CN212618239U - Boiler structure for avoiding low-temperature corrosion of heating surface at tail of boiler - Google Patents
Boiler structure for avoiding low-temperature corrosion of heating surface at tail of boiler Download PDFInfo
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- CN212618239U CN212618239U CN202021697987.4U CN202021697987U CN212618239U CN 212618239 U CN212618239 U CN 212618239U CN 202021697987 U CN202021697987 U CN 202021697987U CN 212618239 U CN212618239 U CN 212618239U
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Abstract
The utility model discloses an avoid boiler structure of boiler afterbody heating surface low temperature corrosion, including air heater and flue gas cooler, air heater installs in duct system, duct system is located outside the boiler, flue gas cooler is located boiler afterbody flue, duct system with boiler afterbody flue intercommunication. The utility model discloses make metal surface wall temperature be higher than low temperature corrosion's highest temperature, avoid the SO in the flue gas2With water vapour to form H2SO3After being fused with water vapor in the flue gas, the water vapor is condensed on the pipe wall to generate acidAnd (4) corrosive corrosion.
Description
Technical Field
The utility model relates to an avoid boiler afterbody to receive boiler structure of hot side low temperature corrosion belongs to power plant boiler technical field.
Background
A traditional 130t/h high-temperature high-pressure boiler tubular air preheater is arranged at an outlet of an economizer, smoke transversely scours the outer surface of a pipeline of the air preheater, heated air is pressurized by a blower and circulates in the pipeline, and hot air enters a boiler for combustion supporting through a primary hot air system and a secondary hot air system after the heat of the smoke is transferred to the air. However, the working medium temperature of the heated surface at the tail part of the boiler is often lower, and SO in the flue gas2With water vapour to form H2SO3And the water vapor in the flue gas is condensed on the pipe wall after being fused with the water vapor in the flue gas, so that the acidic corrosion is generated.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide an avoid boiler afterbody to receive boiler structure of hot side low temperature corrosion for metal surface wall temperature is higher than low temperature corrosion's the highest temperature, avoids the SO in the flue gas2With water vapour to form H2SO3And the water vapor in the flue gas is condensed on the pipe wall after being fused with the water vapor in the flue gas, so that the acidic corrosion is generated.
In order to solve the technical problem, the utility model discloses a following technical scheme:
a method for avoiding low-temperature corrosion of a heated surface at the tail part of a boiler comprises the following steps: controlling the working medium temperature of the heated surface at the tail of the boiler to ensure that the wall temperature of the metal surface of the heated surface at the tail of the boiler is higher than the highest temperature of low-temperature corrosion, and preventing SO in flue gas2With water vapour to form H2SO3And the water vapor in the flue gas is condensed on the pipe wall after being fused with the water vapor in the flue gas, so that the acidic corrosion is generated.
In the method for avoiding low-temperature corrosion of the heated surface at the tail of the boiler, the following method is adopted for controlling the temperature of the working medium at the heated surface at the tail of the boiler: and carrying out heat balance calculation on the heated surface at the tail part of the boiler, and controlling a water supply system, an air supply system and a flue gas system of the boiler to ensure that the wall temperature of the metal surface of the heated surface at the tail part of the boiler is higher than the highest temperature of low-temperature corrosion.
The utility model provides a avoid boiler structure of boiler afterbody heating surface low temperature corrosion, includes air heater and flue gas cooler, air heater installs in air duct system, air duct system is located outside the boiler, flue gas cooler is located boiler afterbody flue, air duct system with boiler afterbody flue intercommunication. Combustion-supporting air is needed for boiler combustion, and in order to ensure the thermal efficiency of the boiler, the combustion-supporting air is generally heated to a certain temperature (about 197 ℃) and then is fed into a hearth. The air preheater is arranged in the air duct system and heats cold air into hot air, and the air duct system conveys primary hot air and secondary hot air to the boiler for supporting combustion.
In the boiler structure for avoiding low-temperature corrosion of the heating surface of the tail part of the boiler, the flue gas cooler comprises a first flue gas cooler, a second flue gas cooler, a third flue gas cooler, a fourth flue gas cooler and a fifth flue gas cooler which are sequentially connected in series along the water supply circulation direction, the water inlet of the flue gas cooler is positioned on the first flue gas cooler, and the water outlet of the flue gas cooler is positioned on the fifth flue gas cooler.
In the boiler structure for avoiding the low-temperature corrosion of the heated surface at the tail part of the boiler, the first economizer and the second economizer are sequentially arranged at the downstream of the fifth flue gas cooler in the flue at the tail part of the boiler.
In the above boiler structure for avoiding low-temperature corrosion of the heated surface at the tail of the boiler, the tubes in the air preheater are spiral fin tubes, the spiral fin tubes are perpendicular to the air circulation direction in the air preheater, the spiral fin tubes are arranged in rows, and two adjacent rows of spiral fin tubes are arranged in a staggered manner.
In the foregoing boiler structure for preventing low-temperature corrosion of the heated surface at the tail of the boiler, the water flow rate in the pipeline in the air preheater is 1-2m/S, and the air flow rate in the air preheater is 7.5 m/S.
In the boiler structure for avoiding low-temperature corrosion of the heating surface at the tail part of the boiler, the flue gas cooler comprises the finned coiled tube panel, a supporting plate and an inner protecting plate, the finned coiled tube panel is arranged on the supporting plate, the inner protecting plate is positioned around the finned coiled tube panel, and the exhaust gas temperature of the boiler is 134 ℃.
Compared with the prior art, the utility model discloses make metal surface wall temperature be higher than low temperature corrosion's highest temperature, avoid the SO in the flue gas2With water vapour to form H2SO3Condensed after being fused with water vapor in the smokeOn the pipe wall, acidic corrosion occurs. The boiler structure that this patent provided has following advantage: 1. the original air preheater system is changed, so that the original direct convection heat exchange between the flue gas and the air is changed into the heat exchange between boiler feed water and cold air and the heat exchange between high-temperature flue gas and cooled boiler feed water; 2. the air preheater is arranged in an air duct system outside the boiler, and the economizer flue gas outlet area is provided with a 5-stage flue gas cooler. The flue gas cooler adopts a phi 38x4 coiled pipe and is arranged in line along the flow direction of flue gas. 3. The air preheater adopts phi 38x4 serpentine tubes, which are staggered along the cold air flow direction. 4. The serpentine pipelines of the flue gas cooler and the air preheater both adopt finned tubes, so that the heating surface of the pipeline can be increased, and the material consumption of the pressurized pipeline is saved.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic view of the internal structure of the back pass of the boiler;
FIG. 3 is a schematic diagram of an air preheater;
FIG. 4 is a cross-sectional view of section A-A of FIG. 3;
FIG. 5 is a piping diagram of boiler feed water.
Reference numerals: 1-a boiler tail flue, 2-an air duct system, 3-an air preheater, 4-a first flue gas cooler, 5-a second flue gas cooler, 6-a third flue gas cooler, 7-a fourth flue gas cooler, 8-a fifth flue gas cooler, 9-a first economizer, 10-a second economizer, 11-a water outlet of the flue gas cooler, 12-a water inlet of the flue gas cooler, 13-a spiral fin pipe, 14-an inner protection plate and 15-a support plate.
The present invention will be further described with reference to the accompanying drawings and the detailed description.
Detailed Description
A method for avoiding low-temperature corrosion of a heated surface at the tail part of a boiler comprises the following steps: controlling the working medium temperature of the heated surface at the tail of the boiler to ensure that the wall temperature of the metal surface of the heated surface at the tail of the boiler is higher than the highest temperature of low-temperature corrosion, and preventing SO in flue gas2With water vapour to form H2SO3After being fused with water vapor in the flue gas, the mixed gas is condensed on the pipe wallIn addition, acidic corrosion occurs. The following method is adopted for controlling the working medium temperature of the heating surface at the tail part of the boiler: and carrying out heat balance calculation on the heated surface at the tail part of the boiler, and controlling a water supply system, an air supply system and a flue gas system of the boiler to ensure that the wall temperature of the metal surface of the heated surface at the tail part of the boiler is higher than the highest temperature of low-temperature corrosion.
The heat balance calculation of the heating surface at the tail part of the boiler and the power method of the water supply system, the air supply system and the flue gas system by calculation can refer to the following table:
accessory 1130 t/h high-temperature high-pressure boiler air preheater system thermodynamic calculation
TABLE 1 FGC Nos. 5-3
TABLE 2 FGC-2
TABLE 3 FGC-1
TABLE 4 Water heating air preheater
Example 1: the utility model provides a avoid boiler structure of boiler afterbody heating surface low temperature corrosion, includes air heater 3 and flue gas cooler, air heater 3 installs in air duct system 2, air duct system 2 is located outside the boiler, the flue gas cooler is located the boiler afterbody flue, air duct system 2 with boiler afterbody flue intercommunication. The flue gas cooler comprises a first flue gas cooler 4, a second flue gas cooler 5, a third flue gas cooler 6, a fourth flue gas cooler 7 and a fifth flue gas cooler 8 which are sequentially connected in series along the water supply circulation direction, a water inlet 12 of the flue gas cooler is positioned on the first flue gas cooler 4, and a water outlet 11 of the flue gas cooler is positioned on the fifth flue gas cooler 8.
And a first coal economizer 9 and a second coal economizer 10 are sequentially arranged at the downstream of a fifth flue gas cooler 8 in the tail flue of the boiler. The air preheater 3 is characterized in that the pipelines in the air preheater 3 are spiral fin tubes 13, the spiral fin tubes 13 are perpendicular to the air circulation direction in the air preheater 3, the spiral fin tubes 13 are arranged in rows, and two adjacent rows of spiral fin tubes 13 are arranged in a staggered mode.
Example 2: the utility model provides a avoid boiler structure of boiler afterbody heating surface low temperature corrosion, includes air heater 3 and flue gas cooler, air heater 3 installs in air duct system 2, air duct system 2 is located outside the boiler, the flue gas cooler is located the boiler afterbody flue, air duct system 2 with boiler afterbody flue intercommunication. The flue gas cooler comprises a first flue gas cooler 4, a second flue gas cooler 5, a third flue gas cooler 6, a fourth flue gas cooler 7 and a fifth flue gas cooler 8 which are sequentially connected in series along the water supply circulation direction, a water inlet 12 of the flue gas cooler is positioned on the first flue gas cooler 4, and a water outlet 11 of the flue gas cooler is positioned on the fifth flue gas cooler 8.
And a first coal economizer 9 and a second coal economizer 10 are sequentially arranged at the downstream of a fifth flue gas cooler 8 in the tail flue of the boiler. The air preheater 3 is characterized in that the pipelines in the air preheater 3 are spiral fin tubes 13, the spiral fin tubes 13 are perpendicular to the air circulation direction in the air preheater 3, the spiral fin tubes 13 are arranged in rows, and two adjacent rows of spiral fin tubes 13 are arranged in a staggered mode. The water flow rate in the tubes in the air preheater 3 is 1-2m/S and the air flow rate in the air preheater 3 is about 7.5 m/S. The flue gas cooler comprises a finned coiled tube panel, a support plate 1 and an inner guard plate 14, wherein the finned coiled tube panel is arranged on the support plate 1, the inner guard plate 14 is positioned around the finned coiled tube panel, and the exhaust gas temperature of the boiler is 134 ℃.
As shown in FIG. 5, the boiler feed water temperature is 220 ℃, the boiler feed water enters the boiler system through 2 pipelines, and after heat balance calculation, 58% of the total feed water amount of a branch I directly enters the economizer inlet header through the bypass of the air preheater system. And in the second branch, 42% of total water supply enters an inlet header of the air preheater, the water temperature is reduced to 90 ℃ from 220 ℃ after passing through an outlet header of the air preheater, the water flow direction and the air flow direction are mutually countercurrent, and the heat convection coefficient is increased. And the feed water enters the inlet header of the flue gas cooler from the outlet header of the air preheater, after the heat convection between the high-temperature flue gas and the boiler feed water, the temperature of the boiler feed water in the outlet header of the flue gas cooler is increased from 90 ℃ to 220 ℃, and the boiler feed water is converged with the first branch and then enters the inlet header of the economizer. And the 5-stage flue gas cooler and the air preheater are respectively provided with a bypass pipeline.
Claims (6)
1. The boiler structure capable of avoiding low-temperature corrosion of the heating surface at the tail part of the boiler comprises an air preheater (3) and a flue gas cooler, and is characterized in that the air preheater (3) is installed in an air duct system (2), the air duct system (2) is located outside the boiler, the flue gas cooler is located in a flue at the tail part of the boiler, and the air duct system (2) is communicated with the flue at the tail part of the boiler.
2. The boiler structure for avoiding the low-temperature corrosion of the heating surface at the tail part of the boiler according to claim 1, wherein the flue gas cooler comprises a first flue gas cooler (4), a second flue gas cooler (5), a third flue gas cooler (6), a fourth flue gas cooler (7) and a fifth flue gas cooler (8) which are sequentially connected in series along the flow direction of feed water, a water inlet (12) of the flue gas cooler is positioned on the first flue gas cooler (4), and a water outlet (11) of the flue gas cooler is positioned on the fifth flue gas cooler (8).
3. The boiler structure for avoiding the low-temperature corrosion of the heated surface at the tail part of the boiler as claimed in claim 2, characterized in that a first economizer (9) and a second economizer (10) are arranged in sequence at the downstream of a fifth flue gas cooler (8) in the flue at the tail part of the boiler.
4. A boiler structure for avoiding low temperature corrosion of the heated surface at the tail of the boiler according to claim 3, characterized in that the tubes in the air preheater (3) are spiral fin tubes (13), the spiral fin tubes (13) are perpendicular to the air flowing direction in the air preheater (3), the spiral fin tubes (13) are arranged in rows, and two adjacent rows of spiral fin tubes (13) are arranged in a staggered manner.
5. A boiler structure avoiding low-temperature corrosion of the heated surface at the tail of the boiler, according to claim 4, characterized in that the water flow rate in the pipe inside the air preheater (3) is 1-2m/S and the air flow rate inside the air preheater (3) is 7.5 m/S.
6. The boiler structure for avoiding the low-temperature corrosion on the heating surface at the tail part of the boiler according to the claim 5, characterized in that the flue gas cooler comprises a finned serpentine tube panel, a support plate (1) and an inner guard plate (14), the finned serpentine tube panel is installed on the support plate (1), the inner guard plate (14) is positioned around the finned serpentine tube panel, and the exhaust smoke temperature of the boiler is 134 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021697987.4U CN212618239U (en) | 2020-08-14 | 2020-08-14 | Boiler structure for avoiding low-temperature corrosion of heating surface at tail of boiler |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021697987.4U CN212618239U (en) | 2020-08-14 | 2020-08-14 | Boiler structure for avoiding low-temperature corrosion of heating surface at tail of boiler |
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| CN212618239U true CN212618239U (en) | 2021-02-26 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202021697987.4U Active CN212618239U (en) | 2020-08-14 | 2020-08-14 | Boiler structure for avoiding low-temperature corrosion of heating surface at tail of boiler |
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| CN (1) | CN212618239U (en) |
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