Why should the valve be switched before the steam engine is 3000rpm

No, the oil pump is switched before the rated speed, and the single valve is switched to the sequential valve control after the load is loaded. The problem is clearer.

The purpose of single valve sequential valve switching is to improve the economy and rapidity of the unit, and the essence is to solve the contradiction between uniform heating and partial load economy in the process of variable load through the non-disturbance switching of nozzle throttling (single valve control) and nozzle steam distribution (sequential valve control).

Under the single-valve mode, the steam enters the regulating blade in a 360° circumference through the high-pressure regulating valve and the nozzle chamber, and the regulating blade is heated evenly, which effectively improves the stress distribution of the regulating blade and enables the unit to change the load quickly. However, since all the control valves are partially opened, the throttling loss is large.

The sequential valve mode is to let the regulating valve open and close one by one according to the pre-set order, before a regulating valve is fully opened, the other regulating valve remains closed, and the steam passes through the regulating valve and the nozzle chamber in the form of partial steam intake, the throttling loss is greatly reduced, and the thermal economy of the unit operation can be significantly improved, but at the same time, it has an impact on the existence of the blades, and it is easy to form a partial stress zone, and the speed of the load change of the unit is limited.

Therefore, during cold start or variable load operation under low parameters, the single-valve method can accelerate the thermal expansion of the unit, reduce the thermal stress, and prolong the life of the unit. When the variable load operation under the rated parameters is the assessment goal of the power plant's operation level, the sequential valve method can effectively reduce the throttling loss and improve the thermal efficiency of the steam turbine.

How big the unit is, what it produces, and how long it runs.

The temperature after the regulation stage is directly proportional to the steam flow, and the higher the steam intake, the higher the temperature after the regulation stage. Obviously, after the valve switching, the main steam flow is higher than before, so the temperature also increases.

The speed of the generator is related to the frequency of the output power, and the frequency of alternating current in China is 50Hz, so the speed of the generator should be a multiple of 50. Because the thermal generator speed is slow when the efficiency is low, the bearing can not be self-lubricated, so the generator speed is generally set at 3000 rpm, of course, there are some 1500 rpm. But on a hydro generator, the speed is very slow, hundreds of revolutions.

The speed of the pneumatic feed pump is independent of the frequency of the power supply, so it is designed to work optimally to determine its speed.

Replication is now calculated with software, if you want to estimate.

Calculation, first find out the BAI dead center of the steam turbine, generally near the center of the DU exhaust cylinder, the ZHI steam turbine drawings will be marked, and then calculate the relative distance (position difference) between the exhaust port and the dead center, the exhaust temperature of the exhaust pipe port is used, pay attention to the different exhaust temperatures of variable load, and the average temperature of the cylinder should be estimated at the inlet port.

Displacement = temperature difference x displacement difference x coefficient of metal expansion.

Partial inlet is defined as the ratio of the length of the arc at the average diameter of the nozzle flowing through the steam to the circumferential length at the average diameter.

Partial steam intake: Partial steam intake is usually used in the regulating stage due to the needs of the gas distribution mode. The ratio of the length of the arc segment equipped with a nozzle to the length of the entire circumference is often used to indicate the degree of partial steam intake, which is called the degree of partial steam intake.

It's troublesome, a few words can't be said clearly.

The need to increase or decrease the load, continuously monitor the operating parameters and status of the boiler, and automatically complete various operations and protection actions, such as emergency fuel cut-off** and emergency furnace shutdown, to prevent the accident from expanding. The main function of the steam turbine DEH system is to adjust the speed of the steam turbine, and can complete the following functions by shooting the leakage: hanging brake; Automatic judgment of thermal status; Select the launch method; speed increase; 3000rpm fixed speed; Generator false simultaneous test; grid-connected belt load; litres of load; valve switching; Single-valve, sequential valve switching; Regulatory-grade pressure feedback; load feedback; primary frequency modulation; CCS control; ATR Thermal Stress Control; high load limiting; low-load limit hail system; Valve position limitations; Main steam pressure limiting; quick load unloading; Overspeed Limit OPC; conform to the imbalance; Overspeed protection OSP; Fuel injection test; overspeed test; valve activity test; Valve ** tuning; solenoid valve test; Control mode switching.

Electrical ECS system, its main role is the start and stop control and logic of the generator; control and logic of each switch of the power system of the plant; Monitoring of the parameters of the electrical system and the status of the equipment; Relay protection action situation, fault alarm and timely attack room sequence record. The main function of the MEH system of the steam pump unit is to adjust the speed of the steam pump unit, which can complete the following functions: hanging gate, speed lifting, fixed speed, CCS control, overspeed protection and other functions.

The control target of DEH before grid connection is rotational speed.

After grid connection, the control target is the load, and the load is high when the steam inlet is large; The rotational speed is determined by the power grid.

Here's a simple example:

A hundred people pull a car to walk at a speed of 20 kilometers per hour, and one of them wants to walk 21 kilometers per hour, so how tired he is, he is almost pulling the car alone. So a hundred people is just a matter of you contributing more and he contributing less, and it is not possible for anyone who wants to run fast or slower.

The control system is measured and fed back and one, and no one tells us the specific internal principle.

After the steam turbine is connected to the grid, the speed is determined by the frequency of the grid and is not limited by the valve opening.

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