JP2009174741A - Ground flare and its combustion control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground flare and its combustion control method capable of stably burning a treated gas by preventing combustion oscillation. <P>SOLUTION: This ground flare 1 having a treated gas introduction passage 4 for introducing the treated gas to a lower portion of a heat chamber 2, and a combustor 5, and supplying combustion air from a bottom of the heat chamber to burn the treated gas, furthermore comprises a first air supply passage 15 for supplying the combustion air to a lower part of the combustor 5, a second air supply passage 18 for supplying the combustion air to an upper part of the combustor 5, an air quantity calculating means for calculating the quantity of air necessary for burning the treated gas, and an air supply quantity control means for dividing and supplying the combustion air from the first air supply passage 15 and the second air supply passage 18 on the basis of the quantity of air calculated by the air quantity calculating means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ground flare capable of stably burning exhaust gas whose calorific value varies, and a combustion control method thereof.

  There is a flare stack as a facility for combusting surplus gas generated in various plants such as oil refining and steel manufacturing facilities.

  As a general flare stack, a frame-supporting flare stack installed at an oil refinery base is known. This type of flare stack guides the gas to be processed to a high place and burns it, and radiant heat can be reduced by taking a distance in the height direction.

  However, in the above flare stack, since radiant heat and flames affect the surroundings, ground flare has been developed and installed in various places to solve these problems.

  Since the ground flare burns the gas to be treated in a cylindrical combustion cylinder installed on the ground, the flame is not visible and the gas to be treated can be burned with low noise (for example, Patent Document 1).

  Therefore, when the gas to be processed is processed by the ground flare, there is an advantage that the influence on the surrounding environment is small.

  FIG. 8 shows the structure of the ground flare.

The ground flare 50 is provided with a combustion air intake 52 at the bottom of the combustion cylinder 51, and the combustion air is sucked from the intake 52 only by the chimney draft (draft). Things are common. In the figure, reference numeral 53 denotes a burner.
JP-A-53-98531

  However, although the above-mentioned ground flare can be stably burned for a gas with a high calorific value, for example, a gas with a low calorific value including a combustion gas or an inert gas has poor flammability. The flame is not stable, and the flame is blown out and re-ignited repeatedly under the influence of the flow of the surrounding air. In some cases, so-called combustion vibration may occur.

  In particular, when the temperature in the ground flare rises, the amount of natural suction increases, and the turbulence of the gas flow in the vicinity of the burner 53 increases, so that combustion vibration is more likely to occur.

  Once combustion vibration occurs, the vibration becomes intense due to resonance, amplification, etc., and the operation may not be continued. In the worst case, the equipment may be damaged.

  When processing a gas to be processed with a low calorific value or a gas to be processed whose gas composition or supply amount changes, the flame can be stabilized by mixing the auxiliary combustion gas with the gas to be processed.

  However, if auxiliary combustion gas is used at all times, the temperature in the combustion cylinder rises too much and the equipment becomes dangerous, and wasteful fuel is consumed, which causes environmental problems.

  The present invention has been made in consideration of the above-described problems in the conventional ground flare, and provides a ground flare and a combustion control method thereof that can stably burn the gas to be treated by preventing combustion vibration. To do.

  The present invention includes a first invention in which combustion air is dividedly supplied based on a flow rate of gas to be treated supplied to the combustion cylinder, and a second invention in which combustion air is dividedly supplied based on the temperature in the combustion cylinder. .

1 First invention A ground flare according to the first invention has a gas inlet for introducing gas to be processed and a combustor at a lower portion of the combustion cylinder, and supplies combustion air from the bottom of the combustion cylinder. In the ground flare for burning the gas to be treated,
A first air supply path for supplying combustion air below the combustor;
A second air supply path for supplying combustion air above the combustor;
An air amount calculating means for calculating an air amount necessary for burning the gas to be treated;
The gist of the present invention is that it comprises air supply amount control means for dividing and supplying combustion air from the first air supply passage and the second air supply passage based on the air amount calculated by the air amount calculation means. .

  In the ground flare, as the first and second air supply passages, a duct communicating with the combustion cylinder, a blower for sending the combustion air into the duct, and an air supply amount in the duct are measured and measured. A flow meter for supplying data to the air supply amount control means, and a damper provided in the duct and having an opening adjusted by the air supply amount control means can be provided.

  Further, an auxiliary combustion gas supply path can be connected to the treated gas introduction path via a valve.

  The second air supply path is preferably configured to supply the combustion air toward the flame upper end of the combustor.

A ground flare combustion control method according to a first aspect of the present invention is a ground flare combustion method in which a gas to be treated is introduced into a lower portion of a combustion cylinder, burned by a combustor, and combustion air is supplied from the bottom of the combustion cylinder. ,
The amount of air necessary for burning the gas to be treated is calculated by the air amount calculation means,
Based on the air amount calculated by the air amount calculation means, a first air supply path provided below the combustor for supplying combustion air, and a combustion air provided above the combustor for supplying combustion air. The gist is to divide and supply the combustion air from the second air supply path.

2 Second invention A ground flare according to the second invention has a gas introduction passage for introducing a gas to be treated and a combustor at a lower portion of the combustion cylinder, and supplies combustion air from the bottom of the combustion cylinder. In the ground flare for burning the gas to be treated,
A first air supply path for supplying combustion air below the combustor;
A second air supply path for supplying combustion air above the combustor;
A first thermometer for measuring the temperature of the combustion part of the combustion cylinder;
A second thermometer for measuring the temperature at the outlet of the combustion cylinder;
Air that flows through the first air supply path based on the temperature measured by the first thermometer and that flows through the second air supply path based on the temperature measured by the second thermometer The gist of the invention is that it comprises an air supply amount individual control means for controlling the amount.

A ground flare combustion control method according to a second aspect of the invention is a ground flare combustion method in which a gas to be treated is introduced into a lower portion of a combustion cylinder, burned by a combustor, and combustion air is supplied from the bottom of the combustion cylinder. ,
The temperature of the combustion part of the combustion cylinder is measured with a first thermometer, and the temperature of the outlet part is measured with a second thermometer,
Air that flows through the first air supply path based on the temperature measured by the first thermometer and that flows through the second air supply path based on the temperature measured by the second thermometer The gist is to control the amount.

  In addition, the gas to be processed in the present invention refers to a gas having a low calorific value including a combustion gas or an inert gas discharged from, for example, an iron manufacturing facility or a melting furnace.

  According to the present invention, even if a gas to be treated with a low calorific value is supplied, combustion can be performed stably without causing combustion vibration, so that air pollution can be prevented and environmental conservation can be achieved. Have. Moreover, there is no possibility of damaging the equipment, and the life of the ground flare can be extended.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

1 First invention
1.1 Configuration of Ground Flare FIG. 1 shows the configuration of a ground flare and its peripheral equipment to which the first combustion control method according to the present invention is applied.

  In the figure, a ground flare 1 has a cylindrical combustion cylinder 2 arranged vertically, and the combustion cylinder 2 is installed on a pedestal 3 made of concrete.

  A to-be-treated gas introduction pipe (a to-be-treated gas introduction path) 4 is provided at the lower part in the combustion cylinder 2, and this to-be-treated gas introduction pipe 4 is connected to a burner 5 as a combustor.

  A gas to be treated including unburned gas is supplied to the gas to be treated introduced pipe 4 in a state of being pressurized by a blower 6, and the blower 6 is connected to a pipe on the upstream side of the water sealing tank 8. 13 is connected. That is, the gas to be treated to be burned is sent into the water sealing tank 8 by the blower 6, floats as a bubble from the water stagnation part 8 a that prevents backflow of air, and is sent from the pipe 7 to the gas to be treated introduction pipe 4. It is supposed to be.

  The flow rate of the gas to be processed flowing through the gas to be processed introducing pipe 4 is measured by a flow meter 9.

  Further, an auxiliary combustion gas supply pipe 11 is connected to the water sealing tank 8 via a valve 10, and when the heat generation amount of the gas to be treated is too low, the auxiliary gas is supplied by opening the valve 10. It has become.

  The auxiliary combustion gas supplied through the valve 10 is mixed with the gas to be processed in the water sealing tank 8 and is sent to the pipe 7 as the gas to be processed whose calorific value is increased.

  Further, the supply amount of the auxiliary combustion gas is measured by a flow meter 12 provided in the auxiliary combustion gas supply pipe (auxiliary gas supply passage) 11, and the flow rate of the gas to be treated is measured by a flow meter 14 provided in the pipe 13. It is like that.

  The gas to be processed whose calorific value is increased by mixing the gas to be processed or the auxiliary combustion gas in this way is introduced into the burner 5 through the gas to be processed introducing pipe 4.

  On the other hand, a first duct (first air supply path) 15 is connected to the lower stage (bottom) of the combustion cylinder 2, and a first blower 16 is connected to the first duct 15. Further, a first damper 15 a for adjusting the amount of air supplied into the combustion cylinder 2 is provided in the first duct 15. In the figure, reference numeral 17 denotes a first flow meter provided in the first duct 15, and measures the amount of air supplied into the combustion cylinder 2.

  A second duct (second air supply path) 18 and a second blower 19 are connected to the middle stage of the combustion cylinder 2 so that air is supplied toward the upper end portion B of the flame A generated from the burner 5. It has become. In the second duct 18, a second damper 18a for adjusting the amount of air to be supplied is provided. A second flow meter 20 that measures the amount of air is provided in the second duct 18.

  A third duct 21 and a third blower 22 are connected to the upper stage of the combustion cylinder 2 so as to supply air toward the inside of the outlet side of the combustion cylinder 2. The third duct 21 is provided with a third damper 21a for adjusting the amount of air to be supplied. A third flow meter 23 for measuring the amount of air is provided in the third duct 21.

  As described above, in this embodiment, air is supplied from the lower and middle stages of the combustion cylinder 2 to perform combustion, and air is also supplied from the upper stage as necessary. Specifically, the air distribution in the vicinity of the burner 5 is stabilized by setting the air distribution in the lower stage, interruption, and upper stage to, for example, 5: 4: 1, and combustion vibration is prevented.

  The combustion cylinder 2 is provided with a first thermometer 24 for monitoring so that the combustion temperature in the combustion cylinder 2 does not exceed the fireproof temperature.

  The pipe 13 is provided with an oxygen concentration meter 25, and an outlet flow meter 26 for measuring the amount of exhaust gas is provided at the upper outlet portion of the combustion cylinder 2.

  The flow rates measured by the flow meters 9, 12, 14, 17, 20, 23 and 26, the temperature measured by the first thermometer 24, and the oxygen concentration measured by the oxygen concentration meter 25 are controlled. Is provided to a device 27 (see FIG. 2)

  The controller 27 is configured to execute a combustion control operation to be described later according to a preprogrammed procedure, and an air amount calculating means for calculating an air amount necessary for burning the gas to be processed, and Based on the amount of air, it functions as air supply amount control means for supplying combustion air separately from the first duct 15 and the second duct 18.

  Further, the opening and closing of the valve 10 and the amount of combustion air from the third duct 21 are controlled as necessary.

  When the gas to be treated is introduced into the combustion cylinder 2 through the gas to be treated introduction pipe 4, the burner 5 is ignited by the pilot burner 5 a, and as a result, a draft effect is generated in the combustion cylinder 2, The supplied air is sucked into the combustion cylinder 2.

  When the load of the gas to be processed increases and the draft becomes stronger, a larger amount of air is sucked from the first duct 15 and the flow in the vicinity of the burner 5 is disturbed to easily generate combustion vibration.

  Thus, in the present embodiment, air is also sucked from the second duct 18 so that the gas flow in the vicinity of the burner 5 is not disturbed.

1.2 Combustion Control Method of First Invention Hereinafter, a combustion control method will be described with reference to FIGS.

First, FIG. 2 is a schematic diagram of a ground flare, and symbols used in the following description of combustion control are shown in the drawing. The list is as follows.
AI-100: Flow rate of treated gas
FI-200: Flow rate of auxiliary gas
FI-101: Air volume from the first duct 15
FI-102: Air volume from second duct 18
FI-103: Air volume from the third duct 21
TI-101: Combustion temperature
AI-O ₂ : oxygen concentration

  FIG. 3 is a flowchart showing a control operation by the controller 27.

  In the figure, when operating the ground flare 1, it is assumed that the first damper 15a and the second damper 18a are each set to be fully open (initial setting).

  Further, the flow rate of the gas to be processed is measured by the flow meter 14, and the flow rate of the auxiliary combustion gas is measured by the flow meter 12 (step S1).

Next, an air amount A required to completely burn the gas to be treated is obtained by the following equation (1) (step S2).
Air volume A = a · (AI-100) + a '· (FI-200) (1)
Where a and a 'are the theoretical combustion air volume [m ³ _N / kg-fuel]

  Next, the amount of air introduced from the first duct 15 is measured by the first flow meter 17, and the measured air amount FI-101 is divided by the air amount A, so that it is necessary to burn the gas to be treated. Convert the amount of air into air ratio.

Next, it is determined whether or not the obtained air ratio FI-101 / A satisfies the following expression (2) (step S3).
1.0 <FI-101 / A <1.5 …… (2)

  In the conventional ground flare that supplies air from one duct provided at the lower part of the combustion cylinder, the air ratio is generally set to about 2. On the other hand, in this embodiment, first, air is supplied from the first duct 15 in the range of 1.0 to 1.5.

  If the determination result of step S3 is NO, the opening degree of the first damper 15a is adjusted (step S4), and the process returns to step S1.

  Specifically, when the air is supplied from the first duct 15 to the combustion cylinder 2 beyond the set range, the first damper 15a is throttled, and when the air is less than the set range, the first damper Control to open 15a.

  If the result of determination in step S3 is YES by adjusting the first damper 15a, the opening degree of the first damper 15 is maintained as it is (step S5).

Next, the amount of air introduced from the second duct 18 is measured, and it is determined whether or not the measured air amount FI-102 satisfies the following expression (3) (step S6).
0 <FI-102 / A <1.0 …… (3)
If the determination result is NO, the second damper 18a is opened and the process returns to step S1.

  That is, if the amount of air introduced from the first duct 15 is insufficient, an amount of air corresponding to the shortage is introduced from the second duct 18.

  If the determination result in step S6 is YES, the second damper 18a is closed (step S8), and the process returns to step S1.

  Thus, in the combustion control method according to the first aspect of the present invention, the amount of air introduced from the first duct 15 is determined based on the amount of air A, and the first amount is determined according to the amount of air introduced from the first duct 15. The amount of air from the two ducts 18 is determined, and combustion air is divided and supplied from the two ducts 15 and 18.

  FIG. 4 is a flowchart showing control for burning the gas to be processed at an appropriate concentration.

First, the oxygen concentration AI-O ₂ of the gas to be processed flowing through the pipe 13 is measured by the oxygen concentration meter 25 (step S10).

Next, it is determined whether or not AI-O ₂ has an oxygen concentration of 4% or less to prevent explosion (step S11).

If YES in step S11, then
Target treated gas combustion temperature T _S -Combustion temperature TI-101 ≧ 30 ° C
Is determined (step S12).

  If the determination result is YES, the valve 10 is opened so that the combustion temperature does not become too high (step S13).

On the other hand, if the determination result is NO,
Combustion temperature TI-101-Target exhaust gas combustion temperature T _S ≥ 50 ° C
Is determined (step S14).

  If the determination result in step S14 is YES, that is, if normal combustion is being performed, the valve 10 is closed (step S15). If the determination result is NO, that is, if the combustion is incomplete, the valve 10 is closed. Is maintained at the current position, and the auxiliary combustion gas is continuously supplied (step S16).

  In this way, proper combustion in the combustion cylinder 2 is ensured.

2 Second Invention According to the Present Invention Next, a combustion control method according to the second invention will be described with reference to FIGS. FIG. 5 shows the configuration of a ground flare to which the combustion control method according to the second invention is applied. In FIG. 5, the same components as those in FIG. To do.

2.1 Structure of ground flare A second thermometer 30 for measuring the exhaust gas outlet temperature is provided at the upper part of the combustion cylinder 2, and the temperature measured by the first thermometer 24 and the second thermometer 30 is The opening / closing operation of the first damper 15a and the second damper 18a is controlled by a control signal input to the controller 31 and output from the second controller 31.

  The second controller 31 controls the amount of air flowing through the first duct 15 based on the temperature measured by the first thermometer 24, and the second controller 31 based on the temperature measured by the second thermometer 30. It functions as air supply amount individual control means for controlling the amount of air flowing through the duct 18.

2.2 Combustion Control Method of Second Invention FIGS. 6 and 7 are flowcharts showing the control operation by the second controller 31.

First, in FIG. 6, when the temperature measured by the first thermometer 24 is θ1, and the target temperature in the combustion section is T1,
It is determined whether θ1> T1 is satisfied (step S30).

  If the determination result is NO, control is performed so that the combustion temperature rises by lowering the opening of the first damper 15a (step S31).

If the determination result is YES, it is subsequently determined whether θ1 has exceeded the upper limit temperature T1 _max of the combustion section (step S32).

If it exceeds T1 _max , the opening degree of the first damper 15a is increased to suppress the combustion temperature (step S33).

  If NO in step S32, the process returns to step S30.

Next, in FIG. 7, when the temperature measured by the second thermometer 30 is θ2, and the target temperature at the combustion cylinder outlet is T2,
It is determined whether θ2> T2 is satisfied (step S34).

  If the determination result is NO, the control is performed so that the combustion temperature rises by lowering the opening of the second damper 18a (step S35).

If the determination result is YES, it is subsequently determined whether or not θ2 exceeds the upper limit temperature T2 _max at the combustion cylinder outlet (step S36).

If it exceeded T2 _max, suppressing the combustion temperature to increase the degree of opening of the second damper 18a (step S37).

  If NO in step S36, the process returns to step S34.

  Thus, the combustion control method of the present invention can also be controlled based on the output from the thermometer provided in each part of the combustion cylinder 2.

  Each control shown in FIGS. 6 and 7 is executed independently.

It is a block diagram of the ground flare of 1st invention which concerns on this invention. It is the schematic diagram of the ground flare which showed the symbol used for description of combustion control. It is a flowchart which shows the combustion control operation | movement of 1st invention. It is a flowchart which shows the control content in order to perform appropriate combustion in 1st combustion control operation | movement. It is a schematic diagram of the ground flare of 2nd invention which concerns on this invention. It is a flowchart which shows the combustion control operation | movement of 2nd invention. It is a flowchart which shows the combustion control operation | movement of 2nd invention. It is explanatory drawing which shows the combustion method of the conventional ground flare.

Explanation of symbols

1 Ground Flare 2 Combustion Tube 3 Base 4 Processed Gas Introducing Pipe (Processed Gas Introducing Path)
5 Burner (combustor)
6 Blower 7 Piping 8 Water-sealed tank 9 Flow meter 10 Valve 11 Auxiliary gas supply pipe (Auxiliary gas supply path)
12 Flow meter 13 Piping 14 Flow meter 15 First duct (first air supply path)
15a First damper 16 First blower 17 First flow meter 18 Second duct (second air supply path)
18a Second damper 19 Second blower 20 Second flow meter 21 Third duct 21a Third damper 22 Third blower 23 Third flow meter 24 First thermometer 25 Oxygen concentration meter 26 Outlet flow meter 27 Controller 30 Second temperature Total 31 second controller

Claims (7)

In a ground flare that has a treated gas introduction path and a combustor that introduces a treated gas into a lower part of the combustion cylinder, supplies combustion air from the bottom of the combustion cylinder, and burns the treated gas.
A first air supply path for supplying combustion air below the combustor;
A second air supply path for supplying combustion air above the combustor;
An air amount calculating means for calculating an air amount necessary for burning the gas to be treated;
And an air supply amount control means for dividing and supplying combustion air from the first air supply passage and the second air supply passage based on the air amount calculated by the air amount calculation means. Grand flare.   As the first and second air supply paths, a duct communicating with the combustion cylinder, a blower for sending the combustion air into the duct, an air supply amount in the duct is measured, and the measurement data is supplied to the air supply 2. The ground flare according to claim 1, further comprising: a flow meter provided to the amount control means; and a damper provided in the duct and having an opening adjusted by the air supply amount control means.   The ground flare according to claim 1 or 2, wherein an auxiliary combustion gas supply path is connected to the processing gas introduction path via a valve.   The ground flare according to any one of claims 1 to 3, wherein the second air supply path is configured to supply the combustion air toward an upper flame end of the combustor. In the combustion method of the ground flare that introduces the gas to be treated into the lower part of the combustion cylinder, burns it with a combustor, and supplies combustion air from the bottom of the combustion cylinder,
The amount of air necessary for burning the gas to be treated is calculated by the air amount calculation means,
Based on the air amount calculated by the air amount calculation means, a first air supply path provided below the combustor for supplying combustion air, and a combustion air provided above the combustor for supplying combustion air. A ground flare combustion control method, wherein combustion air is divided and supplied from a second air supply path. In a ground flare that has a treated gas introduction path and a combustor that introduces a treated gas into a lower part of the combustion cylinder, supplies combustion air from the bottom of the combustion cylinder, and burns the treated gas.
A first air supply path for supplying combustion air below the combustor;
A second air supply path for supplying combustion air above the combustor;
A first thermometer for measuring the temperature of the combustion part of the combustion cylinder;
A second thermometer for measuring the temperature at the outlet of the combustion cylinder;
Air that flows through the first air supply path based on the temperature measured by the first thermometer and that flows through the second air supply path based on the temperature measured by the second thermometer An air supply amount individual control means for controlling the amount of the ground flare. In the combustion method of the ground flare that introduces the gas to be treated into the lower part of the combustion cylinder, burns it with a combustor, and supplies combustion air from the bottom of the combustion cylinder,
The temperature of the combustion part of the combustion cylinder is measured with a first thermometer, and the temperature of the outlet part is measured with a second thermometer,
Air that flows through the first air supply path based on the temperature measured by the first thermometer and that flows through the second air supply path based on the temperature measured by the second thermometer A ground flare combustion control method characterized by controlling the amount.

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