CN113217928A - Boiler system with optimized linear temperature equalizing structure - Google Patents

Abstract

The invention provides a boiler system.A flow guide part extending from the inner wall of a flue gas pipeline to the center of the flue gas pipeline is arranged in the flue gas pipeline between an economizer and an air preheater, a first straight line wall and a second bent wall extend towards the flow direction of flue gas, and the intersection point of a first wall straight line and the second straight line wall is positioned at the downstream of the joint of the first straight line wall and the inner wall and is also positioned at the downstream of the joint of the second straight line wall and the inner wall. The shape of the flow-inducing member is a shape formed by rotating the first and second linear walls and the inner wall along the axis of the outlet pipe. The invention provides a method for reducing flow resistance by arranging a linear flow guide component in a flue gas pipeline, wherein the included angle needs to be set to be smaller and smaller, and the temperature equalizing effect achieves the basically same effect on the aspects of reducing resistance and saving material cost.

Description

Boiler system with optimized linear temperature equalizing structure

Technical Field

The invention relates to the field of heat exchange, in particular to a boiler system with uniform temperature and smoke exhaust temperature.

Background

A large thermal power generating unit generally adopts a rotary air preheater to recover waste heat of a tail flue, and a heat exchange mode of periodic flow heat storage enables flue gas at an outlet of the air preheater to have larger temperature difference in the tangential direction, and the maximum temperature difference in the tangential direction of the rotary air preheater can reach 100 ℃ under normal operation conditions. If the air preheater has serious problems of ash blockage, corrosion, air leakage and the like under the long-term operation condition, the tangential temperature difference of the flue gas at the outlet of the air preheater is far higher than 100 ℃. The tangential huge temperature difference of the flue gas at the outlet of the air preheater enables the temperature of the flue gas at the outlet of the air preheater to be uneven, the mixing length in the distributor is limited, the flue gas is difficult to be completely mixed, and finally the temperature of the flue gas at the outlet of the air preheater is uneven.

Usually, a low-temperature economizer is arranged between the air preheater and the dust remover and used for recovering the waste heat of the flue gas, and at present, condensed water is commonly used for recovering the heat. Generally, the low-temperature coal economizer of each flue gas flow passage in front of the dust remover has the same heat exchange area and heat exchange capacity. If the flue gas temperature deviation is large, the flue gas temperature of some flow passages is lower than the original design value, and the flue gas temperature of some flow passages is higher than the original design value. Under the condition that the flue gas temperature is lower than the design value of the inlet flue gas temperature of the low-temperature economizer, the heat exchange area of the low-temperature economizer of the flow channel is excessive, so that waste is caused, and if the flue gas temperature is equivalent to the design value of the outlet flue gas temperature of the low-temperature economizer, the low-temperature economizer on the flow channel cannot be put into operation, namely, the flue gas resistance is increased, and the economic benefit on heat is not obtained. Under the condition that the flue gas temperature is higher than the design value of the inlet flue gas temperature of the low-temperature economizer, the heat exchange area of the low-temperature economizer of the flow channel is insufficient, although some allowance exists when the low-temperature economizer is selected, if the flue gas temperature exceeds the design value too much, the outlet flue gas temperature of the low-temperature economizer cannot be reduced to the outlet flue gas temperature of the designed low-temperature economizer, and heat waste is caused.

The heat exchange areas and the like of the low-temperature economizers on each channel are the same, the inlet flue gas temperatures are different, in order to reach the same outlet flue gas temperature, the condensate flow of each low-temperature economizer is different, and a regulating valve is further arranged on a water pipeline of each low-temperature economizer, so that the operation and regulation are difficult.

The temperature of the inlet of the low-temperature economizer has deviation, while the temperature of the outlet of the low-temperature economizer is the same, so that the actual flue gas volume deviation of each channel is aggravated, the flue gas volume deviation in each channel of the dust remover is caused, and the dust removal effect is influenced to a certain extent.

Therefore, in order to overcome the defects, the patent previously applied by the applicant provides a boiler system with a flue temperature equalization function, so that the temperature of the flue gas entering the low-temperature economizer is uniform, the requirement of further heat exchange is met, and the service life of the product is prolonged.

The application is an improvement to prior application, and the application is through improving the optimization of prior application structure for the flow resistance of the inside fluid of flue diminishes, and the samming effect reaches the best.

Disclosure of Invention

One of the main objects of the present invention is to provide a boiler system, which improves the flue structure to achieve uniform outlet flue gas temperature, thereby achieving the need of further heat exchange and prolonging the service life of the product.

In order to achieve the purpose, the invention adopts the following technical scheme:

a boiler system comprises a boiler, wherein a flue gas outlet is formed in the top of the boiler and is connected with a flue, an air preheater, a plurality of coal economizers and a dust remover are sequentially arranged in the flue, the tail end of a flue gas pipeline between the coal economizer and the air preheater is provided with a plurality of flue gas outlets, and each flue gas outlet is respectively connected with one coal economizer; the flue gas preheating device is characterized in that a flow guide component extending from the inner wall of the flue gas pipeline to the center of the flue gas pipeline is arranged in the flue gas pipeline between the economizer and the air preheater, the flow guide component comprises a first straight line wall and a second straight line wall extending from the inner wall, an acute angle formed by the first straight line wall and the inner wall is smaller than an acute angle formed by the second straight line wall and the inner wall, the first straight line wall and the second curved wall extend towards the flow direction of flue gas, the intersection point of the first straight line wall and the second straight line wall is located at the downstream of the joint of the first straight line wall and the inner wall, and is located at the downstream of the joint of the second straight line wall and the inner wall. The shape of the drainage component is a shape formed by rotating the first linear wall, the second linear wall and the inner wall along the axis of the outlet pipe; the flue gas guiding device is characterized in that a plurality of flow guiding components are arranged on the inner wall of the flue gas pipeline along the flowing direction of flue gas, and the included angle of A2 is smaller and smaller along the flowing direction of the flue gas.

Preferably, the included angle a2 increases with decreasing magnitude along the direction of flow of the flue gas.

Preferably, the tangent to the first curved wall at the point of intersection forms an angle of 30-60 ° with the axis of the flue gas duct.

Preferably, the tangent to the first rectilinear wall at the point of intersection forms an angle of 45 ° with the axis of the flue gas duct.

Compared with the prior art, the invention has the beneficial effects that:

1) the invention provides a method for reducing flow resistance by arranging a linear flow guide component in a flue gas pipeline, wherein the included angle needs to be set to be smaller and smaller, and the temperature equalizing effect achieves the basically same effect on the aspects of reducing resistance and saving material cost.

2) The invention provides a novel boiler system, wherein a linear flow guide device is arranged in a flue gas pipeline between an economizer and an air preheater, so that part of flue gas flows along a flow guide plate and is guided to the opposite direction, and the flue gas is fully mixed with the flue gas entering from the opposite direction, thereby realizing uniform temperature of the flue gas, realizing the requirement of further heat exchange and prolonging the service life of products.

3) According to the invention, through carrying out extensive research on the heat exchange rule caused by the change of each parameter of the guide plate, the guide plate structure of the heat exchanger is optimized under the condition of meeting the flow resistance, so that the optimal outlet flue gas temperature equalization effect is achieved.

4) According to the invention, through reasonable layout, the guide plate structures in adjacent rows are arranged in a staggered manner, so that the flue gas is further fully mixed, and the temperature is uniform.

5) The invention further promotes the full mixing by setting the distribution change of parameters such as the size, the number angle and the like of the guide plate along the flowing direction of the fluid.

6) According to the invention, the distance of the guide plate is widely researched, a formula of the minimum distance is designed, the temperature-equalizing mixing requirement is fully met, the problems of uneven mixing and increased flow resistance are avoided, and the optimal outlet flue gas temperature-equalizing effect is achieved.

Description of the drawings:

FIG. 1 is a schematic structural view of a boiler system;

FIG. 2 is an axial sectional view of the flue gas duct of the present invention with a vapor chamber;

fig. 3 is a schematic size diagram of the flue gas duct of the present invention.

Fig. 4 is a schematic perspective view of 1 temperature equalization plate per layer.

Fig. 5 is a schematic perspective view of 4 temperature equalization plates disposed in each layer.

Fig. 6 is a schematic perspective view of 1 temperature equalization plate per layer.

Fig. 7 is an exploded perspective view of one side of the flue gas duct of fig. 6.

The reference numbers are as follows:

34 boiler, 35 air preheater, 36 economizer and 37 dust remover

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

Fig. 1 discloses a schematic structural view of a boiler system. As shown in fig. 1, the boiler system includes a boiler 34, a flue gas outlet is arranged at the top of the boiler 34, the flue gas outlet is connected to a flue, an air preheater 35, an economizer 36 and a dust remover 37 are sequentially arranged in the flue, the economizer 36 is provided in plurality, wherein flue gas from the air preheater 35 enters different economizers in a plurality of ways.

In operation, pulverized coal is combusted in a hearth to generate smoke, the smoke flows through a water-cooled wall and a superheater and then enters an air preheater 35, the smoke after primary air and secondary air are heated in the air preheater 35 is divided into multiple paths (preferably three paths) and respectively enters a plurality of (preferably three) low-temperature economizers 36, the smoke enters a dust remover for dust removal 37 after a boiler is heated in the economizers 36 to return water, and the smoke after dust removal is discharged through a chimney.

The tail end of the flue gas pipeline 5 between the economizer and the air preheater is provided with a plurality of flue gas outlets, and each flue gas outlet is connected with one economizer 36. Because the flue gas temperature is different at different positions in the flue, the problem of uneven flue gas temperature distribution exists in a plurality of flue gas channels connected at the tail ends of the flue gas pipelines 5.

As a modification, as shown in fig. 2, a flow guide member 2 extending from an inner wall 51 of the flue gas duct toward the center of the flue gas duct is provided in the flue gas duct 5 between the economizer and the air preheater, and the flow guide member 2 includes a first straight wall 21 and a second straight wall 22 extending from the inner wall, wherein the acute angle formed by the first straight wall 21 and the inner wall is smaller than the acute angle formed by the second straight wall 22 and the inner wall, the first straight wall 21 and the second curved wall 22 extend toward the flow direction of flue gas, and the intersection 23 of the first straight wall 21 and the second straight wall 22 is located downstream of the junction of the first straight wall 21 and the inner wall 51 and downstream of the junction of the second straight wall 22 and the inner wall. The shape of the flow directing member 2 is a shape formed by the first and second rectilinear walls 21, 22 and the inner wall rotating along the outlet tube axis.

The invention provides a method for improving the temperature uniformity of flue gas, which is characterized in that the drainage component is arranged in the flue gas outlet pipe, so that a part of the flue gas flows along the drainage component and is guided to the opposite direction, and the flue gas is fully mixed with the flue gas entering from the opposite direction, thereby realizing the uniform temperature of the flue gas, realizing the further heat exchange requirement and prolonging the service life of products. And through setting up the second straight line wall, the gradient of second straight line wall is little moreover for flue gas from opposite direction water conservancy diversion also can be along the upward direction motion of second straight line wall direction, increase the buffering, reduce flow resistance.

According to the invention, the drainage component is respectively provided with the first linear wall and the second linear wall, the disturbance effect of the flue gas is better by arranging the two linear walls, the area of the drainage component contacting the inner wall is increased, and the stability is improved.

Preferably, the first rectilinear wall 21 at the location of the intersection point 23 forms an angle of 30-60 deg. with the axis of the outlet duct, preferably 45 deg.. By providing this angle, fluid can be quickly directed to the opposite downstream location, and flow resistance can be further reduced.

Preferably, as shown in fig. 2, a plurality of layers of flow guiding components 2 are arranged on the inner wall of the outlet pipe 5 along the flowing direction of the flue gas, and the flow guiding components of the adjacent layers are distributed in a staggered mode. Through the staggered distribution of the adjacent rows of the drainage components, the flue gas can fully move to the opposite position in the outlet pipe, and the full and uniform mixing is ensured. For example, fig. 2, 4 and 6 show that one block is arranged for each layer of drainage component, and the total arc of the block is 150 and 180 degrees. Of course, multiple drainage members may be provided for each layer, for example, three per layer in FIG. 5, with a total arc of 150 and 180.

Preferably, the distance between the intersection point and the inner wall of the outlet pipe is 0.3 to 0.5 times, preferably 0.4 times the diameter of the outlet pipe. With this arrangement, the flue gas has less flow resistance on the basis of sufficient mixing.

Preferably, the length of the first rectilinear wall is greater than the length of the second rectilinear wall.

Preferably, the total radian of the arc connecting the drainage component and the inner wall in the same layer is 150-180 degrees. This parameter set ensures thorough mixing while meeting the resistance requirements. For example, fig. 2 shows that one drainage member is provided for each layer, and the total arc of the one drainage member is 150 and 180 degrees. Of course, each layer of drainage component can be provided with a plurality of blocks, for example, two blocks with a total arc of 150 and 180 degrees, or four blocks with a total arc of 150 and 180 degrees.

Preferably, a plurality of drainage components of the A layer are arranged, intervals are arranged among the drainage components of the A layer, the drainage components of the A layer are arranged at equal intervals, the B layer is an adjacent row of the A layer, and the drainage components of the B layer are arranged at the intervals of the A layer when viewed from the flowing direction. Through the position complementation of the drainage components of the adjacent layers, the smoke can fully move to the opposite position in the outlet pipe, and the full and uniform mixing is ensured. It should be noted that the layer a and the layer B are not specifically and explicitly specified, and A, B is only used as a distinction and is used as an adjacent layer.

Preferably, a plurality of flow guiding components are arranged on the inner wall of the outlet pipe along the flowing direction of the flue gas, and the distribution density of the flow guiding components is smaller and smaller along the flowing direction of the flue gas. Because the mixing degree of the flue gas is better and better along with the continuous movement of the flue gas, the distribution density is required to be set to be smaller and smaller so as to reduce the flow resistance, and the temperature equalizing effect achieves the basically same effect on the aspects of reducing the resistance and saving the material cost.

Preferably, the distribution density of the flow-guiding member is increased to a smaller and smaller extent along the flow direction of the flue gas. The effect is the result through a large amount of numerical simulation and experimental research, through research discovery, this law accords with the law of flue gas motion, on the degree that resistance further reduces and material cost saves, the samming effect reach basically the same effect.

Preferably, a plurality of flow guiding parts are arranged on the inner wall of the outlet pipe along the flowing direction of the flue gas, and the size of the flow guiding parts is smaller along the flowing direction of the flue gas. Because the mixing degree of the flue gas is better and better along with the continuous movement of the flue gas, the size is required to be set to be smaller and smaller so as to reduce the flow resistance, and the temperature equalizing effect achieves the basically same effect on the aspects of reducing the resistance and saving the material cost.

Preferably, a plurality of flow guiding components are arranged on the inner wall of the outlet pipe along the flowing direction of the flue gas, and the size of the flow guiding components is gradually reduced along the flowing direction of the flue gas. The effect is the result through a large amount of numerical simulation and experimental research, through research discovery, this law accords with the law of flue gas motion, on the degree that resistance further reduces and material cost saves, the samming effect reach basically the same effect.

Through a large amount of numerical simulation and experimental study discovery, drainage part's angle and size have very big influence to heat transfer and misce bene, drainage part and inner wall contained angle are on the small side, can lead to mixing the effect variation, and lead to drainage part size too big, influence flow resistance, the contained angle is on the large side, it is not good to lead to stirring the fluid effect, the resistance grow, mixing the effect variation, drainage part's interval is too big, can lead to the vortex effect not good, interval undersize can lead to increasing the movement resistance, consequently, this application has obtained nearest drainage part structure size optimization relation through a large amount of data simulation and experiments.

Preferably, the length L2 of the first straight wall, the length L1 of the second straight wall, the acute angle between the first line and the inner wall is a2, the acute angle between the second line and the inside is a1, the distance S between the structures of the adjacent flow guiding components along the flow direction of the flue gas (for example, the distance between the two adjacent flow guiding components at the upper side of fig. 2 is S), that is, the distance between the center points of the adjacent flow guiding components on the inner wall, and the center point is the middle point of the connecting line of the connecting points of the first straight wall, the second straight wall and the inner wall, and the following requirements are met:

n-a-b ln (M), wherein N ═ (L1+ L2)/S, M ═ sin (a2)/sin (a 1); ln is a function of the logarithm of the number,

0.3123<a<0.3128，0.1267<b<0.1270；

preferably, 0.25< M <0.75,0.34< N <0.44,45< a1<75 °, 15< a2<65 °,350< S <500mm, 70< L2<130mm, 30< L1<90 mm.

The optimum design requirements of the flow-guiding component structure can be met by the above-mentioned formulas. The structural optimization formula is a main improvement point of the invention, is the most optimized formula which is researched by a large number of numerical simulations and experiments, and is not common knowledge in the field.

More preferably, a is 0.3126 and b is 0.1269.

Found in data simulation and experiment, the interval between the drainage part must be greater than certain distance, otherwise can lead to the fluid to guide to opposite direction through last drainage part, but if the interval undersize between the drainage part, can lead to the flue gas to flow opposite, not fully filled with whole pipeline yet, set up the drainage part this moment, play not mixed effect, the drainage part only plays a baffling board effect, does not guide the effect of mixing, can only increase flow resistance. Therefore, the design scheme of the minimum distance of the drainage component is provided through a great deal of research, and the design method has certain guiding significance for the design of the drainage component.

The vertical point of the intersection point 23 on the inner wall, the line formed by the intersection point and the vertical point is a third line, the distance between the connecting point of the first straight line wall and the inner wall and the vertical point is H, the inner pipe diameter of the outlet pipe is R, and the distance S is designed in the following mode:

S1>＝a*H+b*((H)²+R²)^(1/2)；

wherein

1.558<c<1.562，

Preferably, a is 3.0, c is 1.550;

preferably, a plurality of flow guide components are arranged on the inner wall of the flue gas pipeline along the flowing direction of the flue gas, and the included angle of A2 is smaller and smaller along the flowing direction of the flue gas. Because the mixing degree of the fluid is better and better along with the continuous movement of the fluid, the included angle needs to be set to be smaller and smaller so as to reduce the flow resistance, and the temperature equalizing effect achieves the basically same effect on the aspects of reducing the resistance and saving the material cost.

Preferably, the included angle a2 increases with decreasing magnitude along the direction of flow of the flue gas. The effect is obtained through a large number of numerical simulation and experimental research results, and the research finds that the rule accords with the rule of fluid motion, and the temperature equalizing effect achieves the basically same effect on the aspects of further reduction of resistance and saving of material cost.

Preferably, along the flowing direction of the flue gas, the inner wall of the flue gas pipeline is provided with a plurality of layers of flow guiding components, and along the flowing direction of the flue gas, the total radian of the arc connecting the flow guiding components and the inner wall on the same layer is smaller and smaller. Because the mixing degree of the fluid is better and better along with the continuous movement of the fluid, the flow space which needs to be arranged is larger and larger so as to reduce the flow resistance, and the temperature equalizing effect achieves basically the same effect on the aspects of reducing the resistance and saving the material cost.

Preferably, the total radian of the arcs connecting the flow guiding parts and the inner wall of the same layer increases along the flowing direction of the smoke. The effect is obtained through a large number of numerical simulation and experimental research results, and the research finds that the rule accords with the rule of fluid motion, and the temperature equalizing effect achieves the basically same effect on the aspects of further reduction of resistance and saving of material cost.

Preferably, a plurality of guide elements are arranged on the inner wall of the flue gas pipeline along the flowing direction of the flue gas, and the included angle of A1 is larger and larger along the flowing direction of the flue gas. Because the mixing degree of the fluid is better and better along with the continuous movement of the fluid, the included angle needs to be set to be larger and larger so as to reduce the size, the flow resistance is reduced, and the temperature equalizing effect achieves the basically same effect on the aspects of reducing the resistance and saving the material cost.

Preferably, the included angle a1 increases with increasing magnitude in the direction of flow of the flue gas. The effect is obtained through a large number of numerical simulation and experimental research results, and the research finds that the rule accords with the rule of fluid motion, and the temperature equalizing effect achieves the basically same effect on the aspects of further reduction of resistance and saving of material cost.

According to the invention, through a large number of experiments and numerical simulation, the minimum design distance of the drainage component is obtained, and the resistance is reduced through the design distance, and meanwhile, the full mixing can be realized. 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.

Claims (5)

1. A boiler system comprises a boiler, wherein a flue gas outlet is formed in the top of the boiler and is connected with a flue, an air preheater, a plurality of coal economizers and a dust remover are sequentially arranged in the flue, the tail end of a flue gas pipeline between the coal economizer and the air preheater is provided with a plurality of flue gas outlets, and each flue gas outlet is respectively connected with one coal economizer; the flue gas preheating device is characterized in that a flow guide component extending from the inner wall of the flue gas pipeline to the center of the flue gas pipeline is arranged in the flue gas pipeline between the economizer and the air preheater, the flow guide component comprises a first straight line wall and a second straight line wall extending from the inner wall, an acute angle formed by the first straight line wall and the inner wall is smaller than an acute angle formed by the second straight line wall and the inner wall, the first straight line wall and the second curved wall extend towards the flow direction of flue gas, the intersection point of the first straight line wall and the second straight line wall is located at the downstream of the joint of the first straight line wall and the inner wall, and is located at the downstream of the joint of the second straight line wall and the inner wall. The shape of the drainage component is a shape formed by rotating the first linear wall, the second linear wall and the inner wall along the axis of the outlet pipe; the flue gas guiding device is characterized in that a plurality of flow guiding components are arranged on the inner wall of the flue gas pipeline along the flowing direction of flue gas, and the included angle of A2 is smaller and smaller along the flowing direction of the flue gas.

2. The boiler system according to claim 1, wherein the included angle a2 is smaller and smaller with increasing magnitude in the direction of flow of the flue gas.

3. The boiler system according to claim 1, wherein a tangent of the first curved wall at the location of the intersection forms an angle of 30-60 ° with the axis of the flue gas duct.

4. The boiler system according to claim 1, wherein the tangent of the first rectilinear wall at the location of the intersection forms an angle of 45 ° with the axis of the flue gas duct.

5. The utility model provides a boiler system, boiler system includes the boiler, the boiler top sets up the exhanst gas outlet, and exhanst gas outlet connects the flue, sets gradually air heater, economizer and dust remover in the flue, and the economizer sets up a plurality ofly, and the end of the flue gas pipeline between economizer and the air heater sets up a plurality of exhanst gas outlets.

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