一、Overview

As environmental awareness grows and national regulations become increasingly stringent, industrial emissions control has become a critical component of sustainable corporate development. In large laundry detergent manufacturing plants, the spray drying tower granulation process generates significant amounts of moisture-laden flue gas containing fragrance compounds, which can negatively impact the surrounding environment. However, traditional air pollution control methods often fail to effectively address the challenges of flue gas de-whitening, vapor plume abatement, and odor removal in spray drying towers. This makes the development of efficient, cost-effective, and environmentally friendly treatment technologies an urgent priority.

 

This article provides an in-depth analysis of the challenges associated with flue gas treatment in spray drying towers within large-scale laundry detergent plants. It explores feasible air purification solutions, compares different treatment technologies, and ultimately recommends the most effective approach. The goal is to provide scientific decision-making support for laundry detergent manufacturers and contribute to green industry development.

二、Analysis of Challenges in Flue Gas Treatment

he flue gas emitted from spray drying towers presents significant treatment challenges due to its high moisture content and the presence of fragrance-laden compounds. During the spray drying granulation process, molten raw materials are atomized inside the tower to form granules, producing a substantial amount of water vapor, which leads to high-humidity emissions. Additionally, some raw material components and additives are carried into the exhaust stream, contributing to high concentrations of particulate pollutants. These moisture-rich and particle-laden emissions pose considerable difficulties for dust removal and odor elimination processes.

 

Typically, the treatment of flue gas from spray drying towers involves an initial pre-treatment stage to remove large particulate matter and reduce moisture content before the gas enters the main filtration system for advanced dust removal. However, since the emissions contain fragrance compounds and other volatile organic substances (VOCs), conventional dust removal systems alone are insufficient for effective odor control. Therefore, integrating specialized odor removal technologies is essential to achieving optimal flue gas treatment performance.

2.1 Reasons for Low Efficiency of Conventional Electrostatic Demisters

The high moisture content in spray drying tower flue gas significantly reduces the efficiency of conventional electrostatic demisters. The primary challenges include:

• Difficulty in Maintaining High-Voltage Electrostatic Fields: Increased moisture content enhances the conductivity of the flue gas, making it difficult to sustain a stable high-voltage electrostatic field. As a result, the secondary voltage fails to rise or may not even initiate, severely compromising demisting performance.

• Dust Adhering to Electrodes: In high-humidity conditions, dust particles absorb moisture and become sticky, making them more prone to accumulating on electrode plates. This leads to scaling and fouling on the electrodes, reducing dust removal efficiency over time.

2.2 Reasons Why Baghouse Filters Are Unsuitable

Although baghouse filters offer high dust collection efficiency, they are not suitable for treating flue gas from spray drying towers due to the following limitations:

• Bag Filter Blockage: The high humidity in the flue gas causes dust particles to become damp and agglomerate, resulting in severe clogging of the filter bags. This leads to increased system resistance and potential operational failure.

• Corrosion of Filter Bags: Some fragrance compounds and volatile organic substances (VOCs) in the emissions exhibit chemical reactivity, which can gradually degrade the filter material, significantly reducing its lifespan.

2.3 High Operating Costs of RTO Combustion for Odor Removal

The Regenerative Thermal Oxidizer (RTO) combustion method is a highly effective odor removal technology. However, applying it to spray drying tower flue gas treatment results in extremely high operating costs due to the following reasons:

• Increased Energy Consumption Due to High Moisture Content: The flue gas contains a large amount of water vapor, requiring significant energy input to evaporate the moisture, which substantially increases the energy consumption of RTO operation.

• Low Combustibility: The high water vapor content in spray drying tower flue gas reduces its combustibility, making it less efficient for thermal oxidation.

• Gas Pipeline Installation Increases Enterprise Risks: The RTO system relies on natural gas or other fuel sources, necessitating the installation of gas pipelines, which raises safety risks and increases capital investment costs for enterprises.

• High Natural Gas and Maintenance Costs: RTO systems require a continuous supply of natural gas, which is expensive and drives up operational costs. Additionally, RTO equipment maintenance is costly, requiring regular replacement of heat storage media and other components.

三、Noah Plasma Treatment Process

Noah Electric specializes in the research, development, and production of high-voltage, high-frequency plasma pulse power supplies. Its core technology is the self-developed plasma power supply, which is designed for environmental applications. This advanced power supply can be applied to various industrial waste gas treatment processes, effectively removing dust, mist droplets, and odors from emissions.

3.1 Noah Plasma Treatment Technology

Noah Electric focuses on the development of high-voltage, high-frequency plasma pulse power supplies, with its core technology being a proprietary plasma power system. Designed for environmental applications, this technology is applicable to a wide range of waste gas treatment processes, efficiently removing particulates, mist, and odors from industrial emissions.

Noah Plasma Power technology has achieved breakthroughs in two key areas:

• Pulse Square Wave Output: The Noah Plasma Power Supply achieves direct current pulse square wave output at an 80kHz operating frequency, rather than the conventional spike output. This output mode stabilizes plasma generation, enhances energy efficiency, and improves waste gas treatment performance.

• Complete Townsend Discharge Curve: The discharge waveform of the Noah Plasma Power Supply meets the requirements for a complete Townsend discharge curve with no relaxation state. The Townsend discharge curve is considered a key indicator for achieving a standard plasma state. This ensures the production of high-quality plasma, which significantly enhances pollutant decomposition efficiency.

3.2 Noah Plasma Exhaust Gas Treatment Process

The Noah Plasma Exhaust Gas Treatment Process consists of the following key steps:

1. Exhaust Gas Pretreatment: The flue gas first passes through a cyclone separator, which efficiently removes large particulate matter. The collected dust is recyclable, helping reduce operational costs.

2. Flue Gas Cooling: The flue gas is cooled to a temperature below the local atmospheric dew point, enhancing the efficiency of the subsequent demister and optimizing overall gas treatment performance.

3. Advanced Dust Removal: The WPRP Electrostatic Precipitator (ESP), powered by Noah’s proprietary high-voltage pulse power supply, ensures thorough dust filtration. Designed to operate in high-humidity flue gas conditions, it achieves an outlet dust concentration as low as 1 mg/m³, meeting ultra-low emission standards.

4. Odor Elimination: The DRE Odor Control System significantly reduces unwanted odors in flue gas, achieving an odor intensity reduction of 50-80%, effectively eliminating residual organic compounds.

5. Final Emission: After undergoing the above treatment stages, the purified exhaust gas is released through an industrial exhaust stack, fully compliant with environmental regulations.

3.3 Advantages of Noah Plasma Power Supply

• Beyond its two major technological breakthroughs, the Noah Plasma Power Supply offers several distinct advantages:

• High-Frequency High-Voltage Technology: Utilizing advanced high-voltage and high-frequency technology, it generates high-energy-density plasma, significantly improving exhaust gas treatment efficiency.

• Ultra-Fast Voltage and Current Response: Compared to conventional hybrid or superimposed pulse power supplies, the Noah Plasma Power Supply delivers higher instantaneous voltage and current, with an ultra-fast rise time of just 372ns from 0V to peak voltage. This results in a higher plasma energy density, leading to more efficient pollutant breakdown and degradation.

• Superior Adaptability: Engineered for high-humidity and dust-laden environments, the Noah Plasma Power Supply ensures stable and reliable operation even under extreme industrial conditions.

• Energy-Efficient: With its low power consumption, it helps reduce operational costs, making it a cost-effective solution for enterprises.

• Zero Consumables, Zero Secondary Contamination: Unlike traditional odor control technologies, the Noah Plasma Power Supply operates without consumables, eliminating the risk of secondary contamination and ensuring an environmentally friendly solution.

四、Advantages of Noah’s Process

For exhaust gas generated by the tower granulation process, Noah’s environmental technology provides three key advantages:

4.1 High De-White Efficiency

• De-White Emission Standard: After passing through Noah’s equipment, the particulate concentration is reduced to less than 5 mg/m³, making the visible white smoke disappear to the naked eye (at temperatures above 15°C and relative humidity below 75%).

• Unique Technical Advantage: Equipped with a new-generation pulse high-voltage power supply, which provides pulsed energy output instead of continuous output, ensuring that the DRE system operates stably in high-humidity flue gas environments without sparking.

• Operational Characteristics: Under high-temperature flue gas conditions, the Noah DRE system remains spark-free, maintains a stable and high secondary voltage, and achieves high de-misting efficiency.

• Process Comparison Value: Traditional constant-current power supplies (either industrial-frequency or high-frequency types) struggle in high-humidity flue gas environments, leading to frequent sparking, low secondary voltage, and poor de-misting efficiency, making white smoke removal ineffective.

4.2 Superior Particulate Removal Efficiency

• Particulate Matter Contributes to White Smoke Formation In high-humidity exhaust gas, fine particulate matter serves as condensation nuclei, enhancing white smoke visibility under identical conditions. With Noah’s advanced dust removal system, the outlet particulate concentration is reduced to <1 mg/m³, significantly improving white smoke elimination efficiency.

• Verified Ultra-Low Particulate Emissions Over a 45-day test period, nine independent measurements confirmed that the mean particulate concentration remained below 1 mg/m³, which is below the measurable detection threshold, ensuring minimal emissions and enhanced air quality compliance.

• Integrated Dust and Mist Control is Essential Pre-treated high-humidity exhaust gas contains water mist, acid mist, and submicron heterogeneous solid-liquid aerosols, which are highly unstable. Conventional air purification systems often fail to efficiently extract these pollutants, leading to persistent visible white smoke emissions.

4.3 Low Operating Costs

• Operational Cost Structure of Tower Granulation Exhaust Treatment Systems The operating costs of a tower granulation exhaust treatment system consist of two primary components: white smoke removal operational costs and odor and fragrance neutralization costs.

• Cost Reduction in the White Smoke Removal Stage Unlike conventional de-white methods that rely on cooling followed by reheating, the Noah treatment system bypasses condensation requirements, resulting in significant cost savings.

• Cost Efficiency in the Odor Removal Stage The Noah treatment system utilizes an advanced non-combustion odor control technology, reducing operational costs by over 80% compared to traditional thermal incineration methods. The Noah DRE system requires minimal pretreatment, operates without natural gas or chemical additives, and maintains minimal pressure drop, further lowering energy consumption and overall costs.

• Market Potential and Industry Advantages While white smoke is often perceived as harmless water vapor, odor-laden or acidic white smoke is unacceptable in industrial applications. Conventional treatment technologies offer limited effectiveness and come with high operating expenses. In contrast, the Noah plasma treatment process provides high-efficiency white smoke and odor elimination with low operational costs, positioning it as an energy-efficient and scalable solution for the industrial exhaust treatment market.

五、Case Study: Laundry Detergent Factory

5.1、Introduction to Liby

Company Overview

Guangzhou Liby Enterprise Group Co., Ltd. (Liby Group) is a leading household chemical brand in China, recognized as a pioneer in the industry. Founded in 1994 and headquartered in Guangzhou, Liby has transformed over the past three decades from an OEM supplier of laundry detergents into a market leader with annual revenue surpassing 20 billion RMB.

Today, Liby Group operates 30 subsidiaries and branch offices, 9 advanced production facilities, and an extensive supply chain network, including over 600 suppliers, 1,000 distributors, and 1.2 million retail touchpoints across China.

Manufacturing Facilities and Production Bases

Liby Group operates nine advanced production bases across China, including:

• Guangzhou Liby (Panyu) Co., Ltd.

• Liby Household Chemicals Co., Ltd. (Nansha, Guangzhou)

• Ma’anshan Liby Household Chemicals Co., Ltd.

• Xinxiang Liby Industrial Co., Ltd.

• Siping Liby Household Chemicals Co., Ltd., among others.

These state-of-the-art manufacturing facilities are equipped with cutting-edge production technology, adhere to strict quality and environmental management standards, and implement low-emission industrial practices. Each facility is designed to minimize industrial emissions (air, water, and solid waste) while promoting sustainable, eco-friendly, and circular manufacturing.

As environmentally conscious production hubs, Liby’s factories feature green spaces, operate in dust-free and noise-controlled environments, and incorporate advanced water recycling systems. Notably, the Guangzhou Panyu production base has been officially recognized by government authorities as a "Guangdong Provincial Environmental Protection Demonstration Project."

Technology and Research & Development

Liby Group places great emphasis on technological innovation and R&D, maintaining a strong commitment to scientific advancement. The company has been recognized with four "China Famous Brand" products, holds two national-level "High-Tech Enterprise" certifications, and operates both a postdoctoral research workstation and an academician enterprise workstation.

In addition to its in-house research, Liby Group actively engages in global collaborations, forming strategic partnerships with Fortune Global 500 companies such as Germany’s BASF, Dow Chemical (USA), and DuPont (USA). The company also cooperates closely with leading domestic research institutions, including the China Research Institute of Daily Chemical Industry and Sun Yat-sen University, continuously enhancing its technological capabilities and independent innovation.

Through these efforts, Liby drives product optimization, corporate transformation, and sustainable growth. In November 2024, the Guangdong Provincial Light Industry Association evaluated Liby’s R&D project—"Key Technologies and Applications of Green and Low-Carbon Dishwashing Detergents"—as having reached an internationally advanced level.

 

Industry Leadership

Liby Group is a key contributor to China’s laundry and cleaning product standards and ranks as the No.1 detergent brand in China and the fourth-largest globally.

According to internationally recognized market research firm Nielsen, Liby laundry detergent holds the No.1 sales position in China, capturing 25% of the national market share—meaning one out of every four packs of detergent sold in China is from Liby. Similarly, Liby dishwashing liquid has maintained its No.1 national sales position for consecutive years, commanding 40% of the market—which means that one in every 2.5 bottles of dishwashing liquid sold in China is a Liby product.

Over the years, Liby Group has consistently ranked among China’s Top 500 Enterprises, securing its place in the 2024 China Top 500 Manufacturing Enterprises, China’s Top 500 Private Enterprises, and the China Top 500 Private Manufacturing Enterprises.

5.2 Collaboration Between Noah and Liby

 

The high-voltage, high-frequency plasma power supply developed by Noah (80kV voltage, 80kHz frequency) has become the core technology in Liby Group’s environmental solutions, thanks to its industry-leading particulate capture capability.

During laundry detergent production, the tower granulation process generates a significant amount of exhaust gas containing dust, water vapor, and trace chemical substances (such as surfactant residues and alkaline particles). Traditional environmental treatment solutions rely on multi-stage filtration (including cyclone dust collectors and bag filters) combined with chemical adsorption equipment. However, these conventional methods require large installation space, high consumable costs, and excessive energy consumption.

Through its plasma-enhanced electric field technology, the Noah power supply creates a high-intensity ionization field within the exhaust pipeline, enabling direct dynamic adsorption of high-humidity (>90% relative humidity) and high-dust-concentration exhaust gases. This ensures that particulate emissions remain consistently below 5 mg/m³, far exceeding the national standard of 20 mg/m³.

Its core advantages include:

1. Superior Adaptability to High-Humidity Environments

   1. Incorporates a patented anti-flashover design, ensuring stable and continuous discharge in humid conditions.

   2. Completely eliminates short-circuit and sparking issues caused by condensation in traditional electrostatic precipitators.

2. Compact Modular Integration

   1. A single system replaces conventional multi-stage treatment processes, reducing land usage by 60%.

   2. Achieves a 40% reduction in overall energy consumption compared to traditional methods.

3. Zero-Consumable, Long-Term Operation

   1. No filter replacements required, significantly lowering maintenance and operational costs to near zero.

5.3 Liby’s Forward-Thinking Decision

Amid the industry’s environmental upgrade trends, Liby Group’s technical team proactively identified opportunities for technological innovation. In early 2023, engineers at Liby’s Panyu production base reached out to Noah, proposing a pilot project to integrate plasma power supply technology into the laundry detergent granulation workshop.

After three months of on-site testing, the system demonstrated over 99% removal efficiency, even under extreme operating conditions with peak dust concentrations reaching 200 mg/m³. Additionally, energy costs for operation were reduced to just one-third of the original system’s electricity consumption.

This success directly led to the signing of a strategic cooperation agreement in 2024. A Liby representative remarked:

"Noah’s solution not only meets environmental regulations but also transforms compliance costs into long-term financial benefits through lifecycle cost optimization. At the Panyu facility alone, annual savings on electricity, consumables, and maintenance exceed 20 million RMB, with an investment payback period of less than 1.5 years."

5.4 2024 Cooperation Achievements & Nationwide Expansion Plan

By the end of 2024, Noah’s plasma power system had been fully implemented at Liby Group’s Guangzhou Panyu production base.

As of 2025, the partnership has expanded to include Liby’s Xinxiang production base in Henan, with the project officially launching this year. Moving forward, Noah and Liby plan to extend this environmental technology upgrade across Liby’s remaining production facilities, ensuring a comprehensive green transformation for the entire group.