Dry Sorbent Injection

Since 2004, United Conveyor Corporation (UCC) has led dry sorbent injection technology which injects selected sorbents into the flue gas to control SO2, SO3, mercury and HCI. UCC is recognized as the technology leader who delivers optimal system performance and confidence to our customers as we work closely with customers to deliver a reliable solution to specific to their plant needs.

UCC Advantage

Our experience, cutting edge technology, and customer support set us apart from other suppliers. UCC offers single point accountability from sophisticated predictive modeling design to lab testing and evaluation of sorbent type, injection rate and the effects to existing ash handling systems. Through our extensive experience with simultaneous SO2, SO3, HCl and Hg removal, we offer comprehensive compliance strategies and low cost solutions for efficient system performance.

  • Performance-based turnkey solutions
  • Over 25,000 hours of DSI demonstration testing
  • VIPER® Mill Technology delivers the highest removal efficiency and greatest cost savings
  • Patented COBRA™ Lance maximizes particle dispersion in DSI and ACI systems

UCC is committed to innovation and technology that deliver performance advantages in our dry sorbent injection systems. Continual efforts focus on improving removal efficiency, eliminating chances of plugging and system design practices that drive operational reliability.


Our commitment to innovation delivers cost effective results in dry sorbent injection and robust systems that achieve removal goals with minimal use of sorbent.

  • Splitters – UCC splitters are designed to optimize even sorbent distribution and high removal efficiency while minimizing the risk of plugging
  • COBRA Lance – UCC lances are engineered to maximize particle dispersion and eliminate plugging with no impact on pressure drop in DSI and ACI systems
  • Injection Lances – UCC lances are engineered to maximize particle dispersion and eliminate plugging with no impact on pressure drop
  • CFD Modeling – UCC specializes in Computational Fluid Dynamic (CFD) modeling of plant duct flows to predict and enhance sorbent distribution in flue gas while minimizing sorbent usage

Proven Milling Technology

The VIPER® Mill is proven, reliable technology developed specifically for dry sorbent injection. The patented VIPER Mill operates in-line with the DSI system and delivers the smallest particle size, highest throughput and greatest cost savings in the industry. The result is 30 – 50% lower sorbent usage compared with as-delivered material.

  • Designed for trona and sodium biacarbonate
  • Capacity: 0.5 – 7 tons per hour
  • Median particle size: 9 – 15 µm (trona), 15 – 19 µm (SBC)
  • Reduced sorbent usage saves millions of dollars

Skid Mounted Installation with Automated Cleaning

The VIPER Mill is equipped with an automated cleaning system to eliminates sorbent build-up. The cleaning cycle ensures consistency in particle size while balancing horsepower, temperature rise and sorbent throughput. The VIPER Mill uses either a simple bypass system or redundant skid for uninterrupted DSI operation.

  1. We already have marginal ESPs, is dry sorbent injection an option for SO3 control? Or SO2 control?[+]

    Yes. In some cases, trona or sodium bicarbonate are considered solely for the purpose of improving ESP performance. Typically the rates of injection required for SO3 control are low enough that either hydrated lime or trona can be an option to achieve greater than 80% removal without a negative impact to ESPs. However, in some cases hydrated lime may negatively impact ESP performance and trona may be a better option since trona typical has no impact, or may even improve ESP performance. For SO2 control, trona or sodium bicarbonate are the most likely sorbents and both sorbents typically either improve performance or have little impact, even at high injection rates. In some cases, we have almost doubled the loading on ESPs without negatively impacting opacity or PM at the stack.

  2. Is dry sorbent injection a possibility if we need to achieve greater than 90% SO2 removal?[+]
    Yes. Typically sodium bicarbonate is the sorbent of choice to reach 90% SO2 removal, however, in some cases milled trona may be the most cost effective option. Testing needs to be performed to adequately compare the long-term cost differences between each. If greater than 90% removal is required, then dry sorbent injection AND a lower sulfur coal may be required.
  3. I’ve heard about dry sorbent injection systems with plugging issues at the splitters and lances. Why not reduce the number of lances and simply use an open pipe for a lance?[+]
    There is no doubt that reducing the number of lances and using an open pipe will reduce material handling difficulties. HOWEVER, sorbent expenditures will be the largest life cycle costs and making these changes significantly increase your sorbent usage. We have developed techniques to avoid significant plugging in order to continue to provide the most effective sorbent usage possible. This saves millions of dollars over 20 years, even on relatively small systems.
  4. Why is in line milling necessary? Can’t material be milled off site and transported less expensively? Or milled at the silo discharge and then fed into a conveying line?[+]

    Milling is required if sodium bicarbonate is needed since it cannot be transported in a small enough particle size to be effective while maintaining reasonable handling characteristics. Although trona can be delivered in an “unmilled” state that will provide reasonable removal, the trona usage can be reduced by as much as 50% by milling it. In both cases, milling in-line is necessary to avoid downstream material handling problems if the material is stored. Even if the milled material is successfully milled, stored and then fed into a pressure conveying system, it is not possible to avoid some reagglomeration of the material when it is stored immediately after milling. Even reasonable temperature increases during milling will enhance agglomeration.

  5. Why is computational fluid dynamics modeling necessary if a full scale test is going to be performed?[+]

    CFD modeling ensures the right questions are being asked to properly place injection lances to achieve the most effective use of sorbent. We have seen a 20% reduction in sorbent usage based on modifying lance location and design to match a CFD model. In other cases, CFD modeling may be able to explain why the maximum removal achieved is less than predicted by demonstrated how a portion of the ductwork is not receiving any sorbent. The impact will not always be this dramatic, but even a 5% improvement in sorbent usage will pay for itself in less than one year.

VIPER Mill Technology

The new patent-pending VIPER™ Mill is a proven, reliable technology that significantly reduces operating cost and improves emissions control of dry sorbent injection (DSI) systems.

DSI On-Site Demonstrations

DSI On-Site Demonstrations United Conveyor Corporation is the industry leader and the first to provide customer on-site demonstration.  UCC has over 25,000 hours of Dry Sorbent Injection (DSI) demonstration tests. Full-scale, on-site DSI demonstrations help utility customers address regulatory requirements for th