Different forms of lime kilns have different structural forms and calcination forms, and the process flow is basically the same, but the equipment value is very different. Of course, the use effect is definitely different. Calcined quicklime has a long history in China, and the requirements for lime quality are getting higher and higher.
Ordinary vertical kiln production has many shortcomings, such as low utilization coefficient of kiln, less than 50%; High energy consumption, the coal consumption per ton of ash is above 160kg; Because ordinary kilns are mostly open or semi-open, dust removal is difficult and environmental pollution is serious. Feeding and ash discharging are almost directly operated by manual operation, which is labor intensive and seriously damages the health of operators; The quality is unstable, and the raw, burnt and nodulation are generally above 30%, which cannot be controlled in time.
According to China's national conditions, the technology of lime shaft kiln from Japan Hehe Co., Ltd. was introduced, and JHZS type energy-saving and environment-friendly automatic lime shaft kiln was designed in the spirit of introducing digestion, absorption and redevelopment. And formed a number of domestic patented technologies. Widely promoted at home and abroad, nearly 100 buildings have been built.
In recent years, it has been favored by large and medium-sized state-owned enterprises, private individual enterprises and many countries in Southeast Asia because of its remarkable energy saving, high degree of automation, high quality of finished products, low construction cost and short construction period. index
Main technical and economic indexes of lime kiln
1: effective volume of furnace 100-350(m3)
2. The output is 85-300 tons/day
3: the heat consumption is 960× 4.1868 (kj/kg t; Lime) standard coal consumption is 130 (kg/kg/kg lime)
4: Utilization coefficient -0.85 (ton/m3/day)
5: Activity ≥300 (ml)
6: The content of CaO in quicklime is ≥90(%).
7: raw burning rate of quicklime -5-7 (%)
8: limestone consumption 1.8 (ton ash)
9. The concentration of CO2 in flue gas is 42 (%). The 250m3 furnace generates 10(t) CO2 gas per hour.
10: smoke exhaust index -50 (mg/m3)- 1. An energy-saving calcination method is adopted.
(1) Advanced calcining mechanism The design of energy-saving furnace body adopts fully sealed calcining mechanism, and the refractory insulation layer in the kiln adopts high-alumina brick+lightweight insulation brick+insulation fiber+steel furnace shell * * * four-layer thickness1000 mm. The outer furnace shell adopts steel shell structure. Good gentleness, the design life of refractory insulation layer in the furnace is more than 5 years. In order to use energy effectively, the upper and lower parts of the furnace adopt heat exchange, which greatly reduces the heat loss of the upper and lower parts. Combustion-supporting air is blown in from the lower part of the kiln body, and exchanges heat with the finished ash burned in the lower part of the kiln to become hot air, and the finished ash is cooled, so that the temperature of the discharged finished ash is below 40℃. Add the upper raw materials into the kiln and exchange heat with the rising high-temperature flue gas to form a raw material preheating zone, so that the temperature of flue gas discharged from the upper part of the kiln is lower than 140℃. According to the actual measurement, the utilization rate of fuel calorific value is above 80% (generally below 40-60% for kilns).
(2) Through QCX, JCX limestone, coal batching equipment and BLQ distribution equipment, the distribution in the kiln is uniform and energy-saving. Limestone and coal are accurately weighed and evenly mixed by QCX and JCX batching equipment, and limestone and coal are evenly mixed by BLQ 4 distributor and scattered on the material surface. In the calcination area, coal is heated evenly everywhere, which avoids overheating and nodulation in high temperature places and burning in low temperature places due to uneven distribution. It wastes fuel and reduces the quality of finished ash. Many users at home and abroad show that compared with other burden distribution methods, the coal consumption per ton of ash 15Kg is above.
(3) Adopt frequency converter to ensure energy-saving operation of equipment. The power used in kiln production: Roots blower, elevator, disc ash unloader, distributor, mixing belt, etc., is controlled and operated by frequency converter. The phenomenon of big horse-drawn carts and no-load and no-load operation is avoided, and the average energy saving is more than 40%.
(4) Scientific dust removal design ensures dust removal and energy saving. There are six post-dusters, all of which are designed with electric valves controlled by microcomputer. The required air volume for later dust removal is about 50000 m3/h, and the power is 80KW. In the design, the opening and closing of the valve are controlled by program, and the time-sharing control is carried out according to the operation sequence of the equipment, saving 70% of electric energy. This greatly reduces the power of dust removal induced draft fan configuration.
2, dust removal system, flue gas and dust collocation is clever, flue gas emission standards.
Flue gas dust and post dust are mixed and enter the bag dust removal system. It solves the problems that the high dust removal temperature of single flue gas causes damage to the bag, and the flue gas contains a certain amount of tar, which often blocks the pores of the filter bag.
Mixing CaO dust into flue gas before dust removal can turn sticky tar into easy-to-filter granular dust, reduce the temperature of flue gas, and often open the air guide valve to cool down, thus saving the waste of wind power. For the dust with high SO2 content, before dust removal, the flue gas is mixed with the dust, and CaO in the dust is deliquesced when it meets the moisture in the flue gas, and reacts with SO2 to generate fine CaSO4 dust. In the process of kiln production and operation, in the process of raw material hopper-electronic scale weighing-discharging dust removal-finished product warehouse screening-loading, an air hood is designed in every place where dust is generated, and under the action of negative pressure, it enters the dust collector after mixing and is discharged after dust removal. set up
total flow
3. The layout of process flow is compact and reasonable;
The kiln is composed of mixing part, feeding system, distributing part, kiln body part, ore drawing part, finished product bin and dust removal system. The single kiln covers an area of less than 2 mu (30×40m2) and has a compact and reasonable structure.
4. The technological process is scientific, and the waste heat utilization is the most effective.
Qualified raw materials and fuels are accurately weighed in proportion with an electronic scale with an accuracy of 3‰, and then evenly mixed with a hopper and a belt conveyor. The mixture is transported to the top hopper by a single bucket elevator with a height of 1.5m3 along the inclined bridge, and is evenly and quantitatively fed by an electromagnetic vibrating feeder, and the distribution in the furnace is completed by a rotary distributor at the top. The material overcomes the buoyancy of the airflow by its own weight, moves slowly downwards, and passes through the preheating zone, the calcining zone and the cooling zone in turn.
In the process of falling, the burden and hot gas exchange complex heat, accompanied by the decomposition of limestone and the growth and growth of calcium oxide particles. After the whole process is completed, it is also cooled to 40-60℃ with combustion-supporting air. Then the lime is discharged to the belt conveyor outside the furnace by the disc ash unloader and the two-stage sealing valve, and the combustion-supporting air will not be leaked. After hoisting and screening, ≤5mm and >; 5 mm lime is discharged into different silos.
Combustion air is blown into the furnace from the lower part of the furnace body by roots blower, and rises to the top of the furnace from the lower part to overcome particle resistance. Under the attraction of the induced draft fan, the flue gas is transported to the dust collector through the pipeline for dust removal. Due to the induced draft fan, a slight negative pressure area (about-10Pa) is formed above the material level in the kiln. This slight negative pressure ensures the smooth airflow in the furnace, which is very beneficial to the decomposition of limestone in the calcination area. The induced draft fan introduces all flue gas into the dust collector for purification, and then discharges it into the atmosphere from the chimney.
5. Kiln has established a scientific guiding ideology based on raw materials.
The parameters required for raw materials and fuel are as follows
Limestone: chemical composition: CaO content ≥53.5% R2O3≤2%.
Particle size: 40 ~ 80mm
Upper limit ≯90mm, lower limit ≮30mm, and the upper and lower limits shall not exceed 5% respectively.
Coke (anthracite): ash ≤ 14% fixed carbon ≥85%.
Fever value ≥6500×4. 186KJ/Kg.
Particle size: 20 ~ 40mm
Upper limit ≯50mm, lower limit ≮ 15mm, and the upper and lower limits shall not exceed 5% respectively.
Content of
Qualified raw fuel is very important to the quality of quicklime. If the particle size of limestone is uneven, the difference is too large or there are too many impurities, the burden will segregate in the furnace, resulting in disordered airflow, unstable calcination zone and serious overheating, resulting in serious furnace lump.
If the particle size of coal is unqualified, if the particle size is too small, CaCO3 will have insufficient heat when decomposing in the calcination zone, which is easy to cause pinch points. If the particle size is too large, it will still burn when it reaches the cooling zone, which will lead to high ore drawing temperature, waste of fuel and difficulty in ore drawing. Without qualified and stable raw materials and fuels, it is impossible to produce qualified products. Therefore, based on qualified fuel and advanced technology, the high quality of products is guaranteed.
6. The weighing and mixing design of raw materials and fuel is novel and easy to adjust.
The weighing device of the hybrid system adopts an automatic weighing device with full automatic control capability. Accuracy (sex)
7. The distribution equipment has a peculiar structure, and the distribution quantity in the kiln is evenly mixed to the extreme.
The top vibrating feeder evenly conveys the ingredients in the top storage hopper to the rotary distributor, and the rotary distributor rotates while distributing the materials. Every time the cloth is distributed, the position where the rotary chute stops moves forward by 80 degrees compared with the position where it starts to run. This ensures the uniformity of cloth dislocation. The plane or saddle shape of the material surface after cloth distribution is determined by the adjusted cloth plate. It can also be distributed at fixed points in one direction.
8, uniform ash without stopping the wind, keep good furnace condition.
The kiln adopts an ash unloading mechanism consisting of a disc ash unloader and a two-stage sealing valve. The ash discharging function of the disc can ensure that the burnt ash blocks are completely discharged without being crushed and fall into the two-stage sealing valve. The two baffles of the two-stage sealing valve work alternately, which can not only discharge the ash evenly, but also ensure that the combustion-supporting air does not leak and continue to blow. This not only ensures the stable distribution of airflow in the furnace, but also ensures the continuity of calcination zone temperature. So that the quality of the quicklime is high and the yield is high.
9. The furnace condition control method is advanced, and the deviation adjustment only takes 3-4 hours.
The upper part of the kiln body is provided with an exhaust gas circulating device. When there is partial combustion in the upper part of the furnace, the partial combustion in the upper part can be adjusted by operating the opening and closing of eight valves in the upper part to blow out exhaust gas from the chimney without oxygen.
There is a secondary combustion-supporting air device at the lower part of the kiln body. When the furnace condition is off-set, eight valves at the lower part are opened and closed, and the combustion-supporting air sent by Roots blower is blown in, so as to adjust the furnace condition at the lower part. Severe local burns usually take only 3 hours to adjust.
10, high level of automatic production, normal production with single operation.
Automatic feeding, electronic weighing, batching and mixing, feeding, distributing, ash discharging and finished product silo from raw material hopper. When the furnace condition parameters need to be adjusted, they can only be operated on the microcomputer in the industrial control room.