JPH0942872A - Air preheater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an effective removal of combustion ash accumulated at an upper air hood to be carried out. SOLUTION: A scraper 58 is fixed in a discharged gas duct 21. As an air hood 10 is circulated around to reach a position where the scraper 58 is arranged, combustion ash accumulated at an upper surface of the air hood 10 is wiped off with the scraper 58.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an air preheater.

[0002]

2. Description of the Related Art Generally, in a boiler such as a pulverized coal burning boiler, primary air used to convey fuel such as pulverized coal and secondary air used to burn fuel are generated in the boiler. Air preheaters are used to preheat by exchanging heat with the exhaust gas.

Such a conventional air preheater is shown in FIGS.
2 will be described.

In FIG. 3, reference numeral 1 denotes an air preheater main body for exchanging heat between the high temperature exhaust gas 2 and the primary air 3 for fuel transportation and the secondary air 4 for combustion. Reference numeral 5 is a cylindrical stator disposed in the center of the air preheater body 1, 6, 7
Are heat exchange elements (see FIG. 4) provided inside the stator 5 and radially partitioning the inside of the stator 5 on the inner peripheral side and the outer peripheral side, respectively.

Numeral 8 is provided on the lower end surface of the stator 5 so as to cover a part of the stator 5, and is a symmetrical butterfly-shaped insert capable of rotating in the circumferential direction while sliding on the lower end surface of the stator 5. Side secondary air hood, 9 is incoming secondary air hood 8
Is an inlet-side primary air hood provided inside the. Similarly, 10 is provided on the upper end surface of the stator 5 so as to cover a part of the stator 5, and the inlet side secondary air hood 8 and the main shaft 11 are provided.
The outlet side secondary air hood, which is connected through a and rotates in synchronization while maintaining the same phase, 12 is the outlet side secondary air hood 10.
Which is an outlet side primary air hood, and the primary air 3 for fuel transfer is the rotating inlet side primary air hood 9 and rotating side primary air hood 12 in the heat exchange element 6 on the inner peripheral side. The secondary air 4 for combustion flowing through the portion covered with the outer peripheral side heat exchange element 7 is rotated by the rotating inlet-side secondary air hood 8 and outlet-side secondary air hood 1.
It is designed to flow through the part covered with 0 (see FIG. 5).

In the figure, 11b is a stator 5 and a main shaft 11a.
It is a bearing interposed between and.

Reference numeral 13 denotes an inlet side secondary air duct connected to the inlet side secondary air hood 8 via a rotary seal 14, and reference numeral 15 denotes an outlet side connected to the outlet side secondary air hood 10 via a rotary seal 16. It is a secondary air duct. Further, 17 is an inlet side primary air duct connected to the inlet side primary air hood 9 via a rotary seal 18, and 19 is an outlet side primary air duct connected to the outlet side primary air hood 12 via a rotary seal 20. is there.

Reference numeral 21 designates an outlet side secondary air hood 1 of the stator 5.
It is an inlet side exhaust gas duct for supplying the high temperature exhaust gas 2 to a portion other than the portion covered with 0. Further, 22 passes through a portion of the heat exchange element 6 on the inner peripheral side, which is attached to the outer side of the inlet side secondary air hood 8 or the inlet side primary air hood 9, and is not covered by the inlet side primary air hood 9. An outlet side primary exhaust gas hood (see FIG. 6) for receiving the primary exhaust gas 23, and a rotary seal 2 at the outlet side primary exhaust gas hood 22.
An outlet-side primary exhaust gas duct connected through 5 is a secondary exhaust gas 27 which has passed through a portion of the heat exchange element 7 on the outer peripheral side other than the portion covered by the inlet-side secondary air hood 8.
Of the outlet side secondary exhaust gas duct, 28 is a damper provided in the outlet side primary exhaust gas duct 24, and 29 is a damper provided in the outlet side secondary exhaust gas duct 26.

Reference numeral 30 denotes a ring-shaped pin rack mounted on the outside of the inlet side secondary air hood 8. Reference numeral 31 denotes a pinion 32 mounted on the side of the air preheater body 1 of the air preheater and meshing with the pin rack 30. It is a drive mechanism such as a motor.

A reference numeral 33 indicates a fluid such as air or steam on the upper and lower end surfaces of the heat exchange elements 6 and 7 while rotating in the circumferential direction in synchronization with the inlet side secondary air hood 8 and the outlet side secondary air hood 10. Soot blower to be cleaned with 35 is a nozzle attached to the soot blower 33 extending substantially in the radial direction of the stator 5 at a predetermined pitch, 36 is a fluid supply passage for supplying the fluid 34 to the soot blower 33, 37a, 37b, 37
c is an expansion joint provided in the middle of the fluid supply channel 36, 3
Reference numeral 8 is a rotary joint provided in the middle of the fluid supply passage 36 (see FIGS. 7 and 8).

A nozzle position changing device 41 as described below is attached to the soot blower 33.

That is, a vertical shaft 43 is attached to the outlet side secondary air hood 10 or the inlet side secondary air hood 8 via a shaft support member 42, and in the case of the outlet side secondary air hood 10, the upper end of the vertical shaft 43. A steering wheel 45 having about 20 blades 44 at the lower end of the vertical shaft 43 in the case of the inlet side secondary air hood 8 (see FIGS. 11 and 12). 21 and outlet secondary exhaust gas duct 26 Operation arm 46 for striking blade 44 at one position in the circumferential direction
Is attached, and in the case of the outlet side secondary air hood 10, the vertical shaft 4
A heart-shaped cam 47 is attached to the lower end of the camshaft 3 and to the upper end of the vertical shaft 43 in the case of the inlet side secondary air hood 8, and a set of two cam followers 4 guided by the cam 47 is attached.
8 is provided to hold the cam 47, and is provided with a follower holder 49 capable of reciprocating substantially in the longitudinal direction of the soot blower 33, and the follower holder 49 is connected to the soot blower 33 via the swing arm 50 and the mounting pin 51. (See FIG. 10).

Reference numeral 52 is an elongated hole formed in the follower holder 49 for passing the vertical shaft 43 therethrough.

Next, the operation will be described.

A drive mechanism 31 such as a motor is actuated, and the inlet-side and outlet-side air hoods 8 to 10 and 12 and the outlet-side primary exhaust gas hood 22 are passed through the pinion 32 and the pin rack 30 in the circumferential direction of the stator 5. And the high temperature exhaust gas 2 is supplied from the inlet side exhaust gas duct 21 and the primary air 3 is supplied from the inlet side primary air duct 17 between the inlet side secondary air duct 13 and the inlet side primary air duct 17. Secondary air 4 is supplied, respectively.

Then, the high temperature exhaust gas 2 entering from the inlet side exhaust gas duct 21 enters the stator 5 from a portion not covered by the outlet side secondary air hood 10, and is transferred to the inner peripheral side by the thermal energy of the exhaust gas 2. The heat exchange elements 6 and 7 on the outer peripheral side are heated. Then, the exhaust gas 2 is divided into two inside the stator 5 by the heat exchange element 6 on the inner peripheral side and the heat exchange element 7 on the outer peripheral side. As the primary exhaust gas 23 through the hood 22 and the outlet-side primary exhaust gas duct 24,
Further, the exhaust gas 2 that has passed through the heat exchange element 7 on the outer periphery is exhausted to the outside as a secondary exhaust gas 27 via the outlet-side secondary exhaust gas duct 26.

On the other hand, the primary air 3 entering from the inlet-side primary air duct 17 enters into the inner peripheral side heat exchange element 6 heated from the inlet-side primary air hood 9 to be preheated, and the outlet-side primary air hood 12. After being guided to the outside, it is sent from the outlet-side primary air duct 19 to an external supply destination.

Similarly, the secondary air 4 entering between the inlet-side secondary air duct 13 and the inlet-side primary air duct 17 is heated from the inlet-side secondary air hood 8 to the heat exchange element 7 on the outer peripheral side. After entering the inside and being preheated and being led out to between the outlet side secondary air hood 10 and the outlet side primary air hood 12, the outside is discharged from between the outlet side secondary air duct 15 and the outlet side primary air duct 19, respectively. Will be sent to the supplier.

At this time, the exhaust gas ducts 24, 26 on the outlet side
By adjusting the opening degrees of the dampers 28 and 29 provided in, the flow rate distribution of the primary exhaust gas 23 and the secondary exhaust gas 27 is changed, and the preheating degree for the primary air 3 and the secondary air 4 is adjusted.

In the air preheater, the high temperature exhaust gas 2
In order to prevent the sulfuric acid and ash contained in the exhaust gas 2 from adhering to the heat exchange elements 6 and 7 through which the exhaust gas passes, so as not to block the heat exchange elements 6, 7 from the soot blower 33 at regular intervals during operation.
A fluid 34 such as air or steam is jetted toward 7 to wash the heat exchange elements 6 and 7.

As shown in FIG. 9, the soot blower 33 has a pair of parallel links 40 in the vicinity of both ends thereof, as shown in FIG. 9, on a bracket 39 attached to the inlet side secondary air hood 8 or the outlet side secondary air hood 10. The heat exchange elements 6 and 7 are mounted so as to be horizontally swingable, and the heat exchange elements 6 and 7 can be displaced substantially in the radial direction to shift the positions of a plurality of nozzles 35 arranged at intervals.

That is, the soot blower 33 makes one round with the outlet side secondary air hood 10 and the inlet side secondary air hood 8, and is located at one position in the circumferential direction of the inlet side exhaust gas duct 21 and the outlet side secondary exhaust gas duct 26. When a protrusion such as the blade 44 of the steering wheel 45 hits the operation arm 46 provided, the steering wheel 45 and the heart-shaped cam 4
By slightly rotating 7 in the horizontal direction, its phase is slightly changed, and the cam follower 48 and the follower holder 4
9. The soot blower 33 is slightly displaced in the radial direction of the heat exchange elements 6, 7 via the swing arm 50, so that the cleaning position for the heat exchange elements 6, 7 can be changed.

Since about 20 blades 44 are attached to the steering wheel 45 in the circumferential direction, when the operation arm 46 is hit about 20 times, the steering wheel 45 makes one turn and heat is evenly distributed. The replacement elements 6, 7 can be cleaned.

The position of the steering wheel 45 is
The nozzle position changing device 41 is held by the frictional resistance of each part.

[0025]

However, the above conventional air preheater has the following problems.

That is, in general, in the exhaust gas 2 of the boiler,
Although the combustion ash of fuel is included, the combustion ash in the exhaust gas 2 inevitably accumulates on the outlet side secondary air hood 10 located above because the exhaust gas 2 passes through the inlet side exhaust gas duct 21. Will be done.

However, since the accumulated amount of combustion ash reaches several tons, a large load is applied to the outlet side secondary air hood 10, and the gap between the outlet side secondary air hood 10 and the heat exchange element 6 is changed. However, there has been a problem in that they cause wear and damage due to contact between the two and cause air leakage.

It should be noted that the combustion ash accumulated on the outlet side secondary air hood 10 must be manually cleaned when the operation of the air preheater main body 1 is stopped, but there is no particularly effective ash removing means.

In view of the above situation, it is an object of the present invention to provide an air preheater capable of effectively removing the combustion ash accumulated in the outlet secondary air hood (upper air hood). To do.

[0030]

In order to solve the above problems, the present invention uses the following means.

According to the present invention, a cylindrical heat exchange element whose inside is radially partitioned is provided in the middle of the exhaust gas duct, and the upper and lower end faces of the heat exchange element are surrounded by the required angle range of each end face. In addition, a pair of upper and lower butterfly-shaped air hoods are provided so as to be synchronously rotatable around a main shaft penetratingly arranged in the axial center of the heat exchange element, and an air duct is connected to each air hood via a rotary joint. In the air preheater, a scraper capable of wiping off combustion ash accumulated on the upper surface of an upper air hood is fixedly installed in an exhaust gas duct.

In this case, a fluid injection nozzle capable of injecting a fluid for removing combustion ash may be provided at a position downstream of the scraper in the rotation direction of the heat exchange element.

When the exhaust gas is passed through the upper exhaust duct and air is pumped to the lower air duct to rotate the pair of upper and lower air hoods synchronously, the exhaust gas is covered with the air hood of the heat exchange element from the upper exhaust duct. It heats that part of the heat exchange element through the part which is not covered. After that, the exhaust gas is sent to the downstream side through the lower exhaust gas duct and finally discharged to the atmosphere.

On the other hand, the air supplied to the lower air duct passes from the lower air duct through the lower air hood to
After passing through the portion of the heat exchange element covered with the air hood, the heat is transmitted from the upper air hood to the downstream side through the upper air duct, and then to the outside.

At this time, the upper and lower air hoods are synchronously rotated about the main shaft, so that according to the rotation of the air hoods, the air is passed through the portion heated by the exhaust gas of the heat exchange element, This preheats the air.

Exhaust gas from the boiler generally contains combustion ash of the fuel, and the exhaust gas passes through the exhaust gas duct, so that the combustion ash in the exhaust gas is inevitably deposited on the air hood located above. Will be deposited.

Therefore, in the present invention, by fixing the scraper in the exhaust gas duct, when the air hood goes around and reaches the position where the scraper is provided, the scraper wipes off the combustion ash accumulated on the upper surface of the air hood. I will let you.

Further, after wiping the combustion ash with a scraper,
By injecting a fluid such as air or steam from a fluid ejection nozzle arranged toward the upper surface of the air hood, the combustion ash remaining on the upper surface of the air hood is blown off by the pressure of the fluid.

As described above, the accumulation of the combustion ash is eliminated and the large load due to the combustion ash is eliminated on the air hood, so that the gap between the air hood and the heat exchange element is deviated, and the wear and contact due to the contact between the two are caused. Damage and air leakage are prevented.

[0040]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an example of the embodiment of the present invention.

The basic structure of the air preheater is shown in FIGS.
Since it is similar to FIG. 12, these figures will be referred to as necessary.

In the present invention, the air preheater is provided with the following ash removing device.

That is, a pair of support members 53 extending in the radial direction of the heat exchange elements 6 and 7 are provided between the inlet side exhaust gas duct 21 and the outlet side secondary air duct 15, and the support member 5 is provided.
3 is provided with a plurality of support members 54 that extend laterally or downward, and the lower ends of the respective support members 54 are directed to the upper surface of the outlet secondary air hood 10 located above and outward in the radial direction. A fluid for sending to the soot blower 33 between the fluid supply flow path 36 and the fluid injection nozzle 55 by attaching the holders 56 holding a plurality of fluid injection nozzles 55 for injecting the fluid 34 such as air and steam in a row. A fluid purge pipe 57 for purging 34 is connected.

Further, a scraper 58 for wiping the combustion ash accumulated on the upper surface of the outlet side secondary air hood 10 is provided between the respective holding bodies 56 and at a position upstream of the outlet side secondary air hood 10 in the rotation direction. Fix it.

Next, the operation will be described.

The process of exchanging heat with the air preheater is the same as in FIGS.

The boiler exhaust gas 2 generally contains combustion ash of fuel, and the exhaust gas 2 enters the exhaust gas duct 2 on the inlet side.
Combustion ash in the exhaust gas 2 inevitably goes through 1
It will be deposited on the outlet side secondary air hood 10 located above.

Therefore, in the present invention, the inlet side exhaust gas duct 2
By fixing the scraper 58 to the inside of No. 1, when the output side secondary air hood 10 orbits and reaches the position where the scraper 58 is provided, the combustion accumulated on the upper surface of the output side secondary air hood 10 by the scraper 58. I try to get rid of the ash.

Further, after the combustion ash is wiped off by the scraper 58, the fluid 34 such as air or steam is jetted from the fluid jet nozzle 55 arranged toward the upper surface of the outlet side secondary air hood 10, so that the fluid is discharged. The pressure of 34 blows off the combustion ash remaining on the upper surface of the outlet secondary air hood 10.

As described above, the accumulation of the combustion ash is eliminated and the large load due to the combustion ash on the outlet side secondary air hood 10 is eliminated, so that the outlet side secondary air hood 10 and the heat exchange element 6 are separated from each other. It is prevented that the gap is deformed, causing wear and damage due to contact between the two, or causing air leakage.

It should be noted that the present invention is not limited to the above-mentioned embodiment, but is applicable to an air preheater which is not divided into primary air and secondary air. Needless to say, various changes can be made without departing from the scope of the invention.

[0053]

As described above, according to the air preheater of the present invention, it is possible to effectively remove the combustion ash accumulated on the upper air hood.

[Brief description of drawings]

FIG. 1 is a partially enlarged side sectional view of an example of an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows II-II in FIG.

FIG. 3 is a schematic overall side view of a conventional air preheater.

FIG. 4 is a schematic perspective view of a fixing element.

FIG. 5 is a schematic perspective view in which an air hood is extracted.

FIG. 6 is a plan view showing an outlet-side primary exhaust gas hood.

7 is an enlarged view of the outlet side secondary air hood portion of FIG.

FIG. 8 is an enlarged view of an inlet side secondary air hood portion of FIG.

9 is a view on arrow IX-IX in FIG. 3;

FIG. 10 is a view taken in the direction of arrows XX in FIG. 3;

FIG. 11 is a side sectional view of a steering wheel portion.

FIG. 12 is a plan view of a steering wheel portion.

[Explanation of symbols]

 6,7 Heat exchange element 10 Air hood (outlet secondary air hood) 11a Main shaft 15 Air duct (outlet secondary air duct) 16 Rotating joint 21 Exhaust gas duct (inlet exhaust gas duct) 34 Fluid 55 Fluid injection nozzle 58 Scraper

Claims (2)

[Claims] 1. A cylindrical heat exchange element whose inside is radially partitioned is provided in the middle of the exhaust gas duct, and upper and lower end faces of the heat exchange element are surrounded by a portion within a required angle range of each end face. A pair of upper and lower butterfly-shaped air hoods are provided so that they can rotate synchronously around a main shaft that penetrates through the axial center of the heat exchange element, and an air duct that connects air ducts to each air hood via a rotary joint. An air preheater characterized in that a scraper capable of wiping combustion ash accumulated on an upper surface of an upper air hood is fixedly installed in an exhaust gas duct. 2. The air preheater according to claim 1, wherein a fluid injection nozzle capable of injecting a fluid for removing combustion ash is attached at a position downstream of the scraper in the rotation direction of the heat exchange element.