Power plant and method of controlling same

Patent metadata

Field	Value
Publication number	US-10648370-B2
Application number	US-201816013941-A
Country	US
Kind code	B2
Filing date	Jun 21, 2018
Priority date	Aug 9, 2017
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

Disclosed are a power plant that uses a synchronous generator using a working fluid for generation of electric power, and a method of controlling the power plant, the power plant and the control method having an advantage of preventing damage to the power plant during synchronization with an electrical grid. The power plant comprises a pump for compressing a working fluid, a heat exchanger for heat transfer from an external heat source to the working fluid transferred from the pump, and a power turbine generator for generating a rotational force by using the working fluid heated by the heat exchanger, generating electricity using the rotational force, and supplying the electricity to an electrical grid.

First claim

What is claimed is:

1. A power plant comprising:
a pump configured to compress a working fluid;
a heat exchanger apparatus configured to cause heat exchange between the working fluid transferred from the pump and an external heat source;
a power turbine generator configured to generate a rotational force by using the working fluid heated through the heat exchange performed in the heat exchanger apparatus, to generate electricity using the rotational force, and to supply the electricity to an electrical grid, the power turbine generator operating during a first operation session in which synchronization with the electrical grid is performed, during a second operation session in which the power turbine generator operates in synchronization with the electrical grid after the synchronization with the electrical grid is successfully performed through the first operation session, and during a third operation session in which a shut-down operation is performed during the second operation session, the power turbine generator exhibiting an inlet pressure and operating during the second operation session between upper and lower limits of a normal range of the inlet pressure;
a condenser configured to cool the working fluid discharged from the power turbine generator;
a working fluid supply line connected to the heat exchanger apparatus and the power turbine generator at respective ends thereof to provide a flow path from the heat exchanger apparatus to the power turbine generator for the working fluid discharged from the heat exchanger apparatus;
a pressure sensor installed on the working fluid supply line and configured to measure a pressure of the working fluid supplied to the power turbine generator and to output a measurement value indicative of the inlet pressure of the power turbine generator;
a working fluid recovery line connected to the power turbine generator and the condenser at respective ends thereof to provide a flow path from the power turbine generator to the condenser for the working fluid;
a bypass line connected to the working fluid supply line and the working fluid recovery line at respective ends thereof to cause a portion of the working fluid flowing through the working fluid supply line to bypass the power turbine generator and to directly flow to the working fluid recovery line;
a controller comprising a first controller and a second controller;
a first control valve installed on the working fluid supply line and controlled by the first controller to control a flow rate of the working fluid flowing through the working fluid supply line according to a rotational speed of a turbine in the power turbine generator during the first operation session and to control the flow rate of the working fluid flowing through the working fluid supply line according to the measurement value of the pressure sensor during the second operation session; and
a second control valve installed on the bypass line and controlled by the second controller to have an open state to control a flow rate of the working fluid flowing through the bypass line according to the measurement value of the pressure sensor during the first operation session, the flow rate through the second control valve rising during the first operation session,
wherein the first controller is configured to automatically switch from a first mode corresponding to the first operation session in which the first controller controls the first control valve based on the rotational speed of the turbine to a second mode corresponding to the second operation session in which the first controller controls the first control valve based on the inlet pressure of the power turbine generator and is further configured
to perform the second mode by increasing an opening of the first control valve when the measurement value of the pressure sensor reaches the lower limit of the normal range of the inlet pressure, and
to completely close the opening of the first control valve in response to a shut-down command initiating the third operation session, and

wherein the second controller is configured to control the second control valve to have the open state to control the flow rate of the working fluid flowing through the bypass line according to the measurement value of the pressure sensor during the first operation session, the flow rate through the second control valve rising during the first operation session, and is further configured
to change the open state of the second control valve by increasing an opening of the second control valve when the measurement value of the pressure sensor reaches the upper limit of the normal range during the second operation session, and
to gradually increase the open state of the second control valve in response to the shut-down command, the gradual increasing performed according to the measurement value of the pressure sensor.

2. The power plant according to claim 1 , further comprising:
a recuperator installed on the working fluid recovery line and configured to cause heat exchange between the working fluid conveyed through the working fluid recovery line and the working fluid transferred from the pump, thereby cooling the working fluid conveyed through the working fluid recovery line.

3. The power plant according to claim 2 , wherein the heat exchanger apparatus comprises:
a first heat exchanger configured to heat the working fluid transferred from the pump by causing heat exchange between the working fluid transferred from the pump and the external heat source; and
a second heat exchanger configured to heat a portion of the working fluid transferred from the pump, the portion being the working fluid conveyed through the recuperator, by causing heat exchange between the working fluid conveyed through the recuperator and the external heat source.

4. The power plant according to claim 3 , wherein the external heat source is hot exhaust gas, the first heat exchanger and the second heat exchanger are arranged in series and spaced from each other, and the hot exhaust gas sequentially passes through the first heat exchanger and the second heat exchanger to exchange heat with the working fluid.

5. The power plant according to claim 3 , wherein the pump comprises:
a centrifugal pump configured to compress the working fluid conveyed from the condenser for supply of the compressed working fluid; and
an auxiliary turbine coaxially connected to a rotational shaft of the centrifugal pump and configured to generate a rotational force by using the working fluid supplied from the second heat exchanger to rotate the rotational shaft.

6. The power plant according to claim 5 , further comprising a first fluid line connected to an outlet of the auxiliary turbine and the working fluid recovery line at respective ends thereof to provide a flow path from the auxiliary turbine to the working fluid recovery line for the working fluid discharged from the auxiliary turbine.

7. The power plant according to claim 2 , wherein the heat exchanger apparatus comprises:
a first heat exchanger configured to heat a portion of the working fluid transferred from the pump by causing heat exchange between the working fluid conveyed through the recuperator and the external heat source;
a second heat exchanger configured to heat the working fluid transferred from the pump by causing heat exchange between the working fluid transferred from the pump and the external heat source;
a second fluid line connected to the first heat exchanger and the second heat exchanger at respective ends thereof to provide a flow path from the second heat exchanger to the first heat exchanger for the working fluid discharged from the second heat exchanger; and
a third fluid line connected to the pump and the second fluid line at respective ends t

Assignees

• Doosan Heavy Ind & Construction Co Ltd
• Doosan Heavy Ind Constr Co Ltd

Inventors

• Sung Hwa Chang
• Kim Sang Hyeun
• CHA Song Hun

Classifications

• F01K25/103

  Carbon dioxide (F01K25/065 takes precedence) · CPC title

• H02J3/00

  Circuit arrangements for AC mains or AC distribution networks · CPC title

• F01K7/16 Primary

  the engines being only of turbine type (the engines using steam of critical or overcritical pressure F01K7/32; the engines being of extraction or non-condensing type F01K7/34) · CPC title

• F01K13/02 Primary

  Controlling, e.g. stopping or starting · CPC title

• F01K27/00

  Plants for converting heat or fluid energy into mechanical energy, not otherwise provided for · CPC title