Answer: d [Reason:] Velox boiler is a forced circulation water tube boiler. In this boiler, the velocity of the flue gas is greater than the velocity of sound, which causes more heat transfer from gas to the water, which increases the steam generation rate. It is mostly used in gas turbine. Due to this reason it is one of the important boilers.

Answer: d [Reason:] When the velocity of gas is greater is greater than speed of the sound, its heat transfer rate also increases. More heat is transferred from the gas to water comparatively when the heat transfer is at subsonic speed. This boiler can increase the heat transfer or can say steam generation rate without increasing boiler size. This is why; Velox boiler is most successful boiler in the gas turbine industries.

Answer: d [Reason:] This boiler uses oil or gaseous fuel inside furnace for its combustion. The combustion gases are circulated through the tubes with supersonic speed velocity to increase the heat transfer rate between the hot gases and feed water.

Answer: a [Reason:] Velox boiler is a forced circulation boiler. It has gas turbine driven air compressor, which compresses the air. This compressed air enters into the vertical combustion chamber; as a result, high rate of heat is released from the fuel, which increases the flue gas velocity up to the sound velocity. In this boiler pump is used to circulate water inside tube.

Answer: c [Reason:] The combustion gas coming out of the super heater is used to run gas turbine which runs at air compressor. The exhaust gases coming out of the gas turbine are passed through the economizer to heat the feed water. Feed water is recirculated with the help of a pump.

Answer: b [Reason:] There are 2 circuits in S-H boiler, in the primary circuit distilled water from the water drum passes through the primary evaporator and steam produced is passed over drum and in secondary circuit, feed pump supplies impure water from hot well to the evaporator drum through feed preheater.

Answer: a [Reason:] Natural circulation is used in the primary circuit of a Schmidt-Hartmann boiler and this is sufficient enough to affect the desired rate of heat transfer and to overcome the thermo-siphon head of height about 2 to 10 meters. This boiler has got 2 pressure cycles.

Answer: c [Reason:] In normal circumstances, replenishment of distilled water in the primary circuit is not required as every care is taken in the design and construction to prevent leakages. But as a safeguard against leakage accidental loss, a pressure gauge and safety valve are fitted in the Schmidt-Hartmann boiler’s circuit.

Answer: c [Reason:] The salts are deposited in the evaporator drum (steam generator) due to the circulation of impure water can be easily cleaned by blowing off the water with pressure or by removing the submerged coil from the drum.

Answer: b [Reason:] There is a rare chance of overheating or the burning of the highly heated components of the primary circuits there is no danger of salt deposition as well as there is no chance of interruption to the circulation either by rust or any other material. The highly heated parts run safe throughout the life of the boiler.

Answer: a [Reason:] The novel feature of the Loffler boiler is to evaporate water solely by means of superheated steam. The furnace heat is supplied only to economizer and super heater. In other words, steam is used as a heat absorbing medium.

Answer: b [Reason:] Major difficulty experienced in La-Mont boiler is deposition of salt and sediment on the inner surfaces of water tubes. The deposition reduces the heat transfer, ultimately, the generating capacity. This difficulty was solved by Loffler boiler by preventing the flow of water into the boiler tubes.

Answer: d [Reason:] Steam coming out of the radiant super heater enters the convection where it is finally heated to the desired temperature of 500oC. The convection superheater receives heat from the flue gases entered by convective heat transfer. Both radiant and convective super heaters are arranged in the series in the path of flue gases.

Answer: d [Reason:] Varying fuel costs have constantly persuaded power engineers to search for more economical methods of power generation. The most recent method is super critical boiler which operated at pressure of 3200psi or 22Mpa therefore facilitates in converting water into steam instantly.

Answer: d [Reason:] The heat transfer rates of supercritical boilers are large compared to any other boilers. The steam side heat transfer of subcritical is 165000 kJ/m²hr^oc when the steam pressure and temperature are 180 bar and 538^oC whereas, the steam side heat transfer coefficients of supercritical boiler is about 2, 20,200 kJ/m²hr^oC when the steam is generated at 240^oC.

Answer: a [Reason:] The simple single pool tidal system has one pool or basin behind a dam that is filled from the ocean at high tide and emptied to it at low tide. Both filling and emptying processes take place during short periods of time.

Answer: a [Reason:] The total tidal power that is dissipated throughout the world is estimated at 2.4 X 10⁶ MW of these some 106 MW are dissipated in shallow seas and coastal areas and are not recoverable. Because of very high cost of dams and other structures associated with tide energy conversion system, only a small amount of the rest can be satisfied by tidal energy.

Answer: a [Reason:] The flow of water in both directions is used to drive a number of reversible water turbines, each driving an electrical generator. Electric power would thus be generated during two short periods each tidal period of 12h, 25min or once every 6h, 12.5 min.

Answer: b [Reason:] In the simple single pool system two high peaks, short duration power outputs occur every tidal period. Such peaks require large turbine-generators that remain idle much of the time. The power peaks also occur at different times every day (50 min later each successive day), at times of high and low tides.

Answer: a [Reason:] Because the average head h is lower and work and power are proportional to h2, turbine generators are much smaller and operate over a much longer period. The resulting total work is reduced.

Answer: b [Reason:] The two pool tidal system is less dependent on tidal fluctuation but is more complex and involves more costly dam construction. An inland basin is enclosed by dam A and is divided into a high pool and a low pool by dam B.

Answer: a [Reason:] The tidal range must be at least 7 meters (23 feet) for a barrage to be feasible. There are only three commercial-size barrage systems operating: one in France (240 MW), one in Nova Scotia (20MW), and one in Russia (500 kW).

Answer: d [Reason:] Any location where fresh river water meets salty ocean water. The word “estuary” is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. Estuaries are critical habitat for spawning and early life cycle stages of many ocean organisms as well as birds.

Answer: d [Reason:] An area has a semidiurnal tidal cycle if it experiences two high and two low tides of approximately equal size every lunar day. Semidiurnal tides may have daily inequity, where successive high tides have different heights.

Answer: c [Reason:] The tidal range is the vertical difference between the high tide and the succeeding low tide. Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

Answer: d [Reason:] Movement of water generated by or associated with the change in mean sea level is called tidal currents. Tidal currents occur in conjunction with the rise and fall of the tide. The vertical motion of the tides near the shore causes the water to move horizontally, creating currents.

Answer: c [Reason:] Movement of water away from the shore is called ebb tide. Ebb tide means the period between high tide and low tide during which water flows away from the shore, the receding or outgoing tide. The period between high water and the succeeding low water.

Answer: c [Reason:] Littoral transport is the term used for the transport of non-cohesive sediments, i.e. mainly sand, along the foreshore and the shore face due to the action of the breaking waves and the long shore currents.

Answer: b [Reason:] Dredging is an excavation activity usually carried out underwater, in shallow seas or freshwater areas with the purpose of gathering up bottom sediments and widening. This technique is often used to keep waterways navigable and creates an anti sludge pathway.

Answer: a [Reason:] One terra-watt is equal to 1 trillion watts. One terawatt hour of energy is equal to a sustained power delivery of approximately 114 megawatts for a period of one year. The watt second is a unit of energy, equal to the joule. One kilowatt hour is 3,600,000 watt seconds.

Answer: c [Reason:] OTEC is caused by solar energy indirectly. Of late harnessing tidal and wave energy has gained momentum. While OTEC has its own limitations, wave and tidal energy conversion systems can generate more energy when compared to solar energy.

Answer: b [Reason:] Ocean thermal energy conversion (OTEC) uses the temperature difference between cooler deep and warmer shallow or surface sea water to run a heat engine and produce useful work, usually in the form of electricity. OTEC can operate with a very high capacity factor and so can operate in base mode.

Answer: b [Reason:] Sihwa Lake Tidal Power Station is the world’s largest tidal power installation, with a total power output capacity of 254 MW. When completed in 2011, it surpassed the 240 MW Rance Tidal Power Station which was the world’s largest for 45 years. It is operated by the Korea Water Resources Corporation.

Answer: b [Reason:] The Kaplan turbine is a propeller type reaction turbine that is usually immersed completely in the fluid it derives energy from. A Kaplan turbine is beneficial in that it is able to operate in lower pressure situations where Pelton or Francis turbines cannot.

Answer: b [Reason:] The tides are one of the sources of energy from the oceans. This energy can be tapped from coastal waters by building dams. Dams entrap the water at high tide and release it at low tide back to the sea.

Answer: b [Reason:] A sluice is a water channel controlled at its head by a gate. A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the sides of the waterway. Sluice gates commonly control water levels and flow rates in rivers and canals.

Answer: b [Reason:] The tides are rhythmic but not constant. They do not occur on a regular daily schedule. Their occurrence is due to balance of forces, mainly the gravitational force of the moon but also that of the sun, both acting together with that of earth to balance the centrifugal force on the water to the earth’s rotation.

Answer: b [Reason:] It takes the Earth an extra 50 minutes to catch up to the moon. Since the Earth rotates through two tidal bulges every lunar day, we experience two high and two low tides every 24 hours and 50 minutes. Here, we see the relationship between the tidal cycle and the lunar day.

Answer: c [Reason:] The tide that occurs when the difference between high and low tides is greatest. It occurs when the moon is new or full. Spring tides result when the gravitation forces of the sun and moon are parallel to one another.

Answer: b [Reason:] A tide that occurs when the difference between high tide and low tide is the least. Neap tides occur when gravitational forces from the sun and moon are at right angles (perpendicular) to one another.

Answer: c [Reason:] The Gorlov helical turbine (GHT) is a water turbine evolved from Darrieus turbine design by altering it to have helical blades/foils. Gorlov turbine can be mounted both vertically and horizontally because it is not directional.

Answer: a [Reason:] Diurnal tides occur when there is so much interference by continents, only one high tide and one low tide occur per day. This diurnal tide has a period of 24 hrs and 50 min. An area has a diurnal tidal cycle if it experiences one high and one low tide every lunar day.

Answer: c [Reason:] The travelling grate stoker may be of chain grate type or bar grate type. These two, differ only in the construction of grate. The chain stoker employs an endless chain which is constructed to form a support for the fuel bed. The traveling grate stoker consists of grate bars carried by steel chains.

Answer: b [Reason:] The chain travels over two sprockets. In both chain type and in bar type stokes. One sprocket is placed at the front end and other sprocket is placed at the rear end of the furnace. The front sprocket is connected to a variable speed driving mechanism.

Answer: d [Reason:] The coal is fed by gravity from a hopper located in front of the stoker. The depth of fuel on the grate is regulated by hand adjusted gate. The speed of the grate varies at the rate at which the coal is fed to the furnace.

Answer: a [Reason:] The combustion control automatically regulates the speed of the grate to maintain the required steam generation rate. The ash containing a small amount of combustible material is carried over the rear end of the stoker and deposited in the ash pit.

Answer: c [Reason:] Depending on type of coal burned, the grate has air openings in the range of 20-40 percent of the total area. The air supply to different parts of the stoker is regulated to meet the changing demand through these sections.

Answer: c [Reason:] The air required for the combustion is supplied through the air inlets situated the below the grate. The secondary air is supplied through the openings provided in the furnace will be above the grate. The combination of primary air and over fire supplied provide turbulence required for rapid combustion.

Answer: a [Reason:] The operator controls rate of burning in different zones to minimize the coke carried over to ash pit. The coal supplied to the grate is regulated either by varying depth of coal on the grate with the help of grate valve and by varying the rate of grate travel.

Answer: d [Reason:] Any type of fuel except caking bituminous coal can be used with travelling grate stoker because of the formation of large percentage of fines resulting in increased carbon loss. The rate of burning of fuel in this stoker is 200 to 300kg/m2 per hour when forced draught is used.

Answer: a [Reason:] Spreader stoker is an over feed type of stoker. The coal burned on this stoker remains partly in suspension and partly on the grate. The spreader stoker consists of variable feeding device, a mechanism for throwing the coal uniformly on the grate and suitable openings for admitting the air.

Answer: a [Reason:] The coal feeding and distribution mechanism is located in the front above the grate of a spreader stoker. A portion of coal is supplied containing fine particles fine particles of coal burns in suspension and remaining falls to the grate.

Answer: b [Reason:] Continuous plants are fed and emptied continuously. They empty automatically through the overflow whenever new material is filled in. therefore, the substance must be fluid and homogeneous.

Answer: a [Reason:] Continuous plants are suitable for rural households as the necessary work fits well into daily routine. Gas production is constant and higher than in batch plants. Today, nearly all biogas plants are operating on a continuous mode.

Answer: d [Reason:] This is one of the common designs in India, coming under category of semi-continuous feed plant. It has a cylindrical floating biogas holder on top of the well shaped digester. This digester is vividly used in rural sides.

Answer: c [Reason:] As the biogas is produced in the digester, it rises vertically and gets accumulated and stored in the biogas holder at a constant pressure of 8-10 cm of water column. The biogas holder is normally designed to store 50% of the daily gas production.

Answer: c [Reason:] The plant based on fixed dome concept was developed in India in the middle 1970s. The Chinese fixed plants use a seasonal crop wastes as the major feed stock for feeding, therefore, their design is based on principle of semi-batch-feed digester.

Answer: a [Reason:] The Indian fixed dome plant design use the principle of displacement of slurry inside the digester for storage of biogas in the fixed gas storage chamber. Indian fixed dome biogas digesters are designed for pressure inside the plant varying from 0 to 90 cm of water column.

Answer: b [Reason:] The discharge opening is located on water wall surface of the outlet displacement chamber and it spontaneously controls the maximum pressure. It is best suited for batch process especially when daily feeding is adopted in small quantities.

Answer: a [Reason:] Main unit of the plant including the digester is fabricated by using rubber, high strength plastic, neoprene or red mud plastic. The inlet and outlet are made of heavy duty PVC tube. A small pipe of same PVC tube is fixed on top of the plant as gas outlet pipe.

Answer: a [Reason:] Flexible bag biogas plant is portable and can easily be erected. It requires support from outside, upto the slurry level, to maintain the shape as per its design configuration, which is done by placing the bag inside a pit dug on site.

Answer: a [Reason:] The depth of the pit should be in proportion to height of the digester so that the mark of initial slurry level is in line with the ground level. The outlet pipe is fixed in such a way that its outlet opening is also in line with the ground level. Some weight has to be added on the top of the bag to build the desired pressure to convey the generated gas to the point of utilization.

Answer: a [Reason:] Advantage of flexible bag plant is that the fabrication can be centralized for mass production. Individuals or agencies having land and basic infrastructure can take up fabrication of the biogas plant with small investment.

Answer: c [Reason:] Khadi and village industries type biogas plant (KVIC) is an example of Floating drum biogas plant. It is a semi continuous plant. It is one of the most common types of biogas plant used in rural area of India.

Answer: a [Reason:] The KVIC (Khadi and village industries biogas plant) model is a floating holder semi continuous fed bio gas plant and has two types, (I) Vertical and (II) Horizontal. The vertical type is more commonly used and the horizontal type is used only in the high water table region.

Answer: a [Reason:] Foundation of a KVIC is compact base made of a mixture of cement concrete and brick ballast. The foundation is well compacted using wooden ram and then top surface is cemented to prevent any percolation & seepage.