JPS5849764B2 - grand flare - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ground flare, and its purpose is to prevent the release of unburned gas and the explosion of the ground flare caused by the release of unburned gas.

A ground flare is a device that completely burns and incinerates flammable and toxic process gases released from safety valves in various plants such as oil refining, petrochemical, iron and steel manufacturing.

Due to its nature, ground flares have rapid load fluctuations.
If the treated gas is directly introduced into the furnace, black smoke will be generated due to a lack of combustion air, the flame will blow out due to a sudden drop in the gas amount (below the control range of the burner), and unburnt gas will be released due to this. Abnormal vibrations and noise occur due to emission and flame instability.

Therefore, in conventional ground flares, to solve this problem, by equipping the gas piping with an automatic valve,
It is designed to provide a staged combustion state commensurate with the amount of gas to be processed.

A conventional ground flare and its system will be explained based on FIGS. 1 and 2.

Reference numeral 1 denotes a ground flare, which has burner assemblies 2, 3, and 4 in multiple stages.

That is, the burner assemblies 2, 3, 4 include a plurality of burners 2A,
3A and 4A are arranged in an annular shape, and the burner assemblies 2, 3, and 4 of each stage are arranged concentrically.

The number of individual burners forming each burner assembly 2, 3, 4 ranges from tens to hundreds.

Therefore, attaching a pilot burner to each of the burners 2A, 3A, and 4A increases pilot gas consumption.

Therefore, in general, one to several dozen pilot burners 5 are attached to the first stage burner assembly 2, and when processing gas is released from the plant side, the pilot burners 5 are first attached to the first stage burner assembly 2. The burner assemblies 3 and 4 from the second stage onwards are sequentially ignited by the burner assembly 2 at the previous stage.
, 3 is adopted.

On the other hand, the processing gas is introduced into the burner assemblies 2, 3.4 at each stage through separate processing gas introduction pipes that are connected in a branched manner to a processing gas conduit 6 from a plant safety valve (not shown), etc. 7
This is done via A, 7B, and 7C.

In these processing gas introduction pipes 7A, 7B, and IC,
Pressure detectors 8A and 8B are interposed in the first stage and the second stage (pre-final stage), respectively, and automatic valves 9A and 9B are interposed in the second stage and the final stage, respectively.

Each automatic valve 9A, 9B has a pressure detector 8A in front of it.
, 8B, opening and closing are controlled by signals from , 8B.

That is, the processing gas released from the plant first flows through the first-stage processing gas introduction pipe 7A and is burned in the first-stage burner assembly 2.

When the internal pressure of the first-stage processing gas introduction pipe 7A increases due to an increase in the amount of processing gas, this is automatically detected by the pressure detector 8A.
Automatic valve 9A is then opened.

Therefore, the process gas is combusted both in the first stage burner assembly 2 and in the second stage burner assembly 3.

Similarly, if the amount of gas to be processed further increases, the automatic valve 9B
is opened and the process gas is combusted in burner assemblies 2, 3.4 of all stages.

On the other hand, when the amount of processing gas decreases, the automatic valve 9 interposed in the final stage processing gas introduction pipe IC is adjusted according to the amount of decrease.
Starting from B, the automatic valves 9A in the preceding stages are closed.

Note that 10 is a shield ram interposed in the processing gas conduit 6 to prevent flashback.

Such conventional systems potentially have the following drawbacks:

(1) Automatic valve 9 interposed in the third stage processing gas introduction pipe IC
If automatic valve 9B does not close due to some kind of trouble, and gas is re-released in a state where automatic valve 9B does not close due to a malfunction, the process gas will be transferred to the first stage burner assembly 2.
, flows only to the third stage burner assembly 4 and does not flow to the second stage burner assembly 3.

Therefore, the third-stage burner assembly 4 cannot receive the fire from the second-stage burner assembly 3, so a large amount of the process gas is released into the furnace in an unburned state, and if the furnace is full, posing a risk of explosion.

(2) If the automatic valves 9A and 9B do not open due to some kind of trouble If the automatic valves 9A and 9B do not open, the back pressure of the safety valve on the plant side may increase and the safety valve may not operate properly, resulting in a plant explosion. There is a possibility of an accident occurring.

The present invention has been made in view of the above-mentioned drawback (l) among the conventional drawbacks, and an embodiment thereof will be described below with reference to FIGS. 3 and 4.

11 is a ground flare, and 12, 13, and 14 are a first-stage burner assembly, a second-stage burner assembly, and a third-stage burner assembly, respectively.

As is clear from FIG. 4, the first-stage burner assembly 12 has burners arranged in a cross shape inside the furnace of the ground flare 11, and the third-stage burner assembly 14 has the first-stage burner assembly 12 arranged in a cross-shaped manner inside the furnace of the ground flare 11. Each burner is arranged in an annular shape including 12 outermost burners 12A, and the second stage burner assembly 13 is arranged between the first stage burner assembly 12 and the third stage burner assembly 14. The assembly 12 is arranged in an annular shape including the intermediate burner 12B.

A pilot burner 15 is installed near the burner 12C located at the center of the furnace or near each of all first-stage burners.

According to this burner arrangement, even if the process gas does not flow to the second stage burner assembly 13 due to a failure of the automatic valve 9A, the third stage burner assembly 14 is ignited by the burner flame of the first stage burner assembly 12. I am forced to do it.

Even when the burner assembly is configured in three or more stages, the same effect can be achieved based on the arrangement shown in the illustrated example.

16 is an automatic valve 9 interposed in the second stage processing gas introduction pipe 7B.
This is a bypass line extending from the inlet side to the outlet side of A, and a water sealing device 17 is interposed in this bypass line 16.

Reference numeral 18 denotes a bypass line extending from the inlet side to the outlet side of the automatic valve 9B interposed in the third stage process gas introduction pipe IC, and a water sealing device 19 is interposed in this bypass line 18.

The two water sealing devices 17 and 19 each include drums 17A and 19A filled with water, and inlet pipes extending from the inlet sides of the automatic valves 9A and 9B and inserted at fixed depths L and t into the filled water. 16A, 18A, and outlet pipes 16B, 18B.

In this way, if the automatic valve 9A fails to open, for example, the water seal of the water seal device 17 is broken and the process gas flows to the second stage burner assembly 13 through the bypass line 16.

If the automatic valve 9B fails and does not open, the water sealing device 19 operates in the same manner.

If the amount of gas to be processed decreases, there is no problem because the water seal is maintained when the pressure falls below the set pressure of the water seal devices 17 and 19.

The set pressure for opening and closing automatic valves 9A and 9B is 300 to 800WrrrLAq due to the back pressure of the safety valve on the plant side and the performance of the burner.
Closing setting pressure 10-100Trr! rLA
It is set to q.

When the processing gas flows through the water seal devices 17 and 19 under these conditions, when the gas amount decreases, the water seal devices 17 and 19 flow. 1
After 9, the gas pressure becomes less than 10mmAq, causing abnormal vibration,
There is a risk that abnormal noise may occur, but this vibration noise does not cause any harm to the equipment, only lasts for a very short time, and only occurs once every few years, so it is not a problem. As is clear from the above description, the present invention prevents unburned gas from being released from burner assemblies in each stage and from filling the furnace with unburned gas, which poses the risk of explosion. This can be prevented.

[Brief explanation of the drawing]

Figures 1 and 2 show conventional examples; Figure 1 is an explanatory diagram;
The figure is a burner arrangement diagram, FIGS. 3 and 4 show embodiments of the present invention, FIG. 3 is an explanatory diagram, and FIG. 4 is a burner arrangement diagram. 6... Processing gas conduit, 7A, 7B, 7C...
... Processing gas inlet pipe, 8A, 8B... Pressure detector, 9A, 9B... Automatic valve, 11...
・Ground flare, 12, 13, 14... Burner assembly, 12A... Outermost burner, 12B.
...Middle burner, 15...Pilot burner, 12C...Central burner.

Claims (1)

[Claims] 1. The first stage burner assembly is arranged in a cross shape, and the burner assembly of each stage is arranged in a ring shape so as to include at least one burner guarding this first stage burner assembly, and the pilot A ground flare characterized in that a burner is provided near the initial stage burner assembly.