A microgrid is a distribution network that incorporates a variety of distributed energy resources (DER) that can be optimized and aggregated into a single system. The integrated system can balance loads and generation with or without energy storage and is capable of islanding whether connected or not connected to a traditional utility power grid. Distributed energy resources typically include other dual-mode microturbines, reciprocating engines, solar photovoltaic (PV), wind turbines, fuel cells and battery storage. Microgrids can be connected to larger electricity grids, and in the event of a widespread outage, can disconnect from the main grid to operate independently and supply electricity to homes and businesses that are connected to the microgrid’s electricity network.
The microturbines are ideally suited for controlled, decentralized energy supply due to the small power units and the excellent operating characteristics (almost constant efficiency over a wide load spectrum). By using the microturbine in cogeneration, overall efficiencies of up to 86% can be achieved for standard heating systems with temperatures of 60/80°C. Higher efficiencies are possible by optimizing the heat exchanger to the application. For example, we offer a heat exchanger with a thermal capacity of 75kW, achieving an exhaust gas temperature of 65°C. Another possibility results from lowering the operating temperatures or the flow rates, if the heat transfer medium temperature is lowered. Since the microturbine is operated with a lambda of 6-9, the exhaust gas dew point is also very low, so that theoretically exhaust gas temperatures of about 40°C after the heat exchanger are possible without any problems.
The microturbine-specific exhaust gas characteristic with constantly occurring heat at a high temperature level (approx. 300°C) in only one exhaust gas stream is a decisive advantage in direct exhaust gas utilization compared to reciprocating engine-based combined heat and power facilities. The use of oil-free microturbine exhaust gas with oxygen contents of 17 to 18% by volume and very low pollutant concentrations is unproblematic.
The use of microturbines for drying is already being applied in many different industries. These include, among others, the stone and earth industry, paper/cardboard industry, feed industry,...
Another field of application is steam generation, which can be realized with exhaust gas heat exchangers due to the high exhaust gas temperature of the microturbines.
In the field of steam generation by microturbines we closely cooperate with partners like Saacke, Hagelschuer (www.dampfkessel.com) or also with the company SKS (www.sks-systems.com). Below you will find an information sheet of a Saacke burner specially developed for the turbines.
Examples of applications in industry include food manufacturers, pet food producers, industrial laundries, breweries and chemical manufacturers.
The advantage of the high exhaust gas temperature is also evident in the connection with an absorption chiller: Hot water temperatures of 80-90°C are necessary for this. The advantage of connecting an absorption refrigeration facility is the increase in the number of annual operating hours of the CHP unit. Thus, the microturbine can be operated in summer as well as in winter with high utilization rates. Such a facility is thus suitable for the base load supply of buildings with a constant demand for electricity, heating and cooling.
The microturbine thus offers the possibility of ensuring the total energy supply of a building by simply coupling an absorption chiller. Such an installation achieves efficiencies of up to 85% and is particularly suitable in:
Cogeneration is based on the simultaneous generation of mechanical energy, which is usually converted directly into electricity, and heat, which can be used directly for refrigeration using sorption technology.
Absorption refrigeration systems are based on a technology introduced by Albert Einstein in 1926. It uses a refrigeration cycle in which the changes of state of the refrigerant water and the absorber lithium bromide reach the temperature parameters of conventional chillers.
Century absorption chillers are LiBr units capable of producing refrigeration down to 6°C and are well suited for use in conjunction with microturbines.
Whether used individually or in conjunction with a Capstone microturbine, Century absorption chillers feature:
The Capstone microturbines are operated with
Due to its simple design, the turbine is also particularly suitable for use with renewable gases, such as
In the combustion of biogas, the content of hydrogen sulfide (H2S) is a decisive factor for the service life of the engines or their maintenance requirements. The methane in the biogas reacts in the engine to form water vapor, among other things. This in turn combines with H2S from the biogas to form sulfuric acid (H2SO4). The sulfuric acid is absorbed by the oil film of the cylinder walls and enters the oil circuit. As the bearings are lubricated with this oil, the H2SO4 reaches the bearing surfaces, which suffer faster wear as a result of this chemical load.
Due to their compact design (with integration of compressor, turbine, combustion chamber, recuperator and generator), microturbines are ideally suited for use with lean gases. The only moving component is the high-speed rotor, which integrates the compressor and turbine impellers as well as the generator impeller. Furthermore, no lubricant is required in the Capstone turbine because the rotor is air-bearing. This avoids the corrosion problems associated with internal combustion engines caused by H2S components in the biogas. The manufacturer Capstone states that up to 7 vol-% H2S can be tolerated by the MicroTurbine. In this way, pressures are reduced to a minimum and the service life of the machine is increased. Thus, a turbine achieves a service life of approximately 80,000h compared to 50,000h for engines. When used with biogas, a service life of 40,000h is assumed even for motors.
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