Gas-fired boiler

Abstract

The present application is a kind of gas boiler, which comprises a burner, a main heat exchanger and an auxiliary heat exchanger. The flue gas generated after the combustible gas is ignited flows through the main heat exchanger and the auxiliary heat exchanger in sequence, and exchanges heat through the main heat exchanger and the auxiliary heat exchanger. The auxiliary heat exchanger has at least a first liquid inlet and a first liquid outlet, and the main heat exchanger has at least a second liquid inlet and a second liquid outlet. The first liquid inlet is connected to the second liquid inlet, and the first liquid outlet is connected to the second liquid outlet. When the gas boiler is running, the flow of the liquid in the auxiliary heat exchanger is less than that in the main heat exchanger. The present application can reduce the volume while meeting the large flow of the gas boiler, and the auxiliary heat exchanger has a suitable heat exchange capacity, which improves the thermal efficiency.

Description

Technical Field

[0001] This invention relates to the field of gas equipment, and more particularly to a gas boiler. Background Technology

[0002] With the continuous increase in natural gas prices, the operating costs of commercial heating and hot water are gradually rising, leading more and more users to choose condensing boilers to reduce operating expenses. Currently, the condenser and main heat exchanger in condensing boilers are connected in series, with all liquids entering the main heat exchanger and condenser sequentially. To accommodate the large flow of liquid, both the condenser and main heat exchanger need to have a large flow area, resulting in a larger size and increased cost for the condensing boiler. In addition, because the flue gas temperature entering the condenser after heat exchange in the main heat exchanger is generally lower, the condenser may have a heat exchange surplus, resulting in lower heat exchange efficiency.

[0003] Therefore, based on years of experience and practice in related industries, the inventor proposes a gas-fired boiler to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a gas-fired boiler that can reduce its size while meeting the requirements of large flow rate, and whose auxiliary heat exchanger has a suitable heat exchange capacity, thereby improving thermal efficiency.

[0005] The objective of this invention can be achieved through the following methods:

[0006] This invention provides a gas-fired boiler, comprising a burner, a main heat exchanger, and an auxiliary heat exchanger. The flue gas generated after the burner ignites combustible gas flows sequentially through the main heat exchanger and the auxiliary heat exchanger, and undergoes heat exchange through them.

[0007] The auxiliary heat exchanger has at least a first liquid inlet and a first liquid outlet, and the main heat exchanger has at least a second liquid inlet and a second liquid outlet. The first liquid inlet is connected to the second liquid inlet, and the first liquid outlet is connected to the second liquid outlet.

[0008] When the gas-fired boiler is running, the flow rate of the liquid in the auxiliary heat exchanger is less than the flow rate of the liquid in the main heat exchanger.

[0009] In a preferred embodiment of the present invention, the flow area available for liquid flow in the auxiliary heat exchanger is smaller than the flow area available for liquid flow in the main heat exchanger, and / or, the resistance coefficient of the auxiliary heat exchanger is greater than the resistance coefficient of the main heat exchanger.

[0010] In a preferred embodiment of the present invention, the ratio of the flow rate of the liquid in the auxiliary heat exchanger to the flow rate of the liquid in the main heat exchanger is not greater than 1:4 and / or not less than 1:6.

[0011] In a preferred embodiment of the present invention, the gas-fired boiler includes at least a boiler inlet pipe and a boiler outlet pipe. The liquid entering through the boiler inlet pipe flows into the auxiliary heat exchanger and the main heat exchanger through the first inlet and the second inlet, respectively. The liquid after exchanging heat with the flue gas flows into the boiler outlet pipe through the first outlet and the second outlet, respectively.

[0012] In a preferred embodiment of the present invention, the auxiliary heat exchanger includes a first inlet pipe having a first liquid inlet and a first outlet pipe having a first liquid outlet, and the main heat exchanger includes a second inlet pipe connected to the second liquid inlet and a second outlet pipe connected to the second liquid outlet. The first inlet pipe is connected to the second inlet pipe, and both the first inlet pipe and the second inlet pipe are connected to the boiler liquid inlet pipeline. The first outlet pipe is connected to the second outlet pipe, and both the first outlet pipe and the second outlet pipe are connected to the boiler liquid outlet pipeline.

[0013] In a preferred embodiment of the present invention, the auxiliary heat exchanger further includes a third liquid inlet and a third liquid outlet. The third liquid inlet is disposed on the first liquid inlet pipe, and the third liquid outlet is disposed on the first liquid outlet pipe. The third liquid inlet and the third liquid outlet are respectively used to connect to the indoor terminal liquid outlet pipe. Along the flow direction of the liquid in the indoor terminal liquid outlet pipe, the connection position between the third liquid inlet and the indoor terminal liquid outlet pipe is located upstream of the connection position between the third liquid outlet and the indoor terminal liquid outlet pipe.

[0014] In a preferred embodiment of the present invention, a first valve is provided on the first liquid inlet pipe, and the first valve is used to control the connection and disconnection between the first liquid inlet pipe and the boiler liquid inlet pipe.

[0015] And / or, a second valve is provided on the first liquid outlet pipe, the second valve being used to control the connection and disconnection between the first liquid outlet pipe and the boiler liquid outlet pipe.

[0016] In a preferred embodiment of the present invention, the boiler inlet pipe and the boiler outlet pipe are respectively connected to the first outlet and the first inlet of the external heat exchanger, and the second inlet and the second outlet of the external heat exchanger are respectively connected to the indoor end outlet pipe and the indoor end inlet pipe.

[0017] In a preferred embodiment of the present invention, the first inlet pipe and / or the first outlet pipe and / or the second inlet pipe and / or the second outlet pipe are provided with a flow sensor and / or a temperature sensor.

[0018] In a preferred embodiment of the present invention, the auxiliary heat exchanger includes at least a first heat exchange section and a second heat exchange section, and the liquid flowing into the auxiliary heat exchanger is diverted to the first heat exchange section and the second heat exchange section, wherein the liquid flow path between the first heat exchange section and the second heat exchange section is connected in parallel.

[0019] In a preferred embodiment of the present invention, the first heat exchange section includes a plurality of first heat exchange tube groups, and the liquid flow paths of the plurality of first heat exchange tube groups are connected in series.

[0020] The second heat exchange section includes a plurality of second heat exchange tube groups, and the liquid flow paths of the plurality of second heat exchange tube groups are connected in series.

[0021] In a preferred embodiment of the present invention, the first heat exchange tube group includes a plurality of first heat exchange tubes, and the liquid flow paths between the plurality of first heat exchange tubes are connected in parallel.

[0022] The second heat exchange tube group includes multiple second heat exchange tubes, and the liquid flow paths of the multiple second heat exchange tubes are connected in parallel.

[0023] In a preferred embodiment of the present invention, a plurality of first heat exchange tube groups are connected to each other through a first connecting portion, and a plurality of second heat exchange tube groups are connected to each other through a second connecting portion.

[0024] In a preferred embodiment of the present invention, along the flow direction of the liquid, the number of the first heat exchange tubes in the first heat exchange tube group located upstream of the first connecting portion is less than the number of the first heat exchange tubes in the first heat exchange tube group located downstream of the first connecting portion.

[0025] And / or, along the direction of liquid flow, the number of second heat exchange tubes in the second heat exchange tube group located upstream of the second connecting portion is less than the number of second heat exchange tubes in the second heat exchange tube group located downstream of the second connecting portion.

[0026] In a preferred embodiment of the present invention, both the first heat exchange tube and the second heat exchange tube are heat exchange coils. The first heat exchange tube and / or the second heat exchange tube include at least two layers of staggered coiled structures. Multiple first heat exchange tubes are staggered to form a first heat exchange tube group, and multiple second heat exchange tubes are staggered to form a second heat exchange tube group.

[0027] In a preferred embodiment of the present invention, both the first heat exchange tube and the second heat exchange tube are heat exchange coils, and multiple first heat exchange tubes are arranged in parallel to form a hollow first cavity; multiple second heat exchange tubes are arranged in parallel to form a hollow second cavity.

[0028] In a preferred embodiment of the present invention, the auxiliary heat exchanger includes a housing, the first heat exchange section and the second heat exchange section are disposed within the housing, and the housing has at least a flue gas inlet communicating with the first cavity and a flue gas outlet communicating with the second cavity;

[0029] The first heat exchange section and the second heat exchange section respectively form a first cavity and a second cavity. The flue gas entering the shell through the flue gas inlet passes through the first cavity and the second cavity in sequence. A first baffle is provided inside the shell and on the side close to the flue gas inlet. A first flue gas gap is formed between the edge of the first baffle and the inner wall of the shell.

[0030] A second baffle and / or a third baffle are provided between the first cavity and the second cavity. The edge of the second baffle and / or the edge of the third baffle are respectively connected to the inner wall of the shell, and the second baffle and / or the third baffle have a flue gas passage connecting the first cavity and the second cavity.

[0031] A fourth baffle is provided inside the housing and on the side near the flue gas outlet, and a second flue gas gap is formed between the edge of the fourth baffle and the inner wall of the housing.

[0032] In a preferred embodiment of the present invention, the flue gas inlet and the flue gas outlet are respectively located on opposite side walls of the housing.

[0033] In a preferred embodiment of the present invention, the first baffle is provided with at least one through hole for the flue gas to pass through.

[0034] In a preferred embodiment of the present invention, the through hole is located near the edge of the first baffle.

[0035] In a preferred embodiment of the present invention, the gas boiler further includes a fan, the outlet of which is connected to the inlet of the burner, and the fan is used to mix air and gas in a preset ratio and then send them into the burner.

[0036] In a preferred embodiment of the present invention, the gas boiler further includes a main body shell, the fan, the burner, the main heat exchanger and the auxiliary heat exchanger are all located inside the main body shell, and the main body shell is provided with an air inlet;

[0037] The air inlet of the fan is connected to the air inlet pipe and the gas inlet pipe, respectively.

[0038] In a preferred embodiment of the present invention, the main heat exchanger is arranged vertically, the burner is located inside the main heat exchanger, the auxiliary heat exchanger is arranged horizontally, the flue gas outlet of the main heat exchanger is located on the side of the shell of the main heat exchanger, and the flue gas inlet of the auxiliary heat exchanger is located on the side of the shell of the auxiliary heat exchanger.

[0039] In a preferred embodiment of the present invention, the maximum liquid flow rate of the gas-fired boiler is not less than 100 m³ / h. 3 / h.

[0040] As described above, the features and advantages of the gas-fired boiler of the present invention are:

[0041] This invention employs a parallel connection between a main heat exchanger and an auxiliary heat exchanger. The first liquid inlet of the auxiliary heat exchanger is connected to the second liquid inlet of the main heat exchanger, and the first liquid outlet of the auxiliary heat exchanger is connected to the second liquid outlet of the main heat exchanger. When the gas-fired boiler is running, liquid flows through both the auxiliary and main heat exchangers simultaneously, thereby increasing the liquid flow rate during boiler operation. During this process, the flue gas generated after the burner ignites the combustible gas flows sequentially through the main and auxiliary heat exchangers. The main and auxiliary heat exchangers exchange heat with the flowing liquid and flue gas, thereby improving the working efficiency of the gas-fired boiler. The operating cost of the gas-fired boiler in this invention is significantly lower than that of a gas-fired boiler of the same power, making it suitable for widespread use.

[0042] This invention employs a parallel connection of the main heat exchanger and the auxiliary heat exchanger. Compared to a series connection, where both the main and auxiliary heat exchangers require large flow areas to accommodate large liquid flows, resulting in a larger condensing boiler, increased cost, and lower thermal efficiency of the auxiliary heat exchanger, this invention diverts the liquid to both the main and auxiliary heat exchangers during boiler operation. The flow rate of the liquid in the auxiliary heat exchanger is less than that in the main heat exchanger, thus reducing the volume of the auxiliary heat exchanger. This achieves a more rational layout of the main and auxiliary heat exchangers and reduces the overall size of the boiler. Furthermore, the flue gas pre-exchanges heat with the liquid in the main heat exchanger. When the flue gas flows through the auxiliary heat exchanger, the residual heat is relatively low, requiring only a smaller flow rate in the auxiliary heat exchanger to achieve sufficient heat exchange. Therefore, setting the flow rate of the liquid in the auxiliary heat exchanger to be less than that in the main heat exchanger ensures that the auxiliary heat exchanger has appropriate heat exchange capacity, preventing excess heat and improving heat exchange efficiency. Attached Figure Description

[0043] The accompanying drawings are intended only to illustrate and explain the present invention and do not limit the scope of the invention.

[0044] in:

[0045] Figure 1 : This is a schematic diagram of the structure of a gas-fired boiler in one embodiment of the present invention.

[0046] Figure 2 : This is one of the connection structure block diagrams of a gas-fired boiler in one embodiment of the present invention.

[0047] Figure 3 This is a second block diagram of the connection structure of a gas-fired boiler in one embodiment of the present invention.

[0048] Figure 4 : This is a front view of an auxiliary heat exchanger in one embodiment of the present invention.

[0049] Figure 5 : This is a front cross-sectional view of the auxiliary heat exchanger in one embodiment of the present invention.

[0050] Figure 6 : This is a schematic diagram of the structure of the first heat exchanger and the second heat exchanger in one embodiment of the present invention.

[0051] Figure 7 : This is a cross-sectional view of the location of the heat exchange coil inside the auxiliary heat exchanger in one embodiment of the present invention.

[0052] Figure 8 : This is a perspective view of a two-layer coiled structure in a heat exchanger coil according to an embodiment of the present invention.

[0053] Figure 9 : This is a front cross-sectional view of the two-layer coiled structure in a heat exchanger coil according to an embodiment of the present invention.

[0054] Figure 10 : This is a cross-sectional view of the location of the first baffle inside the housing in one embodiment of the present invention.

[0055] Figure 11 : This is a cross-sectional view of the location of the second baffle inside the housing in one embodiment of the present invention.

[0056] Figure 12 : This is a cross-sectional view of the location of the third baffle inside the housing in one embodiment of the present invention.

[0057] Figure 13 : This is a cross-sectional view of the location of the fourth baffle inside the housing in one embodiment of the present invention.

[0058] Figure 14 This is a schematic diagram of the flow path of flue gas in the auxiliary heat exchanger in one embodiment of the present invention.

[0059] The reference numerals in the accompanying drawings of this invention are:

[0060] 1. Burner; 2. Main heat exchanger; 201. Second liquid inlet; 202. Second liquid outlet; 203. Second liquid inlet pipe; 204. Second liquid outlet pipe; 3. Auxiliary heat exchanger; 301. First liquid inlet; 302. First liquid outlet; 303. First liquid inlet pipe; 304. First liquid outlet pipe; 305. Third liquid inlet; 306. Third liquid outlet; 307. Shell; 310. First heat exchange section; 311. First heat exchange tube assembly; 3111. First heat exchange tube; 3112. First cavity; 320. Second heat exchange section; 321. Second heat exchange tube assembly; 3211. Second heat exchange tube; 3212. Second cavity; 3311. Heat exchange plate Pipe; 340, First baffle; 3401, Through hole; 350, Second baffle; 360, Third baffle; 370, Fourth baffle; 380, First flue gas gap; 390, Second flue gas gap; 4, Boiler liquid inlet pipe; 5, Boiler liquid outlet pipe; 6, Indoor end liquid outlet pipe; 7, Indoor end liquid inlet pipe; 8, First valve; 9, Second valve; 10, Third liquid inlet pipe; 11, Third liquid outlet pipe; 12, Third valve; 13, Fourth valve; 14, External heat exchanger; 15, Fan; 16, Main body shell; 1601, Air inlet; 17, Air inlet pipe; 18, Gas inlet pipe; 19, Flue gas inlet; 20, Flue gas outlet. Detailed Implementation

[0061] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0062] like Figures 1 to 14 As shown, the present invention provides a gas-fired boiler, which includes a burner 1, a main heat exchanger 2, and an auxiliary heat exchanger 3. During operation, the flue gas generated after the burner ignites the combustible gas flows sequentially through the main heat exchanger 2 and the auxiliary heat exchanger 3, and exchanges heat with the liquid in the main heat exchanger 2 and the liquid in the auxiliary heat exchanger 3 in sequence. The auxiliary heat exchanger 3 has at least a first liquid inlet 301 and a first liquid outlet 302, and the main heat exchanger 2 has at least a second liquid inlet 201 and a second liquid outlet 202. The first liquid inlet 301 is connected to the second liquid inlet 201, and the first liquid outlet 302 is connected to the second liquid outlet 202. When the gas-fired boiler is running, the flow rate of the liquid in the auxiliary heat exchanger 3 is less than the flow rate of the liquid in the main heat exchanger 2.

[0063] The first liquid inlet 301 and the second liquid inlet 201, and the first liquid outlet 302 and the second liquid outlet 202 can be directly connected, or the two interfaces can be connected through corresponding pipelines to achieve the connection between the two interfaces. Therefore, in this invention, it is sufficient to realize the parallel connection of the main heat exchanger 2 and the auxiliary heat exchanger 3, and the specific connection structure between the interfaces is not limited.

[0064] This invention employs a parallel connection between the main heat exchanger 2 and the auxiliary heat exchanger 3. The first liquid inlet 301 of the auxiliary heat exchanger 3 is connected to the second liquid inlet 201 of the main heat exchanger 2, and the first liquid outlet 302 of the auxiliary heat exchanger 3 is connected to the second liquid outlet 202 of the main heat exchanger 2. When the gas-fired boiler is running, liquid flows through both the auxiliary heat exchanger 3 and the main heat exchanger 2 simultaneously, thereby increasing the liquid flow rate during boiler operation. During this process, the flue gas generated after the burner 1 ignites the combustible gas flows sequentially through the main heat exchanger 2 and the auxiliary heat exchanger 3. The main heat exchanger 2 and the auxiliary heat exchanger 3 exchange heat between the flowing liquid and the flue gas, thereby improving the working efficiency of the gas-fired boiler. The operating cost of the gas-fired boiler in this invention is much lower than that of a gas-fired boiler of the same power, making it suitable for widespread use.

[0065] This invention employs a parallel connection between the main heat exchanger 2 and the auxiliary heat exchanger 3. Compared to a series connection, where both the main heat exchanger 2 and the auxiliary heat exchanger 3 require larger flow areas to accommodate large flow rates of liquid, resulting in larger size, increased cost, and lower thermal efficiency of the auxiliary heat exchanger 3, this invention connects the first inlet 301 of the auxiliary heat exchanger 3 to the second inlet 201 of the main heat exchanger 2 during boiler operation, and connects the first outlet 302 of the auxiliary heat exchanger 3 to the second outlet 202 of the main heat exchanger 2. When the gas boiler is running, all liquid flowing into the boiler is diverted to the auxiliary heat exchanger 3 and the auxiliary heat exchanger 3. In the main heat exchanger 2, the flow rate of the liquid in the auxiliary heat exchanger 3 can be less than that in the main heat exchanger 2, thereby reducing the volume of the auxiliary heat exchanger 3. This achieves the goal of rationally arranging the main heat exchanger 2 and the auxiliary heat exchanger 3 and reducing the volume of the gas-fired boiler. In addition, the flue gas pre-exchanges heat with the liquid in the main heat exchanger 2. When the flue gas flows through the auxiliary heat exchanger 3, the residual heat in the flue gas is relatively small. Only the auxiliary heat exchanger 3 with a smaller flow rate is needed to achieve sufficient heat exchange. Therefore, the flow rate of the liquid in the auxiliary heat exchanger 3 can be set to be less than that in the main heat exchanger 2, so that the auxiliary heat exchanger 3 has a suitable heat exchange capacity, does not generate surplus, and improves heat exchange efficiency.

[0066] In an optional embodiment of the present invention, the flow area of ​​liquid in the auxiliary heat exchanger 3 can be set smaller than that of liquid in the main heat exchanger 2, thereby reducing the flow rate of liquid in the auxiliary heat exchanger 3 to less than that in the main heat exchanger 2. The flow area of ​​liquid in the auxiliary heat exchanger 3 is the total cross-sectional area of ​​the heat exchange pipes through which liquid flows in the auxiliary heat exchanger 3, and the flow area of ​​liquid in the main heat exchanger 2 is the total cross-sectional area of ​​the heat exchange pipes through which liquid flows in the main heat exchanger 2. Alternatively, the flow rate of liquid in the auxiliary heat exchanger 3 can be reduced to less than that in the main heat exchanger 2 by setting the resistance coefficient of the auxiliary heat exchanger 3 to be greater than that of the main heat exchanger 2. Specifically, the resistance coefficients of the auxiliary heat exchanger 3 and the main heat exchanger 2 can be set differently by using different pipe diameters, different numbers of heat exchanger pipes, or different inherent friction coefficients (e.g., the larger the number and diameter of the heat exchanger pipes, the smaller the inherent friction coefficient, resulting in a larger flow area and a smaller resistance coefficient). This makes the resistance coefficient of the auxiliary heat exchanger 3 greater than that of the main heat exchanger 2. It should be noted that while setting different flow areas and / or different resistance coefficients in the auxiliary heat exchanger 3 and the main heat exchanger 2 can achieve the goal of having a lower liquid flow rate in the auxiliary heat exchanger 3 than in the main heat exchanger 2, other measures can also be used to achieve this goal; the specific measures taken are not limited here.

[0067] Furthermore, the ratio of the liquid flow rate Q1 in the auxiliary heat exchanger 3 to the liquid flow rate Q2 in the main heat exchanger 2 is not greater than 1:4 and / or not less than 1:6 (i.e., Q1:Q2≤1:4 and / or Q1:Q2≥1:6). Within this ratio range, it ensures that the sum of the liquid flow rates in the auxiliary heat exchanger 3 and the main heat exchanger 2 (i.e., the total flow rate of the gas-fired boiler) meets the maximum flow rate requirement, while also ensuring that neither the liquid flow rates in the auxiliary heat exchanger 3 nor the main heat exchanger 2 reach their minimum flow rate thresholds. This guarantees that both the parallel-connected auxiliary heat exchanger 3 and the main heat exchanger 2 operate in a highly efficient heat exchange state, thus ensuring heat exchange efficiency. Preferably, the ratio of the liquid flow rate Q1 in the auxiliary heat exchanger 3 to the liquid flow rate Q2 in the main heat exchanger 2 is 1:5. In one specific embodiment of the present invention, the total flow rate of the liquid (Q1+Q2) is 120m³. 3At a flow rate of / h, by designing the flow area or number of heat exchange pipes, the ratio of the flow area available for liquid flow in the auxiliary heat exchanger 3 to that in the main heat exchanger 2 is 1:5. Under a constant inlet pressure, the liquid will automatically flow into the auxiliary heat exchanger 3 and the main heat exchanger 2 at a 1:5 ratio, i.e., 20m³ / h. 3 / h of liquid enters the auxiliary heat exchanger 3, with 100m 3 / h of liquid enters the main heat exchanger 2.

[0068] In this invention, the main heat exchanger 2 and the auxiliary heat exchanger 3 are connected in parallel, and the flow rate of the liquid in the auxiliary heat exchanger 3 is less than that in the main heat exchanger 2. This ensures that the gas-fired boiler has a large flow rate while simultaneously reducing its size and cost, while also guaranteeing appropriate heat exchange capacity and improving heat exchange efficiency for both the main heat exchanger 2 and the auxiliary heat exchanger 3. The maximum liquid flow rate of the gas-fired boiler in this invention (i.e., the sum of the liquid flow rates in the auxiliary heat exchanger 3 and the main heat exchanger 2) can reach no less than 100 m³ / h. 3 The specific reason is as follows: For high-flow-rate scenarios in gas-fired boilers, if the liquid flow paths of the main heat exchanger 2 and the auxiliary heat exchanger 3 are connected in series, all the liquid enters the main heat exchanger 2 and the auxiliary heat exchanger 3 sequentially. To accommodate the large flow of liquid, the flow areas of both the auxiliary heat exchanger 3 and the main heat exchanger 2 need to be large, thus increasing the volume of the gas-fired boiler and increasing costs. Since the flue gas temperature entering the auxiliary heat exchanger 3 is generally low, the heat exchange capacity of the auxiliary heat exchanger 3 is likely to be excessive, and the heat exchange efficiency is low. Therefore, this invention reduces the volume of the gas-fired boiler, lowers costs, improves heat exchange efficiency, and ensures a suitable heat exchange capacity by diverting all the liquid to the auxiliary heat exchanger 3 and the main heat exchanger 2.

[0069] In an optional embodiment of the present invention, such as Figures 1 to 3 As shown, a gas-fired boiler includes at least a boiler inlet pipe 4 and a boiler outlet pipe 5 (the boiler inlet pipe 4 and boiler outlet pipe 5 can be arranged side by side in the horizontal direction, therefore...). Figure 1(The boiler liquid outlet pipe 5 is obscured by the boiler liquid inlet pipe 4 and is not shown.) The boiler liquid inlet pipe 4 is connected to the second liquid inlet 201 of the main heat exchanger 2 and the first liquid inlet 301 of the auxiliary heat exchanger 3. The boiler liquid outlet pipe 5 is connected to the second liquid outlet 202 of the main heat exchanger 2 and the first liquid outlet 302 of the auxiliary heat exchanger 3. The liquid entering the boiler liquid inlet pipe 4 flows into the auxiliary heat exchanger 3 and the main heat exchanger 2 through the first liquid inlet 301 and the second liquid inlet 201, respectively. The liquid in the auxiliary heat exchanger 3 after heat exchange with the flue gas flows into the boiler liquid outlet pipe 5 through the first liquid outlet 302. The liquid in the main heat exchanger 2 after heat exchange with the flue gas flows into the boiler liquid outlet pipe 5 through the second liquid outlet 202. The heat-exchanged liquid is then discharged from the gas boiler through the boiler liquid outlet pipe 5.

[0070] Furthermore, such as Figure 1 , Figure 2 As shown, the auxiliary heat exchanger 3 includes a first inlet pipe 303 with a first inlet port 301 and a first outlet pipe 304 with a first outlet port 302. The main heat exchanger 2 includes a second inlet pipe 203 connected to the second inlet port 201 and a second outlet pipe 204 connected to the second outlet port 202. The first inlet pipe 303 is connected to the second inlet pipe 203, and both the first inlet pipe 303 and the second inlet pipe 203 are connected to the boiler inlet pipe 4. The first outlet pipe 304 is connected to... The second liquid outlet pipe 204 is connected, and both the first liquid outlet pipe 304 and the second liquid outlet pipe 204 are connected to the boiler liquid outlet pipe 5. The liquid entering the boiler liquid inlet pipe 4 flows into the auxiliary heat exchanger 3 and the main heat exchanger 2 through the first liquid inlet pipe 303 and the second liquid inlet pipe 203, respectively. The liquid in the auxiliary heat exchanger 3, after exchanging heat with the flue gas, flows into the boiler liquid outlet pipe 5 through the first liquid outlet pipe 304, and the liquid in the main heat exchanger 2, after exchanging heat with the flue gas, flows into the boiler liquid outlet pipe 5 through the second liquid outlet pipe 204. The connected pipes can be directly connected, or additional pipes can be added between the connected pipes. The specific connection structure between the pipes is not limited here.

[0071] Furthermore, such as Figure 2 As shown, a first valve 8 is provided on the first liquid inlet pipe 303, which can control the connection and disconnection between the first liquid inlet pipe 303 and the boiler liquid inlet pipe 4; and / or, a second valve 9 is provided on the first liquid outlet pipe 304, which can control the connection and disconnection between the first liquid outlet pipe 304 and the boiler liquid outlet pipe 5.

[0072] In an optional embodiment of the present invention, such as Figure 1 , Figure 3As shown, the auxiliary heat exchanger 3 also has a third liquid inlet 305 and a third liquid outlet 306. The third liquid inlet 305 is located on the first liquid inlet pipe 303, and the third liquid outlet 306 is located on the first liquid outlet pipe 304. The third liquid inlet 305 and the third liquid outlet 306 are respectively used to connect to the indoor terminal liquid outlet pipe 6. Along the flow direction of the liquid in the indoor terminal liquid outlet pipe 6, the connection position between the third liquid inlet 305 and the indoor terminal liquid outlet pipe 6 is located upstream of the connection position between the third liquid outlet 306 and the indoor terminal liquid outlet pipe 6. The heating return water in the indoor terminal liquid outlet pipe 6 can be directly introduced into the auxiliary heat exchanger 3 to exchange heat with the flue gas through the third liquid inlet 305 and the third liquid outlet 306, which can improve the heat exchange efficiency of the auxiliary heat exchanger 3. The liquid after heat exchange returns to the indoor terminal liquid outlet pipe 6 and continues to flow into the main heat exchanger 2 for heat exchange.

[0073] Furthermore, a first tee can be provided on the first inlet pipe 303, with the first inlet port 301 and the third inlet port 305 being two ports on the first tee, and also ports on pipelines connected to the two ports on the first tee. Similarly, a second tee can be provided on the first outlet pipe 304, with the first outlet port 302 and the third outlet port 306 being two ports on the second tee, and also ports on pipelines connected to the two ports on the second tee. The provision of the first and second tee ports not only provides the necessary interfaces for the auxiliary heat exchanger 3 but also facilitates the assembly and disassembly of the pipelines.

[0074] Furthermore, such as Figure 3 As shown, the auxiliary heat exchanger 3 includes a third inlet pipe 10 connected to a third inlet port 305 and a third outlet pipe 11 connected to a third outlet port 306. Both the third inlet pipe 10 and the third outlet pipe 11 are connected to the indoor terminal outlet pipe 6. A third valve 12 is installed on the third inlet pipe 10, which controls the connection between the third inlet pipe 10 and the indoor terminal outlet pipe 6. And / or, a fourth valve 13 is installed on the third outlet pipe 11, which controls the connection between the third outlet pipe 11 and the indoor terminal outlet pipe 6. During operation of the gas boiler, the first valve 8 and the second valve 9 can be disconnected to break the parallel connection between the auxiliary heat exchanger 3 and the main heat exchanger 2, allowing the auxiliary heat exchanger 3 to be directly connected to the indoor terminal outlet pipe 6, thereby achieving the purpose of introducing the heating return water in the indoor terminal outlet pipe 6 into the auxiliary heat exchanger 3.

[0075] Furthermore, such as Figure 2 , Figure 3As shown, the boiler inlet pipe 4 is connected to the first outlet of the external heat exchanger 14, the boiler outlet pipe 5 is connected to the first inlet of the external heat exchanger 14, the second inlet of the external heat exchanger 14 is connected to the indoor terminal outlet pipe 6, and the second outlet of the external heat exchanger 14 is connected to the indoor terminal inlet pipe 7. Along the flow direction of the liquid in the indoor terminal outlet pipe 6, the third inlet pipe 10 and the third outlet pipe 11 are located upstream of the external heat exchanger 14, allowing the heating return water in the indoor terminal outlet pipe 6 to flow into the auxiliary heat exchanger 3 for heat exchange. Since the temperature of the heating return water in the indoor terminal outlet pipe 6 is lower than the temperature of the boiler return water, the auxiliary heat exchanger 3 uses the lower-temperature heating return water from the indoor terminal outlet pipe 6 for heat exchange, resulting in higher heat exchange efficiency.

[0076] In an optional embodiment of the present invention, a flow sensor (not shown) is provided in the first inlet pipe 303 and / or the first outlet pipe 304 and / or the second inlet pipe 203 and / or the second outlet pipe 204. Since the auxiliary heat exchanger 3 and the main heat exchanger 2 are connected in parallel in the present invention, and the liquid is diverted to the auxiliary heat exchanger 3 and the main heat exchanger 2, it is necessary to monitor the flow rate of the liquid in the first inlet pipe 303 and / or the first outlet pipe 304 and / or the second inlet pipe 203 and / or the second outlet pipe 204 to ensure that there is no abnormal flow in the auxiliary heat exchanger 3 and the main heat exchanger 2 (i.e., the flow exceeds the preset maximum flow value or is lower than the preset minimum flow threshold value), and an alarm is promptly triggered by an alarm device connected to the flow sensor when an abnormal flow occurs. In this invention, since the total flow rate of liquid entering the gas-fired boiler remains constant, under normal operating conditions, the flow rates of liquid flowing through the first inlet pipe 303, the first outlet pipe 304, the second inlet pipe 203, and the second outlet pipe 204 are in a preset ratio. If an abnormal flow occurs in any of these pipes, the other pipes will also be affected. Therefore, installing a flow sensor on at least one of these pipes can achieve the purpose of flow monitoring. Alternatively, a temperature sensor (not shown) can be installed on the first inlet pipe 303 and / or the first outlet pipe 304 and / or the second inlet pipe 203 and / or the second outlet pipe 204. The temperature sensor collects the temperature value of the liquid in the corresponding pipe, and the flow rate of the liquid flowing through each pipe is determined based on the temperature value.

[0077] In an optional embodiment of the present invention, such as Figure 1As shown, the gas-fired boiler also includes a blower 15. The outlet of the blower 15 is connected to the inlet of the burner 1. The blower 15 is used to mix air and gas in a preset ratio and then send it into the burner 1. The air-gas mixture is ignited and burned on the outer surface of the burner 1, thereby generating high-temperature flue gas. The high-temperature flue gas passes through the main heat exchanger 2 and the auxiliary heat exchanger 3 in sequence, and exchanges heat with the liquid in the main heat exchanger 2 and the liquid in the auxiliary heat exchanger 3 in sequence. Finally, the flue gas is discharged from the flue gas outlet 20.

[0078] Specifically, such as Figure 1 As shown, the gas boiler also includes a main shell 16. The fan 15, burner 1, main heat exchanger 2 and auxiliary heat exchanger 3 are all located inside the main shell 16. The main shell 16 is provided with an air inlet 1601. The air inlet of the fan 15 is connected to the air inlet pipe 17 and the gas inlet pipe 18 respectively. The air inlet pipe 17 is connected to the air inlet 1601. The air inlet of the gas inlet pipe 18 extends to the outside of the main shell 16.

[0079] In this embodiment, as Figure 1 As shown, due to the reduction in the volume of the auxiliary heat exchanger 3, the main heat exchanger 2 can be arranged vertically within the main casing 16 (the main heat exchanger 2 has a cylindrical structure, and its axial direction is set vertically). The burner 1 is located inside the main heat exchanger 2 (the burner 1 and the main heat exchanger 2 have a sleeve-type structure), and the auxiliary heat exchanger 3 is arranged horizontally (i.e., the axial direction of the auxiliary heat exchanger 3 is set horizontally). The auxiliary heat exchanger 3 is arranged side by side with the main heat exchanger 2 in the horizontal direction. The reasonable layout of the main heat exchanger 2 and the auxiliary heat exchanger 3 can achieve the purpose of reducing the volume of the gas boiler. The flue gas outlet of the main heat exchanger 2 is located on the side of the shell of the main heat exchanger 2, and the flue gas inlet of the auxiliary heat exchanger 3 is located on the side of the shell of the auxiliary heat exchanger 3. The flue gas outlet of the main heat exchanger 2 is connected to the flue gas inlet of the auxiliary heat exchanger 3. The flue gas after heat exchange in the main heat exchanger 2 can flow into the auxiliary heat exchanger 3 for heat exchange. The side of the shell of the auxiliary heat exchanger 3 is provided with a flue gas outlet 20, through which the flue gas after heat exchange is discharged.

[0080] In an optional embodiment of the present invention, such as Figure 5 , Figure 6As shown, the auxiliary heat exchanger 3 includes at least a first heat exchange section 310 and a second heat exchange section 320. Liquid flowing into the auxiliary heat exchanger 3 is diverted to the first heat exchange section 310 and the second heat exchange section 320, and the liquid flow paths between the first heat exchange section 310 and the second heat exchange section 320 are connected in parallel. After flowing into the auxiliary heat exchanger 3, the flue gas passes through the first heat exchange section 310 and the second heat exchange section 320 sequentially, creating two return passes within the auxiliary heat exchanger 3, thereby improving the heat exchange capacity of the auxiliary heat exchanger 3 and enhancing heat exchange. Of course, more than one heat exchange section can be provided, with the liquid flow paths between each heat exchange section connected in parallel to achieve the purpose of enhanced heat exchange.

[0081] Furthermore, such as Figure 5 , Figure 6 As shown, the first heat exchange section 310 includes multiple first heat exchange tube groups 311, and the liquid flow paths of the multiple first heat exchange tube groups 311 are connected in series; the second heat exchange section 320 includes multiple second heat exchange tube groups 321, and the liquid flow paths of the multiple second heat exchange tube groups 321 are connected in series. Specifically, each first heat exchange tube group 311 includes multiple first heat exchange tubes 3111, and the liquid flow paths of the multiple first heat exchange tubes 3111 are connected in parallel; each second heat exchange tube group 321 includes multiple second heat exchange tubes 3211, and the liquid flow paths of the multiple second heat exchange tubes 3211 are connected in parallel. This invention employs multiple heat exchange tubes connected in parallel with liquid flow paths to form heat exchange tube groups (i.e., the first heat exchange tube group 311 and the second heat exchange tube group 321). These multiple heat exchange tube groups are connected in series with liquid flow paths. During heat exchange, the liquid flows sequentially through each series-connected heat exchange tube group, thereby effectively controlling the liquid flow rate and ensuring a more uniform temperature change in the first heat exchange section 310 and the second heat exchange section 320 during heat exchange, thus improving the heat exchange efficiency of the auxiliary heat exchanger 3. The first heat exchange tube group 311 can consist of only one heat exchange tube or multiple heat exchange tubes; similarly, the second heat exchange tube group 321 can also consist of only one heat exchange tube or multiple heat exchange tubes.

[0082] Furthermore, multiple first heat exchanger tube groups 311 are connected to each other via a first connecting portion (not shown), and multiple second heat exchanger tube groups 321 are connected to each other via a second connecting portion (not shown). Both the first and second connecting portions are connecting pipes. Along the liquid flow direction, multiple first heat exchanger tubes 3111 connected in parallel in the first heat exchanger tube group 311 upstream of the first connecting portion are connected to the first connecting portion, and multiple first heat exchanger tubes 3111 connected in parallel in the first heat exchanger tube group 311 downstream of the first connecting portion are also connected to the first connecting portion. During heat exchange, the liquid in the multiple parallel first heat exchanger tubes 3111 downstream of the first connecting portion flows through the first connecting portion into the multiple parallel first heat exchanger tubes 3111 downstream of the first connecting portion, thereby achieving liquid exchange between multiple first heat exchanger tube groups 321. The flow between heat pipe groups 311: Along the direction of liquid flow, multiple second heat exchange pipes 3211 connected in parallel in the second heat exchange pipe group 321 located upstream of the second connecting part are respectively connected to the second connecting part, and multiple second heat exchange pipes 3211 connected in parallel in the second heat exchange pipe group 321 located downstream of the second connecting part are also respectively connected to the second connecting part. During the heat exchange process, the liquid in the multiple parallel second heat exchange pipes 3211 located downstream of the second connecting part flows into the multiple parallel second heat exchange pipes 3211 located downstream of the second connecting part through the second connecting part, thereby realizing the flow of liquid between multiple second heat exchange pipe groups 321.

[0083] In this embodiment, along the liquid flow direction, the number of first heat exchange tubes 3111 in the first heat exchange tube group 311 located upstream of the first connecting portion is less than the number of first heat exchange tubes 3111 in the first heat exchange tube group 311 located downstream of the first connecting portion; and / or, along the liquid flow direction, the number of second heat exchange tubes 3211 in the second heat exchange tube group 321 located upstream of the second connecting portion is less than the number of second heat exchange tubes 3211 in the second heat exchange tube group 321 located downstream of the second connecting portion. This results in a gradient increase in the heat exchange capacity of multiple heat exchange tube groups (i.e., the first heat exchange tube group 311 and the second heat exchange tube group 321) for flue gas along the liquid flow direction, thereby improving the heat exchange efficiency of the auxiliary heat exchanger 3 and achieving a better heat exchange effect. In a specific embodiment of the present invention, there are two first heat exchange tube groups 311 and two second heat exchange tube groups 321. The number of first heat exchange tubes 3111 in the first heat exchange tube group 311 located upstream of the first connecting portion may be, but is not limited to, 6, and the number of first heat exchange tubes 3111 in the first heat exchange tube group 311 located downstream of the first connecting portion may be, but is not limited to, 9. The number of second heat exchange tubes 3211 in the second heat exchange tube group 321 located upstream of the second connecting portion may be, but is not limited to, 6, and the number of second heat exchange tubes 3211 in the second heat exchange tube group 321 located downstream of the second connecting portion may be, but is not limited to, 9.

[0084] The multiple first heat exchange tubes 3111 in the first heat exchange tube group 311 and / or the multiple second heat exchange tubes 3211 in the second heat exchange tube group 321 can be heat exchange tubes of the same type or heat exchange tubes of different types (diameter, size, model, etc.). For example, among the nine second heat exchange tubes 3211, five of them are of the same type, while the other four are of the same type (these four second heat exchange tubes are of a different type from the other five). This allows the connection positions to be staggered when different types of heat exchange tubes are connected to the corresponding connecting parts (first connecting part or second connecting part) (it is not necessary for all heat exchange tubes to be arranged in a straight line), which facilitates staggered welding of heat exchange tubes and improves the reliability of the process.

[0085] In an optional embodiment of the present invention, the first heat exchange tube 3111 and the second heat exchange tube 3211 may be heat exchange tubes having the same structure. Further, as... Figures 5 to 8 As shown, both the first heat exchange tube 3111 and the second heat exchange tube 3211 can be heat exchange coils 3311. Each heat exchange tube 3111 and / or the second heat exchange tube 3211 includes at least two layers of staggered coiled structures. The coiled structures are annular, and adjacent layers are staggered along the axial direction of the annular coiled structures. Multiple first heat exchange tubes 3111 are arranged in a staggered manner to form a first heat exchange tube group 311, and multiple second heat exchange tubes 3211 are arranged in a staggered manner to form a second heat exchange tube group 321. By staggering the arrangement of multiple heat exchange coils 3311, flue gas can pass through the gaps between adjacent heat exchange coils 3311, thereby increasing the contact area between the heat exchange coils 3311 and the flue gas and improving heat exchange efficiency.

[0086] Furthermore, such as Figure 5 , Figure 7 As shown, both the first heat exchange tube 3111 and the second heat exchange tube 3211 are heat exchange coils 3311. Multiple first heat exchange tubes 3111 are arranged in parallel to form a hollow first cavity 3112. Multiple second heat exchange tubes 3211 are arranged in parallel to form a hollow second cavity 3212. The flue gas entering the auxiliary heat exchanger 3 can enter the first cavity 3112 and the second cavity 3212 and exchange heat with the liquid in the heat exchange coil 3311.

[0087] In an optional embodiment of the present invention, such as Figure 2 , Figure 3 , Figures 10 to 13As shown, the auxiliary heat exchanger 3 includes a housing 307, a first heat exchange section 310 and a second heat exchange section 320 fixedly disposed within the housing 307. The housing 307 has at least a flue gas inlet 19 communicating with a first cavity 3112 and a flue gas outlet 20 communicating with a second cavity 3212. The first heat exchange section 310 forms the first cavity 3112, and the second heat exchange section 320 forms the second cavity 3212. Flue gas entering the housing 307 through the flue gas inlet 19 passes sequentially through the first cavity 3112 and the second cavity 3212. A disc-shaped first baffle 340 is fixedly installed inside the housing 307 and on the side near the flue gas inlet 19. An annular first flue gas gap 380 exists between the edge of the first baffle 340 and the inner wall of the housing 307. An annular second baffle 350 or an annular third baffle 360 ​​is fixedly installed between the first cavity 3112 and the second cavity 3212. The edge of the second baffle 350 or the edge of the third baffle 360 ​​is sealed to the inner wall of the housing 307. The second or third baffle 360 ​​has a flue gas passage connecting the first cavity 3112 and the second cavity 3212. This flue gas passage is the through hole in the middle of the second baffle 350 or the third baffle 360, allowing flue gas to flow between the first heat exchange section 310 and the second heat exchange section 320. A disc-shaped fourth baffle 370 is fixedly installed inside the housing 307 and on the side near the flue gas outlet 20. There is an annular second flue gas gap 390 between the edge of the fourth baffle 370 and the inner wall of the housing 307. Of course, the second baffle 350 and the third baffle 360 ​​can also be installed at the same time. In this case, a pipe is used to connect the through hole in the middle of the second baffle 350 and the through hole in the middle of the third baffle 360 ​​to form a flue gas passage connecting the first cavity 3112 and the second cavity 3212. It can be seen that the flue gas passage can have a preset length in the flue gas flow direction, or it can be just a flue gas outlet (or flue gas hole), and there is no length limitation in the flue gas flow direction.

[0088] In this embodiment, as Figure 14As shown, the auxiliary heat exchanger 3 forms a heat exchange channel for flue gas to flow through the auxiliary heat exchanger 3 via the flue gas inlet 19, the first flue gas gap 380, the gap between the heat exchange coils 3311 in the first heat exchange section 310, the flue gas passages provided by the second baffle 350 and / or the third baffle 360, the gap between the heat exchange coils 3311 in the second heat exchange section 320, the second flue gas gap 390, and the flue gas outlet 20. During the heat exchange process, the flue gas enters the first heat exchange section 310 inside the shell 307 through the flue gas inlet 19. Due to the obstruction of the first baffle 340, the flue gas cannot directly enter the first cavity 3112, but flows through the first baffle 340 in sequence. The flue gas enters the first cavity 3112 through the gap between the first flue gas gap 380 and the gap between the heat exchange coils 3311 in the first heat exchange section 310. The flue gas in the first cavity 3112 flows into the second cavity 3212 through the flue gas channel. Due to the obstruction of the fourth baffle 370, the flue gas cannot flow out of the second cavity 3212 directly. Instead, it needs to flow through the gap between the heat exchange coils 3311 in the second heat exchange section 320 and the second flue gas gap 390 in sequence before being discharged from the second cavity 3212. Finally, the flue gas that has completed heat exchange in the second heat exchange section 320 is discharged from the auxiliary heat exchanger 3 through the flue gas outlet 20.

[0089] The design of this heat exchange channel maximizes the flow path of the flue gas within the auxiliary heat exchanger 3 and ensures that the flue gas can fully contact the heat exchange coils in the first heat exchange section 310 and the second heat exchange section 320 during its flow. The process of the flue gas flowing through the auxiliary heat exchanger 3 along this heat exchange channel not only achieves the purpose of sufficient heat exchange between the flue gas and the liquid in the heat exchange coils 3311 in the first heat exchange section 310 and the second heat exchange section 320, but also forms at least two return passes inside the auxiliary heat exchanger 3, effectively improving the heat exchange capacity of the auxiliary heat exchanger 3 and enhancing heat exchange.

[0090] Furthermore, such as Figure 2 , Figure 3 As shown, the flue gas inlet 19 and the flue gas outlet 20 are located on opposite side walls of the shell 307, respectively. The flue gas inlet 19 is connected to the first heat exchange section 310, and the flue gas outlet 20 is connected to the second heat exchange section 320.

[0091] In an optional embodiment of the present invention, such as Figure 10As shown, the first baffle 340 is provided with at least one through hole 3401 for flue gas to pass through. After the flue gas enters the housing 307 through the flue gas inlet 19, a small portion of the flue gas can flow through the through hole 3401 into the gap between the heat exchange coils 3311 in the first heat exchange section 310 to exchange heat with the liquid in the heat exchange coils 3311, and then flow into the first cavity 3112. Thus, the through hole 3401 on the first baffle 340 provides another path for a small amount of flue gas to enter the first cavity 3112, thereby ensuring that the flue gas and the liquid in the heat exchange coils 3311 of the first heat exchange section 310 can fully exchange heat, improving the heat exchange efficiency. In addition, the through hole 3401 on the first baffle 340 can also prevent the flue gas from directly entering the gap between the heat exchange coils 3311 and generating excessive pressure.

[0092] Furthermore, such as Figure 10 As shown, the through holes 3401 are located near the edge of the first baffle 340. There are multiple through holes 3401, which are spaced apart and evenly arranged along the circumference of the first baffle 340. This ensures that the position where the flue gas enters the gap between the heat exchange coils 3311 in the first heat exchange section 310 through the through holes 3401 has the longest possible path with the first cavity 3112, thereby extending the flow time of the flue gas in the gap between the heat exchange coils 3311 in the first heat exchange section 310 and ensuring sufficient heat exchange between the flue gas and the liquid in the heat exchange coils 3311.

[0093] Furthermore, such as Figure 10 As shown, in the radial direction of the first baffle 340, a plurality of through holes 3401 are provided in a ring shape along the circumference of the first baffle 340 from the edge position near the edge position to the edge position away from the edge position of the first baffle 340. The diameter of the through holes 3401 located near the edge position of the first baffle 340 is larger than the diameter of the through holes 3401 located away from the edge position of the first baffle 340.

[0094] In this invention, the auxiliary heat exchanger 3 can be made of stainless steel, so that even if condensate is generated after heat exchange, it will not corrode the auxiliary heat exchanger 3.

[0095] The features and advantages of the gas-fired boiler of the present invention are as follows:

[0096] 1. The gas boiler adopts a parallel connection of the main heat exchanger 2 and the auxiliary heat exchanger 3. When the gas boiler is running, liquid flows through both the auxiliary heat exchanger 3 and the main heat exchanger 2, thereby increasing the liquid flow rate during the operation of the gas boiler. The main heat exchanger 2 and the auxiliary heat exchanger 3 exchange heat between the flowing liquid and the flue gas, thereby improving the working efficiency of the gas boiler. The operating cost of the gas boiler of the present invention is much lower than that of a gas boiler of the same power.

[0097] Second, the gas-fired boiler adopts a parallel connection of the main heat exchanger 2 and the auxiliary heat exchanger 3. When the gas-fired boiler is running, the liquid is diverted to the auxiliary heat exchanger 3 and the main heat exchanger 2, and the flow rate of the liquid in the auxiliary heat exchanger 3 can be less than the flow rate of the liquid in the main heat exchanger 2, thereby reducing the volume of the auxiliary heat exchanger 3 and achieving the purpose of reasonable layout of the main heat exchanger 2 and the auxiliary heat exchanger 3 and reducing the volume of the gas-fired boiler.

[0098] Third, in this gas-fired boiler, since the main heat exchanger 2 and the auxiliary heat exchanger 3 are connected in parallel, when the flue gas flows through the auxiliary heat exchanger 3, the residual heat in the flue gas is relatively small. Only the auxiliary heat exchanger 3 with a smaller flow rate is needed to achieve sufficient heat exchange. Therefore, while reducing the volume of the auxiliary heat exchanger 3, the flow rate of the liquid in the auxiliary heat exchanger 3 can be set to be less than the flow rate of the liquid in the main heat exchanger 2, so that the auxiliary heat exchanger 3 has a suitable heat exchange capacity and will not generate surplus, thereby ensuring that the auxiliary heat exchanger 3 has sufficient heat exchange capacity and improving heat exchange efficiency.

[0099] Fourth, in this gas-fired boiler, the ratio range of the liquid flow rate in the auxiliary heat exchanger 3 to the liquid flow rate in the main heat exchanger 2 is set. This ensures that the sum of the liquid flow rates in the auxiliary heat exchanger 3 and the main heat exchanger 2 meets the maximum flow rate requirement, while also ensuring that neither the liquid flow rate in the auxiliary heat exchanger 3 nor the liquid flow rate in the main heat exchanger 2 reaches the minimum flow rate threshold of the auxiliary heat exchanger 3 and the main heat exchanger 2. This ensures that both the parallel-connected auxiliary heat exchanger 3 and the main heat exchanger 2 are in a high-efficiency heat exchange state, thereby ensuring heat exchange efficiency.

[0100] V. In this gas-fired boiler, in addition to the first liquid inlet 301 and the first liquid outlet 302, the auxiliary heat exchanger 3 also has a third liquid inlet 305 and a third liquid outlet 306. The heating return water in the indoor terminal liquid outlet pipe 6 can be directly introduced into the auxiliary heat exchanger 3 for heat exchange through the third liquid inlet 305 and the third liquid outlet 306, thereby improving the heat exchange efficiency of the auxiliary heat exchanger 3.

[0101] VI. In this gas-fired boiler, due to the reduction in the volume of the auxiliary heat exchanger 3, the main heat exchanger 2 can be arranged vertically and the auxiliary heat exchanger 3 can be arranged horizontally within the main shell 16. The layout of the main heat exchanger 2 and the auxiliary heat exchanger 3 is more reasonable, which can achieve the purpose of reducing the volume of the gas-fired boiler.

[0102] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A gas-fired boiler, characterized in that, The gas-fired boiler includes a burner, a main heat exchanger, and an auxiliary heat exchanger. The flue gas produced after the burner ignites the combustible gas flows sequentially through the main heat exchanger and the auxiliary heat exchanger, where heat exchange occurs. The auxiliary heat exchanger has at least a first liquid inlet and a first liquid outlet, and the main heat exchanger has at least a second liquid inlet and a second liquid outlet. The first liquid inlet is connected to the second liquid inlet, and the first liquid outlet is connected to the second liquid outlet. When the gas-fired boiler is running, the flow rate of the liquid in the auxiliary heat exchanger is less than the flow rate of the liquid in the main heat exchanger. The flow area available for liquid flow in the auxiliary heat exchanger is smaller than the flow area available for liquid flow in the main heat exchanger. The ratio of the liquid flow rate in the auxiliary heat exchanger to the liquid flow rate in the main heat exchanger is not greater than 1:4 and not less than 1:

6.

2. The gas-fired boiler according to claim 1, characterized in that, The resistance coefficient of the auxiliary heat exchanger is greater than that of the main heat exchanger.

3. The gas-fired boiler according to claim 1, characterized in that, The gas-fired boiler includes at least a boiler liquid inlet pipe and a boiler liquid outlet pipe. The liquid entering through the boiler liquid inlet pipe flows into the auxiliary heat exchanger and the main heat exchanger through the first liquid inlet and the second liquid inlet, respectively. The liquid after exchanging heat with the flue gas flows into the boiler liquid outlet pipe through the first liquid outlet and the second liquid outlet, respectively.

4. The gas-fired boiler according to claim 3, characterized in that, The auxiliary heat exchanger includes a first inlet pipe with the first liquid inlet and a first outlet pipe with the first liquid outlet. The main heat exchanger includes a second inlet pipe connected to the second liquid inlet and a second outlet pipe connected to the second liquid outlet. The first inlet pipe is connected to the second inlet pipe, and both the first inlet pipe and the second inlet pipe are connected to the boiler liquid inlet pipe. The first outlet pipe is connected to the second outlet pipe, and both the first outlet pipe and the second outlet pipe are connected to the boiler liquid outlet pipe.

5. The gas-fired boiler according to claim 4, characterized in that, The auxiliary heat exchanger also has a third liquid inlet and a third liquid outlet. The third liquid inlet is disposed on the first liquid inlet pipe, and the third liquid outlet is disposed on the first liquid outlet pipe. The third liquid inlet and the third liquid outlet are respectively used to connect to the indoor terminal liquid outlet pipe. Along the flow direction of the liquid in the indoor terminal liquid outlet pipe, the connection position between the third liquid inlet and the indoor terminal liquid outlet pipe is located upstream of the connection position between the third liquid outlet and the indoor terminal liquid outlet pipe.

6. The gas-fired boiler according to claim 5, characterized in that, A first valve is provided on the first liquid inlet pipe, and the first valve is used to control the connection and disconnection between the first liquid inlet pipe and the boiler liquid inlet pipe; And / or, a second valve is provided on the first liquid outlet pipe, the second valve being used to control the connection and disconnection between the first liquid outlet pipe and the boiler liquid outlet pipe.

7. The gas-fired boiler according to claim 5, characterized in that, The boiler inlet pipe and the boiler outlet pipe are respectively connected to the first outlet and the first inlet of the external heat exchanger, and the second inlet and the second outlet of the external heat exchanger are respectively connected to the indoor end outlet pipe and the indoor end inlet pipe.

8. The gas-fired boiler according to claim 4, characterized in that, The first inlet pipe and / or the first outlet pipe and / or the second inlet pipe and / or the second outlet pipe are equipped with a flow sensor and / or a temperature sensor.

9. The gas-fired boiler according to claim 1, characterized in that, The auxiliary heat exchanger includes at least a first heat exchange section and a second heat exchange section. The liquid flowing into the auxiliary heat exchanger is diverted to the first heat exchange section and the second heat exchange section, and the liquid flow path between the first heat exchange section and the second heat exchange section is connected in parallel.

10. The gas-fired boiler according to claim 9, characterized in that, The first heat exchange section includes a plurality of first heat exchange tube groups, and the liquid flow paths of the plurality of first heat exchange tube groups are connected in series; The second heat exchange section includes a plurality of second heat exchange tube groups, and the liquid flow paths of the plurality of second heat exchange tube groups are connected in series.

11. The gas-fired boiler according to claim 10, characterized in that, The first heat exchange tube group includes multiple first heat exchange tubes, and the liquid flow paths of the multiple first heat exchange tubes are connected in parallel; The second heat exchange tube group includes multiple second heat exchange tubes, and the liquid flow paths of the multiple second heat exchange tubes are connected in parallel.

12. The gas-fired boiler according to claim 11, characterized in that, Multiple first heat exchanger tube groups are connected to each other through a first connecting part, and multiple second heat exchanger tube groups are connected to each other through a second connecting part.

13. The gas-fired boiler according to claim 12, characterized in that, Along the direction of liquid flow, the number of first heat exchange tubes in the first heat exchange tube group located upstream of the first connecting part is less than the number of first heat exchange tubes in the first heat exchange tube group located downstream of the first connecting part. And / or, along the direction of liquid flow, the number of second heat exchange tubes in the second heat exchange tube group located upstream of the second connecting portion is less than the number of second heat exchange tubes in the second heat exchange tube group located downstream of the second connecting portion.

14. The gas-fired boiler according to claim 11, characterized in that, Both the first heat exchange tube and the second heat exchange tube are heat exchange coils. The first heat exchange tube and / or the second heat exchange tube include at least two layers of staggered coiled structures. Multiple first heat exchange tubes are staggered to form the first heat exchange tube group, and multiple second heat exchange tubes are staggered to form the second heat exchange tube group.

15. The gas-fired boiler according to claim 11, characterized in that, Both the first heat exchange tube and the second heat exchange tube are heat exchange coils. Multiple first heat exchange tubes are arranged in parallel to form a hollow first cavity; multiple second heat exchange tubes are arranged in parallel to form a hollow second cavity.

16. The gas-fired boiler according to claim 15, characterized in that, The auxiliary heat exchanger includes a housing, and the first heat exchange section and the second heat exchange section are disposed inside the housing. The housing has at least a flue gas inlet communicating with the first cavity and a flue gas outlet communicating with the second cavity. The first heat exchange section and the second heat exchange section respectively form a first cavity and a second cavity. The flue gas entering the shell through the flue gas inlet passes through the first cavity and the second cavity in sequence. A first baffle is provided inside the shell and on the side close to the flue gas inlet. A first flue gas gap is formed between the edge of the first baffle and the inner wall of the shell. A second baffle and / or a third baffle are provided between the first cavity and the second cavity. The edge of the second baffle and / or the edge of the third baffle are respectively connected to the inner wall of the shell, and the second baffle and / or the third baffle have a flue gas passage connecting the first cavity and the second cavity. A fourth baffle is provided inside the housing and on the side near the flue gas outlet, and a second flue gas gap is formed between the edge of the fourth baffle and the inner wall of the housing.

17. The gas-fired boiler according to claim 16, characterized in that, The flue gas inlet and the flue gas outlet are located on opposite side walls of the housing.

18. The gas-fired boiler according to claim 16, characterized in that, The first baffle is provided with at least one through hole for the flue gas to pass through.

19. The gas-fired boiler according to claim 18, characterized in that, The through hole is located near the edge of the first baffle.

20. The gas-fired boiler according to claim 1, characterized in that, The gas boiler also includes a fan, the outlet of which is connected to the inlet of the burner. The fan is used to mix air and gas in a preset ratio and then send the mixture into the burner.

21. The gas-fired boiler according to claim 20, characterized in that, The gas-fired boiler also includes a main outer shell, and the fan, the burner, the main heat exchanger and the auxiliary heat exchanger are all located inside the main outer shell. The main outer shell is provided with an air inlet. The air inlet of the fan is connected to the air inlet pipe and the gas inlet pipe, respectively.

22. The gas-fired boiler according to claim 1, characterized in that, The main heat exchanger is arranged vertically, the burner is located inside the main heat exchanger, the auxiliary heat exchanger is arranged horizontally, the flue gas outlet of the main heat exchanger is located on the side of the shell of the main heat exchanger, and the flue gas inlet of the auxiliary heat exchanger is located on the side of the shell of the auxiliary heat exchanger.

23. The gas-fired boiler according to claim 1, characterized in that, The maximum liquid flow rate of the gas-fired boiler shall not be less than 100 m³ / s. 3 / h.

Images