JPH0566009A - Exhaust gas temperature reducer and reducing method thereof - Google Patents

Abstract

PURPOSE:To remarkably miniaturize a device by adjusting the angle of spray of a spray nozzle in response to the quantity of spray water and the flow rate of a gas and changing a spray pattern. CONSTITUTION:Exhaust gas flowing into an exhaust-gas desuperheater flows toward an upper section from the lower section of a gas-temperature reducing tower 5. Water, etc., are atomized into the gas through a valve 10b, opening and closing of which are controlled by the signal of a temperature detector 10a, from an atomizer 7 disposed to the lower section of the gas-temperature reducing tower 5. Consequently, the temperature of exhaust gas is held at a fixed value. The quantity of heat of exhaust gas is arithmetically operated from the flow rate and temperature of exhaust gas, and the angle of spray of the atomizer 7 is increased through a spray pattern controller 8 when an arithmetic value augments. The state of side-angle spray is brought, and a travel to an upper section until atomized particles are vaporized completely is shortened. When the arithmetic value of the quantity of heat of exhaust gas decreases, the angle of blowout is reduced, and the state of narrow-angle spray is brought. Accordingly, a travel in the horizontal direction until atomized particles are vaporized completely is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for reducing the temperature of exhaust gas from a waste incinerator and the like, and a water injection type gas temperature reducing device installed on the gas inlet side of a dust collector, The present invention relates to improvement of the gas temperature reduction method used.

[0002]

2. Description of the Related Art Conventionally, in dust incinerators and the like, an electric dust collector has been widely used for treating exhaust gas. However, it has become clear that the dioxin re-synthesis occurs in the electrostatic precipitator when the exhaust gas temperature reaches around 300 ° C in recent years.
As a result, the temperature of the exhaust gas introduced into the dust collector is 150 ° C to
It has become necessary to reduce the temperature to about 250 ° C. for that reason,
In many waste incinerators, a semi-dry gas temperature reducer that sprays water or slaked lime slurry into the exhaust gas to reduce the gas temperature is installed on the gas inlet side of the dust collector, and the temperature reducer outlet side. By adjusting the amount of spray water according to the gas temperature, the temperature of the gas introduced into the dust collector is automatically controlled within a predetermined temperature range.

The above-mentioned conventional semi-dry gas temperature reducer can reduce the gas temperature relatively easily and has excellent practical utility. However, many problems remain to be solved in the device. The first problem is that when the amount of water to be sprayed is large, the density of spray particles becomes high and the contact efficiency with exhaust gas deteriorates. As a result, it takes a long time for the spray particles to mix with the gas and completely evaporate. This means that the temperature reducing device becomes large in size. That is, in the case of the municipal waste incinerator, the lower calorific value of the waste greatly varies depending on the waste quality (for example, the minimum waste quality of 1500 kcal / kg to the maximum waste quality of 3000 kcal / kg). Therefore, in general, when designing a gas cooler,
The design is based on the case of incinerating the highest quality waste, and the spray nozzles are installed with a constant spray pattern in a quantity corresponding to the maximum spray water volume required. However,
When the quality of the waste to be incinerated is poor and the required amount of spray water is small, the amount of gas is small, and the spray pattern P becomes a state as shown in FIG. Will be low. As a result, the contact efficiency between the exhaust gas C and the spray particles becomes high, and the length dimension X of the spray pattern P becomes short. In FIG. 5, A is a spray nozzle, B is spray water, and C is exhaust gas. On the other hand, in the case of high-quality waste that has a low calorific value of the waste to be incinerated, the amount of spray water will inevitably increase. However, since the nozzles having a constant spray pattern are used as described above, the ejection angle α of the spray nozzle A is substantially constant regardless of the amount of spray water. Therefore, the pattern P ′ of the sprayed particles becomes a state as shown in FIG. 6 together with the increase of the gas amount,
The spray particle density Q'becomes larger than in the case of FIG. 5, the contact efficiency between the spray particles and the exhaust gas C is deteriorated, and the length dimension X'of the spray pattern P'is increased.

The second problem is that when the gas flow rate decreases,
The point is that the horizontal distance traveled by the spray particles to complete evaporation is increased, resulting in an increase in the required size from the spray nozzle to the side wall of the gas cooler and an increase in the internal diameter of the device. That is, as described above, in order to increase the evaporation efficiency of the spray particles, the spray pattern P of the spray nozzle is set as shown in FIG.
The narrow-angle spray as shown in FIG. 8 is changed to the wide-angle spray as shown in FIG. 8 to reduce the spray particle density Q and increase the contact area S (projected area) with the exhaust gas. However, in the waste incinerator, since the quality of the waste fluctuates greatly as described above, the gas flow rate also fluctuates greatly, and the gas flow rate decreases when burning low-quality waste or when reducing the combustion load of the waste incinerator. The gas flow rate also decreases. Further, the horizontal ejection speed of the spray particles ejected from the spray nozzle A becomes a substantially constant value even if the amount of spray water slightly fluctuates because the ejection angle α is substantially constant. As a result, when the waste to be incinerated is of high quality, the gas flow rate is large, and the gas flow rate is d, the distance f that the sprayed particles move to completely evaporate is as shown in FIG. The horizontal distance from the spray nozzle A to the side wall of the temperature reducer required at this time is approximately L. Note that e is the ejection velocity of the spray particles. On the other hand, when the dust is of low quality and the gas flow rate is small, and as a result, the gas flow velocity d ′ is slow, the moving direction of the spray particles is the same as the vector g ′ as shown in FIG. If the moving distance f until the particles are completely evaporated is the same as in the case of FIG. 9, the required horizontal distance L ′ from the spray nozzle A to the side wall of the temperature reducing device is L + La. That is, the horizontal distance L ′ from the nozzle A to the side wall needs to be increased by the dimension La as compared with the case where the gas flow rate is large.

As described above, in the conventional exhaust gas temperature reducing device using the spray nozzle A having a constant jet angle α, theoretically, the height of the device is X ′ in FIG. 6 and the horizontal from the side wall to the nozzle A. The direction distance may be set to L ′ in FIG. 10, but in the actual design of the temperature reducing device, if the sprayed particles collide with the side wall before the completion of evaporation, the acid gas contained in the exhaust gas causes the side wall to contact the side wall. Since severe corrosion occurs, it is necessary to secure a sufficient dimensional allowance, and the present situation is that the equipment will have a large tower diameter and tower height.

[0006]

DISCLOSURE OF THE INVENTION The present invention has the above-mentioned problems in the conventional exhaust gas temperature control devices for waste incinerators, that is, (a) the quality of waste to be incinerated is high and the amount of spray water increases. Then, the contact efficiency between the spray particles and the exhaust gas decreases, it takes time to completely evaporate the spray particles, the height dimension of the exhaust gas temperature control device becomes large, and (b) the waste to be incinerated is of low quality. When the amount of exhaust gas decreases (the amount of spray water decreases), the movement distance of the spray particles in the horizontal direction increases, and the problem that the inner diameter of the exhaust gas temperature control device increases, etc. will be solved. The present invention provides an exhaust gas temperature reducing device and an exhaust gas temperature reducing method that can significantly reduce the size of the device by adjusting the spray angle α of the spray nozzle according to the gas flow rate and changing the spray pattern.

[0007]

The present invention is directed to a vertical type gas temperature reducing tower 5 through which exhaust gas flows; and water or slaked lime slurry is sprayed into the gas temperature reducing tower 5 and its ejection angle α.
And an exhaust gas temperature control device 10 for detecting the temperature of the exhaust gas for temperature reduction and adjusting the spray amount of the slaked lime slurry by the detection signal; and the jet angle α when the heat amount of the exhaust gas increases. The spray pattern control device 8 that greatly reduces the jet angle α when the amount of heat of exhaust gas decreases is the basic configuration of the invention.

Further, the method of the present invention is an exhaust gas temperature reducing method of spraying water or slaked lime slurry by a spraying device into a gas temperature reducing tower in which exhaust gas flows to reduce the temperature of the exhaust gas. Detected, while controlling the exhaust gas temperature by adjusting the spray amount of spray water or slaked lime slurry by the detected value of the exhaust gas temperature, the exhaust gas heat amount is calculated from the exhaust gas flow rate and the detected value of the exhaust gas temperature, when the exhaust gas heat amount increases The basic configuration of the invention is to control the spraying angle α of the sprayed particles from the spraying device so as to increase, and to control the spraying angle α to decrease when the heat quantity of exhaust gas decreases.

[0009]

[Function] Exhaust gas that has flowed into the exhaust gas temperature reduction device is subjected to the removal of coarse dust in the dust separator, and then the gas temperature reduction tower 5
Flows from below to above. Water or the like is sprayed into the gas from a spraying device 7 arranged below the gas temperature reducing tower 5 through a valve 10b which is controlled to open and close by a signal from a temperature detector 10a, whereby the exhaust gas temperature is kept at a predetermined value. To be done. The heat quantity of the exhaust gas is calculated from the flow rate and the temperature of the exhaust gas, and when the calculated value of the heat quantity increases, the ejection angle α of the spray device 7 is increased via the spray pattern control device 8 and a so-called wide-angle spray state is established. This shortens the upward moving distance until the spray particles are completely evaporated.
Further, when the calculated value of the exhaust gas heat amount decreases, the ejection angle α is reduced via the spray pattern control device 8 and a so-called narrow-angle spray state is established. As a result, the moving distance in the horizontal direction until the spray particles are completely evaporated is shortened. By shortening the moving distance of the spray particles in the upward and horizontal directions, it is possible to downsize the device.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of an exhaust gas temperature reducing device according to the present invention, in which 1 is an exhaust gas inlet duct, 2 is an exhaust gas outlet duct, 3 is a dust collector, 4 is an exhaust gas temperature reducing device, and 5 is a gas reducing device. Hot tower, 5a is a current plate, 6 is a dust separator, 6a is a rotary damper, 7 is a spraying device, 8 is a spraying pattern control device, 9 is a jetting angle adjusting drive device, 9a is a motor,
9b is a gear, 9c is a rack gear, 10 is a gas temperature control device, 10a is a temperature detector, 10b is a spray water amount control valve, 1
Reference numeral 1 is a gas flow rate measuring device, 12 is a gas heat quantity calculating device, H is a high temperature exhaust gas, Ha is a low temperature exhaust gas, W is spray water, and A ₀ is spray air.

The gas temperature reducing apparatus 4 according to the present invention has a vertical gas temperature reducing tower 5 provided with a dust separator 6, and a nozzle portion protruding through the dust separator 6 into the gas temperature reducing tower 5. The spray device 7 includes a spray pattern control device 8 for adjusting the spray angle α of spray particles of the spray device 7, an exhaust gas temperature control device 10 for controlling the temperature of exhaust gas, and the like.

As shown in FIG. 2, the spraying device 7 has a nozzle cap 13 at its tip and spraying air A on its side wall.
_The outer pipe 14 having the ₀ supply hole 14a and the spray water that is inserted into the outer pipe 14 concentrically and is movably supported in the left-right direction and communicates with the inner side of the outer pipe 14 at its tip. A nozzle flare that forms an ejection port 17 of a mixture of spray water W and atomizing air A ₀ between the inner pipe 15 provided with the ejection port 15a of W and the tip of the inner pipe 15 and is fixed to the nozzle cap 13. 16
The inner pipe moving mechanism 18 and the like move the inner pipe 15 in the left-right direction via the screw 18b by swinging the inner pipe moving lever 18a. The water spray device 7
Is supplied with spray water W or slaked lime slurry from the base end opening of the inner pipe 15, and spray air A ₀ from the outer pipe 14,
The atomized spray particles are ejected from the ejection port 17. At this time, the inner pipe moving lever 18a is operated to operate the inner pipe 15
When is ejected to the left, the atomized droplets are diffused in a conical shape along the tapered surface of the nozzle flare 16 and the spray angle α of the spray water becomes wide as shown in FIG. On the contrary, when the inner tube 15 is moved to the right to narrow the gap of the ejection port 17, the atomized droplets are ejected at a higher speed, and the inner portion E is ejected as shown in FIG. It becomes a vacuum state. As a result, the ejected liquid droplets are attracted to the inner portion, and the ejection angle α becomes a narrow angle.

In this embodiment, the spraying device 7 having the same mechanism as the Japanese Patent Publication No. 60-27892 developed by the inventor of the present invention.
However, any structure may be used as long as it is a spray device capable of adjusting a so-called spray pattern by changing the jet angle α. Further, although the inner pipe moving mechanism 18 using the screw mechanism is used in the present embodiment, it goes without saying that any inner pipe moving mechanism 18 may be used.

The spray pattern control device 8 is composed of an exhaust gas temperature detector 10a, a gas flow rate measuring device 11, a gas calorific value calculation device 12, a drive device 9 for adjusting the ejection angle α, etc. The exhaust gas heat quantity is calculated from the detected temperature and the detected flow rate, and the adjustment drive device 9 is operated by the calculated value to adjust the ejection angle α of the spray device 7.

The drive unit 9 for adjusting the ejection angle α is composed of a motor 9a, a gear 9b, a rack 9c, etc., and a rack whose one end is axially supported by an inner pipe moving lever 18a of an inner pipe moving mechanism of the spraying device 7. The gear 9b is meshed with the gear 9c, and the lever 18a is operated by rotating the gear 9b by the motor 9a, whereby the ejection angle α is adjusted.

The gas temperature control device 10 is composed of a temperature detector 10a provided on the exhaust gas outlet side of the temperature reducing tower 5 and a spray water amount control valve 10b, and controls the opening / closing of the control valve 10b by a temperature detection signal. Due to the low temperature exhaust gas Ha
Temperature is automatically controlled to the set value.

Next, the operation of reducing the temperature of the high temperature exhaust gas H according to the present invention will be described. Referring to FIG. 1, high temperature exhaust gas H discharged from a refuse incinerator or the like is introduced into duct separator 6 through exhaust gas inlet duct 1, and coarse dust in exhaust gas H is first removed. After that, the exhaust gas H is rectified by the straightening plate 5.
It is rectified by a and flows into the gas temperature reduction tower 5. Further, the recovered coarse dust is appropriately discharged through the rotary damper 6a. On the other hand, fresh water W (or slaked lime slurry) having a predetermined pressure is supplied into the inner pipe 15 of the spraying device 7 through the spray water amount control valve 10b, and the spraying air A ₀ having a predetermined pressure is supplied to the spraying air supply port 14a. Air control valve 19
Supplied through. As a result, a predetermined amount of spray particles are ejected into the gas temperature reduction tower 5, mixed with the exhaust gas H and evaporated to cool the exhaust gas H.

The low-temperature exhaust gas Ha cooled by mixing with the spray particles is introduced into the dust collector 3 from the upper part of the gas temperature reducing tower 5 through the exhaust gas discharge duct 2 and is cleaned. The temperature of the cooled exhaust gas Ha is detected by a temperature detector 10a provided on the outlet side of the gas cooling tower 5, and the spray water amount control valve 10b is detected by the detection signal of the temperature detector 10a.
Of the exhaust gas Ha is controlled, which controls the temperature of the exhaust gas Ha. The flow rate of the exhaust gas Ha whose temperature has been reduced is detected by the gas flow rate measuring device 11 at the outlet side of the gas temperature reducing tower 5, and the detection signal is input to the gas calorie calculation device 12. The exhaust gas temperature signal from the temperature detection control device 9 is input to the gas heat amount calculation device 12, and the exhaust gas heat amount (gas flow rate × gas temperature × gas specific heat) is calculated, and the calculation signal is supplied to the spray device 7. It is input to the drive unit 9 for adjusting the spray angle.

The angle adjusting drive device 9 is arranged so that, if the exhaust gas heat quantity signal from the arithmetic and control unit 11 is large, the spray angle α of the spray water from the spray device 7 is large (wide-angle spray).
On the contrary, when the exhaust gas heat amount is small, the inner pipe moving lever 18a is moved so that the ejection angle α becomes small (narrow-angle spray). That is, in the present embodiment, the adjustment drive device 9 includes the rack 9c whose one end is axially supported by the inner pipe moving lever 18a, the gear 9b meshing with the rack 9c, and the motor 9a for rotating the gear 9b. When the lever 18a is moved in a predetermined direction by the rotation of the motor 9a, the inner pipe 15 is moved through the screw mechanism as described above, and the nozzle flare 16 and the outer pipe fixed to the tip thereof are formed. The gap between the nozzle cap 13 fixed to the tip of the nozzle 14 and the nozzle cap 13 increases (or decreases), and the spray angle α of the sprayed water becomes a wide angle (or a narrow angle).

In the present embodiment, the spraying device 7 and the spraying angle adjusting drive device 9 are configured as described above, but any structure may be used as long as the spraying angle α of the sprayed particles can be adjusted. Good. Further, in this embodiment, fresh water from the spraying device 7 is sprayed, but it is of course possible to spray slaked lime slurry instead of fresh water.

[0021]

According to the present invention, the spray device 7 for spraying slaked lime slurry into water into the gas temperature reduction tower 5 has a structure in which the spray angle α of spray particles can be adjusted, and the heat quantity of exhaust gas is large and large. If the spraying of reduced temperature water, etc. is required, the jetting angle α is adjusted to a large value. It is configured to do. As a result, even if the amount of dehumidified water to be sprayed is large, the density of spray particles in the spray pattern is reduced and the contact efficiency with the exhaust gas is increased, and the spray particles mix with the gas within a short time to complete evaporation. Therefore, the height of the gas temperature reducing tower 5 can be reduced. In addition, when the amount of dehumidifying water to be sprayed is small, by making the ejection angle α a narrow angle, the horizontal movement distance until complete evaporation of the spray particles is reduced, and the tower diameter of the gas desuperheater is reduced. It will be possible. INDUSTRIAL APPLICABILITY As described above, the present invention is capable of completely reducing the size of the exhaust gas temperature reducing device 4 and completely preventing the corrosion of the tower wall caused by the direct collision of the sprayed water droplets, and has an excellent practical effect. is there.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a system of an exhaust gas temperature reducing device according to the present invention.

FIG. 2 is a vertical sectional view of a spraying device used in the present invention.

FIG. 3 is an enlarged view of a nozzle portion of the spraying device in a wide-angle spraying state.

FIG. 4 is an enlarged view of a nozzle portion of the spraying device in a narrow-angle spraying state.

FIG. 5 shows an example of a spray pattern when the amount of gas is reduced in a conventional spray device having a constant spray pattern.

FIG. 6 shows an example of a spray pattern when the amount of gas is increased in a conventional spray device having a constant spray pattern.

FIG. 7 is an explanatory diagram showing an example of a narrow-angle spray pattern.

FIG. 8 is an explanatory diagram showing an example of a wide-angle spray pattern.

FIG. 9 is an explanatory diagram showing an example of the movement of spray particles when the amount of gas is large.

FIG. 10 is an explanatory diagram showing an example of movement of spray particles when the amount of gas is small.

[Simple explanation of the sign]

H High-temperature exhaust gas W Spray water A ₀ Spraying air Ha Low-temperature exhaust gas α Jet angle 1 Exhaust gas introduction duct 2 Exhaust gas discharge duct 3 Dust collector 4 Exhaust gas temperature reducing device 5 Gas temperature reducing tower 5a Rectifier plate 6 Dust separator 6a Rotary damper 7 Spraying Device 8 Spray pattern control device 9 Jet angle adjustment drive device 9a Motor 9b Gear 9c Rack 10 Gas temperature control device 10a Temperature detector 10b Spray water amount control valve 11 Gas flow rate measurement device 12 Gas calorie calculation device 13 Nozzle cap 14 Outer tube 14a Spray water supply hole 15 Inner tube 15a Air hole 16 Nozzle flare 17 Spray water jet 18 Inner tube moving mechanism 18a Inner tube moving lever 18b Screw 19 Air control valve

Claims (3)

[Claims] 1. A vertical gas temperature reduction tower (5) through which exhaust gas flows; water or slaked lime slurry is sprayed into the gas temperature reduction tower (5), and its ejection angle (α) is adjustable. A spraying device (7); an exhaust gas temperature control device (10) for detecting a reduced temperature exhaust gas temperature and adjusting the spray amount of the slaked lime slurry based on the detection signal; and increasing the jet angle (α) as the exhaust gas heat amount increases. In addition, the exhaust gas temperature control device comprising a spray pattern control device (8) that reduces the ejection angle (α) when the heat amount of the exhaust gas decreases. 2. A spray pattern control device (8), a gas flow rate measuring device (11) and a gas temperature detector (10a), and a gas calorific value computing device for computing the calorific value of exhaust gas from detected values of the gas flow rate and gas temperature ( 12) and the arithmetic unit (12)
The exhaust gas temperature reducing device according to claim 1, further comprising a drive device (9) for adjusting an ejection angle (α) according to a signal from the exhaust gas temperature reducing device. 3. An exhaust gas temperature reducing method for spraying water or slaked lime slurry by a spraying device (7) into a gas temperature reducing tower (5) through which exhaust gas flows to cool the exhaust gas, and the exhaust gas flow rate and the exhaust gas temperature. To control the exhaust gas temperature by adjusting the spray amount of spray water or slaked lime slurry according to the detected value of the exhaust gas temperature, calculate the exhaust gas heat amount from the exhaust gas flow rate and the detected value of the exhaust gas temperature, the exhaust gas heat amount calculation When the value is increased, the spraying angle (α) of the sprayed particles from the spraying device (7) is increased, and when the exhaust gas heat amount is decreased, the spraying angle (α) is decreased. Exhaust gas temperature reduction method.