Discription of lime kiln

A lime kiln is a kiln used to produce quicklime by the calcination of limestone (calcium carbonate). The chemical equation for this reaction is:

CaCO3 + heat → CaO + CO2

This reaction takes place at 900°C (at which temperature the partial pressure of CO2 is 1 atmosphere), but a temperature around 1000°C (at which temperature the partial pressure of CO2 is 3.8 atmospheres) is usually used to make the reaction proceed quickly. Excessive temperature is avoided because it produces unreactive, "dead-burned" lime.

Rotary kilns started to be used for lime manufacture at the start of the 20th century and now account for a large proportion of new installations. The early use of simple rotary kilns had the advantages that a much wider range of limestone size could be used, from fines upwards, and undesirable elements such as sulfur can be removed.

Our Lime Kiln features in,convenient and reliable control of the production process, less wearing parts, high rates of operation, The Lime kiln also has strong structure, stable operation, low energy consumption, high-quality products,large capability from the kiln and so on advantages, we can also offer advanced efficient shaft preheater, five grade cyclone preheater.

Technical features of lime kiln

Take the300t/d kiln as example.It can be regulated within 180t/d-300t/d range without influencing quality and consumption targets.

2.Chalk size:400mm to 80 mm. size range ratio is 1:2

3.Kinds of fuel:natural gas,oil,cola dust,coke oven gas,coal gas of low heat value and mixed fuel of all kinds of fuel(gas and gas,gas and liquid.gas and solid,liquid and solid and so on).

4.Lime products:fine lime and high activity(reaching 360ml,4N HCL Ten minutes). The ratio of lime stone under-firing and over-baking is5-8%.

5.Low heat wastage: they can make full use of heat energy.when primary air passes.fuel gas is preheated.when secondary air passes.cooled lime is preheated. fuel is burned cmpletely adn fuel heat is made full use of .low heat rate is 800-900kal/kg

6.High work ratio: they can operate continuously for 48 to 50 weeks each year.

7.Calcination way: use our new technolohy, three-way pressure system to reduce lime raw burned and burnt rate and raise lime activety.

Structure features and process instruction of lime kiln

1.The kiln body is rectangular or cylindrical.There are double-deck burner girders in the kiln body with periphery burners in the middle kiln body.Waste gas drawing-out girder is set on the kiln top. The kiln is divded into five parts: material storage zone, preheated zone, calcining zone, posterior calcining zone,cooling zone.

the part between the kiln gas drawing-out device and the crown is the storage zone.it is used for storing adequate lime stone in order not to stop producing when the crown feed device needs short-term maintenance

the part between the kiln gas drawing-out device and the upper burner gireder is the peheating zone to preheat lime stone

the part between the upper burner girder and the lower girder the calcining zone where lime stone is calcined  into fine lime .Its height can be regulated according to requirement of quality or lime stone physical property

the part between the lower burner girder and lower gas drawing-out girder is the posterior calcining zone. The lime that was calcined will gain the even and refine quality and raise the activity, when through this zone that has the high temperature and no pressure.

the part between the lower berner and the lime output is cooling zone, cooling air comes into the kiln from the bottom cools lime stone to 75c and comes out of the kiln.Heated secondary air comes into calcining zone to help burn.

2.Tow-girder burning device is central part of the kiln.Some fuel(such as gas .liquid and solid)feed  pipes are placed into the girder the burner mixes fuel with the combustion air even.the quantity and the are of burners on the level are the same.this makes the kiln section temperature distrbuted even to cut doun raw-burner rate and raise lime activety

In order to protect the burner girder working at high temperature in the calcining zone,medium(water or heat oil) enters the burner girder sand-wich and circulates to cool.medium(water or heat oil passes the cooler to cool.reduces temperature and circulates .primary air preheated by waste air ,passes the burner girder and enters the kiln.heat energy is made full use of .safely when medium(water or heat oil)temperature rises above certain temperature.the stand-by pump makes surn mendium(water or heat oil)can keep circulating.

3.Gas extracing girder is on the kiln top. The quantity of pipes is decided by the kiln size.there are many evenly-distributed opens downside of the pipes kiln gas is extracted by the gas extracing girder through the opens to ensure negative pressure of the kiln section is evenly distributed.

4.The kiln has dual-pressure system.The small blower blows secondary air.Secondary air comer into the cooling zone to cool line even. This makes the part under the calcining zone keep positive pressure. Dual-pressure system controls the quantity of primary air and secondary air more precisely than all negative pressure sysrem. Waste air of the kiln top is extracted by the run-off regulator device to keep negative in the zones above the calcining zone and make heat temperature enen on the kiln section. The regulating range of air quantity is 10%~100%. Regulating burning air quantity makes the kiln working under the best operating condition, saves energy and cuts down production cost.