JP2842190B2 - Exhaust heat recovery boiler can structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can body structure of an exhaust heat recovery boiler (hereinafter referred to as "cogeneration exhaust heat recovery boiler") used in a cogeneration system using a gas engine, a diesel engine, a gas turbine, or the like. Things.

[0002]

2. Description of the Related Art Conventionally, in a can body structure of a cogeneration exhaust heat recovery boiler, a heat exchange section for exchanging heat with exhaust gas includes:
It is composed of a heat-insulated metal wall, a heat-insulating wall made of refractory, and the like.

In general, as a cogeneration exhaust heat recovery boiler, as an application condition, design conditions relating to a heat-resistant structure of the boiler itself cannot be set as unique ones. It is required to have a heat-resistant structure that can respond to changes. In addition, from the viewpoint of the installation environment, it is required to provide an earthquake-resistant structure against vibration of a gas engine or the like, or to provide a structure that is not affected by vibration.

Under such application conditions, it is very difficult to take measures against thermal expansion due to a change in temperature of exhaust gas in a conventional metal wall-shaped can body structure. Although complicated structures and measures are taken, there is no materialized structure that reliably absorbs thermal expansion, and even if there is a materialized material in rare cases, the structure becomes complicated, resulting in maintenance. Is very troublesome,
Moreover, it is expensive, and the fact is that sufficient ones have not yet been proposed. In addition, in the case of a can body structure with a heat insulating wall made of a refractory, there is a problem that a connection structure or a building structure of the refractory collapses or collapses in a short time due to vibration. The fact is that it is not. Therefore, this is a major bottleneck in the cogeneration system of effectively utilizing waste heat.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention realizes a can body structure which is not affected by vibration of a gas engine or the like without taking a special structure or means for absorbing thermal expansion. It is intended.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in a heat recovery steam generator having an exhaust gas passage in a can body, a number of water pipes are inserted into the exhaust gas passage. The both side walls defining the exhaust gas passage, the portion from the inlet portion of the exhaust gas passage to a point where the exhaust gas temperature becomes a predetermined temperature or less with respect to the can body temperature has a water cooling wall structure comprising a heat collecting water pipe, The subsequent downstream side is characterized by having a casing structure.

[0007]

According to the present invention, since the water cooling wall structure is constituted by the heat collecting water pipe from the inlet portion of the exhaust gas passage to a predetermined area, the water cooling wall itself also exchanges heat with the exhaust gas, thereby discharging the exhaust heat of the exhaust gas. It has a function of recovering, so that the water cooling wall itself is always kept in a state not affected by thermal expansion. Then, on the downstream side that is continuous with the water-cooling wall structure, the temperature of the exhaust gas is reduced, so that the casing structure always maintains a state in which it is not affected by thermal expansion. Further, since both side walls defining the exhaust gas passage are constituted by the water cooling wall structure and the casing structure, they are not affected by the vibration of the gas engine or the like.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. In the following description, in the illustrated embodiment, a specific example of a multi-tube once-through boiler having a can body structure including a rectangular water pipe assembly will be described as an exhaust heat recovery boiler. FIG. 1 is a schematic side view for explaining the entire configuration of an embodiment of the present invention, and shows a partially broken state. FIG. 2 is an explanatory sectional view taken along line II-II in FIG.

In FIG. 1, a cogeneration waste heat recovery boiler 1 is basically constituted by a rectangular parallelepiped can body 2 composed of a rectangular water pipe assembly, and is disposed on one side in the longitudinal direction, that is, on the upstream side. An inlet chamber 3 for introducing exhaust gas from a gas engine or the like is connected, and exhaust gas that has undergone heat exchange in the can body 2 of the exhaust heat recovery boiler 1 is discharged to the other side in the longitudinal direction, that is, downstream. An outlet chamber 4 is connected. The outlet chamber 4 is provided with an economizer 5 for more effectively recovering the heat of the exhaust gas. Therefore, the high-temperature exhaust gas generated by the gas engine or the like is introduced from the inlet chamber 3 into the can body 2 of the exhaust heat recovery boiler 1 and exchanges heat in a process of passing through the can body 2 to recover the heat. As a result, the temperature of the exhaust gas decreases. The exhaust gas whose temperature has been reduced by heat exchange in the can 2 exits the can 2 and enters the economizer 5, where the heat is recovered to lower the temperature, and then the chimney (not shown) from the outlet chamber 4 Is discharged through.

In the exhaust heat recovery boiler 1, both side walls (both sides in the left-right direction in FIG. 2) forming the outer shell of the can body 2 are provided with an exhaust gas inlet portion 6 connected to the inlet chamber 3.
A part of a predetermined distance from the (upper part in the vertical direction in FIG. 2) to the downstream side is constituted by the water cooling wall structures 7, 7. This water cooling wall structure 7 is composed of a straight tubular heat collecting water pipe 8.
Are arranged at equal intervals, and the adjacent heat collecting water pipes 8 are connected to each other by fin-shaped members 9 so as to close the gap between the heat collecting water pipes 8. Is configured as a wall member. Thus, each of the water cooling wall structures 7 defines an outer shell of the can body 2 and also has a function as a heat transfer surface, that is, a function as an exhaust heat recovery unit. In this regard, since each water cooling wall structure 7 is a heat transfer surface, it is advantageous in reducing the size of the can 2.

The two water-cooling wall structures 7 face each other while maintaining a required interval, and are arranged on both sides so as to be substantially parallel to each other. The upper and lower ends of each of the heat collecting water pipes 8, 8,... Constituting the wall structures 7, 7 are connected to upper and lower headers 10, 11, respectively. Therefore, a pair of water cooling wall structures 7,
7 and the upper and lower headers 10 and 11 form an exhaust gas passage 12 through which the exhaust gas from the inlet chamber 3 passes substantially linearly.

As described above, the water cooling wall structure 7 forms the exhaust gas passage 12 by the upper and lower headers 10 and 11, but extends from the inlet portion 6 to a predetermined distance downstream. Are located in The predetermined distance is set based on a point of thermal expansion due to a temperature change of the exhaust gas passing through the exhaust gas passage 12, and is set as follows. That is, the water cooling wall structure 7 extends from the inlet portion 6 to a point A where the exhaust gas temperature becomes a predetermined temperature or less with respect to the can body temperature, toward the downstream side. The temperature is defined as a portion where the body temperature is equal to or lower than a predetermined temperature, and specifically, is set based on the water temperature. According to the experiments or tests of the inventor, the temperature of the exhaust gas is determined by the following equation:
It is based on the knowledge that if the temperature is 0 ° C. or less, the influence of the thermal expansion caused by the exhaust gas temperature can be avoided. Therefore, it is preferable that the point A is a point at which the temperature of the exhaust gas becomes equal to or lower than the saturated temperature of the still water + 100 ° C.

On the downstream side of the water-cooled wall structure 7, casing structures 13, 13 serving as side walls on both sides forming an outer shell of the rectangular parallelepiped can body 2 are provided at respective downstream ends located at the point A. Are connected respectively. The two casing structures 13 are provided with the upper and lower headers 10 and 1.
It is composed of flat metal plates 14, 14 each having a size as a side wall that closes both side portions between the two. The upper and lower ends of the two metal plates 14 are fixed to the upper and lower headers 10 and 11 by welding or the like. Therefore, also on the downstream side of the can body 2, the exhaust gas passage 12 continuous with the exhaust gas passage 12 is formed by the pair of metal plates 14, 14 and the upper and lower headers 10, 11.

In this embodiment, the upstream ends of the metal plates 14 are bent inward to form bent portions 15, 15, respectively, and the tip portions of the bent portions 15 are formed. Are fixed to the fin-like members 9 located at the most downstream side of the water cooling wall structure 7 by welding or the like (see FIG. 2).

As described above, in the exhaust gas passage 12 formed inside the can body 2 over the entire length thereof in the longitudinal direction, a large number of air passages are provided at intervals allowing the exhaust gas from the inlet chamber 3 to flow. Are inserted substantially vertically. Each of the water pipes 16 is provided with a plurality of substantially horizontal fins 17 and 1 at appropriate intervals in the pipe axis direction.
Are fixed in multiple stages. By fixing the horizontal fins 17, a required heat transfer surface area is secured for each water pipe 16. The interval between the water pipes 16 is preferably set to be as small as possible in order to improve the convective heat transfer efficiency between the exhaust gas and the water pipes 16. However, if the gas flow velocity around each water pipe 16 becomes too fast, the pressure loss becomes large. Conversely, if the gas flow velocity is extremely wide, the gas flow velocity becomes slow, and the convective heat transfer efficiency is reduced. The number of 16 must also be reduced, which means that the heat transfer area is reduced, and therefore the heat transfer amount itself is also reduced. In this regard, the mutual spacing of the water tubes 16 is dependent on the heat transfer surface area of each transverse fin 17 in FIG.
It is preferable to set the interval as shown in FIG.

Each of the water pipes 16 is inserted over substantially the entire area of the gas passage 12 while maintaining the distance. In this manner, the upper and lower ends of each water pipe 16 inserted substantially over the entire area of the gas passage 12 are similar to the heat collecting water pipes 8, 8,. They are connected to the upper and lower headers 10, 11, respectively.

[0017]

As described above, according to the present invention, since the upstream side of the exhaust gas passage has a water-cooling wall structure composed of a heat collecting water pipe, the water-cooling wall itself exchanges heat with the exhaust gas, and the exhaust heat of the exhaust gas is exhausted. The water cooling wall itself can always maintain a state where it is not affected by the thermal expansion due to the exhaust gas temperature, and the thermal expansion can be reliably absorbed with a simple configuration. Since the water cooling wall itself is a heat transfer surface, it is very easy to reduce the size of the can.

Further, on the downstream side continuous with the water-cooling wall structure, since the casing structure is formed after the point where the exhaust gas temperature is reduced, the casing structure itself can always be maintained in a state where it is not affected by the thermal expansion due to the exhaust gas temperature. The can body can be formed with a simple configuration.

Further, since both side walls defining the exhaust gas passage are constituted by a water-cooling wall structure and a casing structure, a robust can body which is not affected by vibrations of a gas engine or the like can be realized. This greatly contributes to the effective use of waste heat in the system, and is very effective as this kind of can body structure.

[Brief description of the drawings]

FIG. 1 is a side view illustrating an entire configuration of an embodiment of the present invention, and is an explanatory view with a part cut away.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, omitting hatching indicating a cross section of each water pipe and a fin-shaped member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust heat recovery boiler 2 Can body 6 Inlet part 7 Water cooling wall structure 8 Heat collection water pipe 12 Exhaust gas passage 13 Casing structure 16 Water pipe A Point where exhaust gas temperature falls below a predetermined temperature

Claims (1)

(57) [Claims] 1. An exhaust heat recovery boiler 1 having an exhaust gas passage 12 in a can body 2. In the exhaust heat recovery boiler 1, a large number of water pipes 16 are inserted into the exhaust gas passage 12, and both side walls defining the exhaust gas passage 12 are formed. A portion from the inlet portion 6 of the exhaust gas passage 12 to a point A where the exhaust gas temperature becomes a predetermined temperature or lower with respect to the can body temperature is defined as a water-cooled wall structure 7 including a heat collecting water pipe 8.
A can body structure for an exhaust heat recovery boiler, wherein a casing structure 13 is provided on the downstream side thereafter.