Development and application of the hottest second

2022-09-19
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Development and application of the second generation drum softening pot

softening is a key process in the process of oil processing. In order to achieve the desired softening effect, various manufacturers have developed a variety of softening equipment. At present, softening equipment can be summarized into three categories: the first category is softening box, which has faded out of the market due to too many defects; The second type is vertical softening pot, which has been gradually replaced by other products due to high power consumption, complex manufacturing and maintenance, and dead corners; The third type is the horizontal drum softening pot. The most outstanding advantage of this type of equipment is low power consumption, which is 1/6 ~ 1/4 of the power consumption of the vertical softening pot. Because of its simple structure, stable working performance and low power consumption, the first generation drum softener has won the favor of the majority of users and is widely used by medium and large-scale oil plants in China

1 analysis of advantages and disadvantages

although the first generation drum softener is widely used because of its advantages, the disadvantages of the first generation drum softener are also gradually exposed in production practice: ① because the heating tube is similar to the "squirrel cage" structure, the heating tube expands and contracts under the influence of heating, and the stress at the welding place between the two ends of the tube and the coil is concentrated, resulting in frequent open welding at the welded junction, and the open welding parts are difficult to weld, Steam and condensate flow out of the crack; As a result, the softening effect is poor, and the water removal capacity is reduced. When the situation is serious, it must be stopped for repair; ② The rotary joint often leaks water and steam, and the sealing ring is seriously worn, which is not convenient for maintenance; ③ The condensate in the softening pot is not discharged smoothly, which leads to the reduction of the temperature of the heating tube and the decline of the heating and softening effect on the oil; ④ When starting up, the air in the heating tube cannot be discharged, and the air is enclosed in the heating tube. Due to the poor heat transfer effect of the air, it cannot be discharged in time, which affects the heat transfer efficiency of the heat exchange tube, as shown in Figure 1

1 - transmission gear ring 2 - pot body 3 - heating tube 4 - rotary joint 6 - axial support 7 - body support

Figure 1 the first generation drum softening pot

2 improvement measures

in view of the shortcomings exposed by the first generation drum softening pot, after a long time of exploration and testing, a modified design was carried out. The improved drum softening pot has been applied to production practice and is in good condition. Next, let's talk about the improvement plan of the second generation drum softener

first, in view of the problem that the heating tube end of the first generation drum softener is easy to be welded, the heating tube end of the second generation drum softener is welded to the tube plate of the steam collecting chamber at the discharge end, which is a fixed end. At the feeding end, the heating tube is floating supported on the support plate, the gap between the outer wall of the heating tube and the hole of the support plate is 1mm, and the heating tube can expand and contract freely when heated. The damage to the heating tube and its weld caused by thermal expansion is eliminated. Second, the problems of water leakage, steam leakage and seal ring wear of the rotating joint of the first generation drum softening pot, in addition to the problems of the rotating joint itself, are mainly caused by the non concentricity of the rotating joint, the steam inlet pipe of the softening pot and the softening pot during installation, resulting in the double rotating bodies in the rotating joint, causing the unbalanced wear of the sealing graphite ring and water leakage and steam leakage. This problem is fully considered in the design of the second generation drum softening pot. The steam inlet pipe is welded on the steam collecting chamber of the softening pot, which shortens the length of the steam inlet pipe and enhances the rigidity of the steam inlet pipe. During welding, the concentricity of the steam inlet pipe and the soft polyurethane exemplified pot can be effectively guaranteed. At the same time, the condensate discharge mode is changed, so that the outlet pipe is changed from the original rotation to static, so that the double rotating body in the rotating joint becomes a single rotating body, Thus, nearly half of the failure rate of the rotary joint is reduced, and the problem of water and steam leakage of the rotary joint is effectively solved. Third, the condensate of the softening pot is discharged. Due to the limitation of the rotating joint, the condensate of the first generation drum softening pot will be discharged only when it exceeds the rotating joint, which makes the condensate accumulated in half of the heating line of the softening pot. The heat exchange part between the heating tube and the oil is mainly the middle and lower tube. Condensate is accumulated in the tube. Attention should be paid to the installation of the tube hydraulic universal material testing machine. The wall temperature is affected by the condensate temperature, and the temperature is not high, which affects the temperature rise of the oil, thus affecting the softening effect of the oil and reducing the utilization rate of steam. The siphon drainage device is used in the design of the second generation drum softening pot, which is matched by a siphon and a condensate tank, and the siphon goes deep into the bottom of the condensate tank. The hot steam in the steam heating pipe releases its latent heat, and the condensate flows to the condensate tank in the low-end steam chamber through its own gravity. Under the action of the pressure difference inside and outside the steam chamber, it is continuously discharged from the softening pot through the siphon in the rotary joint and flows into the drainage system. Fourth, when the first generation drum softener works, there will be a certain amount of air in the heating tube, which cannot be discharged, affecting the heat transfer efficiency of the heating tube. In the design of the second generation drum softener, an exhaust collecting ring is added to the floating end of the heating tube, which is connected with the heating tube by an exhaust hose, and an exhaust valve is added to the exhaust collecting ring. The exhaust valve of a foreign company is selected. The characteristic of this valve is that it can only exhaust air, not steam, so that the air in the heating tube can be discharged in time, which improves the heat transfer efficiency

the second generation drum softening pot has also been improved in other aspects: the self softening pot has 6 discharge ports distributed equidistant at the rear of the shell; There is a fixed discharge box (discharge hopper) around the softener shell at the discharge port end of the softener, and there is a flange port on the top of the discharge box to facilitate the discharge of hot gas; In order to prevent steam and material leakage between the feed inlet and the discharge cover during the operation of the rotating cylinder, it is sealed with a wear-resistant sealing belt. What will the sealing belt look like from an aircraft? The fixed clamp plate is clamped and pulled by the spring, which is close to the rotating surface. See Figure 2

1 - connecting hose 2 - exhaust collecting ring 3 - air discharge valve 4 - transmission gear ring 5 - pot body 6 - supporting wheel 7 - heating tube

8 - steam distribution room 9 - rotary joint 10 - siphon 11-6 - axial support 12 - body support

Figure 2 performance comparison of the second generation softening pot

3

through the above improvements, the performances of the softening pot have been improved and good results have been obtained in the production practice of various oil plants. Table 1 shows the comparison of the application of the first and second generation drum softeners

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