Carbon Regeneration Kilns
Ideal for all Carbon Recovery needs
Heat Systems Carbon Regeneration Kilns are ideal for all Carbon Recovery needs. The TR Series Kilns are designed and engineered with three main principles in mind:
- To extend the life of the equipment;
- To perform servicing and maintenance with less difficulty; and
- Designed with the ability to plug-in additional units.
The Heat Systems TR Series Kilns are SCADA ready and have remote access capabilities. Your process can be monitored from a mobile device, from anywhere in the world. Additionally, we can update process parameters on the TR series kilns within 24 hours of receiving your service request, without having to put boots on the ground.
What is a Carbon Regeneration Kiln?
Horizontal indirect fired carbon regeneration kilns have proven to be the ‘work-horse’ in the regeneration of carbon for the past three decades. The concept of the equipment is based on an oxygen depleted environment within a rotating tube that is encased within a hot combustion chamber. This heat tube is fed with fouled or ‘spent’ carbon from a feed screw. Since the tube has angled lifters, its rotary motion imparts a gentle momentum to the carbon and the lifters also provide more effective heat transfer into the carbon bed. The gentle motion serves to expose the carbon to the regenerative atmosphere and heat transfer surfaces whilst taking care not to fracture the carbon.
The indirect fired (or heated) carbon regeneration kiln allows the carbon to be regenerated in an atmosphere without a direct heat source. The heat source (most commonly fuel fired burners) heat the combustion chamber where the rotating heat tube is exposed to that heat. The external heat then migrates through the skin of the heat tube and into the carbon.
The roll of the heat tube is to provide a steam rich, oxygen deprived atmosphere within the tube where all of the carbon (as the heat tube slowly rotates and agitates the product) is exposed to this atmosphere for approximately 20 minutes at a temperature of between 650°C to 800°C. The heat tube is manufactured from 253MA which is an exotic stainless steel that allows the heat tube to operate under such high heat conditions.
In some circumstances the spent carbon is transported into the feed hopper via water and therefore the carbon will bring a certain amount of moisture in its pores into the heat tube. As the wet carbon enters the heat tube, the moisture is flashed off as super-heated steam which both encourages the regeneration of the carbon, but also provides for a gas stream to allow any particulates that come off the carbon in a gaseous form, to exit the heat tube and the kiln via the discharge chamber.
For carbon that comes into the carbon regeneration kiln dry, either a small amount of water or steam needs to be introduced into the heat tube to create the steam rich environment needed to regenerate the activated carbon. The steam also acts as a barrier for oxygen infiltration into the heat tube. It is important to keep oxygen out of the heat tube as if it is present, the carbon being at regeneration temperature, would combust.
The kiln heat tube has a variable speed capability which has an influence on residence time. This in turn has an effect on the quality of the carbon regeneration. Every rotation removes a ‘cut’ from the solid bed using a simple scroll mechanism. As carbon flows through the tube it is dried and regenerated (or reactivated) to approximate or better than its initial virgin state.
As the carbon moves into the final stage of regeneration, the newly regenerated carbon is cooled by moving into the heat tube section where the external skin of the heat tube is exposed to atmosphere. This final process allows the carbon to recover its structural integrity prior to being discharged from the carbon regeneration kiln. In doing so, the regenerated carbon reduces its exposure to thermal shock if it discharges into a quench tank and at the same time, reduces the possibility of fracturing and creating carbon fines.
There are 3 standard kiln sizes on offer. The heat tube in each model is limited by carbon volume and the volumetric throughput rates below can be converted to mass throughput rates once the bulk density is known.
- TR550 < 0.7 m3/h
- TR800 < 1.4 m3/h
- TR1200 < 3.4 m3/h
Each model is designed to handle carbon that has up to 50% moisture content. However, it is important to note that these throughput values are based on a set 20 minutes residence time. If more residence time is needed, then these throughput volumes should be reduced accordingly. If you are unsure of your specific process needs, please contact us and we will provide a customized assessment for your application.
Furthermore, each kiln can be provided with a customized fuel option, ranging from LPG, Natural Gas, Diesel, Heavy Oil, Electricity and Biogas. Operating temperatures of between 650°C-900°C are typical.
- The carbon feed hoppers have been designed to effectively and efficiently dewater the carbon prior to entering the kiln. This style of hopper provides a much more user-friendly dewatering option and is almost impossible to block;
- Industry proven seal design;
- Provision of a ‘dewatering complete’ signal which avoids subjective and wasteful downtime as well as ensuring consistent feed moisture content for optimum regeneration;
- More efficient heat transfer achieved through features such as a curved kiln top cover, more substantive insulation within the combustion chamber and optimized baffle plate design;
- Added and improved inspection hatches, easily accessible bolts and lifting lugs;
- The split discharge chamber design means that a heat tube change can be completed within hours, rather than days;
- There is no requirement for any product pre-drying with the TR series kiln. This is historically a high maintenance and blockage prone area of the process. The kiln design maintains high energy efficiency via extended heat transfer surfaces around the tube;
- Dewatering within the hopper as well as below the hopper through the easy service pipe screen; and
- In contrast to other manufacturers, the TR series kiln does not require a water-cooled discharge chamber, therefore removing the requirement for the supply of large and constant volumes of cooling water. A dry back end prevents historical issues with tar condensation and blockage in this area.
- Access your data anytime from any location;
- Controls fully integrate with SCADA systems;
- View on multiple devices;
- The system can be installed in several languages;
- control of the unit from any mobile device; and
- Alerts when the kiln needs attention.
Heat Systems has placed a great deal of focus on the development of an efficient and effective de-watering system which has been proven to maintain consistent feed moisture time and time again. The benefit of this cannot be overstated, since consistent moisture presentation inevitably leads to consistent carbon regeneration.
It has also been identified that pre-drying often leads to poor regeneration due to the resultant lean steam environment in the kiln heat tube. Although often misunderstood, over-drying can result in the gasification and destruction of the skeletal structure of the carbon which in turn leads to higher vulnerability for fines generation and subsequent mineral losses from the process. For this reason, we advise against the use of complicated and blockage-prone thermal pre-drying in favour of a three-stage physical de-watering system.
Heat systems has also placed considerable focus on the design of the kiln from both process and maintenance perspectives. The TR series Carbon regeneration kiln was designed to be split into an upper and a lower half. In doing this, the kiln can be field stripped and serviced in far less time than an equivalent unit that has components that are built as a complete unit. For example, on a kiln that has a whole discharge chamber, this item needs to be removed in its entirety before a heat tube can be replaced. With the Heat Systems kiln, only the upper half of the discharge chamber is required to be removed to conduct the same exercise.
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