Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF THE WALL TEMPERATURE ON INORGANIC SCALE DEPOSITION IN PIPES
Submission Author:
Gabriel Siqueira Machado , RJ
Co-Authors:
Gabriel Siqueira Machado, Eric Dittrich, Pedro Petindá, Juliana Loureiro
Presenter: Gabriel Siqueira Machado
doi://10.26678/ABCM.ENCIT2022.CIT22-0446
Abstract
Calcium carbonate scale formation is a recurring problem in oil exploration in the Brazilian pre-salt. This phenomenon occurs with greater severity in heat exchangers located on the top side of oil platforms, as the solubility of calcium carbonate is inversely proportional to temperature. The objective of this work is to experimentally investigate the influence of a local wall temperature raise on the deposition of inorganic scale inside pipes. The experimental apparatus is an open circuit flow loop, which consists of a 65 meter long pipe, 11 mm internal diameter, equipped with flowmeters and pressures transducers. The working fluid is a mixture of two incompatible brines, i.e., water-based solutions of calcium chloride (CaCl2) and sodium bicarbonate (NaHCO3). The heated wall test section is 1 m long and can be installed at different locations of the flow loop. The wall temperature of the heated pipe is adjustable and can be kept constant during the test up to a maximum value of 80oC. Measured data include absolute pressure, mass flow rate and the pH of the mixture. At the entrance and exit of the heated test section, the values of differential pressure, fluid temperature and pH of the mixture are monitored. Along the pipe, including the heated section, removable sections allow the measurement of the mass and thickness of the deposited material, as well as crystallographic analysis in a scanning electron microscope (SEM). The present results indicate that the calcium carbonate structure changes from calcite to aragonite due to the higher wall temperature. The deposited layer of scaling on the heated pipe wall is also thicker in comparison to the ambient temperature reference test. The database generated in the present work allows the estimation of the scaling rate as a function of the wall temperature. These results will be further used to validate kinetic and diffusion-reaction models under development in the research group.
Keywords
Calcium carbonate, Scale formation, experimental work, Scanning Electron Microscope, Wall temperature, Deposite scale
