High-activity calcium-based desulfurizing agent

Active, high-specific-surface-area calcium hydroxide desulfurization (powder) technology carries out desulfurization absorption and product treatment in a dry state. This method offers advantages such as no wastewater or waste acid discharge, reduced equipment corrosion, no significant cooling of flue gas during purification, high flue gas temperature after purification, favorable for chimney exhaust diffusion, and less secondary pollution. It is suitable for flue gas desulfurization technology in industries such as steel, coking, cement, glass, and ceramics.

Part 1: Flue Gas Desulfurization Technology Introduction

In recent years, dry desulfurization technology for flue gas has seen increasing application in small and medium-sized flue gas desulfurization systems, with mature technology and stable operation. The SDS desulfurization process route using sodium bicarbonate as the alkali source has rapidly expanded its market share due to its high desulfurization efficiency, wide availability of desulfurizing agents, and low difficulty in project implementation.

As the number of equipment increases, the drawbacks of this technological route begin to show, and how to deal with desulfurization ash has become a new environmental challenge. Sodium-based desulfurization ash is a mixture of sodium sulfate, sodium sulfite, and sodium carbonate..The substance has excellent water solubility and falls under the category of general solid waste that is difficult to dispose of in compliance with regulations. According to authoritative statistics, the coking industry alone produces up to 300,000 tons of sodium-based desulfurization ash annually. This figure is further increased by the power boilers, hot air furnaces, and heating furnaces of steel enterprises, as well as glass and cement kilns. Some companies rent land to build storage warehouses for storage, while others sell it to qualified institutions for disposal, with costs varying from 300 to 500 yuan per ton, thereby increasing the burden on businesses.

As of September 1, 2020, the new "Environmental Protection Law of the People's Republic of China on Solid Waste Pollution" took effect, introducing new responsibilities for enterprises generating solid waste and imposing severe penalties on illegal acts. The pressure on businesses has surged!

Tianjin Huaneng Langtian Environmental Protection Equipment Co., Ltd. After four years of dedicated research and development, with the efforts of our technical staff, we have successfully developed high-specific surface area calcium hydroxide with a specific surface area (BET) exceeding 45m2/g. Through independently developed core equipment, we have created a new production process, achieving large-scale production. Our Tianjin production base boasts a 100,000-ton production capacity with excellent product performance!

With the HNPS desulfurization system developed by our company, more than 30 sets have been industrially applied with excellent operational data, low cost, and satisfied customers. Currently, it has successfully been applied for ultra-low emission desulfurization in coking furnace push-ash ground stations, dry-cooling coke dust removal, coking furnace flue gas, steelmaking heating furnaces, hot blast stoves, power plant boilers, and waste incineration industrial furnaces.

High-activity, high-specific-surface-area calcium hydroxide - microscopic crystal structure under electron microscopy

Section 3: High-activity, high-specific-surface-area calcium hydroxide desulfurizing agent specifications

Section 4: High-activity, high-specific surface area calcium hydroxide - Recommended usage conditions

Section 5: High-activity, High-Surface Area Calcium Hydroxide Characteristics

Highly active and high specific surface area calcium hydroxide boasts features such as porosity, high activity, good dispersion, and high utilization rates. Its specific surface area is 3-4 times that of ordinary calcium hydroxide and is widely recognized as an excellent dry desulfurization product internationally. The practical dry desulfurization agents mainly include high specific surface area calcium hydroxide and baking soda. While baking soda has a fast reaction rate, it is relatively expensive and difficult to dispose of solid waste. By the 1980s, high specific surface area calcium hydroxide had been widely used in waste-to-energy and thermal power plants for desulfurization in Europe, America, and Japan, successfully replacing baking soda. High specific surface area calcium hydroxide has well-developed pores, allowing for rapid adsorption and absorption reactions of HCl and SO2 in flue gas, achieving a utilization rate of over 85%.

Section 6: Introduction to HNPS Dry Desulfurization Process

Highly active, high surface area calcium hydroxide dry powder desulfurizer, directly jetted into the flue gas duct through air conveyance. Under the action of the high-efficiency jetting unit, the calcium hydroxide powder quickly disperses into the flue gas, adsorbs and absorbs most of the acidic media such as F-, Cl-, SO2, and SO3 in the flue gas, and enters the bag filter with the flue gas. A small portion of the acidic media continues to react in the bag filter, and the flue gas after desulfurization is directly discharged through the induced draft fan.

This process is unaffected by the temperature of the smoke, and can effectively react above room temperature.

Section 7: Characteristics of High-activity, High-Surface-Area Calcium Hydroxide Desulfurization System

1. Storage System: Equipped with large-capacity powder storage silos, radar and anti-rotation level sensors, safety valves, vibration motors, arch-breaking aid flow air discs, and other accessories.

2. Feeding System: Utilizes a high-precision rotary feeder, measured through frequency conversion by sensors.

3. Power System: Positive pressure conveying with Roots blower or compressed air, one in operation and one in reserve.

4. Control System: Centralized control in the control room, with computer screens displaying main operating states or parameters such as material level and feeder operation frequency. The system is equipped with high and low material level alarms, material level display, status of the Roots blower, and fault alarms.

Section 8: Characteristics of Dry Desulfurization with High-activity, High-Surface-Area Calcium Hydroxide

1. Meets ultra-low emission requirements with high desulfurization efficiency; export SO2 concentration can reach near-zero emission levels; flue gas SO2 concentration between 40~300 mg/Nm3, particularly cost-effective.

2. Wide temperature range, utilizing flue gas treatment from 30-350°C, with high desulfurization efficiency.

3. The process is simple, utilizing an efficient jet to directly spray ultra-fine powder into the flue, completing the absorption reaction as the flue gas flows.

4. Ensure low dust emissions in the system with either the reuse or addition of bag dust collectors.

5. By-products are general solid waste, specifically saturated waste desulfurizer, mainly consisting of CaSO4, Ca(OH)2, and CaCO3.

6. Centralized control room operation without increasing personnel; small equipment footprint, especially suitable for low-temperature, low-sulfur environments.

7. Substitute the baking soda process with the SDS method, featuring cost savings, low energy consumption, and waste management solutions.

Section 9: Typical Performance across Various Industries

   1. Coking Industry - Pushing Coal Yard StationShougang Qian'an Sinochem Coal Chemical Co., Ltd. #1, #2, and #3 coke ovens - Push coke surface dust removal with high-activity, high-specific surface area calcium hydroxide desulfurization. The industrial unit was put into operation on June 8, 2021, with stable data below 10mg/m3.

2. Coking Industry - Dry Coke Oven Gas and Coke Oven Flue Gas - High Activity, High Surface Area Calcium Hydroxide Desulfurization

3. Steel Industry - Hot Blast Furnace, Heating Furnace - High Activity, High Surface Area Calcium Hydroxide Desulfurization

4. Other Industries - Waste-to-Energy Plants & Power Station Boilers - High Activity, High Specific Surface Area Calcium Hydroxide Desulfurization