Multi burner management.           

Burner management adjusts the number of burners lit in a zone in such a way that the modulated gas-pressure falls in the preferred window. This ensures that the temperature/ pressure control loops have enough range to increase or decrease the heat output, depending on the load. This is how burner management exactly works:

For instance, if there are not enough burners lit, the temperature control loop will increase the gas-pressure in order to get a higher heat output. Since the gas-pressure can not go higher than its maximum, it will be stuck there. Here burner management comes in: it continuously monitors the gas-pressure, and if the gas-pressure is above the burner management high limit for a longer period than the burner management interval time, it will select an additional burner and light it. As long as the gas-pressure stays above the burner management high limit it will select additional burners every burner management interval time.
The reverse situation occurs if there are too much burners lit and the gas-pressure is stuck at its minimum, burner management will extinguish burners to get the pressure back in its preferred window. If burner management has decided to light or extinguish a burner, the next thing it has to do is to decide which burner it has to light/extinguish. This decision is made via an intelligent special algorithm, based on pre-selected "on" burners.
If burner management has to light a burner, it will search for a burner with the highest priority level which is not yet lit. In the case, where burner management has to extinguish a burner, it will search for a burner with the lowest priority which is on.

Gap detection.                               

Since the CCP can track the product as it travels through the oven, and it has two different burner profiles(idle and product) a current burner profile is calculated according to the following rule:

At the location of the product, the product profile is used; and where no product resides (a "gap") the idle burner profile is used. Of course this current burner profile continuously changes as the product travels through the oven.

The basic gap handling as described above can be fine-tuned by introducing product lead and lag distances. This allows the operator to correct the heat output for the first and last rows of the product. The lead distance is the distance in front of the product that should be treated as if there is product. On the other hand the lag distance is the distance after the product that should be treated as if there is product.

Moisture control.                           

The principle, regulation of rest moisture in product, is based on influencing the relative humidity in the baking chamber.

As known, the humidity in a direct gas fired oven is created by two sources:

Through burner management we can influence the relative the relative quantity water vapor as follows (only in a zero pressure system):

By choosing a higher operational pressure window on the energy controller, less burners will create the same quantity of heat as in a lower pressure window with more burners selected on (assumption that in both cases temperature set-point is the same).

This implicates that in case of rising the pressure window a larger quantity dry air is brought into the baking chamber through non - lit burners, this results in a lower relative humidity in the baking chamber.

No need to say that this also implicates a direct relation between temperature regulation and exhaust regulation.

The sensors needed to detect rest moisture are of a infrared or radio-wave type. A withcoming problem is that each type is not able to sense the total product baking ranges and is not able to sense under different circumstances.

In the same way as with color regulation testing of the sensors and translating the signal into controls algorithms takes a reasonable amount of time.

Color control.                              

Used is a color analyzer which splits up the product color in a red, green and blue component and detects the intensity (intensity is heavily affected by distance to the product).

We found that by normalizing green and blue, the red indication is a good indicator for the product color.

We can also use this red component as a correcting factor to re-instruct the zone energy controllers.

Together with the customer the high and low color limits of acceptable product can be determined, which gives an operational window in the red component. The color regulator will send a delta temperature to the zones where coloring takes place as soon as the product color moves away from the middle of this operational window.

It takes considerable time and testing to determine how the percentual influence per zone will be for this delta T and what division has to be made for the top heat and bottom heat and also how aggressive the correction is allowed to be.