Coffee pulping mill construction

Jonathan has been engineering, assembling and plumbing the wet mill so we will be able to pulp our coffee here on the farm right after it is picked.

I spent my winter vacation constructing a coffee cherry processing mill (a "wet mill"). The purpose is to take coffee cherry that has just been picked from the trees, remove the skin and pulp from the beans, remove the slimy mucilage from the beans, rinse the beans, and have them exit the mill ready to be dried.

1) Cherry in 100+ pound burlap bags arrives from the field on the driveway-side of the mill-deck where it is unloaded and weighed.
2) Cherry is dumped from the bags into a floor-level hopper (not yet built) on the drying-deck side of the mill-deck.
3) Cherry is metered out of the hopper into the sump where it mixes with water. Over-ripe cherry floats, ripe cherry sinks, so we can skim out floaters from the sump using a small fishing net.
4) Cherry and water is pumped up to the cherry separator that sits atop the pulpers. It goes into a tank in the back of the separator where it fills up and any rocks or gravel sink to the bottom.
5) Cherry and water overflows from the back tank to the front tank where a screen separates the cherry from the water. The water returns to the sump.
6) The cherry falls into the pulpers where it is pulped.
7) The cherry skin and pulp falls out of the pulpers into the auger where it is exited from the mill to a trailer or truck bed for distribution onto the field.
8) The slimy parchment beans fall out of the pulper into a rain-gutter that has water flowing through it. The rain gutter carries the parchment to a pipe that runs it over to a fermentation tank.
9) The beans and water mixture ferment overnight until the parchment is no longer slimy.
10) The watery slime from the fermentation is drained from the tank (leaving the beans behind) and is pumped to the sedimentation tanks (future) or the drywell (currently).
11) The beans are then rinsed several times until no slime remains.
12) The beans are drained with water into the sump where they are pumped over to the parchment separator that sits on top of the u-shaped tank.
13) The parchment separator removes the water from the beans and collects it in the u-shaped tank - this water can be re-used for rinsing or pulping.
14) The beans then fall out of the parchment separator into a wheelbarrow
15) The wheelbarrow is used to move the parchment out to the drying deck for drying.

Sticks and leaves are picked out of the cherry as it is dumped into the hopper. If they are missed there, they will float in the sump and be scooped out of the sump with a net.

Rocks and stones can be caught in the back tank of the pulper separator. Additionally, the pump line from the sump to the separator expands from a two-inch line to a three-inch line with a resulting reduction in pressure, which causes heavy objects to drop out of the flow and be caught at a low spot in the line. Should a rock make it through all of this, and get to the pulpers, it will either be crushed harmlessly, or it will damage the pulper skin. If that happens, you go down to a single pulper - this is why I wanted two medium sized pulpers instead of one large one.