Secondary Fuel Supply Systems (SFSS)


Very large gas carriers with an Liquified Petroleum Gas (LPG) transport volume of 60-95,000 m³(upper limit is open) are increasingly being equipped with dual-fuel marine engines during both new builds and retrofits. Nowadays, the actual cargo, LPG, is often "tapped" as the main fuel, and the gas consumption is billed between the shipowner and the charterer after the cargo has been discharged.

The utilization of LPG as ship fuel presents particular challenges. LPG is a liquefied gas stored in huge transport tanks under pressure and deep- cooled conditions. Transporting LPG towards the engine and its injection system the pressure needs to be increased by around 55bar. The engine requires an LPG inlet pressure of above 55 bar to be safely operated.

These requirements must be managed across a wide temperature range, from -45°C in the lower deck transport tank or +50°C in the upper deck or service tank. Additionally, the vapor pressure of LPG must be controlled. It is crucial to stabilize pressure and temperature according to consumption while ensuring a low inlet height, especially when drawing LPG from upper deck gas tanks in equilibrium. Continuous conveying of very low-viscosity media like LPG without interruption of flow from the tank to the main engine also poses a challenge.

Solution of the Side Channel Pump SHPmarine

The SERO side channel pump SHPmarine is capable of handling relatively low flows of LPG at high differential pressures, which is crucial for boosting LPG pressure to 55 bar. It can achieve a delivery head of up to 1,200m, meeting the requirements of LPG propulsion.

Typically, two SHPmarine pumps are cascaded and integrated into the Secondary Fuel Supply System with an intermediate service tank to control pressure and LPG temperature depending on engine load and consumption. Another advantage of the SHPmarine is its ability to control vapor pressure over a wide temperature range while requiring a very low NPSH of just a few centimeters.

This is  particularly  ad- vantageous using LPG from upper deck gas tanks, as it allows  for a  low-rise and compact  installation without requiring a high super- structure. The SHPmarine side channel pumps deliver LPG continuously and without pulsations. Their  unique pumping principle eliminates pressure fluctuations, ensuring the stability  of     the entire system. Additionally the SHPmarine’s unique conveying principle does not cause any pressure fluctuations, which ensures the stability of the entire system.

Therefore, the SHPmarine provides a comprehensive solution for the challenging use of LPG as a marine fuel - safe and efficient-, especially under the extreme conditions at sea.

The SHPmarine is the first of its kind to receive type approval from different class societies, such as DNV (Det Norske Veritas).

Technical Details
Pump:SHP High Pressure Pump
Liquid:Commercial LPG (Propan, Butan)
Flowrate:3,5 - 5 m³/h, depending on consumption
Pressure:55 bar, constant and pulsation-free
Temperature:-45 °C - +50 °C
Viscosity:0,3 - 0,1 mPas
Rotational speed:max. 3600 rpm, VFD (variable frequency drive) capability

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