Tower pressure target, increase

By monitoring the key indicators and making operating adjustments to achieve the targets, the tower pressure was reduced. Online data were gathered to enable a comparison of results before and after implementation. The net result was the ability to process 5000 bpd of additional crude due to imloading of the charge heaters. The value of the increased rate was estimated as 1.5 million per year. To sustain the... 

The DIP process control was accomplished with a Distributed Control Stystem (DCS) system equipped with an APC algorithm. The controller was set to target 10% nCs in the overhead and 10% /C5 in the product, and would increase reboiler steam and reflux rate until reaching the maximum limits for these flows. The tower pressure was also controlled within a specified range by the APC, and this could indirectly limit the reboiler duty as well, if the tower pressure increased beyond its maximum limit. Inferential estimates for product tCs and Cs qualities were calculated based on tower temperatures and pressures, and a bias for these values was continually updated based on daily laboratory (lab) data. 

One way out of this problem, is to increase APL, the pressure drop of the liquid flowing through the orifice holes. This could be done, by increasing the orifice hole liquid velocity. We could drill fewer orifice holes. Unfortunately, this would decrease the number of drip points per square foot of tower area (6 to 10 is a good target). This would reduce vapor-liquid contacting efficiency. Or, we could have smaller orifice holes. But too small a hole would probably plug with corrosion products. 

Solvent oil is a by-product of the platinum reforming plant of petrochemical factories. The target of optimization is to increase the recovery of solvent oil. There are six affecting factors for the recoveiy of solvent oil reflux rate (X]), flow rate of the first side line (X2), pressure at tower top (X3), temperature of reflux (X4), temperature at solvent oil tower bottom (X5), temperature of the 35th-tower plate of solvent oil tower (Xe). Some data from the industrial records are listed in Table 14.2. 

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