Application of water ring vacuum pump in ejection system
1. The condenser vacuum is an important economic indicator of the generator set, which is of vital importance to the efficiency of the unit. According to the thermal characteristics, the efficiency of the turbine is reduced by 0.75% according to the vacuum per 1kPa. Therefore, how to improve the vacuum and achieve the best vacuum of condenser is the top priority of energy saving management for each unit. In domestic units, the condenser vacuum system has the following characteristics:
1) circulating water continuous adjusting range is narrow, mainly by the local regulation of imported door and follow the step of pump operation mode adjustment, the main role to keep the vacuum, form following pump optimization scheduling problem, not to improve the vacuum effect.
It is difficult to achieve the ultimate vacuum in the design of the unit, and most of the units have the possibility and feasibility to further improve the vacuum.
The improvement of the vacuum solution mainly includes the improvement of the rubber ball cleaning system, the performance improvement of the cooling tower, the improvement of the ejection system and so on. The successful case of ejection system improvement is quite a few. The case of water ring vacuum pump is a new example.
2. The example analysis unit has the following problems:
There are 3 12sh-6b (220kW) pumps in the original unit. Due to the low ejection efficiency, all the pumps must be put into the water pump in normal operation.
Because the water tank is made of cement, the wall leakage is serious, and the water replenishment of circulating water is increased, so the overall efficiency of the unit is reduced.
(3) water jet ejector is working medium drive extraction equipment, with the change of the working condition, unstable operation, water consumption and water jet ejector equipment is big, low efficiency, inconvenient operation, causing unnecessary loss of economic operation for the factory.
The efficiency of the system is low, so that the vacuum of the condenser can not meet the design requirements: in the case of the vacuum of the unit in the second half of the year, the vacuum tightness is 0.6kpa /min on average.
3 transformation double-stage vacuum pump characteristics of vacuum pump, through the feasibility analysis and argument, the original water jet extraction system, all the equipment is removed after only one vacuum pump (110 kw) motor power to run, save electricity power of 550 kw per hour, total unit in operation can power saving 3850000 degrees calculated at 7000 h, calculated at 0.2 yuan per kilowatt-hour, save money 770000 RMB each year. Beam pumping system after the renovation work, turn off the vacuum pump imported manual door and start the experiment to establish full scale vacuum time is approximately 30 s, the motor current and the bearing temperature is normal, no other anomalies were found, after a startup success. Work later in the operation name note vacuum pump suction pressure in the normal working condition of data (MPa) 0.0049 minimum suction pressure (MPa) vacuum pump in the normal working order pump output (kg/h) 77 for the amount of dry air vacuum pump speed (r/min) 590 noise (db (A)) < 85 cooling water heat exchanger (m3 / h) 29.98 system work flow (m3 / h) 15.9 to start the vacuum time (min), 28 in the condenser steam exhaust quantity (664 t/h).
4. The vacuum analysis under load in the power (kW)59.5 motor power (kW)110 is shown in table 3. The vacuum increases by 0.45kpa on average, and the turbine efficiency is 0.3%. Table 3A test comparison table (kPa) of the condenser before and after the transformation of the unit
(1) water ring vacuum pump is a kind of good performance of the condenser vacuum equipment, has strong ability of extraction, dry air and prevent cavitation characteristics, at the same time with the use of safe, reliable operation, high automatic degree, low maintenance workload, etc.
After replacing the pump with water ring vacuum pump, the operation condition of the condenser is improved effectively, which improves the operating efficiency of the whole unit and reduces the power consumption of the plant.