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Day tank melting furnace

Day Tank up to 4 ton/day

  • The Day-Tank is a gas fired glass melting furnace used to produce soda- Lime transparent and colored glass.
  • The range dimension is from 500 to 4000 kg.
  • Its main characteristic is a great flexibility in the usage: in fact, it is a furnace in which we introduce raw materials subsequently melted and finally gathered.
  • The working complete cycle is 24 hours, divided as follows: 12 hours of filling and melting, 3 hours of rest (the glass cooling down), and about 8-9 hours of gathering and preparing of the glass items.
  • The tank is circular shaped in order to help the homogeneity of the glass mass temperature. The heating system has only one gas burner which works on the surface of the glass bath.
  • The working temperatures of this type of plant, go from 1450°C (to melt soda-lime transparent glass), up to 1490°C (to melt dark colour like blue or green).

Day Tank Working Cycle Description

The Glass melting furnace Day Tank type has a circular shape and is heated with methane gas through a hot air burner, coming from a steel heating recuperator. The furnace is provided with an automatic combustion system. The flame of the burners works tangent to the circular wall of the furnace, and it runs on the glass surface, following a U trajectory. The draught chimney is placed on a lateral position as regards the working mouth. The working cycle is daily, 24 hours on 24, and it is divided in four different phases

Day Tank working Cycle

Glass Working:

The furnace has a temperature between 1100°C and 1180°C, in order to keep the glass at the suitable viscosity to be worked. During this phase the glass is gathered and worked by the glass-makers.

Heating and Charging of the raw materials

At the end of the working shift, the tank has been emptied from the glass and the heating and charging phase begins: the furnace is taken to the suitable temperature to melt the glass (between 1280 to 1320°C), and we charge the raw materials through the charging machine. The complete charging of the raw material is made in two or three times depending from the dimension of the furnace.

Glass Melting and Refining

After the last charging of raw material, the furnace is brought to the maximum temperature, 1450/1490°C, in order to get a very liquid glass, allowing the elimination of all the gas that have been produced during the melting.

Cooling down to the working temperature

When the glass is well refined (free of gas bubbles), the furnace temperature is brought to the working temperature (according with the production schedule) between 1100 and 1180°C. It takes about two hours


Day tank Refractory Structure

Bottom pavement
Two layers of insulating bricks (130 mm) and two layers of silica-alumina 42% bricks (130 mm).
Safety layer
Made in ERSOL 50 – manufactured by SEPR – 30 mm. thickness. This layer is also to support in the best way the tank electro-fuse blocks.
Round shape melting tan K
Made with Electro-fused blocks, 200 mm sidewall and 100 mm bottom thickness.
Insualtion
Melting tank walls will be insulated with 180 mm of refractory bricks, 65 mm of silicaalumina bricks plus 115 mm of insulating bricks. An Ersol 50 safety layer will cover every joint of the melting tank blocks to prevent leakage of glass outside the tank.
Layer at glass level
Made with Zircon PROMOLD bricks, 65 mm thickness.
Superstructure
Having a total thickness of 415 mm, 300 mm. of Silica (PID Group) plus 115 mm of Calor A insulating bricks.
Crown standard and round shape
250 mm tickness, made with SILICA wedge bricks (PID Group). The crown will be sealed with special cement and insulated with a 75 mm ceramic fiber blanket and covered with aluminium sheet.
Chimney
It will be built with mullite bricks and 115 mm of insulating bricks.
Pre-assembled electrofused cast tank
Pre-assembled round shape silica crown

Day Tank Technical Features

DTR 500 GAS FIRED

  • Max melting temperature: 1490°C
  • Electrical power installed: 5 kW
  • Workable glass: 500 kg
  • Furnace weight: 4000 kg
  • Glass Capacity: 700 kg
  • Tank Inner Size: Ø 1100 mm
  • Energy to mantain 1000°C: 8 Nm³/h
  • Tank Glass Deep: 330 mm
  • Total Gas consumption 24 h: 380 Nm³
  • External dimensions: 1960x2600x1700H mm
  • DTR 1000 GAS FIRED

    • Max melting temperature: 1490°C
    • Electrical power installed: 8 kW
    • Workable glass: 1000 kg
    • Furnace weight: 9000 kg
    • Glass Capacity: 1400 kg
    • Tank Inner Size: Ø 1500 mm
    • Energy to mantain 1000°C: 12 Nm³/h
    • Tank Glass Deep: 350 mm
    • Total Gas consumption 24 hours: 650 Nm³
    • External dimensions: 2360x3000x1700H mm

    DTR 1500 GAS FIRED

    • Max melting temperature: 1490°C
    • Electrical power installed: 10 kW
    • Workable glass: 1500 kg
    • Furnace weight: 12000 kg
    • Glass Capacity: 2200 kg
    • Tank Inner Size: Ø 1800 mm
    • Energy to mantain 1000°C: 18 Nm³/h
    • Tank Glass Deep: 350 mm
    • Total Gas consumption 24 hours: 840 Nm³
    • External dimensions: 2760x3400x1700H mm

    DTR 2000 GAS FIRED

    • Max melting temperature: 1490°C
    • Electrical power installed: 12 kW
    • Workable glass: 2000 kg
    • Furnace weight: 15000 kg
    • Glass Capacity: 3000 kg
    • Tank Inner Size: Ø 2200 mm
    • Energy to mantain 1000°C: 21 Nm³/h
    • Tank Glass Deep: 350 mm
    • Total Gas consumption 24 h: 930 Nm³
    • External dimensions: 3060x3700x1800H mm

    DTR 2500 GAS FIRED

    • Max melting temperature: 1490°C
    • Electrical power installed: 12 kW
    • Workable glass: 2500 kg
    • Furnace weight: 17000 kg
    • Glass Capacity: 3600 kg
    • Tank Inner Size: Ø 2300mm
    • Energy to mantain 1000°C: 24 Nm³/h
    • Tank Glass Deep: 350 mm
    • Total Gas consumption 24 hours: 1080 Nm³
    • External dimensions: 3160x3800x1800H mm

    DTR 3000 GAS FIRED

    • Max melting temperature: 1490°C
    • Electrical power installed: 12 kW
    • Workable glass: 3000 kg
    • Furnace weight: 19000 kg
    • Glass Capacity: 4200 kg
    • Tank Inner Size: Ø 2500 mm
    • Energy to mantain 1000°C: 28 Nm³/h
    • Tank Glass Deep: 380 mm
    • Total Gas consumption 24 hours: 1200 Nm³
    • External dimensions: 3360x4100x1800H mm

    Day Tank Combustion Systems

    AUTOMATIC COMBUSTION CONTROL

    All the main furnace process variables are automatically controlled by precision closed loop controllers. The signals, derived from a comprehensive set of plant sensors, are taken to a central control and instrumentation panel. Manual by-pass switches are available for all variables for setting up or emergency use. From the central control panel it is possible to start and check all the plant.
    Control and instrumentation panel including:

    • Operation selector and push buttons for the complete furnace.
    • Furnace temperature controllers Eurotherm.
    • Gas flow digital controller.
    • Air Flow digital controller.
    • Hot air digital controller.
    • PLC Signal processors for alarm status acquisition (alarm call – alarm knowledge - alarm restore).
    • Furnace pressure controller.

    TEMPERATURE CONTROL

    The Target Temperature is set on the main controller that controls air and gas controllers. Programs for different thermal cycles can be performed.

    AIR CONTROL

    The air controller controls the electronic Inverter that changes the speed of the fan. Fan motor always runs at minimum speed. Then energy consumption and noise are minimum.

    GAS CONTROL

    The gas flow is controlled through the electric valve operated by the gas controller.

    AIR/GAS RATIO

    The system checks any time the proper quantities of gas and air to the burner.

    • 1. Temperature controller
    • 2. Gas controller
    • 3. Air controller
    • 4. Air flow transmitter
    • 5. Heat recuperator
    • 6. Inverter
    • 7. Air valve
    • 8. Fan
    • 9. Thermocouple
    • 10. Gas valve
    • 11. Main gas valve
    • 12. Flexible joint
    • 13. Filter
    • 14. Gas reducer
    • 15. Shut off valve
    • 16. Gas flow transmitter
    • 17. Gas controller

    Day tank Hot Air Burners

    • The internal part is covered with refractory material. The maximum temperature of the air is 550°C.
    • On each burner, there is a butterfly valve with a pressure manometer for hot air regulation.
    • On each burner, there is a micrometric valve and mechanical gas flow meter for gas quantity measure.
    • The gas mixer of the burners is adjustable in order to control the flame length. The distance between air mixer and gas nozzle inside of the burner is adjustable, in order to control the air gas mixing process.
    • The gas pipe with nozzle and air mixer are easily interchangeable from the back of the burner.
    • The burners can work with big excess of air to create a very oxidant atmosphere in the combustion chamber.
    • Low noise burner. The combustion noise of these burners is very low.
    • The burners are installed on a fully adjustable bracket and connected to the gas supplied through quick-release flexible hoses

    Day Tank Hot Air Steel Recuperator

    • This type of recuperator consists in two cylinders of similar diameter made with heat resistant steel and insulated outside with ceramic fiber and rock-wool. The heat exchanging area is the anular space formed between the two concetric cylinders. In fact, the hot waste gas passes through the inner tube heating the steel till 700°C and the combustion air passes through the anular space cooling the steel and heating up itself till 400°C.
    • The stainless steel inside of the recuperator is avalaiable in two qualities: AISI 310S and 253MA.
    • The double shell recuperator is used in single modules.
    • This kind of recuperator is used for Day Tank furnaces of dimensions up to 4 tons/day.
    • The double shell recuperator has a overheating safety system installed on the refractory material of the chimney. This system consists in a stack base motorized valve, that through a cold air flow, regulates the temperature of the waste gas in the chimney in case of overheating, and cooling the recuperator in case of stop of combustion air flow (due to black out or electroventilator breakage)

    Day Tank Furnace Pressure Control

    Complete furnace pressure metering and control system, including:

    • Furnace pressure probe.
    • Sensor for atmospheric pressure measuring transmitter.
    • Digital controller Instrument.
    • Electronic inverter.
    • Electric fan.
    • Air Jet damper.

    PRESSURE REGULATION SYSTEM

    The control of the pressure is regulated by the inserting of plus or minus forced air in the waste gas exit pipe, after the recuperator. In this way, we can reduce or increase the speed of the waste gas and consequently the pressure inside of the furnace.

    The system is composed as follows:

    The differential pressure value coming from the furnace pressure probe is received by the pressure transmitter that transforms it in electric signal and sends it to the digital controller. The automatic digital controller manages the air quantity (electric fan speed) through an electronic inverter.


    Day Tank Furnace batch charger

    Screw feeder automatic charging machine

    The furnace has to be charged through a charging machine in order to distribute the batch in the furnace in a regular way.
    Falorni batch machines are water or air cooled and have two different systems:

    • Automatic or transportable by fork lift screw.
    • Automatic or transportable by fork lift oscillating tube feeder.

    The screw feeder is the most used, while the oscillating tube is used only for colored glass because the machinery empties completely after charging without any deposit in the tube. By automatic charging system with motorized sliding system, combined with a temperature programmer, the glass charging and melting process can be done in fully automatic way.

    Screw Feeder transportable charging machine
    Vibrating tube charging machine on wheels

    Day Tank Furnace Glass Draining System

    In the center of the glass melting tank, 25 mm lower than the electrofused cast sole, there is a draining hole of about 35 mm diameter. The drilled electrofused cast block is fixed 25 mm lower than the sole of the tank, and its thickness is 150 mm.
    The drain opening is controlled by a steel water cooled plunger, installed with a mechanical system.

    The draining can be used for the complete emptying of the furnace or for taking out a part of the glass.
    During the glass drainage of the furnace, the glass flow from the furnace can be open and close by the water cooled plunger mechanism.


    Day Tank Inclining System

    The day tank furnace has the possibility to be inclined by a hydraulic piston. This option is used for the follows reasons:

    • To keep the glass level constant for taking out glass by gathering robot;
    • To help the glass maker to take out the glass at the same level;
    • To increase the glass pull out (empty completely) of the furnace.

    The inclining system is drived manually, by pushing buttons on the panel control or can be fully automatic by a glass level control system for gathering by robot. The lifting speed is very low.


    Day Tank Air-Gas-Oxygen Combustion System

    For the production of special glass with very high melting temperature, such as dark colors, borosilicate glass or glass ceramic, our company proposes a special automatic combustion mixed system (air-gas-oxygen), which is able to get the furnace up to 1550°C.
    This system is an innovative Oxygen/air/natural gas combustion system conceived to work in two different operating ways:

    • Preheated air / natural gas (traditional way)
    • Oxygen / preheated air / natural gas.

    It has been studied to improve the following points:

    1. Melting temperature over than 1500°C: with Falorni Oxy system it is possible to reach the melting temperature of 1550°C in a few hours, without causing stress to the refractory materials and especially to the crown of the furnace.
    2. Shorter melting time: thanks to the higher temperature of the flame and its brightness, the melting process with the AIR/GAS/OXY combustion system is two hours shorter.
    3. Melting of very dark colour: the brightness of the flame allows to melt very dark colored glass.
    4. Loss of chemical components: the quantity of waste gas is reduced of 55%, and the batch powder carried out is very small.
    5. Atmosphere pollution: the emission in the atmosphere is reduced.
    6. Flexibility in the utilisation: Falorni Oxy system can be used in the traditional way (preheated air/natural gas) and with Oxygen/air/gas. The commutation is directly made from the panel control (turning a key selector), and nothing has to be moved (the burner and the digital controller instruments are both the same). The operator can change type of system every time he wants, and he can use the oxygen only during some special glass meltings (for example for the borosilicate glass and the dark colored glass). With this system it is possible to use the Oxygen only when it is necessary. During the working time, for example, it is not convenient to use Oxy because it is not very efficient.
    7. Easy installation: Falorni Oxy system is very easy to install, in comparison with the standard combustion system.

    It is possible to add the oxygen technology to all the Falorni combustion systems.