CN110470141A - It is a kind of to utilize semi-coke harmless treatment garbage flying ash apparatus and method - Google Patents

Abstract

A device and method for the harmless treatment of garbage fly ash using semi-coke. The mixture of semi-coke and garbage fly ash is put into a high-temperature melting pool where semi-coke is accumulated for melting and solidification, so as to realize the reduction of heavy metals and the decomposition of dioxins; high-temperature melting furnace Using graded air distribution technology, most of the pure oxygen is introduced into the semi-molten layer through the air inlet to realize low NOx clean combustion and heavy metal reduction in the reducing atmosphere in the molten pool; the remaining pure oxygen is introduced into the upper part of the melting furnace through the exhaust air nozzle, Oxidation eliminates CO, avoids the escape of toxic gases, and maintains a uniform temperature in the furnace. The use of the device and method of the present invention can realize the harmless, resourceful, and reduction treatment of fly ash, and avoid secondary pollution; the clean fuel characteristics and low price of semi-coke also solve the economic problem of fly ash melting treatment, which is beneficial to fly ash. The ash melting treatment method was further popularized and applied.

Description

A device and method for harmlessly treating garbage fly ash using semi-coke

technical field

The invention relates to the technical field of garbage incineration fly ash treatment, in particular to a device and method for harmlessly treating garbage fly ash by using blue charcoal.

Background technique

Garbage incineration is an important means of disposal of municipal solid waste, and the resulting fly ash brings problems in disposal. The main components of waste incineration fly ash are acidic oxides such as SiO ₂ and Al ₂ O ₃ , basic oxides such as CaO, MgO, and Fe ₂ O ₃ , and a large number of toxic and harmful substances, including highly toxic substances such as dioxins and heavy metals. Pb, Cr, Cd, Hg, Zn, etc. my country's latest 2016 edition of the "National Hazardous Waste List" includes waste incineration fly ash as "HW18 Incineration Disposal Residues", which cannot enter the landfill without special treatment. At present, the harmless treatment methods of fly ash mainly include sintering and melting technology, solidification technology, chemical agent stabilization technology and separation and extraction technology. Among them, sintering and melting technology uses higher temperature to digest highly toxic organic pollutants in fly ash, and at the same time has a high degree of reduction and a large proportion of volume reduction, which is a relatively advanced treatment method.

Fly ash high-temperature melting equipment generally uses surface melting furnaces, electric arc melting furnaces, plasma melting furnaces and cyclone furnaces. When the waste incineration fly ash is heated to the melting temperature of the fly ash, the organic matter such as dioxin in the fly ash is decomposed and destroyed by heat. Fe, Ca, Al, Zn, Mn, Cr and other low-volatility metals are transferred to the slag during the melting process. The molten fly ash is divided into a semi-molten layer suspended on the upper part of the melting pool and a molten layer deposited on the bottom of the high-temperature melting pool by density classification, and the slag is cooled and recovered for resource utilization. When the furnace is in an oxidizing atmosphere, the trivalent chromium in the heavy metal is completely transformed into hexavalent chromium, which is harmful to the environment and is not allowed to exist in the environmental protection standard. Therefore, it is necessary to add coal as a reducing agent to generate a reducing atmosphere at high temperature to provide conditions for the reduction and detoxification of heavy metals. After harmless treatment in a high-temperature reducing atmosphere, the relatively low-density slag (main components SiO ₂ , Al ₂ O ₃ and CaO, etc.) can be used as raw materials for making insulation cotton and cement after cooling and recovery, while the high-density metal (Fe , Zn and Cr, etc.) are deposited at the bottom of the high-temperature melting furnace for recycling.

However, the existing waste incineration fly ash treatment technology uses coal to generate a reducing atmosphere, which has the following problems: (1) The coal used in the high-temperature melting furnace releases NOx and SO ₂ into the flue gas during the combustion process, and the emission concentration is higher than the national standard . (2) In the process of melting waste fly ash, there may be residual dioxins and heavy metals that need secondary treatment, increasing system investment. (3) Melting treatment of waste fly ash has high energy consumption, low energy utilization rate, extremely high construction and operation costs, and it is difficult to implement industrialization.

Contents of the invention

In order to overcome the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a device and method for harmlessly treating garbage fly ash utilizing blue charcoal, effectively decomposing dioxins through a high-temperature melting furnace, and reducing NOx and Heavy metals are reduced while SO ₂ is discharged, which is convenient for final disposal and resource utilization in the next step.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A device for harmlessly treating garbage fly ash by using semi-coke, comprising a melting furnace 3, a feed port 1 is arranged on the top of the melting furnace 3, an overburning air nozzle 2 is arranged on the side of the upper part of the melting furnace 3, and two sides of the lower part of the melting furnace 3 are arranged There is an air inlet 4, a slag outlet 6 is provided at the lower part of the melting furnace 3 located on the other side of the overburning air nozzle 2, and a melting pool 5 is provided at the bottom of the melting furnace 3.

The pure oxygen inlet 4 is set at 1/6 of the furnace body height of the high temperature melting furnace 3 .

The fly ash and slag in the melting pool 5 can be divided into a semi-molten layer with a lower density and a molten layer with a higher density, and the slag outlet 6 is arranged at the molten layer with a higher density.

A method for harmlessly treating garbage fly ash by using semi-coke, comprising the following steps;

The waste fly ash produced in the waste incineration plant is mixed with semi-coke in the mixer and processed into shape. It falls from the top of the melting furnace 3 into the melting pool 5 at the bottom. Decomposition of oxins; pure oxygen is introduced into the high-temperature melting furnace 3 to react with semi-coke; the furnace adopts graded air distribution technology, and a pure oxygen inlet 4 is set at 1/6 of the height of the high-temperature melting furnace 3 to feed most of the Pure oxygen reaches the semi-molten layer to realize clean combustion with low NOx in the reducing atmosphere in the molten pool; the remaining pure oxygen is passed into the upper part of the melting furnace through the burn-off air nozzle 2 to oxidize and eliminate CO to avoid the diffusion and escape of toxic gases, and at the same time keep the furnace temperature uniform 1400-1500°C; the melting pool 5 acts as a high-temperature heat storage body, melting and solidifying the molded waste fly ash falling into the pool, and decomposing dioxins, so as to realize the harmless, resourceful and reduction treatment of fly ash.

The fly ash and slag in the molten pool 5 can be divided into a semi-molten layer with a lower density (mainly composed of SiO ₂ , Al ₂ O ₃ , CaO, newly dropped fly ash and blue carbon, etc.) and a higher-density molten layer. (Fe, Zn and Cr, etc.), discharged from the slag outlet 6 to facilitate the final disposal and resource utilization in the next step.

The high-temperature melting furnace 3 is fed with pure oxygen and semi-coke according to a ratio of 1 to 1.8m ³ /kg of pure oxygen and semi-coke to react; the upper part of the melting furnace 3 is provided with an exhaust air nozzle 2 to burn and consume incomplete products, and The furnace temperature of the melting furnace 3 is kept uniformly at 1400-1500°C.

The high-temperature melting furnace 3 is any one of high-temperature equipment such as a surface melting furnace, a cyclone furnace, or an ironmaking blast furnace.

The air inlet 4 can also pass through gas such as air that can carry out oxidation reaction with semi-coke except pure oxygen, and the amount of intake air can be adjusted with the atmosphere.

The number of slag outlets 6 can be adjusted according to different molten layers, which is convenient for subsequent resource utilization.

Beneficial effects of the present invention:

The invention provides a device and a method for treating garbage fly ash in large quantities by using blue charcoal for harmless treatment of garbage fly ash. Under the high temperature and reducing atmosphere in the melting furnace, the dioxins contained in the garbage fly ash are decomposed and destroyed, and the heavy metals are reduced into the slag, and finally a harmless slag is obtained, which is environmentally friendly and does not need to be landfilled. Harmless, resourceful, and reduced utilization of incineration fly ash.

As a clean fuel, semi-coke has lower NOx and SO ₂ emissions than bituminous coal, and its price is lower than that of heating fuels such as natural gas and oil, which reduces operating costs.

The introduction of pure oxygen into the air inlet can greatly improve the combustion efficiency of blue charcoal in the melting furnace, ensure the high temperature environment in the furnace, and at the same time prevent the _N2 in the air from being oxidized to generate thermal NOx at high temperature.

The staged air distribution technology in the high-temperature melting furnace not only inhibits the formation of thermal NOx in the furnace, but also reduces the reduction products (such as NH ₃ and HCN) produced by incomplete combustion, which will reduce and crack the formed NOx, thereby inhibiting the formation of fuel-type NOx. While streamlining the desulfurization and denitrification devices, the flexibility of adjusting the temperature and atmosphere of the high-temperature melting furnace is improved.

Description of drawings

Fig. 1 is a schematic diagram of a device for harmlessly treating garbage fly ash using semi-coke described in the examples of the present invention.

Among them, 1 is the feed inlet, 2 is the overburning air nozzle, 3 is the melting furnace, 4 is the air inlet, 5 is the melting pool, and 6 is the slag outlet.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, it is a device for the harmless treatment of garbage fly ash using semi-coke. The invention of the medium-high temperature melting furnace can be used for large-scale harmless treatment of garbage fly ash, and at the same time realizes reliable and economical recycling of garbage fly ash. The device includes a semi-coke garbage fly ash mixture feed port 1, an air inlet 4 that feeds most of the pure oxygen for the incomplete combustion of the semi-coke, and a burn-off air nozzle 2 that feeds a small part of the remaining pure oxygen; the semi-coke fly The ash mixture falls into the melting pool 5 at the bottom of the high-temperature melting furnace 3 to melt and solidify, and finally produces slag and is discharged from the slag outlet 6; before the high-temperature melting furnace is opened, a sufficient amount of semi-coke is piled up in the furnace to provide enough heat energy for the melting pool to heat up. Reach the temperature requirements for the melting treatment of garbage fly ash; the appropriate size of the melting furnace 3 and the melting pool 5 in the furnace ensures that the blue-coke fly ash mixture in the melting pool fully reacts under the reducing atmosphere.

In the method, the mixture of semi-coke and garbage fly ash is dropped into the bottom melting pool 5 through the high-temperature melting furnace 3 feed port 1 to melt and solidify, so as to realize the reduction of heavy metals and the decomposition of dioxin; most of the pure oxygen is passed through the air inlet 4 Into the semi-molten layer, the remaining pure oxygen is passed into the upper part of the melting furnace through the overburning air nozzle 2 to oxidize and eliminate CO, avoid the escape of toxic gases, and maintain uniform temperature in the furnace; the slag in the melting furnace 3 is discharged from the slag outlet 6.

The homogeneous mixture of the garbage fly ash and semi-coke falls from the top of the melting furnace 3 into the melting pool 5 at the bottom, and penetrates into the interior of the melting pool 5 under the action of gravity. , to achieve heavy metal reduction.

The high-temperature melting furnace ³ adopts graded air distribution technology, and a pure oxygen inlet is set at 1/6 of the height of the high-temperature melting furnace body. Charcoal reaction realizes clean combustion with low NOx under reducing atmosphere in the melting pool; the overburning air nozzle 2 is set in the middle and upper part of the melting furnace to burn and consume incomplete products, and keep the furnace temperature uniformly at 1400-1500 °C.

The melting pool 5 acts as a high-temperature heat storage body, melting and solidifying the molded garbage fly ash falling into the pool, and decomposing dioxins, so as to realize the harmless, resourceful and reduction treatment of fly ash.

The present invention enters in the blast furnace and calculates as follows to fly ash blue charcoal mixture:

According to the analysis of the semi-coke industry, it can be known that the fixed carbon content is high (80.4%), the ash content (11.57%) and the volatile matter (7.99%) content are low, the calorific value is high (26.87MJ.kg), and the sulfur content is only 0.36%. Other bituminous coal or anthracite is a clean fuel, so the amount of NOx and SO ₂ in the combustion products is much lower than that of some coal types. In the high-temperature melting furnace, blue carbon reacts with pure oxygen at high temperature to produce CO (reaction formula 1). The reducing atmosphere not only detoxifies the molten heavy metals, but also reduces the generated NOx to N ₂ . Because the fixed carbon content of semi-coke is extremely high, assuming that only fixed carbon and _O2 oxidation reaction in semi-coke, other components are ignored, then 0.8kg C contained in 1kg semi-coke needs about 1.1kg of _O2 mass to generate pure CO, The corresponding volume of O ₂ at normal temperature is 0.81m ³ (the density of O ₂ at 20°C under normal pressure is 1.32kg/m ³ ), that is, the minimum consumption of O ₂ corresponding to 1kg of blue carbon is 0.81m ³ . However, considering the loss and dissipation of oxygen during the transportation process, the reaction of other components of semi-coke itself with oxygen, and the need for working condition adjustment, the actual pure oxygen consumption is much higher than the calculated value. According to the present invention, the ratio of pure oxygen to semi-coke is 1-1.8m ³ /kg to feed pure oxygen.

C+0.5O ₂ →CO (1)

The invention utilizes the semi-coke as the raw material for the fly ash treatment of the high-temperature melting furnace. Semicoke is a carbonaceous product with low volatile content obtained by dry distillation and pyrolysis of non-viscous or weakly viscous high-volatile bituminous coal at low temperature. Semi-coke has the characteristics of low volatility (<7%), low sulfur content (<0.5%), low ash content (<10%), and high calorific value (>25MJ). As an environmentally friendly fuel, semi-coal NOx and SO ₂ emissions are lower than bituminous coal and some anthracite. At the same time, the price of semi-coke is low, which has a competitive advantage compared with the fuel oil and natural gas used in high-temperature melting furnaces. The present invention rationally designs a device for harmless treatment of garbage fly ash, utilizes semi-coke and fly ash mixed incompletely to burn to generate a reducing atmosphere, realizes reduction of heavy metals and reduction of NOx and _SO2 emissions, reduces construction and operation costs, and achieves fly ash harmlessness recycling, recycling, and reduction.

The present invention utilizes blue charcoal harmless treatment garbage fly ash method, specifically as follows:

The waste fly ash produced in the waste incineration plant is mixed with semi-coke in a mixer according to a certain proportion and processed into a shape. It falls from the top of the melting furnace 3 into the melting pool 5 at the bottom, and goes deep into the melting pool 5 under the action of gravity for melting and solidification to realize Reduction and decomposition of dioxin; high temperature melting furnace 3 is fed with pure oxygen and semi-coke according to the ratio of pure oxygen and semi-coke at 1-1.8m ³ /kg; The pure oxygen inlet 4 is set at 1/6 of the body height to feed most of the pure oxygen to the semi-molten layer, so as to realize the low NOx clean combustion in the reducing atmosphere in the molten pool; Oxidation eliminates CO to avoid the diffusion and escape of toxic gases, and at the same time keeps the furnace temperature uniform at 1400-1500°C; the melting pool 5 acts as a high-temperature heat storage body, melting and solidifying the molded waste fly ash falling into the pool, and decomposing dioxins , to realize the harmless, resourceful and reduction treatment of fly ash. The fly ash and slag in the molten pool 5 can be divided into a semi-molten layer with a lower density (main components SiO ₂ , Al ₂ O ₃ , CaO, newly dropped fly ash and blue carbon, etc.) and a higher-density molten layer (Fe, Zn and Cr, etc.) are discharged from the slag outlet 6 to facilitate the final disposal and resource utilization in the next step.

The high-temperature melting furnace 3 can be high-temperature equipment such as a surface melting furnace, a cyclone furnace, and an ironmaking blast furnace.

In addition to pure oxygen, the air inlet can also pass through air and other gases that can undergo oxidation reactions with semi-coke, and the amount of air intake can be adjusted with the atmosphere;

The number of slag outlets 6 can be adjusted according to different molten layers, which is convenient for subsequent resource utilization.

Claims (9)

1. A device for harmless treatment of waste fly ash utilizing blue charcoal, characterized in that it comprises a melting furnace (3), the top of the melting furnace (3) is provided with a feed inlet (1), and the upper side of the melting furnace (3) is provided with There is an overburning air spout (2), an air inlet (4) is arranged on both sides of the lower part of the melting furnace (3), and a slag outlet ( 6), the bottom of the melting furnace (3) is provided with a melting pool (5). 2. The device according to claim 1, characterized in that, the pure oxygen inlet (4) is arranged at a furnace body height of 1 /6. 3. A kind of device according to claim 1, characterized in that, the bottom of the melting pool (5) is fly ash slag, and the fly ash slag can be divided into A semi-molten layer with a lower density and a molten layer with a higher density, and the slag outlet (6) is arranged at the molten layer with a higher density. 4. A method utilizing blue charcoal to detoxify garbage fly ash, characterized in that it comprises the following steps; The waste fly ash produced in the waste incineration plant is mixed with semi-coke in the mixer and processed into shape, and falls from the top of the melting furnace (3) into the melting pool (5) at the bottom, and goes deep into the melting pool (5) to melt and solidify under the action of gravity , to achieve heavy metal reduction and dioxin decomposition; high-temperature melting furnace (3) is introduced into pure oxygen to react with semi-coke; the furnace adopts graded air distribution technology, and is set at 1/6 of the height of the high-temperature melting furnace (3) The pure oxygen inlet (4) feeds most of the pure oxygen into the semi-molten layer to realize clean combustion with low NOx in the reducing atmosphere in the molten pool; the remaining pure oxygen is fed into the upper part of the melting furnace through the burn-off air nozzle (2) to oxidize and eliminate CO To avoid the diffusion and escape of toxic gas; the melting pool (5) acts as a high-temperature heat storage body, melts and solidifies molded garbage fly ash falling into the pool, and decomposes dioxins. 5. a kind of method utilizing blue charcoal harmless treatment garbage fly ash according to claim 4, it is characterized in that, fly ash slag can be divided into density lower semi-molten layer in the described fusion pool (5) The molten layer with higher density is discharged from the slag outlet (6) to facilitate final disposal and resource utilization in the next step. 6. A method of using semi-coke to harmlessly treat garbage fly ash according to claim 4, characterized in that, the high-temperature melting furnace ( ³ ) is 1 to 1.8m according to the ratio of pure oxygen and semi-coke Feed in pure oxygen per kg to react with semi-coke; the upper part of the melting furnace (3) is provided with an overburning air nozzle (2) to burn and consume incomplete products, and keep the furnace temperature of the melting furnace (3) evenly at 1400-1500 °C. 7. A kind of method utilizing blue charcoal harmless treatment garbage fly ash according to claim 4, is characterized in that, described high-temperature melting furnace (3) is any high-temperature equipment of surface melting furnace, cyclone furnace, ironmaking blast furnace A sort of. 8. A kind of method that utilizes blue charcoal harmless treatment garbage fly ash according to claim 4, is characterized in that, described air inlet (4) also can pass through air etc. except pure oxygen and can carry out with blue charcoal Oxidation reaction gas, the intake volume is adjusted with the atmosphere. 9. A method for harmlessly treating garbage fly ash by using semi-coke according to claim 4, characterized in that the number of the slag outlets (6) can be adjusted according to the difference of the molten layer, which is convenient for subsequent resource utilization .