KR102629382B1 - Low-Nox Boiler system for preventing overheating of boiler tubes - Google Patents

Abstract

The boiler system includes a burner that burns supplied gas to generate a flame, a plurality of water pipes heated by the burner, a water pump that supplies water to the plurality of water pipes, heated steam in the plurality of water pipes, and It consists of a water separator for separating water, and an economizer installed on the discharge path of the burned gas and preheating the water supplied into the plurality of water pipes through heat exchange with the combustion gas.
The plurality of water pipes include a first water pipe disposed adjacent to the burner and having a first water level, and a second water pipe disposed in parallel with the first water pipe and having a second water level lower than the first water level.
The lower end of the first water pipe passes through the lower header plate and communicates with the first water jacket, and the lower end of the second water pipe passes through the lower header plate and communicates with a second water jacket isolated from the first water jacket. , the upper end of the first water pipe and the upper end of the second water pipe pass through the upper header plate and are in common communication with the wet steam chamber.
The water pump supplies water to the first water jacket through the water pump, and when the supplied water fills the first water pipe and overflows to the top of the first water pipe, the water pump supplies water to the first water jacket. 2 The water pipe is filled with water at the second water level.

Description

Low-Nox Boiler system for preventing overheating of boiler tubes}

The present invention relates to a boiler system that mixes fuel gas and combustion air to form a flame.

Conventionally, in boilers using gas or oil as fuel, there is a need to reduce emissions of NOx, carbon monoxide (CO), etc. as harmful combustion waste due to problems such as air pollution.

Conventional low-Nox technologies include diffusion combustion using split flames and premixed combustion. However, in areas with high air ratios, the premixed combustion method has a better flame cooling effect than the diffusion combustion method, so the generation of rust can be suppressed. However, in low air ratio areas, the premixed combustion method has limitations in suppressing the occurrence of rust because the combustion speed increases and the flame temperature rises compared to the diffusion combustion method.

Therefore, in small boilers, etc., as described above, combustion with a low air ratio under high load combustion conditions generates rust, and therefore fuel cannot be burned at a low air ratio, so the premixed combustion method is generally known to be the best low-nox combustion method.

The fuel used in this premixed combustion method may be LNG or LPG, or a gas in which LNG or LPG is partially mixed with hydrogen (H2). The flame generated from the combustion of this fuel gas comes into contact with a plurality of water tubes installed side by side in the vertical direction and heats the water inside the water tubes, in order to reduce thermal NOx generated from the burner. A plurality of screen tubes are placed in close proximity to the burner (position in direct contact with the flame). These screen tubes are also filled with water and play a role in lowering the temperature of the flame emitted from the burner, which is called flame quenching. If the temperature of the flame is reduced in this flame quenching, the occurrence of rust is reduced accordingly.

However, while the screen tube plays a role in lowering the high flame temperature, the screen tube overheats, and as this process is repeated, damage such as cracks is likely to occur on the outer surface of the screen tube. Operating the boiler system with these screen tubes damaged will not only increase the emissions of thermal rust, but may also cause irreparable damage to the entire boiler system. Therefore, there is a need to develop a technology that can prevent damage due to overheating of the screen tube while lowering the temperature of the flame by using a screen tube disposed near the burner.

Korean Patent Publication No. 2496816 (registered on February 2, 2023)

The technical problem to be achieved by the present invention is to provide a low-nox boiler system in which the screen tube is placed near the burner to lower the temperature of the flame emitted by the burner, thereby preventing damage to the screen tube and reducing the generation of rust.

Another technical problem to be achieved by the present invention is to provide a low NOx boiler system that can always keep the water level in the screen tube high to prevent the screen tube from being overheated and damaged.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

A boiler system according to an embodiment of the present invention for achieving the above technical problem includes a burner that generates a flame by burning supplied gas; a plurality of water pipes heated by the burner; a water pump supplying water to the plurality of water pipes; a water separator that separates heated steam and water in the plurality of water pipes; and an economizer installed on the discharge path of the burned gas and preheating the water supplied into the plurality of water pipes through heat exchange with the combustion gas, wherein the plurality of water pipes are disposed adjacent to the burner and It includes a first water pipe having a water level of 1, and a second water pipe disposed in parallel with the first water pipe and having a second water level lower than the first water level, and the lower end of the first water pipe passes through the lower header plate. 1 communicates with a water jacket, and the lower end of the second water pipe passes through the lower header plate and communicates with a second water jacket isolated from the first water jacket, and the upper end of the first water pipe and the upper end of the second water pipe passes through the upper header plate and is in common communication with the wet steam chamber. The water pump supplies water to the first water jacket through a water supply valve, and the supplied water fills the first water pipe to fill the water pipe. When the water overflows to the top of the first water pipe, the second water pipe is filled with water at the second water level.

The first water jacket and the second water jacket are formed by separating a single chamber by a partition.

Even if the water overflows and flows into only some of the water pipes of the second water pipes, the second water jacket is filled with water, and the lower end of the second water pipe communicates with the second water jacket. The overall water level is maintained the same as the second water level.

In order to maintain the first water level of the first water pipe sufficiently high, a step protruding higher than the upper header plate into the wet steam chamber is formed between the area of the first water pipe and the area of the second water pipe.

The boiler system further includes a water level sensor that detects the water level of the second water pipe, and when the water overflows from the first water pipe and the water level of the second water pipe rises, the water level sensor detects the water level of the second water pipe. When the water level in the water pipe is detected to have reached the target level, the supply of water by the water pump is stopped.

In addition to the water supply valve, an additional valve is further provided to allow or block the supply of water directly to the second water jacket.

By opening the chamber valve and supplying water to the first water jacket by the water pump, the first water pipe and the second water pipe are filled with water to a predetermined level, and then the chamber valve is closed and the water pump is supplied. By supplying water to the first water jacket, the water level of the first water pipe is further increased.

According to the boiler system according to the present invention, the generation of rust can be reduced by placing the screen tube near the burner to lower the temperature of the flame emitted by the burner.

In addition, according to the boiler system according to the present invention, the water level in the screen tube can always be maintained high to prevent the screen tube from overheating and being damaged.

In addition, according to the boiler system according to the present invention, the water level in the screen tube can be maintained high at all times while the water level in the remaining heat transfer tubes can be kept low to an appropriate level.

And, according to the boiler system according to the present invention, simply by supplying water to the screen tube, water can be automatically supplied to the remaining heat transfer tubes.

1 is a front view showing a boiler system according to an embodiment of the present invention.
FIG. 2 is a longitudinal cross-sectional view showing the boiler main body of the boiler system of FIG. 1.
Figure 3 is a cross-sectional view of the boiler body of Figure 2 cut in the AA' direction.
Figure 4 is a diagram showing water from the first water pipe overflowing into the second water pipe within the wet steam chamber.
Figure 5 is a longitudinal cross-sectional view showing a boiler main body according to another embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings that can be commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless clearly specifically defined.

The terminology used herein is for describing embodiments and is not intended to limit the invention. As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. As used in the specification, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other elements in addition to the mentioned elements. Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a front view showing a boiler system 100 according to an embodiment of the present invention.

The boiler system 100 includes an economizer 10, a combustion gas discharge path 20, a feed water pump 30, a water separator 40, an air blower 50, an air supply path 55, and a boiler body ( 200).

The feed water pump 30 pumps and supplies water provided from a supply source (not shown) to the water supply chamber 70 below the boiler body 200. The supplied water is stored in the water supply chamber 70, and the stored water is provided to a plurality of water tubes 90 connected to the water supply chamber 70.

The boiler body 200 may be composed of a plurality of water pipes 90, a combustion chamber 80, and a burner 85.

The combustion chamber 80 is a space where gas is burned, and the burned gas is discharged to the combustion gas discharge path 20. As described above, the plurality of water pipes 90 are connected to the water supply chamber 70 and can accommodate water and water vapor heated by a flame in the combustion chamber 80. Accordingly, the combustion chamber 80 and the water pipe 90 are disposed adjacent to each other in the same space.

The burner 85 is installed adjacent to the combustion chamber 80, generates a flame, and heats water and/or water vapor held in the water pipe 90 through the flame. To create this flame, the burner 85 mixes air and fuel gas and combusts the mixed gas. The air may be forced by the air blower 50 and supplied to the burner 85 through the air supply path 55.

The water separator 40 is connected to the plurality of water pipes 90 and serves to separate the heated water vapor and water. The water vapor and/or water separated in the water separator 40 may be supplied to a remote location through separate circulation paths. Alternatively, when the boiler system 100 uses only water vapor, the water may be separated in the water separator 40 and recirculated.

The economizer 10 is installed on the combustion gas discharge path 20 and can preheat the water supplied into the water supply chamber 70 through heat exchange with the combustion gas. Specifically, the economizer 10 has a pipe that supplies water to the water jacket 70, recovers the sensible heat and latent heat of condensation of the high-temperature combustion gas, and serves to preheat the water flowing through the pipe.

FIG. 2 is a longitudinal cross-sectional view showing the boiler body 200a of the boiler system 100 of FIG. 1.

Referring to FIG. 2, the burner 85 combusts the supplied fuel/air mixed gas to generate a flame FL, thereby heating the plurality of water pipes 90 (91, 92). The plurality of water pipes 90 are connected to the water supply chamber 70, and water is supplied to the plurality of water pipes 90 by the water pump 30. At this time, the steam and water heated within the plurality of water pipes 90 are separated in the water separator 40.

An economizer 10 is installed on the discharge path 20 of the burned gas, and the economizer 10 preheats the water supplied to the water supply chamber 70 through heat exchange with the combustion gas. The preheated water flows into the first water jacket 71 through the water supply valve (35 in FIG. 1) (W in).

Here, the plurality of water pipes 90 include a first water pipe 91 that functions as a screen tube and a second water pipe 92 for generating steam. The first water pipe 91 is disposed closer to the burner 85 than the second water pipe 92. In the present invention, when the boiler system 100 is in operation, the water level (first water level) of the first water pipe 91 is formed to be higher than the water level (second water level) of the second water pipe 92.

The lower end of the first water pipe 91 passes through the lower header plate 75 and communicates with the first water jacket 71, and the lower end of the second water pipe 92 passes through the lower header plate 75. It communicates with the first water jacket 71 and the isolated second water jacket 72. In addition, the upper end of the first water pipe 91 and the upper end of the second water pipe 92 pass through the upper header plate 65 and are in common communication with the wet steam chamber 60. At this time, the first water jacket 71 and the second water jacket 72 may be formed by separating a single water supply chamber 70 by a partition 73.

FIG. 3 is a cross-sectional view of the boiler body 200a of FIG. 2 taken along the A-A' direction.

As shown, the first water pipe 91 is disposed in an area closer to the burner 85 and the second water pipe 92 is disposed in an area farther away from the burner 85 than the first water pipe 91. Therefore, the flame FL generated by the burner 85 directly contacts only the first water pipe 91, but the combustion heat generated by the combustion gas in the combustion chamber 80 penetrates all the water pipes 90 (91, 92). All serve to heat.

Here, since the upper ends of the first water pipe 91 and the second water pipe 92 are both in communication with the upper header plate 65, the water vapor generated in all the water pipes 91 and 92 is directed to the upper header plate 65. It is collected into the wet steam chamber (60). In addition, areas other than the tops of all water pipes 91 and 92 are blocked by the upper header plate 65, so when the water filled in the first water pipe 91 overflows, the overflowed water It can only flow into the second water pipe 92.

FIG. 4 is a diagram showing water in the first water pipe 91 overflowing into the second water pipe 92 within the wet steam chamber 60.

The water pump 30 supplies water to the first water jacket 71 through the water supply valve 35. Accordingly, when the supplied water fills the first water pipe 91 and overflows to the top of the first water pipe 91, the second water pipe 92 can be filled with water. there is. The water pump 30 supplies water to the first water jacket 71 until the water in the second water pipe 92 is filled to the target water level L2. That is, according to one embodiment of the present invention, water is not directly supplied from the water pump 30 to the second water jacket 72. At this time, the water level (first water level) (L1) of the first water pipe (91) may be full, but since the water in the first water pipe (91) is also evaporated when the boiler system (200a) is operated, the first water level (L1) The water level may also be gradually lowered from the full water level.

Meanwhile, even if the water in the first water pipe 91 overflows and flows into only some of the second water pipes 92, the second water jacket 72 is filled with water. At this time, since the lower ends of all second water pipes 92 are in communication with the second water jacket 72, the water level L2 of the entire second water pipe 92 is maintained at the same level as the second water level L2. It can be.

In addition, the boiler body 200a may further include water level sensors (not shown) that detect the water levels L1 and L2 of the first water pipe and/or the second water pipe 92. When the water overflows from the first water pipe 91 and the water level L2 of the second water pipe 92 rises, the water level L2 of the second water pipe 92 is increased by the second water level sensor. When it is detected that the target water level (e.g., 50% water level) has been reached, the operation of the water pump 30 may be stopped. Alternatively, when the second water level (L2) is sufficient but the first water level (L1) is insufficient, while operating the water pump (30), the water level (L1) of the first water pipe (91) is set to the target by the first water level sensor. When it is detected that the water level (e.g., full water level) has been reached, the operation of the water pump 30 can be stopped.

That is, the water pump 30 can operate at any time to maintain the first water level (L1) and the second water level (L2) at their respective target water levels. However, in any case, the first water level (L1) must be maintained higher than the second water level (L2).

Figure 5 is a longitudinal cross-sectional view showing a boiler main body 200b according to another embodiment of the present invention. The embodiment of FIG. 5 has the same configuration as the embodiment of FIG. 2 except for the step portion 63 and the fact that water flows into the second water jacket 72 (W2 in), so duplicate description will be omitted. The description will focus on the above additional components.

The step portion 63 is formed between the area of the first water pipe 91 and the area of the second water pipe 92 in order to maintain the first water level L1 of the first water pipe 91 sufficiently high. . Additionally, the stepped portion 63 protrudes higher than the upper header plate 65 into the wet steam chamber 60. In the case where there is no step 63, even if the water level (L1) of the first water pipe (91) is full, there is a possibility that the water level of the first water pipe (91) will be lowered in a short period of time due to the overflow process or evaporation, which may result in the screen tube It may be difficult to sufficiently protect the first water pipe 91 from the high temperature flame FL. That is, the step portion 63 maintains the first water level L1 sufficiently high to prevent the first water pipe 91 from being damaged by high temperature and at the same time lowers the temperature of the flame FL to prevent the occurrence of rust. It can definitely be reduced.

Meanwhile, in addition to the water supply valve 35 that controls the inflow of water into the first water jacket 71, an additional valve (see 37 in FIG. 1) is further provided to control the inflow of water into the second water jacket 72. It can be. Water supplied through the additional valve 37 may flow directly into the second water jacket 72 (W2 in). For this purpose, a water supply valve 35 may be disposed at the end of the water supply pipe (see 39 in FIG. 1), and an additional valve 37 may be installed in the middle of the water supply pipe 39. Therefore, when both the water supply valve 35 and the additional valve 37 are opened, water is supplied to the first and second water jackets 71 and 72 at the same time, and when the water supply valve 35 is opened and the additional valve 37 is closed, water is supplied to the first and second water jackets 71 and 72 simultaneously. 1 Water will be supplied only to the water jacket (71).

However, as shown in FIG. 2, if there is no additional valve 37, the water level in the second water pipe 92 is raised purely by the overflow of the first water pipe 91, so the target water level in the second water pipe 92 is not reached. It may take a lot of time.

On the other hand, according to this embodiment, both the water supply valve 35 and the additional valve 37 are opened and water is simultaneously supplied to the first and second water jackets 71 and 72 by the water pump 30, The first water pipe 91 and the second water pipe 92 are quickly filled with water to a predetermined water level L2. Thereafter, by closing the additional valve 37 and supplying water to the first water jacket 71 only through the water supply valve 35, the water level L1 of the first water pipe 91 is further raised. The target water level (e.g. full water level) can be reached.

Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features. You will be able to understand it. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

FL: flame
L1: first level
L2: Second level
10: Economizer
20: Combustion gas discharge path
30: water pump
35: Water valve
37: Additional valve
39: water pipe
40: Water separator
50: air blower
55: air supply path
60: Wet steam chamber
63: Stepped part
65: Upper header plate
70: Water supply chamber
71: First water jacket
72: Second water jacket
73: Bulkhead
75: Lower header plate
80: combustion chamber
85: burner
90: water pipe
91: First water tube (screen tube)
92: Second water pipe
100: Boiler system
200: Boiler body

Claims (7)

A burner that generates a flame by burning the supplied gas;
a plurality of water tubes heated by the burner;
a water pump supplying water to the plurality of water pipes;
a water separator that separates heated steam and water in the plurality of water pipes; and
A boiler system installed on the discharge path of the burned gas and including an economizer that preheats the water supplied into the plurality of water pipes through heat exchange with the combustion gas,
The plurality of water pipes include a first water pipe disposed adjacent to the burner and having a first water level, and a second water pipe disposed in parallel with the first water pipe and having a second water level lower than the first water level,
The lower end of the first water pipe passes through the lower header plate and communicates with the first water jacket, and the lower end of the second water pipe passes through the lower header plate and communicates with a second water jacket isolated from the first water jacket. , the upper end of the first water pipe and the upper end of the second water pipe pass through the upper header plate and are in common communication with the wet steam chamber,
The water pump supplies water to the first water jacket through a water supply valve, and when the supplied water fills the first water pipe and overflows to the top of the first water pipe, the water pump supplies water to the first water jacket through a water supply valve. 2 The water pipe is filled with water at the second water level,
In addition to the water supply valve, an additional valve is further provided to allow or block the supply of water directly to the second water jacket,
By opening both the water supply valve and the additional valve and simultaneously supplying water to the first and second water jackets by the water pump, the first water pipe and the second water pipe are filled with water to a predetermined level, and then the additional water pipe is filled with water. By closing the valve and supplying water to the first water jacket only through the water supply valve, the water level in the first water pipe is further raised,
The direction in which the flame is emitted from the burner and the extension direction of the plurality of water pipes are orthogonal to each other, and in order to lower the temperature of the emitted flame, the emitted flame is at a higher water level than the second water pipe. A boiler system that first contacts the first water pipe with a. According to paragraph 1,
A boiler system, wherein the first water jacket and the second water jacket are formed by separating a single chamber by a partition. According to paragraph 1,
Even if the water overflows and flows into only some of the water pipes of the second water pipes, the second water jacket is filled with water, and the lower end of the second water pipe communicates with the second water jacket. A boiler system wherein the overall water level is maintained equal to the second water level. According to paragraph 1,
In order to maintain the first water level of the first water pipe sufficiently high, a step protruding higher than the upper header plate into the wet steam chamber is formed between the area of the first water pipe and the area of the second water pipe. system. According to paragraph 1,
It further includes a water level sensor that detects the water level of the second water pipe,
When the water overflows from the first water pipe and the water level of the second water pipe rises, and the water level sensor detects that the water level of the second water pipe has reached the target water level, water is supplied by the water pump. Boiler system shut down. delete delete