What impact does low ceiling reduction temperature have on vacuum degree and operation?

1. The low overhead temperature will definitely affect the vacuum degree at the top of the tower. Because the overhead temperature is low, the amount of overhead gas will change, and the performance of the vacuum system at the top of the pressure reduction tower will inevitably change.； 2. The temperature at the top of the vacuum tower is generally controlled at around 70°C. ； 3. The appropriate distillation temperature of the first line of reduced overhead circulation (reduced overhead circulation) is around 140°C. Whether the reflux is too high depends on the temperature of your overhead reduction tower. ； 4. I personally feel that internal reflux has little to do with the distillation temperature (can be discussed) ； 5. The function of the subtracted one (reduced overhead circulation) internal reflux is to spray the packing. The reduced overhead circulation reflux has a greater effect on regulating the gas phase load at the top of the tower.

What the 2nd floor said is very detailed, and I completely agree.

The 2nd floor said it in great detail, please add a few more: 1. First of all, we must understand that the increase in vacuum is caused by the gas, not the liquid, being pumped out of the tower. 2. When the ceiling temperature is low, the corresponding gas volume will be small, the load of the evacuator will decrease, and the vacuum degree will increase. 3. Nothing can be generalized. If the overhead reduction cycle is very large, it will also cause the overhead reduction temperature to drop a lot, but it will also increase the pressure drop of the tower, which may not be a good thing for the entire pressure reduction tower operation. Therefore, it is necessary to control the appropriate tower top temperature and overhead reduction circulation flow rate. Generally, the tower top temperature is controlled at 60℃-80℃.

The top reduction temperature decreases, some media are lower than the boiling point, and the mass of the pumped medium decreases. If the vacuum system is fixed (or has no loop), the vacuum degree at the top of the tower will increase.； On the contrary, when the ceiling temperature rises, the vacuum degree will decrease.

The pressure reduction tower is divided into dry pressure reduction tower and wet pressure reduction tower. The bottom temperature of the dry type tower is about 380 degrees, and the wet type is about 405 degrees. The temperature at the top of the dry tower is about 50 degrees, and when it is wet, it is about 80 degrees. If the temperature at the top of the tower is low, the degree of vacuum will rise. It is enough to control the temperature at the top of the tower not to exceed the process specifications by decompression and reflux. Reduce one oil and put it into the normal pressure top cycle for refining.

The normal top temperature is around 43 now. Let me share my operating conditions.: 1. We process asphalt, the vacuum degree is -93, we use two-stage vacuuming, and the outlet of the decompression furnace is about 360. 2. We have a top-reducing cycle, part of which is returned to the flow-controlled top temperature, and the other part is installed as a first-line product. 3. The extraction temperature is about 118, the cooling temperature is 55 degrees, the return flow DCS shows that it is already 40,000 over the range, the output volume is very small, basically 3,000, and the density is about 870. 4. Is our ceiling temperature very low? I am speechless...

A low ceiling reduction temperature is conducive to improving the vacuum degree. However, it can easily cause the diesel oil in the container to emulsify after the ceiling reduction oil vapor is condensed.

Why are all the poster’s new words? What is reflux within minus one? Should I still use a pump for internal reflux? study * study * !

The lower the ceiling reduction temperature, the higher the vacuum degree. Because the lower the ceiling reduction temperature, the lighter the ceiling reduction components and the less liquid phase that can dissolve non-condensable gas, the ceiling reduction temperature has an optimal temperature. You can test it. Lower is not always better. Generally, there will be a maximum vacuum degree between 78 and 100. The top-reducing reflux is to reduce the first line of extraction. Generally, this bucket is designed as a full extraction bucket, and the full extraction method should be adopted. If the bucket is full, the liquid will overflow to the next tray. If the full bucket operation is adopted, the dry point of reducing the first line can be increased as long as the extraction amount is increased. If the half-bucket operation is adopted, the lower part of the first center should be lowered to take heat, so that the second-line components can enter the first-line furnace.

1. The top reduction temperature is generally controlled at 50-100°C, which varies according to the properties of the oil and the quality control requirements of the decompression side line. It is higher than 50°C because the boiling point of water is about 53°C when the vacuum degree is 93Kpa. If the water is liquid below this temperature and cannot be distilled from the distillation line, but condenses and vaporizes back and forth between the reduction line and the top of the tower, then the corrosion of this section of packing or tray will be serious. The low temperature at the top of the tower will not have much impact on the vacuum degree. If the gas phase load of the vacuum system is higher than 100℃, the vacuum degree will inevitably decrease. 2. Your line-reducing reflow is hot reflow and has not been cooled. Its amount does not affect the extraction temperature of the line-reducing line. The low temperature may be directly related to the high atmospheric pressure extraction rate, resulting in a small decompression gas phase load, a large reflux at the top of the tower (if any), or a large reflux in the first and second stages. According to you, the purpose of reducing the first line of reflux is to provide enough liquid phase in the tower and distribute the liquid phase reflux evenly in the tower, similar to dirty washing. In addition, since the internal reflux is improved, let me talk about it.: “As the name suggests, "internal reflux" means reflux within the tower. It is a liquid phase flow method similar to reflux caused by the top-down flow of the liquid phase in the tower. Internal reflux is caused by the heat balance on the trays in the tower. It is mainly used in its hydraulic calculations. The total amount of condensate - the amount produced = the amount of internal reflux. The main difference between it and general reflux is that it is caused by the balance of heat forces in the tower, rather than forced. All forced reflux is external reflux.