ENVIRO-KLEAN REMEDIATION GROUP INC

Thermal Desorbers

Enviro-Klean equipment is engineered and manufactured in North America, and meets UL, CSA and European CE standards.

All machine components are designed for years of productive service. (The KM-2 pictured on the right was built in 1994 and is still in operation.) The drives and gear boxes used to power the screw conveyors and augers are top-of-the line Eurodrive and Baldor. The electronics are Siemens. The fuel system is Eclipse. The heavy-duty trailers feature air-ride suspensions. Enviro-Klean is committed to providing competitive, state-of-the-art thermal remediation equipment that meets or exceed the toughest environmental standards world-wide.

KM-4 Series of Thermal Desorbers

Fuel Costs

The cost of fuel is the largest single expense in a thermal remediation project, and often is the difference in choosing between thermal desorption and landfilling. A typical thermal desorber uses 40 liters (11 US gallons) of fuel per ton to heat the soil, volatilize the hydrocarbons and soil moisture, and further heat the airstream to convert the hydrocarbons into water and carbon dioxide.

For the same throughput, the KM-4 uses 20 liters (5 US gallons) of fuel per ton.

The annual fuel saving based on 100K tons of throughput, is 2 million liters (520,000 US gallons).

Therefore, if the Enviro-Klean KM-4 design meets your remediation requirements, the fuel savings more than recover the capital cost of the equipment within a few years.

And together with the KM-4's portability and ease of operation, these fuel savings have the potential to create soil remediation opportunities that were formerly too cumbersome or costly to manage.

How It Works

The Enviro-Klean KM-4 is a patented high temperature thermal desorption system for removing hydrocarbon (petroleum) contaminants from the soil.

It's a mobile system with the processing equipment mounted on a highway-legal low-bed trailer and the feed/discharge system on its own trailer. The system can be easily moved from site-to-site and set up in a matter of hours. Its small footprint allows the KM-4 to operate in very restricted areas and process material right on-site. Throughput primarily depends on five factors:

• Type of soil
• Moisture content of soil
• Type of contaminant
• Level of contaminant
• Clean-up criteria

Under controlled conditions, this system can

• Have a nominal throughput of 20 tons per hour
• Process soil with contaminant levels up to 35,000 ppm (mg/kg)
• Clean soil down to non-detect levels
• Handle moisture levels of 20% or more

Loader and Conveyor

Soil is loaded into the feed system dump hopper and screened to <5cm (2 inches) by a rotating trommel screen. It is weighed and transported by belt conveyor to the in-feed hopper on top the machine. Then it's conveyed through the preheater and deposited into the KM-4's patented material processor.

Soil through Burner

Material is quickly heated to control temperatures in the Enviro-Klean KM-4 processor. The patented cascading system allows the soil to fall like a waterfall through several heated chambers. Heat is supplied using a fuel or gas burner at the bottom of the processor. It then travels upward through the soil curtains in the heat chambers, vaporizing the contaminants.

Thermal Oxidizer

An induction fan pulls the vapors from the top of the processor through a dust recycling system to remove particulate, and into the thermal oxidizer. Here, a secondary burner destroys the contaminants by heating them to over 1600°F (900°C). 

Filtration System and Exhaust Stack

The clean gasses are then cooled in an air-to-air heat exchanger and pass through a filtration system where the balance of the airborne particulate is removed prior to the clean air passing through an exhaust stack to atmosphere. Continuous or spot air emission monitoring can be done at the stack to show the emissions meet all regulations. 

Soils Discharge System

The soil, meanwhile, continues downward through the processor and exits the machine through a pugmill with a soil rehydration/cooling system and then onto a discharge conveyor to be stacked or piled for use as backfill or other purposes. The discharge temperature of the soil determines the level of cleaning achieved, hence the KM-4 operation speed is tuned by adjusting the soil discharge temperature.  

Major Components

• Feed system, including dump hopper, trommel, weigh belt, feed conveyor
• Feed hopper with laser-controlled material seal
• Preheater for incoming soil
• Four chamber primary treatment unit
• Pugmill for soil cooling and rehydration
• Multi-clone for fines removal
• Thermal oxidizer for up to 2-second residence time
• Air-to-air, 2-pass heat exchanger
• High temperature baghouse with pleated elements
• I.D. fan
• Air compressor
• Sound-attenuated genset
• Gas/fuel burners
• Automatic and/or Manual Control System
• Variable frequency drive motors
• Various heat, temperature and pressure sensors

Thermal Desorbers Applications

Soils

The Enviro-Klean technology can process a wide range of soil types. Some soils will be easier than others to work with and will thus increase the throughput of the machine. The feed system on the machine will remove any rocks or chunks over 5cm (2 inches) in size using a trommel screen.

The specifications for the KM-4 for soil classification refer to ASTM: D2487, with the sub-categories GW (well-graded gravel with sand), GP (poorly graded gravel with silt, sand, cobbles and boulders), SW (well graded sand), and SP (poorly graded sand). Combinations of these soil symbols will indicate a mixture of conditions and are the most common occurrences in nature, plus a``clay`` component.

Clay

Clay soil can prove to be a challenge depending on the type of clay present, moisture retention and tendency to lump into larger chunks. A certain amount of clay is usually present in most sub-soils, and the KM-4 can handle this material quite efficiently. The bottom line with clay – this material can slow the throughput down and make feeding the machine more difficult.

Silt

Some clay breaks down into very fine particles and becomes like powder – another concern for thermal remediation as these fines tend to make their way into the filtration system at increased volumes, causing overloading of the filters more quickly. To combat this potential problem, the KM-4 employs a multi-clone rather than a cyclone to remove 90% of the >50 micron particles from the airstream. Usually a by-product of organic clay and sometimes mixed with fine sand, silt is any soil particles that can pass at least 50% through a 200 mesh screen. High percentages of silt should be avoided or these soils should be blended with a larger aggregate material to minimize their adverse affect on the equipment. The soil symbol for silt is ML, while clay is either CL, OL, CH or OH.

Moisture Levels

Hydrocarbons in a soil matrix tend to attach themselves to water molecules. The thermal processor of the KM-4 will evaporate the water as it vaporizes the hydrocarbons. The higher the moisture content, the slower the machine will process the soil, and therefore the more it will cost to operate.

Moisture level in the soil can vary from one area to another by a considerable amount. The lower the moisture level of the soil, the less energy is required to boil the water out of the soil. The KM-4 specifications recommend that the moisture level not exceed 20%, or too much fuel is wasted dealing just with the water. Moisture levels below 15% increase the throughput capabilities greatly. Clays are especially bad when high moisture is present, because they tend to lock the moisture into their matrix and make it harder to remove.

A higher moisture content than desirable can often be remedied by an effective pre-treatment system. Sometimes, simply piling the soil up, covering it with tarps and letting it drain for a period of time, coupled with turning the pile(s) several time will make a major difference. Another method is using a trommel to aerate the soil before piling it up. This can also help to break up lumps in the soil and make it easier to process. The KM-4 includes a trommel with the feed system.

Type/Level of Contaminant

The KM-4 is designed to remove hydrocarbons from soil. The processor is designed with maximum heat-to-soil contact near the bottom of the soil boxes. The heat diminishes as it contacts soil in its rise upward as it gets pulled by the induction fan.

Hydrocarbons found in BTEX or gasoline contamination are much lower on the Carbon Chain than lubrication oils or Bunker C. The lower the Carbon number, the less heat is required to vaporize the contaminants. The less heat that is required, the faster the machine can process it, thus increasing its ``throughput.``

Soil Profile

Soils will quite often contain hydrocarbons ranging from C10 to C40, the latter being to upper range of hydrocarbons allowable through the KM-4. A contractor must be aware of the Soil Profile prior to estimating the throughput and the amount of fuel required to process a given site. The Soil Profile will also indicate the LEVEL of contaminant(s), registered in parts per million, (ppm), or milligrams per kilogram, (mg/kg).

Both these factors have a dramatic effect on the machine throughput, and therefore on the cost for cleaning up a site. The KM-4 is capable of processing up to 25,000 ppm (mg/kg) of hydrocarbon contaminants to Carbon 40, (C40), however, this would be the absolute worst-case scenario and therefore the throughput would be in the range of 12-15 tons per hour, (tph). With more favorable conditions, the throughput could reach 30 tph or more.

Operating Costs

The five factors: soil type, moisture content, contaminant type, contaminant level and clean-up criteria all vary from project to project. Therefore, one can see that the effect of the soil profile on the operating cost can be much different from site-to-site.

Source Emissions Tests

KM-3 tests were conducted in accordance with Environmental Protection Agency (EPA) standards as defined in document Title 40, Code of Federal Regulations, Part 60 (40 CFR 60), Appendix A, Methods 1, 2, 3A, 4, 5 and 25A, and Puget Sound Air Pollution Control Agency (PSAPCA) Method 5 back-half extraction procedures.

The independent testing laboratory, AMTEST, of Washington State ran three (3) 60-minute tests. The TDU processed 11-12 CY of soil per hour during the tests (16 to 18 tons). EPA Method 25A was performed to quantify emissions of volatile organic compounds (VOC) as THC using a flame ionization analyzer (FIA). PSAPCA back-half analysis procedures were used for considerable matter analysis.

FAQ's

1. How is the machine controlled when there are two trailers?

Our single load KM-4 system is contained on two trailers: one for the processing equipment and one for the feed system. There is an optional generator on board to supply power for both trailers and the control house with state-of-the-art electronic controls that has the controls for both trailers. One operator can handle the controls in either automatic or manual mode.

2. What is a typical cost of operating the machine?

Costs per ton…including fuel, two operators, loader operator and rental and basic maintenance is less than US$ 25.00 per ton. Fuel usage is $8.00 per ton.

3. Can the machine be operated continuously?

A machine can be run continuously 24/7, with up to 24 hours service each weekly/bi-weekly period. All major components (thermal oxidizer, processor chambers, heat exchanger, baghouse have inspection ports. Since the equipment is compact, all of the components and sensors are easily reached from ground level or step-ladder. The KM-4 is designed for easy field servicing.

4. Which parts of the machine require regular maintenance?

Motors and gear boxes are greased daily with the equipment in operation. The grease lines are routed to 5 common stations on the deck of the trailers. The process is completed within 30-minutes.

5. How is the machine fueled?

If using propane, one tank of 5000 gallons or more works best, because the supplier can refill it when needed. This is all supplied by a propane contractor. For natural gas, an industrial site supply is required rather than tanks. The generator requires diesel and has its own tank, which must be kept supplied. The KM-4 is also designed to operate on diesel or fuel oil, and are connected to an external fuel tank.

6. What is the total number of personnel used for every aspect of an 8-hour operation?

We recommend one fully-trained operator and one helper to operate the KM-4 per shift. A loader and operator are needed to keep the soil moving into the infeed system and away from the machine after it's cleaned.

7. What is the easiest soil to clean? What is the most difficult soil the machine can handle?

Throughput depends on 4 factors: Type of soil, moisture content of soil, type of contaminant, level of contaminant.

a. Ideal (27 – 30 tph): Gravelly-sandy soil with less than 15% moisture, Btex or diesel contamination to less than 10,000 mg/kg (ppm)
b. Worst case: (12 – 15 tph): Soil with over 20% moisture, lubrication oils, PAH or Bunker C contaminants over 20,000 mg/kg.

Note:
Moisture content is critical because fuel can be wasted just boiling off water from the soil. Quite often it is much less expensive to pre-treat the soil to remove the moisture either using a trommel or simply turning the piles over daily.

8. What is an optimum operating temperature?

Once you determine the parameters as above from a soil profile, the soil discharge temperature required to clean the soil to the desired level is found in the manual charts. The operator can preset this soil discharge temperature, which speeds up or slows down the augers automatically to give the desired temperature. Desorption is the opposite of absorption, hence the heat vaporizes the hydrocarbons in the Processor or``desorbs`` them where the gases are pulled from the Processor by the Induction Fan into the Thermal Oxidizer or secondary heat chamber where they are destroyed. The level of cleaning can be from 99 – 99.9999%.

9. What certifications according to US National and International norms has Enviro-Klean obtained?

Operating permits are required for most jurisdictions in North America. These are based on stack test results that prove the equipment meets or exceeds the regulatory guidelines. We have received these permits in Oregon, Washington, Alaska, British Columbia, Northwest Territories, Ontario, Newfoundland, Alberta, etc. – wherever our equipment has been in operation.

The Enviro-Klean equipment is the only Thermal Desorption equipment listed on the US EPA site and we are approved by the US Military, National Parks for USA and Canada, Korean Military, Karico, PSAPCA and other regulatory authorities.

The Enviro-Klean equipment has been designed to meet California regulations – the most stringent in North America, and can be permitted virtually anywhere in the world based on our test results.