JP6958588B2 - Ignition judgment method, combustion emission control method using it, and ignition judgment device - Google Patents

Description

The present invention relates to an ignition determination method, a combustion emission control method using the ignition determination method, and an ignition determination device, and more particularly to an ignition determination method of a pilot burner used for a flare stack.

In factories that have gas generation equipment, flammable surplus gas may be generated in addition to product shipping gas or private fuel gas. Since such surplus gas is to be disposed of, the surplus gas is burned and dissipated (incinerated) in a combustion emission tower called a flare stack. Hereinafter, the surplus gas that is burned and dissipated is referred to as a dissipated gas. For example, in a steel mill, flammable blast furnace gas produced as a by-product from a blast furnace can be emitted gas. These excess emissions to be disposed of are burned and released in the flare stack.

Flare stacks typically include a main burner that burns the emitted gas and a pilot burner to ensure that the main burner is ignited. As the pilot gas used for the pilot burner, a combustible gas that is easier and more reliable to ignite than the radiated gas is used to ensure reliable ignition of the main burner.

The pilot burner is known to be a continuous pilot burner that constantly burns regardless of whether the main burner is ignited or a timed pilot burner that is ignited prior to the combustion of the emitted gas by the main burner and extinguished when the main burner is ignited. .. When the released gas is burned and released from the main burner, all pilot burners need to maintain the ignition state.

At the start of ignition of the pilot burner, a drive signal is sent to the igniter for the pilot burner to issue an ignition start command for the pilot burner, but it is necessary to determine the reliable ignition of the pilot burner in order to start the combustion emission of the emitted gas. .. Further, if the pilot burner is detected as a non-ignited state due to some abnormal condition after the pilot burner is ignited, it is necessary to stop the emission of the emitted gas. Therefore, it is necessary to reliably determine the ignition state of the pilot burner.

For example, Patent Document 1 proposes a method of detecting ignition of coke oven gas (pilot gas for pilot burner) in a flare stack and determining whether or not blast furnace gas (emission gas) can be burned. The determination method of Patent Document 1 is to determine whether the coke oven gas is ignited or non-ignited based on the temperature inside the flare stack column and the rate of temperature rise thereof within a preset time after the ignition of the coke oven gas by the pilot burner. It detects whether it is in a state and determines whether or not the blast furnace gas (emission gas) can be burned by the main burner.

JP-A-2017-166720

According to the ignition determination method of Patent Document 1, it is possible to determine the ignition state of the pilot burner from the start of ignition of the pilot burner to a predetermined time. By the way, when trying to determine the ignition state of the pilot burner based on the ambient temperature of the pilot burner, the temperature around the pilot burner does not always continue to rise and may decrease after a certain period of time has passed from the ignition. In such a case, if the determination conditions of Patent Document 1 (the temperature inside the tower and the rate of temperature rise thereof) are applied as they are, the pilot burner is not ignited even though the pilot burner is actually ignited and there is no safety problem. Since it is determined to be ignition, it becomes necessary to stop the combustion emission of the emitted gas. Therefore, it is required to establish an accurate ignition determination method for the pilot burner in consideration of the passage of time from the ignition of the pilot burner.

Therefore, an object of the present invention is to provide an ignition determination method capable of accurately determining the ignition state of the pilot burner used in the flare stack. A further object of the present invention is to provide a combustion emission control method in a flare stack using the determination method. Furthermore, an object of the present invention is to provide an ignition determination device capable of accurately determining the ignition state of a pilot burner used in a flare stack.

In order to solve the above problems, the present inventor has diligently studied the conditions for determining that the pilot burner is ignited using the ambient temperature of the pilot burner. Then, two conditions were conceived: (i) the ambient temperature exceeds the threshold temperature, and (ii) the absolute value of the temperature decrease rate of the ambient temperature is within the range of the absolute value of the threshold temperature decrease rate. Then, it was found that the pilot burner can be determined to be in the ignition state if both of these two conditions are satisfied. The abstract structure of the present invention completed based on the above findings is as follows.

(1) Pilot burner that ignites the pilot burner This is a method for determining the ignition of the pilot burner used for the flare stack that burns and dissipates the emitted gas from the main burner by the flame.
A measurement step for determining the ambient temperature of the pilot burner and the rate of temperature decrease of the ambient temperature per unit time, and
(I) Judgment that the pilot burner is in an ignition state when the ambient temperature exceeds the threshold temperature and (ii) the absolute value of the temperature lowering rate is within the absolute value of the threshold temperature lowering rate. Process and
An ignition determination method comprising.

(2) The flare stack includes N pilot burners (N is an integer of 2 or more).
The ignition determination method according to (1) above, wherein the determination step is performed on one or more (N-1) or less of the N pilot burners.

(3) The first step of determining the ignition of the pilot burner by using the ignition determination method according to (1) or (2) above, and
The second step of performing combustion emission of the emitted gas when it is determined that the pilot burner is ignited, and
A combustion emission control method comprising.

(4) An ignition determination device for a pilot burner used in a flare stack, comprising a pilot burner and a main burner that burns and dissipates emitted gas by a pilot burner flame that ignites the pilot burner.
A measuring instrument provided around the pilot burner to determine the ambient temperature of the pilot burner and the rate of temperature decrease of the ambient temperature per unit time.
The pilot burner is in an ignited state based on (i) that the ambient temperature exceeds the threshold temperature and (ii) that the absolute value of the temperature lowering rate is within the absolute value of the threshold temperature lowering rate. Judgment unit that determines that
An ignition determination device.

According to the present invention, it is possible to provide an ignition determination method capable of accurately determining the ignition state of the pilot burner used in the flare stack, and to provide a combustion emission control method in the flare stack using the determination method. can. Furthermore, the present invention can provide an ignition determination device capable of accurately determining the ignition state of the pilot burner used in the flare stack.

It is a schematic diagram explaining an example of flare stack applicable to one Embodiment of this invention. It is a schematic view which looked at the top of the flare stack in FIG. 1A in a plan view. It is a flowchart for demonstrating one Embodiment of the ignition determination method by this invention. It is a graph of the temperature around the pilot burner immediately after the start of ignition of the pilot burner used for the verification of the present invention. It is a graph of the temperature around the pilot burner after a lapse of a predetermined time from the start of ignition of the pilot burner used for the verification of this invention. It is a graph of the temperature around the pilot burner before and after extinguishing the pilot burner used for the verification of the present invention. It is a flowchart for demonstrating one Embodiment of the combustion emission control method by this invention.

Prior to the description of the present invention, the ignition determination method and the combustion emission control method according to the present invention, and the flare stack 1 suitable for use in the ignition determination device will be described with reference to the schematic views of FIGS. 1A and 1B. Note that FIG. 1B is a schematic view of the upper part of the flare stack in FIG. 1A as a plan view. Further, in FIGS. 1A and 1B, only the main parts necessary for the description of the present invention are shown, and the drawings are simplified.

<Flare stack>
The flare stack 1 will be illustrated exemplarily with reference to the schematic views of FIGS. 1A and 1B. The flare stack 1 includes a pilot burner 10 and a main burner 30, and the pilot burner 10 is arranged in the vicinity of the main burner 30. The pilot burner 10 and the main burner 30 are provided on the tower upper portion 72 of the tower portion 71 in the flare stack 1. FIG. 1B is a schematic view of the upper part of the tower 72 when viewed in a plan view. In the example of FIG. 1B, four pilot burners 10 are arranged substantially evenly (pilot burners 11, 12, 13, 14 respectively). It surrounds the main burner 30.

Further, as shown in FIG. 1A, the pilot gas pipeline 40 and the radiating gas pipeline 50 are connected to each of the pilot burner 10 and the main burner 30 provided in the upper part 72 of the tower. Shutoff valves 41 and 51 and flow rate control valves 42 and 52 are arranged in the middle of the pilot gas line 40 and the emission gas line 50, respectively. With each of these valves, the pilot gas and the emitted gas can be started or stopped from being supplied to the pilot burner 10 and the main burner 30, respectively, and the supply flow rate of each gas can be adjusted.

The flare stack 1 ignites the emitted gas by the pilot burner flame 80 that ignites the pilot burner 10, and burns and dissipates the emitted gas in the form of the main burner flame 90.

It should be noted that the above-described aspect of the flare stack 1 merely describes an example of the flare stack schematically shown in FIG. 1, and does not limit the present invention described in detail below. The number of pilot burners, the installation position thereof, and the configuration of the pipeline and the valve in the middle of the pipeline are arbitrary. The present invention can be applied to various flare stack pilot burners.

(Ignition judgment method)
An embodiment of the ignition determination method according to the present invention will be described with reference to the flowchart of FIG. 2 and FIGS. 1A and 1B described above. The ignition determination method according to the present invention determines the ignition state of the pilot burner 10 used for the flare stack 1 that burns and dissipates the emitted gas from the main burner 30 by the pilot burner flame 80 that ignites the pilot burner 10. Then, the ignition determination method according to the invention the measuring step S10 of obtaining a temperature decrease rate V _T per unit time of the peripheral temperature T and the ambient temperature T of the pilot burner 10, the threshold temperature T ₀ is (i) the ambient temperature T beyond, and includes, when the absolute value is within the range of the absolute value of the threshold cooling rate V _T0, the determination step S20 determines that the pilot burner 10 is ignited state of (ii) cooling rate V _T.

<Measurement process>
First, the measurement step S10 performed for obtaining the temperature decrease rate per unit time of the peripheral temperature T [° C.] and the ambient temperature T of the pilot burner _{10 (V T = ΔT / Δt} ). In FIG. 1A, in the periphery of the pilot burner 10, measurable instrument 20 ambient temperature T of the pilot burner 10 is provided, for example, by using this measuring device 20, the peripheral temperature T and temperature decrease rate V _T Can be sought. The ambient temperature T of the pilot burner 10 can fluctuate momentarily. Therefore, rather than the instantaneous cooling rate, obtaining an average cooling rate V _T per unit time. Unit time for obtaining the cooling rate V _T may be appropriately determined, it can be a temperature decrease rate per second [° C. / s], the cooling rate of the per instead of the second example, 3 seconds You may ask for it. Considering the momentary fluctuation of the ambient temperature T, the unit time is preferably about several seconds (for example, 1 second to 5 seconds).

See FIG. 1B. As described above, in the example of FIG. 1B, four pilot burners are arranged, and in this example, measuring instruments 21, 22, 23, 24 are provided around the pilot burners 11, 12, 13, and 14, respectively. ing. More specifically, the measuring instruments 21, 22, 23, 24 are provided on the sides of the pilot burners 11, 12, 13, and 14 opposite to the main burner 30. These instrument 20 can determine the ambient temperature T and its cooling rate V _T with.

As the measuring device 20, for example, a thermocouple type temperature measuring device attached to a known pilot burner can be used. In addition to the thermocouple type temperature measuring device, any temperature sensor such as a radiation thermometer can be used as the measuring device 20, and the measuring device 20 is not limited as long as it can measure the ambient temperature of the pilot burner 10. Further, the installation position of the measuring instrument 20 is an example, and is not limited as long as it is an arrangement position where the ambient temperature of the pilot burner 10 can be measured, and may be appropriately determined according to the measuring method of the measuring instrument. .. However, it is preferable to dispose of it at a position where the influence of the temperature change due to the combustion emission of the emitted gas by the main burner 30 can be suppressed, and as illustrated in FIG. 1B, the main burner 30 is separated from the main burner 30 via the pilot burner 10. It is preferable to arrange it at a position, and it is preferable to use a thermocouple type temperature measuring device.

<Judgment process>
Following the measurement step S10, a determination step S20 for determining the ignition state of the pilot burner 10 is performed. In this determination step, when the ambient temperature T and a temperature decrease rate V _T of the pilot burner 10 as measured in the measurement step S10 is satisfied each of the following two conditions, it is determined that the pilot burner 10 is ignited state.
Condition 1: The ambient temperature T exceeds the _{threshold temperature T 0.}
(T> T ₀ ; (i) above)
Condition 2: in the range of absolute value of the threshold cooling rate V _T0 of the cooling rate V _{T.
(| V T | ≦ | V} T0 |; previously described (ii))
If at least one of the above conditions 1 and 2 is not satisfied, the pilot burner 10 is determined to be in a non-ignition state (fire extinguishing state).

The threshold temperature T ₀ and the threshold cooling rate V _T0 may be appropriately determined depending on the equipment conditions of gas species such as flare stacks 1 and combustion target threshold temperature T ₀ and the threshold cooling rate V _T0 performed experiments in advance Should be set for each.

Since the ignition determination method according to the present invention goes through the measurement step S10 and the determination step S20 described above, the ignition state of the pilot burner used for the flare stack can be accurately determined.

<Verification>
The effect of the ignition determination method according to the present invention will be verified with reference to the time course of the ambient temperature in the pilot burners shown in FIGS. 3 to 5. In FIGS. 3 to 5, changes in the ambient temperature of the pilot burner in the flare stack of the steelworks with time are measured. The pilot gas at this time is coke oven gas, and the emitted gas is blast furnace gas. Further, similarly to FIGS. 1A and 1B described above, pilot burners 11, 12, 13, and 14 (No. 1, No. 2, No. 3, and No. 4 in the graph, respectively) are provided around the main burner 30. Four are arranged, and measuring instruments 21, 22, 23, 24 are provided around the pilot burners 11, 12, 13, and 14, respectively. Each measuring instrument was a thermocouple type temperature measuring instrument, and continuously measured the ambient temperature of each pilot burner every second. When the threshold temperature T _{0 is set} to 300 ° C. and the absolute value of the threshold temperature lowering rate _{VT 0} per second is set to 2.5 ° C./s, is it possible to accurately determine ignition / non-ignition? , Verify below.

<< Immediately after the start of ignition >>
FIG. 3 is a graph of the temperature around the pilot burner immediately after the start of ignition of the pilot burner. Immediately after the start of ignition of the pilot burners, the temperature continues to rise, and the ambient temperature of each pilot burner sequentially exceeds the threshold temperature of 300 ° C. Since the decrease in the temperature around the pilot burner is not observed at this stage, the ambient temperature and the rate of decrease in temperature satisfy the above two conditions after 120 seconds at the latest. Therefore, it can be determined that all the pilot burners are in the ignition state. After passing through this determination, it can be said that it is possible to start the combustion emission of the emitted gas.

<< After a certain period of time >>
FIG. 4 is a graph of the temperature around the pilot burner after a predetermined time has elapsed from the start of ignition of the pilot burner. In all of the No. 1, No. 2, No. 3 and No. 4 pilot burners, their ambient temperature always exceeds the threshold temperature of 300 ° C. However, it is observed that the ambient temperature may rise or fall. For example, in the time zone surrounded by the broken line in FIG. 4, although the temperature drops in the ambient temperature of the No. 2 pilot burner, the maximum temperature drop rate (absolute value) is 1.8 ° C./s, which is the threshold temperature drop rate. It is within the range of (2.5 ° C./s). The maximum temperature lowering rates (absolute values) of the pilot burners No. 1, No. 2, No. 3, and No. 4 in FIG. 4 are 1.8 ° C./s, 1.5 ° C./s, and 1 in order. .1 ° C / s, 1.8 ° C / s. Even at this stage, since the ambient temperature and the temperature lowering rate satisfy the above two conditions, it can be determined that all the pilot burners are always in the ignition state.

<< When extinguishing a fire >>
FIG. 5 is a graph of the temperature around the pilot burner when the pilot burner is intentionally extinguished. All of the pilot burners No.1, No.2, No.3, and No.4 start to cool down rapidly after the start of extinguishing the fire, and quickly lower the threshold temperature V before reaching the threshold temperature (300 ° C.). _{Since it} is out of the range of T0, it can be determined that the condition 2 is unsatisfactory and therefore the non-ignition state is satisfied. Immediately after extinguishing the fire of the pilot burner, the temperature lowering rate becomes maximum, and the maximum temperature lowering rate (absolute value) is 3.6 ° C./s, 3.4 ° C./s, 3.5 ° C./s, 3.1 ° C./s, respectively. Is. Since the temperature lowering speed at the time of extinguishing is significantly different from the temporary temperature lowering speed illustrated in FIG. 4, it is possible to distinguish between ignition and non-ignition of the pilot burner. Further, as shown in FIG. 5, the ambient temperature exceeds the threshold temperature for about 200 to 300 seconds after the pilot burner is extinguished. Therefore, assuming that the ignition of the pilot burner is restarted after the fire is extinguished and before the ambient temperature falls below the threshold temperature, it is determined whether the ambient temperature is lowered due to intentional fire extinguishing or the temperature is lowered during ignition. It is also possible to make an accurate judgment.

From the above verification results, it can be confirmed that the ignition state of the pilot burner used in the flare stack can be accurately determined by the ignition determination method according to the present invention.

When the flare stack 1 has a plurality of pilot burners 10 (N, N is an integer of 2 or more) as in the above verification, 1 out of N pilot burners 10 is allowed from the viewpoint of allowing exceptions. It is also preferable to perform the determination step S20 on the number of (N-1) or less pilot burners. Further, it is also preferable to perform the determination step S20 on N / 2 pilot burners (however, if the numerical value becomes a decimal number, the number is incremented), and the exception is only one pilot burner (that is, (N-1). ) The determination step S20 is performed on the pilot burners). In either case, the number of pilot burners to be determined may be determined so as to ensure safety according to the surrounding environment of the equipment such as the wind direction and the air volume.

As the pilot gas in the flare stack 1, propane gas, city gas (usually containing methane as a main component), or the like can be used in addition to the coke oven gas mentioned in the previous verification. Further, as the emitted gas, in addition to the blast furnace gas mentioned above, for example, if the pilot gas is propane gas or city gas, coke furnace gas or the like can be used. Although it is common to use a gas that is easier to burn than the emitted gas as a pilot gas, the present invention is not limited to these specific examples. Since the coke oven gas contains tar, it is more preferable to use city gas as the pilot gas when the pilot burner is repeatedly ignited and extinguished.

(Combustion emission control method)
Next, the combustion emission control method according to the present invention will be described. In one embodiment of the combustion emission control method according to the present invention, the first step of determining the ignition of the pilot burner by using the ignition determination method described above, and the emission gas when it is determined that the pilot burner is ignited. Includes a second step of combusting and dissipating. FIG. 6 shows a flowchart in the case of starting the ignition of the pilot burner (or restarting the ignition after extinguishing the fire). When the combustion emission command of the emitted gas is issued, the ignition command is issued to the pilot burner before the actual combustion emission is started. If it is determined that the pilot burner is ignited by the first step, the combustion emission of the emitted gas is started by the second step. If it is determined that the pilot burner is not ignited, the pilot burner is ignited again and an ignition command is given to the pilot burner until it is determined that the pilot burner is ignited. After it is finally determined that the pilot burner is ignited, the combustion emission of the emitted gas is started. As described above, according to the combustion emission control method according to the present invention, it is possible to start the combustion emission of the emitted gas after accurately determining the ignition state of the pilot burner.

(Ignition judgment device)
Refer to FIGS. 1A and 1B described above again. The same reference numerals are given to the duplicated configurations, and the duplicated description will be omitted. The ignition determination device 100 according to an embodiment of the present invention includes a measuring device 20 and a determination unit 60. The ignition determination device 100 is used for the flare stack 1 including the pilot burner 10 and the main burner 30 that burns and dissipates the emitted gas by the pilot burner flame 80 that ignites the pilot burner 10. The measuring device 20 is provided around the pilot burner 10, determine the cooling rate V _T per unit time of the peripheral temperature T and the ambient temperature T of the pilot burner 10. Further, the determination section 60, (i) and the ambient temperature T exceeds the threshold temperature T _0, and, within the absolute value absolute value of the threshold cooling rate VT ₀ of (ii) cooling rate V _T Based on the fact that there is, it is determined that the pilot burner 10 is in the ignition state. Similar to the ignition determination method according to the present invention described above, the ignition determination device according to the present invention can accurately determine the ignition state of the pilot burner used in the flare stack.

The determination unit 60 can be composed of a computer or the like including a processor, a memory, and the like. Further, it is also preferable that the determination unit 60 determines that the combustion emission of the emitted gas can be started when the pilot burner 10 is determined to be in the ignition state. Further, if the determination unit 60 determines that the pilot burner 10 is not in the ignition state when there is a combustion emission command for the emitted gas, the determination unit 60 cannot start the actual combustion emission of the emitted gas, so that the pilot burner 10 is ignited. It is also preferable to give an ignition command to restart. Further, the determination unit 60 controls the shutoff valves 41, 51 and the flow rate adjusting valves 42, 52 to control the ignition and extinguishing of the pilot gas by the pilot burner 10 and the ignition and extinguishing of the emitted gas by the main burner 30. You may. When the combustion and emission of the emitted gas is completed, the flow rate adjusting valve 52 of the emitted gas pipeline is closed, and then the flow rate adjusting valve 42 of the pilot gas pipeline 40 is closed to extinguish the fire.

According to the present invention, it is possible to provide an ignition determination method capable of accurately determining the ignition state of the pilot burner used in the flare stack, and to provide a combustion emission control method in the flare stack using the determination method. can. Furthermore, the present invention can provide an ignition determination device capable of accurately determining the ignition state of the pilot burner used in the flare stack.

1 Flare stack 10 Pilot burner 20 Measuring instrument 30 Main burner 40 Pilot gas pipeline 50 Dissipated gas pipeline 60 Judgment unit 71 Tower 72 Tower upper 80 Pilot burner flame 90 Main burner flame 100 Ignition judgment device

Claims (4)

Pilot burner that ignites the pilot burner This is a method for determining the ignition of the pilot burner used in the flare stack that burns and dissipates the emitted gas from the main burner by the flame.
A measurement step for determining the ambient temperature of the pilot burner and the rate of temperature decrease of the ambient temperature per unit time, and
(I) Judgment that the pilot burner is in an ignition state when the ambient temperature exceeds the threshold temperature and (ii) the absolute value of the temperature lowering rate is within the absolute value of the threshold temperature lowering rate. Process and
An ignition determination method comprising. The flare stack includes N pilot burners (N is an integer of 2 or more).
The ignition determination method according to claim 1, wherein the determination step is performed on one or more (N-1) or less of the N pilot burners. The first step of determining the ignition of the pilot burner by using the ignition determination method according to claim 1 or 2.
The second step of performing combustion emission of the emitted gas when it is determined that the pilot burner is ignited, and
A combustion emission control method comprising. An ignition determination device for a pilot burner used in a flare stack, comprising a pilot burner and a main burner that burns and dissipates emitted gas by a pilot burner flame that ignites the pilot burner.
A measuring instrument provided around the pilot burner to determine the ambient temperature of the pilot burner and the rate of temperature decrease of the ambient temperature per unit time.
The pilot burner is in an ignited state based on (i) that the ambient temperature exceeds the threshold temperature and (ii) that the absolute value of the temperature lowering rate is within the absolute value of the threshold temperature lowering rate. Judgment unit that determines that
An ignition determination device.

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