CN209840140U - Thermodynamic system for improving flue gas temperature at SCR inlet of boiler - Google Patents
Thermodynamic system for improving flue gas temperature at SCR inlet of boiler Download PDFInfo
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- CN209840140U CN209840140U CN201920093612.8U CN201920093612U CN209840140U CN 209840140 U CN209840140 U CN 209840140U CN 201920093612 U CN201920093612 U CN 201920093612U CN 209840140 U CN209840140 U CN 209840140U
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Abstract
The utility model discloses a thermodynamic system for improving boiler SCR entry flue gas temperature, the system includes low temperature over heater, economizer, at least one bypass flue, main road flue, bypass flue shutoff baffle, bypass flue adjusting baffle, main road flue and bypass flue set up in boiler steering room side by side; in the flue gas flow, the low-temperature superheater and the economizer are sequentially arranged in the main path flue; the bypass flue shutoff baffle and the bypass flue adjusting baffle are sequentially arranged in the bypass flue; the main path flue adjusting baffle is arranged in the main path flue and is in front of a mixing point of the bypass flue and the main path flue; the high-temperature flue gas at the outlet of the bypass flue and the low-temperature flue gas at the outlet of the main flue are mixed, so that the temperature of the flue gas at the inlet of the SCR is increased. The utility model discloses utilize the flue gas bypass to promote SCR entry flue gas temperature, flue gas temperature promotes obviously, and the reaction is quick.
Description
Technical Field
The utility model relates to a boiler environmental protection field, concretely relates to coal fired boiler SCR denitrification facility entry flue gas promotes's thermodynamic system, through from boiler back chimney shaft to the room extraction high temperature flue gas mix to economizer export low temperature flue gas in to realize promoting SCR denitrification facility entry flue gas temperature.
Background
Along with the stricter environmental protection policy, the stricter requirements on the pollutant emission of the thermal power generating unit are provided, and the desulfurization and denitrification devices are sequentially added to the coal-fired unit, SO that the thermal power generating unit can realize SO in the operation process2And NOxAchieves great performance in the power industry and other industriesPlays a pioneer demonstration role. For large boilers, to control NOxThe method is characterized in that a denitration device is often installed, particularly, the Selective Catalytic Reduction (SCR) technology is widely applied, the SCR denitration device is installed between an economizer and an air preheater of a boiler, and NO generated in the combustion process of the boiler is realizedxCarrying out a metathesis reaction to produce N2And H2O。
The SCR denitration reaction requires a certain range, and for the current mainstream SCR catalyst, the temperature range of the flue gas at the inlet of the SCR denitration device is generally required to be maintained at 400 ℃ in consideration of the denitration reaction activity and the service life of the catalyst. However, due to the influence of structural characteristics and load variation characteristics of the coal-fired boiler, along with the reduction of unit load, the flue gas temperature at the outlet of the economizer, namely the flue gas temperature at the inlet of the SCR, can be gradually reduced until the flue gas temperature is lower than 300 ℃, so that the normal operation of the SCR denitration device is influenced, and the NO of the boiler under low load can be causedxThe emission concentration exceeds the standard, and the environmental protection emission requirement cannot be met.
At present, the power supply situation of China is in a over-demand condition, with the increasing increase of new energy installation and the enhancement of environmental awareness, the annual utilization hours of thermal power are reduced year by year, a coal-fired power unit can be normalized when running for a long time under low load, and particularly for the coal-fired thermal power unit participating in deep peak shaving of a power grid, a boiler needs to run under low load for a long time, so that the temperature of SCR inlet flue gas is difficult to meet the requirement of a temperature interval.
For the coal-fired boiler, especially when the moisture of the coal entering the boiler is high, the water vapor content in the flue gas is high, the flue gas is large and is difficult to cool, especially when the load is low, the heat exchange temperature difference is small, the flue gas temperature can be reduced only by needing a large heat exchange area, and similarly, the same flue gas temperature is increased, and the required heat is high. In addition, when the load of the boiler is low, partial boiler heat is transferred to the air preheater by increasing the temperature of flue gas at the SCR inlet, the temperature of hot air is increased, and low-temperature corrosion of the air preheater is reduced.
Therefore, the temperature of the flue gas at the SCR inlet of the coal-fired boiler is increased under low load, and the normal operation of the SCR denitration device is solved.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a thermodynamic system for improving coal fired boiler SCR denitrification facility entry flue gas temperature through turning to the low temperature flue gas that the chamber position extracted part high temperature flue gas at the boiler, exports with the economizer and mixes to promote SCR entry flue gas temperature, realize the boiler SCR denitrification facility's when the low-load operation normal operation.
In order to achieve the purpose, a thermodynamic system for improving the temperature of flue gas at an SCR inlet of a boiler is provided, and the specific technical scheme is as follows: the system comprises a low-temperature superheater (4), an economizer (5), at least one bypass flue (12), a main flue (20), a bypass flue shutoff baffle (9), a bypass flue adjusting baffle (10) and a main flue adjusting baffle (7), wherein the main flue and the bypass flue are arranged at a boiler turning chamber in parallel; in the flue gas flow, the low-temperature superheater (4) and the economizer (5) are sequentially arranged in the main path flue; in the flue gas flow, the bypass flue shutoff baffle (9) and the bypass flue adjusting baffle (10) are sequentially arranged in the bypass flue (12); the main path flue adjusting baffle (7) is arranged in the main path flue and is in front of a mixing point of the bypass flue (12) and the main path flue;
the high-temperature flue gas at the outlet of the bypass flue and the low-temperature flue gas at the outlet of the main flue are mixed, so that the temperature of the flue gas at the inlet of the SCR is increased.
In order to enable the boiler to have the adjusting capacity of improving the temperature of the flue gas at the SCR inlet in a larger load range, the extracted high-temperature flue gas bypasses the low-temperature superheater and the economizer, so that the flow of the flue gas in a bypass flue is smaller when the boiler operates at low load, and the influence on the main tail convection heating surface of the boiler body is reduced.
The bypass flue shutoff baffle is arranged in the vertical direction and is close to a flue gas suction opening of a flue gas well behind a boiler, so that the fault caused by dust deposition when the flue gas bypass is not put into use is prevented, the size of a high-temperature-resistant flue can be reduced, the construction cost is reduced, the baffle is used for controlling the operation or quitting of the bypass flue, the tightness after the bypass flue is closed is critical to the influence of the boiler performance, especially, the leaked flue gas quantity of the bypass flue is reduced under high load, and the influence on the flue gas temperature of an SCR inlet and the flue gas temperature of the boiler can be reduced.
The bypass flue adjusting baffle is arranged at the vertical section of the bypass flue, is arranged in the horizontal direction and is used for adjusting the resistance of the bypass flue, and is matched with the main flue adjusting baffle to adjust the flue gas flow distribution in the two parallel flue gas loops, so that the bypass high-temperature flue gas flow is controlled, and the aim of improving the flue gas temperature at the SCR inlet is fulfilled.
The bypass flue is not provided with a heating surface, but resistance elements such as a vertical interface, an elbow, a baffle, an adjusting baffle and the like exist in the bypass flue, theoretically, the resistance of the bypass flue is smaller than that of the main flue, but in order to adjust various resistance characteristics, two adjusting baffles are respectively arranged, so that the inherent resistance characteristics of the equipment can be more flexibly utilized, the capacity of changing the resistance characteristics by using the adjusting baffles is also provided, the resistance characteristics between the main flue and the bypass are changed, and the flow distribution of the main flue and the bypass is adjusted. For a parallel loop system, the resistances between front and rear nodes are the same, the flow rates are different, and the relation of P equals to SQ2, wherein P is the resistance and Pa; s is a resistance coefficient; q is the flue gas flow, m3/s。
As a preferable scheme, the system further comprises a bypass flue horizontal expansion joint (8), a bypass flue vertical expansion joint (11) and a main flue expansion joint (6), wherein the bypass flue horizontal expansion joint (8) is arranged at a horizontal section at the joint of the bypass flue and the boiler steering chamber, the bypass flue vertical expansion joint (11) is arranged at a vertical section of the bypass flue, and the main flue expansion joint (6) is arranged on the horizontal flue at the outlet of the economizer.
Considering the expansion of the boiler body and the expansion of the bypass flue, a horizontal expansion joint is arranged at a horizontal section at the interface of the bypass flue and the boiler steering chamber and is used for absorbing the expansion amount between the boiler rear smoke well and the bypass flue along the depth direction of the boiler in a thermal state; a vertical expansion joint is arranged at the vertical section of the bypass flue and is used for absorbing the expansion amount of the bypass flue in the vertical direction under the thermal state; an expansion joint is arranged on a horizontal flue at the outlet of the economizer to absorb the expansion amount of a flue at the tail part of the boiler in the vertical direction and along the depth direction of the boiler.
The main path flue adjusting baffle is arranged behind an expansion joint of a main path flue at the outlet of the economizer and in front of a cross junction point of the main path flue and the bypass flue and is arranged in a vertical direction.
Preferably, the bypass flue horizontal expansion joint (8), the bypass flue vertical expansion joint (11) and the main flue expansion joint (6) are high-temperature-resistant non-woven expansion joints.
As a preferable scheme, a flue gas temperature measuring point is arranged on the bypass flue and is arranged between the bypass flue shutoff baffle and the bypass flue adjusting baffle. And a smoke temperature measuring point is arranged on the main path flue and is arranged between the rear smoke well economizer and the main path flue expansion joint.
And a smoke temperature measuring point is arranged on the vertical flue of the SCR inlet and is arranged above the ammonia injection grid.
As a preferred scheme, the system comprises two bypass flues, wherein the two bypass flues are arranged in the width direction of the boiler and symmetrically arranged on the left side and the right side, a bypass flue shutoff baffle and a bypass flue adjusting baffle are sequentially arranged on the flue gas flow and are respectively connected with the left horizontal flue and the right horizontal flue of the economizer outlet, and a main flue adjusting baffle is arranged on the horizontal flue of the economizer outlet.
As a preferable scheme, the main path flue adjusting baffle keeps a gap of at least 1000mm in the height direction from the bottom of the main path flue, that is, after the adjusting baffle is closed, the main path also keeps a flow area of at least 1000mm, so that normal flow and dust deposition in the main path flue are ensured not to influence the normal switching operation of the adjusting baffle.
As a preferred scheme, the boiler is loaded at a second load critical point b and above, and the main flue adjusting baffle is in a full-open state; when the boiler load is lower than a second critical point b and higher than a first load critical point a, the main flue adjusting baffle is in a closed state; when the load of the boiler is lower than a first load critical point a, the opening of the main flue adjusting baffle is not lower than a critical opening fixed value;
when the boiler is under the load of a fourth load critical point d and above, the bypass flue shutoff baffle is in a closed state, and the bypass flue adjusting baffle is in a closed state; when the boiler load is lower than a fourth critical point and higher than a third load critical point c, the bypass flue shutoff baffle is in an open state, the bypass flue adjusting baffle is in a gradually-opened state, and the bypass flue adjusting baffle is in a fully-opened state at the load below the third load critical point c;
the first critical load point a, the second critical load point b, the third critical load point c and the fourth critical load point d are determined through the temperature rising characteristic of the bypass flue gas system for operation in a thermal state.
The thermodynamic method of the thermodynamic system for improving the temperature of the flue gas at the SCR inlet of the boiler comprises the following steps:
the opening f of the main flue adjusting baffle1(x) There is a functional correspondence with the boiler load x:
wherein, c1The critical opening fixed value of the regulating baffle is a constant and needs to be optimized and determined in a subsequent thermal state test;
the method specifically comprises the following steps: when the boiler is at the second load critical point b and above, the main flue adjusting baffle is fully opened, so that the resistance of the boiler to the system is reduced; when the load of the boiler is lower than a second critical point b and higher than a first load critical point a, the main path flue adjusting baffle is closed to be small, the resistance of a main path flue gas system is increased, and the flow rate of flue gas of a bypass flue is improved; when the boiler load is lower than the first load critical point a, the opening of the main flue adjusting baffle is not lower than a critical opening fixed value c1；
Opening f of the bypass flue adjusting baffle2(x) There is a functional correspondence with the boiler load x:
the method specifically comprises the following steps: when the boiler is under the fourth load critical point d and above, the bypass flue shutoff baffle is closed, and the bypass flue adjusting baffle is closed; and when the boiler load is lower than the fourth critical point d and higher than the third load critical point c, opening the bypass flue shutoff damper and gradually opening the bypass flue adjusting damper along with the reduction of the boiler load, wherein the bypass flue adjusting damper is fully opened at the third load critical point c and below.
The critical opening degree fixed value needs to be determined through the result of a load change test carried out by the boiler, is related to factors such as the coal quality of the boiler, the water supply temperature and the operation mode of a combustion system, needs to be optimized and determined regularly, ensures the reliable investment of a flue gas bypass system, realizes the controllable flue gas temperature at the SCR inlet, and can reduce the resistance of a main flue gas system to the maximum extent.
The first critical load point a, the second critical load point b, the third critical load point c and the fourth critical load point d are determined by the temperature rise characteristic of the bypass flue gas system in the thermal state, and parameters can be further optimized and adjusted during operation.
The first critical load point a, the second critical load point b, the third critical load point c and the fourth critical load point d are load points which need to be tested, adjusted, optimized and confirmed in a thermal state, and after test setting, a person skilled in the art can basically determine the numerical values of a, b, c and d, and then set the values in DCS logic to realize open-loop control of the two adjusting baffles.
The main flue adjusting baffle and the bypass flue adjusting baffle can be put into an automatic operation mode after being optimized and parameter-set, the control mode is open-loop control, the opening degrees of the two adjusting baffles are only related to the load of the boiler, frequent adjustment and frequent actions of the adjusting baffles during the operation of a bypass flue gas system are reduced, the reliability of the system is improved, and the workload of maintenance and repair is reduced. The two baffles are associated, the adjustment of the bypass adjusting baffle is used as a main means for controlling the temperature of the flue gas at the SCR inlet, the main path baffle is used as a matching adjusting baffle, and the main path baffle is mainly used for changing the resistance of a parallel loop of a main path flue and a rear smoke well, so that a condition is created for the adjustment of the bypass adjusting baffle, namely if the bypass baffles are completely opened, the temperature of the flue gas still cannot meet the requirement, the bypass flue gas flow is low, the main path flue adjusting baffle needs to be reduced, and the main path resistance is increased, so that the bypass flue can improve the flow; in addition, when the opening degree of the bypass flue is adjusted to be smaller, the requirement of the SCR inlet smoke temperature can be met, and then the main path baffle plate needs to be opened properly, so that the resistance of a main smoke system of the boiler is reduced, and the energy conservation is realized.
After the bypass flue is put into operation, the ratio x of the flue gas flow to the total amount of the flue gas at the SCR inlet is (t)3-t2)/(t1-t2) Wherein, t1The temperature of the flue gas in the bypass flue is DEG C; t is t2The flue gas temperature in the main flue is DEG C; t is t3Is the temperature of the flue gas in the vertical flue of the SCR inlet at the temperature of DEG C.
The beneficial effects of the utility model reside in that:
1) the flue gas temperature at the inlet of the SCR is increased by utilizing the flue gas bypass, the flue gas temperature is obviously increased, and the reaction is quick; 2) by pumping high-temperature flue gas which does not pass through the low-temperature superheater and the economizer, the flow of bypass flue gas can be reduced, and the load adjustment range of wide load and small denitration of the boiler is increased; 3) the main flue is provided with the adjusting baffle, so that the flexibility of the bypass flue for adjusting the flow of high-temperature flue gas is enhanced, and the main flue is suitable for the operation of the boiler under different loads; 4) the main flue adjusting baffle and the bypass flue adjusting baffle are both controlled by open loops, and the opening degrees of the main flue adjusting baffle and the bypass flue adjusting baffle are only related to the load of the boiler, so that the control measurement is simplified, the action frequency of the adjusting baffles is reduced, and the operation reliability is improved; 5) the bypass flue gas flow ratio can be indirectly calculated by adopting the temperature detection before and after the flue gas is mixed, so that the operation and adjustment are convenient.
Drawings
FIG. 1 is a front view of the thermodynamic system for increasing the temperature of boiler SCR inlet flue gas of the present invention;
FIG. 2 is a top view of the bypass flue and the rear flue for increasing the flue gas temperature at the SCR inlet of the boiler of the present invention;
FIG. 3 is a schematic view of the arrangement of the temperature measuring points of the thermodynamic system for increasing the flue gas temperature at the SCR inlet of the boiler;
FIG. 4 is a diagram showing the relationship between the opening of the main flue damper and the boiler load according to the present invention;
FIG. 5 is a diagram showing the relationship between the opening of the bypass flue damper and the boiler load according to the present invention;
description of reference numerals:
1. a boiler; 2. a diversion chamber; 3. a rear smoke well; 4. a low temperature superheater; 5. a coal economizer; 6. a main path flue expansion joint; 7. a main path flue adjusting baffle; 8. a bypass flue horizontal expansion joint; 9. a bypass flue shutoff baffle; 10. a bypass flue adjusting baffle; 11. a bypass flue vertical expansion joint; 12. a bypass flue; 13, SCR inlet vertical flue; an SCR reactor; 15. an air preheater; 16. measuring a bypass flue gas temperature point; 17. measuring a smoke temperature point at the outlet of the economizer; measuring the temperature of the SCR inlet smoke; 19. an ammonia injection grid; 20. and a main flue.
Detailed Description
The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings. It should be noted that the embodiments and technical features thereof may be combined with each other in the case where there is no conflict.
As shown in attached figures 1 and 2, a high-temperature flue gas extraction opening is formed in a turning chamber 2 at the upper part of a rear smoke well 3 of a boiler 1, a heating surface is not arranged in the area of the turning chamber 2, and a low-temperature superheater 4 and an economizer 5 are sequentially arranged at the lower part of the turning chamber 2. A bypass flue 12 is arranged in the steering chamber 2, low-temperature flue gas at the outlets of the low-temperature superheater 4 and the economizer 5 is mixed with high-temperature flue gas passing through the bypass flue 12, the flue gas temperature is raised, the flue gas sequentially passes through an ammonia injection grid 19 and an SCR inlet vertical flue 13, the flue gas after temperature raising enters an SCR reactor 14, and the flue gas after denitration reaction enters an air preheater 15.
For a large boiler, two bypass flues 12 are arranged in the width direction of the boiler 1 and symmetrically arranged on the left side and the right side, so that the follow-up processes of ammonia spraying mixing, denitration, flowing through an air preheater and the like are met.
A bypass flue horizontal expansion joint 8 and a bypass flue shutoff baffle 9 are sequentially arranged on a horizontal flue in the joint area of a bypass flue 12 and a steering chamber 2 along the flue gas flow, the bypass flue horizontal expansion joint 8 is close to a boiler body part and used for absorbing the relative expansion amount between a rear smoke well 3 and the bypass flue 12 in a thermal state, the bypass flue shutoff baffle 9 is arranged on the horizontal flue and used for reducing the influence of fly ash on the bypass flue after the bypass flue 12 is stopped, the baffle is used for controlling the flow of the flue gas in the bypass flue, the tightness of the baffle is important for preventing the leakage of the bypass flue 12, when the bypass flue 12 is put into operation, the bypass flue shutoff baffle 9 is required to be opened firstly, when the bypass flue 12 is withdrawn from operation, the bypass flue shutoff baffle 9 is required to be closed, and the high-temperature flue gas bypass rear smoke well 3 is.
A bypass flue adjusting baffle 10 and a bypass flue vertical expansion joint 11 are sequentially arranged on a vertical section of a bypass flue 12, and the bypass flue vertical expansion joint is arranged in a region close to a main flue and is used for absorbing the expansion amount between the bypass flue 12 and the main flue in a thermal state. The bypass flue adjusting baffle 10 is used for controlling bypass flue gas flow in the bypass flue 12, when the bypass flue 12 quits operation, the bypass flue adjusting baffle 10 is required to be closed, when the bypass flue 12 is put into operation, the bypass flue gas flow is increased along with the increase of the opening degree of the bypass flue adjusting baffle 10, and the improvement capability of the SCR inlet flue gas temperature is enhanced.
A main flue expansion joint 6 and a main flue adjusting baffle 7 are sequentially arranged on a main flue 20 at the outlet of the economizer 5, the main flue expansion joint 6 and the main flue adjusting baffle 7 are arranged in front of the mixing point of a bypass flue 12 and the main flue, wherein the main flue expansion joint 6 is used for absorbing the expansion amount between the back smoke well 3 and the main flue in a thermal state, the main flue adjusting baffle 7 is used for adjusting the flow resistance of the main flue, the adjustment change of the baffle is matched to realize the adjustment of the high-temperature smoke flow in the bypass flue 12, namely, when the main flue adjusting baffle 7 is turned off, the flow resistance of a main flue system is increased, the smoke suction capacity of the bypass flue 12 is improved, the rise range of the SCR inlet smoke temperature is increased, when the opening degree of the main flue adjusting baffle 7 is turned on, the flow resistance of the main flue is reduced, and the smoke suction capacity of the bypass flue 12 is reduced, and the amplitude for improving the temperature of the flue gas at the SCR inlet is reduced.
As shown in fig. 3, a bypass flue temperature measuring point 16 is arranged between the bypass flue shutoff damper 9 and the bypass flue adjusting damper 10, and is used for detecting the temperature of high-temperature flue gas flowing through the bypass and indirectly measuring the flue gas flow ratio in the bypass.
As shown in fig. 3, an economizer outlet flue gas temperature measuring point 17 is arranged between the main flue expansion joint 6 and the economizer 5, and is used for measuring and monitoring the economizer outlet flue gas temperature and further judging whether the bypass flue is put into operation.
As shown in fig. 3, an SCR inlet flue gas temperature measuring point 18 is disposed between the ammonia injection grid 19 and the SCR reactor 14, and is used for measuring the SCR inlet flue gas temperature and further judging whether the bypass flue 12 leaks.
By utilizing the mass and energy balance principle in the mixing process of mixing two flue gases to generate a third flue gas, the ratio of the flue gas flow in the bypass flue 12 to the total flow of the flue gas at the SCR inlet can be calculated: x ═ t3-t2)/(t1-t2) Wherein, t1The temperature of the flue gas in the bypass flue is DEG C; t is t2The flue gas temperature in the main flue is DEG C; t is t3Is the temperature of the flue gas in the vertical flue of the SCR inlet at the temperature of DEG C.
The bypass flue adjusting baffle 10 and the main flue adjusting baffle 7 both adopt an open-loop control strategy, frequent actions of the two adjusting baffles due to closed-loop control are reduced, the reliability of system operation is improved, and maintenance workload is reduced, the opening degrees of the two baffles are both related to boiler load, the control relation curves of the two baffles are shown in fig. 4 and 5, in order to ensure that a channel of a boiler flue air system is not interrupted, the opening degree of the main flue adjusting baffle is required to be not lower than a certain critical value, such as 30%, and at least 1000mm of gap is reserved at the bottom of the main flue adjusting baffle 7, so that boiler accidents are prevented from being caused by complete closing of the whole flue gas circulation loop.
For the four critical load points between the boiler load and the opening degrees of the main path adjusting baffle 7 and the bypass adjusting baffle 10, a debugging test needs to be performed according to the boiler load and the flue gas temperature characteristic after the system is put into operation, generally, after a thermal state optimization test is performed, the curves shown in fig. 4 and 5 can be made into a DCS control logic, and the DCS control logic can be used for controlling the changes of the two adjusting baffles after being updated. Wherein, a, b, c, d in fig. 4 and 5 represent a critical load point, a second critical load point, a third critical load point and a fourth critical load point, respectively. As can be seen in fig. 4 and 5: the first critical load point a is 30%, the second critical load point b is 60%, the third critical load point c is 30%, and the fourth critical load point d is 50%.
The four critical load points are the adjusting control curves according to fig. 4 and 5, and two adjusting baffles are limited or fully opened at each load point; for one boiler, the four critical load points are determined after thermal state test and optimized operation and are modified into DCS control logic. The final objective is: the action frequency of the two adjusting baffles is reduced, and the reliability is improved; in addition, the overall resistance of the flue gas system is reduced as much as possible, and energy conservation is realized; and the two baffles have certain adjustment allowance, so that the boiler can adapt to certain external changes, such as fuel and operation condition changes, and the bypass flue still has the capability of being put into automatic operation.
Claims (8)
1. A thermodynamic system for increasing the temperature of flue gas at the SCR inlet of a boiler, the system comprises a low-temperature superheater (4), an economizer (5), at least one bypass flue (12), a main flue (20), a bypass flue shutoff baffle (9), a bypass flue adjusting baffle (10) and a main flue adjusting baffle (7), and is characterized in that the main flue and the bypass flue are arranged in parallel at a boiler turning chamber; in the flue gas flow, the low-temperature superheater (4) and the economizer (5) are sequentially arranged in the main path flue; in the flue gas flow, the bypass flue shutoff baffle (9) and the bypass flue adjusting baffle (10) are sequentially arranged in the bypass flue (12); the main path flue adjusting baffle (7) is arranged in the main path flue and is in front of a mixing point of the bypass flue (12) and the main path flue;
the high-temperature flue gas at the outlet of the bypass flue and the low-temperature flue gas at the outlet of the main flue are mixed, so that the temperature of the flue gas at the inlet of the SCR is increased.
2. The thermodynamic system for increasing boiler SCR inlet flue gas temperature according to claim 1, further comprising a bypass flue horizontal expansion joint (8), a bypass flue vertical expansion joint (11) and a main flue expansion joint (6), the bypass flue horizontal expansion joint (8) being arranged in a horizontal section at the bypass flue to boiler turn room interface, the bypass flue vertical expansion joint (11) being arranged in a vertical section of the bypass flue, the main flue expansion joint (6) being arranged on the economizer outlet horizontal flue.
3. The thermodynamic system for increasing boiler SCR inlet flue gas temperature according to claim 2, wherein the bypass flue horizontal expansion joint (8), the bypass flue vertical expansion joint (11) and the main flue expansion joint (6) all employ high temperature resistant non-woven fabric expansion joints.
4. The thermodynamic system for increasing boiler SCR inlet flue gas temperature according to claim 1, further comprising a bypass flue gas temperature measurement point (16) and an economizer outlet flue gas temperature measurement point (17);
the bypass flue gas temperature measuring point (16) is arranged between the bypass flue shutoff baffle and the bypass flue adjusting baffle; and the economizer outlet smoke temperature measuring point (17) is arranged at the economizer outlet.
5. The thermodynamic system for increasing the temperature of boiler SCR inlet flue gas according to claim 1, wherein the system comprises two bypass flues, and the two bypass flues are arranged in the width direction of the boiler and symmetrically arranged on the left side and the right side.
6. Thermodynamic system for increasing boiler SCR inlet flue gas temperature according to claim 1, characterized in that the main flue regulation damper (7) leaves a gap of at least 1000mm in height direction from the main flue bottom.
7. Thermodynamic system for increasing boiler SCR inlet flue gas temperature according to claim 1, characterised in that both the bypass flue regulation damper (10) and the main flue regulation damper (7) are open loop controlled.
8. The thermodynamic system for increasing the temperature of boiler SCR inlet flue gas according to claim 1, wherein the main flue damper is fully open when the boiler is loaded at or above the second load critical point b; when the boiler load is lower than a second critical point b and higher than a first critical load point a, the main flue adjusting baffle is in a closed state; when the load of the boiler is lower than a first load critical point a, the opening of the main flue adjusting baffle is not lower than a critical opening fixed value;
when the boiler is under the fourth load critical point d and above, the bypass flue shutoff damper is in a closed state, and the bypass flue adjusting damper is in a closed state; when the boiler load is lower than a fourth critical point and higher than a third load critical point c, the bypass flue shutoff baffle is in an open state, the bypass flue adjusting baffle is in a gradually-opened state, and the bypass flue adjusting baffle is in a fully-opened state at the load below the third load critical point c;
the first critical load point a, the second critical load point b, the third critical load point c and the fourth critical load point d are determined through the temperature rising characteristic of the bypass flue gas system for operation in a thermal state.
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| CN111450700A (en) * | 2020-05-12 | 2020-07-28 | 西安热工研究院有限公司 | Wide load denitration of boiler and improvement wind temperature integration system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111450700A (en) * | 2020-05-12 | 2020-07-28 | 西安热工研究院有限公司 | Wide load denitration of boiler and improvement wind temperature integration system |
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