Taking the Heat

Turck’s RFID system ensures correct positioning of the charging carriage

in the dust-laden heat of a Chinese carbide production plant

The most important materials required for the manu-

facture of calcium carbide are coke and lime. They are

converted in arc furnaces at high temperatures into

carbide and carbon monoxide. Carbide production is

a cyclical process. After the burnt carbide is removed

from the furnace it is reheated and fed with coke and

A Chinese carbide producer urgently had to optimize

its production process. A rail-guided carriage for

feeding the raw material in the carbide furnace has

to be correctly aligned to the charging door. With the

previous solution, the position was measured using an

encoder. However, the frequent acceleration, decelera-

tion and braking of the carriage can cause this to slip

a little. The slippage distance is not measured by the

encoder, so that the encoder’s position data is no

longer correct. This resulted in the carriage no longer

conditions present in this area mean that personnel

have to wear protective equipment and are exposed to

a considerable safety risk. All in all, not an environment

in which a person would wish to work frequently.

The plant owner therefore chose an RFID solution for

positioning the charging carriage. The solution essen-

tially consists of three tags fitted on the charging

carriage: one at the opening of the carriage, and one

each at a specific distance in front of and behind the

opening in order to indicate the position. A read/write

down the charging carriage. If the tag on the carriage

opening is opposite the read/write head at the charg-

ing door, the read head outputs the information from

the tag. After the controller has received the informa-

tion, the charging carriage is stopped and the material

fed in. This is executed in fractions of a second and the

correct position of the carriage is guaranteed by the

Hot location: The correct position

of the charging carriage is reliably

APPLICATIONS RFID

information became increasingly incorrect due to

slippage during acceleration and braking, making

it necessary to carry out manual position correc-

tions. Today, the manufacturer measures the

position using RFID tags on the carriage and a

read/write head on the transport rail. This enables

the carriage to be reliably positioned in front of

the charging door. Neither the IP67 read/write

head nor the robust tags are damaged by the dust

and heat from the production process. Today the

considerably reduced.

Solution concept with BL ident

As the customer uses a Supcon process control system,

an RS485 interface is already provided at the installa-

tion site. Turck therefore supplied a BL20 fieldbus

gateway which supports RS 232/RS485. As the tags are

only used for indicating the position, the data require-

ment is very small. An RFID-S module, which can be

integrated easily, is perfectly sufficient. The customer

requires no programming in the PLC for S-Interface (S

can be fitted directly at the installation site. The tags

are made from epoxy resin and are extremely robust.

Even if the surface is scratched or dirty, its function is

not impaired.

Conclusion

Through the use of Turck’s BL ident RFID system, the

operator could increase the production capacity of the

plant and make considerable improvements in terms

of energy savings, reduced consumption and safety at

the same time. As a result of the even more stringent

The BL20 gateway with an RS485 connection provides communication to the controller,

while the RFID-S slice module enables simple connection without any programming