10.1 Goal
10.1.1 The goal of this chapter is to provide safe and reliable delivery of
mechanical, electrical or thermal energy.
10.2 Functional requirements
This chapter is related to functional requirements in 3.2.1, 3.2.11, 3.2.13, 3.2.16
and 3.2.17. In particular the following apply:
- .1 the exhaust systems shall be configured to prevent any accumulation of
un-burnt gaseous fuel;
- .2 unless designed with the strength to withstand the worst case over pressure
due to ignited gas leaks, engine components or systems containing or likely to
contain an ignitable gas and air mixture shall be fitted with suitable pressure
relief systems. Dependent on the particular engine design this may include the
air inlet manifolds and scavenge spaces;
- .3 the explosion venting shall be led away from where personnel may normally be
present; and
- .4 all gas consumers shall have a separate exhaust system.
10.3 Regulations for internal
combustion engines of piston type
10.3.1 General
10.3.1.1 The exhaust system shall be equipped with explosion relief
ventilation sufficiently dimensioned to prevent excessive explosion pressures in the
event of ignition failure of one cylinder followed by ignition of the unburned gas
in the system.
10.3.1.2 For engines where the space below the piston is in direct
communication with the crankcase a detailed evaluation regarding the hazard
potential of fuel gas accumulation in the crankcase shall be carried out and
reflected in the safety concept of the engine.
10.3.1.3 Each engine other than two-stroke crosshead diesel engines
shall be fitted with vent systems independent of other engines for crankcases and
sumps.
10.3.1.4 Where gas can leak directly into the auxiliary system medium
(lubricating oil, cooling water), an appropriate means shall be fitted after the
engine outlet to extract gas in order to prevent gas dispersion. The gas extracted
from auxiliary systems media shall be vented to a safe location in the atmosphere.
10.3.1.5 For engines fitted with ignition systems, prior to admission of
gas fuel, correct operation of the ignition system on each unit shall be
verified.
10.3.1.6 A means shall be provided to monitor and detect poor combustion
or misfiring. In the event that it is detected, gas operation may be allowed
provided that the gas supply to the concerned cylinder is shut off and provided that
the operation of the engine with one cylinder cut-off is acceptable with respects to
torsional vibrations.
10.3.1.7 For engines starting on fuels covered by this Code, if
combustion has not been detected by the engine monitoring system within an engine
specific time after the opening of the fuel supply valve, the fuel supply valve
shall be automatically shut off. Means to ensure that any unburnt fuel mixture is
purged away from the exhaust system shall be provided.
10.3.2 Regulations for dual fuel engines
10.3.2.1 In case of shutoff of the gas fuel supply, the engines shall be
capable of continuous operation by oil fuel only without interruption.
10.3.2.2 An automatic system shall be fitted to change over from gas fuel
operation to oil fuel operation and vice versa with minimum fluctuation of the
engine power. Acceptable reliability shall be demonstrated through testing. In the
case of unstable operation on engines when gas firing, the engine shall
automatically change to oil fuel mode. Manual activation of gas system shutdown
shall always be possible.
10.3.2.3 In case of a normal stop or an emergency shutdown, the gas fuel
supply shall be shut off not later than the ignition source. It shall not be
possible to shut off the ignition source without first or simultaneously closing the
gas supply to each cylinder or to the complete engine.
10.3.3 Regulations for gas-only engines
In case of a normal stop or an emergency shutdown, the gas fuel supply shall be shut
off not later than the ignition source. It shall not be possible to shut off the
ignition source without first or simultaneously closing the gas supply to each
cylinder or to the complete engine.
10.3.4 Regulations for multi-fuel engines
10.3.4.1 In case of shutoff of one fuel supply, the engines shall be capable of
continuous operation by an alternative fuel with minimum fluctuation of the engine
power.
10.3.4.2 An automatic system shall be fitted to change over from one fuel operation
to an alternative fuel operation with minimum fluctuation of the engine power.
Acceptable reliability shall be demonstrated through testing. In the case of
unstable operation on an engine when using a particular fuel, the engine shall
automatically change to an alternative fuel mode. Manual activation shall always be
possible.
|
|
GAS ONLY
|
DUAL FUEL
|
MULTI FUEL
|
| IGNITION MEDIUM
|
Spark
|
Pilot fuel
|
Pilot fuel
|
N/A
|
| MAIN FUEL
|
Gas
|
Gas
|
Gas and/ or Oil fuel
|
Gas and/ or Liquid
|
10.4 Regulations for main and
auxiliary boilers
10.4.1 Each boiler shall have a dedicated forced draught system. A
crossover between boiler force draught systems may be fitted for emergency use
providing that any relevant safety functions are maintained.
10.4.2 Combustion chambers and uptakes of boilers shall be designed to
prevent any accumulation of gaseous fuel.
10.4.3 Burners shall be designed to maintain stable combustion under all
firing conditions.
10.4.4 On main/propulsion boilers an automatic system shall be provided
to change from gas fuel operation to oil fuel operation without interruption of
boiler firing.
10.4.5 Gas nozzles and the burner control system shall be configured such
that gas fuel can only be ignited by an established oil fuel flame, unless the
boiler and combustion equipment is designed and approved by the Administration to
light on gas fuel.
10.4.6 There shall be arrangements to ensure that gas fuel flow to the
burner is automatically cut off unless satisfactory ignition has been established
and maintained.
10.4.7 On the fuel pipe of each gas burner a manually operated shutoff
valve shall be fitted.
10.4.8 Provisions shall be made for automatically purging the gas supply piping to
the burners, by means of an inert gas, after the extinguishing of these burners.
10.4.9 The automatic fuel changeover system required by 10.4.4 shall be monitored
with alarms to ensure continuous availability.
10.4.10 Arrangements shall be made that, in case of flame failure of all operating
burners, the combustion chambers of the boilers are automatically purged before
relighting.
10.4.11 Arrangements shall be made to enable the boilers purging sequence to be
manually activated.
10.5 Regulations for gas
turbines
10.5.1 Unless designed with the strength to withstand the worst case over
pressure due to ignited gas leaks, pressure relief systems shall be suitably
designed and fitted to the exhaust system, taking into consideration of explosions
due to gas leaks. Pressure relief systems within the exhaust uptakes shall be led to
a safe location, away from personnel.
10.5.2 The gas turbine may be fitted in a gas-tight enclosure arranged in accordance
with the ESD principle outlined in 5.6 and 9.7, however a pressure above 1.0 MPa in
the gas supply piping may be accepted within this enclosure.
10.5.3 Gas detection systems and shutdown functions shall be as outlined for ESD
protected machinery spaces.
10.5.4 Ventilation for the enclosure shall be as outlined in chapter 13 for ESD
protected machinery spaces, but shall in addition be arranged with full redundancy
(2 x 100% capacity fans from different electrical circuits).
10.5.5 For other than single fuel gas turbines, an automatic system shall be fitted
to change over easily and quickly from gas fuel operation to oil fuel operation and
vice-versa with minimum fluctuation of the engine power.
10.5.6 Means shall be provided to monitor and detect poor combustion that may lead to
unburnt fuel gas in the exhaust system during operation. In the event that it is
detected, the fuel gas supply shall be shutdown.
10.5.7 Each turbine shall be fitted with an automatic shutdown device for high
exhaust temperatures.