Lifting \"heavy\" loads as easily as in the slurry bed reactor RTMCS of refining technology

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In slurry-bed residue hydrogenation, there are 114 thermocouples (LOW, A-H, TOP) on the axial direction inside each reactor, and 39 thermocouples (BTM, A-H, TOP) on its outer surface. The use of multiple thermocouples is intended to provide a comprehensive assessment of the reaction progress inside the reactor as well as the homogeneity of the slurry distribution. Reactor temperature control is achieved through an integrated RTMCS, which includes a Reactor Temperature Management System (RTMS), a Reactor Temperature Control System (RTCS), and a Reactor Temperature Interlock System (RTSS). I. RTMS: Displays and monitors all temperature signals of the reactors, calculates the average temperature for each reactor, and compares all internal thermocouples with this average temperature. When the measured value deviates from the set average temperature of the reactor by more than ±10°C, an alarm (high or low) is generated, which is indicated through a change in color. The average temperature per ring is calculated and compared with the temperature of each thermocouple within that ring; an alarm (high or low) is generated when the deviation between the measured value and the average temperature in the ring exceeds ±10°C, and this is indicated through a change in color. For all thermocouples, temperature change rate and primary/secondary temperature difference alarms are set; the change rate alarm is set at 3°C/min ； An alarm is triggered when the temperature difference between the primary and backup units exceeds 5°C. The activation/disactivation of the alarm can be switched manually. High surface temperature alarm: To monitor the gas distribution at the bottom of the reactor, alarms are triggered when the surface thermocouples in rings BTM1 and BTM2 exceed 424°C, while alarms are triggered when the surface thermocouples in rings B, C, D, E, F, G, H, and the top ring exceed 445°C. II. RTCS: Each reactor is equipped with a temperature reaction controller, which uses the average reactor temperature as the control value. Controlling the temperature of the recycle hydrogen serves as the key control method; by regulating the fuel supply to the recycle hydrogen heater, the outlet temperature of this heater is controlled, thereby regulating the average reactor temperature. To avoid reaction delays and disturbances, the maximum allowable rate of change for the recycle hydrogen temperature is set at ≯±10°C/h. III. RTSS: An interlocked control SIS for the internal temperature and outer surface temperature of the reactor, designed to prevent runaway heating within the reactor and excessive temperatures on its walls, thereby averting serious accidents such as coking reactions inside the reactor and equipment damage. IV. Reactor temperature control also includes monitoring the temperature trend of the outer bottom wall, in order to control the level of the second liquid phase at the bottom and the degree of coking ； Including the assessment of hydrogen distribution uniformity and the possibility of external welding based on the temperature deviation of the LOW loop at the secondary hydrogen outlet ； This includes using the temperature difference at the top of the reactor to determine whether a foaming zone has formed ； Include determining whether full-flow conditions exist by checking the temperature at the upper part of the overflow pipe and its deviation from that in the reactor ； Including the original start-up reactor heat loss temperature difference records ； This includes determining the condition of flexible thermocouples, whether there is any external leakage, and so on. Regarding the temperature management in the slurry bed reactor, the SIS system has been practically fully utilized; the temperature control system has not been set to automatic mode, and its monitoring function is effective. However, the requirement of maintaining a temperature difference of 10°C was not strictly followed, which prevented timely process interventions. Additionally, doubts were sometimes expressed regarding the accuracy of the instruments. Changes in the properties of the process materials and abnormal gas distribution are the main reasons for variations in the reactor’s temperature parameters.