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Chemistry (Tara) > Additional industrial chemistry > Flashcards

Additional industrial chemistry Flashcards

(107 cards)

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1
Q

3 ways to organise the operation of a chemical manufacturing process

A

batch process
continuous process
semi-continuous process

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2
Q

batch process

A

raw materials place into a vessel (batch reactor) and allowed to react together, conditions are monitored. when reaction finished, products are isolated and process repeated with fresh batch of raw materials

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3
Q

continuous process

A

raw materials fed in at one end of processing plant and product is continuously removed at other end

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4
Q

example of continuous process

A

the manufacture of ammonia

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5
Q

semi-continuous process

A

combination of batch and continuous processes. first part is a batch process to make the product, second stage involves continuous process where product is purified using materials from several batch reactors

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6
Q

example of semi-continuous process

A

soft drink industry, soft drink is produced in a batch process and the addition of carbon dioxide and bottling is continuous

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7
Q

advantage of batch processing

A

more effective for smaller quantities of materials and the same vessel can be used for a range of products

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8
Q

disadvantage of batch processing

A

they require larger workforces and contamination can occur from batch to batch

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9
Q

advantage of continuous processing

A

better suited to larger quantities, low risk of contamination and can run for long periods of time with low labour needs

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10
Q

disadvantage of continuous processing

A

the plant is expensive to build, is not flexible for other products and hence may not be cost effective

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11
Q

feedstock

A

reactants used - produced from the raw materials

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12
Q

rate

A

conditions involved chosen for optimum rate

real conditions may not be necessarily the ideal, compromises must be made to ensure that it is cost effective

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13
Q

production yield

A

conditions chosen to produce a reasonable yield of product in reasonable time - compromises must be made

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14
Q

co-products

A

other products made alongside the main product

can be sold or separated and disposed of appropriately

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15
Q

waste disposal and effluent control

A

contaminated water may contain hazardous material and has to be treated before it is released - some gases can be dangerous (produce acid rain or damage ozone layer), must be purified and monitored

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16
Q

quality control

A

the quality of the feedstocks and products are constantly checked in laboratories so that they are of a required standard

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17
Q

safety

A

staff trained on site and continuous monitoring of hazards - safety features incorporated e.g safety glasses, first aid etc.

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18
Q

3 costs

A

capital costs
fixed costs
variable costs

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19
Q

capital costs

A

cost involved in setting up the plant

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20
Q

fixed costs

A

salaries, repayments of loans, plant depreciation

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21
Q

variable costs

A

raw materials, waste disposal, plant maintenance

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22
Q

ways of reducing costs

A

recycling of unreacted feedstocks, use of heat exchanger selling of co-products, essential equipment

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23
Q

sit location

A

access to roads, ports etc. for transport
available cheap energy and water
available skilled workforce
tax incentives etc.

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24
Q

suitable materials for construction of chemical plant

A

do not react with feedstocks, catalysts or solvents
resistant to corrosion, long-lasting
withstand temperatures and pressures used

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25
process for manufacture of ammonia
continuous process
26
manufacture of ammonia by
IFI in Cobh, Co.Cork
27
manufacture of ammonia | feedstock
raw materials compressed of air, natural gas and water nitrogen - compressed air hydrogen - natural gas and water
28
manufacture of ammonia | do to air first
filtered to remove dust
29
manufacture of ammonia | do to water first
passes through ion exchange resins to deionise it
30
manufacture of ammonia | natural gas first
methane coming from Kinsale gas field, piped underwater to Inch beach in East Cork and supplied underground to IFI in cork, mercaptans added to ensure it has an odour
31
manufacture of ammonia | how do they ensure that the catalyst is not poisoned
first the sufur compunds are removed from naturl gas by mixing incoming gas with hydrogen and passing it over a cobalt/nickel/alumina catalyst hydrogen sulfide is formed and then removed
32
manufacture of ammonia | where does the hydrogen come from
recycled from later on in the process
33
manufacture of ammonia | primary steam reforming
methane gas heated with steam in the presence of a catalyst to produce hydrogen 90% of methane consumed, reaction occurs in a reforming furnace, which contains 520 catalyst filled tubes
34
manufacture of ammonia | equation of primary steam reforming
CH4 + H2O ⇌ CO2 + 3H2
35
manufacture of ammonia | heat change of forward reaction in primary steam reforming
endothermic
36
manufacture of ammonia | secondary reforming
remaining 10% of methane
37
manufacture of ammonia | equation for secondary reforming
CH4 + 2O2 -> CO2 + 2H2O
38
manufacture of ammonia | removal of carbon monoxide equation
CO + H2O ⇌CO2 + H2
39
manufacture of ammonia | heat change of forward reaction in secondary steam reforming
exothermic
40
manufacture of ammonia | name of reaction of secondary steam reforming
shift reaction
41
manufacture of ammonia | significance of secondary steam reforming being exothermic
allows for heat recovery which emphasises the thermal efficiency of the ammonia process
42
manufacture of ammonia | explain the removal of carbon dioxide
the gas is scrubbed with a hot potassium carbonate under high pressure and temperature to form potassium hydrogen carbonate, it is then removed from the system
43
manufacture of ammonia | equation for removal of carbon dioxide
CO2 + K2CO2 + H2O -> 2KHCO3
44
manufacture of ammonia | methanation
the gas is hydrogenated using a catalyst to convert remaining CO and CO2 into methane, as traces of these gases could poison the catalyst in the manufacture of NH3
45
manufacture of ammonia | equation for methanation
CO + 3H2 -> CH4 + H2O
46
manufacture of ammonia | heat change of methanation
exothermic
47
manufacture of ammonia | feedstock
nitrogen and hydrogen
48
manufacture of ammonia | according to Le Chatelier's Principle, what are the ideal conditions?
low temperature and high pressure
49
manufacture of ammonia | low temperature
slow reaction
50
manufacture of ammonia | high pressure
expensive vessel
51
manufacture of ammonia | actual conditions
high pressure of 200 atm and temperature of 500ºC
52
manufacture of ammonia | catalyst
divided iron
53
manufacture of ammonia | promoter
aluminium oxide
54
manufacture of ammonia | how much of the nitrogen and hydrogen react to form ammonia
about 17%
55
manufacture of ammonia | what is done to the ammonia
liquified and stored at -33ºC at atmospheric pressure, or sent directly to urea plant
56
manufacture of ammonia | co-product
carbon dioxide
57
manufacture of ammonia | how is the carbon dioxide released
can be released from potassium hydrogencarbonate by heating it and reducing the pressure
58
manufacture of ammonia | what is done with the CO2 made?
used in the manufacture of urea on site and can also be sold to soft drink companies and breweries
59
manufacture of ammonia | what do they treat the effluent with?
the plant effluent is treated with ion exchange resins to facilitate the recycling of ammonia and carbon dioixed back into the production steam
60
manufacture of ammonia | rate of treatment
225 m3 per hour of water recovered
61
manufacture of ammonia | what are air emissions monitored for?
the presence of ammonia, oxides and nitrogen
62
manufacture of ammonia | CO2
emitted to atmosphere
63
manufacture of ammonia | steam
emitted to atmosphere
64
manufacture of ammonia | ammonia
flamed and emitted as nitrogen
65
manufacture of ammonia | 2 other products
nitrous oxides | water
66
manufacture of ammonia | 2 procedures to analyse the gas mixtures at all stages of the ammonia production
gas chromatography | infra red spectroscopy
67
manufacture of ammonia | safety
2 alarm systems, fire alarm and alarm to indicate gas release workforce trained in first aid and fire fighting site designed to allow fire engines into central parts
68
manufacture of ammonia | fixed costs
labour costs, plant depreciation and repayment of loans
69
manufacture of ammonia | variable costs
raw materials, heat and electricity and waste disposal
70
manufacture of ammonia | cost of natural gas
increased as running out in Kinsale, is now obtained from the North Sea - more expensive due to transport costs
71
manufacture of ammonia | who supplies water and how much
supplied by local council - 4.5 million L per day
72
what reduces the cost
recycling and sale of the co-product heat exchangers in the exothermic reactions use of catalyst to allow lower temperatures
73
manufacture of ammonia | site location
marino point in Cobh, Co.Cork
74
manufacture of ammonia | 4 reasons for location
natural gas nearby skilled personnel in Cork area seawater available for cooling rail and sea available for transport of products
75
manufacture of ammonia | construction materials
mild steel on a deep concrete foundation | stainless steel for reaction chambers and compressors - low rate of corrosion
76
3 uses of ammonia
manufacture of urea manufacture of nitric acid manufacture of fertilisers
77
manufacture of urea | where?
by IFI in Cobh, Co.Cork
78
manufacture of urea | type of process
continuous process
79
manufacture of urea | raw materials and where do they come from
anhydrous ammonia and potassium hydrogen carbonate | produced by IFI
80
manufacture of urea | what is done to the potassium hydrogen carbonate
heat and pressure reduced to produce carbon dioxide
81
manufacture of urea | equation for producing carbon dioxide
2KHCO3 -> CO2 + H2O + K2CO3
82
manufacture of urea | feedstock
ammonia and carbon dioxide
83
manufacture of urea | first step
ammonia and carbon dioxide reacted together to form ammonium carbamate
84
manufacture of urea | equation for reaction with ammonia and carbon dioxide
CO2 + 2NH3 ⇌ NH2COONH4
85
manufacture of urea | heat change in forward reaction of ammonia and carbon dioxide
exothermic
86
manufacture of urea | ideal conditions
carried out at high temperature to favour the forward reaction and heat produced in removed immediately to ensure completion of reaction
87
manufacture of urea | what happens to ammonium carbamate
ammonium carbamate loses water to form urea n a carbamate condenser
88
manufacture of urea | equation for when ammonium carbamate loses water
NH2COONH4 ⇌ CO(NH2)2 + H2O
89
manufacture of urea | heat change when ammonium carbamate loses water
endothermic
90
manufacture of urea | speed of reaction when ammonium carbamate loses water
slow but sped up with high temperature
91
manufacture of urea | left over ammonium carbamate
decomposed to form ammonia and carbon dioxide and these gases are recycled to the condenser to react
92
manufacture of urea | what is done to the urea
changed into molten urea in an evaporator, then prilled
93
manufacture of urea | prilling
process that involves spraying the molten urea downward from the top of a tall prill tower against an upward flow of air, causes urea to solidify into small spherical particles called prills
94
manufacture of urea | co-products
there are no co-products
95
manufacture of urea | waste disposal and effluent control
treated with steam to hydrolyse urea to ammonia and carbon dioxide which is recycled air emissions monitored for the presence of urea dust
96
manufacture of urea | quality control
gas chromatography and infra red spectroscopy are carried out to analyse the gas mixtures at all stages of the ammonia production
97
manufacture of urea | safety
2 alarm systems, fire alarm and alarm to indicate gas release workforce trained in first aid and fire fighting site designed to allow fire engines into central parts
98
manufacture of urea | fixed costs
labour costs, plant depreciation and repayment of loans
99
variable costs
raw materials, heat and electricity and waste disposal
100
manufacture of urea | reduce costs
recycling and sale of the co-product heat exchangers in the exothermic reactions use of catalyst to allow lower temperatures
101
manufacture of urea | site location
marino point in Cobh, Co.Cork
102
manufacture of urea | why that location?
natural gas nearby skilled personnel in Cork area seawater available for cooling rail and sea available for transport of products
103
manufacture of urea | construction materials
mild steel on a deep concrete foundation is used in some areas of the plant stainless steel is used in parts of the plant - reaction chambers and compressors, low rate of corrosion
104
3 uses of urea
as a fertiliser on runways as a non-corrosive de-icer manufacture of MDF (medium density fibreboard)
105
2 other important chemicals produced in Ireland
Nitric acid | magnesium dioxide
106
where is nitric acid produced?
from ammonia by IFI in Arklow, Co.Wicklow
107
where is magnesium dioxide produced?
from seawater by Premier Periclase in Drogheda

Chemistry (Tara) (50 decks)

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