Plant Systems Quiz #3

Question 1

The ______ is the best cycle in terms of thermal efficiency.

Answer 1

Carnot Cycle

Question 2

In a supercritical cycle/system the less fuel consumption is observed because the biggest heat was eliminated which is the ______.

Answer 2

latent heat of vaporization

Question 3

In Reheat cycle, the ______ is the steam that goes back to the boiler (reheater) and then goes to the ______ as a ______ steam.

Answer 3

cold reheat steam, IP turbine, hot reheat

Question 4

In a close heater (FW heater) the ______ temperature is higher than the ______ temperature of the extracted steam that supplies the heater.

Answer 4

feedwater outlet, condensate outlet

Question 5

A ______ is also a ______ where distinction between ______ and ______ phases do not ______.

Answer 5

supercritical water, supercritical fluid, liquid, gas, exist

Question 6

Rankine cycle is more stable than Carnot cycle because three (3) stable points of the cycle which are ______, ______, and ______, compared to Carnot it has only ______ stable conditions.

Answer 6

saturated liquid @ Pcondenser, saturated vapor @ Pboiler, and saturated liquid @ Pboiler, two

Question 7

Furnace enclosure designs for ______ (SC), ______ (USC), and ______ (A-USC) are of temperatures (degC); ______, ______, and ______ respectively.

Answer 7

supercritical, ultra supercritical, advanced ultra supercritical, 540, 600, 700

Question 8

______, a gentleman from Glasgow in 1855 develop a power cycle that is the basis of Thermal Power Plant steam cycles today.

Answer 8

William Rankine

Question 9

The famous Combined Cycle is a ______ as the higher cycle and a ______ as the lower cycle.

Answer 9

Brayton Cycle, Rankine Cycle

Question 9

Multi-stage reheating is possible but not practical. One major reason is because the vapor exiting the turbine exhaust will be ______ at higher temperature thus ______ ______.

Answer 9

superheated vapor, decreases, thermal efficiency

Question 10

In a ______ boiler system in order to prevent economizer ______ damage, a recirculating valve is installed between the ______ tube and the _______, while in a supercritical ______, a ______ _______ pump is installed between the connecting ______ and the ______.

Answer 10

subcritical, tube, downcomer, economizer, steam generator system, boiler, circulation, sphere, economizer

Question 11

In a power plant, there is no ______ steam, the only use is in the following ______ and ______ to become ______ steam then passing different stages at constant pressure and temperature, namely; ______, ______, ______, ______.

Answer 11

saturated, roof, walls, superheated, low-temperature superheater, SH DIV panel, SH platen, SH final (Final Superheater)

Question 12

Modern coal-fired power plants operate between ______ degC to ______ degC and pressure larger than ______ bars.

Answer 12

375, 700, 221

Question 13

14. Supercritical region is defined by ______ MPa and ______ degC.

Answer 13

22.1, 374

Question 14

Three Basic Improvements to have a higher Rankine Cycle Efficiency:

Answer 14

a.) Superheat the steam entering the turbine
b.) Lower down condenser pressure
c.) Increase boiler pressure

Question 15

The advantage of regenerative Rankine cycle is at lower temperature heat is added.

Answer 15

FALSE

Question 16

In a supercritical system, the power block is called Boiler, Turbine, Generator.

Answer 16

FALSE

Question 17

An open feedwater is basically a mixing chamber. Ideally, the mixture leaves the heater as saturated liquid at extraction steam pressure.

Answer 17

TRUE

Question 18

The disadvantage of Reheat Rankine is the steam quality effluent of the low-pressure turbine can be kept very high.

Answer 18

FALSE

Question 19

Having plenty of extractions in the power plant cycle saves more fuel because it heats better the feedwater heater.

Answer 19

FALSE

Question 20

In supercritical point, steam and water cannot be distinguished.

Answer 20

TRUE

Question 21

The operational flexibility of Supercritical technology is shorter start-up time because it operates at lower hg (enthalpy vapor state) and hf (enthalpy liquid state) of steam and water.

Answer 21

FALSE

Question 22

Regenerative cycle is enough to have a better efficiency for big capacity Power Plant.

Answer 22

FALSE

Question 23

A close feedwater heater operates at different pressures of extracted steam and feedwater. It also operates in higher pressures.

Answer 23

TRUE

Question 24

Pump is not required for all close feedwater heaters.

Answer 24

FALSE

Question 25

If the exponent n, in PVn is equal to k, then the polytropic process is an isentropic process only if it is reversible in nature.

Answer 25

TRUE

Question 26

The Otto Cycle is S-V-S-V cycle (ERCA) and the Diesel Cycle is S-P-S-P cycle (ERCA), thus the Diesel cycle is more fuel efficient because of addition of heat is at constant pressure which is equivalent to a higher temperature addition in the cycle.

Answer 26

TRUE

Question 27

Simplifying the SSSF for a heat exchanger, it arrives to an equation, q = h2 – h1.

Answer 27

FALSE

Question 28

According to IUPAC, an extensive quantity is one whose magnitude is independent of the size of the system whereas an intensive quantity is one whose magnitude is additive for subsystems.

Answer 28

FALSE

Question 29

It must be noted, according to the first law of thermodynamics, not all heat provided to a cycle can be transformed into an equal amount of work, some heat rejection must take place.

Answer 29

FALSE

Question 30

An isothermal process is a thermodynamic process, in which the temperature of the system remains constant (T = constant). It is also called the Boyle’s Law.

Answer 30

TRUE

Question 31

In many thermodynamic analyses, it is convenient to use the enthalpy instead of the internal energy. Especially in the case of the First Law of Thermodynamics.

Answer 31

TRUE

Question 32

A quasi-static process is opposite of an adiabatic process, where in quasi-static process is infinite slowness is its characteristic feature, while adiabatic process is a thermodynamic process in which there is no heat transfer into or out of the system (Q = 0), in very rapid processes.

Answer 32

TRUE

Question 33

The exponent, n, is known as the polytropic index and it may take on any value from 0 to ∞, depending on the particular process. If n = ∞, then it is an isometric process.

Answer 33

TRUE

Question 34

During the throttling process, no work is done by or on the system (dW = 0), and usually there is no heat transfer (adiabatic) from or into the system (dQ = 0). On the other hand, the throttling process can be isentropic, it is a fundamentally reversible process.

Answer 34

FALSE