The temperature of the gas discharged from the gas turbine is as high as 600 degrees Celsius, which still has high energy. These high temperature gases are sent to the boiler, and the water is heated into steam to drive the steam turbine and drive the generator to generate electricity. The power generation capacity and thermal efficiency of the combined cycle unit can be increased by about 50%.

This depends on the waste heat of gas turbine to produce steam boiler is called waste heat boiler.

From the appearance of the boiler is mainly composed of inlet flue, furnace body, drum and chimney.

There are dense pipes in the furnace body, and the water to be heated by the feed pump is pressed into these pipes. The high-temperature gas discharged from the gas turbine heats the water in the pipes into high-pressure steam.

Structure of waste heat boiler

The body of waste heat boiler adopts modular structure to facilitate transportation and installation.

The module is composed of tube cluster, which is a serpentine tube assembly composed of dozens of pipes. The two ends of the module have upper header and lower header, which is the heating part of the boiler. The water is heated by the high temperature gas outside the module.

Waste heat boiler steam flow

Large reheat cycle gas turbine power plant using three pressure waste heat boiler, the system is mainly composed of three parts of low pressure, medium pressure and high pressure, can produce low-pressure superheated steam at the same time, medium pressure superheated steam superheat steam, high pressure, respectively drive low pressure turbine, medium pressure steam turbine, and high pressure steam turbine, the heat energy can make the most of the gas is converted into mechanical work.

The low pressure part is composed of low pressure economizer, low pressure drum, low pressure evaporator and low pressure superheater.

The cold water from the condensate pump is preheated through the low pressure economizer and then fed into the low pressure drum. The drum is connected with the evaporator below. The water is heated in the low pressure evaporator to become saturated steam and rises to the low pressure drum.

The saturated steam is output from the low-pressure drum and heated by the low-pressure superheater to produce low-pressure superheated steam, which is used to drive the low-pressure steam turbine to rotate and do work.

Waste heat boiler steam flow

The medium pressure part is composed of medium pressure economizer, medium pressure drum, medium pressure evaporator, medium pressure superheater and reheater.

The water out of the low pressure steam drum is injected into the medium pressure economizer by the medium pressure feed pump to continue heating, and then enters the medium pressure steam drum, and is heated into saturated steam in the medium pressure evaporator and rises to the medium pressure steam drum.

The saturated steam output from the medium pressure steam drum is heated by the medium pressure superheater, and then mixed with the steam discharged from the high pressure steam turbine. It is heated by the reheater together to produce the medium pressure reheat steam, which is used to drive the medium pressure steam turbine to rotate and do work.

The high pressure part is composed of high pressure economizer, high pressure drum, high pressure evaporator and high pressure superheater.

The water out of the low pressure steam drum is heated by the high pressure feed pump into the high pressure economizer, and then enters the high pressure steam drum, and heated into saturated steam in the high pressure evaporator and rises to the high pressure steam drum.

The saturated steam output from the high-pressure drum is heated by the high-pressure superheater to produce high-pressure superheated steam, which is used to drive the high-pressure steam turbine to rotate and do work.

Waste heat boiler is mainly composed of inlet flue, furnace body, drum and chimney.

There are dense pipes in the furnace body, and the water to be heated by the feed pump is pressed into these pipes. The high-temperature gas discharged from the gas turbine heats the water in the pipes into high-pressure steam.

Large waste heat boiler has low pressure, medium pressure, high pressure three parts, can produce low pressure superheated steam, medium pressure superheated steam, high pressure superheated steam, respectively drive low pressure steam turbine, medium pressure steam turbine, high pressure steam turbine, together with the generator to generate electricity, can greatly increase the power generation of gas turbine power plant.

The principle and composition of large waste heat boilers are basically the same as those of coal-fired power plant boilers, which mainly lack the fuel transportation, crushing and combustion system.