Staged combustion method

Abstract

The invention discloses a staged combustion method, which is suitable for a VOCs (volatile organic compounds) tail gas treatment system, and comprises the following steps: introducing waste gas, fuel gas and air into a Venturi premixing cavity according to a set proportion for full premixing to form uniform combustible mixed gas; under the low-load condition, only the inner ring combustor is started to work, so that the combustion power and the energy consumption are reduced; under the condition of high load, the inner ring combustor and the outer ring combustor are started at the same time, so that the high-flow and high-concentration waste gas treatment requirements are met; besides, temperature, pressure and flow parameters of the combustion system are monitored in real time, fuel gas and air flow are automatically adjusted through a control algorithm, dynamic optimization of the combustion efficiency is achieved, compared with the prior art, fuel consumption can be greatly reduced, the energy-saving effect is achieved, meanwhile, the national environmental protection standard is met, and the method is worthy of popularization. And VOCs tail gas treatment is more efficient and economical, and wide market applicability is achieved.

Description

Technical Field

[0001] The invention relates to a staged combustion method. Background Art

[0002] In the current field of industrial waste gas treatment, especially in the VOCs oil and gas treatment industry, the requirements for waste gas emission control and energy conservation and emission reduction are becoming increasingly stringent. Metal surface combustion technology has gradually become one of the mainstream technologies for industrial waste gas treatment due to its efficient ultra-clean emission treatment effect. However, the traditional metal surface combustion process has the problems of high single-stage combustion power and high energy consumption, and cannot flexibly respond to the waste gas treatment needs under different load conditions. This limitation leads to energy waste, especially under low load conditions, the burner still needs to maintain high power output, thereby increasing the consumption of fuel gas.

[0004] Traditional combustion control methods usually respond to load changes by changing the operating frequency of the burner. However, this method is difficult to ensure combustion stability and treatment effects in a wide range of load fluctuations. At the same time, existing single-stage burners usually need to maintain a certain minimum combustion power to prevent flashback, further limiting the energy-saving potential of the burner at low loads.

[0005] Therefore, those skilled in the art are in urgent need of a staged combustion method that can not only effectively meet environmental protection requirements but also reduce energy consumption. Summary of the invention

[0006] The purpose of the present invention is to solve the above shortcomings of the prior art and provide a staged combustion method, which aims to improve the efficiency and economy of VOCs tail gas treatment, and solve the problems of excessive energy consumption during low-load operation and insufficient equipment load during high-load operation in the prior art by optimizing the mixing and combustion mode of fuel gas, exhaust gas and air in the combustion process. The following is a specific solution:

[0007] A staged combustion method comprises the following steps: introducing exhaust gas, fuel gas and air into a venturi premixing chamber, and fully premixing them to form a uniform combustible mixed gas; delivering the premixed combustible mixed gas to an inner ring burner or an outer ring burner, wherein under low load conditions, only the inner ring burner is enabled, and under high load conditions, the inner ring burner and the outer ring burner are enabled at the same time; and real-time monitoring and control of the temperature, pressure and flow parameters of the combustion system.

[0008] Furthermore, the step of introducing the exhaust gas, fuel gas and air into the venturi premixing chamber and fully premixing them to form a uniform combustible mixed gas includes: setting the exhaust gas flow rate Q w , set the fuel gas flow rate Q f , set the air flow rate Q a , the proportional relationship is determined based on the following formula, and Among them, k1 and k2 are proportional coefficients determined according to the exhaust gas concentration and premixing requirements. Compared with the existing technology, this formula allows the mixing ratio to be dynamically adjusted according to the changes in the exhaust gas instead of using a fixed ratio. This flexibility improves the system's adaptability to different exhaust gas components and makes combustion more efficient, thereby reducing exhaust emissions and fuel consumption.

[0009] Furthermore, the method of delivering the premixed combustible mixed gas to the inner ring burner or the outer ring burner further comprises the following steps: setting a minimum combustion power P for the inner ring burner min , the minimum combustion power is calculated based on the following formula, LHV is the lower heating value of the fuel gas, η is the efficiency of the inner ring burner, which can be adjusted by adjusting Q f value, maintain the combustion power at P min This formula introduces the low calorific value and combustion efficiency of fuel gas to make the calculation of the minimum combustion power more scientific, avoiding the flashback phenomenon caused by insufficient combustion power under low load conditions, thereby improving the safety and stability of the burner.

[0010] Furthermore, the method of activating only the inner ring burner under low load conditions and activating both the inner ring burner and the outer ring burner under high load conditions further comprises the following steps: setting a threshold value P threshold , used to distinguish between low load and high load states. According to actual needs, the actual combustion power P can be calculated by the following formula: actual , P actual =Q f ·LHV·η burning , where Q f is the fuel gas flow rate, LHV is the lower heating value of the fuel gas, η burning is the combustion efficiency, if P actual <P threshold , the inner ring burner is enabled, if P actual ≥P threshold The inner and outer ring burners are enabled; this judgment formula enables the working state of the burner to be dynamically adjusted according to the actual exhaust gas treatment needs, avoiding unnecessary energy consumption in traditional methods, while ensuring that the combustion capacity of the equipment can be fully utilized at high loads.

[0011] Furthermore, under high load conditions, the exhaust gas volume Q is monitored in the step where the inner ring burner and the outer ring burner are activated simultaneously. w and exhaust gas concentration C w , and adjust the fuel gas flow rate Q in real time according to the following formula f : This formula allows dynamic adjustment of the fuel gas flow rate based on real-time monitoring data to ensure effective combustion under high-concentration, high-flow exhaust gas conditions. This improvement not only improves the system's responsiveness to high-load conditions, but also reduces fuel consumption, meeting the requirements of energy-saving and emission standards.

[0012] Beneficial effects: It solves the problems of excessive energy consumption and insufficient equipment load in the existing technology in the process of treating VOCs exhaust gas; by dynamically adjusting the mixing ratio, minimum combustion power, flexible judgment of load status and real-time adjustment of fuel gas flow, it improves combustion efficiency, reduces energy consumption and achieves the environmental protection goal of ultra-clean emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic flow diagram of a staged combustion method. DETAILED DESCRIPTION

[0014] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0015] Please see Figure 1 A staged combustion method comprises the following steps: introducing exhaust gas, fuel gas and air into a Venturi premixing chamber, and fully premixing them to form a uniform combustible mixed gas; delivering the premixed combustible mixed gas to an inner ring burner or an outer ring burner, wherein under low load conditions, only the inner ring burner is enabled, and under high load conditions, the inner ring burner and the outer ring burner are enabled at the same time; and real-time monitoring and control of the temperature, pressure and flow parameters of the combustion system.

[0016] Introduce the exhaust gas, fuel gas and air into the Venturi premixing chamber and fully premix them to form a uniform combustible mixed gas, including: setting the exhaust gas flow rate Q w , set the fuel gas flow rate Q f , set the air flow rate Q a , the proportional relationship is determined based on the following formula, and Among them, k1 and k2 are proportional coefficients determined according to the exhaust gas concentration and premixing requirements.

[0017] The method of delivering the premixed combustible mixed gas to the inner ring burner or the outer ring burner further comprises the following steps: setting the minimum combustion power P for the inner ring burner min , the minimum combustion power is calculated based on the following formula, LHV is the lower heating value of the fuel gas, η is the efficiency of the inner ring burner, which can be adjusted by adjusting Q f value, maintain the combustion power at P min .

[0018] Under low load conditions, only the inner ring burner is enabled, and under high load conditions, the inner ring burner and the outer ring burner are enabled simultaneously. The further steps include: setting a threshold value P threshold , used to distinguish between low load and high load states. According to actual needs, the actual combustion power P can be calculated by the following formula: actual , P actual =Q f ·LHV·η burning , where Q f is the fuel gas flow rate, LHV is the lower heating value of the fuel gas, η burning is the combustion efficiency, if P actual <P threshold , the inner ring burner is enabled, if P actual ≥P threshold The inner and outer ring burners are activated.

[0019] Under high load conditions, the exhaust gas volume Q is monitored in steps where the inner ring burners are activated simultaneously with the outer ring burners. w and exhaust gas concentration C w , and adjust the fuel gas flow rate Q in real time according to the following formula f :

[0020]

[0021] In a specific embodiment, the exhaust gas, fuel gas and air are first introduced into the venturi premixing chamber at a preset flow rate for mixing to form a uniform combustible mixed gas. Then, staged combustion is achieved by connecting the flow meter and sensor to the control system to monitor the flow rate and temperature in real time; w Fuel gas Q f and Air Q a Introduce the Venturi premixing chamber; detect the exhaust gas flow rate is 50Nm3 / h, exhaust gas concentration is 1000ppm, according to the current exhaust gas conditions, judge: P actual =Q f ·LHV·η burning =10·35·0.85=297.5kW, compare P actual With the threshold value P threshold =100kW, find P actual >P threshold , so the inner and outer ring burners are enabled at the same time; the temperature Ta is monitored using a temperature sensor ctual , when T actual When the temperature is 750℃, calculate the temperature deviation:

[0022] e T =T set -T actual=800-750=50℃, adjust the fuel gas flow rate: Q f =Q f，base +K T ·e T In this example, we set K T =0.1, so Q f =10+0.1.50=15Nm 3 / h.

[0023] Through dynamic adjustment and optimized control, energy consumption can be reduced by more than 50%, and the concentration of waste gas after treatment is no more than 20mg / Nm 3 , in line with national environmental protection standards; through this embodiment, the actual application effect of the staged combustion device in treating VOCs tail gas can be fully demonstrated.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A staged combustion method, characterized in that: The following steps are involved: Exhaust gas, fuel gas and air are introduced into the Venturi premixing chamber and fully premixed to form a uniform combustible mixed gas; the premixed combustible mixed gas is transported to the inner ring burner or the outer ring burner, wherein, under low load conditions, only the inner ring burner is enabled, and under high load conditions, the inner ring burner and the outer ring burner are enabled at the same time; the temperature, pressure and flow parameters of the combustion system are monitored and controlled in real time.

2. A staged combustion method according to claim 1, characterized in that: The step of introducing the exhaust gas, fuel gas and air into the venturi premixing chamber and fully premixing them to form a uniform combustible mixed gas includes: setting the exhaust gas flow rate Q w , set the fuel gas flow rate Q f , set the air flow rate Q a , the proportional relationship is determined based on the following formula, and Among them, k1 and k2 are proportional coefficients determined according to the exhaust gas concentration and premixing requirements.

3. A staged combustion method according to claim 2, characterized in that: The method of delivering the premixed combustible mixed gas to the inner ring burner or the outer ring burner further comprises the following steps: setting a minimum combustion power P for the inner ring burner. min , the minimum combustion power is calculated based on the following formula, LHV is the lower heating value of the fuel gas, η is the efficiency of the inner ring burner, which can be adjusted by adjusting Q f value, maintain the combustion power at P min .

4. A staged combustion method according to claim 2, characterized in that: The method of only activating the inner ring burner under low load conditions and activating the inner ring burner and the outer ring burner at the same time under high load conditions further comprises the following steps: setting a threshold value P threshold , used to distinguish between low load and high load states. According to actual needs, the actual combustion power P can be calculated by the following formula: actual , P actual =Q f ·LHV·η burning , where Q f is the fuel gas flow rate, LHV is the lower heating value of the fuel gas, η burning is the combustion efficiency, if P actual <P threshold , the inner ring burner is enabled, if P actual ≥P threshold The inner and outer ring burners are activated.

5. A staged combustion method according to claim 1, characterized in that: Under high load conditions, the exhaust gas volume Q is monitored in steps where the inner ring burners are activated simultaneously with the outer ring burners. w and exhaust gas concentration C w , and adjust the fuel gas flow rate Q in real time according to the following formula f :

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