Reference Document on Best Available Techniques for the

3,45
MB Manufacture of Large Volume Inorganic Chemicals - Ammonia,

446
stron Acids and Fertilisers

6060
ID JRC-IPTS Instituto de Prospectiva Tecnológica (IPTS)

2007
rok

EXECUTIVE SUMMARY I

PREFACE .XI

SCOPE.XXV

1 OVERVIEW TO THE PRODUCTION OF LVIC-AAF1

1.1 General information1

1.1.1 Overview 1

1.1.2 Environmental issues3

1.1.2.1 Energy consumption and emission of greenhouse gases 3

1.1.2.2 Energy export .3

1.1.2.3 High exhaust gas volume flows 4

1.1.2.4 Large volume by-products 4

1.1.2.5 Issues arising from impurities in raw materials 5

1.1.2.6 Safety issues .5

1.2 Integrated production sites7

1.2.1 Overview 7

1.2.2 Some examples.7

1.2.3 Supply of steam and electricity.10

1.2.3.1 Steam turbines and steam grid 10

1.2.3.2 Exporters and consumers on an integrated production site.11

1.3 Overview of emissions and consumption levels .12

1.4 Common techniques to consider in the determination of BAT.12

1.4.1 Increase process integration (1) 13

1.4.2 Increase process integration (2) 15

1.4.3 Handling excess steam16

1.4.4 Replacing old PRDS valves17

1.4.5 Optimisation/maintenance of vacuum pumps.18

1.4.6 Mass balances.19

1.4.7 Recovery of NOx from exhaust gases .21

1.4.8 Techniques described elsewhere in this document .23

1.4.9 Environmental management tools 24

1.5 Common BAT 32

1.5.1 Common BAT for the LVIC-AAF industries.33

1.5.2 BAT for environmental management .34

2 AMMONIA35

2.1 General information35

2.2 Applied processes and techniques 37

2.2.1 Overview 37

2.2.2 Output from ammonia production 38

2.2.2.1 Ammonia 38

2.2.2.2 Carbon dioxide .38

2.2.2.3 Sulphur .38

2.2.2.4 Steam38

2.2.3 Conventional steam reforming .39

2.2.3.1 Desulphurisation.39

2.2.3.2 Primary reforming 40

2.2.3.3 Secondary reforming 41

2.2.3.4 Shift conversion41

2.2.3.5 CO2 removal .41

2.2.3.6 Methanation 42

2.2.3.7 Compression .42

2.2.3.8 NH3 synthesis .43

2.2.3.9 Steam and energy system43

2.2.4 Partial oxidation44

2.2.4.1 Air separation plant.44

2.2.4.2 Gasification of heavy hydrocarbons. 45

2.2.4.3 Soot removal 45

2.2.4.4 Gasification of coal 45

2.2.4.5 Sulphur removal . 46

2.2.4.6 Shift conversion . 46

2.2.4.7 CO2 removal. 46

2.2.4.8 Liquid nitrogen wash 47

2.2.4.9 Ammonia synthesis 47

2.2.4.10 Compression, steam and energy system. 47

2.2.5 Startup/shutdown and catalyst replacement . 47

2.2.6 Storage and transfer equipment 48

2.3 Current emission and consumption levels 49

2.3.1 Energy consumption 49

2.3.1.1 Comparison of energy consumption figures. 49

2.3.2 NOx emissions 52

2.3.3 Other consumption levels. 54

2.3.4 Other emission levels . 55

2.4 Techniques to consider in the determination of BAT. 58

2.4.1 Advanced conventional processes 58

2.4.2 Processes with reduced primary reforming and increased process air . 60

2.4.3 Heat exchange autothermal reforming . 62

2.4.4 Revamp: increase capacity and energy efficiency . 64

2.4.5 Pre-reforming. 66

2.4.6 Energy audits . 67

2.4.7 Advanced process control 70

2.4.8 Use of gas turbine to drive the process air compressor 71

2.4.9 Combined Claus unit and tail gas treatment. 72

2.4.10 SNCR at the primary reformer. 73

2.4.11 Improved CO2 removal systems. 75

2.4.12 Preheating of combustion air . 76

2.4.13 Low temperature desulphurisation. 77

2.4.14 Isothermal shift conversion 78

2.4.15 Use of smaller catalyst particles in ammonia converters . 79

2.4.16 Stripping and recycling of process condensates. 80

2.4.17 Low pressure catalyst for ammonia synthesis 81

2.4.18 Use of sulphur resistant catalysts for shift reaction of syngas from partial oxidation 82

2.4.19 Liquid nitrogen wash for final purification of the synthesis gas 83

2.4.20 Indirect cooling of the ammonia synthesis reactor. 84

2.4.21 Hydrogen recovery from the purge gas of the ammonia synthesis loop 85

2.4.22 Ammonia removal from purge and flash gases in a closed loop 86

2.4.23 Low NOx burners . 87

2.4.24 Metal recovery and controlled disposal of spent catalysts . 88

2.4.25 Handling of startup, shutdown and abnormal operating conditions. 89

2.4.26 Ammonia production using hydrogen from water electrolysis 91

2.5 BAT for ammonia 92

3 NITRIC ACID. 95

3.1 General information . 95

3.2 Applied processes and techniques 96

3.2.1 Overview. 96

3.2.2 Raw material preparation . 96

3.2.3 Oxidation of NH3 . 96

3.2.4 Oxidation of NO and absorption in H2O 97

3.2.5 Tail gas properties and emission reduction 99

3.2.6 Energy export. 99

3.2.7 Production of concentrated nitric acid . 100

3.3 Current emission and consumption levels 101

3.4 Techniques to consider in the determination of BAT. 110

3.4.1 Oxidation catalyst performance and campaign length . 110

3.4.2 Optimisation of the oxidation step . 113

3.4.3 Alternative oxidation catalysts. 115

3.4.4 Optimisation of the absorption stage 117

3.4.5 N2O decomposition by extension of the reactor chamber 121

3.4.6 Catalytic N2O decomposition in the oxidation reactor .123

3.4.7 Combined NOx and N2O abatement in tail gases127

3.4.8 Non-selective catalytic reduction of NOx and N2O in tail gases.130

3.4.9 Selective catalytic reduction of NOx (SCR) .132

3.4.10 Addition of H2O2 to the last absorption stage.135

3.4.11 NOX reduction during startup/shutdown.137

3.5 BAT for nitric acid140

3.6 Emerging techniques for nitric acid142

3.6.1 Combined NOx and N2O abatement with addition of hydrocarbons 142

4 SULPHURIC ACID.145

4.1 General information145

4.2 Applied processes and techniques 151

4.2.1 Overview 151

4.2.2 Catalysts .155

4.2.3 Sulphur sources and SO2 production 156

4.2.3.1 Sulphur combustion156

4.2.3.2 Regeneration of spent acids 156

4.2.3.3 Pyrite roasting.157

4.2.3.4 Spent acid from TiO2 production and roasting of metal sulphates .157

4.2.3.5 Non-ferrous metal production.158

4.2.3.6 Other raw gas sources.159

4.2.4 Product H2SO4 treatment 161

4.3 Current emission and consumption levels 162

4.4 Techniques to consider in the determination of BAT.171

4.4.1 Single contact/single absorption process 171

4.4.2 Double contact/double absorption process .173

4.4.3 Addition of a 5th bed to a double contact process .176

4.4.4 Application of a Cs-promoted catalyst .178

4.4.5 Change over from single to double absorption.181

4.4.6 Replacement of brick-arch converters 182