【Q&A Question 089】March 30, 2017
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This post was last edited by 955559 on 2017-7-21 22:28. [Q&A Question No. 089] On 2017.03.30, under what circumstances does a hydrogenation unit require catalyst replacement, and what precautions should be taken? The reference answers will be visible after responding; points are awarded by identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) 1) Temporary replacement ； (1) Catalyst activity deteriorates, and the purification capacity drops below the minimum allowable level; temporary shutdown is required for replacement ； (2) The mechanical strength of the catalyst deteriorates, and the bed resistance exceeds the allowable value; temporary shutdown is required for replacement ； (3) In the event of a serious equipment failure that causes the catalyst to experience abnormal conditions such as prolonged overheating or temperature spikes, it is necessary to temporarily remove and replace the catalyst. 2) Preventive planned replacement ； The catalyst conversion capacity, bed resistance, and equipment performance are all within acceptable ranges. To avoid unplanned shutdowns, preventive replacements are carried out taking advantage of planned shutdown periods. 3) Principle of optimal economic efficiency. Taking into account comprehensive factors such as equipment protection, increased production and cost savings, as well as optimal economic benefits, replacements are carried out in a planned manner in advance. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html Third Phase of HaiChuan’s Outstanding Management Members Selection Contest http://bbs.hcbbs.com/thread-1655902-1-1.html (Source: HaiChuan Chemical Forum)
The catalyst reaction temperature has reached the designed value； The catalyst is severely coked ； The pressure drop across the catalyst bed has reached the design value. When replacing the catalyst, a nitrogen atmosphere is maintained inside the reactor; the removed catalyst is placed in a dedicated container and sealed to prevent spontaneous combustion.
Increasing the reaction temperature had no effect on the reaction effluent; increasing the pressure also had no effect. The pressure drop across the bed was very high, and the bed collapsed
Raising the temperature does not improve the desulfurization efficiency; the pressure difference across the reactor bed is too high, and the catalyst suffers severe coking
Pay special attention during loading； 1. To prevent the catalyst from getting damp, it should be loaded on a sunny day. 2. Remove debris from the furnace and check whether the inner walls, refractory bricks, grates, etc. are in good condition. 3. Lay a stainless steel wire mesh on the grate, distribute the refractory balls evenly, and mark a line at the desired filling height. 4. Prepare the loading tools and protective equipment. 5. It should be sieved before loading to remove dust and broken particles. 6. The height difference for loading should be less than 0.5m. 7. The loading personnel should step on wooden planks; it is strictly prohibited to step directly on the catalyst to avoid crushing it. 8. After loading is complete, use wooden planks to level the catalyst. Install the manhole immediately.
There are three situations for catalyst replacement: Temporary replacement: 1) When the catalyst’s activity deteriorates and its conversion capacity drops below the minimum allowable level, the catalyst is replaced during a temporary shutdown. 2) The mechanical strength of the catalyst deteriorates, and the bed resistance exceeds the allowable value; a temporary shutdown is required for replacement. 3) In the event of a serious equipment failure, the catalyst must be temporarily removed and replaced. Preventive planned replacement: Since the catalyst’s conversion capacity, bed resistance, and equipment performance are all within acceptable limits, preventive replacements are carried out during planned shutdowns in order to avoid unplanned stops. Principle of optimal economic efficiency: By taking into account comprehensive factors such as equipment protection, increased production and cost savings, as well as optimal economic efficiency, replacements are carried out in a planned manner in advance.
1) Temporary replacement； (1) Catalyst activity deteriorates, and the purification capacity drops below the minimum allowable level; temporary shutdown is required for replacement ； (2) The mechanical strength of the catalyst deteriorates, and the bed resistance exceeds the allowable value; temporary shutdown is required for replacement ； (3) In the event of a serious equipment failure that causes the catalyst to experience abnormal conditions such as prolonged overheating or temperature spikes, it is necessary to temporarily remove and replace the catalyst. 2) Preventive planned replacement ； The catalyst conversion capacity, bed resistance, and equipment performance are all within acceptable ranges. To avoid unplanned shutdowns, preventive replacements are carried out taking advantage of planned shutdown periods. 3) Principle of optimal economic efficiency. Taking into account comprehensive factors such as equipment protection, increased production and cost savings, as well as optimal economic benefits, replacements are carried out in a planned manner in advance.
1) Temporary replacement； (1) Catalyst activity deteriorates, and the purification capacity drops below the minimum allowable level; temporary shutdown is required for replacement ； (2) The mechanical strength of the catalyst deteriorates, and the bed resistance exceeds the allowable value; temporary shutdown is required for replacement ； (3) In the event of a serious equipment failure that causes the catalyst to experience abnormal conditions such as prolonged overheating or temperature spikes, it is necessary to temporarily remove and replace the catalyst. 2) Preventive planned replacement ； The catalyst conversion capacity, bed resistance, and equipment performance are all within acceptable ranges. To avoid unplanned shutdowns, preventive replacements are carried out taking advantage of planned shutdown periods. 3) Principle of optimal economic efficiency. Taking into account comprehensive factors such as equipment protection, increased production and cost savings, as well as optimal economic benefits, replacements are carried out in a planned manner in advance.
Catalyst poisoning； coking ； Inactivation ；
The pressure difference across the bed is too high, causing severe coking of the catalyst and bed offset. When the catalyst is deactivated