Steam power plant, modification method and operation method of steam power plant

1. A steam power plant comprising:

a first steam power plant having a boiler which generates steam, a high-pressure turbine which is driven with the steam that the boiler generates, a first reheat line which supplies the steam which is exhausted or extracted from the high-pressure turbine to the boiler, a first feed water heater to which part of the steam which is exhausted or extracted from the high-pressure turbine is supplied, and a high-pressure extraction steam line which supplies the part of the steam which is exhausted or extracted from the high-pressure turbine to the first feed water heater;

a second steam power plant having a boiler which generates steam, a high-pressure turbine which is driven with the steam that the boiler generates, a first reheat line which supplies the steam which is exhausted or extracted from the high-pressure turbine to the boiler, a first feed water heater to which part of the steam which is exhausted or extracted from the high-pressure turbine is supplied, and a high-pressure extraction steam line which supplies the part of the steam which is exhausted or extracted from the high-pressure turbine to the first feed water heater; and

an inter-unit connected extraction steam line which connects the high-pressure extraction steam line of the first steam power plant with the high-pressure extraction steam line of the second steam power plant.

2. The steam power plant according to claim 1 , wherein the inter-unit connected extraction steam line has an inter-unit connected extraction steam valve which controls a flow rate of extraction steam.

3. The steam power plant according to claim 1 ,

wherein the first steam power plant has a condenser which returns the steam to condensed water, a deaerator, and a condensate system which supplies the condensed water which is discharged from the condenser to the deaerator,

the second steam power plant has a condenser which returns the steam to condensed water, a deaerator, and a condensate system which supplies the condensed water which is discharged from the condenser to the deaerator, the steam power plant further comprising:

an inter-unit connected condensate system which connects the condensate system of the first steam power plant with the condensate system of the second steam power plant.

4. The steam power plant according to claim 3 , wherein the inter-unit connected condensate system has an inter-unit connected condensate valve which controls a flow rate of the condensed water.

5. The steam power plant according to claim 1 , wherein the high-pressure extraction steam line has a high-pressure extraction steam valve which controls a flow rate of extraction steam.

6. A modification method of a steam power plant which has

a first steam power plant having a boiler which generates steam, a high-pressure turbine which is driven with the steam that the boiler generates, a first reheat line which supplies the steam which is exhausted or extracted from the high-pressure turbine to the boiler, a first feed water heater to which part of the steam which is exhausted or extracted from the high-pressure turbine is suppled, and a high-pressure extraction steam line which supplies the part of the steam which is exhausted or extracted from the high-pressure turbine to the first feed water heater, and

a second steam power plant having a boiler which generates steam, a high-pressure turbine which is driven with the steam that the boiler generates, a first reheat line which supplies the steam which is exhausted or extracted from the high-pressure turbine to the boiler, a first feed water heater to which part of the steam which is exhausted or extracted from the high-pressure turbine is supplied, and a high-pressure extraction steam line which supplies the part of the steam which is exhausted or extracted from the high-pressure turbine to the first feed water heater, the modification method comprising the step of:

installing an inter-unit connected extraction steam line which connects the high-pressure extraction steam line of the first steam power plant with the high-pressure extraction steam line of the second steam power plant.

7. The modification method of the steam power plant according to claim 6 , further comprising the step of installing an inter-unit connected extraction steam valve which controls a flow rate of extraction steam in the inter-unit connected extraction steam line.

8. An operation method of a steam power plant which has

a first steam power plant having a boiler which generates steam, a high-pressure turbine which is driven with the steam that the boiler generates, a first reheat line which supplies the steam which is exhausted or extracted from the high-pressure turbine to the boiler, a first feed water heater to which part of the steam which is exhausted or extracted from the high-pressure turbine is supplied, and a high-pressure extraction steam line which supplies the part of the steam which is exhausted or extracted from the high-pressure turbine to the first feed water heater, and

a second steam power plant having a boiler which generates steam, a high-pressure turbine which is driven with the steam that the boiler generates, a first reheat line which supplies the steam which is exhausted or extracted from the high-pressure turbine to the boiler, a first feed water heater to which part of the steam which is exhausted or extracted from the high-pressure turbine is suppled, and a high-pressure extraction steam line which supplies the part of the steam which is exhausted or extracted from the high-pressure turbine to the first feed water heater, the operation method comprising the step of:

supplying part of the steam from the high-pressure extraction steam line of the first steam power plant to the high-pressure extraction steam line of the second steam power plant in a case of operating the first steam power plant under a high load and operating the second steam power plant under a low load.