In the gasoline vapor recovery equipment, the screw vacuum pump is the key equipment, and the main components of the gas pumped are gasoline vapor such as C4, C5, and C6.
Generally, the working temperature of the pump is required to be controlled below 80 ° c, but the cooling of the pump casing alone cannot reduce the working temperature of the pump to such a low temperature. In addition, cooling water cannot be provided in most areas. The coolant that can be provided is gasoline. In order to reduce the operating temperature of the pump, the most effective method is to inject an appropriate amount of gasoline (the highest temperature) into the pump cavity and then inject it into the pump cavity. Gasoline, which can evaporate heat to reduce the temperature of the pump chamber.
In the process of recovering oil and gas in the screw vacuum pump, the condensed gasoline will accumulate in the exhaust port of the pump, causing abnormal vibration and noise of the pump, which must be discharged in time. Therefore, the following three improvement measures can be taken.
1.The exhaust pipe of the pump is inclined downward, and the installation position of the exhaust system pipe is obviously lower than the position of the exhaust port of the pump.
2.Install a circulating pump at the lowest position of the pump outlet or muffler to eliminate liquid accumulation.
3.Install a one-way valve at the exhaust port of the pump to prevent siphoning when the pump is stopped, so that the condensed water flows back into the pump cavity.
Why does dry screw vacuum pump discharge at high frequency
Dry screw vacuum pumps have gradually replaced other traditional vacuum pumps by virtue of its series of advantageous features. It has begun to appear in various industries. So do you understand why screw vacuum pumps have high-frequency discharge?
The screw vacuum pump is a mechanical device that converts electrical energy into kinetic energy, and failures in long-term use are inevitable. The high-frequency discharge of a screw vacuum pump is a form of discharge caused when a high-frequency alternating electric field exists between two electrodes. The mass of positive ions is much larger than that of electrons, and the resonance amplitude is small. The frequency is low, and whenever the resonance amplitude is much larger than the two-stage distance, the electron will go through the whole process of collapse, release, and extinguishment every half cycle. This is the discharge condition is the same as the DC condition. When the frequency is high, if the resonance amplitude is much smaller than the distance between the two poles, the electrons will continue to move back and forth, and the ionization ability will become more and more powerful. The small electronic resonance amplitude will also greatly reduce the number of electrons entering the electrode. In this way, the electrons that ensure the self-discharge of the gas are no longer provided by the secondary electrons generated by the electrodes, but by the electrons generated by the ionization when the electrons move back and forth. At this time, there are also a small amount of positive ions and photons bombarding the electrode to generate secondary electrons, but because the electrode polarity continues to change, the vibration direction of the secondary electrons will be reversed at the same time relative to the electron flow direction.
As long as there is a high-frequency electric field, there will be a high-frequency discharge of the screw pump, which does not necessarily require a remote electrode, so it is generally called a non-polar discharge. The electrodeless discharge can not only be formed under an alternating electric field, but also a gradual magnetic field. The direction of the magnetic field is along the axis of the discharge tube, and the eddy current electric field is gradually weakened along the radial direction, and the separation power of electrons is also weakened along the radial direction, and a concentration gradient of electron ions also appears in this direction. The concentration gradient causes the electron ions to diffuse in the axial tube wall. Since electrons diffuse faster than ions, the diffusion results in a positive potential on the axis, a negative potential on the tube wall, and an electrostatic field directed to the tube wall from the axis. At this time, there are two kinds of electric fields appearing in the discharge tube, one is the turbine electric field, around the lines of magnetic force, the other is the electrostatic field, along the axis to the direction of the tube wall. Under the simultaneous action of these two electric fields, electrons move around the axis and diffuse toward the tube wall, forming a series of concentric rings in both directions. The energy of electrons with different radii is different, and the energy level and quantity of excitation are also different, so the color of the aperture of the radius is also different.
The ignition voltage that appears during the high-frequency discharge of the screw vacuum pump is an amplitude generated by the discharge, that is, the alternating potential difference on the electrodes. This amplitude is lower than the ignition voltage of DC discharge. The strength of the high-frequency damaging electric field is related to the air pressure. The higher the pressure, the greater the strength of the destruction electric field, and the higher the frequency of destruction. High frequency discharge is widely used in radar and pulse technology. The high frequency discharge phenomenon of the screw vacuum pump is the existence of the electric field between the electrodes. If this state occurs for a long time, it is easy to damage the equipment. You should master certain techniques and follow certain rules in use to avoid this phenomenon as much as possible.