Integral fuel grading supply technology for gas-fired boiler and low-nitrogen gas-fired boiler

Abstract

The invention relates to an integral fuel grading supply technology for a gas-fired boiler and a low-nitrogen gas-fired boiler. The integral fuel grading supply technology is characterized in that a gas for a boiler is integrally differentiated as a main supply gas for a main combustion zone and an auxiliary supply gas for a re-combustion zone, a gas spray gun zone is differentiated as a main supply type and an auxiliary supply type, the position of a main-supply-type gas spray gun corresponds to that of the main combustion zone, and the position of an auxiliary-supply-type gas spray gun corresponds to that of the re-combustion zone. The concentrated combustion speed in the main combustion zone is reduced by reducing the gas supply amount of the main combustion zone; heat load is preventedfrom being excessively concentrated to reduce the production of NOx in the main combustion zone; as the re-combustion zone is replenished with the auxiliary supply gas, a combustion environment witha new fuel injected therein, high fuel-gas temperature and low oxygen content is created; normal combustion which can inhibit the production of NOx can be stably, uniformly and continuously performedin a hearth; and a reduction reaction is performed between reducing components in the auxiliary supply gas and NOx which is originally generated in a flue-gas flow under a high temperature and low-oxygen condition, so that the total production of NOx is inhibited, and the demand for an environmental index of low NOx emission is met.

Description

technical field [0001] The invention relates to the technical field of boiler combustion, in particular to an integral fuel grading supply technology for a gas boiler and a low-nitrogen gas boiler, which are beneficial to improving gas utilization rate and reducing boiler NOx emissions. Background technique [0002] With the enhancement of people's awareness of environmental protection, more and more attention has been paid to the pollution caused by boiler exhaust gas to the social environment. At present, the environmental protection department has proposed that the NOx emission of new natural gas boilers should be lower than 30mg / Nm 3 The requirements of environmental protection standards, and the gas-fired boilers that have been put into operation must be modified to meet the emission standards. [0003] At present, all the gas required for the combustion of gas-fired boilers in operation in my country is provided by a number of gas spray guns arranged in the throat of ...

AI Technical Summary

Problems solved by technology

This traditional working mode of centrally providing gas at the front of the furnace and gradually advancing natural combustion is relatively primitive. Its disadvantage is that the heat load in the initial combustion stage in the front area of ​​the furnace is too concentrated, resulting in uneven distribution of flames in the furnace , it is easy to generate many local high-temperature points in the furnace that are easy to generate a large amount of NOx nitrogen oxides, so it is difficult to meet the ultra-low nitrogen emission requirements of the boiler; in addition, the CH4 / CO / H2 contained in the gas fuel are commonly used in the industry. The reducing agent has the function of reducing NOx under certain conditions, but it does not have the conditions to use it in this original combustion working mode, so not only is there a waste of resources, but it is also not conducive to the low NOx production of gas-fired boilers; in addition , because the gas is concentrated in the initial combustion section area upstream of the flue gas, it first performs relatively concentrated rapid combustion, and then diffuses to the middle and rear of the furnace along with the direction of the flue gas flow, and burns slowly. Furnaces with irregular furnace structure and poor flue gas circulation are more likely to have uneven flame distribution, which is more likely to cause high NOx generation and CO concentration, and even cause vibration when the boiler burns. big problem

Therefore, the use of this traditional working mode of one-step fuel supply and centralized supply is not scientific and reasonable on the whole, the utilization rate of gas fuel is not high, and it is difficult for gas-fired boilers using this traditional working mode to meet the requirements of low NOx emission standards.

Therefore, it is necessary to start from innovation and improvement, and further explore a novel working mode that is more scientific and reasonable, and can fundamentally solve the problem of low-nitrogen combustion of boilers, so as to solve the problem that the current ubiquitous gas-fired boilers are difficult to meet environmental protection and low-nitrogen emissions. problem

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