OPPORTUNITY CRUDE SAMPLING METHODOLOGY AND IMMISCIBLE FLUID MIXING TECHNOLOGY

摘要

With the advent of new 'fracking' technologies to produce shale oils, 'opportunity crude oils' are increasingly a source of both major cost benefits and major operating risks. These oils are mostly transported as an oil-water mixture that can vary widely, and the economics of accurately quantifying the water content in the mixture has become increasingly important. For example, in custody transfer applications, standards ISO 3171 (1) and API 8.2 (2) are followed to conduct quality sampling. Sampling must start with efficient mixing if the extracted sample is to provide reliable laboratory analysis using protocols such as Karl-Fischer. Achieving a truly homogeneous mixture of immiscible fluids such as oil and water is challenging and can benefit from new advanced mixing technologies such as SmartMix®. These technologies are also believed to provide significant financial and operational benefits. For example in refineries, by accurately quantifying the (salt) water in purchased opportunity crude oil feed stocks, by improving the efficiency of crude desalter units, and by reducing the use of corrosion inhibiters and other expensive chemicals. Testing has confirmed that current sampling methodologies (including API 8.2 and ISO 3171) may not provide representative samples of the actual oil and water mixture. Traditional sampling can result in concentration variations (C1/C2) across the pipe that can result in customers paying millions of dollars for salt water. In extreme cases, crude oil distillation column steam explosions have caused losses of weeks of refinery production and destruction of millions of dollars of downstream water-soluble catalysts. Improved mixing technology is believed by major refiners' professional personnel and major process design firms' senior personnel to be advantageous for optimization of Desalter process units and may even replace high-shear mixing valves. It is also of interest to the NACE (www.nace.org) professional community to reduce corrosion in piping and vessels by improving ion exchange (sodium cations replacing calcium and magnesium cations) in corrosive chloride compounds. These sodium salts are easier to thermally destroy or aqueously dissolve. The described mixing technology is shown to allow compositions to be measured to much higher resolution. It is therefore believed by major refiners and process design firms to be able to minimize addition of treatment chemicals. Real-time data (rather than traditional lab sampling) can facilitate optimization of chemicals addition, rather than treating the 'worst case'. This paper describes experimental investigations that have been carried out on oil-water flows to characterize the effectiveness and efficiency of a novel mixing technology (SmartMix®). This technology uses a novel multi probe profiling (MPP) iso-kinetic sampling device (scoop) and a liquid jet in cross-flow phase homogenization nozzle. This was achieved in two ways. First, samples were withdrawn through the MPP across the whole pipe diameter. Second, through the tubes connected to the MPP, in-line measurement of (iso-kinetic) velocities, pressures and temperatures are captured with an accurate mass flow meter possessing ancillary density functionality. The water fractions through each iso-kinetic probe element are calculated from the homogenous measured densities. According to a method developed in this study to quantify the water fraction at the prevailing temperature and pressure, the degree of homogeneity is measured at 97.2%. This is much higher than other published performance data cited (3), resulting in potentially significant financial benefits.