JPS63220012A - Boiler equipment with gas bypass line - Google Patents

Abstract

PURPOSE:To contrive to flow the gas of high temperature zone to the side of an exhaust gas denitrating unit, by providing the intake of gas of a gas bypass line on the wall of a rear flue on the upstream side of a heat transfer pipe, and by providing the intake of gas to the gas draft fan which is located on the downstream side of a heat transfer pipe below the vicinity of the intake of gas of a gas bypass line. CONSTITUTION:The intake of gas 4a of a gas bypass duct 4 is provided on the rear wall 2a of a rear flue 2 on the upstream side of a heat transfer pipe 11, and the intake of gas 7a of a gas duct 7 is provided on the side of a hopper 5 which is located under the intake of gas 4a. When the opening of a damper 12 is increased at the time when the load to a boiler is decreased, the isokinetic distribution of gas, in which the velocity of flowing gas is quicker as it is closer the intake of gas 4a, is formed. The gas, passing through the heat transfer pipe 11 forms an isothermal distribution, in which low temperature zone is formed below the vicinity close to the intake of gas 4a, and in which high temperature zone is formed blow the neighborhood far from the intake of gas 4a. Accordingly most of gas induced by a gas draft fan 10 is the gas of low temperature zone when the position of the intake of gas 7a of a gas duct 7 to the gas draft fan 10 is provided below the direction of the intake of gas 4a on the side of a hopper 5. Most of gas flowing into an exhaust-gas denitrating unit 8 will be the gas of high temperature zone.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention has a heat exchanger tube in the rear flue, and takes gas from the downstream side of the heat exchanger tube to a gas ventilator and a flue gas denitrification device.
The present invention relates to a boiler device having a gas bypass system for extracting gas from the upstream side of a heat transfer tube to a flue gas denitrification device, and particularly to an improvement in the installation position of the gas outlet.

Prior art FIGS. 12 and 13 show a conventional boiler device, where l is a boiler furnace, 2 is a rear flue, 4 is a gas bypass duct, 5 is a hopper, 8 is a flue gas denitrification device, and 10 is a gas ventilator.

A heat exchanger tube 11 is provided in the rear flue 2 provided at the rear of the boiler furnace l, and the gas bypass duct 4 is connected to the rear wall 2a of the rear flue 2 on the upstream side of the heat exchanger tube 11.
A flue gas denitrification device 8 is installed with a gas outlet 4a provided in the
is connected to. In the hopper 5 downstream of the heat exchanger tube 11,
a gas extraction lower a to the gas passage 7 to the gas ventilator 10;
Further, a gas outlet 6a of the gas passage 6 to a downstream flue gas denitrification device 8 and a heat exchanger (not shown) is provided, and a gas bypass duct 4 is connected to the gas passage 6.

The gas bypass duct 4 and the gas passage 6 are each provided with a damper 12, 13, so that the gas flow rate can be adjusted.

By the way, in the boiler device, the temperature of the flue gas denitrification device 8 is
It is necessary to control the temperature within a range that allows efficient denitrification, and also to ensure that heat exchange with other fluids is performed efficiently in the heat exchanger located downstream of the flue gas denitrification equipment. The inlet gas temperature must be controlled to maintain a suitable temperature range.

Problems to be Solved by the Invention When the load on the boiler decreases, the temperature of the gas flowing through the gas passage 6 decreases, so the opening degree of the damper 12 is increased and the opening degree of the damper 13 is decreased, and the gas bypass duct is closed. The flow rate of the high temperature gas from 4 is increased to control the temperature of the flue gas denitrification device 8 so as not to drop. Looking at the uniform velocity distribution of the gas flow in front of the gas outlet 4a of the gas bypass duct 4 at that time, as shown in Fig. 14a, the gas outlet 4a
It can be seen that the speed is faster in places closer to .

Due to this influence, an uneven flow of gas occurs in that the amount of gas passing through the heat transfer tube 11 becomes smaller at a location near the gas outlet 4a. As a result, heat exchanger tube 1
As shown in FIG. 14b, the temperature of the outlet gas heat-exchanged in step 1 has an equal temperature distribution with a low temperature region near the gas outlet 4a and a high temperature region far from the gas outlet 4a. Therefore, as shown in FIG. 14c, most of the gas in the high temperature range is sucked into the gas ventilator 10, and most of the gas flowing into the flue gas denitrification device 8 is
As shown in Figure 4d, there was a problem that the gas was in the low temperature range.

To solve this problem, it is possible to take in a large amount of high-temperature gas from the gas bypass duct 4 when the boiler load decreases, but to do so, the capacity of the gas bypass duct 4 must be increased. This results in the inconvenience of increased costs.

In addition, in order to take in a large volume of high-temperature gas into the gas bypass duct 4, it is necessary to reduce the opening degree of the damper 13, and as a result, each part of the boiler furnace located upstream of the damper 13 becomes higher. However, there is a problem in that the power burden of a forced draft fan (not shown) that supplies combustion air to the boiler or an induced draft fan that sucks combustion gas from the boiler is increased.

As shown in FIGS. 15 and 16, conventionally, there is a gap 20 between the boiler furnace l and the rear flue 2, and the gas outlet lower a of the gas passage 7 to the gas ventilator lO is located at the center of the boiler. A boiler device installed near line 21 is also known, but this boiler device also had the same problem as described above. In FIGS. 15 and 16, the same parts as in FIGS. 12 and 13 are given the same reference numerals, so
The explanation of that part will be omitted.

Means for Solving the Problems In order to solve the above problems, the present invention includes a heat transfer tube in the rear flue, and supplies gas from the downstream side of the heat transfer tube to the gas ventilator and the flue gas denitrification device. In a boiler apparatus having a gas bypass system, the gas is taken out from the upstream side of the heat exchanger tubes to the flue gas denitrification device, and the gas outlet of the gas bypass system is connected to the rear part of the upstream side of the heat exchanger tubes. A boiler device having a gas bypass system provided in a wall of a flue, and a gas outlet for the gas ventilator located downstream of the heat transfer tube is provided below near the gas outlet of the gas bypass system. provide.

Effect: According to the above means, the gas in the low temperature range formed below the gas outlet of the gas bypass duct is sucked into the gas outlet to the gas ventilator, and the gas in the high temperature range is directed to the flue gas denitrification device. As a result, conventional problems can be solved.

EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to FIGS. 1 to 11. In FIGS. 1 to 11, the same parts as in FIGS. 12 to 16 described as the conventional example are given the same reference numerals, and therefore the description of these parts will be omitted.

First, regarding the first embodiment, FIGS. 1, 2, and 33
The explanation will be given with reference to Figures 3D and 3D. Figure 1 is a schematic longitudinal sectional side view of the boiler equipment, and Figure 2 is a schematic vertical side view of the boiler device, and Figure 2 is a diagram showing ■-■ of Figure 1.
Linear direction arrow view, Figure 3a is an explanatory diagram of the uniform velocity distribution of gas flow in the a-a line section of Figure 1, Figure 3b is the illustration of b in Figure 1.
Fig. 3C is an explanatory diagram of the isotemperature distribution of the gas flow in the section line C-C in Fig. 1. Fig. 3d is an explanatory diagram of the isotemperature distribution of the gas flow in the section line C-11 in Fig. 1. FIG. 3 is an explanatory diagram of the isotemperature distribution of gas flow in a line portion.

In the first embodiment, the gas outlet 4a of the gas bypass duct 4 is provided in the rear wall 2a of the rear flue 2 on the upstream side of the heat transfer tube 11, and the gas outlet lower a of the gas passage 7 is provided in the gas outlet 4a. It is provided on the side of the hopper 5 located below.

In this way, when the opening degree of the damper 12 is increased when the load on the boiler is reduced, a uniform velocity distribution of the gas is formed in which the flow velocity is faster closer to the gas outlet 4a, as shown in FIG. 3a. Due to this influence, the gas passing through the heat exchanger tube 11 has an equal temperature distribution with a low temperature region below near the gas outlet 4a and a high temperature region far below, as shown in FIG. 3b. therefore,
As shown in FIG. 3C, by providing the position of the extraction lower a of the gas passage 7 to the gas ventilator 10 on the side of the hopper 5 on the rear wall 2a side of the rear flue 2, that is, on the lower side in the direction of the gas extraction port 4a, Most of the gas sucked into the gas ventilator 10 is in a low temperature range. Moreover, even if the position of the outlet 6a of the gas passage 6 is the same as before, most of the gas flowing into the flue gas denitrification device 8 is gas in a high temperature range, as shown in FIG. 3d.

Next, a second embodiment will be described with reference to FIGS. 4, 5, and 6a to 6d.

In the second embodiment, as shown in FIG. 4 and FIG. They are placed above and below each other.

In this case as well, the effect of the gas extraction lower a is almost the same as in the first embodiment, and a uniform velocity distribution is formed as shown in FIG. 6a, in which the gas velocity is faster as the gas is closer to the gas extraction port 4a. Due to the influence of the uniform velocity distribution, a uniform temperature distribution Z is formed downstream of the heat exchanger tube 11 as shown in FIG. 6b.

Therefore, as shown in FIG. 6C, by providing the position of the take-out lower a of the gas passage 7 to the gas ventilator 10 on the side surface of the hopper 5, that is, on the side surface 2b of the rear flue 2, the gas is sucked into the gas ventilator lO. Most of the gas will be in the low temperature range.

Furthermore, as shown in Fig. 6d, which is in the same position as Fig. 6C,
Even if the position of the take-out lower a of the gas passage 7 to the gas ventilator 10 is provided at the bottom of the hopper 5 in the direction of the side wall 2b, the same effect as described above can be obtained.

Furthermore, other embodiments of the present invention will be explained with reference to FIGS. 7, 8, and 9a to 9d.

In the snake embodiment, the gas outlet 4 of the gas bypass duct 4
a is provided upstream of the heat exchanger tube 11 at the front wall 2c of the rear flue 2,
The gas extraction lower a of the gas passage 7 is arranged below near the boiler centerline 21.

Therefore, when the voicing buttock load decreases, the opening degree of the damper 12 is increased (
Then, as shown in FIG. 9a, a uniform velocity distribution is formed in which the gas flow velocity is faster closer to the gas outlet 4a. Due to this influence, the gas passing through the heat transfer tube 11 has an equal temperature distribution with a low temperature region below near the gas outlet 4a and a high temperature region far below, as shown in FIG. 9b. Therefore, as shown in FIG. 9c, the gas outlet lower a of the gas passage 7 to the gas ventilator 10 is
Even if the position is the same as before, most of the gas sucked into the gas ventilator 1O will be gas in the low temperature range. Further, even if the gas passage 6 is circular as in the conventional case, most of the gas flowing into the flue gas denitrification device 8 is in the high temperature range, as shown in FIG. 9d.

Further, FIGS. 10 and 11 show still another embodiment of the present invention, in which a gas outlet 4a of a gas bypass duct 4 is shown.
It is the same as that shown in FIGS. 7 and 8 except that it is provided on the front wall 2c of the rear flue 2 closer to the side wall 2b, and in this case as well, the same effect is achieved.

Effects of the Invention The present invention has been described with reference to various embodiments, but the present invention provides a boiler system having a gas bypass system in which the gas outlet to the gas ventilator is located near the gas outlet to the gas bypass duct, that is, By installing the gas outlet of the gas bypass duct on the same wall of the rear flue where the gas outlet is located, or on the same wall as the other wall, it is possible to increase the opening of the damper of the gas bypass duct at low loads. At this time, low-temperature gas can be sent to the gas ventilator side, and high-temperature gas can be made to flow to the flue gas denitration equipment side.

Therefore, a boiler device is provided that greatly contributes to energy saving, such as reducing the capacity of the gas bypass duct and reducing the power burden of the forced draft fan and induced draft fan.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view schematically showing an embodiment of a boiler device according to the present invention, FIG. 2 is a view taken along the line ■-■ in FIG. 1,
Figures 38 to 3d are gas flow velocity and gas temperature distribution diagrams for explaining the present invention in detail, and Figures 4, 7, and 10 are diagrams of boiler apparatuses according to other embodiments of the present invention, respectively. The schematic longitudinal side views, Figures 5, 8, and 11 correspond to the V-V line, ■-■ line, and X[-XI line direction in Figures 4, 7, and 10, respectively. Figures 6a to 6d and 9a to 9d are gas flow rate and gas temperature distribution diagrams for explaining the effects of each embodiment, and Figures 12 and 15 are conventional diagrams, respectively. FIGS. 13 and 16 are longitudinal sectional side views schematically showing the boiler equipment of FIGS.
The I-XVI line direction arrow views and FIGS. 14a to 14d are distribution charts of gas flow velocity and gas temperature shown to explain the problems of the conventional boiler device. ■... Boiler furnace, 2... Rear flue, 4... Gas bypass duct, 4a, 7a... Gas outlet, 5... Hopper,
6.7... Gas passage, 8... Flue gas denitrification device, 10... Gas ventilator, 11... Heat exchanger tube, 12° (1 other person) Fig. 1/U Fig. 2 Fig. 4 Fig. 5 Figure 6α Figure 6C Figure 6'b Figure bd Figure 9α Figure 9° Figure 9b Figure 10 Figure 42 Figure 43 Figure 1 α Figure 74c Figure 74b Figure 15 Figure 16 figure

Claims (1)

[Claims] A heat transfer tube is provided in the rear flue, and gas is taken out from the downstream side of the heat transfer tube to the gas ventilator and the flue gas denitrification device, and gas is also taken out from the upstream side of the heat transfer tube to the flue gas denitrification device. In a boiler apparatus having a gas bypass system, a gas outlet of the gas bypass system is provided on the wall of the rear flue on the upstream side of the heat exchanger tube, and the gas outlet is connected to the gas ventilator located on the downstream side of the heat exchanger tube. A boiler device having a gas bypass system, wherein the gas intake port is provided below near the gas intake port of the gas bypass system.