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Copy of Technical Bulletin

Last Updated 4/15/97


System Information & Specifications- Natural gas power for Caterpillar 398/399D engines

Subject: System specifications for the ECI dual fuel conversion kit for the Caterpillar 398/399D diesel engines.

This document describes the operating conditions and specifications for the ECI Dual-fuel conversion kit as it applies to the Cat 3XX series industrial power engines. ECI conversion kits are designed to retrofit to a customer's existing engine. Contents for each kit include components which replace or are in addition to standard Cat parts.
Kits are supplied partly assembled. The only on-site assembly required are the areas that may be unique to the site, or adaptations to the existing engine. On site assembly may be accomplished by the customer and/or installation contractor. ECI technical support can be made available for any or all of the conversion work.

Standard Rating Conditions

All engine ratings contained herein apply under the following conditions:

  • 77 oF (25 oC) air intake temperature
  • 29.61 in. Hg. (100 kPa) barometer
  • Diesel - 18, 054 BTU/lb. (42,000 kj/kg)
  • fuel (LHV)
  • Gas - 900 BTU/ft3 (LHV)

Data supplied herein is based on a combination of test engine results, operating units in actual commercial applications, and projected estimations. ECI is confident in the accuracy of the data provided, however actual ratings may vary slightly.

Fuel Quality Requirement

Natural gas is composed principally of Methane (CH4), with smaller quantities of other hydrocarbons, nitrogen, carbon dioxide, and water. The quality of the natural gas used to fuel an ECI converted engine, with respect to its percentage makeup of component gases, will directly affect the power, efficiency, emissions, and diesel replacement of the engine. As a general rule, higher methane content results in higher fuel quality. Of the hydrocarbons listed below, Butane is the most common variable to adversely affect engine performance. Hexane is more destructive than Butane, but is seldom seen at levels high enough to cause concern. In any case, maintaining hydrocarbon levels at or below indicated target levels is necessary for achieving rated power performance. Acceptable levels (in Molar percentages) for various component gases are described below, with the sum of all non-methane hydrocarbons not to exceed 8% of the total fuel mixture.

Tolerance

FUEL QUALITY REQUIREMENTS - NATURAL GAS
Element
Tolerance
Methane (CH4)
> 92%
NON- METHANE HYDROCARBONS (NMHC)
Ethane
<8%
Propane
<8%
ISO & N Butane,
Pentane,
Hexane,
Heptane,
Decane,
combined total
< 2%

An engine's full rated horsepower can be achieved and actually exceeded providing the engine variables are kept into proper tolerances. If the fuel mixture is equal to or better than the indicated tolerances the system will provide maximum possible replacement. If percentage levels of elements other than methane are too high, and rated power is required, then the system will make up the power with addition of greater levels of diesel to avoid combustion knock. Alternately the gas fuel may be scrubbed so that diesel replacement is maximized.
To determine the replacement level of diesel using poorer quality gases:
Propane + Ethane + (all remaining heavier hydrocarbons X 4) = % non-methane hydrocarbons.
See figure for more information relating to diesel fueling levels with non-methane (CH4) hydrocarbons.

Turbo Aftercooling System

Extending the performance of the aftercooling circuit is required for rated power performance. Less than optimum aftercooling will result in a reduction of diesel replacement. Target air temperature inside the engine is 125 oF. See temperature curve in figure 2 for correction factors above 125 oF.

Hardware Options

Certain applications require the use of modified cooling system design in order for the converted engine to run properly and produce fully rated output. Consult ECI concerning your particular project for more information.
ECI offers additional related hardware to help accurately monitor and improve your engine's performance:
* ECI's Modem Diagnostics board, can be factory installed in your engine's main electronic control unit. It provides the ability to send engine monitoring information to an operational headquarters or back to ECI via a telephone signal, so that critical data may be gathered and studied while the engine is running.
* An Engine Preheat systems is required for cold start situations, and is available through ECI. Heating the engine to 135 oF is necessary for starting the engine without Ether.

Kit Components and Equipment Packaging

ECI conversion kits include: ECI modified pistons; Pilot fuel (diesel) control system; Electronic Control Unit (ECU) and corresponding electronic components and software; Gas supply piping and necessary flow controls; Pneumatic controls, fittings and hoses; Wiring cabinets, harnesses, switches and diagrams; Water system aftercooling tanks, pumps and valves; and a complete Reference guide including Installation, Maintenance, and Parts documentation.
Basic packaging used on ECI equipment provides protection during domestic shipment only. For overseas shipment, export boxing is available for an additional cost.
All equipment, whether domestic or export, should be inspected for any possible shipping damage.
Delivery lead times may vary with quantity and configuration of orders. Please allow a minimum of 90 days from the date of purchase order received.

Installation

Responsibility for proper installation, including machinery alignment, piping, electrical wiring, and testing, is the responsibility of the customer and or installation contractor. Upon request of the end customer, a final inspection and initial start-up can be made by an ECI representative at the time of completion.

Technical Support

In addition to the supplied installation manual, reference manual, and video, ECI offers technical support in person and over the phone. ECI provides a complimentary service of 30-60 hours per engine as part of the conversion system purchase for inspection and a first time start-up check. This service may be extended depending upon the number of units and complexity of the installation.

Information Required from the Customer

ECI requests a completed information questionnaire in order to submit accurate cost proposals. The questionnaire is located at the bottom of the Contact ECI page. The questions below are among the most pertinent listed on the actual questionnaire.

1. Is the application mobile or stationary?

2. What size is engine(s) and configurations

3. How many units are to be converted

4. Site location; state, country

5. What is the quality and availability of natural gas to the application

6. Which type of fuel source, pipeline, well head gas, or LNG, is most appropriate to the application and most readily available

7. What are the expected ambient conditions (temperature and altitude) in which the engine will operate

8. What is the time line of the project?

A complete questionnaire may be obtained through our web site on the http://www.energyconversions.com/contact.htm or by calling ECI at 253-922-6670

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ECI Conversion Specifications Tables
ECI CONVERSION SPECIFICATIONS -CAT 399 TURBOCHARGED DUAL FUEL ENGINE
ENGINE TYPE
379DF
398DF 399DF
NUMBER OF CYLINDERS
8
12
16
RPM
1200
1200
1200
BHP
645
970
1260
KW prime
400
600
800
KW standby w/o fan 450 675
905
EFFICIENCY BTU/ hp-hr
Diesel / Gas&Diesel
100% load
7670
6825**
7670
6825**
7670
6825*
75% load
7450
7920*
7350
7561*
7300
7950
50% load
9850
9920*
9950
10000*
9950
10750
AIR & EXHAUST SYSTEMS
Intake air temp (77F) CFM
3800
5000*
5400
7500*
7380
10000
Exhaust temp in (F)
-
715*
-
740*
-
720
Exh. volume @ exh. temp CFM
7980
10500*
11340
15700*
15500
20350
EMISSIONS
NHMC in g/hp-hr
CO in g/hp-hr
CURRENTLY TESTING
NOx in g/hp-hr
AFTERCOOLING SYSTEM
Water flow rate gal/min
40*
60*
60
Heat Rejection rate BTU/hr
236K**
354K**
472K*
Raw water
85 F
Water Pump hp
2
3
3
DIESEL FUELING RATES, gal/hr
Diesel / Gas&Diesel
Gas Flow @ 100% load
36
11.5*
54
17.5*
72
23
Gas Flow @ 75% load
26
4.2*
39
6.3*
53
8.4
Gas Flow @ 50% load
17
2.5*
25
3.8*
35
4.7*
Injector timing set to 5 degrees after TDC
GAS FUEL FUELING RATES, SCFM
100% load
49*
73*
98
75% load
41*
62*
82
50% load
36*
54*
72
* values extrapolated from 16 cylinder test data
* Baseline figures. System details affect actual values.
ENERGY CONVERSIONS INC.
6411 Pacific Hwy. East, Tacoma, WA 98424-1587 USA
(253) 922-6670, FAX (253) 922-2258
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