A boiler system for mixed combustion of low calorific value gas and high calorific value gas

Abstract

An embodiment of the present application provides a boiler system for mixed combustion of low calorific value gas and high calorific value gas, relating to the technical field of combustion equipment, including a boiler body, an ignition air pipeline, an ignition gas pipeline, a main air pipeline, a low calorific value gas pipeline, a high calorific value gas pipeline and a control unit; a main burner and an ignition burner are provided in the combustion chamber of the boiler body, the air outlet ends of the ignition air pipeline and the ignition gas pipeline are connected to the ignition burner, and the air outlet ends of the main air pipeline, the low calorific value gas pipeline and the high calorific value gas pipeline are connected to the main burner, so that the low calorific value gas and the high calorific value gas are mixed and burned, solving the technical problem that the low calorific value gas cannot be stably burned alone; flow regulating valves are provided on both the low calorific value gas pipeline and the high calorific value gas pipeline, which can ensure flame stability during combustion through flow control.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion equipment, and in particular to a boiler system for mixed combustion of low calorific value gas and high calorific value gas. Background Art

[0002] Low calorific value gas refers to a gas with a calorific value of less than 6.28MJ / m 3 Common low-calorific-value gases in industry include blast furnace coke oven gas, petrochemical smelting tail gas, landfill gas, and coal mine gas. The large amount of low-calorific-value gases discharged into the atmosphere each year not only leads to a huge waste of resources, but also causes a serious greenhouse effect.

[0003] Combustion purification is the most effective method for treating low calorific value gases. This method not only effectively eliminates harmful substances in low calorific value gases, but also extracts their energy, thereby improving existing energy utilization and protecting the environment. However, when low calorific value gases are burned alone, the flame is unstable and easily extinguished. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides a boiler system for mixed combustion of low calorific value gas and high calorific value gas to solve the technical problem of unstable flame and easy flameout when low calorific value gas is burned alone.

[0005] An embodiment of the present invention provides a boiler system for mixed combustion of low calorific value gas and high calorific value gas, comprising:

[0006] A boiler body, wherein a main burner and an ignition burner are provided in a combustion chamber of the boiler body;

[0007] an ignition air pipeline, wherein an air inlet end of the ignition air pipeline is connected to a blower, and an air outlet end of the ignition air pipeline is connected to the ignition burner;

[0008] an ignition gas pipeline, wherein an air inlet end of the ignition gas pipeline is connected to a high calorific value gas supply source, and an air outlet end of the ignition gas pipeline is connected to the ignition burner;

[0009] A main air pipeline, the air inlet end of the main air pipeline is connected to the blower, and the air outlet end of the main air pipeline is connected to the main burner; an air damper with an adjustable opening is provided in the main air pipeline;

[0010] a low calorific value gas pipeline, wherein the gas inlet end of the low calorific value gas pipeline is connected to the low calorific value gas supply source, and the gas outlet end of the low calorific value gas pipeline is connected to the main burner; a low calorific value gas flow regulating valve is provided on the low calorific value gas pipeline;

[0011] A high calorific value gas pipeline, wherein the gas inlet end of the high calorific value gas pipeline is connected to the high calorific value gas supply source, and the gas outlet end of the high calorific value gas pipeline is connected to the main burner; a high calorific value gas flow regulating valve is provided on the high calorific value gas pipeline;

[0012] a control unit, the low calorific value gas flow regulating valve and the high calorific value gas flow regulating valve being electrically connected to the control unit; when the gas pressure of the low calorific value gas does not reach the required lower pressure limit, the high calorific value fuel is burned alone; when the gas pressure of the low calorific value gas reaches the required lower pressure limit, the low calorific value gas and the high calorific value gas are burned together;

[0013] The main burner is divided into an air chamber, a high calorific value gas chamber, a low calorific value gas chamber and a premixing chamber, wherein the air chamber and the premixing chamber are both connected to the main air pipeline, the high calorific value gas chamber is connected to the high calorific value gas pipeline, and the low calorific value gas chamber is connected to the low calorific value gas pipeline and is connected to the premixing chamber.

[0014] Optionally, the low calorific value gas pipeline is provided with a low calorific value gas pressure transmitter A, a low calorific value gas pressure switch A, a low calorific value gas pressure gauge, the low calorific value gas flow regulating valve, the low calorific value gas stop valve A, the low calorific value gas stop valve B, the low calorific value gas throttling orifice plate, the low calorific value gas pressure switch B and the low calorific value gas ball valve in sequence along the gas flow direction; the low calorific value gas pressure transmitter A is electrically connected to the control unit.

[0015] Optionally, a low calorific value gas pressure transmitter B is connected between the gas inlet end and the gas outlet end of the low calorific value gas throttling orifice plate, and the low calorific value gas pressure transmitter B is electrically connected to the control unit.

[0016] Optionally, the high calorific value gas pipeline is provided with a high calorific value gas pressure switch A, a high calorific value gas pressure gauge, a high calorific value gas pressure stabilizing valve, the high calorific value gas flow regulating valve, a high calorific value gas stop valve A, a high calorific value gas stop valve B, a high calorific value gas throttling orifice plate, a high calorific value gas pressure switch B and a high calorific value gas ball valve in sequence along the gas flow direction.

[0017] Optionally, the air inlet end of the ignition gas pipeline is connected between the high calorific value gas pressure switch A and the high calorific value gas pressure gauge.

[0018] Optionally, an ignition gas shut-off valve A, an ignition gas pressure-stabilizing valve, an ignition gas shut-off valve B, an ignition gas throttling orifice plate, and an ignition gas ball valve are sequentially arranged on the ignition gas pipeline along its gas flow direction.

[0019] Optionally, an air ball valve and an air throttling orifice plate are sequentially provided on the ignition air pipeline along the air circulation direction thereof.

[0020] Optionally, a flue gas oxygen content transmitter is installed at the flue gas outlet of the boiler body; the blower is provided with a frequency converter; and both the flue gas oxygen content transmitter and the frequency converter are electrically connected to the control unit.

[0021] Optionally, the ignition burner is inserted in the air cavity, and the bottom of the air cavity is provided with a through hole for the ignition burner to pass through and a plurality of air holes for air to pass through; the high calorific value gas chamber is sleeved on the outside of the air cavity, and the low calorific value gas chamber and the premixing chamber are both sleeved on the outside of the high calorific value gas chamber; the low calorific value gas chamber extends into the premixing chamber and is provided with a plurality of low calorific value gas holes connected with the premixing chamber; the bottom of the premixing chamber is provided with a plurality of injection pipes connected with the premixing chamber at intervals along its circumference, and the outer wall of the high calorific value gas chamber is provided with a plurality of high calorific value gas nozzles connected with the high calorific value gas chamber along its circumference, and the high calorific value gas nozzles are respectively inserted into the corresponding injection pipes and a gap is left between the two for the mixed gas to pass through.

[0022] Optionally, a plurality of high calorific value gas holes are provided on the inner wall of the high calorific value gas cavity at intervals along its circumference, and the high calorific value gas holes are located on the gas outlet side of the air hole.

[0023] The embodiments of the present invention have the following beneficial effects:

[0024] 1. The mixed combustion of low calorific value gas and high calorific value gas solves the technical problem that low calorific value gas cannot be stably burned alone;

[0025] 2. Ensure flame stability when two gases are burning simultaneously by controlling the flow of the two gases;

[0026] 3. When there is low calorific value gas, the combustion mode of mixed combustion of low calorific value gas and high calorific value gas is adopted; when there is no low calorific value gas, it can automatically switch to the high calorific value gas single combustion mode, and ensure the flame stability when the high calorific value gas is burned alone through flow control;

[0027] 4. Premix the low calorific value gas with combustion air before burning so that the low calorific value gas can be fully burned. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1Schematic diagram of the system structure of an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of regulating the flow rate of low calorific value gas and the flow rate of high calorific value gas in an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of the structure of the main burner and the ignition burner in an embodiment of the present invention;

[0032] The numbers in the figure represent:

[0033] 1. Boiler body; 2. Ignition air line; 3. Ignition gas line; 4. Main air line; 5. Low calorific value gas line; 6. High calorific value gas line; 7. Control unit; 8. Main burner; 9. Ignition burner; 10. Blower; 11. Air damper; 12. Low calorific value gas pressure transmitter A; 13. Low calorific value gas pressure switch A; 14. Low calorific value gas pressure gauge; 15. Low calorific value gas flow regulating valve; 16. Low calorific value gas stop valve A; 17. Low calorific value gas stop valve B; 18. Low calorific value gas throttling orifice; 19. Low calorific value gas pressure switch B; 20. Low calorific value gas ball valve; 21. Low calorific value gas pressure transmitter B; 22. High calorific value gas pressure switch A; 23. High calorific value gas pressure gauge; 24. High calorific value Gas pressure regulating valve; 25. High calorific value gas flow regulating valve; 26. High calorific value gas stop valve A; 27. High calorific value gas stop valve B; 28. High calorific value gas throttling orifice; 29. High calorific value gas pressure switch B; 30. High calorific value gas ball valve; 31. Ignition gas stop valve A; 32. Ignition gas pressure regulating valve; 33. Ignition gas stop valve B; 34. Ignition gas throttling orifice; 35. Ignition gas ball valve; 36. Air ball valve; 37. Air throttling orifice; 38. Flue gas oxygen content transmitter; 39. Frequency converter; 40. Air cavity; 41. High calorific value gas cavity; 42. Low calorific value gas cavity; 43. Premixing cavity; 44. Air hole; 45. Low calorific value gas hole; 46. Injection pipe; 47. High calorific value gas nozzle; 48. High calorific value gas hole. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] See also Figure 1As shown, an embodiment of the present invention provides a boiler system for mixed combustion of low calorific value gas and high calorific value gas, including a boiler body 1, an ignition air pipeline 2, an ignition gas pipeline 3, a main air pipeline 4, a low calorific value gas pipeline 5, a high calorific value gas pipeline 6 and a control unit 7. A main burner 8 and an ignition burner 9 are provided in the combustion chamber of the boiler body 1.

[0036] The air inlet of the ignition air line 2 is connected to a blower 10, and the air outlet of the ignition air line 2 is connected to the ignition burner 9, which is used to provide ignition air to the ignition burner 9. The air inlet of the ignition gas line 3 is connected to a supply source of high calorific value gas (such as natural gas or other conventional gas), and the air outlet of the ignition gas line 3 is connected to the ignition burner 9, which is used to provide ignition gas to the ignition burner 9.

[0037] The air inlet of the main air line 4 is also connected to the blower 10, and the air outlet of the main air line 4 is connected to the main burner 8, thereby providing combustion air to the main burner 8. An air damper 11 with an adjustable opening is provided within the main air line 4, and the air flow within the main air line 4 can be adjusted by adjusting the opening of the air damper 11.

[0038] The inlet of the high-calorific-value gas pipeline 6 is connected to a high-calorific-value gas supply source, and the outlet of the high-calorific-value gas pipeline 6 is connected to the main burner 8, providing combustion gas to the main burner 8. The inlet of the low-calorific-value gas pipeline 5 is connected to a low-calorific-value gas supply source, and the outlet of the low-calorific-value gas pipeline 5 is also connected to the main burner 8, allowing low-calorific-value gas (such as biogas, byproduct hydrogen, blast furnace gas, and other byproduct gases generated during industrial production processes) to be introduced into the main burner 8 for combustion. The mixed combustion of low-calorific-value gas and high-calorific-value gas can solve the technical problem of the low-calorific-value gas being unable to burn stably on its own.

[0039] A low calorific value gas flow regulating valve 15 is provided on the low calorific value gas pipeline 5, and a high calorific value gas flow regulating valve 25 is provided on the high calorific value gas pipeline 6. The low calorific value gas flow regulating valve 15 and the high calorific value gas flow regulating valve 25 are both electrically connected to the control unit 7 to automatically adjust the low calorific value gas flow and the high calorific value gas flow through the control unit 7 to ensure flame stability during combustion.

[0040] Specifically, in the embodiment of the present invention, a low calorific value gas pressure transmitter A12, a low calorific value gas pressure switch A13, a low calorific value gas pressure gauge 14, a low calorific value gas flow regulating valve 15, a low calorific value gas stop valve A16, a low calorific value gas stop valve B17, a low calorific value gas throttling orifice 18, a low calorific value gas pressure switch B19 and a low calorific value gas ball valve 20 are sequentially arranged on the low calorific value gas pipeline 5 along its gas flow direction. During normal boiler operation, when the low calorific value gas pressure (detected by low calorific value gas pressure switch A13) reaches the required lower pressure limit, low calorific value gas shut-off valves A16 and B17 open, allowing the low calorific value gas and high calorific value gas to burn together. If the low calorific value gas pressure (detected by low calorific value gas pressure switch A13) is too low and falls below the required lower pressure limit, low calorific value gas shut-off valves A16 and B17 close, automatically switching to single-fuel combustion mode, where the high calorific value fuel burns alone. If the low calorific value gas pressure detected by low calorific value gas pressure switch B19 is too high (i.e., reaches the required upper pressure limit), the boiler system's interlocking protection program is triggered, causing the boiler to automatically shut down.

[0041] The low calorific value gas pressure transmitter A12 is electrically connected to the control unit 7. The control unit 7 can automatically calculate and adjust the opening of the low calorific value gas flow regulating valve 15 according to the pressure signal sent by the low calorific value gas pressure transmitter A12. Figure 2 As shown, the opening of the high calorific value gas flow regulating valve 25 is automatically calculated and adjusted to adjust the supply ratio of the low calorific value gas to the high calorific value gas. Furthermore, a low calorific value gas pressure transmitter B21 can be connected between the inlet and outlet ends of the low calorific value gas throttling orifice 18. The low calorific value gas pressure transmitter B21 is also electrically connected to the control unit 7 and can feed back the detected pressure signal to the control unit 7. The low calorific value gas pressure can also be monitored through the low calorific value gas pressure transmitter B21.

[0042] Specifically, the high calorific value gas pipeline 6 of the embodiment of the present invention is provided with a high calorific value gas pressure switch A22, a high calorific value gas pressure gauge 23, a high calorific value gas pressure stabilizing valve 24, a high calorific value gas flow regulating valve 25, a high calorific value gas stop valve A26, a high calorific value gas stop valve B27, a high calorific value gas throttling orifice 28, a high calorific value gas pressure switch B29 and a high calorific value gas ball valve 30 in sequence along the gas flow direction thereof, wherein the opening of the high calorific value gas flow regulating valve 25 is automatically calculated and adjusted by the control unit 7.

[0043] The air inlet of the ignition gas pipeline 3 can be directly connected between the high calorific value gas pressure switch A22 and the high calorific value gas pressure gauge 23. Specifically, in this embodiment of the present invention, the ignition gas pipeline 3 is provided with an ignition gas shutoff valve A31, an ignition gas pressure regulating valve 32, an ignition gas shutoff valve B33, an ignition gas throttling orifice 34, and an ignition gas ball valve 35, in sequence along the gas flow direction. The ignition air pipeline 2 is provided with an air ball valve 36 and an air throttling orifice 37, in sequence along the air flow direction.

[0044] Furthermore, a flue gas oxygen content transmitter 38 is installed at the flue gas outlet of the boiler body 1; a frequency converter 39 is provided for the blower 10; both the flue gas oxygen content transmitter 38 and the frequency converter 39 are electrically connected to the control unit 7. The flue gas oxygen content transmitter 38 can detect the oxygen content in the flue gas discharged from the boiler and feed the detection result back to the control unit 7. The control unit 7 then calculates the correction coefficient of the frequency converter 39 based on the oxygen content in the flue gas and adjusts the operating frequency of the blower 10 to achieve the optimal combustion effect.

[0045] Accordingly, the embodiment of the present invention also provides a main burner 8 that supports the mixed combustion of low calorific value gas and high calorific value gas. Figure 3 As shown, the main burner 8 is divided into an air chamber 40, a high calorific value gas chamber 41, a low calorific value gas chamber 42 and a premixing chamber 43, wherein the air chamber 40 and the premixing chamber 43 are both connected to the main air pipeline 4, the high calorific value gas chamber 41 is connected to the high calorific value gas pipeline 6, and the low calorific value gas chamber 42 is connected to the low calorific value gas pipeline 5.

[0046] The ignition burner 9 is inserted into the air cavity 40. The bottom of the air cavity 40 (the side facing the combustion chamber) is provided with a through hole for the ignition burner 9 to pass through and a plurality of air holes 44 for air to pass through. The combustion air in the air cavity 40 can enter the combustion chamber of the boiler body 1 through the air holes 44.

[0047] The high-calorific-value gas chamber 41 is nested outside the air chamber 40, while the low-calorific-value gas chamber 42 and premixing chamber 43 are both nested outside the high-calorific-value gas chamber 41. The low-calorific-value gas chamber 42 extends into the premixing chamber 43 and is provided with a plurality of low-calorific-value gas holes 45 communicating with the premixing chamber 43. This allows the low-calorific-value gas in the low-calorific-value gas chamber 42 to enter the premixing chamber 43 through the low-calorific-value gas holes 45 and mix with the combustion air in the premixing chamber 43. A plurality of injection pipes 46 are spaced along the circumference of the bottom of the premixing chamber 43 (the side facing the combustion chamber). These injection pipes 46 communicate with the premixing chamber 43, allowing the mixed gas in the premixing chamber 43 to enter the combustion chamber of the boiler body 1. Premixing the low-calorific-value gas with the combustion air before combustion ensures sufficient combustion of the low-calorific-value gas.

[0048] The outer wall of the high-calorific-value gas chamber 41 is provided with a plurality of high-calorific-value gas nozzles 47 connected to the high-calorific-value gas chamber 41 along its circumference. Each high-calorific-value gas nozzle 47 is inserted into a corresponding gas injection pipe 46, with a gap between the two for the passage of the mixed gas. The high-calorific-value gas in the high-calorific-value gas chamber 41 can enter the combustion chamber of the boiler body 1 through the high-calorific-value gas nozzles 47 and quickly mix with the mixed gas ejected from the gas injection pipe 46, facilitating combustion. Furthermore, a plurality of high-calorific-value gas holes 48 can be provided at intervals along the circumference of the inner wall of the high-calorific-value gas chamber 41. The high-calorific-value gas holes 48 are located on the outlet side of the air holes 44. The high-calorific-value gas ejected from the high-calorific-value gas holes 48 can mix with the combustion air ejected from the air holes 44 below the ignition burner 9, facilitating ignition and combustion of the ignition burner 9.

[0049] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present invention. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A boiler system for mixed combustion of low calorific value gas and high calorific value gas, characterized in that: include: A boiler body, wherein a main burner and an ignition burner are provided in a combustion chamber of the boiler body; an ignition air pipeline, wherein an air inlet end of the ignition air pipeline is connected to a blower, and an air outlet end of the ignition air pipeline is connected to the ignition burner; an ignition gas pipeline, wherein an air inlet end of the ignition gas pipeline is connected to a high calorific value gas supply source, and an air outlet end of the ignition gas pipeline is connected to the ignition burner; A main air pipeline, the air inlet end of the main air pipeline is connected to the blower, and the air outlet end of the main air pipeline is connected to the main burner; an air damper with an adjustable opening is provided in the main air pipeline; a low calorific value gas pipeline, wherein the gas inlet end of the low calorific value gas pipeline is connected to the low calorific value gas supply source, and the gas outlet end of the low calorific value gas pipeline is connected to the main burner; a low calorific value gas flow regulating valve is provided on the low calorific value gas pipeline; A high calorific value gas pipeline, wherein the gas inlet end of the high calorific value gas pipeline is connected to the high calorific value gas supply source, and the gas outlet end of the high calorific value gas pipeline is connected to the main burner; a high calorific value gas flow regulating valve is provided on the high calorific value gas pipeline; a control unit, the low calorific value gas flow regulating valve and the high calorific value gas flow regulating valve being electrically connected to the control unit; when the gas pressure of the low calorific value gas does not reach the required lower pressure limit, the high calorific value fuel is burned alone; when the gas pressure of the low calorific value gas reaches the required lower pressure limit, the low calorific value gas and the high calorific value gas are burned together; The main burner is divided into an air chamber, a high calorific value gas chamber, a low calorific value gas chamber and a premixing chamber, wherein the air chamber and the premixing chamber are both connected to the main air pipeline, the high calorific value gas chamber is connected to the high calorific value gas pipeline, and the low calorific value gas chamber is connected to the low calorific value gas pipeline and is connected to the premixing chamber; the ignition burner is inserted in the air chamber, and the bottom of the air chamber is provided with a through hole for the ignition burner to pass through and a plurality of air holes for air to pass through; the high calorific value gas chamber is sleeved on the air chamber On the outside, the low calorific value gas chamber and the premixing chamber are both sleeved on the outside of the high calorific value gas chamber; the low calorific value gas chamber extends into the premixing chamber and is provided with a plurality of low calorific value gas holes connected to the premixing chamber; the bottom of the premixing chamber is provided with a plurality of injection pipes connected to the premixing chamber at intervals along its circumference, and the outer wall of the high calorific value gas chamber is provided with a plurality of high calorific value gas nozzles connected to the high calorific value gas chamber along its circumference, and the high calorific value gas nozzles are respectively inserted into the corresponding injection pipes and a gap is left between the two for the mixed gas to pass through.

2. A boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 1, characterized in that: The low calorific value gas pipeline is provided with a low calorific value gas pressure transmitter A, a low calorific value gas pressure switch A, a low calorific value gas pressure gauge, the low calorific value gas flow regulating valve, the low calorific value gas stop valve A, the low calorific value gas stop valve B, the low calorific value gas throttling orifice plate, the low calorific value gas pressure switch B and the low calorific value gas ball valve in sequence along the gas flow direction; the low calorific value gas pressure transmitter A is electrically connected to the control unit.

3. The boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 2, characterized in that: A low calorific value gas pressure transmitter B is connected between the gas inlet end and the gas outlet end of the low calorific value gas throttling orifice plate, and the low calorific value gas pressure transmitter B is electrically connected to the control unit.

4. The boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 1, characterized in that: The high calorific value gas pipeline is provided with a high calorific value gas pressure switch A, a high calorific value gas pressure gauge, a high calorific value gas pressure stabilizing valve, the high calorific value gas flow regulating valve, a high calorific value gas stop valve A, a high calorific value gas stop valve B, a high calorific value gas throttling orifice plate, a high calorific value gas pressure switch B and a high calorific value gas ball valve in sequence along the gas flow direction.

5. The boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 4, characterized in that: The air inlet end of the ignition gas pipeline is connected between the high calorific value gas pressure switch A and the high calorific value gas pressure gauge.

6. A boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 5, characterized in that: The ignition gas pipeline is provided with an ignition gas stop valve A, an ignition gas pressure-stabilizing valve, an ignition gas stop valve B, an ignition gas throttling orifice plate, and an ignition gas ball valve in sequence along the gas flow direction.

7. The boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 1, characterized in that: An air ball valve and an air throttling orifice plate are sequentially arranged on the ignition air pipeline along the air flow direction thereof.

8. The boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 1, characterized in that: The flue gas outlet of the boiler body is equipped with a flue gas oxygen content transmitter; the blower is provided with a frequency converter; the flue gas oxygen content transmitter and the frequency converter are both electrically connected to the control unit.

9. The boiler system for mixed combustion of low calorific value gas and high calorific value gas according to claim 1, characterized in that: The inner wall of the high calorific value gas cavity is provided with a plurality of high calorific value gas holes spaced apart along its circumference, and the high calorific value gas holes are located on the gas outlet side of the air hole.

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