WO2013152681A1

WO2013152681A1 - Heat capacity heat exchange device

Info

Publication number: WO2013152681A1
Application number: PCT/CN2013/073542
Authority: WO
Inventors: 刘阳
Original assignee: 北京兆阳能源技术有限公司
Priority date: 2012-04-09
Filing date: 2013-04-01
Publication date: 2013-10-17
Also published as: CN103363690A; CN103363690B

Abstract

A heat capacity heat exchange device comprises a first shell (1) arranged inside, a second shell (2) arranged outside, a heat exchange media (4) and a heat capacity media (3). A space between the first shell (1) and the second shell (2) is fully or partially filled with the heat capacity media (3); external energy transfers to the heat exchange media (4) through the heat capacity media (3), and accordingly heat collecting of the heat exchange device is completed. The heat capacity heat exchange device has wide usable ranges, can be used for the solar heat utilization field of a groove-type optothermal heat collector, a Fresnel array optothermal heat collector, a disk-type optothermal heat collector, or a tower-type optothermal heat collector; and is specifically applied to a direct steam generation system, a heat transfer oil system and a melt salt system; can also be applied to the boiler heating field or the input and output application field of heat of a heat storage system, and well solves the technical problems which are difficult to solve by means of various normal techniques in the corresponding application field.

Description

Heat capacity heat exchange device

The invention relates to a heat capacity heat exchange device applied in the field of solar heat utilization. Background technique

With the development of renewable energy such as solar energy booming around the world, solar thermal power generation (CSP) is gradually becoming known. In the CSP system, the endothermic heat transfer portion has a very important position. The heat exchange medium in the solar energy collecting system mainly uses heat-conducting oil as the heat transfer medium. After the heat-conducting oil-steam heat exchanger, steam is generated to drive the conventional steam turbine to drive the generator set to generate electricity. Since the current heat transfer oil operating temperature must be controlled within 400 ° C, exceeding this temperature will cause problems such as heat transfer oil cracking, viscosity increase, and heat transfer efficiency.

At present, alternatives to the heat exchange medium of the international solar collector technology are molten salt materials, such as the molten salt medium collector of the ENE A study in Italy. The molten salt medium has a high crystallization point, mostly around 230 to 260 ° C. At present, there are still many difficulties. For example, the local temperature may be too high during the operation, which causes the molten salt to decompose; the molten salt inside the collector needs to be heated at night. The cycle avoids condensation, the control is extremely complicated, and the system needs to consume a large amount of electric energy, which increases the self-consumption of the power plant; therefore, the current molten salt is mainly used for heat storage.

Direct steam generation (DSG) technology, which uses water directly as a heat exchange medium, has been tested for many years. The technology is similar to the operation principle of the steam boiler heated pipeline. The water is used as the working medium, and the low temperature water is injected from one end of the heat absorption pipeline; the water absorbs heat gradually during the process of traveling along the axial direction of the pipeline, and becomes saturated steam after reaching the boiling point. , and then continue to absorb heat into superheated steam. Among them, the phase transition process is the most complicated. In this process, the two phases experience fine bubble flow, gas plug flow, gas bomb flow, wave stratification and annular flow. In the wavy layered process and region, the liquid water and the saturated gas are in contact with the pipe wall alternately, causing the pipe wall temperature to rise and fall rapidly and periodically, which has a great influence on the material structure strength of the entire collector, or even damage; In the annular flow process and area, the upper part of the pipe is in direct contact with the steam, and the bottom is in direct contact with the liquid water, so that the temperature difference between the upper and lower parts of the pipe in the process and the area is large, severe warpage occurs, and the service life of the collector is shortened. Or in the process of generating steam inside the collector, when the cloud moves, the state of the water is unstable when the water is boiled in the heat pipe, and the two-phase flow transmission and the vaporization pressure are uneven in the heat collecting tube. Problems such as water shovel, vibration, fatigue damage of pipeline materials; In addition, when saturated steam enters the superheated steam section, when the pipeline is heated unevenly, the wall wall temperature difference is large, severe bending will occur, and other losses (such as vacuum) will occur. Seal damage;); In addition, the prior art still does not solve the series of problems caused by the DSG pipeline in the local heatless (such as the local shadow caused by the cloud occlusion of the mirror field), such as water input and steam output flow control, The effect of parameter changes. Therefore, the technology is still in the experimental stage, but as long as these problems can be solved, DSG technology becomes the lowest cost and most efficient key technology for environmentally safe solar thermal power generation. SUMMARY OF THE INVENTION A heat capacity heat exchange device in the field of solar energy photothermal application.

The embodiment of the invention provides a heat capacity heat exchange device, which is composed of a first shell and a second shell arranged inside and outside, a heat exchange medium and a heat capacity medium; and a space between the first shell and the second shell Or partially filled with a heat capacity medium; external energy can be transferred to the heat exchange medium through the heat capacity medium to complete heat collection.

Further, the first shell and the second shell are respectively metal tubes.

Further, the phase change temperature point of the heat capacity medium is within a normal use temperature range of the heat exchange medium.

Preferably, the heat capacity medium has a large latent heat of phase change.

Further, the heat exchange medium is a heat transfer oil (heat transfer), molten salt, water, water-steam, compressed gas or supercritical fluid, and is discharged from the outside of the heat capacity heat exchange device after absorption of sensible heat or latent heat is completed.

Further, the heat capacity medium is one of an organic salt, an inorganic salt, a metal, an alloy, or a combination thereof, and is filled in an inner space between the first shell and the second shell.

Further, the heat capacity medium is a one-component or mixed salt of potassium nitrate, sodium nitrate or other nitrate; a single-component or mixed salt of potassium carbonate, sodium carbonate, lithium carbonate or other carbonate; or may be Zinc, aluminum, magnesium, tin metal or alloys thereof.

Further, different regions inside the heat capacity heat exchange device are filled with different heat capacity media, and a high temperature phase change point is filled with a heat capacity medium at a high temperature stage, and a low temperature phase change point is implemented at a low temperature portion. The filling of the heat capacity medium.

Further, the heat medium is filled with a solid material, the thermal conductivity of the heat medium is adjusted, and a temperature difference of the heat medium from the outside to the inside is obtained during heat transfer. Further, the filled solid material is a metal foam, a wire, a metal sheet, a metal particle, a ceramic fiber, a ceramic particle, a graphite fiber, a graphite powder or other high thermal conductivity material to reduce the temperature difference.

Further, the solid material is foam glass, ceramic foam, glass or ceramic particles, glass or ceramic fibers, stone particles or other low thermal conductivity materials to raise the temperature difference.

Further, the heat capacity heat exchange device is arranged at a high temperature end of different heat storage medium filling sections, and a temperature monitor is arranged to ensure temperature operation of the heat capacity medium.

Further, the second metal pipe is provided with a spiral thread, a spiral flow guiding device, a spiral rotating fin or a spiral pipe ring, so that the heat exchange medium is vortex flow inside the second metal pipe, and the wall surface which is in contact with the heat exchange medium is good. The average temperature performance.

The heat capacity heat exchange device provided by the embodiment of the invention can be applied to the field of trough type photothermal, Fresnel array photothermal, dish type photothermal or tower type photothermal collector solar energy utilization; and heat storage system heat input, The output application collar i or; can also be applied to the boiler heat port i or.

The heat capacity heat exchange device of the embodiment of the invention arranges at least one heat capacity medium along the axial direction of the heat exchange device, has a specific phase transition temperature, and has different effects for different heat exchange media. For example, when the heat exchange medium is a heat transfer oil (thermal heat), the heat medium can suppress the rapid rise of temperature and prevent the heat exchange medium from being overheated and deteriorated; for example, the external heat medium is zinc aluminum alloy, and the phase change temperature point is at the heat conduction. The normal temperature range of the oil has a phase transition temperature slightly lower than the cracking temperature of the heat transfer oil, so that the heat medium directly receives the external heat, and then transfers heat to the heat transfer medium of the heat exchange medium, and most of the heat medium In the case of maintaining a solid state; when the heating power outside the heat exchange device suddenly increases locally or the internal heat transfer suddenly decreases, excessive heat is first absorbed by the external heat medium, and the temperature remains in the phase during solid melting. Change the temperature point to ensure that the heat transfer oil is below the cracking temperature, avoiding the high temperature cracking of the heat transfer medium of the heat transfer medium flowing inside, and prolonging the service life. When the heat exchange medium is a molten salt system, the phase change temperature point of the heat medium is selected within the normal use temperature range of the molten salt, and the heat medium having a melting point higher than the melting point of the molten salt heat exchange medium is selected to ensure that the outside is free from sunlight. During gathering (such as at night), within a certain period of time (such as overnight); during the process of gradual solidification of the heat capacity medium, the temperature of the heat exchange device is maintained at the phase transition temperature point of the heat capacity medium, higher than the molten salt heat exchange medium. The melting point of the molten salt heat exchange medium is maintained in a molten state, so that the re-flowing heat exchange can be conveniently started when the sunlight reconverges, thereby eliminating the externally disposed electric heating system and the self-consumption of the molten salt circulation pump. When the heat exchange medium is water-steam, select the phase change temperature of the heat medium The point is slightly higher than the phase transition temperature of the water-steam under the working pressure of the heat exchange system, which can avoid the pipeline safety problem caused by the severe state change and temperature instability during the change of the two phases of steam and water; thus, the heat capacity heat exchange device It can effectively solve the safety problems of most solar collectors. DRAWINGS

Specific embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawings,

1 is a cross-sectional view showing the structure of a heat capacity heat exchange device according to a first embodiment of the present invention;

Figure 2 is a schematic cross-sectional view showing the structure of the heat capacity heat exchange device of Figure 1;

3 is a schematic view showing the internal spiral thread structure of the second metal pipe of the heat capacity heat exchange device; and FIG. 4 is a schematic view showing the direct steam generating system of the heat capacity heat exchange device according to the second embodiment of the present invention. detailed description

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the structure of a heat capacity heat exchange device according to a first embodiment of the present invention. The heat capacity heat exchange device includes a first shell 1 and a second shell 2 disposed inside and outside, a heat exchange medium 4, and a heat medium 3. All or part of the space between the first casing 1 and the second casing 2 is filled with the heat medium 3. External energy is transferred to the heat exchange medium 4 through the heat medium 3 to complete heat collection by the heat exchange unit. Among them, the first case 1 and the second case 2 are preferably metal tubes. The invention will now be described primarily in connection with tubular forms, and those skilled in the art will appreciate that the invention is equally applicable to other forms of housing. Fig. 2 is a schematic cross-sectional view showing the structure of the heat capacity heat exchanger of Fig. 1.

The heat capacity heat exchange device can be used in systems of different heat exchange media. The heat exchange medium 4 may be a heat transfer oil (heat transfer), a molten salt, water, water-steam, a compressed gas, a supercritical fluid, etc., and after absorbing sensible heat or latent heat, it flows out of the heat-exchange heat exchange device.

The heat capacity medium 3 may be an organic salt, an inorganic salt, a metal, or an alloy, and is filled in an inner space between the first shell 1 and the second shell 2. Preferably, the heat capacity medium 3 has a large latent heat of phase change, has a specific phase change temperature point, and the heat medium medium 3 phase change temperature point is within the normal use temperature range of the heat exchange medium 4.

Specifically, the heat capacity medium 3 may be a one-component or mixed salt of potassium nitrate, sodium nitrate or other nitrates. Among them, the single component phase transition point of potassium nitrate is 334 °C, the phase transition enthalpy is 95kJ/kg, and the decomposition begins at a temperature above 400 °C; the single component phase transition temperature point of sodium nitrate is 308 °C, phase transformation The crucible is 175kJ / kg; it starts to decompose above 380 °C; the current common nitrate mixed salt system is 40wt. /. Potassium nitrate + 60wt. /. S-sodium sodium, phase transition temperature point 223 °C, phase transition enthalpy is 90kJ/kg; safe operation at temperatures below 550 °C; The nitrate and mixed salt systems have good compatibility with stainless steel or carbon steel materials, and the phase transition temperature is close to the operating temperature of the system, and the material corrosion problem is very weak.

The heat capacity medium 3 may also be a one-component or mixed salt of potassium carbonate, sodium carbonate, lithium carbonate or other carbonates. The single component phase transition temperature of potassium carbonate is 899 ° C, the phase transition enthalpy is 202.94 kJ / kg; the single component phase transition temperature point of sodium carbonate is 856 ° C, and the phase transition enthalpy is 280.2 kJ / kg; The one-component phase transition temperature point is 732 ° C, the phase transition enthalpy is 622 kJ / kg; lithium carbonate 27 wt ° /. + Potassium carbonate 33wt ° /. +40 sodium carbonate wt%, phase transition temperature 395 ° C, enthalpy difference is 159.6kJ / kg, the carbonate has a small amount of corrosion on steel in thousands of cycles at 800 ° C, with stainless steel and Good material compatibility with carbon steel.

The heat medium 3 can also be zinc, aluminum, magnesium, tin metal and alloys. The single component phase transition temperature of zinc is 419.5 ° C, the phase transition enthalpy is 108 kJ / kg; the single component phase transition temperature of aluminum is 660.32 ° C, and the phase transition enthalpy is 396.66 kJ / kg; The phase transition temperature is 650 ° C, and the phase transition 焓 is 353.3 km/kg. The alloy has a high phase transition temperature point and a high phase change value. It has good metal material compatibility near the phase transition temperature point. The phase transition temperature of the metallic tin is 231.93 ° C, and the phase transition enthalpy is 64.24 kJ / kg.

The heat capacity heat exchange device is arranged with at least one heat medium 3 along the heat exchange device (e.g., the axial direction of the pipe). The heat medium 3 receives external heat through the outer tube wall and then transfers heat to the internal heat exchange medium 4 . The heat exchange medium 4 remains in a solid state in most cases. When the heating power outside the heat exchange device suddenly increases or the internal heat output power suddenly decreases, the excess heat is first absorbed through the heat medium 3, and the solid heat medium 3 is melted. The medium 3 is stable in temperature. Therefore, the temperature of the inner tube wall is relatively stable, rapid temperature rise does not occur, and time adjustment and control can be performed to avoid high temperature cracking of the internal heat exchange medium 4 and prolong the service life.

The heat capacity medium 3 has a specific phase transition temperature and has a different effect for the different heat exchange medium 4. For example, when the heat exchange medium 4 is a heat transfer oil (thermal heat), the phase change temperature point of the heat medium 3 is within the normal use temperature range of the heat transfer oil, which can suppress the rapid rise of the temperature and prevent the heat exchange medium 4 from being overheated and deteriorated; for example, The heat capacity medium 3 is a zinc-aluminum alloy having a phase transition point of 381 ° C and a phase transition of 焓138 kJ/kg; or a zinc-aluminum-magnesium alloy having a phase transition point of 400 ° C and a phase transition of 焓146 kJ/kg. The heat medium 3 receives external heat through the outer tube wall and then transfers heat to the internal heat exchange medium 4 (heat transfer oil). The heat exchange medium 4 remains in a solid state in most cases. When the heating power outside the heat exchange device suddenly increases or the internal heat output power suddenly decreases, the excess heat is first absorbed through the heat medium 3, and the solid heat medium 3 is melted. The medium 3 is stable at 381 ° C or 400 ° C, so The internal wall temperature is relatively stable, there is no rapid temperature rise, and time can be controlled and controlled to avoid high temperature cracking of the heat transfer medium 4 of the internal flow, and prolong the service life.

When the heat exchange medium 4 is a molten salt system, the temperature point of the heat medium 3 is in the normal use temperature range of the molten salt, which can suppress the rapid temperature drop and prevent the molten salt from freezing. For example, a heat medium 3 that is higher than the melting point of the heat exchange medium 4 is disposed to ensure that the temperature of the heat exchange device is maintained near the phase transition temperature point of the heat medium for a certain period of time, which is higher than the melting point of the molten salt. The heat exchange medium 4 can be in a molten state in order to flow heat again.

When the heat exchange medium 4 is water-steam, the phase transition temperature point of the heat capacity medium 3 is slightly higher than the phase transition temperature point of the water-water vapor, and the temperature of the heat exchange medium 4 can be suppressed from fluctuating rapidly, and the heat capacity medium is utilized. 3 The large heat capacity near the phase transition point overcomes the problem of the safety and stability of the pipeline caused by the unstable temperature caused by the unstable state of the heat exchange medium 4, the water enthalpy vibration, etc.; Effectively avoid safety problems in solar collectors.

Figure 3 is a schematic view showing the internal helical screw structure of the second casing of the heat capacity heat exchange device. As shown in Fig. 3, a spiral thread 5 is provided inside the wall of the second casing 1 (e.g., a metal pipe), and the structure can be preferably applied to a system in which the heat exchange medium 4 is water, that is, a system directly generating steam. Medium (DSG). During the operation of the DSG system, the two-phase flow undergoes a fine bubble flow pattern, a gas plug flow pattern, an air elastic flow pattern, a wavy layered shape, and an annular flow pattern. In the wavy layered process and region, the liquid water and saturated gas are in contact with the pipe wall alternately, causing the pipe wall temperature to rise periodically, causing a large impact on the structural strength of the entire collector, or even damage; In the type process and area, the upper part of the pipe is in direct contact with the steam, and the bottom is in direct contact with the liquid water, so that the temperature difference between the process and the upper and lower parts of the pipe is large, severe warpage occurs, and the service life of the collector pipe is shortened. The spiral thread 5 is used to vortex the heat exchange medium inside the second shell 2 to obtain a uniform temperature performance with the heat exchange medium 4 in contact with each other, thereby overcoming the above problems.

In addition, a spiral flow guiding device or a spiral rotating fin or a spiral tube ring may be disposed inside the second shell 2 to vortex the heat exchange medium inside the second shell 2 to obtain mutual contact with the heat exchange medium. The wall has good uniform temperature performance and overcomes problems such as severe warpage.

Fig. 4 is a schematic view showing a direct steam generating system of a heat capacity heat exchange device according to a second embodiment of the present invention. The heat capacity heat exchange device can be applied to a direct steam generating system of a solar heat collecting system. Although the direct steam generation system technology has been tested for many years, there are still many technical problems, such as 1. The temperature difference around the pipe wall is large, and the warpage is severe: During the operation of the system, the two-phase fine bubble flow pattern and air plug will be experienced. Flow pattern, gas bomb Flow pattern, wavy layered type and annular flow pattern; in the wavy layered process and region, liquid water, saturated gas and tube wall are alternately contacted, causing the wall temperature to rise periodically, the structure of the entire collector The strength has a great influence, even damage; in the annular flow process and the area, the upper part of the pipe is in direct contact with the steam, and the bottom is in direct contact with the liquid water, so that the temperature difference between the process and the upper and lower parts of the pipe is large, and severe warpage occurs. , shorten the life of the collector pipe; 2, uneven heating, and caused by heat instability: in the process of generating steam inside the collector, in the case of cloud movement, such as clouds in the overheating section, causing overheating When the heating power is reduced, the temperature outside the collector of the area is rapidly cooled, causing the newly superheated steam to condense. Under the high-speed operation of the steam followed by the rear part, the water droplet impacts the wall or the component causes the water hammer to collide; When the heat exchange medium is running, the downstream of a certain point is a slowly flowing water, while the upstream part is caused by a sudden increase of the sun's rays, causing a bump. Rapid expansion, pushing the downstream liquid water to the front at high speed, causing the water ripple of the pipe or component; even without the influence of the cloud, the intensity of the sunlight in the day changes at any time, resulting in the axial phase of the collector phase Movement, causing a change in the axial temperature distribution of the tube wall, causing the state of the water to be unstable when boiling occurs in the heat-receiving tube, and there are a series of problems caused by the unstable distribution of the two-phase flow and the vaporization pressure in the heat collecting tube, such as leeches , vibration, fatigue damage of pipeline materials, etc.; 3, excessive temperature of the superheated section of the pipe wall, resulting in a decrease in pipe strength: in the saturated steam becomes superheated steam section, due to poor thermal conductivity of steam, weak heat absorption capacity, easy to occur Passing through the temperature damage; and when the pipeline is unevenly heated, the wall wall temperature difference is large, severe bending will occur, causing other losses (such as vacuum seal damage); 4. The output superheated steam parameters are unstable, bringing flow control and rushing The problem of hitting the steam turbine: The prior art still does not solve the problem that the DSG pipeline is not heated locally (for example, the mirror field is due to clouds) Shadows caused by partial blocking) caused by a series of problems, such as flow control is difficult, the output parameter superheated steam turbine instability problem like an impact. The problems corresponding to the above DSG technology can be alleviated or completely solved in this embodiment.

As shown in FIG. 4, the heat capacity heat exchange device includes a first case 1 and a second case 2 which are disposed inside and outside. The first and second shells may preferably be a first metal tube and a second metal tube, respectively. The second shell is filled with a heat exchange medium 4. All or part of the space between the first shell and the second shell is filled with different heat capacity media. In one example, the filling of the high temperature phase change point heat capacity medium 3-2 is performed at a high temperature stage, and the filling of the low temperature phase change point heat capacity medium 3-1 is performed at a low temperature stage. The external energy is transferred to the heat exchange medium 4 through the heat medium 3-1 or the heat medium 3-2 to complete the heat collection of the heat exchange device. For example, high temperature sections are filled with a magnesium-aluminum alloy or a magnesium-aluminum-zinc alloy with a phase transition temperature of 381 °C or 400 °C; for example, low temperature section filling A potassium nitrate or sodium nitrate one-component salt having a phase transition temperature of 334 °C or 308 °C.

The water-steam as the heat exchange medium 4 is mainly composed of three processes, a liquid phase process, a phase change process and a superheat process. The heat exchange is stable during the liquid phase process, and in the region of the process, the heat medium may not be filled.

In the region of the phase change process, the first shell 1 and the second shell are filled with a heat medium 3-1. In the process, the above-mentioned temperature difference between the wall of the pipe wall is large, severe warpage and uneven heating, and the water enthalpy problem caused by heat instability, corresponding to the heat exchanger medium 4 of different pressures, the heat capacity medium 3-1 material to be filled Different; for example, internally running l lMPa of water (corresponding phase change saturation temperature is 318 °C), the external heat capacity medium 3-1 can be potassium nitrate monomer (corresponding phase transition point is 334 °C, phase change)焓 is 95kJ/kg , ); for example, if 9MPa of water is run internally (corresponding phase change saturation temperature is 298 °C), the external heat capacity medium 3-1 can be sodium nitrate monomer (corresponding phase transition point is 308) °C, phase change 焓 is 175 kJ/kg).

The phase change temperature point of the filled heat capacity medium 3-1 is slightly higher than the saturation temperature point of the heat exchange medium 4. Under normal circumstances, the heat medium 3-1 is in a state in which a part of the molten portion is solidified (the heat capacity medium 3-1 between the second shell 2 and the first shell 1 has a certain thermal resistance, so that the temperature of the outer wall of the first shell 1 is Slightly higher than the heat exchanger medium 4 body temperature). When the local heat is uneven, such as in the process of cloud drift or the sudden increase of sunlight, the semi-molten semi-solidified heat medium 3-1 starts to function; if the local heat is enhanced, the heat medium 3-1 first absorbs heat. , so that the melt increases, but the temperature does not change, reducing the occurrence of water ripple caused by internal bumps and bumps; if the local cloud is blocked, the heat is reduced, and the heat medium 3-1 first releases heat, so that the heat is melted. The body is reduced, but the temperature does not change, and the internal heat is not locally heated. The condensation occurs in the corresponding region of the heat exchange medium 4, causing the water vapor to push the condensate forward and running at high speed. Phenomenon, the overall overcomes the problem of water stagnation caused by uneven heating and unstable heat.

In the region of the superheating process, the first shell 1 and the second shell 2 are filled with a heat medium 3-2; the heat medium 3-2 has a higher phase transition point than the heat medium 3-1, such as that required by the DSG. l lMPa, superheated steam parameters of 435 °C. The heat medium 3-2 of this section can be selected from aluminum, magnesium and zinc alloy materials. The melting point of the alloy material is 400 °C, and the phase transition enthalpy is 146 kJ/kg; when it is required to obtain 9 MPa, 390 °C The superheated steam parameter, the heat medium 3-2 of this section can be selected as aluminum and zinc alloy material, the melting point of the alloy material is 381 °C, and the phase transition enthalpy is 1 38 kJ/kJ; under normal conditions, The heat medium 3-2 downstream of the superheated steam is in a molten state higher than the melting point, and the upstream heat medium 3-2 is a solid below the melting point. State, a position in the middle is the junction of the molten state and the solid state.

When the sunlight suddenly increases, the external heat medium 3-2 absorbs heat, moving the boundary of the molten and solid state upstream, and well delays the rise of the temperature of the superheated steam outlet; when the sunlight is suddenly blocked by clouds, the outside The heat capacity medium 3-2 releases heat, moving the boundary of the molten state and the solid state upstream, thereby delaying the temperature drop of the superheated steam outlet well, and prolonging the control system for adjusting the flow rate based on the end superheated steam output temperature feedback. Reaction time (when the temperature of the superheated steam is detected to decrease, the input flow rate of the heat exchange medium of the heat capacity heat exchange device is reduced, and when the temperature of the superheated steam is detected to rise, the input flow rate of the heat exchange medium of the heat phase change heat device is increased, but usually The solar mirror field is long, it takes a certain time for the heat exchange medium 4 to flow through the full length, so that the flow feedback often has a hysteresis phenomenon, which maintains the stability of the system well; overcomes the overheated steam temperature caused by the sudden change of the sunlight in the traditional structure. Change problem, complete the peak elimination of output power, reduce the direct impact on the turbine hit.

The heat capacity heat exchange device can respectively arrange the temperature monitor 6-1 and the temperature monitor 6-2 at the high temperature end of the filling section of the heat capacity medium 3-1 and the heat medium medium 3-2, and implement temperature monitoring to ensure normal operation. In the case where decomposition does not occur, the operation of the heat capacity medium 3-1 and the heat medium medium 3-2 is ensured.

One or more of a spiral thread 5, a spiral flow guiding device, a spiral rotating fin and a spiral tube ring may be arranged inside the second shell 2, so that the heat exchange medium 4 realizes a vortex flow inside the second shell 2, The heat medium 4 is separated into the shell wall during the spiral advancement to enhance the heat exchange capacity and the heat absorption uniformity, thereby alleviating or overcoming the problem of severe warpage due to the large temperature difference around the circumference of the DSG tube wall, and obtaining the heat exchange medium 4 Good temperature uniformity in contact with each other on the wall.

Further, a solid material may be filled inside the heat medium 3-1 to adjust the thermal conductivity of the heat medium 3 to obtain a temperature difference from the outside to the inside of the heat medium 3-1. The filled solid material may be a high thermal conductivity material such as metal foam, metal wire, metal flake, metal particle, ceramic fiber, ceramic particle, graphite fiber, graphite powder, etc., to increase low thermal conductivity heat capacity medium 3-1 (such as inorganic salt) The thermal conductivity of the material) reduces the temperature difference; it can also be a low thermal conductivity material such as foam glass, foam ceramics, glass ceramic particles, glass ceramic fibers, stone particles, etc., to reduce the high thermal conductivity heat capacity medium 3-1 The thermal conductivity of a metal (alloy, alloy-like material) increases the temperature difference.

In the implementation process, the mass ratio of the filled solid material is specifically determined according to the phase transition temperature and thermal conductivity of the selected heat capacity medium material, the internal steam corresponding saturation temperature, and the thickness of the heat capacity medium; to obtain heat suitable for stable operation of the system. The temperature difference of the medium from the outside to the inside, forming a partially melted, partially solidified The heat capacity medium state; thus the heat capacity medium material can be utilized.

The heat capacity heat exchange device can be applied to a heat transfer oil system of a solar heat collecting system. The external heat medium 3 may be an aluminum magnesium zinc alloy having a phase transition point slightly lower than the heat transfer oil cracking temperature, for example, the melting point of the zinc aluminum alloy is 400 ° C, the heat transfer oil cracking temperature is 405 ° C, or, for example, metal tin The melting point is 231.9 ° C, corresponding to the heat transfer oil cracking temperature of 240 ° C. In this way, the heat medium 3 directly receives the external heat, and then transfers heat to the heat exchange medium 4 of the internal heat exchange medium, and the heat medium 3 remains in a solid state for most of the time; when the heat source outside the heat exchanger suddenly increases locally When large, excessive heat is first absorbed by the external heat medium, and the solid heat medium 3 is melted below the heat transfer oil cracking temperature to avoid high temperature cracking of the heat transfer medium 4 flowing inside and prolong the service life.

The heat capacity heat exchange device is applied to a molten salt system of a solar heat collecting system. The melting point of the heat capacity medium in the heat capacity heat exchange device is slightly higher than the phase change point of the heat exchange medium. For example, the common heat transfer medium 4 of the molten salt system is a nitrate mixed salt, the phase transition temperature is 220 ° C, and the working temperature is between 250 ° C and 550 ° C (but the heat collecting field is arranged with an electric heating system, In the case of ensuring no external sunlight condensation, the collector is heated to a certain power to ensure that the internal nitrate mixed salt system is in a liquid state, and the heat capacity medium 3 is selected as a phase change material having a phase transition temperature of 270 °C. In the case of normal sunlight, the heat medium 3 is in a high temperature molten state; when there is no sunlight, the heat medium 3 first releases its own sensible heat, and then releases the heat for a long time at a phase transition temperature of 270 °C. Compensating for heat loss such as heat radiation in the heat capacity heat exchange device without sunlight, ensuring that the internal heat exchange medium 3 is in a molten state for a long time, eliminating the electric heating of the heat exchange medium or the circulation of the internal molten salt before the sun is concentrated again. Control, reduce or even eliminate the installation cost and control cost of the electric heating system, and reduce the self-consumption electricity consumption required for the internal molten heat exchange medium 4 of the circulation pump cycle.

It should be specially stated that the heat capacity heat exchange device has different functions for different heat exchange media: 1. It can be applied to the boiler heating system, and the heat capacity medium added to the furnace side of the water wall can well avoid the water wall. Local overheating; 2. Heat input that can be applied to the heat storage system. For example, the heat capacity heat exchange device is disposed in the heat storage tank, but the decomposition temperature of the heat storage medium inside the heat storage tank is a specific temperature, and the heat capacity can be controlled. The material of the medium protects the heat storage medium from overheating to achieve safe input. Corresponding to the heat output of the heat storage tank, the temperature of the heat medium can be prevented from being too high, and the output temperature can be well controlled. 3. The carbonate element or mixed salt has Higher phase transition temperatures, and phase transitions, can be applied to higher temperature heat transfer structural systems. The heat capacity heat exchange device can be applied to solar heat utilization fields such as trough type photothermal, Fresnel array photothermal, dish type photothermal or tower type photothermal collector; and heat applied to boiler heating and heat storage system Input and output application areas. The structural shape of the heat capacity heat exchange device is preferably a metal tubular shape, but is not limited to a tubular shape.

It will be apparent that the invention described herein can be varied in many variations without departing from the true spirit and scope of the invention. Therefore, all changes that can be foreseen by those skilled in the art are intended to be included within the scope of the claims. The scope of the invention as defined by the appended claims is defined by the appended claims.

Claims

Claim

A heat capacity heat exchange device comprising: a first shell and a second shell disposed inside and outside, a heat exchange medium and a heat capacity medium; all or part of a space between the first shell and the second shell is filled Heat capacity medium; external energy can be transferred to the heat exchange medium through the heat medium to complete heat collection.

2. A heat capacity heat exchange device according to claim 1, wherein the phase change temperature point of the heat capacity medium is within a normal use temperature range of the heat exchange medium.

3. The heat capacity heat exchange device according to claim 1, wherein the first shell and the second shell are respectively metal tubes.

The heat capacity heat exchange device according to any one of claims 1 to 3, wherein the heat capacity medium is one or a combination of an organic salt, an inorganic salt, a metal and an alloy, and is filled in the first An internal space between a shell and a second shell.

5. A heat capacity heat exchange device according to claim 4, wherein the heat capacity medium is a one-component or mixed salt of potassium, sodium nitrate or other nitrates.

6. A heat capacity heat exchange device according to claim 4, wherein the heat capacity medium is a single component or a mixed salt of potassium S, potassium carbonate, lithium carbonate or other carbonate.

7. A heat capacity heat exchange device according to claim 4, wherein the heat capacity medium is zinc, aluminum, magnesium, tin metal or an alloy thereof.

8. The heat capacity heat exchange device according to claim 1, wherein different regions inside the heat capacity heat exchange device are filled with different heat capacity media, and high temperature phase transition is performed at a high temperature portion. The filling of the heat capacity medium at the point, the filling of the heat capacity medium at the low temperature phase change point in the low temperature section.

9. The heat capacity heat exchange device according to claim 8, wherein the heat capacity heat exchange device is disposed at a high temperature end of a different heat medium filling section, and a temperature monitor is disposed to perform temperature monitoring.

10. A heat capacity heat exchange device according to claim 1, wherein the heat medium is filled with a solid material.

11. A heat capacity heat exchange device according to claim 10, wherein said solid material is Foam metal, wire, sheet metal, metal particles, ceramic fibers, ceramic particles, graphite fibers, graphite powder or other high thermal conductivity materials.

12. A heat capacity heat exchange device according to claim 10, wherein the solid material is foam glass, ceramic foam, glass or ceramic particles, glass or ceramic fibers, stone particles or other low thermal conductivity materials. .

13. A heat capacity heat exchange device according to claim 1, wherein the heat exchange medium is a heat transfer oil, a molten salt, water, water-steam, a compressed gas or a supercritical fluid.

The heat capacity heat exchange device according to claim 1 or 3, wherein the second casing is provided with a spiral thread, a spiral flow guiding device, a spiral rotating fin or a spiral tube ring.

15. The heat capacity heat exchange device according to claim 1, wherein the heat capacity heat exchange device can be applied to trough type photothermal, Fresnel array photothermal, dish type photothermal or tower type Photothermal collector solar thermal utilization collar i or.

16. A heat capacity heat exchange device according to claim 1, wherein said heat capacity heat exchange device is applied to a direct steam generating system of a solar heat collecting system.

17. The heat capacity heat exchange device according to claim 1, wherein the heat capacity heat exchange device is applied to a heat transfer oil system of a solar heat collecting system.

18. The heat capacity heat exchange device according to claim 1, wherein the heat capacity heat exchange device is applied to a salt water system of a solar heat collecting system.

19. A heat capacity heat exchange device according to claim 1, wherein the heat capacity heat exchange device is applied to a boiler heating and heat input and output application to a heat storage system.