Variable speed compressor gas turbine

Pochari Technologies’ has invented a radically innovative new type of gas turbine.
The traditional gas turbine is comprised of a compressor, combustor and turbine wheel made of many small blades (used to extract energy from the expanding gases). In order to achieve complete and therefore efficient combustion, a high volume of air at a sufficient pressure is required to achieve the optimal mixture of air and fuel. Oxygen, although not a fuel in itself provides the basis of combustion. As anyone who has experimented with fire has learned, if you blow air over a fire you will increase the intensity of the combustion and thus raise the temperature, the fuel source will subsequently be consumed at a faster rate. A greater level of temperature will lead to greater expansion of the gases, creating more pressure and allowing the turbine blades to extract more power, leading to greater thermal efficiency. Industrial waste incinerators for example use large blowers to increase combustion temperature and to achieve a hotter burn, reducing emissions. In a gas turbine, the compressor is directly connected to the turbine unit, which poses an inherent problem. The speed of the compressor and the turbine do not always converge at the same optimal speed. During low turbine operating speed efficiency is much lower. This is partially due to the compressors inability to provide sufficient air flow and pressure. Centrifugal compressors (commonly used on small turbines) tend to only provide peak pressures ratios at very high rotational speed. If gas turbines are to be operated at maximum possible thermal efficiency it must maintain maximum operating speed, making it challenging to provide feasible propulsion for ground based vehicles. This is one of the reasons the gas turbine has not historically been competitive with Otto or Diesel cycle engines. To solve the gas turbine’s issue with efficient operation at varying levels of speed we provide a highly innovative variable speed compressor by utilizing an electric drive system. In addition to solving this issue we also significantly ameliorate another major issue: excessive gas temperature during startup. This is also caused by a lack of airflow from the compressor. During start up fuel is injected at an increasing rate to increase combustion volume and accelerate the turbine. During this time the air fuel ratio mixture is too rich, causing a rapid rise of temperature which causes a situation known as “thermal shock”. This leads to a shorter life span for the turbine blades. A rapid decline in temperature during shut down also leads to the same problem. This is why gas turbine hot section components are commonly given a limited number of “cycles” before replacement is required.
In some cases one cycle is equivalent to an entire hour of continuous operation. The variable speed system will provide high airflow during startup, maintaining optimal temperature. During shut down the operator can run the compressor at full speed to provide cool air to cool the hot turbine section at a slower rate than what would otherwise occur if the engine is immediately shut down. In short Pochari Technologies’ VSCG in addition to providing enhanced efficiency at low operating speed, will also result in major reductions in temperature related fatigue of hot sections components allowing for significant reduction in direct operating costs. Pochari Technologies’ VCSG. The system is comprised of a high speed DC generator connected to the power turbine output shaft prior to the final reduction gearbox. The generator provides electrical current to multiple high speed axial flux motors connected directly to the compressor. A lithium ion battery pack is provided to enable the compressor to be powered at high speed during occasions where insufficient electrical power is being generated by the turbine during startup and spool up.
To summarize Pochari Technologies’ VSGT provides major technical advantages to operations that require the benefits of gas turbine technology but require variable speed. These applications could be powering a heavy duty transport vehicle, combat vehicle or even continuous high power applications that require frequent start up and shut down.

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