New type of natural gas fired lime

Design Specification for Intelligent Production Line (200 tons/day)(International leading level)

F200 Intelligent Pulverized Coal Spray Lime Kiln

The gas fired vertical lime kiln is arranged from top to bottom as follows: pre heating zone, calcination zone, insulation zone, and cooling zone (an additional insulation zone is added compared to traditional lime kilns).

Pre heating zone: The function of pre heating zone is to use the high-temperature flue gas produced by calcination to preheat the limestone that will enter the calcination zone in advance. This can ① fully utilize the heat energy, reduce production costs, ② accelerate the production efficiency of the kiln, and improve the output (utilization rate) of the kiln.

Calcination zone: The calcination zone is equipped with a three-layer annular furnace and a three-layer peripheral burner (burner). The furnace wall is designed to be wavy, and combined with the fact that the central material in the kiln drops faster than the surrounding material, it causes the materials in the kiln to roll and mix, and also increases the uniformity of lime calcination

When the limestone in the calcination zone absorbs heat above the decomposition temperature, carbon dioxide decomposes from the limestone and the limestone blocks become lime.

Insulation tape: The function of insulation tape is to prevent the high-temperature lime brought out from calcination from rapidly cooling due to the passage of cooling air. ① The high-temperature lime brought out from calcination continues to decompose the partially decomposed calcium carbonate in the insulation tape, making it fully decomposed, and improving the quality of lime (reducing the quickness and overburning of lime, and increasing effective calcium). ② Energy conservation. ③ Stable product quality.

Due to the addition of an insulation belt for lime, this design aims to prevent lime from directly entering the cooling belt after leaving the calcination belt. By utilizing the existing waste heat of the high-temperature lime that has just come out of the calcination belt, the lime can continue to be fully decomposed in the insulation belt for 8.4 hours, thereby reducing the lime's quickness and over burning rate and improving the quality of lime; At the same time, it also fully utilizes waste heat, reducing fuel consumption.

Reduce the diameter of the calcination zone to ensure that the high-temperature flame can penetrate the center of the material in the kiln.

Separate cooling area shall be set to make the lime to be cooled rapidly, so as to improve the activity of lime. Cool as much lime as you need to produce per hour, and the lime that doesn't need to be produced is not in a hurry to cool.

7. Adopting a long flame injection type PWM control burner, while achieving accurate temperature control, it can also ensure flame penetration and improve furnace temperature uniformity.

8. The lime kiln adopts a disc ash extractor with four uninterrupted ash discharge points, which reduces the balance of materials in the kiln during ash discharge, eliminates the problem of ash deviation from the kiln, and improves the stability of kiln operation.

9. The high-temperature kiln gas enters the water bath dust collector for dust removal after passing through the cyclone dust collector, and meets the discharge standards.

10. Adopting inverted cone fabric; After the ignition and debugging of the kiln are normal, it can maintain the kiln without deviation for a long time, thus enabling the operation of the kiln to be automated.

2、 Main technical parameters

1. Single lime kiln volume: 200m3

2. Daily single kiln output: 200-250T

3. Heat consumption: 110-115 kilograms of standard coal/ton of lime

4. Utilization coefficient: 1-1.5

5. Lime activity: (ml): 360 ～ 440

6. Lime CaO (%): 85-92 (depending on the calcium content of Party A's limestone)

7. Lime calcination rate (%): calcination rate less than 5%, over calcination rate less than 2%

8. Limestone consumption (t/t · ash): 1.7

9. Electricity consumption: 20 kWh/ton of ash

3、 Main parameters of kiln

1. Total height of kiln: 34.2 meters

2. Kiln shell outer diameter: 4.94 meters

3. Kiln preheating zone inner diameter: 3.63 meters, volume 57 cubic meters

4. Kiln calcination belt inner diameter: 3.1 meters, volume: 54 cubic meters (4 cycles per day)

5. Kiln insulation belt inner diameter: 3.45 meters, volume: 70 cubic meters

6. Kiln cooling belt volume: 14 cubic meters

7. Volume of intermediate silo in kiln: 9 cubic meters

8. Total volume of kiln: 204 cubic meters

9. Kiln shell steel plate thickness: 10mm

10. Batching measurement method: measuring with a measuring hopper

11. Loading method: inclined frame trolley

12. Ash discharge: The disc ash discharge machine continuously discharges ash at four points

13. Kiln gas dust removal: The coarse dust particles are removed by entering the cyclone dust collector through a stainless steel pipeline with a diameter of 770, and then sent to the water film dust collector for dust removal through the kiln gas induced fan before being qualified for external discharge.

4、 Raw material conditions

(1) High quality limestone: 40-70 mm or 50-80 mm, with a CaO content of ≥ 53%, clean and free of soil, uniform particle size, consistent stone quality, and no impurities.

⑵ Natural gas: Natural gas has a calorific value of 8500-9200 kcal/standard meter ³； The fluctuation range of low calorific value is less than 2%; The impurity content meets national standards.

5、 Process Characteristics and Energy Saving Measures of F200 Intelligent Natural Gas Burning Vertical Kiln

1. This lime production line adopts a fully automatic control system for operation. All ventilation fans of the lime kiln adopt variable frequency speed control, and the kiln gas is monitored by thermocouples. In order to reduce fuel consumption and fully utilize exhaust heat, the pre heating capacity is appropriately increased to use exhaust heat to preheat the limestone that has just entered the kiln, thereby reducing the heat carried away by the kiln gas and achieving energy-saving goals.

2. The furnace wall calcination zone adopts a layer of 345mm thick low creep high alumina bricks (DRL-145), the preheating zone adopts a layer of 345mm thick third grade high alumina bricks (ZL-55), the insulation zone adopts a layer of 345mm thick second grade high alumina bricks (ZL-65), the high-temperature zone non working layer adopts a layer of 230mm thick clay refractory bricks (PN-42)+clay refractory castable, and the insulation layer adopts a layer of 280mm thick lightweight castable, The addition of 30mm thick insulation refractory fiber and 3 layers of 10mm thick asbestos board in a four layer comprehensive insulation system greatly enhances the insulation effect of the kiln. Through the above measures, the heat loss in the calcination area of the lime kiln can be effectively prevented, thus achieving the energy-saving effect of the kiln.

6、 Specific measures to improve the quality of lime (raw and burnt rate, activity)

1. In this design, there is no wind cap in the center of the kiln, and the center of the materials inside the kiln drops faster than the surrounding area. The center of the kiln is loose and has a high porosity, making it easy for high-temperature flames to penetrate, thus ensuring even lime calcination.

7、 Lime production process flow

The lime production line consists of a raw material storage bin system, a batching system, a feeding system, a kiln calcination system, a temperature control system, an ash discharge system, a storage bin, a dust removal system, and automation control.

Process Flow Block Diagram: