00515 - Mechanical Plants

Learning outcomes

At the end of the module, the student knows the most widespread mechanical systems in the industrial field according to the following scheme: general information, references to the basic knowledge necessary to understand their operation, analysis of the characteristics, dimensioning and optimization.

Course contents

 

 

PRELIMINARY NOTIONS

Manufacturing and service plant concept

Influence of time on fixed costs: simple, compound interest and discounted value

Concept of depreciation of a tangible asset: economic depreciation at constant rate

WATER SUPPLY AND DISTRIBUTION PLANTS

Main uses of industrial and civil water

Sources of supply (wells, aqueducts, surface waters)

Classification of pumps (radial, axial, single stage, multistage, etc.) and comparison between them.

Operating fields of the various types of pumps

Bernoulli's theorem and its applications to hydronic circuits

Pump head concept

Pump power for various circuits: open, closed with pressure vessels and not

Characteristic curve of CCP pumps and CCC circuit

Pipes for water transport: iron, copper, PE. Dimensions, PN

Valves: general classification. Examples

Pressure losses along the pipes, distributed and concentrated, l, x, Re, n, e.

Continuous loss tables

Equivalent length

Operating point of the circuit

Equal and different pumps in series and in parallel

Plant schemes

Sizing criteria for hydraulic lines (v const., r const.)

Sizing of the raised tank (utility requests in 24h, integral curve, tank volume)

Geometry and piping of the elevated tank

Sizing of the autoclave

COMPRESSED AIR SYSTEMS

Use of compressed air to transport mechanical energy

Classification of compressors and types of existing compressors (very superficially)

Diagram of the compressed air production plant

The problem of air dehumidification: the shell and tube cooler and its insertion in the line

Air content X and relative humidity j, refrigeration dryers

Calculation of cooling capacity for air drying

The condensate separator: use and geometry

The steam trap: use, geometry and sizing. Connection diagram

VRP pressure regulating valve: construction and connection diagram, and its operation

Adsorption and deliquescence chemical air dryers (diagrams)

Compressed air psychrometric diagram for calculating condensation

Perfect gases (PVT) and volume flow calculation Normal

Effective speed of compressed air inside a pipe

Geometry of distribution networks

Calculation of head losses using the graphical method (nomogram divided into two sections)

 

 

TECHNOLOGICAL STEAM SYSTEMS

Use of steam as a heat source

Functional diagram of the technological steam plant

Thermodynamic cycle on the T-s diagram

Choosing the potential of the boiler: pot. Nominal and Peak

Diagram and operation VRP pressure regulating/reducing valve

Construction criteria for steam delivery lines

Velocity of steam in pipelines

Condensate drain

Sizing of the condensate drain lines: start-up and running conditions

Power of the heat exchanger to the user

Economic calculation of system performance

Bernoulli expression for the calculation of the pressure downstream of the condenser for the thrust of the condensates to the hot well.

FIRE SAFETY SYSTEMS

Ceni on the main fire regulations for obtaining the CPI

Combustion: dynamics and its main competitors (fuel, oxidizer, heat)

Extinguishing methods: smothering, cooling, fuel insulation

Fire classes, main extinguishing agents

Time/temperature curve, fire load q and relationship of q with T and t

Prevention and protection, R.E.I. xxx and its meaning, Passive and active protection

Fire detection system: reference legislation

Types of detectors

Fire tank volume

Scheme of the UNI 9490 suction head fire-fighting pumping unit

Operating principles of the pump group (accessories, start and stop pressure switches, etc.)

Hydrant networks: UNI 10779 reference standard

Risk levels 1, 2, 3

The hose reel and the UNI 671-1 -2 hydrant

Flow coefficients Kv of the hose reel and hydrant

Design of a ramified network of hydrants: calculation of head and effective flow rate of each hydrant

ISO 14520 automatic gas extinguishing system

Gas system diagram and operating logic

Main gaseous agents and their applications, extinguishing concentrations according to the fuel

Principles for calculating the quantity of gas to be used in the plant (ISO14520 tables)

Wet, dry and deluge sprinkler systems: general information

Reference standard UNI 9489: Discharge density, operating area and other operating parameters

Sizing principles based on the level of risk (RL slight risk, RN normal risk, A serious)

Geometries of sprinkler networks

Calculation of a comb sprinkler network: least favored user (calculation in cascade) and most favored (iterative calculation)

Calculation of closed mesh networks with the Hardy Cross method.

SOLAR SYSTEMS: PHOTOVOLTAIC WITH STORAGE AND THERMAL

Energy in the horizontal plane TOA

Energy on the southward inclined plane β TOA

Radiation components on the ground: direct diffuse global

Empirical method for the estimation of ground radiation on an inclined plane β directed to the south

Flat plate solar collectors: types, materials and main characteristics

Photovoltaic panels and their main characteristics

Battery packs and their performance

Design and rough sizing of a complete system

Solar panels terms

Efficiency of flat plate collectors

Complete calculation for the sizing of a flat-plate solar collector system

 

Readings/Bibliography

Materiale didattico

Dispense del docente

A. PARESCHI, "Impianti Industriali", Ed. Esculapio, Bologna, 2007

Testi di approfondimento

G. COLI, “Impianti per il benessere e la sicurezza negli ambienti di lavoro”, PEG, Milano, 1990

S. FABBRI, “Impianti Meccanici”, Vol. I, Ed. Patron, Bologna, 1985

M. GENTILINI, ”Impianti Meccanici”, Pitagora Editrice, Bologna, 1991

A. MONTE, “Elementi di Impianti industriali”, Ed. Libreria Cortina, Torino, 1997, Voll. 1-2

O. PIERFEDERICI, “Impianti Meccanici”, Pitagora Editrice, Bologna, 1990

Office hours

See the website of Mauro Gamberi