Production tubing with thermally insulating coating

Abstract

The invention relates to the oil and gas industry, and more particularly to designs of production tubing for injecting a working fluid in the form of a supercritical fluid into a hydrocarbon-containing formation. The present production tubing comprises a pipe, the outside surface of which is wrapped in a first layer of a first heat-reflecting material in the form of a stainless steel foil. Next, a thermally insulating coating is applied in a second layer, said coating being covered on top by a protective casing, the inside surface of which has applied thereto a second heat-reflecting material in the form of a heat-resistant silver enamel. Two thermally insulated gripping regions are provided for the gripping of the pipe by hydraulic power tongs or a spider during assembly / disassembly of the production tubing. The production tubing is made of an aluminium oxide ceramic, more than 95% of which is composed of aluminium oxide, and up to 5% of which is composed of a mixture of particles of oxides and non-oxides of metals and non-metals. Each thermally insulated gripping region is provided with outwardly facing reinforcing ribs which are attached to the surface of the tube by diffusion welding and which form compartments for receiving the thermally insulating coating. The technical result is that of increasing the insulating properties of the thermally insulating coating and providing improved reliability.

Description

[0001] Pump-compressor pipe with thermal insulation coating

[0002] The invention relates to the construction of tubing pipes (TP) with a heat-insulating coating (HIC) and can be used in the construction of heat-insulated columns of tubing joined to each other to a depth of up to 5000 meters in the oil and gas industry for injecting a working agent (WA) in the form of an ultra-supercritical or supercritical fluid into a hydrocarbon-containing formation, as well as in geothermal energy for the extraction of a coolant in the form of an ultra-supercritical or supercritical fluid from an artificially created underground heat-exchange geothermal reservoir.

[0003] Ultra-supercritical fluids have temperatures up to 700°C and pressures up to 60 MPa.

[0004] Oil companies have recently begun developing oil-bearing shale formations, particularly the Bazhenov and Domanik Formations. The use of so-called thermochemical technologies, based on pumping a high-temperature, high-pressure, ultra-supercritical or supercritical fluid through a tubing string into the reservoir, has been recognized as highly promising for their development.

[0005] A RAV with similar thermobaric characteristics is required for the development of deep-seated hydrocarbon deposits, as well as for the continued profitable exploitation of hydrocarbon deposits in the final stage of exploitation, including hard-to-recover hydrocarbon reserves (HRCR).

[0006] In turn, in geothermal energy, the direction known as “Enhanced Geothermal Systems” (EGS) continues to actively develop. The essence of this technology is pumping cold water through an injection well into a pre-fractionated high-temperature granite formation located at a depth of up to 6000 meters and having a temperature of up to 500-700 °C, heating the cold water (fluid) as it passes through cracks in the high-temperature granite formation and withdrawing the heated high-temperature fluid to the daylight surface through a production well along a tubing string.

[0007] Naturally, the implementation of such technologies requires tubing with high thermal insulation properties to reduce fluid heat loss, high strength properties to withstand high fluid pressure, high anti-corrosion properties necessary for operation in aggressive environments, and also ensuring reliable and tight connections during the construction of tubing columns.

[0008] Currently, such tubing, which optimally combines high thermobaric and anti-corrosion properties, as well as having reliable connecting elements for the formation of columns, is lacking both in the Russian Federation and abroad, which is one of the limiting factors for the use of modern thermochemical technologies.

[0009] Numerous attempts have been made in the Russian Federation and abroad to develop a tubing design that meets such stringent requirements. However, this problem remains unresolved.

[0010] For example, NAO TMK has developed thermally insulated lift pipes (TILP) suitable for transporting RAW to the wellbore in the form of supercritical water, with temperatures up to 450°C and pressures up to 40 MPa. However, for the commercial development of oil-bearing shale formations, such as the Bazhenov Formation, RAW is required in the form of supercritical water, with a wellhead temperature of at least 550°C and pressures up to 60 MPa.

[0011] The most common solution to these problems involves various tubing designs with a wide range of multilayer thermal insulation coatings (MTCs) placed on the outer or inner surface of the tubing. However, their use poses a number of challenges, including maintaining the integrity of the MTCs when gripping the pipe with the clamping elements of a hydraulic wrench and / or spider during assembly and disassembly operations on the tubing strings, as the MTCs are not sufficiently strong; threaded connections traditionally used to connect the tubing to the string are unreliable and leaky under high fluid pressures and temperatures; and high temperatures lead to significant thermal deformation of the tubing, altering its length, which often leads to the destruction of the MTCs and their protective casings.

[0012] Let's consider several typical designs of tubing with TIP.

[0013] A thermally insulated tubing string is known (RU Patent No. 2129202, cl. E21B 17 / 00, 1999), including an inner pipe with a multilayer screen insulation located on it, an outer pipe and a coupling, the inner pipe is made of one piece with upset profiled ends, the outer pipe is compressed along the axis by 9 - 12 mm before installation, has a cone-thrust thread at the ends and is equipped with a seat and a valve equidistant from the ends of the pipe and, after sealing the seat, welded with a vacuum-tight seam, the inner and outer pipes are made of the same material and are welded at the ends with vacuum-tight seams, centering rings are placed on the multilayer screen insulation, a gas absorber is placed between the layers of the multilayer screen insulation, a vacuum of 10' is created in the intertube space 4 - 10“ 3 mm Hg, while the coupling is screwed onto the outer pipe, and the sealing sleeve is provided with a groove and presses the profiled ends of the inner pipe to the outer pipe.

[0014] An analysis of the design of this tubing string reveals that traditionally, a cone-thrust threaded connection is used to connect the tubing string to the casing. This connection, when heated to temperatures of 550°C or higher and at pressures above 45-50 MPa, does not ensure a leak-tight and reliable connection. Furthermore, the high tightening force used to ensure the reliability and tightness of such connections, close to the ultimate strength of the tubing material, can lead to thread stripping during operation. For this reason, the service life of such pipe connectors does not exceed a few make-up-break-out cycles.

[0015] A significant drawback of the known design is the difficulty of maintaining a vacuum in the annular space under high pressure and temperature of the RAW media. Forced compression of the outer pipe before installation creates unwanted prestress in the tubing. The design of such tubing is quite complex, and its manufacturing technology is even more complex. However, this does not guarantee high thermal insulation properties.

[0016] A heat-insulated pipe is known (RU Patent for Utility Model No. 121855, cl. E21B17 / 00, 2012), comprising a heat-insulating coating placed on the pipe, containing a heat-reflecting and heat-insulating layer, a layer of basalt fabric covered with a heat-reflecting layer, wherein the coating additionally contains an outer protective layer and a second heat-reflecting layer, the heat-insulating layer is placed between the heat-reflecting layers, and a protective outer layer is placed on the outer heat-reflecting layer, wherein the heat-reflecting layers are made of aluminum foil, and multi-silica felt is used as the heat-insulating material, the protective layer is a polypropylene pipe, and a fiberglass layer is placed between the heat-reflecting coating and the protective coating.

[0017] As a result of the analysis of the known solution, it should be noted that the heat-insulating coating, consisting of a large number of layers, is very complex and labor-intensive to manufacture, such a coating is characterized by a fairly high percentage of defects, since it is very difficult to ensure a tight fit of all the layers to each other, and, at the same time, it has a fairly high thermal conductivity. As studies have shown, when pumping a coolant at a temperature of 450 ° C through the tubing, the temperature on the outer surface of the pipe is approximately 50 ° C. The average value of the thermal conductivity coefficient of the coating material does not exceed 0.039 W / m * K, and, as studies have shown, for the efficient operation of the tubing string, the value of the thermal conductivity coefficient TIP at a temperature of 400 ° C should not exceed 0.024 W / (m * K), at 600 ° C - 0.029 W / (m * K), and at a temperature of 800 ° C - 0.034 W / (m * K).It is also very significant that the design of the tubing does not provide for specially designed zones for gripping the pipe with a hydraulic wrench or spider during installation and dismantling work, which leads to damage to the thermal insulation coating, a decrease in its thermal insulation properties, and, consequently, the service life of the tubing.

[0018] A well-known tubing system with a type of threaded surface (Russian Federation patent for utility model No. 156386, class F16L 59 / 00, 2015) contains a pipe made of alloy steel with connecting elements at its ends, made in the form of threaded surfaces.

[0019] A multi-layer thermal insulation coating is formed on the outer surface of the pipe.

[0020] On the surface of the pipe, two heat-insulated gripping zones of similar design are formed, intended for gripping the pipe with a hydraulic key and / or spider during assembly (disassembly) of the tubing string.

[0021] Each such zone contains a metal frame welded to a designated location on the pipe's outer surface. Cells for housing the TYPE are formed on the frame by welding longitudinal and transverse ribs.

[0022] A wide range of materials can be used as TYPE, for example, those obtained from short basalt fibers.

[0023] A protective casing in the form of a split tube is placed on the outside of the frame with the heat-insulating material. When gripped with a hydraulic wrench or slider, it ensures the integrity of the heat-insulating material and the metal surface of the pipe.

[0024] A split tube is wrapped in layers of heat-reflecting material (aluminum foil) and a protective fiberglass shell. A thin steel mesh is wound on top of the protective fiberglass shell. The mesh is secured to the shell with a polymer binder. The mesh layer protects the protective shell from damage by the serrated steel jaws of the hydraulic wrench and / or spider. It also prevents the hydraulic wrench or spider from rotating relative to the pipe gripping area, which allows for a slight reduction in pipe clamping force during installation and disassembly.

[0025] An analysis of this tubing design reveals that, unlike the above, it is equipped with thermally insulated gripping zones. However, the design of these zones as a frame secured to the outer surface of the pipe with outward-facing ribs, between which the TIP is positioned, prevents high loads from being applied to these zones. The force of the hydraulic wrench or spider is applied to the frame ribs. This results in very high specific contact forces, leading to failure of the insulating layers placed on the frame at the contact point and deformation of the insulating material located within the frame cells. All of this significantly reduces the thermal insulation properties of the tubing and its service life.

[0026] The threaded connecting elements traditionally used in the design of this tubing do not ensure the tightness of the connection and its reliability under conditions of impact and alternating thermal loads, which has already been noted above.

[0027] Using a multilayer protective coating as a type of coating does not provide reliable thermal insulation under high temperatures and, consequently, significant thermal linear deformations of the tubing. All of the above reduces the service life of the tubing.

[0028] A well-known tubing string has a heat-insulating coating on its outer surface, covered on top by a protective casing, two heat-insulated gripping zones designed for gripping the pipe with a hydraulic wrench or spider during installation and removal of the tubing, as well as connecting elements located at the ends of the pipe, designed for joining the pipes during their assembly into a column. Each gripping zone is formed by a disk placed on the pipe and fastened to it, a ring enclosing the pipe and attached to the disk, as well as plates attached to the outer surface of the pipe and the inner surface of the ring, a protective casing is attached to the rings of the gripping zones and is equipped with a corrugated section to compensate for thermal deformations, and each connecting element of the pipe is made in the form of a sleeve fixed on the outer surface of the pipe at its end and equipped with leashes that can contact the tightening coupling (RU Patent No. 2704405 cl. E21B 17 / 01 (2006.01), 2018.) is the closest analogue.

[0029] An analysis of this tubing design reveals that, like the designs discussed above, it shares a significant drawback: all tubing, including its closest analogue, is made of metal (steel or alloy). In particular, Inconel 740, Inconel 716, and Haynes 282 alloys are expensive and produced abroad, making them unavailable to tubing manufacturers under the current sanctions regime.

[0030] For the heat-insulating coating, the material “MICROTHERM” was used, which is also expensive and produced outside of the Russian Federation.

[0031] The above factors do not allow the closest analogue to be produced in Russia today.

[0032] Moreover, the closest analogue being analyzed has a complex design, and its production is highly labor-intensive.

[0033] The technical result of the present invention is the creation of tubing with TIP, having high thermal insulation properties and a long service life, characterized by simplicity of design and production, as well as the availability of raw materials for their production due to the use of new materials and technologies available in the Russian Federation for the manufacture of the tubing with TIP themselves, subject to maintaining the integrity and, consequently, the tightness of the thermal insulation coating on the pipe and in the capture zones during the entire service life of the tubing with TIP under conditions of high temperatures and fluid pressures, as well as by ensuring a hermetic connection of the tubing during their assembly into columns due to a simplified and reliable design of the connecting elements of the pipe and the use of spacers.

[0034] The specified technical result is ensured by the fact that in the tubing with a heat-insulating coating, containing a pipe, the outer surface of which is wrapped in the first layer with a first heat-reflecting material - stainless steel foil and then a second layer of heat-insulating coating is placed, closed on top with a protective casing, on the inner surface of which a second heat-reflecting material is applied - heat-resistant silver enamel, two heat-insulated gripping zones designed to grip the pipe with a hydraulic key or spider during installation and dismantling of the tubing, what is new is that the individual sections of the tubing are connected to each other using diffusion welding made of large particles (from 2500 to 10000 nm) of metal and non-metal oxides or non-metal and non-metal oxides, individually or from a mixture of such large particles, or microparticles (from 100 to 2500 nm) of metal and non-metal oxides, or non-metal oxides and non-metals,individually or from a mixture of such microparticles, or, preferably, from nanoparticles of metal and non-metal oxides or non-metal and non-metal oxides, individually or from a mixture of such nanoparticles having a size of from 0.1 to 100 nanometers (nm), or, preferably, from aluminum oxide nanoparticles (AI2O3) having a size of from 0.1 to 100 nm, or from corundum ceramics (alumina ceramics) containing more than 95% of aluminum oxide nanoparticles and, preferably, 99.9% of aluminum oxide nanoparticles, or from corundum ceramics containing more than 95% of aluminum oxide nanoparticles and up to 5% of nanoparticles of oxides of other metals and non-metals and non-metal oxides, preferably nanoparticles of zirconium dioxide (ZrCh), manganese oxide (MnO), magnesium oxide (MgO), silicon oxide (SiCh), iron oxide FeO, chromium oxide (CnO3), titanium dioxide (TiO2), tungsten oxide (WO3), silicon carbide (SiC), silicon nitride (Si3N4), boron carbide (B4C), and also, for example,nickel (Ni) and chromium (Cr) or eutectic multicomponent additive systems, for example, AhCh-ZrCh, AhC -ZrCh-CriC, AI2O3-ZrO2-TiO2, AhO3-ZrO2-SiO2, AhC -ZrCh-WC, or other possible eutectic multicomponent additive systems that increase the strength of corundum ceramics, lower the temperature of its formation and increase its plasticity using one or another technology for their production known from the modern development of the level of technology and, preferably, by the method of hot pressing (HP) in graphite press molds with a coating of boron nitride (BN) or the method of hot isostatic pressing (HIP) in gasostatic presses. What is also new is that each heat-insulated capture zone is equipped with several outward-facing stiffening ribs, which are fixed to the surface of the pipe using the diffusion welding method and rest against the upset ends of the pipe, while heat-insulating material can be used for the TIP,composite consisting of aluminosilicate microspheres and hardened liquid glass prepared from dry concentrate of liquid glass and applied to the outer surface of the tubing, and also filling the voids between the longitudinal stiffening ribs of the tubing.

[0035] The connecting joints of tubing (threaded couplings, threadless couplings, etc.) into the tubing string are not the subject of the present invention and therefore various suitable technical solutions for joining tubing known from the current level of technology may be used to connect tubing into the tubing string. For example, a threaded coupling known from Russian Patent No. 2702033 of February 5, 2019 “Tubing and compressor string tightness unit (variants)” [1] may be used. In the case where tubing made, for example, of alumina ceramics is connected to any half of the coupling made of metal or a metal alloy, then diffusion welding, known from the current level of technology, is used for their connection with various types of gaskets, for example, made of titanium (Ti), copper (Cu) or molybdenum (Mo), or without them [6].

[0036] The choice of the above-mentioned materials and, in particular, preferably, alumina ceramics with a high content of aluminum oxide (up to 99.9%) in the form of, preferably, aluminum oxide nanoparticles (size from 0.1 to 100 nm; the higher the dispersion of aluminum oxide particles, the stronger the product made of alumina ceramics) for the manufacture of tubing is due to the following.

[0037] Technical alumina, which is used as a raw material for the production of alumina (corundum) ceramics, is a highly accessible raw material, including in the Russian Federation.

[0038] Alumina ceramics exhibit high wear resistance, density, hardness, flexural strength, resistance to chemically aggressive environments, and corrosion. Thanks to these high characteristics, they are used to manufacture a wide variety of products, from abrasive tools to body armor and biomaterials.

[0039] In terms of tensile strength (P up to 665 MPa), alumina ceramics outperform Sanicro 25 (P = 500 MPa), which was developed for the next generation of coal-fired power boilers: so-called advanced boilers operating on ultra-supercritical steam cycles. It is ideal for reheater and superheater tubes in these new systems and allows the material to be used to transport coolant temperatures up to 700°C.

[0040] Alumina ceramics have a significantly lower density (max. 3.98 g / cm 3 ) compared to any metal alloys and can be used at temperatures up to 1840°C. Possessing high strength—on the Mohs scale, its hardness reaches 9 units (second only to diamond)—it has a virtually unlimited service life.

[0041] Alumina ceramics are excellent for diffusion welding.

[0042] Current technology indicates that the optimal diffusion welding process for butt joints of pipes involves heating the joint to 1500°C for 1 hour at a pressure of 10 MPa. A paste of magnesium oxide (MgO) nanoparticles is first applied to the ends of the pipes to be welded. Importantly, this type of welding, which ensures high-quality welds, can be performed without the need for a vacuum [2].

[0043] High quality alumina ceramics are made from aluminum oxide nanoparticles that can be obtained by using the Supercritical Water Oxidation process, which is well known in the modern technology.

[0044] There are three possible reactions of aluminum with water:

[0045] 2Al + 6H2O = 2Al(OH)3 + 3H2

[0046] 2Al + 4H2O = 2AlO(OH) + 3H2

[0047] 2A1 + ZN2O = A120Z + ZN2

[0048] The first possible reaction product is Al(OH)3 (bayerite). The second possible reaction product is AlO(OH)3 (boehmite). The third possible reaction product is Al2O3 (aluminum oxide), which is necessary for the production of alumina ceramics. These reaction products differ in their degree of hydration*. All three release the same amount of hydrogen relative to the amount of aluminum reacted, but differ in the amount of water required for the reaction.

[0049] *Note: Hydration is the addition of water molecules to molecules or ions. Hydration is a special case of solvation - the addition of molecules to molecules or ions of substances.

[0050] The reaction to produce aluminum oxide nanoparticles is highly exothermic - approximately 15 MJ / kg aluminum powder.

[0051] From room temperature to 280°C, Al(OH)3 is the most stable product, while at 280-480°C, AlO(OH)3 is the most stable. Above 480°C (the supercritical water (SCW) temperature), Al2O3 is the most stable product.

[0052] Thus, it is clear that the production of aluminum oxide nanoparticles requires a SCR, which must have a temperature above 480°C; preferably 530-550°C.

[0053] Russian Patent No. 2671880 (2017) describes in detail the process of synthesizing aluminum oxide nanoparticles in an inorganic compound oxidation reactor, which is connected to an ultra-supercritical water generator (USCG) and located behind it.

[0054] The USCW Generator known from the Russian Federation Patent No. 2726702 of September 26, 2029 “Ultra-supercritical working agent generator” can be used as a USCW Generator in the production of aluminum oxide nanoparticles.

[0055] For example, PA-3 aluminum powder serves as a raw material for the production of aluminum oxide nanoparticles using the supercritical water oxidation method.

[0056] The essence of the claimed invention is explained by graphic materials, in which:

[0057] - Fig. 1 - longitudinal section of tubing 1;

[0058] - Fig. 2 - a separate section of tubing 2, longitudinal section;

[0059] - Fig. 3 - a separate section of tubing 3, longitudinal section;

[0060] - Fig. 4 - tubing with TYPE, longitudinal section;

[0061] - Fig. 5 - section A-A according to Fig. 4 (section along the capture zone). The casing with the coating of the inner surface of the casing with the second heat-reflecting coating is not shown.

[0062] - Fig. 6 - application of the TYPE to the tubing.

[0063] The claimed invention is also explained using the example of tubing with a type of inline casing with subsequent use of threadless couplings when assembling them into a string of tubing with a type of inline casing (when using threaded couplings, the upset ends of the tubing with a type of inline casing will have a different design).

[0064] The tubing 1 (Fig. 1) consists of two types of separate tubing sections made from the above-mentioned materials, for example, by the GP or HIP method - a separate tubing section 2 2 (Fig. 2) and a separate tubing section 3 3 (Fig. 3), connected to each other using diffusion welding. In this case, for the manufacture of tubing 1, two separate sections of tubing 2 2 up to 1000-1500 mm long and several separate sections of tubing 3 3 (two or three separate sections of tubing 3 3 depending on their length) with a length of 3000 to 4500 mm are always used. Due to the peculiarities of the technologies for forming products (pipes) from the above-mentioned materials, the manufacture of a separate section of tubing 3 3 having a length of more than 4500-4800 mm or a single tubing 1 with a length of 10000-12000 mm is not possible.

[0065] A separate section of tubing 2 2 consists of a pipe 3 with an upset end of the pipe 4. At the end of the upset end of the pipe 4, a spacer 5 is installed, made of bismuth or bismuth alloys with other metals, for example, an alloy of bismuth with tin or an alloy of bismuth with lead, etc. The spacer 5, made of bismuth or its alloys, performs the function of a sealing gasket and works as follows.

[0066] Under the influence of the high temperature of the coolant transported through the tubing with TYPE, the spacer 5 gradually heats up and, upon reaching its melting temperature (T=271.4°C), it passes into a liquid state and, having a higher density than, for example, supercritical water, reliably seals the joints of the tubing, for example, with another tubing or with a threaded coupling.

[0067] If the spacer 5 is made of bismuth or an alloy containing bismuth, then even before the transition of the spacer 5 from the solid state to the liquid, some part of the coolant through the joint formed by the pressure surfaces of the joined tubing (the end of one tubing is joined to the end of another tubing in the case of using a threadless coupling) or tubing with a threaded coupling (not shown in the drawing) gets into the volume in which the spacer 5 is located. As a result of the chemical reaction during the interaction of the coolant in the form of ultra-supercritical or supercritical water with the bismuth of the spacer 5, solid nanosized particles of metal oxides are synthesized (for example, bismuth oxide (BiiOs)), which quickly clog the micro and nanosized fluid-conducting channels in the joint formed by the joined tubing with TYPE 7. As the spacer 5 is heated, it gradually passes from the solid state to the liquid state, finally sealing joints of joined tubing with TYPE.

[0068] A separate section of tubing 3 3 (Fig. 3) consists, in fact, of a pipe 6 made from the above-mentioned materials and, compositely, from the same materials from which the separate sections of tubing 1 1 are made.

[0069] The longitudinal section of the tubing with TYPE 7 in assembled form is shown in Fig. 4.

[0070] On pipe 3, at its ends up to the upset end of pipe 4, a gripping zone 8 is formed, intended for gripping tubing with TYPE 7 with a hydraulic key and / or spider during assembly and disassembly work on the assembly (disassembly) of the tubing column.

[0071] The capture zone 8 is made in the form of longitudinal stiffeners 9, which are diffusion-welded to the end of the pipe 3 up to the upset end of the pipe 4 and rest against the upset end of the pipe 4. The diffusion-welded longitudinal stiffeners 9 form cells 10 for accommodating TYPE 11 (Fig. 5). The number of diffusion-welded longitudinal stiffeners depends on how strong the capture zone needs to be, which in turn depends on the weight of the tubing string; the minimum number is 6 longitudinal stiffeners. The minimum length of the capture zone is 300-350 mm.

[0072] The TYPE used is a three-layer heat-insulating coating.

[0073] The first layer of the TIP is represented by the first heat-reflective coating, a 12-mm stainless steel mirror tape with a thickness of 0.02 to 3 mm, manufactured, for example, by the Russian company "GK Stainless Steel Tape" (Moscow), wound on tubing with welded stiffeners 9 (not shown in the drawing). The purpose of this heat-reflective coating is to reduce heat loss by providing a radiation barrier. The VA stainless steel mirror tape (mirror surface) is capable of reflecting, like aluminum tape, up to 95% of the radiation that would otherwise be absorbed by the subsequent TIP layer.

[0074] The claimed invention utilizes stainless steel tape (foil) instead of aluminum foil, as aluminum tape cannot be used for direct winding onto tubing due to the high coolant temperature (up to 700°C). The temperature limit for aluminum foil does not exceed 550-600°C.

[0075] The next, second layer of TIP is made of vacuum microspheres (or aluminosilicate microspheres, which are more readily available in Russia), and the binder is liquid glass, which can withstand high temperatures—up to 1200°C. The thermal conductivity of this insulation, the closest analogue of which is liquid thermal insulation, is approximately 0.06 W / (m*K).

[0076] Liquid glass is prepared from a dry concentrate (DC) for the rapid preparation of aqueous solutions of liquid glass (manufactured by the Ecoe company, Chelyabinsk), used as a binding material for various purposes, including coating metal welding electrodes, lining steel-smelting electric furnaces, pouring ladles, in the manufacture of casting molds and cores, etc.

[0077] The most significant qualities of such thermal insulation 13 are its ability to operate in high temperature conditions, water resistance, relatively high strength and durability of use.

[0078] The third layer of the TIP is represented by a second heat-reflective coating, namely heat-resistant silver paint 14 - for example, enamel "Moskvichka KO-8101", capable of operating in the temperature range from - 60°C to +600°C. Heat-resistant silver paint 14 is applied by any suitable method to the inner surface of the protective casing 15. The tubing with TIP is equipped with a protective casing 15. Protective casing 15 can be made in the form of a pipe, preferably made of stainless steel, with a thickness of 1 - 10 mm. During assembly of the tubing with TIP, rings 16 are attached to the ends of protective casing 15 (preferably by welding), providing protection of the TIP from the effects of aggressive environments, moisture, and mechanical damage during transportation and assembly / disassembly of the tubing with TIP 7.

[0079] Alternatively, the protective casing can be made in the form of a fiberglass pipe or a carbon pipe (for example, the material “Aristar-ET”, company OOO “NIIKAM”, Russian Federation) with the calculated wall thickness of these pipes, but not less than 0.5 mm.

[0080] NKT with TYPE is manufactured as follows.

[0081] The manufacturing process of TYPE 7 tubing is explained based on the use of high-quality alumina ceramics with an aluminum oxide content of 98-99.9%.

[0082] The production of two types of individual sections of tubing 1 1 is mainly carried out using the technology of uniaxial static pressing, which is known at the modern level of technical development, namely, hot pressing at a sintering temperature of 1200-1300°C and a pressure of 20 to 40 MPa.

[0083] On pipe 3, at its ends up to the upset end of pipe 4, a gripping zone 8 is formed, intended for gripping tubing with TYPE 7 with a hydraulic key and / or spider during assembly and disassembly work on the assembly (disassembly) of the tubing column.

[0084] The capture zone 8 is made in the form of longitudinal stiffening ribs 9, which are welded using diffusion welding, a known modern technology, to the end of the pipe 3 to the upset end of the pipe 4 and rest against the upset end of the pipe 4.

[0085] To perform diffusion welding of stiffeners 9 to the end of pipe 3, grip zone 8 and stiffeners 9 are heated to 1500°C after applying a magnesium oxide (MgO) paste made of coarse particles, microparticles, and, preferably, nanoparticles to the joints to be welded. Stiffeners 9 are pressed against the end of pipe 3 with a force of 5 to 20 MPa, maintaining the temperature in the weld zone at 1500°C for 0.5 to 3 hours, and preferably for 1 hour. After 1 hour, stiffeners 9 are welded to the end of pipe 3.

[0086] After fabricating two separate 1000 mm long tubing sections (2x2) with welded stiffeners (9) and three separate 3000 mm long tubing sections (3x3), they are welded together using diffusion welding, a well-known, state-of-the-art technique. Prior to welding, magnesium oxide (MgO) paste is applied to all ends of the individual 2x2 and 3x3 tubing sections to form a single, complete tubing section. During the welding process, the welded sections are heated to 1500°C and maintained, typically for 1 hour, at a pressure of 10 MPa. This diffusion welding process does not require vacuum conditions, significantly simplifying and reducing the cost of the process.

[0087] It should be noted that the use of magnesium oxide paste significantly improves the quality of the weld and welded joints 19 in general.

[0088] A complete tubing assembly without TYPE and casing 15 has been manufactured (not shown in the figure).

[0089] Next, we apply the first heat-reflective coating to the tubing. The heat-reflective material used is stainless steel mirror tape (VA - mirror surface) 12, with a thickness of 0.02 to 3 mm, manufactured by the Russian company "GK Stainless Tape" (Moscow).

[0090] After applying the first heat-reflecting coating to the tubing, we proceed to prepare the main heat-insulating layer by mixing aluminosilicate microspheres of the ANM-150 brand (diameter up to 150 µm) produced by ForeSfera (Yekaterinburg) with dry concentrate for the preparation of liquid glass produced by Ecoe (Chelyabinsk).

[0091] Aluminosilicate microspheres have the following properties:

[0092] 1. Correct spherical shape.

[0093] Cost-effectiveness. Spherical filler requires a minimal amount of binder to moisten the side surface; any other sealant shape will require more resin, binder, water, etc.

[0094] Quality. The regularly shaped spheres provide an efficient surface area-to-volume ratio and compact packing: the packing efficiency is 60-80% of the theoretical value. Therefore, aluminosilicate microspheres exhibit less shrinkage deformation than seals with a broken shape.

[0095] Convenience. The round shape of the filler gives the materials good flowability: they are easy to dispense (including gravity-flow), and convenient to apply to surfaces—by hand with a spatula, by spraying under pressure, by pumping, etc.

[0096] 2. Low density and high strength. The density of aluminosilicate microspheres is several times lower than that of other mineral fillers (bulk density of aluminosilicate microspheres is 0.32-0.37 g / cm3 , true density - 0.58-0.69 g / cm 3 ), therefore, it is more convenient to mix and more economical to transport. At the same time, the strength of the microsphere allows it to withstand hydrostatic pressures in excess of 100 atm. (The thickness of the microsphere walls ranges from 2 to 10 µm, the density of the wall material is 2.5 g / cm 3 ). The compressive strength of aluminosilicate microspheres is 150-280 kg / cm 2 , hardness on the Mohs scale is 5-6.

[0097] 3. Low reactivity.

[0098] Aluminosilicate microspheres do not affect the chemical composition or reactivity of most mixtures in which they are used as a filler. The main components of the microspheres' phase-mineral composition are aluminosilicate glass phase, mullite, and quartz. The main chemical components are silicon, aluminum, and iron. The gas phase inside the microspheres consists of nitrogen and carbon dioxide. The microspheres are pH-neutral and resistant to acids and alkalis.

[0099] 4. High melting point and low thermal conductivity.

[0100] Aluminosilicate microspheres retain their properties when heated to 980°C and melt at 1400-1500°C. Moreover, aluminosilicate microspheres have low thermal conductivity, which gives the materials high thermal insulation qualities and allows for the creation of fireproof coatings [3].

[0101] After mixing, the mixture, consisting of aluminosilicate microspheres and dry powder for making liquid glass (the proportions are determined experimentally), is mixed with water. Typically, 1 ton of dry powder yields 2 to 4 tons of liquid glass. The required density of the liquid glass is determined only by the amount of water added to the dry mixture. This type of thermal insulation can be used at temperatures up to 1200°C.

[0102] This thermal insulation 13 is applied to the surface of the tubing, which has already been wrapped with the first heat-reflecting coating 12, in the following manner (Fig. 6).

[0103] The protective casing 15 with a ring 16 welded to one end of the tubing, the inner surface of which has been pre-applied with a second heat-reflective coating—for example, Moskvichka KO-8101 enamel—is installed vertically so that the welded ring 16 is at the bottom of the tubing. The vertically installed protective casing 15 is secured with supports 17, and the tubing is placed in the protective casing 15, sliding it onto the internal centralizer 18. The empty space formed by the outer surface of the tubing with the first heat-reflective coating 12 applied to its surface and the inner surface of the protective casing 15 with the second heat-reflective coating 14 applied to it is filled with liquid thermal insulation 13. A vibrator 19 is used to compact it. After hardening, the thermal insulation 13 is ready for use.

[0104] Before the thermal insulation 13 hardens, a second ring 16 is welded to the upper part (upper end) of the TYPE 7 tubing. In this case, the liquid thermal insulation 13, which is in a liquid state, fits tightly and is well secured to the inner surface of the second ring 16.

[0105] NKT TYPE 7 is manufactured and ready for use.

[0106] During operation of the assembled tubing string with TYPE 7, spacers 5 increase the degree of tightness of the joint in the case of using a threadless coupling.

[0107] In the design of TYPE 7 tubing, mainly high-quality (99.8-99.9% AlO3) alumina ceramics are used, which have the required high tensile strength, wear resistance, density, hardness, bending strength, resistance to chemically aggressive environments and corrosion for tubing transporting RAW in the form of USKV or SKV.

[0108] Thus, a TYPE 7 tubing was obtained that combines simple design, ease of manufacture, relatively low production costs, sufficient thermal insulation characteristics, reliability and a long service life in the presence of an aggressive environment (USKV or SKB), as well as high temperatures (up to 700° C) and pressure (up to 60 MPa).

Claims

Invention formula 1. A tubing string (TUB) comprising a pipe, the outer surface of which is wrapped in a first layer of a first heat-reflecting material - stainless steel foil, and then a second layer of heat-insulating coating, closed on top by a protective casing, on the inner surface of which a second heat-reflecting material is applied - heat-resistant silver enamel, two heat-insulated gripping zones designed for gripping the pipe with a hydraulic wrench or spider during installation and dismantling of the TUB, characterized in that the TUB pipe is made of alumina ceramics with an aluminum oxide content of more than 95% and a mixture of particles of metal and non-metal oxides and non-metal and non-metal oxides up to 5%, each heat-insulated gripping zone is equipped with outward-facing stiffeners fixed to the surface of the pipe by diffusion welding, forming cells for placing a heat-insulating coating in them.

2. The tubing according to paragraph 1, characterized in that it is made from large particles from 2500 to 10000 nm individually or from a mixture of such large particles.

3. NKT according to item 1, characterized in that it is made from microparticles from 100 to 2500 nm individually or from a mixture of such microparticles.

4. NKT according to item 1, characterized in that it is made from nanoparticles individually or from a mixture of such nanoparticles having a size from 0.1 to 100 nm.

5. NKT according to item 1, characterized in that the size of the aluminum oxide particles is from 0.1 to 100 nm.

6. The tubing according to item 1, characterized in that the mixtures of particles of metal and non-metal oxides and non-metal and non-metal oxides are nanoparticles of zirconium dioxide, manganese oxide, magnesium oxide, silicon oxide, iron oxide, chromium oxide, titanium dioxide and tungsten oxide, silicon carbide, silicon nitride, boron carbide, nickel or chromium.

7. NKT according to item 1, characterized in that a heat-insulating material compositely consisting of aluminosilicate microspheres is used as a second layer of heat-insulating coating on the outer surface of the pipe, and hardened liquid glass prepared from dry concentrate of liquid glass is used as a binder.

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