Primary air and secondary air matching optimization method for garbage incinerator

Abstract

The invention provides a primary air and secondary air matching optimization method for a garbage incinerator. A fan, a water cooling wall, a nozzle, a fire grate, a primary air mother pipe, a secondary air mother pipe, a primary air branch pipe, a secondary air branch pipe, an air heater, a flow regulating valve and the like are included. A numerical simulation result shows that under the same operation condition, compared with actual operation, the garbage pyrolysis rate can be increased by 103 kg.m <-2 >. H <-1 > by adopting the primary air temperature, and the fire grate length required by complete garbage incineration is shortened by 1.85 m; the front arch secondary air and the rear arch secondary air adopt the air direction and air quantity ratio, so that the risk of high-temperature corrosion to the wall surface can be reduced, and the operation and maintenance cost of the incinerator is saved. The operation method has the advantages that (1) the turbulence degree of mixing of combustible gas and oxygen is enhanced, the waste incineration effect is improved, and the output of harmful substances such as dioxin and NOx is reduced; (2) the temperature distribution in the incinerator is improved, the service life of the incinerator is prolonged, and the equipment damage risk is reduced;

Description

Technical Field

[0001] The new patent of the present invention relates to the technical field of domestic waste incineration, and in particular to a method for optimizing the matching of primary and secondary air of a waste incinerator. Background Art

[0002] Incineration is one of the main methods of waste treatment at this stage. Compared with landfill and composting, it has the advantages of significant volume reduction and high utilization rate of organic resources. The chemical energy of the fuel itself can be converted into thermal energy through incineration, and then converted into electrical energy through a steam turbine for wide use. The oxygen required for waste incineration is injected into the furnace through the primary and secondary air ports respectively. Reasonable primary and secondary air parameters will promote full incineration of waste and reduce dioxins, NO x The production of toxic components.

[0003] Primary air is the main contributor to the combustion aid of the incinerator. Its function is to provide sufficient oxygen for the incineration of garbage. Air temperature is an important design parameter of primary air. The increase of primary air temperature will accelerate the incineration rate of garbage and shorten the completion time of garbage incineration. However, excessive primary air temperature will cause serious forward shift of incineration. The main combustion zone tends to the front arch, which can easily aggravate the local high temperature phenomenon of the front arch of the incinerator, increase the amount of NOx generated, and increase the primary air temperature. The operating power of the air heater increases, the power consumption of the system increases, and the operating cost of the incinerator increases. On the contrary, a decrease in primary air temperature will cause the waste incineration reaction process to be postponed. Too low an air temperature will cause the main combustion zone to stick to the rear arch, which can easily aggravate the local high temperature phenomenon in the rear arch of the incinerator. At the same time, too low an air temperature can easily cause incomplete waste incineration, increase the grate operation time, and reduce the amount of waste processed. Secondary air provides secondary oxygen supplement for waste incineration. Its function is to enhance the mixing degree of combustible gas and oxygen, increase the residence time of gas in the incinerator, and ensure sufficient waste incineration. The wind direction and air volume of the front and rear arch secondary air are important design parameters of secondary air. Secondary air directly affects the direction of the flame of the incinerator. Reasonable secondary air direction and air volume can keep the temperature distribution in the incinerator uniform, reduce the risk of coking in the incinerator, and reduce the system operation and maintenance cost. Summary of the invention

[0004] On the basis of not changing the structure of the incinerator, in order to improve the waste incineration efficiency, reduce the risk of coking in the incinerator, and ensure the safe operation of the incinerator, the present invention proposes a primary and secondary air matching optimization method for a waste incinerator. Under this operating condition, the temperature distribution of the incinerator can be uniform, the waste incineration effect is optimal, and the operation and maintenance cost of the waste incinerator can be effectively reduced.

[0005] The present invention proposes a primary and secondary air matching optimization method for a garbage incinerator, comprising: a fan, primary and secondary air main pipes, primary and secondary branch pipes, an air heater, a flow regulating valve, a grate, a water-cooled wall, a nozzle and other components.

[0006] The primary and secondary air matching optimization method of a garbage incinerator is to adjust the primary air temperature, the secondary air volume ratio of the front and rear arches and the wind direction parameters during the operation of the incinerator.

[0007] Furthermore, the primary air is sent into the air heater through the primary air main pipe by the fan, and is sent into the air chamber of each grate section after preheating; the secondary air is sent into the front and rear arch secondary air nozzles through the secondary air main pipe by the fan, and the air volume ratio between the front and rear arches is adjusted by a flow regulating valve.

[0008] There are six primary air chambers in total, and each grate includes 1, 3 and 2 air chambers respectively along the direction of garbage movement.

[0009] Furthermore, the garbage stays on the grate for 2 hours, and the total amount of primary air is 45700Nm 3 / h, the primary air temperature is 483K, and the air volume ratio of each air chamber is 12:19:17:12:17:23.

[0010] There are 15 secondary air nozzles, and 7 and 8 front and rear arch nozzles respectively.

[0011] Furthermore, the total amount of secondary air is 8320Nm 3 / h, the secondary air direction of the front arch is 40°, the secondary air direction of the rear arch is 0°, and the ratio of the front and rear arch secondary air volumes is 1.53:1.

[0012] According to the CFD numerical simulation results, when the primary air temperature is 483K, the front and rear arch secondary air volume ratio is 1.53:1, and the wind directions are 40° and 0° respectively, the present invention has the following beneficial effects:

[0013] For the volatile matter pyrolysis rate, when the primary air temperature is 483K, the volatile matter pyrolysis rate is 288kg·m -2· h -1 When the primary air temperature is 463K and 503K, the pyrolysis rates of volatile matter are 185 and 212 kg·m -2· h -1 , which can increase by 103 and 76 kg·m -2· h -1 .

[0014] As for the oxygen content at the incinerator outlet, when the primary air temperature is 483K, the oxygen mass fraction at the incinerator outlet is 5.69%. When the primary air temperature is 463K and 503K respectively, the oxygen mass fraction at the incinerator outlet is 6.80% and 6.18%, which can be reduced by 1.11% and 0.49% respectively.

[0015] When the secondary air directions of the front and rear arches are 40° and 0° respectively and the secondary air ratio is 1.53:1, the temperature distribution in the incinerator is uniform, the risk of high-temperature coking is reduced, and the system operation and maintenance costs are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a plan view of an incinerator used in the primary and secondary air matching optimization method for a garbage incinerator described in the present invention.

[0018] Figure 2 This is a plan view of the secondary air of an incinerator used in the primary and secondary air matching optimization method of a garbage incinerator described in the present invention.

[0019] List of reference numerals: drying section grate 1, combustion section grate 2, burnout section grate 3, fan 4, air heater 5, primary air main pipe 6, rear arch secondary air main pipe 7, front arch secondary air main pipe 8, primary air branch pipe 9, rear arch flow regulating valve 10, front arch flow regulating valve 11, water-cooled wall 12, secondary air branch pipe 13, nozzle 14. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] 1. Incineration process The domestic garbage is pushed into the grate bed by the pusher, and slowly passes through the drying section 1, combustion section 2 and burnout section 3 grates in sequence under the action of the grate. The primary air is sent to the air heater 5 under the push of the fan 4, and is sent to the primary air chamber under each section of the grate through the primary air branch pipe 9 after preheating. The high-temperature primary air promotes the garbage to go through the drying, pyrolysis, combustion and burnout process, and finally removes the ash at the end of the burnout section 3 grate. The secondary air is sent to the corresponding secondary air nozzle 14 through the front arch flow regulating valve 11 and the rear arch flow regulating valve 10 under the action of the fan 4. The volatile gas generated by the combustion is mixed with the high-speed secondary air of the front and rear arches for secondary combustion.

[0022] 2. Heat exchange process The waste incineration process in the furnace of the incinerator is approximately an adiabatic process. The high-temperature flue gas generated by the incineration moves upward along the flue, and during the movement, it undergoes radiation and convection heat exchange with the water-cooled wall 12 on the surface of the waste heat boiler. The temperature of the flue gas gradually decreases after the heat exchange. At the same time, the saturated water in the water-cooled wall vaporizes after absorbing heat. The high-temperature and high-pressure water vapor converts heat energy into electrical energy through the steam turbine. The water vapor after heat exchange is liquefied into saturated water to achieve the effect of recycling.

[0023] The above are only preferred implementations of this patent. It should be pointed out that various modifications and improvements can be made without departing from the principles of this patent, which should also be regarded as the scope of protection of this patent.

[0024] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the invention.

Claims

1. A method for optimizing the matching of primary and secondary air in a waste incinerator, mainly comprising: Components including fans, primary and secondary air main pipes, primary and secondary air branch pipes, air heaters, flow regulating valves, grates, water-cooled walls and nozzles.

2. According to the method for optimizing the matching of primary and secondary air in a garbage incinerator as described in claim 1, there are six primary air chambers in total. The garbage passes through the drying section, combustion section and burnout section grates in the moving direction in sequence. The number of air chambers arranged in each grate is 1, 3 and 2 respectively, and the total amount of primary air is 45700Nm 3 / h, the wind temperature of each wind chamber is 483K, and the air volume of each wind chamber is distributed in the ratio of 12:19:17:12:17:

23.

3. According to the method for optimizing the matching of primary and secondary air in a garbage incinerator of claim 1, there are 15 secondary air nozzles, of which the number of nozzles in the front and rear arches of the incinerator is 7 and 8 respectively, the injection angle of each nozzle in the front arch is 40°, the injection angle of each nozzle in the rear arch is 0°, and the total amount of secondary air is 8320Nm 3 / h, the secondary air temperature is 303K, and the secondary air ratio between the front and rear arches is 1.53:1.

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