Energy Analysis of Main Propulsion Steam Turbine from Conventional LNG Carrier at Three Different Loads

Mrzljak, Vedran; Poljak, Igor

doi:10.17818/nm/2019/1.2

Cited by 17 publications

(17 citation statements)

References 35 publications

(43 reference statements)

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“…Other marine propulsion systems are significantly less represented in the entire worldwide fleet. As for example, steam propulsion systems are still dominantly represented in the propulsion of LNG (Liquefied Natural Gas) carriers due to the specificity of its operations and transported cargo [8,9]. However, internal combustion dual-fuel en-gines each day takes stronger and stronger impact also in LNG carriers propulsion systems, therefore it can be expected that in the near future it will overcome traditional steam propulsion [10,11].…”

Section: Introductionmentioning

confidence: 99%

Exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system

et al. 2020

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This paper presents an exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system. Based on the operating parameters obtained in system exploitation, it is performed analysis of each system component individually, as well as analysis of the whole observed system. While observing all heat exchangers it is found that combustion gases-CO2 heat exchangers have the lowest exergy destructions and the highest exergy efficiencies (higher than 92%). The lowest exergy efficiency of all heat exchangers is detected in Cooler (51.84%). Observed system is composed of two gas turbines and two compressors. The analysis allows detection of dominant mechanical power producer and the dominant mechanical power consumer. It is also found that the turbines from the observed system have much higher exergy efficiencies in comparison to compressors (exergy efficiency of both turbines is higher than 94%, while exergy efficiency of both compressors did not exceed 87%). The whole observed waste heat recovery system has exergy destruction equal to 6270.73 kW, while the exergy efficiency of the whole system is equal to 64.12% at the selected ambient state. Useful mechanical power produced by the whole system and used for electrical generator drive equals 11204.80 kW. The obtained high exergy efficiency of the whole observed system proves its application on-board ships.

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Section: Introductionmentioning

confidence: 99%

Exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system

et al. 2020

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“…A simplified scheme of the entire marine steam propulsion plant from the commercial LNG carrier is presented in Fig. 2 [17]. The majority of marine steam power plant components are the same as in land-based steam power plants [18,19], but the operation of a marine steam plant must be much more dynamic.…”

Section: Description Of the Analyzed Marine Tgst And The Steam Power mentioning

confidence: 99%

Energy Loss Analysis at the Gland Seals of a Marine Turbo-Generator Steam Turbine

Kocijel

Poljak

Mrzljak

et al. 2020

Teh. glas. (Online)

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The paper presents an analysis of marine Turbo-Generator Steam Turbine (TGST) energy losses at turbine gland seals. The analyzed TGST is one of two identical Turbo-Generator Steam Turbines mounted in the steam propulsion plant of a commercial LNG carrier. Research is based on the TGST measurement data obtained during exploitation at three different loads. The turbine front gland seal is the most important element which defines TGST operating parameters, energy losses and energy efficiencies. The front gland seal should have as many chambers as possible in order to minimize the leaked steam mass flow rate, which will result in a turbine energy losses' decrease and in an increase in energy efficiency. The steam mass flow rate leakage through the TGST rear gland seal has a low or negligible influence on turbine operating parameters, energy losses and energy efficiencies. The highest turbine energy efficiencies are noted at a high load -on which TGST operation is preferable.

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“…Two-stage compressor is evaluated for energy efficiency according to recommendations in the following literature [ 44 , 45 , 46 , 47 , 48 ]. Energy efficiency formulation with referring to Figure 1 is given below.…”

Section: Thermodynamic Efficiency Analysismentioning

confidence: 99%

Energy and Exergy Evaluation of a Two-Stage Axial Vapour Compressor on the LNG Carrier

Poljak

Orović

Mrzljak

et al. 2020

Entropy

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Data from a two-stage axial vapor cryogenic compressor on the dual-fuel diesel–electric (DFDE) liquefied natural gas (LNG) carrier were measured and analyzed to investigate compressor energy and exergy efficiency in real exploitation conditions. The running parameters of the two-stage compressor were collected while changing the main propeller shafts rpm. As the compressor supply of vaporized gas to the main engines increases, so does the load and rpm in propulsion electric motors, and vice versa. The results show that when the main engine load varied from 46 to 56 rpm at main propulsion shafts increased mass flow rate of vaporized LNG at a two-stage compressor has an influence on compressor performance. Compressor average energy efficiency is around 50%, while the exergy efficiency of the compressor is significantly lower in all measured ranges and on average is around 34%. The change in the ambient temperature from 0 to 50 °C also influences the compressor’s exergy efficiency. Higher exergy efficiency is achieved at lower ambient temperatures. As temperature increases, overall compressor exergy efficiency decreases by about 7% on average over the whole analyzed range. The proposed new concept of energy-saving and increasing the compressor efficiency based on pre-cooling of the compressor second stage is also analyzed. The temperature at the second stage was varied in the range from 0 to −50 °C, which results in power savings up to 26 kW for optimal running regimes.

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Energy Analysis of Main Propulsion Steam Turbine from Conventional LNG Carrier at Three Different Loads

Cited by 17 publications

References 35 publications

Exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system

Exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system

Energy Loss Analysis at the Gland Seals of a Marine Turbo-Generator Steam Turbine

Energy and Exergy Evaluation of a Two-Stage Axial Vapour Compressor on the LNG Carrier

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