Parameter calculation method for tail gas inlet of tail gas incinerator

Abstract

The invention belongs to the technical field of tail gas incineration, and particularly relates to a parameter calculation method for a tail gas inlet of a tail gas incinerator. In order to solve the problems that in the using process of an existing incinerator, tail gas cannot be controlled, and the tail gas cannot be fully combusted, according to the gas flow calculation principle, the circumferential aperture ratio calculation principle and the rotational flow strength calculation principle, the combustion of the tail gas is controlled; the number of the tail gas inlets in each row and the gas inlet direction of the tail gas inlets are calculated in combination with parameters of the incinerator, so that rotating gas flow is generated, the tail gas is fully combusted in the incinerator, under the condition that flames are kept stable, the tail gas reaction is more sufficient, the fuel utilization rate and the tail gas treatment efficiency are improved, and the combustion efficiency is improved. And the length of the hearth can be shortened under the condition of keeping the same treatment efficiency, so that the cost is saved, and the occupied area is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of tail gas incineration, and in particular relates to a method for calculating parameters of a tail gas inlet of a tail gas incinerator. Background Art

[0002] The 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 the natural gas absorption tower to the oxidation reaction temperature, thereby causing oxidative decomposition. However, the existing incinerator cannot completely and fully incinerate the tail gas generated in the production process, so it needs to be improved.

[0003] The tail gas injection device of the existing incinerator directly opens a nozzle perpendicular to the furnace wall on the cylindrical furnace, and the nozzle is arranged in the upper part of the furnace. There are two disadvantages of such an arrangement: first, the tail gas flow enters from the upper part of the furnace, and the flow field formed is unevenly distributed and asymmetrical, and the high-temperature airflow in the lower part of the furnace is difficult to fully participate in the reaction, resulting in heat waste; second, the tail gas flow entering the furnace perpendicular to the furnace wall is not fully mixed with the high-temperature gas generated by the combustion of the fuel gas, so that the heat obtained by the tail gas through the air flow mixing is insufficient. Since the oxidation reaction is sensitive to temperature, if the mixing is not sufficient, the temperature of the tail gas components is low, which will lead to a slow oxidation reaction speed and insufficient oxidation of harmful components.

[0004] The Chinese utility model patent application with authorization announcement number CN208871646U discloses a tail gas incinerator for sulfur recovery, which divides the incinerator body into a front incineration zone and a rear incineration zone. The air input structure and the tail gas input structure of the tail gas incinerator both include a gas gathering cavity circumferentially arranged on the furnace body wall and a gas distribution channel arranged on the furnace body wall. The gas distribution channel connects the gas gathering cavity with the inner cavity of the incinerator, so that the amount of NOX generated in the burner fire channel can be controlled, and the generation of carbon monoxide (CO) can be effectively reduced, and ultimately the effective treatment of the tail gas can be achieved. However, it does not play a good control role on the tail gas transported inside the incinerator, and the multi-stage air intake easily leads to a decrease in the temperature inside the incinerator, so that the tail gas cannot be fully burned during the use of the incinerator as a whole, so there are great limitations.

[0005] Therefore, the existing air intake method of the tail gas incinerator cannot meet the needs in actual use. Summary of the invention

[0006] The object of the present 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 problem that the existing incinerator as a whole cannot control the exhaust gas during use and cannot fully burn the exhaust gas.

[0007] In order to solve the above technical problems, the present invention provides a method for calculating the parameters of the tail gas inlet of a tail gas incinerator, and the specific steps include:

[0008] 1) According to the gas flow calculation principle and the circumferential opening rate calculation formula, combined with the size of the incinerator, the size of the tail gas inlet and the flow rate of the tail gas inlet, the total number of tail gas inlets that meet the maximum value of the tail gas flow of the incinerator and are distributed on the circumference of the inner wall of the incinerator is calculated, and then the number of tail gas inlets in each row is obtained in combination with the number of rows of tail gas inlets arranged on the circumference of the inner wall of the incinerator;

[0009] 2) According to the calculation formula of swirl intensity, the angle between the intake direction of the exhaust gas inlet and the radius line of the cross section of the incinerator is calculated in combination with the gas flow rate input in the axial direction of the incinerator, the size of the incinerator, the maximum exhaust flow rate entering the incinerator, and the size of the exhaust gas inlet, and the intake direction of the exhaust gas inlet in the same row has the same angle with the radius line of the cross section of the incinerator, so that the exhaust gas is inhaled in a clockwise or counterclockwise rotating manner in the radial direction of the inner wall of the incinerator;

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

[0011] Its beneficial effects are: in order to solve the problem that the existing incinerator as a whole cannot control the exhaust gas and cannot fully burn the exhaust gas during use, the present invention calculates the number of exhaust gas inlets in each row and the intake direction of the exhaust gas inlets based on the gas flow calculation principle, the circumferential opening rate calculation principle and the swirl intensity calculation principle, combined with the parameters of the incinerator, so that the exhaust gas can be fully burned in the incinerator. The present invention can make the exhaust gas react more fully while maintaining flame stability, increase fuel utilization and exhaust gas treatment efficiency, and can also shorten the furnace length while maintaining the same treatment efficiency, thereby saving costs and floor space.

[0012] Furthermore, the rotation directions of the exhaust gas inlet ports of two adjacent rows of rotating air intake are opposite.

[0013] The beneficial effect is that the positive and negative rotation momentum of every two rows of exhaust gas inlets are offset, which is beneficial for the airflow to decay into a straight flow when leaving the incinerator, and is beneficial for sufficient heat exchange of the downstream waste heat boiler.

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

[0015]

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

[0017] Furthermore, the calculation formula for the angle between the air intake direction of a row of exhaust gas inlets and the radius line of the incinerator cross section is:

[0018]

[0019] Among them, θ i is the angle between the air inlet 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 ) is the gas flow rate of the incinerator in the axial direction, Q r is the maximum value of the gas flow rate in the axial direction of the incinerator, Q k It is the maximum value of the air flow rate in the axial direction of the incinerator.

[0020] Furthermore, in the gas flow rate input into the incinerator in the axial direction, the gas flow rate ratio of the air inlet to the fuel 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

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

[0028] Figure 7 It is 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 It is a partial enlarged view of the sleeve-type air inlet of the tail gas incinerator of the present invention;

[0030] Fig. 9 It is a parameter design flow chart of the tail gas inlet of the present invention.

[0031] Among them: 1-air duct; 2-gas and exhaust gas sleeve-type air inlet; 3-distribution device; 4-incineration furnace; 5-first row exhaust gas inlet; 6-second row exhaust gas inlet; 7-flame observation port; 8-insulation interlayer; 9-gas outlet. DETAILED DESCRIPTION

[0032] The basic concept of the present invention is: to solve the problem that the existing incinerator as a whole cannot control the exhaust gas and cannot fully burn the exhaust gas during use, the present 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 according to the size of the incinerator and the size of the exhaust gas inlet, combined with the axial air flow of the incinerator and the air flow of the exhaust gas inlet, so that the exhaust gas forms a suitable rotating airflow in the incinerator, so that the exhaust gas can be fully burned in the incinerator. Based on this concept, a parameter calculation method for the exhaust gas inlet of an exhaust gas incinerator can be realized according to the size of the incinerator and the size of the exhaust gas inlet.

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

[0034] Example of a method for calculating parameters of a tail gas inlet of a tail gas incinerator:

[0035] The overall view of a tail gas incinerator is as follows Figure 1 As shown, the front view of the tail gas incinerator is as follows Figure 2 As shown, the top view of the tail gas incinerator is as follows Figure 3 As shown, the incinerator specifically includes: an air duct 1, a gas and exhaust gas sleeve-type air inlet 2, a distribution device 3, an incineration furnace 4, a first row of exhaust gas inlets 5, a second row of exhaust gas inlets 6, a flame observation port 7, a thermal insulation interlayer 8, and a gas outlet 10.

[0036] The gas and exhaust gas sleeve-type air inlet 2 is arranged in the center of the air duct 1 and is coaxially arranged with the air duct 1 at the head of the incineration furnace 4 (such as Figure 7 , Figure 8 As shown), it is used to spray fuel gas (mainly CH4) and air into the furnace head for combustion to establish a high-temperature field in the furnace.

[0037] The distribution device 3 is arranged in the middle section of the incineration furnace 4, and is used to set the exhaust gas inlet (in this embodiment, two rows of exhaust gas inlets for counter-tangential intake are arranged), wherein the first row of exhaust gas inlets 5 are arranged at intervals of 1 / 400 mm on the circumference of the inner wall of the incineration furnace 4. An air inlet is set, with a total of N1 (N1 is an integer between 2 and 36) in a circle, and tangential air is introduced in a direction of an angle θ1 formed with the inner radius line of the cross section of the incinerator chamber 4 (the value range of θ1 is 5°-85°, such as Figure 4 As shown in FIG. 1 , the distance between the second row of exhaust gas inlet ports 6 and the first row of exhaust gas inlet ports 5 is between 0.5 m and 5 m, and the second row of exhaust gas inlet ports 6 are spaced apart from each other in the circumferential direction of the inner wall of the incineration furnace 4. An air inlet is set, with a total of N2 (N2 is an integer between 2-36) in a circle, and tangential air is introduced in the direction of the angle θ formed with the inner diameter radius line of the cross section of the incinerator chamber 4 (the value range of θ2 is 5°-85°, such as Figure 5 As shown), the direction of the formed tangential jet is opposite to that of the first row of exhaust gas inlet ports 5, forming an anti-tangential airflow; wherein, in order to solve the problem that the existing incinerator as a whole cannot control the exhaust gas during use and cannot fully burn the exhaust gas, a method for calculating the parameters of the exhaust gas inlet port of the exhaust gas incinerator of the present invention is as follows: Fig. 9 As shown, the specific steps include:

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

[0039] The main design basis for the size of the exhaust gas inlet is to control the speed of the exhaust gas injection. According to the operating experience of the existing exhaust gas incinerator, the flow velocity v of the exhaust gas inlet in the incinerator is generally in the range of 10m / s-50m / s, and the value can be 25m / s under normal circumstances; according to the size of the incinerator, the size of the exhaust gas inlet is selected. 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, such as Figure 6 As shown; Circumferential opening ratio It refers to the ratio of the width of the tail gas inlet opening to the circumference of the inner wall of the incinerator chamber; the total volume flow rate of gas passing through the tail gas inlet is obtained as follows:

[0040] Q=abvN=επDbvN

[0041] After moving the items and reordering them, we get:

[0042]

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

[0044] 2) Calculate the angles θ1 and θ2 between the air intake directions of the two rows of exhaust gas inlets and the radius line of the cross section of the incineration furnace;

[0045] Taking the first row of exhaust gas inlet as an example, its axial air flow in the incinerator is the sum of the maximum air flow of the fuel gas and air input into the incinerator (Q r +Q k ), Q r is the maximum value of the gas flow rate in the axial direction of the incinerator, Q k is the maximum value of the air flow rate of the incinerator in the axial direction; the axial characteristic dimension is the air inlet length b; the total air flow rate of the exhaust gas is Q, and there are N1 exhaust inlets in this row, so the total air flow rate of the exhaust inlet in this row is The exhaust gas inlet cut-off flow is the total gas flow multiplied by the tangent value of the angle θ1, that is, The characteristic dimension of the tangent direction is the inner radius of the incinerator chamber. From this, the swirl intensity (defined as: tangential flow multiplied by tangential characteristic length / axial flow multiplied by axial characteristic length) can be obtained:

[0046]

[0047] After moving items, we can get

[0048]

[0049] According to empirical data, the swirl intensity k ranges from 1 to 100, and can be 30 under normal circumstances. The calculation method of the second row exhaust gas intake port is the same as that of the first row exhaust gas intake port, and will not be described in detail here.

[0050] In order to make the exhaust gas incineration more thorough and make full use of the waste heat at the incinerator outlet, the number of air inlets in each row of exhaust gas inlets is set to be the same, so the formula can be simplified to:

[0051]

[0052]

[0053] Wherein, n is the number of exhaust inlets in each row; m is the number of rows; θ is the angle between the air intake direction of any row of exhaust inlets and the radius line of the cross section of the incineration furnace; in this embodiment, two rows of exhaust inlets are set, so:

[0054]

[0055]

[0056] A flame observation port 7 is provided on the outer side of the middle section of the incineration furnace 4 for observing the treatment of the exhaust gas during the combustion process.

[0057] The combustion furnace 4 is wrapped with a heat-insulating interlayer 8 outside to prevent heat loss during the combustion process.

[0058] A gas outlet 9 is provided at the rear of the incinerator chamber 4 for discharging the burned gas out of the incinerator.

[0059] To sum up, after the incinerator is set up, the specific steps of the working process of the incinerator are as follows:

[0060] Step 1: Use a sleeve to deliver air and fuel gas into the head of the furnace at the entrance of the tail gas incinerator. The fuel gas and air undergo combustion reaction, release heat, and form a high-temperature airflow, which provides heat and necessary oxygen for the oxidation of the tail gas introduced into the middle and rear part of the furnace.

[0061] Step 2, exhaust gas is input into the incinerator by arranging an exhaust gas input device in the middle section of the incinerator, wherein the first row of exhaust gas inlets adopts a tangential air intake method to form a rotating airflow in the center of the furnace, strengthens the pneumatic stirring effect, and makes the mixing between the airflow and the gas flame more complete; the second row of exhaust gas inlets arranged at a certain distance downstream of the first row of exhaust gas inlets form a rotating airflow in the center of the furnace in the same tangential air intake method, but the rotation direction is opposite to that of the first row of exhaust gas, and the reverse collision of the airflow is used to strengthen the pneumatic stirring effect, so that the mixing between the airflow and the gas flame is more complete, and the combustion of the exhaust gas is more thorough;

[0062] Step three, since the velocity and momentum of the two rows of exhaust gas jets are basically the same, but the rotation directions are opposite, after the rotational momentum is offset, the rotational momentum of the airflow in the cylindrical furnace quickly decays into a weak rotation flow, which is beneficial to improving the uniformity of the flow field when entering the waste heat boiler.

[0063] The present invention is mainly applicable to various types of tail gas incinerators for purifying tail gas by combustion. The tail gas can be efficiently treated without premixing the tail gas with the fuel gas, so that the tail gas reacts with oxygen at high temperature to form harmless inorganic oxides, thereby effectively avoiding the risks of accidents such as leakage and explosion when the tail gas is premixed with the fuel gas. The exhaust gas and fuel gas mixing equivalence ratio is adjusted according to the combustion conditions, so as to improve the fuel gas utilization efficiency, and the furnace length can be shortened while maintaining the same treatment efficiency, thereby saving costs and saving floor space.

Claims

1. A method for calculating parameters of an exhaust gas inlet of an exhaust gas incinerator, characterized in that: The specific steps include: 1) According to the gas flow calculation principle and the circumferential opening rate calculation formula, combined with the size of the incinerator, the size of the tail gas inlet and the flow rate of the tail gas inlet, the total number of tail gas inlets that meet the maximum value of the tail gas flow of the incinerator and are distributed on the circumference of the inner wall of the incinerator is calculated, and then the number of tail gas inlets in each row is obtained in combination with the number of rows of tail gas inlets arranged on the circumference of the inner wall of the incinerator; 2) According to the calculation formula of swirl intensity, the angle between the intake direction of the exhaust gas inlet and the radius line of the cross section of the incinerator is calculated in combination with the gas flow rate input in the axial direction of the incinerator, the size of the incinerator, the maximum exhaust flow rate entering the incinerator, and the size of the exhaust gas inlet, and the intake direction of the exhaust gas inlet in the same row has the same angle with the radius line of the cross section of the incinerator, so that the exhaust gas is inhaled in a clockwise or counterclockwise rotating manner in the radial direction of the inner wall of the incinerator; 3) Based on the obtained number of exhaust gas inlets in each row and the angle between the exhaust gas inlet direction and the radius line of the incinerator cross section, the exhaust gas inlet is designed to ensure that the exhaust gas is fully burned in the incinerator.

2. The method for calculating parameters of the tail gas inlet of the tail gas incinerator according to claim 1, characterized in that: The rotation directions of the exhaust gas inlet ports of two adjacent rows of rotating air intake are opposite.

3. The method for calculating parameters of the tail gas inlet of the tail gas incinerator according to claim 1, characterized in that: The formula for calculating the total number of exhaust inlets is: Wherein, N is the total number of exhaust gas inlets; Q is the maximum value of exhaust gas flow entering the incinerator; π is pi; D is the inner diameter of the incinerator; ε is the circumferential opening ratio; a is the length of the exhaust gas inlet along the radial direction of the incinerator; b is the length of the exhaust gas inlet along the axial direction of the incinerator; v is the flow velocity of the exhaust gas inlet.

4. The method for calculating parameters of the tail gas inlet of the tail gas incinerator according to claim 1, characterized in that: The calculation formula for the angle between the air intake direction of a row of exhaust gas inlets and the radius line of the incinerator cross section is: Among them, θ i is the angle between the air inlet 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 ) is the gas flow rate of the incinerator in the axial direction, Q r is the maximum value of the gas flow rate in the axial direction of the incinerator, Q k It is the maximum value of the air flow rate in the axial direction of the incinerator.

5. The method for calculating parameters of the tail gas inlet of the tail gas incinerator according to claim 1, characterized in that: In the gas flow rate inputted into the incinerator in the axial direction, the gas flow rate ratio of the air inlet to the fuel gas inlet ranges from 2:1 to 40:

1.

6. The method for calculating parameters of the tail gas inlet of the tail 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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