Laundry detergent powder production is a continuous solids-processing and thermal-processing system. The equipment configuration depends on formulation, plant capacity, target bulk density, moisture specification, and packaging format.
From an engineering perspective, a detergent powder plant converts raw materials such as surfactants, builders, alkalis, and additives into finished powder through dosing, slurry preparation, drying, blending, screening, conveying, and packaging.
Raw Material Storage and Dosing System
Laundry detergent powder uses both solid and liquid raw materials. The solids typically include:
sodium carbonate (Na₂CO₃)
sodium sulfate (Na₂SO₄)
zeolite 4A
sodium silicate powder
carboxymethyl cellulose (CMC)
sodium percarbonate
enzymes
optical brighteners
Liquid components commonly include:
linear alkylbenzene sulfonic acid (LABSA)
sodium silicate solution
nonionic surfactants
perfume
deionized water
Storage equipment is selected based on bulk density and flowability.
Powders with bulk density above 0.7 g/cm³ are commonly stored in steel silos equipped with fluidization pads or vibrators.
Hygroscopic additives such as sodium percarbonate are often stored in humidity-controlled rooms below 40–50% RH to prevent decomposition.
Dosing equipment typically includes:
screw feeders
rotary valves
loss-in-weight feeders
load cell hopper systems
metering pumps
Feeding accuracy for builders is usually controlled within ±0.5–1.0%. Enzyme dosing generally requires tighter control due to low dosage percentage.
Slurry Preparation System
The slurry preparation system converts powder and liquid ingredients into a pumpable detergent slurry before spray drying.
The main equipment includes:
slurry mixing tank
agitator
heating jacket or steam coil
inline homogenizer
circulation pump
Typical slurry solids concentration ranges from 55% to 70% depending on formulation.
LABSA neutralization often occurs inside the slurry tank using sodium hydroxide or sodium carbonate.
A common reaction:
LABSA + NaOH → Sodium alkylbenzene sulfonate + water
Tank operating temperatures are usually maintained between 60°C and 90°C depending on viscosity and surfactant loading.
Agitator design depends on viscosity. Anchor agitators or turbine impellers are commonly used.
Viscosity is monitored because slurry viscosity directly affects spray nozzle atomization.
Typical detergent slurry viscosity may range from several hundred to several thousand cP depending on solids loading.
High-Pressure Slurry Pump System
Before entering the spray drying tower, slurry is pressurized through high-pressure pumps.
Common pump types:
triplex plunger pump
piston pump
Operating pressure often ranges:
2 MPa
4 MPa
up to 8 MPa
Pressure selection depends on nozzle size and droplet size target.
Droplet diameter directly affects:
particle size distribution
powder moisture
powder density
Pump discharge lines usually include:
pressure transmitters
pulsation dampener
safety relief valve
inline filters
Filters upstream of atomization are required to prevent nozzle blockage.
Typical filtration:
80–200 mesh depending on nozzle design.
Spray Drying Tower
The spray drying tower is the main drying equipment in detergent powder manufacturing.
Its purpose is to atomize detergent slurry into fine droplets and evaporate moisture using heated air.
The system generally includes:
drying chamber
atomizing nozzles or rotary atomizer
hot air distributor
burner or steam air heater
exhaust duct
Spray drying tower height varies by capacity.
Examples:
10–15 meter tower for smaller output
20–35 meter tower for larger capacity
Hot air inlet temperature typically ranges:
250°C
300°C
up to 400°C
Outlet air temperature is normally controlled between:
90°C and 120°C
Target finished powder moisture:
2–8% depending on product grade.
Particle formation depends on:
slurry viscosity
atomization pressure
inlet air temperature
air residence time
Bulk density of spray-dried detergent powder commonly falls between:
300–550 g/L
The tower shell is typically carbon steel with internal insulation.
High-temperature zones often use stainless contact parts.
Powder Cooling and Air Handling System
Powder leaving the tower retains residual heat.
Typical powder discharge temperature may exceed 70°C.
Cooling equipment may include:
fluidized bed cooler
air cooling conveyor
vibrating fluid bed
Target final powder temperature before blending is generally below 40°C.
Cooling improves:
flowability
storage stability
enzyme survival
perfume retention
Air handling includes:
centrifugal fan
ductwork
cyclone separator
baghouse filter
Cyclones capture coarse powder particles.
Bag filters capture dust below cyclone cut size.
Dust concentration limits are normally controlled based on local environmental regulation.
Recovered fines may be returned to blending or slurry.
Post-Blending System
Many detergent ingredients cannot be exposed to spray tower temperature.
These are added after drying.
Common post-addition materials:
enzymes
perfume
sodium percarbonate
colored speckles
anti-caking agents
bleach activators
Equipment includes:
ribbon blender
plow mixer
paddle mixer
liquid spraying system
Blending time depends on formulation and mixer type.
Typical batch blending:
5–15 minutes
Liquid perfume dosing requires atomizing spray bars.
Uniformity is checked through sample testing.
Important production controls:
enzyme distribution
speckle distribution
moisture consistency
bulk density
Improper mixing affects detergent appearance and wash performance.
Screening and Conveying System
After blending, detergent powder passes through screening.
Equipment commonly includes:
vibrating screen
rotary sifter
mesh separator
Typical screening purpose:
remove oversize agglomerates
remove foreign particles
improve particle consistency
Mesh size depends on target powder granulation.
Oversized material may be milled and recycled.
Conveying systems include:
bucket elevator
screw conveyor
pneumatic conveyor
belt conveyor
Conveying velocity is controlled carefully because excessive impact breaks granules and changes bulk density.
Enzyme-containing powder usually requires low-impact conveying.
Packaging System
Finished detergent powder is packed according to retail or industrial format.
Common packaging sizes:
500 g
1 kg
2 kg
5 kg
10 kg
25 kg
Packaging equipment:
auger filler
open-mouth bagger
vertical form fill seal machine
weighing hopper
heat sealing unit
bag stitching machine
checkweigher
metal detector
Target filling accuracy is often:
±0.2–0.5%
Packaging material varies:
laminated PE bags
woven polypropylene sacks
carton box with liner
Powder compaction during filling is monitored because density changes affect bag appearance and net weight.
Dust Collection and Exhaust Air Treatment
Detergent powder production creates airborne fine particles.
Dust sources include:
powder transfer
tower exhaust
blender loading
bagging station
Collection equipment includes:
cyclone separator
pulse jet bag filter
wet scrubber (if required)
Bag filters typically use polyester or PTFE filter media.
Pressure drop across filter banks is monitored.
Collected dust may be recycled depending on formulation.
Fine detergent dust also affects explosion risk.
Grounding and dust concentration control are standard engineering requirements.
Automation System (PLC / DCS)
A detergent powder production line integrates both continuous and batch operations, which require centralized process coordination. The automation system is typically based on PLC or DCS architecture, depending on plant capacity and control complexity.
The control system is responsible for coordinating multiple process units, including:
raw material dosing and feeding accuracy
slurry preparation and mixing stability
neutralization reaction control for surfactant processing
high-pressure pump operation and safety regulation
spray drying burner control and combustion stability
drying air volume and airflow distribution
outlet powder moisture regulation through feedback monitoring
post-blending sequence control for additives
packaging line synchronization and filling speed adjustment
Each of these process sections operates under closed-loop control logic to maintain stable production conditions and reduce batch variation.
Instrumentation in the System
A typical detergent powder plant automation system integrates multiple types of industrial sensors and measurement devices:
load cell-based weighing systems for raw material batching
resistance temperature detectors (RTDs) and thermocouples for process temperature monitoring
pressure transmitters for slurry pump and spray drying system protection
electromagnetic flow meters for liquid dosing and slurry circulation measurement
humidity sensors installed in drying and post-processing zones
pH analyzers for neutralization control in slurry preparation
These instruments are connected through fieldbus networks such as Profibus, Modbus, or Ethernet-based industrial communication systems depending on system design.
Process Control Functions
The automation system maintains stable operating conditions across key process sections:
slurry preparation temperature is maintained within a controlled industrial range suitable for surfactant neutralization and viscosity stabilization
spray drying outlet temperature is continuously adjusted to maintain consistent moisture content in the final powder
airflow and exhaust gas balance is regulated to stabilize drying efficiency and particle formation behavior
These control functions are executed through PID-based loops integrated into PLC or DCS controllers.
Data Monitoring and Production Logging
The system continuously records process data to support production traceability and quality control. Logged parameters typically include:
batch formulation records and raw material consumption
slurry preparation time and mixing conditions
drying tower operating conditions (temperature, airflow, pressure)
final powder moisture and density indicators
packaging output volume and filling accuracy
This data is stored in a centralized historian system and can be used for production analysis, troubleshooting, and process optimization.
Safety Interlock System
The automation system also includes hardware and software interlock functions to protect equipment and ensure safe operation. Typical protection logic includes:
automatic shutdown of spray drying burner in case of abnormal temperature rise or flame failure
pump shutdown under overpressure conditions in slurry feed lines
alarm and isolation response when bag filter differential pressure exceeds design limits
motor protection for overload, phase loss, or abnormal vibration conditions
These interlocks are implemented at both PLC level and independent safety relay level depending on plant safety requirements.
