JP5625572B2 - Closed drain system - Google Patents

Description

  The present invention relates to a closed drain system having a plurality of steam boilers and switching between drain supply control and fresh water supply control for each steam boiler.

For the purpose of energy saving, a closed drain system that collects drain (condensate) discharged from load equipment in a closed drain tank and supplies the collected high-temperature drain as feed water for a steam boiler is disclosed in Patent Document 1 Known. In this patent document 1, a deoxygenating agent is inject | poured with a chemical injection apparatus in the downstream of a drain tank. In general, the amount of chemical injection by this chemical injection device is increased or decreased according to the increase or decrease of the drain flow rate.
JP 2007-263385 A

  The inventors of this application have a closed drain system such as Patent Document 1 that has a plurality of steam boilers and switches between drain supply control and fresh water supply control for each steam boiler (hereinafter referred to as an object). When the system was developed, the following problems were found.

  That is, in this target system, it is conceivable to provide a flow meter in the common drain supply line that supplies drain from the drain tank to each steam boiler, and to control the amount of chemical injection to the common drain supply line. In this case, the drain supply control and the fresh water supply control are switched for each steam boiler, and in addition to this, the operating load of each steam boiler increases and decreases, so the fluctuation range of the flow rate of the drain flowing through the common drain supply line is large. There is a problem that there is no high-temperature specification flow meter that can cope with this fluctuation range.

  In addition, it is conceivable that a flow meter is provided in each branch drain supply line branched from the common drain supply line to each steam boiler, and the amount of chemical injection is increased or decreased by these flow meters. However, even in this method, there is a problem that there is no high-temperature specification flow meter that can cope with a wide flow rate fluctuation range due to increase / decrease in the operation load of each boiler. Furthermore, since many flow meters are required, there is a problem that the system configuration becomes complicated and the initial cost increases.

  The problem to be solved by the present invention is a closed drain system having a plurality of steam boilers and switching between drain supply control and fresh water supply control for each steam boiler, without complicating the system configuration. It is to perform appropriate drug injection for.

This invention was made in order to solve the said subject, The invention of Claim 1 is as follows.
A plurality of steam boilers each having a can body and supplying steam generated in the can body to a load device,
A sealed drain tank for collecting drain discharged from the load device;
A new water tank for storing fresh water;
Drain supply control for supplying drain in the drain tank to each can through a common drain supply line and a branched drain supply line branched from the common drain supply line, and supplying fresh water in the new water tank to common new water A controller for selectively switching in each steam boiler, a fresh water supply control to be supplied to each can through a line and a branch fresh water supply line branched from the common fresh water supply line;
A first medicine that has a plurality of medicine injection pumps corresponding to the number of the steam boilers and injects into a common drain circulation part that circulates before the drain branches and flows into the branch drain supply line during the drain supply control. With a device
The controller is configured to increase or decrease a chemical injection amount by the first chemical injection device in accordance with an increase or decrease in the number of the steam boilers performing the drain supply control and an increase or decrease in the operation load of each steam boiler. There line the dosing control,
In the first chemical injection control, the chemical corresponding to the steam boiler that performs the new water supply control while increasing or decreasing the chemical injection amount of the corresponding chemical injection pump according to the increase or decrease of the operation load of each steam boiler. It is characterized in that the amount of medicine injected by the first medicine injection device is controlled by stopping the injection pump .

According to invention of Claim 1, according to the increase / decrease in the number of the steam boilers which are performing the said drain supply control, and the increase / decrease in the operation load of each steam boiler, the chemical injection amount by said 1st chemical injection apparatus is changed. Since the amount is increased or decreased, it is possible to appropriately control the amount of the medicine injected into the drain. In addition, since the amount of medicine to be drained is controlled without using a flow meter, the system configuration can be simplified. In addition, since the amount of drug injection is controlled by controlling a plurality of drug injection pumps, the amount of drug injection can be controlled with high accuracy, and a complicated control logic is not required, so that the control configuration can be simplified.

The invention according to claim 2 comprises a second medicine injection device for injecting medicine into each of the branched fresh water supply lines or the fresh water tank at the time of the fresh water supply control in claim 1 , wherein the controller includes the controller The second chemical injection control for increasing / decreasing the chemical injection amount by the second chemical injection device is performed according to the increase / decrease of the fresh water flow rate of each branch fresh water supply line or the common fresh water supply line.

According to invention of Claim 2, in addition to the effect by the invention of Claim 1, there exists an effect that the chemical injection quantity to the fresh water at the time of fresh water supply control can be controlled appropriately.

The invention described in 請 Motomeko 3 includes a can body, respectively, sealed to collect a plurality steam boiler supplied to the load device to generate steam in the can body, the drain discharged from the load device Drain tank, a fresh water tank for storing fresh water, and a drain supply control for supplying the drain in the drain tank to each can through a common drain supply line and a branched drain supply line branched from the common drain supply line And each of the steam boilers for supplying fresh water in the fresh water tank to each can through a common fresh water supply line and a branched fresh water supply line branched from the common fresh water supply line. A controller for selectively switching, and at the time of the drain supply control, a first portion for pouring the drain into a common drain circulation part that flows before branching to the branch drain supply line and flowing. With a dosing device, said dispenses drugs to the fresh water supply said at control each branch fresh water supply line or the fresh water tank second dosing device, wherein the controller, the steam is carried out the drain supply control According to the increase / decrease in the number of boilers and the increase / decrease in the operating load of each steam boiler, the first chemical injection control for increasing / decreasing the chemical injection amount by the first chemical injection device is performed, and each branch fresh water supply line or The second chemical injection control for increasing / decreasing the chemical injection amount by the second chemical injection device according to the increase / decrease of the new water flow rate of the common fresh water supply line is characterized.

According to invention of Claim 3, according to the increase / decrease in the number of the steam boilers which are performing the said drain supply control, and the increase / decrease in the operation load of each steam boiler, the chemical injection amount by said 1st chemical injection apparatus is changed. Since the amount is increased or decreased, it is possible to appropriately control the amount of the medicine injected into the drain. In addition to the effect of simplifying the system configuration because the amount of chemicals to be drained can be controlled without using a flow meter, the amount of chemicals to be supplied to fresh water during new water supply control is appropriately controlled. There is an effect that can be done.

  According to the present invention, in a closed drain system having a plurality of steam boilers and switching between drain supply control and fresh water supply control for each steam boiler, it is appropriate for the drain without complicating the system configuration. There is an effect that it is possible to perform various drug injections.

It is explanatory drawing explaining schematic structure of Example 1 of this invention. It is a flowchart figure explaining the control procedure of the Example 1. FIG. It is a flowchart figure explaining the control procedure of the 1st medicine injection control of the Example 1. It is a flowchart figure explaining the control procedure of the 2nd chemical injection control of the Example 1. FIG.

  Next, an embodiment of the present invention will be described. The embodiment of the present invention is preferably implemented in a closed drain system having a plurality of steam boilers and switching between drain supply control and fresh water supply control for each steam boiler.

This embodiment will be specifically described. The closed drain system of this embodiment (which may be referred to as a closed drain recovery system) includes a can body, and a plurality of steam boilers that supply steam generated by the can body to a load device; A sealed drain tank that collects drain discharged from the load device, a new water tank that stores fresh water, a controller that selectively switches between drain supply control and new water supply control in each steam boiler, A first chemical injection device that is driven during the drain supply control.

  In addition to the water supply switching control for selectively switching between the drain supply control and the fresh water supply control in each steam boiler, the controller performs a first chemical injection control for controlling a chemical injection amount by the first chemical injection device. Do. The feed water switching control and the first chemical injection control can be performed by a controller (individual controller) provided for each steam boiler, or can be configured to be performed by a common controller (common controller). Further, the water supply switching control may be performed by the individual controller, and the first chemical injection control may be performed by the common controller or the relay controller by receiving a necessary signal from the individual controller.

  In the drain supply control, the drain in the drain tank is supplied to the cans through a common drain supply line and a branched drain supply line branched from the common drain supply line, and the supply amount is adjusted.

  This drain supply control is preferably performed by turning on (driving) -off (stopping) one or more drain pumps provided in the common drain supply line and common to the steam boilers, and in each branch drain supply line. This is performed by opening and closing a provided drain control valve for water level control (hereinafter referred to as “preferred drain supply control”). In this case, the drain control to each steam boiler is performed by opening and closing the drain control valve so that the water level in the can body becomes the set water level by the water level sensor that detects the water level in the can body of each steam boiler. .

  The drain pump is always driven to rotate under the condition that there is a steam boiler for which drain supply control is performed, and preferably a circulation path connecting the drain pump downstream side of the common drain supply line and the drain tank. In addition, the drain pump is always driven, and a part of the drain is always circulated through the circulation path.

  The drain supply control can be performed by providing a drain pump for each branch drain supply line and controlling each drain pump by ON-OFF control or rotation speed control by a detection signal of the water level sensor. is there. In order to perform this type of control, many drain pumps are required, which has the disadvantage of increasing the initial cost.

  The fresh water supply control supplies fresh water in the fresh water tank to the cans through a common fresh water supply line and a branched fresh water supply line branched from the common fresh water supply line, and adjusts the supply amount. It is control to do.

  The fresh water supply control is preferably performed by providing a fresh water pump in the branch fresh water supply line corresponding to each steam boiler, and turning each new water pump on or off according to a detection signal of the water level sensor. (Hereinafter referred to as “preferable fresh water supply control”).

  In addition, this new water supply control is provided in the common fresh water supply line, and is provided in one or a plurality of new water pumps common to the steam boilers and in each branch fresh water supply line. It can be configured to perform by opening and closing a new water control valve for water level control. However, in general, each steam boiler has a built-in water supply pump. This water supply pump is used as a new water pump for “preferable new water supply control”.

The drain supply control and the fresh water supply control are selectively performed for each steam boiler by the controller. In the selection control by the controller, preferably, the pressure in each can body is a set value or less, the abnormally low water level of each can body, the abnormally high water level of each can body, or the supply water flow rate of the drain pump is reduced. When it is detected, it is determined as abnormal. When this abnormality is determined, the fresh water supply control is performed. When it is not determined as abnormal, the drain supply control is performed. This abnormality determination can include things other than those described above.

  And in each said steam boiler, it comprises so that drain supply control and fresh water supply control may not be performed simultaneously. That is, each of the branch drain supply lines is provided with a shut-off drain control valve that opens each of the branch supply lines during drain supply control and closes each of the branch drain supply lines during fresh water supply control. Each branch fresh water supply line is opened, and a new water control valve for shutting off that closes each branch fresh water supply line during drain supply control is provided in each branch fresh water supply line. The shut-off drain control valve is preferably provided separately from the water level control drain control valve, but may be shared. Further, the fresh water control valve for blocking is preferably provided separately from the fresh water control valve for controlling the water level, but can be shared.

  The first chemical injection device is configured to perform chemical injection to a common drain circulation portion that flows before the drain branches and flows to the branch drain supply line during the drain supply control. The “common drain circulation part” is preferably a drain circulation path formed between the drain tank and the common drain supply line, but may be the drain tank or the common drain supply line.

  When configured to inject medicine into the circulation path, when the first infusion device is configured with an infusion pump that intermittently injects medicine, it is common compared to what is infused into the common drain supply line. The chemical solution concentration in the drain supply line can be made uniform.

  The first chemical injection control by the first chemical injection device is based on the chemical injection by the first chemical injection device according to the increase / decrease in the number of steam boilers performing the drain supply control and the increase / decrease in the operating load of each steam boiler. This is a control to increase or decrease the amount.

  The “signal for increase / decrease in the operating load of each steam boiler” is not a direct feed water flow rate signal to each steam boiler but an indirect feed water to each steam boiler obtained from the operation signal of each steam boiler. It is a flow rate signal and can be calculated from the evaporation amount obtained from the combustion amount of each steam boiler and the amount of blow water discharged from the can body. Further, when the drain control valve adjusts the opening according to the combustion amount of each steam boiler, the opening signal is considered to be an indirect feed water flow signal to each steam boiler. Can be used as the “signal for increasing / decreasing the operating load of each steam boiler”. Further, the blow valve for controlling the blow water from the can body is controlled to open when a predetermined combustion amount is reached, and when blowing at a preset blow rate, the blow valve is synchronized with the open signal of the blow valve. Can be configured to perform drug injection.

  In the embodiment configured as described above, the controller selectively performs the drain supply control or the fresh water supply control for each steam boiler. And according to the increase / decrease in the number of the steam boilers which are performing the said drain supply control, and the increase / decrease in the operation load of each steam boiler, the chemical injection amount by said 1st chemical injection apparatus is increased / decreased. As a result, it is possible to appropriately control the amount of medicine injected into the drain of the common drain supply line. In addition, the system configuration can be simplified by controlling the amount of chemicals injected into the drain without using a flow meter.

In this embodiment, it is preferable that the first chemical injection device includes a plurality of chemical injection pumps corresponding to the number of the steam boilers, and the controller responds to an increase or decrease in the operation load of each steam boiler. The chemical injection amount of the first chemical injection device is controlled by increasing / decreasing the chemical injection amount of the corresponding chemical injection pump and stopping the chemical injection pump corresponding to the steam boiler performing the new water supply control. (Hereinafter referred to as “multiple drug injection pump control method”).

  “The plurality of chemical injection pumps according to the number of the steam boilers” is preferably the same number as the number of the steam boilers and the number of the chemical injection pumps, but a decrease in the accuracy of the chemical injection amount is allowed. In this case, one chemical injection pump can correspond to a plurality of steam boilers. For example, one chemical injection pump can correspond to two or three steam boilers.

  In this embodiment, the first chemical injection device includes a chemical injection pump common to the steam boilers, and the controller controls the number of the steam boilers performing the drain supply control and the number of the steam boilers. Increase / decrease the chemical injection volume of the common chemical injection pump according to the increase / decrease of the operation load of each steam boiler, that is, according to the operation load of the total increase / decrease of the operation load of each steam boiler performing the drain supply control. (Hereinafter referred to as “common chemical injection pump control method”).

  According to the above-mentioned “multiple chemical injection pump control method”, the chemical injection amount is controlled by controlling a plurality of chemical injection pumps. Control can be performed with high accuracy, and the control configuration can be simplified because no complicated control logic is required.

  In this embodiment, in addition to the above-described configuration, the controller includes a second chemical injection device that performs chemical injection to each of the new water supply lines or the new water tank at the time of the new water supply control. It can comprise so that the 2nd chemical injection control which increases / decreases the chemical injection quantity by said 2nd chemical injection apparatus according to increase / decrease in the new water flow volume of a branch fresh water supply line or the said common fresh water line can be comprised. A well-known thing can be employ | adopted for this 2nd chemical injection apparatus and 2nd chemical injection control.

  Further, in this embodiment, in order to compensate for the shortage of the drain, in addition to the above-described configuration, the fresh water in the new water tank is pressurized and supplied to the drain tank by a makeup water pump. be able to. In this case, a water level sensor for detecting the water level in the drain tank is provided, and when the water level in the drain tank decreases, the water level sensor detects this decrease and the water level in the drain tank becomes the set water level. Control.

  Here, the component which comprises the closed drain system of embodiment of this invention is demonstrated. The steam boiler and the can body are not limited to specific types and structures. The drain tank is not limited to a specific structure as long as it is a sealed type. The new water tank is an open type. Furthermore, a motor valve or an electromagnetic valve can be used for the drain control valve and the fresh water control valve. The chemical solution injected by the first chemical injection device and the second chemical injection device contains an anticorrosive and a scale inhibitor.

  As described above, an embodiment of the present invention is a closed drain system that switches between drain supply control and fresh water supply control for each steam boiler, and the controller performs the drain supply control of the steam boiler. The first chemical injection control is performed to increase / decrease the chemical injection amount by the first chemical injection device in accordance with the increase / decrease in the number of units and the increase / decrease in the operating load of each steam boiler.

A preferred form of a closed drain system that switches between drain supply control and fresh water supply control for each steam boiler is as follows.
That is, each of the can bodies, a water level sensor for detecting the water level of each can body, and a new water pump for supplying water to the can body, and a plurality of steam boilers for supplying steam generated in each can body to a load device; ,
A sealed drain tank for collecting drain discharged from the load device;
A new water tank for storing fresh water;
A drain pump for pressurizing drain in the drain tank, a branch drain supply line formed corresponding to each steam boiler and supplying the drain in the drain tank to the downstream side of each fresh water pump by the drain pump, and Drain supply means including a drain control valve provided in each branch drain supply line;
Replenishing water means for pressurizing fresh water in the new water tank by a replenishing water pump and supplying the pressurized water to the drain tank;
A branch fresh water supply line that is formed corresponding to each steam boiler and supplies fresh water in the water supply tank to the upstream side of each first pump by the makeup water pump and each branch fresh water supply line are provided. New water supply means including a new water control valve;
A controller that selectively performs drain supply control and fresh water supply control for each steam boiler;
The drain supply control is a control for controlling the water level in the can body to a set water level by the water level sensor by controlling opening and closing of each branch drain supply line in a state in which each branch fresh water supply line is closed. ,
In the fresh water supply control, each branch drain supply line is closed and the drive of the fresh water pump is controlled in a state where each branch fresh water supply line is opened, whereby the water level in the can body is controlled by the water level sensor. A closed drain system that controls the set water level.

  According to this closed drain system, if the drain supply control cannot be performed, the water supply control to the steam boiler can be performed by the new water supply control. And since drain supply control and new water supply control are not performed simultaneously, stable drain supply control or new water supply control can be performed.

  In this closed drain system, preferably, the controller is configured such that the pressure in each can body is equal to or lower than a set value, the abnormally low water level of each can body, the abnormally high water level of each can body, and the supply water flow rate of the drain pump is decreased. When any one of the above is detected, it is determined to be abnormal, and when the abnormality is determined, the fresh water supply control is performed, and when it is not determined abnormal, the drain supply control is performed.

  The preferable closed drain system further includes a control changeover switch and an alarm means, and the controller alerts the abnormality by the alarm means when the abnormality is determined, and operates the changeover switch to operate the changeover switch. It is configured to switch from the drain supply control to the fresh water supply control. In addition, at the time of the abnormality determination, the drain supply control can be switched to the fresh water supply control without operating the changeover switch.

  Next, a closed drain system according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram illustrating a schematic configuration of the first embodiment of the present invention, FIG. 2 is a flowchart illustrating a control procedure of the first embodiment, and FIG. 3 is a first flowchart of the first embodiment. FIG. 4 is a flowchart for explaining a control procedure for second medicine injection control according to the first embodiment.

<Configuration of Example 1>
The closed drain system according to the first embodiment includes cans 1A, 1B, and 1C, respectively, and supplies steam generated in the cans 1A, 1B, and 1C to the load devices 3 and 4 via the steam header 2 and the like. A plurality of steam boilers 5A, 5B, 5C, a closed drain tank 6 for collecting (collecting) drains discharged from the load devices 3, 4, an open-type new water tank 7 for storing fresh water, A first controller 8A, 8B, 8C that selectively switches between drain supply control and fresh water supply control in each of the steam boilers 5A, 5B, 5C; a first chemical injection device 9 that is driven during drain supply control; A second chemical injection device 10 driven during water supply control is provided as a main part.

  The load devices 3 and 4 are connected between the steam header 2 and the drain tank 6 by steam supply lines 11 and 12 and drain recovery lines 13 and 14.

  The drain tank 6 and the cans 1A, 1B, and 1C are connected to each other by a common drain supply line 15 and branch drain supply lines 16A, 16B, and 16C formed by branching from the common drain supply line 15.

  The common drain supply line 15 is provided with a drain pump 17 and a first check valve 18 that blocks the flow in the direction of the drain pump 17. The downstream side of the drain pump 17 and the upper portion of the drain tank 6 are connected by a circulation path 21 provided with a circulation control valve 19 and an orifice 20 as a flow rate restricting means.

  Each branch drain supply line 16A, 16B, 16C includes a first drain control valve 22A, 22B, 22C for drain shutoff, a second drain control valve 23A, 23B, 23C for water level control, and a common drain supply line 15 Second check valves 24A, 24B, and 24C that block the flow in the direction, and third check valves 25A, 25B, and 25C that block the flow in the anti-can bodies 1A, 1B, and 1C are provided. A water supply preheater (economizer) 26A, 26B, 26C is connected between the cans 1A, 1B, 1C and the third check valves 25A, 25B, 25C.

  Between the fresh water tank 7 and the drain tank 6, there is a makeup water line 30 provided with a makeup water pump 27, a fourth check valve 28 for blocking the flow toward the anti-fresh water tank 7, and a makeup water control valve 29. Connected. Reference numeral 31 denotes a return line that connects between the fourth check valve 28 and the makeup water control valve 29 and the fresh water tank 7. Reference numeral 32 denotes a water supply line to the new water tank 7. Reference numeral 33 is provided with a third drain control valve 34 for adjusting a drain storage amount that opens when drain of a predetermined water level or more is stored in the drain tank 6, and connects the drain tank 6 and the fresh water tank 7. It is an adjustment line.

  The fresh water tank 7 and each of the cans 1A, 1B, 1C include a common fresh water supply line 35 and branched fresh water supply lines 36A, 36B, 36C formed by branching from the common fresh water supply line 35. Connected with. The common fresh water supply line 35 is configured to include a makeup water pump 27 and a fourth check valve 28 in the common fresh water supply line 35 by sharing a part of the makeup water line 30.

  In each branch fresh water supply line 36A, 36B, 36C, flow rate detectors 37A, 37B, 37C, pressure regulating valves 38A, 38B, 38C, fresh water control valves 39A, 39B, 39C for shutting off fresh water, New water pumps 40A, 40B, and 40C and fifth check valves 41A, 41B, and 41C that block the flow in the direction of the common fresh water supply line 35 are provided. The branch fresh water supply lines 36A, 36B, and 36C share a part of the branch drain supply lines 16A, 16B, and 16C (parts including the third check valves 25A, 25B, and 25C). The third check valves 25A, 25B, and 25C and the fresh water pumps 40A, 40B, and 40C are those previously built in the steam boilers 5A, 5B, and 5C.

  Each steam boiler 5A, 5B, 5C is provided with water level sensors 42A, 42B, 42C for detecting the water level in each can 1A, 1B, 1C.

The first chemical injection device 9 includes a number of first chemical injection pumps 44A, 44B, 44C equal to the number of steam boilers 5A, 5B, 5C. Each first chemical injection pump 44A, 44B, 44C is connected to a chemical injection tank (not shown) that stores a common chemical solution, and discharge ports 45A, 45B, 45C corresponding to the first chemical injection pumps 44A, 44B, 44C, respectively. 45C to first drug injection line 46A, 46
A chemical solution is injected between the orifice 20 and the drain tank 6 of the circulation path (corresponding to the shared drain circulation portion of the present invention) 21 through B and 46C. The first chemical injection pumps 44A, 44B, and 44C use electromagnetic pumps that perform intermittent chemical injection.

  The first chemical injection pumps 44A, 44B, 44C are transmitted from the corresponding first controllers 8A, 8B, 8C, respectively, and relayed by the relay second controller 47 provided in the first chemical injection device 9. It is configured to be controlled by the first medicine injection control signal. Specifically, the first relay contacts 48A, 48B, 48C are provided on the power supply lines (reference numerals omitted) of the first drug injection pumps 44A, 44B, 44C, and the first controllers 8A, 8B, 8C are By opening the first relay contacts 48A, 48B, 48C, the first chemical injection pumps 44A, 44B, 44C are stopped. The first chemical injection control signal is composed of an energization control signal and a drive signal. While the first relay contacts 48A, 48B, 48C are closed by the energization control signal, the first chemical injection pumps 44A, 44B, 44C. Discharges a chemical solution intermittently (in a pulse manner) in response to a drive signal sent through a drive signal line (not shown).

  The second chemical injection device 10 has the same configuration as that of the first chemical injection device 9, and the difference is the chemical injection position. That is, the second chemical injection device 10 includes the second chemical injection pumps 49A, 49B, 49C in the number equal to the number of the steam boilers 5A, 5B, 5C. Each of the second chemical injection pumps 49A, 49B, 49C is connected to a chemical injection tank (not shown) that stores a common chemical solution, and discharge ports 50A, 50B, 49C, corresponding to the second chemical injection pumps 49A, 49B, 49C, respectively. From 50C through the second chemical injection line 51A, 51B, 51C, between the fresh water control valve 39A, 39B, 39C of each branch fresh water supply line 36A, 36B, 36C and the fresh water pump 40A, 40B, 40C Is configured to inject. The second chemical injection pumps 49A, 49B, and 49C also use electromagnetic pumps that perform intermittent chemical injection.

The second chemical injection pumps 49A, 49B, 49C are transmitted from the corresponding first controllers 8A, 8B, 8C, respectively, and relayed by the relay third controller 52 provided in the second chemical injection device 10. It is configured to be controlled by a second medicine injection control signal. Specifically, second relay contacts 53A, 53B, and 53C are provided in the power supply lines (reference numerals omitted) of the second chemical injection pumps 49A, 49B, and 49C, and the fourth controller 52 is connected to each second relay. By opening the contacts 53A, 53B, 53C, the second chemical injection pumps 49A, 49B, 49C are stopped . The first chemical injection control signal is composed of an energization control signal and a drive signal. While the second relay contacts 53A, 53B, 53C are closed by the energization control signal, the second chemical injection pumps 49A, 49B, 49C. Discharges a chemical solution intermittently (in a pulse manner) in response to a drive signal sent through a drive signal line (not shown).

  Each of the first controllers 8A, 8B, 8C includes a water supply control changeover switch (not shown) provided in each steam boiler 5A, 5B, 5C, and water level sensors 42A, 42B, 42C of each steam boiler 5A, 5B, 5C, Input signals from sensors such as flow rate detectors 37A, 37B, and 37C, and based on pre-stored control procedures, drain pump 17, circulation control valve 19, first drain control valves 22A, 22B, 22C, Each second drain control valve 23A, 23B, 23C, makeup water control valve 29, third drain control valve 34, makeup water pump 27, fresh water control valves 39A, 39B, 39C, fresh water pumps 40A, 40B, 40C, first The one chemical injection device 9 and the second chemical injection device 10 are controlled.

The control procedure of each of the first controllers 8A, 8B, and 8C includes the procedure of the water supply switching control (the water supply switching control procedure) for switching to either the drain supply control or the fresh water supply control for each steam boiler 5A, 5B, 5C. ), A first chemical injection control procedure (first chemical injection control procedure) for controlling the first chemical injection device by sending a first chemical injection control signal during the drain supply control included in the drain supply control, and a new water supply The control includes a second chemical injection control procedure (second chemical injection control procedure) in which the second chemical injection control signal is transmitted by sending a second chemical injection control signal during control of fresh water supply. Outlines of the water supply switching control procedure, the first chemical injection control procedure, and the second chemical injection control procedure are shown in FIGS. 2, 3, and 4, respectively.

<Operation of Example 1>
Here, the operation of the first embodiment will be described with reference to the drawings. Referring to FIG. 2, in process step S1 (hereinafter, process step SN is simply referred to as SN), each first controller 8A, 8B, 8C is operated by an operation switch (illustrated) of each steam boiler 5A, 5B, 5C. It is determined whether (omitted) is ON.

(Water supply switching control)
If YES is determined in S <b> 1, the process proceeds to S <b> 2 and it is determined whether or not the water supply control switch is turned on. If NO is determined in S2, the process proceeds to S3 to determine whether or not the next abnormality has occurred. The determination of abnormal is that the pressure in each can body 1A, 1B, 1C is less than the set value, the abnormally low water level of each can body 1A, 1B, 1C, the abnormal high water level of each can body 1A, 1B, 1C, and the drain pump 17 This is performed when any one of the water supply flow rate drops is detected. A decrease in the feed water flow rate of the drain pump 17 is determined when the specified water level is not satisfied even though the drain feed water control is performed.

  If it determines with abnormality by S3, it will transfer to S5, will stop operation | movement of each steam boiler 5A, 5B, 5C, this abnormal stop will be alarmed by a display (illustration omitted), and a process will return to S1. A user or maintenance staff who knows the abnormal stop alarm operates the water supply control switch. Then, YES is determined in S2, the process proceeds to S6, and fresh water supply control is executed. When NO is determined in S3, that is, when it is not determined to be abnormal, drain supply control is executed.

(Drain supply control)
The drain supply control in S4 will be described. Drain supply control is performed by turning on and off the drain pump 17 and opening and closing the first drain control valves 22A, 22B, and 22C and the second drain control valves 23A, 23B, and 23C. The first drain control valves 22A, 22B, and 22C that are performing drain supply control are opened, and the first drain control valves 22A, 22B, and 22C that are performing fresh water supply control are closed.

  More specifically, each second drain control valve 23A, which performs drain supply control so that the water level in each can 1A, 1B, 1C becomes the set water level by each water level sensor 42A, 42B, 42C. This is done by opening and closing 23B and 23C. During this drain supply control, the drain pump 17 is always driven to rotate. As a result, the drains in the drain tank 6 pass through the common drain supply line 15 and the respective steam boilers 5A, 5B, 5C that are performing drain supply control, and the respective can bodies 1A, 1B, through the branched drain supply lines 16A, 16B, 16C. To 1C. The supply amount is controlled by opening / closing each of the second drain control valves 23A, 23B, and 23C.

(First chemical injection control)
During this drain supply control, the first chemical injection control of FIG. 3 is performed. In S11, each first controller 8A, 8B, 8C takes in a signal indicating whether or not it is performing drain supply control, and sends a first chemical injection control signal to the second controller 47 in S12. . The first chemical injection control signal includes a signal indicating whether each steam boiler 5A, 5B, 5C is a drain supply control or the fresh water supply control, and a signal for increasing / decreasing the operation load of each steam boiler 5A, 5B, 5C. It is out.

The increase / decrease signal of the operation load is an indirect feed water flow rate signal to the steam boilers obtained from the operation signals of the steam boilers 5A, 5B, and 5C, and the combustion amount of the steam boilers 5A, 5B, and 5C ( (Evaporation amount) and the amount of blow water discharged from the cans 1A, 1B, 1C. The operation load increase / decrease signal is sent to the second controller 47 as a drive signal by a pulse corresponding to the operation load at that time.

  The second controller 47 that has received the first chemical injection control signal closes the first relay contacts 48A, 48B, and 48C corresponding to the steam boilers 5A, 5B, and 5C that are performing drain supply control. Each first chemical injection pump 44A, 44B, 44C to be operated is operated. And since each steam boiler 5A, 5B, 5C sends the drive signal according to the increase / decrease in the operation load, the medicine injection amount is adjusted by driving the medicine injection pump in response to this drive signal. The first relay contacts 48A, 48B, 48C corresponding to the steam boilers 5A, 5B, 5C performing the fresh water supply control are opened, and the first chemical injection pumps 44A, 44B, 44C are stopped.

  By such first chemical injection control, the first chemical injection is controlled according to the increase / decrease in the number of steam boilers 5A, 5B, 5C performing drain supply control and the increase / decrease in the operation load of each steam boiler 5A, 5B, 5C. The amount of medicine injected by the device 9 is controlled. As a result, it is possible to appropriately control the amount of the chemical supplied to the drain of the common drain supply line 15 and the amount of the chemical supplied to the drain supplied to the steam boilers 5A, 5B, 5C. Moreover, since this 1st chemical injection control is performed without using a flowmeter, a closed drain system structure can be simplified.

  In addition, since the amount of the chemical injection is controlled by controlling the same number of first chemical injection pumps 44A, 44B, 44C as the steam boilers 5A, 5B, 5C, the chemical injection amount can be controlled with high accuracy and a complicated control logic is required. Therefore, the control configuration can be simplified.

  At the time of this drain supply control, when the water level in the drain tank 6 drops, this drop is detected by a water level sensor (not shown), the makeup water control valve 29 is opened, and the makeup water pump 27 is not operated. Drive this. Then, the fresh water in the fresh water tank 7 is supplied to the drain tank 6 and controlled so that the water level in the drain tank 6 becomes the set water level.

(New water supply control)
In the new water supply control in S6, the fresh water control valves 39A, 39B, and 39C of the steam boilers 5A, 5B, and 5C that are performing the new water supply control are opened, and the detection signals of the water level sensors 42A, 42B, and 42C are used. The fresh water pumps 40A, 40B, and 40C are turned on and off so that the water levels in the can bodies 1A, 1B, and 1C become the set water levels. The fresh water in the fresh water tank 7 passes through the common fresh water supply line 35, and each can 1A, through each of the steam boilers 5A, 5B, 5C branching fresh water supply lines 36A, 36B, 36C that are controlling the fresh water supply. Supplied to 1B and 1C.

(Second injection control)
At the time of this new water supply control, the second chemical injection control of FIG. 4 is performed. In S21, the first controllers 8A, 8B, and 8C detect the detected flow rate signals (pulse drive signals) from the flow rate detectors 37A, 37B, and 37C of the steam boilers 5A, 5B, and 5C performing the fresh water supply control. Capture. In S <b> 2, a second chemical injection control signal is sent to the third controller 52. This second chemical injection control signal includes a detected flow rate signal (pulse drive signal) relating to each steam boiler 5A, 5B, 5C corresponding to an increase / decrease signal of the operation load of each steam boiler 5A, 5B, 5C.

The third controller 52 that has received the second chemical injection control signal closes the first relay contacts 53A, 53B, and 48C corresponding to the steam boilers 5A, 5B, and 5C performing the fresh water supply control, Each second chemical injection pump 49A, 49B, 49C is operated. And the amount of chemical injection is adjusted according to increase / decrease of the operation load of each steam boiler 5A, 5B, 5C, ie, a detected flow signal (pulse drive signal). The second relay contacts 53A, 53B, 53C corresponding to the steam boilers 5A, 5B, 5C performing drain supply control are opened, and the corresponding second chemical injection pumps 49A, 49B, 49C are stopped. In this way, each second chemical injection pump 49A, 49B, 49C is controlled. The medicinal solution in which the medicinal amount is adjusted is injected from the second medicinal pumps 49A, 49B, 49C to the branch fresh water supply lines 36A, 36B, 36C through the second medicinal lines 51A, 51B, 51C.

1A-1C can body 3, 4 load equipment 5A-5C boiler 6 drain tank 7 fresh water tank 8 first controller (controller)
DESCRIPTION OF SYMBOLS 9 1st chemical injection apparatus 10 2nd chemical injection apparatus 15A-15C Common drain supply line 16A-16C Branch drain supply line 17 Drain pump 21 Circulation path (common drain circulation part)
35A-35C Common fresh water supply line 36A-36C Branch fresh water supply line

Claims (3)

A plurality of steam boilers each having a can body and supplying steam generated in the can body to a load device,
A sealed drain tank for collecting drain discharged from the load device;
A new water tank for storing fresh water;
Drain supply control for supplying drain in the drain tank to each can through a common drain supply line and a branched drain supply line branched from the common drain supply line, and supplying fresh water in the new water tank to common new water A controller for selectively switching in each steam boiler, a fresh water supply control to be supplied to each can through a line and a branch fresh water supply line branched from the common fresh water supply line;
A first medicine that has a plurality of medicine injection pumps corresponding to the number of the steam boilers and injects into a common drain circulation part that circulates before the drain branches and flows into the branch drain supply line during the drain supply control. With a device
The controller is configured to increase or decrease a chemical injection amount by the first chemical injection device in accordance with an increase or decrease in the number of the steam boilers performing the drain supply control and an increase or decrease in the operation load of each steam boiler. There line the dosing control,
In the first chemical injection control, the chemical corresponding to the steam boiler that performs the new water supply control while increasing or decreasing the chemical injection amount of the corresponding chemical injection pump according to the increase or decrease of the operation load of each steam boiler. A closed drain system, characterized in that the amount of chemical injection by the first chemical injection device is controlled by stopping the injection pump . A second chemical injection device for performing chemical injection to each branch fresh water supply line or the new water tank at the time of the new water supply control;
The controller performs second chemical injection control to increase / decrease the chemical injection amount by the second chemical injection device in accordance with increase / decrease of the fresh water flow rate of each branch fresh water supply line or the common fresh water supply line. closed de Len system of claim 1, wherein the.   A plurality of steam boilers each having a can body and supplying steam generated in the can body to the load equipment
La and
  A sealed drain tank for collecting drain discharged from the load device;
  A new water tank for storing fresh water;
  Drain supply control for supplying drain in the drain tank to each can through a common drain supply line and a branched drain supply line branched from the common drain supply line, and supplying fresh water in the new water tank to common new water A controller for selectively switching in each steam boiler, a fresh water supply control to be supplied to each can through a line and a branch fresh water supply line branched from the common fresh water supply line;
  At the time of the drain supply control, a first chemical injection device that performs chemical injection to a common drain circulation part that flows before the drain branches and flows into the branched drain supply line;
  A second chemical injection device for performing chemical injection to each branch fresh water supply line or the new water tank at the time of the new water supply control;
  The controller is configured to increase or decrease a chemical injection amount by the first chemical injection device in accordance with an increase or decrease in the number of the steam boilers performing the drain supply control and an increase or decrease in the operation load of each steam boiler. Dosing control,
  Closed, wherein the second chemical injection control is performed to increase or decrease the chemical injection amount by the second chemical injection device according to the increase or decrease of the fresh water flow rate of each branch fresh water supply line or the common fresh water supply line. Drain system.

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