JP3854477B2 - Exhaust gas temperature reduction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for reducing the temperature of exhaust gas discharged from a combustion apparatus such as a waste incinerator or a boiler, and more specifically, by reducing the temperature of the temperature-reducing water within a range of 55 ° C to 65 ° C. The hot water is rapidly evaporated to prevent solid components and alkali agent in the exhaust gas from sticking to the combustion device or exhaust gas duct. The present invention relates to an exhaust gas temperature reduction method and apparatus that can be prevented.
[0002]
[Prior art]
In general, exhaust gas discharged from a combustion apparatus such as a garbage incinerator or boiler is purified by a gas purification device and then diffused into the atmosphere.
By the way, in exhaust gas purification treatment, there are cases where the exhaust gas temperature must be reduced to an appropriate temperature, for example, about 120 ° C. to 250 ° C., depending on the type of gas purification device used. In general, exhaust gas temperature reducing devices are commonly used in which water is sprayed into exhaust gas and the exhaust gas temperature is lowered by utilizing the sensible heat of liquid, latent heat of vaporization and sensible heat of water vapor.
[0003]
FIG. 3 is a configuration diagram of a conventional general exhaust gas temperature reducing device. In the figure, 21 is an exhaust gas temperature reducing tower, 21a is an exhaust gas inlet, 21b is an exhaust gas outlet, 21c is an ash outlet, 22 is a dewarmed water tank, 23 is an injection pump, 24 is an injection nozzle, 25 is an exhaust gas temperature control device, and 25a is Low temperature exhaust gas temperature detector, 26 is a flow control valve, _GH is high temperature exhaust gas, _GL is low temperature exhaust gas, and C is ash.
[0004]
That is, in the exhaust gas temperature reducing device of FIG. 3, first, the temperature-decreasing water W is supplied from the temperature-decreasing water tank 22 by the injection pump 23 via the flow control valve 26, and passes through the injection nozzle 24 provided in the vicinity of the exhaust gas inlet 21a. The dewarmed water W is sprayed into the exhaust gas dewarming tower 21. The sprayed water rises in temperature by coming into contact with the high temperature exhaust gas _GH , and evaporates to become water vapor when it reaches the boiling point.
[0005]
On the other hand, the high-temperature exhaust gas _GH in the exhaust gas temperature reducing tower 21 is cooled by giving water sensible heat, latent heat of vaporization and sensible heat of water vapor to the sprayed water, and is cooled to a predetermined temperature. _GL is output from the exhaust gas outlet 21b to the subsequent apparatus.
[0006]
The amount of water sprayed into the exhaust gas temperature reducing tower 21 is adjusted by adjusting the opening of the flow control valve 26 by the exhaust gas temperature control device 25 based on the temperature detection signal from the low temperature exhaust gas temperature detector 25a. It is controlled. That is, when the temperature of the low-temperature exhaust gas _GL is high, the opening degree is increased, and when the temperature of the low-temperature exhaust gas _GL is low, the opening degree is decreased and the flow control of the dewarmed water is performed. The temperature of the low-temperature exhaust gas _GL derived from the exhaust gas outlet 21b by the flow control of the temperature-reducing water is maintained at a desired temperature.
[0007]
The high temperature exhaust gas _GH contains not only gaseous components but also solid components. This solid component becomes ash in the exhaust gas temperature reducing tower 21, and is discharged and recovered as ash C from the ash outlet 21c. Water W is constantly supplied to the temperature-reduced water tank 22, and the water level is adjusted to be constant.
[0008]
[Problems to be solved by the invention]
In this conventional exhaust gas temperature reducing device, since the temperature of the temperature-reduced water W is as low as about 20 ° C. to 30 ° C. even in summer, it takes about 2 to 3 seconds for the temperature-reduced water sprayed on the exhaust gas temperature reducing tower 21 to evaporate. Needed. When an exhaust gas flow containing spray water contacts the wall surface of the temperature-decreasing tower 21 or the wall surface such as a duct within a few seconds until the evaporation, water droplets often adhere to these surfaces.
[0009]
The water droplets adhering to the surface absorb the dust inside, and the dust remains adhered to the wall surface even if the water droplet evaporates. Other dust accumulated using the stuck dust as a nucleus, and a dust sticking trouble occurred on the wall surface.
[0010]
In particular, in an exhaust gas temperature reducing device in which an alkaline agent is mixed with dewarmed water to form a slurry, and this slurry is sprayed into the exhaust gas temperature reducing tower 21, when the sprayed slurry comes into contact with the wall surface before the evaporation of moisture, dust is generated. In addition, a solid substance containing an alkaline agent often adheres to the wall surface.
[0011]
This alkaline agent contains slaked lime and the like, and the solid matter that has adhered becomes gradually larger. If this solid material falls, there is a risk that the device will be damaged by a drop impact or the duct may be blocked. Due to these troubles, it has often been difficult to operate incinerators and boilers.
[0012]
Therefore, the exhaust gas temperature reduction method and the apparatus according to the present invention prevent adhesion of the temperature-reduced water to the wall surface by shortening the time required for the temperature-reduced water injected into the exhaust gas temperature-decreasing tower to evaporate, This aims to prevent dust and alkaline agent from sticking to the wall surface.
[0013]
[Means for Solving the Problems]
According to the first aspect of the present invention, combustion exhaust gas discharged from a waste incinerator or waste melting furnace is introduced into an exhaust gas temperature reduction tower, and the temperature reduction water pumped by an injection pump from an injection nozzle provided in the exhaust gas temperature reduction tower is converted into combustion exhaust gas. In the combustion exhaust gas temperature reducing method in which the temperature of the high-temperature combustion exhaust gas is reduced to 120 ° C. at the minimum by spraying in, the temperature of the temperature-reduced water is set to 55 ° C. to 65 ° C. and sprayed. This is a combustion exhaust gas temperature reduction method configured to rapidly evaporate the temperature reduction water to lower the temperature of the exhaust gas and to prevent the temperature reduction water from adhering to the wall surface of the exhaust gas temperature reduction tower.
[0014]
The invention of claim 2 introduces combustion exhaust gas discharged from a waste incinerator or waste melting furnace into an exhaust gas temperature reducing tower, and supplies water and an alkaline agent pumped by an injection pump from an injection nozzle provided in the exhaust gas temperature reducing tower. In the combustion exhaust gas temperature reducing method, the temperature of the high temperature combustion exhaust gas is reduced to 120 ° C. at a minimum by spraying the slurry temperature reducing agent formed by mixing into the combustion exhaust gas. The temperature of the temperature reducing agent is set to 55 ° C. to 65 ° C., and the water in the slurry-like temperature reducing agent is rapidly evaporated to lower the temperature of the exhaust gas. This is a combustion exhaust gas temperature reduction method configured to prevent and neutralize exhaust gas components with an alkali agent .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The lower the temperature of the temperature reducing water sprayed on the exhaust gas temperature reducing tower, the higher the heat absorption capacity of the temperature reducing water. Therefore, the temperature of the temperature-reduced water generally used is normal temperature, about 15 degreeC on average, and 20 degreeC-30 degreeC also in summer. Also, the heat-reduced water is not subjected to any treatment such as heating or cooling.
[0018]
The amount of heat that can be absorbed by the dewarmed water is the sensible heat of water until it reaches 100 ° C, the latent heat for phase change from 100 ° C water to 100 ° C water vapor, and the temperature rise from 100 ° C water vapor to water vapor of any temperature There are three types of steam sensible heat.
[0019]
On the other hand, in order to prevent dust or an alkaline agent from adhering to the wall surface, it is only necessary to prevent water droplets of the dewarmed water from adhering to the wall surface. For that purpose, it is necessary to change the temperature-reduced water into water vapor at an early stage before the temperature-reduced water adheres to the wall surface, and thus the initial temperature of the temperature-reduced water must be set.
[0020]
That is, by shortening the process of heat absorption by the water sensible heat of the reduced temperature water, an early phase change of the reduced temperature water can be realized. In other words, the change to water vapor can be accelerated by increasing the initial temperature of the dewarmed water.
[0021]
However, this reduces the amount of heat absorption per unit mass of the temperature-reduced water, so it is necessary to increase the flow rate of the temperature-reduced water in order to achieve the same amount of heat absorption in the exhaust gas temperature reduction tower. become.
[0022]
As a result of earnest research while balancing the increase in the initial temperature of the temperature-reduced water and the increase in the supply flow rate, the present inventors set the initial temperature of the temperature-reduced water to 55 ° C. to 65 ° C. It has come to be recognized that the temperature reduction of exhaust gas can be realized without fixing to the wall surface.
[0023]
There are two types of temperature reducing agents supplied to the exhaust gas temperature reducing tower: a case where only the temperature-decreasing water is used, and a case where the slurry is a mixture of temperature-reducing water and an alkali agent. In both cases, the cooling of the exhaust gas is achieved with water, so the temperature-reducing water and the slurry are set at 55 ° C to 65 ° C, thereby preventing the solid matter from sticking to the wall surface and improving the efficiency of the temperature reduction. Can be realized.
[0024]
Embodiments of an exhaust gas temperature reducing method and apparatus according to the present invention will be described below in detail with reference to the drawings.
[0025]
FIG. 1 is a configuration diagram of a first embodiment of an exhaust gas temperature reducing device according to the present invention. In the figure, 21 is an exhaust gas temperature reducing tower, 21a is an exhaust gas inlet part, 21b is an exhaust gas outlet part, 21c is an ash outlet part, 22 is a dewarmed water tank, 23 is an injection pump, 24 is an injection nozzle, and 25 is an exhaust gas temperature control device. 25a is a low-temperature exhaust gas temperature detector, 26 is a flow control valve, _GH is high-temperature exhaust gas, _GL is low-temperature exhaust gas, C is ash, and W is dewarmed water.
Since the function and effect of these members are the same as the function and effect of the members having the same reference numerals shown in FIG. 3, which is a conventional example, detailed description thereof is omitted.
[0026]
Next, members that give the features of the present invention will be described. Water W is supplied to the temperature-decreasing water tank 22 so that the temperature-decreasing water W is always stored in a constant amount. A heating device 30 is attached to the temperature-reduced water tank 22 in order to set the temperature-reduced water to a desired temperature between 55 ° C. and 65 ° C.
[0027]
As the heating device 30, not only an electric heater but also a heat exchanger using the heat quantity of an incinerator or a boiler device can be used. In this heat exchanger, the heat quantity of steam, hot water or hot water is imparted to the dewarmed water W.
[0028]
A temperature detector 32 is disposed in the dewarmed water tank 22 and constantly measures the temperature of the dewarmed water W stored. A temperature control device 34 for controlling the heating device 30 is arranged so that the measured temperature of the temperature detector 32 becomes a desired temperature between 55 ° C. and 65 ° C. described above.
[0029]
When the heating device 30 is an electric heater, an electronic control circuit that controls a heating current and a heating voltage can be used as the temperature control device 34. When the heating device 30 is a heat exchanger, the temperature control device 34 can be used. A valve control device that adjusts the flow rate of steam, hot water, or the like can be used.
[0030]
The heating device 30 is actuated by the temperature control device 34 to maintain the temperature of the dewarmed water W in the dewarmed water tank 22 at a set appropriate temperature (desired temperature between 55 ° C. and 65 ° C.). The temperature-reduced water W is sprayed from the spray nozzle 24 into the exhaust gas temperature-decreasing tower 21 through the flow control valve 26 by the operation of the injection pump 23.
[0031]
This dewarmed water W comes into contact with the hot exhaust gas _GH and absorbs the amount of heat, and rapidly becomes water vapor. The high temperature exhaust gas _GH rapidly decreases in temperature and changes to a low temperature exhaust gas _GL . The water vapor is transported to the downstream apparatus together with the low temperature exhaust gas _GL without adhering to the exhaust gas temperature reducing tower 21 or the inner wall surface of the duct (not shown).
[0032]
In the first embodiment, since the temperature-reduced water W is rapidly changed to water vapor, the water vapor does not adhere to the wall surfaces of the apparatus and the duct, and the solid components in the exhaust gas do not adhere to those wall surfaces. Therefore, the inner wall surfaces of the apparatus and the duct are always kept clean, and there is no damage due to the fall of the fixed object and the duct is not closed, so that the durability of the incinerator and the boiler apparatus can be improved.
[0033]
FIG. 2 is a configuration diagram of a second embodiment of the exhaust gas temperature reducing device according to the present invention. In the figure, 21 is an exhaust gas temperature reducing tower, 21a is an exhaust gas inlet part, 21b is an exhaust gas outlet part, 21c is an ash outlet part, 22 is a dewarmed water tank, 23 is an injection pump, 24 is an injection nozzle, and 25 is an exhaust gas temperature control device. 25a is a low-temperature exhaust gas temperature detector, 26 is a flow control valve, GH is high-temperature exhaust gas, GL is low-temperature exhaust gas, and C is ash. The effects of these members are the same as those shown in FIG. Since it is the same as the effect, the detailed description is abbreviate | omitted.
[0034]
Next, members that give the characteristics of the second embodiment will be described. An alkaline agent A such as slaked lime and water W are supplied to the mixer 36 to form a slurry S, and the slurry S is stored in the temperature reducing agent tank 28. That is, in this embodiment, the slurry S is used as a temperature reducing agent, and the temperature-reducing water consisting only of water is not used.
[0035]
The temperature reducing agent tank 28 includes a temperature detector 32 for measuring the temperature of the stored slurry S, a heating device 30 for heating the slurry, and controlling the heating device 30 to keep the slurry within a range of 55 ° C. to 65 ° C. A temperature control device 34 for setting the desired value is arranged.
[0036]
As in the first embodiment, an electric heater device or a heat exchanger can be used as the heating device 30, and an electronic control device or a valve control device can be used as the temperature control device 34.
[0037]
The slurry S is sprayed from the spray nozzle 24 into the exhaust gas temperature reducing tower 21 by the injection pump 23. Slurry S is a mixture of water W and alkali agent A. Water W lowers the temperature of the high temperature exhaust gas _GH to the low temperature exhaust gas _GL , and the alkali agent A acts to neutralize the acidic exhaust gas.
[0038]
The slurry S is set to a desired temperature between 55 ° C. and 65 ° C., and the water W contained therein is naturally set to the same temperature. Accordingly, the water W absorbs heat from the high temperature exhaust gas _GH and rapidly changes into water vapor, and this water vapor is sent to the subsequent apparatus together with the low temperature exhaust gas _GL .
[0039]
Next, the action of the alkaline agent A will be described in detail. The exhaust gas contains hydrogen chloride and sulfur oxide, and these particles are dissolved in slurry water droplets sprayed from the spray nozzle 24 to become hydrochloric acid or sulfurous acid. These acids react with an alkaline agent A such as slaked lime to form neutralized salts such as calcium chloride and calcium sulfite. These neutralized salts are recovered together with the ash C.
[0040]
As described above, when the slurry S is sprayed, the high temperature exhaust gas _GH is neutralized and at the same time the temperature can be reduced to the low temperature exhaust gas _GL , so that the exhaust gas treatment process can be shortened.
[0041]
The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications and design changes are included in the technical scope without departing from the technical idea of the present invention. Absent.
[0042]
【The invention's effect】
According to the invention of claim 1, since warm water having a temperature of 55 ° C. to 65 ° C. is used as dewarmed water, it takes a short time until it becomes water vapor, so that water droplets become water vapor before adhering to the wall surface. It becomes difficult for solid components of the exhaust gas to adhere to the wall surface of the temperature reducing tower or duct, and the durability of the exhaust gas temperature reducing device can be enhanced.
[0043]
According to the invention of claim 2, water and an alkaline agent are mixed to form a slurry, the temperature of the slurry is adjusted to 55 ° C to 65 ° C, and the temperature-adjusted slurry is used as a temperature reducing agent. The amount of heat of the exhaust gas is absorbed and the water is rapidly changed to water vapor, so that the solid component in the exhaust gas is difficult to adhere to the wall surface or the like. At the same time, the exhaust gas can be neutralized by the alkali component.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of an exhaust gas temperature reducing device according to the present invention.
FIG. 2 is a configuration diagram of a second embodiment of the exhaust gas temperature reducing device according to the present invention.
FIG. 3 is a configuration diagram of a conventional general exhaust gas temperature reducing device.
[Explanation of symbols]
21 is an exhaust gas temperature reducing tower, 21a is an exhaust gas inlet, 21b is an exhaust gas outlet, 21c is an ash outlet, 22 is a dewarmed water tank, 23 is an injection pump, 24 is a spray nozzle, 25 is an exhaust gas temperature control device, and 25a is a low temperature exhaust gas temperature. Detector, 28 is a temperature reducing agent tank, 30 is a heating device, 32 is a temperature detector, 34 is a temperature control device, A is an alkaline agent, C is ash, GH is high temperature exhaust gas, GL is low temperature exhaust gas, S is slurry, W is water with reduced temperature (water).

Claims (2)

By introducing the combustion exhaust gas discharged from the waste incinerator and waste melting furnace into the exhaust gas temperature reduction tower and spraying the temperature reduction water pumped by the injection pump from the injection nozzle provided in the exhaust gas temperature reduction tower into the combustion exhaust gas, In the method for reducing the temperature of the high temperature combustion exhaust gas to 120 ° C. at a minimum, the temperature of the temperature reduction water is set to 55 ° C. to 65 ° C., and the sprayed temperature reduction water is rapidly evaporated. It causes to lower the temperature of the exhaust gas Te, configuration and the flue gas down Yutaka method of preventing a reduced hot water adhering to the wall surface of the exhaust gas decreased cooling tower. Slurry formed by mixing combustion exhaust gas discharged from a waste incinerator or waste melting furnace into an exhaust gas temperature reduction tower and mixing water and an alkali agent pumped from an injection nozzle provided in the exhaust gas temperature reduction tower by an injection pump In the combustion exhaust gas temperature reducing method in which the temperature of the high temperature combustion exhaust gas is reduced to 120 ° C. at a minimum by spraying the temperature reducing agent in the combustion exhaust gas, the temperature of the slurry temperature reducing agent is 55 The temperature in the slurry temperature reducing agent is rapidly evaporated to lower the temperature of the exhaust gas at a temperature of from ℃ to 65 ° C., while preventing the temperature-reducing water from adhering to the wall surface of the exhaust gas temperature reducing tower and the exhaust gas component by the alkali agent A method for reducing the temperature of combustion exhaust gas, which is designed to neutralize the exhaust gas.

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