Nut Polishing Drum Optimization
(NPDO)
%201.jpg)
Palm Kernel Recovery Plant consists of various mechanical equipment in which the Nut Polishing Drum (NPD) is regarded as the most vital equipment among all. Its major role is to separate nut kernels from mesocarp fibre after being pressed for crude palm oil (CPO). Subsequently the nut kernel is carried over to ripple milling machine where shell of the nut kernel is cracked open to obtain the palm kernel.
The NPDO comprised of finer separation screen of broken kernels and nuts kernel. After finer separation of broken kernels, it would be redirected to crack mixture separation system instead of conventionally to ripple milling machine for shell cracking.
The conventional NPD was unable to sort out broken kernel and nut kernel effectively. The mixtures, which were not separated, then flowed into ripple milling machine. Broken kernel that flowed into ripple milling machine will be crushed and turned powdery eventually lost in air separation system on the process ahead. Hence, NPDO separates broken kernel and nut kernel before diverting them to two different processes to minimize the losses.
With vast amount of data collected in regards of the size of nuts, kernel and shells and considering the broken kernel characteristic, we have improved the conventional NPD design. Through various trials and errors, we have produced best design that enables separation of most broken kernel with only minimum retrofitting at existing NPD.
Key Optimization of Nut Polishing Drum
-
Finer screen sieve separation of nut kernel and broken kernel
-
Isolate and prevent broken kernel from flowing into ripple milling machine for crushing to powdery hence lost in kernel extraction
-
Reduce workload of ripple mill due to diversion of broken kernel
Due to finer screening separation and isolation of broken kernel, Fresh Stripped Fruit Presses (at upper stream process) could be operated at higher pressure to achieve better oil press which produce better crude palm oil extraction and result in increase of oil extraction rate (OER) of the palm oil mill.
OER versus KER Discussions
During oil extraction process, Fresh Stripped Fruit Presses (FSFPs) were normally set to have sufficient pressure to achieve target OER. Reducing FSFPs pressure would reduce chances of producing broken kernel and indirectly improve Kernel Extraction Rate (KER). However, due to lower pressure of FSFPs, OER would also be reduced due to insufficient pressing force.
On contrary, increasing pressure at FSFPs would increase OER as CPO could be pressed harder from Fresh Stripped Fruit. However, broken kernels would also be increased due to larger press force.
The conventional kernel recovery process would mostly sacrifice this portion of broken kernel as when it passed through ripple milling machine and crushed to powdery form and eventually lost in subsequent downstream process, winnowing separation process.
The argument of salvaging Crude Palm Oil or Palm Kernel seemed to be dilemma among palm oil mill operators. Frequently, operators would arguably of using CPO price and Palm Kernel price as judgment to implement which salvage ability is more profitable. Sometimes, Palm Oil Mill operators would practice balance approach by setting pressure of FSFPs at 4% broken kernel rate. Whilst at this pressure the extraction of CPO from FSFPs would be sufficient and the loss of kernel due to subsequent crushed of broken kernel in ripple milling machine would be at the acceptable rate.
During ripple milling machine crushing process, more than 90% of broken kernel would be crushed to powdery which could not be further recovered.
In order to resolve the above mentioned issue, our Optimized NPD has two separation channels/chutes which could separate broken kernel and nut kernel respectively to eliminate loss of broken kernel being crushed to powdery.
Another key factor of our optimized NPD would be the polishing drum screen sieve size design. Countless efforts has been put in testing and sampling different nuts, broken kernels, kernel shells and full kernel sizes, shapes and density to achieve good screen sieve size design in order to obtain optimum separation and yield highest kernel extraction eventually.
The good news is that these optimization and improvement can be done on existing NPD in your mill with only minimum modification. It is a true worthwhile solution as proven result can be obtained instantly after the upgrading. Result of optimistic Return of Investment (ROI) would be available to prove and concur the viability of the project.
Nut Polishing Drum Optimization Project
NPDO - Simple Schematic Diagram
