How to Improve the Combustion Efficiency of Grate Incinerators?

Raising the combustion efficiency of a grate incinerator starts with waste pre-treatment, the grate system, combustion parameters, in-furnace disturbance, furnace temperature and the thermal system. These links are related to each other and need to be adjusted together according to the waste characteristics and the operating conditions.

Waste pre-treatment and the grate system

Moisture can be lowered by windrow fermentation in advance so that leachate drains out of the waste, raising the lower heating value and making the waste easier to burn, which in turn raises combustion efficiency. Waste particle size is controlled by pre-treatment such as crushing and screening so that the particles are even and suitably sized. This increases the contact area between waste and air, supports complete combustion and avoids uneven burning caused by differences in particle size.

The grate structure should be given a suitable shape, size and inclination to suit the waste characteristics and combustion requirements, so that the waste moves steadily and evenly on the grate and mixes fully with air. Grate openings must be cleaned regularly to prevent waste from blocking them, keeping ventilation good so that primary air can penetrate the fuel bed and supply enough oxygen for combustion.

Combustion parameters and in-furnace disturbance

Feed speed and feed rate should be adjusted to the grate movement speed, the waste heating value and the combustion conditions, so that the waste is evenly distributed in the furnace and keeps a suitable residence time, avoiding incomplete combustion caused by over-feeding or under-feeding. Grate speed should be adjusted together with the combustion progress and the furnace temperature distribution, so that the waste is properly handled in the drying, combustion and burnout stages and overall combustion efficiency rises.

On air volume, primary air mainly supplies the oxygen needed in the early stage of waste combustion, so that the waste ignites smoothly and burns stably. Secondary air is used to strengthen the turbulence of the gas flow in the furnace, so that the flue gas produced by combustion mixes fully with air, the path of fly ash and combustible matter in fly ash inside the furnace is lengthened, flame lift is suppressed and incomplete combustion products are reduced. Disturbance devices such as stirrers and pulsed pneumatic devices can also be fitted in the furnace, so that the waste keeps turning and mixing during combustion, the piled state is broken up and the waste contacts air fully.

Furnace temperature and thermal system

The shape, size and combustion method of the furnace should be designed reasonably, optimising the flow path and residence time of the waste in the furnace and improving temperature uniformity, so that the waste can burn fully in a high-temperature environment. The furnace should be well insulated to reduce heat loss and lower the flue gas temperature, which both raises thermal utilisation efficiency and helps maintain a high-temperature environment in the furnace for complete combustion of the waste.

In the thermal system, piping layout and heat exchanger selection should be optimised as a whole to raise heat transfer and conversion efficiency, so that the heat released by waste combustion is converted more effectively into steam or other usable energy. Within the range the equipment allows, boiler outlet steam pressure and temperature can be raised appropriately to improve thermal utilisation efficiency, but the pressure rating of the equipment and the increase in cost must be taken into account.

Automatic control and process features

An automatic control system can monitor parameters such as furnace temperature, pressure, flow and oxygen content in real time, and automatically adjust operating parameters such as feed speed, grate speed and air volume according to a preset combustion model and control strategy, achieving precise combustion control and reducing the error and instability that manual intervention brings. Together with data analysis and fault diagnosis technology, it can also find abnormal conditions and potential faults in the combustion process in good time and give early warning, so that faults do not grow and affect combustion efficiency and safe operation of the equipment.

The equipment as a whole is simple in structure, easy to operate and convenient to maintain, while the grate resists high temperature, corrosion and wear and has a low replacement rate. Air distribution is even, the waste burns evenly, incineration is complete and the heat loss on ignition is ≤5%. The equipment is modular, easy to install, short in construction period and fully automated.