Cause analysis and treatment of lubricating oil in high pressure air compressor of Yantan Hydropower Station
Cause Analysis and Treatment Method of Lubricating Oil Inlet of High Pressure Air Compressor in Yantan Hydropower Station of Water Resources and Power Station 覃 Tao (Da Tang Yantan Hydropower Co., Ltd., Dahua 530811, Guangxi) 掮 Datang Yantan Hydropower Co., Ltd. No. 1 High Pressure Air Compressor During the overhaul process, the oil inlet defects are analyzed and processed. By installing a water-oil separator after the air compressor outlet pipe, the moisture in the compressed air is effectively removed, and the running time of the air compressor is prolonged, and the problem of the water inflow of the high-pressure air compressor lubricating oil is completely solved, which is a high-pressure gas system. Provides a high quality gas source.
1 Equipment Overview Datang Yantan Hydropower Co., Ltd. (referred to as Yantan Company) is located in the middle section of Hongshui River in the Pearl River Basin. It has 4 sets of 30.25 million kW mixed-flow hydroelectric generating units with a total installed capacity of 1.21 million kW. The volume is 5.66 billion kW*h, shouldering the heavy responsibility of the main power plant and the main FM plant of Guangxi Power Grid.
Yantan's high-pressure gas system is mainly used for aeration and air supply of hydraulic devices.
Each machine is equipped with a hydraulic device and an automatic gas supply cabinet. The rated working pressure is 4MPa. To reduce the relative humidity of the compressed air, the system adopts two-stage pressure supply mode. The rated working pressure of the high-pressure gas storage tank is 6.0MPa. After the pressure reducing valve is decompressed, the pressure oil tank is supplied with gas. The system is equipped with 3 piston air compressors with a rated displacement of 1.0mVtnin and a maximum working pressure of 8.0MPa. All air compressors can simultaneously inflate 0.65 times of a pressure tank to the rated pressure within 2~4h. value. In order to meet the requirements of automatic gas supply for pressure tanks, the system is equipped with one 3m3 high pressure gas storage tank. One air compressor works, and two air compressors are spared, which are on the gas storage tank.
The pressure signal device controls its opening and closing, and the three machines switch to each other. In normal operation, when the oil level of the pressure oil tank is too high, the air is automatically supplied to the oil pressure tank of the unit.
The air compressor is a three-stage three-cylinder air-cooled type, with motor overload, low oil level protection and gas-water separator and its automatic sewage device. The automatic sewage discharge device is composed of a normally closed electromagnetic valve and a sewage pipe of each stage of the gas water separator, and the air compressor automatically vents and discharges when it is turned on. The main technical parameters of the equipment are shown in Table 1. The working principle of the high-pressure air compressor (1) In the suction stroke of the first-stage piston, the atmospheric pressure air enters the first-stage cylinder through the intake air filter and the intake valve. The compression stroke compresses the air to an intermediate pressure and discharges the air through the exhaust valve to the intercooler duct. The pulley fan sends the cooling air to the fin tube of the intercooler, so that the heat generated by the first stage compression is dissipated. .
(2) In the suction stroke of the second-stage piston, the second-stage intake valve is used to suck the cooling air and send it to the second-stage cylinder. The air in the cylinder is further compressed into the air compressor performance of Table 1 and mainly Technical parameters Project name Technical parameters Model type Piston cooling mode Air-cooled drive Three-phase AC motor Run i Splash lubrication stage Number of cylinders Speed ​​Displacement Working pressure Tank capacity Safety valve set value (Level 1) Safety valve set value ( Level 2) Safety valve setting (level 3) Level 1 outlet pressure Level 2 outlet pressure Level 3 outlet pressure Higher pressure. During the compression stroke of the second stage, air is forced into the third stage spire cylinder through the second stage exhaust valve, the second stage intercooler, the condensate tank, and the third stage intake valve. During the third stage spire piston compression stroke, air is compressed to the final pressure requirement, and after air cooling, the chiller and condensate separator are forced to the external system.
(3) The compressor is equipped with a complete start-up unloading system that automatically releases the pressure of the cylinder and intercooler and discharges the condensate in the condensate tank when the compressor is stopped.
3 Equipment Defects Since the No. 1 high-pressure air compressor was put into operation in January 2011, the failure signal of the air compressor lubricating oil frequently occurred, and the oil discharge of the crankcase was removed, and the lubricating oil was found to be black and the water content was large. , seriously affect the stable operation of the air compressor. The main defects are as follows.
On April 15, 2011, the No. 1 high-pressure fan was first serviced. The inspection found that the lubricant was badly deteriorated and returned to operation after the lubricant was replaced.
Out, the on-site inspection "automatic" light is off, press the "start" button, the "automatic" light is on normally, and the fault phenomenon has appeared 2 times. The inspection found that the lubricating oil deteriorated seriously and the water content was large, resulting in a low oil level alarm. After replacing the lubricating oil, adjust the automatic sewage discharge time of the air compressor to 20 seconds for every 2 minutes. (3) Stop the inspection on August 26, 2011, and find that the No. 1 high pressure fan oil is black in color and has a large water content. Replace the lubricant after cleaning.
The water content of the lubricating oil is large, and the double time relay on the control box of the air compressor is re-adjusted. The interval between the automatic sewage discharge is 2 min, the sewage discharge time is 2 min, and the running time of the crushing process is 7 min. (5) February 2, 2012 During the month of June, the No. 1 high-pressure blower was shut down every 2 months, and it was found that the oil inflow phenomenon still exists.
4 Reason analysis (1) The outlet pipe of the high-pressure air compressor is equipped with a check valve. The high-temperature and high-pressure humid air is discharged through the air compressor exhaust valve, and after the post-stage cooler, it still entrains certain oil and water components, although The air compressor's second and third stage interstage coolers and the final stage cooler are equipped with a gas water separator to separate the moisture generated during the compression process, but the actual operation is not satisfactory. Due to the long idle time of the air compressor, the moisture generated by the exhaust gas gathers around the pipeline and the check valve, causing the water to flow back into the interior of the casing, and the moisture content of the lubricating oil is gradually increased, eventually leading to the oil level alarm of the high-pressure air compressor and the shutdown. . When the outlet pipe of the air compressor was removed during shutdown, it was found that a large amount of milky white liquid flowed out in the pipe, which indicates that the air content of the air compressor of the air compressor was seriously exceeded.
(2) According to the operation requirements of the air compressor, the compressor should have a minimum running time to prevent the formation of condensed water, because the condensed water will cause rust in the cylinder valve plate, frame parts and the like. Accumulation of condensate in the crankcase may cause an error in the oil level reading. Water and oil cannot mix, and their co-existence causes the oil to deteriorate quickly. The minimum operating time is generally not less than 10 minutes and should be sufficient to allow the compressor to heat up to vaporize the condensed moisture. At present, the operating time of the air compressor is 7min, which obviously does not meet the requirements.
5 Treatment method (1) For the problem of water ingress into the air compressor of the air compressor, the technician replaces the sealed check valve with excellent sealing, and installs a water separator with high water removal efficiency after the outlet line of the air compressor. As shown. The inside of the oil-water separator is filtered by a precision filter. After the high-temperature compressed air enters the oil-water separator from the inlet a, it is directly separated by the cyclone separation, inertial collision separation and fine fiber filtration, and the water and oil in the compressed air are directly intercepted. c is discharged, and the compressed air after the water is discharged through the outlet b to meet the needs of the high-pressure gas.
The oil-water separator (2) is equipped with an automatic sewage solenoid valve at the bottom of the oil-water separator. The automatic sewage interval is set to 2 min, and the sewage discharge time is set to 5 S. The separation is increased without affecting the normal operation of the air compressor. The sewage discharge time effectively extends the running time of the air compressor to meet the minimum running time requirement of the air compressor. After the trial operation, the air compressor was stopped from the automatic start pressure 4.15~4.40MPa, and the running time was above 11min.
6 The treatment effect was observed after nearly 3 months of operation. The air compressor was in stable operation, the pressure was normal, and no lubricant failure occurred. When the lubricant was changed, the test lubricant was not found to contain moisture and only slightly deteriorated. It can be seen that the operating conditions of the air compressor have been significantly improved, and the defect of the water inflow of the No. 1 high-pressure air compressor has been completely solved. The site layout of No. 1 high pressure air compressor is as shown.
No.1 pressure air compressor on-site layout conclusions In the installation and operation process, various types of defects often appear in the process of installation and operation. The technicians should not analyze from the simple analysis. Only after deep understanding of the structure and performance of the equipment, the equipment should be timely Retrofitting can avoid accidents during operation to ensure safe and stable operation of the equipment.
A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. In some ball check Valves, the ball is spring-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.
Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.
There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with Ball Valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.
A diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.
A swing check valve or tilting disc check valve is check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. The flapper valve in a flush-toilet mechanism is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank Drains and the flapper falls due to gravity. Another variation of this mechanism is the clapper valve, used in applications such firefighting and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure. Another example is the backwater valve (for sanitary drainage system) that protects against flooding caused by return flow of sewage waters. Such risk occurs most often in sanitary drainage systems connected to combined sewerage systems and in rainwater drainage systems. It may be caused by intense rainfall, thaw or flood.
A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.
An in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that will 'lift' when there is pressure on the upstream side of the valve. The pressure needed on the upstream side of the valve to overcome the spring tension is called the 'cracking pressure'. When the pressure going through the valve goes below the cracking pressure, the spring will close the valve to prevent back-flow in the process.
A duckbill valve is a check valve in which flow proceeds through a soft tube that protrudes into the downstream side. Back-pressure collapses this tube, cutting off flow.
A pneumatic non-return valve.
Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
Check Valves, Water Check Valves, Brass Check Valves, Sanitary Check Valves
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