Part one of a four-part series that will cover alignment fundamentals and thermal growth, and highlight the importance of field measurements through two case studies. Despite the best efforts to precisely align rotating machinery shafts, dynamic movement (commonly believed to be due to the thermal growth of the machine casings) has resulted in machines operating at less than optimum alignment conditions. This vexing problem has plagued machine reliability professionals for decades.
I was recently engaged by a client to conduct failure analysis on a large (and expensive) double-acting cylinder off a hydraulic excavator. This cylinder had been changed-out due to leaking rod seals after achieving only half of its expected service life. Inspection revealed that apart from the rod seals, which had failed as a result of the ‘diesel effect’, the other parts of the cylinder were in serviceable condition. The diesel effect occurs in a hydraulic cylinder when air is drawn past the rod seals, mixes with the hydraulic fluid and explodes when pressurized.
The secret to making and keeping reliable electrical connections is contained in two elements: start with clean contact surfaces, and apply high force. Clean contact surfaces are a function of cleaning procedures, including joint compounds, and will be covered in a future article. Application of high force is the subject here. The trouble comes about because the terms “torque” and “force” are incorrectly used interchangeably. Force is NOT torque. Force is a function of torque.
In 1997-98, the facility was considering replacing the aging (1972-73) high, medium, and low voltage equipment because of several operational and maintenance problems with the breakers. We also were concerned about the overall grounding scheme of the facility. To find out the existing status of the grounding system, we procured architect/engineer (A/E) services to check and confirm the overall validity of the facility-grounding scheme.
Using many of its own products and solutions, Schneider Electric was able to realize an energy savings from 2005 through August 2008 that totaled more than $5.1 million. In addition, the company’s goal of reducing energy consumption per employee by ten percent by 2008 was met two years ahead of schedule.
Machine conditions change from the time the machine is off line to when it is running under normal operating conditions. Some of these changes are due to process forces (e.g., fluid pressures, airflow, etc.). The most notable of these changes is the change in the temperature of the machine bearings and supports. This is called the machine’s thermal growth.
Hidden from view in a typical coal-fired power plant is a battle that never ends. Coal attacks steel and alloy components when the fuel is transported about the plant. Predictably, over time, the abrasive nature of coal will prevail against any metal surface because metal will eventually erode. The only opportunity for metal surfaces to have a fighting chance is to advance the secret weapon: ceramics.
The cost per kWhr, the “cost of producing electricity”, is the cost of the energy which is taken out of the steam by the turbine generator system and converted into electricity. The following paper discusses calculation methods for determining this cost — a critical step in the process of evaluating cogeneration feasibility.
The moral: Even when you think you have found the best solution, put the problem aside and then ponder it again. A fresh look may lead to an even better solution. As for the integral desuperheater, it is too elegant a solution to go to waste. Perhaps you may have a use for it.