JP3029192B2 - Denitration equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a denitration apparatus for removing nitrogen oxides (NOx) in combustion exhaust gas discharged from a waste heat recovery boiler of a combined cycle power plant. In particular, a catalyst block composed of a plurality of catalyst units and a frame surrounding the outside of the catalyst unit assembly is stacked in an exhaust gas passage, and the untreated gas flowing through the exhaust gas passage is denitrated by the catalyst block. Related to the device. 2. Description of the Related Art Large-capacity thermal power plants are being constructed to meet the rapidly increasing demand for electric power. However, these boilers are required to perform a voltage-changing operation in order to obtain high power generation efficiency even at a partial load. Is required. [0003] As a characteristic of recent power demand, the difference between the maximum and minimum load increases with the growth of nuclear power generation.
Thermal power generation tends to shift from baseload use to load adjustment. [0004] That is, most of the thermal power generation boilers are always operated at a boiler load of 100%, and the boiler load is reduced to 75%.
The so-called daily start and stop (hereinafter referred to simply as DS) is used to increase or decrease the load to 50%, 25%, or 25%, and to stop or operate the boiler.
S) operation and Weekly StartStop
(Hereinafter, simply referred to as WSS) to carry the intermediate load and improve the power generation efficiency. For example, as part of high-efficiency power generation, a combined cycle power plant has recently been receiving attention. This combined cycle power plant first generates power using a gas turbine, collects heat in the exhaust gas discharged from the gas turbine with a waste heat recovery boiler, and drives the steam turbine with the steam generated by the waste heat recovery boiler to generate power. Is what you do. [0006] The combined cycle power plant performs power generation using a gas turbine and power generation using a steam turbine, so that the power generation efficiency is high and the gas turbine has excellent load response, and therefore can sufficiently cope with a sudden increase in power demand. This is particularly effective for DSS operation and WSS operation. [0007] However, in this combined cycle power plant, L
Since clean fuel such as NG and kerosene is used, SO
Although x and dust are small, the amount of oxygen at the time of combustion is large and the combustion at high temperature increases the amount of NOx in exhaust gas. Therefore, a waste heat recovery boiler equipped with a denitration device has been developed. FIG. 5 is a schematic system diagram of a combined cycle power plant in which a denitration apparatus is arranged. 1 is a gas turbine, 2 is an exhaust gas passage for introducing untreated gas G from the gas turbine 1, 3 is a superheater, 4 is a first evaporator, 5 is a denitration device, 6
Denotes a second evaporator, and 7 denotes a economizer. The superheater 3, the first evaporator 4, the denitration device 5, the second evaporator 6, and the economizer 7 are arranged in the exhaust gas passage 2. 8 is a drum for generating steam, 9 is a steam turbine driven by the steam generated on the drum 8, 10 is a condenser for condensing the steam and returning it to water, 1
1 is a pump for supplying water from the condenser 10 to the drum 8, 12
Is a water supply line. The water in the condenser 10 is supplied by a pump 11
Then, it is preheated by the untreated gas G in the economizer 7 through the water supply pipe 12 and supplied to the drum 8. The water in the drum 8 descends through the downcomer 13 and is introduced into the evaporators 4 and 6 via lines 14a and 14b, and returns into the drum 8 via lines 15a and 15b. In this way, the steam generated by heat exchange with the untreated gas G in the evaporators 4 and 6 during the circulation flow is introduced into the superheater 3 by the saturated steam pipe, where it is superheated by the untreated gas G, The superheated steam is supplied to the steam turbine 9 via the main steam pipe 17. Reference numeral 18 denotes a turbine bypass pipe which is connected to the main steam pipe 17 and bypasses the steam turbine 9 and directly guides the steam to the condenser 10. Reference numeral 19 denotes a steam turbine control valve for adjusting the flow rate of steam to the steam turbine 9, reference numeral 20 denotes a turbine bypass valve for adjusting the amount of steam bypass by the amount of steam supplied to the steam turbine 9, and reference numeral 21 denotes a damper for the exhaust gas passage 2. It is. As described above, the superheater 3, the first evaporator 4, the second evaporator 6, and the economizer 7 are incorporated in the waste heat recovery boiler to recover the heat of the untreated gas G. A denitration device 5 for denitration of the untreated gas G is arranged. FIG. 6 is a longitudinal sectional view of a conventional denitration apparatus, and FIG. 7 is a perspective view of a conventional catalyst block. In these figures, 2 is an exhaust gas passage, 5 is a denitration device, 22 is a catalyst unit, 23 is a catalyst block, 24 is a catalyst block frame, 25
Is a V-shaped plate. The catalyst block 23 is formed by stacking the catalyst units 22 in a catalyst block frame 24 as shown in FIG. 7, and this catalyst block 23 is stacked in the exhaust gas passage 2 as shown in FIG. It is configured. However, as described above, as the capacity of the combined cycle power plant increases, the amount of catalyst charged into the denitration apparatus 5 by the catalyst block 23 increases, and recently, the power in the plant is reduced. For this purpose, it is also required to increase the gas passage cross-sectional area of the denitration device 5 to reduce the pressure loss. In such a combined cycle power plant,
Since the number of stacking stages of the catalyst block 23 increases,
Catalyst block 23 arranged below exhaust gas passage 2
Has a drawback that it buckles due to the integrated vertical load due to the weight of the catalyst block 23 disposed above. A first object of the present invention is to provide a denitration apparatus which solves the conventional drawbacks, prevents buckling of a catalyst block disposed at a lower portion, is inexpensive, and has excellent denitration performance. It is in. A second object of the present invention is to provide a denitration apparatus capable of resolving such a conventional drawback and effectively preventing buckling of a catalyst block disposed below. According to the present invention, a catalyst block composed of a plurality of catalyst units and a frame surrounding the outside of the catalyst unit assembly is stacked in an exhaust gas passage and flows through the exhaust gas passage. A denitration apparatus for denitrifying untreated gas to be treated with the catalyst block. According to a first aspect of the present invention, a catalyst having a low height is provided at a lower portion of the exhaust gas passage.
Place the block on top of its low catalyst block
The catalyst blocks having a high height are stacked, and the vertical load supporting portions forming a part of the frame of each of the catalyst blocks have substantially the same plate thickness, and the width of each of the catalyst blocks is substantially the same. . In order to achieve the second object, the second
According to the present invention, a catalyst block having a low height is provided at a lower portion of the exhaust gas passage.
Position the block and place it above the low catalyst block.
Higher catalyst blocks are stacked , and at least a part of the vertical load supporting portion of the lower catalyst block is constituted by a member having a bent cross-sectional shape. DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the first and second embodiments of the present invention use a low-height catalyst block at the bottom of an exhaust gas passage.
And place the tall catalyst block on the low-height catalyst.
It is configured to be stacked on the medium block . By doing so, the buckling strength of the lower catalyst block is increased, and the occurrence of a buckling accident can be prevented. In the first aspect of the present invention, since each catalyst block uses a member having substantially the same plate thickness as the vertical load supporting portion, the catalyst block can be manufactured at low cost. Moreover, since the vertical load supporting portions have substantially the same thickness and the width of each catalyst block is substantially the same, there is no gap due to the difference in size between the catalyst blocks. Therefore, the amount of leakage of the untreated gas is small, and the denitration performance can be improved. In the second aspect of the present invention, at least a part of the vertical load supporting portion of the catalyst block having a low height is formed of a member having a bent cross-sectional shape. The buckling strength of the lower catalyst block becomes extremely high due to the synergistic effect of reducing the height of the catalyst block, and the buckling accident can be reliably prevented. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a denitration apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are perspective views of a catalyst block loaded in the denitration apparatus, and FIG. 4 is a V used in the catalyst block.
It is a partially expanded perspective view of a template. In these figures, reference numerals 5 to 25 denote the same parts as those of the conventional one, but for convenience of explanation, of the catalyst blocks 23, catalyst blocks 23a having a lower height are designated as 23a,
The tall catalyst block is designated as 23b. As described above, the catalyst block 23 is composed of a plurality of catalyst units 22 and a frame composed of a catalyst block frame 24 and a V-shaped plate 25 surrounding the outside of the aggregate of the catalyst units 22. As shown in FIG. 2, the catalyst block 23a having a low height lowers the height of the catalyst unit assembly, and has a vertical load supporting portion forming a part of the frame.
That is, the height of the vertical portion of the catalyst block frame 24 and the V-shaped plate 25 which receives the vertical load is also reduced. On the other hand, as shown in FIG. 3, the tall catalyst block 23b raises the height of the catalyst unit assembly and, as shown in FIG. The height of the vertical portion of the template 25 that receives the vertical load is also increased. Next, the vertical load applied to the lowermost catalyst block 23 will be described with reference to FIG. Here, assuming that the load per catalyst block 23 is w and the number of stacked catalyst blocks 23 is n, the integrated vertical load W applied to the lowermost catalyst block 23 is W = (n−1) × w. The accumulated vertical load W is supported by a vertical load supporting portion such as a V-shaped plate 25 on the side surface of the catalyst block 23. The allowable supporting load P supported by the vertical load supporting portion is equal to that of the same member. It has the following relationship with the height H of the block 23. (1) When the height H of the catalyst block 23 is low, P∝ (1-H ² ) (2) When the height H of the catalyst block 23 is high, P∝1 / H ² As described above, the catalyst block 23 The lower the height H of the
The allowable supporting load P, that is, the rigidity increases. When the catalyst block 23 has the same height H, the relation between the plate thickness t of the vertical load supporting portion such as the V-shaped plate 25 and the allowable supporting load P is given by the following equation. Is increased, the allowable supporting load P increases. Accordingly, the catalyst block 23 disposed at the lower portion where the integrated vertical load W is large has a low height or a plate thickness t of the vertical load supporting portion such as the V-shaped plate 25, which increases the rigidity. It needs to be raised. Here, conventionally, the catalyst block 23 having the same specifications as the catalyst block 23 sufficiently withstanding the lowermost load condition is stacked or the thickness of the vertical load supporting portion such as the V-shaped plate 25 of the catalyst block 23 disposed at the lower portion. Measures such as increasing t were taken. However, in the former method, excessive design is required, which leads to an increase in cost and a catalyst block 23 per unit.
Weight becomes heavy. When the thickness t of the vertical load supporting portion is increased as in the latter case, the weight of the catalyst block 23 increases, and the thickness of the vertical load supporting portion differs between the upper side and the lower side. Moreover, the difference in the width of the upper and lower catalyst blocks 23 causes a gap in the exhaust gas passage 2, which has the disadvantage that the untreated gas leaks and the denitration performance is reduced. In the present invention, as shown in FIG. 1, the height of the vertical load supporting portion and the height of the catalyst unit assembly, which are a part of the frame, is low, that is, the catalyst block 23a having high buckling strength is used. A high rigidity block layer is formed by stacking several stages below the exhaust gas passage. Then, the catalyst block 23b having a high height of the vertical load supporting portion forming a part of the frame and the height of the catalyst unit assembly is stacked on the catalyst block 23a having a low height in several stages to constitute a denitration apparatus. are doing. [0035] The lower this way a large integrated vertical load applied, placing the height low catalyst block 23a having a rigidity against buckling, height to top of it which is less integrated vertical load exerted than Buckling accident of the lower catalyst block 23 can be effectively prevented by arranging the catalyst block 23b having a high height. Further, since each catalyst block 23 uses a member having the same plate thickness as a vertical load supporting portion, the catalyst block 23 can be manufactured at low cost. In addition, since the vertical load supporting portions have the same thickness and the widths of the catalyst blocks 23 are substantially the same, no gap is formed due to the difference in size of the catalyst blocks 23. Therefore, the amount of leakage of the untreated gas is small, and the denitration performance can be improved. In the above embodiment, the case of the horizontal flow type denitration apparatus used in the combined cycle power plant has been described.
The present invention is not limited to this, and can also be applied to a vertical flow type denitration apparatus used in other power plants that burn dardy fuel such as heavy oil or coal that has more dust than clean fuel such as LNG or kerosene. . According to the first and second aspects of the present invention, as described above, a catalyst block having a low height is arranged at a lower portion of an exhaust gas passage.
And replaces the tall catalyst block with the low catalyst block.
It is configured to be stacked on the Tsuk . By doing so, the buckling strength of the lower catalyst block is increased, and the occurrence of a buckling accident can be prevented. In the first embodiment of the present invention, since each catalyst block uses a member having substantially the same plate thickness as the vertical load supporting portion, the catalyst block can be manufactured at low cost. Moreover, since the vertical load supporting portions have substantially the same thickness and the width of each catalyst block is substantially the same, there is no gap due to the difference in size between the catalyst blocks. Therefore, the amount of leak of the untreated gas is small and the denitration performance can be improved. In the second aspect of the present invention, at least a part of the vertical load supporting portion of the catalyst block having a low height is formed of a member having a bent cross-sectional shape. The buckling strength of the lower catalyst block becomes extremely high due to the synergistic effect of reducing the height of the catalyst block, and the buckling accident can be reliably prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a denitration apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of a low-height catalyst block used in the denitration apparatus. FIG. 3 is a perspective view of a tall catalyst block used in the denitration apparatus. FIG. 4 is a partially enlarged perspective view of a V-shaped plate used for the catalyst block. FIG. 5 is a schematic system diagram of a combined cycle power plant. FIG. 6 is a longitudinal sectional view of a conventional denitration apparatus. FIG. 7 is a perspective view of a catalyst block used in a conventional denitration apparatus. [Description of Signs] 2 Exhaust gas passage 5 DeNOx device 22 Catalyst unit 23 Catalyst block 23a Low-height catalyst block 23b Low-height catalyst block 24 Catalyst block frame 25 V-shaped plate G Unprocessed gas t Plate thickness

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 53/94

Claims (1)

(57) [Claims] The catalyst block composed of a frame surrounding the outside of the plurality of catalyst Yunitsuto and their catalytic Yunitsuto assemblies stacked on the exhaust gas passage, in the untreated gas flowing through the exhaust gas passage which denitration by the catalyst block, the exhaust gas A low catalyst block is placed at the bottom of the passage
And, tall catalyst blow on the low catalyst block with a height
A denitration apparatus , wherein the blocks are stacked, the vertical load supporting portions forming a part of the frame of each of the catalyst blocks have substantially the same thickness, and the width of each of the catalyst blocks is substantially the same. 2. The catalyst block composed of a frame surrounding the outside of the plurality of catalyst Yunitsuto and their catalytic Yunitsuto assemblies stacked on the exhaust gas passage, in the untreated gas flowing through the exhaust gas passage which denitration by the catalyst block, the exhaust gas A low catalyst block is placed at the bottom of the passage
And, tall catalyst blow on the low catalyst block with a height
A denitration apparatus , wherein at least a part of the vertical load supporting portion of the catalyst block having a low height is formed of a member having a bent cross-sectional shape.