Energy Saving Effect of Starting 300MW Thermal Power Unit with Steam Pump instead of Electric Pump

Technology and product use steam pump instead of electric pump to start 300M (energy saving effect of thermal power unit Shao Jianping) Shenzhen Mawan Power Plant, Shenzhen 518052, Guangdong, the start-up process of the unit, after actual application, has proved to have significant economics. In addition, the economic analysis of the equivalent turbulent drop method was conducted. Compared with the conventional qualitative analysis, we not only saw the direction of energy saving, but also saw the size of the direct economic benefits of the energy saving method, and thus achieved the equivalent hydrazine descending method. The application of energy-saving applications is promoted.

1 Put forward the problem of changing the way of Sheung Shui.

Phase I of Energy Research and Utilization At present, bidding for the Internet is about to be implemented or already implemented in some large power grids. The basis is low cost and low consumption, and energy conservation and consumption reduction are the current trends. In this form, it is of practical significance to study the way of energy-saving operation and analyze it economically.

The training water supply system for Shenjin Mawan Power Plant is set to a 2x50% steam-powered water pump plus a 50-capacity electric power feed pump, which is used as a starting backup pump. In normal operation, two steam pumps are running and the electric feed pump is used as a backup pump.

In the initial stage of start-up, it is generally to start the electric water supply pump to the boiler water until the unit takes about 120MW to start the steam-powered water pump and to exit the electric pump operation. This has virtually increased the consumption of the plant electricity (in our factory For example, the power consumption is about 25MWh, which accounts for about 20+ of the electricity consumed by the starter. If you use a steam-driven feedwater pump in the early stage of start-up, you can save plant power and improve the overall plant's adoption. Feasibility First, the models of the front pump and the main pump of the steam pump and the electric pump are the same model, and their characteristics are the same. In the same speed, the electric pump can meet the flow adjustment, the steam pump can also be satisfied, the key is the steam pump speed control problems. The small steam turbine that drives the steam feed water pump is controlled by the MEH system. The original design is to run to 3100 rpm under the automatic control mode of the turbine, open the outlet of the steam pump, and input the remote water supply control. The target speed is given by CCS automatically. Adjustment, gradually load Sheung Shui. In order to use the steam pump as soon as possible and to control the operation with a stable water level, the switching speed of the steam feed water pump of the 3rd and 4th units of the Mawan Power Plant has been changed to 2 600 rpm, which means that the CCS can control the speed of the steam pump to the boiler water at 2600 rpm. There is no special requirement for the adjustment characteristics of the small turbine after changing the switching speed. The starting characteristic of the electric pump is that at the beginning of the load, its speed is about 1600+, which is the energy saving effect of the 300MW thermal power unit replaced by the electric pump of the NVV. The reduction of the switching speed of the steam pump is then reduced. At 1500 rpm, it is possible to replace the electric pump completely and water the boiler in the same initial stage as the electric pump. After discussing with the thermal engineering professionals in our factory, based on a detailed study of the manufacturer's design data, it is considered feasible.

Table 1 shows the changes before and after the replacement.

In the process of switching between technology and product source, it is necessary to ensure a high degree of unity of work contact and coordination; d. During the adjustment of the speed of the steam pump, it is necessary to avoid staying near the first-order critical speed. When passing through the critical speed, attention should be paid to the adjustment of the water level of the drum. control.

4 Economic evaluation using the equivalent enthalpy drop method Energy research and utilization Phase 1 Table 1 Comparison of results before and after the implementation of the plan Water level adjustment Operational personnel's economical stability Operational difficulty Easiness of electric pump start-up Difficult to start the electric pump, need to carry out the steam pump and pump General steam pump is more stable without starting the electric pump, but easier, steam pump better start the need for steam source switching steam source switching implementation of the program 3 start the steam feed pump: steam Before the pump is put into operation, it should be in hot standby state, close the four-supply steam supply electric door and power off, and then check and start according to the normal start-up procedure, and pay attention to the following differences: a. Warm up at 600rpm for 25~30min, When the vibration of the small turbine bearing falls back to a lower value (below 20", below) and stabilized, the speed of the small turbine is again increased to 丨 5 +,6, the small turbine is printed in 丨 500, and the bearings of the warming machine 25 ~ 30 min are shaken down and stabilized. At this time, according to the outlet pressure of the steam pump, after appropriately reducing the rotation speed of the steam pump (approximately 1500 rpm or so), the outlet power door is opened to the boiler water, and the main water feed bypass bypass door at the furnace side is controlled at the manual position.

After the steam pump is put into operation, the flow rate of the feed water is adjusted: a. The speed of the small steam turbine should be controlled within the range of 600~2300 rpm at the initial stage of the drum water or when the drum pressure is low. Control the water supply by adjusting the opening of the feed water bypass valve. Flow; 6. Pay attention to the coordinated control of the speed of the small turbine and the opening of the main feedwater bypass adjustment gate. At this time, the electric feed pump can be put into automatic standby to increase the insurance factor. c. After the generator is connected to the grid, another steam pump is started in time according to the load to meet the requirements of the boiler feed water; d. The load is stable at about 150 MW, and the power consumption of the plant is switched to the belt. At this time, the steam generator of the small turbine is switched to Four pumping belts to improve the economic performance of the unit. When switching, it is necessary to turn off the inlet steam manual door of the auxiliary steam to the small steam turbine until the door opening degree of the steam turbine is increased to a certain degree, and the steam inlet pressure is lower than the four suction pressure at that time.

Operation Precautions: a. Auxiliary steam for small machine vibration during start-up of small turbines, small cylinder temperature, etc. should be monitored and adjusted; 6. When the second steam pump is ready to start, the electric pump must exit automatic standby to avoid unnecessary The electric pump is connected to start up; c. The starting process and the steam turbine of the small steam turbine The steam consumption of the steam pump does not change much under low load, and the error is within the allowable range. In order to facilitate the comparison and calculation convenience, we use the local machine 30; the load is the calculation point, calculated in the machine 30; load when the steam pump instead of the electric pump operation, the adjacent machine load is 70%, 30%, due to additional supply Steam pumps use steam to reduce the load, and then calculate the power consumption of the pump, the difference is the amount of power saved.

First, calculate the following parameters for the 30; load sliding pressure operating conditions as follows: Lin Wanchao. Thermal Power Plant Thermal System Theory. Xi'an: Xi'an Jiaotong University Press, 1994.