JP6778475B2 - Power generation system and power generation method - Google Patents

Description

The present invention relates to a power generation system and a power generation method.

Conventionally, a device that generates electricity by expanding steam in an expander is known. For example, in the apparatus described in Patent Document 1, an evaporator, an expander, and a condenser form one power generation cycle, and a plurality of such power generation cycles are provided. Further, a heating medium shutoff valve and a cooling medium shutoff valve are provided. In this device, the amount of power generation is detected, and the heating medium shutoff valve and the cooling medium shutoff valve are opened and closed based on the detected value of the power generation amount and the heating medium discharge temperature.

Japanese Unexamined Patent Publication No. 2012-202262

By providing a plurality of power generation cycles as in the above-mentioned device, it is possible to cope with a large amount of heat. However, there has never been a power generation system that can respond to fluctuations in the amount of heat. For example, in a turbine design adjusted to 100% of heat, when the amount of heat is reduced to 50%, the torque for operating the generator cannot be obtained and the relative mechanical loss becomes large. In this case, the amount of power generation is significantly reduced.

An object of the present invention is to provide a power generation system and a power generation method capable of sufficiently generating power without lowering the overall efficiency even if the input heat amount fluctuates.

One aspect of the present invention includes a plurality of positive displacement expanders and a plurality of generators connected to each of the plurality of positive displacement expanders, and steam expands in at least one of the plurality of positive displacement expanders. This is a power generation system that generates power, and by controlling the suppression means that can suppress the flow of steam to each of the positive displacement expanders and the suppression means based on the information on the calorific value of the steam, A control unit that adjusts the load factor per unit is provided, and the control unit detects information on the amount of heat of steam, and while operating at least one positive displacement expander, each time the amount of heat changes by a predetermined amount. , changing the rotation speed in each of the positive displacement expander in phased.
In this power generation system, when operating a plurality of positive displacement expanders, the control unit is distributed to the plurality of positive displacement expanders so that the rotation speeds of the plurality of positive displacement expanders are equal. The amount of heat of the steam may be equal.

Another aspect of the present invention uses a power generation system including a plurality of positive displacement expanders and a plurality of generators connected to each of the plurality of positive displacement expanders, and at least one of the plurality of positive displacement expanders. It is a power generation method that generates electricity by expanding steam on a table, and includes a step of adjusting the load factor per unit of a positive displacement expander based on information on the amount of heat of steam, and in that step, the amount of heat of steam. detecting information on, while for operating at least one displacement type expander, each time the amount of heat changes a predetermined amount, changing the rotation speed in each of the positive displacement expander in phased.

According to these power generation systems and power generation methods, a plurality of positive displacement expanders to which generators are connected are provided. The load factor per positive displacement expander is adjusted based on the information on the calorific value of steam. For example, when the amount of input heat decreases, the power generation can be efficiently controlled by increasing the load factor per unit of the positive displacement expander. Further, when the input heat amount increases, the power generation can be efficiently controlled by lowering the load factor per one of the positive displacement expanders. Therefore, even if the input heat amount fluctuates, sufficient power generation can be performed by the required number of positive displacement expanders without lowering the overall efficiency .

In the above power generation system, the plurality of positive displacement expanders are N units, the control unit stores at least (N-1) different threshold values for information on the amount of heat of steam, and the control unit stores steam. When the information on the amount of heat of the above is detected and the detected information exceeds the threshold value of the ath (a is any integer from 1 to (N-1)) from the smaller of the (N-1) thresholds. If it is determined, (a + 1) positive displacement expanders may be operated.

According to this configuration, since the number of operating units is changed stepwise with different (N-1) thresholds as boundaries, more efficient power generation can be performed by a simple determination process.

According to the present invention, even if the amount of heat input fluctuates, sufficient power generation can be performed by a required number of positive displacement expanders without lowering the overall efficiency.

It is a figure which shows the schematic structure of the power generation system which concerns on one Embodiment of this invention. It is a figure which shows the operating state of each generator according to the input heat quantity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

First, the steam power generation system 1 of the present embodiment will be described with reference to FIG. In FIG. 1, the solid line shows the electric circuit, and the broken line shows the steam circuit. The alternate long and short dash line shows the steam circuit. The dashed line shown to be connected to the control unit 30 indicates the control circuit.

As shown in FIG. 1, the steam power generation system 1 is a power generation system that uses high-temperature steam (for example, a pressure of 0.7 to 0.8 MPa and a temperature of about 170 to 180 ° C.) as a heat source to generate power. The steam power generation system 1 includes a first scroll expander 6A, a second scroll expander 6B, a third scroll expander 6C, and three of these (that is, N = 3) first to third scroll expanders 6A to. It includes a first generator 7A, a second generator 7B, and a third generator 7C connected to each of the 6Cs.

The first scroll expander 6A and the first generator 7A rotate their output shafts when steam expands in the first scroll expander 6A, and the first generator 7A generates electricity. The second scroll expander 6B and the second generator 7B rotate their output shafts when steam expands in the second scroll expander 6B, and the second generator 7B generates electricity. The third scroll expander 6C and the third generator 7C rotate the output shaft when steam expands in the third scroll expander 6C, and the third generator 7C generates electricity.

The steam power generation system 1 is provided with a steam line L1, and steam is supplied into the steam line L1 with a predetermined pressure. The steam line L1 is provided with an inlet detector 11 for detecting information on the amount of heat of steam. The information regarding the calorific value of steam is information on any one or more of the flow rate, temperature, and pressure of steam. The inlet detector 11 detects information on the steam supplied to the first to third scroll expanders 6A to 6C. The "line" means a pipe through which a fluid flows.

The steam line L1 is branched into three lines. The first steam supply line L1A is connected to the first scroll expander 6A, the second steam supply line L1B is connected to the second scroll expander 6B, and the third steam supply line L1C is the third scroll expander. It is connected to 6C. The first to third steam supply lines L1A to L1C are provided with first to third solenoid valves 16A to 16C for stopping (cutting off) or suppressing the flow of steam in each line. That is, each of the first to third solenoid valves 16A to 16C can suppress the flow of steam by adjusting the opening degree thereof. Further, each of the first to third solenoid valves 16A to 16C is fully closed to stop the flow of steam. The first to third solenoid valves 16A to 16C correspond to suppressing means capable of suppressing the flow of steam to each of the first to third scroll expanders 6A to 6C.

The first steam discharge line L2A connected to the steam outlet of the first scroll expander 6A, the second steam discharge line L2B connected to the steam outlet of the second scroll expander 6B, and the third scroll expander 6C. It merges with the third steam discharge line L2C connected to the steam outlet portion of the above to form one line, which is discharged to the atmosphere.

Each of the first to third generators 7A to 7C is connected to the inverter 17 via a leak detector, an electromagnetic contactor, or the like. The inverter 17 is connected to a three-phase alternating current (for example, 200 V) commercial power source 21. A load 18 such as an electric motor is connected to the inverter 17.

The steam power generation system 1 includes a control unit 30 that adjusts the load factor per unit of the first to third scroll expanders 6A to 6C by controlling the above-mentioned suppressing means based on the information on the calorific value of steam. ing. The control unit 30 is a computer composed of hardware such as a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and software such as a program stored in the ROM. is there. When the above-mentioned inlet detector 11 detects information on the amount of heat of steam, the detected information is sequentially transmitted to the control unit 30. The control unit 30 acquires information on the amount of heat of steam, and controls opening and closing of the first to third solenoid valves 16A to 16C based on the acquired information. By controlling the opening and closing of the first to third solenoid valves 16A to 16C, the load factor per unit of the first to third scroll expanders 6A to 6C can be adjusted. Further, by controlling the first to third solenoid valves 16A to 16C to be fully closed / fully opened, it is possible to control the number of operating units of the first to third scroll expanders 6A to 6C. In the steam power generation system 1, the number of positive displacement expanders to be operated can be narrowed down in this way.

The control unit 30 stores at least two different ((N-1)) threshold values for information on the calorific value of the steam. The control unit 30 has, for example, two threshold values (here, for example, a first threshold value: 40% and a second threshold value:) for the input heat amount (%) calculated based on the detection result of the inlet detector 11. 70%) is remembered. The input heat quantity (%) is the ratio of the heat quantity actually possessed by the steam to the rated heat quantity of the entire three series. The control unit 30 uses these threshold values for adjusting the load factor or the number of operating units of the first to third scroll expanders 6A to 6C.

Subsequently, the operation method of the steam power generation system 1 (power generation method using the steam power generation system 1) will be described with reference to FIG. The control unit 30 calculates a numerical value corresponding to the above-mentioned threshold value (a numerical value having the same dimension as the threshold value) based on the information regarding the amount of heat of steam transmitted from the inlet detector 11 during the operation of the steam power generation system 1. Here, the control unit 30 calculates the current input heat amount based on the inlet detector 11.

The control unit 30 determines whether the calculated input heat amount exceeds the above-mentioned first threshold value and exceeds the second threshold value. When the control unit 30 determines that the input heat amount is equal to or less than the first threshold value, only the first solenoid valve 16A is opened, and the other solenoid valves are closed. As a result, only the first scroll expander 6A, which is the first series, is in the operating state. When the control unit 30 determines that the input heat amount exceeds the first threshold value, the control unit 30 further opens the second solenoid valve 16B. As a result, the second scroll expander 6B, which is the second series, is also in the operating state, and a total of two series are in the operating state. When the control unit 30 determines that the input heat amount also exceeds the second threshold value, the control unit 30 further opens the third solenoid valve 16C. As a result, the third scroll expander 6C, which is the third series, is also in the operating state, and a total of three series are in the operating state.

As shown in FIG. 2, the number of operating units is switched at the boundary between the first threshold value of 40% and the second threshold value of 70% . The amount of heat of steam distributed to the plurality of scroll expanders operating at the same time is equalized, and therefore the rotation speeds of the plurality of scroll expanders are equal. (In the figure, it can be read that the rotation speeds of the plurality of scroll expanders are equal (the lines overlap) by making the line types different.) In the operation method shown in FIG. 2, the input heat amount is 10. % Each time it changes, the number of rotations in each scroll expander is changed step by step.

In this way, the control unit 30 detects the information regarding the calorific value of the steam, and determines that the detected information exceeds the first threshold value (the first threshold value from the smallest) among the 2 (N-1) threshold values. If so, two positive displacement expanders are operated. When the control unit 30 determines that the detected information on the amount of heat exceeds the second threshold value (the second threshold value from the smallest) of the two threshold values, the control unit 30 operates three positive displacement expanders.

According to the steam power generation system 1 described above and the power generation method using the same, a plurality of positive displacement expanders 6A to 6C to which the first to third generators 7A to 7C are connected are provided. The control unit 30 controls the opening and closing of the first to third solenoid valves 16A to 16C based on the information on the calorific value of the steam, thereby adjusting the load factor per unit of the positive displacement expanders 6A to 6C. To. For example, when the amount of input heat decreases, the power generation can be efficiently controlled by increasing the load factor per unit of the positive displacement expander. Further, when the input heat amount increases, the power generation can be efficiently controlled by lowering the load factor per one of the positive displacement expanders. Therefore, even if the input heat amount fluctuates, sufficient power generation can be performed by the required number of positive displacement expanders 6A to 6C without lowering the overall efficiency.

In particular, the steam power generation system 1 can handle a wide range of heat from a small amount to a large amount of heat, and exerts a particularly advantageous effect when the amount of heat fluctuates greatly. Conventionally, there are few small power generation systems that use steam as a heat source, but the steam power generation system 1 in which a plurality of positive displacement expanders and generators are arranged can support a wide range of scales from small to large.

The control unit 30 detects information on the calorific value of steam, which is a heat source medium, and the detected information sets the ath threshold value (a is an integer from 1 to 2) from the smaller of the two threshold values. When it is determined that the amount exceeds the limit, (a + 1) positive displacement expanders are operated. According to this configuration, since the number of operating units is changed stepwise with two different threshold values as boundaries, more efficient power generation can be performed by a simple determination process.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the number of series (number) of positive displacement expanders may be 4 or more. Even if a large number of series are provided, according to the control of the present invention, it is possible to easily and efficiently generate power with an optimum number of operating units according to the amount of heat of steam as a heat source medium.

The threshold value stored in the control unit 30 is not limited to one less than the number of series. The threshold may be higher or lower. The suppressing means is not limited to the solenoid valve. Pumps may be provided independently in each series, and distribution may be suppressed / stopped by adjusting the flow rate of the pumps or turning them on and off. A three-way valve may be used at the branch point.

The positive displacement inflator is not limited to the scroll inflator. Instead of the first to third scroll expanders 6A to 6C, other positive displacement expanders may be used. For example, various inflators such as a screw inflator, a claw inflator, a reciprocating inflator, and a roots inflator may be used.

1 ... Steam power generation system (power generation system), 6A to 6C ... 1st to 3rd scroll expanders (positive displacement expander), 7A to 7C ... 1st to 3rd generators, 16A to 16C ... 1st to 3rd Solenoid valve (suppressing means), 30 ... Control unit.

Claims (4)

A plurality of positive displacement expanders and a plurality of generators connected to each of the plurality of positive displacement expanders are provided, and power is generated by expanding steam in at least one of the plurality of positive displacement expanders. It ’s a power generation system,
Suppressing means capable of suppressing the flow of the steam to each of the positive displacement expanders,
A control unit for adjusting the load factor per unit of the positive displacement expander by controlling the suppressing means based on the information on the calorific value of the steam is provided.
The control unit detects information on the calorific value of the steam, and while operating the at least one positive displacement expander, each time the calorific value changes by a predetermined amount, the rotation speed in each of the positive displacement expanders the staged changing, the power generation system. When the plurality of positive displacement expanders are operated, the control unit measures the amount of heat of the steam distributed to the plurality of positive displacement expanders so that the rotation speeds of the plurality of positive displacement expanders are equal. The power generation system according to claim 1, wherein the power generation systems are equal to each other. The plurality of positive displacement expanders are N units.
The control unit stores at least different (N-1) thresholds for information about the calorific value of the steam.
The control unit detects information on the calorific value of the steam, and the detected information is any of the (N-1) thresholds from the smallest to the ath (a is 1 to (N-1)). The power generation system according to claim 1 or 2, wherein (a + 1) units of the positive displacement expander are operated when it is determined that the threshold value (the integer) is exceeded. Using a power generation system including a plurality of positive displacement expanders and a plurality of generators connected to each of the plurality of positive displacement expanders, steam expands in at least one of the plurality of positive displacement expanders. It is a power generation method that generates electricity by
Including a step of adjusting the load factor per unit of the positive displacement expander based on the information on the calorific value of the steam.
In the step, while the information regarding the calorific value of the steam is detected and the at least one positive displacement expander is operated, each time the calorific value changes by a predetermined amount, the rotation speed of each of the positive displacement expanders is determined. It staged changing, power generation method.

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