ChE Calculations

SO3-free basis

An Orsat analysis of the flue gas when pyrite is roasted is on a/an

proximate analysis

Coal analysis which is based upon the volatilization characteristics of the fuel is the

input = output

For balances on atomic species, which of the following material balance is applied

Ash

In the combustion of solid fuels, the tie component between the feed and the refuse is the

modified proximate analysis

The analysis of coal given in %C, %N, %S %moisture , % net H, %combined water, and %ash is called

Chemical Engineering

The application of the physical sciences together with the principles of economics and human relations to fields that pertain directly to processes and process equipment in which matter is treated to effect a change in state, energy content or composition

Dulong formula

The empirical relation which allows one to compute for the net hydrogen in a given solid fuel is

Gross calorific value (Higher Heating Value)

The heating value measured when water formed from combustion is in the liquid state is the

tie substance

The material which remains unchanged in a process is called

2

The maximum number of independent equations that can be derived by writing the material balances for an input and output stream with two component substances is/are

relative humidity

The ratio of the partial pressure of a vapor to the vapor pressure in equilibrium with the liquid is called

Inherent moisture

Type of moisture in coal which assumed to be the water held within the pore system and capillaries of coal

By-pass

Type of process stream that can be used to control the composition of a final exit stream by skipping one or more stages of the process and goes directly to another downstream stage

Semi-batch

Type of process where a material enters the process during its operation, accumulates in the process vessel and withdrawn only after the process is over; neither batch nor continuous

It is computed based on how much fuel was burned in the reactor

Which is not true about the theoretical oxygen

It is the reactant that would disappear first if the reaction goes to completion

Which of the following best describes a limiting reactant

Low percentage excess air, high air inlet temperature

Which of the following combustion conditions will give the highest theoretical flame temperature

all of these

Which of the following terms could express the extent to which the limiting reactant

CGS system

a system similar to SI but uses cm, g and s for length, mass and time respectively

American Engineering System or English system

a system that uses ft, lbs and s for length, mass and time respectively

head

a term used to report pressure being the height of the column of a liquid of known density

Excess Air

amount by which the air fed to the reactor exceeds the theoretical air

Sulfates

are commonly employed in surfactant and detergents and as an additive to Portland cement

Nitrogen (N) and Sulfur (S)

both reflected in the VCM

Système Internationale d' Unitès

commonly used in the engineering and scientific community; also referred to as MKS system

Composition in wet basis

component mole fraction of product gas that involves water

Composition in dry basis (Orsat analysis)

component mole fraction of product gas which does not involves water

Water gas

consists of CO and H2 with small amount of N2 generated similar to a producer gas but blown with steam thereby decreasing the N2 content and doubling the heating value

Producer gas

consists of CO, H2, about 55% N2 and trace amounts of CO2 obtained by passing small amount of air through a hot bed of coal, peat, wood and other biomass

liquefied petroleum gas

consists of ethane, propane and butane

Cinder

contains unburned sulfur and non-combustible inert materials from the fuel

Single pass conversion (once-through conversion)

conversion of reactant based on the amount of material that enters (fresh feed + recycle stream) and leaves the reactor (gross product)

Overall conversion

conversion of reactant in a process based on the amount of material that enters(fresh feed) and leaves the reactor(overall product)

Octane number

determined from a calibration curve relating knock intensity to the % volume of i-octane(2,2,4-trimethylpentane) in a mixture of i-octane and n-heptane

Natural gas

found compressed in porous rocks and shale formations and composed of mixture of hydrocarbons and some traces of sulfur and organic nitrogen

Fractional conversion (% conversion)

fraction of feed or some component in the feed that is converted to products

Degree of completion

fraction of limiting reactant converted into products

Heating Value

heat released when the fuel initially at 25C reacts completely with oxygen and the products are returned to 25C

Lower Heating Value (Net Heating Value)

heating value when water comes out as vapor in the combustion reaction

Anthracite

highest rank of coal which contains the highest percentage of FC and percentage of VCM

Combined water (CW)

hydrogen in VCM combined with oxygen in the proportions H2O is called

Net hydrogen (NH)

hydrogen in VCM for which oxygen from the air must be supplied for its combustion termed as

Hydrogen (H)

in the solid fuel is present as ________ in adsorbed moisture

Carbon (C)

in the solid fuel is present in VCM and as FC

Crystallization

involves formation of solid particles within a homogeneous phase (i.e. liquid solutions) by either cooling or removing some of the solvent

Stoichiometry

involves quantitative relationships between reactants and products in a balanced chemical reaction

Drying

involves removal of relatively small amount of water or other liquids from the solid material

Fixed carbon (FC)

is obtained by difference

SO3

is soluble in water and therecore not included in the dry analysis or orsat analysis of the burner gas

Volatile combustible matter (VCM)

is the loss in weight of the dried sample when heated for 7 min at 950C in a covered crucible

Moisture (M)

is the loss in weight of the sample when heated for 1 hour at 104C to 110C

Sub-bituminous

lesser grade of coal with more M and less FC

brown coal/lignite

lowest grade of coal formed from layers of sediment that accumulates over peat and has M and less FC than other grades of coal

Purge

material or energy stream bled off from a process to prevent accumulation of inert materials that may buildup in the recycle streams

Recycle

material or energy stream that leaves a downstream process unit and returned to the same process unit or upstream unit

Cetane number

measure of the fuel's ignition delay, that is, the period between injection and ignition

sealed-end manometer

measures absolute pressure

open-end manometer

measures relative or gauge pressure

Smoke point

measures the tendency of the fuel to form soot

Flash point

minimum temperature at which fuel will rapidly catch fire when exposed to an open flame located above the liquid

Auto ignition temperature

minimum temperature required for the fuel to initiate self-sustained combustion in a standard container in atmospheric air in the absence of a spark or a flame

Theoretical oxygen

mole or molar flow rate of oxygen necessary for the complete combustion or complete conversion of all the fuel fed to the reactor

Bituminous

most abundant and widely used rank of coal which is usually black or dark brown in color

Coal char

non-agglomerated and non-fusible residue from thermal treatment of coal

Coal

originated from the decay of biomass which is converted to peat by bacterial and chemical action and under the influence of time, pressure and temperature, metamorphoses to various ranks

Oxygen (O)

present both in M and CW of the VCM

Continuous

process where input and output flow continuously throughout the duration of the process

Batch

process where the feed is charged into the system at the beginning of the process and the products are all at once removed sometime later

steady-state

process wherein process variables does not vary with time

Transient or Unsteady-state

process wherein process variables varies with time

Stack gas or flue gas

product gas that leaves a combustion furnace

Theoretical air

quantity of air that contains the theoretical oxygen

based on reactant consumed

ratio of the amount of desired product to the amount of limiting reactant consumed

based on reactant fed

ratio of the amount of desired product to the amount of limiting reactant fed

based on theoretical amount of limiting reactant consumed

ratio of the amount of desired product to the amount product obtained if all limiting reactant had reacted and no side reactions occured

Fractional excess (% excess)

ratio of the amount present in excess to the amount stoichiometrically required

Extent of Reaction

ratio of the change in the number of moles of species, i and its stoichiometric coefficient of the species in reaction, j

Selectivity

ratio of the moles of desired product to the moles of the undesired product or by-product

Excess reactant

reactant present in more than its stoichiometric proportion relative to every other reactant

Partial or incomplete combustion

reaction in which CO is also formed

Complete combustion

reaction in which CO2 is also formed

Series reactions or consecutive reactions

reactions where the reactant forms an intermediate product which reacts further to form another product

Parallel reactions or competing reactions

reactions where the reactant is consumed by two different reaction pathways to form different products

Charcoal

residue from the destructive distillation of wood usually containing 10-15% M

Distillation

separation of mixtures based on the differences in volatilities by utilizing vapor and liquid phases at essentially the same temperature and pressure for the coexisting zones

Combustion

sequence of chemical reactions between a fuel and an oxidant accompanied by the production of heat(exothermic) and conversion of chemical species( C ->CO2 or CO, H2 ->H2O and S or N may be partially or completely converted to their oxides)

Coke

solid remains from the carbonization of coal, petroleum residues and other carbonaceous materials.

Limiting reactant

species present in the reaction that would be completely consumed theoretically if the reaction were to proceed to completion

Pour point

the lowest temperature at which a fuel will flow when cooled and a rough indication of the lowest temperature at which a liquid fuel can be pumped

Magma

two-phase mixture of mother liquor and crystals occupying the crystallizer and withdrawn as product is called

Orsat gas analyzer

used to analyze gas samples for its oxygen, carbon monoxide and carbon dioxide content

Evaporator

used to concentrate a solution consisting of a non-volatile solute and volatile solvent

Bourdon gauge

usually gives gauge pressure of the liquid

Free state or Raw sulfur

usually obtained in elemental form as contaminants of natural gas and petroleum refinery