Matters Needing Attention in the Installation and Maintenance of Choke Valve

Matters Needing Attention in the Installation and Maintenance of Choke Valve

Oil and gas choke valve is a valve that controls fluid flow by changing the throttle section or throttle length. A one-way choke valve can be combined by connecting the choke valve and the one-way valve in parallel. Choke valve and one-way choke valve are simple flow control valves. In the quantitative pump hydraulic system, the choke valve and the overflow valve cooperate to form three kinds of throttling speed regulation systems, that is, throttling and speed regulation of the oil inlet circuit. system, oil return throttling speed regulating system and bypass throttling speed regulating system. The choke valve has no flow negative feedback function and cannot compensate the speed instability caused by the load change. It is generally only used in occasions where the load change is small or the speed stability is not high. The valve often needs to be operated, so it should be installed in a position that is easy and convenient to operate. When installing, pay attention to keep the direction of the medium consistent with the direction of the arrow marked on the valve body.

Ⅰ. The sources of oil and gas choke valve body deposits are more complicated, but can be classified into:

1. Mechanical impurities in the oil or colloid, asphalt, carbon residue and other dirt due to oxidation are accumulated in the throttling gap.

2. Due to the aging or extrusion of the oil, charged polarized molecules are produced, and there is a potential difference on the metal surface of the throttling gap, so the polarized molecules are adsorbed to the surface of the gap, forming a firm boundary adsorption layer, and the thickness of the adsorption layer is Generally, it is 5~8 microns, which affects the size of the throttling gap. When the above accumulations and adsorbates grow to a certain thickness, they will be washed away by the liquid flow, and then reattached to the valve port. Repeatedly in this way, the pulsation of the flow is formed.

3. When the pressure difference at the valve port is large, due to the high temperature of the valve port, the degree of extrusion of the liquid is enhanced, and the metal surface is also more susceptible to friction to form a potential difference. Therefore, when the pressure difference is large, blockage is likely to occur.

4. Source of PCV exhaust gas: After the combustible mixture in the combustion chamber enters the crankcase through the piston gap, it is mixed with engine oil vapor to form a mixed gas. To avoid diluting and contaminating the oil, the mixture is drawn into the intake tract by the positive crankcase ventilation system (PCV) for secondary combustion. After this part of exhaust gas enters the intake port, it will condense and form a liquid state due to the temperature drop, and the "unstable components" in it will oxidize and condense at high temperature, and form grease on the surface of the choke valve and adhere to it.

5. Lubricating oil infiltrated by the turbocharged compressor: For turbocharged engines, the exhaust gas drive method is generally adopted, that is, the high-pressure exhaust gas generated by the exhaust passage is used to drive the turbine, and the compressor blades in the intake passage are driven through the coaxial, The formation of air intake port air pressure boost. However, under long-term and harsh working conditions, coaxial bearings are prone to penetration and volatilization of lubricating oil. In addition, the inflation efficiency is doubled, and heavy oil pollution is more likely to form and aggravate the adhesion of throttle body deposits.

6. Fuel vapor discharged from the carbon canister: Among the fuel vapor absorbed by the carbon canister of the engine, cyclopentadiene is easy to form choke valve deposits, and it can be oxidized and condensed to form colloidal grease under continuous high temperature.

Ⅱ. Choke valve maintenance and cleaning

When the choke valve is blocked by deposits, the throttle opening value will be disordered, and the engine cannot control its opening stably and accurately. If the opening value is too low, it will cause difficulty in starting, unstable idling speed or abnormal flameout; , The choke valve cannot respond in time, which will cause acceleration delay or sudden speed increase.