kilnStar System V2 0

©danntech – PROCESS INSTRUMENTATION 2020 1

Filename: kilnStar System V2_0.docx Date: 20 May 2020 Version: 2.0

System The kilnStar System has been developed from our experience on Kiln 3 at Scaw Metals in Johannesburg, South Africa. The system provides a means for transmitting twelve “fixed-point” temperatures and one “roving” temperature measurement off the kiln as well as six shell fan air flowrates. The system consists of the Kiln Data Transceiver (KDT) which is mounted on the kiln inside the Kiln Transceiver Enclosure (KTE). This is then connected to the Kiln Data Receiver (KDR) situated inside the instrument or control room, by means of a pair of slip rings (a radio link can also be used).


Using a striker switch on the kiln, which closes (or opens) once per revolution, the speed and position of the kiln is calculated by the KDT. Using this information, the various bed (zero point or bottom dead centre) temperatures can be obtained from the kiln using the 12 fixed-point thermocouples. A single roving thermocouple can be used to provide a continuous temperature output for the standard kiln temperature profile control used by the operators. Every few seconds the shell fan air flowrate is also transmitted to the control room. The fixed-point thermocouples are located along the length of the kiln with the roving thermocouple positions being opposite the fixed thermocouple locations. Only one roving thermocouple is connected at any time and it can be placed in any position along the kiln. The roving thermocouple has a much faster response and is used at regular intervals to determine the bed and gas temperatures. Due to the construction of the roving thermocouple it has a much shorter life and hence cannot be left installed permanently. The system can be operated in several modes and in the simplest mode the KDT determines when the each thermocouple is at the bottom position (position zero) and transmits that thermocouple temperature to the Kiln Data Receiver (KDR). The KDR then latches that value and produces a 4-20 mA (or 1 to 5 V) output. Each fixed-point temperature is transmitted sequentially as the kiln rotates. In between these fixed-point temperature transmissions, the roving thermocouple temperature is transmitted – typically every 3 to 4 seconds while the kiln reaches the next fixed-point thermocouple transmission.


General System Specifications

End to end accuracy better than ±0.5% (±6ºC).

Output 22 mA when an open

thermocouple is detected and 2 mA when the thermocouple is shorted.

When communications are not available

for more than communications timeout period (set at say 20% more than the time for one kiln revolution) the outputs can be preset to any value.

Up to 13 fixed thermocouple inputs, one

roving thermocouple input (TC#14).

Fixed thermocouple measurement positions to be specified by customer.


All fixed thermocouples will be read and the respective outputs updated when the thermocouple is within a few degrees of the zero point or bottom dead center.

The roving thermocouple

will be read continuously and updated every 3 to 4 seconds or as determined by the data transmission rate.

Only one roving

thermocouple may be connected to any of the roving thermocouple inputs at any time.

Measurement update time

of 1 to 2 seconds for up to 16 thermocouples.

A striker switch for kiln speed sensing.

Kiln rotation speed range 0.1 to 0.7 rpm with nominal speed 0.5 rpm.

The kiln speed (and hence thermocouple locations) are calculated one each revolution.

View of the thermowell after kiln re-lining.

Shell fan inlet inside kiln.


Kiln chemistry. Inside kiln at operating temperature.

kilnStar System Component Connections


Two basic operating conditions - Normal and Continuous: Normal: In the Normal condition the thermocouples are updated every few seconds as determined by the operating mode. Continuous: The Continuous condition occurs when the kiln speed drops below the minimum kiln speed or the striker switch remain closed for longer than the Position Switch State Timeout, all of the thermocouple temperature outputs are updated continuously. System Calibration A PC or the Kiln Data Display can be used to do the calibration. The calibration software switches the KDT into slave mode and then each input can be calibrated. Using a portable calibrator, 0ºC is injected into TC#1 input and when the reading is stable this is latched using the calibrate zero command. 1350ºC is then injected and this value then latched using the calibrate full scale command. This is repeated for each thermocouple input. The Accu-Cal On-Kiln calibration system can also be used. The Accu-Cal On-Kiln Calibration System This is a mV source (could be a Memocal) with short range remote receiver inside a protective enclosure with magnetic clamp. It is temporarily fixed to the kiln at the thermocouple plug-point. The thermocouple plug is removed and the Accu-Cal plugged in. Using the remote control transmitter the mV source will switch from 0 to 1350ºC twice and then go from 0ºC, 250ºC, 500ºC, 750ºC, 1000ºC, 1250ºC and 1350ºC cyclically. Can be controlled from a distance with a simple radio link. Kiln Data Transceiver (KDT)

Fourteen (or more) type K thermocouple inputs, 13 fixed-point and one roving.

Measurement range from 0 to 1350ºC.

Output accuracy better than ±0.5%.

Each input galvanically isolated from the power supply and the communications link.

Accurate calibration and operation - 16 bit

analogue to digital conversion.

Internal temperature sensing and cold junction compensation for each input.

Can be used to interface to other I/O modules on

the kiln for other measurements and controls.

Internal operating temperature 0 to 70ºC.

90 to 260 VAC power supply at 1 A or less. Input surge 10 A.

All internal components DIN rail mounted modules.

Lightening protection on the power input and communications link.


Kiln Transceiver Enclosure (KTE)

Kiln mounting IP66 with double metal enclosure and heatshield.

Approximate size 800 x 1 000 x 500 mm (width

x height x depth). Kiln Data Receiver (KDR)

Sixteen 0 - 20 mA, 4 - 20 mA or 0 – 5 V, 1 – 5 V or 0 – 10 V outputs.

Output scaling from 0 to 1350ºC

(typically 4 mA = 0ºC, 20 mA = 1350ºC).

Output accuracy better than ±0.1% (±1.4ºC).

Each output galvanically isolated from the communications link.

No calibration required - 12 bit digital to

analogue conversion.

Relay outputs for lost communications and other faults from the Kiln Data Transmitter.

Internal operating temperature 0 to 70ºC.

Integral 24 V 1 A internal power supply for

operation from 90 to 260 VAC.

Lightening protection on the power input and communications link.

Internal rail mounted terminals for all

connections suitable for 2.5 mm cross section wire.

Wall mounted IP65 metal enclosure.

Approximate size 600 x 800 x 300 mm (width x height x depth).


Kiln Data Display (KDD) This is software which can provide additional functionality and display options for kilnStar. The software can run on a normal PC or be incorporated into a panel mounted PC in the Kiln Data Receiver. It can be placed in the control room for operator access and can also incorporate a touch screen or suitable keyboard and mouse. Temperature profile alarms and warnings. Trending. Can be used to connect to any number of I/O devices on the kiln for shell fan control and air flow.


Kiln Data Interface (KDI) This module provides an interface to specific communications platforms such as Profibus, Modbus, ethernet or whatever protocol is required. Other options are:

Kiln overview display.

Self documenting Accu-Cal on-kiln temperature calibration.

Data logging.

Remote viewing of any of the displays.

Local and remote alarming on any or all alarm conditions.

SMS messaging to cellphones of alarm conditions.

Automated E-mail reporting.

Remote dial-up with full display access for off-site monitoring.

Other on-kiln measurements and control outputs using the same communications system.

RF data transmission where the slip-rings are not used.

Analogue outputs for kiln position and speed of rotation.

Reg. No. CK86/15338/23 Tel International: 27+11+7921239

Tel National: 011+7921239 Fax International: 27+11+7924687

Fax National: 011+7924687 P O Box 1023, Fontainebleau, 2032

Republic of South Africa www.danntech.com www.kilnstar.com

kilnStar System V2 0

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