SU916768A1 - Method of keeping steam turbine power plant in standby state - Google Patents

Description

The invention relates to a power system and can be used in thermal power plants to ensure long-term operation of steam-turbine generator sets in the motor mode.

Known methods of preserving in reserve a steam turbine generator installation by transferring the generator to the engine mode and supplying steam to the flow part of the turbine to maintain the temperature state of its elements at an acceptable level.

Shut-off valves are closed and steam is fed through the chambers of regenerative sampling to the last stages of high and low pressure cylinders, to the low-pressure cylinder steam inlet to prevent inadmissible heating of the turbine stages, and to the front end seal to prevent inadmissible cooling of hot sections of the flow part [1] ·

In these methods, it is not possible to prevent significant cooling of the high-pressure cylinder and the steam inlet for a sufficiently long period of time in the engine mode, which limits the reliability and maneuverability of the installation.

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The closest to the proposed technical essence and the achieved result is a method of storing the steam turbine generator set in reserve by transferring the generator to the motor mode, ⁵ supplying fresh steam to the high pressure cylinder of the turbine through its stop and control valves, determining the steam consumption values necessary to prevent unacceptable heating low pressure cylinder and inadmissible cooling of the high pressure cylinder, and the effect on the non-pressure valve of the main steam valve for neighing flow supplied steam. Maintaining said flow rate is performed in accordance with the temperature state rate of ¹⁵ low pressure cylinder [2].

The disadvantage of this method is the reduced maneuverability of the installation, since it is not possible for a long time 20 to maintain the temperature state of the high pressure cylinder at an acceptable

level

The purpose of the invention is to increase the maneuverability and efficiency of the installation.

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To achieve this goal, the steam consumption values needed to prevent unacceptable heating of the low pressure cylinder and unacceptable cooling of the high pressure cylinder are compared, and act on the bypass valve to the highest of these values, the turbine control valves being maintained in the fully open position.

FIG. I shows a diagram of the device that implements the proposed method; in fig. 2 - the dependence of the magnitude of the steam flow rate, steam, necessary to prevent unacceptable heating of the low pressure cylinder from the pressure P _to in the condenser; in fig. 3 - dependence of the value of 0 ₂ steam consumption required to prevent unacceptable cooling. high pressure cylinder, from the time of the expected operation of the installation in the motor mode according to the dispatch schedule of the electric load.

The plant contains a turbine with high 1, medium 2 and low 3 cylinders and a generator 4. On the fresh steam line in front of the turbine, there is a main steam valve 5 with a bypass valve 6, a stop valve 7 and 8 regulating valves. The line of fresh steam through the valve body 9 is connected to the front end seal 10 of the cylinder 1 high pressure. In the exhaust part 11 of the low-pressure cylinder 3 a cooling device 12 is installed, to which cooling water is supplied via line 13. In the exhaust part 11 there is a sensor 14 for measuring the pressure in the condenser, and in the last stages of the low-pressure cylinder 3 and in the vicinity of the steam inlet of the high-pressure cylinder 1 there are sensors 15 and 16 for measuring the temperature of the metal.

The method is as follows.

The bypass valve 6 of the main steam valve 5 is opened. The shut-off member 9 is opened on the steam supply line to the front end seal 10. The cooling device 12 of the exhaust part 11 of the low-pressure cylinder 3 is turned on. Close the main steam valve 5. Fully open the control valves 8 of the turbine. Measure the pressure P _to in the condenser using the sensor 14.

Using the dependence Ο _Ι = _ί (Ρ _κ ) (Fig. 2), determine the amount of steam consumption O), necessary to prevent unacceptable heating of the low pressure cylinder 3. Knowing the estimated operating time of the unit in the engine mode 7, determined by the dispatch schedule, find the value of the steam consumption O ₂ necessary to prevent unacceptable cooling of the high pressure cylinder 1 using the dependence O ₂ = 'p (T)

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in fig. 3. Compare the values found O and C ₂ .

Acting on the bypass valve 6 of the main steam valve 5, set the amount of steam through the turbine5 well, equal to the larger of the values of C ₍ and C ₂ .

Heating of the last stages of the low pressure cylinder occurs due to friction loss and ventilation, which, as various studies show, for ₁₀ specific geometry of the flow part depends on the steam flow and pressure in the condenser. To obtain the dependence O = (P) on one of the turbines of this type, a special series of experiments is carried out: at different pressures in the condenser, it is defined. they divide the minimum value of steam consumption, which ensures the permissible level of metal temperature at the periphery of the last-stage guide vanes, measured using the sensor 15 installed here.

The cooling of the casing of the high pressure cylinder in the steam inlet zone for a particular turbine design depends on the operating time in the engine mode and on the steam flow through the turbine. For po15 radiation depending Ο ₂ = ί (T) on one of the turbines of this type also carry out a series of experiments in which, for different times of operation in the engine mode is the quantity of steam consumption O ₂ provides ₃₀ present the desired temperature level in the steam input zone controlled at sensor assistance 16.

Examples of the indicated dependences О ₁ = ί (Рк) and О 2 = φ (ΐ) for turbine-type Т — 50

E5 130 is shown in FIG. 2 and 3. In FIG. 3 marked 1p _st - the temperature of the lower part of the high-pressure cylinder in the zone of the regulating stage For other types of turbines, these dependencies may differ somewhat from ₄₀ .

When the unit is operating in motor mode for 8-40 hours (while the metal of the high pressure cylinder body still does not have time to significantly cool down), the steam consumption required for ensuring reliable operation of the “5 turbine is determined by the value O ,, depending on the pressure in the condenser. Passing this amount of steam through the turbine and the operation of the cooling device 12 in the exhaust part 11 provide _{ί0 the} allowable temperature state of the low-pressure cylinder stages and

exhaust pipe.

If you need long-term reliable operation (with a sufficiently low pressure of 55 in the condenser) in the motor mode and to ensure the subsequent rapid transition to the operating mode under load (i.e., increasing maneuverability), steam consumption must be increased to the value O ₂ .

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Thus, the proposed method provides the possibility of long-term operation of a steam turbine installation in the motor mode, increases the efficiency and reliability of such work while maintaining high maneuverability.

Claims (1)

Claim A method of maintaining a steam turbine generator unit in reserve by transferring the generator to the engine mode, supplying fresh steam to the high-pressure cylinder of the turbine through its stop and control valves, determining the steam consumption values needed to prevent unacceptable heating of the low-pressure cylinder and unacceptable cooling of the high-pressure cylinder, and exposure the bypass valve of the main steam valve to maintain the flow of steam supplied, characterized in that, in order to increase maneuverability and economy Unity installation, compare steam consumption values, ί necessary to prevent unacceptable heating of the low pressure cylinder and unacceptable cooling of the high pressure cylinder, and affect the bypass valve on the highest of these values, ₁₀ and the turbine control valves are maintained in the fully open position.