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Marine Growth Protection System (MGPS)


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Marine Growth Protection System (MGPS) for Ships

Published in: Education

Marine Growth Protection System (MGPS)

  1. 1. Marine Growth Protection System (MGPS) Image Credit: Mohammud Hanif Dewan, Maritime Lecturer & Trainer, Bangladesh
  2. 2. Marine Growth: Sea water contains both macro and micro marine organisms such as sea worm, molluscs, barnacles, algae, hard shells like acorn barnades etc. These organisms stick to the surface of the ship and flourish over there, resulting in marine growth. Effects of Marine Growth The fouling problem arises when barnacles, mussels and other lower forms of marine life as larvae enter pipework systems and settle on the internal surface of pipes where they rapidly grow and multiply. In the most extreme cases, complete seawater lines can become blocked, affecting the safety and operational capability of the ship. In other instances, the gradual restriction in the flow of seawater through cooling systems can impair engine efficiency, leading to increased fuel usage. As the marine organisms flourish they block and narrow the passage of cooling water in the ship’s system resulting in the following factors: – Impairing the heat transfer system. – Overheating of several water-cooled machineries. – Increase in the rate of corrosion and thinning of pipes. – Reduced efficiency which can lead to loss of vessel speed, increase fuel uses and loss of time.
  3. 3. Without MGPS With MGPS Image Credit:
  4. 4. Fighting Marine Growth: To avoid formation of marine growth MGPS or marine growth preventive system (MGPS) is used onboard ship. Image Credit: Fig: MGPS in Engine room sea water system
  5. 5. MGPS and Anodes Image Credit:
  6. 6. Marine Growth Protection System (MGPS) Working Principle: • MGPS is based on the electrolytic principle and consists of copper, aluminium and ferrous anodes which are fed with an impressed electrical current from a control panel. • The anode are usually mounted in pairs in the ship’s sea chest or strainer where they are in direct contact with the flow of water entering the seawater lines. Also the anodes can be mounted on independent treatment tank for other convenience. • In operation, the copper anode produces ions which are transported by the seawater and carried into the pipework system and equipment beyond. • Although the concentrations of copper in solution are extremely small i.e. less than 2 parts per billion they are sufficient to prevent marine life from setting and multiplying. • At the same time, the slow dissolution of the aluminium / ferrous anode produces ions which spread throughout the system and produce an anti- corrosive layer on the internal surface of pipes.
  7. 7. MGPS- Chlorination System • This system is designed to prevent the adhesion of marine growths to the internal pipe line of ships through the chemical reaction of chlorine compounds which are produced through the electrolyzation of sea water. • First, the sea water taken out of the outlet of one of the common sea water pumps or the pump for exclusive use in MGPS is led into the Generating Chamber, in which the sea water is electrolyzed with specially designed electrodes. Then the sea water containing chlorine compounds is injected into scoop or sea chests through the nozzles to mix with the sea water sucked in from outside of the ship, thus preventing marine growths from adhering to the interior of the ship's sea water line including sea chest, piping and heat exchanger.
  8. 8. How it works: - The anti-fouling process is based on the electrolysis of part of the sodium chloride (NaCl) contained in sea water. The electrolysis is obtained by passing the sea water through a generating chamber containing electrode(Ti anode). - The chemical and electrochemical reactions which occur in the generating chamber are as follows: 1) at the anode free chlorine is formed 2 Cl ⇔ Cl₂ + 2e- 2) at the cathode OH-ions are formed 2 H2O + 2e- ⇔ 2 OH-+ H3 3) around the anode the OH- ions react with the Na+ ions and Cl2 to produce sodium hypochlorite 2 NaOH + Cl₂ ⇔ NaOCl + NaCl + H2O
  9. 9. - Alongside these principal reactions which bring about the production of sodium hypochlorite, secondary reactions occur due to the actions which are present in sea water such as calcium and magnesium, forming hydrates and carbonates. - The sodium hypochlorite solution leaving the generating chamber is piped to the chlorine injection points situated on the sea chests to be mixed with the incoming sea water flow. - Then the chlorine-active contained in the solution oxidizes the organic substances found in sea water. - The adult organisms, for example mussels, are able to resist the effects of chlorine-active by closing themselves inside their shells. However unable to feed they will not settle in an environment where chlorine-active is present.
  10. 10. Image Credit: Fig: MGPS (Chlorination System) Pipings
  11. 11. Effects of Chlorine • Chlorine is a well known toxicant. It has been shown that 0.2 to 0.5 PPM of continuous chlorination will prevent all marine fouling in time. Higher than 0.5 PPM might produce the corrosion of the metallic piping, and other metallic Equipment. • A trace residual discharge will insure the killing of all fouling organisms in a sea water system when constant chlorination is employed. It should be emphasized that constant chlorination is the best method for safe and efficient fouling and bacteria control.
  12. 12. Advantages of Using MGPS 1. Based on the electrolytic principle, providing continuous and reliable protection from marine growth without the use of chemicals. 2. A dual system combining pipework anti-fouling and corrosion suppression. 3. Environmentally safe. Meets all environmental protection standards 4. Reduces energy consumption 5. Maintains plant and equipment at high efficiency 6. Reduces cleaning costs of pumps, pipes, valves, sea chests, gratings, heat exchangers, etc. 7. Improved heat transfer in heat exchangers 8. Increases life span of plant and equipment 9. Provides continuous maintenance free protection for years 10. Lower capital and operating costs than any competing technology
  13. 13. References: 1. 2. 3. 4. Marine Auxiliary Machinery, Seventh Edition Paperback by H D Mc George 4. General Engineering Knowledge for Marine Engineers (Reeds-8).