Chapter 5 Hydrothermal Processes in Subcritical Water ................................. 113
5.1 Introduction ........................................................................... 113
5.1.1 Properties of Water at High Temperature and
Pressure .................................................................... 114
5.2 Hydrothermal Carbonization (Wet Pyrolysis)....................... 117
5.2.1 Reaction Mechanisms .............................................. 119
5.2.2 Effects of Operating Conditions............................... 121
5.2.3 Comparison of HTC and Dry Pyrolysis Process ..... 122
5.2.4 Product Characteristics and Usages ......................... 123
5.2.5 Process Considerations............................................. 125
5.3 Hydrothermal Liquefaction ................................................... 125
5.3.1 Reaction Mechanisms .............................................. 126
5.3.2 Effects of Operating Conditions on HTL Process ... 128
5.3.2.1 Pressure, Temperature, and Residence
Time.......................................................... 128
5.3.2.2 Biomass Particle Size, Heating Rate,
and Concentration..................................... 130
5.3.2.3 Gas and Liquid Properties ........................ 131
5.3.3 Role of Feedstock ..................................................... 132
5.3.3.1 Biowastes .................................................. 132
5.3.3.2 Lignocellulose........................................... 133
5.3.3.3 Algae......................................................... 134
5.3.4 HTU Process ............................................................ 136
5.4 Hydrothermal Gasification .................................................... 136
5.4.1 Catalysts for HTG .................................................... 137
5.5 Coal–Water Chemistry .......................................................... 139
5.5.1 Effect of Water Pretreatment of Coal on Coal
Liquefaction.............................................................. 139
5.5.2 Coal Liquefaction in High-Pressure and
High-Temperature Water.......................................... 141
5.5.3 Coal–Water Mixture as Fuel .................................... 142
5.5.3.1 Production of CWF................................... 144
5.5.3.2 Fuel Preparation and Transportation ........ 146
5.5.3.3 Combustion of CWF................................. 147
References ........................................................................................ 148
Chapter 6 Aqueous-Phase Reforming and BioForming Process ...................... 157
6.1 Introduction ........................................................................... 157
6.2 Aqueous-Phase Reforming.................................................... 158
6.3 APR versus Steam Reforming............................................... 159
6.4 Thermodynamics of APR...................................................... 160
viii
Contents
5.1 Introduction ........................................................................... 113
5.1.1 Properties of Water at High Temperature and
Pressure .................................................................... 114
5.2 Hydrothermal Carbonization (Wet Pyrolysis)....................... 117
5.2.1 Reaction Mechanisms .............................................. 119
5.2.2 Effects of Operating Conditions............................... 121
5.2.3 Comparison of HTC and Dry Pyrolysis Process ..... 122
5.2.4 Product Characteristics and Usages ......................... 123
5.2.5 Process Considerations............................................. 125
5.3 Hydrothermal Liquefaction ................................................... 125
5.3.1 Reaction Mechanisms .............................................. 126
5.3.2 Effects of Operating Conditions on HTL Process ... 128
5.3.2.1 Pressure, Temperature, and Residence
Time.......................................................... 128
5.3.2.2 Biomass Particle Size, Heating Rate,
and Concentration..................................... 130
5.3.2.3 Gas and Liquid Properties ........................ 131
5.3.3 Role of Feedstock ..................................................... 132
5.3.3.1 Biowastes .................................................. 132
5.3.3.2 Lignocellulose........................................... 133
5.3.3.3 Algae......................................................... 134
5.3.4 HTU Process ............................................................ 136
5.4 Hydrothermal Gasification .................................................... 136
5.4.1 Catalysts for HTG .................................................... 137
5.5 Coal–Water Chemistry .......................................................... 139
5.5.1 Effect of Water Pretreatment of Coal on Coal
Liquefaction.............................................................. 139
5.5.2 Coal Liquefaction in High-Pressure and
High-Temperature Water.......................................... 141
5.5.3 Coal–Water Mixture as Fuel .................................... 142
5.5.3.1 Production of CWF................................... 144
5.5.3.2 Fuel Preparation and Transportation ........ 146
5.5.3.3 Combustion of CWF................................. 147
References ........................................................................................ 148
Chapter 6 Aqueous-Phase Reforming and BioForming Process ...................... 157
6.1 Introduction ........................................................................... 157
6.2 Aqueous-Phase Reforming.................................................... 158
6.3 APR versus Steam Reforming............................................... 159
6.4 Thermodynamics of APR...................................................... 160
viii
Contents