20451. In which of the waste heat recovery equipment, the flow of flue gas and air is alternately reversed after a fixed interval of time ?
20452. An electric furnace producing heat by means of an electric arc struck between each of three electrodes and the charge is called __________ furnace.
20453. Turndown ratio of a burner gives an idea of the __________ in the furnace.
20454. In low or standard frequency induction furnace, heat is produced by the
20455. Which furnace employs natural draft ?
20456. Test specimen for determination of refractoriness under load (RUL) of a refractory is heated in a
20457. Regenerators compared to the recuperators for the same duty
20458. Regenerators are used for waste heat recovery in
20459. Which of the following furnaces will have maximum thermal efficiency ?
20460. Heat transfer takes place through a liquid medium surrounding the submerged material under heating, in case of a/an
20461. The heating capacity of muffle furnace depends on the
20462. Which of the following is a batch furnace ?
20463. In a heating process, a heat flow diagram in which the quantities of heat in the various items of a heat balance are represented by the width of a band is called the
20464. Maximum thermal efficiency of boiler may be about __________ percent.
20465. Rotary kilns are used in the
20466. The method of Lobo and Evans is concerned with the calculation of the
20467. Reverberatory furnace is used for
20468. Overall thermal efficiency of a lumpy coal fired suitably designed heating furnace, if operated & maintained properly may be about __________ percent.
20469. In furnaces operating at very high temperature (say) 1250°C, e.g. soaking pit), the maximum heat transfer takes place by
20470. Which of the following is a directly fired intermittant furnace ?
20471. Dampers are located
20472. Protective gas used in the annealing furnace for steel coil comprises of
20473. Out of the following fuels used in a furnace exhausting flue gas at a temperature of 600°C, the percentage stack loss will be maximum in case of complete combustion of
20474. Scaling of furnace stock is reduced by __________ in flue gas.
20475. __________ furnace is not an electric furnace.
20476. Forced recirculation of furnace gases is practised
20477. Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the
20478. Air filtration in a furnace
20479. Which of the following is the most important deterrants to an extended use of pulverised coal in boiler firing ?
20480. Which of the following is a periodic furnace?
20481. Regenerators are normally provided in the
20482. Metallic recuperators are not used for waste heat recovery, if the hot flue gas temperature is above __________ °C, because corrosion prevails at higher temperatures.
20483. Furnace pressure is normally controlled by regulating the
20484. An example of indirectly heated furnace is the
20485. Specific heating capacity of a furnace is expressed as
20486. The main function of a muffle in the muffle furnace is to
20487. Flue gas outlet temperature from the chimney of any furnace should be ideally about __________ °C.
20488. Very high pressure boilers are usually __________ boilers.
20489. Heat transfer rate to the charge/stock in a furnace does not depend upon the
20490. Heat balance of furnace provides means of determining the
20491. Thermal efficiency of furnaces can be improved by
20492. Shaft furnaces are used for
20493. Hearth furnaces are not used for
20494. Turn down ratio of a burner
20495. Which of the following is not a continuous waste heat recovery equipment from the flue gases going out of furnace ?
20496. In salt bath furnace, heat is transferred to the charge mainly by
20497. In order to maintain an oxidising atmosphere in a furnace, it should have
20498. Combustion of fuel in a furnace with oxygen enriched air results in higher
20499. Reducing atmosphere is maintained in a
20500. Presence of SO2 in furnace gases attacks the ferrous metal by way of