Daswell vertical preheater is an important heat recovery equipment of modern lime calcination plant. It is usually attached to the end of rotary lime kiln. Daswell vertical preheater preheats/pre-calcines limestone feed by using the exhaust hot gases from the limestone rotary kiln before entering the preheated limestone into the rotary kiln for further calcining. And Daswell vertical preheater has proven to be efficient piece of heat recovery equipment that can precalcine parts of the limestone feed. The vertical preheater can significantly reduce energy consumption and is intensifies the kiln’s utilization which can make high capacity. Daswell machinery offers durable and reliable preheater kiln system for lime calcining plant to reduce energy consumption. Daswell vertical preheater can be an integral part of modern lime plant and can be applied to upgrade existing lime plant with vertical cooler.
Features of Daswell Vertical Preheater
- Two basic prheater shapes available. It comes with rectangular and polygon shapes.
- Wide range of preheater sizes options. The preheater for lime calcining system are of different sizes with different modules and plungers. Customers can choose the fit one according to their needs.
- Automatically control. The discharge plungers of the preheater are controlled by computer so that they can meter the limestone feed into the rotary lime kiln at controlled rate.
- Excellent heat recovery. Daswell preheaters are designed with genius so that it is well sealed and ensures the efficient counter-flow heat transfer in the preheater. As a result, the vertical shaft preheater can be efficient heat recovery and energy-saving equipment.
- High quality. The preheater is of robust design, and the inside of the vertical preheater are equipped with refractory lining throughout. As a result, the Daswell vertical shaft preheater can be durable and reliable equipment for quicklime plant.
- Cost efficiency. As stated, vertical shaft preheater can precalcite the limestone feed using hot process gases from the rotary lime kiln before further calcining in the kiln. So the preheater can save energy consumption of the kiln, shorten the lengths of rotary lime kiln and uses the fuel efficiently. All these in turn can reduce the operation costs.
Vertical Preheater for Quicklime Plant 
Vertical Preheater for Lime Calcination Plant
Dasdwell Vertical Shaft Preheater
Daswell vertical shaft preheater, along with vertical cooler, is an integral part of rotary lime kiln system for lime plant. The combined work of vertical preheater, rotary lime kiln and vertical cooler make efficient counter current flow in the system and can save energy to produce high quality and high capacity of quicklime. And Daswell has made several successful preheater kiln lime calcining systems around the world. As a consequence, the preheater kiln system is ideal for quicklime plant. Daswell preheater is made of high quality materials so that can enjoy long time service life. And its internal design is carefully designed with high technology. So the vertical shaft preheater can work efficiently to recover heat and save energy consumption. In fact, the preheater can not only be a part of new quicklime plane with rotary lime kiln, it can also be applied to upgrade existing lime plant with rotary kiln to save energy.
Structure of Daswell Vertical Preheater
- Upper feeding system. It includes the upper hopper, discharge chutes, hopper legs and so on. Its main purpose is to ensure the device is well sealed and prevents air flow into the vertical preheater.
- Preheater body. The preheater is made up with adjoining modules which can be arranged to form rectangular and polygon shapes. In fact, the body of the preheater is main device to preheat the limestone feed with exhausted hot air from the kiln. So the preheater is entirely equipped with refractory lining to stand high temperature.
- Discharge plungers. Discharge plungers are used to meter preheated into the kiln.
- Hydraulic system. It includes oil pump, oil box, motor and so on. And the system is used to push the discharge plungers.
- Transfer chute. At the bottom of preheater, there is a transfer chute and it is connected to the rotary lime kiln feed end. It is from the transfer chute that the preheated limestone is transferred into the rotary lime kiln.
- Recycle system. It includes dust collecting system, such as recycle silo, recycle slide pipe and so on. For in the preheating process, it can produce carbon dioxide.
- Framework. It includes columns, ring beams and so on to support the whole vertical preheater.
| Capacity (t/d) | 150 | 200 | 250 | 300 | 400 | 500 | 600 | 800 | 1000 | 1200 | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Material | Limestone | ||||||||||
| Vertical Preheater | 4 Pusher head | 6 Pusher head | 8 Pusher head | 12 Pusher head | 14 Pusher head | 18 Pusher head | 22 Pusher head | ||||
| Rotary Kiln | Kiln Size (m) | ø2.5×40 | ø2.8×42 | ø3.0×48 | ø3.2×54 | ø3.4×54 | ø4.0×52 | ø4.0×60 | ø4.5×64 | ø4.9×70 | ø5.24×72 |
| Burning Temperature (°C) | 1350/1250 | 1350/1250 | 1350/1250 | 1350 | 1350 | 1350 | 1350 | 1350 | 1350 | 1350 | |
| Blocking-wheel Mode | Hydraulic or Mechanical | Hydraulic | |||||||||
| Cooler | Vertical Cooler | ||||||||||
| Fuel | Coal, Coal Gas, Natural Gas, Diesel Oil, Heavy Oil | ||||||||||
| Heat Consumption (KJ/KgCaO) | 5300/5000 | 5300/5000 | 5300/5000 | 5200 | 5200 | 5100 | 5100 | 4810 | 4810 | 4810 | |
Preheater Kiln Lime Calcining Process
Limestone, mainly contains calcium carbonate, when heated at a high temperature, can be split into quicklime and carbonate dioxide. The quicklime is left as the lime produce, while the carbon dioxide is driven off from the rotary lime kiln. The process takes place mainly in three pieces of equipment: vertical shaft preheater, rotary lime kiln and vertical cooler. The vertical shaft preheater will preheat the limestone feed using the hot process air from the rotary kiln, and then the partially calcined limestone will be put into the kiln. In the rotary lime kiln, the limestone finishes the calcining process. And then from the kiln, the lime product, quicklime will be discharged into vertical cooler where the quicklime it cooled so that it can be handled by belt conveying equipment.
Daswell Rotary Lime Kiln Preheater Process
How does the preheater for lime calcination work? Limestone of 10-50mm is fed in the preheater through conveyor. The limestone will first go to the upper silo. And from upper silo of preheater, the limestone feed will go to separate preheater modules through the discharge chutes. There, due to the counter current air flow, the limestone feed will be preheated with the hot process gases from the kiln. After the preheating process, parts of the limestone will be calcined. At this time, the discharge plungers, controlled by computer, will push the partially preheated limestone into the rotary lime kiln through transfer chute. In the limestone rotary kiln, the preheated limestone will finish the final calcining. And the carbon dioxide produced from the preheating process will be transferred to dust collectors and finally into the chimney.