At present, the domestic rail light tanker truck loading and unloading oil are used in the upper part of the unloading method, the unloading process summed up in the following three: First, the vacuum unloading process; second volume pump assisted centrifugal pump unloading process; Third Submersible pump unloading process. This paper introduces a new technology for unloading oil with a rotary piston pump for future use in new and modified oil depots. Introduction to the existing unloading process 1, the vacuum unloading process The vacuum system using oil filling irrigation, cleaning warehouse and pumping emptying tank oil operations. The system requires more equipment, such as water ring vacuum pump, vacuum tank, vacuum lines, etc., and the vacuum pump water also consider winter frost problems. In addition, vacuum pump work, the exhaust pipe often have a lot of oil and gas discharge, it is not safe, so the current process has been rarely used in the depot. 2, the volume pump auxiliary centrifugal pump unloading process uses a positive displacement pump to replace the vacuum system, to achieve the centrifugal pump oil and sweep warehouse. The system is currently used more, especially for diesel and aviation oil products. The volumetric pump used is usually a vane pump or a swinging rotor pump. The application of the system should be noted that, in the sweep process, due to the presence of oil and gas mixed transmission case, the pressure of the pump outlet will be far lower than the pump rated value, so you must set the sweep tank or low empty tank, Otherwise it will not work properly. 3, submersible pump unloading process Submersible pump unloading process has two programs: First, low-lift submersible pump and the main oil pump work in tandem with the unloading process. Second, high-lift submersible pump directly into the tank unloading process. The advantages of the process scheme are the high unloading reliability, short working time, no need to worry about the problem of gas tube resistance and pump cavitation, and is particularly effective for high temperature unloading of gasoline in the plateau area. The disadvantage is the higher operating costs of investment, due to crane mouth equipped with submersible pump, the operation is not convenient. In addition, the program can not be omitted warehouse cleaning system, the setting method with centrifugal pump unloading process. The new technology of unloading rotary piston pump unloading process: rotary piston pump is a positive displacement pump, with low speed (400 r / min), strong suction capacity (maximum vacuum of 0.085MPa), high efficiency (0.7 ~ 0.85) , Can be two-phase gas-liquid transport, low impurity characteristics of the filter. Because of its super self-priming capability, there is no need to set up another pump for its oil filling pump when unloading the truck. Because of the liquid that can transport the solid particles, the impurities in the cleaning operation have little effect on it. In the unloading process, just set a rotary piston pump to complete unloading, cleaning warehouse, pipeline venting, emptying cans and other oil pumping operations. As a result, the equipment and facilities such as the cleaning canister, the cleaning pump and the cleaning line are omitted, which not only saves the investment but also facilitates the operation and management. It is an ideal and economical new unloading technology. The unloading process has two options to choose from: First, all crane share a large flow rotary piston pump; the advantages of this program is investment in the province, less equipment, easy management. The program is suitable for unloading traffic between 100 to 200m3 / h, unloading more time than the situation. Second, the pump is located under the trestle, according to a group of three crane, each with a small flow (60 ~ 80m3 / h) rotary piston pump. Unloading oil, all pumps can work simultaneously, which not only meet the requirements of large flow, fast unloading, unloading a train can be completed within three hours; and to avoid the unloading to the end, due to insufficient flow pump vibration problems. Suitable for unloading a short time, large flow and lift is not high. Application Example 1, Hunan 154 oil depot rail sweeping warehouse, the tank car to the end of the oil into the tank emptying 1000m3, trial run in the reservoir commissioning, the first vane pump, the results can not work properly. After the switch to the swing rotor pump, to complete the cleaning operation, but the suction speed is slower, longer cleaning operation time; and the filter is often blocked before the pump, and sometimes the job should stop pump cleaning filter on the way. Rotary piston pump in 2005 to carry out the operation of the cleaning of gasoline, not only pumping speed, but also eliminates the need for frequent cleaning filters, the effect can be compared with the past, the United States vacuum system. 2, PetroChina Hubei Yingcheng depot, the use of rotary piston pump unloading, diesel, six crane share a pump, oil, unloading into the tank, the pump is completed a homogeneous pump, there is no sweeping system, or even pumping station nothing. The depot was put into operation at the end of 2005 and has been in good use so far. 3, Anhui 352 oil depot generation storage system is also used by the rotary piston pump pump unloading oil cleaning process; the trial run, well. Conclusion In summary, the use of rotary piston pump unloading oil can be a pump to complete the oil filling irrigation, unloading, cleaning warehouse, pumping the bottom of tank emptying oil and other operations; the required equipment, investment, simple operation, Easy management, it is worth to promote a new oil discharge process.
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