- Clinker Cooler
Drive Project -

The old system's had been designed at the end of 1980's with hard wired controls using
Proportional Valves NG 16 for open loop control, ( see picture )

Main problems on the type of control was:
- the Hydraulic Control via the 4WRZ 16
combined with Inlet Pressure Compensator
was used in a closed loop control circuit,
where this Valves are for open loop;
- with the long hose lines between the
valves and the cylinder the response time
made this system to slow and weak, with
the result that the accuracy was not
very reliable;

- the best Synchronization on the two Axis's was 2 to 3mm and with higher demand / faster stroking speed this Synchronization Error increased, causing often time complete Plant Shut down;
- Set up via the hard wired control cards was difficult and fault finding took long time
- Faults in the control system was often only recognized in the Central Control Room, when the Plant had to be shut down;
- It was not possible to keep Oil Cleanliness of the hydraulic system as required by the Proportional Valves, the System filters had all
By - Pass Valves, causing short life time of the Valves;
- even with the introduction in the years 1991 to 1992 of Systems with PLC Controls, it was only possible to improve the accuracy of this
systems to 1,5mm to 2,0mm, where this error increased at higher speed;
- The system Pressure was not stable at stroking speed from 16spm up to 25spm, causing more miss Alignment.

With this Problems in mind German Hydraulic & Plant Service Inc. worked on the engineering to Modernization the CLINKER COOLER DRIVES with the
following objectives:

Factory Automation
Accuracy
Reliability, Safety of operation based on 24Hours 360 days

The requirements for the new engineering:

Control of Stroking Speed from 4 up to 25 double strokes per minute;
Control the Alignment of the Cross Head Shaft 6 to 8m lengths with accuracy from 1mm or less over the whole range of speed, under changing load condition;
under changing temperature conditions
Control of Position
Reliability based on 24hours operation, 360 days a year
Full communication with other PLC's with in the Factory
Signal exchange through BUS System

Longer Life time of all used hydraulic components under the most difficult condition in the Cement Industry;

The Pictures here showing the new installation, where now is used a smaller
Valve NG 10 for CLOSED LOOP control
Type: 4 WRE 10 E1-75-2X/G24K4
Where the Control Block is mounted directly
on the Cylinder, to be able to eliminate the
Flexible Hose Lines, which increases the
accuracy of the control.

In the foreground can be seen the Stroke Transducer in a protective Cylinder,
the Cylinder is Oil filled to lubricate the Seals.

System for 4.000T/day Kiln Max Flow : 560L/min Pressure : 120bar / 210bar Force on Cross Head Shaft : 50T Speed : 4 to 25spm ( double Stroke ) Operation : 24hours Accuracy : 0,5mm ( Synchronization )

With the Proportional Valves with Electrical Feedback directly mounted on the Cylinders, this Part of the Control is now very stiff, the accuracy and response time increased.

The Filtration of the System was improved, the Filters now have no By Pass Valve, the Filtration
Area was increased, to be able to have the Required Cleanliness of the Hydraulic Fluid and at the same time to extend the service interval!

To reach a stable Pressure Supply at 130bar respective 210bar, even on Higher stroking speeds above 17spm, we installed one additional Bladder Accumulator ( 35L ) and changed the pre Charge pressure on them to accommodate the required Flow of maximum 560L/min, but still having one Pump as a stand by Pump.

The Hard of the control is for each Grate independent PLC's with
Allen Bradley Logix 5500 Controller and
Modern VT - VRPA 2-1X/ for Valves with
Electrical Feedback used for closed
Loop controls.

he PLC has a very short scan time, the Transducer
signals can be used over
the whole range.

With the PLC we are able to spread the Signals used so that the setting for INPUT and OUTPUT are in same value levels.

With this PLC the DIAGNOSTIC of Faults and the OBSERVATION of the System Is made very easy, this makes it possible to establish a trend, helping
The maintenance of the Grate Clinker Cooler;

For the communication with the Plant Main Controller / Central Control Room we installed PROFI BUS System's on each of the Grate Clinker Coolers, with this all Indications at the CCR are given in real time / real data.

The Pressure Sensors on each of the Cylinder will Sense the Load Pressure to the PLC, which in turn will adopted the System Pressure according to the mechanical Load in the Clinker Cooler via the Dual Pressure Compensator mounted on the each of
the Hydraulic Pumps, this allows the Pumps to work with two fully Independent Pressure settings.

When the mechanical Load at the Grate Controls is Low, the Pumps will work on 130bar, in case the Load is increased, because of Kiln Coating Brake out or other reasons, the Pumps will work with 210bar.

The system as shown here, was commissioned and tested, the accuracy of Synchronization is between 0,28mm to max 0,41mm, independent from Load or Stroking Speed.

The System is in full operation under maximum Kiln Production, which was at the time of this installation increased by the Customer.

      to top page