Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2001-08-02
2003-02-04
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C060S039281
Reexamination Certificate
active
06516263
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to control techniques and systems for preventing flame-outs in generating systems.
2. Background Art
For flame-out prevention in microturbines, one has to determine a flame-out fuel flow limit (lean blow-out schedule) and then use sensor feedback during microturbine operation to make sure that one does not go below the flame-out limit. Illustrative of prior methods which accomplish this (or treat similar problems) include U.S. Pat. No. 5,819,196 (Method and system for adaptive fuel delivery feedforward control); U.S. Pat. No. 5,272,637 (Method and apparatus for controlling the supply of fuel to a gas turbine during load rejection); U.S. Pat. No. 5,083,277 (Fuel Control System); U.S. Pat. No. 4,783,957 (Fuel Control circuit for a turbine engine); and U.S. Pat. No. 3,832,846 (Speed governor with fuel rate control).
Microturbines are high speed, single or dual shaft, low compression turbine-driven generators of electricity and/or other power, and producing up to about 500 kW. They are multi-fuel, modular distributed power generation units having multiple applications. They offer the capability to produce electricity at a lower cost per kilowatt than do central plants, and they do not require the installation of expensive infrastructure to deliver power to the end users. Thus, in parts of the world lacking the transmission and distribution lines of a basic electric infrastructure, commercialization of microturbines may be greatly expedited. In the United States and other countries already having a suitable electric infrastructure, distributed generation units will allow consumers of electricity to choose the most cost-effective method of electric service. In addition to primary power generation, microturbines also offer an efficient way to supply back-up power, uninterruptible power, peak-shaving, and combined heat (or chilling) and power through the use of cogeneration equipment. Other applications for microturbines exist as well.
The present invention operates to make a subsequent flame-out less likely after a flame-out has occurred. It increases the lean blow-out schedule for the next time that the microturbine runs. This process repeats until either there are no more flame-outs, or one hits a fuel flow limit (e.g., a maximum offset of 1.5 lb/hr). The present invention permits use of both inexpensive fuel controls and inexpensive fuel flow sensors. In a small percentage of engines, flame-outs will occur. The present invention automates resolving the problem in the long run, rather than using substantially more expensive and accurate sensors.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
The present invention is of an automated system and method for preventing flame-outs in turbine power generating systems comprising: establishing a minimum fuel schedule for a turbine; detecting occurrence of a flame-out of the turbine; and automatically increasing the minimum fuel schedule for the turbine. In the preferred embodiment, the turbine is a microturbine. Detecting is of a speed droop shutdown of the turbine. Detecting is repeated after increasing and the increasing step is repeated such that the minimum fuel schedule does not exceed a maximum offset from the minimum fuel schedule established in the establishing step. The minimum fuel schedule is increased by a predetermined increment. Execution of the invention is preferably by an electronic control unit of a fuel flow control system for the turbine, and using fuel flow sensors having a tolerance of between approximately +/−4% and +/−10%.
Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
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Desmond, Esq. Robert
Honeywell Power Systems Inc.
Zanelli Michael J.
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