MARINE POLLUTION , SOURCES AND EFFECTS OF MARINE POLLUTION :

Marine Pollution is defined as, " the discharge of waste substances into the sea resulting in harm to living resources, Hazards to human health, hindrance to fishery and impairment of quality for use of sea water."

SOURCES (OR) CAUSES OF MARINE POLLUTION :

1. Dumping the wastes.

The most serious issue is dumping of untreated wastes and sewage into oceans by the coastal towns and cities and industrial units. All That what is carried by rivers ultimately ends up in the seas. On their way to sea, rivers receive huge amounts of sewage, garbage, agricultural discharge, pesticides, including, heavy metals. These all are added to sea. Huge quantity of plastic is being dumped in sea.

2. Oil Pollution of Marine Water :

The great damage to water is imposed by petroleum and its products.

Heavy petroleum products precipitate to the bottom or are adsorbed on rock, stone, and sand banks to inhibit the life of the hydrobionts. One drop of petroleum spreads over a great area to isolate the water from contact with atmospheric oxygen.

Effects of Marine Pollution :

i) Presence of heavy metals and organic pollutants cause more damage in birds as thinning of eggshell and tissue damage of an egg.

ii) Oil Pollution cause damage to marine fauna and flora including algae, fish, birds, invertebrates. About 50,000 to 2,50,000 birds are killed every year by oil.

iii) Oil spilling in sea water causes abnormally low body temperature in birds resulting in hypothermia. Nearly 150 rare species of bald eagles also became victims when they ingested oil during Exxon Valdez accident.

iv) Oil films are able to retard significantly the rate of oxygen uptake by water.

v) The continuous oil films inhibit photosynthesis and formation of oxygen. This inhibits the growth of plankton, which is the main source of the hydrobionts inhabiting the water body.

vi) Hydrocarbons and benzopyrene accumulate in food chain and consumption of fish by man may cause cancer. Detergents used to clean up the spill are also harmful to marine life.

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THROTTLE GOVERNING OF STEAM TURBINES

Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the turbine constant at part load and hence this method of governing is called "Throttle Governing". Construction : Throttle governing system consists of a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber. Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movement of the

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Electrical Comparators are used as a means of detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a roll. The object to be checked is place

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Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.

Mechinopedia For Mechanical Engineers

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