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Developed countries stay ahead by innovative technology

 and, once that technology has become mature, anyone is

entitled to use it.

A problem in developing countries is that small operations

 frequently undercut costs by ignoring health and safety

precautions. Indeed there have been riots in India because

dye manufacturers ignored such precautions. In China,

diethylene glycol was disposed of by combining it with

glycerol, and the mixture sold to companies in Bangladesh

and elsewhere who compounded it into fever medicines.

Many children died from the poisonous diethylene glycol. 63

Struttura Ind. chimica (p2)

The chemical industry is capital intensive. It produces huge

 quantities of homogeneous materials, frequently liquids or

gases, which can be manufactured, processed, and shipped

most economically on a large scale.

The petroleum refining industry was the first to convert to

 continuous operation on a large scale. Plant sizes escalated as

dramatic economies of scale became possible. The capacity of

a typical ethylene cracker rose from 70 million lb/year in 1951

to 1 billion lb in 1972. This was regarded as an upper size limit

until the early 1990s when plants with 1.5 billion lb/year

capacity were built. Meanwhile, in 2001, BASF/Fina brought

on stream a 2 billion lb/year ethylene plant in Port Arthur,

TX, and 2.8 billion lb/year is seen as an attainable size.

 64

Struttura Ind. chimica (p2)

Currently there are few batch processes of any size in operation for

 commodity chemicals, and substantial economies of scale are a

characteristic of the petrochemical industry. They arise not only from

improved technology but also from purely geometric factors. The

capacity of a great deal of chemical equipment (e.g., storage tanks and

distillation columns) varies with its volume, that is the cube of its linear

dimensions. The cost, on the other hand, is the cost of a surface to

enclose the volume and varies with the square of the linear

dimensions. Consequently, cost is proportional

2/3

to (capacity) . It does not apply to all equipment. The capacity of a

 heat exchanger depends on its surface area, so cost is proportional to

1

(capacity) and there are no economies of scale. Control systems are

0

not affected by capacity at all, so cost is proportional to (capacity) and

economies are infinite. It is claimed that, for a modern petrochemical

0.6

plant overall, cost is proportional to (capacity) . 65

Struttura Ind. chimica (p2)

Labor costs are a small proportion of petrochemical plant cash costs

 (benzene 3.5%, purified terephthalic acid 5.7%, acrylonitrile 7.3%)

but they contribute to economies of scale, because they do not

increase proportionately to increase in size of the plant. Doubling

the size of a unit does not double labor cost. Indeed, because of

automation, the labor cost may increase only 10–20%.

The size and complexity of a modern chemical plant demand high

 capital investment. Although other industries invest more capital per

dollar of sales, the chemical industry has the highest investment of

current capital. That means that the chemical industry invests more

each year than do other capital intensive industries such as mining,

where equipment once bought remains in service for many years. 66

Struttura Ind. chimica (p2)

Capital intensity has a number of corollaries. The return on capital is

 relatively low. Because high capital investment reduces the labor

force required, manpower productivity (i.e., value added per

employee) is high, while salaries contribute relatively little to costs

(of the order of 2.0% for steam crackers).

The assets of a company are the estimated value of the plants, land,

 and other capital goods it owns. Generally, the petroleum refining

industry has both the highest assets and the highest sales per

employee. 67

Struttura Ind. chimica (p2)

A chemical industry is critical to the economy of a developed

 country. An advanced economy cannot exist without a chemical

industry; neither can a sophisticated chemical industry exist without

an advanced economy to support it and to provide the educated

manpower it requires.

The chemical industry is an “upstream” industry. It purchases raw

 materials such as petroleum, natural gas, coal, and metallic, and

nonmetallic minerals. It bought about $40 billion worth in 2000 and

made from them products that were sold for $460 billion.

These products, however, are usually not sold to the final consumer.

 About one fifth of them are sold to other firms in the chemical

industry for further processing. The remainder are sold to other

industries to help them make their own products or sell their

services. 68

Struttura Ind. chimica (p2)

Makers of plastic packaging, for example, rely on polymers and one-

 hour photo stores rely on photographic chemicals. Automobile

manufacturers use the products of the chemical industry in tires,

hoses, safety glass, seat belts, upholstery, bumpers, fenders, and

even doors and side panels, as well as many other components. 69

Struttura Ind. chimica (p2)

Another characteristic of the chemical industry is freedom of market

 entry. Anyone who wants to manufacture bulk chemicals may do so

by buying “turnkey” plants.

Chemical engineering contracting companies have processes for

 preparation of virtually any common chemical and will build a plant

guaranteed to operate for anyone who wishes to invest the money.

This was the way that many of the petroleum companies gained

entry to the petrochemical business and is also the route followed by

developing countries.

The one requirement is large amounts of capital. To enter the basic

 chemical business requires a bare minimum of $1 billion. Large sums

of money may be required for purposes other than capital

investment. 70

Struttura Ind. chimica (p2)

There are also various barriers to entry such as lack of necessary

 technology or reluctance on the part of a patent holder to license

technology.

Downstream operations may provide a barrier to entry.

 Low price of the product, and correspondingly low profitability, may

 deter entry. 71

Struttura Ind. chimica (p2)

The chemical industry is one of the most highly regulated of all

 industries. The regulations are intended to protect and improve the

worker’s and the nation’s health, safety, and environment. Chemicals

may be toxic or hazardous, that is, they may be liable to poison

people fairly quickly or to catch fire or to explode. Some chemicals

may appear to damage the environment in ways that are subtle and

not well understood.

These are the problems that arouse the greatest debate. Long-term

 ill effects may not be evident or demonstrable in the short term, and

in the long term it will be too late to do anything.

The regulatory environment of the chemical industry is subdivided in

 a number of ways and monitored by various government

departments and agencies, 72

Struttura Ind. chimica (p2)

In October 2003, the European Commission adopted a draft

 regulation under the acronym REACH (Registration, Evaluation and

Authorization of Chemicals), to expand regulation from the current

3000 chemicals tested to the 70,000, produced or imported at a total

level of more than 1 tonne/year. The degree of testing required

varies depending on whether the total production plus imports in

Europe is greater than 1, 10, 100, or 1000 tonnes/year, and there are

substances of high concern—carcinogens, mutagens, and reprotoxins

(CMRs); persistent, bioaccumulative toxins (PBTs); very persistent

bioaccumulative toxic chemicals (vPvBs); and endocrine disruptors.

The burden of proof of safety is shifted from the regulators to the

industry.

Authorization will involve about 12 million animal tests, and has set

 the “green” supporters of chemicals testing at the throats of the

equally “green” animal rights activists. 73

Struttura Ind. chimica (p2)

The chemical industry is research intensive. It hires many graduates,

 peaking at one time at 13.3% of all scientists and engineers in the

United States. In the late 1990s, the figure was reduced to 9%, 5% in

the pharmaceutical industry, and 4% in the remaining sectors. That

still amounted to 91,000 scientists and engineers, and most of them

work in research and development laboratories.

Actually, 3–4% of sales is considered normal for companies that do

 not have a pharmaceutical arm and are only marginally involved in

specialty chemicals. Research-based pharmaceutical companies with

few other interests spend 10–25% of sales on research. True

specialty chemical companies have budgets about one third of those

of the pharmaceutical companies. 74

Struttura Ind. chimica (p2)

An important concept in today’s chemical industry is the ever-

 present possibility for dislocations. This is particularly important for

planners who, all too often, find their scenarios askew because of a

dislocation. Dislocations are defined as events over which a given

company has no control but which markedly affect that company’s

business. 75

Struttura Ind. chimica (p2) 76

Struttura Ind. chimica (p2) 77

Struttura Ind. chimica (p2)

Sulfuric acid heads the list by a large margin as befits its position as

 an economic indicator, although its maturity means that its growth

has been slow. Though it has many applications, about 45% is used

for phosphate and ammonium sulfate fertilizers.

Of the first 15 chemicals, only five—ethylene, methyl tert-butyl ether,

 propylene, benzene, and ethylene dichloride—are organic. Four are

associated with the fertilizer industry—sulfuric acid, nitrogen,

ammonia, and phosphoric acid. Oxygen is used by the steel industry

and for welding. Sodium carbonate is important in the glass industry.

sulphuric acid ethylene propylene

methyl tert-butyl ether benzene

H SO CH =CH

2 4 2 2 O

Na-carbonate ethylene chloride MTBE

Na CO CH =CHCl

2 3 2 78

Struttura Ind. chimica (p2)

Most of these chemicals are also used to make organic chemicals, but

 their main markets lie elsewhere. Chlorine (Cl ) has a number of uses

2

including the bleaching of paper, as a disinfectant, and as a

component of organic compounds, most important of which is vinyl

chloride whose precursor is ethylene dichloride. Many chlorine

compounds, however, are now considered ecologically undesirable.

The three most important organic chemical building blocks, ethylene,

 propylene, and benzene, occupy positions 4, 7, and 13. The majority

of remaining chemicals in the top 50 are organic, and these form the

backbone of the so-called heavy organic chemical industry. Heavy

organics are defined as large volume commodity chemicals such as

ethylene and propylene as opposed to specialty chemicals such as

dyes and pharmaceuticals. 79

Struttura Ind. chimica (p2)

Some of the chemicals have only one very large use. For example, the

 major use for ethylene dichloride (No. 12) is to make vinyl chloride

(No. 15). The major use for ethylbenzene (No. 20) is to make styrene

(No. 22). p-Xylene (No. 27) is converted primarily into terephthalic

acid (No. 25). Cumene (No. 30) is converted to phenol (No. 33) and

acetone (No. 41). Cyclohexane (No. 42) is used primarily to make

adipic acid (No. 46) and caprolactam (No. 49). terephthalic acid

p-xylene

ethylene dichloride styrene

ethylbenzene

Cl O OH

Cl

vinyl chloride

Cl HO O

caprolactam

acetone cyclohexane adipic acid

cumene phenol O

OH O OH HN

O O OH 80

Struttura Ind. chimica (p2)

Many of the top 50 chemicals are monomers for polymers, including

 ethylene, propylene, vinyl chloride, styrene, terephthalic acid,

formaldehyde, ethylene oxide, ethylene glycol, phenol, butadiene,

propylene oxide, acrylonitrile, vinyl acetate, adipic acid, and

caprolactam.

formaldehyde ethylen glycol

ethylene oxide

O

CH O HO

2 OH

butadiene propylene oxide vinyl acetate

O

O O 81

Struttura Ind. chimica (p2)

Raw materials Base chemicals Intermediate

Inorganic

Inorganic Intermediates

(NH , H , H SO , HCl, H PO , Cl ,

(H O, air, minerals, 3 2 2 4 3 4 2

metals, Si, glass, ceramics,

2 (formaldehyde, acetic ac.,

NaCl, SiO , ….) zeolites, inorg. fibres, …)

2 ethylene oxide, vinyl

chlorure, vinyl acetate,

Fossil fuels Base chemicals acrylonitrile, meta-

acrylic acid, phthalic &

(coal, oil, (syngas- CO/H , alkanes, maleic anh., phenol, …)

2

natural gas) olefins, aromatics, HCN)

Energy Base chemicals Final products

(from other sources) (CH OH, ethanol, methylamine,

3

halogen compounds, Polymers & elastomers, fibres,

acetaldehyde, ethanolamines, detergents, agro-chemicals,

acetone, ..)

Biomass pharmaceuticals, ...

Inorganic Industrial Chemistry

Refinery Petrochemistry Polymer sector

Fine and specialty

chemicals

Struttura Ind. chimica (p2) 83

Struttura Ind. chimica (p2) 84

Struttura Ind. chimica (p2)

a gas at STP

 composed mainly of methane (CH ), plus (in

 4

decreasing order) C2, C3, C4 and C5 alkanes (no

olefins, because they are too reactive)

may or not be associated to oil

 derives from the anaerobic processes of

 decomposition of biomasses

contains variable amounts of H S, N2, CO (+ water

 2 2

deriving often from extraction processes) 85

Struttura Ind. chimica (p2) 86

Struttura Ind. chimica (p2) 87

Struttura Ind. chimica (p2) 88

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Struttura Ind. chimica (p2) 90

Struttura Ind. chimica (p2)

The main process employed is amine absorption

 The sour gas enters at the bottom of an amine

 contactor and contacts the lean amine solution which

enters the contactor at the top

The amine solution removes the acid gas components

 and sweet gas flows from the top of the contactor

The rich amine (amine containing acid gas) flows from

 the bottom of the contactor where is is regenerated

The acid gas will either be injected, flared or sent to a

 sulfur recovery facility to recover the sulfur 91

Struttura Ind. chimica (p2)

The gas to be treated is fed to the

 

bottom of the absorber and flows 2R NH + CO + H O

2 2 2

countercurrent to the absorbing (R NH ) CO

2 2 2 3

liquid supplied at the top of the 

(R NH ) CO + CO + H O

2 2 2 3 2 2

absorber. Acid gases are then 2R NH HCO

2 2 3

absorbed by the absorbing liquid. 

2R NH + H S (R NH ) S

The liquid that has absorbed the acid 2 2 2 2 2

gases is preheated and then supplied 

(R NH ) S + H S 2R NH HS

2 2 2 2 2 2

to the top of the regenerator where

the acid gases are stripped by steam need of weak bases which

for the regeneration of the liquid. accelerates the absorption, but do

not form too strong bonds which

The regenerated liquid is precooled make difficult the stripping

and recirculated to the absorber. 92

Struttura Ind. chimica (p2) 93

Struttura Ind. chimica (p2)

All natural gas will be saturated with water and will

 require to be dehydrated

Three different processes could be employed

 ◦ Glycol Dehydration (similar to the amine absorption process. The

glycol absorbs the water from the gas, so dry gas flows from the

top of the tower. The rich glycol flows from the bottom and is

then regenerated).

◦ Desiccant Beds

◦ Ethylene Glycol injection combined with Refrigeration (Glycol is

injected into the inlet gas stream. The glycol mixes with the water

that is condensed as the gas is cooled. The glycol prevents

freezing the glycol-water mixture). 94

Struttura Ind. chimica (p2) Air Products

Water is a common impurity in natural gas that must be removed to meet pipeline

specifications and prevent hydrate formation.

separation based on the

kinetics of diffusion

95

Struttura Ind. chimica (p2)

The hydrocarbon mix needs to be separated into each

 component. This process is called fractionation.

The fundamental principle for fractionation is that each

 component has a different boiling point.

The usual order is to remove the lighter product first. i.e. start

 with ethane, then propane, then butane (iso then normal)

and finally condensate.

Fractionator towers are usually named for the overhead

 product. A deethanizer implies that the top product is ethane.

A depropanizer indicates the top product is propane.

With C2+

 ◦ Deethanizer - the first step in the fractionating sequence is to separate

the ethane from the rest of the propane and heavier hydrocarbons.

◦ Depropanizer - The next step is to separate the propane from the rest

of the butane and heavier hydrocarbons

◦ Debutanizer - the final step is to separate the butane from the

condensate 96

Struttura Ind. chimica (p2)

GTL (Gas to Liquid)

 notevoli studi e progetti

di sviluppo in questo settore gasolio medio

Fischer-Tropschs

Struttura Ind. chimica (p2) 97

DME, fuels & olefins,

Methanol chemicals

synthesis LPG,

Air Syngas Fischer Product

Synthetic

CO

Air Naphtha

crude

H

separation production Tropsch Upgrading

2 Diesel

Gas

CH

4 processing CO Coal

2 Purification Gasification

removal 98

Struttura Ind. chimica (p2) NG

Stranded 99

Struttura Ind. chimica (p2) 100

Struttura Ind. chimica (p2) 101

Struttura Ind. chimica (p2) 102

Struttura Ind. chimica (p2) 103

Struttura Ind. chimica (p2) 104

Struttura Ind. chimica (p2) 105

Struttura Ind. chimica (p2) 106

Struttura Ind. chimica (p2) 107

Struttura Ind. chimica (p2) 108

Struttura Ind. chimica (p2) 109

Struttura Ind. chimica (p2) 110

Struttura Ind. chimica (p2)

light crude oil (°API 44) heavier crude oil (°API = 31)

 111

Struttura Ind. chimica (p2) 112

Struttura Ind. chimica (p2) 113

Struttura Ind. chimica (p2) 114

Struttura Ind. chimica (p2) 115

Struttura Ind. chimica (p2)

Manages hydrocarbon molecules

 Organized & coordinated arrangement of

 manufacturing processes

◦ Provide physical & chemical change of crude oil

◦ Salable products with specifications & volumes as demanded

by the marketplace

Complete refinery will include:

 ◦ Tankage for storage

◦ Dependable source for electric power

◦ Waste disposal & treatment facilities

◦ Product blending facilities

◦ Around the clock operations

◦ Conversion units 116

Struttura Ind. chimica (p2) 117

Struttura Ind. chimica (p2) 118

Struttura Ind. chimica (p2) 119

Struttura Ind. chimica (p2) 120

Struttura Ind. chimica (p2) 121

Struttura Ind. chimica (p2)

Each refinery has its own unique processing scheme

 ◦ Product demand & specifications

◦ Individual economic considerations

Simple

 ◦ Crude distillation, reforming, sulfur treating

◦ Range of products is limited

Complex

 ◦ Simple + vacuum distillation, FCC, HC, alkylation, gas recovery

Integrated

 ◦ Complex + recovery of material from VTB — coking

◦ Full range of products 122

Struttura Ind. chimica (p2) 123

Struttura Ind. chimica (p2) 124

Struttura Ind. chimica (p2) 125

Struttura Ind. chimica (p2) 126

Struttura Ind. chimica (p2) 127

Struttura Ind. chimica (p2) 128

Struttura Ind. chimica (p2) vacuum distillation 129

Struttura Ind. chimica (p2) 130

Struttura Ind. chimica (p2)

Cracking

 ◦ convert heavier fractions (vacuum gasoil) to lighter fractions

for gasoline

Catalytic reforming

 ◦ isomerization/aromatization to increase octane nr.

Hydrotreatment

 ◦ to eliminate sulphurs (and other heteroatoms and metals) 131

Struttura Ind. chimica (p2) 132

Struttura Ind. chimica (p2) 133

Struttura Ind. chimica (p2) 134

Struttura Ind. chimica (p2) 135

Struttura Ind. chimica (p2) radical mechanism, high T

carbocation mechanism 136

Struttura Ind. chimica (p2) 137

Struttura Ind. chimica (p2)


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DETTAGLI
Corso di laurea: Corso di laurea in chimica industriale
SSD:
Università: Messina - Unime
A.A.: 2013-2014

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher Giuseppe^^ di informazioni apprese con la frequenza delle lezioni di Chimica industriale e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università Messina - Unime o del prof Perathoner Siglinda.

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