RAP Multi-Pollutant Control System

Beaumont Environmental Systems offers both dry and semi-dry scrubbers. The RAP (rapid absorption process) offers improved operation at lower capital and operating costs, when compared with our  SAP (a nozzle type spray absorption processes) or our WAP (a wheel/ disk absorption process).  

These systems offer control of SO2,  HCl and other acid gases.  They are usually combined with a Pulse-Type or Reverse Gas type Baghouse to provide a multi-pollutant control system.

Mercury Control is achieved by cooling / conditioning in the lower stage prior to adding sorbent in the upper stage.

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Beaumont Environmental System – Multi-Pollutant Control System

 The BES RAP process removes sulfur dioxide (SO2), mercury and fine particulate matter from exhaust gases. Other key pollutants controlled by the process are Hydrochloric Acid (HCl), Sulfur trioxide (SO3), sulfuric acid (H2SO4), ash and toxic metals. The process includes a patented semi-dry Flue Gas Desulfurization (FGD) control system and a pulse fabric filter, designed to achieve high removal efficiencies at lower capital and operating costs compared to conventional wet FGD systems.

 How Does the BES Process Work?

The BES flash drying process uses a patented ‘Reactor’ and a ‘Pulse Fabric Filter, described below to control multi-pollutants.

 SO2 Control, Flash Drying Technology

The Rapid Absorption Process (RAP) reactor intimately mixes semi-dry lime sorbent in the flue gas stream to react with SO2 and SO3 gases. The resulting material is flash dried and collected in a fabric filter and recycled back into the reactor. A unique feature of the Rapid Absorption Process is that the entire process takes place at gas temperatures well above saturation, which protects the back-end system components from corrosion and buildup. Other attractive features of the BES process include:

  1. Lower Capital Costs (as low as $33/kW) Savings of 60%-70% over wet FGDs
  2. Smaller Footprint
  3. Non-Exotic Materials
  4. Simplified Controls
  5. Lower Operating Costs (as low as $173/ton SO2  removed)
  6. Reduced Maintenance Cost
  7. No Buildups on the Walls of the Reactor
  8. Reduced Levels of Material Handling
  9. Lower Volume of Lime Sorbent
  10. Higher Utilization
  11. Reduced Power Requirements versus Wet or Semi-Dry
  12. Phase-In Flexibility to Meet Compliance Targets

 High SO2 Removal at a Low Cost/kW

The capital cost for the BES Process is significantly lower than that of a wet FGD SO2  scrubber. Estimated savings in capital costs range from 60% - 70%. For example, in a 500 MW unit, the BES process costs as low as $33/kW compared to the $100 to $130/kW for a wet FGD scrubbing system. Additionally, the BES process is normally furnished in modules and therefore the cost/kW remains relatively constant across different sizes.

 2003 Cost Analysis

SO2 Removal Costs for a Sample 500 MW Unit (All costs are budget basis and will vary by individual unit)

 Unit Data Sizing

  1. Size Plant ACFM 1,741,879

  2. Hours of Operation (Yr) 8,000

  3. MMBtu's/Hr Rating 4,992

  4. Tons/Yr SOx Removed 61,845

  5. Disposal (Tons/Yr) 227,055

  6. Sorbent - Tons/Year 81,695

  7. Water (gal/hr) 22,963

Capital Costs

  1. RAP System $11,080,240

  2. Erection $5,254,592

Total $16,334,832, Cost in $/kW $33

Operating Costs

  1. Capital Recovery $1,277,820

  2. Water Cost $918,533

  3. CaO Costs $4,901,699

  4. kw - Booster Fan $464,640

  5. kw - Other $557,440

  6. Maintenance Costs $332,407

  7. Disposal Costs $2,270,549

Total $ 10,723,088 (for standard Spray Dryer add $4,000,000 for lime, power and maintenance)

Cost in $/Ton Removed $173

Assumptions

  1. Power Costs at $0.04/kWh

  2. Water Costs at $0.005 per gallon

  3. Maintenance Costs assumed at 3% Equipment Cost

  4.  Disposal Cost at $10/ton

  5. Lime Sorbent Cost at $60/ton

  6. Equipment Life at 25 years

  7. Interest Rate at 6%

Particulate Matter (PM) Control

The BES process applies a pulse-jet fabric filter system to collect solids for recycle and discharge. Medium (45 PSIG) and high (90 PSIG) pressure pulse systems are available. The BES process also offers a reverse gas cleaning system where dust is collected inside the bag instead of outside as in the pulse-jet fabric filter design.

Flexible features of the BES process for PM control include:

  1. High Pressure Cleaning

  2. Medium Pressure Cleaning

  3. Variable Bag Spacing

  4. High Inlet Loading Capability for Recycle (to 100+ grains/ACF)

  5. On-Line Cleaning

  6. Off Line Cleaning

  7. Combination Cleaning

High-Pressure Cleaning Units

The BES process offers bags with nominal 5 inch and 6 inch diameter using high pressure cleaning. These designs include variable bag spacing in both directions, online and offline cleaning along with a reduced-flow cleaning mode.

 Medium-Pressure Cleaning Units

The BES medium–pressure process varies the pulse cleaning pressure downward while increasing the flow utilizing large pulse cleaning valves. This design includes similar bag sizes as well as variable bag spacing. Additionally, to improve pressure drop and removal efficiency, the BES process can incorporate electrostatic charging rods into the pulse baghouse.

 Isolation Valves

Poppet valves are used when cleaning off-line. These valves provide metal-to-metal seals and low leakage as required for cleaning. They are used with pulse and reverse gas cleaning designs. The hopper arrangement along with inlet size and location into the hopper is of great importance in proper baghouse design. The BES process uses a plate type rectangular valve for this purpose. The valve must be properly incorporated into the inlet manifold to protect against excessive build-up and fallout within the manifold.

 Mercury Control

The BES process introduces a special oxidized calcium sorbent into the reactor to remove gaseous mercury by up to 90%. A proprietary Dry Absorption Process is used to introduce the oxidized calcium sorbents and cool the gases to a reactive temperature (200°F). The sorbents are carried into the pulse type fabric filter where a reactive cake is built on the surface of the bags. The oxidized calcium sorbents have been successfully tested for their ability to remove Elemental Mercury, SO2, SO3, and NOx. They offer an economical alternative to carbon in mercury removal.