Stabilizer for three rounds of hydrogenation of slurry-bed residue”

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The “stabilizer” in three rounds of hydrogenation of slurry-bed residue: The slurry-bed residue hydrogenation reactor relies on the kinetic energy of the rising gases (cyclic hydrogen and reaction products) to achieve solid suspension and mixing. Based on the properties of these gases, the reactor is divided into a bubble dispersion zone (initial zone), a turbulent bubbling zone (reaction zone), and a surging zone (delay zone). Within the reactor, the rising gases gradually coalesce into large bubbles; surging phenomena occur between the upward-moving gas and the slurry in the middle and upper parts of the reactor, resulting in severe periodic fluctuations in bed density, pressure, temperature, and material circulation. In the middle of the reaction zone, gas accumulation and expansion take place, while liquid slides downward; there is a radial density gradient with higher density at the walls and lower density at the center, as well as a gradient for hydrogen with lower concentration at the walls and higher concentration at the center. This leads to abnormal temperature increases due to thermal cracking coupled with olefin saturation hydrogenation, forming a thicker solid layer in the middle and upper parts of the reactor, which severely affects reaction efficiency and stability. In the slurry bed reactor, the third stage of hydrogen injection involves the supplemental introduction of small bubbles of low-temperature hydrogen (smaller than those used in the first stage of hydrogen injection; the inner diameter of the injection nozzles is 4 mm). This is a precise intervention aimed at suppressing surge phenomena, enhancing heat transfer, and stabilizing operation; it acts as a \"stabilizer\" to ensure the reactor can operate smoothly over long periods under harsh conditions. Core function 1: The injection of hydrogen at low temperature increases the bubble number density within the bed, breaking up large bubbles that could combine to form air slugs into smaller, more dispersed groups of bubbles, thereby transforming the bed flow from a state of intense surging to a more stable bubbling or turbulent flow pattern. Core function 2: It absorbs local heat, acting as a \"micro-cooler\" to effectively stabilize temperature fluctuations and prevent the formation of local hot spots as well as an increase in side reactions caused by uneven gas-solid contact and unstable flow. Core function 3: Optimize the axial and radial gas holdup distribution in the reactor, achieve more stable bed expansion and more consistent interphase contact, improve the mass transfer efficiency of hydrogen activation effluents, and reduce catalyst deactivation caused by adsorption on coke and increased layering due to flow instability. Therefore, the design of the three-stage hydrogen distributor is crucial, as it is necessary to ensure that the injected hydrogen forms small bubbles of appropriate size and uniform distribution. The injection location, hydrogen temperature, and flow rate need to be closely integrated with the reactor’s overall thermal balance and fluid dynamics model to avoid causing excessive disturbances to the main reaction conditions. In summary, adding hydrogen three times in the slug zone of a slurry-bed residue hydroprocessing reactor is a sophisticated operation based on a thorough understanding of fluid dynamics, and it represents an active method for controlling the flow field and temperature. Its core value lies in \"achieving a significant improvement in the overall operational stability, safety, and efficiency of the reactor through reduced energy and material inputs.\" Its core technology lies in \"achieving stability of macroscopic systems through precise control of microscopic perturbations.\" ”