Alcohol double-effect distillation: Some problems have arisen in the first distillation column; seeking help from experts
Thread Content
Recently, while operating the two-effect recovery system, it was observed that during the steam injection phase in the first effect, namely the pressurized tower, the reflux produced at the top of the tower was satisfactory. Once all parameters in the atmospheric pressure tower reached the required levels and stable production was achieved, the temperature at the top of the pressurized tower turned out to be too high. Normally, a minimum reflux ratio along with proper control of feed temperature is sufficient to produce qualified product; now, however, it is necessary to increase both the reflux amount and feed temperature control in order to obtain the desired product, yet the output remains low. ), the pressures at the top and bottom of the tower also increased by nearly twice compared to normal levels (0.095 MPa at the top and 0.107 MPa at the bottom; previously, without increasing the reflux rate, these values were around 0.5 and 0.7 MPa respectively). ) The output at the top of the tower is also low, and it is difficult to control the tower temperature through reflux and feed; increasing the reflux results in very little output from the reflux tank. Increasing the feed rate makes it impossible to control the liquid level at the bottom of the tower, and equilibrium cannot be maintained. I would appreciate guidance from experienced experts.
Is there a condenser at the top of the tower? It’s possible that the condensing effect of the condenser is not good
There is a condenser – is it clogged? Currently, the temperature at the top of the first-effect tower is on the high side, and this difference is quite significant compared to before. I’m not sure if there are any other factors at play; surely the condenser shouldn’t have an impact on the temperature at the top of the tower, right?
Poor condensation efficiency of the condenser is caused by issues such as blocked pipelines, blockages in the tube side, or a high temperature of the condensate water, all of which lead to inadequate condensation performance
Will scaling in the reboiler or the bottom of the tower affect the output?
What is the method used to control pressure in a pressurized tower?
A high top temperature in the pressurized tower indicates that the reboiler at the bottom of the atmospheric tower has insufficient capacity. To find the cause, one must start by examining the process design. (Top of tower: 0.095 MPa, bottom of tower: 0.107 MPa; previously, without increasing the reflux ratio, it was usually 0.5, 0.7.) ) I don’t understand this pressure value; in a normal double-effect system, the pressure in the pressurized tower is around 3 kilograms, while the other side operates at atmospheric pressure, which is quite different from what you mentioned
What is the method used to control pressure in a pressurized tower? It certainly isn’t the opening degree of the steam valve; it must be the feed pump and the recirculation pump
We use the dual-effect model from Jinta here; it is necessary to ensure balanced discharge so that the pressure behind the control valve remains stable, thereby enabling consistent recovery. I was transferred away from this position recently, so I was unable to continue following up on this matter. There’s a new issue: I noticed that for the first-effect tower, there is an additional small steam pipe that leads to the connection between the reboiler and the tower bottom. The second-effect tower also has a steam pipe that connects directly to the reboiler and the tower bottom, but it seems to be unused Does it not work?