Section 220.30 Thermal Dryers

Section 220

Section 220.30  Thermal

Dryers

a)         Thermal dryers; general.

All dryer systems used for drying coal at high temperatures,

hereinafter referred to as thermal dryers, including without limitation, rotary

dryers, continuous carrier dryers, vertical tray, and cascade dryers,

multilouver dryers, suspension or flash dryers, and fluidized bed dryers, shall

be maintained and operated in accordance with the provisions of Section

220.30(b) through (f).

b)         Dryer heating units; operation.

1)         Dryer heating units shall be operated to provide reasonably

complete combustion before heated gases are allowed to enter hot gas inlets.

2)         Dryer heating units which are fired by pulverized coal, shall

be operated and maintained in accordance with the recommended standards set

forth in the National Fire Protection Association Handbook, 12th Edition,

Section 9, "Installation of Pulverized Fuel Systems," 1962.

c)         Bypass stacks.

Thermal dryer systems shall include a bypass stack, relief

stack, or individual discharge stack provided with automatic venting which will

permit gases from the dryer heating unit to bypass the heating chamber and vent

to the outside atmosphere during any shutdown operation.

d)         Hot gas inlet chamber dropout doors.

Thermal dryer systems which employ a hot gas inlet chamber

shall be equipped with drop-out doors at the bottom of the inlet chamber or

with other effective means which permit coal, fly-ash, or other heated material

to fall from the chamber.

e)         Explosion release vents

hamber and vent

to the outside atmosphere during any shutdown operation.

d)         Hot gas inlet chamber dropout doors.

Thermal dryer systems which employ a hot gas inlet chamber

shall be equipped with drop-out doors at the bottom of the inlet chamber or

with other effective means which permit coal, fly-ash, or other heated material

to fall from the chamber.

e)         Explosion release vents.

Drying chambers, dry-dust collectors, ductwork connecting

dryers to dust collectors, and ductwork between dust collectors and discharge

stacks shall be protected with explosion release vents which open directly to

the outside atmosphere, and all such vents shall be:

1)         Hinged to prevent dislodgment;

2)         Designed and constructed to permit checking and testing by

manual operation; and

3)         Equal in size to the cross-sectional area of the collector

vortex finder where used to vent dry dust collectors.

f)         Access to drying chambers, hot gas inlet chambers and

ductwork; installation and maintenance.

Drying chambers, hot gas inlet chambers and all ductwork in

which coal dust may accumulate shall be equipped with tight sealing access

doors which shall remain latched during dryer operation to prevent the emission

of coal dust and the loss of fluidizing air.

g)         Fire protection.

Based on the need for fire protection measures in connection

with the particular design of the thermal dryer, an authorized representative

of the Department may require any of the following measures to be employed:

1)         Water sprays automatically actuated by rises in temperature to

prevent fire, installed inside the thermal dryer systems, and such sprays shall

be designed to provide for manual operation in the event of power failure.

2)         Fog nozzles, or other no less effective means, installed

inside the thermal dryer systems to provide additional moisture or an

artificial drying load within the drying system when the system is being

started or shut down

ature to

prevent fire, installed inside the thermal dryer systems, and such sprays shall

be designed to provide for manual operation in the event of power failure.

2)         Fog nozzles, or other no less effective means, installed

inside the thermal dryer systems to provide additional moisture or an

artificial drying load within the drying system when the system is being

started or shut down.

3)         The water system of each thermal dryer shall be interconnected

to a supply of compressed air which permits constant or frequent purging of all

water sprays and fog nozzles or other no less effective means of purging shall

be provided.

h)         Thermal dryers; location and installation; general.

1)         All thermal dryer systems erected or installed at any coal

mine shall be located at least one hundred (100) feet from any underground coal

mine opening, and one hundred (100) feet from any surface installation where

the heat, sparks, flames, or coal dust from the system might cause a fire or

explosion.

2)         All thermal dryer systems erected or installed may be covered

by roofs; however, such systems shall not be otherwise enclosed unless

necessary to protect the health and safety of persons employed at the mine.

Where such systems are enclosed, they shall be located in separate fireproof

structures of heavy construction with explosion pressure release devices (such

as hinged wall panels, window sashes, or louvers), which provide at least one

y be covered

by roofs; however, such systems shall not be otherwise enclosed unless

necessary to protect the health and safety of persons employed at the mine.

Where such systems are enclosed, they shall be located in separate fireproof

structures of heavy construction with explosion pressure release devices (such

as hinged wall panels, window sashes, or louvers), which provide at least one

(1) square foot of area for each eighty (80) cubic feet of space volume and

which are distributed as uniformly as possible throughout the structure.

i)          Structures housing other facilities; use of partitions.

All thermal dryer systems installed in any structure which

also houses a tipple, cleaning plant, or other operating facility shall be

separated from all other working areas of such structure by a substantial

partition capable of providing greater resistance to explosion pressures than

the exterior wall or walls of the structure.  The partition shall also include

substantial, self-closing fire doors at all entrances to the areas adjoining

the dryer system.

j)          Visual check of system equipment.

Frequent visual checks shall be made by the operator of the

thermal dryer system control station, or by some other qualified person, of the

bypass dampers, air-tempering louvers, discharge mechanism, and other dryer

system equipment.

k)         Control stations; location.

All thermal dryer system control stations shall be installed

at a location which will give to the operator of the control station the widest

field of visibility of the system and equipment.

l)          Control panels.

1)         All thermal dryer system control panels shall be located in an

area which is relatively free of moisture and dust and shall be installed in

such a manner as to minimize vibration

dryer system control stations shall be installed

at a location which will give to the operator of the control station the widest

field of visibility of the system and equipment.

l)          Control panels.

1)         All thermal dryer system control panels shall be located in an

area which is relatively free of moisture and dust and shall be installed in

such a manner as to minimize vibration.

2)         A schematic diagram containing legends which show the location

of each thermocouple, pressure tap, or other control or gauging instrument in

the drying system shall be posted on or near the control panel of each thermal

drying system.

3)         Each instrument on the control panel shall be identified by a

name-plate or equivalent marking.

4)         A plan to control the operation of each thermal dryer system

shall be posted at or near the control panel showing a sequence of startup,

normal shutdown, and emergency shutdown procedure.

m)        Alarm devices.

Thermal dryer systems shall be equipped with both audible and

visual alarm devices which are set to operate when safe dryer temperatures are

exceeded.

n)         Fail safe monitoring systems.

Thermal dryer systems and controls shall be protected by a

fail safe monitoring system which will safely shut down the system and any

related equipment upon failure of any component in the dryer system.

o)         Wet-coal feedbins; low-level indicators.

Wet-coal bins feeding thermal drying systems shall be

equipped with both audible and visual low-coal-level indicators.

p)         Automatic temperature control instruments.

1)         Automatic temperature control instruments for thermal dryer

system shall be of the recording type.

2)         Automatic temperature control instruments shall be locked or

sealed to prevent tampering or unauthorized adjustment.  These instruments

shall not be set above the maximum allowable operating temperature

l-level indicators.

p)         Automatic temperature control instruments.

1)         Automatic temperature control instruments for thermal dryer

system shall be of the recording type.

2)         Automatic temperature control instruments shall be locked or

sealed to prevent tampering or unauthorized adjustment.  These instruments

shall not be set above the maximum allowable operating temperature.

3)         All dryer control instruments shall be inspected and

calibrated at least once (1) every three (3) months and a record or certificate

of accuracy, signed by a person qualified to inspect and calibrate such

instruments shall be kept at the plant.

q)         Thermal dryers; examination and inspection.

Thermal dryer systems shall be examined for fires and

coal-dust accumulations, if the dryers are not restarted promptly after a

shutdown.