Niunin WCFB® Semi-Dry Desulfurization Technique

WCFB® Development Timeline:

Wu Yulin, the founder of Niunin Tech, has a long history with CFB semi dry desulfurization and dust removal technology. Since 2000, he has been engaged in the application and research of fluidized bed semi dry desulfurization and dust removal technology with fruitful results.

  • He was one of the earliest specialists working with CFB desulfurization projects.
  • He was the first project manager of semi dry desulfurization and dust removal project of Wuhan KaiDi Electric Power Environmental Co., Ltd. – Guangzhou Hengyun 200MW semi-dry desulfurization project.
  • Record holder of continuous operation of semi dry desulfurization and dust removal project – 200MW KCFB desulfurization and dust removal project of No.2 boiler of Guodian Jingyuan power plant.
  • RAGAR, a German enterprise, was established in partnership with Zima, the former technical expert of WULLF company in Germany. He fully mastered the whole set of semi dry desulfurization and dust removal technology and solved the problems of all fluidized bed technologies in China.

After years research and explore, Mr. Wu has mastered the key of semi-dry CFB desulfurization system. Eventually, WCFB® technology with independent intellectual property rights has been formed.

WCFB® technology optimizes the CFB to achieve the best operation quality in the whole load range, which means the operation of WCFB® system can always be guaranteed to be in a very stable state in the range of 60% to 100% load, and the stable operation of CFB can be ensured by flue gas recirculation when the load is lower than 60%.

Niunin WCFB® technology achieves the ultra-net emission of flue gas, and its parameter and diagram are as below.

Parameter

SO2 = 85～99％ SO3 ＞ 99％
HCl ＞ 99％ HF ＞ 99％
Dust Emission ＜ 5mg/Nm3 Ca/S = 1.2～1.5
Heavy metal, furan
removal		 ＞ 99％ Dioxin removal ＜ 0.1ng
TEQ/Nm3
Guaranteed availability ＞ 98％

Process Diagram

 

WCFB® Features

  • WCFB® operates continuously and stably without bed collapse, scaling, blockage and performance failure.
  • The emission concentration of smoke, SO2 and NOx shall not be higher than 5, 10 and 50 mg/m3, respectively.
  • The flue gas emission temperature is higher than 80 ℃, the flue gas humidity is low, and there is no aerosol and other substances during desulfurization, thus there will be no haze caused by wet desulfurization.
  • The desulfurization reaction produces no CO2, moreover, adsorb ~ 20% CO2 in flue gas.
  • Almost all pollutants and heavy metals such as sulfur trioxide, mercury, arsenic, HCl, HF, furan and dioxin are removed.
  • The by-product of desulfurization is a dry powder mixture, which can be used as additive for building materials. After being compacted with water, it can be used as subgrade, which will not pollute groundwater. There is no wastewater discharge.
  • The investment is lower than that of wet desulfurization, and the operation cost of flue gas purification in low sulfur coal is far lower than that of wet desulfurization.
  • It is convenient for the upgrading and transformation of stricter environmental protection standards in the future.
  • The flue gas treatment capacity of single tower reaches 2 million m3/h, which is suitable for flue gas purification of thermal power units below 600 MW.

Comparison

Wet
W-FGD		 Semi-dry
WCFB®
The process is mainly the reaction between fluid and gas - the ratio is the key. Therefore, adopting large amount of uniform fluid is required during the process. The process is mainly the reaction between solid and gas - the mixture is the key. Therefore, a stable fluid bed and the full control of pressure difference of fluidized bed is the concern.
Multiple times of clean.Smoke extraction temperature is 50 ~ 60℃. A few times of water spray is needed. Smoke extraction temperature is over 80℃.
SO2 emission concentration is below 35mg/Nm3. Desulfurization efficiency could reach 99%.
Wet Electrostatic Precipitator (WESP) is installed to enable ultra clean emission.		 SO2 emission concentration is below 35mg/Nm3. Desulfurization efficiency could reach 99%.
No additional installation is needed, the system itself supports ultra clean emission.
High humidity will easily cause corrosion.The desulfurization tower, outlet flue and chimney require anticorrosion, which cost more on the building materials, such as 1.4529, 2520, C276, 316L. The whole system is dry. There is no worry about corrosion, and no need to prevent, which saves hugely on building materials - enough with carbon steel.
The humidity of flue gas at the outlet is almost reach saturation. The humidity of flue gas at the outlet is low, far away from saturation.
White pollution at the outlet. Gas at the outlet is merely seen, almost transparent. Please refer to the featured project photos.
Rely on the demister, easy to produce further pollution, for instance the gypsum pours out from the outlet. Dry gas, no supported equipment, no further pollution.
By-product is gypsum, which is available in building materials. By-product is the mixture of calcium sulfite and ash, which is slightly less effective than gypsum, but still works as building materials.
Normal projects exclude the assist equipment cost, like pre- and after-precipitator. To ensure efficiency of the desulfurization, the flue gas dust need less than 100mg/Nm3. The project includes the precipitator, dust removal is guaranteed. No further cost or pollution.
Cannot completely remove SO3, heavy metal, or dioxin, thus less used in waste management and glass industries. 99% removal of SO3, heavy metal, and dioxin, which is largely used in waste/ hazardous waste management and building material industries.
The chloride ions in the flue gas accumulate into the wastewater slowly, which is highly corrosive and needs to be discharged and treated regularly. By-product is in the mixture of dust, no need for wastewater treatment.
The ratio between calcium and sulfur is quite low, is used more on project with high sulfur coal. However, this requests more electricity to proceed. Ratio between calcium and sulfur is high, is used more on projects with low sulfur coal (S≤1%), with less electricity cost.
Water consumption is huge, not economic. Consume few on water, save the resource and cost.

WCFB® Core Equipments

High pressure internal return spray gun
Chute
Chute ash valves
Measurement of
outlet structure
and tower top
Venturi
High pressure return control valve

SCR/SNCR Technique and Product

SNCR Experts

With almost 20 years of experience in SNCR project (design and management), Niunin Tech experts have integrated worldwide advanced CFD flow field simulation technology, front-end process combination technology, nozzle and module manufacturing technology and skid mounted design technology, to eventually develop our own unique SNCR technology, which can offer our customers the professional technical support and product services.

SNCR module supply

Spray gun for project use

Spray gun test experiemnt

Pump unit skid mounted module

Spray nozzle design

SNCR spray gun on experiments, Niunin Tech owns the optimal spray gun design and construction technology.

Test spray nozzle
project decorating

Spray gun ejection experiment
at 30° angle

Spray gun for project use

Wall spray gun

Spray gun ejection experiment
at 45° angle

Wall spray gun

The wall spray gun has successfully applied in multiple projects. In one featured 75 t/h coal fired unit project, the spray gun stably operates and its average efficiency of denitration reaches 75%.

SDS - Sodium derivative system

What is SDS?

Sodium derivative system, also known as SDS, was originally applied into project use by Belgium Solvay. SDS mainly focuses on the acid pollutants in the refuse burner exhaust and industrial boilers. The purify process highly relies on sodium salt, such as sodium hydroxide and soda (sodium carbonate), thus this technique names after sodium.

Technique background

Nowadays, the dry adsorption process using sodium bicarbonate as adsorbent has become an effective means of flue gas purification, which is used to remove various pollutants in the flue gas. Comparing to other desulfurization technique, such as the spray adsorption method using lime milk as adsorbent, SDS is widely applicable to plenty situations while its effect is also guaranteed. Dry flue gas purification can be used not only in coal-fired power plants, garbage, or alternative fuel incineration plants, but also in industrial furnaces in glass, cement, metallurgy, and other industries. Dry flue gas purification can reach the emission standard economically.

Principle

During the fuel gas desulfurization process, sodium bicarbonate (NaHCO3) works as adsorbent via chemical reaction and physical mechanism. The effective method removes both acid pollutants and organic/inorganic trace substances. The key to this process is to directly inject sodium bicarbonate powder into high temperature flue gas, where chemical reaction occurs -sodium bicarbonate decomposes into sodium carbonate, Na2CO3, H2O and CO2. The new produced sodium carbonate Na2CO3 is highly reactive and will automatically react with acid pollutants in the fuel gas. In principle, soda (Na2CO3) is also available for the desulfurization, the mechanism maintains almost the same, except for its slightly lower chemical reactivity.

The chemical reaction occurs during the process is listed as following.

Main reaction: 2NaHCO3(s) = Na2CO3(s) + H2O(g) + CO2(g) ①
SO2(g) + Na2CO3(s) + O2 = Na2SO4(s) + CO2(g) ②
Other reaction: SO3(g) + Na2CO3(s) = Na2SO4(s)+CO2(g) ③
2HCL(g) + Na2CO3(s) = 2NaCL(s)+CO2(g) ④

In order to reach the SDS system expectation, these core factors need to be concerned.

  • The choice of mill
  • Fuel gas temperature
  • The mix ratio of sodium bicarbonate and flue gas
  • The consideration of applying bag filter

Superfine mill

SDS mechanism has been successfully put into project operation in China. The superfine mills used are basically imported and mainly concentrated in three countries: Italy, Germany, and Canada.

With the rapid development of 3D print technology, especially the powder preparation field, domestic superfine mill reaches the same result. Thus, no need of import equipment to operate SDS process, national mill and soda will satisfy the pre-requirements of this mechanism.

Niunin SDS Process Flowchart

Fuel gas treatment features

  • Semi-dry process, simple and reliable mechanism (over 8100 hours operation time per year).
  • Absorbent (NaHCO3) and residual reactants are nontoxic and non-irritative.
  • Residual reactant is a small quantity of dry solid.
  • The adsorption rate of HCl is higher than 99%.
  • The adsorption rate of SO2 is higher than 99%.
  • The variation of pollutants concentration is within consideration.
  • The absorbent is one-time cost, the later treatment and process only requires very a few expenses.
  • The whole investment is economic.
  • Low operation and maintenance cost.

Low Nitrogen Combustion

This section is under development.

Environmental Protection Steam Island Technology

This section is under development.