11 Apparatus for the exchange of substances and heat for use in the production of steam, for use in cooking and for use in refrigeration; Electric egg boilers; Electric food steamers; Electric food warmers in the nature of dishes, portable household appliances, bowls and trays.; Electric rice steamers; Electric slow cookers; Electric vegetable steamers; Electrical rice cookers; Food steamers, electric; Heating installations; Portable electric household appliance used to kill bacteria and viruses on food; Power-operated vaporizers for household purposes