JPS5947802B2 - Flare stack control method - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flare stack and a control method thereof, and its purpose is to reduce pilot fuel (pilot gas) consumption in a pilot burner attached to a flare stack main burner. The purpose of this invention is to ensure that the main burner is ignited while still achieving the desired results.

Flare stacks are used to safely incinerate flammable and toxic process gases released from safety valves in plants, etc., at high places in the atmosphere.

In addition, as a recent trend, ground flares are installed in order to prevent the visible flames, black smoke, and noise pollution generated from the flare stack, and ground flares are used alone until the amount of processed gas generated exceeds a certain value. I am trying to process it.

In such equipment, the pilot burner is always kept in an ignited state in order to cope with a situation where toxic gas is suddenly released from a safety valve or the like of the plant.

Multiple pilot burners are installed around the main burner.

This is to ensure that the main burners will ignite under all weather conditions and even if some of the pilot burners are damaged, which is important as repairs are difficult during plant operation. It is.

However, keeping a plurality of pilot burners in the ignited state at all times in this way increases the amount of pilot gas consumed each year, which is often a problem as it goes against recent energy saving efforts.

The present invention has been made in view of the above, and embodiments thereof will be described below with reference to FIGS. 1 to 3.

1 is a flare stack, 2 is a ground flare, and the process gas is introduced into these by water seal drums 3,
This is done via 4.

That is, these water seal drums 3, 4 consist of drums 3A, 4A filled with water, inlet pipes 3B, 4B inserted into the water at a certain depth, and outlet pipes 3C, 4C.
The inlet pipes 3B and 4B are branched from a common conduit 5 extending from safety valves of plants, etc., and are connected to the depth A?
is set to the relationship L>l. Therefore, the processing gas that has passed through the conduit 5 first breaks the water seal of the ground flare water seal drum 4 and flows to the ground flare 2 side, and the flow rate exceeds a certain level (the ground flare 2 When the processing amount exceeds the processing amount in the flare stack water seal drum 3, the water seal of the flare stack water seal drum 3 is broken and the water flows to the flare stack 1 side.

The outlet pipe 4 of the ground flare water seal drum 4 is connected to each stage of the burner (not shown) of the ground flare 2.

) processing gas inlet pipe 6A. Connected to 6B and 6C in a branched state.

The ground flare 2 has multiple stages of burners (three stages in the illustrated example).
The number of combustion stages of the burner is increased or decreased depending on the amount of processing gas introduced.

That is, the pressure detector 7 is installed in the processing gas introduction pipe 6A leading to the first stage burner and the processing gas introduction pipe 6B leading to the second stage burner.
Automatic valves 8B and 8C are interposed in the processing gas introduction pipe 6B leading to the second stage burner and the processing gas introduction pipe 6C leading to the third stage burner.

Now, when the water seal of the water seal drum 4 is broken and the processing gas is introduced into the ground flare 2 side, the processing gas first flows through the processing gas introduction pipe 6A leading to the first stage burner and is combusted in the first stage burner.

When the amount of processed gas increases and exceeds the capacity of the first stage burner, this is detected by the pressure detector 7A, and the automatic valve 8B is opened in response to the signal.

Therefore, the process gas is combusted in the first stage burner and the second stage burner.

If the amount of gas to be processed further increases and exceeds the total capacity of the first and second stage burners, this is detected by the pressure detector 7B, and the automatic valve 8C is opened in response to the signal.

Therefore, the process gas is combusted in all the burners of the first, second and third stages.

When the amount of processing gas increases further and exceeds the capacity of the ground flare 2, the water seal of the flare stack water seal drum 3 is broken, and the processing gas in excess of the ground flare capacity flows to the flare stack 1.

The flare stack 1 has a main burner 9.

A plurality of pilot burners 10 are installed alongside the main burner 9, one of which is installed inside the main burner 9, and the rest are installed around the outside of the main burner 9 at equal angle intervals.

A pilot gas introduction pipe 11 is connected to the internal pilot burner 10A, as well as an ignition pipe 12 and a device for detecting the presence or absence of ignition, such as a thermocouple (not shown).

) is attached. An on-off valve 13 is interposed in the pilot gas introduction pipe 11.

Similarly, a pilot gas introduction pipe 14 is connected to the outer pilot burner 10B, and an ignition pipe 15 is attached thereto.

An electric valve 16 is interposed in the pilot gas introduction pipe 14.

The base ends of the two ignition tubes 12 and 15 communicate with each other, and this portion communicates with a collecting pipe 19 of the pilot gas pipe 17 and the air pipe 18.

The ignition tubes 12, 15 have ignition devices 12A, 15A.

Further, electric valves 21 and 22 are interposed in the pilot gas pipe 17 and the air pipe 18.

23 is an automatic ignition control device, which controls the internal pilot burner 10A and the external pilot burner 1.
The operating states between the 0Bs and between the ground flare 2 side and the flare stack 1 side are correlated.

Note that the internal pilot burner 10A is always in the ignition state.

In the above, when processing gas exceeding the ground flare capacity flows through the conduit 5, the excess breaks the water seal of the water seal drum 3 and flows into the flare stack 1, as described above, and flows into the internal pilot burner inside the main burner 9. It is ignited by the IOA and combusted by the main burner 9.

In this case, the automatic valve 8C of the process gas introduction pipe 6C leading to the third burner of the ground flare 2 is opened, and at the same time a signal from the pressure detector 7B is sent to the outer pilot burner 10.
B pilot gas introduction pipe 14, pilot gas pipe 17
and a motor-operated valve 16, each interposed in the air pipe 18,
21 and 22 are opened, and the ignition devices 12A and 15A are activated.

The ignition pipes 12, 1 are opened by opening the electric valve 16°21.22.
5, a gas-air mixture within the flammability limit flows and is ignited by the igniters 12A, 15A, thereby igniting the pilot gas ejected from the outer pilot burner 10B.

In order to ignite the outer pilot burner 10B, the processing gas in excess of the ground flare capacity is transferred to the flare stack 1.
completed by the time it flows into.

Therefore, the process gas ejected from the main burner 9 is ignited by both the internal pilot burner 10A and the external pilot burner IOH, and is performed safely and reliably.

An unexpected situation (
When the internal pilot burner 10A is extinguished (for example due to damage), this is detected by the thermocouple and the signal causes the electric valve 16.21.22 to open and ignite the external pilot burner 10B in the manner described above.

In this case, there will be no problem even if the internal pilot burner IOA is relit at the same time.

When the processing gas amount gradually decreases and reaches the ground flare capacity, the flare stack water seal drum 3 automatically shuts off the processing gas flow into the flare stack 1, and the three-stage burner of the ground flare 2 Upon receiving the closing signal of the automatic valve 8C interposed in the processing gas introduction pipe 6C,
The electric valve 16 is closed and the outer pilot burner IOB
extinguishes the fire.

In this embodiment, one of the plurality of pilot burners 10 is provided inside the main burner 9 and is kept in a constantly lit state, but this internal pilot burner 10A
It is also possible to omit.

As described above, according to the present invention, the pilot burner of the flare stack main burner is ignited at the same time as the processing gas is supplied to the final stage burner of the ground flare, so that when the processing gas is ejected from the main burner, it is reliably ignited. is carried out,
The amount of pilot gas disinfection is also reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the same,
FIG. 3 is an explanatory diagram of the same. 1...Flare stack, 2...Grand flare. 3... Water seal drum for flare stack, 4...
... Water seal drum for ground flare, 5 ... Conduit, 6A, 6B. 6C...Processing gas introduction pipe, 7A, 7B...
...Pressure detector, 8B, 8C... Automatic valve, 9.
...Main burner, 10... Pilot burner, 11, 14... Pilot gas introduction pipe, 12, 15... Ignition pipe, 12A, 15A.
...Ignition device, 16, 21, 22...Electric valve, 17...Pipe gas pipe, 18...
...Air pipe.

Claims (1)

[Claims] 1 A flare stack is equipped with a ground flare in which the number of combustion stages of the burner increases as the amount of processing gas introduced increases, and when processing gas exceeding the capacity of the ground flare is generated, the excess amount is introduced. 1. A control method for a flare stack, comprising starting a pilot gas supply to a pilot burner of a main flare stack burner and igniting the pilot gas at the same time as processing gas is supplied to a final stage burner of a ground flare. Control method.