JPS6022967B2 - Deodorization treatment method for odor gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling condensed and sticky odorous gases and low-temperature, key condensed and sticky odorous gases in a system with multiple odorous gas generation sources or outlets. The present invention relates to a method for deodorizing while effectively recovering waste heat by rationally and roughly matching the functional characteristics of a side heat exchanger and a low-temperature side heat exchanger.

The gases emitted during the painting, baking, or printing processes for automobile bodies, containers for weak electrical products, canned goods, cosmetic cans, etc., which use a large amount of organic solvents, contain various hydrocarbons, aldehyde intermediates, tar-like fumes, etc. It contains a large amount of gas components, and the gas is discharged from multiple sources or outlets.

Some of the gas components are subject to hazardous substance regulations, some cause photochemical smog, and some are accompanied by bad odors. In addition, the above gases are classified into various types based on their physical properties, from gases that are condensed and sticky and include tar fume, etc. to gases that have relatively low humidity and do not contain tar or oils and fats. .

Traditionally, when processing these gases, large air volumes, low temperatures,
Low-humidity gas is pretreated with a filter, etc., and then treated with an adsorption device using activated carbon, but the exhaust gases from the other systems mentioned above are collected in a collective duct and passed through an odor gas fan. Generally, the odor gas is treated with a direct combustion device or a catalytic deodorization device via a preheating heat exchanger. Recently, as an energy-saving measure, there has been a trend to collect mist and dust using filters, etc., and then dispose of the mist and dust using catalyst deodorizing equipment.

However, no matter which method is used, by merging the odor gases of each system, the gases of the system that turn into mist as the temperature decreases or that contain tar-like fumes that are treated alone can be removed before being deodorized. It fouls the treatment filter and increases pressure loss, it adheres to the drive part of the odor fan, causing unbalanced rotation, and it also forms deposits on the odor gas heat exchanger, impairing the function of the heat transfer surface. At the same time, the gas passing resistance is increased, and due to repeated operation and shutdown of the plant, the deposits are oxidized or deteriorated, creating a factor that generates dangerous substances that are likely to ignite at ambient temperatures of around 160 to 190 degrees Celsius. There have been many cases in the past where heat exchangers were burnt out and fires were caused from duct systems to process sources, etc. Therefore, the importance of pretreatment is emphasized. Regarding these countermeasures, the present inventor proposed that when deodorizing odor gas in a system with multiple odor gas generation sources by catalytic oxidation or direct combustion, Deodorizing treatment is carried out by catalytic oxidation method or direct combustion method, and the heat of high temperature waste gas generated during this deodorization treatment is converted into a heat medium required by the production system, and the heat of the waste gas is used to generate low temperature and low temperature odor gas. The preheated odorous gas is used as combustion air for the burner, and is combined with the condensed and sticky odorous gas to reduce the temperature and relative humidity, thereby suppressing mist. We would like to propose a deodorizing treatment method for odorous gases.
6-40021)).

However, this method of deodorizing odorous gas is an effective means for returning most of the recovered heat from the plant as a whole to the process that generates the odor in terms of waste heat utilization. In some cases, the source process requires little use of heat recovery.
Particularly for organic solvent-based sources of odor gas, there are few methods of utilizing waste heat due to plant characteristics, equipment improvement costs, etc. Therefore, it is necessary to recover waste heat and save fuel using an odor pre-determined exchanger. I don't get it.

In such a case, gases that easily form into mist, including condensed and sticky gases, adhere to the heat transfer surface on the low-temperature inlet side of the heat exchanger, forming oxidized or degraded lower carbon.

This is particularly noticeable when the load on the amount of odor gas decreases or when the wall temperature of the outdoor duct decreases in winter.

To avoid such troubles, when determining the heat recovery efficiency of a heat exchanger, the most important thing is to always adjust the metal temperature on the heat transfer surface of the low-temperature side heat exchanger into which the odor gas is introduced to the fog point of the gas. It is necessary to maintain the temperature above that temperature.

Therefore, since the inlet odor gas temperature and the outlet waste gas temperature of the heat exchanger have a close relationship, the temperature efficiency of the heat exchanger is itself subject to restrictions. Generally, in the case of condensed and sticky gases as mentioned above, the low temperature heat transfer temperature is 15
000 or more is desirable, and therefore the heat exchanger outlet waste gas temperature usually needs to be 200 to 250 qo or more.

An object of the present invention is to provide a method for deodorizing odor gas that advantageously solves the above-mentioned problems.

Next, this invention will be explained in detail with reference to the drawings.

Figure 1 shows that when using a catalytic deodorizing device to treat harmful foul-smelling gases from organic solvent-based fumes generated from the painting, printing, and condensation processes used to manufacture cosmetic cans for cans, juice, etc., This shows a process system in which odor gas is introduced into two high- and low-temperature preheating exchangers and deodorized at the same time. Roughly classifying the characteristics of the odor gases generated in the above equipment, the gases generated in the baking oven 3 for painting or printing are other than organic solvent fumes because the system includes a burner heating device 4 and a gas circulation fan F4. It is a condensed and sticky odor gas that contains large amounts of hydrocarbon intermediate products and tar-based fumes, and has a fog point usually in the range of about 100 to 150°C.
A part of it is discharged into the duct 5 from the outlet side.

Furthermore, the gas between the painting or printing device 6 and the inlet of the late baking oven 3 is an odor gas generated by the natural evaporation process of the organic solvent and the sealing of the baking oven with an air curtain or the like. The gas emitted from
Low temperature, low humidity, and low concentration gas.

In addition, the cooling process 8 of the product also serves as an air seal on the Akatsuki open exit side, so the drying gas is low temperature and low concentration.
The gas is discharged from the hood 9 and collected together with the gas from the hood 7 in the duct 101.

The low temperature gas of about 20 qo in the duct 10 is preheated by the low temperature side heat exchanger 2 via the odor gas fan F2, and becomes superheated dry gas of about 19,800 qo and is sent to the duct 1 1
It merges with the condensed and sticky gas of about 13,000 in the duct 5, and in order to dilute the atomizing gas and prevent the gas from becoming a mist, it becomes a relatively low relative humidity. It is introduced into a pretreatment filter 13 via a duct 12. Unlike conventional methods that attempted to achieve the effect of fogging gas by increasing the temperature or removing mist, this method does not prevent fogging only by the conventional temperature raising effect, but rather prevents fogging by drying superheated odor gas. The synergistic effect of increasing the temperature while diluting the condensed and sticky gas by mixing them has a remarkable effect on preventing fogging.

Since the gas having the above-mentioned properties is introduced into the pretreatment filter 13, mist adhesion is significantly reduced, and the filter mechanism can therefore be simplified to reduce pressure loss.

Moreover, since mist is prevented from adhering to the rotating part of the deodorizing fan F, which sends gas from the pretreatment filter 13 to the high temperature side heat exchanger 1, unbalanced operation is also prevented. Furthermore, the gas introduced into the high-temperature side heat exchanger 1 has a metal average temperature or a logarithmic average temperature of the low-temperature side heat transfer surface at least about 1
Since it is planned to be 5,000 or more, no deposits will be formed due to tar mist.

The odor gas preheated by the high-temperature side heat exchanger 1 is introduced into the catalyst deodorizing device 14 at a temperature of about 31 to 0, and is heated to about 400q0 by the burner 16 in the subheating chamber 15 of the catalyst deodorizing device 14. activated.

Conventionally, atmospheric air was sucked in as the combustion air for the burner due to problems with the properties of the introduced gas, but in the system of the present invention, the odor of approximately 1 ℃ temperature emitted from the low-temperature side heat exchanger 2 is removed. Since the gas is sent to the burner 16 through the duct 17 and the fan F3 and used as combustion air, it contributes to a reduction in fuel consumption.

The gas heated to about 40,000 ℃ in the heating chamber 16 is catalytically oxidized and deodorized by a catalytic reaction in the catalyst layer 18,
The gas becomes a clean gas with a temperature of about 40,000 g (slight temperature rise due to reaction heat due to oxidative decomposition of the odorous gas), and this gas enters the high temperature side heat exchanger 1, where the heat of the gas is absorbed by the odorous gas. After the temperature reaches about 25,000, it enters the low-temperature side heat exchanger 2, where the heat is absorbed by the low-temperature gas and the temperature reaches about 18
The temperature drops to 0° C., and then it is released into the atmosphere through the exhaust stack 19.

The low-temperature side heat exchanger 2 may be made of the lowest-priced steel material due to its odor gas characteristics and its temperature, and mechanically, the weight ratio of the amount of passing gas on the heating side and the heated side is approximately 100:40. The temperature increase rate on the heated side is high, increasing the dehumidification effect with the other gas. In addition, since it can be introduced into the low temperature side heat exchanger 2 at a low temperature,
The difference between the highest and lowest temperatures inside the vessel can be increased, making it extremely easy to increase waste heat recovery efficiency. Therefore, conventionally, when deodorizing the mixed gas as described above, the temperature of the exhaust gas in the exhaust stack 19 has been set at about 200-200°C.
It was dangerous to set it within 250 qo, but with this invention, an economical heat transfer area of the heat exchanger can be obtained safely and easily, and the pressure loss in the low temperature side heat exchanger can be lowered. In addition, the system pressure drop can be kept low relative to the heat recovery efficiency, and even if the temperature inside the exhaust stack 19 reaches about 150° C., no trouble or danger arises in terms of maintenance and management.

Figure 2 shows an example of a conventional deodorizing device, showing approximately 13,000 condensed and sticky gas systems in duct 5 and duct 1.
About 20q○ of low-temperature/low-temperature gas system is connected to duct 12.
Then, it passes through the mist collection filter 13 and the odor gas fan F, and is preheated in the heat exchanger 1 to become about 240q0 and introduced into the catalyst deodorizing device 14, where it is reduced to about 400qo by the burner 16. It is preheated, catalytically oxidized by a catalytic reaction, and then passed through a heat exchanger 1 to an exhaust pipe 19.
It is discharged at about 2500C.

Note that in order to prevent mist formation, a duct 20 indicated by a silver wire may be provided. Also, about 20 oo of gas from the duct 10 is used as combustion air for the burner 16. In FIG. 2, reference numeral 21 denotes a temperature increasing duct that connects the heat exchanger 1 and the combustion air duct 17 in order to increase the temperature of the combustion air.

A comparative test was conducted with the conditions of the deodorizing apparatus shown in FIGS. 1 and 2 set as shown in Table 1, and the results shown in Table 2 were obtained.

Table 1 Table 2 Note) Fuel used: White kerosene Lower calorific value: 10,400Kca/Hiro specific gravity
: 0.8 Sulfur content: 0.015 or less When carrying out this invention, other devices may be used as the mist removal device in place of the pretreatment filter 13, and the heating method of the catalyst deodorization device 14 An electric heating method may be used instead of the burner 16, and the heating temperature required for catalyst deodorization can be varied depending on the components of the odor gas and the type of catalyst within a range that can maintain the deodorization performance.

Furthermore, a direct combustion type deodorization device may be used. According to this invention, when deodorizing odor gas in a system with multiple odor gas generation sources or exhaust ports by catalytic oxidation method or direct combustion method, it is possible to use a condensed and sticky gas system. The high-temperature waste gas is separated into low-humidity, difficult-to-condensate, and sticky gas systems, and deodorized by the catalytic oxidation method or direct combustion method, and then sent to the high-temperature side heat exchanger 1 and the low-temperature side heat exchanger 2, which are connected in series. The low-humidity, difficult-to-condensate, sticky gas is heated and dried by the low-temperature side heat exchanger 2, and the odor gas is mixed with the condensable, sticky gas. The odor gas is heated and the relative humidity is lowered to suppress mist formation, and then the combined and mixed odor gas is heated by the high temperature side heat exchanger 1 and then introduced into the deodorizing device, so that the characteristics of the odor gas and the high temperature side are By rationally combining the characteristics of the heat exchanger 1 and the low-temperature side heat exchanger 2, high deodorizing efficiency can be maintained, waste heat recovery efficiency can be increased, and fuel consumption can be significantly reduced. Moreover, effects such as being able to prevent malfunctions due to mist adhesion in the gas system introduced into the deodorizing device can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the process of a method for deodorizing a malodorous gas according to the present invention, and FIG. 2 is a diagram showing a process of a conventional method for deodorizing a malodorous gas. In the figure, 1 is a high temperature side heat exchanger, 2 is a low temperature side heat exchanger, 3 is a baking oven for painting or printing, 4 is a burner heating device, 6 is a painting or printing device, 7 is a hood, and 8 is a cooling device. 9 is a hood, 13 is a pretreatment filter, 14 is a catalyst deodorizing device, 15 is an odor gas heating chamber, 1
6 is a burner, 18 is a catalytic oxidation layer, and F, to F5 are fans. Figure 2 Figure 1

Claims (1)

[Claims] 1. When deodorizing odor gas in a system with multiple bromine gas generation sources or exhaust ports using a catalytic oxidation method using a catalytic reaction or a direct combustion method, it is necessary to use a condensable/sticky gas system and low temperature, difficult to condense/sticky gas system. The high-temperature waste gas, which has been deodorized by the catalytic oxidation method or the direct combustion method, is sequentially introduced into the series-connected high-temperature side heat exchanger 1 and low-temperature side heat exchanger 2 as a preheating gas, The low-temperature, difficult-to-condensate, sticky gas is heated and dried by the low-temperature side heat exchanger 2, and the odor gas is mixed with the condensable, sticky gas to raise the temperature and lower the relative humidity. A method for deodorizing odor gas, which comprises suppressing the formation of mist, and then heating the combined and mixed odor gas by the high-temperature side heat exchanger 1, and then introducing the odor gas into a deodorization device.