Energy Conversions Inc.

Transcription

1 Energy Conversions Inc. Maintenance Manual Economizer Dual Fuel Conversion Systems (Locomotive) Energy Conversions Inc., 6411 Pacific Hwy. East, Tacoma WA Phone: , Fax Web: Second Edition January 2011, Energy Conversions Inc., all rights reserved

2 Contents Gas Safety. 3 Properties of Natural Gas... 3 Inspection of Gas Piping and Hoses. 3 Precautions during Gas Fuel System Maintenance... 3 System Overview and Description. 5 Gas Fuel Supply Hardware. 7 Hose Connections. 9 Control Systems 13 Knock system 14 Leak Detection.. 16 Engine Control Unit ECU 17 ECU touch screen. 19 System Sensors Daily Inspection Day maintenance/inspection. 28 Annual Maintenance Three year maintenance.. 30 CNG fuel conditioning LNG fuel conditioning. 32 Notes page

3 Gas Safety Natural gas is as safe as any fuel, including gasoline or diesel. But, like any fuel, it has properties that require special handling considerations. For your safety and that of others, please read and understand the following natural gas information and fuel handling precautions. Properties of Natural Gas Natural gas consists mostly (>90%) of methane, a colorless, odorless, nontoxic gas. The familiar odor of gas is not the gas itself, but a pungent additive called methyl mercaptan. If the converted engine is using pipeline gas, mercaptan has probably been added, and you will be able to smell gas leaks. However, if your source of fuel is liquefied natural gas (LNG), you will NOT be able to smell gas leaks. This is because mercaptan doesn t stay in the gas at LNG s extremely low temperatures. Special equipment could be applied for this but many times it is not done. Therefore, don t rely only on your nose to detect gas leaks. Use the procedures outlined in this manual for checking the integrity of gas line connections and joints. Natural gas will not burn unless it is mixed with between 5% and 15% air by volume. Natural gas, like helium, rises in air. These two facts mean that, as long as there is adequate ventilation in the vicinity of the converted engine and gas fuel supply, there is little danger of fire. A problem can arise, however, when natural gas is allowed to accumulate in a closed area without ventilation. Accumulated natural gas is very dangerous. ALWAYS maintain adequate ventilation in the area of the converted engine and fuel supply. Precautions during Gas Fuel System Maintenance Before working on the gas system, always close the manual shut-off valve located near the gas fuel filter assembly. Manual Shut-Off Valve Gas Vent Valve Fig 1 Gas Filter, typical. After engine shutdown, pressurized gas can remain in the gas fueling system. Subsequent maintenance on the system could allow this trapped gas to be released into poorly ventilated areas close to the engine. To alleviate this problem, the system is provided with a gas vent valve, located near the gas supply filter assembly. It is very important, for the reasons given above, that trapped gas is vented at the vent valve before gas supply maintenance begins. A reminder is given in the text of this manual whenever gas venting is required. -continued next page 3

4 As when working around any fuel, remember to remove or shut off all possible ignition sources before working on the gas fuel system, including lighted cigarettes, welders, portable generators, heaters, electric motors, or anything else that could generate sparks or flame. If welding is necessary to repair gas piping, always purge the gas system with nonflammable gas. Liquid Natural Gas (LNG) Precautions Liquid natural gas has other properties that require special consideration. To turn natural gas into a liquid, it must be cooled to a temperature of -260ºF. Before LNG can be used in the engine, it must first be vaporized and converted back to gaseous form by warming. Liquid never actually reaches the engine itself. Follow these additional precautions when working near LNG tanks or piping: Never touch LNG, freshly boiled-off natural gas vapor, or frosted piping. They are extremely cold, and can freeze skin. In case of accidental contact with LNG, do not rub the burn. Soak affected area in lukewarm, not hot water, and seek medical attention immediately. Since LNG typically has no odor, you will not smell gas around a leaky LNG system. Use a hand-held electronic methane detector to verify leaks. 4

5 System Overview and Description The ECI Economizer Dual Fuel Systems is a retrofit technology that allows diesel engines to operate on a mixture of diesel fuel and natural gas. The conversion system is designed for ease of installation and reliability. Economizer systems are fairly simple and require no modifications to the engine. After conversion the engine will still have the ability to operate in 100 percent diesel fuel mode. The dual fuel system has been designed to allow for switching of fuel modes during full or part load conditions, without interruption of engine speed, power, or stability. The Economizer system utilizes a fumigation gas delivery method. The gas is delivered via an air/gas diffuser that is typically mounted on the air intake of the turbo charger. The gas is ignited in the combustion chamber by a diesel pilot, which acts as an ignition source for the air gas mixture. The dual fuel control system monitors various engine and system parameters such as; engine speed, power, gas pressure, exhaust gas temperature and engine combustion vibration (knock). This information allows the Engine Control Unit (ECU) to automatically activate or deactivate the dual-fuel operation. The ECU is also designed with fail-safe features. If a problem or malfunction is detected, the ECU instantly and automatically deactivates the dual fuel mode and switches the engine to 100 percent diesel only fuel mode. 5

6 Economizer Gas Fuel Supply Hardware The gas fuel supply hardware consists of storage tanks, Pressure Reducing Skid/vaporizer and connection hoses and fittings on the fuel car. The Locomotive has a manual gas shut off valve, Automated Locomotive Shutoff Valves, Gas filter, gas pressure regulator, a Gas Cut Off Valve, Gas Flow Control Valve, piping and flexible gas hose, and finally at the engine is the gas diffuser. Operation Under normal operation, gas pressure supplied to the system can range from 25 psi to 125 psi (this is system dependent). The pressurized gas passes through the opened manual gas valve through the Locomotive Shut Off valves, Filter and Regulator. The regulator is designed to maintain its pressure setting downstream even when upstream pressure changes. The gas pressure is stopped at the Gas Cut Off Valve (GCOV). The GCOV is pneumatically operated and is controlled by the Engine Control Unit (ECU). When the ECU determines that it is time for gas operation, it opens the GCOV, allowing gas to flow to the Gas Flow Control Valve (GFCV) where the gas amount is controlled to meet the engine power requirement. When making power in notch 3 and above, gas operation is normally activated. A general overview of the engine control equipment Fig. 2 6

7 Fuel Storage Types of fuel storage There are different types of fuel storage systems used for locomotives. They have different issues depending on the fuel storage type. In all cases the engine system receives the same basic fuel supply as if the engine system was connected to pipeline quality Natural Gas. CNG (Compressed Natural Gas) is where the gas is stored at high pressure in a tank array. The tanks are all connected with tubing. A means for filtering, heating and reducing pressure is applied. The system will have overpressure protection devices. The engine system will be supplied conditioned gas at normal pressures and temperatures. Normal being dependent on system details. LNG (Liquefied Natural Gas) is where the gas is stored at lower pressures and very low temperatures. LNG has a higher density and is most common with large fuel user applications. Different but similar to CNG the liquid fuel must be heated vaporized and have certain devices for overpressure and under temperature protection. Fuel storage can be applied on a separate car (Tender Car) or onboard the locomotive. The larger fuel using systems always use a Tender Car as the volumetric energy density of natural gas is low compared to diesel. A gallon of diesel has about the same energy content as 1.7 gallons of LNG. CNG volume energy is about half that of LNG. In most cases all the systems have similar connections and protection devices. The fuel supply system will have manual valves to isolate the gas supply and connecting pipe and or hoses to the engine system. Water lines (pipes and or hoses typically from the engine system) to provide heat for the supply system. Details regarding the fuel supply to the engine system is project specific. More information regarding maintenance and equipment details about this can be found in other documentation. Flexible Hoses between Locomotive & Tender Car Applications using a Tender Car will have flex hoses for connection across the coupling. The largest hose is for the gas from the fuel storage car, two medium hoses carry the heated engine water from the locomotive to heat exchanger on the pressure reducing skid/vaporizer where it warms the gas that has been cooled from expansion/vaporization. The small hose is controlled air pressure used to turn the gas on when system parameters are in order. Figure 2 shows typical pipe lines at the end of the locomotive and hose connections between locomotive and the fuel storage car. They include; control air pressure, Natural Gas supply, and engine cooling water. 7

8 Manual Gas Shut-Off Valve Vent Valve Quick Connect Couplings Manual Gas Shut-Off Valve Handle in the OPEN Position Fig. 3 Inspection and Maintenance Gas Piping and Hoses Manual Gas Shut-Off Valve Handle in the CLOSED Position Gas piping should be inspected on a quarterly basis (every 90 days). Engine gas pipe inspection should be performed with the engine running on gas. Use leak detection fluid on all piping and hose joints as well as all mating connections, bubbles will indicate a leak. Inspect the gas vent port at regulator and or discharge hose. Gas should not be venting while the engine is operating on gas or on diesel. If run testing is not easy to perform then compressed air should be applied to the pipes in proper locations and tested in the same way. NOTE: Soapy water may be substituted for leak detection fluid but should be avoided as it contributes to rust and oxidation. Refer to your company s approved equivalent. Hoses should also be inspected for abnormal wear or fatigue. Hose protectors must be in place. Hoses should be replaced if damaged or show signs of wear. Hoses should be replaced after three years of continuous service. 8

9 Connecting the Fuel Storage Car Hoses The hoses can be connected to the locomotive when the engine is running or not. Don t try it when engine is above idle. Assure that all the manual valves are off and always be sure that the locomotive is securely coupled to the fuel car before connecting hoses. Always be sure others are aware you are connecting, and that nobody will move the locomotive while you are making connections. 1. Open vent valves on the gas line to be sure there is no trapped or pressurized gas, then close the vent valves. 2. Be sure to keep the fittings clean and free of dirt. Connect the gas hose by pulling the sleeve ring back against its spring. Get it started over the end. Once started you will not need to keep the release sleeve pulled back. Align the fittings so they are pretty close to strait and shove it together against its internal valve springs until it snaps in place. Be sure the sleeve securely latches and the coupling is fully connected. Open the manual gas valves. 3. Connect the water hoses in the same manner as the gas hose. Connect the air hose. Open the manual valves. 4. If not already done, open the high pressure gas supply valve slowly. For LNG tender cars it may be necessary to reset the control system on the car. 5. Check the hoses for leaks. Disconnecting the Fuel Storage Car Hoses Always disconnect the hoses before releasing the car coupling. 1. Close the manual gas shut off valves both on the locomotive and on the fuel car. Open one of the gas vent valves and let the gas pressure out. 2. Close the vent valve. 3. Disconnect the four hoses in any order you like by pulling the release sleeve and pulling on the hose. Take care not to damage the fittings, don t let the disconnected fittings bang onto the car coupling or frame, and try not to twist or kink the hoses. Try to keep the hose ends out of the dirt or debris. NOTE: If it is expected that service work is to be done to the fuel car then you should vent the complete system by first shutting the high pressure valve, venting the gas with the manual valves open. 9

10 Gas Filter (on locomotive) The filter should be replaced every two years or as necessary. The Gas Filter ensures that any debris from the coupling and uncoupling as well as any pipe scale does not enter the turbo charger and engine. The gas itself typically is very clean. The differential pressure can be measured and should not exceed 2 psi when testing in notches 5-8. To change it, close the supply valve, locate vent valve and drain gas pressure. Install a new element as with any normal filter assembly. Filter Fig 4 Gas Cut Off Valves and Locomotive Shut Off Valves Air operated Gas Cut Off Valve (GCOV) and Locomotive Shut Off Valves (LSO) should be inspected annually. Do this by venting the gas pressure and dismantle the valve. During reassembly, use quality seal lube grease like a silicone based seal glide. Replace the seals if they show any damage or every 3 years. GCOV Fig 5 LSO Fig 6 10

11 Gas Regulator Regulators should be inspected annually for leaks as described in Gas Piping and Hoses. Seals should be replaced/reconditioned every 3 years or sooner if problems appear. The regulator should not need adjusting after install. The pressure of gas without flow is normally higher than the set point and adjustments to the pressure should only be done after determining that the pressure is high while flowing. The gas pressure regulator on the locomotive is set to: 28 inches Water Column on GEA or DEMU locomotives with Cummins engines 28 psi on GE BB36 6 psi on GE Dash 9 Regulator Fig 7 11

12 Gas Flow Control Valve Visually inspect the inlet and outlet flanges for gas leaks as describes in Gas Piping and Hoses and ensure electrical connection to the ECU is undamaged. The Gas Flow Control Valve itself requires no periodic maintenance. Life expectancy is 6 years (approximately 48,000 hrs of operation). GFCV Fig. 7 Air/Gas Diffuser The Diffuser has no moving parts and is maintenance free. Inspect the rubber boots and the security of the clamps annually. Visually inspect for cracking along welds and ensure gas supply connection is tight. Diffuser Fig. 8 Gas heating equipment As outlined in the fuel conditioning section, there are several configurations for heating the gas during conditioning. Most all of the ECI systems use engine water for this purpose. Typically water is taken from the engine water pump discharge for the supply. Return is routed to a location in the system after the engine radiators, near the pump intake. Inspect the connecting hoses for leaks. Hose replacement should be considered every five years. 12

13 Control Systems Engine Control Unit, ECU overview The Economizer control system uses a PLC controller connected to sensors and actuators to monitor various engine and system parameters such as; engine speed, power, gas pressure, exhaust gas temperature and engine combustion vibration (knock). This information allows the Engine Control Unit (ECU) to automatically activate or deactivate the dual-fuel operation. Maintenance No regular service is necessary for the ECU. Servicing the ECU should only be done by qualified technicians. The electronic modules are robust but electrostatic discharge precautions should be observed while handling the hardware. Power for the ECU comes from the locomotive batteries, through the System circuit breaker (added circuit breaker to the locomotive control panel). Then through a 72 to 24 volt converter module. The ECU power connector has both a 72 volt circuit and a 24 volt circuit. The 24 volt system is isolated from the locomotive battery circuit. Inside the ECU are additional circuit breakers and a power module to create a stable 24 volts for the computer. In addition there are 5 and 15 volts created for system sensors. All of the devices of the conversion system operate through the system 72 volt circuit breaker. Relays are used to switch the 72 volt circuits while most everything else is powered off the 24 volt converter module. SCFM (home screen display value) Because the engine operation will hardly be any different than strait diesel you may wonder how much gas is actually being supplied. The SCFM (Standard Cubic Feet per Minute) reading on the information screen is a good indication that the system is operating properly. This number indicates the amount of gas flow into the engine and will be automatically adjusted depending on power. Generally in the upper notches you will expect gas flows to be: SCFM for Cummins engines SCFM for GE engines If the number is fairly low (0-50) then the system may be having a problem trying to supply gas to the engine. There may be a hardware problem or a system variable that has trimmed the set point excessively low. Display screen Fig. 9 13

14 Knock System In addition to the primary controller the Economizer system is equipped with a special computer to detect and control Knock or detonation. Knock is a term used to describe undesirable combustion. When the speed of combustion gets to high, cylinder pressure becomes ragged and the peak pressure climbs to levels above what the engine is designed to withstand. Knock is affected by a number of different things; high temperatures, fuel gas content, engine health, and/or excessive gas to air or diesel ratio just to name a few. Knock sensors (mounted to engine cylinder heads) and controls are used to protect the engine in the event that knock occurs. The knock sensor generates a voltage signal proportional to the amplitude and frequency of vibration. The signal from the sensors goes to a dedicated computer. The computer filters and measures the signal for amplitude. If the signal from any sensor exceeds it s threshold, the ECU computer is signaled. If the computer receives excessive knock signal, then it determines that more diesel should be delivered to avoid knock. If the signal continues and is extreme the computer switches off gas mode and operates on diesel only. This alarm function is then latched. To reset the latch you switch the mode switch (on the side of the ECU) to diesel and back to gas. Maintenance: The knock system should not need any regular service but should be inspected for proper operation every 90 days. The best inspection is by connecting to it with a laptop computer through a USB cable with the engine running. Run the software for the system Denedit.exe. Connect with the proper serial channel and view the operation of the system. Confirm the ISU pulse and low RPM signals are inactive and that each cylinder sensor is providing adequate signal strength. You will most likely need to increase engine speed to throttle 8, but it is not necessary to do a load test or even operate on gas. This test is just to insure that the sensors are connected and working properly. Alternatively you can inspect the system by simply viewing the indicating lights on the knock computer module itself with the engine running. At idle the green ignition pulse light should be pulsing and none of the red knocking sensor lights should be flashing. 14

15 Knock system continued The knock system is configured so that when there is no knock and the system is functioning properly, the controller signal is 5 volts. Lower voltage indicates knock or a system problem. Some systems will also use the Trip signal for continuous operational monitoring. The knock system uses a sensor (or other input signal) to detect the position of the engine, typically via the camshaft or a target rotating at camshaft speed for timing. The sensor is set at two-four turns out from contact with the highest point of the target or gear. For GEA/ DEMU locomotives with Cummins engines you must be very careful to set the sensor gap when cam lobe is aligned with the sensor. For GE BB36 locomotives with GE engine there is only one target hole in the cam gear and the sensor can be checked anywhere except at 335 degrees. Ignition pulse should be pulsing when engine is running above notch 4 Knocking indicators for each cylinder should not be flashing Power light normally on Knock computer Fig 10 Center trip light is normally on 15

16 Leak Detection System LDS The LDS is a stand alone protection system to turn off the gas supply in the event that a leak develops in the gas piping on the locomotive. The control module is mounted in the locomotive electrical cab. It is powered with 24 volts from the 72 to 24 volt converter. The LDS has 2 to 4 sensors connected to it. It is configured to be as fail safe as possible, if it is not powered or has detected a leak its control circuit is open. A bad sensor will only indicate a fault. After a short warm up from being turned on it will close its control circuit. It will open the circuit and sound its alarm if it detects gas concentrations greater than 2.5% gas in air. There is no need for calibration. The system has a short time delay upon sensing gas and will take a few seconds to trip when making tests. You can test the system with any hydrocarbon gas. Maintenance Testing should be done approximately every 90 days. There are no user serviceable parts to the system. If a sensor fails it can be replaced with a new sensor by turning off power and replacing the sensor. Turning on the power will auto calibrate, there is no need for calibration gas. Normally the panel will only show a light for each 4 channels. If a fault is indicated it means that that channel is having a problem. System schematics will show the location of what sensor is connected to what channel. If the system indicates a trace level it might be due to a sensor going out of calibration as well, not necessarily a leak. Check for leaks and try replacing the sensor. LDS panel Fig 11 The LDS system is connected to a fairly simple group of relays on the locomotive so that the function of the series of interlocks will stop gas delivery. System schematics will detail the exact configuration of your system. The result is that gas supply is shut off at the source for several circumstances to include, Emergency Brake, engine shut down and detected gas leak. 16

17 ECU Controller details The touch screen display on the ECU is the window into the operation of the Economizer System. The screen uses rectangular touch buttons to navigate to various information screens. The Home Screen indicates the power output of the running engine, gas flow and whether or not the system is ready to operate with gas. Indication on or off of gas is made known by screen color. A green screen indicates the engine is running on gas. If the screen is amber/orange the engine is running on diesel. Screen color changing is done the same time as the Gas Cut Off Valve (GCOV) function changes. Some factors provide instant shut-off and some factors provide for a 5-second ramping off of gas, so the screen color change may be delayed from the time you flick the switch. By pressing the menu button on the home screen you gain access to approximately twelve sub screen options. An indication light is provided to indicate there is a trouble with the system. The trouble indicator will light if the engine is above the necessary power level but not running with gas. If the screen indicates the unit is not on gas, Menu1 provides Limit and Limit2 buttons for access to possible out of limit values. By selecting one of these two buttons 16 factors can be displayed. The factors that cause the unit not to use gas will be blackened, allowing for troubleshooting. Most of these blackened buttons can be touched to access further information. There are 3 factors that will cause a Latched Fault (LF). A Latched Fault is where the fault will not automatically reset itself with a good value. Excessive knock signal will lock the system onto diesel, high gas pressure, or high engine speed after the programmed number of retries (typically 5) will require you to reset the latch. Turn the ECU mode switch off and on again to reset. The system includes a clock that is used to time stamp the most recent Out Of Limit message. This is useful for a quick check that the unit has been running without any recent Out Of Limit conditions. This information is accessed from the Menu1 screen Last Limit. The Last Limit message is reset anytime the system is powered off and a fault message is only set when it is automatically switched from gas to diesel. The clock is also used to record the amount of time the engine is running as well as the time it has run with gas. This information is accessed from Menu2. On older systems the clock is only adjustable through a PC with time adjustment program. 17

18 ECU Screen Acronyms (Meanings and Normal Limit Settings) Limit levels are set for most of the system variables to suit each engine family and type. Differences in RPM and Power levels are common and specific to generator type. Values outside of normal limits and levels will cause the system to operate in the diesel mode. Note: Not all of these values are available on all systems. Altcomp Altitude compensation (some models) Amp Air Manifold Pressure, 0-20 psi is common. (GE Dash9 approximately 36 psi) AmT Air Manifold Temperature, 80 F to 250 F. Ampc Pressure compensation Amtc Temperature compensation Baro Barometric Pressure, Hg. (GE Peru) Calib Calibration (GE BB36 governor rack sensor) Delta Difference between set point and actual governor position, a unit-less number that is normally within +/- 200 Drive % Percent of Pulse width drive to GFCV, EGT Exhaust Gas Temperature F changing with load and air temperature GPE Gas Pressure Engine, typically 28 psi. (GE Dash9 6 psi) GPM Gas Pressure Meter, meter compensation measurement PSI GT Gas Temperature, F HP Horse Power, percent of generator rating I/O On/Off Switch JWT Jack Water Temperature, F KNO Knock, unit-less number makes fuel adjustments above the number 75 LDS Leak Detection System, this on off signal tells the system if all is good LF Latched Fault, turn mode switch off and on to reset MGA Main Generator Amps, (Locomotive dependent) MGV Main Generator Volts, RPM Engine Speed, +/- 10 percent of operating speed with some exceptions V0 Trim adjustment, percentage of reduced gas setting KNO2 The amount of gas reduction to engine in order to reduce engine knock during operation. Note that some specifications listed may not apply to your application. Always double check the actual documentation (ie. schematics and drawings) provided by ECI for your particular application. If for reason there are any difficulties or limitations after reading the supplied literature. Please contact ECI for any additional technical support questions you may have at (253) Tacoma WA., U.S.A. 18

19 ECU Touch Screen (Menu1) Illustrated below are the most common ECU screen configurations for the Economizer systems Small changes and differences may be found with your system depending on particular custom modifications. Main Home Screen Menu1 Screen Menu1-Pressure Menu1-Temperature Menu1-Last Limit Menu1-Limits Menu1-Limit2 Display screens Fig

20 ECU Touch Screen (Menu2) Main Home Screen Menu1 Screen Menu2 Screen Menu2-Fuel Menu2-Engine Menu2-Calib (Calibration) Menu2-Clock Menu2-Outval Menu2-Trims Fig

21 ECU details continued Circuit Breakers Inside the ECU is a 10 A circuit breaker for the 24 volt supply. A 5A circuit breaker for the power to the GFCV. If the 5 A switch is Off or tripped, the system would function without much change except that very little gas would be supplied to the engine. If your SCFM value is low, this would be a first good item to inspect. It can be useful for diagnostics too. Relays there is capacity for three relays. Relay 1 is activated to turn gas on to the system. Relay 3 activates the trouble indicator. Relay 2 is not used. V0 Trim Inside the ECU on the computer itself there are two trim pots. V0 and V1. V1 is not used. V0 can be turned down (counter clockwise) to reduce the amount of gas delivered to the engine. Normally this is left fully clockwise for the full, programmed amount of fuel replacement. For diagnostics the trim pot can be turned down to increase the level of diesel used and evaluate the engines operation. The value for this variable can be read on the Trims screen, V0. Voltage test locations: there are a number of locations inside the ECU where voltage values can be measured for diagnostics. Channels 9-16 ECU voltage measurement locations Fig. 14 Sensors voltages 1-8 PLC +24V System common 21

22 Sensors overview Sensors are used to create electrical signals proportional to the process variable they are designed to measure. The electrical signals are measured by the Engine Control Unit (ECU) and in most cases converted to engineering units or real world numbers. The conversion system controller measures the following process variables: Air Manifold Pressure Air Manifold Temperature Exhaust Gas Temperature Engine Speed Fuel Oil Pressure (pressure switch) Gas Pressure 2 places Gas Flow Gas Temperature Governor Position (application specific) Knock Jack Water Temperature Generated Power by Volts and Amps Gas leak 4 places The sensors are very important components to the conversion system. It is critical that they are in good working order if the conversion system is to operate properly. The ECU uses the information to determine if gas operation can be performed and to tune engine performance. In nearly all cases a bad sensor will result in not being able to operate in the gas mode. Maintenance: The sensors should provide years of service without problems and no regular maintenance is required. A damaged sensor can be replaced easily with a new sensor using basic guidelines. Pressure Sensors AMP,GasPM, GasPE : The system uses two to three identical pressure transmitters for sensing the system gas pressures and air manifold pressure. The sensors are rated for psi. They are powered with 24 volts. The signal output is 4-20mA, measured on the PLC as a 1-5Volt signal Pressure sensor Fig 15 22

23 Temperature Sensors AMT, GT, JWT :, the system has three identical temperature sensors for Air, Water and Gas. These sensors are a resistance device who s value is affected by temperature. At room temperature the sensor will have about 3k ohms. They are powered with 5 volts. Temperature sensor Fig 16 Exhaust Temperature EGT,EGTR, EGTL : The ECI system will use one or two sensors for measuring exhaust gas temperature. These sensors are a thermocouple K type. This type of sensor generates a very small signal voltage. A good sensor will measure like shorted wires. The signal gets amplified on a special board in the ECU. Exhaust Temperature sensor Fig 17 Fuel Oil Pressure FOP : Most ECI systems will monitor diesel fuel pressure as a measure of proper engine health. Loosing diesel fuel pressure while running with gas will cause misfire. There are different styles depending on the engine type. A Cummins engine will use a Pressure Transmitter as shown previously. GE engines will have a basic pressure switch that is typically set for 15 PSI, Normally Open. 24 volt signal. Pressure switch Fig 18 23

24 Engine Speed Erpm : The engine speed is measured typically through the application of a magnetic pickup either to the cam gear of flywheel ring gear. In some applications (Dash 9) connections are made to the existing speed sensor at the camshaft gear. These sensors have a coil inside them and generate their own signal when the gear teeth pass. Resistance of the coil will vary with sensor type and temperature. It is common for the sensors to have about 1200 ohms resistance. When the sensor is changed it must be adjusted to have the proper gap. Approximately is good. Typically you will adjust the sensor in until it touches the gear tooth and then back it out one full turn, secure the lock nut. Don t over tighten the lock nut, approximately 15 Ft. Lb. max. Speed sensor Fig 19 Gas Flow: DP, The system uses a flow sensor and a flow transmitter to calculate gas flow. The sensor is a robust pipe assembly that has connection fittings on it. Hoses are applied connecting the sensor to the Differential Pressure (DP) transmitter. The transmitter is powered with 24 volts DC. Signals the ECU with a 4-20 ma current. The transmitter is calibrated to send full scale signal at 35 water column. Measured by the PLC as 1-5 volts. Gas flow sensor & transmitter Fig 20 Transmitter Sensor 24

25 Governor GOV : There are three basic types of governor sensors/signals. Dash 9 locomotives measure the pulse width of the electronic fuel pump. This signal wire connection is made to the locomotive governor system. This signal is applied to a special module inside the ECU and is scaled into milli Seconds. Cummins engines have a pressure sensor (same pressure sensor that is used for air pressure and fuel oil pressure) applied to the common rail exiting the fuel pump.engines with a mechanical linkage will have a position sensor mounted to the linkage of the fuel pump rack control. Governor position sensors Fig 21 Knock KNO : Knock sensors are applied to each cylinder head of the engine. These sensors are vibration transducers. Like a microphone they generate a signal relative to the amplitude and frequency of the vibration. The signal is analyzed by the knock computer. Inspection is generally done through the computer. The sensors are peizo electric. When measured with an ohm meter they will look like they are an open circuit. You can measure their capacitance. Normally approximately 2uF. Knock sensor Fig 22 Sync this is also a part of the knock system. GE Dash 9 systems will get a synchronizing pulse signal from the existing cam position sensor that is wired to the locomotive governing system. Other engines (non electronic injection) will have a probe type sensor to detect a target on the camshaft so the knock computer will know when to take its measurements for each cylinder. The probe type sensor is a Hall effect device, powered from 15 volts and will be wired directly to the knock computer. Adjust its gap when at the highest point of the target, set 4 turns out from contact. If pulses are missed turn the sensor in one turn. Knock Sync sensor Fig 23 25

26 Volts and Amps: VAI sensor and MGV and MGA signals, The locomotive Main Generator volts and amps are connected to the Volt Amp Isolator. This signal conditioning module isolates and scales voltages. The module is powered with 5 volts and the output signals range 0-5 volts relative to the input voltages. There are different configurations for different locomotive types. All have the same conditioning for the voltage. 300:1 ratio DC input volts will produce a 5 volt output signal. The current signal of the module can be configured to measure mv s from Current Shunt sources (0-100mv) or 0-10 VDC range from a conditioned signal as found on GE, BB36 and Dash9 s. Volt Amp Isolator Fig 24 Leak LDS : Sensors for the Leak Detection System are a very special type of sensor. These are part of LDS package and there is little information available on the specific details. If you have a problem with a channel, change the sensor. Gas leak sensor w/clamp Fig 25 26

27 Service and Maintenance Initially the conversion system should be monitored quite regularly, recording the operational time clocks and making sure that the operation is mostly with gas. If time clocks indicate that excessive diesel operation occurs it will be necessary to determine the cause. Eventually the conversion system should be inspected for proper operation every 90 days. A load test operating with gas will cause all of the devices to be functional. If load testing is not practical then at least a short ride with the unit working on gas should be performed for making the necessary tests for gas operation. Cab indicator trouble lights will light when the gas system determines something is not normal. Information from the operating crews should normally indicate that the trouble lights are rarely on. Gas operation lights should indicate operation when in throttle notches 3-8. Daily Tasks added to normal service tasks: WHAT WHO HOW COMMENTS Operation Engineers Visual Indicators Check to see that the fault light is usually not on. Green light is usually on above Notch 2. Hoses and pipes Engineers Visually inspect for damage or leaks. Leak Detection System Engineers Visual inspection of Leak Detection System General inspection to insure that pipes and hoses are in good working order. Ensure all four sensors lights are lit on panel. Initially weekly then monthly, finally, every 90 days after weekly operation proves good: WHAT WHO HOW COMMENTS Operation Manager Talk to Engineers Ensure locomotive operation is satisfactory during gas operation. High pressure filter Maintenance Disassemble and inspect Pipes and hoses Maintenance Visual and leak detection fluid. See below on filter inspection. Check pipes for leaks Leak Detection System Maintenance Visual Ensure all four sensors lights are lit on panel. 27

28 Routinely every 90 days: WHAT WHO HOW COMMENTS Operation Manager Talk to Engineers Make sure locomotive operation is satisfactory while on gas. Gas Piping Maintenance Visual and leak detection fluid. Check pipes for leaks. Regulator vents Maintenance Visual and leak detection fluid. Ensure gas is not leaking Leak Detection System Maintenance Visual Ensure all four sensors are operating and no leak lights are lit on panel. Testing Maintenance Load Testing Operationally test the unit to confirm proper gas operation. Tender Car connecting hoses Maintenance Visual Inspect the hoses for damage. Clean and lube connector fittings Knock System Maintenance Laptop connection and visual inspection of Ignition pulse light. Inspect the input channels to ensure signals from sensors are being received. Differential Pressure Transducer Maintenance Visual Inspect for near 0 reading at no gas flow conditions. (0 error in excess of +/- 1) Gas piping should be checked for leaks using bubble test fluid when the system pressurized (check gas pressure reading on system information screen). Visually inspect hoses and piping for leaks or damage. 28

29 Maintenance every year WHAT WHO HOW COMMENTS Gas Cut Off Valve Maintenance Disassemble and inspect. Fit new seals if needed. Pipe flange torque Maintenance Visually inspect and check bolt tightness Flange bolt torque 60Ft. Lbs. Diffuser connection hoses and clamps Maintenance Visually inspect and check clamp tightness 29

30 Maintenance every three years WHAT WHO HOW COMMENTS Gas Pressure Regulator Maintenance Remove and replace Refurbish regulator assembly Gas and Water hoses connecting tender car Maintenance Visual inspection Replace hoses as necessary Gas Cut Off Valve and LSO valves Maintenance Dismantle Replace all rubber parts Gas Filter Maintenance Dismantle, replace filter element and leak check 30

31 CNG high pressure reducing hardware Pressure Reducing Skid: The PRS takes the high pressure gas supply, reduces the pressure and heats the gas back to normal levels, and protects the locomotive from possible overpressure condition. Normally the skid requires no maintenance and should not be tinkered with. There are six adjustable devices on the skid. Primary Pressure Reduction: The primary regulator reduces the gas pressure from the storage tanks. The regulator is a dome loaded design whereby air pressure applied to it will turn it on. The gas pressure will equal the pressure of the air on the dome (locomotive air pressure). Air Pressure Control for Primary Pressure Reduction (PRS): Air supply to the dome of the primary regulator is controlled on the locomotive with a solenoid valve. The solenoid valve will be activated when the Leak Detection System is operational and detects no leaks, when the engine run relay is closed (typically Fuel Pump Relay) and when the train brakes are set up. On two engine locomotives these controls come from engine #2. There are quick exhaust valves on both the source and destination ends of the air system. These valves work to quickly reduce the air and close the gas supply when the air supply is shut off. On the PRS there is a restriction valve so that the air pressure on the dome of the regulator builds slowly resulting in the gas pressure also building at a comfortable rate. The restriction can be adjusted for a 1 2 second rise time. The level of air pressure might not be adjusted on the locomotive, just using full air is the normal application, >125 psi. Pressure Relief: The gas leaving the high pressure regulator is routed past a high volume pressure relief valve. This safety device will quickly vent any gas above its set value. The valve is pilot operated and set for 150 PSI. It is capable of limiting the system pressure to 250 psi even if the primary regulator has completely failed and the tanks are at maximum pressure. ECI recommends checking this valves operation annually. To check this operation apply air pressure to the high pressure regulator in a manner that you can control and increase it above the relief valve setting, increasing it until the pressure relief valve operates. The pilot pressure is adjustable with its regulator but should never need adjusting. 31

32 High Pressure Filter (on Pressure Reducing Skid with CNG fuel storage) The filter should be replaced every two years. Check for condensate collection every 90 days. Close the high pressure supply valve, locate vent valve and drain gas pressure off of the skid. Carefully remove the plug on bottom of filter canister. Drain any accumulated liquids. Note the volume and consider when the next inspection period should be (different fueling systems can produce different amounts). After approximately 6 months of operation, vent as above, then carefully remove filter canister (it is heavy and has threads, be careful not to damage the threads) and inspect filter element for contaminants. If it is reasonably clean re-install, otherwise install new filter. If the unit is in daily operation, this should be checked more regularly at first to determine how much contaminant is in the gas. If initial checks show little contaminants then inspections can be extended. The goal is that this should need draining only every 90 days. The filter has a differential pressure indicator to view for filter restriction however this is effective only when tank pressure is low and engines are using maximum gas flow, notches 5-8. Secondary Regulator (not all systems will have this) The secondary regulator is designed to take the high pressure from the primary regulator and further reduce its amount. Typically to a value below 30 psi. When checking this setting make sure that gas is flowing. Even if just out a small vent valve as this regulator seat tends to leak some and the pressure will increase slowly when there is no gas flowing. LNG fuel conditioning hardware The LNG fuel conditioning hardware varies on different projects. Generally the system on the tank for filling and delivering LNG is very involved. Follow the tank system manufacture guidelines for maintenance and service. Once the gas is past this equipment it is a fairly simple task of vaporizing it and having a regulator to control pulsations that might develop from vaporization. Make sure the water supply to the system is adequate. The Vaporizer should never be cold enough to form frost on the gas pipes leaving the tender car. 32

33 Notes: 33