Cooling water flow

Sequence errors refer to situations when a person performs a task, or an individual step in a task, out of sequence. For example, charging the reactor before starting the cooling water flow. 

Excessive system demand from com- leaving bearings should 3. Inadequate cooling water flow... 

The flask B is two-thirds filled with cyclohexene, and, with the cooling water flowing, this is heated to vigorous boiling. 

A chemical reactor, being started, was filled with the reaction mixture from another reactor which was alic.uly on line. The panel operator increased the flow of fresh feed while watching an eye level temperature recorder He intended to start cooling water flow to the reactor when the temperature began to rise, but did not because the tempe.r.j, ure recorder was faulty, thus a runaway reaction. 

Where an under-slung condenser has been specified, the provision of a basement to the engine room offers the attraction of compactness at the expense of enhanced civil works, while alternatively, the specification of pannier condensers can obviate the need for a basement and will simplify the foundation design, but will considerably increase the floor area requirements. The condensing plant itself consists essentially of banks of tubes through which cooling water flows and around which exhausted steam from the turbine is condensed to form a vacuum. Such tubes have traditionally been made of brass, but where severe corrosion conditions exist, cupro-nickel is sometimes used. 

Optimal cooling water temperatures and cooling water flows in upper and lower reactor cooling circuits... 

Figure 5.65. Temperature profiles caused by turning on the cooling water flow by setting TIMEON to 10.

A similar equation could be applied to the manipulation of the cooling water flow. 

Using the controller constant found in Exercise 2, make a step decrease in the cooling water flow rate. Did the controller decrease the reactant flowrate to compensate for this change ... 

Modify the program and change the controller to manipulate the cooling water flow rate. Experiment with this program. 

Cooling water flow = (40 30)4 18 = 104-5 kg/s Assumed overall coefficient (Table 12.1) = 900 W/m2oC... 

Figure 24.4 Minimizing cooling water flow in a parallel arrangement. (From Kim J-K and Smith R, 2001, Chem Eng Sci, 56 3641, reproduced by permission of Elsevier Ltd.)...

After the new cooling duty is added, the temperature of the cooling water flow to the cooling network must be maintained to be 20°C. 

The lube oil cooler consists of a hollow shell with several tubes running through it. Cooling water flows inside the shell of the cooler and around the outside of the tubes. Lube oil flows inside the tubes. The water and lube oil never make physical contact. 

The lube oil temperature is the controlled variable because it is maintained at a desired value (the setpoint). Cooling water flow rate is the manipulated variable because it is adjusted by the temperature control valve to maintain the lube oil temperature. The temperature transmitter senses the temperature of the lube oil as it leaves the cooler and sends an air signal that is proportional to the temperature controller. Next, the temperature controller compares the actual temperature of the lube oil to the setpoint (the desired value). If a difference exists between the actual and desired temperatures, the controller will vary the control air signal to the temperature control valve. This causes it to move in the direction and by the amount needed to correct the difference. For example, if the actual temperature is greater than the setpoint value, the controller will vary the control air signal and cause the valve to move in the open direction. 

This results in more cooling water flowing through the cooler and lowers the temperature of the lube oil leaving the cooler. 

The actuating signal passes through the two control elements the temperature controller and the temperature control valve. The temperature control valve responds by adjusting the manipulated variable (the cooling water flow rate). The lube oil temperature changes in response to the different water flow rate, and the control loop is complete. 

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