JP6678692B2 - Boiler system and control device for boiler system - Google Patents

Description

  The present invention relates to a boiler system having an exhaust gas boiler and a once-through boiler.

  BACKGROUND ART As a boiler system, a boiler system including an exhaust gas boiler that generates steam by exhaust gas generated by a gas turbine and a plurality of once-through boilers that supplement the generation of steam by the exhaust gas boiler is known (for example, see Patent Document 1). ). In such a boiler system, when the amount of generated steam decreases, the number of once-through boilers corresponding to the degree of the reduction is set to an operation state, thereby increasing the amount of generated steam.

JP-A-2000-274211

As a result of closely observing the operation state of the boiler system as described above, the inventors of the present application have noticed that depending on the operation state, each once-through boiler may frequently repeat operation and stop (start and stop). . In this case, for example, the operating efficiency of the once-through boiler is reduced, and the fuel efficiency is increased. In view of the above points, the present invention can increase the operating efficiency of the once-through boiler, achieve energy saving, and the like. It is intended to be.

To achieve the above object, the present invention provides:
A control device for a boiler system, comprising: a first boiler, a second boiler that is a once-through boiler, and a header into which steam generated by the first boiler and the second boiler is introduced.
A second boiler operation that suppresses the operation of the second boiler according to at least one of the degree of restriction of the amount of heat introduced into the first boiler and the opening degree of a vaporization valve that releases steam from the header. It is characterized by having a suppressing part.

   Thereby, for example, when the limit of the amount of heat introduced into the first boiler is equal to or more than a predetermined value, the step-up control of the second boiler is suppressed, thereby suppressing the careless operation of the second boiler. Can be easily done.

  ADVANTAGE OF THE INVENTION According to this invention, the operating efficiency of a once-through boiler can be improved and energy saving can be achieved.

It is a block diagram showing the composition of the boiler system of an embodiment. It is a graph which shows the example of a bypass damper opening degree control of an exhaust gas boiler. It is a graph which shows the example control of the number of once-through boilers. It is a flowchart which shows the control operation of a boiler system. It is a graph which shows the typical specific example of the control content of a boiler system.

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

(Configuration of boiler system)
As shown in FIG. 1, the boiler system is provided with an exhaust gas boiler device 110 and a plurality of once-through boiler devices 120. The steam generated by these is supplied to the load via the header 130.

  The exhaust gas boiler device 110 includes a GE / GT 111 (gas engine / gas turbine), an exhaust gas boiler 112, an exhaust gas boiler pressure gauge 113, a valve opening control unit 114, and a bypass damper 115. The GE / GT 111 generates power by, for example, a gas engine or a gas turbine, and the exhaust gas is introduced into the exhaust gas boiler 112 to be used for generating steam. The GE / GT 111 and the exhaust gas boiler 112 constitute, for example, a CGS (cogeneration system). The exhaust gas boiler pressure gauge 113 detects the pressure P1 of the steam near the outlet of the exhaust gas boiler 112. The valve opening control unit 114 controls the amount of exhaust gas introduced from the GE / GT 111 into the exhaust gas boiler 112 by controlling the opening degree of the bypass damper 115 according to the pressure P1 as shown in FIG. 2, for example. It has become.

  On the other hand, the once-through boiler device 120 includes a once-through boiler 121 and a once-through boiler number controller 122. The once-through boiler 121 is detected by the header pressure gauge 131, for example, as shown in FIG. 3, when the steam generated from the exhaust gas boiler 112 decreases or when the load on the secondary side increases due to increased steam utilization. The number of once-through boilers 121 according to the pressure (pressure drop) of the header 130 is operated to generate and supply steam.

  The header 130 supplies the steam generated by the exhaust gas boiler device 110 and the once-through boiler device 120 to a load. The header 130 is provided with, for example, a steam release valve 116 so that the above-mentioned inside can be released according to the steam pressure inside the header 130, the steam pressure P1 near the outlet of the exhaust gas boiler 112, and the like. .

  The once-through boiler operation suppressing unit 140 is described in detail below, for example, based on the opening degree detected by a sensor (not shown) of the bypass damper 115 of the exhaust gas boiler device 110 and the pressure P2 of the header 130 detected by the header pressure gauge 131. As described above, when the pressure of the header 130 is temporarily reduced and a sufficient supply of steam is expected from the exhaust gas boiler 112 within an allowable range, the operation of the once-through boiler 121 is suppressed. It has become.

(Operation of boiler system)
Hereinafter, an example of a control operation performed by the once-through boiler operation suppressing unit 140 in the above-described boiler system will be described with reference to FIGS. 4 and 5.

  (S101) First, it is determined whether or not the setting for performing the operation suppression control of the once-through boiler 121 has been made according to the opening degree of the bypass damper 115 and the like. In other words, the suppression control function as described below may always be activated, but by allowing such a function to be turned ON / OFF, the degree of freedom of control can be increased. If the operation suppression control is not performed, the process proceeds to (S107), and a number control instruction is issued to the once-through boiler number control unit 122, and the control of the once-through boiler number control unit 122 causes t0 to t5 in FIG. As shown in the period, the number of operating once-through boilers 121 according to the pressure of the header 130 is controlled. More specifically, for example, when the header pressure P2 falls below the predetermined reference value C at time t1, the number of once-through boilers 121 corresponding to the pressure drop is operated. Eventually, when the header pressure P2 recovers to the reference value C (Pa) at time t2, all of the once-through boilers 121 stop. Similarly, in the period from t2 to t3, the number of once-through boilers 121 corresponding to the header pressure P2 is operated.

  When it is determined (YES) in the above (S101), that is, when the suppression control of the once-through boiler 121 is performed, the process proceeds to (S102, S103) and is shown in a period from t5 to t11 in FIG. Such an operation is performed. Here, in the period from t0 to t5 and the period from t5 to t11, the header pressure P2 and the opening degree of the bypass damper do not necessarily change in the same manner if the control that is normally performed is different, but here, for convenience, In order to easily understand the relationship between the number of operating once-through boilers 121 and the number of operating once-through boilers 121, they are shown as changing similarly.

  (S102, S103) It is determined whether the GE / GT 111 is operating and there is no information indicating that the GE / GT 111 is out of order. If these determinations are (NO), the processing is performed in the same manner as described above. In (S107), the number of once-through boilers 121 is instructed to the once-through boiler number control unit 122, and the number of operating once-through boilers 121 is controlled. That is, when the GE / GT 111 is not operating or is out of order, an increase in steam by the exhaust gas boiler 112 cannot be expected, so that control is performed so as to increase the number of operating once-through boilers 121 immediately.

  (S104, S105) If any of the above (S101 to S103) is (YES), then whether the opening degree of the bypass damper 115 of the exhaust gas boiler device 110 is larger than a predetermined set value A (%) , And whether the header pressure P2 is higher than a predetermined set value B (Pa). If any of them is (NO), the process also proceeds to (S107), and the number control instruction is sent to the once-through boiler number control unit 122. Is performed, and the number of once-through boilers 121 is controlled.

  (S106) On the other hand, if the opening degree of the bypass damper 115 is larger than the set value A (%) and the header pressure P2 is higher than the set value B (Pa), the number of operating the once-through boilers 121 does not need to be increased. Eventually, when the opening degree of the bypass damper 115 becomes small, it is expected that the pressure P1 near the outlet of the exhaust gas boiler 112 will increase and the header pressure P2 of the header 130 will also increase, so that the step-up of the once-through boiler 121 is not performed. After the number control control instruction is given to the once-through boiler number control unit 122, the process returns to (S101) and the same processing is repeated.

  Specifically, for example, if the setting for performing the operation suppression control of the once-through boiler 121 is made after time t5 shown in FIG. 5, the opening degree of the bypass damper 115 becomes equal to or less than the set value A (%) at time t6. In such a case, the operation of the once-through boiler 121 is controlled by the once-through boiler number control unit 122 according to the header pressure P2. That is, for example, when the header pressure P2 becomes equal to or less than the predetermined reference value C (Pa) at time t7, the number of once-through boilers 121 according to the pressure drop is operated in the same manner as at time t1. Further, even when the opening degree of the bypass damper 115 becomes larger than the set value A (%) at the time t8, if the header pressure P2 is equal to or less than the set value B (Pa), it is more than just closing the bypass damper 115. The process proceeds to (S107) to perform the number control by the once-through boiler number control unit 122 so that the header pressure P2 can be promptly increased. However, when the header pressure P2 becomes larger than the set value B (Pa) at time t9, the step-up of the once-through boiler 121 is not performed even if the header pressure P2 is equal to or less than the reference value C (Pa). Similarly, if the opening degree of the bypass damper 115 is larger than the set value A (%) as in the time t10 to t11, the number of the once-through boilers 121 even if the header pressure P2 becomes equal to or less than the reference value C (Pa). Control is suppressed.

   When the opening degree of the bypass damper is equal to or more than a predetermined value, such as after the time t9 or the time 10 to t11, and particularly when the header pressure P2 is equal to or more than a predetermined value, the step-up control of the once-through boiler 121 is suppressed. This makes it difficult for the step-up control and the control of the bypass damper opening degree to interfere with each other, so that careless operation (start / stop) of the once-through boiler 121 can be suppressed and energy saving can be easily achieved.

  In the case where the above-described control is performed, the operation start and stop of the once-through boiler 121 are not limited to be performed immediately when the conditions are satisfied. Or the once-through boiler 121 may be able to temporarily perform reheating after the opening degree of the exhaust gas bypass damper becomes equal to or less than the set value.

  In the above example, the operation of the once-through boiler 121 is suppressed according to the opening degree of the bypass damper 115. However, the present invention is not limited to this. If provided, operation suppression may be performed instead of or together with the opening of the bypass damper 115 in accordance with the opening of the vaporization valve 116.

  Further, in the above example, an example in which the GE / GT 111 and the exhaust gas boiler 112 are used is shown. However, the present invention is not limited to this. For example, a boiler derived from unused energy such as waste energy or natural energy may be used. These may be used in combination. That is, for example, in the case where the amount of heat supplied or the amount of released steam of the boiler is limited, the frequent start and stop of the once-through boiler can be easily avoided by releasing the limitation.

110 Exhaust gas boiler 111 GE / GT
112 Exhaust gas boiler 113 Exhaust gas boiler pressure gauge 114 Valve opening control unit 115 Bypass damper 116 Vaporization valve 120 Once-through boiler device 121 Once-through boiler 122 Number of once-through boiler number control unit 130 Header 131 Header pressure gauge 140 Once-through boiler operation suppressing unit

Claims (7)

It has a first boiler, a second boiler that is a once-through boiler, and a header into which steam generated by the first boiler and the second boiler is introduced. A controller for a boiler system in which the second boiler is operated when the value is equal to or less than a threshold,
A second boiler operation that suppresses the operation of the second boiler according to at least one of the degree of restriction of the amount of heat introduced into the first boiler and the opening degree of a vaporization valve that releases steam from the header. With a suppression unit,
The second boiler operation suppressing unit is configured to perform the second boiler operation suppression unit, when the steam pressure in the header is equal to or less than a predetermined threshold, and at least one of the heat amount restriction degree and the opening of the vaporization valve is equal to or more than a predetermined value. A control device for a boiler system, characterized in that the operation of the boiler is suppressed. It is a control device of the boiler system of Claim 1, Comprising:
The boiler system further includes a second boiler number control unit that controls the number of operating second boilers according to the pressure of the header,
The control device for a boiler system, wherein the second boiler operation suppression unit is configured to control the second boiler number control unit. It is a control device of the boiler system of Claim 2, Comprising:
The control device for a boiler system, wherein the second boiler operation suppression unit further suppresses the operation of the second boiler when the pressure of the header is equal to or higher than a predetermined value. It is a control device of the boiler system according to any one of claims 1 to 3,
The second boiler operation suppressing unit can be set so as not to suppress the operation of the second boiler irrespective of at least one of the degree of restriction of the heat quantity and the opening of the vaporization valve. Boiler system controller. A control device for the boiler system according to any one of claims 1 to 4,
The second boiler operation suppressing unit is configured to, when at least one of the information indicating that the device for introducing heat into the first boiler is not operating and the information indicating the failure of the device is present, determine the heat amount. A control device for a boiler system, characterized in that it can be set so as not to suppress the operation of the second boiler irrespective of at least one of the degree of restriction and the opening of the vaporization valve. It is a control device of the boiler system according to any one of claims 1 to 5,
The control device for a boiler system, wherein the first boiler includes at least one of an exhaust gas boiler, a waste energy utilization boiler, and a natural energy utilization boiler. A control device for the boiler system according to claim 1,
Said first boiler;
The second boiler,
The above header,
A boiler system comprising:

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