The heat source issue in the distillation tower
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The solid content of the slurry is high, the reaction temperature decreases, the temperature at the bottom of the distillation tower drops, and a large amount of the slurry is discharged. Insufficient heat source occurs during distillation (primarily when the diesel extraction temperature is below the set value). Is fractional distillation about appropriately increasing the middle-stage volume? The process involves extraction from the middle stage of distillation ---- slurry heat exchanger -- stabilizer reboiler -- desorber reboiler -- water cooling. The middle-stage oil is heated by the slurry heat exchanger, which can raise its temperature as well as lower the temperature of the slurry, thereby reducing the temperature at which the slurry returns to the tower. To produce more oil slurry. This provides more heat sources for stabilization, prompting it to release heat; as a result, the temperature of the oil returning to the tower in the middle section is effectively increased, which in turn raises the temperature at which diesel is extracted, thus solving the heat source issue. Is my understanding correct? Please give me some advice.
When the temperature at the bottom of the distillation column decreases, the temperature in the middle section drops accordingly, and the load in that middle section also decreases; making adjustments to that middle section is ineffective. The primary issue is to determine the reason for the high solid content of the slurry. The large amount of oil slurry being discharged also results in an increase in the heat load, a decrease in the bottom temperature, a reduction in the load in the middle section, and a drop in the temperature of the diesel distillate; as a result, it is impossible to raise the temperature in that middle section.
What is the purpose of you doing this? By doing this, isn’t the high-temperature heat of the oil slurry being wasted by you? Our one-stage circulation supply is sufficient as a stable heat source. The slurry can generate 3.5 MPa of steam, producing nearly 80 tons per hour. It has a significant positive impact on the device.
I think it depends on whether what you do is correct; you’ll know by doing a heat balance calculation for a distillation column. But from an intuitive perspective, I agree with what was said on the second floor: you should find out as soon as possible why the solid content of the slurry is too high. Reduce the amount of slurry that is spilled outside.
Actually, by performing a heat balance on the entire distillation tower, everything becomes clear
But there is still a lot of excess cooling in the temperature at the bottom of the fractionation tower; isn’t that a waste? Steam can be fully supplied by boilers and external heat extraction
Agree with the view from the second floor: figure out the reason for the high solid content in the slurry, and then address it. The fundamental problem needs to be solved.
First of all, I think this approach is wrong. There are many factors that contribute to an increase in the solid content of oil slurry. For example, issues such as catalyst loss, poor performance of the centrifuge, or an increase in solid content due to other factors – the first step is to identify the cause before taking any action. Increasing the discharge of oil slurry is merely a temporary emergency measure at present. The reason lies in the reaction system; we need to check for any abnormalities in the operation
Not to mention the high solid content of the slurry, which is due to equipment limitations. However, when dealing with the increased external discharge of slurry, considering lowering the reaction temperature as a solution is possible. However, check whether the level of the reprocessed oil is rising; if there is enough reprocessed oil, it is recommended not to proceed with reprocessing. Now the quality of the raw materials is poor, and reprocessed oil and oil slurry have no value for reprocessing. My unit doesn’t recycle at all. All recycled oil is returned to the tower for discharge. At the same time, increase both the reaction depth and the conversion rate; of course, the exit temperature of the riser must be controlled using a terminator. Some time ago, a malfunction in the level control of the raw material buffer tank caused the raw oil to flow back into the distillation tower, resulting in a large amount of material being discharged. I keep the bottom temperature of the tower below 310 degrees, resulting in less heat exchange between the slurry and the intermediate oil. It is mainly used for steam generation and heat exchange of raw materials. The mid-section oil-water cooler is basically not in use, as the flow rate in that section is sufficient. Therefore, it is recommended to estimate the slurry system while taking into account the yield and diesel quality.
If the reaction temperature is lowered, insufficient heat will be available for the slurry to be discharged; raising the reaction temperature is necessary. If the solid content of the slurry is high, the cause must be identified – the operating conditions cannot be changed
Reduce the amount of slurry that is discharged outside a little; oil slurry reprocessing can be utilized to lower the solid content while minimizing heat loss. Additionally, the thermal energy present at high temperatures in the oil slurry isn’t being utilized effectively. Moreover, if there is a leak in the oil slurry heat exchanger, things can get problematic, as the connections between these elements are quite strong.