Great American Equipment Company

Stock Number K12863

Kiln
ACTUAL PHOTO

  

Kiln Specifications

TYPE Model USA-27

Front Loaded Chamber Kiln

FUNCTION Technical Ceramic Products

KILN CAPACITY 27 Cubic Feet

SETTING DIMENSIONS Width - 36 inches

Depth - 36 inches

Height - 36 inches

KILN LINING 9.0" of 3300F bubble alumina refractory

4.5" of 2600F insulating firebrick

1.5" of 1900F block insulation

15.0" Total Wall Thickness

TYPE BURNERS High velocity, high turn-down, nozzle mix

NUMBER OF BURNERS Two (2)

OPERATING TEMPERATURE 1650C

FIRING CYCLE Various

FUEL Natural gas

KILN RATING 3,000,000 Btu/Hr.

TEMPERATURE CONTROL ZONES One (1)

ELECTRICAL SERVICE 480V, 3ph, 60Hz

GAS SUPPLY 3 psi

DRAWING NUMBER KI0575

SECTION 3

Kiln Description - Mechanical

Steel Structure

The outer shell will consist of structural steel members

combined with heavy gauge 3/16" plate, welded together

to form a strong, stiff integral unit. Structural tubing is

utilized in the base design to provide combustion air for the

burners. Combustion airflow helps keep the base cool at

high kiln temperatures, contributing to long life. The entire

kiln is mounted on heavy-duty structural support legs. All

exposed metal surfaces will be painted with high

temperature paint.

A COOL SKINTM coated steel sheet will be attached to the

Kiln door and side walls. This combination radiation and

convective shielding provides a cooler work environment in

front of the kiln by reducing the outer skin temperature.

Refractory Lining

The kiln walls are lined with a total of fifteen inches (15") of high quality refractories. The composite

wall design is as follows:

Nine inches (9") of 3300F bubble alumina refractory brick

Four and one- half inches (4.5") of 2600F insulating firebrick

One and one-half inches (1.5") of 1900F calcium silicate insulating block

Anchoring bricks secure the lining to the steel shell by means of specially designed AFloating@ alloy

anchors. Generously sized expansion joints help to compensate for the tendency of the hot face

refractories to grow over time. The kiln hearth brickwork is composed of high quality refractories,

properly anchored, to minimize maintenance.

The kiln roof is a turned arch design with a nine inch (9") hot face of wedge shaped 3300F bubble

alumina refractory bricks, covered with layers of 2600F fiber blanket.

Door Arrangement

The door of the "USA" kiln is a refractory lined, full opening double hinged, non-sag door fabricated

of structure steel with heavy duty, positive action door clamps. The full opening door allows the

operator to stand directly adjacent to the setting deck when loading and unloading product. A port is

located in the center of the door to observe the product setting area or to sight with an optical

pyrometer.

Exhaust Outlet

The "USA" Front Loaded Chamber Kiln is an updraft design, where exhaust gases are discharged

through an opening in the Kiln roof. Refractory slabs are positioned above the roof slot to minimize

heat radiation out of this exhaust slot, thereby conserving fuel and improving temperature uniformity.

SECTION 4

Combustion System

NFPA Standards

The combustion system will be built to meet NFPA standards in effect at the time this proposal is

submitted. The complete combustion system has consciously been designed to meet all significant

and well-defined standards that are recognized in the United States.

Combustion Components

This kiln is heated with two (2) specially modified high turndown burners. Burners are positioned to

fire horizontally in the space provided beneath the product setting deck. The high velocity burners

entrain and circulate kiln gases as they pass around and through the product setting, creating

excellent circulation and temperature uniformity.

Both burners are grouped into a single temperature control zone. The control thermocouple is

carefully positioned within the kiln chamber to assure reliable repeatability. This system

automatically compensates for variations in product settings from cycle to cycle thereby providing

the best possible temperature control.

Each burner is spark ignited and equipped with a shutoff valve, solenoid valve, and fuel and air

balancing valves. In addition, each burner has an independent fuel metering orifice to insure simple

and accurate setup of the fuel/air ratio. For the ultimate control, each burner has its own control

regulator. An automatically controlled impulse line manages the fuel flow to the burners to maintain

accurate temperature control in the kiln throughout the heating portion of the cycle.

The air supply blower, which is floor mounted behind the kiln has sufficient capacity to provide the

appropriate combustion air supply as well as additional air for cooling. A butterfly valve in the main

combustion air supply line is automatically regulated to control the cooling portion of the firing cycle.

SECTION 5

Controls

Fuel Supervision

Pressure switches will be applied to the combustion air source and fuel train to insure that the

appropriate values are maintained. A Modular Gas Train which includes the main pressure

regulator plus required pressure switches is attached to the back of the kiln structure. All of these

devices work in concert to shut down the fuel delivery in the event of a problem.

Each burner is equipped with UV flame sensors that detect the presence of flame. This device acts

to shut down the fuel to an individual burner in the case of flame failure.

Temperature Control

Control functions are through a Honeywell Model DCP-100 Programmer and a Honeywell Model

UDC-3300 Controller. These instruments provide the following control functions:

Time/Temperature set point programming of the kiln temperature with fuel only control.

Programmed conversion to controlled cooling followed by regulation of the combustion

air input to control the cooling curve.

All controls are mounted in a free standing control console, ergonomically arranged for simple and

logical operations. Appropriate alarms will be supplied for flame failure at any burner, loss of air,

fuel, and/or over temperature.

A dual element type-B thermocouple is supplied. One element is used for monitoring and control of

the process temperature and the second is independently wired to the over temperature controller

for automatic Kiln shutdown in the event of over temperature.

Automatic Fuel Shutoff

This system includes an adjustable timer in the microprocessor programmer to be set for the time

the fuel is to be shut off. After the fuel is shut off, the combustion air blower remains in operation to

provide cooling. A second adjustable timer in the programmer is set for the total length of the cycle

time, and shuts down the entire kiln at the end of the program.

Over-Temperature Control

This system senses the temperature in the kiln with a dedicated thermocouple mounted just below

the roof of the kiln. The thermocouple is connected to a separate on-off over temperature controller

mounted in the control console.

The kiln over temperature set-point is programmed into the controller at approximately 15 C above

the maximum soak temperature. If, at any time, the temperature reaches this preset temperature,

an alarm is energized notifying personnel of the over-temperature condition. If the situation is not

corrected within a preset period of time, then the kiln is shut down.

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