Foreword

Sulfur is a light yellow crystal with a melting point of 112.8-119.3℃, and its physical properties are relatively special, and its viscosity changes with the change of temperature. As shown in the figure below, the viscosity of solid sulfur decreases with the increase of temperature when it is in incipiency; the liquid sulfur, when it is less than 159℃, is still annular; when the temperature is greater than 159℃, it cracks into chain S8 molecules, and the viscosity increases sharply with the increase of temperature, reaching a maximum value of 93Pa.S at 190℃. When the temperature is higher than 190℃, the viscosity decreases with the increase of temperature. When the temperature is less than 120 ° C, it is possible to solidify into solid sulfur, at 150 ° C to 190 ° C, the viscosity rises sharply to a maximum value, and will gradually decline as the temperature continues to rise. Therefore, when the liquid sulfur temperature is > 158 ° C, due to its excessive viscosity, the fine sulfur pump can not be used normally.

1. Fault Symptom

In the process of load adjustment of the sulfur acid making plant, the flow rate of the sulfonate gun is often reduced or the liquid sulfur is transported, resulting in continuous production being interrupted and the device being forced to stop. However, there is often no abnormal situation found when stopping to check the fine sulfur pump, sulfur pipeline, and sulfur gun, and everything is normal when starting the fine sulfur pump again.

2. Cause analysis

Fine sulfur pump operates under small flow conditions, the pump provides a larger head, but the efficiency of the pump is low, the pump energy loss is large, the liquid sulfur fluid in the pump is almost doing adiabatic compression, remove a certain amount of energy obtained by liquid sulfur in the pump, the rest of the energy is converted into heat energy, transferred to the liquid sulfur in the pump, when the pump delivers less liquid sulfur, can not take the heat away in time, It causes the temperature of the liquid sulfur to rise. Since the normal production temperature of the fine sulfur tank is maintained at 135~145 ° C, when the liquid sulfur transported is heated to 160 ° C, the viscosity of the liquid sulfur will rise rapidly, resulting in liquid sulfur unable to flow in the pipeline and unable to transport liquid sulfur to the sulfonate gun.

3. Solution

The output power of the pump is greater than the output power of the liquid sulfur taking away the pump, and the excess output power of the pump is converted into heat and transferred to the liquid sulfur, heating the liquid sulfur to more than 160 ° C, and the viscosity of the liquid sulfur rises rapidly, thus affecting the flow of liquid sulfur in the pipeline. Therefore, when adjusting the load, it is necessary to follow the standard operation sequence to avoid the liquid sulfur being heated in the pump.

Lifting load

(fine sulfur pump is a variable frequency pump) Check whether the manual valve on the sulphate tube is in the throttling state. If yes, first increase the opening of the manual valve, reduce the operating pressure of the sulphate tube, and slowly increase the frequency conversion of the fine sulfur pump to reach the predetermined load flow. When the pressure of the sulfonate tube is high and the flow rate of liquid sulfur is small, it is necessary to open the manual valve again, or check whether there is a blockage of the sulfonate gun, and increase the frequency conversion again to reach the predetermined value after eliminating the problem.

(fine sulfur pump is power frequency pump) Check whether the manual valve on the sulphate tube is in the throttling state. If yes, first increase the opening of the manual valve, reduce the operating pressure of the sulphate tube, and slowly turn down or close the return valve to reach the predetermined load flow. When the reflux valve is turned off, the pressure on the sulphate pipe increases and the liquid sulphur flow rate is low, check whether the sulphate gun is blocked or the liquid sulphur temperature rises.

Load reduction

(fine sulfur pump is a variable frequency pump) When it is necessary to reduce the number of sulfonate guns used to achieve the purpose of reducing the load, it is necessary to reduce the frequency first, but the pressure of the sulfonate pipe must be maintained above the minimum pressure of the sulfonate gun atomization, before closing the inlet valve of the on-site sulfonate gun to achieve the goal of reducing. If the inlet valve of the sulfonate gun is closed first and the frequency conversion is reduced, the liquid sulfur in the pump will be overheated and the liquid sulfur cannot be transported.

(fine sulfur pump is power frequency pump) When it is necessary to reduce the number of sulfonate gun to achieve the purpose of reducing the load, it is necessary to use the return valve to control the pressure of the sulfonate pipe to ensure that the flow rate of the pump after the sulfonate gun is closed is above the minimum flow rate allowed by the pump, and the sulfonate gun inlet valve can be closed.

Precautions

In the selection of fine sulfur pump, according to the maximum amount of sulfur spray capacity of the device, the flow regulation ratio of the sulfur gun, the minimum pressure and the maximum pressure of atomization parameters, according to the lift and flow of the fine sulfur pump, calculate the shaft power of the pump and match the corresponding motor. Since the efficiency of the pump will decrease during operation, the calculated shaft power can be amplified by 20~50%, and the shaft power should not be amplified by 1.5~2 times. When the amplification is too much, the minimum flow rate of the pump will exceed the flow rate of the sulfonate gun, and the liquid sulfur temperature in the pump will rise. The minimum working flow of the fine sulfur pump, the working flow of the sulfonate gun and the pressure range should be reflected in the operating procedures.