IST designs and manufactures Once Through heat recovery Steam Generators (OTSGs) for the industrial and power generation sectors. OTSGs are best suited, technically and economically, for the following applications: . Once Through Steam Generation is IST's solution to the limitations of traditional drum-type boilers.

The once-through steam generator (OTSG), in its simplest form, is a continuous tube heat exchanger in which preheating, evaporation, and superheating of the feedwater takes place consecutively, see Figure 1.

Each once-through steam generator (OTSG) is a vertical, straight, tube-and-shell heat exchanger which produces superheated steam at constant turbine throttle pressure throughout the power range. Figure 2.4-1 is a cross-sectional view of the OTSG.

The OTSG HFT was designed to include transients which - will stress the OTSG tubes, open up any cracks which are on the threshold | of propagation or open up any undetected cracks further.

Seal Separator. This separator is simply a small vessel located between the evaporator and superheater sections of the OTSG. In normal gas turbine operation, it has superheated steam entering and exiting. However, during startup and shutdown, it can allow water to circulate through the OTSG, by use of a

Heat Recovery Steam Generators (HRSG) and Once Through Steam Generators (OTSG) generate saturated or superheated steam recovered from the exhaust heat of the Gas Turbines or Diesel Engines. Steam is used for extra power production in steam turbines and also to satisfy process and utilities heat demands.

OTSG and Plant Feedwater Treatment •No blowdown so water quality critical •Requires demineralized and polished feedwater. –Cation Conductivity Limit: 0.25 μS/cm •IST recommends stainless FW piping from polisher to OTSG (particularly for cycling plants) •Eliminates: –Tube scaling –Deposition and carry over

Natural gas is piped through “runners” and distributed by nozzles across the width of the duct. Use a Forced Daft Fan and Duct Burner combination to simulate the gas turbine exhaust during a GT outage. Common in cogen applications where an uninterrupted steam supply is paramount.

Once through steam generators are a type of heat exchanger used in pressurised water reactors (PWR) for boiling water into steam. Typically, there are two to four OTSGs per reactor. Each OTSG may be up to 21m in height and weigh up to 800 tons. Each OTSG is connected to a primary and secondary loop.

The OTSG has a vertical-shell counterflow straight-tube heat exchanger design, which directly generates superheated steam as the feedwater flows through the steam generator in a single pass. BWXT is the exclusive designer and manufacturer of OTSGs for the nuclear industry.