JP7427918B2 - boiler - Google Patents

Description

The present invention relates to a boiler that recovers waste heat from a furnace such as an incinerator.

Generally, a boiler for recovering waste heat is installed downstream of a furnace such as an incinerator that burns waste such as household garbage. Boilers include, for example, tail-end boilers (see Patent Document 1) and vertical boilers (see Patent Document 2).

As shown in FIG. 4, the tail-end boiler 31 includes a radiant heat transfer chamber 32 and a convection heat transfer chamber 33. The casing of the radiant heat transfer chamber 32 is constructed from water-cooled wall tubes. The radiant heat transfer chamber 32 generates steam by receiving radiant heat from the exhaust gas. A superheater 34 that superheats steam by exchanging heat with exhaust gas is arranged in the convection heat transfer chamber 33 . The superheater 34 is a hanging superheater suspended from the ceiling of the convection heat transfer chamber 33. The flow of exhaust gas in the convective heat transfer chamber 33 is substantially parallel to the ground. The steam superheated by the superheater 34 is sent to the steam turbine 35.

The tail-end boiler 31 is provided with a hammering device 36 that vibrates the superheater 34 to remove dust attached to the superheater 34, and the hammering device 36 is applied to the hanging superheater 34. This has the advantage that dust can be removed efficiently. However, the flow of exhaust gas in the convection heat transfer chamber 33 is substantially parallel to the ground. Therefore, there is a disadvantage that the site area of the boiler 31 becomes large.

As shown in FIG. 5, the vertical boiler 41 also includes a radiant heat transfer chamber 42 that receives radiant heat from exhaust gas to generate steam, and superheaters 44a and 44b that superheat the steam by exchanging heat with the exhaust gas. , 44c are arranged in the convection heat transfer chamber 43. In the vertical boiler 41, the flow of exhaust gas in the convection heat transfer chamber 43 is substantially perpendicular to the ground. Therefore, there is an advantage that the site area of the boiler 41 can be reduced.

By the way, in the vertical boiler described in Patent Document 2, the superheaters 44a, 44b, and 44c include a primary superheater 44a with the lowest steam temperature for generating superheated steam, and a steam temperature generator 44a with the lowest steam temperature for generating superheated steam. It is composed of a secondary superheater 44b having an intermediate temperature, and a tertiary superheater 44c having the highest steam temperature for generating superheated steam. Here, since the corrosion rate of the tube depends on the temperature of the steam flowing inside the tube and the ambient temperature on the surface of the tube, the tertiary superheater 44c, which has the highest steam temperature for generating superheated steam, is most likely to corrode. Therefore, by arranging the tertiary superheater 44c downstream of the primary superheater 44a, the tertiary superheater 44c is prevented from becoming high temperature, and the risk of corrosion of the tertiary superheater 44c is reduced.

Japanese Patent Application Publication No. 2002-310594 Japanese Unexamined Patent Publication No. 7-139706

However, in the vertical boiler described in Patent Document 2, the tertiary superheater is placed downstream of the primary superheater, so the steam temperature for the tertiary superheater to generate superheated steam cannot be raised too high. There are challenges. If the steam temperature cannot be raised, the power generation efficiency of the generator will decrease.

The present invention was made in view of these problems, and it is possible to reduce the site area of the boiler, and to increase the steam temperature for generating superheated steam, thereby increasing the power generation efficiency of the generator. The purpose is to provide a boiler that can.

In order to solve the above problems, one aspect of the present invention provides a boiler connected to a waste incinerator , which includes a radiant heat transfer chamber that generates steam by receiving radiant heat from exhaust gas, and a radiant heat transfer chamber that generates steam by receiving radiant heat from exhaust gas. a convective heat transfer chamber in which a superheater for exchanging and superheating steam is disposed, the flow of exhaust gas in the convective heat transfer chamber being substantially perpendicular to the ground, and the flow of exhaust gas in the radiant heat transfer chamber A hanging superheater suspended from the ceiling is arranged at a bend in the road, and the heat transfer tubes of the hanging superheater include a plurality of straight pipe sections and a plurality of heat exchanger tubes provided at both ends of the straight pipe section. It has a bend part, an inlet end part, and an outlet end part, and is in direct contact with the exhaust gas , gives vibration to the hanging superheater, and adheres to the heat exchanger tube of the hanging superheater. This boiler is equipped with a hammering device to remove dust.

According to the present invention, the site area of the boiler can be reduced, and the steam temperature for generating superheated steam can be increased, thereby increasing the power generation efficiency of the generator.

FIG. 1 is a vertical cross-sectional view of a boiler according to an embodiment of the present invention. 2 is an enlarged view of part II in FIG. 1. FIG. FIG. 2 is an enlarged view of section III in FIG. 1; FIG. 2 is a vertical cross-sectional view of a conventional tail-end boiler. FIG. 2 is a vertical view of a conventional vertical boiler.

Hereinafter, a boiler according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the boiler of the present invention can be embodied in various forms and is not limited to the embodiments described in the specification. Rather, this embodiment is provided with the intention that this disclosure will be thorough and thorough, and will fully enable those skilled in the art to understand the invention.

FIG. 1 is a longitudinal sectional view of a boiler 1 according to an embodiment of the present invention. The boiler 1 is connected to the rear stage of the furnace 2. Note that FIG. 1 shows a grate-type waste incinerator as an example of the furnace 2. As shown in FIG.

The boiler 1 includes a radiant heat transfer chamber 3 that generates steam by receiving radiant heat from exhaust gas, and a convection heat transfer chamber 4 in which superheaters 5b and 5c that superheat the steam by exchanging heat with the exhaust gas are arranged. Be prepared. The casing of the radiant heat transfer chamber 3 is composed of water-cooled wall tubes.

The radiant heat transfer chamber 3 is provided with a first bending part 7 and a second bending part 9 that bend the exhaust gas flow path. The first bent portion 7 changes the flow of exhaust gas from upward to downward. The second bent portion 9 changes the flow of exhaust gas from downward to upward. The first bent portion 7 and the second bent portion 9 form a first passage 6 and a second passage 8 in the radiant heat transfer chamber 3 from the upstream side through which the exhaust gas flows. The exhaust gas discharged from the furnace 2 flows through the first passage 6 from below to above, is changed direction by the first bending part 7 , flows through the second passage 8 from above to below, and is changed by the second bending part 9 . It is redirected and flows through the convective heat transfer chamber 4 from below to above (substantially perpendicular to the ground).

A hanging superheater 5a suspended from the ceiling 3a of the radiant heat transfer chamber 3 is arranged at the first bending part (the second flow path 8 or the first flow path 6) of the radiant heat transfer chamber 3. .

The hanging superheater 5a is an nth-order superheater in which the steam temperature for generating superheated steam is maximum among the superheaters of orders 1 to n (where n is an integer of 2 or more). The 1st to n-1th order superheaters 5b and 5c are arranged in the convection heat transfer chamber 4. For example, when n=3, the hanging superheater 5a is a tertiary superheater, and the first to second order superheaters 5b and 5c are arranged in the convection heat transfer chamber 4.

In addition, the hanging superheater 5a is an n-th superheater that has the maximum steam temperature for generating superheated steam among the superheaters from 1 to n (where n is an integer of 3 or more). It may be an n-1 order superheater with the second highest steam temperature. In this case, 1st to n-2nd order superheaters are arranged in the convection heat transfer chamber 4. For example, when n=5, the hanging superheaters are a 5th order superheater and a 4th order superheater, and the 1st to 3rd order superheaters are arranged in the convection heat transfer chamber 4.

FIG. 2 shows a detailed view (an enlarged view of section II in FIG. 1) of the hanging superheater 5a. The hanging superheater 5a is composed of a plurality of heat exchanger tubes 11 (heat exchanger tube group) arranged in a direction perpendicular to the paper surface of FIG. Each heat exchanger tube 11 is bent in a zigzag shape, and includes a plurality of straight tube sections 11a, a plurality of bend sections 11b and 11c provided at both ends of the straight tube section 11a, an inlet end section 11d, and an outlet end section. 11e. The straight pipe portion 11a is substantially perpendicular to the ground. The inlet end 11d and the outlet end 11e penetrate the ceiling 3a of the radiant heat transfer chamber 3 and are connected to the headers 12 and 13. The feeding end 11d and the feeding end 11e are supported by a support beam (not shown). By opening the ceiling portion 3a, the suspended superheater 5a can be replaced using a crane.

Further, the straight pipe portions 11a of each heat exchanger tube 11 are connected by a straight pipe portion connecting member 14. The heat exchanger tubes 11 are connected by panel connecting members 15 and 16 extending in a direction perpendicular to the plane of the drawing. The panel connecting members 15, 16 are hit by a hammering device 17 (see FIG. 1). The direction of impact of the hammering device 17 is perpendicular to the paper plane of FIG. The hammering device 17 is, for example, an air knocker. The air knocker has a piston inside, and the piston strikes the panel connecting members 15 and 16 due to air pressure. Alternatively, in addition to the air knocker, a hammer-type hammering device may be used.

When the panel connecting members 15 and 16 receive a blow from the hammering device 17, the blow is transmitted to each heat transfer tube 11 via the panel connecting members 15 and 16. In each heat exchanger tube 11, force is transmitted to all the straight pipe parts 11a through the straight pipe part connecting member 14. Therefore, the heat exchanger tube 11 vibrates, and dust such as ash adhering to the heat exchanger tube 11 is removed.

FIG. 3 shows a detailed view (an enlarged view of section III in FIG. 1) of the primary superheater 5b arranged in the convection heat transfer chamber 4. The primary superheater 5b is composed of a plurality of heat exchanger tubes 21 (heat exchanger tube group) arranged in a direction perpendicular to the paper surface of FIG. Each heat exchanger tube 21 is bent in a zigzag shape, and includes a plurality of straight tube sections 21a, a plurality of bend sections 21b and 21c provided at both ends of the straight tube section 21a, an inlet end section 21d, and an outlet end section. 21e. The straight pipe portion 21a is substantially parallel to the ground. The inlet end 21d and the outlet end 21e penetrate the wall 4a of the convection heat transfer chamber 4 and are connected to the headers 22, 23.

Dust adhering to the primary superheater 5b is removed by, for example, a soot blower that blows steam onto the heat transfer tubes 21, or a pressure wave generator that releases pressure waves into the convection heat transfer chamber 4. The configuration of the secondary superheater 5c is substantially the same as the primary superheater 5b except that the steam temperature for generating superheated steam is higher than that of the primary superheater 5b, so a description thereof will be omitted. .

Further, the convection heat transfer chamber 4 shown in FIG. 1 is provided with an economizer (not shown) in addition to the primary superheater 5b and the secondary superheater 5c. Economizers heat water by exchanging heat with exhaust gas. The hot water heated by the economizer is supplied to the water-cooled wall tube of the radiant heat transfer chamber 3. Steam generated in the water-cooled wall tube by receiving radiant heat from the exhaust gas is supplied to a primary superheater 5b, a secondary superheater 5c, and a hanging superheater 5a (tertiary superheater) in this order. The primary superheater 5b superheats the steam supplied from the radiant heat transfer chamber 3. The secondary superheater 5c further superheats the steam superheated by the primary superheater 5b. The hanging superheater 5a further superheats the steam superheated by the secondary superheater 5c. The steam superheated by the hanging superheater 5a reaches the maximum temperature and is supplied to the steam turbine.

The configuration of the boiler of this embodiment has been described above. According to the boiler of this embodiment, it is possible to realize both the advantages of a hanging superheater used in a tail-end boiler and the advantages of a superheater used in a vertical boiler. play.

That is, since the flow of exhaust gas in the convection heat transfer chamber 4 is substantially perpendicular to the ground, the site area of the boiler 1 can be reduced. Furthermore, since the hanging superheater 5a is arranged in the radiant heat transfer chamber 3 where the exhaust gas temperature is high, the steam temperature for generating superheated steam can be increased, and the hanging superheater 5a can be Thermal area can be reduced. Furthermore, if the superheater 5a is placed in the radiant heat transfer chamber 3 where the exhaust gas temperature is high, the superheater 5a is likely to corrode. Therefore, corrosion of the superheater 5a can also be prevented. Furthermore, the hanging superheater 5a can be replaced entirely by opening the ceiling 3a of the radiant heat transfer chamber 3, which not only facilitates replacement, but also reduces material costs and maintenance costs for the superheater 5a. There is expected.

The hanging superheater 5a is the n-th superheater 5a that has the maximum steam temperature for generating superheated steam among the superheaters of the order 1 to n (where n is an integer of 2 or more), Since the 1st to n-1st order superheaters 5b and 5c are arranged in the convection heat transfer chamber 4, corrosion of the 1st to n-1st order superheaters 5b and 5c is prevented, and the maximum temperature of superheated steam is maintained. can be made higher. Therefore, the power generation efficiency of the generator can be increased.

In addition, among the superheaters of the order 1 to n (where n is an integer of 3 or more), the hanging type superheater is the superheater of the nth order that has the maximum steam temperature for generating superheated steam, and the superheated steam Even if the n-1st order superheater has the second highest steam temperature to generate , and the 1st to n-2nd order superheaters are placed in the convection heat transfer chamber 4, the It is possible to increase the maximum temperature of superheated steam while preventing corrosion of the vessel. Therefore, the power generation efficiency of the generator can be increased.

Since the radiant heat transfer chamber 3 includes the first bending section 7 and the second bending section 9, the temperature of the exhaust gas reaching the convection heat transfer chamber 4 can be lowered, and the primary superheating disposed in the convection heat transfer chamber 4 can be lowered. Corrosion of the container 5b and the secondary superheater 5c can be prevented.

Note that the present invention is not limited to being embodied in the above-described embodiments, and can be modified to other embodiments without changing the gist of the present invention.

In the above embodiment, the radiant heat transfer chamber is provided with the first bending portion and the second bending portion that bend the exhaust gas flow path, but the radiant heat transfer chamber may be provided with only one bending portion. In this case, the flow of exhaust gas in the convection heat transfer chamber is from top to bottom.

In the above embodiment, the hanging superheater arranged in the radiant heat transfer chamber is an n-th order heater, or an n-th order superheater and an n-1 order superheater. may be used as a primary heater and/or a secondary superheater.

1... Boiler 3... Radiation heat transfer chamber 4... Convection heat transfer chamber 7... First bending part (bending part)
3a...Ceiling part 5a...Third superheater (hanging type superheater)
5b…Primary superheater (superheater)
5c…Secondary superheater (superheater)
17...Hammering device

Claims (4)

A boiler connected to a waste incinerator ,
a radiant heat transfer chamber that generates steam by receiving radiant heat from exhaust gas;
a convection heat transfer chamber in which a superheater for superheating steam by exchanging heat with exhaust gas is arranged;
the flow of exhaust gas in the convection heat transfer chamber is substantially perpendicular to the ground;
A hanging superheater suspended from the ceiling is disposed at a bent part of the exhaust gas flow path in the radiant heat transfer chamber,
The heat exchanger tube of the hanging superheater has a plurality of straight pipe sections, a plurality of bend sections provided at both ends of the straight pipe section, an inlet end, and an outlet end, and has in direct contact with
A boiler provided with a hammering device that applies vibration to the hanging superheater to remove dust adhering to heat transfer tubes of the hanging superheater. The hanging superheater is an nth-order superheater in which the steam temperature for generating superheated steam is maximum among the superheaters of orders 1 to n (where n is an integer of 2 or more),
The boiler according to claim 1, wherein a 1st to n-1th order superheater is arranged in the convection heat transfer chamber. The hanging superheater is a superheater of the order 1 to n (where n is an integer of 3 or more), which has the maximum steam temperature for generating superheated steam, and the steam temperature. is the second highest n-1 order superheater,
The boiler according to claim 1, wherein a 1st to n-2nd order superheater is arranged in the convection heat transfer chamber. The bent portion of the radiant heat transfer chamber is
a first bending portion that changes the flow of exhaust gas from upward to downward;
a second bending portion that changes the flow of exhaust gas from downward to upward;
The boiler according to any one of claims 1 to 3, wherein the hanging superheater is arranged at the first bending part.

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