Automatic regeneration

As we saw in the last chapter, by discarding the noise eigenvectors, we are able to remove a portion of the noise from our data. We have called the data that results after the noise removal the regenerated data. When we perform principal component regression, there is not really a separate, explicit data regeneration step. By operating with the new coordinate system, we are automatically regenerating the data without the noise. 

Another process involving the use of both air stripping and activated carbon adsorption has been developed by Wang and colleagues.29 This process purifies and recycles the emitted gas, thus not creating an air pollution problem. Also, the spent GAC can be automatically regenerated for reuse. 

The two HPLC pumps and the six-port switching valve permit one to switch from one eluent to the other, and the immunoadsorbent column is automatically regenerated. In addition, for the frontal elution mode, this system permits one to... 

DI water is produced using an XYZ rapid, high-performance, twin-bed deionizer. The plant consists of two glass-reinforced plastic pressure vessels that hold the ion exchange resins together with a process pump, pipe work, valves, flowmeters, and controls to enable the plant to produce high-quality deionized water and automatically regenerate the resins. 

The adaptive mesh scheme that automatically regenerates the mesh when the elements are severely distorted due to large deformation... 

The ARSA system is designed to operate continuously in remote areas with minimal maintenance and consumables limited to replacement bottles of nitrogen carrier gas and CO2 removal traps. Dryers and gas traps were chosen that could be automatically regenerated in the field. The system has many components and a complex path for the analyte gas that traverses the system. The numerous valves ( 100) for controlling the gas flow and trap regeneration processes require a control system about one order of magnitude more complex than that for the RASA system described in the preceding section, if the number of parts is taken as a measure of... 

The resin is automatically regenerated when washing the column with water. No reagents are needed for the displacement of solutes hum the column and no wastes are generated. ISE is a green separation process. 

For automatic regeneration after fixed periods of operation, e.g. 8 hours, electromechanical (relays) or PLC based control may be used. 

Ion exchange equipment suppliers will usually furnish a water meter that totalizes the quantity of waste processed through the column. After the system has been caUbrated by the equipment suppher, the water meter will activate an alarm after a specified volume of waste has been processed. An alarm will sound if the system requires manual regeneration. If the system is supphed with automatic regeneration, the water meter will deactivate a column while regeneration takes place. Where multiple columns are included within a system, valves must be adjusted to accommodate regeneration.This will be accomplished by manual or automated (pneumatic-, electric-, or hydraulic-actuated) techniques. 

Control Devices. Control devices have advanced from manual control to sophisticated computet-assisted operation. Radiation pyrometers in conjunction with thermocouples monitor furnace temperatures at several locations (see Temperature measurement). Batch tilting is usually automatically controlled. Combustion air and fuel are metered and controlled for optimum efficiency. For regeneration-type units, furnace reversal also operates on a timed program. Data acquisition and digital display of operating parameters are part of a supervisory control system. The grouping of display information at the control center is typical of modem furnaces. 

A typical ozone system consists of 100 g/hr at a concentration of 1.0 percent to 1.5 percent in air fed to the bottom of bleach collection tanks through ceramic spargers (pore size of approximately 100 t). The system contains air compression and drying equipment, automatic control features, and a flat-plate, air-cooled ozone generator. Regeneration of bleach wastes totaling about 10,000 gallons a year, and recovery of other chemicals can also be cost effective. 

Most adsorbers operate on a fixed drying cycle time and, frequently, the cycle lime is set for the worst conditions. However, the adsorbent capacity is not a fixed value it declines with usage. For the first few months of operation, a new desiccant has a very high capacity for water removal. If a moisture analyzer is used on the effluent gas, a much longer initial drying cycle can be achieved. As the desiccant ages, the cycle time will be automatically shortened. This will save regeneration fuel costs and improve the desiccant life. 

While it produces very pure water, de-ionization is an expensive process to operate. It uses acid and caustic for regeneration and produces an effluent which may need neutralization before it can be discharged. On the other hand, all sizes of de-ionization plants are available with fully automatic operation and control so that the plant... 

The activity of catalyst degrades with time. The loss of activity is primarily due to impurities in the FCC feed, such as nickel, vanadium, and sodium, and to thermal and hydrothermal deactivation mechanisms. To maintain the desired activity, fresh catalyst is continually added to the unit. Fresh catalyst is stored in a fresh catalyst hopper and, in most units, is added automatically to the regenerator via a catalyst loader. 

Hardness breakthrough can be particularly troublesome at those small, hard-working facilities that employ just one automatic softener. The problem may develop gradually and go unnoticed for some time. This may be because the softened water is not tested daily or, more usually, because the soft water is tested soon after resin regeneration rather than immediately before the point of exhaustion (which may be many hours later, but perhaps still 2 or 3 hours before the end of a working shift or plant shutdown). 

The primary advantage of fluidized bed reactors, however, is that they permit continuous, automatically controlled operations using reactant-catalyst systems that require catalyst regeneration at very frequent intervals. Fluidized bed operation permits one to easily add or remove the catalyst from the reactor or the regenerator. Regeneration can be accomplished by any convenient procedure, but the... 

The prepared sample may be applied in pH 2.2 buffer directly to the top of the column and the analysis sequence started, and after elution of all the amino acids and regeneration of the resin column, the next sample can be applied. However, many newer models incorporate an automatic loading device which enables several samples to be stored ready for analysis either in sample cups or in small Teflon coils. After the completion of an analysis the next stored sample is automatically applied to the resin and the buffer cycle restarted. 

Total unit heat dnty will typically be in the range of 500-1000 BTU per pound of feed to the unit. This set of process heat requirements establishes the amount of heat that must be supplied by combustion of coke. Because of the process control schemes that are normally employed in FCCUs, the unit operation will automatically adjust itself so that the energy produced via coke combustion equals the heat requirements of the process. If the balance is shifted by changes to the feed quality or operating conditions, shifts in catalyst circulation rate and regenerator temperature will occur until a new equilibrinm set of conditions is established. 

The efficiency of these steps can be conveniently monitored by continuous in-line measurement of the resistivity of the water (deionization results in increased resistivity, typically to levels of 1-10 MQ). If the resistivity of the deionized water falls below a value of approximately 1 MQ, automatic system shut-off, followed by regeneration of the anion and cation exchange beds (with NaOH and HCl respectively), is initiated. 

As the loam becomes laden with oil 3"d solids pressure drop across the foam increases. When the pressure drop reaches 6 psi the automatic controls initiate the regeneration process... 

Figure 15.16. A three-vessel drying system for a cracked light hydrocarbon stream. Valve operation usually is on automatic timer control. Recycled process gas serves as regenerant.

---