BONETTI RLG. Conductivity electrode type level indicators

Transcription

1 BONETTI RLG Conductivity electrode type level indicators

2 BONETTI Conductivity electrode type level indicators series RLG BONETTI electrode type level indicators RLG series (Resistive Level Gauge) are made up of three main components: - RLG/C pressure water column - RLG/E electronic metering, monitoring and transmission unit - RLG/P conductivity electrode PRINCIPLE OF MEASUREMENT The electronic unit (RLG/E) detects the presence of either water or steam around one or more electrodes (RLG/P), by measuring the conductivity between the electrode tips themselves and the water column metallic wall (RLG/C). A suitable number of electrodes are fitted to the column. They are placed at different levels. The electronic unit (RLG/E) measures the water level within the column (RLG/C) detecting the number and position of the wet electrodes (RLG/P). APPLICATIONS BONETTI electrode type level indicators RLG series are the ultimate solution to water level monitoring under high pressure and high temperature conditions. They provide high reliability, while providing easy remote signal transmission. Their primary application is in steam boiler drum water level monitoring and signal transmission to the control room, in thermoelectric power plants. Fig. 1 2 BONETTI

3 KEY FEATURES The following features clearly highlight the high reliability of BONETTI RLG level indicators: No moving parts. No need for periodic maintenance. Easy installation, with pre-cabled electrical connections. No need for calibration at start up. Not influenced by load and ambient temperature variation. The electrodes hydrostatic seals are made of graphite. Redundant connection between electrodes and electronic unit. Electronic unit with double redundant power supply. Separate fully independent analog measuring circuit for each electrode. Two digital monitors, each one with its own self testing circuit and relevant malfunctioning alarm. Two process alarms can be independently set by switches. Totally impervious to electromagnetic radiations (EN class A) Fig. 1 Pressure water column RLG/C A set of conductive electrodes RLG/P are assembled to the column RLG/C, aligned into one or more rows, at suitable angles and intervals. Each electrode is connected to a separate steam/water detection and indication circuit. Electrodes and connecting wires are protected by a stainless steel covering (Refer to illustration 2). The water column has the necessary connections to the process, and both vent and drain pipes. The water column is made of F316 stainless steel. Other materials are available on request. The level gauge column is designed according to ASME B31.1 standard. Connections to process and drainage are flat face nipples. Other connections are available on request. We highly recommend the installation of suitable stop valves between process and instrument. Such valves can isolate the level indicator if required. BONETTI 3

4 Protective covering Fig. 3 - RLG/P conductivity sensor probe RLG/P sensor probe Fig. 2 - sample of RLG/C column having RLG/P conductivity sensor probes fitted on two rows at 180 Ceramic insulator Conductivity sensor probe RLG/P The conductivity sensor probe RLG/P is the heart of the RLG level indicator. It is made of stainless steel, with a ceramic insulating element. The hydrostatic sealing consist of special graphite gaskets. Each probe is individually tested, both with helium and hydrostatically at 420 bar, to verify sealing and function. Graphite hydrostatic sealing Sensor tip Fig. 4 - RLG/P conductivity probe section 4 BONETTI

5 RLG/E electronic metering, monitoring and transmission unit The electronic metering, monitoring and transmission unit RLG/E is housed in a box suitable for wall mounting, including outdoors (refer to illustration 5). It is connected to the electrodes with a redundant tinned copper, silicon insulated cable, suitable for the high temperature near to the sensors themselves. Pure nickel, mineral insulated cable can be delivered on request. Standard cable length is 10 meters, but other lengths are available on request. A pre cabled connector connects the wires to the box, in order to facilitate installation. Electrodes are pre-wired with metallic rings. Sensor connections are divided into two sets: odd and even. Each set has its own power source and it s able keep on working even after an unexpected failure in the twin section. Fig. 6 -RLG/E - Panel details Bicolour LEDs indicating water/steam Self diagnostic LEDs Level alarm LEDs Display Fig probes RLG/E Reliability and safety The RLG is designed to have two completely independent metering units, placed in the same box, in order to guarantee full redundancy and, therefore, it offers very high reliability. The electronic unit is divided into two sections: - signal / measure section - supervision section. A separate, full analog and independent circuit monitors each sensor. Therefore, continuity function is guaranteed even in case of the unlikely failure of any section. BONETTI 5

6 Each measured point has its own relay, with potential free switching contacts. Typically, they can be used for remote level transmitting. Their conditions are shown on the front panel on bicolour LEDs: green for water, red for steam (refer to illustrations 5 and 6) In parallel to the analog section, a double digital microprocessor section is present. The latter is fully redundant as well, and it is independent from the previous one. Each section receives the signal from all the sensors and manages them : - to measure the water level present in the column; - to show the level indication on the digital display; - to remotely transmit the level measure, by an analog 4 20 ma current signal; - to analyze signal congruity, warning of abnormal status (i.e. presence of water rather than steam) and, if becomes necessary, alerting via the self checking alarm; - alerting alarm if process conditions are different from preset ones. Both sections receive the signals from all sensors, in order to continue working separately, even in case of failure of a single section. A set of warnings and alarms can be set both in analog (connecting the potential free switch relay contacts) and in digital fashion (via relevant programming software). The above status is visible via the graphic display on the electronic unit. The signal can be remotely monitored. Reliability of components, simplicity of analog circuits, the presence of a parallel and independent digital measuring section, the complete redundancy of the feeders of each circuit section, plus the self monitoring and self checking diagnostic functions, make BONETTI RLG level gauges very reliable and the best choice to transmit the visual indication of boiler water level at thermoelectric power plants control rooms, in full compliance to ASME, PED and ATEX directives. Fig. 2 - RLG/E assembly on water column 6 BONETTI

7 Accessories The following accessories are available on request: A wide range of stop, vent and drain valves, expressly designed for use with level gauges A set of tools to assemble the conductivity sensors. This guarantees both the correct installation as well as the right gasket torque. Independent displays to provide remote indication to control room, via a 4 20 ma signal. Remote display box meets IP40. (IP65 available on request) Standard equipment includes tinned copper, silicon insulated cable, suitable for the high temperature near to the sensors themselves. Special pure nickel, mineral insulated cable can be delivered on request. Standard cable length is 10 meters. It can be supplied in longer lengths on request. BONETTI 7

8 BONETTI CESARE BONETTI S.p.A. Via Cesare Bonetti Garbagnate Milanese (Italy) Telefono: Telefax: Internet web site: Bonetti Armaturen GmbH & Co. KG D Limburg an der Lahn (Germany) In den Fritzenstücker, 4 BONETTI (Suzhou) Level Gauges & Valves Co., Ltd. Yuandong Gongyefang, Minsheng Road, Shengpu District, Suzhou Industrial Park, Jiangsu, China Vendite Italia: Telefono: Telefax: italia@bont.it Export sales: Telephone: Telefax: export@bont.it Sales Office Telephone: Telefax: armaturen@bonetti.de Sales Office Phone Fax: bonettisuzhou@yahoo.com This catalogue is exclusive property of Cesare Bonetti S.p.A. Any unauthorized reproduction, in total or in part, of this catalogue shall be prosecuted. Products and data sheets on this catalogue reflect current standard production. Cesare Bonetti S.p.A. reserves the right to carry out necessary amendments to products and materials. Amendments or modifications to drawings and materials can be done also to comply with particular Customer's request or technical specifications. Pubblicazione B Rev. 00 -Eng