Low-nitrogen combustion cyclohexanone heat-conducting oil furnace

Abstract

A low-nitrogen combustion cyclohexanone heat-conducting oil furnace comprises a heat-conducting oil furnace body, a heat exchange coil pipe is arranged in the heat-conducting oil furnace body, a fuel feeding pipe is connected to the bottom of the heat-conducting oil furnace body, a combustor is arranged at the connecting position of the fuel feeding pipe and the heat-conducting oil furnace body and further connected with a gas inlet pipe, and a smoke exhaust pipe is arranged at the top of the heat-conducting oil furnace body. And a gas return pipe is connected between the smoke exhaust pipe and the combustor. According to the low-nitrogen combustion cyclohexanone heat conduction oil furnace, the air return pipe is additionally arranged, a large amount of high-temperature flue gas is sucked according to the low-pressure injection principle generated by high-speed flowing air and then is fully mixed with combustion fuel to form oxygen-deficient combustion, the combustion temperature is reduced by reducing the oxygen content in the combustion air, and the combustion efficiency is improved. Therefore, the generation of nitrogen oxides is reduced.

Description

Technical Field

[0001] This utility model relates to the field of cyclohexanone production technology, and in particular to a low-NOx combustion cyclohexanone thermal oil furnace. Background Technology

[0002] Cyclohexanone is one of the important organic chemical raw materials for the production of caprolactam. In the production process of cyclohexanone, the global industry generally adopts the cyclohexane oxidation method and the partial hydrogenation cyclohexene hydration method. In some cases, the partial hydrogenation cyclohexene hydration method is even used in conjunction with the cyclohexane oxidation method to enhance market competitiveness. However, regardless of whether the cyclohexane oxidation method or the partial hydrogenation cyclohexene hydration method is used, the final product, cyclohexanol or a byproduct of cyclohexanol, must undergo a cyclohexanol dehydrogenation reaction to convert it into cyclohexanone. Since cyclohexanol dehydrogenation is an endothermic reaction, temperature fluctuations and amplitudes in the fixed-bed catalytic reaction processes used domestically and internationally have a significant impact on the service life of the dehydrogenation catalyst. Therefore, the industry commonly uses heat transfer oil as the heat medium to heat the fixed-bed catalyst.

[0003] Domestic thermal oil heaters generally have high nitrogen oxide emissions due to their early design or construction. With the country's increasing environmental emission requirements and the crackdown on seasonal heavy pollution emissions, reducing nitrogen oxide emissions from thermal oil heater combustion is becoming increasingly urgent. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide a cyclohexanone thermal oil furnace with low nitrogen combustion, thereby reducing the content of nitrogen oxides in the flue gas emitted after combustion of the thermal oil furnace.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a low-NOx combustion cyclohexanone thermal oil furnace, including a thermal oil furnace, a heat exchange coil provided inside the thermal oil furnace, a fuel feed pipe connected to the bottom of the thermal oil furnace, a burner provided at the connection between the fuel feed pipe and the thermal oil furnace, the burner also being connected to an air inlet pipe, an exhaust pipe provided at the top of the thermal oil furnace, and a return gas pipe connected between the exhaust pipe and the burner.

[0006] Preferably, the exhaust pipe is equipped with a flue gas heat exchanger, and the intake pipe is connected to the flue gas heat exchanger and then to the burner.

[0007] Preferably, the air intake pipe is equipped with a fan.

[0008] Preferably, the fuel feed pipe is connected to the thermal oil furnace through two feed branches, and a burner is installed at the end of one of the feed branches.

[0009] Preferably, the two ends of the heat exchange coil are connected to the circulating heat transfer oil inlet pipe and the circulating heat transfer oil outlet pipe, respectively.

[0010] Preferably, the fuel feed pipe is equipped with a first flow monitor, a first pressure monitor, and a second regulating valve; the air inlet pipe is equipped with a first regulating valve, a second flow monitor, and a second pressure monitor; the exhaust pipe is equipped with a flue gas monitor and a second temperature monitor; the return gas pipe is equipped with a third regulating valve and a fourth pressure monitor; and the thermal oil furnace is equipped with a third pressure monitor and a first temperature detector. The first flow monitor, the first pressure monitor, the second regulating valve, the second flow monitor, the second pressure monitor, the flue gas monitor, the second temperature monitor, the third regulating valve, and the fourth pressure monitor are all electrically connected to the controller.

[0011] Preferably, a third flow monitor and a third temperature monitor are provided on the circulating heat transfer oil inlet pipe, and a fourth temperature monitor is provided on the circulating heat transfer oil outlet pipe; the third flow monitor, the third temperature monitor and the fourth temperature monitor are electrically connected to the controller.

[0012] This invention provides a low-NOx combustion cyclohexanone thermal oil furnace, which adds a return gas pipe and uses the low-pressure ejection principle generated by high-speed air flow to draw in a large amount of high-temperature flue gas, which is then fully mixed with the combustion fuel to form oxygen-deficient combustion. By reducing the oxygen content in the combustion air, the combustion temperature is lowered, thereby reducing the generation of nitrogen oxides. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0014] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0015] like Figure 1 As shown, a low-NOx combustion cyclohexanone thermal oil furnace includes a thermal oil furnace 2, a heat exchange coil 3 inside the thermal oil furnace 2, a fuel feed pipe A connected to the bottom of the thermal oil furnace 2, a burner 4 located at the connection point between the fuel feed pipe A and the thermal oil furnace 2, and the burner 4 is also connected to an air inlet pipe B. An exhaust pipe C is located at the top of the thermal oil furnace 2, and a return gas pipe 24 connects the exhaust pipe C and the burner 4. After the high-temperature flue gas mixes with fuel and air, the oxygen concentration in the combustion zone is reduced, creating an oxygen-deficient combustion environment. Simultaneously, the combustion temperature is lowered, fundamentally inhibiting the formation of thermal nitrogen oxides (NOx), significantly reducing NOx emissions in the flue gas, and meeting environmental protection requirements.

[0016] Preferably, the exhaust pipe C is equipped with a flue gas heat exchanger 5, and the intake pipe B is connected to the flue gas heat exchanger 5 and then to the burner 4.

[0017] Preferably, the air intake pipe B is equipped with a fan 1.

[0018] Preferably, the fuel feed pipe A is connected to the thermal oil furnace 2 via two feed branch pipes, and a burner 4 is installed at the end of one of the feed branch pipes. The multi-branch pipe design allows the fuel to be distributed more evenly in the combustion zone, avoiding high-temperature hot spots caused by local fuel concentration and reducing nitrogen oxides generated by local high temperatures; at the same time, it optimizes the combustion space distribution, improves fuel utilization and the heating uniformity of the thermal oil furnace.

[0019] Preferably, the two ends of the heat exchange coil 3 are connected to the circulating heat transfer oil inlet pipe D and the circulating heat transfer oil outlet pipe E, respectively.

[0020] Preferably, the fuel feed pipe A is equipped with a first flow monitor 11, a first pressure monitor 12 and a second regulating valve 7; the air inlet pipe B is equipped with a first regulating valve 6, a second flow monitor 13 and a second pressure monitor 14; the exhaust pipe C is equipped with a flue gas monitor 19 and a second temperature monitor 18; the return gas pipe 24 is equipped with a third regulating valve 8 and a fourth pressure monitor 17; and the thermal oil furnace 2 is equipped with a third pressure monitor 15 and a first temperature detector 16. The first flow monitor 11, the first pressure monitor 12, the second regulating valve 7, the first regulating valve 6, the second flow monitor 13, the second pressure monitor 14, the flue gas monitor 19, the second temperature monitor 18, the third regulating valve 8 and the fourth pressure monitor 17 are all electrically connected to the controller 23.

[0021] Preferably, a third flow monitor 20 and a third temperature monitor 21 are provided on the circulating heat transfer oil inlet pipe D, and a fourth temperature monitor 22 is provided on the circulating heat transfer oil outlet pipe E; the third flow monitor 20, the third temperature monitor 21 and the fourth temperature monitor 22 are electrically connected to the controller 23.

[0022] This invention utilizes a return gas pipe installed between the exhaust pipe and the burner, employing the low-pressure ejection principle of high-speed airflow to guide high-temperature flue gas back to the combustion zone. This gas mixes with fuel and air to create an oxygen-deficient combustion environment, reducing combustion temperature and oxygen concentration, thereby inhibiting nitrogen oxide formation. Simultaneously, it incorporates a flue gas heat exchanger to recover waste heat, a fan to ensure airflow power, and multiple branch pipes to optimize fuel distribution. Furthermore, an intelligent monitoring and control system integrating flow, pressure, and temperature monitors and regulating valves enables precise control of the combustion process. This solves the problem of high nitrogen oxide emissions from traditional thermal oil furnaces, offering advantages such as low nitrogen emissions, environmental friendliness, high efficiency and energy saving, and stable heating. It is suitable for supplying heat to the cyclohexanol dehydrogenation reaction in cyclohexanone production, meeting environmental requirements and improving process stability.

[0023] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A low-NOx combustion cyclohexanone thermal oil furnace, comprising a thermal oil furnace (2), a heat exchange coil (3) provided inside the thermal oil furnace (2), a fuel feed pipe (A) connected to the bottom of the thermal oil furnace (2), a burner (4) provided at the connection between the fuel feed pipe (A) and the thermal oil furnace (2), the burner (4) also being connected to an air inlet pipe (B), and an exhaust pipe (C) provided at the top of the thermal oil furnace (2), characterized in that: A return pipe (24) is connected between the exhaust pipe (C) and the burner (4).

2. The low-NOx combustion cyclohexanone thermal oil furnace according to claim 1, characterized in that: The exhaust pipe (C) is equipped with a flue gas heat exchanger (5), and the inlet pipe (B) is connected to the flue gas heat exchanger (5) and then to the burner (4).

3. A low-NOx combustion cyclohexanone thermal oil furnace according to claim 1 or 2, characterized in that: A fan (1) is installed on the air intake pipe (B).

4. The low-NOx combustion cyclohexanone thermal oil furnace according to claim 1, characterized in that: The fuel feed pipe (A) is connected to the thermal oil furnace (2) through two feed branches, and a burner (4) is installed at the end of one of the feed branches.

5. The low-NOx combustion cyclohexanone thermal oil furnace according to claim 1, characterized in that: The two ends of the heat exchange coil (3) are connected to the circulating heat transfer oil inlet pipe (D) and the circulating heat transfer oil outlet pipe (E), respectively.

6. The low-NOx combustion cyclohexanone thermal oil furnace according to claim 1, characterized in that: A first flow monitor (11), a first pressure monitor (12), and a second regulating valve (7) are provided on the fuel feed pipe (A). A first regulating valve (6), a second flow monitor (13), and a second pressure monitor (14) are provided on the air inlet pipe (B). A flue gas monitor (19) and a second temperature monitor (18) are provided on the exhaust pipe (C). A third regulating valve (8) and a fourth pressure monitor (17) are provided on the return gas pipe (24). A third pressure monitor (15) and a first temperature detector (16) are provided inside the thermal oil furnace (2). The first flow monitor (11), the first pressure monitor (12), the second regulating valve (7), the first regulating valve (6), the second flow monitor (13), the second pressure monitor (14), the flue gas monitor (19), the second temperature monitor (18), the third regulating valve (8), and the fourth pressure monitor (17) are all electrically connected to the controller (23).

7. The low-NOx combustion cyclohexanone thermal oil furnace according to claim 5, characterized in that: The circulating heat transfer oil feed pipe (D) is equipped with a third flow monitor (20) and a third temperature monitor (21), and the circulating heat transfer oil discharge pipe (E) is equipped with a fourth temperature monitor (22); the third flow monitor (20), the third temperature monitor (21) and the fourth temperature monitor (22) are electrically connected to the controller (23).

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