JPS58101728A - Removing method for nitrogen oxides in waste gas of combustion - Google Patents

Abstract

PURPOSE:To remove NOX in waste gas of combustion at low running costs by feeding night soil into the waste gas of combustion of relatively high temp. and reducing NOX with the ammonia nitrogen in the night soil. CONSTITUTION:Human or livestock night soil is fed by spraying or the like to the flow of waste combustion gas at 850-1,100 deg.C and NOX in the waste combustion gas is removed perfectly or partially by a dry method using no catalyst. About >=60% of the nitrogen in the night soil is ammonia nitrogen which reduces NOX in the waste gases in the above-mentioned temp. range and further induces the chemical oxidation reaction by O2, whereby N2, CO2 and H2O are formed. Therefore, the best place for feeding the night soil is right after burning out of fuel, an when O2 is deficient in the combustion gas, a method for feeding the same in a form of mist together with air is suited.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses human waste to reduce nitrogen oxides (NOx) in combustion gas.
) is completely removed, and maf( is partially removed).

Methods for completely or partially removing (hereinafter referred to as 0) 101 in combustion exhaust gas include dry methods and wet methods, and dry methods are further divided into catalytic methods and non-catalytic methods.

In the catalyst method, for example, the combustion exhaust gas purity is about 300 to 400.
A reducing agent (such as ammonia) is injected into the medium temperature range of ℃ and installed immediately after that, for example, 11% 0
By passing through a catalyst layer containing Pt etc., N
This method reduces o to M14C. (MO at high temperature
X is effectively KMO. ,) The non-catalytic method is a method in which reducing chemicals (ammonia, urea, etc.) are injected into a high-temperature combustion chamber, and the NO in the exhaust gas is reacted non-catalytically to produce Ml. .

In addition, in the wet method, Mol.
HOtMO! In order to oxidize to nitrogen, for example, ozone or 0101 is used, which is absorbed into a sodium sulfite aqueous solution and simultaneously reduced to nitrogen gas.

Among these three methods, the mixing method has significantly higher equipment costs and operating costs than the other methods, and is hardly used at present.

Among the dry methods, the catalytic method can be advantageously used for gases such as NPG, LPG, and kerosene combustion exhaust gas that contain almost no sulfur oxides (aOX) or other catalyst poisons, but they It is not used when the combustion exhaust gas contains soot, sulfur oxides (110X), hydrogen chloride gas, etc., as in the case of a fire-burning furnace.

Therefore, especially for dirty gases, we have to rely on the non-contact method, but this method is also sensitive to the chemicals used, such as ammonia, urea, or hydrogen in combination with these. , -Acid carbons, hydrocarbons, etc. are all expensive, so they have the disadvantage of increasing luck and responsibility.

In view of the above circumstances, it is an object of the present invention to provide a method for reducing Mol in combustion exhaust gas that is inexpensive and, more narrowly, to provide a method for reducing MOX using human waste. The purpose of the present invention is to provide a method for utilizing human waste.

That is, the present invention uses night soil, which is a poisonous substance for livestock, in place of the ammonia and urea mentioned above. It is as follows.

PH7 9 Floating matter 21,000-26,000 ppmBO
D 8,000-15,000 ppm1t
5,000-6,000 ]>pm Ammonia nitrogen 3,000-4,000 DPIII alpminoid nitrogen 1,000-2,000 ppm Evaporative logging 3.0-3.5% (However, ]>P (The above-mentioned albuminoid nitrogen is also a proteinaceous nitrogen/element, so it is considered to be substituted ammonia. Therefore, 60 to 80% of the nitrogen in human excrement is nitrogen in a broad sense. It can be said to be ammonia-based.

Regarding the human waste from Mae House 1, its properties and analysis examples are as follows: PH7.0 Floating matter 21,000-26.000 ppmBO
D 8,000~17,000 PI>m total f
i1 element 4000-5,000 ppm ammonia nitrogen 2. OQO~3,000 ppm Algminoid nitrogen 800~2,000 ppm Roaring residue 3.
0 to 5.0% (ppm and % are based on weight), and 55 to 80% of the total amount of human waste from livestock.
is wide A ammonia thread.

In other words, conservatively speaking, more than 60% of the total nitrogen is ammonia nitrogen in a broad sense, and is not included in the above analysis value, but very little nitrogen is included as nitrites.
The nitrogen content as nitrate is 10() ppm or less.

Now, according to the results of experiments, human urine exhibits a reducing power for No in the range of approximately 850°C to 1100'C, and the chemical reaction that occurs at this time can be expressed simply as: 4NR1+6NO+: 6RkoO+511z...
・・・・・・・・・(1) 161JR3+120z=24
RzO+8N...C) (Rt water ratio per amino group excluding 1 amino group in protein. If R is other than a hydrogen atom, RsO ik (Currently, this is not appropriate; it consumes more oxygen and becomes carbon dioxide and water.)

The above-mentioned reaction formula is based on the fact that only ammonia fibers among the nitrogen in human waste can participate in the reduction of MO, and that ammonia-based substances that are not used for reduction are oxidized by oxygen in the combustion exhaust gas and converted to nitrogen. It is merely a chemical equation used to show that changes occur, and is not intended to show the exact relationship between material balances and expenditures.

However, it is clear from equation (2) that it is essential to have enough oxygen to oxidize the ammonia-based substances used for reduction, but all combustion exhaust gas
As a result of combustion using surplus air (excess oxygen to be exact) in a combustion furnace, it contains acid #, and this oxygen content is OK to burn ammonia-based substances that were not used for reduction.
That's enough.

In addition, the amount of human waste to be used for NO is at least 0:67 times the molar concentration of nitrogen when the ammonia-based substances it contains is expressed as molar nitrogen per 10 molar loss, so that all of the NO can be reduced. However, in reality, even if more than one ammonia-based substance is used,
Since NO cannot be completely removed, it is necessary to use it in excess.

As mentioned above, the temperature at which human waste can be reduced to N0t is 85
Although the temperature is 0° to 1100°C, the best place to send human waste according to the actual value is immediately after the fuel has finished burning.
°In the case of a garbage incinerator, it is sent to the entrance of the secondary combustion chamber, and in the case of a boiler such as Arashi-Tuna-fired, it is sent to the beginning of the woodwind group. On this occasion,
It is preferable to disperse it into the combustion exhaust gas in the form of a spray using pressure or force such as using a rotating ridge plate.If there is a lack of oxygen in the combustion gas, it is better to send it in the form of a mist with air. The body is convenient. The sprayed human waste is vaporized and decomposed at high temperatures to reduce NO.

A method for reducing unreleased NOj will be explained in detail by way of an example.

6mtl'lJ1 Exhaust gas temperature 900℃ at the furnace outlet of the continuous combustion mechanical sluggish combustion furnace to 55,000M Gin, NO! When the concentration is 1100 pp, human human waste is sprayed at the outlet of the furnace.
1% A:/9Nia water equivalent g/h 714 435 50%
920 561 60%
1100 671 70
%Met.

As mentioned above, human and livestock human waste are effective in removing MO (therefore MOX) from combustion exhaust gas, but from the perspective of human waste disposal, recent treatment regulations require 1. There is a growing demand for a reduction in not only BOD but also nitrogen content, and this method is extremely useful because it can release BOD components and nitrogen contained into the atmosphere as carbon dioxide, water, and nitrogen gas. This can be said to be a major contribution to pollution prevention in both a technical and economic sense.

In addition, if fuel gas, such as -chlorinated carbon, hydrogen, hydrocarbons, or a mixture of two or more of these, is injected into the combustion exhaust gas when or before or after burying human waste, the combustion heat will be increased. This increases the temperature and prevents the temperature from decreasing due to the heat of evaporation of the water, but this is not a necessary condition.

Dewhaleman Ririma Co., Ltd. Agent: Patent Attorney Masaaki Miki Agent: Patent Attorney Yoshi Nakamura

Claims (1)

[Claims] A method for removing nitrogen oxides from combustion exhaust gas, characterized in that human waste is introduced into the combustion exhaust gas stream at a temperature of 850° C. to 1100”c.