Analysis of the operating mode of the zero electric pump of the new flushing system

The steam-driven feedwater pump with the fourth-stage extraction steam as the working steam source can meet the water supply needs under the current load. At this time, the steam source of the small engine previously driven by the auxiliary steam should be switched to the normal working steam source, that is, the four-stage extraction The steam passes through during specific operations; the operating station closes the high and low pressure regulating valve of the small machine, and quickly completes the steam source switching work when the regulating valve is completely closed. Due to the inertia effect, the speed of the small machine is still as high as about 34567. Then quickly increase the speed of the small machine from the normal working steam source to the load stage, so as to ensure that the two steam-driven feedwater pumps operate in the normal way. According to the operating experience of Yiyang Power Plant, in the absence of electric pumps, according to the above operation mode, it is completely possible To ensure that the water supply needs to be started when the unit is fully cold, the steam pump can also meet the needs of starting when it is turned on in warm and hot states. In addition, when starting in hot state, in addition to using auxiliary steam, it can also be directly powered by high pressure. The steam source is used as the working steam source of the steam pump, and the heat storage of the boiler guarantees the steam demand before ignition. In this way, at the specified load points 1,1, the low-pressure steam source switching of the small engine is also required.

Technical measures to ensure the operation of the unit due to the lack of electric pumps, if the unit is still in operation according to the protection requirements, that is, the steam pump is protected when the unit is tripped, the unit will face the situation of being unable to supply water and dry pot This is not allowed. In order to ensure that the steam pump can still supply water to the unit normally during and after the unit is out of service, Yiyang Power Plant has made corresponding changes to the protection of the feedwater pump under the premise of ensuring the safety of the unit. The boiler> action in the logic .

If the machine trips, first touch the furnace>, and then by> realize that after the small machine trips, the small machine trip is cancelled. After the modification, the steam pump does not trip at the same time when the steam turbine trips, that is, the small machine can continue to run. The extraction steam has been lost, so in addition to ensuring that the small machine still keeps running after the main engine trips.

The high and low pressure control valve of the small machine should also be modified appropriately. The original design of the small machine is that the high pressure steam source is fully opened after the low pressure valve is fully opened and then controlled by the automatic steam distribution device according to the output requirements of the feedwater pump. When the regulating door is not fully opened, the high-profile door will not be opened, and it cannot be realized even if it is manually operated. Obviously, according to the original logic, the small machine cannot meet the requirements of Sheung Shui even if it does not trip. In order to correct this shortcoming, Yiyang Power Plant will not affect the small In the case of dual steam source operation characteristics of the engine, in the small engine; a small engine high-source steam source input permission button is added to the control. The function of this button is to not press the button when the high-pressure steam source cannot be backed up. When the low-pressure steam source cannot meet the requirements, the high-pressure steam source will not be switched on either

The above is appropriate, but the maximum value should not be exceeded, otherwise it may have a negative impact on the way of shutdown. For example, after the unit is out of service such as the sliding parameter shutdown, the drum water level should be raised to the highest water level as soon as possible. Steam can no longer guarantee the operation needs of the small machine and the small machine cannot run at no load for a long time. Therefore, after the unit is out of operation, the manual door of the water drainage system on the boiler side should be checked and tightened in time to avoid the valve from being loosely used. The water level of the steam drum drops too fast,

The accident condition lacks an electric pump as a backup, and it is not enough that the steam pump can only guarantee the normal start-up and shutdown of the water supply requirement. The water supply requirement under the accident condition should also be guaranteed, otherwise the operation mode discussed in this article should not be adopted. Due to the many types of accidents on site and the different situations, according to the characteristics of this article, we only discuss the worst working condition of unit fault trip during full load operation. Others such as single steam pump failure will not be discussed. Boiler overpressure is easy to occur. At the same time, due to the different reaction speeds of operators, there will generally be short-term boiler running short of water. However, as long as the operation mode of the feedwater pump is changed in time, it can basically meet the on-site operation requirements. Usually the unit trips The operating personnel should promptly open the high-pressure regulating valve of the small machine and quickly increase the outlet pressure of the steam pump to reach the pressure value required by the current water supply due to the sudden load dump of the unit.