Process heat input

Abnormal Process Heat Input - The required capacity is the maximum vapor generation rate at PR valve relieving conditions, including any noncondensibles produced from overheating, less the normal condensation or vapor outflow rate. In every case, one should consider the potential behavior of a system and each of its components. For example, the fuel or heating medium control valve or the mbe heat transfer may be the limiting consideration. Consistent with the practice... 

Excessive Process Heat Input Most hydrocarbon and chemical processes require or contain varying amounts of heat exchange. Should a process upset occur, which inputs more heat than design conditions have allowed an overpressure may result due to expansion of liquid or vapor contained within the system. 

In the case of welded overlays, parameters acting on the phenomena have been studied. It has been shown that disbonding depends on [2,3] (i) Materials parameters (base metal chemistry, stainless steel overlay chemistry), (ii) welding conditions (welding process, heat input, post weld heat treatment), and (iii) service parameters (temperature, hydrogen pressure, cooling rates). 

Induction heating is used to heat steel reactor vessels in the chemical process industry (5). The heat produced in the walls is conducted to the material within. Multisectioned cods are used to provide controlled heat input to the process material as it passes through the reactor. Figure 6 illustrates a cross section of such a typical installation. 

PETROSIX. The PETROSIX technology is operated in the IH mode using hot recycle gas as the heat-transport medium. The PETROSIX retort has only one level of heat input, uses countercurrent flows, and uses a circular grate to control the flow of soflds (Eig. 3). The PETROSIX has been operated by Petrobras (Brazil) since the 1950s and is one of the few retorting processes producing shale oil in 1995. 

When the dryer is seen as a heat exchanger, the obvious perspective is to cut down on the enthalpy of the air purged with the evaporated water. Minimum enthalpy is achieved by using the minimum amount of air and cooling as low as possible. A simple heat balance shows that for a given heat input, minimum air means a high inlet temperature. However, this often presents problems with heat-sensitive material and sometimes with materials of constmction, heat source, or other process needs. AH can be countered somewhat by exhaust-air recirculation. 

The use of high or low limits for process variables is another type of selective control, called an override. The feature of anti-reset windup in feedback controllers is a type of override. Another example is a distillation column with lower and upper limits on the heat input to the column reboiler. The minimum level ensures that liquid will remain... 

Abnormal Heat Input From Reboiler - Reboilers are designed with a specified heat input. When they are new or recently cleaned, additional heat input above the normal design can occur. In the event of temperature control failure, vapor generation may exceed the process system s ability to condense or otherwise absorb the buildup of pressure, which may include noncondensibles due to overheating. 

Loss of heat input to closed process equipment handling low vapor pressme materials (e.g., fractionation of alcohols and aromatic solvents), while cooling continues such as by a condenser or through heat loss to the atmosphere. 

Loss of heat input to closed process equipment where appreciable quantities of steam are generated. 

Diisopropanolamine Systems. Diisopropanolamine (DIPA) is a secondary amine used in the Shell ADIP process to sweeten natural gas. DIPA systems are similar to MEA systems but offer the following ad an-tages carbonyl sulfide (COS) can be removed and regenerated easily and the system is generally noncorrosive and requires less heat input. 

The cemented lap seam used in these cans is a sandwich of plate, organic coatings, and cement. The body is formed on a modified body-maker, and the process is based on the control of heat input and removal. Welded cans are also made on a modified bodymaker. Coated TFS body blanks with bare edges are fed into the bodymaker where the margins are cleaned so that a uniform electrical resistance will be presented to the electric current provided to weld the side seam. 

Figure 5 shows the calculated heat Input and cooling coll heat removal rates In KW, the latter calculated from water flow and temperature differential by the computer when logging. As Is typical with non-reflux processes, actual heat Is within 5% of expected from the theoretical heat of reaction. 

Here Q(t) denotes the heat input per unit volume accumulated up to time t, Cp is the specific heat per unit mass at constant pressure, Cv the specific heat per unit mass at constant volume, c is the sound velocity, oCp the coefficient of isobaric thermal expansion, and pg the equilibrium density. (4) The heat input Q(t) is the laser energy released by the absorbing molecule per unit volume. If the excitation is in the visible spectral range, the evolution of Q(t) follows the rhythm of the different chemically driven relaxation processes through which energy is... 

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