[Q&A Question 060] 2017.03.01

Check whether the belt is properly fastened before starting the motor

First, check whether power is supplied to the motor. If the unit is started up, it is also necessary to verify whether the stop button for the air cooler of the reactor effluent has been reset. Before starting the motor, it is required to turn the shaft by hand to check if its rotation is normal. After the high-pressure air cooling system is put into use, it is necessary to check whether the temperatures of all individual circuits are consistent; if any uneven distribution of flow occurs, it should be addressed promptly. The operating air-cooled fans should be kept as evenly distributed as possible. For a single air-cooled unit that has been repaired and put back into operation, water injection should be initiated as soon as possible to prevent the formation of ammonium salts, which could affect the cooling efficiency and flow rate, thereby avoiding increased corrosion of the equipment.

First, check whether power is supplied to the motor. If the unit is about to start up, also verify whether the button to shut down the reactive effluent air cooler has been reset. Before starting the motor, it is also necessary to turn the shaft by hand to check if its rotation is normal.

I. Preparatory work before startup 1.1 Check the clearance dimensions of various parts of the fan; the radial clearance between the blades and the duct shall be no greater than the smaller of 0.5% of the fan’s diameter and 19 mm, and shall not be less than 9 mm (for fans with a diameter of less than 2.4 m, it shall not be less than 6 mm). ) 1.2 Check whether the tension of the belt is appropriate and its degree of wear; if there are any issues, it should be replaced promptly. 1.3 Set the frequency conversion signal of the motor equipped with a frequency conversion device to the desired value. 1.4 Rotate the fan to check for any scratches on the fan blades, for any abnormal noises in the fan’s bearing box, and to determine whether the rotation is heavy. II. Startup 2.1 Start the fan by pressing the start button. Check whether the operating sound of the fan is normal, inspect the vibration of the fan as well as the temperature rise at various operating points; if any abnormal noises are detected, the fan should be stopped immediately to identify the cause. 2.2 After the first startup, conduct a 1-hour test at the maximum installation angle; no abnormal phenomena should occur. 2.3 Adjust the operating angle of the fan to an appropriate position according to the required amount of cooling air. 2.4 Motors equipped with variable frequency systems shall have their variable frequency systems put into use. 2.5 Check the motor current; if it is too high, adjust the angle of the blades accordingly.

Before putting the air cooling into use, the air cooling tube bundle has been connected to the reaction system. Open the air cooling louvers, first rotate the air cooling motor to apply lubricant, and then turn on the power supply

First, check whether power is supplied to the motor. If the unit is about to start up, also verify whether the button to shut down the reactive effluent air cooler has been reset. Before starting the motor, it is also necessary to turn the shaft by hand to check if its rotation is normal. After the high-pressure air cooling system is put into use, it is necessary to check whether the temperatures of each branch are consistent; if any uneven distribution of flow occurs, it should be addressed promptly. The operating air-cooled fans should be kept as evenly distributed as possible. For a single air-cooled unit that has been repaired and put back into operation, water injection should be initiated as soon as possible to prevent the precipitation of ammonium salts from affecting the cooling efficiency and flow rate, thereby avoiding increased corrosion of the equipment. Areas prone to corrosion are generally elbows and other locations where turbulence occurs; the presence of Cl- and oxygen accelerates corrosion. The corrosion rate is also related to the flow rate of the medium; if the flow rate is too low, the corrosive agents tend to accumulate, thereby exacerbating corrosion ； When the flow rate is too high, erosion combined with the corrosion caused by NH4HS intensifies as well. Therefore, it is necessary to select an appropriate flow rate and be sure to avoid flow deviation; attention should be paid to this when putting it into use. The flow velocity of the medium inside the carbon steel is 4.3~6.1 m/s. The conditions under which corrosion occurs in high-pressure air cooling are as follows: molar concentration < 0.07, no corrosion will occur ； Corrosion can also occur when it is between 0.07 and 0.2 ； When it is greater than 0.5, corrosion definitely occurs ； In highly acidic water, the NH4HS concentration is ≯4%, so the likelihood of corrosion is low. When injecting softened water at high-temperature areas, it is necessary to ensure that 20% of the total water injection volume remains in liquid form at those areas, provided that the amount of water injected is sufficient. This is to prevent all the water from vaporizing and turning the environment acidic, or to avoid excessive local concentrations of salt that could lead to crystallization when the first drops of water begin to condense. For high-pressure cooling, 16MnR (HIC) or carbon steel is generally used; the operating temperature for carbon steel should be below 200°C, otherwise hydrogen corrosion will occur (Nelson curve).

First, check whether power is supplied to the motor. If the unit is about to start up, also verify whether the button to shut down the reactive effluent air cooler has been reset. Before starting the motor, it is also necessary to turn the shaft by hand to check if its rotation is normal. After the high-pressure air cooling system is put into use, it is necessary to check whether the temperatures of each branch are consistent; if any uneven distribution of flow occurs, it should be addressed promptly. The operating air-cooled fans should be kept as evenly distributed as possible. For a single air-cooled unit that has been repaired and put back into operation, water injection should be initiated as soon as possible to prevent the precipitation of ammonium salts from affecting the cooling efficiency and flow rate, thereby avoiding increased corrosion of the equipment.

Answer: First, check whether power is supplied to the motor. If the unit is starting up, also verify whether the stop button for the reactive effluent air cooler has been reset. Before starting the motor, it is also necessary to turn the shaft by hand to check if its rotation is normal. After the high-pressure air cooling system is put into use, it is necessary to check whether the temperatures of each branch are consistent; if any uneven distribution of flow occurs, it should be addressed promptly. The operating air-cooled fans should be kept as evenly distributed as possible. For a single air-cooled unit that has been repaired and put back into operation, water injection should be initiated as soon as possible to prevent the precipitation of ammonium salts from affecting the cooling efficiency and flow rate, thereby avoiding increased corrosion of the equipment.

①Before activating the air cooler, carefully inspect and remove any debris on and around it. ②Perform fan barring to check whether the lubricating grease is sufficient, whether the belt is secure and at the proper tension, and whether the automatic or manual adjustment mechanism operates smoothly and reliably. ③After starting, it is necessary to check the operation of the fan, motor current, temperature, speed, and lubrication conditions. ④During normal operation, it is necessary to regularly check for leaks at the inlet and outlet flanges of the tube bundles in the air cooler, and strive to keep the temperatures at the outlets of each tube bundle roughly the same.

1) Open the drain valve before the return water valve, slightly open the supply water valve, and then open the return water valve once the drain valve switches from discharging air to discharging water. 2) Open the supply valve fully, and adjust the opening degree of the return valve according to the temperature at the medium outlet.