The manufacture of glass & ceramic products is complicated by numerous chemical reactions which occur during the process. The use of a clean fuel like LPG reduces technical problems related to the manufacturing activity and thereby leads to enhanced product quality.
Glass is passed through LPG flames for one or more of the following reasons:
- To round off sharp edges
- To smooth off gob or grinding marks
- Seal cracks
- To Increase surface lustre
- To remove cutting marks via heat.
Glass melting is a large, energy intensive operation that requires precise temperature control and fuel purity. LPG can provide easily controllable small flames for specialist processes such as melting optical glass.
Re-heating of melted glassware is carried out in a special furnace before shaping operations. When making complicated shapes, the glassware may have to be reheated several times to keep it malleable. LPG is generally used because the firing rate is relatively low and the combustion must be carbon-free.
Fire polishing of glass surfaces is done to increase brightness. This is done using high-speed polishing gas burners which can utilise a hydrogen-oxygen flame that is blended with LPG.
Annealing is a process of slowly cooling glass to relieve internal stresses after manufacture. The cooling rate is very important because strains will be set up in the glass if it cools at undesired rate. Annealing is done in normally long ovens (‘tunnel’ ovens called “lehrs”) with the glass traveling through on a steel conveyor belt. LPG is used for direct firing and for finer temperature control.
Air-gas burners are also known to be utilized for the shrink packaging of glass articles.
In the ceramic industry, kilns are primary responsible for fuel consumption. Dryers also benefit from the warm flue gases emitted by the kilns with temperature stabilization being achieved supplemental LPG firing.
LPG is an ideal fuel for use in the biscuit and gloss firing of pottery and ceramics, which can be adversely affected by soot produced by other fuels. It is vital to the production of tableware, decorative earthenware, stoneware, porcelain, sanitary ware, tiles as well as electrical insulators.
LPG has become the fuel of choice for many potteries. The fuel’s clean combustion and accurate temperature control leads to enhanced productivity, reduces costs & pollution. It is as earlier stated, desirable for giving the potter control over the kiln's atmosphere during firing, and the lack of carbon deposits also leads to reductions in downtime and contamination.