Operator/controller interface

Operation When operated correctly, thickeners require a minimum of attention and, if the feed characteristics do not change radically, can be expected to maintain design performance consistently. In this regard, it is usually desirable to monitor feed and underflow rates and sonds concentrations, flocculant dosage rate, and pulp interface level, preferably with dependable instrumentation systems. Process variations are then easily handled by changing the principal operating controls—underflow rate and floccirlant dose—to maintain stability. 

Human error assessment Operator/process and equipment interfaces Administrative controls versus hardware... 

Personal computer interface simplifies operator control of the system through a user-friendly interface. 

In the LPG contactor the amine is normally the continuous phase with the amine-hydrocarbon interface at the top of the contactor. This interface level controls the amine flow out of the contactor. (Some liquid/liquid contactors are operated with the hydrocarbon as the continuous phase. In this case, the interface is controlled at the bottom of the contactor.) The treated C3/C4 stream leaves the top of the contactor. A final coalescer is often installed to recover the carry-over amine. 

For capillary zone electrophoresis (CZE) mass spectrometry coupling, another modification of an ESI interface has been developed. This interface uses a sheath flow of liquid to make the electrical contact at the CZE terminus, thus defining both the CZE and electrospray field gradients. This way, the composition of the electro sprayed liquid can be controlled independently of the CZE buffer, thereby providing operation with buffers that could not be used previously, e.g., aqueous and high ionic strength buffers. In addition, the interface operation becomes independent of the CZE flow rate. [62]... 

Poorly operating interface-level controllers can upset the interface level and cause a loss of water resulting in oil being dumped out. There is also the problem of improperly positioned inlet splash baffles within the vessel and this can cause problems regardless of the chemical. This, in most cases, can only be eliminated by removing or repositioning the baffle... 

Horizontal treaters. Multiwell installations normally require horizontal treaters. Fig 2 shows a typical design. Flow enters the front section of the tteatei where gas is flushed. Liq uid falls to the vicinity of the oil-water interface where it is water washed and freewater separated Oil and emulsion rise past the lire tubes and are. skimmed into the oil surge i Irani -her. "Fhe oil-water interface in the inlet section is controlled by an interface level controller that operates a dump valve for the freewater... 

The wet crude tar.k operates at approximately 50t level and gives a period of several hours retention time, allowing formation water to settle out of suspension. Separated free water settles at bottom of tank and Is transferred to waste water conditioning unit through an interface level controlle . 

Water is drained off the boot to maintain an interface level between water and hydrocarbon in the boot. These interface level controllers, especially on reflux drum water draw-off boots, are typically set locally. The operator finds the visible interface level in the boot s gauge glass, and then sets the local interface level controller, to hold the level half way down the boot. Level taps in the lower portion of any vessel, tend to plug. This is especially true with the level taps in water draw-off boots. You need to blow out these taps on some frequent basis, because a high boot interface level can push water into the tower s reflux pump. 

In practice, this process ensures that the system (computer hardware, computer software, controlled equipment, interfaces, operating environment, operators, equipment, procedures, and so on), in its normal operating environment, produces acceptable quality product and that sufficient documentary evidence exists to demonstrate this assessment. 

Control dependencies Operator interface Operating environment... 

Minimize mechanical damage to cells (mixing operations and air-liquid interfaces) Provide control of environment (pH, dissolved oxygen, temperature, etc.)... 

Poor interface control allows the main liquid-liquid interface to leave the extractor. This may result from inadequate size of interface flow control valves, or operation with internals that provide inverse control responses such as those observed with sieve tray extractors. (See Process-Control Considerations. )... 

Capable of achieving adaptability to various threats and technology Mdecular operational control (for example electrochemical interface with multifunctional matrix)... 

Systematic investigations of microbial cell recovery by foam flotation were performed by Hansenula polymorpha [113-117] and Saccharomyces cerevisiae [ 118 -123] in continuous operation. The equipment used for flotation was often identical to that used for protein flotation. The microorganisms were cultivated in laboratory reactors on synthetic media in the absence of antifoam agents in continuous operation and the cell-containing cultivation medium was collected in a buffer storage and was fed into the middle of the colunm, at the top of the interface between the bubble and the foam layers. The height of the interface was controlled by an overflow. The foam left the colunm at the top. The cells were recovered from the foam liquid by a mechanical foam destroyer. The liquid residue left the column through an overflow [113] (Fig. 6). 

The programming for mustard agent processing at TOCDL is unique, so software coordination problems should not arise. However, the display interfaces processed by the RSView HMI were modified so that display and related operator control processes would be consistent across all sites. Any future modifications of this type should similarly take consistency across sites into account. 

The General Database operation controls storage, retrieval, searching, and deletion of data in general databases that interface to MACCS-II. ORACLE or System 1032 DBMS interfaces are available from MDL. Other DBMS s that have interface architecture similar to ORACLE S may be user-programmed for use with this facility. 

Table 4.21 lists the mixing process variables that are easy to measure using readily available instrumentation. Interfacing the controls with an alarm system allows the operator to be alerted to any out-of-specification condition. This needs to be corrected by cleaning, maintenance and recalibration before a major problem develops. 

The process operators control strategy is based on anticipation, knowledge (know-how), and experience, and can be considered as a set of heuristic decision rules or rules of thumb. In order to recognize the human s basic elements and to include the operator s control actions in an automatic scheme, a good user-system interface is required. A useful way to combine this user-system interface with process control is to use intelligent control systems. 

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