JP6557387B1 - COGENERATION SYSTEM, COGENERATION SYSTEM CONTROL DEVICE, AND COGENERATION SYSTEM CONTROL METHOD - Google Patents

Abstract

An energy saving effect of a cogeneration system is enhanced. A cogeneration system includes a cogeneration device, a fuel gas boiler (through-flow boiler 111), a steam header 114, and a heat source device 101 to which steam is supplied from the steam header 114. The control device of the cogeneration system is a hot / cold water flowing into the heat source unit 101 according to the pressure of the steam header 114, the flow rate of the fuel gas supplied to the once-through boiler 111, and the opening degree of the steam valve 114b of the steam header 114. The control part which increases / decreases the flow volume of is provided. [Selection] Figure 2

Description

  The present invention relates to a cogeneration system having a cogeneration apparatus and a separately provided boiler, a control apparatus for such a cogeneration system, and a control method.

  As a technology for improving the exhaust heat utilization rate of the cogeneration system, the steam pressure supplied by the first boiler provided in the cogeneration system should be set higher than the steam pressure supplied by the separately provided second boiler. Thus, a technique is known in which the steam generated by the first boiler is preferentially supplied (see, for example, Patent Document 1).

JP 2015-17713 A

  However, even if the steam generated by the first boiler is preferentially supplied as described above, in practice, the second boiler is frequently in an operating state, and the fuel consumption is not necessarily reduced. Not exclusively.

  In view of the above points, an object of the present invention is to easily enhance the energy saving effect of a cogeneration system.

In order to achieve the above object, the present invention provides:
A cogeneration device having an exhaust gas boiler;
A fuel gas boiler that generates steam by burning fuel gas;
A steam header to which steam generated by the exhaust gas boiler and the fuel gas boiler is input;
A heat source machine to which steam is supplied from the steam header;
A control device for a cogeneration system having
When the pressure of the steam header is lower than a predetermined threshold value, the flow rate of the cold / hot water flowing into the heat source unit is gradually decreased every time the flow rate of the fuel gas supplied to the fuel gas boiler exceeds a predetermined threshold value. While letting
When the pressure of the steam header is higher than a predetermined threshold, every time the opening of the evaporating valve for lowering the pressure of the steam header exceeds a predetermined threshold, cold / hot water flowing into the heat source unit A control unit for gradually increasing the flow rate is provided.

  As a result, the flow rate of the cold / hot water flowing into the heat source machine when the pressure in the steam header decreases is decreased, making it difficult for the fuel gas boiler to be in an indirect operation state or increasing the pressure in the steam header. Sometimes, the energy efficiency can be easily improved by increasing the flow rate of the cold / hot water flowing into the heat source machine so that the steam is not easily released from the steam header.

  According to the present invention, it is possible to easily increase the energy saving effect of the cogeneration system.

It is a block diagram which shows the structure of a cogeneration system. It is explanatory drawing which shows the example of the driving | running state of a cogeneration system. It is a functional block diagram showing an example of control operation of a cogeneration system.

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

(Schematic configuration of cogeneration system)
As shown in FIG. 1, the cogeneration system (CGS) of the present embodiment is provided with a cogeneration device including a CGS generator 112 and an exhaust gas boiler 113, and generates power by operating a gas engine or a gas turbine. In addition, steam is generated by the heat of the exhaust gas. The generated steam is supplied to the steam load 115 and is also supplied to the heat source unit 101 for both hot water and steam, and cold water and hot water are supplied to the cold / hot water load 105. The heat source apparatus 101 is not limited to the combination of hot water and steam, but may be a steam dedicated heat source apparatus in which steam is exclusively used as a heat source.

(Detailed configuration of cogeneration system)
The hot water / steam combined heat source unit 101 is constituted by, for example, one or a plurality of absorption chillers, and generates cold / hot water and supplies the cold / hot water load 105 via the cold / hot water header 103. It has become. The cold / hot water returned from the cold / hot water load 105 is sent to the heat source device 101 again via the cold / hot water return header 104 and the inverter-type pump 122, for example. Further, for example, one or a plurality of electric heat source units 102 are provided between the cold / hot water return header 103 and the cold / hot water return header 104 to supply cold / hot water regardless of whether steam is supplied or not. It has come to be able to do.

  The steam supplied to the heat source device 101 is generated not only by the exhaust gas boiler 113 as described above but also by combustion of fuel gas by one or a plurality of once-through boilers 111 (fuel gas boilers). It has become. Steam generated by the exhaust gas boiler 113 and the once-through boiler 111 is supplied to the once-through boiler 111 and the steam load 115 via the steam header 114.

  Moreover, the control part 121 is provided in the cogeneration system, and the flow rate of the cold / hot water flowing into the heat source apparatus 101 is controlled by the pump 122 according to the state of each part. More specifically, fuel gas is supplied to the once-through boiler 111 via a fuel gas flow meter 111 a, and a power generation meter 112 a is connected to the CGS generator 112, and signals corresponding to these flow rates and power are transmitted to the control unit 121. To be input. Further, a bypass damper 113a for releasing excess exhaust gas is provided between the CGS generator 112 and the exhaust gas boiler 113, and a signal indicating the opening degree is input to the control unit 121. In addition, the steam header 114 is provided with a pressure gauge 114 a that detects the pressure of the internal steam, and a signal corresponding to the detected pressure is input to the control unit 121. Further, the steam header 114 is provided with a steam release valve 114 b for releasing excess steam, and a signal indicating the opening degree is input to the control unit 121. The control unit 121 controls the flow rate of cold / hot water flowing into the heat source device 101 by the pump 122 in accordance with the signal input as described above.

  In the cogeneration system, in addition to the control by the control unit 121, each part is controlled by a normal general control operation. However, since it is not the main point of the control operation performed in the present embodiment, the description will be given. Omitted.

(Control action)
As shown in FIG. 2, when the steam pressure in the steam header 114 is less than a predetermined threshold, for example, less than 0.78 MPa, the controller 121 determines that the flow rate of the fuel gas supplied to the once-through boiler 111 is the predetermined threshold. The flow rate of the cold / warm water sent from the pump 122 to the heat source device 101 is gradually reduced every time. That is, the situation where the pressure of the steam header 114 becomes low may be, for example, a case where the supply of steam from the exhaust gas boiler 113 is small or the supply of steam to the heat source unit 101 or the steam load 115 is large. In such a case, the general control of the once-through boiler 111 makes it easy to increase the number of operating once-through boilers 111 and increase the amount of fuel gas supplied.

  Thus, when the flow rate of the fuel gas exceeds a predetermined threshold value, the control unit 121 decreases the flow rate of the pump 122 by a predetermined amount. Then, the amount of steam required by the heat source device 101 is reduced, and therefore, it is possible to suppress the operation of the once-through boiler 111 in order to supply the heat source device 101 with steam. In this case, when the load required by the cold / hot water load 105 is large, the heat source device 102 operates as necessary to supply the necessary cold / hot water, thereby making it easy to suppress the energy consumption as a whole. To be able to.

  Here, the control for decreasing the flow rate of the cold / hot water is performed every time the flow rate of the fuel gas exceeds a predetermined threshold value, while the flow rate of the cold / hot water is maintained when the flow rate of the fuel gas falls below the predetermined threshold value. Is done. That is, as long as the situation that requires an increase in the flow rate of the fuel gas continues, the amount of steam sent to the heat source device 101 decreases, and the steam pressure in the steam header 114 is easily increased.

  Further, when the pressure of the steam in the steam header 114 exceeds the predetermined threshold, the control unit 121 causes the heat source from the pump 122 each time the opening degree of the evaporating valve 114b of the steam header 114 exceeds the predetermined threshold. The flow rate of cold / hot water sent to the machine 101 is gradually increased. That is, the situation in which the pressure of the steam header 114 increases and the opening of the steam valve 114b increases, for example, there is a large amount of steam supplied from the exhaust gas boiler 113, or the steam supply to the heat source unit 101 or the steam load 115 is increased. This may be the case when the supply is low. In such a case, the evaporative valve 114b is easy to open.

  Thus, when the opening degree of the evaporating valve 114b exceeds a predetermined threshold, the control unit 121 increases the flow rate of the pump 122 by a predetermined amount. As a result, the amount of steam required by the heat source device 101 increases, so that more steam generated by the exhaust gas boiler 113 is supplied to the heat source device 101, and the operation of the heat source device 102 can be suppressed or reduced. Become. Therefore, the energy consumption as a whole can be easily reduced.

  Here, the control for increasing the flow rate of the cold / warm water is performed every time the opening degree of the evaporating valve 114b exceeds a predetermined threshold value, while when the opening degree of the evaporating valve 114b is lower than the predetermined threshold value, The flow rate of cold / hot water is maintained. That is, as long as the situation that requires opening of the steam release valve 114b continues, the amount of steam sent to the heat source device 101 increases, and the steam generated by the exhaust gas boiler 113 is easily used effectively.

(Initial value of cold / hot water flow rate)
The initial value of the cold / hot water flow rate when the above control is performed is set as follows, for example.

  That is, as shown in FIG. 3, for example, when the operation of the cogeneration system is started and an optimum control start command is issued, the surplus steam amount based on the opening degree of the bypass damper 113a and the generated power of the CGS generator 112 Further, an initial value is set like the optimum flow rate estimated in accordance therewith. Note that the initial value may be set as a remote variable value that can be changed according to the load condition of the premises at that time.

  After the initial value of the cold / hot water flow rate is set and the operation of the cogeneration system is started, the pressure in the steam header 114, the fuel gas flow rate, and the opening degree of the evaporating valve 114b are set as described above. Control is performed.

  As described above, when the pressure in the steam header 114 decreases, the flow rate of the cold / hot water flowing into the heat source device 101 is decreased, so that the once-through boiler 111 is not easily put into an operating state, or the steam header 114 When the internal pressure increases, the flow rate of cold / hot water flowing into the heat source device 101 is increased so that the steam is not easily released from the evaporating valve 114b, thereby improving energy efficiency. Can be easily done.

DESCRIPTION OF SYMBOLS 101 Heat source machine 102 Heat source machine 103 Cold / hot water forward header 104 Cold / hot water return header 105 Cold / hot water load 111 Through-flow boiler 111a Fuel gas flow meter 112 CGS generator 112a Generator power meter 113 Exhaust gas boiler 113a Bypass damper 114 Steam header 114a Pressure gauge 114b Release Steam valve 115 Steam load 121 Control unit 122 Pump

Claims (4)

A cogeneration device having an exhaust gas boiler;
A fuel gas boiler that generates steam by burning fuel gas;
A steam header to which steam generated by the exhaust gas boiler and the fuel gas boiler is input;
A heat source machine to which steam is supplied from the steam header;
A control device for a cogeneration system having
When the pressure of the steam header is lower than a predetermined threshold value, the flow rate of the cold / hot water flowing into the heat source unit is gradually decreased every time the flow rate of the fuel gas supplied to the fuel gas boiler exceeds a predetermined threshold value. While letting
When the pressure of the steam header is higher than a predetermined threshold, every time the opening of the evaporating valve for lowering the pressure of the steam header exceeds a predetermined threshold, cold / hot water flowing into the heat source unit A control device for a cogeneration system, comprising a controller for gradually increasing the flow rate. A control device for a cogeneration system according to claim 1,
The control unit sets an initial value of a flow rate of the cold / hot water flowing into the heat source unit based on an opening degree of a bypass damper that bypasses the exhaust gas flowing into the exhaust gas boiler and power generated by the cogeneration apparatus. A control device for a cogeneration system. A cogeneration device having an exhaust gas boiler;
A fuel gas boiler that generates steam by burning fuel gas;
A steam header to which steam generated by the exhaust gas boiler and the fuel gas boiler is input;
A heat source machine to which steam is supplied from the steam header;
The control unit according to any one of claims 1 to 2,
A cogeneration system characterized by comprising: A cogeneration device having an exhaust gas boiler;
A fuel gas boiler that generates steam by burning fuel gas;
A steam header to which steam generated by the exhaust gas boiler and the fuel gas boiler is input;
A heat source machine to which steam is supplied from the steam header;
A control method for a cogeneration system having
When the pressure of the steam header is lower than a predetermined threshold value, the flow rate of the cold / hot water flowing into the heat source unit is gradually decreased every time the flow rate of the fuel gas supplied to the fuel gas boiler exceeds a predetermined threshold value. While letting
When the pressure of the steam header is higher than a predetermined threshold, every time the opening of the evaporating valve for lowering the pressure of the steam header exceeds a predetermined threshold, cold / hot water flowing into the heat source unit A control method of a cogeneration system characterized by gradually increasing the flow rate.

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