Do You Know Where Your Water Is?
March 11, 2008
Typically March in Texas is not a time to expect snow to fall; but it did. While we don’t know when we are going to have freezing water fall from the sky, hopefully we have more control over our operating units – freezing water in our sky is much better than freezing water in our gas plants.
Water content is important for predicting these freeze conditions, including hydrate formation, as well as corrosion in the plants. This is especially true in units containing H2S and CO2 as these tend to exacerbate these issues.
Phase envelopes with ice, dry ice and hydrate lines are very helpful in determining how safe your unit is operating. However, these diagrams are only as good as the simulator that generated them. ProMax has the unique ability to predict multiple hydrate, ice, or solid CO2 formation points. Most simulators only calculate the highest formation temperature; however ProMax will predict up to three solids formation temperatures and plot them directly on the phase envelope. Depending on the operating conditions of the plant, the highest formation temperature may not be the one of most relevance.
Critical of all these calculations is the proper prediction of water content during processing, especially in the presence of H2S and CO2. What may seem to be a trivial difference, can actually have a very significant impact. For additional information on this topic, please refer to the John M. Campbell website and read the December 2007 “Tip of the Month”.
So keep the freezes outside by truly knowing where your water is.
Authored by Craig Spears - BR&E Sales Department