By CC 2019-10-21 16:00:49
1. NOx hazards
In the combustion process of fuel, the NOx in the atmosphere dissolves into water and generates nitric acid rain. The acid rain will bring a wide range of tails to the environment, causing huge economic losses, such as corrosion of buildings and industrial equipment; Cultural relics; damage to plant pages, leading to forest death; death of fish and shrimp in lakes; destruction of soil components, production of crops and even death; drinking groundwater caused by acidification, harmful to humans. At the same acid concentration, nitric acid rain is twice as damaging to trees and crops as sulfuric acid. NOx also directly damages human health. The greater the NOx concentration, the stronger its toxicity, because it is easy to combine with the hemoglobin in the blood of animals, causing blood hypoxia and causing central nervous system paralysis. NOx is exposed to the sun's ultraviolet rays and automobile exhaust. When a hydrocarbon is present, a light blue toxic nitro compound can form a photochemical smog. Urban photochemical smog refers to the urban atmosphere containing primary pollutants such as hydrocarbons and nitrogen oxides, a special mixture of products and reactants produced by chemical reactions of solar radiation. Photochemical smog has a great irritating and toxic effect on the human body. It stimulates the eyes, nose, trachea and lungs, causing redness, tears, cough and other symptoms. The long-term chronic tail also causes lung function, bronchial inflammation, and even cancer. In severe cases, people can be dizzy, chest pain, nausea and vomiting, hand and foot convulsions, blood pressure drop, coma and even death. Photochemical smog can cause thousands of people to suffer or die, and can also cause plants to fade green, the color of the hundred years, causing leaf damage, leaf fall, flower fall and fruit drop until production is reduced or rejected. In addition, the incidence of livestock can be increased, causing cracks in rubber products, corrosion of metals, damage to various utensils, materials and buildings. Photochemical smog is easily formed due to the large amount of nitrogen oxides and hydrocarbons emitted in the city and the unique climatic conditions.
2. Measures to reduce NOx emissions
1. Low-nitrogen burners use staged combustion, local oxy-combustion, flue gas internal circulation and the design of rapid mixing simulation premixing effects to control the generation of thermal NOx and rapid NOx. Rapid mixing achieves the effect of premixing, forming a uniform fuel and air mixture before reaching the ignition point, avoiding areas with excessive local fuel, and significantly reducing the formation of rapid NOx. In addition, in this area, an oxygen-rich combustion zone with a large excess of air is formed, which helps to lower the temperature of the flame and reduce the generation of thermal NOx. The blazing is distributed to different areas, and the staged combustion delays the mixing of the fuel and the air and fully expands the flame, lowers the peak value of the flame and the average temperature, and greatly reduces the generation of thermal NOx.
2. The arrangement of the burner injection port is arranged in layers and sections, and the center is provided with a central gun and a stable flame disk and uses diffusion combustion. The injection port adopts a method of supplying fuel in stages. According to the distribution of the load, the injection port part bears 90% of the load, and the center gun takes up 10% of the load of the burner. The arrangement of the gun and the injection port is formed as a split layer. The burner head that is arranged in a staggered and misaligned manner can cause the airflow to swirl and fully burn to reduce nitrogen oxides. The HANWELL low-nitrogen burner uses staged combustion, local oxy-combustion, flue gas internal circulation, and rapid mixing simulation premixing to control thermal NOx and rapid NOx generation. Rapid mixing achieves the effect of premixing, forming a uniform fuel and air mixture before reaching the ignition point, avoiding areas with excessive local fuel, and significantly reducing the formation of rapid NOx. In addition, in this area, an oxygen-rich combustion zone with a large excess of air is formed, which helps to lower the temperature of the flame and reduce the generation of thermal NOx. The fuel is distributed to different areas, and the staged combustion delays the mixing of fuel and air and fully expands the flame, reducing the peak and average temperature of the flame, and greatly reducing the generation of thermal NOx. Using the simulation design base, the burner is custom designed to best match the original boiler. The combustion flame is suitable for the furnace size, and the combustion and discharge meet the optimal operation requirements. The central gun maintains the combustion mode of the diffuser burner, and this central gun takes into account the function of the igniter and bears 1 to 30% of the load on the burner. The gun also has an important role in maintaining the permanent force of the furnace. Flame, which solves the problem of easy tempering and unsafeness of a fully premixed surface burner.
3. The mixed gas is reversely arranged by two-stage swirling to enhance the mixing effect and reduce nitrogen oxides.
4, using CFD simulation design base, burner custom design, so that it is the best match with the original boiler, the combustion flame is suitable for the furnace size, combustion and emissions to achieve the best operational requirements, including:
Combustion flame temperature distribution simulation
Combustion throat flow field velocity vector simulation
Simulation of the match between flame shape and boiler furnace size
Simulation analysis of nitrogen oxides and carbon monoxide production
5, low oxygen