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CCPP with Over Load Valve for Peaking Operation

IP.com Disclosure Number: IPCOM000222067D
Publication Date: 2012-Sep-18
Document File: 4 page(s) / 186K

Publishing Venue

The IP.com Prior Art Database

Related People

Hongtao Li: INVENTOR [+3]

Abstract

The main objective of the present invention is to provide a CCPP with high peak load capacity at high efficiency without impairing the base load efficiency. The essence of the invention is a CCPP plant with peaking steam for power augmentation, including steam from supplementary firing, or / and from external such as steam produced from solar field, using at least one OLV (overload valve) and a steam line to introduce a steam flow into a steam turbine downstream of the first stage of the steam turbine. The steam turbine itself is also modified to allow introduction of steam downstream of the first stage.

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This is the abbreviated version, containing approximately 50% of the total text.

Page 01 of 4

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B12/116-0

CCPP with Over Load Valve for Peaking Operation

In certain markets it is required that a CCPP (combined cycle power plant) can provide large power augmentation of about 10%-20% or higher of the plant net base load power output. Further, in an ISCC (integrated solar combined cycle)

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requires CCPP being able to operate at peaking load to take all the steam produced from solar field when it is available.

Typical CCPP design solutions consider the live steam pressure margin for the supplemental peaking steam from either internal such as supplementary firing (SF)

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or/and external such as steam from solar field, with Steam Turbine in sliding

pressure operation.

The base load and part load steam turbine live steam pressure without steam from SF or solar field will be lower than the allowed operating pressure due to this

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preserved pressure margin. A CCPP with about 500MW power output, considering 10% net power output to be provided by supplementary firing or by steam from soloar field at peak operation, the requested live steam pressure design margin may result in a substantial drop of live steam pressure at base load and correspondingly to a plant performance (power and efficiency) drop that can be up

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to 0.5%.

In alternative solutions a bypass of the supplemental peaking steam or part of the supplemental peaking steam to a reheat line (hot or cold reheat line), has been suggested. These the base load performance of the plant, but reduce the peak load performance.

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SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a CCPP with high peak load capacity at high efficiency without impairing the base load efficiency.

30

The essence of the invention is a CCPP plant with peaking steam for power augmentation, including steam from supplementary firing, or / and from external


Page 02 of 4

B12/116-0

such as steam produced from solar field, using at least one OLV (overload valve) and a steam line to introduce a steam flow into a steam turbine downstream of the first stage of the steam turbine. The steam turbine itself is also modified to allow introduction of steam downstream of the first stage.

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In one embodiment an OLV can handle up to additional 18% of a base load steam flow, and the steam turbine can correspondingly produce additional 15% of steam turbine power output (the difference is due to the pressure loss of throttling). This provides approximately 5% of additional plant net power output of the CCPP.

In a further embodiment, two HP (high pressure) OLVs in are arranged in sequence with supply lines to introduce supplemental steam into different HP flow path locations thus adding more peaking capacity.

In one embodiment an OLV can be arranged in an intermediate pressure steam line with and a steam line to introduce a steam flow into an intermediate pressure steam turbine downstream of the first stage of the intermediate pressure steam turbine.

In addition to the above described OLVs,...