What are the device interlocks?

Interlock for power outage of the catalytic unit, interlock for shutdown of the main fan, interlock for shutdown of the air compressor, interlock for shutdown of the booster pump.

Interlock for high compressor shaft vibration value, Interlock for high compressor bearing temperature, Interlock for compressor surge, Interlock for low compressor lubricating oil pressure

The catalytic reforming unit has a pre-hydrogenation hydrogen mixing interlock value of 2000 standard cubic feet, and a first-stage reforming hydrogen mixing interlock value of 7500 standard cubic feet.

Routine interlock items for the heating furnace: 1) Low fuel pressure interlock – The fuel pressure is below the level necessary to maintain stable combustion in the burner. (When the pilot light pressure is below 0.07 MPa, the main fuel gas burner, the pilot light, and the fuel oil burner solenoid valves are turned off, causing the heating furnace to shut down.) ) 2) Low feed rate interlock: The heating furnace stops automatically when the flow rate in the furnace tubes falls below the set interlock value. (Shut off the fuel gas burner and fuel oil burner solenoid valves.) ) 3) Burner shutdown interlock: For small heating furnaces that lack a reliable low fuel gas pressure interlock and are not monitored regularly, it is advisable to use two-way confirmation flame detectors. These detectors allow for automatic shutdown when the burner stops burning, thereby preventing false alarms caused by the failure of a single flame detector and enhancing the safety and reliability of the system. 4) Low atomization steam pressure interlock: When fuel oil is used, a low atomization steam pressure can cause the flame to weaken or even go out. (The atomized steam pressure is below 0.35 MPa; the fuel oil solenoid valve is closed, and the oil burner goes out.) ) 5) Interlock failure of the smoke and air ventilation system: For heating furnaces equipped with forced ventilation equipment (blowers, exhaust fans) and air preheaters, the furnace must be shut down and the fire extinguished in case of a fan failure, unless the furnace can operate under natural ventilation or with positive pressure in the furnace chamber. If natural ventilation operation is permitted, forced ventilation can be switched to natural ventilation by opening the quick-opening damper located on the hot air duct in front of the forced-ventilation burner, thereby ensuring that the heating furnace can continue to operate.

Interlocks in catalytic cracking units: 1. Interlocks related to the compressor station, such as displacement, low oil pressure, and the differential pressure between the high-pressure and low-pressure sides of the dry gas seal. 2. Interlocks related to the main fan station. Such as displacement, low oil pressure, etc. 3. Interlocks for the reaction unit: main air protection, differential pressure protection, feed protection, etc

In domestic oil refining plants, interlocks are generally few in number and are mainly installed on large-scale units. These interlocks monitor parameters such as vibration and displacement of the units, lubricating oil temperature and pressure, outlet pressure and temperature, inlet pressure and temperature, as well as the liquid level in the separation tank. Process interlocks are usually placed in hazardous areas such as heating furnaces； In chemical process design, there are many process interlocks; for example, a polypropylene plant has dozens of such interlocks, and some operations are even carried out automatically as a result of these interlocks.