JPS59122811A - Automatic control method for industrial waste material melting furnace - Google Patents

Abstract

PURPOSE:To suppress creation of a change in a furnace pressure occasioned by variation in an amount of cooling combustion exhaust gas, by a method wherein the amount of combustion exhaust gas exhausted is varied in a direct-proportional correlation which is previously set according to a change in the amount of cooling combustion exhaust gas supplied. CONSTITUTION:Based on information from a controller 27 for the amount of cooling combustion exhaust gas supplied, a control instruction is transmitted to a controller 30 for adjusting a pressure in a furnace by a feed-forward type controller 31. Through automatic control of a damper 16, the amount of combustion exhaust gas exhausted from a furnace 3 is varied in a direct-proportional correlation previously set according to a change in the amount of cooling combustion exhaust gas supplied, the furnace is brought into a condition in which a change in a pressure in a furnace resulting from a change in the amount of cooling combustion exhaust gas supplied is decreased, and the furnace pressure is restored to a set range for a short time. This permits control of variation in a furnace pressure occasioned by a change in the amount of cooling combustion exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves forming a high-temperature hearth in the lower part of the furnace by burning carbon-based combustible materials, supplying industrial waste or its intermediate processed material to the high-temperature hearth, and melting it. The molten material is taken out of the furnace from the lower part of the high-temperature hearth, and a part of the flue gas discharged from the upper part of the furnace is cooled and then supplied to the upper part of the high-temperature hearth. The detected furnace temperature is adjusted to be maintained within a set range by a feedback type automatic temperature control mechanism, and the detected furnace pressure is maintained within a set range by a feedback type automatic pressure control mechanism. This article relates to an automatic control method for industrial waste melting furnaces.

The above control method was previously proposed in Japanese Patent Application No. 147089 of 1982, and is designed to control the temperature of the flue gas above the high-temperature hearth by supplying cooled flue gas into the furnace to ensure sufficient combustion of unburned gas. It is possible to maintain a low level while effectively preventing NOx generation and dust adhesion to the inner wall of the furnace.
By adjusting the pressure inside the furnace, an appropriate amount of high-temperature gas can be supplied to the molten material removal path, and the molten material can be discharged smoothly without being hindered by cooling and solidification.

However, there was room for improvement in the following points.

However, when the amount of cooled combustion exhaust gas supplied into the furnace is changed, especially when the change is sudden and wide, the furnace pressure fluctuates greatly, and the feedback type automatic pressure regulation mechanism is busy. Chattering occurs in the furnace pressure, and it takes a long time to return the furnace pressure to within the set range. However, there was a drawback that it was difficult to sufficiently achieve smooth and reliable discharge of the molten material.

In view of the above-mentioned circumstances, an object of the present invention is to effectively suppress fluctuations in furnace pressure due to changes in the amount of cooling combustion exhaust gas.

The characteristic configuration of the automatic control method for an industrial waste melting furnace according to the present invention is that the feedforward automatic The pressure regulating mechanism changes the flue gas emissions with a preset direct proportional correlation in accordance with changes in the amount of cooled flue gas supplied, and adjusts the flue gas emissions so that the detected furnace pressure is maintained within the set range. The furnace pressure can be automatically adjusted by both the feedback type automatic pressure adjustment mechanism and the feedforward type automatic pressure adjustment mechanism.

The effects of the characteristic means of the present invention are as follows. In other words, when the furnace temperature rises and the cooled combustion exhaust gas supply amount is increased, K1-1, the combustion exhaust gas emission amount is increased simultaneously with the operation to increase the supply amount, and the furnace temperature is lowered and the cooled combustion exhaust gas When the supply amount is reduced, the amount of change in the combustion exhaust gas emissions is increased as the fluctuation in the cooling combustion exhaust gas supply amount increases, so that the combustion exhaust gas emissions are reduced simultaneously with the operation to reduce the supply amount. In order to increase the furnace pressure, the feedforward automatic pressure regulating mechanism adjusts the furnace pressure according to a preset block according to the characteristics of the melting furnace.

As a result, furnace pressure fluctuations associated with automatic furnace temperature adjustment can be reduced or almost eliminated, and feedback type
In order to eliminate the chatter in the furnace pressure that accompanies the operation of the J pressure regulating mechanism, or to absorb fluctuations in the furnace pressure in a short period of time, overall, the specified furnace pressure can be maintained accurately and reliably, and the melting By more effectively preventing and preventing troubles such as coke, etc. flying out due to excessive supply of high-temperature gas to the material discharge path, and melting problems caused by insufficient supply of high-temperature gas to the molten material discharge path, the industry can be improved. It is now possible to reliably melt and process waste.

Next, we will show examples using drawings.

Coke and industrial waste are supplied into the vertical furnace 434 from the hopper (2) by alternately or simultaneously using the double dampers (la) and (11)), and are filled into the lower part of the furnace. The coke layer is combusted by air supplied from the primary tuyere (4) to form a high-temperature hearth c5), and the waste (61) is heated and melted in the upper part of the high-temperature hearth (6), and the molten material is , the high-temperature hearth (5) is allowed to flow down the gap, and taken out from the lower part of the high-temperature hearth (5) to the outside of the furnace through a discharge passage (71).

Most of the combustion exhaust gas rising from the high-temperature hearth (5) is transferred from the exhaust gas path (81) connected to the upper part of the furnace to the exhaust heat boiler (91).
, dust removal saike o :/ [101% air preheater (Il
l, desulfurization equipment 0211 wet dust removal equipment aj1 exhaust blower
(141 in that order and discharged into the atmosphere, and a part of the combustion exhaust gas is also discharged into the atmosphere from the discharge passage (7) to keep the melt warm. It9, air preheater 01) K' The combustion air supplied from the blower wholesaler to the primary tuyere (4) is preheated to maintain the temperature of the high-temperature hearth (6) at a high enough temperature to melt the industrial waste. 3) Based on the information from the furnace pressure detection weapon at the top, the controller automatically operates the damper spider to adjust the furnace pressure and appropriately adjust the proportion of combustion exhaust gas supplied to the exhaust gas path 1B+ and the exhaust path (7). Set.

The secondary blade 00η and the tertiary tuyere (I81 to the high temperature hearth (51
Air for combustion of 1 combustible gas is supplied to the upper and lower parts of the furnace + 3) to completely burn the unburned gas from the waste material 161, and the combustion exhaust gas is sent to the exhaust gas path (8) K. Combustion of fuel gas is dispersed throughout the space above the high-temperature hearth (6), suppressing a rise in temperature within the furnace due to a drop in flame temperature, and preventing NOx generation and dust adhesion to the inner wall of the furnace.

The controller (207L) based on the information from the flowmeter (19a)
) Flowing from busy! 'The control valve (21JL) is automatically operated to maintain the amount of combustion air supplied from the second tuyere (4) to the high-temperature hearth (6) almost constant, and also to maintain one flow rate (1
9b), controller (2ob), flow valve (21
b) Maintain the air supply amount for combustible gas combustion from (tertiary tuyere Q8 with zero action) almost constant, and
o) and on the downstream side of the wet dust remover +131.
&Based on the information from the meter Jl■ that detects the oxygen gas concentration of the exhaust gas, the flow control valve (GLC) is activated by the controller (20G).
) is automatically operated to adjust the amount of air supplied from the secondary tuyere Q for combustible gas combustion so that the oxygen gas concentration of the mackerel exhaust gas is maintained within the set range, for example, about 2 cm. The amount of air supplied should be adjusted to be just the right amount, and the amount of coke should not be consumed more than necessary. In addition, the air supply amount ratio from the secondary and tertiary tuyere (Iη, the sea bream is both tuyere αη,
70 to 80% of the total supply from the aal to the secondary tuyere (1'6) and 30 to 20% to the tertiary tuyere (181
It is desirable to set the settings so that they are supplied from the respective sources.

Secondary tuyere (17), secondary tuyere for cold exhaust gas directly above it (
23a), and further upper secondary tuyere for cold exhaust gas (
23b), the combustion exhaust gas after being sufficiently cooled by the wet dust remover Qj is passed through the regulating valves (24a), (24b), (2
As well as distributing and supplying at an appropriate distribution ratio by the action of 4c),
Based on the information from the flowmeter (2) that detects the combustion exhaust gas temperature in the vicinity of the flow meter and the exhaust gas path (81 population), the flow tm control valve (2BIt) is automatically operated by the controller gradient to detect the thermometer mother. Adjust the total supply amount of cooled combustion exhaust gas t to maintain the temperature at 11 [I:, for example, about 90060.
Prevents ox generation and dust adhesion to the furnace inner wall.

Based on the information from the cooling flue gas supply controller, the feedforward controller C11) sends an operation command to the furnace pressure feeding controller ■, and automatically controls the damper wholesaler to control the amount of cooled flue gas supplied. The range of flue gas emissions from the furnace (31) is restored with a predetermined direct proportional correlation commensurate with the change in .

More specifically, at the same time as the change in the amount of cooled flue gas supplied, or at a timing slightly earlier or later than that, the change in the amount of cooled flue gas is controlled while keeping the furnace pressure fluctuations associated with changes in the amount of cooled flue gas supplied to the side. When the supply amount increases, the opening degree of the damper is increased, and conversely, when the supply amount decreases, the opening degree is decreased.Moreover, the change in the opening degree with a large change in the supply amount is also large. The reactor pressure is precisely maintained in a state that allows good reactor operation by the cooperation of the feed-forward reactor pressure control based on the information from the controller 131) and the feed-forward reactor pressure control based on the information from the controller 131). be.

The industrial wastes inputted from the hopper (2) include, for example, sewage sludge, municipal waste incineration ash, tire scraps, waste catalysts, etc., or intermediate treatments thereof.

Next, another example will be shown.

The cooled combustion exhaust gas may be supplied above and below the high-temperature hearth (6) at one, two, or four or more locations above and below the furnace (3). Air may be supplied from the same tuyere or from separate tuyeres, and in order to effectively suppress the local temperature rise of the flame, if it is supplied from the same tuyere, it does not matter whether the tuyeres are upper or lower. In addition to coke, suitable carbon-based combustible materials such as anthracite briquettes and graphite electrode scraps can be used to form the high-temperature hearth.

The specific configuration for adjusting the amount of combustion gas supplied so that the furnace temperature detected at an appropriate position is maintained within an appropriate setting range can be changed in design as appropriate, and these can be adjusted using a feedback type automatic temperature control mechanism. (26, 27, 28) and burn it completely. In addition, the specific configuration of the valve that adjusts the amount of combustion exhaust gas discharged from the furnace (3) so that the furnace pressure detected at an appropriate position is maintained within an appropriate setting range can be changed as appropriate, and these can be changed using a feedback method. Collectively referred to as automatic pressure regulating mechanism (29, 30, 16). In addition, 1 automatic temperature controller 1ft, (26,27
, 28), the specific structure for changing the amount of combustion exhaust gas with an appropriately set correlation can be changed as appropriate, and the feedforward automatic pressure regulation mechanism (31 , 30, 16).

[Brief explanation of the drawing]

The drawing is a flow sheet of an example of an apparatus used in the method of the present invention. (3)...Furnace, (S)...High temperature hearth,
(2!, 27.28)---Feedback type automatic temperature regulation mechanism, (29,30,16)---Feedback type automatic pressure regulation mechanism, (31,30,16)...・
・Feedforward automatic pressure regulation mechanism.

Claims (1)

[Claims] A high-temperature hearth (5) is located at the bottom of the furnace for combustion of carbon-based combustible materials.
The industrial waste or its intermediate treatment product is supplied to the high humidity hearth (5) and melted, and the molten material is taken out of the furnace (3) from the lower part of the high temperature hearth (51). After cooling a part of the combustion valve gas discharged from the upper part of the high-temperature hearth 1B), a part of the combustion valve gas discharged from the upper part of the high-temperature hearth 1B) is supplied to the above-mentioned high-temperature hearth 1B).
8] The CX detection furnace temperature is adjusted to be maintained within the set range, and the amount of combustion exhaust gas discharged from the furnace (3) is controlled by the feedback type automatic pressure regulation mechanism (29, 30, 16). An automatic control method for an industrial waste melting furnace that adjusts the setting range gK to be maintained, the automatic temperature control mechanism (26
, 27, 28), the feedforward automatic pressure regulating mechanism (31, 30, 16) An automatic control method for an industrial waste melting furnace characterized by changing the amount of combustion exhaust gas discharged.