For an industrial "hot" scrubber design calculation in Excel, you need to structure your spreadsheet to handle gas cooling (quenching) mass transfer simultaneously
. High-temperature inlet gases require an initial saturation step to prevent damage to internal packing and to stabilize the absorption chemistry. Core Calculation Workflow
To design a functional packed bed scrubber for hot gases, follow these steps: Gas Saturation & Flow Correction
Calculate the "Saturated Gas Flow Rate." Hot gases shrink significantly when cooled by the scrubbing liquid. Use the ideal gas law and psychrometric data to find the adiabatic saturation temperature.
cap Q sub s a t end-sub equals cap Q sub i n end-sub center dot open paren the fraction with numerator cap T sub s a t end-sub and denominator cap T sub i n end-sub end-fraction close paren center dot open paren the fraction with numerator cap P sub i n end-sub and denominator cap P sub s a t end-sub end-fraction close paren (Corrected for moisture addition). Column Diameter Sizing Determine the column diameter based on superficial gas velocity ). For most vertical scrubbers, is kept between to avoid flooding while maintaining contact time. Calculation: Mass Transfer & Packing Height Calculate the Height of a Transfer Unit (HTU) Height Equivalent to a Theoretical Plate (HETP) . For hot acid gases (like cap H cap C l
), Norton’s correlation or empirical mass transfer coefficients ( cap K sub cap G a end-sub
) are commonly used to find the required packing depth for your target removal efficiency. Standard Target: removal efficiency. Hydraulic Performance (Pressure Drop)
Calculate the pressure drop across the packing to size your fan. High-temperature applications often have higher liquid-to-gas ( ) ratios, which increases the pressure drop. Typical Limit: Design for of the flooding velocity. Excel Spreadsheet Structure
Scrubber Design Calculation: A Step-by-Step Guide
A scrubber is a crucial piece of equipment in various industrial processes, used to remove pollutants and contaminants from gas streams. Designing a scrubber requires careful consideration of several factors, including gas flow rate, pollutant concentration, and scrubbing liquid properties. In this story, we'll walk through a step-by-step guide on how to perform scrubber design calculations using Excel.
The Problem
A chemical plant is looking to install a scrubber to remove sulfur dioxide (SO2) from its flue gas stream. The plant's engineers need to design a scrubber that can handle a gas flow rate of 10,000 Nm³/h, with an SO2 concentration of 500 ppm. The scrubbing liquid will be a solution of sodium hydroxide (NaOH).
Step 1: Define the Design Parameters
| Parameter | Value | Unit | | --- | --- | --- | | Gas flow rate (Q) | 10,000 | Nm³/h | | SO2 concentration (C) | 500 | ppm | | Scrubbing liquid | NaOH solution | - | | Temperature (T) | 25 | °C | | Pressure (P) | 1 | atm |
Step 2: Calculate the Molar Flow Rate of SO2
To calculate the molar flow rate of SO2, we need to convert the volumetric flow rate from Nm³/h to mol/h.
$$ \textMolar flow rate of SO2 = Q \times C \times \frac110^6 \times \fracPR \times T $$
where R is the gas constant (8.314 J/mol·K).
Assuming ideal gas behavior, we can simplify the calculation:
$$ \textMolar flow rate of SO2 = 10,000 \times 500 \times \frac110^6 \times \frac122.4 = 223.2 , \textmol/h $$
Step 3: Determine the Scrubber Type and Size
Based on the molar flow rate of SO2, we can select a suitable scrubber type and size. For this example, let's assume a packed tower scrubber with a packed height of 5 meters.
Step 4: Calculate the Liquid Flow Rate
The liquid flow rate (L) can be calculated using the following equation: scrubber design calculation excel hot
$$ L = \frac\textMolar flow rate of SO2 \times \textStoichiometric ratio\textMolecular weight of NaOH \times \textDensity of NaOH solution $$
Assuming a stoichiometric ratio of 1.5 and a NaOH solution density of 1,000 kg/m³:
$$ L = \frac223.2 \times 1.540 \times 1000 = 8.37 , \textm³/h $$
Step 5: Calculate the Scrubber Diameter
The scrubber diameter (D) can be calculated using the following equation:
$$ D = \sqrt\frac4 \times Q\pi \times v $$
where v is the superficial gas velocity ( typically 1-3 m/s).
Assuming a superficial gas velocity of 2 m/s:
$$ D = \sqrt\frac4 \times 10,0003600 \times \pi \times 2 = 1.33 , \textm $$
Excel Calculation
We can now create an Excel spreadsheet to perform these calculations.
| Parameter | Value | Formula |
| --- | --- | --- |
| Gas flow rate (Q) | 10,000 | - |
| SO2 concentration (C) | 500 | - |
| Molar flow rate of SO2 | 223.2 | =Q*C/10^6*1/22.4 |
| Liquid flow rate (L) | 8.37 | =223.2*1.5/40/1000 |
| Scrubber diameter (D) | 1.33 | =SQRT(4*10000/3600/PI()/2) |
By following these steps and using Excel to perform the calculations, we can quickly and accurately design a scrubber system that meets the plant's requirements.
Conclusion
In this story, we walked through a step-by-step guide on how to perform scrubber design calculations using Excel. By defining the design parameters, calculating the molar flow rate of SO2, determining the scrubber type and size, calculating the liquid flow rate, and calculating the scrubber diameter, we can design a scrubber system that effectively removes pollutants from gas streams.
Designing a scrubber for hot gas streams requires calculating the column diameter, height, and cooling capacity to ensure efficient pollutant removal . Excel-based design tools typically focus on mass transfer pressure drop correlations to determine these dimensions. assets-global.website-files.com Key Design Parameters for Hot Gas Scrubbers Gas Inlet Conditions : You must input the initial temperature (e.g., 400 raised to the composed with power cap F 70 raised to the composed with power cap C ) and flow rate to account for gas expansion. Humidification & Cooling
: Scrubbers reduce gas temperature to saturation conditions (e.g., down to 59 raised to the composed with power cap C ) while increasing relative humidity. Column Diameter
: Calculated based on the gas mass flow rate and a target "percentage of flooding" (typically 50–85%) to avoid liquid backup. Height of Packing (HETP) : Determined using correlations like Norton’s to ensure enough contact time for chemical absorption. Pressure Drop ( cap delta cap P
: Essential for sizing the fan or blower motor; usually calculated for both irrigated and dry packing. assets-global.website-files.com Scrubber Design Excel Resources
The following platforms provide templates and detailed spreadsheets for scrubber sizing: Wet Scrubber Design Excel Sheet | PDF - Scribd
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 For an industrial "hot" scrubber design calculation in
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
): 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
Title: Scrubber Design Calculation in Excel: The Hot, Handy Template You Need
Meta Description: Stop guessing the L/G ratio. Here is a step-by-step guide to building a hot (high-temperature) packed bed scrubber design sheet in Excel, including flooding velocity, pressure drop, and makeup water.
GasFlow, TempIn, L_G_ratio).If you want, I can also provide the Excel formulas (e.g., for adiabatic saturation, pressure drop, or d50) so you can implement them directly into cells. Just let me know which module you'd like to start with.
Designing a wet scrubber for high-temperature ("hot") gas streams requires balancing pollutant removal efficiency with heat recovery and structural integrity
. Using Excel allows for iterative modeling of these complex thermal and chemical interactions. www.mchip.net Core Design Parameters
A proper design calculation must start with these foundational inputs: Gas Characteristics : Volumetric flow rate ( cap Q sub g ), inlet temperature ( cap T sub i n end-sub ), moisture content, and pollutant concentration (e.g., cap H sub 2 cap S cap S cap O sub 2 , or particulate matter). Removal Requirements : Desired outlet concentration ( cap C sub o u t end-sub ) and overall absorption efficiency ( Saturation State : For hot gases, calculating the saturation temperature ( cap T sub s a t end-sub
) and saturated volume is critical for sizing the shell diameter. www.mchip.net Step-by-Step Calculation Logic in Excel Gas Volume Correction
: Hot gas volume must be corrected to saturated conditions. For example, a 10,000 ACFM stream at 450°F may reduce to 7,500 ACFM upon saturation. Tower Sizing
: Determine based on the allowable gas velocity through the shell (typically 1–2 m/s or 500 ft/min).
: Calculated using the Height of a Transfer Unit (HETP) and the required Number of Transfer Units (NTU) based on absorption kinetics. Liquid-to-Gas (L/G) Ratio
: This ratio (typically 0.1 to 10) determines the volume of scrubbing liquid needed to handle the pollutant load and provide necessary cooling. Pressure Drop ( cap delta cap P : Use correlations like Norton’s Darcy-Weisbach
equation to ensure the system operates within fan/blower limits. : For hot gases, calculate the energy balance ( Title: Scrubber Design Calculation in Excel: The Hot,
) to determine the cooling load or potential for heat recovery. www.mchip.net Excel Implementation Resources
For a professional starting point, utilize these established templates: EPA Cost & Design Spreadsheets US EPA Cost Calculation Spreadsheets
provide detailed tabs for Packed Bed and Wet Flue Gas Desulfurization (WFGD) parameters. Spray Tower Calculators : Marco Meloni offers a specialized Spray Tower Excel Sheet that covers removal efficiency and pressure losses. General Wet Scrubber Sheets
: Detailed sizing guides for diameter, plate thickness, and packing selection can be found on platforms like H2s Scrubber Design Calculation - MCHIP
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:
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.
For hot gases, viscosity (μ) increases, which changes collection efficiency.
η = 1 – exp[- (ψ * Q_l) / (Q_g * μ)]
Where ψ is the inertial impaction parameter.
μ via Sutherland’s formula for air or steam.The L/G ratio determines the number of scrubbing droplets.
Before building your Excel spreadsheet, you must understand the core engineering equations. A professional design consists of five interconnected modules.
Instead of manually typing packing factors, create a "Database" tab listing common packing types (e.g., 2" Pall Rings, 3" Saddles) and their associated Packing Factors ($F$), Surface Areas ($a$), and Void Fractions ($\epsilon$).