Chimica industriale - struttura dell'industria chimica

Struttura dell'Industria Chimica

S. Perathoner

una introduzione alla chimica e

produzione industriale

CDL Chimica Industriale

4 CFU 1

Introduction to the

Chemical Production

UniME S. Perathoner 2

Topics

Tools for Industrial Chemistry

1. the concept of flowsheet

• quantification of mass/heat transfer

• kinetics and thermodynamic of chem. processes (elements)

• catalysis (intro)

• unit operations (reaction, separation, utilities) (intro)

• process economics (elements)

• safety

• Structure of the Chemical Production

2. What is the chemical sector (& nomenclature)

◦

◦ Facts and Figures, characteristics of the Chemical Industry

◦ Energy products

◦ Petrochemical Industry

UniME ◦ use of coal 3

Additional material and books

Concepts of Chemical Engineering 4 Chemists, S.J.R. Simons, Royal

◦ Society of Chemistry 2007 (Ch. 1 - Mass/heat balance, Ch. 2

Introduct Chem Eng., Ch 9 Economics, Ch 10 Risk)

Applied Process Design for Chemical and Petrochemical Plants,

◦ E.E. Ludwig, Vol. 1, Third Edition, Butterworth-Heinemann, 1999

(Ch. 1 Process planning, Ch 7 Process Safety)

Perry's Chem. Eng. Handbook (8th Ed.), McGraw-Hill 2008 (Ch. 4

◦ Thermodynamics, Ch. 7 Reaction kinetics, Ch. 9 Process

economics, Ch. 19 reactors, Ch. 23 Process safety

Chemical Process Technology, J.A. Moulijn et al.,

◦ Wiley 2001

UniME 4

The concept of flowsheet

A tool for understanding and

design chem. processes

UniME 5

The concept of flowsheet

UniME 6

Unit operations in chem. processes

pretreatment of the feed (purification, heating, etc.)

▸ chemical transformation (reactor)

▸ continuous or batch-type

◦ mono- or multi-phase

◦ fixed bed, stirred tank, multiphase

◦

separation

▸ mechanical (not usual)

◦ different composition between gas/liq. phase (distillation)

◦ different solubilities (extraction, absorption-stripping,

◦ crystallization, ...)

preferential adsorption (active carbones)

◦

UniME and many more

◦ 7

Flowsheet

The flowsheet is the “road-map’’ of a process, and serves to

▸ identify and focus the scope of the process for all interested and

associated functions of the project. As a project progresses, the

various engineering disciplines read their portions of responsibility

from the flowsheet, although they may not understand the process

or other details relative to some of the other phases of engineering.

The flowsheet also describes the process to management as well as

▸ those concerned with preparing economic studies for process

evaluation.

A good process flowsheet pictorially and graphically identifies the

▸ chemical process steps in proper sequence. It is done in such a

manner and with sufficient detail to present to others a proper

mechanical interpretation of the chemical requirements.

UniME 8

distillation columns

multistep

multi-feed

introductions

UniME 9

gas-.liq separ.

ethylbenzene reactor

vent transalkylation vent

water

benzene furnace

heat out toluen

e

heat exchanger

furnace

ethylene

furnace reactor

compressor alkylation

- input-output, mass flow

sequence of operations

- main equipments (with possible omissions)

UniME - 10

Type of flowsheets

Block Diagram

▸ Usually used to set forth a preliminary or basic processing concept

◦ without details. The blocks do not describe how a given step will be

achieved, but rather what is to be done. These are often used in survey

studies to management, research summaries, process proposals for

“packaged” steps, and to “talk-out’’ a processing idea. For management

presentations the diagrams are pictorial and help illustrate the basic

flow cycle.

UniME 11

Ammonia

Ammonia is an important primary inorganic material. 85% of

▸ the worldwide production is utilized in the manufacture of

synthetic fertilizers.

N2 + 3 H2 2 NH3, H = -91.6 kJ/mol

 

▸ favored by: (i) high pressure, (ii) low temperature,

◦ (iii) active catalyst, (iv) pure gas (low inert gas )

α-Iron

catalyst: (from magnetite), promoted by

◦ (a) K2C03 (increases activity),

(b) Al203, SiO2, (protect against sintering),

(c) CaO (reduces susceptibility to sulfur and

chlorine compounds)

UniME 12

Ammonia and Nitric Acid

ammonia synthesis ammonia (NH3) oxidation

to nitric acid (HNO3)

UniME 13

Nitric acid (HNO3) production by ammonia

(NH3) oxidation

UniME 14 14

Process schemes

It is shown the sequence of unit operations and the

▸ flows between them.

Four types

▸ simplified

◦ only main operations



quantified

◦ also T,P and composition (in, out of main equipments)



with instruments

◦ also the main instruments to control operations



operational

◦ complete



UniME 15

Main symbols (in flowsheets)

1 vertical empty reactor

2 filling (catalyst., resins,

structured filling)

1 2 3 4 3 fixed bed reactor (or column)

4 multitubular reactor

5 continuous mixed reactor

6 gas-lig (or liq/liq) separat.

7 plate distillation column

8 tanks

9 furnace