Pot furnaces
Pot furnaces with regenerative air preheating
Fossil fuel heating principle:
The top fired melting pot furnaces are usually designed for 6 – 8 pots located in one common combustion space with elliptic plan.The pots are placed on the bottom of the combustion space. The furnace is always heated by means of one of two burner ports located one against another on both sides of the furnace. Each burner port is equipped with 4 – 6 burners
Flame from the burner passes through the combustion space, combustion gases leave the furnace through the other opposite burner port, and enter the regeneration chamber through vertical exhaust channels. The chamber (located in furnace substructure) is packed with refractory packing. Both sides of the substructure are equipped with one regeneration chamber.
Refractories of regenerator packing, and regenerator walls are heated up by the passing through combustion gases. Then, in predetermined time, this cycle is reversed, and combustion air then flows through the regenerator packing of the hot chamber. Heat from the refractories is transferred to combustion air that is heated up to 1,200 0, and in the mouth of the burner port, the preheated air is then mixed with fossil fuel in controlled mixing ratio.
High temperature combustion process with the optimum parameters of flame, and a relatively long residence time of combustion gases in the furnace, result in a very good heat transfer to the pots.
Therefore these types of furnaces reach one of the lowest specific energy consumption among all the fossil fuel fired pot furnaces.
The furnace operates in work - melting- refining and step down –work mode. Furnace control is usually semi-automatic, and fully automatic control system can be provided when required. All important data are monitored and filed.
Waste molten glass from the furnace bottom is gathered in a glass pit located in the substructure between regeneration chambers, and emptied as necessary.
The furnace is charged manually or by means of special mechanized batch charger.
Brief technical parameters:
Typical applications: Table ware glass, lightening ware glass
Glass type: Soda-lime glass, lead crystal (waste gases cleaning is necessary)
Number of open pots: 6 –8, (max..10)
Diameter of pots: 600-1200 mm
Fuel: Natural gas, fuel oil
Operating mode: Work 8 h
Melting 12-13 h
Refining and Step down 3-4 h
Specific energy consumption: 7200kcal/kg of glass and more, which depends on the type and colour of molten glass,total melting capacity of the furnace, kind of manufacture, cullet ratio, etc.
Pot furnaces with recuperative air preheating in steel recuperators
Fossil fuel heating principle:
The pot furnace is usually designed for 1 or 2 pots. Each pot is located in a separate combustion space-zone, and specific (relatively different) thermal conditions can be created in each zone, even in a two-zone type pot furnace..
Each zone is heated by means of two hot air-fuel burner situated one above another in the sidewall of the furnace, near the front wall.
Both burners burn all the time. In the mouth of burners, preheated air (coming from the recuperator by insulated steel piping) is mixed with fossil fuel in controlled mixing ratio. Flames that leave the burners then pass through the combustion space, by-pass the pot, and combustion gases leave the furnace through exhaust outlet in furnace bottom. The combustion gases then flow under the bottom, which is heated by them, and they are then led by exhaust channel into metal recuperator. Downstream the recuperator they are directed to steel stack or to equipment for heat recovery (decreases specific energy consumption – see hereinafter)) and flue gas cleaning. The double shell steel recuperators are usually used for combustion air preheating to approx. 450 0C.
The furnace operates in work-melting- refining and step down -work mode. Furnace control is usually semi-automatic, but fully automatic control system can be provided when required. All important data are monitored and filed.
Brief technical parameters:
Typical applications: Table ware glass, art glass
Glass type: All types of glass (excl. opal glass) - for lead crystal glass, it is necessary to install waste gas cleaning equipment
Number of pots: 1-2
Diameter of pots 500-1000 mm
Fuel: Natural gas, LPG, light fuel oil
Operating mode of the furnace: Work approx. 8 h
Melting approx. 11-13 h
Refining and Step down approx. 2- 4 h
Specific energy consumption: 12 000kcal/kg of glass and higher, which depends on combustion air (gas) preheating, melting temperature, type and colour of molten glass,total furnace melting capacity, kind of manufacture, cullet ratio, etc.
