Product Description

Process of Sludge Drying Furnace

The sludge dryer is specially developed for sludge-like materials with high moisture content, high viscosity, high water- binding capacity and low heating value. With features of internal structure of the dryer, thermal efficiency is increased, and stickiness and excessive dryness of sludge in the dryer are prevented.
Features of Sludge Dryer:
 (1) High thermal capacity coefficient, high thermal efficiency. Overall coefficient of heat transfer doubled, even tripled, that of traditional rotary dryers, thanks to the
combined effects of crusher and dasher, as well as to the revolving of cylinder. Exposure to hot air is increased by the crusher and dasher, meanwhile, shortness of hot air was prevented, and heat transferred by hot air are used more efficiently.
(2)Uniform product size. As viscosity of sludge is increased by flocculant added by sewage plant during dehydration, possibility of agglomeration during drying process is increased, which may compromise effectiveness of drying, and reduce feasibility of the plant(a clod crusher is required). Crusher and dasher, flexible kiln blade in the drying plant crushes clods prior to settling, and hence ensures uniform size(approx. 2mm) of products, therebv facilitates subsequent treatments and processes.
 (3) User-friendly operation. Automatic control system is provided with the plant. Two flames sizes are optional for the methane combustor. Temperature sensor in the end of drying rotator controls internal humidity of the drying roller by switching size of the flame, and so that to prevent coking of sludge in excessively high temperature. Revolving
speed of the roller is adjustable via the controlling cabinet.
 (4) Unique arch-collapsing and rapping devices are perfect solutions for cementation between material and dryer, material and lifter, and blockage caused by agglomeration of materials during drying process.
Process of Sludge Carbonization Furnace
The plant is entirely controlled by a PLC system which otters much lower labor intensity, controllable quality, safety, much less manual work, comparing to traditional operation mode. It mainly consists of conveyor belts, material bins, a carbonization furnace stack, a feeder, na actuator, refractories, a heater, a heater exchanger, fans, a cooling discharger, a dust collector, a waste gas disposal recycler, a PLC cabinet, an auxiliary preheater, an end-gas dryer for pre-treatment, and a combustor for end gas from drying furnace.
Collectively stored hydrated sludges are put into material bin of conveyor (approx. 6m3), and conveyed into pre-material bin by the conveyor, (waste heat furnace and
combustion furnace shall be heated before starting rotary furnace), and fed into furnace by the variable-frequency feeder for drying with heat from waste gas in lifter blade.
Dried materials are conveyed forward in the carbonization furnace for preheating gradually till desorption temperature (******0°C) is reached. Temperature control at this point is critical for the efficiency of carbonization of organic substances in sludge. The proper temperature shall be *******0°C during the ****5 minutes of carbonization period.
Proper air supply and feeding rates are keys to secure an effective carbonization, and prevent a temperature drop. Heat supplied by preheater shall be limited when temperature in the furnace reaches a constant level. Carbonized materials are discharged and cooled down to ******0°C through the rotary cooling tube of the rotary furnace, and then conveyed in to the cooling furnace again following rotation of the furnace stack. Carbonized materials leave the discharge tube at ***- **0°C，and then are conveyed into the secondary cooling furnace again following rotation of the furnace. Carbonized sludges are obtained after 3 minutes of water-cooling at an anaerobic  state in furnace.
Materials and end gas are flowing to opposite directions in the furnace, which is known as the reverse flow method. The heater mentioned below refers to auxiliary heating by natural gas or combustor for reaching the temperature required for activation when volatiles from materials are insufficient. End gas of ********0°C from high-temperature
combustion is induced into the drying furnace. A *-million-kilocalory combustor is provided with the combustion furnace. The waste gas (with a trace of dioxin) of ******0°C
at this point is induced into pouch-style pulse deduster by the fan on waste heat boiler through jet ammonium hydroxide pump, alkaline liquor spray tower, gas -water separator
 (condenser), quicklime jet tower, active carbon jet tower, cyclone collector and secondary alkaline liquor spray in sequence, and then conveyed into the active carbon absorption tank for waste gas collection before discharging to an elevation of *5 meters. The above regeneration cycle takes about 2 hours.
Carbonization sludges produced by the Sludge Carbonization Weight-reduction Treatment Plant may be used as biomass carrier for pretreatment of sewage, or deodorant for landfill leachate which has been proven to be effective in cost-saving for water treatment by experiment. Carbonized sludge offers a much preferable cost performance and efficiency than ceramsite, anthracite or any other filter material does, and saturated or fired sludge carbon can be used directly for brickmaking. Bricks made by sludge carbon are more intense, and free of spallation after exposure to high temperature environment.