The kiln is either horizontal, vertical, or oblique. It mainly depends on the temperature and space that can be reached in the kiln.

I have used two methods to burn pottery before, one is to dig a pit in the ground and bury it, and the other is to burn it in an open-air urn, but these two methods are not very good, the temperature is not high, and the texture of the fired pottery is not good. Of course, he demanded it according to the standards of later generations.

In addition, there is also a method of urn firing, in which a circle of stones is placed on the ground as a stove hole, and a wooden stick is placed around the circle of stones, just like a roof, and a small hole is made in the top as a vent. The outside of the wooden stick should also be coated with thick soil, and of course, the inside is a clay pot, which can maintain a temperature of about 800.

There are people in foreign countries who use a similar method to burn charcoal, but foreigners do not have the habit of using "stove holes", but use fireplaces, so foreigners do not leave the stove hole underneath, but fence the whole wooden stick and poke small holes in the side to start the fire. It's okay to burn charcoal, but it's a bit lacking in clay pots.

In addition to these three methods, there are two simpler horizontal and vertical methods, the horizontal firing of pottery is like a pipe, the clay pot is placed in the middle of the pipe, while igniting the fire, while emitting smoke, this method can increase the temperature some; The pottery is fired vertically, similar to the honeycomb coal stove of later generations, and the clay pots are stacked into it, and the fire is lit below, and smoke is emitted above.

However, although the above five methods can be burned out of pottery, either the temperature is not enough, or a few pottery can not be burned at one time, and it can no longer keep up with the development of the tribe, so he wants to make a larger one, and also lay the foundation for burning lime and smelting metal in the future.

The horizontal kiln was directly abandoned, this one will be eliminated, and the remaining vertical kiln can be made into a circular kiln, and the oblique one can be made into a centipede, which should be called a dragon-shaped kiln. The circular project is smaller, and the dragon-shaped project is large, so it can be abandoned for the time being.

In the end, it was settled so happily, and if you get a round kiln in the shape of a bunker, there will definitely be a harvest of bunkers.

This kind of bunker kiln has a very high technical content, even if he makes it now, others can't copy it, and even he can pat his chest and say, find a modern person who doesn't know how to fire a kiln to learn it, and he still can't get it.

First of all, he made a pit diagonally on the ground, which could be used for four people to walk side by side, and the height of this pit was about one and a half meters, which was equivalent to a stove hole, a place to burn a fire.

When it was done, a grate was built about seventy or eighty centimeters above the ground, and this thing was similar to a protective fence, horizontal with a gap in the middle. The main purpose is to ventilate, when there is a lack of oxygen the fire will be extinguished, of course this is not absolute, but the stove has to follow this principle.

This grate, at the beginning, can stump him, because it is direct contact with the flame, so you have to use iron, now there is no substitute, and without this thing, it will greatly reduce the temperature of the flame in the furnace, and the wood is not suitable for burning, can not always maintain sufficient firepower.

Since last year's pottery meeting, he has been thinking about how to deal with the problem of the grate, and he has not figured it out until recently, so he has delayed until now.

He replaced it with a uniformly sized hardwood stick, which, according to common sense, must have ignited in an instant, turned to ashes and leaked out, and could not be replaced with stones, it would burn. However, the outside of the sticks could be coated with a thick layer of refractory earth, which could withstand more than fifteen hundred degrees of calcination, and he had already used a small stove of refractory earth before.

The grate is solved, even if the refractory soil wrapped wooden rod has a limited service life, but the one he designed is not troublesome to replace, basically the left and right sides are stuck in the cracks of the stone, and if it is broken, just insert another one.

And the grate is seventy or eighty centimeters high from the ground, which is the hole of the stove, where the wood is placed. The air from under the grate comes up and comes into contact with the flame, which will escape into the bunker kiln to be built above, and the ash from the burning wood can leak through the cracks in the grate and be collected and used as fertilizer.

That's not all, the opening for the timber needs to be reduced to the size of a face plate, or even smaller, because it involves the airflow, and the same is true under the grate. When the time comes, it will be sealed, and the ash mouth and the firewood mouth will be sealed.

Sealed and opened, the firepower is small; When the seal is opened, the fire is larger, and the fire is closed when it is sealed together, and the flame on it will be extinguished because it cannot touch the air.

Therefore, the technical content here is very high, if it weren't for Su Yang's strong memory, and he used to be in and out of the cement factory for a period of time, and he had been preparing for a long time, otherwise he would not dare to start work like this.

After completing this step, it is necessary to build the furnace above, with an estimated volume of about 200 cubic meters, about ten meters in diameter and two meters in height.

Since it is called a bunker furnace, it is natural to use all stones, the walls are round, and the top is also a round lid, and it is also necessary to leave a door from the front near the grate for entering and exiting the clay pot. The two-meter-high wall below is easy to say, but the top is difficult to get, because there is no adhesive, not to mention cement, and lime is not yet available.

This is only a selection of stone, with the principle of stone arch bridge to build, after the capping can remove the support, the top is not left air outlet, because the chimney is located at the back of the kiln, leaving a hole at the bottom, so that when the flame of the grate rises to the top of the furnace, because it can not be discharged, it will fall back into the rear vent, through the chimney out, which forms a thermal cycle.

The outside of the bunker kiln is made of stone, and the inside is also plastered with a layer of inner walls, first clay and then refractory soil, which will be smeared thicker to prevent air leakage and also to maintain the temperature in the furnace.

Probably like this, some people do not leave a chimney, but make some small holes above the stove, so that you can observe the burning in the furnace from the outside, the disadvantage is that you have to keep putting in the firewood to calcine, and you can't stop for a moment.

The specific method is good, he can't judge now, can only be handed over to time to witness, it is simple to say, but every step is very particular, including the flow line of the furnace wall, if the arc is not smeared, it may also cause the chimney air flow can not echo with the furnace grid, commonly known as not being able to pull the fire, then the furnace will be crippled.

Su Yang stared at it for six days in a row, and he carefully determined every step, who knew that there was still a problem when he finally tried to burn, his design was wrong, and there was no problem with the ignition of the grate hole, but as soon as the fire came up, it went straight from the low place to the chimney hole in the back, in short, the thermal cycle he envisioned did not appear at all, and this situation could not be calcined into the pottery in the kiln at all.

"What went wrong?" Su Yang scratched his head, he had to figure this out by himself, and the rest of the people couldn't help. (To be continued.) )