JP2007315281A - Small once-through boiler power generation system and its operation control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small once-through boiler power generation system in which a plurality of small once-through boilers and a plurality of steam turbines utilizing steam produced therein to generate electric power are installed, capable of performing efficient operation corresponding to a demand fluctuation of a steam flow amount, and to provide its operation control method. <P>SOLUTION: A steam supply flow path 6 connecting the small once-through boiler 2 to a steam utilizing process 5 is parted into a plurality of branch flow paths 6a, 6b, 6c. An power generation unit 3 consists of a detection part consisting of a steam superheater 7, a flowmeter, and a pressure gage, an emergency shut-off valve, a flow control valve, a steam turbine 8 incident to a generator, and a pressure reducing valve, a bypass flow path 16 bypassing the emergency shut-off valve, the flow control valve and the steam turbine 8 incidental to the generator and connected to the branch flow path, and a bypass valve provided in the bypass flow path 16, which are mounted in each of the plurality of branch flow paths. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a small once-through boiler power generation system in which a plurality of small once-through boilers and steam turbines are installed, and a small once-through boiler power generation system capable of efficient operation in response to fluctuations in demand for steam flow, and an operation control method thereof. About.

  Various proposals have been made for controlling the number of systems for supplying steam by installing a plurality of small once-through boilers. A method for controlling the number of once-through boilers according to the conventional example will be described below with reference to FIGS. FIG. 7 is a schematic explanatory view showing one embodiment of a method for controlling the number of once-through boilers according to the conventional example, and FIG. 8 is a boiler installation situation diagram showing one embodiment of the steam supply system provided with the backup boiler according to the conventional example. Show.

  First, in FIG. 7, the method for controlling the number of once-through boilers according to the conventional example is that a plurality of once-through boilers 21 are installed, the steam pipes of the respective boilers 21 are assembled and connected to the steam accumulator 22, and the output unit of the steam accumulator 22. In the multi-can installation system in which the steam flow detection device 23 is provided between the pipes of the steam header 25 and the pressure detection device 24 is provided in the middle of the pipe or the steam header 25, signals from the steam flow detection device 23 and the pressure detection device 24 are provided. Thus, the combustion and stop of each boiler 21 are controlled (see Patent Document 1).

  According to the method for controlling the number of once-through boilers according to the above-described conventional example, the steam accumulator 22 can be installed to prevent a rapid change in pressure with respect to a rapid change in steam load, thereby enabling a stable steam supply. Further, by determining the number of combustions of the boiler 21 based on the signal from the steam flow rate detection device 23 and determining the combustion pattern based on the signal from the pressure detection device 24, the appropriate number of combustions and the combustion state of the boiler 21 according to the steam load fluctuation are determined. It is determined.

  Next, the steam supply system provided with the backup boiler according to the conventional example shown in FIG. 8 is the main steam supply apparatus 34 and the steam supply system provided with a plurality of backup boilers 31. The operation control device 32 that calculates the number of backup boilers 31 corresponding to the amount of steam supplied by the engine and sends a preheating command to the backup boilers 31 for the calculated number is provided (see Patent Document 2). .

  According to the steam supply system provided with the backup boiler according to this conventional example, it is possible to prevent the steam pressure from being lowered due to the emergency stop of the main steam supply device 34 and affecting the amount of steam used. However, the inventions according to the above-described conventional examples all relate to a method for controlling the number of multiple once-through boilers and a steam supply system, and do not describe any power generation system.

  In view of such a situation, the present inventors have already proposed a power generation system, a cogeneration system, and a power generation method. The technique according to this conventional example will be described below with reference to FIG. FIG. 9 is a piping diagram showing the overall configuration of the cogeneration system according to the embodiment of the conventional example.

This power generation system and cogeneration system according to the conventional example is a power generation system 40 that generates power using steam used in the steam utilization facility 44, and the steam is generated by a small once-through boiler 41, and A steam superheater 42 that superheats steam generated by the small once-through boiler 41, a steam turbine 44 that is driven by superheated steam that is superheated by the steam superheater 42, and power generation is performed as the steam turbine 44 is driven. And a generator 46 (see Patent Document 3).
Japanese Patent Laid-Open No. 5-288302 JP 2002-310403 A Japanese Patent Application No. 2005-155808

  However, the small-capacity steam turbine 44 such as the radial turbine employed in the conventional example has a high rated efficiency of about 80%, but the problem is that the efficiency is extremely lowered under partial load conditions. For example, when the supplied steam flow becomes half of the rated flow, the efficiency of this steam turbine is reduced to 40%.

  Accordingly, an object of the present invention is to change the demand of steam flow in a small once-through boiler power generation system in which a plurality of small once-through boilers and steam turbines for generating electricity using steam generated by the small once-through boiler are installed. Is to provide a small once-through boiler power generation system capable of efficient operation and an operation control method thereof.

  In order to achieve the above object, the means adopted by the small once-through boiler power generation system according to claim 1 of the present invention includes a plurality of small once-through boilers for generating steam to be supplied to the steam utilization process, The present invention relates to a small once-through boiler power generation system including a power generation unit for generating power using the steam before the steam is supplied to the steam utilization process and an operation control device for controlling the operation of the power generation unit. is there.

  In this small once-through boiler power generation system, the steam supply flow path connecting the small once-through boiler and the steam utilization process is branched into a plurality of branch flow paths, and the power generation unit is connected to the plurality of branch flow paths. Each includes a detector comprising a steam superheater, a flow meter and a pressure gauge, an emergency shut-off valve, a flow control valve, a steam turbine and a pressure reducing valve attached to the generator, and the emergency shut-off valve, the flow control valve and the steam attached to the generator A bypass passage connected to the branch passage by bypassing the turbine and a bypass valve provided in the bypass passage are interposed.

  The means adopted by the operation control method of the small once-through boiler power generation system according to claim 2 of the present invention is the small once-through boiler power generation system according to claim 1, wherein the operation control device is provided with steam required from a steam utilization process. Is input as a control signal, and the number of power generation units to be operated is determined according to the steam demand flow rate.

  The operation control method of the small once-through boiler power generation system according to claim 3 of the present invention is the operation control method of the small once-through boiler power generation system according to claim 2, wherein the steam flow rate and the steam turbine of each of the power generation units are The outlet pressure is detected, and the flow rate control valve of each power generation unit is controlled based on the detection signal.

  The means adopted by the operation control method of the small once-through boiler power generation system according to claim 4 of the present invention is the operation control method of the small once-through boiler power generation system according to claim 2 or 3, in the steam demand flow rate of the steam utilization process. Accordingly, the flow control valve of each power generation unit is controlled according to the following steps.

(1) When the steam demand flow rate is equal to or lower than the rated steam flow rate of the power generation unit, only the first power generation unit is operated in the normal operation method among the plurality of power generation units,
(2) When the steam demand flow rate approaches the rated steam flow rate, the warm-up operation of the second power generation unit among the power generation units is started,
(3) When the steam demand flow rate becomes equal to or higher than the rated steam flow rate, the second power generation units are operated in parallel. The first power generation unit is rated operation and the second power generation unit is partially loaded. Control the flow control valve of the unit,
(4) When the steam demand flow rate approaches twice the rated steam flow rate, the warm-up operation of the third power generation unit is started,
(5) Hereinafter, the steps corresponding to (2) to (4) are repeated until the steam demand flow approaches the total rated steam flow of all power generation units,
(6) When the steam demand flow exceeds the total rated steam flow of all power generation units, all the power generation units are operated in parallel, but only one power generation unit is set to partial load operation and all other power generation units are rated. The flow control valve of each power generation unit is controlled to operate.

  According to the small once-through boiler power generation system according to claim 1 of the present invention, the steam supply flow path connecting the small once-through boiler and the steam utilization process is branched into a plurality of branch flow paths, and the power generation unit includes: In each of the plurality of branch flow paths, a detection unit comprising a steam superheater, a flow meter and a pressure gauge, an emergency shut-off valve, a flow control valve, a steam turbine and a pressure reducing valve attached to a generator, the emergency shut-off valve, and a flow control Since a bypass passage connected to the branch passage bypassing the steam turbine attached to the valve and the generator and a bypass valve provided in the bypass passage are interposed, demand for steam to be used The number of power generation units can be selected according to the flow rate.

According to the operation control method of the small once-through boiler power generation system according to claim 2 of the present invention,
Since the steam demand flow rate required from the steam utilization process is input to the operation control device as a control signal, the number of power generation units to be operated can be determined according to the steam demand flow rate. Depending on the situation, automatic operation with high power generation efficiency becomes possible.

  Furthermore, according to the operation control method of the small once-through boiler power generation system according to claim 3 of the present invention, the steam flow rate and the steam turbine outlet pressure of each of the power generation units are detected, and based on this detection signal, Since the flow rate control valve is controlled, it is possible to automatically operate the steam turbine so that the operating state of the steam turbine matches the fluctuation in the steam demand.

  Furthermore, according to the operation control method of the small once-through boiler power generation system according to claim 4 of the present invention, the number of power generation units to be rated is determined according to the steam demand flow rate of the steam utilization process, and the partial load operation is performed. Since the power generation unit is at most one unit, automatic operation with high power generation efficiency corresponding to fluctuations in steam demand has been realized.

  A small once-through boiler power generation system according to Embodiment 1 of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic explanatory diagram for explaining an outline of a small once-through boiler power generation system according to an embodiment of the present invention. FIG. 2 is a diagram for explaining a power generation unit of the small once-through boiler power generation system according to an embodiment of the present invention. It is a systematic diagram.

  First, an outline of a small once-through boiler power generation system according to an embodiment of the present invention will be described below with reference to FIG. The small once-through boiler power generation system 1 includes six small once-through boilers 2 for generating steam to be supplied to the steam utilization process 5 and the generated steam before the steam utilization process 4 is supplied. A power generation unit 3 for generating power using steam and an operation control device 4 for controlling the operation thereof are provided.

  The steam generated by the six small once-through boilers 2 is once integrated into the steam supply flow path 6 for supply to the steam utilization process 5. And the steam supply flow path 6 which connects the said small once-through boiler 2 and the steam utilization process 5 is three branch flow paths, ie, the 1st branch flow path 6a, the 2nd branch flow path 6b, and the 3rd branch flow path. 6c, and the three power generation units 3 in which the three branch flow paths 6a, 6b, and 6c are provided with devices such as the steam superheater 7 and the steam turbine 8, respectively. A first power generation unit 3a, a second power generation unit 3b, and a third power generation unit 3c are provided.

  One unit of the power generation unit 3 can supply 3 tons / h (3000 kg / h) of steam and 100 kW of power, and the power generation unit 3 as a whole has a steam volume of 9 tons / h (9000 kg / h). 300 kW of power can be supplied, but from 1 unit up to 3 units can be operated depending on the steam demand.

  Next, the power generation unit will be described in more detail with reference to FIG. Since each of the power generation units, that is, the first power generation unit 3a, the second power generation unit 3b, and the third power generation unit 3c have the same configuration, the configuration of the first power generation unit 3a will be described below as a representative example. That is, the first power generation unit 3a includes, in order from the upstream side, a steam superheater 7a, a detection unit including a flow meter 9a and a pressure gauge 10a, an emergency shut-off valve 12a, a flow control valve 13a, a steam turbine 8a attached to the generator, and a pressure reduction. A valve 14a is interposed. The said apparatus which comprises the 1st electric power generation unit 3a is demonstrated still in detail below.

  The steam (saturated steam) generated by the small once-through boiler is branched into the first branch passage 6a constituting the first power generation unit 3a through the steam supply passage 6, and is first introduced into the steam superheater 7a. The steam superheater 7a is configured to superheat the saturated steam. Since the flow rate of the flowing steam is about 3 tons / h, the steam superheater 7a having a capacity of, for example, 106 kW is used. The maximum operating pressure of the steam superheater 7a is 0.98 MPa, and the maximum operating temperature is 230 ° C.

  The steam superheated by the steam superheater 7a is detected by the detection unit composed of the flow meter 9a and the pressure gauge 10a for the steam flow rate and the steam pressure flowing through the first branch flow path 6a. The detection unit may further include a thermometer 11a for detecting the steam temperature. Further, the detection signal detected by such a detection unit is connected online (not shown) so as to be transmitted to the operation control device 4.

  Next, the emergency shut-off valve 12a is used to completely shut off the first branch flow path 6a and stop supplying superheated steam to the steam turbine 8a on the downstream side, and the operation control device 4 It is comprised so that control is possible. The flow rate adjusting valve 13a is for adjusting the flow rate of the superheated steam flowing through the first branch flow path 6a, and is configured so that the valve opening degree can be controlled by the operation control device 4.

  And the steam turbine 8a is comprised by the radial turbine, and the superheated steam is introduce | transduced by connecting the suction inlet to the said 1st branch flow path 6a. A generator (not shown) is connected to the output shaft of the steam turbine 8a through a speed reducer, and the generator converts rotational energy into electrical energy. If the generator is of a high speed type, the speed reducer can be omitted.

  The outlet side of the steam turbine 8a is connected to the first branch flow path 6a. A pressure reducing valve 14a is interposed in the first branch flow path 6a on the outlet side. The pressure reducing valve 14a is for maintaining the outlet pressure (back pressure) of the steam turbine. By providing the pressure reducing valve 14a, the steam discharged from the steam turbine 8a is expanded and decompressed. Alternatively, the outlet pressure of the steam turbine 8a is detected by a pressure gauge 15a, and this detection signal is sent to the operation control device 4, and the pressure reduction degree of the pressure reducing valve 14a is adjusted by a command from the operation control device 4. The outlet pressure (back pressure) can be controlled.

  Further, the first branch flow path 6a is provided with a bypass flow path 16a connected to the branch flow path 6a by bypassing the emergency shutoff valve 12a, the flow rate adjusting valve 13a and the steam turbine 8a. A bypass valve 17a is interposed in the bypass channel 16a. The bypass passage 16a is a bypass circuit for opening the bypass valve 17a so that steam can be supplied to the steam utilization process when the steam turbine 8a is urgently stopped for some reason.

  The first branch channel 6 a is integrated with the steam supply channel 6 again, and steam is supplied to the steam utilization process 5. The operation control device 4 controls the operation of the small once-through boiler 2 and, as described above, monitors the pressure, flow rate, and temperature of the superheated steam supplied to the steam turbine 8a, and opens the flow control valve 8a. And the pressure reduction degree of the pressure reducing valve 14a are controlled. The first power generation unit 3a is configured as described above. Regarding the second power generation unit 3b and the third power generation unit 3c, the description of the power generation unit is made by replacing the end a of the reference numerals in the above description with b and c, respectively. Therefore, description of these power generation unit configurations is omitted.

Next, the operation control method of the small once-through boiler power generation system according to the embodiment of the present invention will be described below with reference to FIG. Typical rated operating conditions for each of the steam turbines 8 used in the power generation system 1 are as follows.
Steam temperature: 216 ° C
Steam turbine inlet pressure: 0.75 MPa
Steam turbine outlet pressure: 0.25 MPa
Steam flow rate: 3 tons / h

  When the steam flow rate is 3 ton / h or more and the steam pressure ratio (= turbine inlet pressure / outlet pressure) is 3 or more, the output of the steam turbine 8 exceeds the rated output, so control of the steam flow rate and the steam pressure is important. . In the normal operation control method of the small once-through boiler power generation system according to the embodiment of the present invention, first, at the start of operation, the emergency valve of each power generation unit 3 is closed, the steam superheater 7 is preheated, Is supplied to the bypass passage 16 to warm up the steam turbine 8.

  Next, when the induction generator of the steam turbine 8 is connected to each power generation unit 3, the generator starts to rotate at the rated rotational speed. When the emergency shut-off valve is opened and the opening of the flow control valve is gradually increased, the induction generator shifts from the motoring mode to the power generation mode and begins to generate power. Up to this point, the operation method of the normal power generation system has been described.

  In the operation control method of the small once-through boiler power generation system 1 according to the embodiment of the present invention, the demand flow rate of steam required from the steam utilization process 5 is input to the operation control device 4 as a control signal. The control signal may be an external signal input to the operation control device 4 in real time from the steam utilization process 5 side, or may be based on a command programmed in the operation control device 4 in advance. Then, in the steps as described below, the number of the power generation units 3 to be operated is determined according to the demand for the steam flow rate, and the operation is controlled.

(1) When the steam demand flow rate is 2.5 tons / h or less, one unit of the power generation unit 3, for example, the first power generation unit 3a is operated by a normal operation method.
(2) When the steam demand flow rate is 2.5 tons / h or more, the power generation unit 3
The second unit, for example, the warm-up operation of the second power generation unit 3b is started.
(3) When the steam demand flow rate is 3 ton / h or more, the second power generation unit 3b is operated in parallel. The first power generation unit 3a is rated operation (3 ton / h), and the second power generation unit 3b is a partial operation. The flow rate control valves of the power generation units 3a and 3b are controlled so that the load operation is performed.
(4) When the steam demand flow rate is 5.5 tons / h or more, the third unit of the power generation unit 3, that is, the warm-up operation of the third power generation unit 3c is started.
(5) When the steam demand flow rate is 6 tons / h or more, all the power generation units 3a, 3b and 3c of the three units are operated in parallel. Among them, the first power generation unit 3a and the second power generation The unit 3b controls the flow rate adjustment valve of each power generation unit so that the rated operation (3 ton / h × 2) and the remaining third power generation unit 3c are in partial load operation.

Even when the number of the power generation units is four or more, similarly to the above, operation control may be performed according to the following steps (5) and (6) instead of the above step (5).
(5) Hereinafter, until the steam demand flow rate approaches the total rated flow rate of all the power generation units, (2
) To (4) are repeated,
(6) When the steam demand flow rate exceeds the total rated flow rate of all power generation units, all the power generation units are operated in parallel, but only one power generation unit is set to partial load operation, and all other power generation units are all operated. The flow control valve of each power generation unit is controlled so as to perform rated operation.

  As described above, in the operation control method of the small once-through boiler power generation system according to the present invention, the steam flow rate is detected by the flow meter provided in each of the power generation units, and the outlet pressure is detected by the outlet pressure gauge provided on the steam turbine outlet side. Then, based on these detection signals, the operation is controlled as described above by the flow rate adjusting valve of each power generation unit.

<Example>
Next, an embodiment of an operation control method for a small once-through boiler power generation system according to the present invention will be described below with reference to FIGS. FIG. 3 is an explanatory diagram showing an example of a steam demand pattern of a steam utilization process according to an embodiment of the present invention. FIG. 4 is a diagram for explaining a method for determining the number of operating units of a small once-through boiler power generation system for the steam demand pattern A shown in FIG. FIG. 5 is an explanatory diagram for explaining a method of determining the number of operating units of the small once-through boiler power generation system for the steam demand pattern B shown in FIG.

  The steam demand pattern of the steam utilization process will be described below as an example for the pattern A having a large daytime fluctuation and the pattern B having a small daytime fluctuation, as shown by a solid line in FIG. In this pattern A, there is a maximum steam demand of 10 tons / h during the day, but there is no night demand. In pattern B, there is a maximum steam demand of 6 tons / h, but there is no significant difference between day and night.

  First, the case where the steam demand pattern of the steam utilization process is pattern A will be described with reference to FIG. In this case, since there is a demand for a maximum amount of steam of 10 tons / h in the daytime, according to the above procedure, the power generation unit is operated by three units in the daytime, and a maximum amount of steam of 9 tons / h and 300 kW. Can be supplied. 4 and 5, the shaded portion indicates the rated operation, and the shaded portion indicates the partial load operation.

  That is, in FIG. 4, in the early morning and evening hours when the steam demand is 3 ton / h or less, partial load operation is performed only with the first power generation unit 3a of the first unit, and the steam demand exceeds 3 ton / h. In the time zone before and after the start of work and before and after the end of work less than ton / h, the first power generation unit 3a is set to rated operation and the second power generation unit 3b of the second unit is set to partial load operation. Furthermore, in the time zone from 11 o'clock to 15 o'clock when the steam demand exceeds 6 tons / h and less than 9 tons / h, the two units of power generation units 3a and 3b are operated at rated operation. The power generation unit 3c is assumed to be partially loaded.

  On the other hand, when the steam demand pattern of the steam utilization process is pattern B, as shown in FIG. 5, in the time zone from midnight to early morning when the steam demand is 5 tons / h, the rated operation and the first operation by the first power generation unit 3a are performed. In a time zone other than the above, which corresponds to partial load operation by two power generation units 3b and a steam demand of 6 tons / h, the first power generation unit 3a and the second power generation unit 3b are operated only by rated operation, and 6 tons / H steam amount and 200 kW power can be supplied.

  As described above, the operation control method for each power generation unit is to perform the partial load operation of the insufficient steam demand with another unit while securing the number of units to be rated as much as possible within the range of the steam demand. It is preferable to cover with. The number of rated operation units of the power generation unit is determined for fluctuations in steam demand, and the demand of less than 3 tons / h is handled by partial load operation of the other power generation unit. This is preferable in terms of efficiency of the small once-through boiler power generation unit according to the invention.

  Next, the effect of such a small once-through boiler power generation system and its operation control method according to the present invention will be described with reference to FIG. FIG. 6 is an explanatory diagram for explaining the effect of the operation control method of the small once-through boiler power generation system according to the present invention. In FIG. 6, the solid line shows a case where a power generation unit of 3 units (rated steam flow rate 3 ton / h × 3 units) is used, only one of them is in partial load operation, and other units are rated operation according to the steam flow rate. It shows the power generation output. Moreover, the broken line has shown the electric power generation output with respect to the steam flow at the time of driving | running only by partial load operation | movement using the 1 unit power generation unit which consists of a steam turbine of rated steam flow 9 ton / h.

  That is, when indicated by the solid line, each power generation unit is supplied under conditions where the flow rate of steam supplied to the power generation system is an integral multiple of 3 tons / h, 3 tons / h, 6 tons / h, and 9 tons / h. Since the steam turbine provided in 1 operates at the highest efficiency point at a rated flow rate of 3 tons / h, it is possible to generate power close to 100 kW, 200 kW and 300 kW.

  On the other hand, in the case of the broken line, since the partial load operation is performed over the entire steam flow rate, the power generation efficiency is poor, and as a result, the power generation output is extremely low. Only the rated flow rate of the steam turbine reaches 9 ton / h, and the same power generation output 300 kW as above is obtained. In this case, even when three units of power generation units each having a power generation unit with a rated flow rate of 3 ton / h are used and the steam flow rate is divided and supplied equally to each unit, the same power generation output as this broken line is obtained. .

  As described above, according to the small once-through boiler power generation system according to the present invention, the steam supply passage connecting the small once-through boiler and the steam utilization process is branched into a plurality of branch passages, and the power generation unit is In each of the plurality of branch channels, a detection unit comprising a steam superheater, a flow meter and a pressure gauge, an emergency shut-off valve, a flow control valve, a steam turbine and a pressure reducing valve attached to a generator, the emergency shut-off valve, and a flow rate Since the bypass passage connected to the branch passage bypassing the control valve and the steam turbine attached to the generator and the bypass valve provided in the bypass passage are interposed, The number of power generation units to be operated can be selected according to the demand flow rate.

  Further, the demand flow of steam required from the steam utilization process can be input to the operation control device as a control signal, and the number of power generation units to be operated can be determined according to the demand flow of steam. It is possible to automatically respond to fluctuations in flow rate.

  The present invention provides a plurality of small once-through boilers for generating steam to be supplied to a steam utilization process, and generates electricity using the steam before the generated steam is supplied to the steam utilization process. It is suitable to apply to a small once-through boiler power generation system equipped with a power generation unit for the purpose, but is not limited thereto, and a power generation unit for generating power using a normal boiler and steam generated by this boiler It can also be applied to a power generation system equipped with

It is an outline explanatory view for explaining an outline of a small once-through boiler power generation system concerning an embodiment of the invention. It is a distribution diagram for explaining a power generation unit of a small once-through boiler power generation system concerning an embodiment of the invention. It is explanatory drawing which shows the example of a steam demand pattern of the steam utilization process which concerns on the Example of this invention. It is explanatory drawing for demonstrating the determination method of the number of operation units of the small once-through boiler power generation system with respect to the steam demand pattern A shown in FIG. It is explanatory drawing for demonstrating the determination method of the number of operation units of the small once-through boiler power generation system with respect to the steam demand pattern B shown in FIG. It is explanatory drawing for demonstrating the effect of the operation control method of the small once-through boiler electric power generation system which concerns on this invention. It is a schematic explanatory drawing which shows one Example of the number control method of the once-through boiler which concerns on a prior art example. The boiler installation condition figure which shows one Example of the steam supply system which provided the boiler for backup which concerns on a prior art example is shown. It is a piping system diagram which shows the whole structure of the cogeneration system which concerns on embodiment of a prior art example.

Explanation of symbols

1: Small once-through boiler power generation system, 2: Small once-through boiler,
3: power generation unit, 3a: first power generation unit, 3b: second power generation unit,
3c: third power generation unit,
4: Operation control device, 5: Steam utilization process,
6: Steam supply channel, 6a: First branch channel, 6b: Second branch channel,
6c: third branch flow path,
7, 7a, 7b, 7c: Steam superheater,
8, 8a, 8b, 8c: steam turbine,
9a, 9b, 9c: flow meters 10a, 10b, 10c: pressure gauges,
11a, 11b, 11c: thermometer,
12a, 12b, 12c: emergency shutoff valve,
13a, 13b, 13c: flow control valves,
14a, 14b, 14c: pressure reducing valves,
15a, 15b, 15c: pressure gauge,
16, 16a, 16b, 16c: bypass flow path,
17a, 17b, 17c: Bypass valve

Claims (4)

  A plurality of small once-through boilers for generating steam to be supplied to the steam utilization process; and a power generation unit for generating electricity using the steam before the generated steam is supplied to the steam utilization process; In the small once-through boiler power generation system provided with an operation control device for controlling these operations, the steam supply flow path connecting the small once-through boiler and the steam utilization process is branched into a plurality of branch paths, The power generation unit includes a detector comprising a steam superheater, a flow meter and a pressure gauge, an emergency shutoff valve, a flow control valve, a steam turbine and a pressure reducing valve attached to the generator, A bypass passage connected to the branch passage by bypassing the shutoff valve, the flow control valve and the steam turbine attached to the generator, and a bypass provided in the bypass passage Small once-through boiler power generation system characterized by comprising been interposed and.   2. The small once-through boiler power generation system according to claim 1, wherein the demand flow rate of steam required from a steam utilization process is input to the operation control device as a control signal, and the number of power generation units that are operated according to the steam demand flow rate is set. The operation control method of the small once-through boiler power generation system characterized by determining.   3. The operation control method for a small once-through boiler power generation system according to claim 2, wherein a steam flow rate and a steam turbine outlet pressure of each of the power generation units are detected, and a flow rate control valve of each power generation unit is controlled based on the detection signal. An operation control method for a small once-through boiler power generation system. 4. The operation control method for a small once-through boiler power generation system according to claim 2 or 3, wherein the flow rate control valve of each power generation unit is controlled according to the following steps according to the steam demand flow rate of the steam utilization process. Operation control method for small once-through boiler power generation system.
(1) When the steam demand flow rate is equal to or lower than the rated steam flow rate of the power generation unit, only the first power generation unit is operated in the normal operation method among the plurality of power generation units,
(2) When the steam demand flow rate approaches the rated steam flow rate, the warm-up operation of the second power generation unit among the power generation units is started,
(3) When the steam demand flow rate becomes equal to or higher than the rated steam flow rate, the second power generation units are operated in parallel. The first power generation unit is rated operation and the second power generation unit is partially loaded. Control the flow control valve of the unit,
(4) When the steam demand flow rate approaches twice the rated steam flow rate, the warm-up operation of the third power generation unit is started,
(5) Hereinafter, the steps corresponding to (2) to (4) are repeated until the steam demand flow approaches the total rated steam flow of all power generation units,
(6) When the steam demand flow exceeds the total rated steam flow of all power generation units, all the power generation units are operated in parallel, but only one power generation unit is set to partial load operation and all other power generation units are rated. The flow control valve of each power generation unit is controlled to operate.

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