AU2009100156A4 - Thermo-chemical solid fuel gasification plant with integrated internal combustion engine and integrated energy storage device - Google Patents

Description

Title of the invention: Thermo-chemical solid fuel gasification plant with integrated internal combustion engine and integrated energy storage device Inventor 1.Inventor Name / Title Dr.-Ing. Berkan First name Jens Street address 42 SchOfield CCT Address, Suburb Caboolture, QLD 451 Od Country AUSTRALIA Nationality German / Australian Proportion of invention [%] 100 Signature Definition: Symbol Description Unit BE Fuel consumption kJ be Specific Fuel Consumption kJ/kWh EcBGideal theoretic ideal potential energy content of the fuel kJ/kg, k/m 3 gas EC,BG,real Actual chemical energy content of the fuel gas kJ/kg, kJ/m 3 n Revolution speed rpm, min M Torque Nm * Air mass flow Kg/s Gas mass flow Kg/s * ~ Exhaust gas mass flow Kg/s Fuel mass flow Kg/s Pei Electric output power kW PmICE Mechanic output power of the intemal combustion kW engine P.._ Power of additional energy supply source kW Heat flow kJ/s TIgen generator efficiency IN overall efficiency Titrans transmission efficiency -- ~j I I.-T Description [0001] The invention relates to a method and a device to operate a power plant to provide mechanical power by a primary source which is a combustion engine and to provide this mechanical power to consumers, which can be for instance an electric generator to generate electric energy, and to divide and timely decouple the relation between energy provided by the combustion engine and energy consumed by the connected consumers. State of the art [0002] In combustion engine propelled generator systems, e.g. with two or multi phases alternating current, the required mechanical energy, to cover the electrical base load of electrical consumers, is generally produced continuously. For instance a generator is operated continuously with a constant revolution speed and supplies permanently an electrical power output to cover the base load and to maintain the electrical output voltage. Thereby the generator is coupled with the combustion engine via a transmission with a constant speed ratio. Thereby the operating revolution speed of the combustion engine is constant and results from the generators electrical frequency, the number of pole pairs of the generator and the speed ratio between the generators revolution speed and the combustion engines revolution speed. A continuously operating generator with the electric output power Pel loads the combustion engine in each point of its consumption characteristic diagram with a mechanical power Pm,ICE, which is given by the generator efficiency characteristic diagram ligen and the transmission efficiency characteristic diagram trmns. Especially if this kind of power plant is used to support or to feed isolated grids, small electrified island grids etc., the whole system needs to be dimensioned to satisfy rare events of extreme peak load. Under other operating conditions, depending on the actual electrical load of the consumers, this could result in a very poor efficiency of the combustion engine, in a high fuel consumption BE, be, and high add on costs due to the required oversizing of the whole system. [0003] The produced electricity must be equivalent to the current consumption of attached consumers. If the sum of the loads of the consumers attached to the generator set is equal or larger than the maximum power of the generator set, as it would be the case when the system is connected to the public grid, then this can be regarded as an infinitely large energy sink for the energy delivered by the generator. In this case the overall system, consisting of combustion engine, transmission and generator, could be permanently operated in the most energy efficient operating point. In such a case (e.g. base load power station) the components combustion engine, generator and transmission can be optimized according this favoured operating point. [0004] If the sum of the consumers attached to the generator is smaller than the maximum power of the generator set, or if this sum varies in arbitrary values between zero (idle operation) and the maximum power of the generator (full load), as it is the case e.g. while feeding into a limited island electricity grid or a single, intermittently operating consumer, then in typical generator systems the constant number of revolution speed of generator and attached combustion engine must be maintained by controlling and regulating the engine's specific load (= amount of fuel burned) according to the momentary load of the connected consumers. In this case the efficiency of the operating combustion engine varies depending on the output power between zero (idle operation) and its design-specific maximum value, in the magnitude of around 40% at best point. The operation of the system in idle or in partial load range results in an increased specific fuel consumption. This problem is intensifying, the larger the generator's and engine's maximum output power has to be designed and more often this generation system operates in the partial load range and/or idle. This problem is also intensifying, the slower the response time of the fuel supply chain is. This could be especially an issue if a solid fuel gasification unit is used to produce a fuel gas to fuel the internal combustion engine. Typical response time of such gasification units can be as large as tens of seconds to increase load from idle to maximum power output. Therefore, in conventional gasification units typically a vessel is used to buffer, harmonize and average the quantity and quality of fuel gas provided to the combustion engine. [0005] Recapping, it is to be stated that often the overall efficiency of the generation of electricity is low and/or that the specific fuel consumption, which is related to the produced electric energy, is high. Further disadvantages are a relatively high engine wear and a reduced specific life span, especially in the partial load range. Further disadvantage are specific high investment costs for such power plant systems if counter measures such as fuel gas vessels are used aJ I r.-T to compensate for slow response time. Accompanying with this, relatively high operating costs and increased maintenance costs also result. [0006] De-coupling of the physical relationship between combustion engine energy output Pm,iCE and electric generator energy output P., would be a solution and a significant improvement of many of the foregoing problems. This can be achieved by decoupling the fixed speed ratio between generator and combustion engine by integration of a transmission, whereby the aim is to arbitrary increase or decrease the combustion engine revolution speed depending on the required generator electric output in order to maintain an optimal operating point of the combustion engine in combination with potential attached solid fuel gasification units. In general, the transmission can be a multi fixed gear ratio box or a cvt type, operating by means of hydraulic, mechanic or any other form of energy transformation. [0007] De-coupling of the physical relationship between combustion engine energy out Pm,iCE and electric generator energy out P.i can also be achieved by attachment and integration of an additional energy supply source between combustion engine and generator. This energy source would provide a variable power output P,.. It could be negative, zero or positive. Negative means that the combustion engine provides more mechanical power than actually required by the generator. The difference is to be removed by the additional energy supply source. Neutral means that the additional energy supply source is "idling" which means that the combustion engine is providing exactly the required amount of mechanic energy used by the generator. Positive means that the combustion engine's mechanic energy provision does not meet the generators requirement and that the remaining difference is provided by this additional energy supply source. The energy supply source itself is connected with an energy storage system. [0008] Summarizing, it can be stated that different possibilities and technological principles to decouple the tight relationship between combustion engine power output and generator electric power output theoretically exist and thus can be applied. [0009] No control procedure or method exists to integrate, in an extended functional range, the components and sub-systems used to provide the additional V i 41? energy supply to optimize the total power plant generation system with regard to cost, flexibility, efficiency and lifetime. [0010] Figure 1 shows exemplarily such a power generation plant with integrated solid fuel gasification unit, whereby (1) is the thermo-chemical fuel gas generator (gasifier). (2) represents the solid fuel supply into the gasifier, whereby (2) features an integrated heat exchanger (3) to pre-condition the solid fuel prior entering the gasifier via connecting device (4). The gasifier also features different supply assemblies for the gaseous oxidizing agent (12) which can feature an additional heating element (17) to heat the gaseous oxidizing agent prior entering the gasification unit. This heating of the gaseous oxidizing agent can also be achieved by a heat exchanger (16), providing thermal energy from a different source. The fuel gas generated by the fuel gas generator passes a de-dusting unit (5) and a fuel gas cooler 6) prior to entering a volumetric gas mixer (7). An additional blower (8) can be integrated to compensate for pressure losses. The volumetric gas mixer (7) mixes the fuel gas with air to provide a combustive gas-air mixture to the internal combustion engine (11). The combustion engine can feature an exhaust gas heat exchanger (9), a coolant heat exchanger (10), a starting device (14) with attached external energy source (15). Typically the generator (13) is directly attached to the combustion engine via shaft (22) and flange (20). The generator can feature additional control devices (18) and can be attached to consumers, e.g. a grid via external electric connection (19). Task [0011] Purpose of this invention is it to describe a component and sub-system assembly and an operating method and procedure to integrate an additional energy supply source into a combustion engine driven mechanical power plant in order to optimize the total power plant generation system with regard to cost, flexibility, efficiency and lifetime. The fully integrated control of this device will also allow for highest security of energy supply for consumers. Different Hardware types and integration strategies are suggested in the following.

1 I 4 [0012] Referring to figure 2, in a preferred configuration is now suggested that: " Between the combustion engine (11) and the generator (13) an additional hydraulic pump (20) will be attached to the shaft (22). Also attached to the shaft will be an additional hydraulic motor (21). " The hydraulic pump (20) can pump hydraulic fluid through the feed pipe (24) into the hydraulic pressurized storage device (23), controlled by the control valve unit (26). The hydraulic pressurized storage device (23) is also attached to the return pipe (25) which is controlled by the control valve unit (27). The return pipe (25) is connected to the hydraulic motor (21). " The addition of this device allows to split the combustion engine's mechanical power output into two different completely independent energy flows. " By controlling valve (26) an arbitrary portion of the combustion engine's momentary mechanical energy output can be diverted into the hydraulic storage device (23) and be stored for later usage. * By controlling valve (27) an arbitrary portion of the hydraulic energy stored in the hydraulic storage device (23) can be diverted back to the shaft between combustion engine and generator, additionally propelling the generator. * Pressure sensors measure the pressure inside the hydraulic storage device (23) and therefore allow calculating the amount of energy stored. * Further a control unit actuating the hydraulic valves (26) and (27) and also controlling the combustion engine's mechanical power output allows to split and to mix the three mechanical power sources, the combustion engine's power output, the hydraulic pump's power requirement and the hydraulic motor's power output, acting on the shaft in such a way that each of the power sources can be separately actuated between 0% and 100% load and that a continuous cross-fade of each separate power source can be adjusted between 0% and 100% load acting on the shaft. " A drag torque model of the hydraulic pump (20) as a function of valve actuation (26) and the state of charge of the hydraulic storage device (23) is used to control the energy flow into the hydraulic pump and the hydraulic storage device. " A motor torque model of the hydraulic motor (21) as a function of valve actuation (27) and the state of charge of the hydraulic storage device (23) is used to control the energy flow into the hydraulic motor and out of the hydraulic storage device. " That the amount of hydraulic power provided by the hydraulic pump for storage into the hydraulic storage device is optimized incrementally in a way that the amount of hydraulic power provided by the hydraulic motor is always sufficient enough to compensate for mechanic load jumps at the shaft (22) which for instance could be resulting from electric load jumps at the generator. This means that the ratio between actual mechanic power provided by the shaft (22) to connected consumers (e.g. generator (13)) and the theoretical maximal power requested by this connected consumers becomes a functional input to determine the required amount of energy to be stored into the hydraulic storage device and to be potentially released to the shaft via hydraulic motor (21). " A. learning function in the control unit can be used to optimize the amount of hydraulic power provided by the hydraulic pump for storage into the hydraulic storage device by calculating the actual mean value of the load of the external connected consumers and the time based actual deviation of load fluctuation and the integration over a specific time interval. This can allow adjusting volume, volume flow and pressure in hydraulic pump, storage device and motor to optimize overall efficiency. " To start the power plant after a shut down, remaining hydraulic energy in the hydraulic storage device can be used to crank and to start the combustion engine in a controlled manner by operating the hydraulic motor (21). [0013] Referring to figure 3, in another preferred configuration is now suggested that: * The hydraulic storage device (23) is replaced by a mass flywheel energy storage device (32).

7 / 4't The hydraulic pump (20) can now pump hydraulic fluid through the feed pipe (30) into the hydraulic motor (31), controlled by the control valve unit (26). The hydraulic motor (31) acts on the mass flywheel (33), providing mechanical energy for acceleration and compensation of mechanical losses. The mass flywheel (33) can feature low friction bearing devices (35) and a vacuum to minimize energy losses. The mass flywheel is also attached to the hydraulic pump (34) which is attached to the return pipe (36) which is controlled by the control valve unit (27). The return pipe (36) is connected to the hydraulic motor (21). [0014] Referring to figure 4, in another preferred configuration is now suggested that: * The hydraulic storage device (23) acts on a feed pipe (25) which is controlled by a control valve (27), acting on a hydraulic motor (21), acting on a separate shaft (22a), acting on a separate generator (13a), connected to the same consumers (19a) as generator (13) or to different consumers. Also the generator (13a) is generic type. It can be replaced by another consumer of mechanic energy. [0015] Referring to figure 5, in another preferred configuration is now suggested that: * The hydraulic storage device (23) is replaced by a mass flywheel energy storage device (32). " The mass flywheel energy storage device (32) acts on the hydraulic pump (34) which is attached to the return pipe (36) which is controlled by the control valve unit (27). The return pipe (36) is connected to the hydraulic motor (21), acting on a separate shaft (22a), acting on a separate generator (13a), connected to the same consumers (19a) as generator (13) or to different consumers. Also the generator (13a) is generic type. It can be replaced by another consumer of mechanic energy.

I %J I A.T [0016] Referring to figure 6, in another preferred configuration is now suggested that: * The control valves (26) and (27) are replaced by active flow volume controlled hydraulic pump (20) and motor (21). [0017] Referring to figure 7, in another preferred configuration is now suggested that: . The shaft between combustion engine (11) and generator (13) features a controlled clutch to physically disconnect the combustion engine from the generator or other attached consumers. If the clutch is engaged, the combustion engine is running with the same revolution speed as the connected consumer, e.g. a generator. If the clutch is disconnected the combustion engine can run on an arbitrary speed, providing arbitrary mechanical energy output which is transferred via hydraulic pump to the hydraulic storage device and the hydraulic motor to drive loads attached to shaft (22), e.g. a generator. [0018] Referring to figure 8, in another preferred configuration is now suggested that: * The shaft between combustion engine (11) and generator (13) features a controlled clutch to physically disconnect the combustion engine from the generator or other attached consumers to allow a gear shift in the integrated transmission (37). By means of this the gear ratio between combustion engine and connected consumers (e.g. a generator) can be varied by changing the selected gear in the gearbox (37). By means of this the combustion engine, providing power for the attached consumers, can be operated in the most suitable gear ratio and therefore revolution speed, to optimize for power output, efficiency and durability. The attached hydraulic pump, hydraulic storage device and hydraulic motor are also used to compensate for temporary interruption of traction force during shift and synchronizing events.

I I / 4?t [0018] Referring to figure 1 to figure 8, in another preferred configuration is now suggested that: * An arbitrary combination of the in [0012], [0013], [0014], [0015], [0016], [0017] described component and sub-system assemblies and operating methods and procedures are used.

Claims (16)

1. Stationary power generation system with integrated combustion engine characterized by the fact that the combustion engine is connected to a propulsion shaft which is connected to at least one consumer of mechanical energy, further characterized by the fact that a hydraulic pump and a hydraulic motor are connected to and acting on the same shaft, further characterized by the fact that the hydraulic pump and the hydraulic motor are connected to a hydraulic energy storage device, further characterized by the fact that the energy flow between hydraulic pump and hydraulic energy storage device can be controlled by a controller, further characterized by the fact that the energy flow between hydraulic energy storage device and hydraulic motor can be controlled by a controller.

2. The power generation system of claim 1 integrated into a mobile power generation system.

3. The power generation system of claim 1, claim 2, further comprising a solid fuel gasification unit to provide a fuel gas from such a gasifier to the internal combustion engine.

4. The power generation system of claim 3, further comprising a mechanical flywheel acting as energy storage device and replacing the hydraulic energy storage device, powered by a hydraulic motor acting on the shaft of the mechanical flywheel which is connected to and powered by a hydraulic pump, acting on and connected to the shaft between combustion engine and consumer, and acting on and driving a hydraulic pump which is connected to the shaft of the mechanical flywheel, powering a hydraulic motor which is connected to and acting on the shaft between combustion engine and consumer.

5. The power generation system of claim 4, further comprising that the motor, driving the mass flywheel can be an electric motor.

6. The power generation system of claim 4, claim 5 further comprising that the separated hydraulic pumps and motors can be single bidirectional acting devices.

7. The power generation system of claim 4, claim 5, claim 6, further comprising the fact that the hydraulic motor propelled by the energy of the hydraulic or I J / .,? mechanic energy storage device can act on a separate shaft to provide energy for a separate energy consumer.

8. The power generation system of claim 4, claim 5, claim 6, further comprising the fact that shaft providing the connection between combustion engine, hydraulic pump, hydraulic motor and consumer features a clutch do mechanically couple or decouple the combustion engine and the hydraulic pump from the hydraulic motor and the energy consumer, allowing the switch between same and different free variable revolution speed between combustion engine and driven consumer, allowing adjustment of engine rpm and torque to the consumers power requirements.

9. The power generation system of claim 8, further comprising a transmission, allowing the switch mode between same and different fixed speed ratio and free ratio revolution speed between combustion engine and consumer. 1O.The power generation system of claim 9, further comprising the hydraulic pump, the hydraulic energy storage device and the hydraulic motor acting as device to provide interruption free mechanical energy to the connected consumer when the clutch is disengaged to change the gear of the transmission.

11.A method and procedure characterized by the fact that the hydraulic pump with regard to hydraulic pump power requirement, the hydraulic motor with regard to hydraulic motor power output, and the energy stored in the hydraulic energy storage device and the combustion engine energy output are controlled independently.

12.A method and procedure using the hydraulic energy stored in the hydraulic energy device to crank and start the combustion engine by releasing the stored hydraulic energy through the hydraulic motor which is connected to and acting on the shaft between combustion engine and energy consumer.

13.A method and procedure to control the hydraulic pump power requirement and the hydraulic motor output power and the energy stored in the energy storage device and the combustion engine power output when the combustion engine is directly connected to the energy consumer on the same shaft, characterized by the fact that the amount of stored energy in the energy storage device which can be either a hydraulic energy storage device or a mechanical flywheel energy storage device, is depending on the ratio between momentary consumer power demand and theoretical possible maximum consumer power demand, characterized by the fact that the amount of stored energy in the energy storage device is further depending on the maximum possible dynamic of the power plant's combustion engine and attached fuel supply to increase the combustion engine's output power to the level of the dynamic power required by the attached consumer, allowing sufficient provision of the differencial energy between actual combustion engine output power and consumer required power by means of the hydraulic motor acting on the shaft between combustion engine and consumer.

14.Method and procedure of claim 13, further comprising that the amount of energy stored in the energy storage device is sufficient enough to allow solely energy provision to the attached consumer by means of the hydraulic pump without any additional power supply contribution from the combustion engine during transient power plant operational events such as gear changes, requiring temporary disengagement of the clutch acting from the shaft of the combustion engine on the shaft of the attached consumer or transmission.

15. Method and procedure of claim 13, claim 14, further comprising that a second consumer can be attached to the hydraulic device, acting independently from the first consumer which is attached to the combustion engine by the means of a shaft, or clutch and shaft, or clutch, transmission and shaft.

16. Method and procedure of claim 15, further comprising that a second consumer can be powered continuously by the hydraulic motor acting on the shaft of the second consumer.

17.Method and procedure of claim 15, claim 16, further comprising that the first and second consumer is a generator, generating electric energy, further comprising that generator 1 and generator 2 are connected to the same electrical distribution grind, further comprising that generator 1 is optimized with regard to cost, package and efficiency to provide the power plant system specific electric constant output power, further comprising that generator 2 acts as a dynamic source of additional electric energy to support additional short term electric loads by providing additional power supply by converting the stored hydraulic energy whereby generator 2 can be optimized with regard to cost, package and efficiency to provide the power plant system specific additional electric short term dynamic output power. IV I .N Definitions 1 Thermo-chemical fuel gas generator, gasifier 2 Fuel supply 3 Integrated heat exchanger 4 Connecting device 5 De-dusting device 6 Fuel gas cooler 7 Volumetric gas mixer 8 blower 9 Exhaust-gas heat exchanger 10 Engine coolant heat exchanger 11 Combustion engine 12 Supply assembly for the gaseous oxidizing agent 13 Generator 13a Generator 14 Starter device 15 External electric energy source 16 Heatexchanger 17 Electrical heating elements 18 Generator control logic 18a Generator control logic 19 External electrical connection 19a External electrical connection 20 In figure 1: shaft flange 20 Hydraulic pump 21 Hydraulic motor 22 Shaft 22a Shaft 23 Hydraulic pressurized storage device 24 Feed pipe 25 Return pipe 26 Valve / throttle 27 Valve / throttle 28 Clutch 29 Hydraulic Bypass 30 Feed pipe 31 Hydraulic motor 32 Mass flywheel energy storage device 33 flywheel 34 Hydraulic motor 35 Bearing 36 Return pipe 37 transmission