JPH0812112B2 - Mounting structure of water pipe temperature detector in square multi-tube once-through boiler - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detector mounting structure for detecting a water pipe temperature in a square multi-tube type once-through boiler having a newly developed unique can structure.

[0002]

2. Description of the Related Art Conventionally, for a boiler of a type in which a plurality of water pipes are annularly arranged in a can and an annular combustion gas passage is provided, prevention of overheating of the water pipes, temperature control, detection of scale adhesion in the water pipes, etc. For this purpose, a method of mounting a temperature measuring sensor such as a thermocouple or a thermistor on the water pipe and detecting the temperature of the water pipe by this is adopted, and various mounting structures have been proposed.

However, in recent years, for a square multi-tube type once-through boiler having a newly developed unique can body structure, a mounting structure similar to that of a conventional type boiler (type having an annular combustion gas passage) is sufficient. In reality, it is impossible to achieve the purpose, and an effective mounting structure has not been proposed, and its development is desired. That is, in the can body structure of the rectangular multi-tube once-through boiler, a plurality of water pipes are arranged between a pair of water pipe walls that are parallel to each other, and a combustion burner is arranged at one side opening between the water pipe walls. At the same time, a combustion exhaust gas outlet is formed in the other side opening, and the water pipe is located near the combustion surface of the combustion burner, and the combustion chamber is almost absent. As a result, the combustion gas has a new combustion heat transfer system in which the combustion reaction and the heat transfer action simultaneously proceed in the water tube group space. Therefore, it is desired to develop a mounting structure for a temperature detector that is compatible with such a new combustion heat transfer system. In particular, in this new combustion heat transfer system, the combustion reaction and heat transfer action proceed simultaneously in the water tube group space, so depending on the mounting position of the temperature sensor, it is easily affected by the high temperature combustion flame. There is a problem in that the temperature of the flame changes due to a change in the air ratio, which changes the detected temperature, which makes it impossible to accurately detect the water pipe temperature.

[0004]

SUMMARY OF THE INVENTION In view of the above points, the present invention provides a new combustion heat transfer system for a square multi-tube once-through boiler, in which a water pipe located near the combustion burner is significantly overheated. Based on the finding that it is most likely to be overheated, by providing a temperature sensor mounting structure that is compatible with the new combustion heat transfer method, it is possible to prevent overheating of water pipes, temperature control, or detection of scale adhesion in water pipes. It aims to ensure the safe and efficient operation of a square multi-tube once-through boiler.

[0005]

According to the present invention, a plurality of substantially vertical water pipes are arranged and adjacent water pipes are connected by fins to form one side water pipe wall. The water pipes are arranged so that adjacent water pipes are connected by fins to form the water pipe wall on the other side, and the water pipe walls are arranged so as to be parallel to each other, and the water pipe walls are arranged between the water pipe walls. In a rectangular multi-tube once-through boiler in which a plurality of substantially vertical water pipes are arranged, a combustion burner is arranged at one side opening between the water pipe walls, and a combustion exhaust gas outlet is formed at the other side opening. , Arranging the combustion burner so as to be displaced downward at the one side opening,
Of the water pipes of the water pipe wall on the other side, a mounting base of the temperature measuring sensor is fixed to the outer peripheral surface of the upper end of the water pipe close to the combustion burner by penetrating the fin-shaped member in the horizontal direction. The tip portion projecting inward of the side water pipe wall is located in the gas flow separation area of the fixed water pipe, and is located outside the other side water pipe wall.
Further, the temperature measuring sensor is tightly inserted and held in the mounting base .

[0006]

In the present invention, the combustion burner is arranged so as to be displaced downward at the one side opening between the water pipe walls,
Also, since the temperature sensor mounting base is fixed to the upper end of the water pipe forming the wall of the water pipe near the combustion burner, the flame temperature received by the mounting base will be low and the heat flux will be low. Therefore, the effect of flame temperature is reduced. Further, although the radiant heat transfer is large from the lower side, the amount of radiant heat in the upward direction and the lateral direction is small, and the radiant heat transfer received by the mounting base is small as a whole. further,
The amount of exposure to hot combustion gas is small, and even if exposed to this combustion gas, the tip protruding inside the water pipe wall of the mounting base is located in the gas flow separation area of the fixed water pipe. Since the local heat transfer coefficient is low in the gas flow separation region, heating of the mounting base due to convective heat transfer of the combustion gas can be suppressed as much as possible. As a result, the amount of heat transferred from the combustion flame and the combustion gas to the mounting pedestal is reduced, and the temperature change of the temperature measuring sensor is reduced even if the temperatures of the combustion flame and the combustion gas are changed. As a result, the temperature of the water pipe is accurately detected. Further, the mounting base is penetrated through the fin-shaped member and fixed.
Attach it to the landing pipe and take the temperature sensor from the outside of the water pipe wall.
Since it has a structure that it is inserted and held tightly inside the pedestal with a temperature
Allows maintenance of the sensor from the outside surface of the boiler
It

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 3 show an embodiment of a water pipe temperature detector mounting structure according to the present invention. Further, FIG. 4 is an explanatory view schematically showing the local heat transfer coefficient.

In the drawings, a can body 1 forming the basic shape of a square multi-tube type once-through boiler is composed of substantially vertical water pipes 2A, 2
A, ..., 2B, 2B, ..., 2C, 2C, ...
., 2D, 2D, ... And 2E, 2E ,. Each of these water pipes 2A to 2E is arranged in parallel in a plurality of columns in parallel, and each column arrangement constitutes a group of five water pipes, and is formed in a vertically long rectangular shape as a whole. Of these water pipes 2A to 2E, the water pipe groups 2A and 2E located on the outer sides of both sides are such that adjacent ones are connected to each other by the fin-shaped members 3, 3, ... The one side water pipe wall 4 and the other side water pipe wall 5 that are arranged to face each other and define unburned and burned gas passages are formed. A combustion burner 8 having a planar shape with a primary air system is displaced downward from the center of the opening 6 in the vertical direction in the opening 6 on one side of both the water pipe walls 4 and 5. A combustion exhaust gas outlet 9 is formed in a part of the other side opening portion 7, so that unburned and burned gas is basically discharged from each of the water pipes 2A to 2A.
It is configured to flow in one direction (from left to right in FIG. 2) in a direction orthogonal to 2E. The one side opening 6
And the other side opening 7, the water pipe walls 4, 5 and the upper header 1
0, the left and right openings of the can body 1 formed by the lower header 11, strictly speaking, the openings excluding the refractory members 12, 12.

The water pipes 2A to 2E are arranged in a staggered manner with respect to the water pipes of the water pipe groups adjacent to each other, and the gaps between them are set to be substantially equal to or less than the diameter of the water pipes.

The rectangular can 1 having the above-mentioned structure is a combustion bar.
Almost no combustion chamber is formed in the front of the burner 8 , that is, the water pipe is located near the combustion surface of the combustion burner,
The mixture of primary air and fuel gas is burned at a low temperature between the water tube groups to suppress the amount of nitrogen oxides generated.

Side walls 13 and 14 are attached to the outer sides of both the water pipe walls 4 and 5 at appropriate intervals, respectively, and the side walls 13 and 14 of the water pipe walls 4 and 5 and the both side walls 13 and 14 are attached. Spaces 15 and 16 that are substantially sealed are formed between them. Both spaces 15 and 16 are provided so as not to leak out of the can body 1 when the combustion gas leaks from the water pipe walls 4 and 5, but the deformation due to the internal pressure of the side walls 13 and 14 is prevented. In order to prevent the other side water pipe wall 5 from communicating with the combustion exhaust gas outlet 9 at a position close to the combustion exhaust gas outlet 9.
An appropriate communication hole (not shown) is formed on the fin-shaped member 3 or its extension.

Now, the mounting pedestal 17 which is the main part of the present invention
The mounting pedestal 17 has the temperature measuring sensor 18 tightly inserted and held therein, and plays an important role for accurate temperature detection, and its mounting position is particularly problematic. Regarding the amount of heat transfer in the mounting base 17, the amount of radiant heat transfer is expressed by the following equation 1. Q ₁ = ΦA (TF ⁴ −TC ⁴ ) where Φ: emissivity, A: heat transfer area (m ² ), TF: combustion gas temperature (K), TC: water pipe wall temperature (K), and convection heat transfer The quantity is expressed by the following Equation 2. Q ₂ = αA (TF-TC) where α is the heat transfer coefficient

When the sum of the heat transfer amounts of both is large, the difference between the tip temperature of the mounting pedestal 17 and the wall temperature of the water pipe becomes large, and thermal stress is generated. As a result, the mounting base 17 and / or the water pipe will be damaged. Further, when the amount of heat transfer becomes large, a temperature gradient is generated between the water pipe and the tip of the mounting base 17, and the temperature change of the temperature measuring sensor 18 due to the change of the combustion gas temperature (TF) becomes large, so that the accurate water pipe wall The temperature of can not be detected.

Therefore, in the embodiment of the present invention, the mounting pedestal 17 of the temperature measuring sensor 18 is located near the combustion burner 8 among the water tubes forming the water tube wall 5 on the other side, and the upper end of the water tube 2E ₁ that is most likely to overheat. It adheres to the outer peripheral surface of the part. Mounting base 17
Is made of the same material as the water pipe 2E ₁ that secures it _, eg SS
It is formed by wood and SB material or the like, the diameter of the inner peripheral surface thereof is equal to the outer diameter of the fixing water pipes 2E _1, is fixed by welding or the like in close contact with the fixed water pipe 2E _1. The mounting position of the mounting pedestal 17 is preferably as far as possible from the combustion burner 8 in the fixed water pipe 2E ₁ , and a position of 200 mm from the upper end of the combustion burner 8 is preferable, but depending on the implementation, It is also effective above this. further,
The mounting pedestal 17 is fixed in a state of penetrating the fin-shaped member 3 from the outer side to the inner side of the water pipe wall 5 on the other side, and the tip portion of the mounting pedestal 17 protruding to the inner side of the water pipe wall 5 on the other side. 17A
However, the position is within the gas flow separation area X _{1 of} the fixed water pipe 2E ₁ .

The mounting pedestal 17 has a bottomed hole 19 formed therein for tightly holding a temperature measuring sensor 18 such as a thermocouple or thermistor. The bottomed hole 19 has an opening (reference numeral). (Omitted) is open to the outside of the fin-shaped member 3. Then, the lead wire 20 of the temperature measuring sensor 18 is led out of the can body 1 through the opening of the bottomed hole 19.

Here, the gas flow separation region X of the fixed water pipe 2E ₁
Referring to _1, the gas flow separation area X ₁ is, as shown in FIG. 1, refers to the range of about 90 degrees in the upstream direction of gas flow G the fin member 3 on the downstream side of the gas flow G as a reference line At the separation point H, the gas flow G separates from the wall surface of the fixed water pipe 2E ₁ .

In the above embodiment, the combustion gas flow of the combustion burner 8 flows in a substantially horizontal direction in the middle stage and rises up and down on both upper and lower sides, as shown in FIG. 3 , and intersects with the water tube groups 2A to 2E, respectively. It flows in the state of being. Then, the combustion gas flows while the combustion reaction and the heat transfer action simultaneously proceed in the space of each of the water tube groups 2A to 2E, so that the combustion gas contains the combustion flame. The combustion gas temperature distribution in the vertical direction, that is, the combustion flame temperature distribution in the water pipe 2E ₁ to which the mounting base 17 is fixed is as shown in FIG.
It becomes about 1200 to 1300 degrees at 8 parts of the combustion burner and about 1000 degrees at the position of the mounting pedestal 17. Therefore, the heat quantity A from the downward direction of the radiant heat received from the combustion flame of the mounting pedestal 17 and the heat quantity B from the other upward and leftward directions are obtained by the equation 1, respectively. The value is as low as about 1/2.

The amount of convective heat transfer by the combustion gas flow received by the mounting pedestal 17 is small in the vicinity of the upper end of the fixed water pipe 2E ₁ because the combustion burner 8 is deviated downward, and the mounting pedestal 17 is Is exposed to the combustion gas flow, and even when exposed to the combustion gas, the tip portion 17A protruding inside the water pipe wall 5 on the other side of the mounting pedestal 17 has a fixed water pipe 2
Since it is fixed so as to be located in the gas flow separation area X ₁ of E ₁ , the local heat transfer coefficient is low in the gas flow separation area X ₁ .
There is little heat transfer to the mounting base 17 due to convective heat transfer of the combustion gas. The local heat transfer coefficient around the fixed water pipe 2E ₁ is schematically shown in FIG.

As described above, the heat transfer amount from the combustion flame and the combustion gas to the mounting pedestal 17 can be reduced, and as a result, even if the temperature of the combustion flame and the combustion gas changes, the temperature measuring sensor 18
The temperature change of the part is reduced, and the temperature of the fixed water pipe 2E ₁ can be accurately detected.

The present invention is not limited to the above embodiment, but various modifications and additions can be made according to the embodiment. For example, a pair of water pipe walls having mounting bases 17 parallel to each other can be used. Of the water pipes forming the one-side water pipe wall 4 out of 4, 5, it is also preferable that the water pipe 2A ₁ near the combustion burner 8 is fixed. Further, a configuration in which the mounting pedestal 17 is fixed to each of the water pipes 2A ₁ and 2E ₁ of the both water pipe walls 4 and 5 and the temperature of the two water pipes is detected is also suitable depending on the implementation. Further, it is also preferable that the mounting pedestal 17 is fixed not to the water pipes forming the water pipe walls 4 and 5 but to the water pipe near the combustion burner 8 which easily overheats.

[0021]

As described above, according to the present invention, the radiant heat transfer amount from the combustion flame and the convective heat transfer amount from the combustion gas received by the mounting base of the temperature measuring sensor can be minimized, and the combustion flame can be minimized. Also, even if the temperature of the combustion gas changes due to the change of the air ratio, it is possible to reduce the influence thereof, and thus it is possible to accurately detect the temperature of the water pipe. In addition, it is possible to prevent the mounting pedestal from peeling off or dropping due to heat transfer from the combustion flame and the combustion gas even during long-term operation, and it is possible to provide a temperature detector mounting structure having excellent durability. As a result, it is possible to provide a temperature detector mounting structure adapted to a new combustion system in which the combustion reaction and the heat transfer action simultaneously proceed in the water tube group space. In addition, the mounting base is made to penetrate the fin-shaped member.
The temperature sensor to the front of the water pipe wall from the outside.
Since the structure is inserted and held tightly in the mounting base,
Easy maintenance of temperature sensor from outside of boiler
It can be carried out. Furthermore, this mounting structure allows the square multi-tube once-through boiler to be operated safely and efficiently, and is therefore extremely effective as this type of mounting structure.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a main part of an embodiment of a mounting structure according to the present invention.

FIG. 2 is an explanatory plan view showing an arrangement of water tubes in a can body structure of a square multi-tube once-through boiler.

FIG. 3 is a side explanatory view in which a part in the direction of arrow III in FIG. 2 is cut away.

FIG. 4 is an explanatory diagram schematically showing local heat transfer coefficients around a water pipe 2E ₁ .

[Explanation of symbols]

1 can body 2A water pipe 2A ₁ fixed water pipe 2B water pipe 2C water pipe 2D water pipe 2E water pipe 2E ₁ fixed water pipe 3 fin member 4 one side water pipe wall 5 other side water pipe wall 6 one side opening 7 other side opening 8 combustion burner 9 Combustion exhaust gas outlet 17 Mounting base 17A Tip 18 Temperature measurement sensor X ₁ Gas flow separation area

Claims (2)

[Claims] 1. A plurality of substantially vertical water pipes 2A, 2A ,.
.. Arranged between adjacent water pipes 2A to form fins 3,
Are connected to form one side water pipe wall 4, and a plurality of substantially vertical water pipes 2E, 2E, ... Are arranged so that fins 3 and 3 are provided between adjacent water pipes 2E. , To form the water pipe wall 5 on the other side, and the water pipe walls 4 and 5 are arranged to face each other so as to be parallel to each other.
A plurality of water pipes 2B, 2B, ...
, C, 2C, ..., 2D, 2D, ... are arranged, a combustion burner 8 is arranged in one side opening 6 between the water pipe walls 4, 5, and a combustion exhaust gas is formed in the other side opening 7. In a square multi-tube once-through boiler having an outlet 9, the combustion burner 8 is arranged so as to be displaced downward at the one side opening 6, and the one of the water tubes 2E of the other side water tube wall 5 is On the outer peripheral surface of the upper end of the water pipe 2E ₁ near the combustion burner 8, the mounting base 1 for the temperature sensor 18 is installed.
7 through the fin-shaped member 3 in the horizontal direction to fix it,
Further, the tip portion 17A of the mounting pedestal 17 projecting inside the other side water pipe wall 5 is located in the gas flow separation region X ₁ of the fixed water pipe 2E ₁ , and the outside side of the other side water pipe wall 5 is Taking
A mounting structure for a water pipe temperature detector in a rectangular multi-tube once -through boiler, characterized in that a temperature measuring sensor 18 is tightly inserted and held in a pedestal 17 with an attached. 2. The mounting pedestal 17 is also fixed to the outer peripheral surface of the upper end portion of the water pipe 2A ₁ near the combustion burner 8 of the one side water pipe wall 4, and the tip portion 17A is fixed to the gas of the fixed water pipe 2A ₁ . Located inside the flow separation area X ₁ and outside the one-side water pipe wall 4.
Insert the temperature sensor 18 into the mounting base 17 from the side
Mounting structure of the water pipe temperature detector in the square-tube once-through boiler according to claim 1, characterized in that by entering retained.