This set of Energy Engineering Assessment Questions and Answers focuses on “Problems Associated with Geothermal Conversion”.
1. How are solids present in steam and water of geothermal energy removed?
b) De-sanding Hydro clones
c) Centrifugal separators
d) Gravity setting
Explanation: Steam and water from both hydrothermal systems contain along with the dissolved solids in the water, entrained solid particles and non-condensable gases. The entrained solids must be removed as much as possible, usually by centrifugal separators at the well head, before they enter plant equipment and strainers.
2. How do Non-condensable gases escape from geothermal plant?
a) Air vents
b) Trap holes
c) Condenser ejectors
d) Centrifugal Filters
Explanation: The non condensable gas content varies from 0.2 – 0.4 percent depending upon the particular well and its age. The non condensable themselves are mostly CO2 plus varying amount of methane CH4, hydrogen H2, nitrogen, ammonia and hydrogen sulfide. Besides finding way with the fluid into the plant equipment the non condensable partly escape to atmosphere via condenser ejectors.
3. Non condensable are environmentally undesirable because __________
a) tare not soluble
b) they contain Solid particles
c) they partly escape into atmosphere
d) they damage the machineries
Explanation: Non condensable are environmentally undesirable because they partly escape into the atmosphere. Most are corrosive in the normal damp atmosphere of the plant and are noxious and toxic and hence major pollutants.
4. Which is the environmental problem caused by geothermal energy?
b) Loose soil
c) Land surface subsidence
d) Loss of fertility of land
Explanation: Environmental problem caused by geothermal plants is land surface subsidence because of the extraction of large quantities of underground fluids. Large extractions and re-injections also pose possibility of seismic disturbances.
5. What is the material used for building turbines in geothermal plant?
a) Chrome steel
b) Bronze alloys
c) Cast iron
d) Copper alloys
Explanation: In the turbine, steam nozzles and blades are subjected to dry or high quality steam is usually made of 11 to 13 percent chrome steel. The nozzles are usually designed with large throat areas o a wide pitch to minimize scaling.
6. Which material is recommended for condensate pipes?
a) Cast iron
Explanation: Aluminum is recommended for condensate pipes and valves that are made large enough to allow low velocities and hence erosion. Aluminum is also recommended for switchyard structures that are in the open but in a generally corrosive atmosphere.
7. Which gas is always present in geothermal fields?
Explanation: H2S (Hydrogen Sulfide) is always present in geothermal field. If this gas is present in excess quantities may cause harmful effects on the bearings. This also attacks electrical equipments and it may have adverse effects on corps and on river life.
8. Which process could avoid discharging large quantities into the river?
b) Centrifuge distillation
Explanation: Re-injection could avoid discharging large quantities of heat into rivers, with consequent hazards to fisheries, and would also avoid infecting rivers and stream with toxic substances emitted from the bores which would endanger downstream with toxic substances, water supplies and farming activities.
9. Which among the following is problem caused by geothermal plant?
a) Land usage
b) Noise pollution
c) Global warming
d) Greenhouse effect
Explanation: Noise pollution is another problem. Exhausts, blow downs and centrifugal separation are some sources off noise pollution that necessitate the installation of silencers on some equipment. The noise causes a serious health hazards.
10. Which of the following can affect the fisheries in river?
a) Heat pollution
b) Noise pollution
c) Land erosion
d) Air borne poisons
Explanation: Heat pollution in river water can damage fisheries and encourage growth of unwanted water weeds. Possible remedies include re-injection of surplus cooling tower water and unwanted bore water, the generation of additional power by means of binary fluid cycles etc.
11. Does harnessing of geothermal energy cause earthquakes.
Explanation: Some fears have been expressed that prolonged geothermal exploitation could trigger off earth quakes especially if reinjection is practiced in zones of higher shear stresses where fairly large temperature differentiation occurs.
12. How many known geothermal areas are there in India?
Explanation: There are about 340 known geothermal areas in India, each represented by hot or warm springs. Many more areas are being discovered and reported, in the 12 well defined geothermal provinces.
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