JP2009079840A - Boiler device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler device capable of keeping the inlet gas temperature of a denitration device constant regardless of a variation in a boiler load. <P>SOLUTION: This boiler device is characterized by individually arranging dampers 7 and 22 for adjusting a gas flow rate on the downstream side of a first economizer 24 and a second economizer 23, by arranging the first economizer 24 constituted of a first heat transfer tube much in a hear absorption quantity per the unit length and the second economizer 23 constituted of a second heat transfer tube little in the heat absorption quantity per the unit length, in the direction crossing with the flowing direction of exhaust gas, in a rear flue part 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a boiler device, and more particularly to a boiler device in which a gas flow path of a rear flue is divided into a plurality along the exhaust gas flow direction, and a economizer is installed in the divided gas flow path.

  In order to reduce nitrogen oxides in boiler exhaust gas, a denitration device is installed downstream of the economizer in the gas flow direction. Usually, the gas temperature at the inlet of the denitration apparatus is designed so that the activity of the catalyst used in the denitration apparatus is the highest under the rated load conditions of the boiler. However, since the gas temperature at the inlet of the denitration device is low when the boiler is activated or when the load is low, the activity of the catalyst is lowered and the denitration performance is degraded.

  For this reason, conventionally, a boiler apparatus having a structure as shown in FIG. 5 has been proposed (Japanese Patent Laid-Open No. 61-250405). In the figure, 1 is a rear flue section, 2 is a reheater, 3 is a superheater, 4 is a economizer, 5 is a partition, 6 is a flow adjustment damper A, 7 is a flow adjustment damper B, and 8 is a bypass flue. , 9 are bypass dampers.

  At the time of boiler start-up or low load, high temperature exhaust gas is extracted from the upstream side in the exhaust gas flow direction of the economizer 4, and the bypass flue 8 is circulated to increase the gas temperature at the inlet of the denitration device.

  In addition, as shown in FIG. 6, in this publication, instead of providing the bypass flue 8, the rear flue is divided into a plurality of gas flow paths (corresponding to gas A, gas B, and gas C), A gas mixer 10 for mixing and averaging gases is provided to control the gas temperature at the inlet of the denitration apparatus. 11 in the figure is an ash hopper.

  In another example disclosed in Japanese Patent Laid-Open No. 62-98116, as shown in FIG. 7, a dividing wall 14 is installed in the boiler flue section 1, and the main duct 12 and the economizer 4 are installed. A bypass duct 13 that is not installed is provided, and a device for suppressing a decrease in gas temperature at the inlet of the denitration apparatus when the boiler is activated or at a low load is devised by a flow rate adjustment damper 19 installed upstream thereof. In the figure, 15 is an exhaust gas temperature detector, 16 is a temperature adjuster, 17 is a temperature setter, and 18 is a damper drive device.

  In the example shown in Japanese Patent Laid-Open No. 63-148010, as shown in FIG. 8, the pipe group pitch of the economizer 20 and economizer 21 installed in the rear flue section 1 divided into two is set. By making it different, the device which adjusts gas temperature is made | formed.

Further, in the example shown in JP-A-8-82405, as shown in FIG. 9, the economizer 20 installed in the flow path on the reheater 2 side of the rear flue section 1 is divided into two by the dividing wall 14. The gas temperature is adjusted by controlling the amount of gas flowing through each economizer 20 with the downstream flow rate adjustment damper 6 and the flow rate adjustment damper 22.
JP 61-25405 A JP-A-62-098116 JP 63-148010 A Japanese Patent Laid-Open No. 08-082405

  The conventional example described above has the following problems. That is, in the structure having the bypass flue 8 shown in FIG. 5, the mixed state of the low temperature gas that has passed through the economizer 4 and the high temperature gas that has bypassed the economizer 4 and circulated through the bypass flue 8 is poor. The high temperature gas and the low temperature gas are separated up to the denitration apparatus inlet. For this reason, in order to adjust the gas temperature at the inlet of the NOx removal device to a predetermined value, it is necessary to bypass a large amount of high-temperature gas through the economizer bypass flue 8, and the bypass flue 8 needs to be enlarged. It was.

  In the structure in which the rear flue portion shown in FIG. 6 is divided into a plurality of gas flow paths and the gas mixer 10 for mixing and averaging the respective gases A, B, and C is provided, it is necessary to subdivide the gas flow paths. Therefore, the structure becomes very complicated and the equipment cost increases. Further, since the gas flow path is narrowed, the pressure loss increases and the operation cost increases.

  In the configuration shown in FIG. 7, the flow rate adjustment damper 19 installed on the upstream side of the bypass duct 13 is closed so that no gas flows into the bypass duct 13 under the rated load condition, that is, the heat recovery amount is not reduced. There is a need to. However, when the flow rate adjustment damper 19 is closed, there is a problem that ash accumulates on the upper portion and sticks, and in the worst case, the flow rate adjustment damper 19 may not be opened and closed. Moreover, since the bypass duct 13 that does not contribute to heat transfer is provided in the rear flue portion 1, the size is larger than that of the conventional rear flue portion 1.

  In the structure in which the tube group pitches of the economizers 20 and 21 installed in the rear flue portion 1 divided into two shown in FIG. 8 are made different, the side where the heat transfer tubes are roughly arranged for temperature adjustment. The number of heat transfer tubes of the economizer 21 needs to be extremely smaller than the number of heat transfer tubes of the economizer 20 on the densely arranged side. For this reason, the amount of heat recovered per unit volume is greatly reduced, and the structure is wasted. For this reason, there is a problem that it is necessary to increase the height of the rear flue portion 1 and the equipment cost increases.

  In the structure which divides the economizer 20 installed in the reheater 2 side flow path of the rear flue section 1 shown in FIG. 9 into two parts and controls the amount of gas distributed to each economizer 20, the equivalent performance Since the economizer 20 composed of the tube group is simply divided into two, one of the flow rate adjustment dampers 6 and 22 installed below the economizer 20 is almost fully closed when the temperature is adjusted. It was necessary to operate with. For this reason, there is a problem that ash accumulates and adheres to the upper part of the damper, and in the worst case, there is a disadvantage that the flow adjustment damper cannot be opened and closed.

  The object of the present invention is to eliminate such drawbacks, and to reduce the boiler load to the inlet gas temperature of an exhaust gas treatment device such as a denitration device installed downstream of the economizer without increasing the size and cost of the device. An object of the present invention is to provide a boiler device that can be kept constant regardless of fluctuations and can always operate with high performance of the exhaust gas treatment device.

In order to achieve the above object, the first means of the present invention divides the rear flue portion along the flow direction of the exhaust gas, and one or more economizers are installed in the divided flue portion, In the boiler device in which the exhaust gas treatment device is installed on the downstream side in the flow direction of the exhaust gas in the rear flue,
Among the economizers, the heat transfer tubes constituting at least one economizer are composed of two or more types of heat transfer tube portions with different heat absorption per unit length,
Two or more types of heat transfer tube portions having different heat absorption amounts are arranged in a direction crossing the flow direction of the exhaust gas,
A damper for adjusting the gas flow rate is separately provided on the downstream side of the heat transfer tube in the exhaust gas flow direction.

According to a second means of the present invention, the rear flue portion is divided along the flow direction of the exhaust gas, and two or more economizers are installed in the divided flue portion, and the exhaust gas of the rear flue portion is provided. In the boiler device in which the exhaust gas treatment device is installed on the downstream side in the flow direction of
Among the economizers, at least two economizers are a first economizer constituted by a first heat transfer tube having a large amount of heat absorption per unit length, and an amount of heat absorption per unit length. Is a second economizer composed of fewer second heat transfer tubes than the first heat transfer tubes,
The first economizer and the second economizer are arranged in a direction crossing the flow direction of the exhaust gas;
A damper for adjusting a gas flow rate is individually provided on the downstream side in the flow direction of the exhaust gas of the first economizer and the second economizer.

According to a third means of the present invention, the rear flue portion is divided along the flow direction of the exhaust gas, and one or more economizers are installed in the divided flue portion, and the exhaust gas of the rear flue portion is provided. In the boiler device in which the exhaust gas treatment device is installed on the downstream side in the flow direction of
Of the economizers, a heat transfer tube constituting at least one economizer is a finned heat transfer tube portion with fins or a heat transfer tube portion having a porous layer formed on the tube surface. A heat transfer tube portion and a second heat transfer tube portion composed of a bare tube portion without fins or a heat transfer tube portion that does not form a porous layer on the tube surface;
The first heat transfer tube portion and the second heat transfer tube portion are arranged in a direction intersecting with the flow direction of the exhaust gas,
A damper for adjusting the gas flow rate is individually provided on the downstream side of the first heat transfer tube portion and the second heat transfer tube portion in the flow direction of the exhaust gas.

According to a fourth means of the present invention, the rear flue portion is divided along the flow direction of the exhaust gas, and two or more economizers are installed in the divided flue portion, and the exhaust gas of the rear flue portion is provided. In the boiler device in which the exhaust gas treatment device is installed on the downstream side in the flow direction of
Among the economizers, at least two economizers include a finned heat transfer tube with a fin or a first economizer composed of a heat transfer tube having a porous layer formed on the tube surface, and a fin. A second economizer composed of a bare pipe or a heat transfer pipe that does not form a porous layer on the pipe surface;
The first economizer and the second economizer are arranged in a direction crossing the flow direction of the exhaust gas,
A damper for adjusting a gas flow rate is individually provided on the downstream side in the flow direction of the exhaust gas of the first economizer and the second economizer.

  According to a fifth means of the present invention, in the second or fourth means, the first economizer and the second economizer are connected by a common inlet header and outlet header. Is.

  The sixth means of the present invention is characterized in that, in the second or fourth means, the pipe group pitches of the first and second economizers are substantially equal.

  The present invention is configured as described above, and the inlet gas temperature of an exhaust gas treatment device such as a denitration device installed on the downstream side of the economizer is reduced without increasing the size and cost of the device. It is possible to provide a boiler device that can be kept constant regardless of fluctuations and that can always operate with high performance of the exhaust gas treatment device.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view of a boiler device according to an embodiment.

  As shown in the figure, the rear flue section 1 is divided into two along the flow direction of the exhaust gas by the partition wall 5, and the reheater 2 is heated to the upstream side (front side of the can) with respect to the flow of the exhaust gas. The vessel 3 is installed on the downstream side (the rear side of the can) with respect to the gas flow.

  A flue downstream of the superheater 3 in the exhaust gas flow direction is divided along the exhaust gas flow direction by the dividing wall 14, and a bare pipe economizer 23 configured using bare pipes without fins in each space; A finned pipe economizer 24 configured by using a finned pipe body provided with plate-like fins in a direction perpendicular to the pipe axis is installed. The bare pipe economizer 23 and the finned pipe economizer 24 are arranged in a direction crossing the flow direction of the exhaust gas, and the tube group pitches of both economizers 23 and 24 are substantially equal.

  The fluid flowing in the pipes of the bare pipe economizer 23 and the finned pipe economizer 24 is supplied from the inlet header 25, and flows into the bare pipe economizer 23 and the finned pipe economizer 24 and flows therethrough. It merges at the outlet header 26 later.

  The flow rate of each in-pipe fluid is adjusted by a flow rate adjusting means (not shown) such as an orifice installed at the outlet of the inlet header 25.

  On the downstream side in the gas flow direction of the reheater 2, the bare pipe economizer 23, and the finned pipe economizer 24, a flow rate adjustment damper (A) 6, a flow rate adjustment damper (C) 22, and a flow rate adjustment damper (B) 7 is installed, and the gas flow rate can be adjusted independently of each other.

  An exhaust gas temperature detector 15 is installed at the outlet of the rear flue 1, and the detected exhaust gas temperature and a temperature setting signal from a temperature setting device 17 in which the exhaust gas temperature for each boiler load is set are supplied to the temperature regulator 16. The flow rate adjustment damper (A) 6, the flow rate adjustment damper (C) 22, and the flow rate adjustment damper (B) 7 are opened and closed by each damper driving device 18 based on the control signal from the temperature regulator 16.

  Although not shown, an exhaust gas treatment device such as a denitration device carrying a catalyst is installed downstream of the exhaust gas temperature detector 15 in the exhaust gas flow direction.

  As the finned tube economizer 24, a heat absorption amount per unit length of 1.2 times or more that of the bare pipe economizer 23 was used.

  Further, the finned pipe economizer 24 having a large heat absorption amount occupies 70% or more of the economizer's occupied volume, and the flow adjustment damper (B) 7 on the finned pipe economizer 24 side at the time of high load. On the contrary, at the time of low load, the finned pipe economizer 24 side is opened so that the opening degree of the flow control damper (C) 22 on the bare pipe economizer 23 side with a large opening and a small heat absorption amount becomes small. The flow rate adjustment damper (B) 7 has a small opening, and the flow adjustment damper (C) 22 on the bare pipe side economizer 23 side with a small heat absorption amount is configured to have a large opening.

  By using the economizer of the present invention, as shown in FIG. 2, the flow rate adjustment damper (C) 22 on the lower side of the bare pipe economizer and the flow rate adjustment damper on the finned pipe economizer side according to the boiler load. (B) It is possible to adjust the opening degree of 7 and individually adjust the flow rate of gas flowing through each, and by controlling the opening degree of the damper, the inlet gas temperature of the denitration device is maintained almost constant regardless of the boiler load. be able to.

  The gas bypass amount at the time of low load in the prior art provided with the economizer bypass duct 8 shown in FIG. 5 is about 10 to 20% of the total gas amount, and the gas temperature at the inlet of the denitration apparatus is about 20 to 30 ° C. Can rise. On the other hand, in the present invention, the gas temperature at the inlet of the denitration device equivalent to the conventional one can be obtained by flowing about 70 to 80% of the total gas amount to the bare tube side at the time of low load.

  In addition, as shown in FIG. 3, regarding the steam temperature control of the reheater during load change operation, the conventional technology adjusts the two damper opening degrees on the reheater side and the superheater side, While the amount of gas passing through was adjusted, in the present invention, the number of flow rate adjustment dampers installed in the duct on the superheater side is increased from one to two, and three dampers are combined with the reheater side. Adjust the opening. Since the damper on the superheater side is divided into two in this way, there is an advantage that the damper driving device is miniaturized and the response delay is reduced.

  Another embodiment of the present invention is shown in FIG. In the above embodiment, the flue downstream of the superheater 3 in the exhaust gas flow direction is divided into two by the dividing wall 14, the bare pipe side economizer 23 is provided in one flue portion, and the fin is provided in the other flue portion. Although the attached pipe economizer 24 is installed, in this embodiment, the flue where the economizers 23 and 24 are installed is not divided, and the flow rate adjustment damper (B) 7 is provided from the space below the economizers 23 and 24. And the partition wall 14 is installed only between the flow control damper (C) 22.

  In the said embodiment, although the bare pipe side economizer 23 and the finned pipe economizer 24 were comprised separately and installed in the predetermined position, in this embodiment, as shown to a figure, one end of a heat exchanger tube group is shown. As a whole, the bare pipe side economizer 23 is constructed as a bare pipe without attaching fins to the section side (the left end as viewed in the drawing), and fins are attached to the remaining part as finned pipes. The tube side economizer 24 with fins is configured as a whole.

  The fluid flowing in the pipe is supplied from the inlet header 25, passes through the finned pipe economizer 24 and the bare pipe economizer 32 alternately, and reaches the outlet header 26.

  For example, as a form of a finned pipe economizer, a rectangular plate-like fin in which the outer shape of the pipe is cut from both the left and right sides of one or two or more sets of heat transfer pipes is welded. It is done. The same applies to the above embodiment.

  The gas flow resistance in the lateral width direction (tube axis direction) toward the paper surface of the finned tube economizer 24 is very large, and movement of the gas flowing into the finned tube economizer 24 in the width direction is limited. Therefore, even if the gas flow path of the economizer part is not divided by the dividing wall 14 as in the present embodiment, each gas flow rate passing through the bare pipe economizer 23 and the finned pipe economizer 24 is It can be arbitrarily adjusted by the downstream flow rate adjusting dampers 22 and 7.

  In this way, by not dividing the economizer portion with the dividing wall, it is not necessary to construct a penetration portion of the heat transfer tube in the dividing wall 14, and the construction cost can be reduced.

  In the said embodiment, although the finned heat exchanger tube was used as a heat exchanger tube with high heat transfer performance, the heat exchanger tube in which the porous layer was formed in the tube surface can also be used.

  According to the present invention, as shown in FIG. 2, the inlet gas temperature of an exhaust gas treatment device such as a denitration device installed on the downstream side of the economizer can be kept constant regardless of boiler load fluctuations. The device can be operated at a high level at all times.

It is a partial sectional side view of the boiler apparatus which concerns on embodiment of this invention. It is a characteristic view which shows the relationship between the boiler load which concerns on embodiment of this invention, a bare pipe economizer side, and a finned pipe economizer side damper opening degree, and the relationship between a boiler load and a denitration apparatus inlet gas temperature. It is a characteristic figure which shows steam temperature control of the reheater in a prior art example and this invention. It is a partial sectional side view of the boiler apparatus which concerns on other embodiment of this invention. It is a partial sectional side view of the boiler apparatus proposed conventionally. It is a partial sectional side view of the boiler apparatus proposed conventionally. It is a partial sectional side view of the boiler apparatus proposed conventionally. It is a partial sectional side view of the boiler apparatus proposed conventionally. It is a partial sectional side view of the boiler apparatus proposed conventionally.

Explanation of symbols

  1: rear flue section, 2: reheater, 3: superheater, 4: partition wall, 6: flow adjustment damper (A), 7: flow adjustment damper (B), 14: dividing wall, 15: exhaust gas temperature detection 16: Temperature controller, 17: Temperature setting device, 18: Damper drive device, 22: Flow rate adjustment damper (C), 23: Bare pipe economizer, 24: Finned pipe economizer, 25: Inlet header 26: Exit header.

Claims (6)

The rear flue portion is divided along the flow direction of the exhaust gas, and one or more economizers are installed in the divided flue portion, and the exhaust gas treatment device is disposed downstream of the rear flue portion in the flow direction of the exhaust gas. In the boiler equipment where
Among the economizers, the heat transfer tubes constituting at least one economizer are composed of two or more types of heat transfer tube portions with different heat absorption per unit length,
Two or more types of heat transfer tube portions having different heat absorption amounts are arranged in a direction crossing the flow direction of the exhaust gas,
The boiler apparatus characterized by providing the damper for adjusting a gas flow rate separately in the flow direction downstream of the exhaust gas of the heat exchanger tube part. The rear flue portion is divided along the flow direction of the exhaust gas, and two or more economizers are installed in the divided flue portion, and the exhaust gas treatment device is disposed downstream of the rear flue portion in the flow direction of the exhaust gas. In the boiler equipment where
Among the economizers, at least two economizers are a first economizer constituted by a first heat transfer tube having a large amount of heat absorption per unit length, and an amount of heat absorption per unit length. Is a second economizer composed of fewer second heat transfer tubes than the first heat transfer tubes,
The first economizer and the second economizer are arranged in a direction crossing the flow direction of the exhaust gas;
The boiler apparatus characterized by providing the damper for adjusting a gas flow rate separately in the flow direction downstream of the exhaust gas of a said 1st economizer and a 2nd economizer. The rear flue portion is divided along the flow direction of exhaust gas, and one or more economizers are installed in the divided flue portion, and the exhaust gas treatment device is disposed downstream of the rear flue portion in the flow direction of exhaust gas. In the boiler equipment where
Of the economizers, a heat transfer tube constituting at least one economizer is a finned heat transfer tube portion with fins or a heat transfer tube portion having a porous layer formed on the tube surface. A heat transfer tube portion and a second heat transfer tube portion composed of a bare tube portion without fins or a heat transfer tube portion that does not form a porous layer on the tube surface;
The first heat transfer tube portion and the second heat transfer tube portion are arranged in a direction intersecting with the flow direction of the exhaust gas,
The boiler apparatus characterized by providing the damper for adjusting a gas flow rate separately in the flow direction downstream of the exhaust gas of the said 1st heat-transfer tube part and the 2nd heat-transfer tube part. The rear flue is divided along the flow direction of the exhaust gas, and two or more economizers are installed in the divided flue portion, and the exhaust gas treatment device is disposed downstream of the rear flue in the flow direction of the exhaust gas. In the boiler equipment where
Of the economizers, at least two economizers include a finned heat exchanger tube or a first economizer composed of a heat exchanger tube having a porous layer formed on the tube surface, and a fin. A second economizer composed of a bare pipe or a heat transfer pipe that does not form a porous layer on the pipe surface;
The first economizer and the second economizer are arranged in a direction crossing the flow direction of the exhaust gas,
The boiler apparatus characterized by providing the damper for adjusting a gas flow rate separately in the flow direction downstream of the exhaust gas of a said 1st economizer and a 2nd economizer.   5. The boiler device according to claim 2, wherein the first economizer and the second economizer are connected by a common inlet header and outlet header.   5. The boiler device according to claim 2, wherein tube pitches of the first economizer and the second economizer are substantially equal. 6.

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