Preventing compressor pressure material and process

The natural gas pressure in the pipeline is affected by the ambient temperature, flow resistance along the way, and flow rate, which is unstable. The purpose of the damper is to buffer pressure fluctuations in the gas pipeline. Piston movement during compressor operation causes pressure pulsations in the intake manifold. The damper is also used to block the pressure pulsations in the intake pipe from passing into the gas pipe. In addition, the unloading valve of the compressor and the natural gas discharged from the safety valve are also sent to the buffer to expand to the inlet pressure. The purpose of the pressure reducing valve is to maintain a certain compressor inlet pressure. The main components of the outlet system are dryers, filters, check valves and so on.

If the natural gas content of the compressor outlet reaches 110 ppm, the outlet system must have an absorption dryer to completely remove moisture to prevent corrosion of downstream components and water blockage in low temperature environments. When the natural gas flows through the dryer, a part of the desiccant particles are entrained, so there is a molecular sieve filter behind the dryer to remove the desiccant particles and water droplets and oil droplets below 0.1 m.

The dryer is operated in two parallel rotations, one of which is working and the other is being restored. A small amount of uncooled natural gas is taken out at the compressor outlet, and after decompression, flows through the dryer in the opposite direction to restore the absorption capacity of the dryer. The check valve allows natural gas to flow out of the outlet without allowing inflow. Compressed natural gas storage system There are two different forms of car refueling: first, refueling after stopping on the same day, regardless of the length of refueling time; second, the car needs to be refueled during driving to complete quickly. Thus, two storage systems are formed, namely a slow charging system and a fast charging system.

It takes a long time to inflate the car cylinder through continuous operation of the compressor. The inflation time depends on the compressor capacity, the number of inflated vehicles, and the capacity of the vehicle's gas cylinder. The slow-charge system is suitable for public and private bus services, which return to the public parking lot every night. Each car has a relatively fixed mileage every day. If you do not calculate the parking time and there is a parking position next to the filling station, then the slow charging system is the most economical. Slow filling (gas) machines, usually not metered, mainly include inflation valves, pressure gauges, hoses and fittings. The cost of a slow charge (gas) machine depends on the level of reliability. Normally unattended during the inflation period, additional safety devices need to be installed. The fast charge system fast charge system is inflated by using the natural gas stored in the high pressure gas cylinder group, and the high pressure natural gas is pre-outputted to the gas storage bottle group through the compressor, and then the gas cylinder is refilled. The system is capable of inflating at a flow rate greater than the displacement of the compressor, thus requiring less time.

In order to maintain fast charging, a sufficient pressure difference should be maintained between the vehicle cylinder and the gas cylinder of the dispenser. The pressure of the cylinder group is usually maintained at a filling pressure (gas) to adjust the gas flow to a pressure of 20 MPa. The inflation time is a function of the pressure difference. The flow starts at the maximum and then gradually decreases. At the beginning, through the check valve CV1, the gas is sent from the compressor to the high pressure cylinder group, and at the same time, when the pressure of the high pressure cylinder group reaches 21 MPa by the priority sequence valve DL (spring control), the priority of the sensor opening the medium pressure cylinder group Valve 1, the gas enters the medium pressure cylinder group, and the check prevents the gas from flowing back in the high pressure cylinder group. Similarly, when the pressure of the medium pressure cylinder group reaches 21 MPa, the sensor opens the priority valve 2 of the low pressure cylinder group, the gas enters the low pressure cylinder group, and the check valve CV prevents the gas of the medium pressure cylinder group from flowing back. Finally, when the pressure of the low pressure cylinder group reaches 21 MPa, all the priority valves are opened, and all cylinder groups are inflated to 25 MPa, at which time the compressor is closed by the pressure switch. Simply put, the three-level priority is: high-pressure gas cylinder group; medium-pressure gas cylinder group; low-pressure gas cylinder group.

The heart of the compressor filling station is the compressor, and its reliability is very important. Usually, the initial pressure in the gas cylinder is 20 MPa, and the initial pressure in the gas cylinder is 25 to 26 MPa. Regarding the outlet pressure of the compressor, the resistance loss of the gas line and the valve member and the temperature should be considered, and should be about 30 MPa. With such a high outlet pressure, only the piston type three-stage compressor can be satisfied, and the average pressure ratio per stage is about 16. According to the outlet pressure and pressure ratio, the inlet pressure of the compressor should be below 7 kPa, so the inlet system must have a pressure reducing valve. Due to the high pressure ratio, the compressor has a cooler at each stage of the outlet, so that the outlet temperature of each stage is close to the inlet temperature, thereby reducing the total power consumption.

The gas-water separator of the imported system can only separate the water under the imported state, but after the natural gas is compressed and cooled, the water will continue to be suspected, so each stage of the compressor has a gas-water separator. In order to prevent the compressor's outlet pressure material and process in order to improve the service life of the pendulum die, we have adopted the process curve of ultra-high temperature quenching and tempering heat treatment. After ultra-high temperature quenching and tempering, the hardness of the mold is HRC43-47. After being used on the pendulum machine, each set of pendulum mold can process about 6,000 pieces of semi-axle, and its thermal fatigue resistance is obviously improved.

Analysis and comparison of two different heat treatment processes 5CrMnMo is a medium carbon alloy steel, which is pre-cooled and quenched after heating to 820-850 °C, and the metallographic structure is a mixture of lath martensite and acicular martensite. Among them, lath martensite has better comprehensive mechanical properties, while micro-cracks in acicular martensite have poor plastic toughness. After medium-temperature tempering, the shape of acicular martensite cannot be completely eliminated, thus leading to hot forging. The mold has poor heat fatigue resistance and short service life.

After quenching the 5CrMnMo hot mold steel to 910-930 °C, the following effects will be affected on the microstructure transformation: (1) As the heating temperature increases, the austenite grains grow and the yield strength of austenite becomes smaller. Easy to form lath martensite.

(2) Ultra-high temperature austenitizing treatment increases the amount of alloy carbides to be melted, which reduces the possibility of unmelted carbides as acicular martensite nucleation sites and also reduces the number of microcracks present.

This means that after ultra-high temperature quenching, a large amount of lath martensite structure is easily obtained, and the influence of microcracks in the needle-shaped martensite can be effectively eliminated, and the thermal fatigue resistance of the pendulum mold is improved.

Conclusion After the ultra-high temperature quenching and tempering, the pendulum die has obtained a better structure and has higher heat fatigue resistance, which greatly improves the service life of the pendulum die and reduces the production cost. Economic benefits.

Force and temperature exceed the limit, each level has safety valves and thermal relays. Natural gas is a flammable gas, the gas station must be explosion-proof, and the compressor is usually driven by an explosion-proof motor. The compressor must be unloaded when it stops working, otherwise the motor will not start. Therefore, each stage of the compressor has an unloading valve, and the natural gas discharged from the unloading valve and the safety valve is sent to the buffer. In order to obtain a faster refueling time than liquid fuel, an air refilling machine is used. According to the capacity of the filling station, the dispenser can have one or several airing hoses. The end of the aerated hose is a quick connector for aeration, and the other end is connected to the dispenser via a solenoid valve. The dispenser has a line connecting the snubber, which is connected to the hose through a solenoid valve. When the vehicle refueling reaches the rated pressure, the solenoid valve closes the hose, stops the filling and closes the buffer, and discharges the high-pressure natural gas inside the hose to ensure the safety of the operator and the environment.

In order to make the best use of the stored gas, the three-way electronic refueling (gas sales) machine is refueled according to the low cylinder group, the medium pressure cylinder group and the high pressure cylinder group. The gas filling machine records the gas delivery volume, gas filling time, natural gas pressure and temperature of each aerated hose. Therefore, the dispenser is equipped with the following meters: flow meter, flow recorder, pressure gauge, pressure recorder, thermometer, temperature recorder, price recorder, printer and timer. Compressor kits are typically housed in a single enclosure for 24/7 protection and noise reduction, with proper ventilation and heat dissipation, and a low gas ignition concentration of less than 25%.