The invention is applied for 20 days 7 months in 2018, the application number is 2018108050172, and the invention and creation name is a divisional application of a power station boiler flue gas waste heat utilization system.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides novel-structure flue gas waste heat utilization devices and methods, which fully utilize heat sources, reduce energy consumption and improve smoke exhaust effect.
In order to achieve the purpose, the invention adopts the following technical scheme:
flue gas waste heat utilization system of power station boilers comprises a heat pipe, a flue gas channel and an air channel, wherein the heat pipe comprises an evaporation end and a condensation end, the condensation end is arranged in the air channel, the evaporation end absorbs waste heat of flue gas in a boiler flue and transfers heat to air in the air channel through the condensation end, the preheated air enters a boiler furnace to support combustion, a stabilizing device is arranged in the heat pipe and is of a sheet structure, the sheet structure is arranged on the cross section of the heat pipe, the stabilizing device is composed of a square through hole and a regular octagonal through hole, the side length of the square through hole is equal to that of the regular octagonal through hole, four sides of the square through hole are respectively sides of four different regular octagonal through holes, and four mutually spaced sides of the regular octagonal through hole are respectively sides of four different square through holes.
Preferably, the cross-section of the heat pipe is square.
Preferably, the distance between adjacent stabilizers is M1, the side length of the square through hole is C1, the heat pipe is a square section, and the side length of the square section of the heat pipe is C2, so that the following requirements are met:
M1/C2=a*Ln(C1/C2)+b
wherein a, b are parameters, wherein 1.725< a <1.733,4.99< b < 5.01; 11< C2<46 mm;
1.9<C1<3.2mm;
18<M1<27mm。
preferably, the stabilizers include at least of two types, the type is a square central stabilizer with a square through hole in the center of the heat pipe, and the second type is a regular octagonal central stabilizer with a regular octagonal through hole in the center of the heat pipe.
Preferably, the adjacently arranged stabilizing means are of different types.
The invention has the following advantages:
1) the invention provides a power station boiler waste heat utilization system of a stabilizing device with a novel structure combining novel square through holes and regular octagon through holes, wherein the included angles formed by the edges of the formed square holes and regular octagon through the squares and the regular octagons are both larger than or equal to 90 degrees, so that fluid can fully flow through each position of each hole, and short circuit of fluid flow is avoided or reduced.
2) According to the invention, through reasonable layout, the square and regular octagonal through holes are uniformly distributed, so that the fluid on the whole cross street is uniformly divided, and the problem of nonuniform division of the annular structure along the circumferential direction in the prior art is avoided.
3) The invention ensures that the large holes and the small holes are uniformly distributed on the whole cross section by uniformly distributing the square holes and the regular octagonal holes at intervals, and ensures that the separation effect is better by changing the positions of the large holes and the small holes of the adjacent stabilizing devices.
4) According to the invention, the stabilizing device is of a sheet structure, so that the stabilizing device is simple in structure and low in cost.
5) According to the invention, the optimal relation size of the parameters is researched by setting the regular changes of the parameters such as the distance between adjacent stabilizing devices, the side length of the holes of the stabilizing devices, the pipe diameter of the heat absorbing pipes, the pipe spacing and the like in the height direction of the heat absorbing pipes, so that steps are carried out to achieve the effect of stabilizing the flow, reduce the noise and improve the heat exchange effect.
6) The invention carries out extensive research on the heat exchange rule caused by the change of each parameter of the stabilizing device, and realizes the optimal relational expression of the heat exchange effect under the condition of meeting the flow resistance.
7) waste heat utilization devices with novel structures are provided, and uniform pressure, uniform distribution of fluid flow and uniform distribution of fluid motion resistance in each heat pipe are ensured by arranging the flow equalizing pipe between the heat pipes.
Detailed Description
boiler flue gas waste heat utilization system, the waste heat utilization system includes a heat pipe 11, a flue gas channel 1 and an air channel 2, the heat pipe 11 includes an evaporation end 111 and a condensation end 112, the condensation end 112 is arranged in the air channel 12, the evaporation end 11 is arranged in the flue, the evaporation end 111 absorbs the waste heat of the flue gas in the boiler flue, the heat is transferred to the air in the air channel 12 through the condensation end 112, and the preheated air enters the boiler furnace for combustion supporting.
When the heat pipe is in operation, heat is absorbed from flue gas through the evaporation end 111, then the heat is released to air at the condensation end, fluid is condensed, and then enters the evaporation end 111 under the action of gravity.
In the operation process of the waste heat utilization device, fluid distribution is uneven, in the heat collection process, different heat pipes absorb different heat, so that the temperatures of fluids in different heat pipes are different, and in some heat pipes, even the fluids, such as water, are in a gas-liquid two-phase state, and the fluids in some heat pipes are still liquid, so that the pressure in the heat pipes is increased because the fluids are changed into steam, and therefore, the fluids can flow in the heat pipes mutually by arranging the flow equalizing pipes among the heat pipes, so that the pressure distribution in all the heat pipes is balanced, and the fluid distribution can be promoted to be balanced.
options, as shown in fig. 6, a flow equalizing pipe 3 is arranged between the heat pipes, and a flow equalizing pipe 3 is arranged between at least two adjacent heat pipes 11, it is found in research that in the process of heat absorption and heat release of the evaporation pipe, the heat absorption amount and the heat release amount of the heat absorption and heat release pipes at different positions are different, which results in different pressures or temperatures between the heat pipes 11, which results in overhigh temperature of part of the heat pipes 11 and shortened service life, and denier heat pipes 11 have problems, which may cause the problem that the whole waste heat utilization system cannot be used.
Preferably, a plurality of uniform flow tubes 3 are arranged between adjacent heat pipes 11 from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. Through setting up a plurality of flow equalizing pipes, can make the continuous balanced pressure of fluid in the heat absorption evaporation process, guarantee the pressure balance in the whole heat pipe.
Preferably, at the evaporation end 111, the distance between adjacent uniform flow tubes 3 decreases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. The purpose is to arrange more flow equalizing pipes, because the fluid continuously absorbs heat along with the upward flow of the fluid, and the pressure in different heat pipes is more and more uneven along with the continuous heat absorption of the fluid, so that the pressure equalization can be ensured to be achieved as soon as possible in the flowing process of the fluid through the arrangement.
Preferably, at the evaporation end 111, the distance between adjacent uniform flow tubes decreases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 to a greater extent. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.
Preferably, the diameter of the equalizer tube 3 increases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 at the evaporation end 111. The purpose is to ensure a larger communication area, because the fluid continuously absorbs heat to generate steam along with the upward flow of the fluid, and the temperature and pressure in different heat pipes are more and more uneven along with the continuous difference of the steam, so that the pressure balance can be ensured to be achieved as soon as possible in the flowing process of the fluid through the arrangement.
Preferably, the diameter of the equalizer tube 3 increases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 at the evaporation end 111. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.
Preferably, at the condensation end 112, the distance between adjacent uniform flow tubes 3 increases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. The purpose is to arrange fewer flow equalizing pipes and reduce the cost. Because the steam in the heat pipe continuously releases heat and condenses along with the upward lower part of the condensation end 112, and the pressure in the heat pipe is smaller and smaller along with the continuous heat release of the fluid, the phenomenon of non-uniformity is more and more alleviated, therefore, by the arrangement, the material can be saved, and the pressure equalization can be achieved as soon as possible in the flowing process of the fluid by arranging the flow equalizing pipe according to the pressure change.
Preferably, at the condensation end 112, the distance between adjacent uniform flow tubes increases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.
Preferably, the diameter of the flow equalizing pipe 3 at the condensation end 112 decreases from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11. The purpose is to ensure reduced communication area and reduce cost. The same principle as the distance from the front is increasing.
Preferably, the diameter of the flow equalizing pipe 3 is gradually reduced from the evaporation end of the heat pipe 11 to the condensation end of the heat pipe 11 at the condensation end 112. Experiments show that the arrangement can ensure that the pressure balance is achieved more optimally and more quickly in the fluid flowing process. This is also the best way of communicating by extensively studying the law of change of the pressure distribution.
In the heat pipe, because of the heat exchange of the steam, the heat pipe generates steam-liquid two-phase flow, in the aspect of , the heat pipe inevitably carries liquid into the heat pipe in the evaporation process, meanwhile, because of the heat release and condensation of the condensation end, the liquid exists in the condensation end, and the liquid inevitably enters the steam, so that the fluid in the heat pipe is a steam-liquid mixture, meanwhile, the heat pipe can rise to the condensation end on the upper part of the heat pipe like incondensable gas due to aging in the operation process, the pressure in the condensation end of the heat pipe is increased due to the incondensable gas, and the liquid flows into the heat pipe due to the pressure.
A stabilizing device 4 is arranged in the heat pipe, and the structure of the stabilizing device 4 is shown in figures 2 and 3. The stabilizing device 4 is a sheet-like structure which is arranged on the cross section of the heat pipe 11; the stabilizing device 4 is composed of a square and regular octagonal structure, so that a square through hole 41 and a regular octagonal through hole 42 are formed. The side length of the square through hole 41 is equal to the side length of the regular octagonal through hole 42 as shown in fig. 2, the four sides 43 of the square through hole are the sides 43 of four different regular octagonal through holes, respectively, and the four mutually spaced sides 43 of the regular eight deformed through hole are the sides 43 of four different square through holes, respectively.
The invention adopts a stabilizing device with a novel structure, and has the following advantages:
1) the invention provides a stabilizing device with a novel structure combining novel square through holes and regular octagon through holes, wherein the included angle formed by the edges of the formed square through holes and regular octagon through the square and regular octagon is more than or equal to 90 degrees, so that fluid can fully flow through each position of each hole, and short circuit of fluid flow is avoided or reduced.
2) According to the invention, through reasonable layout, the square and regular octagonal through holes are uniformly distributed, so that the fluid on the whole cross street is uniformly divided, and the problem of nonuniform division of the annular structure along the circumferential direction in the prior art is avoided.
3) According to the invention, the square holes and the regular octagonal through holes are uniformly distributed at intervals, so that the large holes and the small holes are uniformly distributed on the whole cross section, and the separation effect is better through the position change of the large holes and the small holes of the adjacent stabilizing devices.
4) According to the invention, the stabilizing device is of a sheet structure, so that the stabilizing device is simple in structure and low in cost.
By arranging the annular stabilizing device, the invention equivalently increases the internal heat exchange area in the heat pipe, strengthens the heat exchange and improves the heat exchange effect.
The invention divides the gas phase and the liquid phase at all cross section positions of all heat exchange tubes, thereby realizing the contact area between the division of a gas-liquid interface and a gas phase boundary layer and a cooling wall surface on the whole heat exchange tube section and enhancing the disturbance, greatly reducing the noise and the vibration and strengthening the heat transfer.
Preferably, the stabilizing means includes two types, as shown in fig. 2 and 3, type is a square central stabilizing means, a square is positioned at the center of the heat pipe or the condenser pipe, as shown in fig. 3, and the second type is a regular octagonal central stabilizing means, a regular octagon is positioned at the center of the heat pipe or the condenser pipe, as shown in fig. 2, as preferred, the two types of stabilizing means are adjacently arranged, that is, the type of stabilizing means adjacently arranged is different, that is, the regular octagonal central stabilizing means is adjacent to the square central stabilizing means, and the square central stabilizing means is adjacent to the regular octagonal central stabilizing means.
Preferably, the heat pipe 11 has a square cross-section.
Through analysis and experiments, the distance between the stabilizing devices cannot be too large, the damping, noise reduction and separation effects are poor if the distance is too large, meanwhile, the distance cannot be too small, the resistance is too large if the distance is too small, and similarly, the side length of a square cannot be too large or too small, the damping and noise reduction effects are poor or the resistance is too large, so that the damping and noise reduction effects are optimized under the condition that normal flow resistance (the total pressure bearing is less than 2.5MPa or the on-way resistance of a single heat pipe is less than or equal to 5Pa/M) is preferentially met through a large number of experiments, and the optimal relation of each parameter is arranged.
Preferably, the invention is arranged on a vertical flue. The heat pipe is vertical to the extending direction of the flue. I.e. the heat pipe extends in the horizontal direction.
Preferably, the distance between adjacent stabilizers is M1, the side length of the square through hole is C1, the heat pipe is a square section, and the side length of the square section of the heat pipe is C2, so that the following requirements are met:
M1/C2=a*Ln(C1/C2)+b
wherein a, b are parameters, wherein 1.725< a <1.733,4.99< b < 5.01.
11<C2<46mm;
1.9<C1<3.2mm;
18<M1<27mm。
preferably, a is smaller and b is larger as the ratio of C1/C2 is increased.
Preferably, a is 1.728, b is 4.997;
preferably, the side length C1 of the square through hole is the average value of the inner side length and the outer side length of the square through hole, and the side length C2 of the square cross section of the heat pipe is the average value of the inner side length and the outer side length of the heat pipe.
Preferably, the outer length of the square through hole is equal to the inner length of the square section of the heat pipe.
Preferably, the C1 is increased with the increase of C2, but the increasing amplitude of C1 is smaller and smaller with the increase of C2, the regular change is obtained by a large number of numerical simulations and experiments, and the heat exchange effect can be further improved and the noise is reduced.
Preferably, M1 is continuously reduced with the increase of C2, but the amplitude of the continuous reduction of M1 is smaller and smaller with the increase of C2, the regular change is obtained through a large number of numerical simulations and experiments, and the heat exchange effect can be further steps by the regular change, so that the noise is reduced.
Analysis and experiments show that the distance between the heat pipes also meets requirements, for example, the distance cannot be too large or too small, no matter the distance is too large or too small, the heat exchange effect is poor, and because the stabilizing device is arranged in the heat pipe, the stabilizing device also meets requirements on the distance between the heat pipes, therefore, the damping and noise reduction are optimized under the condition that normal flow resistance (the total pressure bearing is less than 2.5MPa or the on-way resistance of a single heat pipe is less than or equal to 5Pa/M) is preferentially met through a large number of experiments, and the optimal relation of each parameter is arranged.
The distance between adjacent stabilizing devices is M1, the side length of a square is C1, the heat pipe is a square section, the side length of the heat pipe is C2, an acute angle formed by the heat pipe and a horizontal plane is A, and the distance between the centers of the adjacent heat pipes is M2, so that the following requirements are met:
M2/C2=d*(M1/C2)2+e-f*(M1/C2)3-h*(M1/C2);
wherein d, e, f, h are parameters,
1.239<d<1.240,1.544<e<1.545,0.37<f<0.38,0.991<h<0.992。
11<C2<46mm;
1.9<C1<3.2mm;
18<M1<27mm。
16<M2<76mm。
the spacing between the centers of adjacent heat pipes is M2, which refers to the distance between the centerlines of the heat pipes.
, d is 1.2393, e is 1.5445, f is 0.3722, h is 0.9912;
preferably, d, e, f are larger and h is smaller as M1/C2 is increased.
Preferably, M2 is increased with the increase of C2, but the increasing amplitude of M2 is smaller and smaller with the increase of C2, the regular change is obtained through a large number of numerical simulations and experiments, and the heat exchange effect can be further steps through the regular change.
Preferably, the length of the evaporation end (the length of the heat pipe in the flue 1) is between 1000-.
Preferably, the length of the condensation end is between 500 and 900mm, and the further step is preferably between 600 and 700 mm.
By optimizing the optimal geometric dimension of the formula, the optimal effect of shock absorption and noise reduction can be achieved under the condition of meeting the normal flow resistance.
For other parameters, such as pipe wall, wall thickness, etc., it is sufficient to set the parameters according to normal standards.
The heat pipes are multiple, and the distribution density of the heat pipes is smaller and smaller along the flowing direction of the flue gas. In numerical simulation and experiments, the heat pipes are heated less and less along the flowing direction of the flue gas, and the temperatures of the heat pipes at different positions are different, so that local heating is not uniform. Because the temperature of the flue gas is continuously reduced along with the continuous heat exchange of the flue gas, the heat exchange capacity is also reduced, and therefore, the density of the heat pipes arranged at different positions of the flue gas channel is different, the heat absorption capacity of the heat pipes is continuously reduced along the flow direction of the flue gas, the temperature of the whole heat pipes is basically the same, the whole heat exchange efficiency is improved, materials are saved, the local damage caused by uneven temperature is avoided, and the service life of the heat pipes is prolonged.
Preferably, the distribution density of the heat pipes is continuously increased with smaller and smaller amplitude along the flow direction of the flue gas. As the change of the distribution density of the heat pipe, the invention carries out a large number of numerical simulations and experiments, thereby obtaining the change rule of the distribution density of the heat pipe. Through the change rule, materials can be saved, and meanwhile, the heat exchange efficiency can be improved by about 9%.
Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.