Slurry solutions for the FGD Power Plant.

The Vacucam® Slurry Systems are capable of making limestone slurries with 30+% solids on a single pass. The VACUCAM® Ejector Mixer represent the heart of the process, providing major benefits that cannot be achieved with traditional mechanical mixers.

Process Options

Three process options are available to meet any plant capacity and provide the most efficient use of plant logistics. All processes provide for dry material storage and conditioned feed to the slurry process. With high capacity slurry making, high quality slurry of 30%+ solids can be delivered to one or multiple scrubbers. A single system can produce ample slurry into storage tank(s) and a second unit can be provided for stand-by.

Option 1: Single Pass Process Direct Into Slurry Storage Tank(s)

A single or a dual VACUCAM® mixer assembly is mounted to discharge directly into the top of a slurry storage tank. The mixer assembly conveys conditioned limestone powder from a surge hopper located below the silo discharge, slurries the powder with water on a single pass to 30%+ solids and discharges the slurry into the slurry storage tank. Slurry make-up is on demand based on slurry storage requirements. The mixers can be operated as a single unit, or as a dual unit depending on slurry make-up demand. This process configuration requires the slurry storage tank to be located directly below the silo.

Option 2: Single Pass In-Line Process to Remote Slurry Storage

The skidded packaged Vacucam® in-line slurry module is located near the silo discharge. The module conveys conditioned limestone powder from a surge hopper located below the silo discharge and slurries the powder with water on a single pass to 30%+ solids. The finished slurry is continuously pumped from the in-line slurry tank to one or more slurry storage tanks. A level transmitter on the in-line tank controls the VFD on the transfer pump. The process can be supplied as a single pass steady state process by measuring the finished slurry density discharging from the mixer. The water delivery rate to the mixer can be adjusted by ±15% to maintain targeted solids levels.

Option 3: Single Pass Process for Direct pH Control to Scrubber

This process is designed to deliver limestone slurry directly to the FGD Scrubber based on a pH feedback loop. A fixed portion of the scrubber make-up water is diverted to the skidded VACUCAM® in-line slurry unit. The unit conveys conditioned limestone powder from a surge hopper located below the silo, slurries the powder with the scrubber make-up water and delivers the slurry to the scrubber as required to maintain pH set-point. The pH control loop regulates the speed of the rotary valve on the silo to deliver limestone powder to the unit at the rate required to maintain the pH set-point. Slurry solids level will vary depending on the amount of limestone required to maintain pH.

Hg Removal – [MRCS] Mercury Re-Emission Control System

The Purpose of the MRCS is to inhibit re-emission of mercury from the wet FGD [WFGD] liquor and thereby increase the total mercury captured and retained in the FGD system. Mercury re-emission can occur when soluble Hg+2 reacts via various mechanisms in the wet FGD liquor and is reduced to insoluble Hg, which then re-enters the gas phase and is emitted with the FGD outlet flue gas. The MRCS will inject an additive such as Powered Activated Carbon (PAC) into the WFGD slurry to absorb and sequester oxidized mercury before it can be reduced to the elemental form and re-emitted.

This modular process is based on the incorporation of the Vacucam® Ejector Mixer Slurry Process to provide the most efficient dust free mixing of the hydrophobic PAC product with water.

Process Options

Two process options are available to meet any plant capacity and provide the most efficient use of plant logistics. All processes provide for dry material storage and conditioned feed to the slurry process. The Vacucam® Ejector Mixer Slurry Process is capable of delivering slurry with up to 10% solids to one or multiple scrubbers. A single system can produce ample slurry into storage tank(s) and a second unit would be provided for stand-by.

Option 1: PAC Storage | Single Pass PAC Slurry / Delivery Process | Injection Control

The skidded, packaged, single pass slurry process module is located underneath the silo discharge. It conveys PAC power directly from the batch weigh hopper with Air-Cone? discharge, slurries the PAC with water and discharges the slurry into a day tank.   The finished slurry is pumped from the day tank to one or multiple injection points on a controlled basis. Slurry batches are produced on demand to maintain a setpoint level in the day tank.

Process Flow Schematics – Multiple Injection Control for Single Scrubber

Option 2: PAC Storage | Single Pass PAC Slurry | Direct Batch Slurry to Multiple Scrubbers

The skidded, packaged, single pass slurry process module is located underneath the silo discharge. It conveys PAC powder directly from the batch weigh hopper with Air-Cone? discharge and slurries the PAC with water. The finished slurry is pumped from the in-line slurry tank directly to one or multiple scrubbers.  A level transmitter controls the VFD on the transfer pump to enable slurry batches to be produced on demand.

Process Flow Schematics – Injection Control for Multiple Scrubbers

Utilizing the VACUCAM® Ejector Mixer Slurry Process for producing PAC slurries offers major benefits for FGD in Power Plants that cannot be achieved with traditional mechanical mixers. The Systems are typically designed for single pass or batch processing of up to 10% solids. The VACUCAM® Ejector Mixer units represent the heart of the process, providing major benefits for PAC slurries feed to scrubbers.

• No Moving Parts
  • No mechanical conveyors
  • No pneumatic conveyors
• Low Maintenance
• Low Energy
• Efficient Dispersion and Mixing for high yield process reaction
• Total Dust Control
• Rapid Start/Stop w/high capacity for total automation of slurry feed.
• Provide System Redundancy within one system. One system can support redundancy for second scrubber.

NOx Reduction – [SNCR] Selective Non-Catalytic Reduction Process

SNCR is a post-combustion NOx reduction method that reduces NOx through a controlled injection of an aqueous urea solution into the combustion gas of industrial fired sources including: coal-fired boilers; waste-fired boilers; incinerators or heaters. The most commonly used reagent consists of a 50 % Urea solution. SBS provides the most efficient Continuous Steady State Process for handling Urea prills and rapidly and continuously converting them into Urea Solution.

Semi-Bulk Systems provides a totally automated and modular turn-key design for receiving and handling Urea prills and delivering a Urea solution to storage or directly to the furnace.

Process Options

Systems can be designed for total bulk delivery of Urea Prill from bulk rail cars, bulk trucks, bulk silo, bulk bags or paper bags. If the delivery silo cannot be installed adjacent to the mix skid, a pneumatic receiver will be located to supply continuous Urea prill feed to the mix station. A pneumatic receiver can be supplied directly from a remote silo, a rail car, or a bulk truck. Paper bags can be unloaded into a surge hopper for continuous delivery to the mix station.

Urea Prill is typically dissolved into a 50% Urea solution. The reaction of Urea prill into water produces a highly endothermic reaction requiring the addition of heat to dissolve the prill at a temperature to achieve stability for a given concentration.

Continuous Steady-State Processing of Urea Prill into Urea Solution

The VACUCAM® Ejector Mixer unit is designed into a modular skidded process. The VACUCAM® Dynamic Continuous Steady State (DCSS) Slurry Skid inhales the prill from the pick-up funnel below the feeder. Heated water (170-175°F) is supplied continuously to the slurry skid. The rate of water addition is controlled by the feedback from a density meter to control the concentration at set-point [typically 40-50%].

The water pumped through the Ejector Mixer generates a vacuum to convey the prill into the high velocity liquid flow through the mixer for rapid reaction and dissolving. The second pump circulates the mix and returns solution back to the mix tank until the mix reaches solution set point. When the mix reaches its set point [50% solution], the valves divert the recycled liquid to Urea solution storage. Fresh heated water addition is slaved to the rate of prill addition to maintain 50% solids. The solution is recirculated through a mass flow/density meter to confirm and control the concentration level before it is continuously pumped forward to the storage tank.

The process maintains the temperature of the solution at a set-point temperature to overcome the endothermic heat of reaction of the Urea and achieve rapid dissolution. The final solution temperature will be approximately 92°F with an endothermic temperature loss of approximately 78°F, which is approximately 30°F above the salt out temperature of 50% Urea solution.

The process achieves total reaction and solubility with initial hot water only. No additional heat needs to be added to the process before solution is pumped to solution storage tank.

Process Flow Schematic – Continuous Steady State Processing of Urea Prill into Urea Solution: Paper bags; Bulk bags; and Bulk Truck.

VACUCAM® Ejector Mixer

Semi-Bulk Systems VACUCAM® Ejector Mixer Dynamic Batching Station provides the most efficient dispersion, mixing and hydration of ALL dry ingredients used in today’s broad range of product types and ALL Beverage Processes.

The Vacucam® Ejector Mixer is the most effective system available for conveying, wetting, and dispersing powders into liquids.

Here is how it works.

Conditioned powder is conveyed into the mixer by a near-perfect vacuum, which is created when pressurized fluid is discharged as a high-velocity, hollow jet into which the powder is drawn.

The high speed dispersion mixer.

The Vacucam® system achieves high-speed, instantaneous and complete wetting by bringing together conditioned powder and highly atomized liquid from two separate streams, incorporating particles of liquid with particles of powder. The reactive surface areas of both the powder and the liquid are maximized before intimate contact is actually made. The result is consistently uniform, superior wetting without the agglomeration or “clumping” usually associated with conventional mixing methods.

Semi-Bulk Systems can design and integrate the Vacucam® in-line system to feed finished slurry into multiple locations of your preference, such as storage or mix tanks. Your entire process can be physically separated and centrally controlled. Semi-Bulk Systems provides options such as mounting the Ejector-Mixer on your tanks or integrating our system with your existing process.

The best fluid ejector upgrade with improved efficiency over the traditional fluid mixer.

Since the Vacucam® system achieves high-speed, instantaneous and complete mixing, it makes it perfect for fluid mixing too. You can bring together highly atomized liquids from two separate streams for batch to batch consistency and uniform mixing.

Air-Cone® Hopper

The Air-Cone® Hopper’s ability to condition difficult powders makes it ideal for applications where dependable flow and total discharge are critical. Batch-to-batch variations due to material hold-back are virtually eliminated when it is used as a weigh hopper.

Since the conditioned powder is able to flow freely, the Air-Cone® Hopper is an excellent feed source for vacuum conveyors and for the VACUCAM® Ejector Mixer above.

Here’s how the system works

An inner membrane completely covers the surface where product comes into contact with the cone. Low pressure “conditioning” air or inert gas is distributed by an air supply manifold and diffused through the membrane wall. When the dry ingredients are conditioned, they assume the properties of a liquid and can then flow smoothly and accurately into your manufacturing process. This aeration process eliminates some of the typical production problems with difficult powders such as bridging and rat holes.

Total Dry Mix Automated Process

• Single In-Line process to deliver to selected mix tanks
• Separate dry room from wet area
• Bulk bag handling of major ingredients, paper bag handling of minor ingredients
• Multiple bulk bag hoppers for automated powder delivery of all dry ingredients

Dry Side Delivery

• Paper Bags
• Bulk Bags
• Bulk Truck
• Bulk Rail
• Bulk Silo