JPS62172102A - Tie-in section structure of boiler furnace wall and rear-section heat transfer wall - 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] <Industrial Application Field> The present invention relates to the structure of a boiler wall, and provides a structure for preventing the occurrence of cracks due to thermal stress in the joint structure between the boiler furnace wall and the rear heat transfer wall. This is related to this.

<Prior art and their melting points> Generally, the boiler wall is formed of a membrane wall made by continuously welding tubes and bars, and the joint between the furnace wall and the rear heat transfer wall has a complex three-dimensional structure between the membrane walls. .

The joint between the furnace wall and the rear heat transfer wall is located on the furnace side wall 1. as shown in FIG. Rokuro Seihan 2. It is composed of a wall 3 and a bottom wall 4, which are welded together to seal the gas inside the furnace.

In this structure, at the joining corner 50, the six walls marked J: intersect at one point. On the other hand, the fluid in the pipe rises up the furnace side wall 1 and is supplied to the rear heat transfer side wall 3 and bottom wall 4 via the ceiling wall, or is branched from the furnace side wall 1 to the bottom wall 4 and ceiling wall 3a, and then flows through the ceiling wall. The fluid inside the tube is supplied to the rear heat transfer wall side wall 3.

FIG. 7 schematically shows the arrangement of the heat exchanger tubes, and a portion of the water tubes on the rear wall 2 constitutes a nose portion 2a, and passes through the rear wall to form the bottom wall 4. A Q moss-suspended secondary superheater is located inside the furnace, and a reheater tube is located downstream of the rear wall tube.

FIG. 8 is a perspective view showing the mutual relationship of the wooden pipes in the joint of such a water pipe, which is a problem in the present invention.

Furthermore, the temperature of the fluid flowing inside these water pipes has a gradient along the flow path, and the temperatures of the six walls are different. Particularly in a transient state such as when a boiler is started or stopped, the temperature difference between each wall is large, and the thermal expansion difference is also large. However,
At the joining corner 5, the six walls with different temperatures are welded together so that they intersect at one point, so the differences in thermal expansion of the six walls are mutually restrained, and strain concentration due to structural rigidity discontinuity is also superimposed. A large thermal stress occurs near the joining corner 5, and in a boiler that operates with frequent startup/stoppages and load changes, this thermal stress is repeated, and a fatigue crack occurs and propagates at this corner, eventually causing a crack. This may lead to pipe leakage.

As mentioned above, due to the structure of the fluid path in the pipe, it is difficult to eliminate the temperature difference between each wall, so we proposed a structure that reduces the generated thermal stress even if there is a temperature difference, and can seal the gas in the furnace. is requested.

<Object of the invention> The object of the invention is to eliminate the above-mentioned drawbacks of the prior art;
Boiler furnace wall and rear heat transfer wall arrangement A that can reduce thermal stress due to temperature difference between each wall without impairing the sealing function of gas in the furnace
It's about making a child.

<Summary of Means> In short, the present invention has a structure in which a slit, an L-shaped bending plate, and a self-adhesive gasket are provided at the joint between the boiler furnace wall and the rear heat transfer wall.

<Example> Next, one embodiment of the present invention will be described with reference to the drawings.

In this embodiment, as shown in FIG. 6, there is a joining line between the furnace side wall 1 and the rear heat transfer side wall 3, and the furnace rear wall 2.

FIG. 1 (an enlarged perspective view of the vicinity of the joining corner 5 of the device according to the present invention), FIG. Weld and fix the rising part of the rice m (one side of the L-shaped bent plate) and the end of the rising side of the pond to the furnace side wall 1 and rear heat transfer side wall 3, and to the furnace rear wall 2 and bottom wall 4. From Slintro The horizontal parts of the two bending plates 8a and 8b are overlapped with each other at a constant interval over the long range.The two bending plates 8a.

A thin cylinder 9 (self-tightening gasket) with a slit 9a along the entire length in the longitudinal direction is provided between the horizontal parts of the bending plate 8b.
A stopper 11 is provided at. A spring 12 with a rough -Ih thread is passed through the horizontal part of the fuku plate 8a, the other end is welded and fixed to the membrane bar 13 of the water pipe 3 of the rear heat transfer wall, and the screw 14 is inserted into the 7J looped part. 1': i A hoof nut 15 is provided. The spring 12 moves at a partial pitch along the slit 6 due to its shallowness.

A bent plate 8 along the slit 6 as shown by a dotted line in FIG.
Attach an end plate to the longitudinal end of a to make the L-shaped cloth-faced box-shaped crack gas-tight. The bending plate 8b and the end plate (make airtight contact and do not weld 1. In other words, the membrane bar 13, the bending plates 8a, 8b, the slit-shaped bowl 9 and the end plate 16 should be connected to each other so that a closed space is formed between them. Weld and join.

Note that when 818B having such a structure is provided at the so-called corner G between the furnace rear wall 2 and the bottom 4, the surface J slit 6
7sA and G cover the 1b-shape, creating a structure that prevents gas leakage from the corners. Its condition is shown in Figure 4 as a cross-sectional plan view of the furnace. FIG. 5 is an a-a view of FIG. 4.

Effect〉 Furnace side wall 1. Furnace rear wall 2. The thermal expansion difference due to the temperature difference between the rear heat transfer side wall 3 and the bottom wall 4 is released by the slit 6 provided near each wall joining corner 5, eliminating mutual restraint, so that no strain concentration occurs. Thermal stress is significantly reduced 10, and the end plate 16i forms a closed space to prevent the furnace gas from flowing out through the slit 6.

If the thickness of the bending plate is set to an appropriate thickness and the tightening nut 15 is adjusted by the spring 12 to receive a tensile force, an appropriate initial surface pressure can be applied to the contact surfaces between the bending plates 8a, 8b and the slit cylinder 9. When given, the restoring force of the spring during boiler operation [
This maintains an appropriate surface pressure, thereby preventing the gas in the furnace from flowing out. The stopper 11 prevents the slit cylinder 9 from curving and the contact surface with the bending plate 8 from shifting due to the in-furnace gas pressure leaking from the slit 6. The cylinder 9 with slits has the function of a so-called self-tightening gasket that expands due to the pressure of the furnace gas flowing in through the slit and increases the contact surface with the bending plate 8.

<Example 2> Another example of the present invention is shown in FIG. Two cylinders 9 with slits are made, the end plate 16 is extended to the position a of the cylinder 9 with slits, and the gas detection port 17 is provided in the bending plate 8.
A gas detection nozzle 18 is provided, to which a conduit 19 and a gas detector 2o are connected.

According to this embodiment, even if in-furnace gas leaks from the contact surface between the inner cylinder with slits 9 and the bending plate, the closed cylinder formed by the outer cylinder with slits 9, the bending plate l, and the end plate 16 Since it is sealed within the space, leakage into the atmosphere is prevented. Furnace gas leaking into the closed space is further detected through gas detection port 1.
Gas leakage is detected as it reaches the gas detector 20 via the 7° scum detection nozzle 18 and the conduit 19, and an alarm is issued, making it possible to perform a gradual shutdown operation by gradually reducing the boiler load, resulting in a rapid shutdown. Damage to various parts of the boiler due to operation can be prevented. Therefore, it has the effect of completely eliminating gas leakage into the atmosphere without causing any damage to the boiler.

Furthermore, if necessary, gas leakage can be more actively prevented by supplying additional EF and gas to the conduit unit 9.

<Effects of the Invention> By carrying out this invention, the thermal stress at each wall joint can be significantly reduced, and the occurrence of fatigue cracks due to repeated thermal stress during start-stop operation can be prevented, resulting in significant savings in life. improve,
It has the effect of enabling high-frequency start-stop and stop-start operations. Furthermore, it prevents thermal stress from occurring in the furnace gas sealing member and maintains an appropriate sealing surface pressure at all times, completely preventing the furnace gas from flowing out and enabling frequent start-stop operations. has.

The slit processing, the processing and attachment of the seal member are easy, and can be adequately handled using existing equipment and techniques, and the seal member can be easily replaced due to deterioration over time.

Furthermore, since the target area is limited to the O-shaped corner near each wall joining corner, the amount of construction work is small and there is no need to extend the boiler construction process.

Furthermore, by carrying out the present invention, I') the sensitive stress at the joint between the furnace wall and the rear heat transfer wall, which has a temperature difference, is reduced to about 1, and the thermal stress caused by starting and stopping the boiler is reduced to approximately 1. By increasing the fatigue life against shocks by about 50 times and eliminating any leakage of gas in the furnace, it is possible to provide a boiler device capable of high-frequency start-stop operations of about 50,000 times.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a joint structure of a boiler furnace wall and a rear heat transfer wall according to a first embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 is a second embodiment of the present invention. 4 is a cross-sectional plan view of the furnace, and FIG. 5 is a cross-sectional view corresponding to the section taken along line A-A of
-c It is a partial cross-sectional pipe arrangement diagram. 1... Water pipe on the side wall of the furnace 2... Rear wall of the furnace 3... Water pipe on the rear heat transfer side wall 4...
・Bottom wall 5... Corner (corner) of the joint 711. '
L (seal member) 6...Slit 8...
...Bending plate members 8a, 8b...Bending plate 10
...Insulation material 11 ...Stopper 12.
- Spring 13... Membrane bar Figure 1 Figure 2? ○ Figure 4

Claims (1)

[Claims] 1. A membrane bar that connects a water pipe on a side wall located at the intersection of the side wall and rear wall of a boiler furnace with a membrane structure and a water pipe forming the wall surface of a rear heat transfer section adjacent to this water pipe. On the other hand, a slit is provided near the corner where the three surfaces of the furnace water wall tube surface, the water tube wall surface of the rear heat transfer wall, and the bottom surface of the rear heat transfer section intersect, and the slit is covered so that the outer shape is approximately L-shaped and box-shaped. A joint structure between a boiler furnace wall and a rear heat transfer wall, characterized in that a cover is provided at the corner. 2. An L-shaped box-shaped cover is attached by welding the ends of one side of a bent plate having an L-shaped cross section to both sides of the slit, and the other sides are free sides facing parallel to form a bent passage. A connecting portion between a boiler furnace wall and a rear heat transfer wall according to claim 1, wherein a self-containing gasket is positioned between the opposing surfaces, and the bent passage is filled with a heat insulating material. structure. 3. L to increase the tightening force of the self-tightening gasket.
3. A joint structure between a boiler furnace wall and a rear heat transfer wall according to claim 2, further comprising a means for tightening the free side of the letter-shaped bent plate.