The Gas Turbine (GT) systems comprise two Turbec T100 Microturbines: series 1 and series 3. Both turbines are CHP units integrating the T100 power module generating around a 100kW of electrical power with an exhaust gas heat exchanger generating and additional 170kW of thermal power with an overall efficiency of 77%.
The turbines normally operated on 330kW of natural gas, but the use of fuels such as biogas, syngas, diesel, kerosene, methanol, LPC is also possible enabling research on alternative fuels.
The exhaust from the heat exchanger is connected to the onsite Solvent-based Carbon Capture Plant. This enables research into post-combustion carbon capture from gas turbine based power generation. The concentration of CO2 in the GT flue gases is typically low (1.5%-6%. This affects the economic and technical viability of the carbon capture process. PACT is developing an Exhaust Gas Recycling system for the turbines (GT-EGR) to increase the CO2 concentration in the flue gas for carbon capture applications. Furthermore PACT is also looking at Humid Air Turbine Cycle to also enhance efficiency
The microturbine uses a high speed generator to produce electricity with the compressor and the turbine both placed on the same shaft as the generator. An exhaust gas recuperator is connected to the microturbine to improve the electrical efficiency and the hot flue gases leaving the turbine are passed through a heat exchanger to heat up water.
The electric power is generated a high conversion efficiency water-cooled generator.
The turbine engine comprises a compressor and turbine. The Turbec T100 uses a radial centrifugal compressor to compress ambient air with pressure ratio of about 4.5:1. The turbine drives the compressor and the generator, both mounted on the same shaft as the turbine. The compressed air, which has been preheated by the recuperator (see below), enters the combustion chamber where it is mixed with the fuel. The combustion chamber is of lean pre-mix emission type, achieving exhaust gases with low emissions of NOx, CO and unburned hydrocarbons. When the combustion gases leave the combustion chamber the temperature is approximately 950°C and pressure is approximately 4.5 bar. As the combustion gases expand through the turbine the pressure decreases to nearly atmospheric pressure and the temperature drops to approximately 650°C.
The recuperator is a gas-to-air heat exchanger attached to the microturbine. The heat is exchanged from the hot exhaust gases to the compressed air that is fed to the combustion chamber.
The temperature of the exhaust gases is approximately 270°C when they enter the exhaust gas heat exchanger. The heat exchanger is of gas-water counter-current flow type. The thermal energy from the exhaust gases is transferred to the hot-water system. The outlet water temperature depends on the incoming water conditions, temperature and mass flow, typically 70-90°C. The cooled exhaust gases leave the exhaust gas heat exchanger through site stack.
A tee in the exhaust duct provides connection to the PACT Solvent-based Carbon Capture Plant (SCCP). System fan on the SCCP draws the required amount of flue gas. The GT generates flue gas in excess of the volume taken by the SCCP with the remainder leaving through the site stack.
The T100 is controlled and supervised by an inbuilt automatic control system (Power Module Controller). The PMC has a built-in web based remote system for remote monitoring and operation of the turbine. The turbine records a variety of parameters for system monitoring and analysis. The data can be downloaded from the turbine via an Ethernet link to a monitoring and control software package
o Flue gas analysis: dedicated flue gas analysers are installed serving both turbines and monitoring CO2 (both high and low concentrations), O2, NOx, SOx and THC concentrations in the flue gas outlet sampling and recorded continuously.
o Emissions monitoring: a GASMET FTIR industrial analyser is also used for monitoring the above gases, THC components, water and other gases. A PERKIN ELMER SQ8 GCMS analyser is also available for analysis of gaseous samples.
o Particle size analysis: a CAMBUSTION DMS500 Fast particulate analyser is used for flue gas particle analysis with particle size, number and mass spectra in real time.
o Other analysis: Other analysis can also be provided through the extensive analytical facilities of the Universities of Leeds and Sheffield who jointly operate the PACT site.
The turbines are normally operated one a time via a change over switch.