Influence of low nitrogen burner transformation on boiler operation

Influence of low nitrogen burner transformation on boiler operation
Under the requirements of environmental protection policies, the industry now also attaches great importance to energy conservation and emission reduction measures. Low-nitrogen combustion technology has certain advantages in environmental protection, but also has a certain impact on boiler operation. Therefore, it is necessary to further strengthen the treatment measures for problems arising from new environmental protection technologies and strive for the largest environmental protection mechanism for the sustainable development of industry. This paper discusses the relevant content, which has certain practical significance.
1. Connotation analysis of burner
Burner is the main combustion equipment of boiler in fuel power plant. The furnace is installed on the four corners or walls of the boiler furnace. The burner injects various fuels and air required for combustion into the furnace in a certain way, so that the fuel and air are fully mixed in the furnace and ignite rapidly under a certain airflow structure to maintain stable combustion. Burner is a highly automated electromechanical equipment, mainly including air supply, ignition, monitoring, fuel and electrical control system. According to the type of fuel, burners can be divided into pulverized coal burner, gas burner and fuel burner. The burner uses primary air and secondary wind direction to inject pulverized coal fuel into the furnace. When the mixed fuel is mixed with air, a special air flow structure is formed to make the fuel stable and fully burn. The secondary air rotating jet is used to combine the rotating jet with the surrounding medium, and enhance the ignition characteristics of pulverized coal flow.
2. Analysis of influence of low nitrogen burner transformation on boiler
(1) The influence of combustion stability is reflected in many aspects, the most important of which is the stability of temperature and the stability during operation. Low-nitrogen burners are equipped with a concentration/dilution combination at the primary jet port, and are designed according to the asymmetric principle of heat and power in the combustion process by using technologies such as thermal reflux relay combustion. The pulverized coal at the pyrolysis jet port is connected with the composite jet swirl at the center of the boiler. The high reflux rate of the thermal reflux carbon powder extends the residence time and increases the heat generated by combustion in the swirl. The boiler's low-nitrogen transformation also controls the amount of oxygen, During the combustion process, oxygen needs to meet the combustion conditions to generate heat. Since the number of oxygen is controlled, the generation of heat is also inhibited, which affects the operation of the boiler. These two operation modes have an impact on the stable operation of the boiler.
(2) The influence of the internal environment of the boiler on the low nitrogen burner nozzle is less than that of the traditional burner, so the flame generated by the fuel also moves. The reduction of combustion area will reduce the boiler's acceptance of temperature, and the pressure state generated inside the boiler will also change, resulting in disharmony. The transformation of low nitrogen burner equipment has changed the boiler components and the operation conditions are also different. The modification of the low nitrogen burner has affected the oxygen content inside the boiler to a certain extent. Generally, there is the maximum and minimum operating oxygen content. The unit adjustment cannot keep up with the oxygen content adjustment and negative oxygen is generated. The change of oxygen content and the change of combustion degree have changed the pressure inside and outside the boiler and changed the internal environment. Relevant personnel need to adjust the oxygen content and directly carry out the air supply operation.
(3) The reheating temperature of the boiler is affected. The elevation of the original burner is reduced after the transformation of the low nitrogen burner, which has a great impact on the reheating temperature. After burner transformation, the unit coordination is slow, the boiler pressure tracking and adjustment can not keep up, and it is easy to cause over-adjustment and temperature change. The modified low nitrogen burner has a set of oscillating burners. When the nozzle swings upward, the temperature of steam will rise, and when the nozzle swings downward, the temperature will drop. However, because there is only one set of oscillating burners, the temperature adjustment speed is limited, the adjustment time is too long, and the air ratio is controlled by low oxygen conditions, affecting the efficiency of the machine. In order to ensure that the boiler outlet temperature is within the low load range, the powder manufacturing system must be adopted, which will cause the heating surface temperature to be too high and difficult to exceed the temperature. At the same time, the outlet temperature should be controlled within a certain range to affect the normal operation of the boiler.
(4) Influence on furnace coking. During the use of low nitrogen burners, although coking may occur during the operation of the burners, especially when starting the lower pulverizing system, which will affect the furnace coking, coking still exists at the burner nozzle during the operation, especially when starting the lower pulverizing system, which will significantly affect the negative pressure, indicating that the combustion zone is not in good condition, because the main combustion zone is in anoxic combustion, Therefore, the cold wall coking phenomenon will occur near the burner, especially when the lower coal pulverizing system is started, which will have a significant impact on the boiler combustion status, indicating that the combustion zone is not in good condition, because the main combustion zone is anoxic and anoxic, so the cold wall coking phenomenon will occur near the burner, which will have an impact on the furnace coking.
(5) The low nitrogen burner not only reduces the NO production rate, but also increases the combustibility of the slag. Low-nitrogen combustion technology uses low temperature and low oxygen conditions for combustion. The more the temperature in the combustion zone decreases, the greater the impact of pulverized coal ignition. The oxygen content in the combustion zone decreases, the combustion capacity of pulverized coal decreases, the combustion process also increases, the slag combustibles increase, the burner nozzle area changes, the mixing air delay, and the pulverized coal airflow in the boiler.
Summary: The advantages and disadvantages of the boiler in operation will be affected by many factors. Although the transformation of the low nitrogen burner has a certain impact on the boiler operation, in order to keep the energy clean and reduce the harm to the environment, it is still necessary to optimize the low nitrogen burner in combination with the actual situation, standardize the transformation process of the low nitrogen burner, and improve the reliability of the boiler operation.