LCO-500 Full Oxygen Combustion Oxygen Generator

Principle of Oxygen Generator for Oxy-Fuel Combustion

The core adsorbents used in industrial oxygen generators for oxy-fuel combustion include pressure swing adsorption silica gel, activated alumina, high-efficiency Cu-based adsorbents, lithium-based oxygen-producing adsorbents, etc. UOP pressure swing adsorption silica gel is designed for the production process of adsorbents in pressure swing adsorption gas separation technology. By controlling the pore size distribution and pore volume of the adsorbent and altering its surface physicochemical properties, it achieves characteristics such as high adsorption capacity, fast adsorption and desorption rates, strong adsorption selectivity, high separation coefficient, and long service life. Using 5A zeolite molecular sieve as the adsorbent and a two-bed PSA device, breakthrough progress has been made in the industrial application of pressure swing adsorption oxygen production technology. It is primarily used in oxygen-nitrogen separation, air drying, and purification. Among these, the technological advancement in oxygen-nitrogen separation involves combining the new adsorbent carbon molecular sieve with pressure swing adsorption to separate O2 and N2 from the air, thereby obtaining nitrogen. With improvements in the performance and quality of molecular sieves, as well as continuous enhancements in pressure swing adsorption processes, the purity and recovery rate of the product have been steadily increasing. Working principle of the oxygen production system: For any given adsorbed gas, the adsorption process follows specific principles.

Process Flow of Oxygen Generator for Oxy-Fuel Combustion

Under adsorption equilibrium conditions, the lower the temperature and the higher the pressure, the greater the adsorption capacity. Conversely, the higher the temperature and the lower the pressure, the smaller the adsorption capacity. Therefore, gas adsorption separation methods typically employ two cyclic processes: temperature swing adsorption or pressure swing adsorption. Adsorption occurs under pressurized conditions, while desorption is achieved by reducing pressure (vacuum) or at atmospheric pressure, a method known as pressure swing adsorption. Thus, pressure swing adsorption involves adsorption and desorption through changes in pressure. Due to the low thermal conductivity of adsorbents, the temperature changes in the adsorbent bed caused by adsorption and desorption heat are minimal during pressure swing adsorption operations, allowing it to be regarded as an isothermal process. Its working conditions approximately follow the常温 adsorption isotherm. In pressure swing adsorption (PSA), compressed air from the air compressor first enters a refrigerated dryer to remove moisture and then enters a PSA oxygen production unit consisting of two adsorption towers. Specialized molecular sieve adsorbents filled in the towers selectively adsorb impurities such as N2, CO2, and other gas components, while the product gas, O2, is discharged from the top of the tower with a purity ranging from 25% to 95%.

During pressure reduction, the nitrogen adsorbed by the adsorbent desorbs and is discharged through countercurrent release at the bottom of the tower. After purging, the adsorbent is regenerated. The regenerated adsorbent can then be switched back to adsorption after equalization pressurization and product pressurization. By alternating the use of the two towers, continuous air separation for oxygen production is achieved. Zeolite molecular sieves were initially used in industry primarily for air drying and hydrogen purification. Later, they were developed for air oxygen or nitrogen production. Subsequently, carbon molecular sieves or vacuum pressure swing adsorption methods using zeolite molecular sieves were successfully developed to produce oxygen or nitrogen from the air, enabling the production of medical oxygen using a single-bed PSA method. Adsorption separation utilizes the differences in adsorption and desorption capacities of adsorbents for specific gases. To facilitate this process, common methods include pressurization and vacuum techniques. The mechanism of molecular sieve pressure swing adsorption for air separation to produce oxygen relies on two factors: first, the molecular sieve's greater adsorption affinity for nitrogen than for oxygen to separate oxygen, and second, the faster diffusion rate of oxygen compared to nitrogen in the narrow pores of the carbon molecular sieve microporous system.

Benefits of Oxygen Generator for Oxy-Fuel Combustion

1. Oxygen-enriched combustion can increase the flame temperature in the combustion zone.

Studies show that flame temperature significantly increases as the proportion of oxygen in the combustion air rises. Oxygen-enriched combustion can markedly elevate flame temperature, enhancing the heating effect on the batch and molten glass. The combustion process involves oxygen in the air participating in fuel gasification while simultaneously emitting light and heat. Thermal radiation primarily depends on factors such as flame type and shape, the oxygen content in the supplied air, and the conditions surrounding the combustion. Since the rate of heat transfer is proportional to the fourth power of temperature, increasing the combustion temperature will substantially enhance thermal radiation.

2. Oxygen-enriched combustion reduces the amount of air required for combustion, decreasing the heat carried away by exhaust gases.

In conventional combustion, only about one-fifth of the total air volume, which is oxygen, participates in combustion. The remaining approximately four-fifths, consisting of nitrogen, not only does not aid combustion but also carries away a significant amount of heat generated during combustion, which is discharged through the flue gas. When using oxygen-enriched air, fuel combustion is more complete, naturally reducing exhaust gas emissions and correspondingly lowering heat loss from flue gas discharge.

Application of pressure swing adsorption oxygen production in the field of oxygen-enriched combustion: The oxygen content in air is 21%. Industrial boilers and kiln furnaces also operate under such air conditions. Practice has shown that when the oxygen content in the gas for boiler combustion reaches above 25%, energy efficiency can increase by over 20%, and the time required for boiler startup and heating can be shortened by 1/2 to 2/3. Oxygen enrichment involves using physical methods to collect oxygen from the air, resulting in an oxygen-enriched gas content of 25% to 30%. By introducing this portion of oxygen-enriched gas into the boiler or kiln as secondary air, the overall or local oxygen content in the furnace can be increased, reducing the overall excess air coefficient in the furnace. This effectively mitigates heat loss due to excess air carrying away heat and lowers the flue gas temperature. The increase in oxygen enrichment improves ignition conditions and ensures complete combustion, achieving energy savings while also meeting environmental protection requirements and complying with national emission reduction standards.