Anti-flashback multi-nozzle burner and waste gas treatment method

Abstract

The present invention discloses an anti-flashback multi-nozzle burner and an exhaust gas treatment method. The burner described in the present invention includes a burner body, the burner body includes a heat exchange chamber, the bottom of the burner body is provided with a first pipe for introducing exhaust gas, a second pipe for introducing fuel gas, and a third pipe for introducing combustion-supporting air; the first pipe is connected to a plurality of exhaust gas branch pipes, the exhaust gas branch pipes extend upward to the top of the burner body, and the exhaust gas outlet of the exhaust gas branch pipes is provided with an exhaust gas burner nozzle; the second pipe is connected to a plurality of fuel gas branch pipes, the fuel gas branch pipes extend upward to the top of the burner body, and the fuel gas outlet of the fuel gas branch pipes is provided with a burner nozzle; the top of the burner body is provided with a combustion-supporting air outlet for the delivery of combustion-supporting air. The burner of the present invention ensures that the temperature of the flame is not transmitted to the exhaust gas, no backfire occurs, and the exhaust gas pipeline is not ignited.

Description

Technical Field

[0001] The invention relates to the field of petrochemical waste gas purification, and in particular to an anti-flashback multi-burner burner and a waste gas treatment method. Background Art

[0002] The burner is a key part of the gas / waste gas combustion device, and is commonly found in various combustion-related industrial equipment, such as direct-fired boilers, regenerative combustion devices, garbage incinerators and exhaust gas turbines. A burner with good performance can reasonably organize the mixing of fuel and oxidant (such as air) to achieve safe and stable combustion, and ensure sufficient combustion efficiency and pollutant emission standards. For some special petrochemical devices, it is also necessary to meet the needs of flexible adjustment of flame length, combustion ignition temperature, heating temperature and heat load. According to the mixing method of gas fuel and air, it can be divided into three categories, namely diffusion combustion, partial premixed combustion and complete premixed combustion. According to the air supply method, it can be divided into several categories such as induced burner, blast burner and natural induced draft burner. According to the calorific value of gas, it can be divided into low calorific value burner and high calorific value burner. According to the location where gas and air are mixed, it can be divided into external mixing burner and internal mixing burner. According to the flue gas outlet velocity of the fire channel, it can be divided into low-speed burner and high-speed burner. The nozzle flow rate of the low-speed burner is lower than 50m / s; the nozzle flow rate of the high-speed burner is higher than 50m / s, generally 200-300m / s.

[0003] The fully premixed burner mixes the gas and air in advance before entering the combustion chamber. The gas and air are mixed evenly, which makes the combustion better and smoother. There is less incomplete combustion, because the pressure used for combustion is low, and low-pressure fans are not needed or required to assist combustion. The fully premixed burner is prone to flashback when the flow rate is low, so strict requirements are placed on the calorific value and density of the gas before design, and the adjustment is relatively small, and anti-flashback devices are installed; the heat load of a single burner is small; the noise is large, especially when operating at high pressure and high load, which is more obvious.

[0004] Partial premix burners mix part of the air (20%-80% of primary air) before combustion. A part of the mixed combustion-air mixture burns directly after leaving the burner, while the rest of the gas burns by diffusion and mixing with the surrounding air. Partial premix burners are generally designed in the form of a single nozzle (such as a straight tube). When the combustion load is large, it is easy to misfire or flameout. The nozzle head can also be designed in the form of multiple fire holes, but it requires higher pressure.

[0005] In the diffusion combustion method, air and fuel are separated before combustion, and air is supplied during the combustion process. The fuel and air are mixed and burned at the contact surface. According to the air supply method, it can be divided into natural induced draft and forced blast. Natural induced draft is mostly used for civil purposes, with low nozzle injection speed and small investment. Forced blast combustion is mainly used in industrial applications. This burner contains a complex swirler structure and requires forced blast. The design and manufacturing costs are high, and the combustion effect is more stable.

[0006] The specific scope of use of the burner is the waste gas treatment in petrochemical enterprises. The waste gas contains some air, accounting for 0-98%. The combustible components in the waste gas are relatively small. This part of the waste gas is in the range of non-spontaneous combustion, combustible, and explosive. The combustion mode is diffusion combustion, partial premixed combustion, and full premixed combustion. When deflagration occurs, backfire is likely to occur, so a stable and safe combustion method is needed to reduce the occurrence of accidents.

[0007] Waste gas from petrochemical enterprises. The waste gas from petrochemical enterprises has complex components, with air accounting for 0-98% and other components accounting for 0.5-10%. The components are complex, and hydrogen, methane, ethane and diesel components may exist, and the explosion range of each component is different. Due to the complex components of the waste gas, the above-mentioned existing combustion methods have problems with imperfect combustion technology or combustion applicability. It is required to find a suitable burner that can be used safely within the explosion range. Therefore, it is of great significance to design a new type of burner with adjustable load, relatively low manufacturing cost, flexible and convenient operation, meeting environmental protection indicators, and adapting to a wide ratio for the development of industrial environmental protection equipment. Summary of the invention

[0008] Purpose of the invention: In order to solve the problems of the prior art, the present invention provides a multi-nozzle burner with anti-flashback, which ensures that the temperature of the flame is not transmitted to the exhaust gas, does not flash back, and the exhaust gas pipeline is not ignited. The present invention also provides a method for treating exhaust gas using the multi-nozzle burner with anti-flashback.

[0009] Technical solution: The anti-backfire multi-nozzle burner described in the present invention includes a burner body, the burner body includes a heat exchange chamber, and the bottom of the burner body is provided with a first pipe for introducing exhaust gas, a second pipe for introducing fuel gas, and a third pipe for introducing combustion-supporting air; the first pipe is connected to a plurality of exhaust gas branch pipes, and the exhaust gas branch pipes extend upward to the top of the burner body, and the exhaust gas outlet of the exhaust gas branch pipe is provided with an exhaust gas burner nozzle; the second pipe is connected to a plurality of fuel gas branch pipes, and the fuel gas branch pipes extend upward to the top of the burner body, and the fuel gas outlet of the fuel gas branch pipe is provided with a burner nozzle; the top of the burner body is provided with a combustion-supporting air outlet for delivering combustion-supporting air.

[0010] As a preferred structure of the present invention, the fuel gas branch pipes are distributed between the exhaust gas branch pipes at intervals.

[0011] As a preferred structure of the present invention, the first pipe is coiled at the bottom of the burner body to form an exhaust gas pipe bundle, and the exhaust gas pipe bundle is connected to each exhaust gas branch pipe.

[0012] As a preferred structure of the present invention, the second pipeline is coiled at the bottom of the burner body to form a fuel gas pipe bundle, and the fuel gas pipe bundle is connected to each fuel gas branch pipe.

[0013] As a preferred structure of the present invention, the third pipeline is a cylindrical structure.

[0014] As a preferred structure of the present invention, the fuel gas pipe bundle is arranged above the exhaust gas pipe bundle.

[0015] As a preferred structure of the present invention, the burner nozzle includes a multi-hole nozzle and an automatic ignition device.

[0016] As a preferred structure of the present invention, the exhaust gas burner includes a venturi tube and a flame arrester arranged at the top of the exhaust gas burner.

[0017] The method for treating waste gas by using the anti-flashback multi-nozzle burner of the present invention comprises the following steps:

[0018] (S1) When the device is started, the combustion air first enters the burner body to purge the equipment for 5-10 minutes;

[0019] (S2) After the purge is completed, the igniter is ignited, the fuel gas pipeline enters the burner and the fuel gas is put into the burner, and the fuel gas is ignited; if the fuel gas cannot be ignited, the fuel gas is turned off and the device is restarted;

[0020] (S3) After the fuel gas is ignited, the furnace heating speed is adjusted. When the temperature in the furnace rises to above 650°C, waste gas is added. The waste gas enters the top outlet of the burner from the waste gas channel and is ignited by the high temperature.

[0021] Beneficial effects: (1) The present invention, through the setting of the main structure of the burner, exchanges heat between the exhaust gas and the combustion-supporting air, and the cold combustion-supporting air cools the exhaust gas. There are multiple venturi tube bundles at the exhaust gas end, the heat exchange area is increased, and the exhaust gas temperature is reduced more thoroughly than conventional fuel gas. The exhaust gas temperature is lower than the ignition point, and the burner has flame-retardant and flame-retardant functions. (2) The burner of the present invention ensures the safety of exhaust gas combustion, and through the exhaust gas flow rate and the low temperature control of the exhaust gas and the increase of the flame-retardant performance, it ensures that the temperature of the flame is not transmitted to the exhaust gas, no backfire occurs, and the exhaust gas pipeline is not ignited. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the anti-flashback multi-nozzle burner of the present invention;

[0023] Figure 2 This is a schematic diagram of the exhaust gas burner distribution of the present invention;

[0024] Figure 3 It is a schematic diagram of the distribution of the burner nozzles of the fuel gas of the present invention;

[0025] Figure 4 It is a schematic diagram of the exhaust gas burner and the Venturi structure in the burner nozzle of the present invention. DETAILED DESCRIPTION

[0026] Example 1: Figure 1 As shown, a backfire-proof multi-nozzle burner of the present invention, the medium of the burner described in the present invention is fuel gas, exhaust gas and air, and the burner is a combination of three-medium combustion and combustion-supporting. The burner includes a burner body 1, and the burner body 1 includes a heat exchange chamber 100. The bottom of the burner body 1 is provided with a first pipe 2 for introducing exhaust gas, a second pipe 3 for introducing fuel gas, and a third pipe 4 for introducing combustion-supporting air. In this embodiment, the third pipe 4 is a cylindrical structure, and the top of the burner body 1 is provided with a combustion-supporting air outlet 401 for the combustion-supporting air to be sent out. The pipeline material of the present invention is divided into multiple types, among which the material of fuel gas and exhaust gas is stainless steel and ultra-high temperature resistant material; the material of the combustion-supporting air path is stainless steel or carbon steel. The material of the furnace body of the burner body is carbon steel; the material of the branch pipeline is stainless steel.

[0027] The first pipe 2 is connected to a plurality of exhaust branch pipes 201, which extend upward to the top of the burner body 1. The top of the exhaust branch pipe 201 is an exhaust outlet 202, and an exhaust burner 203 is provided at the exhaust outlet 202 of the exhaust branch pipe 201. The first pipe 2 is wound at the bottom of the burner body 1 to form an exhaust pipe bundle 204, and the exhaust pipe bundle 204 is connected to each exhaust branch pipe 201. The entrance of the first pipe 2 is an exhaust inlet 205. Figure 4 As shown, the exhaust gas burner 203 includes a venturi tube 5 and a flame arrester 206 disposed at the top of the exhaust gas burner 203 , and an exhaust gas flow channel 207 is between the venturi tube 5 and the flame arrester 206 .

[0028] The second pipeline 3 of the present invention is connected to a plurality of fuel gas branch pipes 301, which extend upward to the top of the burner body 1. A multi-hole nozzle 305 is provided at the fuel gas outlet 302 of the fuel gas branch pipe 301. The multi-hole nozzle 305 is provided at the top of the burner nozzle 303. The multi-hole nozzle 305 is in an umbrella-shaped structure, and a plurality of combustion holes for gas ejection are provided around the umbrella-shaped structure. The second pipeline 3 is coiled at the bottom of the burner body 1 to form a fuel gas pipe bundle 304, and is connected to each fuel gas branch pipe 301 through the fuel gas pipe bundle 304. In addition to the porous nozzle 305, the gas end of the fuel gas branch pipe 301 also includes a conventional automatic ignition device (not shown in the figure). The porous structure is located at the gas outlet section of the fuel gas branch pipe 301, and the ignition device is located next to the porous structure nozzle. The burner nozzle 203 has a porous nozzle with an automatic ignition function. The fuel gas passes through the Venturi structure 5 located on the fuel gas branch pipe 301, enters the fuel gas flow channel 306, and then enters the porous nozzle 305 to be automatically ignited.

[0029] As a preferred structure of the present embodiment, the fuel gas branch pipe 301 is spaced apart from the exhaust gas branch pipe 201, and the third pipe 4 for delivering combustion-supporting wind (air) of the present invention is a straight cylindrical structure. The present invention realizes heat exchange between the air end and the exhaust gas and the fuel gas through the pipeline arrangement of the fuel gas, the combustion-supporting gas and the exhaust gas, and balances the heat of the three routes. Because the flow rate of the exhaust gas is greater than the flashback combustion speed of the flame, the burner has an anti-flashback function. The exhaust gas exchanges heat with the combustion-supporting air, and the cold combustion-supporting air cools down the exhaust gas. The multiple venturi tube bundles at the exhaust gas end increase the heat exchange area, and the exhaust gas temperature is reduced more thoroughly than that of conventional fuel gas. The exhaust gas temperature is lower than the ignition point, and the burner has flame-blocking and flame-retardant functions.

[0030] As a preferred structure of the present invention, the combustion disk of the exhaust gas is located above the venturi tube bundle. The combustion disk is formed by winding a variety of metal plates. The gaps between the metal plates are very small, and the flow rate of the exhaust gas therein is also relatively fast; the channel area between the metal plates is large, which strengthens the heat transfer, reduces the flame temperature to below the ignition point, and prevents the flame from spreading to the fuel gas, playing a role in fire prevention and backfire prevention. The combustion disk of the exhaust gas has a certain thickness. The two sides of the channel between the metal plates are called channel walls. The thicker the thickness of the combustion disk. Combustion and explosion are not direct reactions between molecules, but are stimulated by external energy. The molecular bonds are destroyed and activated molecules are generated. The activated molecules are split into short-lived but very active free radicals. The free radicals collide with other molecules to generate new products. At the same time, new free radicals are also generated to continue to react with other molecules. When the burning combustible gas passes through the narrow and long channel of the fire-blocking element, the probability of collision between the free radicals and the channel wall increases, and the number of free radicals participating in the reaction decreases. When the channel of the flame arrester is narrow to a certain extent, the collision between the free radicals and the channel wall dominates. Due to the sharp decrease in the number of free radicals, the reaction cannot continue, that is, the combustion reaction cannot continue to propagate through the combustion disk, thus playing a role of flame arrester.

[0031] In the burner of the present invention, the exhaust gas section burns at a high speed, the normal flow rate is greater than 50 m / s, and the minimum flow rate is 15 m / s. The flow rate of the exhaust gas outlet end of the first pipeline 2 entering the venturi throat is greater than 15 m / s, and the venturi tube bundle has an automatic control adjustment function to adjust the number of exhaust gas branch pipes 201 passing the exhaust gas under the condition of 5-110% of the flow rate, ensuring that the flow rate in the venturi throat of the exhaust gas meets the flow rate requirement of greater than 15 m / s.

[0032] The specific implementation method of the burner of the present invention is as follows: when the device is started, the combustion-supporting air first enters the device to purge the device, and the purge time is 5-10 minutes. After the purge is completed, the igniter is ignited, the fuel gas pipeline enters the burner and the fuel gas is put in, and the fuel gas is ignited; if the fuel gas cannot be ignited, the fuel gas is turned off and the device is restarted; after the fuel gas is ignited, the furnace heating speed is adjusted, and when the temperature in the furnace rises to above 650°C, the exhaust gas is put in, and the exhaust gas enters the top outlet of the burner from the exhaust gas channel. The exhaust gas is ignited at high temperature. Due to the fast flow rate of the exhaust gas, the entire combustion furnace will have a flame with a longer length. Because the speed of the combustion-supporting air is slow, a speed difference is formed with the flow rates of the exhaust gas and the fuel gas, and the gas flow state of this furnace will form turbulence, which increases the degree of ignition and the efficiency of combustion.

[0033] Effect: The temperature of the combustion chamber of the present invention is controlled at 760-820℃, and the non-methane total hydrocarbon is controlled at ≯20mg / m 3 , NOx content control ≯50mg / m 3 The above content indicators are calculated based on the 3% oxygen content in GB31570 and GB31571 standards.

[0034] After combustion, the removal rate of non-methane total hydrocarbons of the present invention is above 99%, meeting the requirements of national standards GB31570 and GB31571.

[0035] The system of the present invention is distributed into a symmetrical structure by adjusting the composition of fuel gas, exhaust gas and combustion-supporting air, flow pattern layout, flow velocity design, hardware composition, and venturi devices arranged at the outlet ends of fuel gas and exhaust gas, such as Figure 2 and Figure 3 As shown, the fuel gas: exhaust gas bundle ratio is 1:6-20; the exhaust gas enters the combustion chamber through the flame arrester to ensure that the temperature of the flame is not transferred to the exhaust gas, no backfire occurs, and the exhaust gas pipeline is not ignited

[0036] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A flashback-proof multi-nozzle burner, characterized in that: The burner body (1) comprises a burner main body (1), the burner main body (1) comprises a heat exchange chamber (100), the bottom of the burner main body (1) is provided with a first pipe (2) for introducing exhaust gas, a second pipe (3) for introducing fuel gas, and a third pipe (4) for introducing combustion-supporting air; the first pipe (2) is connected to a plurality of exhaust gas branch pipes (201), the exhaust gas branch pipes (201) extend upward to the top of the burner main body (1), and an exhaust gas burner (203) is provided at the exhaust gas outlet (202) of the exhaust gas branch pipe (201); the second pipe (3) is connected to a plurality of fuel gas branch pipes (301), the fuel gas branch pipes (301) extend upward to the top of the burner main body (1), and a burner nozzle (303) is provided at the fuel gas outlet (302) of the fuel gas branch pipe (301); the top of the burner main body (1) is provided with a combustion-supporting air outlet (401) for sending out combustion-supporting air; The fuel gas branch pipes (301) are distributed at intervals between the exhaust gas branch pipes (201); the third pipeline (4) is a cylindrical structure; The exhaust gas burner (203) comprises a venturi tube and a flame arrester (206) arranged at the top of the exhaust gas burner (203); The heat exchange chamber (100) is in communication with the third pipeline (4).

2. The anti-flashback multi-nozzle burner according to claim 1, characterized in that: The first pipe (2) is coiled at the bottom of the burner body (1) to form an exhaust gas pipe bundle (204), and the exhaust gas pipe bundle (204) is connected to each of the exhaust gas branch pipes (201).

3. The anti-flashback multi-nozzle burner according to claim 2, characterized in that: The second pipeline (3) is coiled at the bottom of the burner body (1) to form a fuel gas pipe bundle (304), and the fuel gas pipe bundle (204) is connected to each of the fuel gas branch pipes (301).

4. The anti-flashback multi-nozzle burner according to claim 3, characterized in that: The fuel gas pipe bundle (304) is arranged above the exhaust gas pipe bundle (204).

5. The anti-flashback multi-nozzle burner according to claim 1, characterized in that: The burner nozzle (303) comprises a multi-hole nozzle (305) and an automatic ignition device.

6. A method for treating waste gas using the anti-flashback multi-nozzle burner according to claim 3, characterized in that: The following steps are involved: (S1) When the device is started, the combustion air first enters the burner body to purge the equipment for 5-10 minutes; (S2) After the purge is completed, the igniter is ignited, the fuel gas pipeline enters the burner and the fuel gas is put in, and the fuel gas is ignited; if the fuel gas cannot be ignited, the fuel gas is turned off and the equipment is restarted; (S3) After the fuel gas is ignited, the furnace heating speed is adjusted. When the temperature in the furnace rises to above 650°C, waste gas is added. The waste gas enters the top outlet of the burner from the waste gas channel and is ignited by the high temperature.

7. The method for treating exhaust gas using an anti-flashback multi-nozzle burner according to claim 6, characterized in that: The flow velocity of the exhaust gas from the outlet end of the first pipe (2) entering the venturi tube is greater than 15 m / s.

8. The method for treating exhaust gas using an anti-flashback multi-nozzle burner according to claim 6, characterized in that: The ratio of the fuel gas bundle to the exhaust gas bundle is 1:6~20.

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