Patent Description:
Currently, fire coal is used for heating in winter in most areas, and there is inevitably a loss of heating power during heating power transmission, and therefore consumption of fire coal increases sharply. With the continuous decrease of energy resources, reducing energy consumption has become one of problems to be resolved urgently.

Geothermal heat is heat energy contained in the earth. It has two different sources, one comes from an exterior of the earth, and the other comes from an interior of the earth. From the earth surface to the earth interior, impact of solar radiation gradually decreases, and to a specific depth, this impact disappears, temperature is unchanged all the year round, that is, the so-called "normal temperature layer" is reached. It can be seen from the normal temperature layer downwards that, impact of heat inside the earth on earth temperature gradually increases, and the heat energy from the earth interior is referred to as "internal heat". An increment of ground temperature when an underground depth is increased by <NUM> or <NUM> is referred to as a geothermal gradient. In view of development and utilization of geothermal energy resource, compared with other renewable energy sources, the geothermal energy resource has more development potential and is attracting increasing attention all over the world.

A geothermal resource is mainly applied to the following several aspects currently:
Geothermal power generation, which is a most direct manner of geothermal utilization. Principles of geothermal power generation and thermal power generation are the same, and they are that steam thermal energy in a turbine is transformed into mechanical energy, and then the mechanical energy drives a generator to generate electricity. A difference is that, unlike thermal power generation, geothermal power generation does not need a huge boiler and does not need to consume fuel, and energy used for geothermal power generation is geothermal energy. A process of geothermal power generation is a process in which underground heat energy is transformed into mechanical energy first and then the mechanical energy is transformed into electric energy. Currently, a heating medium that can be used by a geothermal power station is mainly natural steam and hot water underground.

Geothermal heating, which is a terrestrial heat utilization mode that ranks only second to geothermal power generation and in which geothermal energy is directly used for heating, supplying heat, and supplying hot water.

Application of geothermal energy in agriculture: geothermal water with suitable temperature is used to irrigate farmland, to make crops can early-mature and increase production of crops; geothermal water is used for fish-farming, fish fattening can be accelerated in <NUM> water, and a fish yield rate is increased; geothermal heat is used for greenhouse building, sprout cultivation, growing vegetables, and growing flowers; geothermal heat is used for heating a biogas digester, increasing a biogas yield, and the like.

Geothermal industrial utilization: geothermal water includes many valuable rare elements, radioactive elements, rare gases, and compounds such as bromine, iodine, boron, potassium, helium, heavy water, potassium salts, and the like, and is an indispensable raw material for national defense industry, atomic energy industry, chemical engineering industry, and agriculture.

Geothermal medical treatment and traveling: geothermal water has relatively high temperature, special chemical components, gas components, a small amount of biological active ions, radioactive substances, and the like, forms mineral mud in some geothermal areas, and has obvious medical treatment and health care effects on human body.

A geothermal energy resource has an extensive utilization value. To better use the geothermal resource, the following problems further need to be resolved: a low geothermal heat utilization, few exploitable geothermal resources, and high exploitation costs.

Due to a limitation of current exploitation technologies, only shallow geothermal resources can be used. In an exploitation process, a thermal insulation effect of a tubular product is poor, which further reduces geothermal heat utilization and greatly affects exploitation and utilization of geothermal energy.

Similarly, during a process of underground petroleum exploitation, a thermal insulation effect of a pipe is poor, leading to an increase in difficulty in petroleum exploitation. Petroleum is also referred to as crude oil, which is brownish black combustible thick liquid exploited from deep underground. A freezing point of crude oil is approximately between -<NUM> and <NUM>. During an exploitation process, a thermal insulation effect of a pipe is poor, which easily leads to crude oil solidification in the exploitation pipe, and it is needed to timely heat the solidified crude oil to ensure smooth exploitation, which greatly increases costs and a period of petroleum exploitation. Therefore, during a petroleum exploitation process, a pipe with a good thermal insulation effect is also needed.

The patent <CIT>) has disclosed a vacuum insulation pipe. An outer steel pipe is sleeved outside a working steel pipe. Several movable supports are fastened to the working steel pipe. Two ends of a fixed support are connected to the outer steel pipe and the working steel pipe, respectively. Thermal insulation cotton is filled between the working steel pipe and the outer steel pipe, and there is a vacuum state between the outer steel pipe and the working steel pipe. Vacuum thermal insulation improves thermal insulation performance of a tubular product. However, for a casing pipe with a relatively large length, the movable support cannot play support role well, and the outer steel pipe and the working steel pipe of this product are connected by relying on the fixed support. When the product is used for underground work at a depth of thousands of meters, deformation is easily caused, leading to a failure of the fixed support and seriously shortening a service life of the pipe.

The patent <CIT>) has disclosed an insulation steel jacket pipe, including a working steel pipe, a PPR pipe sleeved outside the working steel pipe, and a protecting steel pipe sleeved outside the PPR pipe, where an airtight cavity is formed between the working steel pipe and the PPR pipe; a support frame configured to make the working steel pipe and the PPR pipe keep coaxial is disposed between the working steel pipe and the PPR pipe; and a heating element is further disposed on an outer wall of the working steel pipe. A PPR pipe is further disposed in the middle of the insulation steel jacket pipe, and the heating element is disposed on the outer wall of the working steel pipe, so as to implement an thermal insulation effect of the insulation steel jacket pipe. The steel pipe cannot be applicable to underground heat source exploitation work, and the addition of the PPR pipe may improve the thermal insulation effect to a specific extent. However, in a working environment with relatively high geothermal temperature, the PPR pipe is heated and deformed, and consequently, the thermal insulation effect is rapidly reduced.

<CIT> discloses a super-long thermal insulation steel jacket pipe according to the preamble of claim <NUM>.

Therefore, how to improve a thermal insulation effect of a pipe during underground work is to resolve many energy consumption problems in geothermal energy source exploitation and petroleum exploitation.

Based on the foregoing problem, an objective of the present invention is to provide a super-long thermal insulation steel jacket pipe. The steel jacket pipe can be used for exploitation and development of underground geothermal resources and petroleum resources, and has a good thermal insulation effect and long service life. Super long pipes with different specifications can be fabricated according to different working environments. A vacuum insulation layer is disposed in the pipe, and a vacuum degree can be kept continuously from being affected by underground pressure and temperature.

Another objective of the present invention is to provide a machining process and an application of the super-long thermal insulation steel jacket pipe.

The super-long thermal insulation steel jacket pipe in the present invention includes a working steel pipe and an outer steel pipe, where the outer steel pipe is sleeved outside the working steel pipe, an annular cavity formed by a gap is reserved between the working steel pipe and the outer steel pipe; a support frame is disposed between the working steel pipe and the outer steel pipe; the annular cavity is a vacuum cavity, two ends of the outer steel pipe are tightened, a tightened part of the outer steel pipe is sealed with an outer wall of the working steel pipe through several seal rings, and the annular cavity is further filled with a phase-change material; the support frame is a spiral annular support frame, the spiral annular support frame is made of an elastic material, the spiral annular support frame is sleeved on an outer peripheral side of the working steel pipe, tightly supports an inner wall of the outer steel pipe, and is not in contact with the working steel pipe.

The phase-change material is an organic phase change material, and is preferably paraffin. The phase-change material is added to the annular cavity. This can effectively store heat, and release heat when temperature of an external environment is low, thereby increasing the insulation performance of the pipe.

The spiral annular support frame is not in contact with the working steel pipe, and tightly supports an inner wall of the outer steel pipe, so as to keep cut-through of the annular cavity in the pipe, facilitating vacuumizing treatment.

The spiral annular support frame or the C-shaped support frame, not part of the present invention, is made of an elastic material. Most conventional support frames are fixed supports made of a steel material, but no elastic material has been used as a support structure currently to fully support an outer steel pipe. To improve mechanical performance of the steel jacket pipe fabricated in the present invention during underground work, an elastic material is selected as a support material, so as to buffer the damage caused by external mechanical force to the working steel pipe. The elastic material used in the present invention is preferably rubber.

The C-shaped support frames, not part of the present invention, wind outside the working steel pipe at intervals, which is easy to install. In addition, the annular cavity is formed between adjacent C-shaped support frames, the working steel pipe, and the outer steel pipe. By using C-shaped supports with different orientations and opening sizes, the annular cavity can be kept cut through, which is convenient for vacuumizing treatment of the annular cavity.

Further, stability and thermal insulation performance of the steel jacket pipe are ensured, especially during working at an underground depth greater than <NUM> meters, working environment pressure, temperature, and the like do not cause deformation of an end of the pipe. In the present invention, solder sealing is further performed on the end of the steel jacket pipe.

To further improve a thermal insulation effect, a thickness of the annular cavity is <NUM> to <NUM>. For the annular cavity, an excessively large thickness causes an increase in production costs, while an excessively small thickness cannot effectively ensure the insulation effect of the annular cavity. When the thickness of the annular cavity is <NUM> to <NUM>, an optimum insulation effect is achieved.

An anti-corrosion layer is prepared by coating anti-corrosion liquid. The anti-corrosion liquid is composed of the following components by weight parts: silicone oil <NUM>-<NUM>, zinc powder <NUM>-<NUM>, citric acid <NUM>-<NUM>, epoxy resin <NUM>-<NUM>, aluminum oxide <NUM>-<NUM>, diatomite <NUM>-<NUM>, and polyacrylamide <NUM>-<NUM>. Preferably, the anti-corrosion liquid is composed of the following components by weight parts: silicone oil <NUM>, zinc powder <NUM>, citric acid <NUM>, epoxy resin <NUM>, aluminum oxide <NUM>, diatomite <NUM>, and polyacrylamide <NUM>. The foregoing components of the anti-corrosion liquid are mixed evenly according to the proportion and then coated on an outer wall of the outer steel pipe, and an anti-corrosion layer with a thickness of <NUM> to <NUM> can be formed through layer-by-layer coating.

A length of the steel jacket pipe is <NUM> to <NUM>.

Preferably, the working steel pipe and the outer steel pipe are made of any one or a combination of stainless steel, carbon steel, or titanium alloy. Preferably, the thickness of the annular cavity is <NUM> to <NUM>.

Main components of stainless steel include the following by weight percentage: C <NUM>%-<NUM>%, Si <NUM>%-<NUM>%, Mn <NUM>%-<NUM>%, P <NUM>%, S <NUM>%, Ni <NUM>%-<NUM>%, Cr <NUM>%-<NUM>%, N <NUM>%-<NUM>%, Cu <NUM>%-<NUM>%, Mo <NUM>%-<NUM>%, and Fe and inevitable impurities as balance. Tensile strength of stainless steel is greater than or equal to <NUM> MPa, yield strength is greater than or equal to <NUM> MPa, internal yield pressure can reach <NUM> Mpa, and collapse pressure can reach <NUM> Mpa.

Main components of carbon steel include the following by weight percentage: C <NUM>%, Si <NUM>%-<NUM>%, Mn <NUM>%-<NUM>%, P <NUM>%-<NUM>%, S <NUM>%, Cr <NUM>%-<NUM>%, Ni <NUM>%, Cu <NUM>%, Mo <NUM>%-<NUM>%, and Fe and inevitable impurities as balance. Tensile strength of carbon steel is greater than or equal to <NUM> MPa, yield strength is greater than or equal to <NUM> MPa, internal yield pressure can reach <NUM> Mpa, and collapse pressure can reach <NUM> Mpa.

Titanium alloy is TA18 alloy, and main components of TA18 alloy include the following by weight percentage: Al <NUM>%-<NUM>%, V <NUM>%-<NUM>%, Fe <NUM>%, C <NUM>%, N <NUM>%, H <NUM>%, O <NUM>%, and Ti and inevitable impurities as balance. Tensile strength of TA18 alloy is greater than or equal to <NUM> MPa, yield strength is greater than or equal to <NUM> MPa, internal yield pressure can reach <NUM> Mpa, and collapse pressure can reach <NUM> Mpa.

The present invention further provides a machining process of the super-long thermal insulation steel jacket pipe, specifically includes the following steps:.

Preferably, in step (<NUM>) of the present invention, before heat treatment of the steel jacket pipe fabricated in step (<NUM>), the steel jacket pipe needs to be first rolled into an S shape, to prevent a decrease in mechanical performance of the pipe when the pipe is installed for use.

The super-long thermal insulation steel jacket pipe in the present invention can be applied to exploitation of underground petroleum and an underground heat source, and can be used in working at an underground depth of <NUM> to <NUM>.

Compared with the prior art, the present invention has the following beneficial effects: The super-long thermal insulation steel jacket pipe in the present invention has relatively good thermal insulation performance and corrosion resistance. Because its annular cavity is in a vacuum state, and the pipe is internally filled with a phase change energy storage material, the thermal insulation performance of the working steel pipe can be fully ensured. When the pipe is used for underground energy exploitation, temperature in the working steel pipe in the pipe can be effectively kept unaffected when external temperature decreases. To avoid impact of pressure, temperature, and the like in underground work, the spiral annular support frame used in the present invention supports the outer steel pipe, so as to keep cut-through of the annular cavity. The steel jacket pipe in the present invention has long service life, and greatly reduces costs of exploitation of petroleum and an underground heat source.

To describe the technical solutions in the embodiments of the present invention or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments.

Reference signs: <NUM>. working steel pipe; <NUM>. outer steel pipe; <NUM>. annular cavity; <NUM>. rubber ring; <NUM>. spiral annular support frame; <NUM>. C-shaped support frame.

The following describes the present invention in detail with reference to the accompanying drawings and specific embodiments.

A super-long thermal insulation steel jacket pipe in the present invention is shown in <FIG>, and includes a working steel pipe <NUM> and an outer steel pipe <NUM>, where the outer steel pipe <NUM> is sleeved outside the working steel pipe <NUM>, an annular cavity <NUM> formed by a gap is reserved between the working steel pipe <NUM> and the outer steel pipe <NUM>; a support frame is disposed between the working steel pipe <NUM> and the outer steel pipe <NUM>; the annular cavity <NUM> is a vacuum cavity, two ends of the outer steel pipe <NUM> are tightened, a tightened part of the outer steel pipe <NUM> is sealed with an outer wall of the working steel pipe <NUM> through several seal rings <NUM>, and the annular cavity <NUM> is further filled with a phase-change material; the support frame is a spiral annular support frame <NUM>, the spiral annular support frame <NUM> is sleeved on an outer peripheral side of the working steel pipe <NUM>, and is not in contact with the working steel pipe <NUM>.

In some embodiments, not part of the present invention, a super-long thermal insulation steel jacket pipe in the present invention is shown in <FIG>, and includes a working steel pipe <NUM> and an outer steel pipe <NUM>, where the outer steel pipe <NUM> is sleeved outside the working steel pipe <NUM>, an annular cavity <NUM> formed by a gap is reserved between the working steel pipe <NUM> and the outer steel pipe <NUM>; a support frame is disposed between the working steel pipe <NUM> and the outer steel pipe <NUM>; two ends of the outer steel pipe <NUM> are tightened, a tightened part of the outer steel pipe <NUM> is sealed with an outer wall of the working steel pipe <NUM> through several seal rings <NUM>, and the annular cavity <NUM> is further filled with a phase-change material; and the support frame is a C-shaped support frame <NUM>, and several C-shaped support frames <NUM> wind an outer peripheral side of the working steel pipe <NUM> at intervals.

In some embodiments, a thickness of the annular cavity of the super-long thermal insulation steel jacket pipe in the present invention is <NUM> to <NUM>. The spiral annular support frame of the super-long thermal insulation steel jacket pipe in the present invention is made of an elastic material, and is preferably made of rubber. In some embodiments, the phase-change material of the super-long thermal insulation steel jacket pipe in the present invention is an organic phase-change material and is preferably paraffin.

The working steel pipe and the outer steel pipe of the steel jacket pipe in the present invention are made of any one of stainless steel or carbon steel; or a combination of stainless steel, carbon steel, or titanium alloy.

With reference to specific examples, the following describes a process for fabricating the insulation steel jacket pipe in the present invention by using different combinations of steel materials.

Stainless steel is selected as a steel material of a working steel pipe, and main components of stainless steel include the following by weight percentage: C <NUM>%, Si <NUM>%, Mn <NUM>%, P <NUM>%, S <NUM>%, Ni <NUM>%, Cr <NUM>%, N <NUM>%, Cu <NUM>%, Mo <NUM>%, and Fe and inevitable impurities as balance. Titanium alloy TA18 is selected as a steel material of an outer steel pipe, and main components of TA18 alloy include the following by weight percentage: Al <NUM>%, V <NUM>%-<NUM>%, Fe <NUM>%, C <NUM>%, N <NUM>%, H <NUM>%, O <NUM>%, and Ti and inevitable impurities as balance. A <NUM>-meter insulation steel jacket pipe fabricated by using the foregoing selected steel materials (the two steel materials both have a length of <NUM> meters) is shown in <FIG>, and a specific fabrication process thereof includes the following steps:.

Titanium alloy TA18 is selected as a material for fabricating a working steel pipe, and main components of TA18 alloy include the following by weight percentage: Al <NUM>%, V <NUM>%, Fe <NUM>%, C <NUM>%, N <NUM>%, H <NUM>%, O <NUM>%, and Ti and inevitable impurities as balance. Carbon steel is selected as a material for fabricating an outer steel pipe, and main components of carbon steel include the following by weight percentage: C <NUM>%, Si <NUM>%, Mn <NUM>%, P <NUM>%, S <NUM>%, Cr <NUM>%, Ni <NUM>%, Cu <NUM>%, Mo <NUM>%, and Fe and inevitable impurities as balance. A <NUM>-meter insulation steel jacket pipe fabricated by using the foregoing selected steel materials (the two steel materials both have a length of <NUM> meters) is shown in <FIG>, and a specific fabrication process of the pipe includes the following steps:.

Carbon steel is selected as a material for fabricating a working steel pipe, and main components of carbon steel include the following by weight percentage: C <NUM>%, Si <NUM>%, Mn <NUM>%, P <NUM>%, S <NUM>%, Cr <NUM>%, Ni <NUM>%, Cu <NUM>%, Mo <NUM>%, and Fe and inevitable impurities as balance. Stainless steel is selected as a material for fabricating an outer steel pipe, and main components of stainless steel include the following by weight percentage: C <NUM>%, Si <NUM>%, Mn <NUM>%, P <NUM>%, S <NUM>%, Ni <NUM>%, Cr <NUM>%, N <NUM>%, Cu <NUM>%, Mo <NUM>%-<NUM>%, and Fe and inevitable impurities as balance. A <NUM>-meter insulation steel jacket pipe is fabricated by using the foregoing selected steel materials (the two steel materials both have a length of <NUM> meters), and a fabrication process of the pipe includes the following steps:.

Titanium alloy TA18 is selected as a material for fabricating a working steel pipe and an outer steel pipe, and main components of TA18 alloy include the following by weight percentage: Al <NUM>%, V <NUM>%, Fe <NUM>%, C <NUM>%, N <NUM>%, H <NUM>%, O <NUM>%, and Ti and inevitable impurities as balance. An <NUM>-meter insulation steel jacket pipe is fabricated by using the foregoing selected steel materials (the two steel materials both have a length of <NUM> meters). The pipe is fabricated according to the process in Embodiment <NUM>, and only the heat treatment process of the steel jacket pipe in step (<NUM>) is changed, and the heat treatment process in step (<NUM>) specifically includes: heating the steel jacket pipe at <NUM> for <NUM>, air-cooling to room temperature, and coating the anti-corrosion liquid in Embodiment <NUM>. In this case, the <NUM>-meter insulation steel jacket pipe in the present invention is fabricated.

The insulation steel jacket pipes each fabricated in Embodiment <NUM> and Embodiment <NUM> of the present invention and Example <NUM> and Example <NUM> not part of the present invention are used to perform a test operation to simulate heat source exploitation in an underground working environment. Temperature of extracted water is set to <NUM>, <NUM>, <NUM>, and <NUM>, respectively. The <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is used to extract a <NUM> water source, an environment outside the pipe is simulated to be an environment at temperature of <NUM> meters underground to the land surface (it is specified that the pipe is placed into the <NUM> meters underground to extract the <NUM> water source), step heating is performed on the pipe until temperature of a top end of the pipe is room temperature. Similarly, the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is used to extract a <NUM> water source; the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is used to extract a <NUM> water source; and the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is used to extract a <NUM> water source. It can be found by detecting temperature of a water source extracted from a pipe outlet, that temperature of the water source extracted by the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is <NUM>, temperature of the water source extracted by the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is <NUM>, temperature of the water source extracted by the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is <NUM>, temperature of the water source extracted by the <NUM>-meter steel jacket pipe fabricated in Embodiment <NUM> is <NUM>. It can be learned from the foregoing that the super-long thermal insulation steel jacket pipes have very good thermal insulation performance, and it can be found through detection of a tested steel jacket pipe that no obvious mechanical deformation occurs on a working steel pipe or an outer steel pipe in the pipe.

Claim 1:
A super-long thermal insulation steel jacket pipe, wherein a length of the steel jacket pipe is <NUM> to <NUM>, comprising a working steel pipe (<NUM>) and an outer steel pipe (<NUM>),
wherein the outer steel pipe (<NUM>) is sleeved outside the working steel pipe (<NUM>), an annular cavity (<NUM>) formed by a gap is reserved between the working steel pipe (<NUM>) and the outer steel pipe (<NUM>);
a support frame is disposed between the working steel pipe (<NUM>) and the outer steel pipe (<NUM>); a
the annular cavity (<NUM>) is a vacuum (<NUM>), the annular cavity (<NUM>) is further filled with a phase-change material; the support frame is a spiral annular support frame (<NUM>), the spiral annular support frame is sleeved on an outer peripheral side of the working steel pipe (<NUM>) and tightly supports an inner wall of the outer steel pipe (<NUM>), characterized in that:
two ends of the outer steel pipe (<NUM>) are tightened, a tightened part of the outer steel pipe (<NUM>) is sealed with an outer wall of the working steel pipe (<NUM>) through several seal rings (<NUM>), the spiral annular support frame (<NUM>) is made of an elastic material and is not in contact with the working steel pipe (<NUM>).