how to start the fired heater?

To start a heater, follow these steps:

1. Check start permissives: Verify that all start permissives or interlocks are in the correct state, indicating that the necessary conditions for starting the heater are met. Ensure that fuel gas pressure, combustion air flow, heater box pressure, heater temperature, steam drum level, and stack temperature are within acceptable ranges.
2. Reset the system: Reset the heater system from the DCS (Distributed Control System) and also manually from the field. This step ensures that all interlocks are functioning properly.
3. Check start permissives again: After resetting the system, recheck all start permissives to confirm that they are still within the acceptable range. For natural draft heaters, keep the stack dampener fully open. For forced draft heaters, start the FD fan, and for induced draft heaters, start the ID fan. Balanced draft heaters have both an FD fan and an ID fan.
4. Purge the heater: Purge the heater for approximately 5 minutes to remove any flammable gases or fluids that may be present before ignition. This is especially important for safety.
5. Start the pilot: Line up the pilot fuel gas and air supplies, and ignite the pilot by pressing the pilot "ON" button. Ensure that the pilot light is burning steadily before proceeding.
6. Light the main burner: Once the pilot is successfully lit, line up the main burner fuel gas and air supplies, and ignite the main burner by pressing the main burner "ON" button. Ensure that the main burner light is steady and not flickering.
7. Increase the temperature gradually: Gradually increase the heater temperature at a rate of 25°C per hour. This gradual increase helps prevent thermal shock to the heater and allows for a smooth startup of operations.

It is important to note that these steps provide a general guideline, and the specific startup procedure may vary depending on the type and model of the heater. Always follow the manufacturer's instructions and any applicable safety guidelines or procedures provided by your organization.