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CN-122015017-A - High-efficiency energy-saving conveying method for large-caliber thermal pipeline based on phase-change heat preservation

CN122015017ACN 122015017 ACN122015017 ACN 122015017ACN-122015017-A

Abstract

The invention discloses a high-efficiency energy-saving conveying method for a large-caliber thermal pipeline based on phase change heat preservation, relates to the field of thermal pipeline conveying, and solves the problems of temperature preservation difference, high energy consumption and inaccurate regulation and control of the existing pipeline. The intelligent temperature compensation control system comprises a step phase change heat preservation layer, a vacuum filling auxiliary heat preservation layer and an outer protective layer which are sequentially paved on the outer wall of a pipeline working pipe, wherein the step phase change heat preservation layer is adapted in a segmented mode according to an axial temperature attenuation rule to realize dynamic temperature compensation, an electric intelligent control system collects temperature and pressure data through distributed monitoring nodes, a control terminal PID gain calibration model is used for generating an instruction, the control equipment is controlled to operate accurately, the conveying process is optimized, and the number of heat compensation stations is reduced. The intelligent heat-insulating device has the advantages of remarkably improving heat-insulating performance, reducing thermal loss, realizing intelligent and accurate regulation and control, reducing energy consumption and operation and maintenance cost, adapting to long-distance large-flow heat supply requirements and having strong practicability.

Inventors

  • JIANG TIELIU
  • Hao Die
  • WANG YINGQIAN

Assignees

  • 东北电力大学

Dates

Publication Date
20260512
Application Date
20260319

Claims (8)

  1. 1. The efficient energy-saving conveying method for the large-caliber thermal pipeline based on phase-change heat preservation is characterized by comprising the following steps of: S1, a pipeline heat preservation system is designed in an adapting mode, namely a multi-layer heat preservation system adapting to a large-caliber heat distribution pipeline is built in advance, the heat preservation system sequentially corresponds to a working pipe, a step phase-change heat preservation layer, an auxiliary heat preservation layer and an outer protective layer from inside to outside, sealing treatment is conducted among the layers, heat preservation tightness is guaranteed, and a foundation is laid for follow-up electrical intelligent regulation and heat preservation construction. S2, screening and preparing the composite phase-change heat-insulating material, namely screening the matched composite phase-change material according to the working temperature range of the large-caliber heat pipeline, wherein the composite phase-change material is formed by mixing, melting and solidifying and has good chemical compatibility with an auxiliary heat-insulating material. S3, constructing a step phase-change heat-insulating layer, namely processing the prepared composite phase-change material into heat-insulating units, attaching the heat-insulating units to the outer wall of a working pipe to form the step phase-change heat-insulating layer, wherein the step phase-change heat-insulating layer is axially divided into a plurality of heat-insulating sections along the pipeline, the phase-change temperature of the composite phase-change material in each heat-insulating section is determined through calculation of a dynamic temperature attenuation matching formula, the temperature of a medium in the pipeline is adapted to the natural attenuation law, and the heat-insulating units are subjected to airtight treatment to ensure that the phase-change material is free from leakage. S4, auxiliary heat preservation and external protection construction, namely paving an auxiliary heat preservation layer outside the step phase-change heat preservation layer, constructing an external protection layer outside the auxiliary heat preservation layer, preventing external water vapor and impurities from entering the heat preservation layer, and guaranteeing heat preservation effect and normal operation of the electrical monitoring element. S5, the electric intelligent regulation and control system operates, namely an electric monitoring node is arranged along the pipeline, medium temperature, pressure and temperature data related to the heat preservation layer in the pipeline are collected in real time and transmitted to an intelligent regulation and control terminal, the intelligent regulation and control terminal analyzes and processes the data based on a PID regulation and control gain coefficient calibration model, pipeline conveying parameters are adjusted in a self-adaptive mode, dynamic regulation and control of the pipeline temperature are achieved by combining heat storage and release characteristics of phase change materials, and energy consumption is reduced. S6, full life cycle operation and maintenance management, namely performing performance detection and maintenance on the pipeline heat-insulating layer regularly, performing performance reinspection and replacement on the composite phase-change material, periodically maintaining an electrical intelligent regulation and control system to ensure normal operation of the system, establishing a pipeline operation database, optimizing regulation and control parameters, and realizing energy-saving operation and maintenance.
  2. 2. The high-efficiency energy-saving conveying method for the large-caliber heat pipeline based on phase change heat preservation according to claim 1 is characterized in that in the step S2, a fused salt or sugar alcohol material is used as a base material, a heat conduction enhancer, a leakage preventing agent and a stability regulator are added, wherein the heat conduction enhancer is one or more of graphene, carbon fiber or metal powder, the addition amount is 3% -8% of the mass of the base material, the leakage preventing agent is organic silicon resin or a high-molecular sealant, the addition amount is 2% -5% of the mass of the base material, the stability regulator is hydroxystearic acid or polyethylene glycol, and the addition amount is 1% -3% of the mass of the base material.
  3. 3. The high-efficiency energy-saving conveying method for the large-caliber heat distribution pipeline based on phase change heat preservation, which is disclosed in claim 1, is characterized in that in the step S3, the thickness of a stepped phase change heat preservation layer is 50-150mm, the thickness of an auxiliary heat preservation layer is 30-80mm, the thickness of an outer protective layer is 10-20mm, the heat preservation units are jointed in a tongue-and-groove jointing mode, high-temperature resistant sealant is adopted at the jointing part to seal, no gap is ensured, and the dynamic temperature attenuation matching formula is as follows: ; Wherein: the target temperature of the medium of the ith heat preservation section at the position which is far from the heat source x is set as the unit of the target temperature; The initial temperature of the medium at the inlet of the pipeline is expressed as the unit of the temperature; When no phase change is adopted for heat preservation, the natural temperature at the position x away from the heat source is reduced, and the unit is the temperature; the thermal storage temperature drop compensation value of the phase change material of the kth heat preservation section is shown in the unit of DEG C; i is a number of insulation segments, i=1, 2.
  4. 4. The high-efficiency energy-saving conveying method for the large-caliber thermal pipeline based on phase change heat preservation, which is disclosed in claim 1, is characterized in that in the step S5, the electrical monitoring node is arranged every 1-2km, a temperature sensor, a pressure sensor, a wireless transmission module and a data acquisition unit are integrated, the precision of the temperature sensor is less than or equal to +/-0.1 ℃, the precision of the pressure sensor is less than or equal to +/-0.01 MPa, the wireless transmission module adopts LoRa or 5G communication protocol, the transmission delay is less than or equal to 500ms, and the PID regulation gain coefficient calibration model is as follows: ; Wherein: 、 、 The proportional, integral and differential gain coefficients after calibration are respectively; 、 、 initial gain coefficients for the PID algorithm; The unit is the temperature of the medium deviation from the target temperature; The unit is the temperature deviation change rate which is the temperature deviation per minute; 、 、 the nonlinear calibration function based on the pipeline working condition is obtained through fitting on-site actual measurement data.
  5. 5. The high-efficiency energy-saving conveying method for the large-caliber heat pipeline based on phase change heat preservation according to claim 1 is characterized in that in the step S6, the heat preservation performance detection comprises tightness detection and heat loss detection, the tightness detection adopts a vacuum pressure detection method, the heat loss detection adopts a heat flow meter method, the maintenance of an electrical monitoring node comprises sensor precision calibration, and the calibration adopts a standard signal source comparison mode.
  6. 6. The high-efficiency energy-saving conveying method for the large-caliber heat distribution pipeline based on phase change heat preservation, which is disclosed by claim 1, is characterized in that the composite phase change material can be reused, the service life of the composite phase change material after performance restoration treatment is prolonged, an auxiliary heat preservation layer is in a modularized design, and is convenient to detach, overhaul and replace, and the electrical intelligent regulation and control system can realize remote monitoring and fault alarm.
  7. 7. The phase-change heat preservation-based high-efficiency and energy-saving conveying method for the large-caliber heat distribution pipeline, which is disclosed in claim 1, is characterized in that the large-caliber heat distribution pipeline is defined as a heat distribution pipeline with a nominal diameter DN being more than or equal to 400 mm.
  8. 8. The high-efficiency energy-saving conveying method for the large-caliber heat distribution pipeline based on phase change heat preservation, which is disclosed in claim 1, is characterized in that the solid-liquid phase change latent heat of the composite phase change material in the step S2 is more than or equal to 100kJ/kg, and the heat conductivity coefficient is less than or equal to 1.0W/(m.K).

Description

High-efficiency energy-saving conveying method for large-caliber thermal pipeline based on phase-change heat preservation Technical Field The invention relates to the technical field of heat transport, in particular to a high-efficiency energy-saving transport method of a large-caliber heat pipeline based on phase change heat preservation. Background The city central heating system and the industrial heat transfer pipe network are important components of modern energy infrastructure, wherein the large-caliber heat transfer pipeline (DN is more than or equal to 400 mm) becomes a core carrier for long-distance heat transfer due to large transfer flow and wide coverage range, and is widely applied to projects such as cross-regional heat supply, industrial waste heat recovery and the like. Along with the promotion of energy conservation and emission reduction policies in China, the energy conservation and high efficiency requirements of heat transmission are urgent, and the integration of a heat preservation technology and a regulation technology is a key for reducing heat loss of a pipeline and improving the energy utilization rate, so that the heat preservation technology and the regulation technology become the research focus in the technical field of the current heat pipeline. In actual operation, the heat loss of the pipeline is commonly influenced by external factors such as ambient temperature, air speed convection, soil heat conductivity coefficient, laying depth, surface water content and the like, and internal factors such as local heat bridge effect of structural parts such as pipeline interfaces, flanges, elbows, tee joints and the like, splicing gaps of heat preservation layers, ageing and attenuation of materials and the like, and the heat loss presents dynamic fluctuation characteristics, so that the energy consumption and temperature fluctuation of a heating system are further aggravated. At present, the heat preservation mode of the large-caliber heating pipeline mainly adopts the traditional passive heat preservation technology, such as wrapping heat preservation materials of polyurethane, rock wool and the like, and the regulation and control mode is mostly manual regulation, so that the large-caliber heating pipeline has a plurality of technical limitations, namely the traditional heat preservation material only can delay heat dissipation, does not have heat storage and release capacity, cannot adapt to the fluctuation characteristics of the load of a heating system along with time and environmental temperature change, is lack of effective electrical intelligent regulation and control means, causes frequent regulation of a heat source to adapt to load change, reduces the operation efficiency, also causes a large amount of energy waste, and according to statistics, the comprehensive energy utilization rate of the traditional heating system is only 60% -70%, is far lower than the theoretical level, and even if the large-caliber pipeline is conveyed for a long distance, the temperature drop is quite obvious, when the pipeline is conveyed for more than 5 km, the heating station is always required to be arranged midway, the initial investment, the floor area and the maintenance cost are greatly increased, the interface combination property of the traditional heat preservation material and the pipeline is poor, the heat source is easy to fall off and age, the pollution problem easily occurs in the solid-liquid phase change process, the comprehensive energy utilization rate of the traditional heat preservation system is only reduced, the temperature of the heat source is greatly reduced, the temperature fluctuation of the heat preservation layer is greatly reduced, the temperature fluctuation of the heat preservation temperature can not be well regulated and the temperature can be controlled by the intelligent heat preservation system is more than 8 ℃ when the temperature is greatly, and the temperature fluctuation is difficult to be controlled by the temperature fluctuation of a user, and has a high temperature fluctuation is stable and has a high temperature can not reach the temperature regulation and temperature control mechanism is stable, and has the temperature stability is stable when the temperature is stable, and is stable when the temperature is stable. The phase change material is widely applied in the fields of building energy conservation and the like due to the characteristic that the phase change material can absorb or release a large amount of latent heat at a specific temperature, but the phase change material is combined with an electrical intelligent regulation technology, so that a plurality of technical problems still exist when the phase change material is applied to heat preservation and transportation of a large-caliber heating pipeline, and an effective fusion scheme is not formed in the prior art, wherein the existing research focuses on a low-temperature application scen