Field-fouling units for refinery experiments

Two skid mounted field test units were designed and installed at two refineries for fouling data. Each fouling test unit contains test sections with a heat transfer monitor, an onboard computer for acquiring data, controls and instruments, an piping networks for start-up, sampling, and shut-down procedures. Both units are designed according to ASTM specifications for service in refinery or chemical plants. One fouling test unit is designed for two-phase flow of hydrogen and the product stream, the second for single-phase flow of crude oil, which has two heat transfer monitors operating independently. Calculation procedures for the heat transfer coefficient and fouling resistance are presented along with heat transfer data for air and water obtained at Argonne National Laboratory and crude oil obtained at the Shell Wood River refinery. Comparisons are made with the theoretical heat transfer coefficients

High-temperature organic-fluid fouling unit

A new type of fouling unit is developed for high-temperature (500 C) and high-pressure (70 atmosphere) fouling experiments by modifying a commercial autoclave. Key modifications are the installation of a helical impeller in a flow tube and a fouling probe in the autoclave to simulate the fluid dynamics and heat transfer of typical heat-exchange equipment. A calibration technique is described, and fouling results are presented for experimental runs with indene and kerosene. The results are compared with those obtained using other types of fouling test units. Other potential applications of the fouling unit, such as corrosion and micro-scale reaction experiments, are discussed

Experimental and analytical study of condensation of ammonia-water mixtures

The need for more energy efficient power generation and recent environmental issues of CFCs prompted the development of combined steam and Kalina cycle power systems, and advanced ammonia/water absorption heat pumps. However, the working media and associated thermal design aspects require new concepts for maintaining high thermal effectiveness and phase equilibrium for achieving maximum possible thermodynamic advantages. In the present study, a theoretical analysis was carried for the condensation of ammonia/water mixtures on a vertical tube. A set of equations was formulated and a calculation algorithm was developed to predict the local rate of heat and mass fluxes for binary ammonia-water systems. The predicted rate of condensation was compared with the experimental data obtained at Oak Ridge National Laboratory (ORNL) for a mixture of 90% ammonia and 10% water. The role of diffusion in simultaneous heat and mass transfer associated with condensation was analyzed by comparing the results from three limiting cases, which include equilibrium conditions, and liquid-phase diffusion of finite and infinite values. The results showed that the vapor-phase diffusion is a controlling mechanism