Water-cooled low-nitrogen premix combustion vacuum hot water boiler

Abstract

The utility model relates to vacuum hot water boiler technical field discloses a water cooling type low nitrogen premixing combustion vacuum hot water boiler, including furnace body, the inner wall fixedly connected with the generating cylinder of furnace body, the outer wall of generating cylinder is provided with mixing mechanism, the outer wall of furnace body is provided with circulating heating mechanism, and the circulating heating mechanism is used for circulating heat exchange, the mixing mechanism includes natural gas intake hopper, the outer wall of natural gas intake hopper is fixedly connected with the left side of furnace body, and the outer wall right side of furnace body is fixedly connected with air intake hopper. In the utility model, natural gas flows in from natural gas intake hopper, air flows in from air intake hopper, and the two mix in mixing chamber, the thread vane stirs and pushes to natural gas and air, and the electric spark of ignition electrode ignites, and the flame is more uniform and stable by fiber net, achieves efficient combustion, makes combustion more thorough, and the phenomenon of easy occurrence of fireout, tempering is not easy.

Description

Technical Field

[0001] This utility model relates to the field of vacuum hot water boiler technology, and in particular to a water-cooled low-NOx premixed combustion vacuum hot water boiler. Background Technology

[0002] Water-cooled low-NOx premixed combustion vacuum hot water boilers are high-efficiency thermal energy devices that combine vacuum heat exchange technology, low-NOx premixed combustion technology, and water-cooled heat exchange structure. Their core definition lies in using a closed vacuum heat exchange chamber as the core, achieving precise fuel-air ratio combustion through a low-NOx premixed burner, and then rapidly absorbing combustion heat with the help of a water-cooling system. This heat is ultimately transferred to the heat transfer medium water within the heat exchange chamber, providing users with a stable hot water supply. Structurally, this type of boiler mainly includes five core modules: first, the vacuum heat exchange chamber; second, the low-NOx premixed combustion system, consisting of a premixer, burner, and ignition device; third, the water-cooled heat exchange system, encompassing the water-cooled walls surrounding the combustion chamber and the water-cooled tube bundles within the chamber, efficiently absorbing combustion heat through forced and natural water circulation; fourth, the control system; and fifth, auxiliary structures such as exhaust pipes, insulation layers, and water replenishment devices, which respectively realize the functions of flue gas emission, heat preservation, and system water replenishment.

[0003] Early water-cooled low-NOx premixed combustion vacuum hot water boilers suffered from insufficient matching between the burner and the water cooling system. Due to the concentrated temperature of the premixed combustion flame, if the distance between the water-cooled wall and the burner was too close, it could easily lead to a sudden rise in local water temperature, causing the heat transfer medium water to vaporize too quickly and disrupting the heat exchange balance within the vacuum chamber. If the distance was too far, the combustion heat could not be fully absorbed, resulting in increased flue gas temperature and decreased thermal efficiency. To address these drawbacks, existing technologies have developed adjustable burner mounting brackets to address the matching problem between the burner and the water-cooled wall. Through the horizontal and vertical displacement adjustment function of the brackets, precise matching between the burner and the water-cooled wall can be achieved. At the same time, a guide hood structure is set at the burner outlet to guide the flame to a diffused distribution, avoiding concentrated flame impact on the water-cooled wall. However, this technology cannot achieve ultra-uniform premixing of natural gas and air, and local gas concentrations may be too high or too low, leading to flameout and backfire phenomena, thus limiting its practicality. Utility Model Content

[0004] To overcome the above shortcomings, this utility model provides a water-cooled low-NOx premixed combustion vacuum hot water boiler, which aims to improve the existing technology's inability to achieve ultra-uniform premixing of natural gas and air, resulting in excessively high or low local gas concentrations, flameout and backfire phenomena, and low practicality.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a water-cooled low-NOx premixed combustion vacuum hot water boiler, comprising a furnace body, a generator cylinder fixedly connected to the inner wall of the furnace body, a mixing mechanism provided on the outer wall of the generator cylinder, and a circulating heating mechanism provided on the outer wall of the furnace body, the circulating heating mechanism being used for circulating heat exchange; The mixing mechanism includes a natural gas inlet hopper, the outer wall of which is fixedly connected to the left side of the furnace body, and an air inlet hopper fixedly connected to the right side of the outer wall of the furnace body. A premixing component is provided at the top of the generating cylinder, a driving component is provided at the top of the furnace body, and a heating component is provided on the inner wall of the generating cylinder.

[0006] As a further description of the above technical solution: The circulating heating mechanism includes a water inlet pipe, the outer wall of which is fixedly connected to the outer wall of the furnace body. A heat exchange coil is fixedly connected to the left side of the water inlet pipe, and a water outlet pipe is fixedly connected to the left side of the heat exchange coil. A circulation component is provided on the right side of the generating cylinder.

[0007] As a further description of the above technical solution: The premixing component includes a furnace cavity, the bottom of the outer wall of the furnace cavity is fixedly connected to the top of the outer wall of the generator cylinder, and a mixing chamber is fixedly connected to the top of the furnace cavity.

[0008] As a further description of the above technical solution: The drive assembly includes a protective shell, the bottom of which is fixedly connected to the top of the furnace body, and a stepper motor is fixedly connected to the top of the inner wall of the protective shell. A mixing component is provided at the output end of the stepper motor.

[0009] As a further description of the above technical solution: The mixing component includes a long shaft, the outer wall of which is fixedly connected to the output end of a stepper motor, and a threaded blade is fixedly connected to the outer wall of the long shaft. A diverter component is provided on the lower side of the outer wall of the long shaft.

[0010] As a further description of the above technical solution: The diversion assembly includes a connecting shaft, the outer wall of which is fixedly connected to the outer wall of the long shaft, and perforated diversion plates are fixedly connected to both the left and right sides of the connecting shaft.

[0011] As a further description of the above technical solution: The heating assembly includes an isolation plate, the outer wall of which is fixedly connected to the generating cylinder, a fiber mesh is fixedly connected to the inner wall of the generating cylinder, and an ignition electrode is fixedly connected to the top of the isolation plate.

[0012] As a further description of the above technical solution: The circulation assembly includes a first connecting pipe, the left side of which is fixedly connected to the right side of the outer wall of the generator cylinder, a circulation pump is fixedly connected to the right side of the first connecting pipe, and a second connecting pipe is connected to the top of the circulation pump.

[0013] This utility model has the following beneficial effects: 1. In this utility model, natural gas flows in through the natural gas inlet hopper and air flows in through the air inlet hopper. The two are mixed in the mixing chamber of the premixing component. After the stepper motor in the drive component is started, it drives the threaded blades to rotate. The threaded blades stir and push the natural gas and air, making the two more thoroughly mixed. The porous diverter plate divides the mixed gas into multiple fine streams, further improving the uniformity of the mixture. The uniformly mixed gas enters the furnace chamber, and the ignition electrode of the heating component generates an electric spark to ignite the mixed gas. At the same time, the isolation plate plays the role of separating and stabilizing the combustion zone, and the fiber mesh can make the flame more uniform and stable, achieving efficient combustion and realizing ultra-uniform premixing of natural gas and air. This prevents the local gas concentration from being too high or too low, making the combustion more complete and less prone to flameout and backfire, thus improving practicality.

[0014] 2. In this invention, combustion within the furnace cavity generates a large amount of heat. The outer wall of the furnace cavity is in direct contact with the heat transfer water inside the generator cylinder. The heat transfer water absorbs the heat conducted by the furnace cavity, causing its temperature to rise. A circulation pump draws in the heated heat transfer water via connecting pipe one, and the water circulates and is heated again via connecting pipe two, ensuring uniform heating of the heat transfer water inside the generator cylinder. The heat transfer water flows around the heat exchange coil, while cold water flows into the heat exchange coil through the inlet pipe. After the heat transfer water transfers heat to the cold water in the heat exchange coil, its temperature drops, and it flows back to the lower side of the furnace inner wall to continue absorbing heat from the furnace cavity, thus forming a circulation of the heat transfer water. The cold water absorbs heat from the heat transfer water in the heat exchange coil, causing its temperature to rise and turning into hot water. Finally, it is delivered to the user end through the outlet pipe, achieving efficient heating and continuous circulation of cold water. This ensures a stable and continuous supply of hot water, meeting the demand for continuous hot water use. Attached Figure Description

[0015] Figure 1 A perspective view of the front side of the furnace body of a water-cooled low-NOx premixed combustion vacuum hot water boiler proposed in this utility model; Figure 2 This is a partial structural breakdown diagram of the generator cylinder of a water-cooled low-NOx premixed combustion vacuum hot water boiler proposed in this utility model; Figure 3 This is a partial structural diagram of the long axis of a water-cooled low-NOx premixed combustion vacuum hot water boiler proposed in this utility model. Figure 4 This is a partial structural diagram of the isolation plate of a water-cooled low-NOx premixed combustion vacuum hot water boiler proposed in this utility model; Figure 5 This is a partial structural diagram of the inlet pipe of a water-cooled, low-NOx premixed combustion vacuum hot water boiler proposed in this utility model.

[0016] Legend: 1. Furnace body; 2. Mixing mechanism; 201. Natural gas inlet hopper; 202. Air inlet hopper; 203. Premixing component; 2031. Mixing chamber; 2032. Furnace cavity; 204. Drive component; 2041. Protective shell; 2042. Stepper motor; 205. Mixing component; 2051. Long shaft; 2052. Threaded blade; 206. Diverter component; 2061. Connecting shaft; 2062. Perforated diverter plate; 207. Heating component; 2071. Isolation plate; 2072. Fiber mesh; 2073. Ignition electrode; 3. Circulating heating mechanism; 301. Water inlet pipe; 302. Heat exchange coil; 303. Water outlet pipe; 304. Circulation component; 3041. Connecting pipe one; 3042. Circulation pump; 3043. Connecting pipe two; 4. Generator cylinder. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] Please see the appendix Figure 1 - Appendix Figure 3 An embodiment of this utility model is provided: a water-cooled low-NOx premixed combustion vacuum hot water boiler, including a furnace body 1, a generator cylinder 4 fixedly connected to the inner wall of the furnace body 1, a mixing mechanism 2 provided on the outer wall of the generator cylinder 4, the mixing mechanism 2 being used to fully mix natural gas and air in proportion to provide a uniform combustible mixture for low-NOx combustion, and a circulating heating mechanism 3 provided on the outer wall of the furnace body 1, the circulating heating mechanism 3 being used for circulating heat exchange; The mixing mechanism 2 includes a natural gas inlet hopper 201, the outer wall of which is fixedly connected to the left side of the furnace body 1. An air inlet hopper 202 is fixedly connected to the right side of the outer wall of the furnace body 1. The air inlet hopper 202 is used to introduce combustion air and cooperates with the natural gas inlet hopper 201 to achieve the initial separation and introduction of gas and air. A premixing component 203 is provided at the top of the generator cylinder 4, a driving component 204 is provided at the top of the furnace body 1, and a heating component 207 is provided on the inner wall of the generator cylinder 4. The heating component 207 is used to ignite the mixed combustible gas and maintain stable combustion. Specifically, the boiler includes a furnace body 1, which serves as the main supporting structure for the entire boiler, providing an installation carrier and protective shell for the internal components while maintaining the overall structural stability of the boiler. A generator cylinder 4 is fixedly connected to the inner wall of the furnace body 1, providing storage and circulation space for the heat transfer medium water. Its outer wall can contact the combustion components to achieve heat transfer, making it the core transfer area for heat exchange. A circulating heating mechanism 3 is installed on the outer wall of the furnace body 1, used for circulating heat exchange, achieving cold water heating and hot water output through medium circulation. The mixing mechanism 2 includes a natural gas inlet hopper 201, which serves as the input channel for natural gas. Its outer wall is fixedly connected to the left side of the furnace body 1, ensuring stable natural gas introduction and preventing leakage. A premixing component 203 is installed at the top of the generator cylinder 4, forming the core area for thorough mixing of gas and air. A drive component 204 is installed at the top of the furnace body 1, providing power for the mixing process and ensuring mixing efficiency.

[0019] Please see the appendix Figure 3 - Appendix Figure 5 The circulating heating mechanism 3 includes a water inlet pipe 301, the outer wall of which is fixedly connected to the outer wall of the furnace body 1. A heat exchange coil 302 is fixedly connected to the left side of the water inlet pipe 301, and a water outlet pipe 303 is fixedly connected to the left side of the heat exchange coil 302. The water outlet pipe 303 is used to export the heated hot water and deliver it to the user's heating end. A circulation component 304 is provided on the right side of the generating cylinder 4. The circulation component 304 is used to drive the circulation of the heat medium water to ensure uniform heat transfer. The circulation component 304 includes a first connecting pipe 3041, the left side of which is fixedly connected to the right side of the outer wall of the generating cylinder 4. A circulation pump 3042 is fixedly connected to the right side of the first connecting pipe 3041. A second connecting pipe 3043 is connected to the top of the circulation pump 3042. The second connecting pipe 3043 is used to guide the heat medium water output by the circulation pump 3042 back to the generating cylinder 4 and the heat exchange area to form a closed loop of heat medium water circulation. Specifically, the circulating heating mechanism 3 includes a water inlet pipe 301, which serves as the input channel for cold water. Its outer wall is fixedly connected to the outer wall of the furnace body 1, allowing stable access to an external cold water source and guiding the cold water into the heat exchange area. A heat exchange coil 302 is fixedly connected to the left side of the water inlet pipe 301. The heat exchange coil 302 adopts a multi-turn winding or multi-pipe parallel structure, which greatly increases the contact area between the cold water and the heat transfer medium water, and is the core component for heat exchange. The circulation component 304 includes a connecting pipe 3041, which is fixedly connected to the right side of the outer wall of the generating cylinder 4 on the left side. It serves as the extraction channel for the heat transfer medium water, allowing the high-temperature heat transfer medium water after heat absorption to be extracted from the generating cylinder 4. A circulation pump 3042 is fixedly connected to the right side of the connecting pipe 3041. The circulation pump 3042 is the power source for the circulation of the heat transfer medium water. The operation of the pump provides pressure for the flow of the heat transfer medium water, ensuring circulation efficiency.

[0020] Please see the appendix Figure 2 - Appendix Figure 4 The premixing component 203 includes a furnace cavity 2032, the bottom of the outer wall of the furnace cavity 2032 is fixedly connected to the top of the outer wall of the generator cylinder 4, and a mixing chamber 2031 is fixedly connected to the top of the furnace cavity 2032. The heating component 207 includes an isolation plate 2071, which is used to separate the combustion zone from the heat transfer medium water zone to prevent the flame from directly contacting the heat transfer medium water and causing local overheating, and at the same time plays a role in stabilizing the combustion space. The outer wall of the isolation plate 2071 is fixedly connected to the generator cylinder 4, and a fiber mesh 2072 is fixedly connected to the inner wall of the generator cylinder 4. An ignition electrode 2073 is fixedly connected to the top of the isolation plate 2071. Specifically, the premixing component 203 includes a furnace chamber 2032, which is a closed space for the combustion of combustible gas. The bottom of its outer wall is fixedly connected to the top of the outer wall of the generator cylinder 4, which can quickly transfer the heat generated by combustion to the heat transfer medium water in the generator cylinder 4. A mixing chamber 2031 is fixedly connected to the top of the furnace chamber 2032. The mixing chamber 2031 provides a sealed space for the mixing of gas and air, preventing leakage of the mixed gas. At the same time, it works with the mixing component 205 to achieve full stirring. The heating component 207 includes an isolation plate 2071. A fiber mesh 2072 is fixedly connected to the inner wall of the generator cylinder 4. The fiber mesh 2072 is made of high-temperature resistant metal material, which can disperse the flame into a uniform surface combustion, reduce the flame center temperature, reduce the generation of nitrogen oxides, and prevent backfire. An ignition electrode 2073 is fixedly connected to the top of the isolation plate 2071. The ignition electrode 2073 generates an electric spark through high-voltage discharge, which is used to ignite the premixed gas introduced into the mixing chamber 2031 and is the combustion starting component.

[0021] Please see the appendix Figure 2 - Appendix Figure 4The drive assembly 204 includes a protective shell 2041, the bottom of which is fixedly connected to the top of the furnace body 1. A stepper motor 2042 is fixedly connected to the top of the inner wall of the protective shell 2041. A mixing assembly 205 is provided at the output end of the stepper motor 2042. The mixing assembly 205 is used to mechanically stir the gas and air to improve the mixing uniformity. The mixing assembly 205 includes a long shaft 2051, the outer wall of which is fixedly connected to the output end of the stepper motor 2042. A threaded blade 2052 is fixedly connected to the outer wall of the long shaft 2051. The threaded blade 2052 is spiral. The gas is distributed in a circular pattern and can be stirred and pushed in the mixing chamber 2031 when rotated, so as to achieve full mixing and guide the mixed gas to flow into the furnace chamber 2032. A flow-dividing component 206 is provided on the lower side of the outer wall of the long shaft 2051. The flow-dividing component 206 includes a connecting shaft 2061. The outer wall of the connecting shaft 2061 is fixedly connected to the outer wall of the long shaft 2051. A porous flow-dividing plate 2062 is fixedly connected to both the left and right sides of the connecting shaft 2061. The porous flow-dividing plate 2062 has uniformly distributed micro-holes. When rotated, it can divide the mixed gas into multiple fine streams, break the gas stratification, and ensure that the fuel gas and air are fully in contact at the micro level. Specifically, the drive assembly 204 includes a protective shell 2041, the bottom of which is fixedly connected to the top of the furnace body 1. The protective shell 2041 is made of a high-temperature resistant and corrosion-resistant material to protect the internal motor components from the high temperature and dust of the boiler. A stepper motor 2042 is fixedly connected to the top of the inner wall of the protective shell 2041. The stepper motor 2042 can precisely control the rotation speed, providing stable and adjustable power to the mixing assembly 205 to adapt to the mixing requirements under different combustion loads. The mixing assembly 205 includes a long shaft 2051, the outer wall of which is connected to the stepper motor 2041. The output end of 2 is fixedly connected and serves as a power transmission shaft, which can transmit the torque of the stepper motor 2042 to the stirring component. A flow divider 206 is provided on the lower side of the outer wall of the long shaft 2051. The flow divider 206 is used to perform secondary division of the initially mixed gas to further improve the uniformity. The flow divider 206 includes a connecting shaft 2061, the outer wall of which is fixedly connected to the outer wall of the long shaft 2051. It serves as the mounting carrier for the porous flow divider plate 2062 and rotates synchronously with the long shaft 2051. The model of the stepper motor 2042 is 42BYGH4818.

[0022] Working principle: Natural gas enters through the natural gas inlet hopper 201, and air enters through the air inlet hopper 202. The two gases are mixed in the mixing chamber 2031 of the premixing component 203. The stepper motor 2042 in the drive component 204 starts, driving the threaded blades 2052 to rotate. The threaded blades 2052 stir and push the natural gas and air to ensure thorough mixing. The porous diverter plate 2062 divides the mixed gas into multiple fine streams, further improving the mixing uniformity. The uniformly mixed gas enters the furnace chamber 2032. The ignition electrode 2073 of the heating component 207 generates an electric spark to ignite the mixed gas. At the same time, the isolation plate 2071 separates and stabilizes the combustion zone, and the fiber mesh 2072 makes the flame more uniform and stable, achieving efficient combustion. It achieves ultra-uniform premixing of natural gas and air, avoiding excessively high or low local gas concentrations, making combustion more complete, and reducing the likelihood of flameout or backfire, thus enhancing practicality. Combustion within the furnace cavity 2032 generates a large amount of heat. The outer wall of the furnace cavity 2032 is in direct contact with the heat transfer water inside the generator cylinder 4. The heat transfer water absorbs the heat transferred from the furnace cavity 2032, causing its temperature to rise. The circulating pump 3042 absorbs the heated heat transfer water through connecting pipe 1 3041. The heat transfer water is then circulated and heated through connecting pipe 2 3043, ensuring uniform heating of the heat transfer water within the generator cylinder 4. The heat transfer water flows around the heat exchange coil 302, while cold water enters the heat exchange coil 302 through the inlet pipe 301. The heat transfer water transfers heat... After the cold water is transferred to the heat exchange coil 302 and completes the heat exchange, the temperature of the hot water decreases and flows back to the lower side of the inner wall of the furnace body 1 to continue absorbing heat from the furnace cavity 2032, forming a circulation of the hot water. The cold water absorbs heat from the hot water in the heat exchange coil 302 and its temperature rises, becoming hot water. Finally, it is transported to the user end through the outlet pipe 303 to achieve a continuous supply of hot water. This achieves efficient heating and continuous circulation of cold water, providing a stable and continuous supply of hot water to meet continuous heating needs.

[0023] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A water-cooled low-nitrogen premix combustion vacuum hot water boiler comprising a furnace body (1), characterized in that: The inner wall of the furnace body (1) is fixedly connected to a generating cylinder (4), the outer wall of the generating cylinder (4) is provided with a mixing mechanism (2), and the outer wall of the furnace body (1) is provided with a circulating heating mechanism (3), which is used for circulating heat exchange. The mixing mechanism (2) includes a natural gas inlet hopper (201), the outer wall of which is fixedly connected to the left side of the furnace body (1), an air inlet hopper (202) is fixedly connected to the right side of the outer wall of the furnace body (1), a premixing component (203) is provided on the top of the generator cylinder (4), a driving component (204) is provided on the top of the furnace body (1), and a heating component (207) is provided on the inner wall of the generator cylinder (4).

2. The water-cooled low-nitrogen premix combustion vacuum hot water boiler according to claim 1, characterized in that: The circulating heating mechanism (3) includes a water inlet pipe (301), the outer wall of which is fixedly connected to the outer wall of the furnace body (1), a heat exchange coil (302) is fixedly connected to the left side of the water inlet pipe (301), a water outlet pipe (303) is fixedly connected to the left side of the heat exchange coil (302), and a circulation component (304) is provided on the right side of the generating cylinder (4).

3. The water-cooled low-nitrogen premix combustion vacuum hot water boiler according to claim 1, characterized in that: The premixing component (203) includes a furnace cavity (2032), the bottom of the outer wall of the furnace cavity (2032) is fixedly connected to the top of the outer wall of the generator cylinder (4), and a mixing chamber (2031) is fixedly connected to the top of the furnace cavity (2032).

4. The water-cooled low-nitrogen premix combustion vacuum hot water boiler according to claim 1, characterized in that: The drive assembly (204) includes a protective shell (2041), the bottom of which is fixedly connected to the top of the furnace body (1), and a stepper motor (2042) is fixedly connected to the top of the inner wall of the protective shell (2041). A mixing assembly (205) is provided at the output end of the stepper motor (2042).

5. A water-cooled low-NOx premixed combustion vacuum hot water boiler according to claim 4, characterized in that: The mixing component (205) includes a long shaft (2051), the outer wall of which is fixedly connected to the output end of a stepper motor (2042), and a threaded blade (2052) is fixedly connected to the outer wall of the long shaft (2051). A diverter component (206) is provided on the lower side of the outer wall of the long shaft (2051).

6. The water-cooled low-nitrogen premix combustion vacuum hot water boiler according to claim 5, characterized in that: The diversion assembly (206) includes a connecting shaft (2061), the outer wall of the connecting shaft (2061) is fixedly connected to the outer wall of the long shaft (2051), and a perforated diversion plate (2062) is fixedly connected to both the left and right sides of the connecting shaft (2061).

7. The water-cooled low-nitrogen premix combustion vacuum hot water boiler according to claim 1, characterized in that: The heating assembly (207) includes an isolation plate (2071), the outer wall of which is fixedly connected to the generating cylinder (4), the inner wall of which is fixedly connected to a fiber mesh (2072), and the top of which is fixedly connected to an ignition electrode (2073).

8. The water-cooled low-nitrogen premix combustion vacuum hot water boiler according to claim 2, characterized in that: The circulation assembly (304) includes a first connecting pipe (3041), the left side of which is fixedly connected to the right side of the outer wall of the generator cylinder (4), and a circulation pump (3042) is fixedly connected to the right side of the first connecting pipe (3041), and a second connecting pipe (3043) is connected to the top of the circulation pump (3042).

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