OVERVIEW | ||
---|---|---|
As a kiln operator your primary job is to maximize the efficiency of the kilns under your supervision in order to allow your company to provide better drying quality to your customers plus help reduce the drying costs and waste (degrade). -- Remember lumber drying is all about maximizing profit by increasing the value of the lumber together with minimizing the cost of drying. (Cost of drying = Energy cost + Degrade + Depreciation + Maintenance). This procedure for improving a drying schedule has been compiled in a rather simple format and we hope it explains the general approach a kiln operator should take in optimizing the kiln performance. First and foremost it is important to understand that: "Not all kilns are created equal"Most lumber kilns have similar layouts; however, the devil is in the details. You will often find great variation in the venting, heating and fan capacity depending on design, manufacturer, and time of construction. Consequently, you may have to develop variations in certain drying schedules depending on which kiln you intend to dry a certain species and thickness in. This is all part of the job as a kiln operator. We have worked hard to provide the tools needed for making intelligent and educated evaluations for maximizing your kiln operation and we hope you will consider our kiln controllers and components for your next kiln upgrade or new kiln. We hope this information and these guidelines meet with your expectations and approval. We always welcome your opinion and suggestions. You can email, fax, or call us. |
FORMULATE GOAL | ||
---|---|---|
Before you begin experimenting with new and hopefully much better kiln drying schedules and programs, which will offer faster drying times; more energy efficiency; and/or better drying quality, it is important to structure your research. This is best done by setting clear and singular goals. By singular we mean, that we should only set one goal and try to change the drying process to achieve this goal. By setting only one goal we will know the cause and effect of the changes we make, which will provide clear results and help us make better decisions. If we were to try and solve two or more goals at once, we would probably need to change several parameters. With more parameter changes and several goals we will make it difficult to analyze the collected data for exact cause and effect. In addition, by changing one parameter to achieve a modest goal we would not be running as big a risk. Since it is easier to predict the effects of changing one parameter versus changing many parameters.
A few examples of "singular" goals:-- Lower the electrical energy consumption without increasing drying time or degrade. -- Drying a certain species at lower temperatures without increasing the drying time (in order to create a lighter color). -- Reduce the drying time by 5% without increasing degrade. -- Prevent excessive case-hardening (and checking) during the length of the drying process by using the interval fan operation.
A multiple goal could be:-- Reducing drying time and decreasing drying temperatures without increasing the degrade. The last example has conflicting goals, which will be difficult to incorporate into the same test run; however, you may get there by dividing the test into two or three experiments. You would then be able to monitor the effects of your program improvements more exactly and then later combine the two new test schedules into a third (and hopefully final) schedule.
|
DEVELOP ADJUSTMENTS | ||
---|---|---|
When developing improvements to your drying schedules it is best to change as few parameters as possible. This is similar to the idea of setting singular goals. By studying the effect of lowering only the temperature, it is fairly easy to see the exact change. Whereas studying a change in the temperature, relative humidity and air flow will not provide a similarly clear picture, since three factors were changed and it may be unclear which ones helped improve the drying quality and which ones may have hurt the drying quality. Let's imagine an example where we would like to dry a load of maple with a lighter color result than the schedules used in the past. It could be argued that by lowering both the temperature and the relative humidity setting you would get a brighter color. However, the lessons from an experiment where both the temperature and relative humidity is reduced will not be as educational as two test runs (one with lower temperature and one with lower relative humidity). By making two test runs you will learn what each change accomplishes. Remember that you must have an accurate method establishing a benchmark to measure you improvements. Learn about how adjustments in temperature, relative humidity, and air flow changes drying rate of the lumber. |
COLLECT INFORMATION | ||
---|---|---|
Once the new drying schedule has been developed and the actual drying process initiated it is very important to collect information for later study in order to evaluate the result (good or bad). If you do not already have computerized controllers with data collection capability (and preferably networkable to a central computer), your best option is to invest in one. The old style kiln controllers with circular graphs can tell you many things and was very valuable before the recent development in information technology; however, they generally fall short when compared to the information gathering of networked and computerized kiln controllers available from several kiln controller manufacturers. In addition, the kiln control system you invest in (or maybe already have) should make it easy to share the collected information with others. Our software allows you to easily email this information to any person, thereby allowing you maximum access to the kiln drying knowledge. Maximum sharing ability can help you obtain the best possible help and opinions from any person with kiln drying knowledge. This person could be a consultant, a university professor, or a friend, who has experience similar problems or faced similar challenges. |
ARRANGE DATA | |||||
---|---|---|---|---|---|
|
COMPARE RESULTS | |
---|---|
Comparing the results sounds like a simple task after all the hard work is done of:
How can comparing the result be any significant task? Well, in theory it is simple; however, lumber is not a uniform material like steel, plastic, aluminum, etc. Instead we find that the structure and drying characteristic varies greatly within the same specie. The actual value of a specie often depends on its geographical origin. You will even find that the time of year the logs were harvested has a noticeable effect on the drying process. This means that during your testing you have tried to eliminate as much of the variations as possible, but you will never be able to eliminate it completely. Hence the reason that several test charges can help create an average effect, so you do not make permanent changes based on an "abnormal" charge. |
EVALUATE RESULT | ||
---|---|---|
In most cases evaluating the result becomes a judgement between achieving a balance between contradictory goals. The obvious two contradictory goals are:
Now it should be understood that there are two types of evaluation:-- Evaluate the best way to use the existing equipment in the most profitable way. This is very much related to improving drying schedules. -- Evaluate the best way to invest in future upgrades, kilns, predryers, fansheds etc. This is more related to evaluating how capital investment can be put to the best use possible. The first type of evaluation has a short distance from collecting the data to its usage and implementation; in addition, a bad change can easily be undone for the next kiln charge. The second type of evaluation is more the kind where you have collected data and information for some time, which you will look back upon to determine the most efficient use of upgrades and expansion. |
ENACT CHANGE | ||
---|---|---|
Enacting permanent change to your drying schedule is the reward for a long process (if done correctly), where you have decided that the changes will improve your kiln's profitability. In addition, you have gained valuable knowledge for making better and more educated guesses in the future. It is important to keep a very close eye on the next couple of kiln charges to insure that the results are in line with your earlier findings. We hope this information and guidelines meet with your expectation and approval. We always welcome your opinions and suggestions and are more than willing to receive email from you. |