Section 4 Controls, Monitoring and Safety Systems

401. General requirements

1. For instrumentation and automation, including computer based control and monitoring, the require- ments in this Section are to apply in addition to those given in Pt 6 Ch 2 of the Rules for Steel Ships.

2. A local reading pressure gauge is to be fitted between the stop valve and the connection to shore at each bunker pipe.

3. Pressure gauges are to be fitted to FC fuel pump discharge lines and to the bunkering lines.

4. A bilge well in each tank room surrounding an independent FC fuel tank is to be provided with

both a level indicator and a temperature sensor. Alarm is to be given at high level

Temperature sensor for low temperature indication is to lead to automatic closing

valve.

in bilge well.

of main tank

5. The fuel cell and the FC fuel supply system are to be arranged for manual remote emergency stop from the following locations:

(1) the cargo control room (if any)

(2) navigation bridge

(3) engine control room

(4) fire control station (if any).

402. Control systems

1. If at least two control devices suited for the operation of FC systems are stipulated by the Pt 6, Ch 2, 201 of the Rules for Steel Ships, then they are to function independently of each other and are not to affect each other in the event of a failure.

2. The effects of the control actions must be indicated at the control panel. If control actions can be taken at several control units (control panels), the following requirements are to be observed:

(1) conflicting operator actions are to be prevented by means of suitable inter-locks

(2) the control panel which is currently active must be indicated appropriately

3. Control devices are to be designed in a way that no serious damage or loss of essential functions can occur in the case of faulty operating actions.

4. It is to be ensured that the fuel cells can be disconnected from the electrical load at any load condition.

5. Automatic control devices

(1) For the FC systems, regulating devices are to be provided to keep the process variables within the specified limits under normal operating conditions.

(2) The regulating behaviour is to cover the entire range of operation. Parameter changes which can be anticipated must be considered during the design phase.

(3) Faults in a regulating circuit are not to affect the proper functioning of other regulating circuits.

The power supply to the regulating circuits is to be monitored and an alarm must be generated on failure of the power supply.

(4) Regulating devices containing computers are to be designed in accordance with the require

ments in Pt 6, Ch 2, 201. 7 of the Rules for Steel Ships.

(5) Regulating devices for fuel cell systems are to be subjected to type approval.

403.

Monitoring Systems

1. FC fuel tank monitoring

(1) FC fuel tanks are to be monitored and protected against overfilling as required in Pt 7 Ch 5 1302 and 1303 of the Rules for Steel Ships.

(2) Each tank is to be monitored with at least one local indicating instrument for pressure and re-

mote pressure indication at the control position. The manometers and indicators are to be clearly marked with the highest and lowest pressure permitted in the tank. In addition to high pressure alarm, and if vacuum protection is required, low pressure alarm is to be provided on the bridge.

The alarms are to be activated before the set pressures of the safety valves are reached.

2. FC compressor monitoring

(1) FC fuel compressors are to be fitted with audible and visual alarms both on the bridge and in the engine room. As a minimum, the alarms are to be in relation to low gas input pressure, low gas output pressure, high gas output pressure, outlet temper(2) In addition, high pressure FC fuel compressors are to be stopped automatically in the event of:

(A) control air pressure loss

(B) high gas concentration in the compressor room

(C) automatic stop or emergency stop of FC fuel supply to fuel cell.

3. Fuel Cell monitoring

(1) The fuel cell is to be monitored to the extent necessary to avoid that the safety is impaired.

(2) A failure mode and effect analysis examining all possible faults affecting the fuel cell operation and safety is to be submitted. Based on the outcome of the analysis the extent of the monitor- ing and control is to be decided.

(A) As a minimum, the following items must typically be monitored:

(a) cell voltage

(b) cell voltage deviations

(c) exhaust gas temperature

(d) temperature in FC

(e) current level.

(B) Other typical monitoring that are to be considered:

(a) air flow

(b) air pressure

(c) cooling medium flow, pressure, temperature (if used)

(d) fuel flow

(e) fuel temperature

(f) fuel pressure

(g) gas detection in exhaust gas

(h) water system level

(i) water system pressure

(j) water system purity

(k) parameters necessary to monitor lifetime/deterioration.

404. Gas Detection

1. Permanently installed gas detectors are to be fitted in the tank room, in all ducts around gas pipes, in fuel cell spaces, compressor rooms, and other enclosed spaces containing FC fuel piping or other FC fuel equipment, but not including spaces where only completely ducted FC fuel pipes are present. Gas detection systems are to be installed for all types of flammable gases that may occur in the space.

2. The number of detectors in each space must be considered taking size, layout, fuel density in air and ventilation of the space into account.

3. The detection equipment is to be located where gas may accumulate and/or in the ventilation outlets. Gas dispersal analysis or a physical smoke test is to be used to find the best arrangement.

4. An audible and visible alarm is to be activated before the vapour concentration reaches 20% of the lower explosion limit(LEL). For ventilated ducts around FC fuel pipes the alarm limit can be set to 30% LEL. For reference, LEL is at 4% in air for hydrogen, at 5.3% in air for methane and at 1.7% in air for propane.

5. Audible and visible alarms from the gas detection equipment are to be located on the bridge and in the engine control room.

6. Continuous detection is required for FC fuel pipe ducts and fuel cell spaces kept gas safe by ven- tilation and fully welded fuel pipes(ESD-protected FC spaces).

405. Safety Functions of FC fuel Supply Systems

1. Each FC fuel storage tank is to be provided with a tank valve capable of being remote operated and is to be located as close to the tank outlet as possible.

2. Master fuel valve

(1) The main supply lines for FC fuel is to be equipped with a manually operated stop valve and an automatically operated "master fuel valve" coupled in series or a combined manually and au- tomatically operated stop valve. The valves are to be situated in the part of the piping that is outside the FC space.

(2) The master fuel valve is automatically to cut off the FC fuel supply as given in Table 3.1.

(3) The automatic master fuel valve is to be operable from a reasonable number of places in the FC space, from a suitable location outside the FC space and from the bridge.

3. Double block and bleed valve

Each FC fuel utilization unit is to be provided with a set of "double block and bleed" valves. These valves are to be arranged so that when automatic shut down is initiated as given in Table 3.1, this will cause the two FC fuel valves which are in series to close automatically and the vent valve to open automatically, and :

(1) Two of these valves are to be in series in the FC fuel pipe to the FC fuel consuming equipment. The third valve is to be in a pipe that vents to a safe location in the open air that portion of the FC fuel piping that is between the two valves in series. The function of one of the valves in series and the ventilation valve can be incorporated into one valve body, so ar- ranged that the flow to the FC fuel utilization unit will be blocked and the ventilation opened. The vent valve is to be connected to the piping to vent a gas to a safe location in the open air.

(2) The two block valves are to be of fail-to-close type, while the vent valve is to be fail-to- open.

4. In cases where the master fuel valve is automatically shut down, also a vent valve that will the pipe piece between the master fuel valve and the double block and bleed valve is to be opened.

vent

5. There are to be one manually operated shut down valve in the FC fuel supply line to each FC fuel utilization unit upstream of the double block and bleed valves to assure safe isolation dur ing maintenance on the gas utilization equipment.

6. In the main supply FC fuel line to each FC

space where fuel piping is not in a double duct,

an automatic excess flow shut off valve is to be fitted. The valve is to be adjusted to shut off

FC fuel supply in the event of rupture of the

FC fuel line. The valve is to be located as close

as possible to the point of entry of the FC fuel supply line into the FC space. The shutdown is to be time delayed to prevent shutdown due to transient load variations. The requirement of this Para. may be waived if the FC fuel pipes are located in protected locations, for instance

very high in the space or mechanically shielded.

7. If the FC fuel supply is shut off due to activation of an automatic valve, the FC fuel supply is not to be opened until the reason for the disconnection is ascertained and the necessary

precautions taken. A readily visible signboard giving instruction to this effect at the operating station for the shut-off valves in the FC fuel supply lines.

8. If a FC fuel leak leading to a FC fuel supply shut down occurs, the FC fuel be operated until the leak has been found and dealt with. Signboards to this placed in a prominent position in the machinery space.

is to be placed

supply is not to effect are to be

9. A signboard is to be fitted in the FC space stating that heavy lifting, maintenance or other ac tivities capable of potentially causing damage to the FC fuel pipes are not to be done when the fuel cell is running.

Table 3.1 Monitoring of FC fuel supply system to fuel cells (1/2)

Note :

1) Two independent gas detectors located close to each other are required for redundancy reasons. If the gas de- tector is of self monitoring type, the installation of a single gas detector can be permitted.

2) If the tank is supplying FC fuel to more than one fuel cell and the different supply pipes are completely sep-

arated and fitted in separate ducts and with the master valves fitted outside of each duct, only the master valve on the supply pipe leading into to the duct where gas or loss of ventilation is detected is to be closed.

3) If the FC fuel is supplied to more than one fuel cell and the different supply pipes are completely separated

and fitted in separate ducts and with the master valves fitted outside of each duct and outside of the FC space, only the master valve on the supply pipe leading into the duct where gas or loss of ventilation is de- tected is to be closed.

4) Only double block and bleed valves to close.

5) If the duct is protected by inert gas (See 107. 2) then loss of inert gas overpressure is to lead to the same ac tions as given in this table.