GAS BURNING INTERNAL COMBUSTION ENGINE INSTALLATIONS

STANDARD FOR CERTIFICATION No. 2.11 GAS BURNING INTERNAL COMBUSTION ENGINE INSTALLATIONS JANUARY 1999 DET NORSKE VERITAS Veritasveien 1, N-1322 Høvi...
Author: Josephine Pitts
1 downloads 0 Views 165KB Size
STANDARD FOR CERTIFICATION No. 2.11

GAS BURNING INTERNAL COMBUSTION ENGINE INSTALLATIONS JANUARY 1999

DET NORSKE VERITAS Veritasveien 1, N-1322 Høvik, Norway Tel.: +47 67 57 99 00 Fax: +47 67 57 99 11

FOREWORD DET NORSKE VERITAS is an autonomous and independent Foundation with the objective of safeguarding life, property and the environment at sea and ashore. DET NORSKE VERITAS AS is a fully owned subsidiary Society of the Foundation. It undertakes classification and certification of ships, mobile offshore units, fixed offshore structures, facilities and systems for shipping and other industries. The Society also carries out research and development associated with these functions. DET NORSKE VERITAS operates a worldwide network of survey stations and is authorised by more than 120 national administrations to carry out surveys and, in most cases, issue certificates on their behalf. Standards for Certification Standards for Certification (previously Certification Notes) are publications that contain principles, acceptance criteria and practical information related to the Society's consideration of objects, personnel, organisations, services and operations. Standards for Certification also apply as the basis for the issue of certificates and/or declarations that may not necessarily be related to classification. A list of Standards for Certification is found in the latest edition of the Introduction booklets to the ”Rules for Classification of Ships”, the ”Rules for Classification of Mobile Offshore Units” and the ”Rules for Classification of High Speed and Light Craft”. In “Rules for Classification of Fixed Offshore Installations”, only those Standards for Certification that are relevant for this type of structure, have been listed. The list of Standards for Certification is also included in the current “Classification Services – Publications” issued by the Society, which is available on request. All publications may be ordered from the Society’s Web site http://exchange.dnv.com. Changes: − −

This Standard for Certification replace Certification Notes 2.11 from May 1995 A reference to Classification Note 42.1 has been added in item 2.3.6.

© Det Norske Veritas AS 1999 Data processed and typeset by Division Technology and Products, Det Norske Veritas AS Printed in Norway by Det Norske Veritas AS 26/11/2002 1:41 PM - Cer0211.doc

1.99.2000 If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compensation shall never exceed USD 2 million. In this provision “Det Norske Veritas” shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalf of Det Norske Veritas.

CONTENTS 1. 1.1 1.2 1.3 1.4 2. 2.1 2.2 2.3 2.4

General .....................................................................4 Application ................................................................4 Scope .........................................................................4 Certification ...............................................................4 Plans and particulars ..................................................4 Requirements for Engines Suitable for use in Gas Safe Rooms ...............................................................4 Functional requirements for dual fuel diesel engines 4 Functional requirements for gas-only engines ...........5 Design of on-engines gas piping...............................5 Monitoring .................................................................5

3. 4. 4.1 4.2 4.3 5. 5.1 5.2 5.3

Requirements for Low Pressure Gas Burning Engines for use in Potentially Gas Dangerous Rooms....................................................................... 7 Requirements for Land Based Installations with Engine Room being a Gas Safe Space ................... 7 Arrangement.............................................................. 7 Gas supply lines ........................................................ 7 Fuel gas compression ................................................ 8 Requirements for Land Based Installations with Engine Room being potentially Gas Dangerous ... 8 Gas supply................................................................. 8 Monitoring system .................................................... 8 Electrical Installations ............................................... 8

DET NORSKE VERITAS

4

Standard for Certification No. 2.11 January 1999

Preamble

1.3 Certification

The only internationally accepted safety standard for using gas as fuel is found in the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk, IGC-Code. Chapter 16 of this Code contains provisions for using boil-off gas from LNG cargoes as fuel for boilers, gas turbines and internal combustion engines.

1.3.1

In response to the growing need for using gas as fuel also in other types of ships than LNG carriers, this Standard for Certification gives requirements for gas burning internal combustion engines for use onboard ships in general. The requirements are based on the safety philosophy and safety principles found in the IGC Code and are to be regarded as supplementary requirements. The Standard for Certification gives in addition technical standards for gas burning internal combustion engines used in land or offshore installations not covered by the Rules for Classification of Ships. These standards are mainly based on the same safety philosophy and principles as those in the IGC Code. For high pressure dual fuel engines the standards for land/offshore installations are identical to the standards required for ship installations. For low pressure type gas burning internal combustion engines, the Standard for Certification offers an alternative to the complete double walled gas piping otherwise required. With this alternative, safety is partly based on automatic shut down and de-energising of all possible ignition sources in the event of gas being detected in the engine room.

1. General 1.1 Application This Standard for Certification applies to dual fuel diesel engines utilising high pressure gas injection (in gaseous or liquefied state) simultaneously with injection of the liquid fuel, low pressure dual fuel engines or low pressure gas-only internal combustion engines.

1.2 Scope

Dual fuel or gas-only engines satisfying Section 2 of this standard as well as the Rules Pt.4 Ch.2 may be certified for use onboard ships or for use in landbased installations. For the instrumentation and control equipment covered by the certification, the requirements of the Rules Pt.4 Ch.5 apply. 1.3.2 Low pressure dual fuel diesel or gas-only engines satisfying the requirements of Section 3 of this standard may be certified for use in landbased installations with potentially gas dangerous engine rooms subject to the requirements of Section 5.

1.4 Plans and particulars 1.4.1 The following plans and particulars are to be submitted for approval: − documentation requirements for the engine as specified in the Rules Pt.4 Ch.2 − gas piping − pressure vessels and heat exchangers − gas compression and gas treatment installations − control and instrumentation systems − ignition and starting system for the engine. 1.4.2 The following information shall be submitted for reference: − arrangement plan for the engine room − description of control functions in the form of logic diagrams − system description, computer software (if applicable) − failure mode/failure effect analysis (FMEA) related to gas operation of engine.

2. Requirements for Engines Suitable for use in Gas Safe Rooms

Section 2 of this standard gives requirements to the dual fuel or gas-only engine itself suitable for use onboard ships or in land installations with gas safe engine rooms complying with Section 4. These requirements are complementary to the requirements in the Rules for Classification of Ships Pt.4 Ch.2.

2.1 Functional requirements for dual fuel diesel engines

Section 3 of this standard gives requirements for gas-only or low pressure dual fuel engine itself suitable for installation in potentially gas dangerous spaces on land complying with Section 5.

Gas injection is not to be possible without a corresponding pilot oil injection.

2.1.1 Start, normal stop and low power operation is to be on oil fuel only.

2.1.2 Change over to and from gas fuel operation is only to be possible at a power level where it can be done with acceptable reliability as demonstrated through testing.

DET NORSKE VERITAS

Standard for Certification- No. 2.11

5

January 1999 On completion of preparations for change over to gas operation including checks of all essential conditions for change over, the change over process itself is to be automatic. On power reduction the change over to oil fuel is to be automatic (compressor and auxiliaries may continue to run unloaded). 2.1.3 On normal shut-down as well as emergency shut-down, gas fuel supply is to be shut off not later than simultaneously with the oil fuel. Shut off of the gas fuel is not to be dependent on the shut off of the oil fuel. 2.1.4 Firing of the gas-air mixture in the cylinders is to be initiated by injection of pilot fuel. The amount of pilot fuel fed to each cylinder is to be sufficient to ensure a positive ignition of the gas mixture. It is not to be possible to shut off the supply pilot fuel without first or simultaneously closing the gas supply to each cylinder or to the complete engine.

2.2 Functional requirements for gas-only engines 2.2.1 The starting sequence must be such that fuel gas is not admitted to the cylinders until ignition is activated and the engine has reached a minimum rotational speed. 2.2.2 If ignition has not been detected by the engine monitoring system within 10 s after opening of gas injection valve the gas supply is to be automatically shut off and the starting sequence terminated. 2.2.3 When restarting after a failed start attempt admission of fuel gas to the cylinders is not to be possible before the exhaust gas system has been purged with a volume of air at least equal to 3 times the volume of the exhaust gas system before the turbocharger(s). Purging may be carried out through e.g. running the engine on starting air for a predetermined number of revolutions.

2.3 Design of on-engines gas piping 2.3.1 The fuel gas lines must be completely jacketed, i.e. enclosed in a gas tight duct. The ducting must have sufficient strength to withstand the pressure encountered in case of rupture of the gas pipe at full pressure.

2.3.2 The connecting of the pressure gas lines with ducting to the gas injection valves must be so as to provide complete enclosure by the ducting. The arrangement must facilitate replacement/overhaul of injection valves, cylinder covers and components in the gas supply system. 2.3.3 The gas is to be fed directly to each cylinder via a special gas valve. For small engines gas feed to a common manifold may be considered. 2.3.4 The exhaust receiver is to be equipped with explosion relief vent sufficient dimensioned to prevent excessive explosion pressure in the event of ignition failure of one cylinder followed by ignition of the unburned gas in the receiver. The explosion venting is to be led outside the machinery space. As an alternative to explosion venting, documentation showing that the exhaust system has sufficient strength to contain the worst-case explosion without damage may be accepted. 2.3.5 For gas-only engines where gas is supplied in a mixture with air via a common inlet manifold, explosion relief venting is to be arranged, alternatively the manifold must be of sufficient strength to withstand an explosion. 2.3.6 Regarding arrangement of gas supply lines, ventilation of ducting, arrangement of valves and gas compression/gas treatment arrangements see Section 3 for landbased installations and Classification Note 42.1 for shipboard installations.

2.4 Monitoring 2.4.1 A failure mode and effect analysis (FMEA) examining all possible faults affecting the combustion process shall be submitted. Details of required monitoring will be determined based on the outcome of the analysis. However, Table 1 may serve as guidance.

DET NORSKE VERITAS

6

Standard for Certification No. 2.11 January 1999 Alarm and safety action (stated by an x)

Item Alarm

Automatic start of standby pump with alarm 1)

Comments

Temperature, high Exhaust gas, outlet Temperature deviation from each cylinder average, large

x

Automatic stop of gas supply

Ignition failure each cylinder

x

Automatic stop of gas supply

Gas injection valve sealing oil pressure low

x

High pressure injection only.

Lubricating oil inlet to engine 2)

Cylinder lubrication 3)

Temperature, high

x

Pressure, low

x

Pressure, low x

Filter differential pressure, high

x

Flow, low

Piston cooling medium Fuel valve cooling medium 4)

Fuel oil inlet to engine 4)

Pressure, low Temperature, high

Engine shut-down

x x x

Flow from each piston, low

x

Pressure, low

x

Pressure, low Temperature, high

x

Pressure, low

x

Pressure, low Temperature, high

x

Temperature or viscosity of heavy oil, high

x

Temperature or viscosity of heavy oil, low

x

Pressure, low

x

Pressure, low

x

Not required if main pump is engine driven Outlet each cylinder if individual stop valves are fitted for the cylinder jackets

x

Not required if main pump is engine driven

x

Not required if main pump is engine driven

Inlet high pressure pump x

Scavenge air belt, each cylinder 5)

Temperature, high

Crankcase protection

Bearing temperature or oil mist concentration

x

Gas fuel knockout drums

Liquid level, high

x

1) 2) 3) 4) 5)

Independent of safety system x

Pressure, low

Pressure, low Cylinder cooling medium

x

Not required if main pump is engine driven

x

Only for propulsion engines All separate systems At least one measuring point for each lubricator unit Dual fuel engines only For detection of fire (2-stroke engines)

Table 1 Monitoring of dual fuel diesel or gas-only engines

DET NORSKE VERITAS

Engine shut-down

Standard for Certification- No. 2.11

7

January 1999

3. Requirements for Low Pressure Gas Burning Engines for use in Potentially Gas Dangerous Rooms The requirements in 2.2, 2.3 and 2.4 apply except for the requirements of jacketed fuel gas lines given in 2.3.1 and 2.3.2. The fuel lines shall have a design pressure of at least 10 bar.

4. Requirements for Land Based Installations with Engine Room being a Gas Safe Space 4.1 Arrangement

The outlets are to be located in an area with no risk of ignition of any explosive gas mixture. 4.2.2 The ventilation of the duct spaces is to be in operation whenever there is fuel gas in the supply line. The duct outlet is to be continuously monitored for combustible gases. 4.2.3 The gas supply lines are to be designed for a pressure equal to the highest occurring transient or pulsatory pressure, but not less than 1.5 times the normal working pressure. Conceivable external loading or exposure due to vibration or other is not to damage the pipe. The pipe is to be pressure tested to minimum 1.5 times the working pressure.

4.1.1

4.2.4

The compressor and any other equipment for "treatment" of the gas (cooler, heater, etc.) are to be located in a space separate from the engine room.

The duct is to be designed to withstand the destructive forces that may follow a failure or fracture of the actual fuel line in such a way that its containment function is maintained.

The space will normally be considered gas dangerous and is to be fitted out accordingly.

4.2.5

Electric equipment is to be as required for gas dangerous spaces (flame proof or pressurised, intrinsically safe etc.).

There is to be an inert gas system enabling gas pipes and duct space and hood/casing space to be effectively gas-freed and inerted (e.g. prior to maintenance). 4.2.6

4.1.2 The compressor room and the engine room are to have separate ventilation systems. If access doors are fitted between the two spaces, the compressor room shall have underpressure ventilation and the engine room overpressure ventilation. Doors between the spaces are to be self closing with closing in the direction assisted by the pressure differential. 4.1.3 The ventilation capacity of the compressor room should correspond to 30 air changes per hour. The ventilation of the engine room should be sufficient for supply of the required combustion air and provide a minimum of 8 airchanges per hour.

4.2 Gas supply lines 4.2.1 The gas supply lines from the compressor space to the engine is to be as simple and short as is practical. They are to be all welded. They are to be fitted with an outer gastight shielding duct, that is to prevent gas from any potential leak from spreading into the engine room. The duct space is to be ventilated with a minimum of 10 air changes per hour. The duct pressure is to be maintained below ambient atmospheric pressure. The ventilating fans are to be located outside the engine room.

The compressor room is to be provided with hydrocarbon gas detection system. Alarm is to be given at a gas concentration exceeding 30% of lower flammable limit (LFL). 4.2.7 The main supply lines for gas are to be equipped with two automatically operated shut off valves in series, at least one of which is to be a quick-closing valve. The quick closing valve is to be situated in the part of the piping which is outside the engine room. The shut off valves are to cut off the gas supply at: − abnormal pressure variations in the supply line − fire alarm − gas concentration of 60 % or more of lower explosion limit in the vented duct − loss of duct ventilation − emergency shut-down of the engine. The quick-closing valve is to be manually operable from one or more locations near the engine, from room outside the engine room and from the control room. 4.2.8 The gas line between the two shut off valves is to be provided with a vent line with a valve opening automatically in case of closing of both shut off valves. The vent line is to exhaust to a safe location.

DET NORSKE VERITAS

8

Standard for Certification No. 2.11 January 1999

4.2.9

5.1.5

Opening of gas supply valve to the engine room is not to be possible unless the mechanical ventilation of the engine room is in operation.

If the gas supply installation comprises a gas compression or gas treatment module the requirements in 4.3.2 apply as far as applicable.

4.3 Fuel gas compression

5.2 Monitoring system

4.3.1

5.2.1

The fuel gas compressor is to be fitted with accessories and instrumentation necessary for efficient and reliable function.

The engine room is to be provided with a hydrocarbon gas detection system. The system is to release an alarm if the gas concentration exceeds 30% of the lower flammable limit (LFL). If the gas concentration exceeds 60% LFL, the following actions to be activated automatically:

4.3.2 The monitoring system should include: Alarm Gas heater outlet, temperature high

X

Gas compressor outlet, temperature, high

X

Gas compressor inlet, pressure, low

X

Gas compressor outlet, pressure, high

X

Gas compressor outlet, pressure, low

X

Control system failure

X

Sealing gas pressure, low

X

Lubrication oil pressure, low

X

Lubrication oil temperature, high

X

Master gas valve close

X

Automatic stop X

− shut-down of the gas engine − shut off of gas supply to the engine room, venting of gas lines to a safe location outside the engine room − disconnecting electrical supply to all electrical installation in the engine room not certified safe for a hydrocarbon gas atmosphere. 5.2.2 Shut-down of the gas engine with closing of gas supply and venting, of gas lines is to be initiated by:

X

5. Requirements for Land Based Installations with Engine Room being potentially Gas Dangerous 5.1 Gas supply

− fire alarm − emergency shut-down manually initiated from inside or outside the engine room − automatic shut-down of gas engine. 5.2.3 Alarm is to be initiated for unintended stop of the mechanical ventilation of the engine room.

5.3 Electrical Installations

5.1.1 The pressure in the gas supply system shall nowhere exceed 4 bar.g. 5.1.2 The gas supply lines are to have a design pressure not less than 10 bar. The lines shall as far as practicable be joined by welding. All buttwelds are to be subjected to 100 % radiographic inspection.

5.3.1 The following electrical installations are required to be certified safe for a hydrocarbon gas atmosphere: − −

lighting ventilation fans.

5.1.3 In the main supply gas line to each engine an automatic excess flow shut off valve shall be fitted. The valve shall be adjusted to shut off gas supply in the event of rupture of the gas line. The valve shall be located as close as possible to the point of entry of the gas supply line into the engine room. 5.1.4 An arrangement for purging gas lines in the engine room with nitrogen is to be provided.

DET NORSKE VERITAS

Suggest Documents