After changing the residual feedstock to the dry gas of the refinery, as in the pre-retrofit, all relevant process variables (such as temperature, pressure, flow and valve position) are controlled by the safety protection system in order to ensure safe operation of the plant. The system checks the selected process variables to see if they are in the correct range. If the relevant parameters are not within the correct range, the system will prompt the operator. When some parameters or valve position feedback information does not match the design during heating or driving, the system will terminate the heating or driving process. However, during normal operation, the parking is automatically interlocked. The safety protection system automatically adapts to different commands at different stages of the device's operation. Therefore, each process variable and driving state is monitored by a separate instrumentation system that can increase the level of safety assurance depending on the operating conditions. The transformation control system is realized by the existing DCS, and the interlock is realized by using the existing PLC system. The control interlock of the compressor itself is supplied by the compressor factory. The DCS transformation is carried out inside the existing DCS, adding some card parts, and adding and modifying some configuration software. After the device is transformed into oil and gas blending, the whole residual oil can be used for driving. After the production is normal, the manual valve on the small residue oil circulation line and the refinery dry gas flow setting value FRC-11002B1 are gradually switched to the mixing. material. When the system is parked, the residue and refinery dry gas will be cut off at the same time. When the Shell slag oil and gas is changed to oil and gas blending, the transformation of the control interlock system needs to carefully analyze the safety measures under opening, stopping and different accident conditions. The above-mentioned transformation plan was completed on the basis of the successful transformation experience of the oil-to-gas automatic control system of the Lanzhou Petrochemical Shell residuum ammonia plant, but it needs to be further verified in the device driving.