SUMMARY / RELATED TOPICS

Sanremo Music Festival 1991

The Sanremo Music Festival 1991 was the 41st annual Sanremo Music Festival, held at the Teatro Ariston in Sanremo, province of Imperia, between 27 February and 2 March 1991 and broadcast on Rai 1. The show was presented by actors Andrea Edwige Fenech. Adriano Aragozzini served as artistic director; the winner of the Big Artists section was Riccardo Cocciante with the song "Se stiamo insieme", while Enzo Jannacci won the critics award with the song "La fotografia". Paolo Vallesi won the "Newcomers" section with the song "Le persone inutili". According to the rules of this edition, each song of the big artist section was presented in a double performance by a non-Italian singer or group, adapted in their foreign language

Screen scroll centrifuge

Screen/Scroll centrifuge is a filtering or screen centrifuge, known as worm screen or conveyor discharge centrifuge. This centrifuge was first introduced in the midst of 19th century. After developing new technologies over the decades, it is now one of the used processes in many industries for the separation of crystalline, granular or fibrous materials from a solid-liquid mixture; this process is considered to dry the solid material. This process has been some of the most seen within coal preparation industry. Moreover, it can be found in other industries such as chemical, environmental and other mining fields. Screen scroll centrifuge is a filtering centrifuge which separates solids and liquid from a solid-liquid mixture; this type of centrifuge is used with a continuous process in which slurry containing both solid and liquid is continuously fed into and continuously discharged from the centrifuge. In a typical screen scroll centrifuge, the basic principle is that entering feed is separated into liquid and solids as two products.

The feed is transported from small to larger diameter end of frustoconical basket by the inclination of the screen basket and different speed of the scraper worm. The solid material retained on the screen is moved along the cone via an internal screw conveyor while the liquid output is obtained due to centrifugal force causes the feed slurry to pass through the screen openings. Furthermore, screen scroll centrifuge may rotate either in vertical position; the use of screen scroll centrifuge has been seen in numerous process engineering industries. One of the most noticeable applications is within coal preparation industry. In addition to that, this centrifuge is employed in the dewatering of potash, gilsonite, in salt processes and in dewatering various sands. Moreover, it is designed for use in the food processing industry, for instant, dairy production, cocoa butter equivalents and other confectionery fats. Screen scroll centrifuges, which are known as worm screen or the conveyor discharge, instigate the solids to move along the cone through an internal screw conveyor.

The conveyor in the centrifuge spins at a differential speed to the conical screen and centrifugal forces 1800g - 2600g facilitate reasonable throughputs. Some of the screen scroll centrifuges are available with up to four separate stages for improved performance; the first stage is used to de-liquor the feed, followed by a washing stage, with the final stage being used for drying. In an advanced screen scroll centrifuge with four stages, two separate washes are employed in order to segregate the wash liquors; the two most common types of screen/scroll centrifuge used in many industrial applications are vertical screen/scroll centrifuge and horizontal screen/scroll centrifuge. Vertical screen scroll is built with the main components of screen, basket and helical screw. Feed containing liquid and solid materials is introduced into vertical screen scroll centrifuge from the top; this is sped up by centrifugal acceleration produced from the rotating parts contacted. As such, centrifugal force slings liquids through the openings, while solids are held on the screen surface as they cannot pass through because of granular particles larger than the screen pores or due to agglomeration.

Movement of solids across the screen surface is manipulated by flights. Liquids that have gone through screen are obtained and discharged through effluent outlet from the side of machine, while solids collected from the screen fall by gravity through the bottom discharge of the machine; some of the available vertical screen scroll centrifuges are CMI model EBR and CMI model EBW which are manufactured by Centrifugal & Mechanical Industries. The former can dewater coarser particles size ranging from 1.5 in to 28 mesh whereas the latter can dewater finer particles size ranging from 1 mm to 150 mesh. Similar to a vertical screen scroll centrifuge, a horizontal screen scroll centrifuge is constructed of several main parts: screen, basket and helical screw; the screen and the basket with frustoconical geometry are assembled into the housing in a horizontal axis. Inside the frustoconical structure there is a tubular wall. Inside the tubular wall there is a cylinder of helical screw; the tubular wall will have a different angular speed to the helical screw.

The solid-liquid mixture is fed into the closed rearward portion of the scroll. The rotation movement of the scroll and basket allows the liquid to pass through from the openings on the screen; the solid remains will be separated according to size due to the difference of the angular velocity of the helical screw and the basket. The helical screw pushes the solid material to be discharged to the forward end of the scroll; the processing time depends on the angular velocity difference. It may be influenced by the design of the scroll feed opening; the solid particles exiting are collected via a conveyor in the collection unit. The performance and output efficiency of the screen scroll centrifuge can be affected by several factors, such as particle size and feed concentration, flow rate of feed and screen mesh size of the centrifuge. Particle size in the feed is one of the most important parameters to be taken into account since the choice of slot and screen holes size of screen scroll centrifuge or different types of process depends on feed contents.

Non-uniform particles size in the feed can cause partial blockage on the screen due to the small size solids blocking the holes besides normal and larger particles. So, liquids flow over the screen instead of passing through it; as such, it requires higher s