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Furnace productivity and its factors affecting productivity

Shenzhen Changlin energy-saving equipment specializing in the production of various aluminum melting furnaces , melting furnaces, melting zinc furnaces, as a manufacturer must be familiar with the various figures and efficiency of the furnace, the following describes the productivity of the furnace and its factors affecting productivity.

one. What is furnace productivity? Calculation formula? What is the strength of the hearth? Calculation formula?

1. Furnace productivity: refers to the output of steel ingots or billets that have been heated to a specified temperature per unit time.

Unit ton / hour

If the heating time is known, the formula is G=N/τ ton/hour.

G-furnace productivity, t/h

N-furnace capacity, the weight of the furnace containing metal, tons

Τ-heating time, hour

2. Bottom strength: refers to the amount of steel per hour per square meter of the floor area of ​​the furnace, also known as unit productivity.

Unit kg / (m 2 * hour)

The formula is P = 1000G/A kg / (m 2 * hour)

P-bottom strength;

G-furnace hourly output, tons / hour

A-bottom floor area, for example for continuous furnaces, has the following relationship:

A=n*l*L m 2

N-the number of rows of billets in the continuous heating furnace;

L-the length of the billet, m

The effective length of the L-furnace, meters.

two. What are the factors that affect the productivity of the furnace?

1. The influence of the furnace structure on the furnace structure has a great impact on productivity. The improvement of productivity can be considered from the following aspects:

(1) Adopting a new furnace type: As the furnace type of the heating furnace is continuously improved, new furnace types are constantly appearing, and the material of the furnace is continuously improved and innovated. The productivity of the furnace has also increased from 300 to 400 kg / (m 2 * hour) to 700 to 800 kg / (Ami 2 * hour). Therefore, the use of a new furnace type with high mechanization and automation will be very High productivity.

(2) Renovation of the old furnace type:

1 Enlarge the furnace and increase the loading. In the case that the furnace base is unchanged, the furnace can be enlarged by the modification of the furnace body to increase the amount of charging.

2 Improve the furnace type and size to make it more reasonable.

3 reduce the heat loss of the furnace.

2. The influence of combustion conditions and heating intensity.

After the heat load is increased, the temperature level of the furnace is increased, the ability to transfer heat to the metal is enhanced, and the output is inevitably increased. The important measures for increasing the heating intensity of the continuous heating furnace are to increase the hot spot, expand the heating section and increase the temperature of the heating section, and shorten the preheating section to increase the temperature of the exhaust gas. An important condition for increasing the heat load is that the complete combustion of the fuel must be ensured. If the fuel is 20% in the furnace, the furnace output will be reduced by 25% to 30%.

3. Influence of steel material into furnace conditions

(1) When the heating conditions are constant, the thicker the slab to be heated, the longer the heating time required, and the lower the unit productivity of the furnace. The thickness of the billet is objectively unchangeable, so in order to increase productivity, it is necessary to increase the heating area of ​​the billet.

(2) The furnace temperature of the steel material has an important influence on the productivity of the furnace. If the temperature is higher, the shorter the heating time required, the higher the productivity of the furnace.

4. Effect of process conditions

The heating process is a factor that affects the productivity of the furnace. The same furnace, the use and heating process are different, and the productivity is often quite different. For example, the productivity of a furnace that is operated periodically is much lower.

three. Please write out the specific content of each calorie income item and expenditure item when preparing the furnace heat balance.

1. Heat income items: (1) chemical heat of fuel combustion (2) physical heat brought by fuel

(3) Physical heat brought in by air (4) Heat released by metal oxidation

2. Heat expenditure items: (1) heat required for metal heating (2) heat taken away from the exhaust gas

(3) Chemical incomplete heat loss of fuel (4) Mechanical incomplete combustion heat loss of fuel

(5) Heat loss through the furnace masonry (6) Radiant heat loss of the furnace door and opening

(7) Heat loss of furnace door and opening gas (8) Heat absorption loss of water-cooling component of furnace

(9) Other heat losses, including loss of heat storage in the furnace and heat loss in the furnace.

four. What is the unit fuel consumption?

Unit fuel consumption: refers to the amount of fuel consumed to heat a unit mass (kg or ton) of steel. The use of solid and liquid fuel is kg/ton steel; when using gaseous fuel, it is 3/ton steel.

Fives. What is the unit heat consumption? Write the calculation formula.

Unit heat consumption: refers to the chemical heat of fuel consumed per unit of quality steel. The unit is kilojoules per hour or kilojoules per kilogram of steel.

Use R to denote R=B*Q low/G kJ/kg steel

B-furnace fuel consumption, kg / hour or standard meter 3 / hour (refers to fuel consumption per unit time)

G-furnace production, kg / hour

six. What is the thermal efficiency of the stove?

Thermal efficiency of the furnace: refers to the percentage of the effective heat of the heated metal to the heat supplied to the furnace (the heat of combustion of the fuel), ie η = (heat Q1 required for metal heating / chemical heat Q1 for fuel combustion) * 100%

η=30~50% of general continuous heating furnace

Seven. What are the ways to improve the thermal efficiency of the furnace and reduce the fuel consumption?

1. Reduce the heat taken away from the furnace by the exhaust gas. Under the premise of ensuring complete combustion of the fuel, the air consumption coefficient should be reduced as much as possible to increase the combustion temperature and reduce the amount of exhaust gas. Pay attention to the sealing problem of the furnace, control the pressure at the bottom of the furnace at a slight positive pressure level, prevent the inhalation of cold air, increase the amount of flue gas in the furnace and lower the combustion temperature. To control a reasonable exhaust gas temperature.

2. The exhaust gas is recovered to preheat the air, gas and steel. The waste heat of the exhaust gas is fully recovered, and preheating the air, gas, etc., is equivalent to bringing the heat back to the furnace, which can directly improve the thermal efficiency of the furnace.

3. Reduce the heat taken away by the furnace cooling water. The following measures can be taken:

(1) reducing the unnecessary water cooling area; (2) performing the thermal insulation of the water-cooled tube;

(3) using vaporization cooling instead of water cooling; (4) using anhydrous cold rails.

4. Reduce the heat dissipation of the furnace masonry. The main measure is to implement insulation. The use of lightweight refractory materials and various insulation materials can effectively reduce the heat loss through the masonry conduction.

5. The furnace is kept in balance operation at rated output and optimal control of various thermal parameters is achieved.