Abstract: During the production process of the separator, in order to prevent production accidents caused by the inaccuracy of the level gauge, the processing station regularly organizes personnel to clean and maintain the level gauge. There are potential risks of working at heights. Through the development of the separator level gauge flushing device, it can be completed by one person in 15 minutes without stopping the separator, and the risk of high-altitude operations has been eliminated and good results have been achieved.The centralized treatment station is an important part of the oilfield surface gathering and transportation system. It is a comprehensive station library for oil-gas-water separation, crude oil purification, natural gas treatment, and sewage treatment for the mixed liquid delivered by several metering stations or transfer stations. The oil and gas two-phase separator is the front-end device of the crude oil processing system. At present, the magnetic flap level gauge is widely used in the separator level gauge. The magnetic flap level gauge uses the liquid level sensor on the basis of the on-site real-time display of the level of the separator. It can be remotely monitored in the central control room and linked with the on-site pneumatic valve to realize automatic control of the liquid level of the separator. The accurate and reliable display of the level gauge is the basic guarantee for the various parameters of the crude oil processing system.1 Questions1.1 The structure and principle of the level gaugeThe magnetic flap level gauge is composed of a water bag, a magnetic floating ball, a cavity for holding the floating ball, a flap box (red and white two-color magnetic small flap), etc. The cavity of the level gauge forms a communicating device through the downstream pipeline of the level gauge, the flange and the water bag. The water bag with the upper opening is installed at the bottom of the separator, and the light salt water added in the water bag is to ensure that the measured medium is isolated from the display mechanism. The water bag will soak in the oil-water mixture for a long time, and there will be sludge and other impurities deposited, which will easily cause the connecting pipeline between the level gauge and the water bag to be blocked. If more viscous dirty oil enters the cavity of the level gauge, it is easy to cause the floating ball to move up and down and block, resulting in inaccurate display of the level gauge, which may cause serious accidents such as gas line oil blow-by in the separator. (see picture 1)1.2 The flushing operation of the level gaugeIn order to ensure the accuracy and reliability of the liquid level display of the level gauge, the centralized treatment station must regularly organize personnel to add water to the level gauge to prevent the connection pipeline between the level gauge and the water bag from being blocked, and replace the sewage and float in the outlet water bag with dilute salt water. Oil to ensure that the level gauge display is accurate and reliable. However, there are the following problems in the washing process: First, the operation steps are cumbersome, the separator must be disabled, and it takes a long time; the second is that the operation needs to climb to a height of more than 2 m to work; the third is that at least 4 people are required to complete it.Before the level gauge is flushed with water, the separator is first stopped by the operator. After completing various safety measures, the operator set up a ladder to close the up and down valves of the level gauge, then opened the lower valve of the level gauge to vent the level gauge and closed it, then removed the upper plug of the level gauge, and one person escalated the ladder. , One person delivers water, one person fills the level gauge cavity from the upper plug with water and tightens the plug, then opens the up and down flow valve of the level gauge to back pressure the water in the level gauge cavity into the water bag.Commonly used magnetic flap level gauges in centralized treatment stations have a cavity diameter of 50 mm and a height of 2 m, a water bag diameter of 300 mm, and a water bag height of 0.3 m. These can be calculated to clean and replace the liquid gauge and the water inside the water bag. The required amount.Volume of Level Gauge Chamber:After calculation, the volume of the water bag is 5.4 times the volume of the cavity of the level gauge, so every time the cavity of the level gauge is filled with water, the operation steps of pouring the water from the cavity into the water bag need to be repeated at least 6 times. The operation time is about 13 minutes each time, and the operation process of cleaning and replacing a separator level gauge and water bag takes more than 1.5 hours. The work efficiency is low and there are hidden safety hazards.2 Development of the flushing device for the level gauge of the separator2.1 Design ideasA set of level gauge flushing replacement device is installed in the separator operation room. The pressure balance valve 5 of the device is connected to the upstream pipeline of one of the separator level gauges through a pipeline; the water outlet valve 6 of the device is connected to several others through the water outlet pipeline. The downstream pipeline of the separator level gauge is connected, and a set of level gauge flushing device can meet the flushing requirements of multiple separator level gauges in the same operation room. In order to ensure the integrity of the equipment, the main structure of the separator and the level gauge is not changed or welded. Only three-way and control valves are installed between the separator and the upstream and downstream flanges of the level gauge to flush and replace the device with the level gauge respectively. The pressure balance valve is connected to the outlet valve (see Figure 2).When the level gauge is flushed and replaced, first open the vent valve 4 and the water filling valve 3 to fill the device with dilute salt water, close the water filling valve 3, the vent valve 4, and then open the pressure balance valve 5 of the device to ensure the pressure in the device and the separator The internal pressure is balanced; then open the water outlet valve 6 and the water inlet valve 7 of the level gauge to be flushed. Using the principle of level difference, the water in the device can enter the level gauge water bag from the downstream pipeline of the level gauge, and the water The medium in the bag is replaced into the separator to complete the flushing inspection of the downstream pipeline of the level gauge and the replacement of the medium in the water bag, so as to achieve the purpose of flushing and checking the level gauge (see Figure 3)2.2 Implementation planAfter approval by the technical department and safety department of the unit, and a technical change plan issued, a professional team will make a flushing replacement device for the level gauge. In order to ensure the effect of flushing and replacement, the water holding capacity of the main body of the device should be greater than the water holding capacity of a level gauge water bag; the upper part of the main body of the device is equipped with a vent valve, a water filling valve and a pressure balance valve, and a water outlet valve and a low liquid level observation valve are installed at the lower part. ; The flushing device is placed in the separator operating room, which can meet the flushing conditions of multiple separator level gauges; the installation height of the device is higher than the level of the separator level gauge; in order to facilitate the operation of adding water to the inside of the device, a supporting operation is provided platform.2.2.1 The main structure of the flushing deviceUse φ2197mm spiral steel pipe production, pipe designThe pressure bearing is 1.6MPa, which is much higher than the working pressure of the separator (0.3MPa).The safety of the barrier device.Theoretical calculation basis:Device diameterD = φ219 7 = 219-7 2=205mm=0.205m (4)Refer to relevant specifications: the design capacity of the device should be greater than 1.2~1.5 times the volume of the water bag itself.Flushing device volumeThe device capacity V3 (49.48L) is greater than the total water volume of the level gauge water bag V1 (21.195L), and all the media inside the water bag can be replaced and cleaned again.2.2.2 Equipment pipelines, valves and other accessoriesUse φ263 mm seamless steel pipe, DN20 fast ball valve and other accessories. The design pressure of pipelines and valves is 1.6 MPa, which is much higher than the working pressure of the separator (0.3 MPa), which guarantees the safety of the device. The fast ball valve is easy to open and close, and can quickly press the water inside the device into the water bag.2.2.3 Operating platformSteel pipes, steel plates, and angle irons are selected for firm welding, safe and reliable, and easy for personnel to operate. After measurement, the working liquid level of the separator is 1.7 m from the ground, and the installation height of the device only needs to be greater than the working height of the liquid level of the separator to smoothly press water. In order to facilitate the operation of personnel, the height of the operating platform is determined to be 1 m based on the personnel height of 160~180 cm (see Figure 4).3 Field application3.1 Job effectAfter the level gauge flushing device was installed in the separator operation room of the centralized processing station, it was verified by many on-site operations and achieved good results.In the process of adding water and washing, there is no need to stop the separator to ensure safe and stable production; operation on the working platform eliminates the risk of high-altitude operation; the operation time is reduced from 1.5 hours to 15 minutes at present, which improves work efficiency; The 4-person operation is reduced to 1~2 person operation, which reduces the number of operations and reduces the labor intensity of employees. (See Figure 5).
3.2 Benefit evaluationSave operation labor costs:The average labor cost is 180 yuan/day, and each megaton-level centralized processing station is equipped with an average of 4 separators, and each separator cleans the replacement liquid level gauge and water bag once a month on average, and each time 4 people operate it for 1.5 hours. The annual labor costs for the cleaning and replacement liquid level of the separator in each processing station and the water bag are:4 sets 4 people/time 1.5 hours 12 times/set ·year 180 yuan/day·person÷8 hours/day=6480 yuan/year; renovation cost: labor cost 320 yuan + material cost 730 yuan = 1 050 Yuan; annual savings in operating costs: 6480 yuan-1 050 yuan = 5 430 yuan.4 resultsThe development of the cleaning device for the level gauge of the separator. During the flushing process of the level gauge, the separator does not need to be stopped, and the pressure balance principle of the communicating device is used to complete the rapid flushing and replacement of the level gauge and the sewage in the water bag, thus realizing the flushing. The real-time display and remote control of the liquid level of the separator in the process also shorten the washing operation time, reduce the number of operators, reduce the labor intensity of employees, improve work efficiency, and transform high-place operations into routine operations, eliminating high-altitude operations The hidden safety hazards in the operation provide a guarantee for safe production and have a good promotion value in the oilfield surface gathering and transportation system.
Post time: 21-09-21