A steam generator is a form of low water-content boiler, similar to a flash steam boiler. The usual construction is as a spiral coil of water-tube, arranged as a single, or monotube, coil. Circulation is once-through and pumped under pressure, as a forced-circulation boiler. The heat may be derived from the combustion of a fuel such as coal, petroleum fuel oil, natural gas, municipal waste or biomass, a nuclear fission reactor and other sources. There are a great many different types of steam generators ranging in size from small medical and domestic humidifiers to large steam generators used in conventional coal-fired power plants that generate about 3,500 kilograms of steam per megawatt-hour of energy production. Steam generators, or boilers, use heat to convert water into steam for a variety of applications. Primary among these are electric power generation and industrial process heating. B&W provides boilers ranging from small package boilers for commercial applications to large, high capacity utility boilers used to generate 1300 MW of electricity. We have the experience to burn virtually any fuel to produce steam efficiently, safely and reliably. This book covers steam generators and related systems used in process plants, refineries, chemical plants, electrical utilities, and other industrial settings. The book is intended for practical engineers, researchers, students and other people dealing with the reviewed problems. We hope that the presented book will be beneficial to all readers and initiate further inquiry and development with aspiration for better future.