Post on 04-Feb-2016
description
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