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7.1 Operation methods for the reaction unit: Basic principles for operating the reaction unit: The reaction unit is one of the key components of the entire gasoline upgrading facility; stable operation of this unit is crucial for the safe production of the reaction system as well as the entire facility. Changes in the operating parameters of the reaction unit not only cause changes in the reaction system but also affect the absorption and stabilization system as well as the operating parameters of the pumps. Therefore, reaction unit operators must be familiar with the process flow of the entire plant, operate strictly in accordance with the operating procedures, select appropriate reaction conditions within the limits set by the specified parameters, maintain proper heat and mass balance, understand the basic principles and conditions of reactions, and be able to make sound judgments and adjust operational parameters as the reaction progresses and the catalyst cokes up. This ensures that production operates at an optimal level, allowing the plant to function safely, with low consumption, stability, high quality, and over the long term. Operating characteristics of the reactor: The reactor is the core equipment of the entire production facility. Its stable and safe operation not only affects the processing capacity of the facility but also determines the quality of the products produced. Therefore, the normal and stable operation of the reactor is a prerequisite for the safe and stable operation of the entire facility. After catalyst regeneration by coking or catalyst replacement, the plant enters a new production cycle. After regeneration and charring, the activity of the catalyst is restored to a large extent; however, overall its activity continues to decline. Therefore, for each start-up of production, it is necessary to maintain an appropriate temperature of the raw materials after heating in the furnace. Too low a temperature fails to meet the conditions for the reaction, while too high a temperature can cause intense reactions that result in the generation of large amounts of gaseous substances, affecting the subsequent absorption and stabilization systems as well as the pumps. Since the updated catalyst has higher activity, adjustments must be made as appropriate to ensure that the reaction proceeds while simultaneously minimizing the temperature at the furnace outlet, so that the reaction occurs in a slow and stable manner. As the reaction progresses, the molecular sieve inside the catalyst becomes clogged by the heavy carbon components formed during the neutralization reaction of the raw materials, resulting in a decrease in its activity. During the operation, the temperature at the furnace outlet must be gradually increased to meet the most basic requirements of the reaction. When the furnace outlet temperature rises to 420°C, there is no significant temperature increase inside the reactor; the olefin content in the liquefied gas exceeds 15%, the amount of dry gas is high, and the ratio of heavy C4 converted into gasoline is significantly low. This indicates that the catalyst’s activity has reached its minimum level, and it is necessary to carry out in-reactor regeneration and coking treatment on the catalyst. After N2 displacement, when the concentration of explosive gases in the reactor falls below 0.5%, air can be introduced for coking; the amount of purge air supplied is determined based on the coking temperature and degree. While burning occurs at the first layer, increasing the air supply in the second and third stages can cause heat to concentrate, leading to higher temperatures; it is necessary to closely monitor changes in temperature differences within the reactor at this time. The internal single-layer temperature is kept below 470°C to prevent the catalyst molecular sieve from being damaged due to excessive temperature. Key operating points for the reaction unit: (1) Ensure that the operating parameters of the equipment remain within the limits specified in the operational guidelines (process cards); operations must not exceed these limits. (2) During feeding, strictly control the reaction temperature to maintain a normal and appropriate level of reaction progress; it should not be too high or too low. (3) Maintain a normal and stable reaction feed rate; there should be no severe fluctuations. (4) Maintain material and heat balance in various systems, and strive to reduce energy consumption. (5) Ensure proper pressure balance among all towers and tanks to prevent pressure buildup. (6) Strictly enforce safety production regulations to ensure the safe operation of production facilities. (7) Adjust the reaction depth reasonably according to product quality, in order to minimize the dry gas production. (8) Pay attention to changes in the operating conditions of the heating furnace and reactor, make adjustments in a timely manner to prevent overheating and overpressure, and ensure continuous and stable production. (9) Pay attention to the liquid level changes in each tank; it must be strictly kept within the specified operating limits, with the level not dropping below 50% before shift handover. (10) Pay attention to the conditions at each water cut and oil injection point; carry out water cutting and oil injection at regular intervals to prevent the interface and liquid level from exceeding specified limits. (11) During winter, take proper measures to prevent freezing; pay attention to checking whether the condition of all heat tracing wires and drain points is normal. Operation control of the reaction unit: 1. Operation control of the reaction temperature: It is adjusted according to the octane number of the stable gasoline; if the octane number is low, the reaction temperature is increased. Factors affecting it: (1) Changes in the reaction feed rate ； (2) Changes in the preheating temperature of the reaction feed ； (3) Changes in the feed rate of heavy C4 ； (4) Changes in the catalyst’s ability to promote reactions (activity) ； Adjustment method: (1) Control the reaction temperature by regulating the feed rate and preheating temperature ； (2) The temperatures of the middle and lower bed layers are controlled by the amount of C4 added; (3) The feed material must be dehydrated ； (4) Closely monitor changes in catalyst activity. 2. Control of reaction pressure: Influencing factors: (1) Changes in the amount and properties of the reaction feed ； (2) Changes in furnace exit temperature ； (3) Change in reaction depth ； (4) Failure of the reaction pressure control valve ； (5) High level in D-102 or high level in D-103 ； (6) The inlet temperature of the compressor is too high or too low, causing changes in the composition at the compressor inlet ； (7) Excessive pressure application in D-104 led to air entrainment, causing an increase in the pressure in D-102 ； (8) Large pressure fluctuations in the dry gas system ； (9) Instrument failure. Adjustment method: (1) Stabilize the reaction feed rate ； (2) Coordinate with oil quality control to ensure the quality of straight-run gasoline ； (3) Stable furnace outlet temperature ； (4) Adjust the air compressor and rear operations promptly when the reaction depth changes ； (5) Change the pressure control valve to manual mode; contact the instrumentation team for repair ； (6) Lower the D-102 level or the D-103 level ； (7) Adjust the temperature of the reaction mixture in front of the pneumatic compressor ； (8) Control the backflow momentum of the air compressor to stabilize inlet pressure ； (9) Adjust the absorption temperature system to stabilize gas pressure ； (10) In case of instrument failure, switch to manual or backup control and contact relevant personnel for handling ； (11) Switch to standby pump in case of pump failure ； (12) When the reaction pressure becomes excessively high, the flare control valve at the top of the gas-liquid separation tank (D-102) is activated to regulate the reaction pressure. 3. Changes in the outlet temperature of the heating furnace: Influencing factors (1) Changes in the feed volume – an increase (decrease) in the amount fed into the heating furnace results in a decrease (increase) in the preheating temperature ； (2) Changes in the temperature and flow rate of the heavy C4 fraction feed result in variations in the proportion of straight-run gasoline, which in turn causes changes in the outlet temperature of the heater ； (3) Fuel gas flow rate: Changes in pressure, as well as an increase in flow rate or pressure, lead to an increase in the feed preheating temperature; conversely, a decrease in these values results in a decrease in the preheating temperature ； (4) Changes in fuel gas quality, heavier composition, increase in feed preheating temperature ； (5) Failure of fuel gas instrument control ； (6) Whether the flame arrester or burner is clogged. Adjustment method: (1) Under normal conditions, the feed preheating temperature is controlled by the furnace outlet temperature, and this is achieved by adjusting the amount of fuel gas; there are control circuits for fuel gas pressure and flow rate ； (2) If the pressure in the fuel gas system drops, it is necessary to contact someone for handling promptly ； (3) If the instrument or control valve fails, manual or bypass control shall be used, and the instrumentation team shall be contacted for handling ； (4) If the flame arrester is blocked, it should be diverted via a bypass line and removed. Additionally, during startup or compressor failure, the reaction pressure is controlled by the flare control valve at the top of the gas-liquid separation tank (D-102).