Mitsuyo Nishikawa

Method and apparatus for monitoring the shaft vibration of a rotary machine

From the viewpoint of the preventive maintenance operation of a rotary machine, it is a very important subject to monitor the shaft vibration of the rotary machine and grasp the operating state of the machine. This invention relates to input processings in the case of executing the frequency analysis of a shaft vibration signal by digital processings. This invention describes the rotational frequency synchronization of a sampling frequency, the phase synchronization of the rotary machine to a reference phase, the relationship between an analytical wave number and a sample nunber, etc. in that case.

Method and apparatus for symptom diagnosis by monitoring vibration of shaft of rotary machine

A method of symptom diagnosis by continuously detecting vibration of the shaft of a rotary machine and monitoring a signal indicative of detected shaft vibration for the diagnosis of the operating condition of the rotary machine. In the method, a symptom of unusual operation of the rotary machine is diagnosed. The rotation speed range of the rotary machine is classified into a safety region, an alarm region and a trip region depending on the level of the shaft vibration signal. According to the disclosed method, symptom diagnostic regions are established within the safety region at time intervals of a symptom diagnostic period, and whether or not the level of the detected shaft vibration signal deviates from that of the symptom diagnostic regions is continuously monitored for the diagnosis of a symptom of unusual operation of the rotary machine.

A Combustion Diagnosis Method for Pulverized Coal Boilers using Flame-Image Recognition Technology

A flame image recognition system (FIRES) has been developed, which calculates the estimated value of NOX emission from pulverized coal combustion by two dimensional measurements and digital image processing of flame forms. This system can be effectively applied to low NOX and high efficiency combustion is industrial and utility boilers. ITV cameras observe the flame image in the vicinity of burners through optical-fiber probes attached to each burner stage, and a minicomputer digitizes and processes the image data. The NOX-reducing index (INOX), indicating the amount of NOX reduction can be calculated from the form and the location of high radiant intensity zones. Using INOX and stoichiometric ratio of combustion, NOX concentration in ehaust gases can be acculately estimated. This paper discusses the system concepts, NOX estimation algorithm and experimental results.

A Microcomputer Based Vibration Diagnostic System for Steam Turbines and Turbo-Generators in Power Plants

A new shaft-vibration diagnostic system for rotating machinery in power plants has been developed. This system, with its microcomputer, can be effectively applied to solve almost all the vibrational problems which occur during load operation or inspection. For frequency spectral analysis, the Walsh to Fourier transform is used with some modifications to reduce the microcomputer load. New firmware is also developed. With these improvements it is possible to diagnose simultaneously shaft vibrations for a five second period at a maximum of twelve points. This system has been successfully used in field tests to diagnose abnormal shaft vibrations caused by machinery unbalance or rubbing of steam turbines and turbo-generators.