Regarding the question about the time at which feed is introduced into the hydrogenation unit, should the reactor be fed with feed while it is at cold temperature or at hot temperature?
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This post was last edited by 328104062 on 2016-7-9 at 18:52. As the title suggests, for hydrogenation units (used for hydroprocessing of gasoline, coal tar, and diesel), first pressurize to 1.5 MPa, then start the recycle hydrogen compressor, subsequently light the furnace, and continue to increase the pressure (this step is not necessary for gasoline and coal tar hydroprocessing, but it is required for diesel hydroprocessing). The reactor bed temperature (usually based on the inlet temperature) should be between 200–220°C when feeding the oil in; the reduction temperature for Ni-Co-Mo catalysts is generally considered to be 230°C. Since the oil is cold at the time of feeding, with a temperature of room temperature or 60–90°C, and even lower in winter, the reactor inlet temperature drops from 220°C to 100°C immediately upon oil feeding. Such a large temperature change is detrimental to the equipment. Questions: 1. Is it possible to first pressurize to 1.5 MPa, then start the compressor, feed the oil in, light the furnace, and continue to increase the pressure (this step is not necessary for gasoline and coal tar hydroprocessing, but it is required for diesel hydroprocessing) in order to raise the temperature? This way, it won’t cause sudden temperature changes. 2. What do people do? That method is good, manager discussion group
The decrease in inlet temperature is purely due to untimely operation; as for feeding oil at low temperatures, thermal expansion must be taken into account, and if the catalyst is soaked in cold oil, an increase in temperature can cause the catalyst’s micropores to vaporize, leading to structural breakdown and other issues
Yes, it’s just that the time required for the product to meet the quality standards is longer, but this has little impact on the heat exchanger.
If you can ensure that the reactor inlet temperature doesn’t drop while feeding in the oil, then your skill level is truly outstanding. It’s practically impossible to achieve this in real operations; I’m curious about how you manage to do it. Please share your insights
There isn’t a very good solution for this; try to raise the oil inlet temperature, as it doesn’t cause significant direct damage to the equipment
The key is to figure out how to improve the situation. After a shutdown, the oil in the crude oil buffer tank as well as that in the pipelines at the pump inlet and outlet is definitely cold; the temperature is even lower in winter
What is the purpose of the furnace? ! ! ! I can accept a decrease in the furnace outlet temperature, but a drop of 100°C – should we look for the reasons from an operational perspective?
During the start-up process, when the reactor is being wetted with oil, the feed rate cannot be very high – it is around 25% of the normal load. In this case, raising the temperature of the reaction furnace in advance is sufficient to meet the requirements, and the temperature will not drop significantly.
The problem is that the pump’s minimum flow rate is not sufficient for 60% load, so the equipment stops working
Use your brain more – there’s no problem with that. Even if it decreases, it won’t drop by 100 degrees; a decrease of twenty or thirty degrees is acceptable