With reference to diesel engine cooling water:
(a) explain why the water requires treatment;(6)
(b) describe the type of treatment that should be used.(4)
Why Diesel Engine Cooling Water Requires Treatment
Diesel engine cooling water requires treatment primarily to prevent the following issues:
- Corrosion: Untreated water can corrode the cooling system components, leading to leaks, reduced efficiency, and potential engine damage. 1. Understanding and Preventing Engine Coolant Breakdown – BG Products www.bgprod.com
- Scale formation: Minerals in the water can form deposits (scale) on heat transfer surfaces, reducing cooling efficiency and potentially causing blockages. 1. Scale Formation – Coolant – Penray penray.com
- Microbiological growth: Bacteria, algae, and other microorganisms can thrive in cooling systems, leading to fouling, corrosion, and system blockages. 1. Microorganisms in Cooling Water Systems – Watertech of America, Inc. www.watertechusa.com
- Cavitation: Water cavitation can occur due to high temperatures and pressures, causing erosion and damage to cooling system components.
By treating the cooling water with appropriate chemicals, these problems can be mitigated, ensuring the efficient and reliable operation of the diesel engine.
Treatments for Diesel Engine Cooling Water
Effective diesel engine cooling water treatment involves a combination of chemical additives and system management practices. Here are some common approaches:
Chemical Treatments
- Corrosion Inhibitors: These chemicals form a protective film on metal surfaces to prevent corrosion. Common types include phosphates, chromates (though less common due to environmental concerns), and organic inhibitors.
- Scale Inhibitors: These prevent the formation of mineral deposits (scale) by interfering with the crystallization process. Common agents include polyphosphates, organophosphonic acids, and polymers.
- Dispersants: These keep suspended solids dispersed in the water, preventing them from settling and forming deposits.
- Biocides: These kill or inhibit the growth of microorganisms in the cooling system. Common types include chlorine, bromine, and quaternary ammonium compounds.
System Management Practices
- Regular water analysis: Monitoring water quality parameters like pH, conductivity, hardness, and alkalinity helps in determining the effectiveness of the treatment program.
- Blowdown: Periodically removing a portion of the cooling water helps to concentrate impurities and maintain water quality.
- Filtration: Using filters can help to remove suspended solids from the cooling water.
- Regular inspections: Checking for leaks, deposits, and corrosion is essential for early detection of problems.
It’s important to note that the specific treatment program should be tailored to the water quality, engine type, and operating conditions. Consulting with a water treatment specialist can help in selecting the most appropriate treatment approach.