Letter E engineering technology coal mine underground abrasive water jet cutting machine cutting performance test study bookmark0 Shao Quanjiang 1 Hou Yong 2 Lu Fengfeng 3 Zhao Wei 3bookmark1 (1. Shanxi Orchid Branch Chuangwang Coal Mine Branch 2. Xuzhou Zhongyu Yonghong Technology Co., Ltd. 3 China University of Mining and Technology (Xuzhou) School of Electric Power Engineering) bookmark2 uses a self-designed coal mine underground abrasive water jet cutting system to cut steel plates.

Grade material state strength limit -b (MPa) yield limit rate section shrinkage Brinell hardness 45 annealed steel>Cutting speed and cutting depth and cutting efficiency curve Table 3 Effect of cutting speed This test mainly discusses different cutting parameters (drive The influence of pressure, cutting speed, cutting target distance and abrasive flow rate on the performance of abrasive water jet cutting.

It can be seen from the above figure that the cutting speed and the cutting depth change inversely, and the cutting speed is larger, and the cutting depth is smaller. The cutting efficiency and the cutting depth change in a convex curve relationship, and the cutting speed is increased, and the cutting efficiency is first increased, and gradually decreases after reaching a certain value. It can be seen that the cutting speed is not as small as possible. Considering the influence of cutting depth and cutting efficiency, there is an optimum range of cutting speed. Under the conditions of this test, the optimal cutting speed is 80mm/min. The influence of cutting target distance refers to the distance between the outlet of abrasive water jet nozzle and the material to be cut. It is an important factor affecting the cutting of abrasive water jet. parameter. In the test, the cutting speed was 80mm/min, the driving pressure was 30MPa, the abrasive flow rate was 3.2kg/min, and the cutting target distance was set to five grades of 5, 10, 15, 20 and 25mm respectively, and the cutting target distance to the cutting depth was examined. Influence, the experimental results are shown in Table 4. (Continued on page 368) Table 2 The influence of driving pressure The driving pressure (MPa) 101520253035 The maximum depth of one cut (mm) 5931662023 The driving pressure is an important parameter affecting the cutting performance of abrasive water jet cutting machine It reflects the ability of the abrasive jet to destroy the material being cut. When ignoring pressure losses in the lines, valves, and mixing chambers, the drive pressure is approximately equal to the jet pressure of the nozzle. During the experiment, it is an important basis for realizing safe production to maintain the transformation measures of the technology information engineering technology heating equipment. In order to safely transport oil production in the Zhongluo line, the existing heating equipment should be updated. The future operation of the Zhongluo line can be used for direct heating or additive transportation of crude oil, and the updated equipment should meet the load requirements of various transportation modes. Therefore, the heating equipment of Zhongluo Line should be updated as soon as possible, and the 2500kW and 5000kW direct heating furnaces produced by Huadong Petroleum Machinery Plant should be used for the oil production of Zhongluo Line. The thermal efficiency will reach 90%, and the small hot water for heating and heating of each station will be added. Boiler, used for heating and winter living, to ensure safe and smooth operation of oil production, improve operating efficiency, reduce maintenance costs, strengthen infrastructure, and improve technical equipment.

After updating the 2500kW and 5000kW direct heating furnaces produced by Huadong Petroleum Machinery Plant, the safety performance and operation efficiency of the equipment can be obviously improved. The furnace type is highly automated, and can be connected with the station control system to facilitate the operation and control of the heating furnace.

Renovation of heating equipment demonstrates that if Zhongluo Line can gradually replace the advanced and efficient heating furnace type in recent years, it will ensure the safe and stable operation of oil production, improve the overall technical equipment level, and save a lot of equipment maintenance costs. Recovering equipment investment in a relatively short period of time is reasonable and beneficial in terms of economic benefits.

The crude oil of the direct heating furnace directly enters the high temperature furnace to absorb heat, the crude oil has a low flash point and a low ignition point, and has a high freezing point. It belongs to Class A B flammable liquid and has a high risk of fire; the moisture present in the crude oil has corrosive effect on the furnace tube, and the crude oil The colloid, asphalt, salt content is high, the thermal stability is poor, and it is easily cracked and decomposed after heating, coking in the furnace tube, affecting the heat transfer effect, causing local overheating, and fires such as bursting due to corrosion or local overheating. Accidents will directly threaten oil production.

The heat medium furnace adopts a heat medium with good thermal stability at a higher temperature, which can avoid the coking of the furnace tube, has no corrosive effect on the metal, the crude oil system does not enter the furnace, and the furnace heating is two independent systems, and the furnace enters the furnace to absorb heat. The hot medium has a high flash point and a low ignition point and a low freezing point. It is a Class B flammable liquid and has a relatively low fire risk.

Therefore, from the point of view of the physical properties of the medium, the heat medium furnace is safer than the direct heating furnace. However, due to the above problems in the heat medium furnace, it is still difficult to solve the problem effectively, which will directly hinder the further promotion of the heat medium furnace. The direct heating furnace system is simple, low in cost, easy to operate, and easy to maintain. As long as sufficient measures are taken, safe production can be achieved.

The safety measures mainly include the following aspects: strict quality control: the heating furnace should be manufactured in accordance with the safety of the oil industry-95 and the construction and acceptance specifications of the heating furnace. The design unit shall obtain the approval of the pressure vessel design unit, and the manufacturing unit shall obtain the pressure vessel manufacturing license. The material used for the heating furnace must have a quality certificate. The depth of corrosion, pitting or scratch on the surface of the pipe shall not exceed 1/2 of the negative deviation of the thickness of the pipe. Valves, pressure gauges, thermocouples and other accessories shall be tested and calibrated one by one. . Set the control system and over temperature and fire alarm to automatically cut off fuel when auto-ignition and flameout. The furnace tube is made of high temperature resistant seamless pipe, and the butt weld is subject to 100% non-destructive testing.

After the furnace is installed, the hydrostatic test is carried out and the leaks are checked at each joint.

The water pressure test water should be higher than the ambient dew point temperature to prevent condensation on the furnace tube. The water pressure should be slowly raised and lowered. When the water pressure rises to the working pressure, the pressure should be suspended, check for water leakage or abnormality, stabilize for 5 minutes, then rise to the test pressure and store for 5 minutes, then reduce to working pressure. an examination.

Strictly implement the inspection procedure: the inspection of the heating furnace must strictly follow the inspection procedure of the heating furnace, and must conduct a periodic shutdown inspection every year; perform a hydraulic pressure test in 6 years; at any time when an abnormal situation occurs, and have an inspection report. The surface of the radiant furnace tube and the convection furnace tube shall be flat, and no circular cracks of any depth shall be allowed. The geometric deformation shall not exceed the allowable value.

The repair of the heating furnace shall be carried out in accordance with the heating furnace repair procedure. After the burner is assembled, the axes of the main components shall coincide, and the deviation shall not exceed 2 mm. Check and measure the corrosion of the furnace tube, and treat according to the corrosion condition, for the severely corroded furnace tube Replace it and make sure that the tube is safe to use under normal working pressure. Carefully organize the acceptance of the repaired furnace.

Careful operation: strengthen operation management, control furnace and exhaust gas temperature, furnace temperature does not exceed 800C, weaken high temperature oxidation corrosion; exhaust gas temperature is not lower than 130C, to prevent low temperature acid mist condensation corrosion. Because of the sulfur content in the crude oil, it becomes S2 after combustion, and is further oxidized to S3. The combination of SO3 and water vapor is H2S4, which corrodes the surface of the steel. Control the temperature rise and decrease speed, soak the ash in time, and close the door of each part during normal operation. There is a water hammer protection pressure relief valve in the station. The operation of the heating furnace strictly implements the operation rules of the tubular light heating furnace.

Strengthen maintenance: If the furnace is shut down for more than 30 days, it should be cleaned in time, and dry maintenance should be done to prolong the service life of the furnace.

Formulate an emergency plan: set up an emergency venting valve, and formulate detailed and targeted emergency plans for crude oil vaporization accidents, tempering and explosion accidents, furnace tube burn-through accidents, and furnace explosion accidents in the furnace tubes. Emergency shutdown should occur when there is a critical condition in the operating procedures.

The height of the heat medium furnace chimney is 10m, which is unfavorable for the spread of smoke and dust. The smoke emission of the above type of heating furnace is up to standard discharge, and the height of the chimney is up to 30m. It has successfully passed the demonstration of the environmental impact assessment department.

Through the above analysis and comparison, it is proved that the replacement of the Zhongluo line heat medium furnace into a direct heating furnace can meet the requirements of the full-line thermal parameters and ensure safe and smooth oil transportation. At the same time, it is feasible and beneficial to reduce maintenance tasks and save maintenance costs.

(Continued from page 366) Table 4 Effect of cutting target distance Cutting target distance (mm) 510152025 Maximum cutting depth (mm) 152013107 Table 5 Influence of abrasive flow rate With the reduction of cutting target distance, the cutting depth is gradually increased first When the target distance is reduced to a certain value, the target distance is continuously reduced, and the cutting depth is decreased. This is mainly because the abrasive jet has a constant velocity core zone near the nozzle outlet, and the jet energy is larger in this zone, and the cutting ability is stronger. As the cutting target distance increases, the disturbance of the abrasive jet and the surrounding environment medium is enhanced. The jet flow rate is reduced, so that the kinetic energy of the abrasive particles is reduced, the cutting depth is reduced, and the cutting ability is lowered. However, the smaller the cutting target distance is, the smaller the cutting target distance is, and the abrasive jet splashing is severe, which will reduce the cutting depth, so there is an optimal cutting target distance. The test results in the above figure show that under the conditions of this test, the optimal cutting target distance is 10mm. 3.4 The influence of abrasive flow rate The amount of abrasive flow mainly reflects the amount of abrasive particles in the jet and the abrasive particles to the material being cut. Impact frequency, abrasive flow not only affects the depth of cut, but also has a large impact on abrasive consumption and cutting costs.

The best values ​​of the previous rounds were selected: cutting speed 80mm/min, driving pressure 30MPa, target distance 10mm, keeping other parameters unchanged. Under different abrasive flow conditions, the cutting results are shown in Table 5. Abrasive flow Q (kg /min) As can be seen from the above figure, the abrasive flow rate and the cutting depth change in a convex curve relationship, that is, as the abrasive flow rate increases, the cutting depth first increases, and after a certain value, the cutting depth gradually decreases.

Therefore, there is an optimum range of abrasive flow rates, giving the abrasive jet a greater depth of cut. The test results show that under the conditions of this test, the optimal abrasive flow rate is 3.2kg/min. Because the abrasive flow rate increases, the amount of abrasive sprayed from the nozzle per unit time increases, and the impact frequency of the material to be cut increases. Large, so that the cutting depth of the material to be cut is increased. However, due to the limitation of the diameter of the nozzle, the abrasive flow rate cannot be excessive. If the abrasive flow rate is too large, the abrasive particles become crowded and collide and interfere with each other, so that the number of effective impacts on the material to be cut is reduced, so that the impact resistance of the abrasive particles on the material to be cut is weakened. It will block the nozzle and affect the cutting. In addition, the abrasive flow rate is too large to increase the abrasive consumption, thereby increasing the cutting cost. Therefore, there is an optimum range of abrasive flow.

It can be seen from the above test results that it is feasible to cut the steel by the coal mine underground water jet cutting machine, and the following conclusions can be obtained: the driving pressure and the cutting depth are linearly changed. As the driving pressure increases, the underground grinding water of the coal mine The depth of the cutting steel plate of the jet cutting machine is gradually increased, and the cutting ability is gradually improved. With the increase of the cutting speed, the depth of the cutting steel plate of the coal mine underground water jet cutting machine is gradually reduced, and the cutting efficiency is increased first, then gradually Reduced. Considering the cutting depth and cutting efficiency, there is an optimum range of cutting speed; there is an optimum value for the cutting target distance, so that the abrasive jet can exert the strongest cutting ability; (4) With the increase of the abrasive flow rate, the underground mine abrasive water jet cutting The depth of the machine-cut steel is first increased. After a certain value, the cutting depth decreases as the abrasive flow increases.

Therefore, there is also an optimum value for the abrasive flow.

In summary, under the condition of nozzle diameter of 1mm and abrasive of 60kg, the optimal parameter combination obtained by this cutting test is: driving pressure 30MPa cutting speed 80mm/min cutting target distance 10mm, abrasive flow rate 3.2kg/min.

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