JP3054838B2 - How to incinerate soy sauce - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for incinerating soy sauce, which is one of the by-products produced in the soy sauce production process.

[0002]

2. Description of the Related Art Soy sauce is basically a seasoning obtained by heat-treating soybeans and wheat and fermenting in a saline solution to clarify suspended slurry-like mash by press filtration. By the way, in a soy sauce manufacturing plant, in the clarification step, soy sauce is by-produced as a water-insoluble liquid component. This soy sauce is mainly higher fatty acids or their ethyl esters derived from raw materials such as soybeans and wheat, and is not suitable for edible use and must be discarded. Some of them are not refined and cannot be sold as cutting oils for machining metal products, but most of them are incinerated together with other municipal waste in waste incinerators etc. due to refining costs. This is the conventional situation.

[0003]

When crude soy sauce is simply incinerated as in the prior art, the nitrogen (N) content contained in the soy sauce is incinerated under combustion conditions such that the air becomes partially insufficient. There is a risk of by-products of the compound. The main constituents of the original soy sauce are higher fatty acids, that is, linoleic acid, oleic acid, palmitic acid or their ethyl esters, which themselves do not contain N components. Since the crude soy sauce separated in the process dissolves or suspends soy sauce containing amino acids and fine solids derived from moromi, it is 0.1 to 0.5.
It usually contains wt% N.

[0004]

[Table 1]

[0005] Table 1 shows measurement examples of the physical properties and composition of crude soy sauce. According to this, the N content is 0.3 wt%.

[0006] It is well known that nitrogen oxides are liable to be formed when organic matter containing N is burned, but according to recent studies on their reaction mechanisms, for example, Toshiro Hirano, , 185 pages, Kaibundo Publishing, 198
In six years,

[0007]

(Equation 1)

[0008] A reaction formula such as Formula 1 is shown, and it has been clarified that the N component in the fuel undergoes a combustion reaction via hydrogen cyanide (HCN) as an intermediate product.

If the fuel containing N is forcibly burned in a state of lack of oxygen (O ₂ ), the reaction in the latter half of equation 1 does not proceed, and toxic HCN remains as a by-product.

HCN is usually in a gaseous state and is contained in exhaust gas. However, when the exhaust gas is purified by washing with water or the like, it is absorbed into water as cyan ions (CN ⁻ ), and the waste water has toxicity. become. As is well known, H
CN and CN ^- is the intensity of toxic substances, removal of exhaust gas or waste water below normal 1ppm to discharge into the environment containing them, are those that must be reduced.

Here, it is generally said that O ₂ deficiency easily occurs when incinerating wastes and the like. However, in a portion where incineration is in progress, the ratio of O _{2 to} incineration is small and locally. Means that O _{2 is in} short supply. In particular, when a solid or a solid / liquid mixture is incinerated, O _{2 is} likely to be insufficient in a relatively large part since air hardly permeates into the incineration.

References as an experimental example of this HCN generation include Takashiro et al., Transactions of the Japan Society of Mechanical Engineers, 4
Vol. 4, No. 388, p. 4282, 1978. That is, Takagi et al. Added ammonia (N ₃ ) as a N source to propane gas (main component C ₃ H ₈ ) as a fuel not containing N.
H ₃₎ the 1.35VOL% (0.43Wt as N minutes
%) The contained gas is blown out from the sintered metal porous plate and burned to form a flat flame, and the gas composition near the flame surface (at a position 10 mm from the sintered metal porous plate) is measured.

According to the results, the generated HCN concentration varies depending on the combustion temperature (1600-1800 ° K).
It shows a value of 00 to 1000 Volppm. Also,
For reference, the measured values without NH ₃ are also shown,
Also in this case, a small amount of HCN is generated from the N content in the air, but the concentration is about 1/100 of the former, and it is clear that HCN generation is remarkable when the N content is incinerated. Of course, the HCN in these flames are usually intended to be oxidized further NO, etc. N ₂ according to equation 1 in the wake of the flame, stop at HCN when O ₂ is insufficient in Wakashi slipstream , Causing a risk of discharging the cyanide into the environment as described above.

An object of the present invention is to prevent the danger of containing toxic cyanide in exhaust gas and / or exhaust gas washing wastewater when the above-mentioned crude soy sauce is incinerated. In addition, since soy sauce oil usually has a heat of combustion of 9000 kcal / kg or more, in order to make effective use of this heat, incinerators for wastes and the like that require generation of hot air, for example, Japanese Patent Application Publication No.
The object of the present invention is to make it possible to incinerate soy sauce safely by using it as a fuel for generating hot air in a soy sauce slag incinerator as shown by the method for incinerating 143510 soy sauce slag.

[0015]

According to the present invention, as a means for solving the problem, soy sauce is sprayed into fine droplets and burned, so that the soy sauce is rapidly and completely removed under a high temperature and sufficient O ₂ atmosphere. The method of burning is adopted.

In the case of burning liquid fuel, the necessary conditions for improving the burning rate are generally to atomize the spray droplets, raise the combustion temperature, increase the oxygen partial pressure, and mix the combustion field. And giving the combustion gas sufficient residence time to complete the combustion reaction.

The present inventors have studied how to set the above combustion conditions in order to suppress the generation of HCN in soy sauce.

First, the conditions for finely spraying soy sauce oil are usually employed. For finely spraying liquid, spraying with a high-pressure spray nozzle or a two-fluid spray nozzle is usually employed. The former is intended to atomize the liquid is ejected pressure energy from the small holes of the nozzle tip by the pressure of the liquid itself more than 10kg / ^cm 2 -G, the latter 2 to 10 kg / cm ² -
G is ejected from a small hole at the tip of the nozzle together with a gaseous medium such as air or steam pressurized to G, and is atomized by the pressure and kinetic energy of the air or steam.

However, in order to atomize the spray droplets by the former self-pressure spraying, it is necessary to use a small nozzle having a small flow rate of the spraying liquid or to use extremely high-pressure spraying, which requires a certain amount of large-scale processing. Is not practical. In the latter two-fluid spraying, atomization spraying is possible even if the pressure of the air or steam of the spraying medium is not so high as described above, and a nozzle having a relatively large spraying liquid flow rate can also be manufactured.

Therefore, the present inventors first limited the nozzles used to the two-fluid spray nozzle, and studied the relationship between the spray conditions and the droplet diameter of the soy sauce oil. Subsequently, based on the results of these studies, a combustion experiment was conducted on soy sauce under conditions that allow atomization and spraying, and a study was conducted to determine the presence or absence of HCN generation.

FIG. 1 shows an example of the structure of the two-fluid spray nozzle used by the present inventors. This nozzle has a structure in which a liquid to be sprayed and pressurized air or steam are once mixed in a mixing chamber provided at a nozzle tip portion, and then are ejected into a combustion space from an ejection hole having a small tip. This is a nozzle called an internal mixing type. The number of ejection holes may be from 1 to 10 or more depending on the flow rate of the liquid to be sprayed. It will be almost the same.

First, when the soy sauce oil is sprayed by the above-described two-fluid spray nozzle, the spray liquid amount to the spray droplet size versus the spray medium amount, that is, the pressurized air flow rate to the soy sauce oil flow rate.
Alternatively, the effects of the ratio of the water vapor flow rate, the pressure between the spray liquid and the spray medium, the size and number of the ejection holes, etc. were systematically examined. In addition, a measuring device utilizing diffraction of laser light was used for measuring the diameter of the spray droplet.

Some of the results are shown in FIG. The figure shows two nozzles for a small flow rate of 30 l / h and a pressure of 5 kg / cm ² -G, with the pressure of the spray liquid and the pressure of the spray medium being constant, 2.2.
mmφ-1 hole nozzle and large flow rate 200 liter / h,
It is a graph showing a change in a spray droplet diameter depending on a ratio of a spray medium to a spray liquid amount in a 2.2 mm φ-6 hole nozzle, that is, a gas-liquid ratio.

The average particle size _{d 32} in the figure 99% particle size d
It is shown _99, but these were determined body area average particle diameter distribution of the measured spray droplet size was approximated by the Rosin-Rammler distribution formula of d _32, the mass cumulative curve from smaller particle size side particle diameter corresponding to a 99 wt% is _{d 99.} When the unburned residue in the flue gas is a problem, the maximum particle size of the spray droplets is more dominant. From this point, d is also applied to HCN which is considered to be a kind of incomplete combustion product. ₉₉ is a more important index.

From the experimental values shown in the figure, it can be understood that, as described above, if the nozzle hole diameter is made the same, even nozzles having different numbers of spray liquid and different amounts of spray liquid can obtain substantially the same droplet diameter.

The physical properties (density, viscosity, surface tension) of the spray liquid influence the diameter of the spray droplet. In particular, the viscosity of the spray liquid is an important factor, and it is difficult to spray a highly viscous liquid.
If it is 0 cP or less, it is possible to perform spraying according to the spraying of water (viscosity of about 1 cP). As shown in Table 1, the viscosity of soy sauce oil is about 10 cP, which is in a range where fine spraying is possible.

The pressure of the spray liquid and the spray medium also affects the spray droplet size. However, in the case of a two-fluid spray nozzle, the stability of the flow rate cannot be obtained unless the pressures of both nozzles are substantially equal. The higher the spray pressure, the finer the spray droplets. From this point, the spray pressure is 2.0 kg /
At cm ² -G or less, atomization of the spray droplets is difficult, and the non-uniformity of the spatial distribution of the spray droplets increases. on the other hand,
When the spray pressure is 8.0 kg / cm ² -G or more, the effect of atomization accompanying the pressure increase becomes small. As a result of the experimental data, the effect of the spray pressure when spraying into the normal pressure space was 2.0
If it is in the range of up to 8.0 kg / cm ² -G, the gas-liquid ratio (G / L) is converted to a value in normal pressure (Nm ³ -gas / liter-).
When the pressure is increased, the liquid flow rate is increased, so that G / L does not change much, and the curve relationship in FIG. 2 hardly changes even if the spray pressure changes.

The diameter of the nozzle ejection hole also affects the diameter of the spray droplet. Generally, the absolute value shown in FIG. 2 changes almost in proportion to the hole diameter. Therefore, in order to perform fine spraying with a pore diameter of 4 mmφ or more, a considerably large amount of a spray medium is required, and the pore diameter is 4 mmφ or less, preferably 2.
It is better to be 5 mmφ or less. However, if the pore size is too small, the solid particles suspended in the liquid may cause blockage at the nozzle hole, which is not desirable. 1.0mm for practical use
φ or more is required.

Here, the relationship between the size of the droplet and the burning speed when burning the liquid is known. The burning speed is known to increase in inverse proportion to the square of the droplet diameter. Therefore,
When the atomized droplets are atomized, the combustion speed increases rapidly,
Since to achieve incineration to complete combustion of soy sauce oil of the present invention have found that the present invention has found that there needs to be a d ₉₉ to 300μm or less, and the spray nozzle that can be the d ₉₉ to 300μm or less The selection of spray conditions was a necessary condition for complete combustion. Therefore, in the case of soy sauce, d ₉₉
G / L is set to 0.3 from FIG.
Nm ³ -gas / liter-oil or higher.

Next, the combustion temperature and the oxygen partial pressure are shown as indices for achieving complete combustion.
It has been found that it is necessary to desirably have a temperature of 1050 ° C. or higher, and the air ratio needs to be 3 vol% or more in the exhaust gas after combustion.

Here, the combustion temperature is determined from the calorific value of the fuel, the spray medium and the amount of combustion air, and the enthalpy balance of the heat loss in the combustion furnace, as in the general combustion calculation. From this, it is difficult to obtain a high combustion temperature when the calorific value is too small. The amount of excess oxygen in the exhaust gas is determined by the amount of air supplied above the theoretical amount of air required to oxidize the fuel stoichiometrically, that is, the excess air ratio.

In the case of soy sauce, as shown in Table 1, the higher calorific value is about 9400 kcal × kg. The theoretical air amount is about 8.5 Nm ³ / kg, and the theoretical combustion temperature when the excess air rate is 0 is calculated to be about 2300 ° K. Therefore, even when considering the sensible heat for excess air and the heat loss of the combustion furnace necessary to make the excess oxygen amount in the exhaust gas 3 vol% or more, the calorific value of the soy sauce oil depends on the combustion temperature. Sufficient to realize.

Next, to improve the mixing in the combustion field, atomization of the spray droplets is also a powerful means for improving the mixing itself. It is common practice to apply a swirl force to the medium and combustion air to blow it in. This type of burner is called a swirl flow burner and is commonly used as a high-load burner that enables calorifically large amounts of combustion in a small space. Have been. The same type of burner is used in the present invention.

On the other hand, while the residence time required for complete combustion is complementary to the degree of mixing, in soy sauce incineration,
When the above temperature and residual oxygen partial pressure are satisfied by using a burner with a good mixed state, the combustion is sufficiently completed if 0.4 s or more. Therefore, it is necessary to design the internal volume of the combustion furnace so that the residence time can be secured.

The incineration experiment of crude soy sauce under the various combustion conditions described above was conducted, and the result of examining the presence or absence of HCN generation will be specifically described below. Here, the detection of HCN has a very low concentration in the exhaust gas, and the analysis method is difficult. Therefore, the flue gas discharged from the combustion furnace is immediately introduced into the water to absorb the HCN component into the water, and its time The amount of accumulation was detected.

A method in which the combustion exhaust gas is immediately introduced into water to rapidly cool the exhaust gas or absorb harmful components by direct contact between the exhaust gas and water is called a submerged cooling can method. FIG. It is a structural explanatory view of an incinerator with a submerged cooling can.

In FIG. 3, the upper half constitutes the incinerator 1. The spray nozzle 2 for soy sauce is a two-fluid spray nozzle using pressurized air, and the size is 30 liter / h (2.2 mmφ-1).
Hole), which is attached to the center of the upper end of the burner 3. The burner 3 has a cylindrical shape with a refractory material lined therein, but has a combustion air blowing port 4 attached in the circumferential direction at the upper end, so that the combustion gas forms a swirling flow. The lower end of the burner 3 is further connected to a cylindrical incinerator body lined with a refractory material, and is designed so that complete combustion proceeds while the combustion gas passes through the furnace and stays therein. The inner diameter of this straight body is 400mmφ, length 1300m
m, the furnace volume is about 160 liters. A detection end TI for detecting a combustion temperature is attached to a lower portion of the combustion furnace.

The lower half of FIG. 3 constitutes a submerged cooling can 5, and the gas exiting the combustion furnace passes through a downcomer 6 of a combustion gas injection pipe having a funnel-shaped upper part and a straight tubular part at the lower part. It is blown into. The can volume is about 130 liters.
The injected gas is inverted at the bottom of the can and becomes bubbles to rise in the liquid. During this time, the gas is cooled and the water-soluble components are absorbed. It is optional to improve the absorption capacity by making the can solution 7 alkaline water as needed. However, in the case where the harmful components of the gas discharged from the submerged cooling can are not completely absorbed or the harmful components insoluble in water are contained, the exhaust gas is further made harmless, though not shown in FIG. Of course, it must be processed and discharged. The upper part of the downcomer is funnel-shaped in order to form a wet wall by overflowing water or a can solution from the peripheral edge of the upper end for material protection. The pump 9 is for circulation of the can liquid, and FI is a flow meter.

[0039]

[Table 2]

Table 2 shows the results of a soy sauce oil combustion experiment using the apparatus described in FIG. The soy sauce used had the physical properties shown in Table 1. In the data of Table 2, the supply amount of soy sauce was 26.0 kg / h, and the spray was 5 kg / cm ² -G.
Gas / liquid ratio of 0.40 Nm ³ -air /
The experiment was conducted by spraying as liter-oil and changing the combustion temperature by arbitrarily adjusting the amount of combustion air. Approximately 130 liters of water was first supplied to the can solution, and the solution was circulated while replenishing the evaporation. Here, CN ^- of analysis JIS-K0
102, but in this case, CN ⁻
Is 1 μg / g.

Experimental results other than those in Table 2 were also examined, and the following findings were obtained as combustion conditions without danger of HCN generation. That is,
Air or water vapor pressurized to 2.0 kg / cm ² -G or more using a two-fluid spray nozzle having a hole diameter of an ejection hole for spraying of 3 mm or less, desirably 2.5 mm or less, and 1.0 mm or more is used. By spraying at a ratio of 0.3 Nm ³ -gas / liter-oil or more, the combustion gas temperature becomes 950 ° C. or more, preferably 1050 ° C. or more, and the amount of combustion air is reduced to 3 vol% or more of residual oxygen in the combustion exhaust gas. Then, the combustion is performed by adjusting the soy sauce oil flow rate and the combustion air flow rate so that the combustion gas residence time becomes 0.4 s or more.

In a waste incinerator or the like that requires the generation of hot air, for example, in an incinerator for soy sauce slag, the combustion conditions of the burner for generating hot air and the entire combustion furnace are set to the combustion conditions without the risk of HCN generation. If so, soy sauce can be used as a fuel for generating hot air, and at the same time, it can be treated.

[0043]

If soy sauce is incinerated under the spray combustion conditions disclosed above, the spray oil droplets are atomized and most of the particle size is 30.
Since the particle size is 0 μm or less and the combustion proceeds rapidly and completely, no cyanide compound which may be a by-product under the oxygen-deficient combustion conditions is not contained in the combustion exhaust gas or the exhaust gas cleaning water.

[0044]

EXAMPLE 1 26 kg of crude soy sauce having an N content of 0.30 wt% was prepared using the same apparatus as described above with reference to FIG.
/ H, and the amount of combustion air was adjusted so that the combustion temperature became 1050 ± 15 ° C., and continuous incineration for 48 hours or more was performed. The analysis of the exhaust gas and the cyanide compound in the exhaust gas cleaning water was performed once per hour, and in all cases, the analysis was below the quantification limit (1 μg / g in terms of CN-amount).

[0045]

Embodiment 2 Next, an embodiment using soy sauce as a fuel for generating hot air in an incinerator or the like will be described. Japanese patent, JP-A-4-
In the soy sauce slag incinerator according to 143510, a soy sauce combustion burner satisfying the combustion conditions of the present invention is attached in place of the heavy oil burner for generating hot air, and the soy sauce slag is burned and simultaneously burned. Was. This incinerator uses soy sauce slag (crushed material with a particle size of 2 mm or less, N content: 1.9 wt%)
Is burned in a stream of hot air at a rate of 900 kg / h, soy sauce is burned at a flow rate of about 25 kg / h so that the combustion gas forms a swirling flow in a vertical frustoconical incinerator. Designed, average combustion gas residence time about 1.5s
The operation is performed by adjusting the amount of soy sauce and combustion air so that the temperature is maintained at 1300 ± 20 ° C. Although the operation of the incinerator was continued for 6 months or more, no cyanide was detected in the washing water of the venturi scrubber, which is a combustion exhaust gas washing device, and in the exhaust gas after washing.

In this embodiment, an incinerator for soy sauce slag was selected as an example of using soy sauce as a fuel for generating hot air.
The object of utilization is not limited to this, and it is natural that the invention can be applied to incinerators for other waste liquids, waste oils and other wastes as long as the combustion conditions of the present invention are satisfied.

[0047]

According to the present invention, there is a risk that toxic cyanide is contained in exhaust gas or exhaust gas washing water when crude soy sauce is simply incinerated. In addition, it can be effectively used as a fuel for generating hot air in waste incinerators that require the generation of hot air, for example, incinerators for soy sauce slag, which is extremely useful in preventing pollution and saving resources. is there.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view of a two-fluid spray nozzle.

FIG. 2 is a diagram showing a change in a spray droplet diameter depending on a gas-liquid ratio in a two-fluid spray nozzle.

FIG. 3 is a structural explanatory view of a waste liquid incinerator with a submerged cooling can.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator 2 Spray nozzle 3 Burner 4 Air inlet for combustion 5 Cooling can in liquid 6 Downcomer 7 Can liquid

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Asami 7th Horie-cho, Matsuyama-shi, Ehime Miura Kogyo Co., Ltd. (72) Inventor Isoroku Otsuka 339 Noda, Noda-shi, Chiba Pref. Within Kikkoman Corporation (72) Inventor Yukiaki Hara 2-12-26 Konan, Minato-ku, Tokyo Nippon Steel Chemical Co., Ltd. (56) References JP-A-4-143510 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23G 7/00 F23G 7/05

Claims (2)

(57) [Claims] 1. A method for incinerating soy sauce oil by-produced in a soy sauce production process as it is, wherein the soy sauce oil is sprayed using a two-fluid spray nozzle having an orifice diameter for injection of 4 mm or less and 1.0 mm or more. 2.0 as spray medium
Air or steam pressurized to 8.0 kg / cm ² -G is sprayed using a ratio of 0.3 Nm ³ -gas / liter-oil or more. When the combustion gas temperature is 950 ° C. or more, oxygen in the combustion exhaust gas is reduced. By burning under combustion conditions such that the combustion gas becomes 3 vol% or more and the residence time of the combustion gas in the combustion furnace becomes 0.4 s or more, the combustion exhaust gas or the exhaust gas washing waste water is made to contain no cyanide. Characteristic method of incineration of soy sauce. 2. A burner equipped with a spray nozzle according to claim 1 as a burner for generating hot air when incinerators for wastes or the like require hot air generation, and burning of the incinerator using soy sauce oil as fuel. The incineration treatment of soy sauce oil, characterized in that the combustion conditions described in claim 1 are satisfied with respect to temperature, oxygen partial pressure, and combustion gas residence time so that combustion exhaust gas or exhaust gas washing wastewater does not contain cyanide. Method.