Maximum Allowable Pressure Calculation of Water Tube Boiler during Operation

In the steam boiler industrial sector, pressure and temperature of the water tube are the two main factors that affect the safety and efficiency of a steam boiler. Explosions may be occurring because of a sudden drop in pressure without a corresponding drop in temperature. Therefore, understanding the temperature distribution of the water tube boiler is essential to control the failure and explosion of the boiler. Once the temperature distribution is known than the limiting factors that affect the water tube life such as the maximum allowable pressure can be determined. ANSYS software will be used to determine the temperature distribution in the water tube of a utility boiler during operation at elevated inlet water and furnace temperature. The theory of axisymmetric has been utilized since the water- tube is cylindrical in shape. In axisymmetric theory, a three-dimensional cylindrical problem like a water tube can be reduced to two-dimensional by ignoring the circumferential Ө, while the r-axis and z-axis became x-axis and y-axis or Cartesian coordinate. Then two-dimensional rectangular elements meshing for the profile cross-section along the water tube in r and z axes were implemented in a computerized simulation using ANSYS 10 to find out the steady-state temperature distribution of the water tube.

Fullerene-like Nanoparticles of WS2 as a Promising Protection from Erosive Wear of Gun Bore Nozzles

Background: Erosive wear causes increase in the bore diameter of firearms barrels and nozzles. Most responsible factors for this erosion are friction and heat generated during the shot. Protection from erosive wear is very important for gun tube life cycle, and various protection methods are used: adding phlegmatizers in gunpowder composition or applying protective layers on the gun bore inner surface. Objective: In this research, a possibility is examined to protect the surface of a nozzle exposed to gunpowder erosion applying a layer of tungsten disulfide fullerene-like nanoparticles, IF-WS2, known as outstanding solid lubricant of a great mechanical resistance. Methods: Nanoparticles on the nozzle surface before and after the gunfire tests were observed using scanning electron microscopy/energy dispersive X-ray spectroscopy. Gunfire tests were performed on designed erosion device. Temperatures in the defined position near the affected surface were measured with thermocouples and compared for the nozzles with and without nanoprotection, as well as the nozzle mass loss after each round. Results: For the sample with IF-WS2 lower temperatures after firing and lower mass losses were observed. Mass loss after first round was 25.6% lower for the sample with protective nanoparticles layer, and the total mass loss was about 5% lower after five rounds. After the first round the nozzle without IF-WS2 was heated up to a temperature which was for 150.8°C higher than the nozzle with IF-WS2. Conclusion: Protective function of IF-WS2 is the most pronounced for the first round. The observed results encourage its further application in firearms gun bores protection.

MAXIMUM ALLOWABLE THERMAL STRESSES CALCULATION OF WATER TUBE BOILER DURING OPERATION

In steam boiler industrial sector, pressure and temperature of the water tube are the two main factors that affecting the safety and efficiency of a steam boiler. Explosions may be occurring because of a sudden drop in pressure without a corresponding drop in temperature. Therefore, understanding the temperature distribution of the water tube boiler is essential control the failure and explosion of the boiler. Once the temperature distribution is known then the limiting factors that affect the water tube life such as maximum allowable thermal stresses can be determined. ANSYS software will be used to determine the temperature distribution in the water tube of a utility boiler during operation at elevated inlet water and furnace temperature. The theory of axisymmetric has been utilized since water- tube is cylindrical in shape. In axisymmetric theory, a three-dimensional cylindrical problem like water tube can be reduced to two dimensional by ignoring the circumferential Ө, while r-axis and z-axis became x-axis and y-axis or Cartesian coordinate. Then two-dimensional rectangular elements meshing for the profile cross-section along the water tube in r and z axes were implemented in a computerize simulation using ANSYS 10 to find out the steady state temperature distribution of the water tube.

Metal Temperature Prediction of a DLN1 Class Flame Tube by CFD CHT Approach

Combustor liner of present gas turbine engines is subjected to high thermal loads as it surrounds high temperature combustion reactants and is hence facing the related radiative load. This generally produces high thermal stress levels on the liner, strongly limiting its life expectations and making it one of the most critical components of the entire engine. The reliable prediction of such thermal loads is hence a crucial aspect to increase the flame tube life span and to ensure safe operations. The present study aims at investigating the aero-thermal behavior of a GE DLN1 (Dry Low NOx) class flame tube and in particular at evaluating working metal temperatures of the liner in relation to the flow and heat transfer state inside and outside the combustion chamber. Three different operating conditions have been accounted for (i.e. Lean-Lean partial load, Premixed full load and Primary load) to determine the amount of heat transfer from the gas to the liner by means of CFD. The numerical predictions have been compared to experimental measurements of metal temperature showing a good agreement between CFD and experiments.

Latest Developments in Optimizing Reformer Tube Life Through Advanced Inspection and Remaining Life Assessment

Steam methane reformer tubes must withstand high temperature and pressures during operation and are made from centrifugally cast austenitic materials, typically HK-40, HP Modified, and Micro-Alloy materials. Since operating conditions can result in various forms of damage, the identification and quantification of damage is of vital importance if tube life is to be predicted accurately. This paper describes the recent developments in an integrated inspection system which uses multiple NDT techniques to provide a most comprehensive assessment of current tube condition. This system is coupled with a sophisticated remaining life assessment software model which predicts the remaining life of each tube in a furnace.