Grate for biomass boiler

Abstract

The invention provides a grate for a biomass boiler, which can supply air distinctively and is provided with an oxygenation area structure; the grate comprises a grate body for supporting and ventilation, and is characterized by comprising a plurality of rib plates and a plurality of water-cooled wall pipes; the rib plates and the water-cooled wall pipes are sequentially lined at intervals, and the rib plates are provided with vent holes; the density of the vent holes of the rib plates which are close to a feed opening and are far from the feed opening is smaller than the density of the vent holes in the middle part of the rib plates; the middle part of each rib plate is also provided with a plurality of hoods with cavities inside which protrude out of the surface of the rib plate; and the inside cavities of the hoods are communicated with the upper side and the lower side of the rib plate. The grate of the invention can increase an oxidation area but reduce a reduction area when the biomass on the grate is burned, and effectively improve the burning efficiency of the biomass.

Description

technical field [0001] The invention relates to a fire grate used on a boiler, more specifically, to a fire grate for a biomass boiler with a distinguishable air supply and a structure for increasing oxidation regions. Background technique [0002] At present, most of the biomass power plants in my country adopt vibrating grate boilers with imported technology, and their basic structure can be found in the accompanying drawings. figure 1 , the shown primary air passes through the first air chamber 4, the second air chamber 5 and the third air chamber 7 and then passes through the grate 3 and enters the boiler furnace 1, and the secondary air enters the boiler furnace 1 directly from the secondary air nozzle 18, but the biomass The combustion of the vibrating grate boiler is quite different from that of ordinary layer-fired boilers and chain boilers, and even from the coal-fired vibrating grate boilers commonly used in my country. Therefore, there is basically no experience in...

AI Technical Summary

Problems solved by technology

The demand for air in these areas is very different. In the new fuel area, oxygen is basically not needed, and only a small amount of primary air is needed to dry biomass materials; Oxygen is supplied by the primary air, mainly by the secondary air to supply oxygen for combustion in the furnace; in the oxidation area, the primary air is required to supply sufficient oxygen to cause the combustion to release a large amount of heat violently, and to burn the coke in the bed material; while in the reduction The area is to reduce carbon dioxide to carbon monoxide and absorb heat; in the back is the burnout area, which is mainly ash containing a small amount of unburned carbon, which requires a small amount of oxygen. It can be seen that the size of the oxidation area is critical to combustion efficiency , but under normal combustion conditions, the oxidation area is not large, especially after the grate vibrates, the new fuel area and reduction area become larger, and the oxidation area will be further reduced, so that the temperature of the grate and the furnace temperature will also drop. When the biomass material releases a large amount of combustible gas, and the secondary air volume is not increased in time, a large amount of combustible gas is wasted, which increases the chemical unburned loss of the boiler

[0006] At present, the primary air chamber of the biomass boiler with relatively large capacity is separated according to the combustion area, as shown in the attached drawing of the manual. figure 1 As shown, it is generally divided into the first air chamber 4, the second air chamber 5 and the third air chamber 7, and the air supply is controlled respectively through the primary air control baffle 6; the primary air chamber of the relatively small biomass boiler is not separated, and the air is supplied uniformly. In this way, the air supply cannot be differentiated according to the different air volumes required in each area, so that the combustion area (such as the oxidation area) that requires a large amount of oxygen cannot achieve the purpose of full combustion because it cannot supply sufficient oxygen, and basically does not need one time. The area where the wind supplies oxygen (new fuel area and volatile matter precipitation area) supplies a lot of air and produces a certain amount of waste

But the problem is that even after being divided into three air chambers, the primary air in the main combustion area (such as the oxidation area) is still insufficient or the primary air cannot reach the upper position of the oxidation area on the grate, resulting in the oxidation area being too small and reducing If the area is too large, the loss of unburned combustible gas will be large, especially when the grate is just vibrating, a large amount of new fuel will enter and spread, which will further reduce the oxidation area. At this time, the combustion state is close to the gasification process of biomass, resulting in a large amount of CO and CmHn, while the total air volume does not increase at this time, the amount of oxygen in the supplied air cannot completely burn CO and CmHn, resulting in a significant increase in chemical incomplete combustion losses

In addition, the control baffles of the air chambers of the current biomass vibrating grate boilers have relatively poor adjustment characteristics and are prone to failure. In order to reduce the failure rate, some biomass power plants have to remove the air intake adjustment baffles. The situation exacerbates the amount of heat loss from biomass

[0007] Through the above analysis, it can be seen that one of the main reasons for the large heat loss of the current biomass boiler is that the air supply volume does not match each combustion area, that is, the air supply cannot be differentiated according to the oxygen demand of different combustion areas; the other is that each combustion area The proportion of space actually occupied by the region is not balanced compared with the ideal state

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