Petrochemical Flares

Hi-Lo Enclosed Petrochemical Flares can be tailored to suit customer requirements.

Degassing Philosophy

Main Components

Control Cabinet

A control cabinet is fitted onto the skid incorporating a door mounted PLC. Housed in the cabinet will be a supply isolator, ignition start button, solenoid valve, control connections and feed to *ram control. Supply will be 240v 50Hz single phase via plug and socket.

Igniter

A small box is fitted nearer to the stack on the skid housing the igniter transformer, which will feed the igniter.

The igniter consists of two high voltage probes that cause an electrical short across when power is applied. A pilot gas tip forces pilot gas between the contacts hence lighting the pilot. The pilot can be a constant type or an automatic type which when the flame is established the pilot is extinguished.

Flare Tip Control

An Actuator is fitted at the base of the stack which opens/closes the tips to achieve optimum velocity. This is done manually via the control panel. The actuator gives a 4-20mA signal to indicate to the PLC the flame tip position.

Flame Establishment

This is achieved by the means of thermocouples these are rated at 0-1200°C giving a 4-20mA signal to the PLC that reads the temperature. These are plugged into a connection box fitted on the skid at the base of the stack.

*Ram Control for Self Erecting Flare Systems

A supply from the control cabinet is supplied to the ram control. The stack is then able to be raised/lowered via these controls. (This item can be fitted as an extra)

Flame Arrestors

Flame arrestors are fitted into the gas lines prior to the stack for safety reasons.

The gas flow rate emergency shutdown and pressures are the responsibility of the customer, as the Hi-Lo Flare has no control of these.

When the gas enters the unit and the line is purged satisfactorily, by pressing the ignition start button the tip control actuator is then set to a set point for starting which then opens the solenoid valve allowing the pilot gas to ignite. The igniter flashes for a set period of time and if the pilot lights it then in turn lights the main gas. The temperature rise is noted by the flame temperature thermocouple that then signals to the PLC that the flame is established. A lamp on the control cabinet indicates this. If the flame failure alarm condition lights on the door then a sounder is sounded. The system can be programmed to try to re-light a set number of times until the flame is established.

Once the flame is established the flare tip actuator open the tips to a set point for running.

Any other position required for the flare tips has to be done manually via the control panel.

Once the temperature drops below it’s set point the thermocouple indicates to the PLC that the flame is out and then alarm conditions operate.

Flue Temperature

In the stack two thermocouples are installed, one at the bottom to read the flame temperature and the other at the top to read the flue temperature. These are 0-1200°C rated and give a 4-20mA signal back to the control panel, which gives a temperature reading in °C on the display screen.

The flue temperature will be the indication for the exhaust emissions. The ideal temperature for the flue will be around 1100°C –1150°C that minimizes most emission gases. This temperature is achieved by opening and closing air vents at the base of the stack the greater they are opened the more air intake lowering the temperature.

This reading is also displayed on the display screen but does not produce any alarms.

Alarms

Alarm conditions will be by means of indication lamps on the control panel door and a flashing beacon/sounder located at a suitable position to alert the operator only (can be automated if required).

Two other lines for gas are provided which enter the bottom of the stack. These will also have the same design tip fitted but will be free floating and will not have any actuator control.

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Version: 1.0 Updated: 05/11/2002

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