At present, kilns that burn purple sand are basically electric kilns and liquefied gas kilns. Coal kilns that mainly burn daily-use pottery and Qianshulong kilns that burn coal and firewood can also burn purple sand pots.
Electric kiln, which is electrified and heated by metal resistance wire in a closed space, is characterized by constant oxygen content (the content of the space in the kiln when charging the furnace), slow heating and cooling, balanced feeding temperature inside and outside the blank (but the position difference may be large, the large electric kiln can reach more than 30 degrees) and accurate temperature control. Because the firing is completed in a closed environment, there is no oxygen supplement during the firing process, and the carbon monoxide released from the green body cannot be discharged, so the firing atmosphere is generally weakly reducing (the fired products are placed in an open position).
Liquefied gas kilns are mainly push-plate kilns, which are shaped like tunnels. It is driven by a hydraulic press, and both ends are always open during the firing process, and the middle section is the combustion zone. The combustion substance of liquefied gas is also carbon, so carbon monoxide will also be produced during the combustion of liquefied gas, which will be mixed with oxygen coming in through two openings to form a combustion atmosphere. Saggers made of refractory materials must be put into the pusher kiln first, and the saggers are placed up and down, so that a stack of saggers can only open the upper layer and the lower part is closed and semi-closed (saggers are slotted). The length of the whole kiln, the length of the combustion zone, the size of the remaining space at the openings at both ends, the purity of liquefied gas, the injection amount of liquefied gas, the placement mode (open or closed) and the placement position (up and down) of the sagger are all variables that affect the firing effect of the pusher kiln. Liquefied gas kilns also have shuttle kilns, which are similar in shape to large electric kilns, but the heating mode is not electrified by resistance wires, which leads to the difference between shuttle kilns and electric kilns mainly in the firing atmosphere and heating (the surface of the fired product ejected by the flame will have a higher temperature).