Vertical type once-through heat recovery steam generator and combined power generation system including

Patent metadata

Field	Value
Publication number	US-12203393-B2
Application number	US-202318358213-A
Country	US
Kind code	B2
Filing date	Jul 25, 2023
Priority date	Dec 15, 2022
Publication date	Jan 21, 2025
Grant date	Jan 21, 2025

Abstract

A vertical type once-through heat recovery steam generator (HRSG) capable of improving operational stability during rapid startup and lifetime of a steam turbine while reducing environmental pollution caused by emissions, and a combined power generation system including the HRSG are provided. The HRSG includes a medium-pressure section including a medium-pressure side desuperheater installed at the rear of a medium-pressure superheater to lower the temperature of the steam supplied to a medium-pressure steam turbine, and a high-pressure section including a high-pressure side desuperheater installed at the rear of a high-pressure superheater to lower the temperature of the steam supplied to a high-pressure steam turbine.

First claim

The invention claimed is:

1. A vertical type once-through heat recovery steam generator (HRSG) comprising:
a low-pressure section comprising a condensate preheater configured to heat feedwater through heat exchange with combustion gases and supply the heated feedwater to a low-pressure drum, a low-pressure evaporator configured to heat feedwater stored in the low-pressure drum and convert the feedwater to steam, and a low-pressure superheater configured to heat the steam separated from the feedwater in the low-pressure drum and supply the heated steam to a low-pressure steam turbine;
a medium-pressure section comprising a medium-pressure economizer configured to receive at least a portion of the feedwater heated by the condensate preheater, heat the feedwater through heat exchange with the combustion gases, and supply the heated feedwater to a medium-pressure drum, a medium-pressure evaporator configured to heat the feedwater stored in the medium-pressure drum and convert the heated feedwater to steam, a medium-pressure superheater configured to heat the steam separated from the feedwater in the medium-pressure drum and supply the heated steam to a medium-pressure steam turbine, and a medium-pressure side desuperheater installed at the rear of the medium-pressure superheater to lower the temperature of the steam supplied to a medium-pressure steam turbine; and
a high-pressure section comprising a high-pressure economizer configured to receive at least a portion of the feedwater heated by the condensate preheater and heat the feedwater through heat exchange with the combustion gases, a multi-stage once-through evaporator configured to heat the feedwater heated by the high-pressure economizer through heat exchange with the combustion gases, a high-pressure superheater configured to heat the steam heated by the multi-stage once-through evaporator and supply the heated steam to a high-pressure steam turbine, and a high-pressure side desuperheater installed at the rear of the high-pressure superheater to lower the temperature of the steam supplied to the high-pressure steam turbine,
wherein the medium-pressure side desuperheater comprises a first medium-pressure desuperheater and a second medium-pressure desuperheater, and wherein the medium-pressure section comprises a first medium-pressure reheater, the first medium-pressure desuperheater, a second medium-pressure reheater, and the second medium-pressure desuperheater sequentially between the medium-pressure superheater and the medium-pressure steam turbine such that the steam heated in the medium-pressure superheater is supplied to the medium-pressure steam turbine through the first medium-pressure reheater, the first medium-pressure desuperheater, the second medium-pressure reheater, and the second medium-pressure desuperheater, consecutively,
wherein the second medium-pressure desuperheater is deactivated after completion of a rapid startup process of the vertical type once-through HRSG while the first medium-pressure desuperheater remains active after the completion of the rapid startup process of the vertical type once-through HRSG, and,
wherein the multi-stage once-through evaporator comprises:
an inlet part which receives feedwater and includes a small-diameter tube portion; and
a heat transfer tube having a first heat transfer tube part and a second heat transfer tube part, wherein a front end of the first heat transfer tube part is connected to the small-diameter tube portion and the first heat transfer tube part has a first inner diameter larger than an inner diameter of the small-diameter tube portion, and wherein a front end of the second heat transfer tube part is connected to the first heat transfer tube part and the second heat transfer tube part has a second inner diameter larger than the first inner diameter of the first heat transfer tube part, and
wherein a first tapered part is disposed between the small-diameter tube portion and the first heat transfer tube part, and a second tapered part is disposed between the first heat transfer tube part and the second heat transfer tube part, and
wherein each of the first and second tapered parts has an inner diameter that increases gradually and gently toward a rear end thereof.

2. The vertical type once-through HRSG according to claim 1 , wherein the low-pressure section comprises a condensate preheater bypass configured to allow a portion of the feedwater to bypass the condensate preheater and flow directly to the low-pressure drum.

3. The vertical type once-through HRSG according to claim 1 , wherein a feedwater line between the medium-pressure drum and the medium-pressure superheater is supplied with steam heated by an external heater.

4. The vertical type once-through HRSG according to claim 3 , wherein the external heater is configured to generate steam through heat exchange of a portion of the feedwater with high-temperature compressed air compressed from a compressor of a gas turbine and supply the generated steam to the feedwater line.

5. The vertical type once-through HRSG according to claim 1 , wherein the high-pressure superheater comprises first and second high-pressure superheaters and the high-pressure side desuperheater comprises first high-pressure desuperheater and second high-pressure desuperheater, wherein the first high-pressure superheater, the first high-pressure desuperheater, the second high-pressure superheater, and the second high-pressure desuperheater are disposed sequentially between the multi-stage once-through evaporator and the high-pressure steam turbine such that the steam heated in the multi-stage once-through evaporator is supplied to the high-pressure steam turbine through the first high-pressure superheater, the first high-pressure desuperheater, the second high-pressure superheater, and the second high-pressure desuperheater, consecutively.

6. The vertical type once-through HRSG according to claim 5 , wherein a steam separator is disposed between the multi-stage once-through evaporator and the first high-pressure superheater to separate steam contained in the feedwater having flowed through the multi-stage once-through evaporator.

7. The vertical type once-through HRSG according to claim 1 , wherein a portion of the feedwater heated in the high-pressure economizer is supplied to a fuel preheater of a combustor through a fuel-preheating feedwater line.

8. The vertical type once-through HRSG according to claim 1 , wherein the heat transfer tube comprises a plurality of heat transfer tube parts having different inner diameters, each increasing stepwise toward the rear end of the heat transfer tube.

9. A combined power generation system comprising:
a gas turbine including a compressor configured to suck and compress external air, a combustor configured to mix fuel with the compressed air and combust the mixture, and a turbine rotated by combustion gases discharged from the combustor to generate a rotational force;
a heat recovery steam generator (HRSG) configured to heat feedwater and generate steam by using the combustion gases discharged from the gas turbine; and a steam turbine in which blades are rotated by the steam generated from the HRSG to generate a rotational force, the HRSG comprising:
a low-pressure section comprising a condensate preheater configured to heat feedwater through heat exchange with the combustion gases and supply the heated feedwater to a low-pressure drum, a low-pressure evaporator configured to heat feedwater stored in the low-pressure drum and convert the feedwater to steam, and a low-pressure superheater configured to heat the steam separated from the feedwater in the low-pressure drum and supply the heated steam to a low-pressure steam turbine;
a medium-pressure section

Assignees

• Doosan Enerbility Co Ltd

Inventors

• Seon Chil Yeong
• Kim Tae Woo
• Kim Jin Il

Classifications

• F02C7/224

  Heating fuel before feeding to the burner · CPC title

• F02C7/141

  of working fluid · CPC title

• F22B37/47

  responsive to abnormal temperature, e.g. actuated by fusible plugs · CPC title

• F22G1/02

  with heat supply by hot flue gases from the furnace of the steam boiler · CPC title

• F22B11/02

  the fire tubes being in upright arrangement · CPC title