Design features
Vibrating prillers
The Vibro Priller principle of operation is based on the liquid jet property to break up at a strictly uniform (monodisperse) drops, creating a periodic pertrubation on the jet surface at the same distance from each other . Such regular pertrubations are imposed on the jet due to the periodic variation of the melt velocity upon dispersion in the melt or at the top of disperser (bucket) of the pressure pulses propagation from the emitter of vibrations. Thus, the vibration imposition on the jets allows to make a controlled and uniform process of the jet disintegration into drops. Which undoubtedly leads to the improvement of the finished product quality. Space saver vibration devices of different designs are used as a generator of vibrations.
Structural options of vibrating prillers
From 1998 Rotating Vibro Prillers (RVP) with pneumatic vibrators and outboard drive of bucket rotation were manufactured.
This model of Vibro Priller is the most demanded of our products line.
As on the September 2018 there were 43 prilling systems installed on the basis of vibroprillers RVP
Such vibroprillers perfectly proved itself in the towers of 10-12 m in diameter with built-in device «Fluidized bed». Improved design of such Vibro Prillers still the most demanded upon revamping relatively old prilling towers. Prillers of similar design were also been installed at some revamped aggregates AN-72 – 2 Vibro Prillers in the extreme mounting positions.
In 2007 the construction of centrifugal rotating Vibro Priller was developed (CRVP) for melts of complex fertilizers with big amount of insoluble impurities (dolomite, ground phosphorite etc.). In this prillers, the melt is displaced from the cavity of the bucket by means of centrifugal fource, which is caused by means of rotating blades inside the priller.
As of today, based on prillers of such type there were implemented 13 systems
From 2012 Static Vibro Prillers (SVP) are mainstreamed
As of September 2018 based on SVP Prillers were installed 11 Prilling Systems with total amount of 49 prillers of different modifications,
assembled with buckets of different shape (flat, spherical, toroid), depending on the specific requirements of the Customer. Such Prillers have no moving parts, consequently creating the best conditions for laminarization of liquid jet. These Prillers are in demand when revamping of rectangular and circular section towers, where the use of acoustic granulators of RA and AGS type was envisaged. Only such design of the priller allows to make the irrigation shower any shape in order to eliminate the sticking on the walls of the tower.
Considering the worldwide trend upon increasing the capacity of prilling towers, in 2013 our specialists had developed and in 2015 was revamped the construction of Quickly Rotating Vibro Priller (QRVP) for the towers of 16-28m in diameter, with capacity up to 160 t/hour. 
These Prillers are installed and successfully operate at the productions of urea in India. The main issue at indian productions is high temperature of final product. By the aid of new prillers of RPF «Grace-Engineering» manufacturing with unique design of the bucket we managed to reduce the prill’s temperature for 8-15˚С without loss of production (increasing the quality of prills size distribution).
DESIGN FEATURES OF VIBRATING PRILLING SYSTEMS BY GRACE
Melt Filtering
In cases, when it is planned to operate with melt containing a large amount of foreign mechanical impurities and particle size more than 0.4-0.6 mm, we recommend the tangentional melt filters of our own production within the scope of supply. Constructions for the capacity of 20-100 t/hour were developed and implemented. Such kind of filters are installed directly before the Vibro Priller and allows to increase the period between cleanings of the bucket up to 7-15 days (depending on the degree of melt contamination).
Magnetostrictive Vibrator
All Vibro Prillers are assembled with generator of mechanical fluctuations (vibrator). Earlier our constructions were assembled with pneumatic and electromechanical vibrators. Disadvantage of such devices are the complexity of output parameters control. From 2007 highly effective magnetostrictive vibrators were implemented
Magnetostriction this is the feature of ferromagnetic material, which causes shape modification (in this case the length of magnetic core) under the influence of magnetic field. Such phenomenon is called longitudinal magnetostriction. When applying the magnetic field, the magnetic domains, which are present in the core material, are rotating to align with the field, providing proportional and repeated in microseconds the change of core length, which allows to generate mechanical fluctuations of set frequency and amplitude in wide range with smooth adjustment. Output vibrator parameters: – vibration frequency: 200-1200-2500Hz, – fluctuations amplitude: 50-100-150 micrometers.
Automatic Control System of Prilling process
Main purpose of Automatic Control System (ACS) – is calculation and generation of electrical signal for magnetistrictive vibrator depending on the melt level in the prilling bucket either from momentary melt discharge which is fed to Vibro Priller. Recently ACS has been significantly improved in terms of simplified maintenance and flexibility. ACS is supplied as an integral part of each prilling system and can operate as independent control system, and also can become integrated with Customer’s CCP using different data transmission protocols, providing its mobility and ability to be controlled from both CCP and its own panel of operator. Application of ACS in conjunction with magnetistrictive vibrator provides high stability of prills size distribution without the use of replaceable buckets. ACS of new generation in its design considers the application of modern highly reliable components produced by well-known world companies (SIEMENS, YOKOGAWA, CAMOZZY).