Automatic water cutting device for oil storage tank

Abstract

The invention provides an automatic water cutting device for an oil storage tank, and particularly relates to the technical field of petrochemical engineering, the automatic water cutting device comprises a vertically arranged buffer cylinder I, the buffer cylinder I is connected with the oil storage tank through a suction assembly and an oil return assembly, and the inner side of the buffer cylinder I is separately connected with an oil-water separation assembly; each oil-water separation assembly comprises a filtering assembly arranged in the buffer cylinder I, a rotating structure connected with the filtering assembly and a lifting structure connected with the rotating structure, the lifting structure is movably arranged on the track assembly, and the multiple oil-water separation assemblies are arranged on the track assembly; and the oil content detection controllers are separately arranged in the oil storage tank. According to the automatic water cutting device for the oil storage tank, oil-water separation can be efficiently and rapidly achieved, deposition of impurities such as oil sludge and sand at the bottom of a dehydrator is avoided, dehydration is basically achieved in the oil storage tank, and the thorough oil return process is basically achieved in the dehydrator.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of petrochemical industry, and particularly relates to an automatic water cutting device for oil storage tank. BACKGROUND

[0002] The medium stored in the storage tank of a petrochemical enterprise generally contains oil and water. The water will gradually settle at the bottom and must be removed in time to avoid affecting production and product quality. The water cutting device is a new generation product developed and designed according to the needs of the current petrochemical industry for removing water from the storage tank. The water cutting device is made of stainless steel and has the advantages of reasonable design, simple structure, large water discharge capacity, fast oil return speed, strong corrosion resistance, easy and safe use, and the like. The water cutting device is used in the petroleum and chemical industry to replace the manual water cutting mode of the oil tank, realizes automatic water cutting, greatly reduces the labor intensity of the operation work and the hydrogen sulfide poisoning phenomenon during manual water cutting, reduces oil waste and environmental pollution, and meets the specification requirements of the petrochemical system for discharging into a blind ditch and being piped.

[0003] However, the current water cutting device still has the following technical problems in the use process:

[0004] (1) Most of the current water cutting devices are of a buffer tank type structure. The water and oil at the bottom of the oil tank enter the buffer tank, form an oil-water interface after settlement, and the water cutting valve is controlled by detecting the height of the oil-water interface. However, in the water cutting process, the oil sludge, sand and other impurities at the bottom of the oil tank also enter the water cutting device and deposit at the bottom of the water cutting device, which needs to be cleaned regularly, and the maintenance amount is large.

[0005] (2) When the oil-water density difference is small, the time for establishing the oil-water interface is relatively long, which affects the water cutting speed. For example, the density of heavy crude oil is greater than or equal to 0.931 and less than 0.998 (g / cm 3 ), the density of super-thick crude oil is greater than or equal to 0.998 (g / cm 3 ), and finally the water at the bottom of the oil storage tank is difficult to completely enter the water cutting device for water cutting. A small amount of water is still stored at the bottom of the oil storage tank, and part of the oil is also mixed in the water cutting device and cannot completely return to the oil storage tank.

[0006] The present application provides a kind of automatic water cutting device for oil storage tank, for solving the above technical problems. SUMMARY

[0007] The present application provides a kind of automatic water cutting device for oil storage tank, for solving the above technical problems.

[0008] The application discloses an automatic water cutting device for an oil storage tank.

[0009] The device further comprises a plurality of oil content detection controllers one which are separately arranged in the oil storage tank and an oil content detection controller two which is positioned on the filter assembly.

[0010] Preferably, the filter assembly comprises a support box which is arranged with an opening facing upwards, a cover plate which is positioned above the support box and is closed by a screw, a rotating drum which is coaxially and fixedly connected to the center of the cover plate at the bottom end, and a horizontal rod which is movably connected to the top end of the rotating drum, wherein the bottom end of the rotating drum is in communication with the inside of the support box, the rotating drum is rotationally connected to the horizontal rod, and the upper end surface of the support box is sealingly connected to the cover plate by a sealing ring.

[0011] The top end of the rotating drum is rotationally and sealingly connected to one end of an air suction pipe, and the other end of the air suction pipe is connected to an air pump.

[0012] The support box, the cover plate and the rotating drum are all metal mesh structures, the outside of the metal mesh structure is covered with a hydrophilic ceramic membrane, the outside of the hydrophilic ceramic membrane is coated with a hydrophilic polymer, the outside of the hydrophilic polymer is covered with a polyvinylidene fluoride microfiltration membrane, and the inside of the support box is provided with a plurality of hydrogel particles.

[0013] The metal mesh structure is provided with a plurality of through holes, the inner diameter of the through holes is 1-2 mm, and the metal material used is iron, aluminum or the like.

[0014] Preferably, the rotating structure comprises a synchronous wheel one which is coaxially arranged on the upper end of the rotating drum, a synchronous wheel two which is coaxially connected to a driving motor, and a synchronous belt which is drivingly connected to the synchronous wheel one and the synchronous wheel two, wherein the driving motor is fixed to the horizontal rod.

[0015] Preferably, the lifting structure comprises lifting cylinders which are respectively arranged at the two ends of the horizontal rod, a moving seat which is connected to the lifting cylinders, and a power wheel which is arranged at the bottom end of the moving seat, wherein the free end of the lifting cylinder is fixedly connected to the end of the horizontal rod.

[0016] Preferably, the suction assembly comprises a suction pump which is in communication with the bottom end of the oil storage tank, a suction pipe which is connected to one end of the suction pump, and a filter which is arranged on the suction pipe, wherein the other end of the suction pipe is connected to the buffer cylinder one.

[0017] The suction pump is arranged at the bottom end of the oil storage tank and can fully suck away the moisture at the bottom end of the oil storage tank under the control of the oil content detection controller one.

[0018] Preferably, the oil return assembly comprises an oil return pipe in communication with the bottom end of the buffer cylinder one, an oil return pump arranged on the oil return pipe, the other end of the oil return pipe is in communication with the oil storage tank, and a valve is further arranged on the oil return pipe.

[0019] Preferably, a plurality of scraping blades are arranged in an annular array on the outer side of the support box, and the outer end surface of the scraping blade is tangent to the inner side surface of the buffer cylinder one.

[0020] Preferably, the hydrophilic ceramic membrane is a hydrophilic modified alumina membrane or a zirconium oxide membrane, and the hydrophilic polymer is any one of polydopamine, polyethyleneimine, polyacrylic acid and polyethylene glycol.

[0021] Preferably, the track assembly comprises two tracks arranged in parallel with each other, the power wheel is movably arranged on the tracks, and a buffer cylinder two is further arranged between the two tracks.

[0022] The beneficial effects of the present application are as follows:

[0023] (1) The filter assembly is arranged in the present scheme, which achieves the following technical effects:

[0024] First, the support box, cover plate and rotating drum in the present scheme are all prepared by using a metal mesh structure, which helps to increase the strength, and a hydrophilic ceramic membrane, a hydrophilic polymer and a polyvinylidene fluoride microfiltration membrane are coated on the outer side surface from the inside to the outside, which can maximize the hydrophilic and oleophobic process, not only keeping the filter assembly relatively clean, but also facilitating cleaning and replacement;

[0025] Second, under the action of the air pump, air is sucked from the rotating drum, which helps to achieve negative pressure in the support box and the rotating drum, thereby facilitating efficient filtration of the oil-water mixture;

[0026] Third, a hydrogel is arranged on the inner side of the support box, which realizes sufficient absorption of water molecules.

[0027] (2) The rotating structure and the lifting structure are arranged, which cooperate with the filter assembly to work and achieve the following technical effects:

[0028] First, the rotation of the filter assembly helps to stir the oil-water in the buffer cylinder one, so that the impurities such as oil sludge and sand in the buffer cylinder one float up and flow back to the oil storage tank again, avoiding residues in the buffer cylinder one; in addition, when the oil return is completed, the rotation also has the effect of centrifugation, which can shake off part of the oil that may be adhered on the filter assembly and make it fall into the buffer cylinder one again.

[0029] Second, provided with lifting structure, can contact the oil-water mixture up and down buffer cylinder, thereby realizing sufficient water absorption of oil-water upper and lower parts, avoiding the problem of residual moisture in the past;

[0030] Three, provided with a scraper, when the oil return is about to end, under the action of rotation and lifting, the scraper can contact the inside surface of the buffer cylinder one in each position, thereby scraping the oil on the inside surface of the buffer cylinder one downward, realizing sufficient oil return;

[0031] (3) provided with a track assembly, on the one hand, a plurality of oil-water separation assemblies can reciprocate along the track, under the action of the lifting structure, the filter assembly is separated from the buffer cylinder one, people can disassemble the screws on the cover plate, replace the hydrogel in the support box; on the other hand, the buffer cylinder two can be arranged between the tracks, when there are more oil storage tanks, the water cutting process of multiple oil storage tanks can be carried out at the same time;

[0032] (4) the water cutting device provided in the scheme is improved and designed based on the principle of the prior art, which is obviously different from the existing dehydrator, basically solves the technical problems proposed in the background art, and has very excellent technical effects. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a working state schematic diagram of the closed water cutting device in the application.

[0034] Figure 2 It is a structure schematic diagram of the closed water cutting device in the application.

[0035] Figure 3 It is a connection structure schematic diagram of the filter assembly and the rotary lifting assembly in the application.

[0036] Figure 4 It is an explosion structure schematic diagram of the filter assembly in the application.

[0037] Figure 5 It is a structure schematic diagram of the buffer cylinder one and the support box in the application.

[0038] Figure 6 It is a connection structure schematic diagram of the filter assembly, the rotary lifting assembly and the buffer cylinder two in the application.

[0039] Among them, the reference signs are: 1, track; 2, moving seat; 3, lifting cylinder; 4, buffer cylinder one; 5, oil return pump; 6, oil return pipe; 7, suction pipe; 8, suction pump; 9, oil storage tank; 10, filter; 11, baffle; 12, air pump; 121, discharge pipe; 13, rotating cylinder; 130, horizontal rod; 131, cover plate; 132, support box; 133, scraper; 134, screw; 14, driving motor; 15, buffer cylinder two. DETAILED DESCRIPTION

[0040] In order to make the technical features of the present scheme clearer, the present scheme will be described below through specific embodiments.

[0041] Reference Figures 1-6 The automatic water cutting device for oil storage tank comprises a buffer cylinder 4 arranged vertically, the buffer cylinder 4 is connected with the oil storage tank 9 through a suction assembly and an oil return assembly, the inner side of the buffer cylinder 4 is connected with an oil-water separation assembly in a detachable manner, the oil-water separation assembly comprises a filtering assembly arranged in the buffer cylinder 4, a rotating structure connected with the filtering assembly, and a lifting structure connected with the rotating structure, the lifting structure is movably arranged on a track assembly, and a plurality of oil-water separation assemblies are arranged on the track assembly.

[0042] Further comprising a plurality of oil content detection controllers one arranged in the oil storage tank 9 in a detachable manner and a plurality of oil content detection controllers two arranged on the filtering assembly.

[0043] Among them, the plurality of oil content detection controllers one are arranged at different position points in the oil storage tank 9, and the plurality of oil content detection controllers two are also arranged at different position points in the buffer cylinder 4, for example, the height position of the control sensor can be adjusted by controlling the length of the sensor data line.

[0044] It should be noted that the oil content detection controller is composed of a liquid column resonance type oil content detection sensor and a controller. The sensor is a single-piece structure, the vibrating piece is in direct contact with the medium, and the vibrating piece is connected with the driving element through a transmission rod to produce resonance with the medium. The resonance frequency and amplitude of the vibrating piece will change due to different oil content in water, thereby detecting the oil content. In order to prevent the sensor from being contaminated by oil sludge, a layer of diamond protective film is plated on the surface of the sensor. This is a prior art sensor, and the working principle will not be described in detail.

[0045] Through the oil content detection controller, the working condition of the inside of the oil tank is basically clear, the dehydration system can be judged in time, which brings convenience to production and improves work efficiency.

[0046] The filtering assembly comprises a support box 132 arranged with an opening upward, a cover plate 131 positioned above the support box 132 and closed and positioned by a screw 134, a rotating drum 13 fixedly connected with the center of the cover plate 131 in a coaxial manner at the bottom end, a horizontal rod 130 movably connected with the top end of the rotating drum 13 in a perpendicular manner, the bottom end of the rotating drum 13 is communicated with the inside of the support box 132, the rotating drum 13 is rotationally connected with the horizontal rod 130, and the upper end surface of the support box 132 is sealingly connected with the cover plate 131 through a sealing ring;

[0047] The top end of the rotating drum 13 is rotatably connected with one end of an air extraction pipe, and the other end of the air extraction pipe is connected with the air pump 12; more preferably, an air pressure gauge is arranged on the air extraction pipe to determine the negative pressure data.

[0048] The support box 132, the cover plate 131 and the rotating drum 13 are all metal mesh structures, the outer side of the metal mesh structure is covered with a hydrophilic ceramic membrane, the outer side of the hydrophilic ceramic membrane is coated with a hydrophilic polymer, and the outer side of the hydrophilic polymer is covered with a polyvinylidene fluoride microfiltration membrane; the inside of the support box 132 is provided with a plurality of hydrogel particles.

[0049] More preferably, a baffle plate 11 is arranged coaxially and perpendicularly at the upper end of the rotating drum 13 to prevent oil and water in the buffer cylinder 4 from splashing. The air pump 12 is connected with the exhaust pipe 121 for air exhaust.

[0050] When the filter assembly in the present scheme is immersed in oil and water, its surface is covered with a layer of firm water molecules (hydration layer), and oil droplets cannot replace this layer of water film to directly contact the material surface, thus showing a large underwater oil contact angle (usually > 150°), and being easy to roll off or be blocked;

[0051] The material itself or the substrate of the coating needs to have connected and large enough pores to allow water to flow through, and at the same time rely on the hydration layer on the surface rather than simply rely on the pore size to block the oil droplets.

[0052] In the present scheme, the coating structure arranged on the outer side of the metal mesh structure can allow water to continuously penetrate downward when the oil-containing wastewater contacts the film surface, and the surface always maintains super-oleophobicity, so that oil is retained on the surface to achieve the effect of oil-water separation. Due to the inherent oleophobicity of the film, the oil cannot always pollute the film surface, and the present scheme is suitable for occasions with less water and more oil.

[0053] The rotating structure includes a synchronous wheel one coaxially arranged at the upper end of the rotating drum 13, a synchronous wheel two coaxially connected with the driving motor 14, and a synchronous belt drivingly connected with the synchronous wheel one and the synchronous wheel two; the driving motor 14 is fixed on the horizontal rod 130.

[0054] In order to simplify the design, the synchronous wheel one and the synchronous wheel two are not indicated in the drawings, but they are easy to be realized by those skilled in the art, and thus will not be described in detail here.

[0055] The lifting structure includes lifting cylinders 3 arranged at both ends of the horizontal rod 130, a moving seat 2 connected with the lifting cylinders 3, and a power wheel arranged at the bottom end of the moving seat 2; the free ends of the lifting cylinders 3 are fixedly connected with the ends of the horizontal rod 130. In order to simplify the design, the power wheel is not indicated in the drawings, but this does not affect the implementation of the present scheme, and thus is described here.

[0056] The suction assembly comprises a suction pump 8 communicated with the bottom end of the oil storage tank 9, a suction pipe 7 with one end connected with the suction pump 8, and a filter 10 arranged on the suction pipe 7, and the other end of the suction pipe 7 is connected with the buffer cylinder I 4.

[0057] The oil return assembly comprises an oil return pipe 6 with one end communicated with the bottom end of the buffer cylinder I 4, an oil return pump 5 arranged on the oil return pipe 6, and the other end of the oil return pipe 6 is communicated with the oil storage tank 9, and a valve is further arranged on the oil return pipe 6.

[0058] More preferably, the valve structure is arranged in the pipeline in the present scheme, for example, the valve structure is also designed on the suction pipe 7, which is not marked in the drawing, and is hereby described.

[0059] The outer side of the support box 132 is provided with a plurality of scrapers 133 in an annular array, and the outer end surface of the scraper 133 is tangent to the inner side surface of the buffer cylinder I 4. When the scraper 133 works, the support box 132 is adjusted to the top end of the buffer cylinder I 4, and then it is rotated and descended, so that the oil on the inner side of the buffer cylinder I 4 is scraped down into the oil return pipe 6, and finally flows back to the oil storage tank 9.

[0060] The hydrophilic ceramic membrane is any one of a hydrophilic modified alumina membrane or a zirconia membrane, and the hydrophilic polymer is any one of polydopamine, polyethyleneimine, polyacrylic acid and polyethylene glycol.

[0061] The track assembly comprises two tracks 1 arranged in parallel with each other, the power wheel is movably arranged on the track 1, and the buffer cylinder II 15 is further arranged between the two tracks 1.

[0062] The specific working process of the present application is as follows:

[0063] In the prior art, a dehydrator is usually used, and in the present scheme, in order to avoid the problems existing in the prior dehydrator, the buffer cylinder is designed to make the filter assembly contact with the buffer cylinder in a separated mode, so that the gravity dehydration separation effect, the filtering effect and the collision separation effect are comprehensively generated, and the separation effect is better than that of the prior dehydrator. Through experiments, it is verified that the buffer cylinder basically does not contain oil sludge, sand and the like, and the water content in the original oil storage tank 9 is 0.1-0.3%, and the oil residual rate in the buffer cylinder is 0.22-0.35%, so that the clean oil-water separation is basically achieved.

[0064] In the present scheme, the filter assembly is arranged, the support box 132, the cover plate 131 and the rotating drum 13 in the present scheme are all prepared by using a metal mesh structure, which is helpful to increase the strength, and the hydrophilic ceramic membrane, the hydrophilic polymer and the polyvinylidene fluoride microfiltration membrane are coated on the outer side surface from inside to outside, so that the hydrophilic and oleophobic process can be realized to the maximum extent, the relative cleanliness of the filter assembly is maintained, and the filter assembly is also convenient to clean and replace.

[0065] The present scheme sets multiple water filtering membranes outside the metal mesh structure, fully utilizes the oil-repellent characteristics to realize oil-water separation, and water molecules pass through the polyvinylidene fluoride microfiltration membrane, the hydrophilic polymer, the hydrophilic ceramic membrane and the metal mesh structure in turn, enter the inside of the supporting box 132, and then contact the hydrogel particles, which greatly improves the oil-water filtering efficiency and avoids the adhesion of oil.

[0066] When the filtering assembly rotates and lifts, the air pump 12 works simultaneously, and under the action of the air pump 12, air is sucked from the rotating drum 13, which helps to realize negative pressure in the supporting box 132 and the inside of the rotating drum 13, so as to facilitate efficient filtering of the oil-water mixture; at the same time, the action of negative pressure also makes the combination of the supporting box 132 and the cover plate 131 more compact, which is helpful for sealing; the hydrogel is arranged on the inside of the supporting box 132, which realizes sufficient absorption of water molecules, and after a certain time, the expanded hydrogel is replaced to perform the work of oil-water separation again.

[0067] The rotating structure and the lifting structure are arranged, cooperate with the filtering assembly to work, and through the rotation of the filtering assembly, the oil-water in the buffer cylinder 4 is stirred, so that the oil sludge, sand and other impurities in the buffer cylinder 4 float up and flow back to the oil storage tank 9 again to avoid residue in the buffer cylinder 4; in addition, when the oil return is completed, the rotation also has the effect of centrifugation, which shakes off the part of oil that may be adhered to the filtering assembly and falls into the buffer cylinder 4 again.

[0068] The lifting structure is arranged, which can contact the oil-water mixture above and below the buffer cylinder 4, so as to realize sufficient water absorption of the upper and lower parts of the oil-water, and avoid the problem of water residue in the past;

[0069] The scraper 133 is arranged, when the oil return is about to be completed, under the action of rotation and lifting, the scraper 133 can contact each position of the inner side of the buffer cylinder 4, so as to scrape the oil on the inner side of the buffer cylinder 4 downward to realize sufficient oil return;

[0070] The track assembly is arranged, on the one hand, a plurality of oil-water separation assemblies can reciprocate along the track 1, under the action of the lifting structure, the filtering assembly is separated from the buffer cylinder 4, and people can disassemble the screws 134 on the cover plate 131 to replace the hydrogel in the supporting box 132; on the other hand, the buffer cylinder 2 15 can be arranged between the tracks 1, when the oil storage tanks 9 are more, the water cutting process of multiple oil storage tanks 9 can be carried out at the same time.

[0071] The technical features not described in the present application can be realized by or using the prior art, which will not be described here, of course, the above description is not a limitation of the present application, the present application is not limited to the above examples, the changes, modifications, additions or replacements made by ordinary skilled in the art within the essential scope of the present application should also belong to the protection scope of the present application.

Claims

1. An automatic water cutting device for oil storage tank, comprising a buffer cylinder one (4) arranged vertically, characterized in that, The buffer cylinder one (4) is connected with the oil storage tank (9) through a suction assembly and an oil return assembly, the inner side of the buffer cylinder one (4) is connected with an oil-water separation assembly in a detachable manner, the oil-water separation assembly comprises a filter assembly arranged in the buffer cylinder one (4), a rotating structure connected with the filter assembly, and a lifting structure connected with the rotating structure, the lifting structure is movably arranged on a track assembly, and a plurality of oil-water separation assemblies are arranged on the track assembly. A plurality of oil content detection controllers one are arranged in the oil storage tank (9) in a detachable manner, and an oil content detection controller two is arranged on the filter assembly.

2. The automatic water cutting device for oil tank according to claim 1, characterized in that, The filter assembly comprises a support box (132) with an opening arranged upwards, a cover plate (131) positioned above the support box (132) and closed by a screw (134), a rotating drum (13) fixedly connected with the center of the cover plate (131) in a coaxial manner at the bottom end, and a horizontal rod (130) movably connected with the top end of the rotating drum (13), the bottom end of the rotating drum (13) is in communication with the inside of the support box (132), the rotating drum (13) is rotatably connected with the horizontal rod (130), and the upper end surface of the support box (132) is sealingly connected with the cover plate (131) through a sealing ring; the top end of the rotating drum (13) is rotatably and sealingly connected with one end of a suction pipe, the other end of the suction pipe is connected with a gas pump (12), and the support box (132), the cover plate (131) and the rotating drum (13) are all metal mesh structures.

3. The automatic water cutting device for oil tank according to claim 2, characterized in that, The rotating structure comprises a synchronous wheel one coaxially arranged on the upper end of the rotating drum (13), a synchronous wheel two coaxially connected with a driving motor (14), and a synchronous belt drivingly connected with the synchronous wheel one and the synchronous wheel two, and the driving motor (14) is fixedly connected with the horizontal rod (130).

4. The automatic water cutting device for oil tank according to claim 3, characterized in that, The lifting structure comprises lifting cylinders (3) arranged at two ends of the horizontal rod (130) respectively, a moving seat (2) connected with the lifting cylinders (3), and a power wheel arranged at the bottom end of the moving seat (2), and the free end of the lifting cylinder (3) is fixedly connected with the end of the horizontal rod (130).

5. The automatic water cutting device for oil tank according to claim 1, characterized in that, The suction assembly comprises a suction pump (8) in communication with the bottom end of the oil storage tank (9), a suction pipe (7) connected with one end of the suction pump (8), and a filter (10) arranged on the suction pipe (7), and the other end of the suction pipe (7) is connected with the buffer cylinder one (4).

6. The automatic water cutting device for oil tank according to claim 1, characterized in that, The oil return assembly comprises an oil return pipe (6) in communication with the bottom end of the buffer cylinder one (4) at one end, and an oil return pump (5) arranged on the oil return pipe (6), the other end of the oil return pipe (6) is in communication with the oil storage tank (9), and a valve is further arranged on the oil return pipe (6).

7. The automatic water cutting device for oil tank according to claim 2, characterized in that, A plurality of scraping blades (133) are arranged in an annular array on the outer side of the support box (132), and the outer end surface of the scraping blade (133) is tangent to the inner side surface of the buffer cylinder one (4).

8. The automatic water cutting device for oil tank according to claim 2, characterized in that, The outer side of the metal net structure is covered with a hydrophilic ceramic membrane, the outer side of the hydrophilic ceramic membrane is coated with a hydrophilic polymer, the outer side of the hydrophilic polymer is covered with a polyvinylidene fluoride microfiltration membrane, and the inside of the support box (132) is provided with a plurality of hydrogel particles.

9. The automatic water cutting device for oil tank according to claim 9, characterized in that, The hydrophilic ceramic membrane is a hydrophilic modified alumina membrane or a zirconia membrane, and the hydrophilic polymer is any one of polydopamine, polyethyleneimine, polyacrylic acid and polyethylene glycol.

10. The automatic water cutting device for oil tank according to claim 4, characterized in that, The track assembly comprises two tracks (1) arranged in parallel with each other, the power wheel is movably arranged on the track (1), and a buffer cylinder two (15) is further arranged between the two tracks (1).

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