Minimization heater

Maintenance of isothermal conditions requires special care. Temperature differences should be minimised and heat-transfer coefficients and surface areas maximized. Electric heaters, steam jackets, or molten salt baths are often used for such purposes. Separate heating or cooling circuits and controls are used with inlet and oudet lines to minimize end effects. Pressure or thermal transients can result in longer Hved transients in the individual catalyst pellets, because concentration and temperature gradients within catalyst pores adjust slowly. 

While process design and equipment specification are usually performed prior to the implementation of the process, optimization of operating conditions is carried out monthly, weekly, daily, hourly, or even eveiy minute. Optimization of plant operations determines the set points for each unit at the temperatures, pressures, and flow rates that are the best in some sense. For example, the selection of the percentage of excess air in a process heater is quite critical and involves a balance on the fuel-air ratio to assure complete combustion and at the same time make the maximum use of the Heating potential of the fuel. Typical day-to-day optimization in a plant minimizes steam consumption or cooling water consumption, optimizes the reflux ratio in a distillation column, or allocates raw materials on an economic basis [Latour, Hydro Proc., 58(6), 73, 1979, and Hydro. Proc., 58(7), 219, 1979]. 

Air recirculation. Prevailing winds and the locations and elevations of buildings, equipment, fired heaters, etc., require consideration. All air-cooled heat exchangers in a bank are of one type, i.e., all forced-draft or all induced-draft. Banks of air-cooled exchangers must be placed far enough apart to minimize air recirculation. 

Replacement of orchard heaters by wind machines is the most desirable control measure. These large propellers force the warmer air aloft to the ground, where it mixes with the cold air, minimizing frost formation. 

Many systems are shut down for periods of the year, either for process closure or if not required in winter. The advice of the supplier should be sought as to the correct procedure. In the case of refrigerant circuits, it is advisable to pump down into the receiver or condenser to minimize leakage losses. Water towers should be drained in winter in this climate, if not in use, and the tank heater disconnected. 

For all types of boilers, from the most simple HW heaters to immense power generating plants, one of the most fundamental objectives of any water treatment program is (as stressed several times) to minimize boiler section waterside corrosion, especially those common types of corrosion involving oxygen. The actions taken to achieve this objective are generally the same, irrespective of boiler size or design. These actions include ... 

The risk of corrosion is high with cold lay-up, and all efforts should be made to minimize humidity through the use of desiccants and heaters. Additionally, film formers and temporary coatings may be applied using spray equipment. 

A type of damper used to control the air temperature in air heaters. It also provides a means of minimizing air heater corrosion. 

Other thermal zones which should be thermostated separately from the column oven include the Injector and detector ovens. These are generally insulted metal blocks heated by cartridge heaters controlled by sensors located in a feedback loop with the power supply. Detector blocks are usually maintained at a temperature selected to minimize detector contamination from condensation of column bleed or sample components and to optimize the response of the detector to the sample. The requirements for i injectors may be different depending on the injector design and may include provision for temperature program operation. 

In the thermal bath modulation, a thermocouple is used as a weak link to the thermal bath, and the temperature of the bath is modulated sinusoidally in time. This configuration eliminates the need for a separate thermometer and heater on the sample, while retaining the ability to make measurements with minimal addenda. 

Provide curbing with trapped drains around each heater to prevent a liquid spill fire from involving other equipment. Drains should be sized accordingto heater liquid holdup to minimize pooling of the spill within the curbed area. 

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