CN212327935U - Flue gas temperature homogenizing device - Google Patents
Flue gas temperature homogenizing device Download PDFInfo
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- CN212327935U CN212327935U CN201922095969.2U CN201922095969U CN212327935U CN 212327935 U CN212327935 U CN 212327935U CN 201922095969 U CN201922095969 U CN 201922095969U CN 212327935 U CN212327935 U CN 212327935U
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 94
- 239000003546 flue gas Substances 0.000 title claims abstract description 94
- 239000012071 phase Substances 0.000 claims abstract description 167
- 230000008859 change Effects 0.000 claims abstract description 143
- 238000012546 transfer Methods 0.000 claims abstract description 34
- 238000000265 homogenisation Methods 0.000 claims abstract description 32
- 230000001105 regulatory effect Effects 0.000 claims abstract description 15
- 238000004891 communication Methods 0.000 claims abstract description 11
- 239000012808 vapor phase Substances 0.000 claims abstract description 7
- 239000007789 gas Substances 0.000 claims description 31
- 230000007704 transition Effects 0.000 claims description 24
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical group [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 11
- 229910052753 mercury Inorganic materials 0.000 claims description 11
- 239000012530 fluid Substances 0.000 claims description 9
- 239000000295 fuel oil Substances 0.000 claims description 3
- -1 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000007791 liquid phase Substances 0.000 description 11
- 238000000034 method Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000002309 gasification Methods 0.000 description 4
- 238000009835 boiling Methods 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012782 phase change material Substances 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
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Abstract
The utility model provides a flue gas temperature homogenization device, a serial communication port, the device includes: a first network of heat transfer pipes in a first cross section of the flue, the first network of heat transfer pipes filled with a phase change medium; a pressure controller disposed outside the flue; and a pressure regulating tube fluidly connecting the first heat transfer conduit network and the pressure controller, wherein the pressure controller is configured to regulate a pressure of the phase change medium in the first heat transfer conduit network via the pressure regulating tube such that a liquid-vapor phase temperature of the phase change medium is at a target homogenization temperature. The device of the utility model can quickly homogenize the temperature of the flue gas.
Description
Technical Field
The utility model relates to a flue gas denitration field, concretely relates to flue gas temperature homogenization device.
Background
The Selective Catalytic Reduction (SCR) method is a commonly used flue gas denitration method. Flue gas from, for example, a coal-fired boiler, is contacted with a catalyst in which nitrogen oxides are reduced to nitrogen and water.
The reaction rate of the chemical reaction has a close relationship with the temperature of the flue gas. As the temperature increases, the removal rate of nitrogen oxides increases and then decreases. Further, as the temperature increases, NH3The escape amount is continuously reduced, but SO2The conversion rate is increasing continuously. Therefore, the temperature cannot be too high for the SCR process, nor is it too highCan be too low. Therefore, it is necessary to maintain the stability of the temperature of the flue gas.
However, since the inlet flue cross section is large, even if the average temperature value is within the required range, uniformity of the temperature distribution in the flue cross section cannot be ensured, i.e., the partial region temperature may be too high, while the partial region temperature may be too low.
At present, for the uniformity of the flue gas temperature in the flue, a related adjusting means is always lacked, and the further improvement of the denitration performance is restricted.
SUMMERY OF THE UTILITY MODEL
The utility model provides a flue gas temperature homogenization device, a serial communication port, the device includes:
a first network of heat transfer pipes in a first cross section of the flue, the first network of heat transfer pipes filled with a phase change medium;
a pressure controller disposed outside the flue; and
a pressure regulator tube fluidly connecting the first network of thermally conductive tubing and the pressure controller,
wherein the pressure controller is configured to adjust the pressure of the phase change medium in the first network of heat transfer conduits via the pressure regulating tube such that the liquid-to-vapor phase temperature of the phase change medium is at a target homogenization temperature.
Optionally, the pressure controller adjusts the pressure by changing a total volume of the phase change medium.
Optionally, the pressure controller is a chamber having a piston.
Optionally, the pressure controller adjusts the pressure by varying the amount of phase change medium.
Optionally, the pressure controller comprises:
a negative pressure tank receiving a phase change medium from the network of thermally conductive pipes; and
and the positive pressure storage tank is used for inputting the phase change medium into the heat conduction pipeline network.
Optionally, the apparatus further comprises:
a second network of heat transfer conduits in a second cross section of the flue downstream of the first cross section, the second network of heat transfer conduits filled with the phase change medium, and the second network of heat transfer conduits in fluid communication with the first network of conduits.
Optionally, the liquid-gas phase transition temperature is between 300 ℃ and 450 ℃.
Optionally, the phase change medium has a liquid-gas phase transition temperature between 300 ℃ and 450 ℃ at normal pressure.
Optionally, the phase change medium is selected from mercury, aviation fuel or polytetrafluoroethylene.
Drawings
Fig. 1 and 2 are schematic views of an embodiment of the device of the present invention.
Fig. 3 and 4 are schematic views of an embodiment of the apparatus of the present invention for flue gas homogenization.
Fig. 5 is a schematic view of another embodiment of the present invention.
Fig. 6 is a schematic diagram of an embodiment of the pressure controller of the present invention.
Fig. 7 is a schematic diagram of a specific example of the apparatus of the present invention.
Fig. 8 is a phase diagram of mercury.
Detailed Description
In order to solve the inhomogeneous problem of different position temperatures of flue gas in the flue cross section, the utility model provides a flue gas temperature homogenization device, a serial communication port, the device includes:
a first network of heat transfer pipes in a first cross section of the flue, the first network of heat transfer pipes filled with a phase change medium;
a pressure controller disposed outside the flue; and
a pressure regulator tube fluidly connecting the first network of thermally conductive tubing and the pressure controller,
wherein the pressure controller is configured to adjust the pressure of the phase change medium in the first network of heat transfer conduits via the pressure regulating tube such that the liquid-to-vapor phase temperature of the phase change medium is at a target homogenization temperature.
The utility model discloses a heat conduction pipeline network is the network of constituteing by heat conduction pipeline, and it extends in the cross section of flue. In the present invention, the network means that any two points of the heat conducting pipe in the flue cross section are in fluid communication with each other through the heat conducting pipe. The network may take various forms as long as fluid connectivity is ensured.
The thermally conductive conduit allows heat exchange between the contents of the conduit and the contents of the conduit. The utility model discloses in, heat conduction pipeline sets up in the flue to will contact with the flue gas that flows through its outside. The heat conducting pipeline is filled with a phase change medium. In this way, the flue gas can exchange heat with the phase change medium. When the temperature of the flue gas is higher than that of the phase change medium, heat is conducted from the flue gas to the phase change medium through the heat conducting pipeline; when the temperature of the flue gas is lower than that of the phase change medium, heat is conducted from the phase change medium to the flue gas through the heat conducting pipeline.
The material and size of the heat conducting pipe can be designed properly, and the utility model discloses do not have special restriction to this. For example, a common heat exchanger design may be used.
Phase change media are media that can undergo a phase change. During the phase change, the medium absorbs or emits the phase change heat at a constant temperature. Generally, the phase change heat of a medium is much greater than the heat absorption and release due to the specific heat capacity of the medium. The phase change has various forms such as solid-liquid phase change, liquid-gas phase change, and the like. In the utility model, the phase-change heat of liquid-gas phase change is used to adjust the flue gas temperature.
The phase change medium is filled in the heat conducting pipe network and is regulated to the temperature of liquid-gas phase change. At this temperature, the temperature of the medium does not rise as it absorbs heat, but changes from a liquid state to a gaseous state until the medium has all changed to a gaseous state. Likewise, as the medium gives off heat, its temperature does not decrease, but changes from a gaseous state to a liquid state until the medium has all changed to a liquid state.
In this way, when the flue gas in the flue passes through the network of heat conducting pipes in the cross-section of the flue, heat exchange takes place with the phase change medium in the heat conducting pipes. At some point in the cross-section, the temperature of the flue gas may be higher than the phase change temperature of the phase change medium, heat will be transferred from the flue gas to the phase change medium, and the temperature of the flue gas decreases to a minimum not lower than the phase change temperature. At other locations in the cross-section, the temperature of the flue gas may be below the phase transition temperature of the phase transition medium, heat will be transferred from the phase transition medium to the flue gas, and the temperature of the flue gas will rise, up to no higher than the phase transition temperature. Since the phase change media in the network of thermally conductive pipes are in fluid communication with each other through the network, they are at the same pressure and thus have the same phase change temperature. The phase transition temperature is defined by the pressure of the phase change medium. When the pressure is stable, the phase transition temperature is stable. Therefore, when being stable with pressure control, the flue gas in the flue and the in-process of heat conduction pipeline network contact, the temperature all will be towards stable phase transition temperature change, high temperature flue gas cooling promptly, and low temperature flue gas intensifies simultaneously to reached the utility model discloses a with the flue gas temperature "homogenization" in the flue cross section the purpose. In other words, the temperature of the flue gas is adjusted towards the liquid-gas phase temperature.
The device of the utility model is a flue gas temperature homogenizing device, but not a flue gas heating or cooling device. Therefore, the liquid-vapor phase temperature of the phase change medium should be set at a desired temperature, referred to as a target homogenization temperature in the present invention, which should be within the temperature range of the flue gas with non-uniform temperature distribution. If the target homogenization temperature is set higher than the maximum temperature of the flue gas, the flue gas temperature is too low for the gas-liquid phase transition temperature of the phase change medium, resulting in the phase change medium will continue to release heat and liquefy, and eventually liquefy entirely. If the target homogenization temperature is set below the minimum temperature of the flue gas, the flue gas temperature is too high for the gas-liquid phase transition temperature of the phase change medium, resulting in the phase change medium being continuously, and eventually fully, vaporized. Both cases will cause the phase change medium to lose its ability to absorb or reject heat by phase change, thereby causing the device to lose its ability to homogenize.
When the phase change medium undergoes a liquid-gas phase change, its volume will change significantly. For example, when vaporized, its volume will increase significantly. If the network of thermally conductive pipes is closed, the internal pressure increases dramatically, possibly damaging the pipes and, more importantly, the phase transition temperature may vary. Ideally, the target homogenization temperature is set to achieve substantially the same heat absorption and release required for that temperature, with the volume and pressure of the phase change medium being substantially constant. But this ideal situation is almost impossible. To this end, the device of the present invention is provided with a pressure controller outside the flue and a pressure regulating pipe connecting the heat conducting pipe network with the pressure controller.
The pressure controller is used for controlling the pressure in the heat conduction pipeline and simultaneously providing a containing space for the phase change medium gasified due to heat absorption in the heat conduction pipeline or providing supplement for the volume shrinkage generated by the exothermic liquefaction of the phase change medium in the heat conduction pipeline. The pressure regulating pipe is used for connecting the pressure controller and the heat conducting pipeline network. The pressure regulating pipe can be a pipeline or a plurality of pipelines.
Optionally, the pressure controller adjusts the pressure by changing the total volume of the phase change medium. When the overall volume of the phase change medium in the heat conduction pipe does not change much as a whole due to the phase change, the pressure can be kept constant by adjusting the overall volume of the container containing the phase change medium. A possible simple example of such a pressure controller is a chamber with a piston subjected to a constant external pressure. The chamber is in fluid communication with the thermally conductive conduit. The phase change medium in the chamber is also at a phase change temperature and a liquid-gas mixture. When the internal pressure is slightly increased due to the heat absorption and gasification of the phase change medium, the piston moves towards the outer side of the chamber until the internal pressure and the external pressure are balanced, so that the pressure intensity of the phase change medium is kept unchanged, and the gas-liquid phase change temperature is kept unchanged; and vice versa. Such a straightforward scheme may be employed when the total volume of the phase change medium does not vary much due to non-uniform flue gas temperatures.
More generally, the pressure may be controlled by varying the total amount of phase change material. In one embodiment, a pressure controller comprises: a negative pressure tank receiving a phase change medium from the network of thermally conductive pipes; and a positive pressure storage tank for inputting the phase change medium into the heat conducting pipeline network. Two chambers of a check valve that opens at a fixed pressure may be provided in the pressure control pipe as the pressure controller. A one-way valve is configured to discharge the phase change medium to the negative pressure reservoir when the pressure inside the network of thermally conductive pipes is above a predetermined pressure. The other one-way valve is set to fill the phase change medium from the positive pressure storage tank to the interior of the heat conducting pipe when the pressure inside the heat conducting pipe network is lower than a predetermined pressure. The negative pressure and the positive pressure are relative to the pressure required to maintain the phase transition temperature.
The pressure controller can be designed in other modes as long as the pressure controller can adjust the pressure of the phase change medium in the heat conduction pipeline through the pressure adjusting pipe.
The pressure control device is used for stabilizing the pressure of the phase change medium so as to provide stable liquid-gas phase change temperature. And different target homogenization temperatures can be obtained by selecting different preset pressures.
When the device operates, the liquid-gas phase temperature of the phase change medium is at the target homogenization temperature through the pressure controller, so that the temperature of the flue gas passing through the heat conduction pipeline network is close to the target, and the function of temperature homogenization is achieved.
The device of the utility model can be provided with a plurality of heat conducting pipeline networks which are respectively extended in different cross sections of the flue. The utility model discloses a device has a heat conduction pipeline network at least, can be called first heat conduction pipeline network, is located first cross section. The device of the utility model can also have second, third and even more heat conduction pipeline networks, be located second, third and even more cross sections respectively. The second cross-section may be downstream of the first cross-section. The plurality of heat conducting pipe networks are in fluid communication with each other, thereby continuing to homogenize the homogenized, but still insufficiently uniform, flue gas.
The phase change temperature and the corresponding phase change medium can be selected as required. At present, the mature catalyst of the SCR technology of the coal-fired boiler is V2O5-TiO2The normal working temperature range of the catalyst is 310-420 ℃, and the optimal temperature range is 340-360 ℃. Therefore, it is preferred to adjust the temperature of the phase change medium at the liquid-vapor phase transition to a temperature between 300 ℃ and 450 ℃, preferably between 310 ℃ and 420 ℃, more preferably between 340 ℃ and 360 ℃. For the temperatureThe temperature range can adopt substances with the liquid-gas phase transition temperature between 300 ℃ and 450 ℃ under normal pressure as the phase transition temperature. Therefore, when the phase change medium works, the working pressure of the phase change medium is near the normal pressure, and the phase change medium is convenient to control. Mercury is a suitable phase change medium. Mercury has a boiling point of 357 c and the phase change temperature can be easily adjusted to the desired value by pressure change. The boiling point of the conventional aviation fuel oil is between 200 and 400 ℃, so that the proper aviation fuel oil can be selected. Polytetrafluoroethylene having a boiling point of 400 ℃ may also be used.
In one embodiment, the flue gas can be passed from top to bottom through a vertical flue in which the device of the present invention is installed. When the local flue gas temperature is higher than the gasification temperature of the phase change medium, the phase change medium is gasified and absorbs a large amount of heat until the local flue gas temperature is equal to the gasification temperature of the phase change medium; similarly, when the local flue gas temperature is lower than the gasification temperature of the phase change medium, the phase change medium can be liquefied and emit a large amount of heat, and the part of heat can heat the flue gas, so that the flue gas temperature is increased. Since the phase change heat of the medium is very large, the mode can realize efficient and quick heat transfer. Finally, the flue gas after the device is close to the liquid-gas phase change temperature of the medium, and the balance of the flue gas temperature distribution on the large section is realized.
The liquid-gas phase temperature can be adjusted according to the temperature of the flue gas to be homogenized so that it lies between the highest and lowest temperature of the flue gas in the cross-section. Preferably, the target homogenisation temperature is set within ± 0.5 ℃ of the mean temperature of the flue gas prior to heat exchange with the phase change medium. So that the averaged flue gas temperature is substantially the average temperature of the flue gas.
The utility model discloses a device can be automatically and quick realization high temperature region to the heat transfer in low temperature district, and then maintains the homogeneity of flue gas temperature distribution in the SCR flue, improves denitration reaction rate, improves the deNOx systems performance.
The device of the utility model is suitable for a flue gas temperature homogenization method, the method includes:
disposing a phase change medium in a first cross-section of the flue;
setting the pressure of the phase change medium to make the liquid-gas phase temperature of the phase change medium at a target homogenization temperature, and setting the temperature of the phase change medium at the liquid-gas phase change temperature; and
enabling the flue gas to pass through the cross section and exchange heat with the phase change medium, so that the flue gas with the temperature higher than the target homogenization temperature is cooled, and the flue gas with the temperature lower than the target homogenization temperature is heated;
wherein the pressure of the phase change medium is maintained stable during the heat exchange, thereby maintaining the phase change medium at the target homogenization temperature.
The method enables the temperature of the flue gas with uneven temperature to approach the target homogenization temperature through heat exchange, and plays a role in temperature homogenization. In addition, by adopting the phase change to absorb and release heat, the temperature homogenization can be realized quickly.
The phase change medium may also be provided in a second cross section of the flue downstream of the first cross section, the phase change medium in the second cross section being in fluid communication with the phase change medium in the first cross section. In this way, the temperature of the flue gas that has been homogenized can be further homogenized.
Preferably, the target homogenisation temperature is within ± 0.5 ℃ of the mean temperature of the flue gas prior to heat exchange with the phase change medium. In this way, the flue gas can be brought to substantially its average temperature after temperature homogenization.
Fig. 1 and 2 are schematic views of an embodiment of the device of the present invention.
FIG. 1 is a top view of a vertical flue. 1 denotes a flue, 10 denotes flue walls. 2 is the heat conducting pipe network in the flue cross section, 21 denotes the heat conducting pipe wall. 3 is a pressure controller, 4 is a pressure regulating tube, and 41 is a pressure regulating tube port. 51(52) is a phase change medium filled in the heat conducting pipe network. The flue gas flows in the direction perpendicular to the paper in 1 and exchanges heat with the phase change medium 51(52) in the pipe network 2 via the heat conducting pipe walls 21. The heat transfer pipe network 2 is in fluid communication with a pressure controller 3 via a pressure regulating tube 4. The pressure regulating tube 4 may have a port 41 thereon.
Fig. 2 is a sectional view taken along a-a' of fig. 1. Wherein the phase change medium is at a liquid-gas phase transition temperature and thus consists of a gas phase 51 and a liquid phase 52. Note that the liquid-gas phase interface between 51 and 52 is only schematic here. When the phase change medium absorbs heat from the flue gas, it will change from a liquid phase 52 to a gas phase 51 at the phase change temperature, but the temperature remains the same. Conversely, when the flue gas is heated from the phase change medium, the phase change medium will change from the gas phase 51 to the liquid phase 52 at the phase change temperature, and the temperature will remain the same.
Figures 3 and 4 show schematic views of the flue gas when it passes through a heat conducting pipe network with non-uniform temperature. The flue gas flowing in from above is indicated by arrows, the temperatures are T1, T2 and T3, respectively, and T1 > T2 > T3. The pressure of the phase change medium is adjusted by the pressure controller 3 via the pressure adjusting pipe 4 so that its liquid-gas phase transition temperature is at the target homogenization temperature. For example, the target homogenization temperature is set to the intermediate temperature T2. At the same time, the temperature of the phase change medium in the heat conducting pipe network 2 is adjusted to T2. At this time, the phase change medium is in a state where the gas phase 51 and the liquid phase 52 coexist, and the temperature is T2. The flue gas with the temperature T1 exchanges heat with the local phase change medium, so that the local phase change medium 52 absorbs heat and changes into the gas phase 51. While flue gas at temperature T3 changes the local gas phase 51 to 52. Under the condition that the pressure controller keeps the pressure of the phase change medium at the port 41 of the pressure control pipe constant, the phase change temperature of the phase change medium in the heat conduction pipeline network is kept at T2, so that the temperature of the T1 flue gas can be continuously reduced, and the temperature of the T3 flue gas can be continuously increased. Thus, in an ideal situation, after passing through the heat conducting pipe, the flue gas changes to the phase transition temperature T2 everywhere.
Fig. 1 to 4 are merely schematic. Various specific configurations of heat conducting pipe networks may be designed.
Fig. 5 shows a schematic view of another embodiment of the present invention. On the basis of fig. 3 and 4, a heat transfer pipe network is further provided downstream of the heat transfer pipe network, which may be referred to as a first and a second heat transfer pipe network, respectively. The downstream second heat transfer duct network may further homogenize flue gas that is not fully temperature homogenized at the first heat transfer duct network to more closely approach the target homogenization temperature.
FIG. 6 shows a schematic diagram of one embodiment of a pressure controller. Which is a chamber, the left side of which communicates with a pressure control tube. The top of the chamber has a piston 6 that can move up and down so that the volume of the chamber can be varied. The outside of the piston is subjected to a pressure P0 that ensures that the liquid-gas phase transition temperature is at the target homogenization temperature. The chamber interior is also filled with phase change media 51 (gas phase) and 52 (liquid phase) and its temperature is also at the phase change temperature. The chamber housing 6 may be a thermally insulating material to insulate the phase change medium inside the chamber from the outside.
FIG. 7 shows a schematic diagram of one embodiment of a pressure controller. In the figure, the rectangle at the bottom left represents a heat conducting pipe network, which includes gaseous and liquid phase change media. A pressure measuring device, such as a pressure gauge, is arranged in the heat conducting pipe network, which measures the pressure in the heat conducting pipe network and sends the measured values to a computer for controlling the pressure. The pressure controller further comprises a negative pressure storage tank and a positive pressure storage tank, which are connected to the heat conducting pipeline network through pressure regulating pipes, respectively. In the figure, a negative pressure tank stores a gas phase change medium therein, and a positive pressure tank stores a liquid phase change medium therein. The two pressure regulating pipes are respectively provided with a pressure reducing valve and a pressure increasing valve. The pressure in the tank is also measured by a pressure gauge and sent to the computer. The pressure controller also includes a pressure pump connected to the reservoir.
When the pressure measured from the heat-conducting pipe network is lower than the pressure for maintaining the stable phase-change temperature, the computer controls to open the pressurizing valve so that the phase-change medium enters the heat-conducting pipe network, thereby increasing the pressure therein to a desired value. On the contrary, when the pressure in the heat conduction network is measured to be too high, the computer opens the pressure reducing valve, so that a part of the phase change medium is discharged into the negative pressure storage tank, and the pressure is reduced to the expected value.
For example, the pressure controller may be constituted by a pressure gauge, a high-pressure tank of 0.1MPa, a negative-pressure tank of-0.5 MPa, a pressure increasing valve, a pressure reducing valve, a pressure pump, and a computer. Here, the pressures are relative pressures.
When the pressure needs to be controlled to be 0.01MPa, the computer controls to open the pressure increasing valve when checking that the actual pressure is smaller than the required pressure, liquid medium is sent into the device, the pressure in the device is continuously increased along with the sending of the medium, and when the pressure gauge detects that the actual pressure reaches 0.01MPa, the computer controls to close the pressure increasing valve.
In the operation process, the high-pressure storage tank is conveyed to the device in one way; the device is sent to the negative pressure storage tank in one way. This ultimately results in lower and higher high and lower pressure tanks. The pressure pump functions to maintain the pressure of both tanks. When the pressure of the storage tank deviates from a normal value, the pressure pump is started, the pressure of the high-pressure storage tank is increased, and the pressure of the negative-pressure storage tank is reduced.
Fig. 8 shows a phase diagram of mercury, showing the phases of mercury at different pressures and temperatures. From the phase boundary line, it can be seen that the phase transition temperature and pressure are in a positive correlation. The liquid-vapor phase temperature of mercury, at around atmospheric pressure, i.e., at about 0.1MPa, is between 300 and 400 c, and is shown as the phase change medium of the flue gas temperature uniformizing apparatus of the present invention.
The invention is further illustrated by the following examples.
Example (b):
the rated load of a certain thermal power generating unit is 600MW, and the size of a flue of an SCR region is 10m multiplied by 9 m. Flue gas volume flow rate of 500000Nm3H is used as the reference value. The smoke density is 1.34kg/m3Therefore, the smoke mass flow is 670000 kg/h. The average temperature of the flue gas in the flue is 350 ℃, and the temperature deviation is +/-10 ℃. One side of the flue is a high-temperature area with the temperature of 360 ℃, and the other side is a low-temperature area with the temperature of 340 ℃. The flue gas flow on the two sides is basically equal.
The constant pressure specific heat of conventional flue gas is about 1.15KJ/(kg · K). In order to achieve 350 ℃ of flue gas on two sides of the flue, the heat exchange amount per unit time is 2140.3 kW. In the case of a heat exchanger in cross-section for heat exchange, if the heat exchanger tubes occupy a cross-sectional area of 1/9, i.e. the total heat exchange area is 10m2. The required heat transfer coefficient will be 21402.8W/(m)2·K)。
Such a high heat transfer coefficient is difficult to achieve with conventional heat transfer media that do not involve a phase change. E.g. even if it is adoptedThe forced convection heat exchange of water has the heat exchange coefficient of only 1000-15000W/(m)2K), far from satisfying the requirements.
In the phase change process, the heat of vaporization (also called potential) is often very large, so the heat transfer coefficient of phase change heat transfer is far greater than the heat transfer coefficient of convection. For example, if mercury is used as the phase change medium, its latent heat is 272 KJ/kg. Namely, mercury absorbs the heat of the flue gas in a high-temperature area (360 ℃), and the flue gas is changed into a gas state from a liquid state at the speed of 7.8 kg/s; mercury releases heat in a low-temperature region (340 ℃) and changes from a gas state to a liquid state at the speed of 7.8kg/s, so that the temperature of the high-temperature region and the low-temperature region can reach 350 ℃ rapidly, and temperature balance is realized.
It will be apparent to those skilled in the art that various changes and modifications may be made to the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (9)
1. A flue gas temperature uniformalizing device, characterized in that the device comprises:
a first network of heat transfer pipes in a first cross section of the flue, the first network of heat transfer pipes filled with a phase change medium;
a pressure controller disposed outside the flue; and
a pressure regulator tube fluidly connecting the first network of thermally conductive tubing and the pressure controller,
wherein the pressure controller is configured to adjust the pressure of the phase change medium in the first network of heat transfer conduits via the pressure regulating tube such that the liquid-to-vapor phase temperature of the phase change medium is at a target homogenization temperature.
2. The flue gas temperature uniforming device according to claim 1,
the pressure controller adjusts the pressure by changing the total volume of the phase change medium.
3. The flue gas temperature uniforming device according to claim 2,
the pressure controller is a chamber having a piston.
4. The flue gas temperature uniforming device according to claim 1,
the pressure controller adjusts the pressure by changing the amount of the phase change medium.
5. The flue gas temperature uniforming device according to claim 4,
the pressure controller includes:
a negative pressure tank receiving a phase change medium from the network of thermally conductive pipes; and
and the positive pressure storage tank is used for inputting the phase change medium into the heat conduction pipeline network.
6. The flue gas temperature uniforming device according to claim 1, further comprising:
a second network of heat transfer conduits in a second cross section of the flue downstream of the first cross section, the second network of heat transfer conduits filled with the phase change medium, and the second network of heat transfer conduits in fluid communication with the first network of heat transfer conduits.
7. The flue gas temperature uniforming device according to claim 1,
the liquid-gas phase transition temperature is between 300 ℃ and 450 ℃.
8. The flue gas temperature uniforming device according to claim 1,
the liquid-gas phase transition temperature of the phase transition medium under normal pressure is between 300 ℃ and 450 ℃.
9. The flue gas temperature uniforming device according to claim 8,
the phase change medium is selected from mercury, aviation fuel oil or polytetrafluoroethylene.
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| CN201922095969.2U CN212327935U (en) | 2019-11-28 | 2019-11-28 | Flue gas temperature homogenizing device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110898663A (en) * | 2019-11-28 | 2020-03-24 | 国家电投集团远达环保工程有限公司重庆科技分公司 | Flue gas temperature homogenizing device and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110898663A (en) * | 2019-11-28 | 2020-03-24 | 国家电投集团远达环保工程有限公司重庆科技分公司 | Flue gas temperature homogenizing device and method |
| CN110898663B (en) * | 2019-11-28 | 2024-03-22 | 国家电投集团远达环保工程有限公司重庆科技分公司 | Flue gas temperature homogenizing device and method |
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