pressure of the discharge pipe 18. The third motor valve 19 as an opening valve is opened (ON). Accordingly, the inside of the water supply tank 7 is reduced to a pressure lower than the drain pressure of the drain supply pipe 10 without making negative pressure, and the drain from the recovery tank 6 is drawn into the water supply tank 7 by its own pressure. At this time, the control unit 27 determines that the drain is contained in the water supply tank 7 based on the differential pressure between the pressure in the water supply tank 7 detected by the first and second pressure sensors 12 and 20 and the pressure in the drain supply pipe 10. The opening and closing of the third motor valve 19 is controlled so that an appropriate amount is drawn. Moreover, since the pressure in the boiler 1 is higher than the pressure of the drain of the drain supply pipe 10, the drain does not flow into the boiler 1.

  When there is a water supply request from the boiler 1, the control unit 27 closes the first and third motor valves 11 and 19 (OFF), and opens the second motor valve 17 as a steam introduction control valve of the steam introduction pipe 16 (ON). ) The steam from the boiler 1 is introduced into the feed water tank 7 so that the pressure in the feed water tank 7 becomes equal to the pressure in the boiler 1, and thereby the water level is higher than the water level in the boiler 1. Drain is supplied from the tank 7 to the boiler 1.

  In this embodiment, although the drain pressure of the drain supply pipe 10 is detected by the first pressure sensor 12, the drain pressure is not limited to the drain supply pipe 10, for example, piping from the steam trap 5 to the recovery tank 6, Detection may be performed by providing a pressure sensor in the recovery tank 6 or the exhaust pipe 24 between the recovery tank 6 and the primary pressure regulating valve 25.

  FIG. 2 is a flowchart for explaining the above operation.

  First, in step S1, it is determined whether or not the water supply signal is ON, that is, whether or not there is a water supply request from the boiler 1. If there is no water supply request from the boiler 1, NO is determined and the process proceeds to step S2. When the second motor valve 17 as the steam introduction control valve is not turned off (closed) in step S2, the second motor valve 17 is turned off.

  Next, after the processing in step S2, the process proceeds to step S3. In this step S3, it is determined whether or not the water level detected by the water level sensor 31 provided in the water supply tank 7 is a predetermined water level, that is, whether or not the water supply tank 7 is full. When it is determined in step S3 that the water is full and YES, the process returns to step S1 and waits until there is a water supply request. On the other hand, when it is determined in step S3 that the water level of the water supply tank 7 is not full and NO, the process proceeds to step S4. In this step S4, the first motor valve 11 is turned on (opened), and the drain pressure of the drain supply pipe 10 detected by the first and second pressure sensors 12, 20 and the pressure in the water supply tank 7 are compared. The third motor valve 19 serving as a pressure release valve that depressurizes the inside of the water supply tank 7 according to the differential pressure is ON / OFF controlled to depressurize the inside of the water supply tank 7 and draw an appropriate amount of drain into the water supply tank 7. . After step S4, the process returns to step S1.

  On the other hand, when the water supply signal is ON in step S1, that is, when there is a water supply request from the boiler 1 and it is determined YES, the process proceeds to step S5. In step S5, if the first motor valve 11 and the third motor valve 19 are not turned off, both of them are turned off, and the process proceeds to the next step S6. In step S6, the second motor valve 17 as the steam introduction control valve is turned on. After step S6, the process returns to step S1. As a result, the steam of the boiler 1 is introduced into the feed water tank 7, and the pressure in the feed water tank 7 and the pressure in the boiler 1 become equal, so that the drain of the feed water tank 7 becomes the water level in the feed water tank 7 and the boiler 1. Water is supplied to the boiler 1 by the difference in height from the water level inside, that is, the water head difference.

  As described above, in the water supply tank 7 installed above the boiler 1, the inside of the water supply tank 7 is decompressed without making the negative pressure lower than the atmospheric pressure, and the drain is supplied from the drain supply pipe 10. The drain drawn into the water supply tank 7 is supplied to the boiler 1 by making the pressure in the water supply tank 7 equal to the pressure in the boiler 1 and by the difference in level between the water level in the water supply tank 7 and the water level in the boiler 1. Therefore, an expensive drain pump for supplying the high-temperature drain recovered by the closed system to the boiler 1 becomes unnecessary.

  As a result, the initial cost and running cost when the closed type drain recovery system is introduced can be reduced, and the temperature of the drain that is recovered and supplied to the boiler 1 is limited to the maximum operating temperature of the drain pump. Nor.

  Further, in this embodiment, as shown in FIG. 3 (b), in the water supply tank 7, a dispersion plate that rectifies steam introduced from above through the steam introduction pipe 16 as indicated by an arrow F1. 28 is installed. The dispersion plate 28 as a rectifying means is made of a disk and is suspended horizontally so as to face a circular steam inlet 29 formed at the center of the upper wall of the water supply tank 7. Note that the dispersion plate 28 is not limited to a circular plate, and may be, for example, a substantially hemispherical dispersion plate 28a whose bottom surface is spherical as shown in FIG.

  As shown in FIG. 3A, when the dispersion plate 28 is not installed, the steam introduced from the steam inlet 29 into the water supply tank 7 cannot spread sufficiently in the water supply tank 7 and is biased. As shown by the arrow F2, the vicinity of the center becomes a locally fast flow. Thus, when locally fast steam enters the water surface 45a of the drain 45 in the water supply tank 7, the water surface 45a is disturbed and heat exchange between the lower drain 45 and the steam occurs. A so-called time lag occurs in which it takes time until the internal pressure is stabilized and water supply to the boiler 1 is started. In addition, a large amount of steam is introduced into the feed water tank 7 due to the occurrence of a time lag, and the water level in the boiler 1 is lowered or the pressure is lowered.

  On the other hand, in this embodiment, since the dispersion plate 28 is installed in the water supply tank 7, the steam introduced into the water supply tank 7 from the steam inlet 29 is reduced in momentum by the dispersion plate 28 and dispersed. It is possible to prevent the water surface 45a of the drain 45 from being disturbed by generating a flow that circulates around the plate 28 and rectifying the flow into an even flow that spreads in the water supply tank 7. As a result, heat exchange between the lower drain 45 and the steam is suppressed, and a thin film 45b of a saturated liquid having a higher temperature than the lower drain 45 is formed at the interface between the steam and the drain 45 as shown in FIG. Is quickly formed, and the pressure in the water supply tank 7 can be quickly made equal to the pressure in the boiler 1, so that the start of water supply to the boiler 1 can be accelerated. For this reason, the amount of steam introduced from the boiler 1 to the water supply tank 7 can be reduced, and the water level in the boiler 1 can be suppressed from decreasing or the pressure can be suppressed from decreasing.

  As the dispersion plate 28, a porous plate may be used. Further, the porous plate is provided in a plurality of stages, for example, as shown in FIG. The steam introduced from the above may be rectified by passing the perforated plates 46, 47 through the arrows F2, F3. As the rectifying means, for example, as shown in FIG. 6, steam from the boiler 1 is introduced from the side wall of the water supply tank 7 into the water supply tank 7 as indicated by an arrow F <b> 1. The steam may be ejected toward the wall inner surface as indicated by an arrow F2, and the steam colliding with the inner surface 7a may be directed toward the water surface of the lower drain 45 in the direction indicated by the arrow F3.

(Embodiment 2)
FIG. 7 is a diagram showing an example of the configuration of a closed-type drain recovery system according to another embodiment of the present invention, and portions corresponding to those in FIG. 1 are given the same reference numerals.

  The drain collection system according to this embodiment is provided with a plurality of boilers, for example, three boilers 1a to 1c, and adjusts the number of operating boilers according to the load amount to increase boiler efficiency.

  The steam from the three boilers 1a to 1c is supplied to the load device 4 through the steam pipe 3 and the branch steam pipe 30 in the same manner as in the above-described embodiment, and the drain from the load equipment 4 passes through the steam trap 5. To the closed recovery tank 6.

  In this embodiment, two sealed water supply tanks 7a and 7b for supplying drain to the boilers 1a to 1c are installed above the three boilers 1a to 1c. Each water supply tank 7a, 7b is installed so that the water level in each tank 7a, 7b becomes higher than the water level in each boiler 1a-1c.

  The bottom of each water supply tank 7a, 7b and each boiler 1a-1c are connected via the branch water supply pipes 8a, 8b and the common water supply pipe 32, and each branch water supply pipe 8a, 8b has a third check Valves 33 a and 33 b are provided, respectively, and a fourth check valve 34 and a fifth motor valve 35 are provided in the common water supply pipe 32. The common water supply pipe 32 between the fifth motor valve 35 and the boiler 1c is connected to a preliminary water supply pipe 38 connected to the open-type supply water tank 13. The auxiliary water supply pipe 38 is provided with a makeup water pump 15 and a sixth check valve 51 from the upstream side.

  A branch drain supply pipe 10a in which a drain supply pipe 36 connected to the bottom of the recovery tank 6 is branched between the check valves 33a, 33b of the branch water supply pipes 8a, 8b and the water supply tanks 7a, 7b. , 10b are connected to each other. Each branch drain supply pipe 10a, 10b is connected to each water supply tank 7a, 7b via a part of each branch water supply pipe 8a, 8b, respectively. Similarly to the above embodiment, each branch drain supply The pipes 10a and 10b may be directly connected to the water tanks 7a and 7b. In the middle of each branch drain supply pipe 10, first motor valves 11a and 11b are provided, and fifth check valves 37a and 37b are provided, respectively.

  Branch steam introduction pipes 16a and 16b branched from the steam introduction pipe 16 are connected to the upper portions of the water supply tanks 7a and 7b. The branch steam introduction pipes 16a and 16b are connected to a first steam introduction control valve. Two motor valves 17a and 17b are respectively installed. Further, branch discharge pipes 18a and 18b are connected to the upper portions of the water supply tanks 7a and 7b, respectively. The branch discharge pipes 18a and 18b are joined to form a discharge pipe 18 and connected to the makeup water tank 13. Yes. The branch discharge pipes 18a and 18b are respectively provided with third motor valves 19a and 19b as pressure release valves for reducing the pressure in the water supply tanks 7a and 7b.

  The recovery tank 6 and the supply water tank 13 for supplying supply water to the recovery tank 6 are connected by a supply water pipe 21. The supply water pipe 21 and the second check valve are connected to the supply water pipe 21 from the upstream side. 23 is provided. Further, an exhaust pipe 24 for discharging the flash vapor flashed and evaporated in the recovery tank 6 is connected to the upper part of the recovery tank 6, and the exhaust pipe 24 is connected to the makeup water tank 13 via a primary pressure adjustment valve 25. Connected to the top of the. A replenishment pipe 26 for replenishing new water is connected to the lower portion of the replenishment water tank 13.

  Although not shown, each of the first and second pressure sensors for detecting the pressure of the drains of the drain supply pipes 10a and 10b and the pressure in the water supply tanks 7a and 7b, respectively, as in the above-described embodiment, A water level sensor that detects the water level of the water supply tanks 7a and 7b, and a controller that controls the first to third motor valves 11a, 11b, 17a, 17b, 19a, 19b, and the like based on the detection outputs are provided. .

  In this embodiment, when there is a water supply request from any one of the boilers 1a to 1c, the first water supply tank filled with drain, for example, the steam introduction control valve of the steam introduction pipe 16a of the water supply tank 7a. 2 Open the motor valve 17a (ON), introduce steam from the boilers 1 to 1c into the feed water tank 7a so that the pressure in the feed water tank 7a is equal to the highest pressure in the boilers 1a to 1c, Due to the difference in level between the water level in the water supply tank 7a and the water levels in the boilers 1a to 1c, the drain water is supplied from the water supply tank 7a to the boilers 1a to 1c having a water supply request through the branch water supply pipe 8a and the common water supply pipe 32.

  When the water supply tank 7a supplies water to the boilers 1a to 1c that require water supply, the first motor valve 11b of the branch drain supply pipe 10b of the other water supply tank 7b is opened (ON) and the discharge pipe 18b. The third motor valve 19b serving as the pressure release valve is opened and closed according to the pressure difference between the drain pressure in the branch drain supply pipe 10b and the pressure in the water supply tank 7. As a result, the inside of the water supply tank 7b is depressurized and becomes lower than the pressure of the drain of the branch drain supply pipe 10b.

  When the drain in one water supply tank 7a becomes empty, the second motor valve 17b as the steam introduction control valve of the steam introduction pipe 16b of the other water supply tank 7b is opened (ON), and the steam from the boilers 1a to 1c is The water supply tank 7b is introduced so that the pressure in the water supply tank 7b becomes equal to the highest pressure in the boilers 1a to 1c, whereby the water supply tank 7b is connected via the branch water supply pipe 8b and the common water supply pipe 32. Drain is supplied to the boilers 1a to 1c having a water supply request.

  When draining water from the other water supply tank 7b to the boilers 1a to 1c, the first motor valve 11a of the branch drain supply pipe 10a of the one water supply tank 7a is opened (ON) and the pressure of the discharge pipe 18a is released. The third motor valve 19a as a valve is opened and closed. As a result, the inside of the water supply tank 7a is depressurized and becomes lower than the pressure of the drain in the branch drain supply pipe 10a, so that an appropriate amount of drain from the recovery tank 6 is drawn into the water supply tank 7a by its own pressure.

  In this way, when drain is being supplied from one of the two water supply tanks 7a and 7b to the boilers 1a to 1c that require water supply, the other water supply tank 7b (or 7a) is supplied. When the water supply tank 7a (or 7b) is emptied, water is supplied from the other water supply tank 7b (or 7a) to the boilers 1a to 1c and drained to the one water supply tank 7a (or 7b). I try to pull in.

  In the first embodiment described above, one water supply tank 7 is installed for one boiler 1 and drainage is supplied from the water supply tank 7 to the boiler 1 according to the presence or absence of a water supply request from the boiler 1, or The drain is drawn into the water supply tank 7 from the drain supply pipe 10. Therefore, in the above-mentioned Embodiment 1, the water supply tank 7 is required for the number of boilers.

  On the other hand, in this embodiment, for example, two water supply tanks 7a and 7b are installed for three boilers 1a to 1c, and one water supply tank 7a (or 7b) of the two water supply tanks 7a and 7b is provided. When the drain is supplied to the three boilers 1a to 1c, the drain is drawn into the other water supply tank 7b (or 7a) from the drain supply pipe.

  Thereby, even if the number of boilers increases, it is not necessary to provide water supply tanks as many as the number of boilers, and it is sufficient to install at least two water supply tanks.

  In this embodiment, the fifth motor valve 35 is provided in the common water supply pipe 32 between the boiler 1c and the fourth check valve 34. However, as another embodiment of the present invention, the motor valve is a fourth valve. You may provide in the common water supply pipe | tube 32 of the upstream (water supply tank 7a, 7b side) rather than the non-return valve 34, and it is provided in each branch water supply pipe | tube 8a, 8b downstream from the 3rd non-return valve 33a, 33b. You may provide, respectively, or you may provide between the connection part with each branch drain supply pipe | tube 10a, 10b of each branch water supply pipe | tube 8a, 8b, and 3rd check valve 33a, 33b, respectively. In addition, a motor valve is not provided between the connection part of each branch water supply pipe 8a, 8b with each branch drain supply pipe 10a, 10b and each water supply tank 7a, 7b.

 The present invention is useful as a closed type drain recovery system.

1, 1a to 1c Boiler 6 Recovery tank 7, 7a, 7b Water supply tank 8 Water supply pipe 10 Drain supply pipe 12 First pressure sensor 13 Supply water tank 16 Steam introduction pipe 17, 17a, 17b Second motor valve (steam introduction control valve) )
18 Discharge pipe 19, 19a, 19b Third motor valve (pressure release valve)
20 Second pressure sensor 27 Control unit 28, 28a Dispersion plate

Claims (5)

A closed-type drain recovery system that recovers drain discharged from load equipment that uses steam from a boiler and supplies water to the boiler,
A sealed water tank for supplying drain to the boiler ;
A water supply pipe that connects the water supply tank and the boiler, and supplies the boiler with a drain of the water supply tank;
A steam introduction pipe for connecting the water supply tank and the boiler, and introducing steam from the boiler into the water supply tank;
A drain supply pipe connected to the water supply tank directly or via a part of the water supply pipe to supply drain to the water supply tank;
A discharge pipe connected to the water supply tank;
A pressure release valve provided in the discharge pipe to reduce the pressure in the water supply tank;
A steam introduction control valve provided in the steam introduction pipe;
Control means for controlling opening and closing of the pressure release valve and the steam introduction control valve,
Installing the water tank so that the water level in the water tank is higher than the water level in the boiler;
The control means includes
When supplying the drain to the water supply tank, the opening and closing of the pressure release valve is controlled so that the inside of the water supply tank is depressurized without making it negative, and the pressure of the drain supply pipe is made lower than the drain supply pipe. Draw the drain into the water tank from
When supplying drain from the water supply tank to the boiler, the steam introduction control valve is controlled to open and close so that the steam in the water supply tank is equal to the pressure in the boiler so that the pressure in the water supply tank becomes equal to the pressure in the boiler. Introduced into the water supply from the water supply tank to the boiler by the difference in level between the water level in the water supply tank and the water level in the boiler,
A drain collection system characterized by that. Detecting means for detecting a differential pressure between the pressure in the water supply tank and the pressure of the drain of the drain supply pipe;
The control means controls the opening and closing of the pressure release valve based on the detection output of the detection means;
The drain recovery system according to claim 1 . Rectifying means for rectifying steam introduced from the steam introduction pipe into the water supply tank;
The drain recovery system according to claim 1 or 2 . A closed recovery tank for recovering drainage discharged from the load device;
An open-type makeup water tank to which makeup water is supplied,
The drain supply pipe connects the water supply tank and the recovery tank directly or via a part of the water supply pipe,
The discharge pipe connects the water supply tank and the makeup water tank;
The drain recovery system according to any one of claims 1 to 3 . A plurality of the boilers are provided, and at least two water supply tanks are provided. When water is supplied from one water supply tank to the boiler, drain is supplied from the drain supply pipe to another water supply tank, and the water supply tank is supplied to the water supply tank. When supplying drain from the drain supply pipe, water is supplied to the boiler from another water supply tank.
The drain recovery system according to any one of claims 1 to 4 .

Images