1 Application of the mouth-filling technology The rigid polyurethane foam anti-corrosion insulation pipe (commonly known as jacket insulation pipe) is widely used in domestic and international petrochemical, urban thermal supply and other industries for its excellent anti-corrosion and thermal insulation properties. The reason is that the rigid polyurethane foam has excellent thermal insulation properties (its thermal conductivity is 3W/mt, high-density polyethylene plastic pipe has high strength (tensile, shear strength can reach 18~22MPa) and very The great elasticity, the organic combination of the two, is theoretically an ideal way of insulation.
Since the protection, insulation and anti-corrosion layer of the main pipe are prefabricated by special equipment in the factory, the quality of the protective layer and the anti-corrosion coating is relatively reliable. Therefore, the key to determine the final anti-corrosion performance of the pipeline is the quality of the protective layer (ie, the interface between the outer polyethylene and plastic pipes). If the quality of the mouth is not good (such as the seal is not tight at the mouth, the strength of the mouth is low, etc.), it will produce thermal deformation in the lower groove or in use of the pipe, cracks or gaps will appear at the mouth, and the groundwater can penetrate the inner layer. , destroy the thermal insulation properties of polyurethane foam. What's more, water can dissolve soluble ions in the insulation layer (polyurethane foam), forming an acidic corrosive environment, which further accelerates the corrosion of the pipeline and seriously affects the safe operation and service life of the pipeline.
At present, in the rigid polyurethane foam anti-corrosion insulation pipeline polyethylene protective layer filling method, the following three commonly used: heat shrinkable sheet (set) method. In the method, the heat shrinkable sleeve or sheet is baked by flame, which is heat-shrinked and clamped with the polyethylene protective layer of the prefabricated pipe section at both ends. The utility model has the advantages of simple structure and convenient construction; the disadvantage is that the quality of the on-site filling is not easy to guarantee, and the filling strength is low.
Hot melt method. In this method, the patch sheet (polyethylene sheet) is laminated with the polyethylene protection by a clamp, and then the heating sheet is heated to fuse the patch sheet with the polyethylene protective layer. The advantage is that the filling strength is improved compared with the heat shrinking method; the disadvantage is that the shrinkage sheet has no shrinkage property, and the rigid fixture for pressing has poor stretching performance, which affects the sealing performance of the interface.
Plastic welding method. The plastic welding method uses a plastic electrode to weld the patch (or sleeve tube) and the polyethylene protective layer together. The advantage is that the construction process is simple; the disadvantage is that the weather is greatly affected by the construction, the welding quality is not easy to guarantee, and at the same time, the strength of the welded portion is much lower than that of the hot melting method because of the small sintering area.
In short, over the years, scientific and technological workers at home and abroad have never interrupted the research on the technology and methods of rigid polyurethane foam anti-corrosion insulation pipe. The first is to corona the jacket tube during the pre-fabrication process of the tube-in-tube method, and increase the polarity of the polyethylene jacket tube so that the foam layer and the jacket tube can be closely bonded together to prevent the "two-layer skin" phenomenon; Add a special-shaped waterproof cap at each end of each pipe section to prevent water vapor from eroding from the joint to the middle of the pipe; then increase the temperature-sensing line on the surface of the heat-shrinkable material, that is, change the color when the heating temperature reaches the specified temperature, thereby avoiding heating The unevenness of the temperature is too high or too low to ensure the molding quality of the heat shrinkable material. However, these improvements cannot fundamentally overcome the shortcomings of the general patching technique.
2 Principle of Electrothermal Melt-Compression Composite Filling In response to the defects and shortcomings of various commonly used filling methods, Jidong Oilfield Design Engineering Co., Ltd. and China Petroleum Group Engineering Technology Research Institute jointly developed a rigid polyurethane foam anti-corrosion insulation pipe. The electrothermal fusion shrinkage compound filling technology has also successfully developed the DD-1 type electric heat fusion shrinkage compounding tape, and has been applied for national patent.
The filling method integrates the functions of sintering and shrinking, and effectively solves the problem that the tightness and the strength of the rigid polyurethane foam anticorrosive insulation pipeline can not be balanced.
The principle is to use a special power source to heat the electric heat fusion compounding band, so that the composite band is sintered under the action of the special elastic clamp and the hoop tightening force formed by the heat shrinking of the mouth band itself, and the polyethylene protective layer. Form a whole.
Since the patch belt adopts special heating and sintering materials, the line contact of the fusion joint surface is changed into surface contact, which increases the welding area, enhances the connection strength between the filler belt and the protective layer, and makes the fusion joint portion The tensile and shear strengths are greater than or equal to the strength of the substrate. In the case of destructive external forces, the composite patch tape will not be damaged prior to the polyethylene protective layer (see Table 1 for random sampling test data and results).
Table 1 composite joint structure sintering strength test results test number specimen number tensile shear strength and test results (refer to GB7124-86) PE pipe diameter / mm 2 21.2MPaPE jacket tube substrate damage 20.6MPaPE sleeve tube substrate Destruction 22.7MPa PE jacket tube substrate damage 2 (X8MPaPE jacket tube substrate damage 20.2MPaPE sleeve tube substrate damage 2L5MPaPE jacket tube substrate damage MPaPE sleeve tube substrate damage 21,9MPaPE sleeve tube substrate damage 22.7MPaPE jacket tube substrate destruction It is worth mentioning that in the process of heating, cooling and normal use of the pipe, the shrinkage force of the band is not affected, so the strength of the joint is ensured, and the stable and reliable sealing quality is further ensured.
In the on-site construction, the composite filler belt is subjected to the action of the elastic clamp and the composite filler belt to uniformly press the axial pressing force of the pipeline, and the pressing force at any point of the sintering joint is basically equal. The sintering effect of the entire sintered layer is almost the same, the uneven defects of the hot melt fusion are discarded, and the appearance of the entire band is smooth and flat.
3Materials, Structure and Technical Features of Composite Filling In order to reduce the cost of filling, the technology adopts the combination of polyethylene sleeve sleeve and composite patch belt. The appearance of the joint is seen in the internal structure.
Composite trim with polyethylene sleeve sleeve polyethylene protective layer 2 composite joint internal structure shows the same sleeve with a polyethylene protective layer without axial cutting. On the one hand, the overall rigidity of the mouth is increased, and the damage resistance is improved; on the other hand, the use area of ​​the composite mouth band is reduced (the price of the compound mouth band is much larger than that of the sleeve tube), thereby reducing the cost of the mouth. ). The DD-1 composite patch band is the core of this technology. It is a composite structure composed of a variety of materials of different nature, mainly composed of a heat shrink layer, a heating layer and a fusion layer. The composite patch belt is manufactured in a special workshop in the production hall and then transported to the construction site. Due to its unique technological advancement, the quality and strength of the fusion band and the polyethylene protective layer of the pipeline are higher than other commonly used methods.
4 On-site construction technology According to the principle of electric polycondensation composite sealing technology of rigid polyurethane foam anti-corrosion insulation pipe, after years of experimentation and on-site construction experience, a standardized and unified construction process has been formed. The specific construction steps are as follows: First step, according to the pipeline OD, sleeve sleeves and elastic clamps for the corresponding pipe diameter.
In the second step, the sleeve sleeve is pre-assembled on the process pipe before the pipe joint is welded.
The third step is to remove the rust, anti-corrosion and foaming of the welded joint after the process pipe joint is welded, and pull the sleeve tube to the filling position (you can also pull the sleeve tube to the filling position first, then on the sleeve tube) Open-cell foaming has the advantage that the foam inside the sleeve tube is full, but the opening on the sleeve tube needs to be sealed, which not only increases the construction difficulty, but also increases the possible leakage point), and then fills the process pipeline. A gap between the polyethylene protective layer and the sleeve tube.
In the fourth step, the composite patch band is wound and clamped with a resilient clamp.
In the fifth step, the special supplementary power supply is used to heat the composite trim band to the specified temperature.
In the sixth step, after the surface temperature of the composite patch tape is lowered to a predetermined temperature, the elastic jig is removed.
In the seventh step, the appearance quality inspection is carried out. Since the electrothermal fusion composite compounding technology has the characteristics of stable quality, the quality of the filling can be inferred according to the surface forming quality. If the requirements of the party A are required, the rigorous pressure test can also be carried out (general specification test) The pressure is 2.94 kPa, and the test does not leak for 5 minutes. At this point, all the filling work is completed.
The cable lead treatment method for special parts such as the cathodic protection system is: the cable lead is taken out from the gap between the polyethylene protective layer of the process pipe and the sleeve tube, and the periphery thereof is sealed with hot melt adhesive.
5 Field application effect At the beginning of 1999, the technology officially passed the field test and expert appraisal, and was well received by the expert group. In the second half of 1999, it began to be fully promoted in Jidong Oilfield. In 2002, it was applied in the river crossing project of several large-diameter oil pipelines in Liaohe Oilfield. After repeated destructive inspections by the quality supervision department, the quality of each project has reached and exceeded the national and industry standards. Especially in the complicated construction process such as directional crossing of pipelines, it has experienced the harsh construction and use environment of low temperature, drag and friction, and its excellent strength and sealing performance indexes are obviously superior to other repair methods. The main engineering examples are shown in Table 2. From the actual situation, the main advantages of the electrothermal fusion shrinkage compounding technology using the DD-1 composite filler tape are: (1) The welding area is increased (the fusion surface width is >50mm) Not only makes the strength of the joint part higher than the strength of the base material of the protective layer, Table 2 composite joint technology field application example engineering name construction period pipeline diameter / mm pipeline length / km mouth number / a Jidong oilfield Gaoshangbao - Laoye Temple Oil pipeline Yandong Oilfield L2丨 oil station crude oil export pipeline Jidong Oilfield Liuzan-Gaushangbao oil pipeline Liaohe Oilfield Pan-Jin Oil Pipeline (directional crossing) Liaohe Oilfield å¨-Saddle oil pipeline (directional crossing) Jidong Oilfield Liubei The oil transfer station double oil pipeline Liaohe special oil-petrochemical plant oil pipeline (crossing) 篼63 rpm-high one-link oil pipeline willow 27-turn oil pipeline and also greatly enhance the sealing performance of the joint surface.
Due to the use of a special heating electrode of the same size as the patch belt, the temperature rise and the sintering process are very uniform, making it more rigorous than the commonly used method of filling. For example, after the oil pipeline of Gaoyi Temple was put into production, the temperature drop of crude oil was reduced by 5t compared with the original pipeline. Therefore, the heating point No. 2 of the original three heating points was stopped, and only two heating points were operated, which reduced the energy consumption.
The construction technology is simple, and the sintering process is mainly controlled by special fixtures and special supplementary power sources, so the quality of the mouth is not affected by human factors.
Due to the uniform heat forming, the mouth strip has a smooth and flat appearance.
Based on reliable sealing quality, the service life of the pipe can be increased by more than 30%.
6 Problems and development direction Through several years of practical application, it is found that the rigid polyurethane foam anti-corrosion insulation pipe electric heat fusion shrinkage compounding technology mainly has the following problems: the engineering cost is slightly higher. The compound filling technology integrates the functions of hot melt and shrinkage. Although the quality of the mouth is guaranteed and the service life is improved, the price is higher than that of the hot melt method and the heat shrink method.
In the future, improvements will be made in the production of composite tape and on-site construction techniques to reduce the cost of replacement.
The processing technology of some special pipe sections is not perfect.
In the pipeline tee, elbow bend and reducer joints, due to its complicated structure, the electric heat fusion shrinkage compound joint has not been used, and only the finished parts of the manufacturer can be selected at present.
In summary, although there are some areas for improvement in the electrothermal fusion compounding technology, from the technical principle and practical use effect, the quality of the mouth is indeed better than that of other filling systems. Optimized design of sand remover and Linlin forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest, forest (1. PetroChina Jidong Oilfield Company, Tangshan 063004, China; 2. PetroChina Jidong Oilfield Company 丨§计工程有é™å…¬å¸, Tangshan 063004, China) The optimization design of solid-liquid separation equipment-hydrocyclone separator was carried out. Explore. The article introduces the basic calculation basis, calculation method, structural parameters and mathematical model of the optimization design. The practical application shows that the optimized cyclone desander is used in the closed sand removing device of the collecting and conveying system, which not only has high sand removing efficiency, fine separation granularity, but also has advanced production technology, compact equipment structure and low operating cost.
The earliest application of cyclone desander in Jidong Oilfield was in the autumn of 1987, which was used in Gaoyilian's water injection well recovery system. It was used to remove muddy sand from the well recovery water. On November 13, 1998, at the M101 station, a set of CSQ-type sand removing devices was commissioned, including three cyclone desanders. At the end of 2001, five new cyclone desanders were built.
The separation process of the cyclone desander is very complicated, and there are many factors affecting the separation effect, and various factors cross each other and restrict each other, and the process method is not easy to express accurately by mathematical expressions. However, due to the needs of the site, basic calculations must be made on the technical parameters of the desander, equipment selection and structural optimization. Therefore, it is necessary to study a calculation method combining theory with practice.
Due to the low solid concentration in the sand-containing sewage on site (the volume concentration is less than the presence of particles in the liquid stream does not affect the flow pattern of the cyclone liquid, and the interaction between the particles can be neglected. Since only a small amount of particles are deposited to the end In the flow, the ratio of the underflow to the feed flow can be kept low, and can be considered to have no effect on the separation particle size. This paper only discusses the optimal design of the cyclone when dealing with such low concentration materials.
1 Fundamental data of hydrocyclone optimization design According to the separation theory of the secondary analysis method and the hydrocyclone (balance trajectory theory and residence time theory), the basic relationship between two dimensionless quasi-numbers can be obtained: Re- Reynolds number; Eu—the pressure loss factor based on the static pressure drop in the cyclone; C, Kp, np—the empirical constants of the geometrically similar hydrocyclones, respectively, determined experimentally.
The Reynolds number is defined as: Re II also D - the inner diameter of the cyclone; v - the characteristic speed of the cyclone; IL - liquid phase particle size.
Euler's criterion is defined as: method, the comprehensive benefits are very good. It is believed that in the near future, the electrothermal fusion shrinkage compounding technology will be fully promoted in the construction of rigid polyurethane foam anticorrosive insulation pipelines, which will play a role in improving the investment efficiency of pipeline users and extending the service life of pipelines. Zhao Qixin (1967-) male, graduated from Chongqing University in 1987 with a major in mechanical manufacturing technology and equipment. He has won many provincial and municipal excellent design awards. He is currently the deputy manager of China Petroleum Jidong Oilfield Design Engineering Co., Ltd., and has been engaged in design work.
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Spade bits are used for rough boring in wood. They tend to cause splintering when they emerge from the workpiece. Woodworkers avoid splintering by finishing the hole from the opposite side of the work. Spade bits are flat, with a centering point and two cutters. The cutters are often equipped with spurs in an attempt to ensure a cleaner hole. With their small shank diameters relative to their boring diameters, spade bit shanks often have flats forged or ground into them to prevent slipping in drill chucks.
Some bits are equipped with long shanks and have a small hole drilled through the flat part, allowing them to be used much like a bell-hanger bit. Intended for high speed use, they are used with electric hand drills. Spade bits are also sometimes referred to as "paddle bits".
Spade drill bits are ordinarily available in diameters from 6 to 36 mm, or ¼ to 1½ inches.
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