The crude oil stored in the crude Oil Storage Tanks contains impurities such as sediment and moisture. These impurities are deposited at the bottom of the tank. On the one hand, the effective volume of the oil storage tank is reduced, and on the other hand, corrosion occurs on the tank bottom plate and the wall plate. oil. Therefore, the crude oil storage tank should be cleaned and repaired according to the regulations 5~7a. With the increase of national crude oil reserves, the number of crude oil storage tanks continues to increase. Traditional manual cleaning methods or semi-mechanized cleaning will be gradually replaced by mechanized cleaning due to problems such as high labor intensity, long construction period, poor safety and environmental pollution. In order to get rid of the adverse effects of manual cleaning on safety, environmental protection and cleaning quality, Pipeline Storage and Transportation Company introduced the world's most advanced crude oil storage tank cleaning equipment in 2005 and put it into use at the end of 2005. The practice shows that the crude oil recovery rate of the equipment is 98% c, the oil content of the discharged water reaches 10x10-6, and the oil content of the discharged waste reaches 3%. Compared with the previous cleaning equipment, the construction cost is reduced by 120,000 yuan (5000m3/seat), and the labor intensity is reduced. 6 times smaller. The composition and use of the equipment will be introduced in conjunction with the cleaning process of Huangdao 14 crude oil storage tank.
1 The cleaning equipment cleaning equipment composition and process flow are as follows, the main components and functions of the cleaning equipment are as follows.
Cleaning device. On the one hand, the cleaning oil is sucked from the oil supply tank and heated, and on the other hand, the cleaning liquid (oil or water) is supplied to the washing machine installed at the top of the oil tank.
Recycling device. The liquid oil is pumped from the tank being cleaned and transferred to a recovery tank. In some cases, when the cleaning tank or other oil tank cannot provide the cleaning oil continuously, the recycling system is used to replace the cleaning equipment composition and the process flow chart cleaning machine. A device installed in the top of the oil storage tank or in the manhole and capable of operating the spray liquid at various angles, with a pressure of 0.7 MPa, an effective injection distance of 14 m, and a flow rate of 80 m3/h. Oxygen monitoring device. During the cleaning process, the oxygen concentration in the cleaning tank is controlled to keep the oxygen concentration below 8% to prevent static electricity generation and prevent the cleaning tank from exploding.
Inert gas generator. The inert gas is produced and the inert gas is delivered to the cleaning tank.
Oil-water separation device. During the warm water cleaning process, the oil and water are separated, the oil is recovered and transferred to the recovery oil tank, and the water is recycled to constitute a mechanized cleaning operation. One of the main parts is to store the cleaning 2-4 in the sewage channel Publish tank. Inject the inert gas body and clean the oil storage tank by 1 (turn down on page 43).
2 cleaning procedures site survey, development of construction plans, drawing process flow diagrams, installation equipment. The Huangdao Oil Depot 14 oil tank is a 50000m3 crude Oil Storage Tanks. There are 2 manholes, 2 agitator holes around the tank body, 80 floating roof pillar holes, and the depth of the precipitated crude oil in the tank is 1.5m. The crude oil has solidified, the top plate and the side plate. The thickness of the attached crude oil is 5 cm, and the 4 oil tanks are located near the 14 oil tanks. According to the survey results, the suction port was determined to be 4, the tank was installed with 22 cleaning machines, and the 4 oil tanks were designated as recovery oil tanks (supply tanks); the cleaning scheme was carried out by crude oil transfer, same oil cleaning, warm water cleaning, and tanks. Clean inside. According to the survey results, a flow chart is drawn, and the cleaning equipment is connected to the 14 oil tanks and the 4 oil tanks according to the flow chart, and the tightness test leak is performed at a pressure of 0.7 MPa.
Crude oil transfer. Since the crude oil in the 14 tanks cannot flow, firstly, the oil with better fluidity is sucked from the four tanks, the crude oil in the 14 tanks is dissolved and melted, and the melted crude oil is transferred to the four tanks. In this process, inert gas should be injected into the 14 tanks to reduce the oxygen concentration to below 8%.
The same kind of oil is cleaned. The cleaning machine is used to spray the crude oil in the four oil tanks into the 14 oil tanks, so that the sludge in the oil tank is dissolved and dispersed, and the residual amount of sludge in the oil tank is minimized, and the inside of the oil tank is attached to the top plate and the side plate and The dirt on the accessories is washed away. The flow is 4 oil tanks, a cleaning device, a 14 oil tank, a filter, a recovery device, a 4 oil tank. The main data of cleaning are shown in Table 1. Table 1 The same kind of oil cleaning Main data cleaning Oil return oil Washing pump outlet Washing machine Washing machine Washing machine Each group of moving running total azimuth temperature rc temperature / e pressure / MPa injection angle actuating order time /h time / h tank bottom plate 1000 a middle tank top plate 1000-.1400 periphery a middle all-round 1400 middle one peripheral warm water cleaning. After the same kind of oil cleaning, after most of the crude oil in the 14 oil tanks is recovered, the warm water washing is started, and the warm water washing is sprayed to the entire inner surface of the cleaned oil tank (from the tank top to the tank bottom plate) by circulating hot water. 80m3 of clean water was injected into 14 oil tanks for self-circulation. During the cycle, the oil in the water was continuously separated and recovered into 4 Oil Storage Tanks by automatic oil-water separation device. The process is 14 oil tanks, a filter, a cleaning device, and a 14 tank. The main data of cleaning are shown in Table 2. Table 2 Warm water cleaning Main data cleaning Oil return oil cleaning pump Outlet cleaning machine Each group dynamic running total azimuth temperature / e pressure / MPa injection angle action sequence time / h time / h tank bottom plate 4 1000 in the middle of a peripheral full range of 400-1400 in the middle of a peripheral sewage treatment. The sewage treatment device is used to treat the sewage generated during the warm water cleaning process. The process is 14 tanks, filtered and ventilated. Through warm water cleaning, the oil in the 14 tanks is completely recovered, the inner surface of the tank is cleaned, and all manhole covers are opened for natural ventilation. After the air quality in the tank meets the safety requirements, the original materials remaining in the cleaning tank, such as rust, gravel, wood, rubber, etc., are cleaned.
Waste oil residue, sewage treatment. The dirt removed from the 14 oil tanks, the dirty oil generated by the filter during the cleaning process, and the sediment deposited by the oil-water separation device are placed in the waste oil residue treatment device, and the soil reducing agent is added in a ratio of 1:1 to be sufficiently stirred.
Dismantle the equipment, temporarily lay the pipeline, and restore the 14 tank attachments.
3 cleaning operation critical control point cleaning machine installation position and depth. The control point determines whether various parts of the tank can be cleaned. Therefore, the distance between adjacent washing machines is controlled within 13m, and the nozzle insertion depth should be determined by calculation to ensure that the effective cleaning area of the washing machine covers the entire bottom plate or top plate. . When the 14th Oil Storage Tanks is cleaned, the cleaning machine is installed in the hole of the floating roof column, and the distance between the cleaning machines is 10~13m. When the bottom plate is cleaned, the nozzle part of the cleaning machine is 1. 4m away from the bottom plate. Partly 0.3m from the bottom plate. Accurately judge the end and start of each program. This control point determines whether the tank can be cleaned and affects the cleaning cost. If the cleaning is terminated too early, the tank cannot be cleaned. If the cleaning is too late, the cleaning cost will be increased. The judgment is based on the depth of the crude oil in the tank, the fluidity and the thickness of the crude oil attached to the inner surface of the tank. At the beginning of the same kind of oil cleaning, the depth of the crude oil in the 14 oil tanks is 0.1~0.4m, and the fluidity is poor. After the cleaning of the same kind of oil, the depth of the crude oil in the 14 tanks is 0. The fluidity is good, the middle part of the tank bottom and the tank top No crude oil is attached. After the warm water washing is finished, the water depth of the tank wall near the tank wall is 0.05m, and the remaining parts are exposed to metallic color.
Control the oxygen concentration. This control point determines the safety of the washing tank. The oxygen concentration must be controlled within 8% throughout the cleaning process, otherwise the cleaning should be stopped.
Suction port height. This control point affects the cleaning speed and cleaning quality, and the suction port height is adjusted during the cleaning process. When cleaning 14 oil tanks, the suction port of the crude oil transfer stage is 300mm from the bottom plate, the cleaning stage of the same kind of oil is 120mm from the bottom plate, and the warm water cleaning stage is 70mm away from the bottom plate. 4 Safety measures taken in terms of safety, environmental protection, cost and labor intensity. In order to prevent the oil tank from exploding during the cleaning process, the equipment uses an inert gas generator to generate an inert gas, which is continuously injected into the cleaning oil tank. The oxygen concentration in the Oil Storage Tanks is controlled within 8% to ensure the safety of the cleaning operation.
The couple of the 8-type combined rotary compensator consists of three rotating cylinders and two left and right L pairs. The calculated L arm length is the minimum value and can be appropriately enlarged (reduced H angle) to reduce the thrust during expansion. The force P of the 8-type combined rotary compensator is determined by the following formula: 2 Things to be aware of when using it For long-distance installation, pay attention to the length of the tube bracket of the sliding and guiding bracket. The farther away from the fixed bracket, the greater the thermal displacement. Choose a tube holder that is long enough to prevent the tube from being tripped. In addition, the pipe support needs to be pre-biased in advance in the opposite direction of the thermal expansion of the pipe. Generally, the pre-bias amount is half of the thermal displacement of the pipe design.
In order to reduce the frictional thrust of the fixed bracket, if possible, use a rolling bracket. In order to ensure the safety of the entire pipe network, it is necessary to install a guide bracket in a certain pipe section.
Since the rotary compensator has a certain lateral displacement during the swinging process, it is preferable that the brackets closest to the compensator are not provided with guide brackets that limit the lateral displacement.
Although the absorption thermal expansion value increases with the rotation angle H or the force couple arm L, in order to limit the y swing too large, it is preferable to select L as 2~ although the rotation compensator compensation amount is very large, for safety, the arrangement is as far as possible Do not be too long. When the design temperature does not exceed 300 °C, the pipe should not exceed 450 m. If the design temperature exceeds 300 °C, the arrangement spacing should be reduced accordingly.
Try not to use the 8-type combined rotary compensator. Although it has a larger compensation than the 0-type combined rotary compensator, a spring bracket is added to the vicinity of the compensator when it is arranged, but if the pipe diameter is large, The height of the space is high, and it is still possible that the bending compensator of the local pipe is too large to cause damage to the rotary compensator.
When the pipeline is laid underground (ground trench or direct burial), the hydrophobic scheme must be fully considered. Especially when the hydrophobic point is near the rotary compensator, the steam trap should be avoided as much as possible due to the vibration of the pipeline.
3 Conclusion Compared with the traditional compensators, the rotary compensator has obvious advantages in long-distance pipelines. If it is used properly, it can play a huge role, saving money, simple construction, and improving the safety of the pipe network. The first object of choice when designing a heat pipe.
Warm design.
