| # | Country | Total Patents | |
|---|---|---|---|
| #1 | Germany | 8 | |
| #2 | United Kingdom | 4 | |
| #3 | United States | 3 | |
| #4 | USSR (Union of Socialist Soviet Republics) | 1 |
| # | Industry | |
|---|---|---|
| #1 | Thermal processes |
| # | Technology | |
|---|---|---|
| #1 | Grates | |
| #2 | Steam generation | |
| #3 | Cleaning heat-exchanger internal surfaces |
| # | Name | Total Patents |
|---|---|---|
| #1 | Ferdinand Graafen | 4 |
| Publication | Filing date | Title |
|---|---|---|
| US2005544A | Furnace grate | |
| GB414956A | Improvements in furnace grates | |
| SU37081A1 | Water-cooled pushing grate | |
| US1975601A | Furnace grate | |
| US2005543A | Water tube boiler | |
| GB397634A | Improvements in water-tube boilers | |
| GB397446A | Improvements in furnace grates | |
| GB397633A | Improvements in furnace grates |