Abstract:
A system (10) particularly suited for employment for purposes of effectuating the monitoring, diagnosing and controlling of the chemistry of the water and steam in a steam generator steam cycle (46). The subject system (10) is operative to monitor water and steam quality at a number of critical locations (70, 72, 74, 76) in the steam generator steam cycle (46). Based on the information gathered through such monitoring of water and steam quality, the subject system (10) is designed to be operative to provide diagnoses of potential causes of upsets in the steam generator steam cycle chemistry and to suggest corrective actions as appropriate. Furthermore, historical data is also readily available from the subject system (10) which can be utilized for identifying trends and for assessing the operational chemistry of the steam generator steam cycle (46) both on a short-term basis and on a long-term basis.
Abstract:
A distributed control system controlling a plurality of energize-to-start, energize-to-stop subprocesses is designed for on-line maintenance. One or more of the process control computers (86) forming the distributed control system (86-100) can be removed from service and the input and output connections (130) thereto switched to another of the process control computers that remains on-line. A bumpless transfer of control is achieved by reconstructing the status of the latches in the process control computer (86) removed from service that are history dependent and establishing that status in the latches of control circuits of the process control computer (96) assuming control. The status that the history dependent latches should have is derived based upon the operating status of the subprocess at the time switching is complete. Control functions dependent on the status of a latch are delayed until the reconstructed status of latches are complete.
Abstract:
A direct-fired, pulverized coal-fired furnace (2), wherein the fuel supply system is modified so that a load carrying pulverizer (10) supplying pulverized coal to the furnace through a plurality of burners (4) may simultaneously also supply pulverized coal to a storage bin (16) for storage therein until needed to start-up, warm-up and stabilize the low load firing of the furnace (2) at a later time.
Abstract:
A gas turbine (10) combined cycle system with a heat recovery steam generator (12) which may include enclosed adjacent cavities (30) may accumulate combustible gas mixtures during shut-downs. Gas detectors (38, 46, 48) located in the heat transfer section (30) of the heat recovery steam generator (12), in related duct work (16) and in the adjacent cavities (30) detect the presence of these gas mixtures and produce appropriate signals. A signal from the detectors (38, 46, 48) in the cavities (30) initiate the aspiration (42) of the mixture from the cavity (30). Signals from the detectors (38, 46, 48) in the heat transfer section and ducts as well as from the cavities (30) control the gas turbine (50) so that upon start-up, no fuel is introduced to the gas turbine (10) so that the gas turbine (10) forces purge air through the heat recovery steam generator (12). When all of the signals indicate that no combustible gas mixtures are present, the gas turbine (10) is ignited.
Abstract:
A buckstay system (32) of an associated furnace (10) having a combustion cavity (12) with a front waterwall (11), a rear waterwall (11), and opposed left and right side waterwalls (11) joining the front and rear waterwalls (11) and where the waterwalls (11) are arranged in a generally square pattern about the cavity (12). The cavity (12) has four corners and each buckstay (32) an attachment module (36, 36a) welded to each end, each attachment module (36, 36a) including first and second planar plates (36, 36a). The first and second planar plates (36, 36a) are disposed in side abutting relationship to the web (38) of the buckstay (32) and extend beyond the end of the buckstay (32); each of the first and second plates (36, 36a) has coaxial pivot holes (40) disposed in a part thereof that extends beyond the end of the buckstay (32). The planar plates (36, 36a) in the attachment module (36, 36a) may be rectangular, or have a notch or recess (40) for clearance. A spacer (44) may be disposed intermediate the planar plates (36, 36a)in the attachment module (36, 36a) and the spacer (44) may have a thickness substantially equal to the thickness of the web (38) of the buckstay (32) for which the attachement module (36, 36a) is intended.
Abstract:
A lug (30) for attachment to a waterwall (11) and for supporting a load on the waterwall (11) which is a part of steam generation apparatus (10) and which includes a web shaped metal plate formed in a generally arch shape. The arch shape has first and second legs (32, 34), each of the legs (32, 34) being dimensioned and configured for engagement with a part of the axial extent of respective associated tubular members (20) in an associated waterwall (11). In some forms of the invention each of the legs (32, 34) includes a generally planar portion and each of the legs (32, 34) has an axial extremity that is rectilinear. The axial extremity of each leg (32, 34) that is rectilinear may be disposed within the generally planar portion of the leg (32, 34). The lug (30) may be fabricated from a single piece of metal and the generally planar portions in respective legs (32, 34) are disposed in respective planes that intersect at an angle that is less than 90 degrees or even 30 degrees. In still other embodiments of the invention the generally planar portion is disposed in respective legs (32, 34) of the lug (30) that are mutually parallel.
Abstract:
The feedwater of a steam generator (10) and particularly the feedwater to a heat recovery steam generator (10) is injected with non-volatile chemicals such as trisodium phosphate to maintain a desired pH. The use of the non-volatile chemicals is possible because the system includes the recycle of blowdown from the steam drums (28, 48, 54) to the feedwater line at a point downstream from the condensate pump (20) and downstream from where feedwater (18) is extracted for attemperation.
Abstract:
An alarm significance mapping method assigns the subset of parameters and their alarms considered to be of a safety-critical nature in an industrial control system and displays that subset on an apex screen display and other selected appropriate displays, such as a touch-responsive display in the form of alarm icons for presentation to the system operators. Each alarm icon on the "apex" display is coupled or concatenated to other displays through a display page hierarchy so that the operator, by selecting a particular alarm icon on the "apex" screen, can follow the alarm "thread" through the multi-level display page hierarchy to the ultimate condition or conditions that cause an alarm on the "apex" screen.
Abstract:
An automatic self-testing system includes a plurality of sensor processing channels (100A-100D) or paths each having a sensor (102A-102D) for providing, either directly or indirectly, a digital value to a comparator (106A-106D) which compares the measured value with predetermined value that is, in turn, provided to coincidence logic (108A-108D) that evaluates the output of its comparator with the output of the comparators of the other paths to provide an output indicative of a pass/fail condition. Each sensor processing path includes two sub-paths that can be associated with or switched into the processing path while the dissociated sub-path undergoes off-line testing by a test processor. Testing is effected by providing a digital value to the sub-path under test while sensing the output to determine the functional validity of the sub-path under test. The combinational logic state of the system is monitored and converted into a decimal value that is compared with the set of decimal values corresponding to the finite known-good logic states of the system. The appearance of a decimal value that is not a member of the set of decimal values for the known-good logic states is thus an indication of a failure.
Abstract:
In order to reduce the number of lifts which are required to remove the various equipment normally disposed above the reactor pressure vessel (100) and to make way for refuelling or regular maintenance, the control rod element drive mechanisms (112) are completely enclosed within a cylindrical enclosure (106) which is attached to the head of the pressure vessel. The top of the cylindrical enclosure (106) is closed with a cap-like member (116) which acts as both a missile shield and a head area cable tray (116a). The missile shield (116), the cylindrical enclosure (106), the control rod drive mechanisms (112) and the pressure vessel head (110), are connected to form an integral unit which can be removed in a single lift. Cable trays (130) are pivotally supported on a wall of a building to establish a bridge between the building and the head area cable array and to establish a connection with the control element drive mechanism cables (128). During lifting, the control element drive mechanism cables (128) are disconnected and the pivotal bridge trays (130) are swung out of the way. During normal operation, the cylindrical enclosure (106) guides a flow of cooling air over the control rod drive mechanisms (112).