A method for calculating parameters of the exhaust gas inlet of a flue gas incinerator.

Abstract

This invention belongs to the field of tail gas incineration technology, specifically relating to a method for calculating parameters of the tail gas inlet of a tail gas incinerator. Specifically, to address the problems of existing incinerators failing to control tail gas and achieve complete combustion during operation, this invention, based on the principles of gas flow rate calculation, circumferential opening ratio calculation, and swirl intensity calculation, calculates the number and direction of tail gas inlets in each row, combined with incinerator parameters, to generate a rotating airflow, ensuring complete combustion of the tail gas within the incinerator. This invention achieves more complete tail gas reaction while maintaining flame stability, increasing fuel utilization and tail gas treatment efficiency. It also allows for a shorter furnace length while maintaining the same treatment efficiency, thereby saving costs and floor space.

Description

Technical Field

[0001] This invention belongs to the field of exhaust gas incineration technology, specifically relating to a method for calculating parameters of the exhaust gas inlet of an exhaust gas incinerator. Background Technology

[0002] A tail gas incinerator is a device that uses the heat generated by the combustion of auxiliary fuel to raise the temperature of harmful components in the tail gas of a natural gas absorption tower to the oxidation reaction temperature, thereby causing oxidation and decomposition. However, existing incinerators cannot completely and fully incinerate the tail gas generated during the production process, so improvements are needed.

[0003] Existing incinerators use nozzles in their exhaust gas injection systems, which are directly installed on the cylindrical furnace wall, perpendicular to the furnace wall and located in the upper half of the furnace. This arrangement has two drawbacks: First, the exhaust gas enters from the upper half of the furnace, resulting in an uneven and asymmetrical flow field. The high-temperature gas flow in the lower half of the furnace cannot fully participate in the reaction, leading to heat waste. Second, the exhaust gas flow, entering the furnace perpendicularly to the furnace wall, does not mix sufficiently with the high-temperature gases generated by fuel combustion. This results in insufficient heat gain from the gas mixture. Since oxidation reactions are temperature-sensitive, insufficient mixing leads to lower exhaust gas temperatures, resulting in slower oxidation rates and incomplete oxidation of harmful components.

[0004] Chinese utility model patent application CN208871646U discloses a tail gas incinerator for sulfur recovery. The incinerator body is divided into a pre-incineration zone and a post-incineration zone. Both the air input structure and the tail gas input structure of the tail gas incinerator include a gas gathering chamber arranged circumferentially around the furnace wall and a gas distribution channel arranged on the furnace wall. The gas distribution channel connects the gas gathering chamber with the inner cavity of the incinerator, thereby controlling the amount of NOx generated in the burner flue and effectively reducing the generation of carbon monoxide (CO), ultimately achieving effective treatment of tail gas. However, it does not play a good role in controlling the tail gas transported inside the incinerator, and the multi-stage air intake can easily lead to a decrease in the temperature inside the incinerator, making it impossible for the tail gas to burn completely during the operation of the incinerator. Therefore, it has great limitations.

[0005] Therefore, the existing exhaust gas incinerator intake method cannot meet the needs of actual use. Summary of the Invention

[0006] The purpose of this invention is to provide a method for calculating the parameters of the exhaust gas inlet of an exhaust gas incinerator, so as to solve the problems that existing incinerators cannot control the exhaust gas and cannot fully combust the exhaust gas during use.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for calculating the parameters of the exhaust gas inlet of an exhaust gas incinerator, the specific steps of which include:

[0008] 1) Based on the gas flow calculation principle and the circumferential opening ratio calculation formula, combined with the size of the incinerator, the size of the tail gas inlet and the flow velocity of the tail gas inlet, the total number of tail gas inlets distributed in the circumferential direction of the inner wall of the incinerator to meet the maximum tail gas flow requirement of the incinerator is calculated. Then, combined with the number of rows of tail gas inlets set in the circumferential direction of the inner wall of the incinerator, the number of tail gas inlets in each row is obtained.

[0009] 2) Based on the swirl intensity calculation formula, combined with the gas flow rate input to the incinerator in the axial direction, the size of the incinerator, the maximum value of the tail gas flow rate entering the incinerator, and the size of the tail gas inlet, the angle between the inlet direction of the tail gas inlet and the radius line of the incinerator cross-section is calculated. The inlet direction of the tail gas inlets in the same row is the same as the angle between the inlet direction of the incinerator cross-section, so that the tail gas enters in a clockwise or counterclockwise rotation in the radial direction of the inner wall of the incinerator.

[0010] 3) Based on the number of exhaust gas inlets in each row and the angle between the exhaust gas inlet direction and the radius of the incinerator cross-section, the exhaust gas inlets are designed to ensure that the exhaust gas is fully combusted in the incinerator.

[0011] Its beneficial effects are as follows: To solve the problem that existing incinerators cannot control the exhaust gas and cannot fully combust it during use, this invention calculates the number of exhaust gas inlets in each row and the direction of the exhaust gas inlets based on the principles of gas flow rate calculation, circumferential opening ratio calculation, and swirl intensity calculation, combined with the parameters of the incinerator. This ensures that the exhaust gas is fully combusted in the incinerator. This invention can make the exhaust gas reaction more complete while maintaining flame stability, increasing fuel utilization and exhaust gas treatment efficiency. It can also shorten the furnace length while maintaining the same treatment efficiency, thereby saving costs and floor space.

[0012] Furthermore, the exhaust gas inlets of two adjacent rows of rotating air intakes rotate in opposite directions.

[0013] Its beneficial effects are: the opposing rotation momentum of the exhaust gas inlets of each pair of rows cancels each other out, which helps the airflow to attenuate into a straight flow when leaving the incinerator, and is conducive to the full heat exchange of the downstream waste heat boiler.

[0014] Furthermore, the formula for calculating the total number of exhaust gas inlets is:

[0015]

[0016] Where N is the total number of exhaust gas inlets; Q is the maximum exhaust gas flow rate entering the incinerator; π is pi; D is the inner diameter of the incinerator; ε is the circumferential opening ratio; a is the radial length of the exhaust gas inlet along the incinerator; b is the axial length of the exhaust gas inlet along the incinerator; and v is the flow velocity of the exhaust gas inlet.

[0017] Furthermore, the formula for calculating the angle between the air intake direction of a certain exhaust gas inlet and the radius line of the incinerator cross-section is as follows:

[0018]

[0019] Where, θ i Let be the angle between the air intake direction of the i-th row of exhaust gas inlets and the radius line of the incinerator cross-section; N is the total number of exhaust gas inlets; Q is the maximum exhaust gas flow rate entering the incinerator; D is the inner diameter of the incinerator; N i is the number of exhaust gas inlets in the i-th row; k is the swirl intensity; b is the length of the exhaust gas inlet along the axial direction of the incinerator; (Q r +Q k Q represents the axial gas flow rate input to the incinerator. r Q represents the maximum axial flow rate of the incinerator. k This represents the maximum axial airflow rate of the incinerator.

[0020] Furthermore, in the axially input gas flow of the incinerator, the gas flow ratio between the air inlet and the gas inlet ranges from 2:1 to 40:1.

[0021] Furthermore, the gas flow ratio between the exhaust gas inlet and the fuel gas inlet of the incinerator ranges from 0:1 to 60:1. Attached Figure Description

[0022] Figure 1 This is an overall view of the exhaust gas incinerator of the present invention;

[0023] Figure 2 This is a front view of the exhaust gas incinerator of the present invention;

[0024] Figure 3 This is a top view of the exhaust gas incinerator of the present invention;

[0025] Figure 4 This is a cross-sectional view of the first exhaust gas inlet of the present invention, wherein the dashed arrow indicates the airflow direction;

[0026] Figure 5 This is a cross-sectional view of the second exhaust gas inlet of the present invention, wherein the dashed arrow indicates the airflow direction;

[0027] Figure 6 This is a three-dimensional perspective view of the burner head portion of the present invention;

[0028] Figure 7 These are a front view and a cross-sectional view of the sleeve-type air inlet of the tail gas incinerator of the present invention.

[0029] Figure 8 This is a partially enlarged view of the sleeve-type air inlet of the tail gas incinerator of the present invention.

[0030] Figure 9 This is a flowchart illustrating the parameter design of the exhaust gas inlet of the present invention.

[0031] Wherein: 1-Air duct; 2-Gas and exhaust gas inlet; 3-Distribution device; 4-Incinerator; 5-First exhaust gas inlet; 6-Second exhaust gas inlet; 7-Flame observation port; 8-Insulation layer; 9-Gas outlet. Detailed Implementation

[0032] The basic concept of this invention is as follows: To solve the problem that existing incinerators cannot control the exhaust gas and cannot fully combust it during use, this invention calculates the number of rows of exhaust gas inlets, the number of exhaust gas inlets in each row, and the angle of each exhaust gas inlet based on the size of the incinerator and the size of the exhaust gas inlet, combined with the air flow rate along the axial direction of the incinerator and the air flow rate at the exhaust gas inlet. This allows the exhaust gas to form a suitable rotating airflow in the incinerator, ensuring full combustion. Based on this concept, a method for calculating the parameters of the exhaust gas inlet of an exhaust gas incinerator can be implemented.

[0033] The present invention will now be described in detail with reference to the accompanying drawings and method embodiments.

[0034] Example of parameter calculation method for the exhaust gas inlet of a tail gas incinerator:

[0035] An overall view of a certain exhaust gas incinerator is shown below. Figure 1 As shown, the front view of the exhaust gas incinerator is as follows: Figure 2 As shown, the top view of the exhaust gas incinerator is as follows: Figure 3 As shown, the incinerator specifically includes: an air duct 1, a gas and exhaust gas coaxial inlet 2, a distribution device 3, an incineration furnace 4, a first exhaust gas inlet 5, a second exhaust gas inlet 6, a flame observation port 7, an insulation jacket 8, and a gas outlet 10.

[0036] The gas and exhaust gas inlet 2 is located in the center of the air duct 1 and is coaxially arranged with the air duct 1 at the head of the incinerator 4 (e.g., Figure 7 , Figure 8 As shown), it is used to inject fuel gas (mainly CH4) and air into the furnace head for combustion, in order to establish a high-temperature field inside the furnace.

[0037] The distribution device 3 is located in the middle section of the incinerator 4 and is used to set the exhaust gas inlet (in this embodiment, two rows of reverse tangential exhaust gas inlets are set), wherein the first row of exhaust gas inlets 5 are spaced at intervals along the circumference of the inner wall of the incinerator 4. One air inlet is set up, with a total of N1 inlets around the circumference (N1 is an integer between 2 and 36). Air is introduced tangentially in the direction forming an angle θ1 with the inner diameter radius of the incinerator furnace cross-section (θ1 ranges from 5° to 85°). Figure 4 As shown), the distance between the second row of exhaust gas inlets 6 and the first row of exhaust gas inlets 5 is between 0.5m and 5m, and the second row of exhaust gas inlets 6 are spaced at intervals along the circumference of the inner wall of the incinerator 4. One air inlet is set up, with a total of N2 inlets around the circumference (N2 is an integer between 2 and 36). The air is introduced tangentially in the direction forming an angle θ with the inner diameter radius line of the incinerator furnace cross-section 4 (θ2 ranges from 5° to 85°, e.g., ...). Figure 5 (As shown), but the direction of the tangential jet is opposite to that of the first exhaust gas inlet 5, forming a reverse tangential airflow; wherein, in order to solve the problem that the existing incinerator cannot control the exhaust gas and cannot make the exhaust gas fully combust during use, the present invention provides a method for calculating the parameters of the exhaust gas inlet of an exhaust gas incinerator, as follows: Figure 9 As shown, the specific steps include:

[0038] 1) Calculate the total number N of exhaust gas inlets installed in the incinerator;

[0039] The main design basis for the size of the exhaust gas inlet is to control the exhaust gas injection velocity. Based on the existing operating experience of exhaust gas incinerators, the flow velocity v at the exhaust gas inlet in the incinerator is generally in the range of 10m / s-50m / s, and 25m / s is commonly used. The size of the exhaust gas inlet is selected according to the size of the incinerator. If the axial length of the inlet is b and the width (circumferential length) is a, then the area of ​​each exhaust gas inlet is ab. Figure 6 As shown; circumferential opening ratio This refers to the proportion of the width of the exhaust gas inlet opening to the circumference of the inner wall of the incinerator; from the above, the total volumetric flow rate of gas passing through the exhaust gas inlet is:

[0040] Q = abvN = επDbvN

[0041] After rearranging the terms and reordering them, we get:

[0042]

[0043] Where N is the total number of exhaust gas inlets; Q is the maximum exhaust gas flow rate entering the incinerator; π is pi; and D is the diameter of the inner wall of the incinerator.

[0044] 2) Calculate the angles θ1 and θ2 between the air intake direction of the two exhaust gas inlets and the radius line of the cross-section of the incinerator;

[0045] Taking the first exhaust gas inlet as an example, its axial gas flow rate in the incinerator is the sum of the maximum gas flow rates of the fuel gas and air input into the incinerator (Q). r +Q k ), Q r Q represents the maximum axial flow rate of the incinerator. k Let be the maximum axial airflow rate of the incinerator; the axial characteristic dimension is the inlet length b; the total exhaust gas flow rate is Q; and there are N1 exhaust gas inlets in this exhaust gas flow rate. Then the total exhaust gas flow rate at all inlets in this exhaust gas flow rate is... The exhaust gas inlet flow rate is the total gas flow rate multiplied by the tangent of the included angle θ1, i.e. The characteristic dimension in the tangential direction is the radius of the inner diameter of the incinerator chamber. Therefore, the swirl intensity can be obtained (defined as: tangential flow rate multiplied by tangential characteristic length / axial flow rate multiplied by axial characteristic length):

[0046]

[0047] After rearranging the items, we can obtain

[0048]

[0049] Based on empirical data, the swirl intensity k ranges from 1 to 100, with 30 being a common value. The calculation method for the second exhaust gas inlet is the same as that for the first exhaust gas inlet, and will not be described in detail here.

[0050] To ensure more complete combustion of the exhaust gas and to fully utilize the residual heat at the incinerator outlet, the number of inlets in each row of exhaust gas inlets is set to be the same. Therefore, the formula can be simplified to:

[0051]

[0052]

[0053] Where n is the number of exhaust gas inlets per row; m is the number of rows; θ is the angle between the intake direction of any row of exhaust gas inlets and the radius of the cross-section of the incinerator; in this embodiment, two rows of exhaust gas inlets are provided, therefore:

[0054]

[0055]

[0056] A flame observation port 7 is installed on the outer side of the middle section of the incinerator 4 to observe the treatment of exhaust gas during combustion.

[0057] An insulation layer 8 is wrapped around the outside of the incinerator chamber 4 to prevent heat loss during combustion.

[0058] A gas outlet 9 is provided at the tail end of the incinerator 4 to discharge the burned gas from the incinerator.

[0059] In summary, after the incinerator is set up, the specific steps of its operation are as follows:

[0060] Step 1: At the inlet of the exhaust gas incinerator, air and fuel gas are introduced into the head of the furnace using a sleeve. The fuel gas and air undergo a combustion reaction, releasing heat and forming a high-temperature airflow, which provides heat and the necessary oxygen for the oxidation of the exhaust gas introduced into the middle and rear of the furnace.

[0061] Step two involves introducing exhaust gas into the incinerator through an exhaust gas injection device installed in the middle section of the incinerator. The first exhaust gas inlet uses a tangential air intake method to create a rotating airflow in the center of the furnace, enhancing the gas mixing effect and making the mixing between the airflow and the gas flame more complete. Downstream of the first exhaust gas inlet, at a certain distance, a second exhaust gas inlet is set up, which also uses the same tangential air intake method to create a rotating airflow in the center of the furnace, but in the opposite direction to the first exhaust gas inlet. The reverse impact of the airflow enhances the gas mixing effect, making the mixing between the airflow and the gas flame more complete and the combustion of the exhaust gas more thorough.

[0062] Step 3: Since the velocity and momentum of the two exhaust gas jets are basically the same, but the swirl direction is opposite, after the rotational momentum cancels out, the rotational momentum of the gas flow in the cylindrical furnace rapidly decays into a weak swirling flow, which is beneficial to improving the uniformity of the flow field when entering the waste heat boiler.

[0063] This invention is mainly applicable to various types of exhaust gas incinerators that purify exhaust gas through combustion. It can efficiently treat exhaust gas without premixing it with fuel gas, allowing it to react with oxygen at high temperatures to form harmless inorganic oxides. This effectively avoids the risk of leaks and explosions that may occur when exhaust gas is premixed with fuel gas. Adjusting the mixing ratio of exhaust gas and fuel gas according to the combustion conditions can improve fuel gas utilization efficiency. It can also shorten the furnace length while maintaining the same treatment efficiency, thereby saving costs and floor space.

Claims

1. A method for calculating parameters of the exhaust gas inlet of a tail gas incinerator, characterized in that, include: 1) Based on the gas flow calculation principle and the calculation formula for circumferential opening ratio ε, combined with the incinerator inner diameter D, the tail gas inlet radial length a and axial length b, and the tail gas inlet velocity v, the total number N of tail gas inlets distributed circumferentially on the inner wall of the incinerator to meet the maximum tail gas flow requirement Q of the incinerator is obtained: π is the mathematical constant Pi; the number of exhaust gas inlets in each row is obtained by combining the number of rows of exhaust gas inlets set around the circumference of the inner wall of the incinerator. 2) Based on the calculation formula for swirl intensity k, combined with the gas flow rate Q input to the incinerator in the axial direction. r +Q k The dimensions of the incinerator, the maximum value of the exhaust gas flow rate entering the incinerator, and the dimensions of the exhaust gas inlet are used to determine the angle between the intake direction of the exhaust gas inlet and the radius of the incinerator's cross-section. Furthermore, the intake directions of the exhaust gas inlets in the same row are at the same angle to the radius of the incinerator's cross-section, allowing the exhaust gas to enter in a clockwise or counterclockwise radial rotation along the inner wall of the incinerator. The angle θ between the intake direction of the i-th row of exhaust gas inlets and the radius of the incinerator's cross-section is... i for N i Let Q be the number of exhaust gas inlets in the i-th row. r Q k These represent the maximum values ​​of the gas flow rate and air flow rate in the axial direction of the incinerator, respectively. 3) Based on the number of exhaust gas inlets in each row and the angle between the exhaust gas inlet direction and the radius of the incinerator cross-section, the exhaust gas inlets are designed to ensure that the exhaust gas is fully combusted in the incinerator.

2. The method for calculating the parameters of the tail gas inlet of the tail gas incinerator according to claim 1, characterized in that, The exhaust gas inlets of two adjacent rows of rotating air intakes rotate in opposite directions.

3. The method for calculating the parameters of the tail gas inlet of the tail gas incinerator according to claim 1, characterized in that, In the axial gas flow rate input to the incinerator, the gas flow rate ratio between the air inlet and the gas inlet ranges from 2:1 to 40:

1.

4. The method for calculating the parameters of the exhaust gas inlet of the exhaust gas incinerator according to claim 1, characterized in that, The gas flow ratio between the exhaust gas inlet and the fuel gas inlet of the incinerator ranges from 0:1 to 60:1.

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