Steam turbine plant and operation method, combined cycle plant and operation method

1. A steam turbine plant comprising:

a turbine;

a main steam supply line that supplies main steam to the turbine;

a control valve provided in the main steam supply line; and

a first auxiliary steam supply line that supplies auxiliary steam to the turbine via the main steam supply line on a downstream side of the control valve,

wherein a drain discharge line is provided between the turbine and the control valve in the main steam supply line, and the first auxiliary steam supply line is connected to the drain discharge line at a connecting portion, and

wherein drain valves are provided in the drain discharge line on an upstream side and a downstream side of the connecting portion, respectively.

2. The steam turbine plant according to claim 1 ,

wherein the drain discharge line is connected to a condenser.

3. The steam turbine plant according to claim 1 ,

wherein the turbine includes

a high and medium-pressure turbine of which one end portion in an axial direction is provided with a high-pressure turbine portion and of which the other end portion is provided with a medium-pressure turbine portion, and

a low-pressure turbine disposed coaxially with the high and medium-pressure turbine, and

wherein the first auxiliary steam supply line is disposed to supply the auxiliary steam to the high-pressure turbine portion and the medium-pressure turbine portion.

4. The steam turbine plant according to claim 1 ,

wherein a second auxiliary steam supply line is provided which supplies the auxiliary steam to the turbine via the control valve and the main steam supply line.

5. The steam turbine plant according to claim 1 , further comprising:

a control device which performs control such that the auxiliary steam is supplied from the first auxiliary steam supply line and the main steam supply line to the turbine before a drive timing of a main steam generation source.

6. The steam turbine plant according to claim 5 ,

wherein the control device performs control such that the auxiliary steam is supplied from the first auxiliary steam supply line and the main steam supply line to the turbine after vacuum processing of a condenser is completed.

7. The steam turbine plant according to claim 5 ,

wherein the control device performs control such that a supply of the auxiliary steam to the turbine is stopped when or before a condition for supplying steam to the turbine is satisfied.

8. The steam turbine plant according to claim 5 ,

wherein the control device performs control such that a supply of the auxiliary steam to the turbine is stopped after a load is applied to the main steam generation source.

9. The steam turbine plant according to claim 5 ,

wherein the drain valves include a first drain valve which is provided in the drain discharge line on a turbine side of the connecting portion, and a second drain valve which is provided in the drain discharge line on an opposite side of the connecting portion with respect to the first drain valve, and

wherein the control device performs control such that the auxiliary steam is supplied to a second drain valve side of the drain discharge line before the drive timing of the main steam generation source, and is then supplied to a first drain valve side of the drain discharge line.

10. The steam turbine plant according to claim 9 ,

wherein a second auxiliary steam supply line is provided which supplies the auxiliary steam to the turbine via the control valve and the main steam supply line, and the control device performs control such that when the auxiliary steam is supplied to the turbine, the auxiliary steam is supplied from the second auxiliary steam supply line to the control valve.

11. A method for operating the steam turbine plant according to claim 1 , the method comprising:

supplying auxiliary steam to the turbine from the downstream side of the control valve provided in the main steam supply line before a drive timing of a main steam generation source;

stopping a supply of the auxiliary steam to the turbine when or before a condition for supplying steam to the turbine is satisfied; and

starting a supply of main steam to the turbine when the condition for supplying the steam to the turbine is satisfied after the supply of the auxiliary steam to the turbine is stopped.

12. A combined cycle plant comprising:

a gas turbine including a compressor, a combustor, and a turbine;

a heat recovery steam generator that uses waste heat of flue gas from the gas turbine to generate steam; and

the steam turbine plant according to claim 1 that is driven by the steam generated by the heat recovery steam generator.

13. A combined cycle plant comprising:

a gas turbine including a compressor, a combustor, and a turbine;

a heat recovery steam generator that uses waste heat of flue gas from the gas turbine to generate steam; and

the steam turbine plant according to claim 5 that is driven by the steam generated by the heat recovery steam generator,

wherein a drive timing of a main steam generation source is a steam generation start timing of the heat recovery steam generator, which is determined by ignition of the gas turbine.

14. A method for operating the combined cycle plant according to claim 12 , the method comprising:

supplying auxiliary steam to the turbine from the downstream side of the control valve provided in the main steam supply line before a steam generation timing of the heat recovery steam generator, which is determined by ignition of the gas turbine;

stopping a supply of the auxiliary steam to the turbine when or before a condition for supplying the steam to the turbine is satisfied; and

starting a supply of main steam to the turbine when the condition for supplying the steam to the turbine is satisfied after the supply of the auxiliary steam to the turbine is stopped.

15. A steam turbine plant comprising:

a first turbine and a second turbine;

a first main steam supply line that supplies main steam to the first turbine, and a second main steam supply line that supplies main steam to the second turbine;

a first control valve provided in the first main steam supply line and a second control valve provided in the second main steam supply line; and

one first auxiliary steam supply line that supplies auxiliary steam to the first and second turbines, wherein the one first auxiliary steam supply line merges into the first main steam supply line on a downstream side of the first control valve and merges into the second main steam supply line on a downstream side of the second control valve,

wherein the first control valve is a closest valve to the first and second turbines within the first main steam supply line, and the second control valve is a closest valve to the first and second turbines within the second main steam supply line.