【Q&A Question 147】2016.09.14
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【Q&A Question 147】September 14, 2016: After stopping the water supply to the reaction, with the operating conditions remaining unchanged, how will the reaction depth change? Why? The answer key will be available after responding; scoring is based on answering the key points. The main purpose of injecting water into the reactor is to dissolve and carry away the ammonium salts present in the air-cooled tube bundles. If this injection is stopped, some of the hydrogen sulfide and most of the ammonia will not be absorbed, and thus they will be returned to the reactor. This leads to nitrogen poisoning of the refining catalysts and cracking catalysts, resulting in a decrease in their activity, a drop in the temperature of the reactor bed, and a reduction in the degree of reaction. Stopping the water supply for an extended period will increase the nitrogen content in the refined oil at the outlet of the refining reactor, as the nitrogen element in the oil cannot be removed.
After stopping the addition of water to the reaction, the reaction depth decreases even if the operating conditions remain unchanged. This is because: hydrocracking catalysts are bifunctional catalysts, possessing both hydrogenation and cracking functions...
It has little impact on the reaction. The purpose of water injection is to remove ammonium salts and reduce the system pressure drop.
Decline: After the water injection is stopped, the salts that precipitate cannot be carried away by water; this affects the heat exchange efficiency, reduces the inlet temperature of the reactor, and leads to a decrease in the degree of reaction
After stopping the addition of water to the reaction, the reaction depth decreases even if the operating conditions remain unchanged. This is because hydrocracking catalysts are bifunctional catalysts, possessing both hydrogenation and cracking capabilities. It is the acidic sites on these catalysts that enable the cracking function; these acidic sites readily adsorb the basic NH3. After the water supply to the reaction is stopped, the ammonia content in the recycle hydrogen increases significantly, and a large amount of NH3 gets adsorbed onto the acidic sites of the catalyst. As a result, the number of active acidic sites available for reacting with the oil products decreases, leading to a reduction in the overall activity of the catalyst. If the temperature of the catalyst bed is not increased, the depth of the reaction will decrease as well. At the same time, the presence of ammonia inhibited the occurrence of secondary reactions, reducing the formation of gaseous products.
Decrease; system pressure drop increases, and the purity of recycled hydrogen decreases
The reaction depth will increase, as the injection of water leads to a decrease in the heat exchange temperature; once the water injection stops, the temperature rises, and this heat exchange causes the reactor temperature to increase, which naturally results in an increased depth
The main purpose of injecting water into the reactor is to dissolve and carry away the ammonium salts present in the air-cooled tube bundles. If this injection is stopped, some of the hydrogen sulfide and most of the ammonia will not be absorbed, and thus they will be returned to the reactor. This leads to nitrogen poisoning of the refining catalysts and cracking catalysts, resulting in a decrease in their activity, a drop in the temperature of the reactor bed, and a reduction in the degree of reaction. Stopping the water supply for an extended period will increase the nitrogen content in the refined oil at the outlet of the refining reactor, as the nitrogen element in the oil cannot be removed.
The main purpose of injecting water into the reactor is to dissolve and carry away the ammonium salts present in the air-cooled tube bundles. If this injection is stopped, some of the hydrogen sulfide and most of the ammonia will not be absorbed, and thus they will be returned to the reactor. This leads to nitrogen poisoning of the refining catalysts and cracking catalysts, resulting in a decrease in their activity, a drop in the temperature of the reactor bed, and a reduction in the degree of reaction. Stopping the water supply for an extended period will increase the nitrogen content in the refined oil at the outlet of the refining reactor, as the nitrogen element in the oil cannot be removed.
After stopping the addition of water to the reaction, the reaction depth decreases even if the operating conditions remain unchanged. This is because hydrocracking catalysts are bifunctional catalysts, possessing both hydrogenation and cracking capabilities; it is the acidic centers on these catalysts that enable the cracking function. These acidic centers readily adsorb the basic NH3. After the water supply to the reaction is stopped, the nitrogen content in the recycle hydrogen increases significantly, and a large amount of NH3 gets adsorbed onto the acidic centers of the catalyst. As a result, the number of active acidic centers available for reacting with the oil products decreases, leading to a reduction in the overall activity of the catalyst. If the temperature of the catalyst bed is not increased, the depth of the reaction will decrease. At the same time, the presence of ammonia inhibits the occurrence of secondary reactions, reducing the formation of gaseous products.
It decreases; after water injection, the purity of the circulating hydrogen drops, there is an increase in debris, pipeline blockages occur, and the pressure drop increases