CN105008802B - The EGR gas supply control method of grate furnace and grate furnace - Google Patents

Abstract

The present invention provides a recirculation exhaust gas supply control method of a grate furnace and a grate furnace capable of greatly reducing the _NOx concentration at the furnace outlet without increasing the CO concentration. The recirculated exhaust gas from the front side is supplied to the rear from the front ceiling wall, and the recirculated exhaust gas from the rear side is supplied to the front from the rear wall or the rear ceiling wall. Measure the temperature distribution in the combustion chamber to obtain the position of the combustion position on the grate in the front and rear direction relative to the preset reference range. Compared with the reference range, the combustion position is divided into the front case, the rear case and the case within the reference range, and the distribution ratio of the recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side is changed according to each situation.

Description

Recirculation exhaust gas supply control method for grate furnace and grate furnace

technical field

The present invention relates to a recirculation waste gas supply control method of a grate furnace and a grate furnace, in particular to a recirculation waste gas supply control method of a grate furnace which is used for garbage combustion and the technical problem of reducing CO and _NOx in the waste gas. and a grate furnace capable of proper recirculation exhaust gas feed control.

Background technique

Patent Document 1 discloses a method for suppressing nitrogen oxides ( Hereinafter referred to as "NO _x ") method of operation.

In addition, Patent Document 2 discloses an operation method for suppressing CO generation by supplying an appropriate amount of secondary air to the secondary combustion chamber of the grate furnace and supplying recirculation exhaust gas to the secondary combustion chamber.

In addition, Patent Document 3 discloses a method of acquiring an ignition position (combustion start position) and a burnout position using an infrared camera to perform position control such as the ignition position.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. Showa 59-44513

Patent Document 2: Japanese Patent Laid-Open Publication No. Heisei 5-113208

Patent Document 3: Japanese Patent No. 3916450

Contents of the invention

(1) Technical problems to be solved

As disclosed in Patent Document 1, compared with the case where only secondary air is supplied, _NOx can be suppressed by supplying the _recirculated exhaust gas. In the case of lowering the target (for example, a strict target value of 20 ppm), it is difficult to achieve the target only by controlling the supply amount of the recirculated exhaust gas. In addition, if the supply amount of the recirculated exhaust gas is controlled to reduce NO _x , the CO concentration will increase, so it is difficult to control to achieve the target.

An object of the present invention is to provide a recirculation exhaust gas supply control method of a grate furnace and a grate furnace capable of significantly reducing the _NOx concentration at the furnace outlet without increasing the CO concentration.

(2) Technical solution

Based on the recirculation exhaust gas supply control method of the grate furnace of the present invention, the recirculation exhaust gas supply is controlled for the grate furnace, the grate furnace is provided with a lower primary combustion chamber supplied with primary air, and a secondary air supply chamber. The upper secondary combustion chamber and a plurality of grates arranged at the bottom of the primary combustion chamber. The indoor supply of recirculated exhaust gas is characterized in that the recirculated exhaust gas from the front side is supplied from the top wall of the front side toward the rear, and the recirculated exhaust gas from the rear side is supplied forward from the rear wall or the rear side ceiling wall, and the primary combustion is measured at the same time Indoor temperature distribution, with respect to at least one of the combustion start position and the burnout position on the grate, obtains what position is in the front and rear direction relative to a preset reference range, and at least one of the combustion start position and the burnout position is the same as the reference position The ratio is divided into at least three cases: the front case, the rear case, and the case within the reference range, and the distribution ratio of the recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side is changed according to each case.

In addition, in the present invention, when there is no need to distinguish the primary combustion chamber and the secondary combustion chamber, they are simply referred to as combustion chambers.

In addition, the grate furnace according to the present invention is characterized in that it includes a lower primary combustion chamber supplied with primary air, an upper secondary combustion chamber supplied with secondary air, and a plurality of furnaces installed at the bottom of the primary combustion chamber. The primary combustion chamber has a front wall provided with a hopper, a top wall on the front side, a rear wall and a top wall on the rear side, and recirculation waste gas is supplied to the primary combustion chamber; the grate furnace is equipped with a recirculation waste gas supply device, Temperature distribution measurement device and control device, the recirculation exhaust gas supply device supplies the recirculation exhaust gas from the front side to the rear from the top wall on the front side, and supplies the recirculation exhaust gas from the rear side to the front from the rear wall or the rear top wall; The temperature distribution measurement device measures the temperature distribution in the primary combustion chamber; the control device controls the combustion to reduce the CO concentration and _NOx concentration, and the control device has a combustion position calculation unit and a recirculation exhaust gas control unit, and the combustion position calculation unit is determined by the temperature The output data of the distribution measurement device acquires the temperature distribution in the primary combustion chamber to calculate at least one of the combustion start position and the burnout position; At least one of the burnout position and the burnout position, the recirculated exhaust gas control unit acquires what position is in the front and rear direction relative to the preset reference range, and at least one of the combustion start position and the burnout position is classified as being forward compared to the reference position The distribution ratio of the recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side is changed according to each of the three cases of the case of , the case of the rear and the case of the case of being within the reference range.

In the present invention, firstly, the recirculation exhaust gas is supplied into the primary combustion chamber from the front side and the rear side for optimal control. Also, in order to find out what the current combustion state is, a reference range for the combustion start position and/or the burnout position is set in advance. The combustion start position and burnout position on the grate can be obtained by measuring the temperature distribution in the combustion chamber. The temperature distribution in the primary combustion chamber is preferably measured by an infrared camera. The grate is divided into a drying section, a combustion section, and a post-combustion section from the front side. Generally, combustion starts from the final position of the drying section to the front side of the combustion section, and after the combustion section is roughly burned, the post-combustion section burn out.

In the present invention, in order not to increase the CO concentration, the _NOx concentration at the furnace outlet can be greatly reduced. Focusing on the combustion position (combustion start position and/or burnout position) on the grate that changes from time to time, the current combustion position is acquired. Where is the position in the front-rear direction, the combustion position is at least divided into three cases: a case where it is forward, a case where it is behind, and a case where it is within the reference range compared with the reference range. By classifying such cases, it can be seen that when the combustion position is at the front, the CO concentration tends to increase more than when the combustion position is within the reference range or at the rear, and it is necessary to perform control to suppress the increase of CO. That is, when the combustion position is advanced, different control is performed than in other cases, so that appropriate control can be performed, and the _NOx concentration can be significantly reduced compared with the case where no distinction is made, and an increase in the CO concentration can be prevented.

When distinguishing the situation, for the case where the combustion start position is near the front but the burnout position is near the rear, as "wide area", it is preferable to perform different control from the front, within the reference range, and rear. When it is divided into the four situations of the front, the reference range, the rear and the wide area, usually the front case is set to a different distribution ratio from the other three cases. For the reference range, the rear and the wide area For the three situations, set two or three of them to the same distribution ratio as required.

As a specific control method, it is preferable to control to reduce the amount of recirculated exhaust gas from the front side while increasing the amount of recirculated exhaust gas from the rear side when the combustion start position is earlier than the reference range. , increase the amount of recirculated exhaust gas from the front side, while reducing the amount of recirculated exhaust gas from the rear side.

In this way, the _NOx concentration can be greatly reduced regardless of the combustion start position, and the increase in the CO concentration can be suppressed when the combustion start position where the CO concentration increases is earlier.

The distribution ratio of the recirculated exhaust gas is, for example, set to about 30/70 to 40/60 when it is in the front, and set to about 50/50 to 40/60 in other cases. Values other than the distribution ratio of recirculated exhaust gas can be set appropriately. For example, the ratio of recirculated exhaust gas is set at 10-35%, the primary air ratio is set at 0.7-1.2, and the total air ratio is set at 1.1-35%. 1.40, the temperature at the exit of the primary combustion chamber is set at 900-1100°C, the combustion efficiency at the exit of the primary combustion chamber is set at 80-98%, the temperature at the upstream side of the secondary combustion chamber is set at 850-1100°C, etc.

In the present invention, it is more preferable to measure the combustion state by using a radiation thermometer installed in the secondary combustion chamber to measure the temperature in the combustion chamber. The recirculated exhaust gas amount from the rear side and the recirculated exhaust gas amount from the rear side are reduced at the same time when the combustion state is milder than the preset reference state.

By using an infrared camera, it is possible to measure the surface temperature of the layer to be burned, and to determine the distribution ratio of the recirculated exhaust gas from the front side to the recirculated exhaust gas from the rear side according to the combustion position (combustion start position and/or burnout position) control. In addition, by using a radiation thermometer, it is possible to measure the temperature in the combustion chamber, that is, the combustion state of the object to be combusted. When the combustion state is more intense than the reference state, the amount of recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side are simultaneously increased. amount, when the combustion state is milder than the reference state, the amount of recirculated exhaust gas from the front side and the amount of recirculated exhaust gas from the rear side can be reduced at the same time, so that the _NOx concentration can be greatly reduced, and it can be performed with higher accuracy. Controls to prevent CO concentration increases.

In addition, when incineration is carried out when the incinerator is garbage such as municipal waste, the combustion start position and burnout position vary, and it is difficult to adjust the combustion start position by controlling the supply of recirculated exhaust gas. Therefore, it is necessary to change the combustion start position and In the case of the burnout position, it is preferable to change the position by manipulating at least one of the dust feeding amount and the grate speed.

When the combustion start position and the burnout position change, in the case where the combustion start position and the burnout position are both ahead of the reference range, it is preferable to implement at least one of reducing the amount of dust and increasing the grate speed in the drying section, so that at least one of them The direction moves to the rear side of the reference range.

Regarding the combustion start position and the burnout position, it is difficult to simultaneously reduce CO and NO _x when both are ahead of the reference range. In this case, the combustion start position is changed while changing the distribution ratio of the recirculated exhaust gas. and the burnout position are shifted to a side where CO and _NOx are likely to be simultaneously reduced (at least one of them is on the rear side of the reference range), whereby more preferable control for simultaneously reducing CO and _NOx can be performed.

(3) Beneficial effects

According to the recirculation exhaust gas supply control method of the grate furnace and the grate furnace of the present invention, it is possible to perform appropriate control by controlling differently when the combustion start position is at the front and when the combustion start position is within the reference range and at the rear. Compared with the case where no distinction is made, the _NOx concentration can be significantly reduced, and the CO concentration can also be prevented from increasing.

Description of drawings

FIG. 1 is a diagram showing one embodiment of a grate furnace according to the present invention.

Fig. 2 is a block diagram showing main parts of a control device for a grate furnace.

It is a figure which shows an example of the control result of a grate furnace, wherein (a) shows an example of the case where appropriate control was performed, and (b) shows an example of the case where appropriate control was not performed.

Fig. 4 is a diagram showing three cases where combustion start positions are different in the grate furnace according to the present invention, and an appropriate control state in each case. Among them, (a) shows the case where the combustion start position is forward, (b) shows the case where the combustion start position is within the reference range, and (c) shows the case where the combustion start position is behind.

Fig. 5 is a gas flow diagram showing the combustion exhaust gas when the distribution ratio of the recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side is changed in the case where the combustion position is near the front, where (a) shows a gas flow without proper control An example of the case, (b) shows an example of the case where appropriate control is performed, respectively.

Fig. 6a shows a case where the combustion position is at the front in a diagram showing changes in the state of refuse on each grate when the combustion position is different.

Fig. 6b shows the case where the combustion position is within the reference range in the graph showing the state change of the garbage on each grate when the combustion position is different.

Fig. 6c shows the case where the combustion position is behind in the graph showing the state transition of the garbage on each grate when the combustion position is different.

Fig. 6d shows the case where the combustion position is in a wide area in the diagram showing the state change of the garbage on each grate when the combustion position is different.

Explanation of reference signs

1 grate furnace

2 primary combustion chambers

3 secondary combustion chamber

4a, 4b, 4c, 4d grates

6 into the hopper

10 Recirculation exhaust gas supply

11 front wall

12 Front top wall

13 back wall

14 Rear top wall

15 Infrared camera (temperature distribution measuring device)

16 radiation thermometer

20 Controls

21 Combustion position computing unit

22 Combustion state computing unit

23 Dust control department

24 Grate speed control unit

26 Recirculation Exhaust Gas Control Section

detailed description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the left side in FIG. 1 is referred to as the front side, and the right side in FIG. 1 is referred to as the rear side.

Fig. 1 schematically shows an embodiment of a grate furnace according to the present invention. The grate furnace 1 is a facility for incinerating garbage such as municipal waste, and is formed in such a manner that a lower primary combustion chamber 2 for supplying primary air is connected to an upper secondary combustion chamber 3 for supplying secondary air.

At the bottom of the primary combustion chamber 2, a plurality of grates 4a, 4b, 4c, 4d are arranged. A plurality of grates 4a, 4b, 4c, 4d are divided into a drying section grate 4a, a first combustion section grate 4b, a second combustion section grate 4c, a post-combustion section grate 4d, and the drying section grate 4a It is the part that is at the front side and dries the garbage by the heat in the furnace; the first combustion section grate 4b and the second combustion section grate 4c are at the rear side of the drying section grate 4a and make the dried garbage The main combustion part that is ignited; the post-combustion section grate 4d is located at the rear side of the combustion section grate 4b, 4c and the part that completely burns the combustion residue.

Each grate 4a, 4b, 4c, 4d is movable in the front-rear direction by the grate driving device 5, thereby moving the refuse to the rear side.

The primary combustion chamber 2 has the top wall 14 of the front wall 11, the front side, the rear wall 13 and the rear side, and the opening between the top wall 12 of the front side and the top wall 14 of the rear side is to lead to the secondary combustion chamber. 3 entrances. The front top wall 12 is located above the drying section grate 4a.

The front wall 11 of the primary combustion chamber 2 is provided with an input hopper 6 for inputting garbage to be incinerated, and a pusher (dust feeding device) 7 for supplying the garbage to the grate 4a of the drying section.

Primary air for combustion is supplied to each grate 4a, 4b, 4c, 4d by an air supply device 8 having a blower 8a. Secondary air is supplied to the secondary combustion chamber 3 through the secondary air supply nozzle 9 .

Recirculation exhaust gas (abbreviated as "EGR" in FIG. 1 ) is supplied into the primary combustion chamber 2 by a recirculation exhaust gas supply device 10 . Nozzles 10 a for supplying recirculated exhaust gas from the front are provided at multiple positions on the entire front top wall 12 , and nozzles 10 b for supplying recirculated exhaust gas from the rear are provided at multiple positions on the entire rear wall 13 . The recirculated exhaust gas discharged from the secondary combustion chamber 3 is supplied into the primary combustion chamber 2 through these nozzles 10a, 10b in the direction of the arrow.

Preferably, the supply direction of the recirculated exhaust gas from the front top wall 12 is 15° to 15° downward relative to the horizontal direction, and the supply direction of the recirculated exhaust gas from the rear wall 13 is preferably from the horizontal direction to 15° upward relative to the horizontal direction. 20° up. The recirculation exhaust gas may be supplied from the rear ceiling wall 14 instead of the rear wall 13 for supply from the rear side.

The amount of dust supplied by the pusher 7 to the grate 4a of the drying section, the moving speed of each grate 4a, 4b, 4c, 4d moved by the grate driving device 5, the air supply device 8 to the primary combustion chamber 2 The amount of primary air supplied, the amount of recirculated exhaust gas supplied from the front ceiling wall 12 and the rear wall 13 , etc. are controlled by the control device 20 shown in FIG. 2 .

Above the primary combustion chamber 2, an infrared camera (temperature distribution measuring device) 15 for measuring the temperature distribution in the primary combustion chamber 2 is arranged on the rear top wall 14 above the rear combustion section grate 4d.

A radiation thermometer (pyrometer) 16 for measuring the temperature in the combustion chamber is installed in the secondary combustion chamber 3 . The temperature in the combustion chamber can be measured by the radiation thermometer 16, and thus the combustion state (flame state) of the garbage can be judged.

If the recirculation waste gas is supplied to the primary combustion chamber 2 from the front top wall 12 and the rear wall 13 respectively, the combustion waste gas from the garbage layer is close to the front top wall 12 side and the rear wall 13 side respectively, and the primary combustion chamber 2 as a whole serves as a combustion chamber. Space is used efficiently. The combustion exhaust gas on the side near the front top wall 12 mainly contains a precursor substance (NH ₃ ) of NO _x and combustible gas. The combustion exhaust gas near the rear wall 13 mainly contains combustible gas (CO) generated from fixed carbon and oxygen, and hardly contains precursor substances of NO _x . Therefore, CO can be sufficiently combusted without the presence of the NO _x precursor substance on the side of the rear wall 13 . Therefore, the combustion exhaust gas near the front ceiling wall 12 and the combustion exhaust gas near the rear wall 13 are mixed in the secondary combustion chamber 3, and the combustion temperature is gradually increased. Thereby, the amount of _NOx can be reduced.

In the case where the influence of the recirculated exhaust gas jet flow from the front side is relatively strong, the _NOx precursor substances and combustible gases are concentrated on the front wall 11 side, and as a result, the _NOx precursor substances at the inlet of the secondary combustion chamber 3 increases, and the temperature of the secondary combustion chamber 3 rises, so the amount of NO _X produced increases. Conversely, when the influence of the recirculated exhaust gas jet flow from the rear side is relatively strong, the NO _X precursor material flows to the rear wall 13 side, and the NO X precursor material flows to the rear wall 13 side, and the NO _X precursor The substance becomes _NOx , and as a result, even in this case, the amount of _NOx produced increases.

Therefore, by appropriately controlling the supply amounts of the recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side, the amount of generated NO _x can be reduced.

The main points obtained by thermal fluid analysis using the general-purpose software Fluent Ver. 6.3 are shown in Figs.

[Table 1]

In addition, in Table 1, η refers to the combustion efficiency, which is obtained by the following formula.

η=1-△HnFn/HIFI

△Hn: low-level calorific value of unburned combustible components at the outlet of the primary combustion chamber [kJ/kg], Fn: mass flow rate of passing gas at the exit of the primary combustion chamber [kg/h], HI: low-level calorific value of inflowing combustible components [kJ/kg], FI: mass flow rate of inflow combustible components [kg/h].

Fig. 3(a) shows an example of the case where appropriate control is performed, and low _NOx and low CO combustion is realized with the CO concentration at the outlet of the secondary combustion chamber 3 being 0.6 ppm and the _NOx concentration at the furnace outlet being 16 ppm.

FIG. 3( b ) shows an example of a case where appropriate control is not performed (influence of jet flow of recirculated exhaust gas from the rear side is strong). The temperature distribution of Figure 3(b), compared with Figure 3(a), the temperature of the combustion exhaust gas entering the secondary combustion chamber 3 from the rear side of the primary combustion chamber 2 increases, and the CO concentration at the outlet of the secondary combustion chamber 3 is 0.3 ppm, the _NOx concentration at the furnace outlet is 35ppm, which has the problem of low CO but high _NOx .

In Fig. 4, (b) shows a state where combustion is carried out within the reference range, and the NO The amount of _X is 9 ppm, and the amount of CO is 0.1 ppm, which is low _NOx and low CO combustion (refer to the combustion position "reference range" in Table 1). In addition, the recirculation exhaust gas ratio was 30.4% with respect to the exhaust gas at the furnace outlet, the primary air ratio was set to 0.89, and the secondary air ratio was set to 0.15.

4( a ) and ( c ) show the appropriate control state performed when the combustion positions (combustion start position and burnout position) are different. The combustion start position is closer to the front side in (a) and closer to the rear side in (c) than in (b) within the reference range, whereby it can be distinguished that the combustion position is front, within the reference range, and rear. In the front case shown in Figure 4(a), the amount of NO _X is 7ppm, and the amount of CO is 2.4ppm (refer to the distribution ratio 35/65 of the combustion position "front" in Table 1), and in Figure 4(c ) in the rear case, the NO _X amount is 8 ppm, and the CO amount is 0.2 ppm (refer to the case where the combustion position is "rear" in Table 1).

In FIG. 5 , (a) shows the combustion gas streamline when the distribution ratio is set as front side 50/rear side 50 when the combustion position is front, and (b) shows the distribution ratio when the combustion position is front. Let it be the combustion gas flow line in the case of the front side 35/rear side 65. According to Figure 5(a), the distribution ratio is front side 50/rear side 50, compared with the proper conditions, the recirculated exhaust gas from the front side is relatively increased, and the combustion gas is strongly moved closer to the front side, as a result the primary combustion chamber 2 The combustion efficiency at the outlet decreases, and the CO concentration and NH concentration at the outlet of the secondary combustion chamber ₃ increase (refer to the distribution ratio of the combustion position "front" in Table 1 is 50/50). In this regard, according to Fig. 5 (b), by setting the distribution ratio as the front side 35/rear side 65, it becomes an appropriate condition, and it is difficult to make the combustion gas close to the front side. As a result, the combustion efficiency of the outlet of the primary combustion chamber 2 is improved, The CO concentration and the NH ₃ concentration at the outlet of the secondary combustion chamber 3 are reduced (refer to the distribution ratio of the combustion position "front" in Table 1 is 35/65).

Fig. 6a to Fig. 6d show the state changes of the garbage on each grate when the burning positions are different. Figure 6a corresponds to the front, Figure 6b corresponds to the reference range, Figure 6c corresponds to the rear, and Figure 6d corresponds to the wide area. In Fig. 6a to Fig. 6d, each grate 4a, 4b, 4c, 4d is composed of 7, 8, 8 and 9 grate blocks, respectively, and there are a total of 32 grate blocks. The three curves shown in each figure respectively represent the moisture ratio in the garbage, the ratio of volatile components (pyrolysis gas) in the garbage, and the ratio of fixed carbon in the garbage from the left side. When classifying the combustion positions, the state in which the pyrolysis gas generation areas in Fig. 6b are accommodated between the eighth and fifteenth positions is taken as a reference. Then, for example, as shown in FIG. 6a, the situation where the generation start position of pyrolysis gas, that is, the combustion start position is at the position in front of the seventh block is set as “front”, and as shown in FIG. 6b, the combustion start position is set at the seventh to The case of the 10th block is defined as "within the reference range", and as shown in FIG. 6c, the case where the combustion start position is behind the 10th block is defined as "rearward". Usually, since the burnout position moves back and forth according to the combustion start position, the combustion start position can be used to distinguish the situation, and the burnout position can also be used. In addition, in addition to the cases of "front", "within the reference range" and "rear", as shown in Figure 6d, there are also cases where the combustion start position is near the front and the burnout position is near the rear, and this case is referred to as "wide range". , more preferably referred to as a different control than the other three cases.

The strength of the recirculated exhaust gas jet is affected by the burning position (combustion start position and/or burnout position) and combustion state (flame position or flame state) of the garbage on the grate 4a, 4b, 4c, 4d. That is, it is necessary to control the recirculation exhaust gas from the front side and the recirculation exhaust gas from the rear side supplied to the primary combustion chamber 2 according to the combustion position of the garbage on the grates 4a, 4b, 4c, and 4d and the combustion state of the garbage. During control, preferably as shown in Fig. 6a to Fig. 6d, the combustion start position and/or the burnout position are distinguished based on any one of front, reference range, rear and wide area.

Furthermore, as shown in FIG. 4 , when the combustion position is forward, it is preferable to reduce the amount of recirculated exhaust gas from the front side and increase the amount of recirculated exhaust gas from the rear side. In addition, when the combustion position is located at the rear, it is only necessary to increase the amount of recirculated exhaust gas from the front side and decrease the amount of recirculated exhaust gas from the rear side. Also in the case where the combustion position is behind, the same control as the case where the combustion position is within the reference range can be performed.

As shown in FIG. 2 , the control device 20 has a combustion position calculation unit 21, a combustion state calculation unit 22, a dust feeding amount control unit 23, a grate speed control unit 24, an air supply amount control unit 25, and a recirculation exhaust gas control unit 26, The combustion position computing unit 21 acquires the temperature distribution in the primary combustion chamber 2 from the output data of the infrared camera 15 to calculate the combustion position; the combustion state computing unit 22 calculates the combustion status from the output data of the radiation thermometer 16 The dust feeding amount control part 23 controls the dust feeding amount to the drying section grate 4a; the grate speed control part 24 controls the moving speed of each grate 4a, 4b, 4c, 4d; the air supply amount control part 25 controls the supply amount of air; the recirculation exhaust gas control unit 26 controls the supply amount of recirculation exhaust gas.

Combustion position calculation part 21 is based on the output of infrared camera 15, calculates the temperature in primary combustion chamber 2, and for combustion position (combustion start position and/or burnout position), progress situation is divided into reference range, front, rear and Any one of the wide areas, and output the situation classification information to the recirculation exhaust gas control unit 26 .

For the acquisition of the combustion start position and the burnout position, as described in Patent License No. 3916450, as long as the imaging data of the infrared camera 15 is processed into temperature distribution data whose color is thicker, the temperature is higher, and viewed from the input hopper 6 side, the The position at which the area above the specified temperature (combustion start temperature) reaches the specified value is obtained as the combustion start position, and when viewed from the ash discharge port 17, the position at which the area above the specified temperature (burnout temperature) reaches the specified value is taken as the burnout position. Just get it.

The recirculated exhaust gas control section 26 is composed of a distribution ratio control section 27 which acquires an appropriate distribution ratio of the recirculated exhaust gas from the front side and the recirculated exhaust gas from the rear side, and supplies the The recirculation exhaust gas supply device 10 issues an instruction to achieve the distribution ratio; the supply amount control unit 28 obtains the appropriate supply amount of the recirculation exhaust gas from the front side and the recirculation exhaust gas from the rear side, and supplies the recirculation exhaust gas supply device 10 issues instructions to achieve the supply.

From the combustion position calculation unit 21 to the distribution ratio control unit 27 of the recirculation exhaust gas control unit 26, the relevant combustion position (combustion start position and/or burnout position) is sent as any one of the reference range, the front, the rear and the wide area. The situation distinguishes the information. The distribution ratio control unit 27 acquires the distribution ratio of the recirculated exhaust gas according to a table stored in advance, and controls the distribution ratio of the recirculated exhaust gas based on this.

As for the control content, as described above, if the combustion position is within the reference range, there is no need to change it, and the control at A/B which is the reference distribution ratio is continued. Also, in the case where the combustion position is at the front, the amount of recirculated exhaust gas from the front side is decreased by a predetermined amount α (>0), while the amount of recirculated exhaust gas from the rear side is increased by the same amount α, and the distribution ratio is set to It is (A-α)/(B+α). In addition, in the case where the combustion position is at the rear, the recirculated exhaust gas amount from the front side is increased only by a predetermined amount β (≥0), while the recirculated exhaust gas amount from the rear side is decreased by the same amount β, and the distribution ratio is set to It is (A+β)/(B-β). In addition, in the case where the combustion position is a wide area, the amount of recirculated exhaust gas from the front side is decreased by a predetermined amount γ (≥0), while the amount of recirculated exhaust gas from the rear side is increased by the same amount γ, and the distribution ratio Let it be (A-γ)/(B+γ).

On the other hand, the supply amount control unit 28 of the recirculation exhaust gas control unit 26 is sent from the combustion state calculation unit 22 to the reference state, ratio, etc., in which the measurement value obtained by the radiation thermometer 16 related to the combustion state is within a predetermined range. Arbitrary information on a state that is severe from the reference state and a state that is less severe than the reference state. The supply amount control unit 28 acquires the supply amount of the recirculation exhaust gas according to a table stored in advance, and controls the supply amount of the recirculation exhaust gas based on this.

Regarding the control content, if the combustion state of the garbage is the reference state, there is no need to change it, and the control at A/B which is the reference distribution ratio is continued. In addition, when the waste burning state is more severe than the preset reference state, the amount of recirculated exhaust gas from the front side and the amount of recirculated exhaust gas from the rear side are both δ (>1) times, so that the overall supply amount Increase. Also, when the waste burning state is milder than the reference state, the amount of recirculated exhaust gas from the front side and the amount of recirculated exhaust gas from the rear side are both ε(<1) times, and the supply amount is reduced as a whole.

Further, the combustion position computing unit 22, when the obtained situation is classified as the front side, sends an instruction to the dust feeding amount control unit 23 to reduce the dust feeding amount, and at the same time instructs the grate speed control unit 24 to raise the drying section grate. 4a's movement speed. As a result, the combustion position moves to the rear side (direction to be accommodated within the reference range).

In this way, according to the grate furnace 1 provided with the control device 20, the combustion position and combustion state of the garbage are measured and quantified, and based on this value, the amount of recirculated exhaust gas from the front side and the recycled exhaust gas from the rear side are respectively controlled. amount, thereby increasing the CO concentration at the outlet of the secondary combustion chamber 3, the _NOx concentration at the furnace outlet can be greatly reduced.

Industrial Applicability

Used in grate furnaces for waste combustion, etc., where the technical problem is to reduce CO and NO _X in the exhaust gas, since the NO _X concentration at the furnace outlet can be greatly reduced without increasing the CO concentration, it can help to improve the grate furnace. Furnace performance.

Claims (14)

1. an EGR gas supply control method for grate furnace, carries out recirculation to grate furnace The control of waste gas supply, described grate furnace possesses the primary combustion of the bottom being fed with primary air Room, it is fed with the secondary combustion chamber on the top of auxiliary air and is arranged at the bottom of primary zone Multiple grates in portion, primary zone have be provided with input the antetheca of hopper, the roof of front side, Rear wall and the roof of rear side, to primary combustion indoor supply EGR gas, it is characterised in that

The EGR gas from front side is rearward supplied, from rear wall or rear side from the roof of front side Roof forwards supplies the EGR gas from rear side, measures primary combustion indoor temperature simultaneously Distribution, about the burning starting position on grate and at least one party in after-flame position, obtains Where it is in go fore-and-aft direction relative to reference range set in advance, with benchmark position Putting and compare, in burning starting position and after-flame position, at least one party is at least divided into forward feelings Condition, situation rearward and the situation these three situation in reference range, change according to each situation Become the distribution ratio of the EGR gas from front side and the EGR gas from rear side.

The EGR gas supply control method of grate furnace the most according to claim 1, It is characterized in that, control as follows: when the situation that burning starting position is more forward than reference range Under, reduce the amount of recirculated exhaust gas from front side, improve the EGR gas from rear side simultaneously Amount, when burning starting position than reference range rearward in the case of, improve following again from front side Ring exhausted air quantity, reduces the amount of recirculated exhaust gas from rear side simultaneously.

The EGR gas supply control method of grate furnace the most according to claim 1 and 2, It is characterized in that, in the case of burning starting position is forward compared with reference range, further It is divided into the situation forward compared with reference range in after-flame position and situation rearward, according to various feelings Condition changes the distribution ratio of the EGR gas from front side and the EGR gas from rear side.

The EGR gas supply controlling party of grate furnace the most according to claim 1 and 2 Method, it is characterised in that measure primary combustion indoor Temperature Distribution by infrared camera.

The EGR gas supply controlling party of grate furnace the most according to claim 1 and 2 Method, it is characterised in that be arranged on the indoor radiation thermometer of second-time burning by use and measure institute State primary zone and described second-time burning indoor temperature, measure fired state, at burning shape In the case of state is fiercer than normal condition set in advance, improve following again from front side simultaneously Ring exhausted air quantity and the amount of recirculated exhaust gas from rear side, at fired state than base set in advance In the case of quasi-state relaxes, reduce from the amount of recirculated exhaust gas of front side and from rear simultaneously The amount of recirculated exhaust gas of side.

The EGR gas supply controlling party of grate furnace the most according to claim 1 and 2 Method, it is characterised in that in order in the burning starting position on traveling grate and after-flame position extremely A few side, changes at least one party in dust quantity and grate speed.

The EGR gas supply control method of grate furnace the most according to claim 6, It is characterized in that, in the situation that burning starting position and after-flame position are all forward than reference range Under, perform reduce to dust quantity and improve at least one party in dryer section grate speed so that at least one Direction ratio reference range side shifting rearward.

8. a grate furnace, it is characterised in that it possesses the one of the bottom being fed with primary air Secondary combustor, it is fed with the secondary combustion chamber on the top of auxiliary air and being arranged on and once fires Burning the multiple grates bottom room, primary zone has and is provided with the input antetheca of hopper, front side The roof of roof, rear wall and rear side, to primary combustion indoor supply EGR gas,

Described grate furnace possesses EGR gas feedway, temperature distribution measuring apparatus and control Device, described EGR gas feedway rearward supplies from front side from the roof of front side EGR gas, forwards supplies the EGR gas from rear side from rear wall or rear side roof； Described temperature distribution measuring apparatus measures primary combustion indoor Temperature Distribution；Described control device control System burning is so that CO concentration and NO_XConcentration reduces；

Manufacture device and possess burning position operational part and EGR gas control portion, described burning position Put the operational part temperature by the output data acquisition primary combustion indoor of temperature distribution measuring apparatus It is distributed and at least one party in burning starting position and after-flame position is carried out computing；Described recirculation Wastegate control portion controls the quantity delivered of EGR gas；

About at least one party, EGR gas in the burning starting position on grate and after-flame position Control portion obtains and where is in go fore-and-aft direction relative to reference range set in advance, combustion Burn at least one party in starting position and after-flame position and be at least divided into compared with reference position forward Situation, situation rearward and the situation these three situation being in reference range, according to each feelings Condition changes the distribution ratio of the EGR gas from front side and the EGR gas from rear side.

Grate furnace the most according to claim 8, it is characterised in that EGR gas control Portion processed, in the case of burning starting position is more forward than reference range, reduces following again from front side Ring exhausted air quantity, improves the amount of recirculated exhaust gas from rear side simultaneously, compares base in burning starting position Quasi-scope rearward in the case of, improve from the amount of recirculated exhaust gas of front side, reduce simultaneously from The amount of recirculated exhaust gas of rear side.

Grate furnace the most according to claim 8 or claim 9, it is characterised in that recirculation gives up Gas control portion, in the case of burning starting position is forward compared with reference range, is further divided into Situation that after-flame position is forward compared with reference range and situation rearward, change according to various situations Become the distribution ratio of the EGR gas from front side and the EGR gas from rear side.

11. grate furnaces according to claim 8 or claim 9, it is characterised in that Temperature Distribution Measurement apparatus is infrared camera.

12. grate furnaces according to claim 8 or claim 9, it is characterised in that be also equipped with setting Put indoor in second-time burning and measure described primary zone and described second-time burning indoor temperature Radiation thermometer, control device be also equipped with by the output data of radiation thermometer fired state Carry out the fired state operational part of computing；

EGR gas control portion is fiercer than normal condition set in advance at fired state In the case of, improve the amount of recirculated exhaust gas from front side and the EGR gas from rear side simultaneously Amount, in the case of fired state relaxes than normal condition, reduces following again from front side simultaneously Ring exhausted air quantity and the amount of recirculated exhaust gas from rear side.

13. grate furnaces according to claim 8 or claim 9, it is characterised in that control device It is also equipped with to dust quantity control portion and grate speed controlling portion, described controls to dry to dust quantity control portion Dry section of grate to dust quantity；Described grate speed controlling portion controls the translational speed of each grate；For At least one party in burning starting position on traveling grate and after-flame position, change to dust quantity and At least one party in grate speed.

14. grate furnaces according to claim 13, it is characterised in that control device and exist Burning starting position and after-flame position all forward than reference range in the case of, perform by dirt What amount control portion was carried out is reduced to dust quantity and the raising dryer section stove that carried out by grate control portion At least one party in grid speed, so that at least one party is towards than reference range side shifting rearward.