JPH10281411A - Combustion of emulsion oxygen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in view of the exigencies of the times, an effective means for bringing to naught the hazardous substances, such as dioxin, in the emission from an incinerator. SOLUTION: Mixed fuel of water and oil prepared as a gas with oxygen concentration of 21% or more is burnt. Although pure oxygen combustion of fuel has advantages that nitrogen oxides are close to naught, exhaust gas is lessened drastically, and so forth, the fact that there is no refractory brick resisting a high temperature of 2,800 deg.C has left the idea impracticable. Now by adjusting the water content in an emulsion fuel the heating value can freely be adjusted and the temperature, controlled so that the pure oxygen combustion of fuel can be applied easily to an incinerator, etc. The emission of dioxin and nitrogen oxides from the uncinerator can be reduced to virtually naught. Since fusion treatment of ash becomes practicable in the manner of the high- temperature treatment, complete seal of heavy metal and no separation from its solution become possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION As the environmental problems become more serious, the superiority of emulsion fuels in which water and oil are mixed is being reexamined. By burning this emulsion fuel with pure oxygen instead of air, nitrogen oxides and dioxins discharged from the incinerator can be significantly reduced. Complete incineration of fly ash and fly ash by high temperature flame of pure oxygen combustion,
Other efforts include improving fuel efficiency of diesel engines and reducing carbon monoxide and nitrogen oxides.

[0002]

2. Description of the Related Art The principle of incinerators is air combustion. Four-fifths of the air is nitrogen. For this purpose, nitrogen oxides are discharged. In order to suppress the generation of dioxin, it is considered that high temperature, residence time in a furnace, and stirring by turbulent flow conditions are conditions. Even if you keep this, it is difficult to reduce dioxin to zero. A large amount of exhaust gas makes exhaust gas treatment difficult. Also, increase equipment costs. Although indirect heating has also been tried experimentally, it is difficult at present to treat a large amount of waste due to a small amount of treatment. The incineration ash from the incinerator is required to prevent the elution of heavy metals. Melt processing is common, but no technology has been completed. Although plasma is said to be good, plasma currently used does not solve the problem. It is difficult to maintain a high temperature stably with combustion plasma.
Complete vitrification of the ash is not possible due to the low temperature.

[0003]

SUMMARY OF THE INVENTION The problems with the current incinerator described above, (1) the occurrence of diokin is suppressed.
(2) Eliminate nitrogen oxides. (3) Increase thermal efficiency.
(4) To solve the complete vitreous treatment of incinerated ash and fly ash. In addition, the high temperature associated with oxyfuel combustion shortens the life of the brick. Reduce exhaust gas treatment equipment costs and operating costs. In addition, it will improve fuel efficiency of diesel engines and reduce carbon monoxide and nitrogen oxide emissions.

[0004]

An emulsion state is a typical example of a state in which water and oil are mixed. A state in which water is mixed at 50% or more is considered to be a colloidal state different from this emulsion state. In the present invention, the term “emulsion” hereinafter refers to a mixed fuel of water and oil, including a colloidal state having a water content of 50% or more. Use the emulsion as fuel. Further, the combustion temperature is increased by using oxygen instead of ordinary secondary air. The combustion temperature can be freely adjusted by controlling the water content. Significantly reduce exhaust gas volume. By using the emulsified light oil as fuel, it is possible to improve the fuel efficiency and exhaust gas of the diesel engine in question.

[0005]

[Action and Examples] In order not to generate dioxin,
To raise the temperature inside the furnace and completely decompose chlorine-based organic matter. In the case of air combustion, it does not increase because four-fifths are nitrogen and the average calorific value of urban garbage is as low as 2000 kcal. The incineration temperature is around 800 to 1000 degrees. To maintain the furnace temperature at this temperature, auxiliary combustion with heavy oil or the like may be necessary. A waste heat boiler is usually installed after the incinerator to recover the thermal energy of the temperature of the exhaust gas. When the thermal energy of the exhaust gas is recovered by secondary air preheating, the concentration of nitrogen oxides in the exhaust gas increases.

[0006] The use of oxygen instead of the combustion air of an incinerator substantially eliminates nitrogen oxides. Further, the chlorine-based organic matter is completely decomposed because the temperature in the furnace increases. Since the amount of radiated heat transfer increases as a whole, the thermal efficiency increases. Exhaust gas loss is greatly reduced. Overall, the thermal efficiency is considered to exceed 65%. Since the amount of exhaust gas is reduced to about one-fifth, the size of the venturi clubber, bag filter, and dust collector is also reduced. Equipment costs and operating costs can be significantly reduced.

When the amount of exhaust gas is reduced to one fifth, the amount of fly ash carried over is greatly reduced. As a result, ash disposal costs are reduced. Dioxin is often contained in fly ash. This is due to the catalytic action of the oxide during the cooling process. Reduction of fly ash will reduce the production of diokin itself. The dioxin concentration discharged from the incinerator is as small as 0-1 ng in the incineration ash. In particular, the amount of dioxin in the cooling process becomes apparent because the amount is small during continuous operation.

In order to prevent the generation of dioxin, it is necessary to prevent incomplete combustion, suppress the production of carbon monoxide, and reduce the concentration. Oxygen combustion does not produce carbon monoxide. In oxyfuel combustion, combustion is uniform. With the required amount of oxygen, incomplete combustion does not occur. In the case of an incinerator, dioxin becomes almost zero when complete combustion and staying in a temperature of 900 ° C. or more for 2 seconds or more. According to the data, it occurs in large quantities at start and stop.
This proves that complete combustion and a temperature of 900 ° C. or more are required.

In the case of pure oxygen combustion, the maximum temperature rises to 2800 degrees. Above 1800 degrees, there is no refractory brick. This is one of the reasons why pure oxygen combustion was not used, despite the obvious advantages. In the case of an incinerator, the average calorific value of municipal waste is 2000 Kcal / k
g, so the temperature is not so high. moisture%
Is relatively high, which also lowers the combustion temperature. If the furnace temperature rises, an appropriate amount of steam (mist) may be added together with oxygen. Water splitting is an endothermic reaction and also increases the amount of exhaust gas, so it is effective in lowering the temperature.

When the emulsion is used as fuel, the problem of combustion temperature can be easily solved. The heat value of the emulsion fuel decreases with the percentage of moisture. This moisture readily decomposes at temperatures above 800 degrees and where carbon atoms are present. Since water splitting is an endothermic reaction, the combustion temperature drops. However, the energy of the emulsion is not negative in terms of energy. The produced oxygen combines with carbon and the hydrogen combines with oxygen to generate heat. The averaging of the combustion temperature and the increase in the amount of combustion gas lower the combustion temperature.

In the treatment of incinerated ash and fly ash, vitrification is required as a condition of landfill so that heavy metals and the like contained therein are not eluted. There is an urgent need to develop a vitrification method using high temperatures. The emulsion fuel plus oxyfuel combustion of the present invention meets this need. The maximum temperature of pure oxygen combustion is 2700-2800 degrees, and the chlorine-based organic matter in the incineration ash is completely decomposed. However, it is too high considering the refractory brick of the furnace. Reducing this temperature is difficult with ordinary fuels. If it is an emulsion fuel, the temperature of oxyfuel combustion can be adjusted. The inventor has developed a stable emulsion fuel and is in a position to take full advantage of its advantages. As described above, the combustion temperature is adjusted to a temperature sufficient for dissolving incineration ash and fly ash by adjusting the water content to a temperature that the refractory brick has. He invented an incinerator that burns emulsion fuel with oxygen, and a melting furnace for incinerated ash and fly ash.

For melting of incineration ash and fly ash, arc melting, plasma melting and combustion methods have been developed and tested. Both are not perfect and have many problems. The temperature is low. It is unstable. Processing costs are high. Mass processing is not possible. Emulsion fuel plus oxyfuel combustion can completely solve this problem. The cost is less than half that of using electricity. Mass processing is possible. Dioxin is not contained in exhaust gas. Because high-temperature treatment can be performed, heavy metals do not elute. High melting temperature results in large weight loss.

When the emulsion fuel is burned with oxygen,
There is almost no nitrogen oxides in the combustion gas. The main constituent elements are carbon, oxygen and hydrogen. When the emulsion fuel is blown into the furnace, it starts heating and gasifying depending on the furnace temperature. At the same time, the water droplets of the fine particles are also heated, exploding with steam at a certain temperature, and making the oil particles fine. This promotes oil evaporation and gasification. Proceed with uniform dispersion, mixing, decomposition, carbonization and combustion. Water molecules break down into oxygen and hydrogen. This oxygen is
Combines with adjacent carbon and burns to carbon dioxide. The remaining hydrogen is blown and combines with oxygen to form water. In a state where the amount of oxygen is small, a reducing atmosphere in which hydrogen exists is formed. Oxygen generated by water splitting is bonded to carbon generated by splitting oil, and hydrogen is bonded to oxygen, and the generated heat is not negative.

In order to make it easy, the calorific value of kerosene should be 10
000 Kcal / Kg. The calorific value of 1 kg of the 15% moisture emulsion is 8500 Kcal. Water 0.1
The amount of heat required to decompose 5 Kg is 225 Kcal, and the amount of heat generated by burning the generated hydrogen is 528 Kcal, which is a plus value. Water becomes fuel. However, this is conditional. When the furnace temperature is 800 ° C. or higher, oxygen generated by decomposition of water is combined with carbon first and burns, only carbon dioxide is generated, there is sufficient oxygen, and water does not decompose without carbon.

C + O 2 = CO 2 H 2 + 1 / 2O 2 = H 2 O Since hydrogen and oxygen have a strong binding force, they completely burn even if the amount of surplus oxygen is small. Low oxygen combustion becomes possible. In the case of normal combustion, the oxygen concentration in the exhaust gas is about 7%. However, in the case of emulsion combustion, this oxygen concentration can be reduced to 1%. The amount of exhaust gas can be reduced. Emulsion fuel is also effective in normal air combustion.

When an emulsion fuel is used in an internal combustion engine, a great improvement in fuel efficiency can be achieved. Light oil was used as an emulsion with 15% moisture, and it was supplied to diesel vehicles to check the driving status and to confirm the improvement in fuel efficiency. The used truck is 10t
It is a diesel car. It was 3.2 kilometers per liter of emulsion. In the case of ordinary light oil, it is 112.9 km. As is evident from the result, it is improved by 25% in terms of light oil. Further, what is better is that the concentration of carbon monoxide in the exhaust gas has been greatly improved to 0.3%.

When water is optically decomposed by the action of infrared rays or visible light produced by carbon, the decomposition energy has an experimental value smaller than the theoretical value. In particular, it often occurs when the emulsion is burned with oxygen.

Suppose kerosene is used to melt the ash. In the case of air combustion, the temperature may not be sufficient depending on the nature of the ash. When burning with oxygen, flame temperature will be 2
It rises to 800 degrees. No refractory brick can withstand this temperature. However, if the fuel is made into an emulsion, the temperature easily drops below 1800 degrees. At a burning temperature of 1800 degrees, the refractory brick currently in use is sufficient. Oxygen combustion takes advantage of its many advantages by combining it with an emulsion fuel. The problem with oxyfuel combustion is that the cost of oxygen is high, but overall the cost is lower than air combustion. Thermal efficiency becomes 65% or more. Exhaust gas treatment equipment costs and operating costs can be reduced. Fly ash is reduced. There is almost no generation of dioxin. Complete incineration ash can be made into glass. In general, even if you pay 10-40 yen / cubic meter for oxygen, you pay enough.

This oxyfuel combustion method can also be used for burning pulverized coal slurry. This pulverized coal slurry is also a kind of emulsion. It can be used for boilers by adjusting the water content. Nitrogen oxides can be significantly reduced if used in power plants. Moisture does not cause energy loss, and there is a possibility that power generation can be increased if conditions are set.

The oxygen generator may be a molecular sieve type or an adiabatic expansion type. If oxygen and nitrogen are generated simultaneously, the adiabatic expansion type is more convenient. The generated nitrogen is used as a heating medium. Increasing the oxygen purity lowers the efficiency of the oxygen generator and increases the oxygen cost. For the purpose of reducing the amount of exhaust gas and the amount of nitrogen oxides, oxygen does not need to be 95% or more pure. Even at about 60%, there is a sufficient reduction effect.

FIG. 1 shows a reflection type incineration ash melting furnace. For example, an emulsion fuel of heavy fuel oil C and 30% moisture is supplied to the burner 1 that burns the emulsion with oxygen. To burn the emulsion, a gas of 100% oxygen is supplied. The flow rate of oxygen is slightly higher than the theoretical oxygen amount. The inner surface of the reverberatory furnace 2 has a brick with fire resistance. The incineration ash 6 is continuously supplied to the gap between the reverberatory furnace 2 and the rotary furnace 3 by the screw feeder 5. As the rotary furnace 3 rotates, the incineration ash 6 slides down into the reverberatory furnace 2. There, the burner 1 is melted by the high-temperature flame blown out. Since the reverberatory furnace 2 is thermally insulated from the incineration ash 6 and the refractory brick, the inside of the furnace is maintained at a high temperature. The melted incineration ash 6 flows down the slope of the rotary furnace 3. The molten incineration ash 6 serves to protect the refractory heat insulating material of the rotary furnace 3. The incinerated ash 6 heated by the high-temperature flame of the emulsion oxyfuel combustion and having flowability is dropped into the ladle 8 after the flow rate is adjusted by the gate 7. The exhaust gas passes through a flue 9 to an exhaust gas treatment device. In oxyfuel combustion, the amount of exhaust gas is 1/5
And the processing equipment becomes smaller. Almost no nitrogen oxides. If the supplied oxygen amount is smaller than the theoretical value, hydrogen remains and the inside of the furnace becomes reductive. Dioxin is reductively decomposed.

When oxygen is generated in an air separation device separated by an adiabatic expansion method, a large amount of nitrogen can be obtained at the same time. This nitrogen can be used as a medium for indirect heating. The indirect heating method includes a complete indirect heating method and a direct heating method. Complete indirect heating uses nitrogen generated from the air separator. Heat nitrogen to around 650 degrees. This nitrogen is passed through a heating pipe and heated indirectly to decompose waste. The waste gasifies and carbonizes. This exhaust gas undergoes oxyfuel combustion in a high-temperature combustion furnace.

FIG. 2 is a conceptual diagram of a complete indirect heating incinerator. The hopper 21 receives the municipal waste 20 crushed to an appropriate size from the storage hopper. The screw feeder 22 is for supplying the municipal waste 20 to the rotary furnace 23. The driving device 24 rotates the rotary furnace 23. The municipal waste 20 is indirectly thermally decomposed in the rotary furnace 23, and is gasified and carbonized. This exhaust gas is supplied to the melting furnace 29 and is subjected to oxygen combustion. The carbonized carbon residue is discharged from a discharge mechanism 25 and carried to a screen 27 by a conveyor 26. The screen 27 sorts carbon carbide residues. Metal, glass, stone, etc. are taken out, and the remaining carbon residue is used as a fuel in the melting furnace 29. The carbon residue is sent from tank 28. The slag pit 30 collects the molten slag from the melting furnace 29.
The high temperature of the oxyfuel combustion results in a glass in which the metal elutes. The boiler 31 is a radiation boiler and recovers waste heat as steam. This steam is converted into electric power in the power generation facility 32. Dust from the dust collector 33 and the boiler 31 is sent to the melting furnace 29 by gas transport with nitrogen and blown into the furnace. The oxygen concentration in the melting furnace 29 is continuously monitored and controlled. The oxygen generated by the air separator 34 is used for oxygen combustion in the melting furnace 29. Nitrogen is used as a medium for indirect heating. The nitrogen is heated by the heat exchanger 36 to about 650 degrees. The garbage is indirectly thermally decomposed by passing through a heating pipe.
It returns to the heat exchanger 36 at about 350 degrees. Since the metal is recovered in the indirect heating stage, there is no generation of dioxin in the exhaust gas treatment process. An integrated incineration system with an air separator at the core is the ideal system.

[0024] There is an increasing need to develop a safe treatment of the PCB itself or substances contaminated by the PCB. Emulsion fuel plus oxyfuel combustion is also very effective in this PCB processing. If the incineration system of FIG. 2 is used, the PCB can be completely decomposed and made harmless.

[0025]

By burning the emulsion fuel with pure oxygen, a high temperature of 2800 degrees, which cannot be obtained by air combustion, can be produced. Since the amount of exhaust gas is reduced to 1/5 or less, when applied to an incinerator, the cost of exhaust gas treatment equipment and operating costs can be significantly reduced. Dioxin formation can be prevented. Fly ash is reduced. The combustion temperature can be adjusted by adjusting the water content of the emulsion. Nitrogen oxides are very low. The incinerated ash is completely vitrified and the contained heavy metals do not elute. Fuel efficiency and exhaust gas from diesel engines can be cleaned. Combined with air separation, which can supply nitrogen and oxygen simultaneously, a complete incinerator system can be created comprehensively, which can solve all environmental problems related to waste incineration.

[Brief description of the drawings]

Fig. 1 Conceptual diagram of incineration ash melting by emulsion and oxygen combustion

FIG. 2 is a conceptual diagram of an incineration system using an air separator as a core.

[Explanation of Signs] 1 ... Burner 2 ... Reflection furnace 3 ... Rotary furnace 4 ... Drive device 5 ... Screw feeder 6 ... incineration ash 7 ... gate 8 ... ladle 9 ... flue 20 ... city garbage 21 ... hopper 22 Screw feeder 23 Rotary furnace 24 Driving device 25 Discharge mechanism 26 Conveyor 27 Screen 28 Screen 28 ………………………………………………………………………………………………………… ···································································································································· ……… Air separator 35 ………… Scrubber 36 …………… Heat exchanger

Claims (7)

[Claims] 1. A fuel mixture of water and oil having an oxygen concentration of 21%
A method for burning a mixed fuel of water and oil, characterized by burning with the above gas. 2. A method for controlling the combustion temperature of a fuel mixture of water and oil, wherein the combustion temperature is changed by changing the water content of the fuel mixture of water and oil. 3. A mixture of water and oil is generated by decomposing water in the mixed fuel of water and oil by supplying oxygen in excess of the theoretical amount of oxygen necessary for complete combustion determined from the components of the mixed fuel of water and oil. A method characterized by completely oxidizing the inside of a furnace by completely burning hydrogen. 4. The method according to claim 3, wherein the amount of oxygen is made lower than a theoretical value, and hydrogen generated by the decomposition of moisture is left to make the inside of the furnace a reducing atmosphere. 5. In a combustion furnace, a gas having an oxygen concentration of 21% or more is supplied instead of air in order to burn a combustion product. A combustion furnace wherein steam or mist-like water is supplied to adjust the furnace temperature, and the furnace temperature is adjusted by utilizing the heat of decomposition of water. 6. An air separator capable of simultaneously supplying oxygen and nitrogen is provided. Nitrogen generated by the air separator serves as a medium for gasification and carbonization by indirect heating of an object to be heated, and
A combustion furnace system equipped with an air separator, characterized in that it is used as a transport fluid for generated powder and oxygen is used for combustion. 7. A method for burning a mixed fuel of water and oil with a gas containing 21% or more of oxygen, wherein the gas for spraying the mixed fuel of water and oil is a mixed gas of oxygen and water vapor, and the water used as fuel is mixed with water. A method of burning a mixed fuel of water and oil, wherein the mixing ratio of oxygen and water vapor is changed according to the water content of the mixed fuel of oil.