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7. Fuel/Emission Reduction System for Marine Diesel Engines

Fuel/Emission Reduction System for Marine Diesel Engines

The analysis and conclusions contained in this case study are those of the authors alone and do not necessarily represent the point of view of the Government of Canada.

Organization
M. A. Turbo/Engine Ltd.

Major Finding
A Fuel/Emission Reduction System is an efficient and cost-effective way to improve marine diesel engines performances while reducing emissions and fuel consumption.

Project Timeline
July to November 2006

Please note that some figures such as diesel prices are based on data from the period that this project took place.

Introduction

In July 2006, M.A. Turbo/Engine Ltd. (M.A. Turbo) began a project to reduce marine diesel engine emissions with financial assistance from Transport Canada’s Freight Sustainability Demonstration Program.

While the diesel engine is one of the most efficient power-generating machines, it produces high levels of air pollution. Today, high efficiency is no longer the single criteria for a successful engine design; it must also reduce operational costs and exhaust gas emissions.

The three major pollutants from diesel engines are diesel soot (particulate matter or PM), nitrogen oxides (NO_x), and carbon dioxide (CO₂). Current environmental technologies address PM, NO_x and sulphur oxide (SO_x) emissions but not CO₂. The best way to reduce total greenhouse gas (GHG) emissions from marine diesel engines is to reduce their fuel consumption. As clean engines operate more efficiently than dirty ones, a clean engine will consume less fuel and produce fewer emissions.

Carbon deposits in the air-suction duct (ASD) often reduce marine diesel engine performance. The most intense growth of the deposit layer takes place during the first 200-500 hours of operation. This layer continues to get thicker, but at a slower pace, during 700 to 900 hours of operation; and eventually stabilizes at around 1,200 -1,400 hours. As a result, engines work with restricted combustion airflow and reduced turbocharger efficiency for approximately 90% of the time after an overhaul period. This in turn raises exhaust gas temperature and increases fuel consumption, emissions and wear on cylinders and other engine parts.

Project Description

The objective of the Fuel/Emission Reduction System (FERS) project was to reduce the exhaust emissions of marine diesel engines by using water injections to keep the engine as clean as possible and running at maximum efficiency. Specific goals included:

• Reducing GHG
• Reducing NO_x
• Reducing fuel consumption
• Improving engine operation conditions

A water-injection FERS injects a limited amount of water into combustion air before and after the air cooler of a turbocharged marine diesel engine, 2 to 3 times a day, for 2 to 3 minutes each time - to remove carbon deposits.

M.A. Turbo installed a FERS on one of three auxiliary engines on the Queen of New Westminster ferry, operated by BC Ferries Services Inc. These auxiliary engines, called Gensets, are engine generators used to produce electricity.

The FERS system was installed on a 3508 Caterpillar diesel engine (Genset#2) in July 2006. The engine design parameters are:

• RPM – 1025
• Maximum Cont. Rating – 400 kW
• Bore/Stroke – 170/190 mm
• Aspiration – turbocharged and air-cooled
• Cylinder number – 8 in-line
• Specific fuel consumption at design output – 178 g/hp-h
• Fuel – Diesel No. 2

The FERS was expected to eliminate all deposits from the engine in the period between overhauls, during 8,000 to 12,000 hours of continuing operation.

Methodology

Emissions and fuel consumption data were collected according to US Environmental Protection Agency (EPA) requirements on two Gensets during 982 hours of normal operation. Genset #1 was tested without FERS, while Genset # 2 was tested with with FERS.

Genset #2 was overhauled in November 2005, before installing the FERS. Its air cooler and main parts were examined and cleaned of deposits. Data was collected on Genset #2 long before overhaul, closer to overhaul, and after overhaul, to find out the influence of overhaul on engine operational parameters. It is important to note that the FERS was put into operation on Genset # 2 almost 6 months after the air cooler was manually cleaned in November 2005. This means that deposits had already fouled the ASD before FERS started to clean it.

A similar diesel engine (Genset #1), without the FERS, was a reference engine for comparison, to measure the amounts of pollutants and fuel consumption.

The tests were done using the following main measuring equipment:

• Testo-350 exhaust gas analyzer (to measure emissions)
• Ultrasonic Dwyer Flow meter, Sonicflow UF10A (to measure fuel consumption)
• Direct measurements of CO₂ emission by California Analytical Instruments (CAI) Model 200 Infrared CO₂ analyser.

Results

The CO₂ emissions from the FERS Genset #2 during the test period decreased in the range of 1.93% to 2.15%, depending on engine load. The NO_x emission rate also decreased by 5% to7%.

Genset #2 demonstrated a reduced Specific Fuel Consumption (SFC) of 4.08% after an overhaul. This reduction was considered the ideal SFC and was used as the goal for the project. Practically the same SFC reduction level was reached after using the FERS for only three months (3.9% reduction). This was attributed to a cleaner combustion air suction duct. Average SFC savings for 982 hours of the FERS operation on Genset #2 was 2.6%.

During 982 hours of the FERS operation on Genset #2, no engine side effects were observed or registered. Genset #2 consumed 766 kg less fuel and emitted 2,428 kg less CO2 than it would have without the FERS.

Cost and Payback

As the FERS was only installed on an auxiliary engine, MA Turbo used data from BC Ferries as well as data generated from the project to provide an estimate of payback if the FERS technology was installed on all main and auxiliary engines of the Queen of New Westminster.

Projected Expenditures

FERS cost including installation (for all main and auxiliary engines) -$27,300
Water supply- $1500 per year
Cartridges for the water injection system- $1200 per year
Total expenditures: $30,000

Payback

• Savings for main engines due to FERS: $45,800
• Fuel savings for auxiliary engines: $5,500
• Total fuel savings: $51,300
• Replacements parts savings due to reduced gas exhaust temperatures: $6,000
• Reduction of maintenance costs due to cleaner air coolers etc.: $4,000

Total savings: $61,300 per year

The payback period for this ferry would be six months, if FERS were installed on all its main and auxiliary engines.

Conclusion

The FERS not only reduced emissions and fuel consumption, but improved engine performance including reduced engine wear, longer times between overhauls, lower exhaust gas temperatures, etc. The FERS is very efficient and cost-effective for reducing gas emissions and improving operational parameters without affecting engine reliability.

Additional Information

• US Environmental Protection Agency
• International Maritime Organization (United Nations Agency)

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Date modified:

2012-02-08

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