JPH06323486A - Duct - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent ash from accumulating on the horizontal part of the exhaust gas duct. [Structure] The exhaust gas 8 is provided on the bottom of the horizontal portion of the exhaust gas duct 7.
The plurality of protrusions 18 are provided in the flow direction of
A turbulent flow of the exhaust gas 8 is generated on the back surface of the exhaust gas 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a duct.

[0002]

2. Description of the Related Art As an example of a conventional coal-fired boiler,
There is one as shown in FIG.

In FIG. 4, reference numeral 1 denotes a boiler main body, which is connected to a furnace 2, an auxiliary side wall 3 connected to the upper rear of the furnace 2, and a rear side of the auxiliary side wall 3. It is provided with a rear heat transfer section 4 in which an overheater, a reheater, and a economizer (none of which are shown) are installed.

Reference numeral 5 is a coal burner attached to the lower front wall of the furnace 2, and the coal burner 5 is housed in a wind box 6.

Reference numeral 7 is an exhaust gas duct connected to a lower portion of the rear heat transfer section 4 and through which an exhaust gas 8 discharged from the rear heat transfer section 4 of the boiler body 1 passes, and 9 is a denitration device connected to a midway portion of the exhaust gas duct 7. Reference numeral 10 denotes an air preheater connected to a midway portion of the exhaust gas duct 7 so as to be located downstream of the denitration device 9 with respect to the flow of the exhaust gas 8, and 11 is downstream of the air preheater 10 with respect to the flow of the exhaust gas 8. It is an electrostatic precipitator connected to an intermediate part of the exhaust gas duct 7 so as to be located on the side.

12 is a high pressure blower for feeding the secondary air 13,
Reference numeral 14 is an air duct whose rear end is connected to the high-pressure ventilator 12 and to which the air preheater 10 is connected in the middle, and the front end of the air duct 14 is connected to the wind box 6.

In the above coal-fired boiler, the coal injected from the coal burner 5 into the furnace 2 is burned by the secondary air 13 introduced into the furnace 2 from the wind box 6 to generate combustion gas. , The combustion gas passes through the furnace 2, the side wall 3, and the rear heat transfer section 4 to heat or superheat the internal fluid of the evaporator, superheater, reheater, and economizer, and the rear heat transfer of the boiler body 1 Exhaust gas 8 is discharged from the lower part of the portion 4 to the exhaust gas duct 7, denitrified by the denitration device 9 and fed to the air preheater 10, the air preheater 10 preheats the secondary air 13, and the electric dust collector 11 exhausts the exhaust gas 8 The ash and the like in the inside is removed, and the exhaust gas 8 from which the ash and the like have been removed is further subjected to predetermined treatment such as denitration,
Emitted from the chimney to the atmosphere.

Further, the air duct 14 is driven by the high pressure blower 12.
The secondary air 13 introduced into the air preheater 10 is heated by the exhaust gas 8 fed through the exhaust gas duct 7 in the air preheater 10 and is introduced into the furnace 2 from the wind box 6 to be used for combustion of fuel.

[0009]

In the above coal-fired boiler, in the exhaust gas 8 before being collected by the electric dust collector 11,
The ash produced by the combustion of coal is mixed, and if the exhaust gas flow rate in the exhaust gas duct 7 is slow, ash may accumulate in the exhaust gas duct 7. Therefore, the exhaust gas flow rate is 10 times or more the natural sedimentation speed of the ash. Value (5 to 10 m / sec.) To prevent ash from accumulating in the exhaust gas duct 7.

However, when the boiler load is low, the flow velocity of the exhaust gas in the exhaust gas duct 7 decreases, so that the ash entrained in the exhaust gas 8 is likely to settle, and as shown in FIG. On the bottom surface of the horizontal portion of the exhaust gas duct 7 located on the upstream side, the ash 15 is deposited starting from the corner of the bent portion of the exhaust gas duct 7, and grows rearward. Further, the ash 15 that has once accumulated is not entrained in the exhaust gas 8 even when the boiler load becomes high and the exhaust gas flow velocity in the exhaust gas duct 7 becomes fast. Therefore, due to the long-term operation of the boiler, the exhaust gas duct 7 A large amount of ash 15 is deposited on the bottom surface of the horizontal portion of the inside, and an excessive load may be applied to the exhaust gas duct 7.

Further, the air preheater 10 is a regenerative rotary air preheater, and since the exhaust gas passage and the air passage are shared, a part of the exhaust gas 8 flows from the exhaust gas passage to the air flow. It leaks to the road, is mixed with the secondary air 13 and is fed to the wind box 6 side. Therefore, ash 16 is also accumulated on the bottom surface of the horizontal portion of the air duct 14 from the air preheater 10 to the wind box 6, and the boiler 16 As a result of the long-term operation, a large amount of ash 16 is accumulated, and an excessive load may be applied to the air duct 14.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent ash from accumulating in a duct body such as an exhaust gas duct or an air duct.

[0013]

In order to achieve the above object, according to the present invention, a plurality of ash-containing fluids are provided on a bottom surface of a duct body and extend in a direction orthogonal to the fluid flow direction. The protrusions are arranged at required intervals in the fluid flow direction.

Further, of the plurality of projections, the projection located on the most upstream side with respect to the fluid flow direction can be located in the vicinity of the corner of the bent portion of the duct body, and the side surface of the projection has a top portion. It can be formed in an angled shape facing upward, and furthermore, a guide vane for guiding the fluid can be provided in the bent portion in the duct body.

[0015]

When the fluid flowing in the duct body collides with the projecting body, turbulent flow occurs on the back surface on the downstream side with respect to the fluid flow direction of the projecting body, and an upward velocity component is generated in the fluid. No ash is deposited on the.

Assuming that the protrusion located on the most upstream side with respect to the flow direction of the fluid is near the corner of the bent portion of the duct body,
It is possible to prevent ash from accumulating and growing downstream from the corner portion in the fluid flow direction.

If the side surface of the projecting body is formed in an angled shape with the top facing upward, or if a guide vane is provided at the bent corner portion in the duct main body, the turbulent flow generated on the back surface of the projecting body becomes stronger, so that it is more reliable. Ashes can be prevented from accumulating.

[0018]

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

1 and 2 show an embodiment of the present invention,
The portion where the exhaust gas 8 transitions from the upward flow to the horizontal flow is shown.

In the figure, 17 is a guide vane provided inside the upper bent portion of the exhaust gas duct 7 so as to guide the exhaust gas 8 from an upward flow to a horizontal flow, and 18 is an exhaust gas duct 7 on the bottom surface of the upper horizontal part of the exhaust gas duct 7. The plurality of protrusions are provided at required intervals in the flow direction of the exhaust gas 8 with reference to the inner corners of the bent portions. The projecting body 18 extends in the width direction of the exhaust gas duct 7 so that both ends come into contact with the insides of both side plates of the exhaust gas duct 7, and the side surface is formed in an angle shape with its top portion facing upward. According to the experiment, the height h of the projecting body 18 is preferably about 10 to 20% of the height H of the exhaust gas duct 7.

The exhaust gas 8 that has risen in the vertical portion of the exhaust gas duct 7 is guided by the guide vanes 17, and is turned to the horizontal direction in a state where it is distributed substantially evenly over the entire cross section, and the horizontal portion of the exhaust gas duct 7 is guided. It flows downstream. At this time, a part of the exhaust gas 8 collides with the guide vanes 17 and rises along the front inclined surface of the guide vanes 17, and becomes a turbulent state on the back surface. Therefore, on the bottom surface of the horizontal portion of the exhaust gas duct 7, an upward velocity component is generated in the flow of the exhaust gas 8, and even if the exhaust gas 8 contains ash, the ash rises due to the upward velocity component and is deposited on the bottom surface. There is no such thing.

FIG. 3 shows another embodiment of the present invention, showing a portion where the exhaust gas 8 shifts from a downward flow to a horizontal flow.

In the figure, 19 is a guide vane provided for guiding the inside of the lower bent portion and the exhaust gas 8 from a downward flow to a horizontal flow, and 20 is a bent portion of the exhaust gas duct 7 on the bottom surface of the lower horizontal portion of the exhaust gas duct 7. The plurality of protrusions are provided at required intervals in the flow direction of the exhaust gas 8 with reference to the vicinity of the outer corner portion. The shape and size of the protrusion 20 are substantially the same as those of the protrusion 18.

In the case of this embodiment as well, as in the case of the previous embodiment, ash does not accumulate on the bottom of the horizontal portion of the exhaust gas duct 7.

In the above embodiment, the protrusions 18, 20 are
Although it is not particularly described in which range of the horizontal portion of the exhaust gas duct 7 is provided, it may be provided at a required interval over the entire horizontal portion, or the ash may be provided by the protrusions 18 or 20. If it does not exist, the corner portion of the bent portion is used as a starting point to deposit on the downstream side in the exhaust gas flow direction.

[0026]

In the duct of the present invention, it is possible to prevent ash from accumulating in the duct body in any of the ducts of the claims, and in the case of the duct of claim 2, the ash flows from the corner portion to the fluid. It is possible to prevent deposition and growth downstream in the flow direction, and in the case of the duct according to claims 3 and 4, claim 1
The effect of preventing ash accumulation is more remarkable than that of the duct.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the duct of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a side sectional view of another embodiment of the duct of the present invention.

FIG. 4 is an elevational view showing an outline of a coal-fired boiler.

[Explanation of symbols]

 7 Exhaust Gas Duct (Duct Main Body) 8 Exhaust Gas (Fluid) 13 Secondary Air (Fluid) 14 Air Duct (Duct Main Body) 17 Guide Vane 18 Projection Body 19 Guide Vane 20 Projection Body

Claims (4)

[Claims] 1. A plurality of protrusions extending in a direction orthogonal to the flow direction of the fluid are arranged at a required interval in the flow direction of the fluid on the bottom surface of the duct main body through which the fluid containing ash flows. And duct. 2. The duct according to claim 1, wherein the protrusion located on the most upstream side with respect to the flow direction of the fluid is located near the corner of the bent portion of the duct body. 3. The duct according to claim 1, wherein the side surface of the projecting body is formed in an angled shape with its top portion facing upward. 4. The duct according to claim 1, 2 or 3, wherein a guide vane for guiding a fluid is provided at a bent portion in the duct body.