Without going into the construction details, the cyclone, whether side-by-side or stacked, or if specially designed by the licensor, typically has an overall height around of 10m and a diameter of about 1.5m. Powder monitoring usually takes place in the last metres of the cylindrical section of the cyclone that ends with a conical part. Relying on radiometry represents the only reli- able and safe solution for monitoring the level. Installation of the instrumentation is, in fact, external to the cyclone. A nuclear source emits energy towards a detector mounted on the opposite side of the cyclone. Mounting on parallel structures to the cyclone, but detached, is common prac- tice. The number of sources depends on the required mea- surement range. For about 3m of total measuring range, two sources with low-energy activity are sufficient. The measurement system is based on a physical law in which the energy emitted by the source undergoes an expo- nential decay law relating the attenuating factor to the density and thickness of the matter crossed. If the cyclone was empty, a high value of received energy would be read on the receptor. As the dust settles, the energy value recorded on the receptor, with the empty cyclone, decreases until it is almost zero. This occurs when the dust level has reached the maximum required elevation. The precision, accuracy, and resolution that radiometric technology can offer is very high. With these measurements, it is often required that the degree of reliability that the system must achieve to reduce the risk of accidents during its use complies with the safety standards defined by the IEC 61508 standard in the safety integrity level (SIL 2) level. At the very least, a low-level alarm is dedicated to a nuclear switch detector. VEGA nuclear detectors, all equipped with Plics electron - ics, could meet this requirement. SIL 2 is always ensured in single-channel architecture.
In addition, beyond compliance with SIL standards, PLICS electronics offers: • Storage of up to 250 events • Storage of up to 250 parameter changes • Storage of up to 100,000 measured values • Diagnostic functions according to NE 107 • Storage based on a clock that reliably records the time. Safety Management of cyclone safety is improved with extensive diagnostic functions. Event storage based on a clock that reliably records the time shows how VEGA meets the high - est safety and reliability requirements while also facilitating the work of the operators in the refinery. In addition to the standards (such as SIL), having user-friendly instruments can help plant security. Since VEGA electronics are incorporated into the nuclear receptor, it is not only possible to have the display on the receiver head, but also to connect the receiver directly to the distributed control system (DCS). This simplicity, which also minimises commissioning time, responds to the requirement for better system safety and radio protection. ALARA An industrial system of measurement based on radiometry is engineered following the ALARA principle (as low as rea- sonably achievable). The activity of the source is minimised as much as possible considering the required measuring role and the regulations of radio protection in the country in which the plant is located. However, in addition to the high standards and promoted practices established by interna- tional regulations in radio protection, it is also possible to consider optional solutions that could help maximise safety in radio protection. Wireless communication, through the Bluetooth stan- dard, available in the electronic solution Vega Plics, repre- sents a further possibility to manage the detector located almost 20m from the source. The option to choose the type of detector provides a balance in maximising simplicity with concrete technical requirements. For several years, the scin- tillation detector has been the reference model for industrial measurements, which can be provided in a mechanically The rigid receptor with polyvinyl toluene (PVT) scintillator is highly sensitive. However, the flexible detector made in styrene, working according to the principle of optical fibres, allows great advantages, although physically slightly less • Low weight, which facilitates transport and installation • The diameter is approximately half of a rigid receptor. The advantage of having a diameter of almost half of the rigid detector is to centre it in a narrow energy bundle, mak- ing it intercept the energy at its maximum power. This way, the opening can be minimised on the horizontal plane of the energy beam coming from the source. For example, in the case of a fourth-stage cyclone with sensitive. Other advantages include: • Being able to follow the tank profile rigid or flexible version. Detector sensitivity
350 (13.78)
1471 (57.91)
ø
Tag-No.: 030-LE/LT- 922
50 (1.97)
1650 (64.96)
350 (13.78)
40˚
3800 (149.61)
Tag-No.: 030-LE/LT- 924
40˚
800 (31.50)
Figure 1 Fourth-stage cyclone separator with two Fibertrac 31s
94
PTQ Q3 2024
www.digitalrefining.com
Powered by FlippingBook