FEA Analysis of an Elevated Temperature Vessel used in Glass Fiber Production

We performed an (FEA) design analysis of elevated temperature pressure vessels – used in glass fiber production. At these high temperatures creep rupture, creep ratcheting are major concerns.

The glass fiber manufacturing process involves (high temperature) impure molten glass entering the piston-less pump comprised of the two vessels. Pressurized nitrogen is forced into the two cylinders at intervals. As one cylinder pumps, the other fills then pressurizes. When the glass level in the pumping cylinder becomes low, the idle cylinder (already filled and pressurized) takes over pumping. This ensures that the downstream glass flow pressure is constant. Typical operating conditions are 1,900 ºF and 150 psi. The dimensions of the cylinders were chosen for pump cycle times of 90 seconds at a glass flow rate of 2,400 pounds per hour of glass. A more typical flow rate will be 1,200 pounds per hour so the volume can be cut by half or the cycle time can be doubled. Ideally the pump will last 2,200 hours (1/4year) before it fails or has to be replaced.

The process involves impure molten glass at high temperature flowing through an inlet header, into the vessel – from where it’s discharged to an outlet header and fed to the glass fiber-making process downstream. Each vessel has an inlet and outlet header, which are controlled by four check valves. The check valves allow the vessels to alternate between a fill condition and a discharge condition.

When a vessel is in the fill condition, it is at atmospheric pressure or at a slight vacuum to help the glass flow. For the discharge condition, the vessel is pressurized to 150 psi to feed the molten material to the downstream processes. This cycle is repeated every 90 seconds, alternating between the two vessels to maintain a constant supply to the downstream equipment.

The expected life for the (Cast Haynes 188 Alloy) pressure vessels are 2,200 hours at 1,900 ºF. Each vessel has an inlet nozzle, an outlet nozzle, and a vent nozzle. At these high temperatures, creep rupture, creep ratcheting and creep fatigue damage are major concerns regarding the life of the vessel. ASME Code Procedures were used in the analysis. Finite Element Models were created using 2D axi-symmetric elements and 3D solid elements.

 We Perform Elevated Temperature Design and Analysis on Equipment for Clients in Industries including Manufacturing, Energy, and Aerospace.