A New Dual-Channel Analyzer for Vibration of Rotary Machine

A new simultaneous sampling and analyzer for dual-channel signal of vibration for rotating machine is developed based on the C8051F060, which is a high-speed SoC system and has two ADCs embedded with high sampling frequency. The signal condition circuits for various vibration sensors are designed, such as charge amplifier, integral transform and rotating speed detector. A colorful TFT LCD used can display all kinds of vibration analysis plots that are friendly in human-machine interface. The large capability non-volatile memory is used to restore up to one hundred of group of vibration waves. With many typical functions of vibration analysis, including waveform analysis, spectrum, orbit and balancing, this instrument is widely applied to vibration measurement and fault diagnosis of machine and equipment, especially for field balancing of rotary machine.

Greenhouse Gas Emissions Calculation Methodology in Thermal Power Plants: Case Study of Iran and Comparison With Canada

Nowadays, the global climate change has been a worldwide concern and the greenhouse gases (GHG) emissions are considered as the primary cause of that. The United Nations Conference on Environment and Development (UNCED) divided countries into two groups: Annex I Parties and Non-Annex I Parties. Since Iran and all other countries in the Middle East are among Non-Annex I Parties, they are not required to submit annual GHG inventory report. However, the global climate change is a worldwide phenomenon so Middle Eastern countries should be involved and it is necessary to prepare such a report at least unofficially. In this paper the terminology and the methods to calculate GHG emissions will first be explained and then GHG emissions estimates for the Iranian power plants will be presented. Finally the results will be compared with GHG emissions from the Canadian electricity generation sector. The results for the Iranian power plants show that in 2005 greenhouse gas intensity for steam power plants, gas turbines and combined cycle power plants were 617, 773, and 462 g CO2eq/kWh, respectively with the overall intensity of 610 g CO2eq/kWh for all thermal power plants. This GHG intensity is directly depend on efficiency of power plants. Whereas, in 2004 GHG intensity for electricity generation sector in Canada for different fuels were as follows: Coal 1010, refined petroleum products 640, and natural gas 523 g CO2eq/kWh, which are comparable with same data for Iran. For average GHG intensity in the whole electricity generation sector the difference is much higher: Canada 222 vs. Iran 610g CO2eq/kWh. The reason is that in Canada a considerable portion of electricity is generated by hydro-electric and nuclear power plants in which they do not emit significant amount of GHG emissions. The average GHG intensity in electricity generation sector in Iran between 1995 and 2005 experienced 13% reduction. While in Canada at the same period of time there was 21% increase. However, the results demonstrate that still there are great potentials for GHG emissions reduction in Iran’s electricity generation sector.

The Case for Combining Pump Maintenance and Systematic Upgrading

Virtually, all industrial machinery requires periodic maintenance for dependable long-term operation. In fact, the very term “maintenance” is defined as keeping machines in the as-designed or as-purchased and manufactured condition. At issue is whether the equipment owner’s profitability objectives are best served by “maintaining only”, or by judiciously combining maintenance and upgrading tasks. Assuming the answer favors combining maintenance and upgrading, the question arises whether an intelligent and well thought-out combination of maintenance and upgrading should be entrusted only to the original equipment manufacturer (OEM), or if qualified non-OEMs should be considered also. The co-authors would like to offer their answer to the question. Experience shows that a highly qualified independent rebuild shop with demonstrated capabilities and experienced personnel can offer high-quality upgrades that improve both uptime and efficiency. Such a shop can do so consistent with current system performance requirements. With the considerable consolidations in the pump industry, the distinct possibility exists that the OEM is not able to offer the same engineering competence he previously had and that independent shops should be considered. This presentation deals with a case study and details where such upgrading was being planned, implemented, and verified to have had the desired results. It further explains the role played by competent pump rebuild shops (we chose to call them “CPRS”) in these important endeavors. Our work supports the premise that rebuilding a vintage process pump to original OEM specifications makes no sense, given current pump rebuilding technology and changes to the system performance that occur over time. We find compelling reasons to systematically upgrade the efficiency and potential run length of large centrifugal pumps. Of course, this upgrading must be pre-planned and then carried out during a future maintenance outage.

Gas Turbine Efficiency (GTE) Benefits of GTE Water Wash Systems

The desire to maintain power plant profitability, combined with current market fuel gas pricing is forcing power generation companies to constantly look for ways to keep their industrial gas turbine units operating at the highest possible efficiency. Gas Turbines Operation requires the compression of very large quantities of air that is mixed with fuel, ignited and directed into a turbine to produce torque for purposes ranging from power generation to mechanical drive of pumping systems to thrust for air craft propulsion. The compression of the air for this process typically uses 60% of the required base energy. Therefore management of the compression process efficiency is very important to maintain overall cycle efficiency. Since fouling of turbine compressors is almost unavoidable, even with modern air filter treatment, and over time results in lower efficiency and output, compressor cleaning is required to maintain gas turbine efficiency.

Is Your Power Plant Headed for a HILP? How to Avoid, Detect or Mitigate High Impact–Low Probability (HILP) Events

In recent years some power companies have instituted programs aimed at reducing or eliminating their power plants’ unreliability caused by abnormal events that occur infrequently but result in extended unplanned outages when they do occur, i.e. High Impact–Low Probability events (HILPs). HILPs include catastrophic events such as turbine water induction, boiler explosions, generator winding failures, etc. Many of these successful programs have relied on the detailed reliability data contained in the North American Electric Reliability Corporation’s (NERC) Generating Availability Data System (GADS) that contains data collected over the past 25 years from 5000+ generating units in North America. Using this data, these companies have been able to 1) benchmark their fleet’s unreliability due to HILPs against their North American peers, 2) prioritize their peer group’s susceptibility to various HILP modes and 3) use root cause data contained within the NERC-GADS data base to help identify and evaluate ways to proactively prevent, detect and/or mitigate the consequences of HILP events. This paper will describe the methods used in these successful programs in sufficient detail to enable others to adopt the techniques for application at their own generating plants.

Mechanical Seal Efficiency Considerations for Pumps in Utilities: Economics of Seals vs. Packing, and Savings With Best Available Seal Flush Arrangements

Applicable industrial standards for centrifugal pumps endorse several different sealing options as “best practice.” However, the overall acceptance of best practice techniques seems slow and is linked to the fact that sealing devices account for only a small fraction of the energy consumed by pumps. Yet, regardless of perception, significant energy conservation has been achieved by thoughtful sealing practices, as this paper will show. It will highlight case studies that provide guidance on issues of increasing technical and societal concerns relating to fluid emissions. Special attention will be directed to barrier fluid circulation devices used in dual mechanical seal arrangements as described by API-682 (Ref.1), a Standard widely used in the oil refining and petrochemical industries. The applicability of these ciculation devices to the Power Industry will be explained. Comparisons of three of the most widely used conventional integral flow induction/pumping ring devices will be made and the results of extensive testing presented. The paper and presentation also quantifies the value of advanced sealing technologies for pumps and highlights configurational differences between the newer and the more traditional (older) devices. Without exception, international utilities and power producers know that both energy and maintenance expenditures are affected by availability and reliability considerations relating to power generators and their turbine drivers. But feed water pumps and cooling water issues play their part as well. Consequently, a measure of attention has been given to “other big ticket items”, such as cooling tower losses and the like. However, there is compelling evidence that additional, less prominent or less obvious opportunities exist and that these can no longer be overlooked. Pump sealing falls into that category, although sealing devices and seal cooling account for only a small fraction of the energy consumed by pumps. In can be readily shown that significant energy savings have been achieved by thoughtful sealing practices. The general narrative and the implications conveyed by our case studies give visibility to the issues and provide guidance to the user.

CFD Study on Vermiculite Injection System Optimization in a Cyclone-Fired Boiler

Boilers firing low-rank coal generally experience high levels of slagging and fouling. To help manage convective pass fouling, various additives or conditioners can be injected into the boiler furnace high temperature region as physical disruptors of slag deposits, exhibiting a varying density or gas evolution, which physically breaks up slag or as chemical modifiers of the ash to increase its softening temperature. Vermiculite is one additive that has been applied with success; however, it is important to ensure that the injected material is placed in the most heavily slagged and fouled areas. The purpose of this study was to evaluate the effectiveness of a vermiculite injection system installed on a large cyclone-fired boiler and to identify improvements in the injection system that would permit more effective treatment of the areas of interest. During the study, a million-cell full boiler combustion model was developed. Typical features of the furnace flow and temperature field were obtained. Considering the particular operating conditions and features of the upper furnace flow field (biased gas velocities and rotational flow), optimized injection schemes were proposed. This study shows the usefulness of applying CFD to solve slagging and fouling issues for coal-fired boilers.

Sensitivity Analysis and Application of Natural Frequency of Torsional Vibration of Rotor System

The disturbance of electric power system makes large-scale turbine-generator shafts generate torsional vibration. A available method to restrain the torsional vibration of turbine-generator shafts is that all the natural frequencies of torsional vibration of turbine-generator shafts must keep away from the working frequency and its harmonic frequencies as well as all the frequencies that possibly bring on interaction between turbine-generator and electric power system so that the torsional resonation of shafts may not occur. A dynamic design method for natural frequencies of torsional vibration of rotor system based on sensitivity analysis is presented. The sensitivities of natural frequency of torsional vibration to structure parameters of rotor system are obtained by means of the theory of sensitivity. After calculated the torsional vibration dynamic characteristics of original shafts of a torsional vibration stand that simulates the real shafts of 300MW turbine-generator, the dynamic modification for the torsional vibration natural frequency is carried out by the sensitivity analysis method, which makes the first-five natural frequencies of torsional vibration of the stand is very close to the design object. It is proved that the sensitivity analysis method can be used to the dynamic adjustment and optimal design of real shafts of turbine-generator.

Condenser Tube Examination Using Acoustic Pulse Reflectometry

Acoustic Pulse Reflectometry (APR) has been applied extensively to tubular systems in research laboratories, for purposes of measuring input impedance, bore reconstruction, and fault detection. Industrial applications have been mentioned in the literature, though they have not been widely implemented. Academic APR systems are extremely bulky, often employing source tubes of six meters in length, which limits their industrial use severely. Furthermore, leak detection methods described in the literature are based on indirect methods, by carrying out bore reconstruction and finding discrepancies between the expected and reconstructed bore. In this paper we describe an APR system designed specifically for detecting faults commonly found in industrial tube systems: leaks, increases in internal diameter caused by wall thinning, and constrictions. The system employs extremely short source tubes, on the order of 20cm, making it extremely portable, but creating a large degree of overlap between forward and backward propagating waves in the system. A series of algorithmic innovations enable the system to perform the wave separation mathematically, and then identify the above faults automatically, with a measurement time on the order of 10 seconds per tube. We present several case studies of condenser tube inspection, showing how different faults are identified and reported.

Verifying Suitability for Service With EMI Diagnostics

This paper provides examples of conditions found with nuclear plant electrical equipment by the application of EMI (electromagnetic interference) Diagnostics. This is an on-line test that can detect a wide variety of defects in motors, generators, power cables transformers and isolated phase bus. There is no interruption to service and no risk to the system while data is collected. Photo 1 shows the temporary placement location of a RFCT (radio frequency current transformer) to collect EMI data from this CWP motor. Photo 2 shows the RFCT application on the generator stator grounding transformer. This is the preferred location to collect generator system data.