Thermal Desorption Unit (short as TDU) is a specialized, environmentally friendly industrial system designed to treat hazardous oil sludge via oxygen-free (anaerobic) thermal decomposition. It converts oily sludge into valuable resources while eliminating environmental hazards, achieving harmless treatment and resource recovery. KES Separation TDU can be widely applied to waste from oilfields, refineries, tank cleaning and drilling operations.
TDU working procedures consists of 4 stages, feeding, heating, cooling and discharge. There are some key points need to pay attention during each working procedure.
1st Stage: KES Separation TDU Feeding Process
The TDU can treat a wide variety of raw materials. The feeding cycle ranges from 2 to 4 hours, depending on material properties. Drilling cuttings, available in both wet and dry forms, are taken as the typical processing material.
For wet drilling cuttings with high water and oil content, the operator can adopt rotor pumps or pneumatic Wilden air pumps to pump the slurry to the reactor. Dry drilling cuttings with low moisture content are fed via screw conveyors.
To satisfy diversified feeding demands, three ports are arranged at the feeding end of the reactor. The middle main port is dedicated to screw conveyor feeding; a 2-inch flanged port allows hose connection for pumping wet cuttings into the reactor. The third flanged port serves for real-time material level observation inside the reactor.
2nd Stage: KES Separation TDU Heating Process
Once materials are fed up to the safe level inside the reactor, the heating procedure can be initiated. Standard operating steps are as follows:
- Start the air compressor and induced draft fan first. The air compressor provides compressed air for oil burners, while the induced draft fan extracts flue gas from the furnace.
- Inspect fuel diesel and confirm it is free of water impurities.
- Ignite the burners for furnace heating. Maintain a low flame for gentle preheating at the initial stage. Raise flame intensity appropriately when the reactor temperature rises to 120~150℃.
- On-site operators must stay on duty for full-process inspection during heating.
- The maximum Air drum working pressure shall not exceed 0.006 MPa. Close monitoring is required once pressure reaches 0.002~0.003 MPa, and troubleshooting shall be conducted promptly.
- Keep observing the water level inside the dust removal tower and replenish water in time if the level is too low.
- Control the water tank temperature below 60℃. Activate the cooling tower once overheating occurs; drain hot water and fill with external cold water if necessary.
- Check the sight glass pipe continuously to monitor the flow of condensed water and oil.
- Criteria for burner shutdown: Compare temperature readings of the reactor and air drum. A continuous temperature drop in the air drum relative to the reactor indicates cessation of oil and gas generation inside the reactor. Meanwhile, zero oil flow observed through the sight glass pipe ahead of the oil tank is another confirmation signal.
- After burner shutdown, open the manual safety valve mounted on the top of the air drum for pressure relief and ventilation.
The main equipment in Heating process is the heating reactor, it can be made by Q345R Boiler steel, SS304/SS316/SS321. The heating reactor made by Stainless steel have longer lifespan compared with Q345R boiler steel. However, the heating period might be a littler longer because of the lower thermal conductivity value.
The auxiliary tools working with the heating reactor including furance, introduced draft fan (ID fan), air compressor, fuel tank, fuel oil burners, waste gas fire gun. The ID fan is used to suck the flu gas out from the furnace. The furnace is made with steel outer shell and high-temperature resistant bricks and cement which can bear up to 1000℃.
During heating period, the cooling function of the cooling tank is very important for safety and valuable oil production. Sufficient cooling water volume can cool down the evaporated oil gas and water vapor very quickly, and the oil and water will be storage in oil tank after condensation. With the volume increasing in the oil tank, the operator can pump the water out and discharge it directly. Meanwhile, the oil will be kept storage in the oil tank.
Insufficient cooling water volume will be dangerous for the TDU operations. The generated oil gas and water vapor cannot be condensed quickly, and it might lead to positive pressure in the heating reactor, air drum and the pipelines. The heating reactor, air drum and pipes are not designed according to pressure vessel standard, they can maximum bear up to 0.008Mpa pressure. Usually, we suggest client to prepare one 60cbm water pond or water tank to connect with the cooling unit in the TDU to exchange the water and heat.
3rd Stage: KES Separation TDU Cooling Process
Keep the induced draft fan running during cooling to exhaust hot flue gas, to shorten the overall cooling period.
Ash discharge can be commenced when the internal reactor temperature drops to 100~150℃. Special attention shall be paid to the temperature of two auger bearings, which must be kept below 100℃. Excessively high temperature will cause bearing softening and deformation, leading to frequent maintenance and lowered operational efficiency. The discharge conveyor is equipped with water jacket, the operator can connect cooling water for cool down the auger during high temperature ash discharging process.
Get more information from the On-site Working videos of KES Separation TDU
4th Stage: KES Separation TDU Discharging Process
There are two ash discharge modes: high-temperature discharge and low-temperature discharge.
High-temperature discharge enables ash removal at high temperatures, which shortens cooling time and boosts operational efficiency. Nevertheless, operators must ensure full sealing from the heating reactor through the discharge screw conveyor to the ash tank. Reliable sealing is critical to prevent flash explosion. Meanwhile, the discharge screw conveyor shall be fitted with cooling water circulation to avoid damage caused by high-temperature ash. This mode allows ash discharging while the heating reactor maintains a temperature of 250~280℃.
Low-temperature discharge operates at 100~150℃. Under this condition, cooling water for the discharge screw conveyor is generally unnecessary, yet special attention shall still be paid to bearings at both ends. Since the reactor temperature drops to the safe range of 100~150℃, ash can be directly discharged into open containers or waste skips.
The overall ash discharge period ranges from 3 to 6 hours, depending on residual ash quantity and the internal ash collecting chute structure. After targeted structural optimization, our ash discharge efficiency has increased by approximately 50%, effectively reducing labor costs and saving operating time. Please contact our sales staff for detailed discharge operating procedures and safety operation specifications.
Leveraging abundant field operation experience, KES Separation has carried out multiple structural upgrades. Our self-developed and supplied TDU is highly adaptable to actual working conditions for drilling cuttings disposal.
As a professional manufacturer specializing in solid control and drilling waste management, KES Separation takes the lead in offering a full lineup of relevant equipment, including vertical cuttings dryers, high-G dryers, decanter centrifuges, water-based mud dewatering systems, screw conveyors, offshore mud skips, pneumatic cuttings transfer system, and oil-based cuttings thermal desorption units. The TDU functions as the final core processing unit in the complete drilling waste disposal workflow, KES Separation Thermal Desorption Unit (TDU) is a mature, modular thermal treatment system designed for the harmless treatment, volume reduction and resource recycling of drilling waste and waste slurry. As the core terminal equipment of the full drilling waste management process, it forms a complete closed-loop disposal system by cooperating with upstream solid control equipment, realizing full-process standardized and pollution-free treatment of drilling waste from initial separation to final harmless disposal. Hereunder with descriptions of the Drilling cuttings and oil sludges resources which require final treatment by Thermal Desorption Unit.
Resources No.1: Vertical cuttings dryer
Vertical cuttings dryer is engineered to treat the OBM cuttings discharged form shale shakers, for both onshore and offshore. It can help to recover the oil-based mud for reuse and generate dry cuttings with less than 5% oil on cuttings. This is very good performance and can increase the working efficiency of Thermal Desorption Unit. The popular brand of Vertical cuttings dryer includes CSI dryer, Elgin Vertical dryer, Swaco cuttings dryer and KES Separation Vertical dryer.
High G dryer is engineered to treat the WBM cuttings discharged from solids control line shakers. After separation, the recovered water-based mud can be pumped back to solids control system for reuse. However, the thick WBM cuttings usually don’t need to be treated by TDU as it is considered non-environment harmful. and we can use WBM dewatering unit to treat it, and get thickened mud cake and clean water for disposal.
Get more information from on-site working videos of KES Separation Vertical cuttings dryer & other drilling waste management equipment
Resources No.2: The Drilling Cuttings from Mud cleaners
The OBM cuttings separated by mud cleaner is already very fine. After the 10in desander cones separation, the separated cuttings is about 40~70microns and after the 4in desilter cones separation, the separated cuttings is about 15~40microns. The cuttings is very minor and cannot be separated again by vertical cuttings dryer. These cuttings need to be collected temporarily by mud skips as well and transport it to TDU for final treatment.
Resources No.3: The thick sludge separated by Decanter Centrifuge
Decanter centrifuge is the last stage separation equipment in solids control, which can cut 2~5microns cuttings out from the drilling mud. The decanter centrifuge play the roles of reducing mud weight and adjust the mud properties.
The thick sludge separated by decanter centrifuge is very thick and very sticky. This part of oil sludge can only be treated by TDU as final treatment.
Resources No.4: The contaminated soil in the drilling site
During the drilling operations, sometimes it will occur soil contamination because of oil spills, and the contaminated soil need to be final treated by TDU considering the environmental issues.
Meanwhile, the tank bottom sludges in the mud tank and crude oil tank, the oil sludges in the sludge pit can also be treated by Thermal desorption unit.
With rich overseas project experience, KES Separation TDU systems have been successfully deployed and operated in multiple African countries, serving local oil and gas drilling contractors and energy service companies. All field units maintain long-term stable continuous operation, adapting to harsh environments including high temperature, dust, and unstable on-site power conditions. Compared with traditional incineration and chemical cleaning methods, the KESS TDU features low energy consumption, zero secondary pollution, high oil recovery rate, and fully automatic operation, greatly reducing on-site labor input and overall waste disposal costs.
Customized skid-mounted and containerized TDU solutions are available to meet mobile drilling demands, enabling fast installation, convenient transportation, and rapid commissioning for temporary and remote drilling projects. Till now, KES Separation has provided one-stop drilling waste management solutions for dozens of domestic and overseas oilfield projects, establishing reliable technical and service advantages in the global solid control and waste treatment industry.
TOP 5 World-Class Thermal Desorption Unit (TDU) Brand
1. NOV Brandt (USA)- World famous Oilfiled solutions provider.
Full name: National Oilwell Varco. Its Brandt division is a leading enterprise in solid waste and drilling cuttings treatment. It features heat-conducting oil type TDU with over 20 years of on-site application experience, holding high market share in high-end onshore and offshore oilfield markets.
2. Vulcan (USA) – Leading TDU Brand Profile
Vulcan (often referred to as Vulcan Industrial or Vulcan Environmental Solutions) is a well-established U.S. manufacturer specializing in high-performance Thermal Desorption Units (TDUs) for oily sludge, oil-based drilling cuttings, and hazardous waste remediation. With decades of engineering expertise, it is widely recognized as one of the top TDU brands in North America, competing directly with NOV Brandt and other industry leaders.
3. KES Separation- China leading brand TDU
KES Separation (short for KESS) series TDU with processing capacity 10-100 tons per day. Equipped with thermal oil indirect heating system, the brand provides flexible mobile modular TDUs and heavy-duty fixed-type TDUs to meet diversified project demands. Its products are widely applied to oily sludge and drilling cuttings treatment, gaining extensive recognition in Africa and the Middle East.
4. Veolia (France)- World famous Environmental solutions provider
World-class full-chain environmental service giant, offering integrated TDU plus wastewater treatment and incineration solutions, widely adopted for large-scale contaminated site remediation.
5. Siemens Energy (Germany)- World famous Industrial Solutions providers
Provides large-scale industrial thermal desorption systems equipped with flue gas treatment and energy recovery units, ideal for hazardous waste projects in refineries and large oilfields.
