I refer to Mr. Wee‘s excellent Case Study Paper on Steam & Power Balance.

After downloaded the paper and studying in detail for 1 weeks, I found the paper so intriguing that it compels me to ask questions and want to understand this subject thoroughly.

First of all, as a Mill Engineer for a while, I have heard of Steam & Power Balance of a Palm oil mill now and then but I could not really comprehend it more so, how is it represented in the mill. None of my Sifu Engineers has ever explained and guided me about it.

So, my question is:

1. how do I know if the Steam & Power is

balanced in my mill?

2. How do I go about correcting it?

Thank you in advance. Hope other members would join in and take keen interest in this important and pertinent subject in all Palm oil mill Engineer’s career.

How to counter check that our Steam & Power is balanced? My simple definition of Steam and Power Balance is the amount of steam that passes through the turbine to generate the required power, KW to run all machinery of the mill is equal to the required amount of process steam. After much been said and discussed by Mr. Wee and Mr. Lee on this subject, I would like to complete the subject with how to check that your Steam and Power is balanced? On Power side, the Turbine must be delivering ALL the power, KW for the whole mill operation without any supplemental power. On steam side, we will know our steam required is fulfilled or balanced if we can achieve the throughput with no complaints on not enough steam to allow smooth and continued process. And to know if there is over production of steam, we can check this scenario if we see extra steam always blowing off from the back pressure receiver. In this situation we can know that our steam and power is balanced

Much has been discussed on this topic, here is how you could put what you have learned into your work in your mill.

Read on:

Wesley asked:

1. How do I know if the Steam & Power is balanced in my mill?

2. How do I go about correcting it?

Refer to Archie's posting in 'Help Us Improve ...' under 'Proposal for next Case Study Topic'.

Comments posted by CS Tan is a good example of understanding the concept of Fuel/Steam/Power balance in any palm oil mill. He has explained how the capacity of the mill had to take into consideration of the steaming capacity of the boiler and the power required to run the mill.

Some rule of thumb ratios to consider include:

1. Process steam required (from BPR at 45 psig) for Sterilization and other heating processes in the mill varies between 0.35 tons and 0.5 tons steam per ton FFB. With better steam management, the figure will be on the lower end.

2. Steam to power the Turbines. This will depend on the efficiency of the Turbines. For single stage turbines normally 20-23 kg/kW of power. For high efficiency or multi-stage Turbines, the steam requirement will be lower maybe around 14-17 kg/kW. You have to check with the Turbine supplier. So for a given load, if you have a high efficiency or multi-stage Turbine, you will have lower quantity of process steam and hence lower FFB per hour capacity. Say if your mill required 1000 kW to run, a single stage Turbine will require 23,000 kG/hr steam and you will have 23 tons of process steam and this is good for 46 tons FFB per hour milling capacity. However, if you have a high efficiency or multi-stage Turbine, you will have only 17,000 kG/hr of steam which will limit your milling capacity to 34 tons FFB per hour. Some mills with this problems resorted to using the Make-Up line into the BPR to increase the quantity of process steam. This is not recommended.

3. Having established your milling capacity and the power requirement, and the Turbine steam requirement at that required load and the specific steam consumption of the Turbine, you can then check the capacity and operating pressure of your Boiler. Once you have determined the capacity of your boiler, you have to check if there will be enough fuel (mesocarp fiber, shell and EFB fiber) to fire up the boiler at the steam flow rate required by your Turbine. According to boiler supplier, the rule of thumb is, you will need about 320 kG per hour of biomass (80% mesocarp fiber and 20% palm shell) to generate 1 ton of steam per hour. Base on the mass balance by MPOB, you will have about 19% mesocarp fiber and 8% palm shell as fuel for your boiler, and another 22% unprocessed Empty Bunch as potential fuel for the boiler.

I hope you can use this template as a guide to understanding and troubleshoot problems with Fuel/Steam/Power balance in your mills.

Going back to Wesley's first question - How do I know if the Power and Steam is balance in my mill?

The following are signs that you are having problems with the Fuel/Steam/Power balance:

1. Your boiler is always short of fuel due to low throughput. Your milling capacity not providing sufficient biomass to support the requirements of the boiler.

2. Boiler cannot maintain the normal working pressure and black smoke from the chimney. This could be due to steam demand from turbine exceeding the capacity of the boiler. This is a common problem. Additional plant and equipment or power for downstream activities will increase total kW and hence steam demand from the boiler. Parallel operation with diesel generating sets will meet the power demand, but the milling capacity is limited to the steam drawn from the boiler by the turbine. Please note operating the boiler above 80% rated capacity usually will also cause black smoke.

3. Turbine capacity lower the total kW required to run the mill. The turbine will lose speed when the steam pressure in BPR increases. Or load on turbine too low to provide sufficient steam required for milling at the desired capacity. This is common when turbine and diesel generating sets are in parallel operation and the load on the turbine is low.