DESCON Engineering - White Papers and Technical Papers

Technical Papers
Some Design Considerations for Oxygen Supplyin Gasification or GTL By Ron MacDonald, Ph.D. Director of Process Engineering Descon Engineering Summary - The oxygen plant for the syngas reactor in a gasification or GTL project represents a large portion of the installed cost and is probably the largest internal power consumer. Additionally, oxygen plants for such projects are sometimes among the largest in the World. Treating the oxygen plant simply as a package bought from an ASU vendor may not provide the optimum design of oxygen plant for the facility with respect to capital cost, efficiency, operability and reliability. Thus it is important for the project Owner to have expert input in the following areas.
Steam Flow Compensation Equations for Distributed Control Systems By Tom Carter Principal Control Systems Engineer Descon Engineering Summary - Temperature and Pressure compensation of steam flow corrects for two factors: 1) changes in Specific Volume (or density) of the steam and 2) thermal expansion of the metal flow nozzle or orifice plate. The Steam Flow Compensation Factor for Specific Volume is a function of both Temperature and Pressure. The specific volume factor is calculated from Steam Tables. The traditional compensation factor used is the ratio of square root of T and design P versus design T and P. The traditional yields an error of atleast 1.3 %. An error of less than 0.3% can be achieved for an operating range from 860 DegF to 1100 DegF and 1500 Psia to 2000 Psia using the polynomial described: an improvement in accuracy by over 1%.
Flow Compensation Equations for Boiler Feed Water in Distributed Control Systems By Tom Carter Principal Control Systems Engineer Descon Engineering Summary - A mass balance around a Boiler involves comparing steam flows out and water flows into the boiler. The density of water is a very non-linear function of Temperature resulting in errors greater than 18% in uncompensated measurements. The traditioanl method is to use Steam Tables to compensate for this error. However, most DCS Systems do not support Steam Tables. Using polynomial equations, an error of less than 0.58% can be achieved for an operating range from 50 DegF to 350 DegF and 0 Psia to 3500 Psia. An error of less than 1.3% can be achieved for an operating range from 350 DegF to 650 DegF and 500 Psia to 3500 Psia. The coefficients of these polynomial equations can be calculated in an EXCEL spreadsheet using simple slope and intercept functions.