Patent Description:
In an exhaust heat recovery boiler, water flowing through a heat exchanger tube is converted into steam by utilizing heat of exhaust gas, and with this, heat energy is recovered from the exhaust gas. When the exhaust gas supplied to the exhaust heat recovery boiler contains a large amount of dust, the dust accumulates on the heat exchanger tube, and this lowers recovery efficiency of the heat energy. As a countermeasure against this, an exhaust heat recovery boiler including a hammering rod is being proposed (see PTL <NUM>, for example). The hammering rod is connected to the heat exchanger tube. By applying impact to the hammering rod from outside, the impact is transferred to the heat exchanger tube, and the dust accumulating on the heat exchanger tube falls. Thus, the recovery efficiency of the heat energy can be prevented from lowering.

In the exhaust heat recovery boiler, the heat exchanger tube is provided in a duct casing through which the exhaust gas flows. In the duct casing, the hammering rod is connected to the heat exchanger tube. Moreover, an upper part of the hammering rod projects to an outside of the duct casing and is strongly hit by an external mechanism. To be specific, since the hammering rod penetrates the duct casing, a seal between the hammering rod and the duct casing needs to be realized.

Moreover, both of the heat exchanger tube and the duct casing expand by the heat of the exhaust gas. However, since the water flows in the heat exchanger tube, the temperature of the heat exchanger tube does not increase significantly. On the other hand, the temperature of the duct casing increases to a temperature close to the temperature of the exhaust gas. Therefore, the amount of thermal expansion of the duct casing is larger than that of the heat exchanger tube, and the duct casing is displaced relative to the hammering rod. Even when the duct casing is displaced relative to the hammering rod as above, the seal between the hammering rod and the duct casing needs to be maintained.

The present invention was made under these circumstances, and an object of the present invention is to provide an exhaust heat recovery boiler configured such that even when a duct casing is displaced relative to a hammering rod, high seal performance between the hammering rod and the duct casing can be maintained. An exhaust heat-recovery boiler featuring a hammering rod form cleaning the boiler tubes is known from <CIT>.

According to one aspect of the present invention, the above object is achieved by an exhaust heat recovery boiler according to claim <NUM>.

According to the exhaust heat recovery boiler, the seal is realized between the lower surface of the sleeve and the upper flat surface of the extending portion. To be specific, since the seal is realized between the surfaces, a contact area is large, and therefore, high seal performance can be obtained. Moreover, when the high-temperature exhaust gas flows in the duct casing, the duct casing is displaced relative to the hammering rod. Therefore, the extending portion extending from the duct casing is displaced relative to the sleeve attached to the hammering rod. As described above, the contact area between the sleeve and the extending portion is large. Therefore, even when the sleeve is displaced relative to the extending portion, high seal performance can be maintained.

In the above exhaust heat recovery boiler, the upper flat surface of the extending portion may be in surface-contact with the lower surface of the sleeve.

According to the exhaust heat recovery boiler, since the upper flat surface of the extending portion and the lower surface of the sleeve are in surface-contact with each other, high seal performance between the hammering rod and the duct casing can be maintained although the configuration is simple.

The exhaust heat recovery boiler according to another aspect may further include one or a plurality of seal plates located between the lower surface of the sleeve and the upper flat surface of the extending portion and formed in an annular shape.

According to the exhaust heat recovery boiler, the seal between the lower surface of the sleeve and the upper flat surface of the extending portion is realized by using one or a plurality of seal plates. When the extending portion is displaced relative to the sleeve, the seal plates are slightly displaced relative to each other and gradually fit each other. With this, high seal performance between the hammering rod and the duct casing can be maintained.

The exhaust heat recovery boiler according to yet another aspect may further include a plurality of seal plates located between the lower surface of the sleeve and the upper flat surface of the extending portion and formed in an annular shape. The plurality of seal plates may include a first seal plate having a thickness which decreases as the first seal plate extends outward in a radial direction and a second seal plate arranged adjacent to the first seal plate and having a thickness which increases as the second seal plate extends outward in the radial direction.

The exhaust heat recovery boiler includes the first and second seal plates that are so-called tapered plates. Therefore, even when the lower surface of the sleeve is inclined relative to the upper flat surface of the extending portion, or even when the sleeve rattles, the seal plates can fit each other. On this account, high seal performance between the hammering rod and the duct casing can be maintained.

In the above exhaust heat recovery boiler, during a cold state in which the exhaust gas is not flowing in the duct casing, a central axis of the extending portion may be located closer to a middle side of the duct casing than a central axis of the hammering rod.

According to the exhaust heat recovery boiler, during the cold state, the central axis of the extending portion is located closer to the middle side of the duct casing than the central axis of the hammering rod. Therefore, during the hot state in which the exhaust gas is flowing in the duct casing, the central axis of the extending portion approaches the central axis of the hammering rod. As a result, during the hot state, positional deviation between a central axis of the lower surface of the sleeve and a central axis of the upper flat surface of the extending portion decreases, and therefore, high seal performance between the hammering rod and the duct casing can be maintained.

In the above exhaust heat recovery boiler, the extending portion may include: a cylindrical main body portion extending upward from the duct casing; and an annular horizontal portion extending outward in a radial direction from an upper end part of the main body portion and including an upper surface constituting the upper flat surface.

According to the exhaust heat recovery boiler, the upper surface of the horizontal portion extending outward in the radial direction from the upper end part of the main body portion constitutes the upper flat surface of the extending portion. Therefore, the upper flat surface of the extending portion can be easily formed.

The above exhaust heat recovery boiler may further include a bellows covering a boundary between the sleeve and the extending portion. The extending portion may include an outer wall portion extending downward from a radially outer end part of the horizontal portion. The bellows may include an upper end part fixed to an outer peripheral surface of the sleeve and a lower end part fixed to the outer wall portion of the extending portion.

Since the exhaust heat recovery boiler includes the bellows covering the boundary between the sleeve and the extending portion, the seal performance between the hammering rod and the duct casing can be improved. In addition, since the lower end part of the bellows is fixed to not the main body portion, which is high in temperature, of the extending portion but the outer wall portion located outside the main body portion in the radial direction, thermal damage of the bellows can be prevented.

In the above exhaust heat recovery boiler, the hammering rod may include: a circular column portion penetrating the sleeve and having a circular section; a square column portion having a square section, a coupling member being fixed to the square column portion, the heat exchanger tube being coupled to the square column portion through the coupling member; and an intermediate portion located between the circular column portion and the square column portion and formed in such a curved shape that a section of the intermediate portion changes from a circular shape to a square shape as the intermediate portion extends from the circular column portion toward the square column portion.

According to the exhaust heat recovery boiler, since the portion of the hammering rod which portion penetrates the sleeve has the circular section, the seal between the hammering rod and the sleeve can be easily realized. Moreover, since the portion of the hammering rod to which portion the coupling member is fixed has the square section, the fixing of the coupling member to the hammering rod can be easily performed. In addition, since the hammering rod includes the intermediate portion located between the circular column portion and the square column portion and formed in the curved shape, the dust can be prevented from accumulating at the boundary between the circular column portion and the square column portion.

As described above, according to the above configuration, the present invention can provide the exhaust heat recovery boiler configured such that even when the duct casing is displaced relative to the hammering rod, high seal performance between the hammering rod and the duct casing can be maintained.

First, an exhaust heat recovery boiler <NUM> according to Embodiment <NUM> will be described with reference to <FIG>. <FIG> is a sectional view showing the exhaust heat recovery boiler <NUM>. <FIG> is an enlarged view showing an upper part of a hammering rod shown in <FIG> and its periphery. <FIG> is a diagram during a cold state in which exhaust gas is not supplied to the exhaust heat recovery boiler <NUM>.

The exhaust heat recovery boiler <NUM> is a facility configured to recover heat energy from the exhaust gas. A plurality of exhaust heat recovery boilers <NUM> according to the present embodiment are provided so as to be stacked on each other in an upper-lower direction. As shown in <FIG>, the exhaust heat recovery boiler <NUM> according to the present embodiment includes a duct casing <NUM>, extending portions <NUM>, heat exchanger tubes <NUM>, hammering rods <NUM>, and sleeves <NUM>. Moreover, as shown in <FIG>, the exhaust heat recovery boiler <NUM> according to the present embodiment includes bellows <NUM>. The following will describe these components in order.

The duct casing <NUM> is a member constituting part of a duct in which the exhaust gas flows. Upper and lower surfaces of the duct casing <NUM> are open. The duct casing <NUM> is formed in a tubular shape having a substantially rectangular section. In the present embodiment, the exhaust gas flows downward in the duct casing <NUM>. Moreover, the exhaust gas flowing in the duct casing <NUM> contains a large amount of dust. The exhaust gas of the present embodiment is assumed to be exhaust gas generated in the process of manufacturing cement. However, the exhaust gas is not limited to this. Furthermore, the duct casing <NUM> includes a recess <NUM> formed such that an outer surface of the duct casing <NUM> is concave inward. The recess <NUM> is located at an upper portion of one longitudinal end side (left side on a paper surface of <FIG>) of the duct casing <NUM>, and the below-described extending portion <NUM> is provided at the recess <NUM>.

The extending portion <NUM> is a tubular member extending upward from the duct casing <NUM>. As described above, the extending portion <NUM> is provided at the recess <NUM> of the duct casing <NUM>. As shown in <FIG>, the extending portion <NUM> includes a cylindrical main body portion <NUM> extending upward from the duct casing <NUM>, an annular horizontal portion <NUM> extending outward in a radial direction from an upper end part of the main body portion <NUM>, and a cylindrical outer wall portion <NUM> extending downward from a radially outer end part of the horizontal portion <NUM>. An upper surface of the horizontal portion <NUM> is an annular flat surface (horizontal surface) and constitutes an upper flat surface <NUM>. The upper flat surface <NUM> is located at an upper end of the extending portion <NUM> and is in surface-contact with a lower surface of the below-described sleeve <NUM> to realize a seal between the upper flat surface <NUM> and the lower surface of the sleeve <NUM>.

The heat exchanger tubes <NUM> are located in the duct casing <NUM>, and the exhaust gas flows along outer surfaces of the heat exchanger tubes <NUM>. The exhaust heat recovery boiler <NUM> according to the present embodiment includes a plurality of heat exchanger tubes <NUM>, and the heat exchanger tubes <NUM> are arranged at regular intervals in a width direction (direction vertical to the paper surface of <FIG>). Each of the heat exchanger tubes <NUM> extends in a horizontal direction (left-right direction on the paper surface of <FIG>) while making a turn plural times. Water is supplied to each heat exchanger tube <NUM> through a water feed header <NUM>. The water supplied to each heat exchanger tube <NUM> is converted into steam by heat energy of the exhaust gas. After the steam is once recovered by a steam header <NUM>, the steam is supplied to a steam turbine (not shown).

Both of the heat exchanger tube <NUM> and the duct casing <NUM> expand by the heat of the exhaust gas. However, since the water flows in the heat exchanger tube <NUM>, the temperature of the heat exchanger tube <NUM> does not increase significantly. On the other hand, the temperature of the duct casing <NUM> increases to a temperature close to the temperature of the exhaust gas. Therefore, during a hot state in which the exhaust gas is flowing in the duct casing <NUM>, the thermal expansion of the duct casing <NUM> is larger than the thermal expansion of the heat exchanger tube <NUM>. The steam header <NUM> to which each heat exchanger tube <NUM> is connected is supported by the duct casing <NUM> through a supporting member <NUM>. Therefore, in the vicinity of the steam header <NUM>, the duct casing <NUM> is hardly displaced relative to the heat exchanger tube <NUM>. On the other hand, in a region (left side on the paper surface of <FIG>) opposite to a position where the steam header <NUM> is provided, the duct casing <NUM> is relatively largely displaced relative to the heat exchanger tube <NUM>.

The hammering rod <NUM> is a member which applies impact to the heat exchanger tubes <NUM> to make the dust, accumulating on the heat exchanger tubes <NUM>, fall. The hammering rod <NUM> is connected to the heat exchanger tubes <NUM> in the duct casing <NUM> and passes through an inside of the extending portion <NUM>. The hammering rod <NUM> includes the upper part projecting to an outside of the extending portion <NUM>. When the upper part of the hammering rod <NUM> is hit by an external mechanism, the impact is applied to the hammering rod <NUM>, and the impact is transferred to each heat exchanger tube <NUM>.

The hammering rod <NUM> includes: a circular column portion <NUM> including the upper part; a square column portion <NUM> including a lower part; and an intermediate portion <NUM> located between the circular column portion <NUM> and the square column portion <NUM>, and these portions are integrally formed. The circular column portion <NUM> penetrates the below-described sleeve <NUM> and is formed to have a circular section. Since the portion penetrating the sleeve <NUM> has the circular section as above, the seal (seal by using a below-described packing <NUM>) between the sleeve <NUM> and the hammering rod <NUM> can be realized more easily than when the section has a shape other than the circular shape.

The square column portion <NUM> is a portion to which the heat exchanger tubes <NUM> are connected. The square column portion <NUM> is located in the duct casing <NUM>. <FIG> is a horizontal sectional view showing the square column portion <NUM>. As shown in <FIG>, the square column portion <NUM> has a square section and includes a pair of vertical surfaces <NUM> and a pair of parallel surfaces <NUM>. The vertical surfaces <NUM> are vertical to an extending direction (left-right direction on the paper surface of <FIG>) of the heat exchanger tube <NUM>, and the parallel surfaces <NUM> are parallel to the extending direction of the heat exchanger tube <NUM> and perpendicular to the vertical surfaces <NUM>.

One of the heat exchanger tubes <NUM> which are located adjacent to each other in the width direction (upper-lower direction on the paper surface of <FIG>) is coupled to one of the parallel surfaces <NUM>, and the other heat exchanger tube <NUM> is connected to the other parallel surface <NUM>. Moreover, each heat exchanger tube <NUM> is coupled to the square column portion <NUM> through a plate-shaped coupling member <NUM>. The coupling member <NUM> is fixed to the hammering rod <NUM> by welding. In the present embodiment, the section of the portion to which the heat exchanger tube <NUM> is coupled is square. With this, the coupling member <NUM> is easily fixed to the hammering rod <NUM>, and the heat exchanger tube <NUM> can be firmly connected to the hammering rod <NUM>.

As described above, the intermediate portion <NUM> is a portion located between the circular column portion <NUM> and the square column portion <NUM>. The intermediate portion <NUM> is formed in such a curved shape that a section of the intermediate portion <NUM> changes from a circular shape to a square shape as the intermediate portion <NUM> extends from the circular column portion <NUM> toward the square column portion <NUM>. If the hammering rod <NUM> does not include the intermediate portion <NUM>, the dust accumulates on portions (corner portions and the like) of an upper surface of the square column portion <NUM> which portions protrude from the circular column portion <NUM>. However, since the hammering rod <NUM> includes the intermediate portion <NUM> in the present embodiment, the dust can be prevented from accumulating on the square column portion <NUM>.

Moreover, as shown in <FIG>, during the cold state in which the exhaust gas is not flowing in the duct casing <NUM>, a central axis <NUM> of the extending portion <NUM> is located closer to a middle side of the duct casing <NUM> than a central axis <NUM> of the hammering rod <NUM>. As described above, during the hot state in which the exhaust gas is flowing in the duct casing <NUM>, the duct casing <NUM> is relatively largely displaced relative to the heat exchanger tube <NUM> in the region opposite to the position where the steam header <NUM> is provided. Therefore, although the central axis <NUM> of the extending portion <NUM> is not aligned with the central axis <NUM> of the hammering rod <NUM> during the cold state, the central axis <NUM> of the extending portion <NUM> approaches the central axis <NUM> of the hammering rod <NUM> during the hot state.

The sleeve <NUM> is a member attached to the upper part (circular column portion <NUM>) of the hammering rod <NUM>. In other words, the hammering rod <NUM> penetrates an inside of the sleeve <NUM>. The sleeve <NUM> has an annular shape (cylindrical shape having a certain thickness or more), and the lower surface of the sleeve <NUM> is formed horizontally. Moreover, the sleeve <NUM> is attached to the hammering rod <NUM> through the packing <NUM>. When impact is applied to the hammering rod <NUM>, the hammering rod <NUM> is displaced relative to the sleeve <NUM> in the upper-lower direction to some extent. Furthermore, an annular cover <NUM> is attached to an upper surface of the sleeve <NUM> so as to cover the packing <NUM>.

In the present embodiment, the lower surface of the sleeve <NUM> is in surface-contact with the upper flat surface <NUM> of the extending portion <NUM>, and the seal is realized between the lower surface of the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM>. To be specific, in the present embodiment, since the seal is realized between the surfaces, a contact area is large, and therefore, high seal performance can be secured. It should be noted that the lower surface of the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM> are not fixed to each other, and the sleeve <NUM> is movable relative to the extending portion <NUM> in the horizontal direction.

As described above, during the hot state, in the region opposite to the position where the steam header <NUM> is provided, the duct casing <NUM> is relatively largely displaced relative to the heat exchanger tube <NUM>. Therefore, the extending portion <NUM> extending from the duct casing <NUM> is displaced relative to the sleeve <NUM> attached to the hammering rod <NUM>. In the present embodiment, the contact area between the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM> is large as described above. Therefore, even when the extending portion <NUM> is displaced relative to the sleeve <NUM>, high seal performance can be maintained.

The bellows <NUM> is a member covering a boundary between the extending portion <NUM> and the sleeve <NUM>. Since the bellows <NUM> covers the boundary between the extending portion <NUM> and the sleeve <NUM>, the seal performance between the hammering rod <NUM> and the duct casing <NUM> can be improved. An upper end part of the bellows <NUM> is fixed to an outer peripheral surface of the sleeve <NUM>, and a lower end part of the bellows <NUM> is fixed to the outer wall portion <NUM> of the extending portion <NUM>. Since the lower end part of the bellows <NUM> is fixed to not the main body portion <NUM>, which is high in temperature, but the outer wall portion <NUM>, thermal damage of the bellows can be prevented.

The bellows <NUM> is fixed to the outer peripheral surface of the sleeve <NUM> and the outer wall portion <NUM> of the extending portion <NUM> by using fixing members <NUM>. As the fixing members <NUM>, bolts, belts, or the like may be adopted.

Next, an exhaust heat recovery boiler <NUM> according to Embodiment <NUM> will be described with reference to <FIG> is an enlarged view showing the upper part of the hammering rod <NUM> according to Embodiment <NUM> and its periphery and corresponds to <FIG> of Embodiment <NUM>. As shown in <FIG>, the exhaust heat recovery boiler <NUM> according to the present embodiment is different in configuration from the exhaust heat recovery boiler <NUM> according to Embodiment <NUM> in that the exhaust heat recovery boiler <NUM> includes two seal plates <NUM> located between the lower surface of the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM>. Other than the above, the exhaust heat recovery boiler <NUM> according to the present embodiment is the same in configuration as the exhaust heat recovery boiler <NUM> according to Embodiment <NUM>.

Each of the seal plates <NUM> is formed in an annular shape and may be made of metal or silicon. Moreover, the exhaust heat recovery boiler <NUM> of the present embodiment includes two seal plates <NUM> but may include only one seal plate <NUM> or three or more seal plates <NUM>. It should be noted that the seal plates <NUM> are not fixed to each other and are not fixed to the lower surface of the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM>.

As above, in the present embodiment, the seal between the lower surface of the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM> is realized by using the seal plates <NUM>. When the extending portion <NUM> is displaced relative to the sleeve <NUM> during the hot state, the seal plates <NUM> are slightly displaced relative to each other and gradually fit each other. With this, high seal performance between the hammering rod <NUM> and the duct casing <NUM> can be maintained.

Next, an exhaust heat recovery boiler <NUM> according to Embodiment <NUM> will be described with reference to <FIG> is an enlarged view showing the upper part of the hammering rod <NUM> according to Embodiment <NUM> and its periphery and corresponds to <FIG> of Embodiment <NUM> and <FIG> of Embodiment <NUM>. As shown in <FIG>, as with Embodiment <NUM>, the exhaust heat recovery boiler <NUM> according to the present embodiment is different in configuration from the exhaust heat recovery boiler <NUM> according to Embodiment <NUM> in that the exhaust heat recovery boiler <NUM> includes two seal plates <NUM> located between the upper flat surface <NUM> of the extending portion <NUM> and the lower surface of the sleeve <NUM>. It should be noted that the exhaust heat recovery boiler <NUM> according to the present embodiment is different in configuration from the exhaust heat recovery boiler <NUM> according to Embodiment <NUM> in that in the present embodiment, the seal plates <NUM> are so-called tapered plates. Other than the above, the exhaust heat recovery boiler <NUM> according to the present embodiment is the same in configuration as the exhaust heat recovery boiler <NUM> according to Embodiment <NUM> and the exhaust heat recovery boiler <NUM> according to Embodiment <NUM>.

In the present embodiment, the two seal plates <NUM> are constituted by a first seal plate <NUM> and a second seal plate <NUM>. The first seal plate <NUM> is arranged above and adjacent to the second seal plate <NUM> and is formed such that a thickness of the first seal plate <NUM> decreases as the first seal plate <NUM> extends outward in the radial direction. On the other hand, the second seal plate <NUM> is arranged under and adjacent to the first seal plate <NUM> and is formed such that a thickness of the second seal plate <NUM> increases as the second seal plate <NUM> extends outward in the radial direction. It should be noted that the seal plates <NUM> and <NUM> are not fixed to each other and are not fixed to the lower surface of the sleeve <NUM> and the upper flat surface <NUM> of the extending portion <NUM>.

Claim 1:
An exhaust heat recovery boiler comprising:
a duct casing (<NUM>) in which exhaust gas flows;
a tubular extending portion (<NUM>) extending upward from the duct casing (<NUM>);
a heat exchanger tube (<NUM>) located in the duct casing (<NUM>);
a hammering rod (<NUM>) connected to the heat exchanger tube (<NUM>) in the duct casing (<NUM>) and passing through an inside of the extending portion (<NUM>), the hammering rod (<NUM>) including an upper part projecting to an outside of the extending portion; and
an annular sleeve (<NUM>) attached to the upper part of the hammering rod (<NUM>) through a packing (<NUM>),
wherein the extending portion (<NUM>) includes an upper surface (<NUM>) which is located at an upper end of the extending portion (<NUM>) and which is annular and flat, the upper flat surface (<NUM>) realizing a seal between the upper flat surface and a lower surface of the sleeve (<NUM>) even when the sleeve (<NUM>) is displaced relative to the extending portion.