Heating furnace interlock duration
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The petrochemical plant is currently undergoing SIS interlock upgrades, one of which involves an interlock that shuts down the main fuel supply when the furnace pressure remains abnormally high. I have set the duration to 5 seconds; what determines this time? Are there any regulatory requirements, or is it necessary to calculate it? How is it calculated? The furnace pressure interlock value is set at 50 Pa (for negative-pressure furnaces). How was this value determined? Is it provided by the furnace manufacturer? Thank you all
The high-high interlock value and delay time for the furnace negative pressure must be provided by the heater manufacturer, confirmed by the design institute, and determined based on actual production conditions. Relevant requirements are specified in NFPA 85-2015 Boiler and Combustion Systems Hazards Code. 1. The high negative pressure in the furnace serves to prevent abnormal situations caused by tube ruptures, damper failures, or explosions. 2. It prevents short-term fluctuations and allows for a delay. 3. Interlock for high negative pressure in the furnace and subsequent actions
The negative-pressure heating furnaces I’ve encountered (tubular furnaces, steam superheaters, startup furnaces, those with equal light and heavy loads) do not have overpressure (positive pressure) interlocks – what type of furnace is yours?
Refer to the \"Guidelines for the Setting of Interlock Protection Systems in Tubular Heating Furnaces in Sinopec’s Refining Units\", which states that, unless otherwise specified, all signals that trigger interlocks should remain active for 1 second before an interlock is activated. However, regarding the 5-second setting, this may need to be determined based on the specific conditions of the device and safety assessments.