JPS58205003A - Spiral type water-tube boiler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a combustion chamber formed into a cylindrical shape with a predetermined diameter by winding up a water tube in a spiral manner, and a different cylindrical shape having a different diameter from the cylindrical shape for the combustion chamber. This invention relates to improvements in the convection heat transfer section of a spiral water tube boiler, which is constructed by configuring a convection heat transfer section consisting of annular channels between cylinders of different diameters arranged in concentric circles. .

Figure 1 shows a schematic diagram of a conventional spiral water tube boiler.

The water pipes are fully or partially welded concentrically to the spirally wound inner cylinder 1, so that they are in close contact with each other and combustion gas does not leak from between the water pipes. Instead of welding, the outer cylinder 2 may also be rolled up tightly onto an outer casing 3, with which gas sealing is provided. Boiler feed water enters, for example, from the upper part of the outer cylinder 2, flows down the outer cylinder while swirling, and enters the connecting pipe 4 at the lowest end.
to the inner cylinder. The boiler water flows up the inner cylinder 1 from the lower part while swirling and flows out from the uppermost end to, for example, a steam separator (not shown). The circulation power of the canned water is ensured by the pressure of the attached pump.

t 2 \ The burner 5 is attached to the top of the inner cylinder 1 . The upper part of the inner cylinder 1 is gas-sealed by a refractory material 6. The bottom of the outer cylinder 2 is gas-sealed by a bottom refractory 7.

Fuel is combusted by the burner 5 using the inside of the inner cylinder 1 as a combustion chamber. The generated combustion gas flows down inside the combustion chamber,
The gas flows upward through the annular flow path 8 between the inner cylinder 1 and the outer cylinder 2, collects at the gas header part 9 at the upper end, and flows out through the exhaust port 10 installed in that direction.

In such a spiral water tube boiler, the water tubes can be constructed relatively easily, and the entire boiler can be assembled into a compact form, so it is suitable for forced once-through boilers,
It is often put into practical use as forced circulation boilers and forced circulation heat medium boilers, etc., with thermal output / θ 0,000 W / hour ~ 3 θ θ
Call me 10,000 days/hour.

Heat absorption in this type of boiler can be roughly divided into heat absorption by radiant heat transfer from the combustion flame in the combustion chamber constituted by the inner cylindrical part 1, and heat absorption in the annular flow path between the inner and outer cylinders, 2. This is the sum of the heat absorption due to contact heat transfer of combustion gas to the channel wall surface.

Radiant heat transfer in the combustion chamber is mainly determined by the size of the combustion flame, the size of the combustion chamber, combustion conditions, etc. In boiler design methods, the size of the combustion chamber is determined by the dimensions required for combustion. Therefore, the heat absorption in the combustion chamber, which is one element of heat absorption in the boiler, is almost uniquely determined by the burner mechanism used in the boiler, and cannot be determined arbitrarily by the designer. In the current normal combustion method, the combustion chamber is / mB volumetric jθ million ~ /
It is often designed to have a combustion amount of θθ million days/hour, and the amount of heat absorbed in the combustion chamber, that is, the amount of heat absorbed on the inner circumferential side of the inner cylinder in Fig. 1 (a), is equal to the amount of heat absorbed in the entire boiler. gθ% to 0%.

The remaining required heat absorption of the boiler will be 40-g0%. These amounts of heat must be absorbed by the water tube surfaces of the inner and outer cylinders 1.2 that form the flow path while the combustion gas flows through the annular flow path 8 of FIG. 1, by so-called contact heat transfer. The amount of heat absorbed by this contact heat transfer is expressed by equation 1.

ΔQ = A x K × ΔT ・
・・・・・・・・・ (1) Here, Q: Amount of heat absorbed by contact heat transfer m/hA: Contact heat transfer area
m2: Heat transmission coefficient due to contact kal/m
t h 'CΔT: Logarithmic average temperature difference defined by equation (2) ℃ where tGl : Gas temperature at the annular flow path inlet ℃ta2 : Gas temperature at the annular flow path outlet ℃t
W: Boiler water temperature For a certain type of boiler, tW is determined by the operating conditions of the boiler, and tJ is determined mainly by the size of the combustion chamber. A is a value that is almost determined by the size of the combustion chamber.

K is a value that is approximately determined by the flow velocity of the high-temperature combustion gas flowing through the annular flow path 8, and becomes a constant value if the gap t of the annular flow path is determined.

tG2 is a value that the designer would like to arbitrarily decide based on the design efficiency target of the boiler, but it is uniquely determined once the dimensions of the combustion chamber of the boiler are determined by the equation (above) (2). In order to lower tGl and increase boiler efficiency, it is necessary not only to increase the contact heat transfer area A, but also to make the combustion chamber thicker (and the boiler as a whole unnecessarily thicker). In some cases, as shown in FIG. 2, it may be necessary to employ one more passage in the contact heat transfer section to create a so-called three-pass boiler.

゛In this J-pass boiler, there are also 3 connections from the gas passage Copass.
The gas temperature at the turning point to the pass is 4100-iljθ℃
In this case, normal steel materials cannot be used for the shell, so 1
There will be a limit to the manufacturing capacity of this type of boiler, making it impossible to manufacture large-capacity boilers (6).

The present invention compensates for the above-mentioned drawbacks of the spiral water tube boiler and makes it possible to efficiently manufacture large-capacity models.The structure, operation, and effects of the present invention will be described in detail below based on examples.

Figure 3 is a cross-section of the annular gas flow path of the spiral water tube boiler in the gas flow direction. flows.

Since both ends of the gap are constituted by the outer surface of the tube, the gas flow sequentially flows through the large gap, creating appropriate turbulence. For this reason, convective heat transfer is somewhat better than smooth flow, but it does not reach a value as good as so-called extra-tube cross flow.

Figure 1 shows an example of this invention for promoting heat transfer in the annular flow path of a spiral water tube boiler.A round rod with a diameter d is placed on the surface of the cylinder in the direction of combustion gas flow. A certain angle θ,
They are arranged with an interval pitch P. FIG. 4 (-) is a cross-sectional view of the annular flow path taken along a plane parallel to the cylindrical axis XX,
FIG. 7(b) is a view of the inner cylinder viewed from YY.

Since the heat transfer promoting baffles are arranged along the outer surface of the cylinder made of water pipes, they are actually machined into a circular shape.

When the baffles are arranged in the annular flow path in this way, the combustion gas flow changes the flow angle by θ along the baffles in seven parts, and flows over the baffles in the other seven parts. The former component of the flow increases the relative velocity of the gas to the wall of the water pipe by (1/CO8·θ), thereby increasing the heat transfer coefficient. Other flow components flow over the baffle, creating a vortex behind the baffle, thereby creating turbulence in the flow near the wall and increasing heat transfer.

Due to the fluid elements of these J components, as shown in Figure 7, □ The heat transfer coefficient of the created heat transfer surface is significantly improved.

FIG. 3 is an exploded view of the cylinder. The figure (-) shows g baffles for promoting heat transfer arranged at an angle θ with respect to the gas flow angle. Although such an arrangement has a sufficient effect, if the angle of the baffle is changed midway to θ' as shown in Figure (b), the turbulent flow effect due to the baffle becomes even greater and heat transfer is further improved. do.

The second figure shows an example of a spiral water tube boiler based on the basic concept of promoting heat transfer coefficient as described above. The combustion gas produced by the burner 5 flows down the combustion chamber and upwards in the annular channel 8 between the inner cylinder l and the outer cylinder 2. At this time, the heat transfer from the combustion gas flow to the water tube is significantly improved by the heat transfer promoting baffle 11 attached to the inner cylinder 1, and the heat retained in the combustion gas is sufficiently transferred to the boiler water.

As an example of the effect of the heat transfer promoting baffle, a comparative example of a conventional boiler without a baffle and a boiler according to the present invention having a baffle is described below.

(9) In this way, by adding a heat transfer promoting baffle, the boiler exhaust gas temperature can be lowered by 770°C, and the boiler efficiency can be improved by 1%. ! 00k, /
The fuel consumption of the H boiler is J71/H with A heavy oil, and the annual increase in efficiency by 4% increases from jθθθ to 10,0θ.
This results in fuel savings of θl, and the effect is significant.

Further, other examples for boilers larger than the above example will be described below.

This is the 2pa of the 3pass boiler shown in Figure 2.
This is a comparison between a case where a baffle is attached to the ss section and a case where a baffle is not attached.

By using the heat transfer enhancing baffle of the present invention, boiler efficiency is increased by 4%, resulting in significant fuel savings. Furthermore, in a typical boiler design, 1.7pal18
The temperature of the turning part from part to J p888 part is SOO℃
When the boiler structure reached this point, it became impossible to design the boiler structure using ordinary steel materials, and this type of boiler was no longer viable.

In contrast, in the design of the present invention, the temperature is 370° C., so common steel materials can be used, thereby expanding the range of applications of spiral water tube boilers to large boilers.

As described above, the effects of this invention are remarkable.

In the above explanation, one example was given for each case in which a baffle was attached to the outside of the inner cylinder, but the effects of the present invention can be obtained when baffles are attached to the inside of the outer cylinder or to both the inner and outer cylinders. The effect is also demonstrated. 3 in Figure 2
The same applies when a baffle is attached to the pass.

[Brief explanation of the drawing]

Figure 1 shows an example of a conventional spiral water tube boiler (
a) is a longitudinal section, (b) is a cross section. Fig. 2 is a schematic diagram of a J-pass type spiral water tube boiler. Fig. 3 is a conceptual diagram of an annular flow path. Fig. 1 has a heat transfer promoting baffle rod according to the present invention. Conceptual diagram of an annular flow path Figure S is a developed view of an annular flow path with a baffle for promoting heat transfer according to the present invention. Figure 4 is a diagram showing a spiral water tube boiler according to the present invention. Cylindrical 4 Outer casing (connection tube upper part refractory Z Bottom refractory and annular flow path Z Part of gas header/Q Exhaust port/X Heat transfer accelerating baffle (13) - Air A52 Mountain law procedural amendment (method) Showa J7/R/'7 Date of X case 1988 Patent application No. G741/θ λ Name of invention Spiral water tube boiler d Person making the amendment Relationship to the case Patent Applicant address: 3-23 Shimome, Dojimahama, Kita-ku, Osaka City, July 1980 Submitted procedural amendment 1981 / / A'', 2nd (shipment date) Procedural amendment not accepted. Subject Contents of the amendment to the entire specification As attached Specification 1 Title of the invention Spiral water tube boiler 2 Claims A water tube boiler in which a water tube is spirally wound into a cylindrical shape with a predetermined diameter. The convection heat transfer portion composed of an annular flow path between different cylindrical shapes is characterized by having baffles made of round rods, flat plates, etc., arranged parallel to the combustion gas flow direction or at a certain angle. Spiral water tube boiler 3, the combustion chamber is made of a cylindrical shape with a diameter as described in the detailed description of Akira, and the cylindrical shapes of the tubs with different winding diameters are arranged concentrically with respect to the cylindrical shape for the combustion chamber, This relates to an improvement in the convection heat transfer portion of a spiral (1) water tube boiler, which is constructed by configuring a convection heat transfer portion consisting of an annular flow path between cylinders of different diameters. This is a schematic diagram of a spiral water tube boiler.The water tube is composed of an inner cylinder 1 wound up spirally and an outer cylinder 2 arranged concentrically. Alternatively, the outer cylinder 2 is partially welded to maintain close contact with each other and prevent combustion gas from leaking between the water pipes.The outer cylinder 2 is welded to the outer casing 3
The casing may be rolled up closely to provide a gas seal. Boiler feed water enters, for example, from the upper part of the outer cylinder 2, flows down the outer cylinder while swirling, and is transferred to the inner cylinder via the connecting pipe 4 at the lowest end. The boiler water flows up the inner cylinder 1 while swirling from the bottom and flows from the top end to a steam/water separator (not shown), for example.
It flows out. The circulation power of the canned water is ensured by the pressure of the attached pump. (2) The burner 5 is attached to the upper part of the inner cylinder 1. The upper part of the inner cylinder l is gas-sealed by an upper refractory 6. The bottom of the outer cylinder 2 is gas-sealed by a bottom refractory 7. Fuel is combusted by the burner 5 using the inside of the inner cylinder 1 as a combustion chamber. The generated combustion gas flows down inside the combustion chamber, flows upward through the annular flow path 8 between the inner cylinder 1 and the outer cylinder 2, collects at the gas header part 9 at the upper end, and flows out from the exhaust port 10 installed in that direction. I will do it. Such a spiral water tube boiler can be used as a forced once-through boiler, forced circulation boiler, forced circulation heat medium boiler, etc. because the water tubes can be constructed relatively easily and the entire boiler can be put together in a compact form. It has been put into practical use a lot, and the heat output/θ million days/hour ~ 3θθ million b+ 7
Spanning hours. Heat absorption in this type of boiler can be roughly divided into heat C1) absorption by radiant heat transfer from the combustion flame in the combustion chamber constituted by the inner cylindrical part 1, and high temperature absorption in the annular flow path between the inner and outer cylinders 1.2. This is the sum of the heat absorption due to contact heat transfer of combustion gas to the channel wall surface. Radiant heat transfer in the combustion chamber is mainly determined by the size of the combustion flame, the size of the combustion chamber, combustion conditions, etc. In boiler design methods, the size of the combustion chamber is determined by the dimensions required for combustion. Therefore, the heat absorption in the combustion chamber, which is one element of heat absorption in the boiler, is almost uniquely determined by the burner mechanism used in the boiler, and cannot be determined arbitrarily by the designer. In current normal combustion systems, the combustion chamber is often designed to have a combustion rate of 500,000 to /θ00,000 days/hour per m3 volume, and the amount of heat absorbed in the combustion chamber, that is, as shown in Figure 1 (a). The amount of heat absorbed on the inner circumferential side of the inner cylinder is tθ% of the amount of heat absorbed in the entire boiler.
(0%. The remaining required heat absorption amount of the boiler is θ~tθ%. These heat quantities form the annular flow path 8 in Fig. 1 while the combustion gas flows. It must be absorbed by the water tube surfaces of the inner and outer cylinders 1 and 2 by so-called contact heat transfer.The amount of heat absorbed by this contact heat transfer is expressed by equation (1). ΔQ=AXKXΔT・・・・・・・・・( 1) Here,
Q: Amount of heat absorbed by contact heat transfer m/h A: Contact heat transfer area m2: Heat transmission coefficient due to contact hl/m'h'CΔT: Logarithmic average temperature difference defined by equation (2) ℃Here, tGl : Gas temperature at the inlet of the annular flow path ℃tGjQ : Gas temperature at the outlet of the annular flow path ℃tW : Temperature of boiler water
℃ For a certain type of boiler, tW is determined mainly by the operating conditions of the boiler, and tGl is determined mainly by the size of the combustion chamber. A is a value that is almost determined by the size of the combustion chamber. K is a value that is approximately determined by the flow velocity of the high-temperature combustion gas flowing through the annular flow path 8, and becomes a constant value if the gap 8 of the annular flow path is determined. tG2 is a value that the designer wants to arbitrarily decide based on the design efficiency target of the boiler, but it is uniquely determined once the dimensions of the combustion chamber of the boiler are determined by the formula fil +21. In order to lower tGl and increase boiler efficiency, it is necessary not only to increase the contact heat transfer area, but also to make the combustion chamber thicker, making the entire boiler unnecessarily large. Therefore, in some cases, as shown in FIG. 1, it may be necessary to employ one more passage in the contact heat transfer section to form a so-called three-pass boiler. In this J-pass boiler as well, the gas temperature at the turning point from the gas passage copass to the 3rd pass is lθθ~41. When the temperature reaches fθ°C, normal steel materials cannot be used for the shell, so there is a limit to the manufacturing capacity of this type of boiler, and it becomes impossible to manufacture a large capacity boiler. The present invention compensates for the above-mentioned drawback (6) of the spiral water tube boiler and enables efficient manufacture of large-capacity models.The structure, operation, and effects thereof will be described in detail below based on examples. Figure 3 is a cross-section of the annular gas flow path of the spiral water tube boiler in the gas flow direction. flows. Since both ends of the gap are formed by the outer surface of the tube, the gas flow sequentially flows through the larger gap,
Flows with appropriate turbulence. For this reason, convective heat transfer is somewhat better than smooth flow, but it does not reach a value as good as so-called extra-tube cross flow. Figure 1 shows an embodiment of the present invention for promoting heat transfer in the annular flow path of a spiral water tube boiler. They are arranged with an interval pitch P. FIG. 4(a) is a cross-sectional view of the annular flow path cut along a plane parallel to the cylinder axis XX, and FIG.
b) is a drawing (7) looking at the inner cylinder from Y-Y. Since the heat transfer promoting baffles are arranged along the outer surface of the cylinder made of water tubes, they are actually machined into an elliptical shape. When the baffles are arranged in the annular flow path in this way, the combustion gas flow changes the flow angle by θ along the baffles in seven parts, and flows over the baffles in the other seven parts. The former component of the flow increases the relative velocity of the gas to the water pipe wall by (1/CO8θ), thereby increasing the heat transfer coefficient. Other flow components flow over the baffle, creating a vortex behind the baffle, thereby creating turbulence in the flow near the wall and increasing heat transfer. Due to these fluid elements of the J component, the heat transfer coefficient of the heat transfer surface prepared as shown in FIG. 1 is significantly improved. FIG. 5 is an exploded view of the cylinder. Figure (a) shows g baffles for promoting heat transfer arranged at an angle θ with respect to the gas flow angle. Although such an arrangement has a sufficient effect, if the angle of the baffle is changed midway to θ' as shown in Figure bj, the turbulent flow effect due to the baffle becomes even greater and heat transfer is further improved. The second figure shows an example of a spiral water tube boiler based on the basic idea of promoting heat transfer coefficient as described above.The combustion gas produced by combustion by the burner 5 flows down the combustion chamber, and flows into the inner cylinder 1 and the outer cylinder. 2. At this time, the heat transfer promoting baffle 11 attached to the inner cylinder 1 significantly improves the heat transfer from the combustion gas flow to the water pipe, and the heat retained in the combustion gas is sufficient. As an example of the effect of the heat transfer promoting baffle, a comparison example between a conventional boiler without baffles and a boiler according to the present invention having baffles is shown below. As shown, by installing a heat transfer promoting baffle, the boiler exhaust gas temperature can be lowered by 770℃ and the boiler efficiency can be improved by 4%.Jθθkg/H The fuel consumption of the boiler is 3 yt/H with A heavy oil. and 5%
By improving the efficiency of 200θ~/0.0θOj per year
This results in fuel savings, and the effect is significant. Further, other examples for boilers larger than the above example will be described below. (10) This is page 2 of the 3paBB boiler shown in Figure 2.
This is a comparison between a case where a baffle is attached to the section and a case where a baffle is not attached. By using the heat transfer enhancing baffle of the present invention, boiler efficiency is increased by 5%, resulting in significant fuel savings. Furthermore, in a normal boiler design, the temperature at the turning point from the 1.2paBB section to the J pass section (11) reaches 50θ℃, making it impossible to design the boiler structure using normal steel materials, and this type of boiler was established. It disappears. In contrast, in the design of the present invention, since the temperature is 370° C., common steel materials can be used, thereby expanding the range of application of the spiral water tube boiler to large boilers. As described above, the effects of this invention are remarkable. In the above explanation, an example has been described in which a baffle is attached to the outside of the inner cylinder, but the effects of the present invention are also exhibited when baffles are attached to the inside of the outer cylinder or to both the inner and outer cylinders. . The same applies to the case where a baffle is attached to j pall B in FIG. 4 Brief explanation of the drawings Fig. 1 is a diagram showing an example of a conventional spiral water tube boiler (a
) is a longitudinal section, (b) is a cross section. FIG. 2 is a schematic diagram of a three-pass spiral water tube boiler. FIG. 3 is a conceptual diagram of an annular flow passage. Figure 5 is an exploded view of an annular flow passage with a baffle for promoting heat transfer according to the present invention.The second figure is a diagram showing a spiral water tube boiler according to the present invention. Outer casing (connection pipe) Upper refractory Z Bottom refractory and annular flow path 2 Gas header part 10, exhaust port/X Heat transfer promotion buttful

Claims (1)

[Claims] In a water tube boiler, a water tube is spirally wound into a cylindrical shape with a predetermined diameter. arranged at a certain angle,
Spiral water tube boiler characterized by having a baffle made of round rods, flat plates, etc.