Patent Number: 047626682
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an ultrasonic device for cleaning a venturi flow nozzle mounted in a pipe in a fluid system whereby the nozzle may be cleaned on line without requiring the system to be shut down. 2. Description of the Prior Art In operation of many industrial plants employing fluid systems having venturi flow nozzles therein, fouling of the venturi flow nozzles, particularly at or near the throat, occurs causing the flow indication to be higher than the actual or calibrated flow value. In these circumstances, the flow rate is less than actually indicated, and consequently, the output for the plant is reduced. This is particularly true in connection with pressurized water nuclear powered electric generating plants which employ venturi flow nozzles in the main feedwater pipe to measure the flow rate of the feedwater to the steam generator. In such plants, following the secondary side calorimetric and adjustment of the Nuclear Instrumentation System, indicated power is higher than the actual reactor power, and the plant thus operates below its licensed thermal limit. Because of this, the electrical output on such plants can fall short of its rated limit by as much as four percent, which in some plants can amount to 40 megawatts. While various means have been tried for correcting the problem of fouling of venturi flow nozzles, none have proved totally satisfactory. For example, one solution has been to install a handhole upstream of the venturi flow nozzle and manually insert a jet spray nozzle through the handhole to hose off and remove deposits for fouling on the inner surface of the venturi. This particular solution requires a plant shutdown and pipe drainage which is expensive and time consuming. Another solution has been to install leading edge flow meters which are not subject to fouling. Installation of such leading edge flow meters, however, can be expensive. At the present time, numerous utilities with nuclear power plants, in particular, are trying to find solutions to recovering lost megawatts due to feedwater venturi flow nozzle fouling. In view of the fact that a good solution to the fouling problem presently does not exist, such utilities are reluctant to implement any solutions, and consequently, they continue to lose megawatt output which is very costly. Accordingly, a need still exists for an economical device capable of easily cleaning venturi flow nozzles which is relatively inexpensive and easy to install and which does not require plant shutdown and pipe drainage. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an ultrasonic cleaning device for venturi flow nozzles which can be operated on line and does not require plant shutdown. It is another object of the present invention to provide an ultrasonic device for cleaning venturi flow nozzles which is automatic in operation and therefore does not have to be operated manually. It is still another object of the present invention to provide an ultrasonic cleaning device for venturi flow nozzles which is relatively inexpensive, easy to install and is essentially maintenance free. To achieve the foregoing and other objects of the present invention, and in accordance with the purpose of the invention, there is provided an ultrasonic cleaning device for a venturi flow nozzle mounted in a pipe in a fluid system which includes one or more transducer assemblies mounted around a pipe for producing and transmitting sound waves to the throat of the venturi flow nozzle. The transducer assemblies may be mounted on a plate mounted around the pipe. Each transducer assembly includes a transducer for generating sound waves, a horn attached to the transducer for concentrating the sound waves and a rod connected at one end to the horn and extending through an opening into the pipe so that the other end of the rod contacts the nozzle to transmit the sound waves thereto. The device further includes a guiding and sealing assembly for each rod which is attached to the pipe around each opening. Each guiding and sealing assembly includes a base member and a cover member, each having a central opening therein through which the rod passes, and sealing means surrounding the rod. In one of the embodiments the sealing means includes packing rings around the rod, while in another embodiment the sealing means includes a bellows surrounding the rod. The guiding and sealing assembly further may include spring means for biasing the rod towards the nozzle. In another embodiment of the invention, there is provided an ultrasonic cleaning device for a venturi flow nozzle mounted in a pipe in a fluid system which includes one or more transducers positioned adjacent the nozzle in the pipe for producing and transmitting sound waves to the nozzle. A mounting and sealing assembly is mounted in an opening in the pipe for each transducer for maintaining the transducer in position adjacent the nozzle and for sealing the opening. The mounting and sealing assembly includes a fitting threadably mounted in the pipe opening and spring means for biasing the transducer towards the nozzle. The transducer may include a threaded portion at one end for connection to the nozzle. In another embodiment, the mounting and sealing assembly includes a base member attached to the pipe and has a central opening therein in alignment with the pipe opening and wherein at least a portion of the fitting is threadably engaged with the base member. These, together with other objects and advantages, which subsequently will be apparent, reside in the details of construction and operation of the invention as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part hereof wherein like numerals refer to like parts throughout.