Die hole quantity selection for floating feed

Hello Bashir; During the operation of an expander or extruder there are involved several factors that we keep to maintain under control in order to achieve an excellent finished product quality, most of the people pay too much attention on steam conditioning (quantity and quality of steam); temperature, moisture, retention time, etc; but one of the keys to accomplish a good hydro stability on fish feed are directly related with the die inserts or opening area at the die plate discharge. The configuration of the main worm shaft plays an important role on how to cook the material and also the way to put back pressure at the discharge of the product in order to precipitate more friction inside the expander / extruder which traduces a better cooking degree. The more you restrict the discharge (openings) the more back pressure you produce and subsequently the more cooking of the ingredients in the mash, certainly all of this with the assistance of direct injected steam into the expander / extruder barrel. Additionally people only think that die inserts are used to produce the shape on the collets, however the internal configuration of the die represent a tremendous part in the success to get floating fish feed, diameter and internal land, tapered, etc, are some of the characteristic we have to evaluate in order to get the best results. For example; in our Anderson 8" EEC (Expander-extruder-Cooker) the die plate discharge has 24 perfectly drilled openings to accommodate the die insets. For a normal operation we install die-blank plugs on the die plate and only leave 6-8 openings with the selected die inserts for an specific feed. With this setup we can achieve 4-5 TPH without any problems, the fact that we "block" more than 65% of the openings at the die plate allows us to get the best expansion of the feed at the discharge due to the differential of pressure between the expander / extruder and the ambient. Another factors such as fat content, fiber, particle size, etc has to be also monitored in order to get the desired results. An important subject you brought to the table, quality VS quantity.... in all feed operations sometime the quantity is sacrificed by the quality which at the bottom line is the most important part, so in your case you have to start testing the machine with certain amount of die-blank plugs and then evaluate if more are required to get the proper expansion without facing a drop in capacity more than 15-20%. I hope this helps. ED.

Thanks a Ton Mr. Enrique Diaz. You explained it perfectly. Regards. Bashir