(Daily Question) Coal-to-oil and olefins forum, April 18, 2018

Factors affecting the vacuum level of the rehydrator include: plant load, drive steam temperature and pressure, extraction steam volume, rehydration water volume, and cooling water volume or cooling temperature

Reasons for the decrease in vacuum degree in the water reclaimer① Blockage of the nozzles of the two-stage vacuum pumps, which affects their performance. ② If the tubes of the water cooler become clogged, the cooling efficiency decreases, and the steam entering the machine cannot be effectively condensed. ③ The vacuum system has poor sealing performance, with issues such as failed sealing, inadequate welds, or corrosion-induced perforations. ④ The cooler of the air compressor is clogged or the water pipes are blocked, resulting in a reduced cooling effect. ⑤ The liquid level in the water recirculator is too high, which affects its cooling efficiency. ⑥ The circulating water pressure is low or the temperature is too high, failing to meet the requirements for the operation of complex water treatment equipment. ⑦ The turbine blades get clogged, steam expansion is hindered, and its internal energy cannot be released properly. Treatment measures: ① Inspect the nozzles of the two-stage vacuum pump, remove debris and blockages to keep the vacuum pump in good condition. ② Open the cover plates at both ends of the water recycler, remove the dirt from it, and restore its cooling efficiency. ③ Check the tightness of the welds and sealing areas in the vacuum system, repair leaking welds and corrosion-induced holes, and replace damaged sealing gaskets to ensure the reliability of the vacuum system’s sealing. ④ Open the exhaust cooler, remove debris and blockages from the pipes, to ensure effective exhaust. ⑤ Start the auxiliary recirculation pump to restore the liquid level in the recirculator to normal, and further investigate the cause of the high liquid level in the recirculator in order to address it. ⑥ When checking the circulating water, install pipelines to remove blocking debris, and inform the circulating water system to increase the pressure of the circulating water and lower its temperature, so that the circulating water falls within the specified control range. ⑦ Conduct a disassembly inspection of the turbine blade condition, remove debris from the blades, maintain the cleanliness of the gas passages, and improve the efficiency of steam expansion work.

1) Low cooling water pressure, high temperature, and insufficient flow. 2) System leakage (turbine seal leakage). 3) Fouling of the surface condenser. 4) The jet pump nozzle is clogged or damaged. 5) Poor return water flow in the jet pump condenser. 6) The pressure of the injected steam is low. 7) After the startup jet pump was shut down, the valve connecting it to the reheat apparatus was not fully closed. 8) The water seal of the atmospheric safety valve is not in good condition, and the sealing water of the recirculation pump is abnormal. 9) The leak steam condenser is not working properly. 10) The liquid level in the rehydrator is too high, reducing the heat exchange area of the rehydrator. 11) The sealed steam control valve is malfunctioning, resulting in low pressure.

1) Low cooling water pressure, high temperature, and insufficient flow. 2) System leakage (turbine seal leakage). 3) Fouling of the surface condenser. 4) The jet pump nozzle is clogged or damaged. 5) Poor return water flow in the jet pump condenser. 6) The pressure of the injected steam is low. 7) After the startup jet pump was shut down, the valve connecting it to the reheat apparatus was not fully closed. 8) The water seal of the atmospheric safety valve is not in good condition, and the sealing water of the recirculation pump is abnormal. 9) The leak steam condenser is not working properly. 10) The liquid level in the rehydrator is too high, reducing the heat exchange area of the rehydrator. 11) The sealed steam control valve is malfunctioning, resulting in low pressure.

Answer: (1) Operating condition of the jet pump； (2) The liquid level in the rehydrator is too high ； (3) Cooling water volume and temperature of the rehydrator ； (4) Is the water seal of the atmospheric safety valve functioning properly? ； (5) Are there any air leakage points in the system?

1) Low cooling water pressure, high temperature, and insufficient flow. 2) System leakage (turbine seal leakage). 3) Fouling of the surface condenser. 4) The jet pump nozzle is clogged or damaged. 5) Jetting

(1) Operating condition of the jet pump； (2) The liquid level in the rehydrator is too high ； (3) Cooling water volume and temperature of the rehydrator ； (4) Is the water seal of the atmospheric safety valve functioning properly? ； (5) Are there any air leakage points in the system?

① The nozzles of the two-stage vacuum pump are blocked, affecting the performance of the pump. ② If the tubes of the water cooler become clogged, the cooling efficiency decreases, and the steam entering the machine cannot be effectively condensed. ③ The vacuum system has poor sealing performance, with issues such as failed sealing, inadequate welds, or corrosion-induced perforations. ④ The cooler of the air compressor is clogged or the water pipes are blocked, resulting in a reduced cooling effect. ⑤ The liquid level in the water recirculator is too high, which affects its cooling efficiency. ⑥ The circulating water pressure is low or the temperature is too high, failing to meet the requirements for the operation of complex water treatment equipment. ⑦ The turbine blades get clogged, steam expansion is hindered, and its internal energy cannot be released properly.

1. Low cooling water pressure, high temperature, and insufficient flow rate； 2. System leakage ； 3. The jet pump nozzle is clogged or damaged ； 4. Poor return flow of the jet pump condenser water ； 5. Fouling on the surface condenser ； 6. The steam injection pressure is low.

1) Low cooling water pressure, high temperature, and insufficient flow. 2) System leakage (turbine seal leakage). 3) Fouling of the surface condenser. 4) The jet pump nozzle is clogged or damaged. 5) Poor return water flow in the jet pump condenser. 6) The pressure of the injected steam is low. 7) After the startup jet pump was shut down, the valve connecting it to the reheat apparatus was not fully closed. 8) The rehydration return control valve fails to close, preventing the injected steam from condensing. 9) The water seal of the atmospheric safety valve is not in good condition, and the water seal of the feed pump is abnormal. 10) The leak steam condenser is not working properly. 11) The liquid level in the rehydrator is too high, reducing the heat exchange area of the rehydrator. 12) The sealed steam control valve is malfunctioning, resulting in low pressure.