Basic concept and characteristics of top pressure recovery steam turbine

TRT is an energy-saving equipment used in blast furnaces in steel mills.It has the following two functions.One is to control the top pressure of the blast furnace,and the other is to use the blast furnace gas to drive the steam turbine to generate electricity.Generated in a blast furnace has played a role in energy saving and environmental improvement of global steel.

Features:

• Original technology and manufacturing

• High reliability and experience

• Fully enclosed vane control system with less noise

• High efficiency

• Excellent blast furnace top pressure control performance

• Excellent maintenance service

• Blast furnaces for steel mills

Basic Concept 

The top pressure recovery steam turbine unit is installed downstream of the blast furnace gas purification equipment.There are two types of gas purification equipment: a wet type that uses water and a dry type that does not use water.After dust is collected by either of them,the blast furnace gases are directed to and drive the turbines while expanding from around the furnace roof pressure to atmospheric pressure.The electricity generated by the turbine is sent to the generator and converted into electricity.In traditional practice,the energy of the blast furnace gas is wasted due to the pressure reduction.Now recovered as electricity for significant energy savings.There are two types of turbines:radial turbines and axial turbines.At present,the axial flow turbine is widely used because it is more suitable for handling large flows.The furnace top pressure is controlled by opening or closing the first stage stator vane of the steam turbine according to the increase or decrease of the blast furnace gas volume.For conventional steam turbines,a governor valve is also used in combination to control the top pressure.However,the regulating valve causes a larger pressure loss than the stator vane,and thus is disadvantageous in terms of power recovery and noise prevention.Therefore,in the system widely used now,the speed control valve is canceled,and the top pressure is only controlled by the first-stage stator vane.

Effects:

Depending on the size of the blast furnace,typically up to 35,000kW of power can be provided.In recent years,the size of blast furnaces has been increasing. As a result,the production of top pressure recovery turbine power plants is increasing.In September 1974,delivered the first head pressure recovery turbine plant in Japan,and since then we have continued to make various technological improvements for better head pressure control and higher energy recovery, such as developing the axial flow reaction Turbine and control system using only first stage stator blades.

Blast furnace gas top pressure recovery steam turbine

Modern blast furnaces in steelworks operate on blast top gas pressure.The blast furnace (BF) gas leaving the BF at the top remains at a pressure of about 1.6 kg/sq cm (g) to 3 kg/sq cm (g) and has a temperature of about 200 degrees Celsius.This BF gas comes out of the top of the blast furnace cleaned to remove dust and is used as fuel in steel mills for heating at relatively low pressure.In the process,a large amount of pressure energy is lost at the valve.Blast furnace gas top pressure recovery steam turbine (TRT) is a mechanism that uses the heat and pressure energy of blast furnace gas to drive a steam turbine.The work produced by the turbine is transferred to the generator and converted into electrical energy.TRT generates electricity by exploiting a known property of all gases,which is that gases expand in volume as pressure decreases.The system includes dedusting equipment,gas turbines and generators.TRT is basically an energy saving measure for blast furnaces,which uses the waste pressure energy of blast furnace top gas to generate electricity.A TRT unit can produce approximately 15 to 60 kWh/t of hot metal (HM).Its output power can meet about 30% of the power required by all blast furnace equipment (including fans). The BF gas leaving the TRT unit can still be used as fuel for the steel mill.During the ironmaking process,high-temperature and high-pressure blast furnace gas is produced in the blast furnace.In traditional practice,the energy of the blast furnace gas would be wasted by decompression at the diaphragm valve. Equipping TRT device is the best way to recover blast furnace gas pressure and heat energy.TRT devices are generally installed downstream of blast furnace gas purification equipment.Usually,it is economical to equip a blast furnace with a capacity greater than 1000 m3 with TRT.The TRT system is a power generation system that uses an expansion turbine to convert the physical energy of the high-pressure blast furnace top gas into electrical energy.Despite the low pressure differential,the large volume of gas makes recovery economically feasible.The key technology of TRT is to ensure the stable and efficient operation of the expansion turbine under the dusty blast furnace conditions without affecting the operation of the blast furnace.