Bench-scale heat flow

The Sikarex safety calorimeter system and its application to determine the course of adiabatic self-heating processes, starting temperatures for self-heating reactions, time to explosion, kinetic data, and simulation of real processes, are discussed with examples [1], The Sedex (sensitive detection of exothermic processes) calorimeter uses a special oven to heat a variety of containers with sophisticated control and detection equipment, which permits several samples to be examined simultaneously [2]. The bench-scale heat-flow calorimeter is designed to provide data specifically oriented towards processing safety requirements, and a new computerised design... 

Regenass, W., Thermal and Kinetic Design Data from a Bench Scale Heat Flow Calorimeter, In Chemical Reaction Engineering—Houston, ACS Symposium Series (D. Luss and V. W. Weekman, eds.), p. 37 (1978). 

DTA Differential Thermal Analysis DSC Differential Scanning Calorimetry TGA Thermo Gravimetric Analysis ARC Accelerating Rate Calorimetry BSC Bench Scale, Heat Flow Calorimetry SEDEX Sensitive Detector of Exothermic Processes Others Oven Tests, Dewar Tests, Hot Plate Tests, etc. 

F. Brogli et al. "Assessment of Reaction Hazards by means of a Bench Scale Heat Flow Calorimeter ,... 

Two bench-scale heat flow calorimeters (with a Scunple size of O.3-2.5 litres) have been described a design of Hub Q3, particularly suitable for work under reflux conditions, and the instrument presented in this paper, which is a single sample active heat flow calorimeter, using the heat flow control method 31). ... 

For the requirements of process development and process safety investigation, a bench scale heat flow calorimeter has been developed eind built. Figure 1 outlines its principle. The stirred tank reactor (A) is surrounded by a jacket in which a heat transfer fluid is circulated at a very high rate. A cascaded controller (B) adjusts the temperature of the circulation loop (C) so that heat transfer through the reactor wall equilibrates the heat evolution in the reactor. Injection of thermostated hot or cold fluid is used to adjust the temperature in the loop. 

Figure 1. Bench scale heat flow calorimeter...

The PHI-TEC or VSP bench scale apparatus can be employed to determine information about the self-heat rate and vapor disengagement when this is not readily available. Additionally, the VSP equipment can be used for flashing flow characteristics using a special bottom vented test cell. Here, the flowrate, Gq (kg/sm ), is measured... 

Silveston et al. (1994) use a one-dimensional plug flow model to represent the packed bed in the final stage. Because the intent of their work was to model the experiments of Briggs et al. discussed earlier, they allowed for heat loss or gain in the bench scale reactor used by Briggs through wall... 

Three different principles govern the design of bench-scale calorimetric units heat flow, heat balance, and power consumption. The RC1 [184], for example, is based on the heat-flow principle, by measuring the temperature difference between the reaction mixture and the heat transfer fluid in the reactor jacket. In order to determine the heat release rate, the heat transfer coefficient and area must be known. The Contalab [185], as originally marketed by Contraves, is based on the heat balance principle, by measuring the difference between the temperature of the heat transfer fluid at the jacket inlet and the outlet. Knowledge of the characteristics of the heat transfer fluid, such as mass flow rates and the specific heat, is required. ThermoMetric instruments, such as the CPA [188], are designed on the power compensation principle (i.e., the supply or removal of heat to or from the reactor vessel to maintain reactor contents at a prescribed temperature is measured). 

The Contalab, initially supplied by Contraves, was purchased by Mettler-Toledo, which is now placing less emphasis on this design than on the RC1. Some comments here are appropriate, however, since it is another type of bench-scale calorimeter, and units continue to be used. Its measuring system is based on the heat balance principle, in which a heat balance is applied over the cooling/heating medium. For this purpose, both the flow rate of the coolant and its inlet and outlet temperatures must be known accurately. Figure 3.12 is a schematic plan of the Contalab. 

The second material property is heat of gasification, L, defined as the net heat flow into the material required to convert one unit mass of solid material to volatiles. The net heat flux into the material can be obtained from an energy balance at the surface of the specimen. Typically, a sample exposed in a bench-scale calorimeter is heated by external heaters and by its own flame. Heat is lost from the surface in the form of radiation. Owing to the small sample size, the flame flux is primarily convective, and flame absorption of external heater and specimen surface radiation can be neglected. Hence, L can be defined as... 

Figure 14. Flow diagram of bench-scale hydropyrolysis unit 1. drier, 2. pressure regulator, 3. air inlet, 4. rotameter, 5. c/iecfc valve, 6, 9. thermocouples, 7. preheater, 8. reactor, 10. condenser, II, 12, collectors, 13, 14. /too control valves, 15. CdCl2 scrubber, 16. tesf meter, 17. piston pump, 18, 19. rupture discs, 20. reciporating pump, 21. oil reservoir, heated.

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