JP5522969B2 - Exhaust gas energy recovery device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas energy recovery device for an internal combustion engine that recovers the energy of exhaust gas discharged from the internal combustion engine as electric energy.

Conventionally, various devices have been proposed as a device for recovering the energy of exhaust gas discharged from a private power generation facility using a reciprocating internal combustion engine such as a diesel engine or a gas engine.
For example, exhaust gas that has passed through a supercharger from a reciprocating internal combustion engine is sent to a heat exchanger, heat is exchanged with water to generate steam, and the generated steam is supplied to hot water, heating, or other processes that require heat. In addition, an energy plant is known in which steam generated by a heat exchanger is also supplied to a reciprocating internal combustion engine so that the thermal energy of exhaust gas can be recovered without waste (see Patent Document 1).

In addition, the rotating shaft of an exhaust turbine driven by the exhaust gas of the internal combustion engine is connected to a generator via a clutch, and a capacitor is connected to the generator, so that the energy of the exhaust gas is electrically transmitted between the exhaust turbine and the generator. It is known that the exhaust energy is effectively used over the entire operating range of the engine by converting the energy into energy and storing the electric energy in a capacitor (see Patent Document 2).
Further, the turbocharger is rotated by the exhaust gas discharged from the internal combustion engine, the exhaust turbine is further rotated by the exhaust gas discharged from the turbocharger, and the generator and the pump are driven by the energy recovered by the exhaust turbine. It is known that the surplus energy of the exhaust gas is effectively recovered regardless of the load fluctuation by driving or reducing as the power of the main shaft of the internal combustion engine (see Patent Document 3).

  Furthermore, an exhaust turbine having a generator is provided in the exhaust pipe of the engine, and a temperature sensor for detecting the temperature of the exhaust gas provided at each of an inlet portion and an outlet portion of the exhaust turbine, and a speed for detecting the rotational speed of the exhaust turbine Sensors to reduce the load on the generator so that the exhaust turbine speed can be obtained in an operating state where the exhaust gas supplied to the exhaust turbine can obtain the maximum output from the exhaust turbine shaft. An apparatus that is controlled to improve the efficiency of exhaust gas recovery is known (see Patent Document 4).

JP 2003-239810 A JP 61-4814 A Japanese Patent Laid-Open No. Sho 62-13722 Japanese Patent Publication No. 4-28886

  A part of the exhaust gas energy of a conventional reciprocating internal combustion engine for power generation is recovered by a turbocharger provided in the exhaust manifold, and in order to recover further energy, steam is generated by an exhaust gas heat exchanger or is discharged to an exhaust turbine. A method of recovering heat by generating electricity with a connected generator is used. This is because the exhaust gas of a reciprocating internal combustion engine is considered to recover energy while leaving kinetic energy enough to be released to the atmosphere through the flue, but the conditions of the exhaust flue differ depending on the plant and are optimal. Energy recovery could be difficult.

  In addition, an exhaust gas energy recovery device using an exhaust turbine or a heat exchanger is a factor for increasing the resistance of an exhaust gas system for a reciprocating internal combustion engine, and the exhaust gas resistance increases as the energy is recovered by the exhaust gas energy device. Become. If the total resistance value of the exhaust gas system from the internal combustion engine to the open air part at the exhaust flue outlet exceeds the allowable value of the reciprocating internal combustion engine, the temperature of the exhaust gas becomes high and the internal combustion engine or the exhaust turbine is abnormal. It had caused the problem of.

  The present invention has been made in order to solve the above-described problems in an equipment for recovering exhaust gas energy of an internal combustion engine with an exhaust turbine installed in an exhaust flue. An object of the present invention is to obtain an exhaust gas energy recovery device for an internal combustion engine that can recover the exhaust gas energy as electric energy most efficiently within a range in which the internal combustion engine does not cause problems.

An exhaust gas energy recovery device for an internal combustion engine according to the present invention is installed in a three-phase AC generator mechanically connected to an internal combustion engine that converts reciprocating motion into rotational motion and generates electric power, and an exhaust flue of the internal combustion engine. , An exhaust turbine that converts kinetic energy of exhaust gas discharged from the internal combustion engine into rotational energy, a generator that is mechanically connected to the exhaust turbine via a speed reducer, and electrical energy obtained by the generator Is converted to a commercial frequency, a temperature sensor is provided near the exhaust gas outlet of the internal combustion engine and detects the temperature of the exhaust gas discharged from the internal combustion engine, and the exhaust gas temperature is detected based on the exhaust gas temperature detected by the temperature sensor. and a control device for variably controlling the angle of attack of the turbine of the turbine blades, the control device includes a setting value predetermined exhaust gas temperature detected by the temperature sensor When the comparison is made and the exhaust gas temperature is higher than the set value, the angle of attack of the turbine blades of the exhaust turbine is decreased. When the exhaust gas temperature is lower than the set value, the angle of attack of the turbine blades of the exhaust turbine is reduced. Is intended to increase .

  According to the present invention, the exhaust gas resistance of the exhaust turbine can be reduced by monitoring the exhaust gas temperature of the internal combustion engine with the temperature sensor and variably controlling the angle of attack of the turbine blades of the exhaust turbine based on the exhaust gas temperature. Therefore, the exhaust gas temperature of the internal combustion engine can be controlled to remain within the stable operation range of the internal combustion engine, and the internal combustion engine can increase the energy recovery amount of the exhaust turbine without causing problems such as abnormal exhaust temperature. it can.

1 is an overall configuration diagram of an exhaust gas energy recovery device showing Embodiment 1 of the present invention. It is a flowchart which shows operation | movement of the exhaust gas energy recovery apparatus in Embodiment 1 of this invention.

Embodiment 1 FIG.
Hereinafter, an exhaust gas energy recovery device for an internal combustion engine according to Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 1 is an overall configuration diagram of an exhaust gas energy recovery device showing Embodiment 1 of the present invention. In FIG. 1, a reciprocating internal combustion engine 1 such as a diesel engine or a gas engine changes its reciprocating motion to rotational motion. Then, the three-phase alternating current generator 2 mechanically connected to the reciprocating internal combustion engine 1 is rotated, and the three-phase alternating current generator 2 converts the rotational energy into electric energy to generate electric power. Electric power from the three-phase AC generator 2 is used as a private power generation facility. Exhaust gas from the reciprocating internal combustion engine 1 is guided to the exhaust flue 4 via the exhaust manifold 3, and exhaust gas from the reciprocating internal combustion engine 1 is released from the exhaust flue 4 to the atmosphere.

An exhaust turbine 5 is installed in the vicinity of the outlet portion (atmospheric discharge portion) of the exhaust flue 4, and the exhaust turbine 5 is composed of a casing and turbine blades rotatably disposed in the casing. The exhaust turbine 5 introduces the exhaust gas of the reciprocating internal combustion engine 1 into the casing to rotationally drive the turbine blades, and converts the kinetic energy of the exhaust gas into rotational energy by the turbine blades. The exhaust turbine 5 has a mechanism that can vary the angle of attack of the turbine blades.
The rotating shaft of the generator 6 is mechanically connected to a rotating shaft integral with the turbine blades of the exhaust turbine 5 via a speed reducer (not shown). The generator 6 converts the rotational energy recovered by the exhaust turbine 5 into electric energy. And convert. The electric energy obtained by the rotation of the generator 6 is converted into a commercial frequency by the inverter 7, and the output is used for other electric loads.

  A temperature sensor 8 for detecting the temperature of the exhaust gas discharged from the reciprocating internal combustion engine 1 is provided in the vicinity of the exhaust gas outlet of the reciprocating internal combustion engine 1, and the exhaust gas temperature signal detected by the temperature sensor 8 is a control device. 9 is input. The control device 9 compares the exhaust gas temperature signal input from the temperature sensor 8 with a predetermined set value, and exhausts the exhaust gas temperature from the reciprocating internal combustion engine 1 within the target range. A control signal for variably controlling the angle of attack of the turbine blades of the turbine 5 is output to the exhaust turbine 5.

As means for variably controlling the angle of attack of the turbine blades of the exhaust turbine 5, an angle-of-attack control signal is sent from the control device 9 to the exhaust turbine 5, and for example, the motor and gears provided in the exhaust turbine 5 are controlled to control the turbine blades. Change the angle of attack.
The predetermined set value set by the control device 9 is a temperature value at which the exhaust gas temperature of the reciprocating internal combustion engine 1 remains within the stable operation region of the reciprocating internal combustion engine 1.

Next, the operation in the overall configuration diagram of the present invention will be described based on the flowchart shown in FIG.
Step ST1 starts when the reciprocating internal combustion engine 1 is started and electric energy is supplied by the three-phase AC generator 2 to operate as an energy plant.
In step ST2, the reciprocating internal combustion engine 1 is operated at a rated speed with the start of electric energy supply of the energy plant. When the reciprocating internal combustion engine 1 is started, the angle of attack of the turbine blades of the exhaust turbine 5 is an angle of attack that minimizes the resistance of the exhaust gas system. The angle of attack that minimizes the gas resistance is an angle that reduces the area where the turbine blade contacts the exhaust gas.

In step ST3, when the reciprocating internal combustion engine 1 operates and supplies energy to the plant, the exhaust gas is discharged to the atmosphere through the exhaust flue 4. Thereafter, the angle of attack of the turbine blades of the exhaust turbine 5 installed in the exhaust flue 4 is increased, and the area where the turbine blades are in contact with the exhaust gas is increased. Increasing the angle of attack of the turbine blade inevitably increases the gas resistance.
Increasing the angle of attack of the turbine blades of the exhaust turbine 5 is performed by changing the angle of attack of the turbine blades of the exhaust turbine 5 according to the angle of attack control signal output from the control device 9.

In step ST4, the kinetic energy of the exhaust gas is converted into rotational energy of the exhaust turbine 5, the rotational energy of the exhaust turbine 5 is converted into electrical energy of the generator 6, and the electrical energy of the generator 6 is converted to a commercial frequency by the inverter 7. The power is converted and recovered as electric power.
In step ST5, the exhaust gas temperature of the reciprocating internal combustion engine 1 during operation is always detected by the temperature sensor 8, and is the exhaust gas temperature detected by the temperature sensor 8 by the control device 9 greater than a predetermined set value? Perform a comparison operation.

  In step ST5, when the exhaust gas temperature is lower than a preset set value (exhaust gas temperature range lower limit value) as a result of the comparison calculation of the control device 9, the control device 9 returns to step ST3 and the control device 9 performs exhaust. For the purpose of increasing the amount of kinetic energy recovered by the turbine 5, a control signal for increasing the angle of attack of the turbine blades of the exhaust turbine 5 is sent to the exhaust turbine 5. Thus, the control signal for increasing the angle of attack is sent until the exhaust gas temperature falls within the exhaust gas temperature setting range.

On the other hand, when the exhaust gas temperature is higher than a preset set value (exhaust gas temperature range upper limit value) as a result of the comparison calculation of the control device 9 in step ST5 (YES), the process proceeds to step ST6, where the control device 9 In order to reduce the amount of kinetic energy recovered by the turbine 5, a control signal for reducing the angle of attack of the turbine blades of the exhaust turbine 5 is sent to the exhaust turbine 5.
If the angle of attack of the turbine blades of the exhaust turbine 5 is reduced, the area where the turbine blades are in contact with the exhaust gas is reduced, inevitably the gas resistance is reduced, and the temperature of the exhaust gas discharged from the reciprocating internal combustion engine 1 is lowered. .

In step ST7, the exhaust gas temperature of the reciprocating internal combustion engine 1 during operation is always detected by the temperature sensor 8, and is the exhaust gas temperature detected by the temperature sensor 8 by the control device 9 smaller than a predetermined set value? Perform a comparison operation.
In step ST7, when the exhaust gas temperature is higher than a preset set value (exhaust gas temperature range lower limit value) as a result of the comparison calculation of the control device 9 (NO), the process returns to step ST6, and the control device 9 For the purpose of reducing the amount of kinetic energy recovered by 5, a control signal for reducing the angle of attack of the turbine blades of the exhaust turbine 5 is sent to the exhaust turbine 5. The operation in step ST6 is as described above.

On the other hand, when the exhaust gas temperature is lower than a preset set value (exhaust gas temperature range upper limit value) as a result of the comparison calculation of the control device 9 in step ST7 (YES), the process proceeds to step ST8, and the reciprocating operation during operation The exhaust gas temperature of the internal combustion engine 1 maintains the state constantly monitored by the temperature sensor 8 and returns to the original state.
Although the reciprocating internal combustion engine 1 has been described above as the internal combustion engine, the present invention is not limited to this.

  As described above, according to the present invention, the exhaust gas temperature of the internal combustion engine 1 is constantly monitored by the temperature sensor 8, and the angle of attack of the turbine blades of the exhaust turbine 5 is controlled based on the exhaust gas temperature. The amount of energy recovered by 5 is controlled by the control device 9 within a range in which an abnormality in the exhaust gas temperature and the like does not occur.

1: Reciprocating internal combustion engine 2: Three-phase AC generator 3: Exhaust manifold 4: Exhaust flue 5: Exhaust turbine 6: Generator 7: Inverter 8: Temperature sensor 9: Control device

Claims (1)

A three-phase AC generator mechanically connected to an internal combustion engine that converts reciprocating motion into rotational motion and generating electric power, and kinetic energy of exhaust gas that is installed in the exhaust flue of the internal combustion engine and exhausted from the internal combustion engine An exhaust turbine that converts the energy into rotational energy, a generator that is mechanically connected to the exhaust turbine via a speed reducer, an inverter that converts electrical energy obtained by the generator into a commercial frequency, and the internal combustion engine A temperature sensor for detecting the temperature of exhaust gas exhausted from the internal combustion engine and an angle of attack of the turbine blades of the exhaust turbine are variable based on the exhaust gas temperature detected by the temperature sensor. A control device for controlling,
The control device compares the exhaust gas temperature detected by the temperature sensor with a predetermined set value, and reduces the angle of attack of the turbine blades of the exhaust turbine when the exhaust gas temperature is higher than the set value. When the exhaust gas temperature is lower than a set value, the exhaust gas energy recovery device for an internal combustion engine is configured to increase the angle of attack of the turbine blades of the exhaust turbine .

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