Organic solid waste self-maintaining smoldering treatment method based on catalytic oxidation in furnace
Technical Field
The invention belongs to the field of solid waste disposal, and particularly relates to an organic solid waste self-maintaining smoldering disposal method based on catalytic oxidation in a furnace.
Background
The organic solid waste comprises high-water-content low-heat-value organic solid waste such as kitchen waste, oil field sludge, municipal sludge, river sludge, oil soil, biogas residue and the like. Currently, traditional disposal of organic solid wastes such as domestic garbage mainly relies on incineration by an incinerator. However, the organic solid wastes with high water content and low calorific value do not have the conditions for direct incineration disposal in the traditional incinerator due to the characteristics of the organic solid wastes, and the incineration disposal process is difficult to burn, or the combustion temperature needs to be raised by adding high calorific value fuel, so that the process cost is increased.
Smoldering disposal is a novel organic solid waste heat disposal technology, and the special principle of the smoldering disposal is particularly aimed at high-water-content low-calorific-value organic solid waste. The smoldering disposal process relies on a porous medium material (usually sand) as an auxiliary ingredient to be fully mixed with high-water-content low-calorific-value organic solid waste, so that the specific surface area of the organic component participating in the reaction is indirectly increased, the transmission path of oxygen in the organic component is improved, a heat storage function is provided in the process, and limited heat released by the combustion reaction is fully utilized. Compared with the traditional combustion process, the smoldering treatment enables the direct incineration treatment of the organic solid waste with high water content and low calorific value to be possible, a large amount of external heat energy or fuel is not required in the treatment process, and the process energy consumption is greatly reduced.
However, in the existing smoldering technology, due to the characteristics of lower combustion, upper pyrolysis and continuous transmission from bottom to top in the process, the combustible gas components such as carbon monoxide in the discharged flue gas are high, and the discharged flue gas needs to be purified and then is discharged into the atmosphere. Meanwhile, the current catalytic oxidation flue gas treatment technology mainly utilizes temperature rise or flue gas residual temperature to perform catalytic oxidation on waste combustible flue gas components after flue gas is discharged out of a furnace body, and then the purpose of purification is achieved, however, because the flue gas temperature is low (80 ℃) and the humidity is high (about 80% -90%) in the smoldering treatment technology, the technical difficulty of the prior art in flue gas purification in the smoldering treatment process is improved, and the overall complexity and the implementation cost of a process system are improved.
Disclosure of Invention
Aiming at the defects or improvement requirements of the prior art, the invention provides a self-sustaining smoldering treatment method of organic solid waste based on catalytic oxidation in a furnace, which aims to organically combine a catalytic oxidation technology and a smoldering technology, improve the further oxidation of combustible gas components in the self-reaction process while improving the reaction process of smoldering treatment, reduce the pollution emission of flue gas and optimize the treatment process of the smoldering organic solid waste.
In order to achieve the aim, the invention provides an organic solid waste self-maintaining smoldering disposal method based on catalytic oxidation in a furnace, which comprises the following steps:
the method comprises the following steps of taking a mixture of organic solid waste, a porous medium material and a catalyst as a packed bed material in a smoldering furnace, then starting heating, introducing air into the smoldering furnace, and enabling the organic solid waste mixed in the porous medium material to have a smoldering reaction, wherein unburned flue gas generated by the smoldering reaction continuously has an oxidation reaction with residual oxygen under the action of the catalyst when passing through a pyrolysis reaction layer on a smoldering reaction surface, so that the content of waste gas generated by the smoldering reaction is reduced, and the smoldering treatment of the organic solid waste is completed.
Preferably, the mass part ratio of the porous medium material, the organic solid waste and the catalyst in the mixture is 33.3-81.4: 14.3-20: 4.1-51.4.
Further preferably, the temperature of the pyrolysis reaction layer is 300 ℃ to 500 ℃ when the unburned flue gas continues to be subjected to oxidation reaction with the residual oxygen under the action of the catalyst.
More preferably, after the start of heating, when the bottom layer temperature of the packed bed material reaches 250 to 300 ℃, the introduction of air into the smoldering furnace is started.
More preferably, the Darcy flow rate of the air introduced into the smoldering furnace is 3cm/s to 5 cm/s.
Further preferably, the catalyst is a platinum supported catalyst, a cerium oxide supported catalyst, a zirconium oxide supported catalyst, a manganese cobalt catalyst or a copper dichromate catalyst.
As a further preference, the catalyst is a manganese cobalt catalyst supported on diatomaceous earth or alumina particles.
More preferably, the catalyst has a particle size of 0.5mm to 2 mm.
More preferably, the porous medium material is a spheroidal particle with a particle size of 0.5 mm-1.2 mm.
As a further preferable mode, the water content of the organic solid waste is not less than 80%.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. aiming at organic solid waste with high water content and low calorific value, the smoldering treatment process is combined with a catalytic oxidation technology, and a catalyst replaces part of porous medium materials to be used as a mixed packed bed material component in the smoldering furnace, so that unburned flue gas generated on a smoldering reaction surface continuously performs an oxidation reaction with residual oxygen when passing through a pyrolysis reaction bed layer on the smoldering reaction surface, the concentration of the finally discharged unburned flue gas is reduced, the optimization of the traditional smoldering treatment process is realized, and the requirement of flue gas purification is reduced.
2. The method comprises three processes of particle size smoldering, pyrolysis and drying from bottom to top in a reactor in a smoldering treatment process, wherein carbon monoxide, alkane, alkene, alkyne and micromolecule organic gas compounds are inevitably generated in the smoldering and pyrolysis processes under the process condition.
3. The method enables organic solid wastes to fully react by regulating and controlling the proportion of the materials in the packed bed and the Darcy flow rate of air; the catalyst loaded with manganese and cobalt and based on diatomite or alumina particles is selected, unburned flue gas (such as carbon monoxide, methane and other gas small molecule organic compounds) generated by smoldering reaction can be treated, the influence on the smoldering process is avoided, and meanwhile, the propagation rate of a smoldering reaction surface can be improved under the same smoldering treatment working condition by using the catalyst, so that the process optimization of the smoldering treatment process is achieved.
Drawings
FIG. 1 is a schematic diagram of a self-sustaining smoldering treatment method for organic solid waste based on catalytic oxidation in a furnace according to an embodiment of the present invention;
FIG. 2 is a schematic view of a typical smoldering furnace structure and operation in accordance with an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The smoldering disposal method provided by the embodiment of the invention is carried out based on a typical smoldering furnace, as shown in fig. 2, the smoldering disposal method is divided into a DE section air distribution device, a CD section coarse sand grain filler, a BC section heating device and an AB section mixture reaction section from bottom to top, when the smoldering disposal method works, a packed bed material is placed in the mixture reaction section, air is introduced from the lower end, so that organic solid waste in the packed bed material is subjected to smoldering reaction, and is treated, but combustible gas components such as carbon monoxide and the like in discharged flue gas are high, and the combustible gas components are discharged into the atmosphere after being purified.
In order to solve the problem, an embodiment of the present invention provides a self-sustaining smoldering disposal method for organic solid waste based on catalytic oxidation in a furnace, where the organic solid waste refers to high-water-content low-calorific-value organic solid waste with a water content of not less than 80%, and as shown in fig. 1, the method includes the following steps:
replacing partial porous medium materials with catalysts to serve as mixed packed bed material components in the smoldering furnace, namely mixing and uniformly stirring organic solid wastes, the porous medium materials and the catalysts, and taking the mixture as the packed bed material in the smoldering furnace; and then the heating device starts to heat, when the temperature of the bottom layer of the packed bed material reaches 250-300 ℃, air starts to be introduced into the smoldering furnace, the heating is closed after air supply is carried out for 10-30 min, and air supply is continued until the treatment of all the packed bed material in the furnace is finished.
In the treatment process, the smoldering furnace is subjected to smoldering, pyrolysis and drying from bottom to top, wherein carbon monoxide, alkane, alkene, alkyne and small molecular organic gas compounds are inevitably generated in the organic solid waste smoldering and pyrolysis processes under the process condition, and after the catalyst is added, unburnt flue gas generated by the smoldering reaction can assist the unburnt flue gas to further perform oxidation reaction with residual oxygen (the oxygen content is 12-19%) in the flue gas in a pyrolysis reaction layer at the temperature of 300-500 ℃ when passing through the pyrolysis reaction layer on the smoldering reaction surface, so that the waste gas content of the smoldering reaction is reduced, and the smoldering treatment of the organic solid waste is completed.
Further, the Darcy flow velocity of air introduced into the smoldering furnace is 3-5 cm/s.
Furthermore, the mass part ratio of the porous medium material, the organic solid waste and the catalyst in the mixture is 33.3-81.4: 14.3-20: 4.1-51.4, and comprehensive evaluation needs to be carried out in combination with treatment requirements and economic cost in the actual use process.
Preferably, the catalyst is a platinum-supported catalyst, a cerium oxide-supported catalyst, a zirconium oxide-supported catalyst, a manganese cobalt catalyst or a copper dichromate catalyst, and more preferably a manganese cobalt catalyst supported on diatomaceous earth or alumina particles.
Preferably, the particle size of the catalyst is 0.5 mm-2 mm; the porous medium material is spherical, spheroidal or cube-shaped particles with the particle size of less than 2mm, and is further preferably spheroidal particles with the particle size of 0.5 mm-1.2 mm.
The following are specific examples:
example 1
Treating municipal sludge with water content of 80% by using a smoldering device, uniformly mixing the sludge, sand and platinum-loaded catalyst (with particle size of 1-2 mm) in a mixing proportion of 20%, 76% and 4% through physical stirring, feeding the mixture into the smoldering reaction device through a feeder after mixing, then starting heating, starting air supply when the temperature of the mixed material at the bottommost layer reaches 250 ℃, wherein the air flow rate in the furnace is 3.5cm/s, closing heating after about 20min of air supply, and continuously supplying air until the treatment of all the filling materials in the furnace is finished, namely the temperature of the topmost layer of the filling materials in the furnace reaches more than 350 ℃. By adding the catalyst, the concentration of carbon monoxide in the flue gas can be reduced by about 78%, and the smoldering reaction rate can be increased by about 18%.
Example 2
Treating municipal sludge with water content of 80% by using a smoldering device, physically stirring and uniformly mixing sludge, sand and a manganese-cobalt catalyst (with particle size of 0.5 mm-1 mm) loaded on diatomite or alumina particles according to a mixing ratio of 14.3%, 81.4% and 4.3%, feeding the mixture into a smoldering reaction device through a feeder after mixing, starting heating, starting air supply when the temperature of the mixed material at the bottommost layer reaches 280 ℃, stopping heating after air supply is carried out for about 10min, and continuously supplying air until the treatment of all filling materials in the furnace is finished, namely the temperature of the topmost layer of the filling materials in the furnace reaches more than 350 ℃. By adding the catalyst, the concentration of carbon monoxide in the flue gas can be reduced by about 65%, and the smoldering reaction rate can be increased by about 13%.
Example 3
Treating municipal sludge with the water content of 90% by using a smoldering device, uniformly mixing the sludge, sawdust, sand and a copper dichromate catalyst (with the particle size of 0.5-1.2 mm) in a mixing proportion of 16%, 4%, 60% and 20% by physical stirring, feeding the mixture into a smoldering reaction device by using a feeder after mixing, then starting heating, starting air supply when the temperature of the mixed material at the bottommost layer reaches 300 ℃, wherein the air flow velocity in the furnace is 3.0cm/s, closing heating after the air supply is about 30min, and continuously supplying air until the treatment of all the filling materials in the furnace is finished, namely the temperature at the topmost layer of the filling materials in the furnace reaches more than 350 ℃. By adding the catalyst, the concentration of carbon monoxide in the flue gas can be reduced by about 76%, and the smoldering reaction rate can be increased by about 15%.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.