The hum of the plant was usually a comfort to Elias, but today, the caustic scrubber
was screaming. Not literally, of course—though the high-pressure alarm on the control panel was doing a fine job of that.
The inlet gas temperature from the kiln had spiked, and the old design parameters were failing. If the liquid-to-gas ratio stayed this off-balance, the stack would start "yellow-smoking," and the EPA would be at the gates by noon.
Elias ducked into the site office, his boots clacking on the linoleum. He pulled up his master file: Scrubber_Design_Final_v4_HOT.xlsx
"Talk to me," he muttered, fingers flying across the mechanical keyboard. He didn't just need a fix; he needed a recalculation for adiabatic saturation
. As the hot gas hit the recirculating liquor, it would evaporate water instantly, cooling the gas but shrinking its volume and changing the density. The Inputs:
He punched in the new 450°F inlet temp and the soaring flow rate. The Magic:
The spreadsheet’s hidden VLOOKUPs pulled the physical properties of the gas. The NTU (Number of Transfer Units) cells turned a cautionary orange. The Solve:
He adjusted the packing depth from 10 feet to 14. The pressure drop calculation—the heart of the sheet—recalculated.
With a final tweak to the pump frequency on the screen, he watched the "Flood Point %" drop from a dangerous 92% to a stable 70%. He hit 'Save,' exported the setpoints, and ran back to the floor.
Ten minutes later, the alarm fell silent. The plume at the top of the stack turned from a ghost of a haze to invisible, clean air. Elias leaned against the steel railing, the heat of the tower radiating against his back, and smiled.
The math held. The Excel sheet, messy as it was, had saved the day. pressure drop across the packing for your own design?
The design of a wet scrubber—whether for particulate removal or gas absorption—requires a systematic calculation process to determine critical dimensions and operational parameters. Utilizing a structured Excel spreadsheet
allows engineers to quickly iterate through design variables like gas flow rates, temperature, and pressure drops to find an optimal configuration. 1. Define Design Inputs and Gas Conditions scrubber design calculation excel hot
The first step is establishing the "source" data. In an Excel sheet, these are typically grouped in a dedicated "Inputs" tab. Gas Stream Properties : Include the inlet volumetric flow rate (e.g., in ), inlet temperature, and pressure. Saturation Calculations
: For hot gases, the scrubber will saturate the stream. You must calculate the saturated gas flow rate cap Q sub s a t end-sub ) and temperature ( cap T sub s a t end-sub
) using a psychrometric chart or humidity ratios. The scrubber is sized based on this saturated outlet volume, not the hot inlet volume. Target Efficiency : Define the required collection efficiency (e.g., for particulates) based on regulatory standards. 2. Determine Column Diameter The column diameter ( ) is primarily a function of the gas velocity required to avoid flooding while maintaining contact time. Calculation
: Divide the saturated volumetric flow rate by the allowable shell velocity (typically around for spray towers). Cross-Sectional Area ( cap A sub s
cap A sub s equals the fraction with numerator cap Q sub s a t end-sub and denominator v end-fraction Diameter (
cap D equals the square root of the fraction with numerator 4 cross cap A sub s and denominator pi end-fraction end-root Hydraulic Check : For packed towers, the Excel sheet should check the % Flooding (typically designed for
) using correlations like Norton’s to ensure the gas can move through the packing without pushing the liquid back up. 3. Calculate Tower Height and Packing
The height ensures sufficient contact time between the gas and the scrubbing liquid. Wet scrubber design calculation xls
The first step is to establish the properties of the incoming hot gas. Because the gas is "hot," you must account for its actual volume at operating temperature rather than standard conditions. Gas Flow Rate ( Vincap V sub i n end-sub ): Define in ACFM (Actual Cubic Feet per Minute) or Inlet Temperature ( Tincap T sub i n end-sub ): Note the temperature (e.g., 400∘F400 raised to the composed with power cap F 590∘C590 raised to the composed with power cap C
Contaminant Data: Identify the molecular weight and concentration (ppm or ) of the component to be removed (e.g., HCl, H2Scap H sub 2 cap S Gas Properties: Calculate gas density ( ρgrho sub g
) at inlet temperature and pressure using the Ideal Gas Law. 2. Perform Humidification and Saturation Calculations
Hot gases will evaporate the scrubbing liquid until they reach the adiabatic saturation temperature ( Tsatcap T sub s a t end-sub
). The scrubber must be sized for the saturated gas volume, not the inlet volume. Determine Saturation Temperature ( Tsatcap T sub s a t end-sub The hum of the plant was usually a
): Use a psychrometric chart or humidity balance to find the temperature at which the gas becomes saturated with moisture. Calculate Saturated Gas Flow ( Qsatcap Q sub s a t end-sub ):
Qsat=Qin×Volume Correction Factorcap Q sub s a t end-sub equals cap Q sub i n end-sub cross Volume Correction Factor For example, a gas at 450∘F450 raised to the composed with power cap F might have a correction factor of 3. Determine Column Diameter
The tower diameter is typically calculated to avoid "flooding," where upward gas velocity prevents downward liquid flow.
Select Packing Material: Choose a packing type (e.g., Intalox Saddles, Rosette) and its specific Packing Factor ( Fpcap F sub p ).
Calculate Flooding Velocity: Use the Generalized Pressure Drop Correlation (GPDC). Aim for an operating velocity between of the flooding velocity. Find Cross-Sectional Area ( Ascap A sub s ):
As=Qsatvgascap A sub s equals the fraction with numerator cap Q sub s a t end-sub and denominator v sub g a s end-sub end-fraction vgasv sub g a s end-sub is the selected design gas velocity (e.g., Final Diameter ( ):
D=4×Asπcap D equals the square root of the fraction with numerator 4 cross cap A sub s and denominator pi end-fraction end-root 4. Determine Packing Height
The required height depends on the mass transfer efficiency needed to meet outlet concentration targets.
HCL Packed Column Scrubber Design | PDF | Mole (Unit) - Scribd
Introduction
A scrubber is a type of air pollution control device that uses a liquid to remove contaminants and pollutants from a gas stream. The design of a scrubber involves several key calculations to ensure that it can effectively remove pollutants and meet emissions standards. In this write-up, we will discuss how to perform scrubber design calculations using Excel.
Scrubber Design Calculations
The design of a scrubber involves several key calculations, including: Gas Flow Rate Calculation : The gas flow
Excel Calculation Template
To perform scrubber design calculations in Excel, we can create a calculation template that includes the following inputs:
The template can then be used to calculate the following outputs:
Step-by-Step Calculation Procedure
Here is a step-by-step procedure for performing scrubber design calculations in Excel:
Example Calculation
Here is an example calculation for a scrubber design using Excel:
Using the calculation template and step-by-step procedure, we can calculate the following outputs:
Conclusion
Scrubber design calculations can be performed using Excel to ensure that a scrubber can effectively remove pollutants and meet emissions standards. By following a step-by-step calculation procedure and using a calculation template, engineers can quickly and accurately design scrubbers for a variety of applications.
Pressure drop is critical for fan sizing and operating cost. This module includes:
Live flag: “ΔP > 15 kPa? → Check fan power limit”
Venturi scrubbers are preferred for hot gas applications due to their robust construction, lack of moving parts, and ability to handle high-temperature, high-humidity streams. The design challenge lies in balancing the gas velocity and liquid injection rate to maximize particle impaction while minimizing energy consumption (pressure drop).
Scope of Calculation:
You can download generic calculators, but here is how to build the professional-grade version that stands out.