Waste heat boilers are widely used today in the oil, chemical, textile, food and other industrial sectors. What are these units, what are they intended for and what is their structure?
Waste heat boiler operation
The purpose of such a boiler is to obtain superheated steam of low and high pressure, as well as to heat the condensate of a steam turbine using heat from the hot exhaust gases generated by the gas turbine unit. Due to its modern design, the waste heat boiler allows performing pre-start and operational water-chemical flushing of the steam-water path, as well as preserving its internal surfaces during shutdowns.
The operating range of the unit load changes corresponds to the load range of the gas turbine unit.
During the operation of the waste heat boiler in production, the amount of nitrogen oxide emissions in the system of the gas turbine plant and the boiler itself is determined by their quantity and concentration behind the installation, while in the waste heat generator there are no solutions to reduce emissions. In addition, the waste heat boiler is capable of operating when the temperature and flow rate of gases that come from the gas turbine unit change. The principle of operation of the boiler is based on the sliding parameters of steam supplied under the pressure of gases from a gas turbine unit.
Waste heat boiler device
The gas duct of the unit, in which the heating surfaces are located, suspended from the ceiling slabs of the frame, forms a metal sheathing attached to the columns of the frame in the area of the heating surfaces. The drums are also supported by steel frame structures. On the inside, the flue and diffuser are covered with insulation, which in turn is protected by a steel sheathing.
The frame elements of the waste heat boiler are interconnected by high-strength bolted joints.
The steam-water path of the unit is equipped with a set, which includes shut-off, control and protective valves, instrumentation, drains, air vents and devices for sampling water / steam. In addition, fittings, bosses and other selection devices for the gas path are installed in the boiler flue. The outlet part of the flue, consisting of a confuser and a sound attenuator, is covered with decorative cladding that hides the outer insulation. In the area of heating surfaces located at the top and bottom of the gas duct, there are "warm" boxes, which are separated from the gas flow by means of removable metal shields.
The waste heat boiler is gas-tight, and the strength of its gas flue body is able to withstand 4.0 kPa - this is the excess pressure of gases entering the boiler after the gas turbine installation, while the exposure to cotton is 3.0 kPa.
