Chemical Process

IndustriesPrepared by:Engr. Sandra Enn Bahinting

ChE 150

Chemical Industry comprises the companies that produce

industrial  chemicals which converts  raw materials  into more than 70,000 different products

Basic Raw Materials:

Overview

Organic Chemicals • Oil and gas - source of 90% of world organic

chemical productionInorganic Chemicals • Sulphur and Chlorine,minerals

Products of Chemical Industry

Petrochemicals- derived from oil (coal or biomass)Example: Methanol=produced from oil and natural gas(US and Europe) = coal in China. poly(ethene)=derived from oil and gas (US and Europe) =biomass in Brazil Polymers

Example:  polyalkenes, polyurethanes, acrylics, polycarbonates and silicones 

Basic Inorganics  - low cost chemicals used throughout manufacturing and agriculture

Example: chlorine, sodium hydroxide, sulfuric and nitric acids

Base/ Basic Chemicals

 wide variety of chemicals for crop protection, paints and inks, colorants (dyes and pigments)

Specialty chemicals

Consumer chemicals

 chemicals are sold directly to the public. Example: detergents, soaps and other toiletries.

About 85% of chemicals are produced from ~ 20 simple chemicals called base chemicals.

Base chemicals produced from ~ 10 raw materials.

Base chemicals converted to ~ 300 intermediates.

Base chemicals and intermediates classified as bulk chemicals.

About 30,000 consumer products are produced from intermediates.

Consumer products from raw

First step in petrochemical industry is conversion of raw materials into base chemicals.

Synthesis gas (H2 and CO) through steam reforming of NG ammonia or methanol.

Lower alkenes through steam cracking of ethane or naphtha: ethene, propene, butadiene.

Aromatics through steam cracking of ethane or naphtha or the catalytic reforming process: benzene, toluene, xylenes (‘BTX’).

The second step involves a variety of chemical processes often aimed at introducing various hetero-atoms (O, Cl, S etc.) into the molecule.

This leads to formation of intermediates such as: acetic acid, formaldehyde, acetaldehyde and monomers like acrylonitrile, terephthalic acid etc.

The third step yields consumer products.The chemical industry can be conveniently

divided into 7 sectors.

World chemical market (1989)

Where these chemicals go..12 % of the cost of a car

polyurethane seat cushions; neoprene hoses and belts;airbags and nylon seat restraints

10 % of the cost of a houseincluding the cost of important insulation pipeselectrical wiring

10 % of what the average household consumer buys and uses every dayfood productsclothingfootwearhealth and personal care productshousehold cleansershome entertainment equipment.

World chemical Industry Top five organic chemicals: ethylene, propylene,

ethylene dichloride, methyl-tert-butyl-ether (MTBE), and vinyl chloride.

Top inorganic chemicals: nitrogen, oxygen, chlorine, and sodium hydroxide.

Raw materials and energy are closely related.

main raw materials for the chemical industry are fossil fuels.

These are also the most important sources of energy.

Major energy source is oil (~40%), Coal (~ 26%), then NG (~ 21%).

RAW MATERIALS AND ENERGY

Energy and the chemical industry

A lot of energy is used in the chemical industry (~ same order as used for feedstock)

crude oil (8% ) = raw material in the chemical industry: the balance is used for fuel production.

1. Fuels for direct heaters and furnaces: often same as raw material, e.g. in steam reforming

of NG, the NG is used for both feedstock and fuel.

Fuel oil (a product of distillation) is often used to preheat feed to the crude oil fractionator.

2. Steam: most important utility system for process heating, a

reactant, & in distillation. It is used saturated, wet or superheated. Steam used is replaced by treated make-up water. Steam used at 3 pressures levels:

Operating Conditions Saturation

Pressure (bar) Temp (K) Temp (K)HP 40 683 523MP 10 493 453LP 3 463 407

3. Electricity: Can be generated in-plant or purchased

from utility. Reduction of energy costs by generation

of power on-site with steam turbines and process heating with exhaust gases.

Often economical to drive large compressors with steam.

Co-generation (electricity and local/district heating).

Chemical Engineer chemical engineers concern themselves with

the chemical processes that turn raw materials into valuable products. The necessary skills encompass all aspects of design, testing, scale-up, operation, control, and optimization, and require a detailed understanding of the various "unit operations", such as distillation, mixing, and biological processes, which make these conversions possible

Process Flowchart

Lower Alkenes from Oil

Ammonia and methanol production

Sulfuric Acid

Process variables Mass and Volume Flowrate - The rate at which a material is

transported through a process line 1.Mass Flowrate (mass/time) 2. Volumetric Flowrate (volume/time)

Concentration

Mass concentration = mass of a component / volume of the mixtureMolar concentration = moles / volumeMolarity = molar concentration of solute / volume of solution

Process and Process variables

PressureAtmospheric pressure at sea level, 760 mmHg = 1 atm.

Pgauge = 0 → Pabsolute = Patmospheric Pabsolute = Pgauge + Patmospheric

Temperature

Process Classification Batch Process - The feed is charged (fed) into a vessel at the

beginning of the process and the vessel contents are removed sometime later

Continuous process - The inputs and outputs flow continuously throughout the duration of the process

Semi-batch process - Any process that is neither batch nor continuous

steady state -If the values of all the variables in a process (i.e., all temperatures, pressures, volumes, flow rates) do not change with time

Transient or unsteady state - If any of the process variables change with time

Material Balance A balance on a conserved quantity system can be

expressed by :

Each year 50,000 people move into a city, 75,000 people move out, 22,000 are born, and 19,000 die. Write a balance on the population of the city.

The following rules may be used to simplify the material balance equation:

If the balanced quantity is total mass, set generation =0 and consumption =0. Except in nuclear reactions, mass can neither be created nor destroyed.

If the balanced substance is a nonreactive species (neither a reactant nor a product), set generation = 0 and consumption = 0

If a system is at steady state, set accumulation=0 , regardless of what is being balanced