JP2001349534A - Method of operating regenerative combustion type exhaust gas treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of operating a regenerative combustion type exhaust gas treating device preventing the melting damage to a heat reservoir due to the abnormal combustion of a harmful component with a high concentration inside a thermal storage chamber by an easy and inexpensive means. SOLUTION: At least two thermal storage chambers 4 having a heat reservoir S are provided. One end of each of the thermal storage chambers is made to communicate with a combustion chamber 2 having a heating means 3, and the other end is made to communicate with switching valves V1a to V3c. Supplying the exhaust gas containing a harmful component to either thermal storage chamber through the switching valves and exhausting the treated gas with the harmful component heated and decomposed inside the combustion chamber from the other thermal storage chamber through the switching valves are subsequently switched by driving the switching valves so as to continuously treat the exhaust gas. On the other hand, the internal temperature of the heat reservoir is detected by a temperature measuring means TR, and the detected value is compared with the measured temperature that is predetermined. When the detected value becomes higher than the set temperature, the quantity of dilute gas supplied to the exhaust gas is controlled on the basis of this detected value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for operating a heat storage combustion type exhaust gas treatment apparatus.

[0002]

2. Description of the Related Art Exhaust gas from paint drying ovens, metal heat treatment ovens, etc. includes, in addition to organic solvents, plasticizers, oils, surfactants, etc., high boiling point and high molecular weight tan components generated by thermal decomposition thereof. And harmful components such as ammonia, hydrogen sulfide, and dioxins.

Therefore, conventionally, generally, the exhaust gas containing the harmful component is supplied to a heat storage combustion type exhaust gas treatment device to decompose the harmful component by decomposing the harmful component, and then emits the harmful component to the atmosphere from an exhaust tower. .

That is, the thermal storage combustion type exhaust gas treatment device comprises at least two or more thermal storage chambers having one end communicating with the combustion chamber and a switching valve, and supplies the exhaust gas to any of the thermal storage chambers by a switching valve. After being preheated by the heat storage body in the heat storage chamber and supplied to the combustion chamber, the harmful components are heated and decomposed and the harmless process gas is passed through another heat storage chamber, and the heat is exchanged with the heat storage body to lower the temperature. Release to the atmosphere from exhaust tower.

When a predetermined time has elapsed, the switching valve is switched to supply a low-temperature exhaust gas from a heat storage chamber having a heat storage body heated by the processing gas in the previous step, and preheat the exhaust gas. A process of supplying a high-temperature processing gas to a heat storage chamber having a cooled heat storage body, lowering the temperature of the processing gas, and dispersing the processing gas to the atmosphere is repeated.

The heat storage body is formed by stacking a plurality of ceramic heat storage materials having a honeycomb structure, by stacking ceramic or metal spherical heat storage materials at a predetermined height, and further by forming a plurality of ceramic heat storage materials. It is configured by cutting a metal or metal pipe into a predetermined length.

[0007]

Since the harmful components are not composed of a single component but composed of a plurality of components having various ignition temperatures, high-temperature treatment is required in the preceding process due to the concentration fluctuation of the harmful components in the exhaust gas. When exhaust gas with a high concentration of harmful components is supplied to the heat storage chamber heated by the gas, the amount of combustion of harmful components with a low ignition temperature in the heat storage body increases,
There has been a problem that the temperature of the heat storage body abnormally rises to 1400 ° C. or more and the heat storage body is melted and damaged.

In order to solve the above problem, a harmful component concentration measuring means is provided in the exhaust gas supply duct, and dilution air is supplied into the exhaust gas supply duct based on the measured value to control the harmful component concentration within a predetermined range. However, if such a measuring means is provided, there is a problem that the equipment configuration becomes complicated and expensive.

Therefore, conventionally, an abnormal temperature increase in the combustion chamber is detected by measuring the temperature of the combustion chamber, the temperature of the processing gas in which harmful components in the exhaust gas are thermally decomposed, and the supply temperature of the exhaust gas. When the above was found, the dilution gas was supplied to the exhaust gas supply duct to prevent the heat storage body from being melted, and the thermal efficiency of the heat storage body was monitored.

However, the harmful component having a low ignition temperature ignites and burns when the temperature reaches or exceeds a predetermined temperature due to heat exchange with the heat storage body. The temperature measurement items (combustion chamber temperature, temperature of the processing gas at the inlet and outlet of the regenerator) are measurement items outside the regenerator, so it is not possible to accurately detect abnormal temperature rise in the regenerator. However, there is a problem that there is not much effect on the prevention of melting.

Accordingly, the present invention provides a heat storage medium based on abnormal combustion by indirectly detecting the occurrence of abnormal combustion from the temperature of the heat storage medium and making the supply amount of the dilution gas into exhaust gas variable. It is an object of the present invention to provide a method of operating a regenerative combustion type exhaust gas treatment apparatus which prevents a melting damage accident.

[0012]

According to the present invention, in order to achieve the above object, at least two heat storage chambers having heat storage bodies are provided, and one end of each of the heat storage chambers is communicated with a combustion chamber having heating means. The other end is communicated with a switching valve, exhaust gas containing harmful components is supplied to any one of the heat storage chambers through a switching valve, and a processing gas obtained by heating and decomposing harmful components in the combustion chamber is supplied from another heat storage chamber. A method for operating a regenerative combustion type exhaust gas treatment apparatus for continuously treating exhaust gas by sequentially switching exhaust through a switching valve by driving the switching valve,
Detecting the internal temperature of the heat storage body, comparing the detected value with a predetermined set temperature, and when the detected value is higher than the set temperature, the supply amount of the dilution gas to the exhaust gas based on the detected value. It is intended to be controlled.

Further, the internal temperature of the heat storage element is detected at a plurality of locations, and when at least one of the detected values becomes higher than a set temperature determined at each detection position, the temperature of the dilution gas is determined based on the highest detected value. The supply amount to the exhaust gas may be controlled.

The internal temperature of the heat storage element is compared with a predetermined set temperature, and when all the measured internal temperatures are lower than the set temperature, the exhaust gas of the dilution gas is determined based on the highest detected internal temperature. May be controlled so as to reduce the supply amount to the fuel cell.

[0015] The internal temperature of the heat storage element is compared with a predetermined set temperature, and when all the measured internal temperatures are lower than the set temperature, the predetermined supply amount of the diluent gas is maintained. Is also good.

The internal temperature of the heat storage body is compared with a predetermined set temperature, and when all the measured internal temperatures are lower than the set temperature, the supply of the dilution gas to the exhaust gas is stopped. Good.

Further, a purge gas supply step may be provided next to the step of supplying the exhaust gas to the heat storage chamber to prevent the exhaust gas from being mixed into the discharged processing gas.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment, in which 1 shows a regenerative combustion type exhaust gas treatment apparatus, in which a combustion chamber 2 provided with a burner 3 as a heating means and at least two combustion chambers each having one end communicating with the combustion chamber 2 (FIG. in three) regenerators 4 having a heat storage body S of (4A, 4B, and 4C), said communicated with the other end of the regenerator, in either the exhaust gas from the exhaust gas supply duct P ₁ regenerator the first switching valve V ₁ a to be supplied to the 4, V ₁ b, V ₁ c and the process of combustion deodorization process gas in the combustion chamber 2 from the other regenerator 4 gas exhaust duct P ₂
Switching valves V ₂ a, V ₂ b, V ₂ c for exhausting gas to the outside and third switching valves V ₃ a, V ₃ for supplying purge gas to the remaining heat storage chamber 4
b, V ₃ c. The switching valve may be constituted by one rotary valve having a plurality of passages for each heat storage chamber.

Further, any one of the heat storage chambers,
The central portion of the heat storage chamber 4A disposed in the heat storage body S is provided with a temperature measuring means T _R, the temperature measurements at the temperature measuring means T _R Do exceeds a predetermined set temperature, or lowered,
So as to control the opening degree of the control valve V ₄ of the dilution gas supply pipe P ₃ provided in the exhaust gas supply duct P _1.

Furthermore, the process is a gas exhaust duct P ₂ is provided an exhaust fan F, on the downstream side of branch duct P ₄ is provided in the exhaust fan F, the branch duct P ₄ is the third switching valve V ₃ a, V ₃ b and V ₃ c are used as purge gas.

Next, an operation method of the regenerative combustion type exhaust gas treatment apparatus having the above-described configuration will be described. The inside of the combustion chamber 2
Combustion rate of the burner 3 on the basis of the measured temperature values of the temperature measuring means T _B provided in the combustion chamber 2 is controlled and held at about 850 ° C..

The first switching valve V ₁ a and the second switching valve V ₂
c, the third switching valve V ₃ b and the on-off valve V ₅ provided in the branch duct P ₄ are opened, and the other is closed to drive the exhaust fan F, and exhaust gas (for example, containing an organic solvent from a paint drying furnace, etc.) exhaust gas), the first from the exhaust gas supply duct P ₁ changeover valve V ₁
a, it reaches the combustion chamber 2 via the first heat storage chamber 4A, where the organic solvent and the like are thermally decomposed. Thereafter, the processing gas passes through the third heat storage chamber 4C, is cooled by the heat storage body S of the heat storage chamber 4C, and cools down to about 230 ° C., and then flows from the second switching valve V ₂ c through the processing gas exhaust duct P ₂ to the exhaust tower. 5 to the atmosphere.

A part of the processing gas reaches the second heat storage chamber 4B through the branch duct P ₄ and the third switching valve V ₃ b by the exhaust fan F, and the exhaust gas remaining in the heat storage body S Is purged into the combustion chamber 2.

Each of the switching valves is operated for a predetermined time (for example, when the temperature at which the processing gas exits the regenerator S is about 230 ° C.).
(The time required to become).

That is, a predetermined time (for example, one minute) elapses.
The first switching valve V₁a, the second switching valve V_Twoc, 3rd cut
Valve change V_Threeb is closed, the first switching valve V₁c, second switching valve V_Twob
And third switching valve V_Threea is opened, and it becomes processing gas in the previous process.
Exhaust gas is supplied to the heat storage element S of the third heat storage chamber 4C, which is further heated.
After being supplied and preheated, it is thermally decomposed in the combustion chamber 2 and
From the second heat storage chamber 4B purged in the previous process
Processing gas exhaust duct P _TwoThrough the exhaust tower 5 to the atmosphere
Is done. On the other hand, a purge gas is supplied to the first heat storage chamber 4A.
The exhaust gas supplied and remaining in the heat accumulator S is
The combustion chamber 2 will be purged. After that, switch off the switching valve
Alternatively, the processing gas is exhausted from the first heat storage chamber 4A, and the second heat storage chamber
Exhaust gas is supplied from 4B and purge gas is supplied to the third heat storage chamber 4C.
And then repeat the process.

When the concentration of the harmful components of the exhaust gas is within the normal range, the temperature of the heat storage body S in each of the heat storage chambers 4A, 4B and 4C on the combustion chamber side is about 800 ° C., and the temperature on the switching valve side is about 800 ° C. Is about 200 ° C. when the exhaust gas is supplied and about 230 ° C. when the processing gas is exhausted. Therefore, the temperature near the center of the heat storage body provided in the heat storage chamber 4 is about 500 to 600 ° C.

On the other hand, if a high concentration of oil mist is contained in the exhaust gas, the oil mist usually reaches the ignition temperature in the regenerator S because the self-ignition temperature is as low as 250 to 300 ° C. However, a rapid rise in temperature (about 1400 ° C. or more) causes the heat storage body S to be melted.

[0028] Thus, the heat storage body is disposed in the first regenerative chamber 4A at the temperature measuring device T _R provided in the first regenerative chamber 4A S
Temperature (the temperature at the center) is detected, and the detected temperature is 6
When the temperature is higher than 50 ° C., the concentration of harmful components in the exhaust gas increases, and it is considered that abnormal combustion has occurred, and the control valve V ₄ of the dilution gas supply pipe P ₃ starts to be opened. The valve opening of Step ₄ is set to 100%, and the concentration of harmful components in the exhaust gas supplied to the heat storage chamber 4 is reduced to prevent abnormal combustion. Further, the control valve V ₄ When the temperature in the regenerator S by opening the control valve V ₄ is lowered below 650 ° C. intended to be closed (see FIG. 3A).

In the above description, the opening of the control valve V ₄ is continuously controlled in proportion to the temperature in the heat storage element S.
The opening of the control valve V ₄ is 30% at 650 ° C. and 50% at 700 ° C.
%, And may be controlled stepwise at 750 ° C. to 100% (see FIG. 3B). Further, although a part of the processing gas is used as the purge gas, it may be air supplied separately.

Furthermore, in the embodiment, the one, for example, has been controlling the opening of the control valve V ₄ at a temperature of the center portion of the heat storage body S which is disposed in the first regenerative chamber 4A, in the central portion Not limited to this, the internal temperature is detected at a plurality of locations, and one of the temperatures is set at a set temperature (for example, 7
00 ° C., the switch valve side, for example when it becomes 600 ° C.) or higher, it may be controlled hottest opening degree of the control valve V ₄ correspond to those of the detected internal temperature. Each regenerator 4A, 4B, the temperature measuring means T _R provided 4C of the heat storage body S, the control valve V ₄ by detecting the temperature in the regenerator S
May be controlled.

Incidentally, in the case where the concentration of the harmful component in the exhaust gas is within a predetermined range suitable for maintaining the temperature of the combustion chamber 2 at a predetermined value, and the equipment does not supply the diluent gas during the steady operation, the above-mentioned explanation is given. As described above, when the internal temperature of the heat storage body S becomes higher than a predetermined set temperature, a diluent gas is supplied.
The supply of the dilution gas may be stopped when the temperature becomes lower than the set temperature. However, for example, the concentration of harmful components such as organic solvents contained in the exhaust gas from a paint drying furnace (not shown) is always high, and when this exhaust gas is supplied as it is to the regenerative combustion type exhaust gas treatment device 1, the temperature of the combustion chamber 2 becomes a predetermined value. It is clear that the temperature cannot be maintained at the preset temperature (the temperature is too high), and in the case of a facility that must always supply a constant amount of dilution gas so that the combustion chamber temperature maintains the preset temperature, the internal temperature of the heat storage element S If the temperature becomes higher than the predetermined set temperature, the supply amount of the diluent gas is further increased, and thereafter, the supply amount is reduced to the supply amount of the diluent gas during the steady operation in accordance with the decrease in the internal temperature of the heat storage element S. Alternatively, the supply amount of the diluent gas during the steady operation may be maintained when the internal temperature becomes lower than a predetermined set temperature regardless of the internal temperature of the heat storage element S. At this time, the internal when the measured value of the temperature is more, adjustment to the supply amount of the opening degree of the control valve V ₄ corresponds to the highest temperature of the internal temperature in the regenerator S (decrease)
Control. In the above control, when the supply amount is reduced in accordance with the decrease in the internal temperature of the heat storage unit S up to the supply amount of the dilution gas during the steady operation, the supply amount of the dilution gas may be continuously reduced, It may be decreased stepwise for each predetermined temperature range.

[0032] Figure 2 shows a second embodiment, provided with a branch pipe P ₅ leading to the exhaust supply duct P ₁ is branched from the downstream of the exhaust fan F of the processing gas exhaust duct P _2, the branch pipe P ₅ the control valve V ₄ provided, is obtained by supplying a part of the processing gas by controlling an opening degree of the temperature measuring means T _R by the control valve V ₄ exhaust gas as a diluent gas. As described above, by circulating and using a part of the processing gas as the diluent gas, the amount of gas radiated from the exhaust tower 5 can be suppressed by separately supplying air as the diluent gas.

In each of the above-described embodiments, the purge gas is supplied to the heat storage chamber 4 to which the exhaust gas has been supplied in the previous step, and the exhaust gas containing harmful components remaining in the heat storage chamber 4 and the heat storage body S is converted into the following. Although the emission of the harmful components to the outside air is prevented by preventing the harmful components from being discharged when the process gas is discharged, it is not always necessary to supply the purge gas when the required removal rate of the harmful components is low.

[0034]

As is apparent from the above description, claim 1
According to the invention of the present invention, paying attention to the fact that the temperature in the heat storage body fluctuates depending on the concentration of the harmful component, the concentration of the harmful component in the exhaust gas is installed in the heat storage body without using an expensive concentration measurement means. In addition, since the diluent gas is supplied into the exhaust gas supply duct in response to temperature changes, it is possible to prevent erosion of the heat storage body and the equipment is inexpensive, and it can be easily applied to existing thermal storage combustion type exhaust gas treatment equipment. can do.

According to the second aspect of the present invention, since the temperature in the heat storage body is detected at a plurality of locations, abnormal combustion in the heat storage body can be grasped more accurately, and accurate dilution gas supply can be performed. Can be.

Furthermore, according to the third to fifth aspects of the present invention, the supply amount (suppression amount) of the diluent gas is controlled even after the internal temperature of the heat storage becomes lower than the set temperature. Not only can this be prevented, but it can be maintained at a predetermined value up to the temperature of the combustion chamber of the heat storage combustion type exhaust gas treatment device.

Furthermore, according to the invention of claim 6, it is possible to almost completely prevent the emission of harmful components into the air irrespective of the concentration of harmful components in the exhaust gas.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a heat storage combustion type exhaust gas treatment apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a second embodiment of a heat storage combustion type exhaust gas treatment apparatus to which the present invention is applied.

FIGS. 3A and 3B are diagrams showing states of a heat storage chamber temperature and a control valve opening degree.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1: heat storage combustion type exhaust gas treatment device, 2: combustion chamber, 3: heating
Means, 4 (4A, 4B, 4C): heat storage chamber, F: exhaust fan
N, P₁... Exhaust gas supply duct, P_Two… Processing gas exhaust duct
G, P_Three... Dilution gas supply pipe, P_Four, P_Five... Branch pipe, V₁a ~
V₁c, V_Twoa to V _Twoc, V_Threea to V_Threec ... Switching valve, V_Four… System
Oben, S ... heat storage element.

Claims (6)

[Claims] An exhaust gas containing harmful components, wherein at least two heat storage chambers having a heat storage body are provided, one end of each of the heat storage chambers is connected to a combustion chamber having a heating means, and the other end is connected to a switching valve. Is supplied to any one of the heat storage chambers through a switching valve, and the processing gas obtained by thermally decomposing harmful components in the combustion chamber is exhausted from another heat storage chamber through a switching valve by driving the switching valve sequentially. In the operation method of the regenerative combustion type exhaust gas treatment device for switching and continuously treating the exhaust gas, the internal temperature of the heat storage body is detected, and the detected value is compared with a predetermined set temperature. A method for operating a regenerative combustion type exhaust gas treatment apparatus, characterized in that when it becomes high, the supply amount of dilution gas to exhaust gas is controlled based on the detected value. 2. The internal temperature of the heat storage element is detected at a plurality of locations, and when at least one of the detected values becomes higher than a set temperature set at each detection position, the temperature of the dilution gas is determined based on the highest detected value. The method for operating a regenerative combustion type exhaust gas treatment apparatus according to claim 1, wherein a supply amount to the exhaust gas is controlled. 3. An internal temperature of the heat storage element is compared with a predetermined set temperature. When all the measured internal temperatures are lower than the set temperature, the dilution gas is determined based on the highest detected internal temperature. The method for operating a regenerative combustion type exhaust gas treatment apparatus according to claim 1 or 2, wherein the supply amount to the exhaust gas is controlled to be reduced. 4. A method for comparing the internal temperature of the heat storage body with a predetermined set temperature, and maintaining a predetermined supply amount of the dilution gas when all the measured internal temperatures become lower than the set temperature. The method for operating the regenerative combustion type exhaust gas treatment apparatus according to claim 1 or 2, characterized in that: 5. A method for comparing the internal temperature of the heat storage element with a predetermined set temperature, and stopping the supply of the dilution gas to the exhaust gas when all the measured internal temperatures are lower than the set temperature. The method for operating a heat storage combustion type exhaust gas treatment apparatus according to claim 1 or 2, wherein: 6. The method according to claim 1, further comprising a step of supplying a purge gas after the step of supplying exhaust gas to the heat storage chamber.