Induced draught

These applications have considerably more stringent performance requirements than any other application. Circulating water pumps, boiler feed pumps, forced-draught (FD) and induced-draught (ID) fans, pulverizers (ball mills) and condensate pumps are components in a thermal power station that may require extra safety in a standard motor to make it able to fulfil these requirements and withstand abnormal service conditions and system disturbances. Abnormal operating conditions may be one or more of the following ... 

It is generally difficult to eliminate all the droplets leaving with the air flow so that in induced draught designs, these droplets are likely to enter the fan system with the possibility of erosion and corrosion and damage to the fan. 

Some coal-fired kilns used arches to create voids into which coal batches were projected, either manually or mechanically. Shaft diameters of up to 4.5 m were used, but output rates, even with impressed air and induced draught were only 150 t/d. 

At very high tip speeds of blowers, the rubber/FRP lining can come off exposing the blower to corrosive gases. Please discuss with party who will carry out the lining job. This problem can arise in case if induced draught fans of pollution control units. 

Provide induced draught fans and scrubbers for necessary equipments to suck out any toxic and inflammable vapours in working areas (e.g. electrolysis cells for chlorine/caustic soda plants). 

An air pollution control system was designed for a waste disposal plant with venturi scrubber, two packed towers with cold water and alkali solution, an ESP, and an induced draught fan discharging through a 45-m-tall chimney. 

It is desirable to have diesel generators sets of sufficient capacity as stand by the soiurce of power with automatic change over faciUly. These shall be used for operating equipment for emergency use such as alkali circulation pumps and induced draught fans for scrubbers, refrigeration units (to prevent escape of volatile solvents), fire hydrant pumps, boiler feed water pumps, and plant lighting. 

A coal-, oil-, or a gas-fired boiler will not be a WHRB. It will need separate air pollution control systems such as dust separators, electrostatic precipitators, induced draught fans, and a tall chimney for the exit gases from the boiler. Comparison of water-tube and smoke-tube boilers. 

Induced draught created by a fan can blow away the moist air more upwards — but it will need power to operate the fan (fibreglass reinforced plastic blades are preferred). 

Extensive laboratory analysis and statutory permission are necessary to decide whether these can be used as industrial fuel or sent to destruction by incineration. The flue gases produced when this type of fuel is burnt may contain considerable pollutants. They need air pollution control system having venturi scrubbers, packed towers, electro static precipitators, induced draught fans and a tall chimney. 

Forced draught (FD) and induced draught (ID) fans It may be considered for handling large gas volumes of the flue gases and discharging through a taU chimney. The ID fans shall be fabricated from corrosion- and erosion-resistant MOC. 

But a difference of even 5 gin a vane of a high-speed impeller can imbalance it and damage a costly mechanical equipment such as a turbine or an induced draught fan. Likewise, an impurity of even a few ppm can spoil a pharmaceutical intermediate. 

Air pollution control (APC) alkali absorber Induced draught fans for areas of chlorine handling area, near electrolytic cells This is required for the absorption of free chlorine/HCl and for removal of any CI2 leak HCl gas will be released in the atmosphere working area becomes suffocating and dangerous if CI2 is not removed Keep gas detectors for CI2, HCl 200 % spares for absorber and ID fans... 

Need an induced draught (ID) fan which can create sufficiently strong suction throughout the plant (it should be able to overcome the pressure drops in aU units and connecting ducts). 

The major area of potential environmental impact in this industry is emissions to air. Fugitive emissions from the dryer and kiln processes can, under normal conditions, be considered minimal. Kilns operate under slight negative pressure, using induced draught fans. 

Route of pipelines must avoid electrical cables, heavy traffic, hot areas Detectors and warning devices for CO leak Flameproof fittings, photocell-actuated gas control valves Induced Draught (ID) fans and tail gas scrabbers (if the gases contain H2S or other sulphurous compounds)... 

Possibility of air pollution due to SO2 in stack gases and corrosion of gas ducts and induced draught fans since moisture is also present due to burning of hydrocarbons. 

Type of coohng tower dranght required natiual/forced/induced (induced draught type is preferable). 

Sand blasting of the surface may be permitted if sufficient personal protective devices and ventilation by Forced Draught (FD) fans, dust removal Induced Draught (ID) fans are used. However, workers should not enter the vessel when this is being done. 

Induced-draught artificial ventilation by axial-flow fans mounted on the roof and fitted with sound attenuators on their outlets. The air for cooling the interior of the building enters through openings at the base, these likewise being provided with attenuators (Fig.20). 

Fig.20 Induced-draught ventilation of a mill building air extracted by fans...

The total system shall be maintained under negative pressure at all times with respect to the building, to enhance the effectiveness of the static barrier for preventing the dispersion of radioactive materials into the incinerator building in the event of an accidental leak in the equipment. This dynamic barrier is provided by the incineration system s exhaust or induced draught fan. When a positive pressure is essential as a process requirement in a part of the incineration system, special precautions shall be taken to ensure that leakage beyond the static barrier cannot occur. 

Induced draught fans shall be used to maintain a negative pressure in the total system. Radial fans are the preferred type of off-gas fan. Control of the off-gas fans may be ensured by throttle dampers or by frequency control of the electric motor. The casing and frame of the off-gas fans shall be made of steel or special alloys if necessary. The fan casing should be provided with a condensate drain at its lowest point. Vibration monitors should be provided on the induced draught fans. 

Figure A1.5 Typical scheme of coal-fired thermal power plant (AuthorAJser BillC https // commons.wikimedia.org/wiki/File PowerStation2.svg website approached January 26, 2016) (1) Cooling tower (2) cooling-water pump (3) transmission line (3-phase) (4) step-up transformer (3-phase) (5) electrical generator (3-phase) (6) low-pressure (LP) steam turbine (7) condensate pump (8) surface condenser (9) intermediate-pressure steam turbine (10) steam control valve (11) high-pressure (HP) steam turbine (12) deaerator (13) feedwater heater (14) coal conveyor (15) coal hopper (16) coal pulverizer (17) boiler steam drum (18) bottom ash hopper (19) superheater (20) forced draught (draft) fan (21) reheater (22) combustion air intake (23) economizer (24) air preheater (25) precipitator (26) induced-draught fan and (27) flue gas stack.

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