JPS61141925A - Method for utilizing waste heat of stock powder preheating apparatus - Google Patents

Abstract

PURPOSE:To enhance waste heat utilization efficiency, by shortcircuiting a part of hot gas to the exhaust gas duct, which extends from the inlet end cover of a combustion furnace to the downstream side of a preheating apparatus or the waste heat utilizing equipment of an exhaust gas system, so as to bypass one stage or more of a heat exchange stage. CONSTITUTION:The exhaust gas duct 15 reaching the waste heat utilizing equipment of a boiler 16 from a preheating apparatus 1 and the gas duct 7a in the preheating apparatus 1 are connected by a shortcircuit gas conduit 19. Because the hot gas extracted from the gas duct 7a is not used in the heat exchange with the stock powder in the downstream side from the gas extraction part and retains high temp., said hot gas is allowed to meet with the exhaust gas in the exhaust gas duct 15 to raise the temp. of the exhaust gas finally introduced into the boiler 16. Therefore, the heat recovered in the boiler 16 increases to a large extent and, at the dame time, the temp. and pressure of generated steam become high abd the power generation efficiency in a turbine is markedly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a raw material powder child heating device, such as a cyclone type multi-stage preheating device, which is installed in an apparatus for firing powdered raw materials such as cement raw materials and aluminum hydroxide. The present invention relates to a method for efficiently collecting and utilizing sensible heat.

Figure 1 shows an example of a device used when preheating and firing cement raw materials. It is composed of a preheating device 1 formed by vertically arranging calcining furnaces 2 of a combustion device A, which constitutes a heat exchange stage, a calcining furnace 3, and a clinker cooler 4. In these operations, the raw material powder A is sent from the feeder 5 into the duct 7a, heated by the hot gas rising inside the duct 7a, separated from the hot gas by the cyclone C1, and then transferred to the raw material chute t. −8a through the next gas duct l
-7b, and thereafter undergoes the same steps and is sequentially heated.

Finally, after being calcined in a calcining furnace 2 equipped with a burner 6a, it enters a separation cyclone C4, and then a doping chute 8d.
From there, it is introduced into the firing furnace 3 via the firing furnace artificial end mold 12.

High-temperature air from the cooler 4 and firing fuel from the burner 6b are introduced into the firing furnace 3, and the clinker that has been fired at high temperature enters the clinker cooler 4 and is cooled. It is carried out by. Reference numeral 9 indicates a surplus air induction fan, 10 a forced air blower, 13 an air bleed duct, 14 a square gas ventilation fan, and 15 an exhaust gas duct.

The temperature of the exhaust gas discharged from the uppermost cyclone C1 of the preheating device 1 in such a baking device is usually around 350 to 400°C, although it depends on the heat exchange method and the number of stages of the preheating device 1, and it still consumes a considerable amount of thermal energy. is left behind. Therefore, in order to use this exhaust gas sensible heat more effectively, as shown in Fig. 1, 1) exhaust heat utilization equipment such as a boiler 16 is installed in the middle of one gas tact 15, and steam is generated by heat exchange with high-temperature exhaust gas. By using this for power generation, etc., we aim to improve thermoeconomic efficiency. In addition, in order to cope with cases where the wood pipes of the boiler 16 are damaged, a bypass tuff 1-17 is provided to bypass the boiler 16, and a tamper 18a is provided on the duct 1-wood pipe 15, and a tamper 18b is provided on the bypass tuffs 1 to 17. The firing apparatus can be operated continuously by opening and closing the opening and closing operations.

However, in this conventional exhaust heat utilization method, the exhaust gas temperature in the exhaust gas duct 15 is not that high, so the boiler 1
The temperature and pressure of the steam generated in step 6 do not rise sufficiently,
The power generation efficiency of the turbine is low. Moreover, the exhaust gas from the preheating device 1 is generally used as a heat source for drying raw materials.
Only the surplus can be used for heating in the boiler 16, but as a result, the usable sensible heat of the gas is insufficient, and the efficiency of the power generation turbine is not sufficiently high.

As a way to compensate for this lack of heat, exhaust gas duct 1-1
It is possible to install a combustion chamber at the appropriate location in step 5 and supply fuel and combustion air to raise the exhaust gas temperature, but it is difficult to install a combustion section other than a calciner or calciner in terms of equipment and operation. It's also not a good thing. Moreover, when cheap coal is used as fuel, it becomes difficult to dispose of combustion residual ash generated in the combustion chamber.

The present inventor focused on the above-mentioned circumstances and conducted research to increase the sensible heat of exhaust gas and improve the heat utilization efficiency of exhaust heat utilization equipment such as boilers for power generation turbines. The present invention was completed as a result of such research, and the method consists of vertically arranging multiple stages of raw material powder collectors above the inlet end cover of a firing furnace, as shown in FIG. At the same time, the raw material powder is preheated using a preheating device which is connected by a gas duct between the raw material powder collectors and between the lowest raw material powder collector and the inlet end cover. When using the exhaust gas from the exhaust gas system as a heat source for exhaust heat utilization equipment attached to the exhaust gas system, from the upstream side of the preheating device or from the inlet cover of the firing furnace to the downstream side of the preheating device as seen in the flow direction of the hot gas. Or, by skipping one or more heat exchange stages and short-circuiting a part of the hot gas to the exhaust gas duct leading to the exhaust heat utilization equipment in the exhaust gas system, the temperature of the exhaust gas introduced from the preheating device to the exhaust heat utilization equipment can be reduced. The gist lies in increasing the.

The configuration and effects of the method of the present invention will be explained below based on the drawings, and the following are representative examples and do not limit the present invention. The technical scope of the present invention includes not only the type, structure, number of stages, etc., but also changing the design of the exhaust heat utilization equipment, etc. as appropriate.

FIG. 2 is a schematic explanatory diagram showing an embodiment of the apparatus used in the method of the present invention, and the overall configuration can be understood in accordance with the example shown in FIG. 1. The characteristic part of this example is that the exhaust gas ducts 1 to 15 from the preheating device 1 to the exhaust heat utilization equipment such as the boiler 16 and the gas duct l- (7a in the figure) in the preheating device 1 are connected to each other. Connected by a short-circuit gas conduit 19, the hot gas extracted by short-circuiting the uppermost cyclone c1 from the gas duct 7a is discharged from the cyclone Ci.
It is at the point where it is combined with JE gas and guided to the boiler 16.

That is, the hot gas extracted from the gas duct 7a is not used for heat exchange with the raw material powder on the downstream side (downstream side as seen in the gas flow direction, the same applies hereinafter) of the oil gas section, and maintains a high temperature. Therefore, when this is combined with the exhaust gas in the exhaust gas duct 15, the temperature of the exhaust gas that is finally introduced into the boiler 16 increases. Therefore, the heat recovered by the boiler 16 increases significantly, and at the same time, the temperature and pressure of the generated steam increase, so that the power generation efficiency of the turbine is significantly improved. In addition, the oil position and confluence position of hot gas are not limited to the example shown in the diagram.
Air can be extracted from the gas ducts 7b, 7c, and 7d, or directly from the artificial end mold 12 of the calcination furnace 2 or the firing furnace 3, or from multiple locations if necessary. At this time, the temperature of the hot gas is higher as it is extracted from the two liquids, so less oil is needed to raise the exhaust gas temperature to a certain level. On the other hand, the temperature of the exhaust gas changes depending on the oil content of the hot gas, and as this increases, the temperature of the exhaust gas rises by 20%. Therefore, as shown in FIG. By adjusting the amount of short-circuit hot gas using the flow rate regulator 2o according to the temperature required to efficiently operate the exhaust heat utilization equipment, the temperature of the exhaust gas introduced into the exhaust heat utilization equipment can be raised to an arbitrary temperature. can.

Furthermore, as shown, a short-circuit gas conduit 1 to an exhaust gas duct 15 is provided.
A temperature detector 21 is disposed downstream of the junction of No. 9, an opening regulator 22 is connected to the flow regulator 2o, and the detector 21 and regulator 22 are connected to a control device 23.
By controlling the amount of short-circuit gas so that the exhaust gas temperature detected by the detector 21 is a predetermined value, the temperature of the exhaust gas introduced into the exhaust heat utilization equipment can be kept as constant as possible even if the operating status of the firing equipment changes. Can be maintained. As a result, the amount of heat supplied to the waste heat utilization equipment becomes constant, its operating state becomes stable, and in the case of a power generator, a constant amount of power can be obtained at all times. Furthermore, the setting of the amount of power generation can be adjusted as necessary, and furthermore, an increase in the amount of fuel used in the firing apparatus due to short-circuiting of a part of the high-temperature gas can be minimized.

In order to prevent the raw material powder from being discharged from the preheating device into the exhaust gas system along with the short-circuit gas, a dust collector 24 is installed in the middle of the short-circuit gas pipe 19 as shown in the figure. The discharged fine powder may be captured and returned through the chute 25 to the lower heat exchange stage or the inlet end cover 12 of the calciner 2 or calciner 3.

FIG. 3 shows an embodiment of another device used in the present invention, in which the preheating device 1 does not include a calcination furnace, and the lowermost cyclone C4 is directly connected to the calcination furnace inlet end cover 12 by the gas duct 7d.
The structure is the same as the example shown in Fig. 2, except that the oil position of the hot gas and the return position of the fine powder captured by the dust collector 24 have been changed, but the number of short-circuited heat exchange stages has been changed. Because of the large number of gas pipes, the cross-sectional area of the short-circuit gas pipe 19 and the dust collector are small.
Multiple stages of dust collectors can be installed if necessary.

FIG. 4 is a main part explanatory diagram showing still another embodiment of the apparatus used in the present invention, in which the short-circuit gas conduit 19 is connected to the gas duct 7c.
and the gas duct 7a, so that a part of the hot gas extracted from the upstream side is short-circuited and flows to the downstream side. That is, in this example, the extracted hot gas merges with the gas in the duct 7a in a high temperature state without performing heat exchange in the heat exchange stage including at least the cyclones c3 and cyclones C2. The hot gas temperature increases and the exhaust gas duct finally discharged from cyclone C rises. In this way, in the present invention, the short-circuit gas conduit 19 is connected in a short-circuited manner within the preheating device 1, or between the inlet end cover of the calcination furnace 2 or firing furnace 3 and an appropriate location in the preheating device 1. It is also possible to install piping, and a part of the raw material powder can be circulated to the upper part of the preheating device together with the short-circuit gas. According to the arrangement shown in Fig. 4, the short-circuit hot gas finally passes through the cyclone C1, so there is no need to separately provide a dust collector in the short-circuit duct, and the arrangement is therefore particularly simplified, and ventilation resistance is also reduced. Because of the small cross-sectional area of the short-circuit duct, the cross-sectional area of the short-circuit duct can be small. Also in this case, the exhaust gas temperature may be adjusted by controlling the amount of short-circuited hot gas using the flow rate regulator 20.

In this way, in the present invention, a part of the high-temperature gas in the preheating device is short-circuited to the downstream side without performing heat exchange with the raw material powder, and the efficiency of preheating the raw material powder in the preheating device 1 is slightly increased. This increases the temperature of the exhaust gas at the expense of increasing the temperature of the exhaust gas, and accordingly, it becomes necessary to increase the amount of fuel used in the calciner 2 or the calciner 3. However, this increased amount of heat can be fully recovered by effective use of the exhaust heat utilization equipment due to the exhaust gas temperature of 2R, and the overall energy economy is considerably improved over the conventional method. Furthermore, since the amount of fuel originally used in the calciner 2 and the calciner 3 is increased, there is no fear that the equipment and operational burden will increase compared to the case where fuel is supplied to the exhaust gas system. In addition, even when solid fuel such as pulverized coal is used as fuel, the ash produced by combustion is consumed as part of the cement dispersion within the sintering device, so special ash processing equipment is not required.

In addition, in the present invention, it has been explained that an apparatus in which the calcining furnace 2 is omitted as shown in FIG. It is preferable to connect a calciner 2 equipped with a combustion device to the lower gas duct, and to absorb temperature changes caused by hot gas and oil in the preheater 1 by adjusting operating conditions of the calciner 2. Furthermore, in order to increase the heat utilization efficiency of the exhaust heat utilization equipment, the present invention is a method of increasing the exhaust gas temperature at the expense of preheating efficiency as described above, so when the exhaust heat utilization equipment is not operated, for example, the second The flow rate regulator 20 in FIG. 4 is fully closed to avoid short-circuiting the hot gas, and the preheating device 1 is used so as to exhibit the highest thermal efficiency.

In the internal factors, an example was shown in which one series of preheating devices was combined for one firing furnace 3, but two sets of preheating devices were combined for one firing furnace 3.
At least one of the preheating devices installed in the series or above
By applying the method of the present invention to multiple trains, it is also possible to combine the exhaust gases from multiple trains and guide them to the waste heat utilization equipment, or to add the feed material powder to the preheating device or a part of the preheating material powder into the short-circuit hot gas. It is also possible to introduce such modifications, and all design changes to this degree should be considered as implementations within the technical scope of the present invention. In addition to the boiler for power generation turbines as shown in the diagram, exhaust heat utilization equipment includes raw material drying equipment such as rotary dryers, and various auxiliary equipment for firing equipment such as raw material drying and simultaneous pulverization equipment using roller mills, ball mills, etc. This applies even when various heat demand facilities in the vicinity are used.

The present invention is generally configured as described above, but the point is that the exhaust gas temperature is increased by short-circuiting a portion of the hot gas on the upstream side to the downstream side by skipping at least one heat exchange stage. As a result, the amount of heat supplied to the exhaust heat utilization equipment was increased, and its heat utilization efficiency was significantly improved. And this increase in the amount of recovered energy is
This more than compensated for the increase in fuel used in the firing furnace, etc., and the energy economy of the entire preheating, firing, and waste heat utilization equipment was significantly improved.

The method of the present invention is simple and can be easily applied to existing equipment equipped with exhaust heat utilization equipment. Furthermore, the pressure drop in the preheating device is reduced due to the reduction in the amount of gas passing through the short-circuit heat exchange stage of the preheating device, or the circulation and accumulation of harmful components such as alkaline content in the combustion gas is reduced due to the short-circuiting gas. There are also other secondary effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus used in a known raw material powder child heating/sintering and exhaust heat utilization method, FIG. 2 is an explanatory diagram showing an example of an apparatus used in the method of the present invention, and FIG. Figure 3.4 is an explanatory view of the main parts showing another embodiment of the apparatus used in the method of the present invention. 1... Preheating device 2... Calcining furnace C~C4・
...Dissolved powder collector 3...Calcination furnace 4...Clinker cooler 7
... Gas duct 15 ... Exhaust gas duct 16 ... Exhaust heat utilization equipment 19 ... Short circuit gas conduit 20 ... Flow rate regulator

Claims (4)

[Claims] (1) A plurality of stages of raw material powder collectors are arranged vertically above the inlet end cover of the firing furnace, and between the raw material powder collectors and between the raw material powder collector at the lowest stage and the inlet end cover. At the same time, the raw powder is preheated using a preheating device which is connected by a gas duct, and at the same time, the exhaust gas from the preheating device is used as a heat source for the exhaust heat utilization equipment attached to the exhaust gas system. 1 to the exhaust gas duct from the upstream side of the preheating device or the inlet cover of the firing furnace to the downstream side of the preheating device or the exhaust heat utilization equipment of the exhaust gas system when viewed in the gas flow direction;
A method for utilizing waste heat in a raw material powder child heating device, characterized in that the temperature of the exhaust gas introduced from the preheating device to the waste heat utilization equipment is increased by skipping a heat exchange stage or more and short-circuiting a part of the hot gas. . (2) In claim 1, introducing short-circuiting hot gas into a precipitator and collecting raw material powder in the hot gas,
A waste heat utilization method in which dust-collected hot gas is returned to a suitable location in the preheating device or to the inlet cover of the firing furnace and introduced into the exhaust heat utilization equipment. (3) In claim 1 or 2, an independent heat source is provided in the lowest heat exchange stage of the preheating device, and a part of the hot gas is introduced from the preheating device into the waste heat utilization equipment. Method. (4) In any one of claims 1 to 3,
A waste heat utilization method that detects the temperature of the exhaust gas introduced into the exhaust heat utilization equipment and adjusts the amount of hot gas short-circuited using this detected temperature as an index.