JP4841011B2 - Hydrous substance combustion treatment equipment and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply a drying heat source of stable temperature to a dryer. <P>SOLUTION: This water-containing object combustion treatment facility comprises the dryer 3 for drying water-containing waste using a heat medium as the drying heat source, and a treating furnace 5 for incinerating or melting the dried waste dried by the dryer 3. When the used heat medium used by the dryer 3 is heated by heat exchange with exhaust gas in the treating furnace 5 in a first stage indirect heat exchanger 8, a second stage indirect heat exchanger 9 and a third stage indirect heat exchanger 10 and circulated and supplied again to the dryer 3, the used heat medium is circulated in the order of the first stage indirect heat exchanger 8, the second stage indirect heat exchanger 9 and the third stage indirect heat exchanger 10, while the exhaust gas in the treating furnace 5 is circulated in the order of the first stage indirect heat exchanger 8, the third stage indirect heat exchanger 10 and the second stage indirect heat exchanger 9. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a treatment facility and a method for water-containing waste such as sewage sludge and garbage that require drying prior to incineration or melting treatment.

  In recent waste treatment facilities, in response to a request for energy saving, exhaust heat generated by incineration or melting is recovered and effectively used as a heat source in the facility or as electric energy by a generator.

  For example, there is a technique disclosed in Japanese Patent Publication No. 7-24733 as an effective utilization of exhaust heat in a hydrous waste treatment facility. This prior art includes a steam direct dryer that performs drying by directly contacting steam and water-containing waste, and a combustion furnace that burns dry waste dried by the dryer, and is dried using a heat exchanger. The used steam used by the machine is heated by heat exchange with the exhaust gas of the combustion furnace, and is circulated again to the dryer.

Japanese Patent Publication No. 7-24733 JP 54-131344 A JP-A-6-26629 JP-A 61-209099

  However, if the heating medium used as the drying heat source of the dryer is configured to rely only on heat exchange with the combustion furnace exhaust gas, the temperature of the heating medium varies depending on the combustion processing amount and the temperature of the combustion furnace exhaust gas. It becomes difficult to secure a stable drying heat source.

  Then, the main subject of this invention is to enable it to supply the heat medium of the stable temperature to a dryer.

The present invention that has solved the above problems comprises a dryer that dries hydrated material using a heat medium as a drying heat source, and a combustion furnace that burns the dried material dried by the dryer, and is used by the dryer. In the hydrated material combustion treatment facility configured to heat the heat medium by heat exchange with the exhaust gas of the combustion furnace and to circulate and supply again to the dryer,
The first stage indirect heat exchanger, the second stage indirect heat exchanger, and the third stage indirect heat exchanger that perform heat exchange between the used heat medium and the exhaust gas of the combustion furnace,
The used heat medium is circulated in the order of the first-stage indirect heat exchanger, the second-stage indirect heat exchanger, and the third-stage indirect heat exchanger, while the combustion furnace exhaust gas is in the first-stage indirect heat exchanger. The indirect heat exchanger of the eye, the indirect heat exchanger of the third stage and the indirect heat exchanger of the second stage are configured to be distributed in this order.
This is a hydrated material combustion treatment facility.

  By comprising in this way, the heat medium of the stable temperature can be supplied to a dryer.

  The present invention is particularly suitable for equipment in which the heat medium is steam and the dryer is a steam direct dryer that performs drying by directly contacting the steam and the hydrated material.

On the other hand, the hydrated material combustion treatment method of the present invention performs drying of the hydrated material using the heating medium as a drying heat source, and burns the dried dried material, while generating the used heating medium used for the drying by the combustion. When heating by heat exchange with the combustion furnace exhaust gas to be used again for the drying,
Using the first stage indirect heat exchanger, the second stage indirect heat exchanger, and the third stage indirect heat exchanger that perform heat exchange between the used heat medium and the exhaust gas of the combustion furnace,
The spent heat medium is circulated in the order of the first-stage indirect heat exchanger, the second-stage indirect heat exchanger, and the third-stage indirect heat exchanger, while the combustion furnace exhaust gas is passed through the first-stage indirect heat exchanger. Indirect heat exchanger, the third-stage indirect heat exchanger and the second-stage indirect heat exchanger in order,
It is characterized by this.

  As described above, according to the present invention, a drying heat source having a stable temperature can be supplied to a dryer.

It is a front | former flow chart of the example of sludge processing equipment concerning this invention. It is a latter part flow diagram. It is an enlarged view of a waste heat recovery part. It is an expansion perspective view of an exhaust gas communicating path.

Hereinafter, the present invention will be described in detail with reference to an example of sewage sludge treatment equipment.
FIG.1 and FIG.2 has shown the flowchart of the example of the sewage sludge processing equipment to which this invention is applied. Reference numeral 1 in FIG. 1 denotes a sludge pit, and the sludge S stored therein is transferred to a hopper (not shown) by a crane (not shown) and supplied to a dryer 3 by a sludge supply pump 2 attached thereto. The

  In the dryer 3, the sludge is dried using a steam of about 400 ° C. that has been heated by heat exchange with the exhaust gas described later as a drying heat source. The dryer 3 is not of a steam direct drying type in which steam and water-containing waste are directly brought into contact as shown in the illustrated example as long as a heat medium such as steam can be circulated as a drying heat source. May be. The circulating heat medium is not limited to steam.

  The steam reduced in temperature by heat exchange with the sludge is supplied to the dust collector 3C at about 150 ° C. After the dried sludge dust is separated and recovered here, the first-stage steam described later by the steam circulation fan 3F. It is supplied to the heater 8. As the dust collector 3C, it is preferable to provide a plurality of stages of bag filters or cyclones.

  The dried sludge dried and discharged by the dryer 3 and the dried sludge dust collected by the dust collector 3C are then supplied to the melting furnace 5 by pneumatic transportation by the dried sludge transportation blower 4, and are burned and melted. Although the combustion melting furnace 5 is not particularly limited in the present invention, in the illustrated example, a vertical swirl type preliminary combustion furnace 50, a horizontal main combustion furnace 51 having one end connected to the lower end, and a slag chute at the other end. This is a naturally-cooled type composed of a saddle-type mixing cooler 53 connected via 52, and the dried sludge is blown into the upper portion of the preliminary combustion furnace 50. A burner 54 is provided in the upper portion of the pre-combustion furnace 50, and fuel such as city gas, heavy oil, kerosene, waste oil, and combustion air from the fan 55 are supplied to the burner 54. The dried sludge blown into the pre-combustion furnace 50 along the swirl direction is burned and melted by the combustion frame by the burner 54 while swirling down, and is discharged from the slag chute 52 as molten slag through the main combustion furnace 51. . The discharged molten slag is taken out after being cooled and solidified by the water-cooled slag conveyor 6.

  On the other hand, the exhaust gas from the melting furnace 5 is about 1350 to 1450 ° C., and after this is cooled to about 850 ° C. through the mixing cooler 53, the air preheater 7 and the multistage steam heaters 8 to 10 are cooled. It is sent to the exhaust heat recovery unit consisting of In this example, the air preheater 7 and the first stage steam heater 8 are each composed of a radiant heat exchanger, and the second and third stage steam heaters 9 and 10 are each composed of a shell and tube heat exchanger. However, the present invention is not limited to such types and combinations, and other known heat exchangers can also be used.

  The air preheater 7 is preheated by heat exchange with the melting furnace exhaust gas in advance in order to avoid an extreme temperature drop when blowing air of about 20 to 200 ° C. into the main combustion furnace 51 to prevent overheating in the furnace. More specifically, as shown in FIG. 3, a vertically-arranged cylindrical portion 7T (for example, an inner diameter 1500) through which melting furnace exhaust gas is circulated from the upper supply port 7i toward the lower end discharge port 7e. ˜2500 mm) and a cylindrical jacket portion 7J which is provided so as to surround the circulating exhaust gas in the cylindrical portion 7T and through which combustion air flows from the upper end supply port 7m to the lower end discharge port 7n. . For example, as shown in the drawing, the atmospheric air is directly supplied to the air preheater 7, and the supplied air flows in the jacket portion 7J in the downward direction, and the melting furnace exhaust gas flows in parallel in the cylindrical portion 7T. Is preheated to about 500 ° C. by indirect heat exchange, and then sent to the main combustion furnace 51 to suppress the furnace temperature to an appropriate temperature. This preheated air can also be supplied to the precombustion furnace 50. Further, the cooling air of about 200 ° C. taken out from the upper cooling jacket of the pre-combustion furnace 50 can be supplied to the air preheater 7 alone or in place of the air.

  The melting furnace exhaust gas that has passed through the air preheater 7 reaches about 811 ° C. and is supplied to the first stage steam heater 8 via the exhaust gas communication passage 70. The first stage steam heater 8 has basically the same structure as the air preheater 7. That is, as shown in detail in FIG. 3, the first stage steam heater 8 includes a vertically disposed cylindrical portion 8 </ b> T through which melting furnace exhaust gas flows from the lower end supply port 8 i to the upper discharge port 8 e, and the cylindrical portion. It arrange | positions so that the distribution | circulation waste gas in 8T may be surrounded, and it is comprised from the cylindrical jacket part 8J through which the vapor | steam discharged | emitted from the dryer 3 distribute | circulates from the lower end part supply port 8m toward the upper end part discharge port 8n. The steam of about 150 ° C. discharged from the dryer 3 is heated to about 181 ° C. by indirect heat exchange with the melting furnace exhaust gas flowing in the cylindrical portion 8T in the process of circulating in the jacket portion 8J. . On the other hand, the melting furnace exhaust gas is cooled to about 750 degrees.

  Next, in this example, the steam that has passed through the first stage steam heater 8 is circulated in the order of the second stage steam heater 9 and the third stage steam heater 10, and conversely, the melting furnace exhaust gas is the third stage steam. The heater 10 and the second-stage steam heater 9 are circulated in this order, and indirect heat exchange is performed in such a manner that they flow backward to each other. These second-stage and third-stage steam heaters 9 and 10 are, as shown in detail in FIG. 3, a so-called shell-and-tube heat exchange having a large number of tubes 9T and 10T in the shells 9S and 10S. Steam is circulated between the inner surface of the shell 9S, 10S and the outer surface of the tubes 9T, 10T, and the melting furnace exhaust gas is circulated in the tubes 9T, 10T. In the process, the steam is indirectly heat exchanged with the melting furnace exhaust gas. Is heated by.

  To explain in detail along the flow of the steam, first, with respect to the second stage steam heater 9, the steam of about 181 ° C. that has been heated in the first stage steam heater 8 is passed through the steam communication path 80. The melting furnace exhaust gas at about 400 ° C. after the heat exchange in the third stage steam heater 10 is supplied through the exhaust gas communication path 72. Thereby, the vapor | steam which distribute | circulates the inside of the shell 9S is heated to about 232 degreeC by indirect heat exchange with the waste gas which distribute | circulates the inside of the tube 9T. The melting furnace exhaust gas is cooled to about 250 ° C. Next, in the third stage steam heater 10, the steam of about 232 ° C. that has been heated in the second stage steam heater 9 passes through the steam communication path 81 and the first stage steam heater 8. The melting furnace exhaust gas at about 750 ° C. after the heat exchange is supplied through the exhaust gas communication passage 71. Thereby, the vapor | steam which distribute | circulates the inside of the shell 10S is heated to about 369 degreeC by indirect heat exchange with the waste gas which distribute | circulates the inside of the tube 10T. The melting furnace exhaust gas is cooled to about 400 ° C.

  On the other hand, the dust contained in the melting furnace exhaust gas accumulates and collects at the lower end of the air preheater 7 and the first to third steam heaters 8 to 10, and removes foreign matter etc. with a fly ash treatment facility (not shown). It stabilizes after processing, and it disposes outside or returns to the entrance side of dry sludge transport blower 4, and mixes in dry sludge.

  As described above, in this example, among the heat exchangers 7 to 10 that sequentially recover the exhaust heat of the melting furnace exhaust gas, the front heat exchanger (air preheater 7) that easily generates dust due to re-solidification of the evaporated metal. In addition, by using the radiant heat exchanger having the above-described configuration as the first stage steam heater 8), even if some dust adheres to the inner peripheral surface of the cylindrical portion, the flow of the exhaust gas is inhibited or blocked. It is difficult to reach a serious situation, cleaning is easy, and high temperature resistance is sufficiently secured. Moreover, simply using such a radiant heat exchanger results in a low heat exchange efficiency, and therefore the installation space of the entire exhaust heat recovery unit becomes excessive. In this example, the latter stage is further difficult to generate dust due to evaporated metal. Combined as a side heat exchanger (second and third stage steam heaters 9 and 10) is a shell and tube heat exchanger with very high heat exchange efficiency per unit installation area and sufficient high-temperature resistance As a result, it is possible to minimize the installation space of the exhaust heat recovery unit while reducing the risk of blockage of the exhaust gas circulation system due to dust.

  However, even if the above combined configuration is adopted, dust cannot be completely prevented from adhering in the heat exchangers 7 to 10, and regular cleaning is required. However, even if cleaning is necessary, cleaning work becomes very complicated if dust adheres to all of the heat exchangers in a plurality of stages. Therefore, preferably, as shown in FIG. 4, the exhaust gas from the heat exchanger (air preheater 7) on the most upstream side where dust due to evaporated metal is likely to be generated is used as the heat exchanger (first stage steam heater) at the next stage. 8) In the exhaust gas communication passage 70 fed to 8), for example, the cross-sectional area with respect to the exhaust gas flow direction is higher than that of the upstream heat exchanger 7 so that the internal exhaust gas flow velocity is lower than that of the upstream heat exchanger 7. It is desirable to form large dust capture spaces 70S, 70S. Particularly preferably, the flow rates in the dust trapping spaces 70S and 70S are all exhaust gas passages upstream of the dust trapping spaces 70S and 70S (that is, in this example, the heat exchanger 7 and the mixed cooler). It is desirable that the speed is lower than that in the communication path 72) with 53. The degree of decrease in the flow velocity in the dust trapping spaces 70S and 70S cannot be generally specified, but is preferably about 2 to 5 m / second, for example. More specifically, the flow velocity in the communication path 72 is 5 to 10 m / second, the flow velocity in the heat exchanger 7 is 3 to 6 m / second, and the flow velocity in the dust trapping space 70S is 2 to 5 m / second. It is desirable to design.

  Thereby, the flow velocity of the exhaust gas accompanied by dust generated by cooling in the heat exchanger 7 on the most upstream side is lowered in the dust trapping spaces 70S and 70S in the exhaust gas communication passage 70 to the next stage, and the dust contained therein is reduced. The trapping spaces 70S and 70S are trapped in a concentrated manner. Therefore, some dust may adhere to the heat exchanger 7 on the most upstream side, but dust is less likely to be generated / attached in the heat exchangers 8 to 10 after the exhaust gas communication path 70, and the flow path is blocked. The risk is also reduced and the cleaning work is greatly facilitated.

  Further, as shown in the drawing, a sideways exhaust gas communication path (duct) 70 connecting the air preheater 7 and the steam heater 8 is provided at the lower end discharge port 7e of the cylindrical portion of the air preheater 7 at the supply port 70i on the upper end wall. When the exhaust port 70e is connected to the lower end supply port 8i of the tubular portion of the steam heater 8 at the discharge port 70e on the upper wall of the other end, there is an advantage that the exhaust gas communication passage 70 can be easily cleaned. .

  In particular, as shown in detail in FIG. 4, the exhaust gas communication path 70 has a cylindrical upper portion t1 connected in series with the lower end discharge port 7e of the air preheater 7, and a conical lower side having a dust discharge port x1 at the lower end vertex. A conical lower portion c2 having an inlet side cylindrical portion 70A composed of a portion c1, a cylindrical upper portion t2 connected in series to the lower end supply port 8i of the steam heater 8, and a dust discharge port x2 at the lower end apex portion. The entrance side saddle-shaped cylindrical portion 70B is connected to the side of the entrance-side saddle-shaped cylindrical portion 70A and the exit side is connected to the side of the exit-side saddle-shaped cylindrical portion 70B. A lateral duct portion 70C in which the lower surface en is continuously inclined downward to the lower end discharge port x1 of the entry side saddle-shaped cylindrical portion and the lower surface ex in the exit side portion is continuously inclined downward to the lower end discharge port x2 of the exit side saddle-shaped cylindrical portion; Are preferably formed integrally. In the exhaust gas communication passage 70, the entire sides of the reduced diameter portion ce at the center of the lateral duct portion 70C serve as dust capturing spaces. With this configuration, not only the entire communication path 70 excluding the reduced diameter portion ce becomes a dust capturing space, but also substantially all of the lower portion c1, en, ex, c2 are formed with downward inclined surfaces. Therefore, there is no horizontal surface over substantially the entire lower surface, and almost all of the dust that has fallen due to a decrease in the flow velocity slides down to one of the discharge ports x1 and x2. Therefore, the dust capturing ability in the exhaust gas communication passage 70 is further increased, and substantially all of the descending dust can be collected and discharged at the discharge ports x1 and x2.

  On the other hand, the steam heated by heat exchange with the melting furnace exhaust gas is circulated and supplied to the dryer 3. At this time, if necessary, the auxiliary heater 11 (indirect heat exchanger) is heated to a predetermined temperature, for example, 400 ° C. by heat exchange with clean exhaust gas from the auxiliary furnace 12 that burns fuel such as city gas. And supplied to the dryer 3. For this reason, although not shown, a temperature measuring device for measuring the temperature of the steam returned to the dryer 3 is provided. It is desirable to configure so as to adjust the degree of combustion. Reference numeral 13 denotes an auxiliary furnace fan that feeds combustion air to the auxiliary furnace.

  As shown in the drawing, it is also preferable to supply a part of the steam returned to the dryer 3 into the melting furnace 5 to prevent overheating. That is, when the steam is brought into direct contact with the sludge and dried as in this example, the circulating steam increases with time due to the evaporation of moisture during sludge drying, and therefore it is necessary to discharge it outside the system as necessary. . On the other hand, when the melting furnace 5 is a natural cooling type as described above, a large amount of air must be supplied into the furnace in order to prevent overheating. However, by blowing part of the circulating steam into the furnace 5, not only can the amount of circulating steam be adjusted, but the specific heat of the steam is about four times that of air, so it is remarkably compared to the case of air alone. The furnace temperature can be adjusted with a small amount of blowing. The circulating steam contains a large amount of malodorous components, but there is a secondary advantage that when the steam is blown into the melting furnace 5, the malodorous components are thermally decomposed. However, when the steam blown into the melting furnace 5 is at a low temperature (about 370 ° C.) as in this example, the temperature in the furnace is drastically lowered and the temperature adjustment is hindered. Thus, it is preferable to mix with the air blown into the melting furnace 5 from the preheater 7 and then blow it into the furnace. In the case of the melting furnace 5 of this example, in order to obtain the above advantages, it is desirable to blow the circulating steam into the main combustion furnace 51 and the remainder into the mixing cooler 53. Although not shown, a pressure gauge for measuring the internal pressure of the dryer 3 and means for controlling the amount of the circulating steam supplied to the melting furnace 5 according to the measurement result of the pressure gauge are provided for adjusting the amount of the circulating steam. Is desirable.

  On the other hand, the melting furnace exhaust gas cooled to about 250 ° C. by heat exchange with steam is cooled to about 200 ° C. by spraying cooling water and cooling air in the exhaust gas cooler 100, and then removed by the bag filter 101. . The dust collected by the exhaust gas cooler 100 and the bag filter 101 is also stabilized and disposed of after being subjected to foreign matter removal or the like in a fly ash treatment facility (not shown), or on the inlet side of the dry sludge transport blower 4 And mix with dry sludge. The exhaust gas that has passed through the bag filter 101 is then supplied to the flue gas treatment tower 102 (scrubber) and cleaned and collected with cleaning water. Further, after being cooled to about 50 ° C. in the process, it is introduced into the denitration processing unit 110 by the induction fan 103.

  The denitration processing unit 110 preheats the melting furnace exhaust gas to about 250 ° C. in advance by heat exchange with exhaust heat in a denitration preheater (indirect heat exchanger) 111, and then heats about 350 by the heating furnace 112 using a fuel such as city gas. After heating to the reaction tower supply temperature of 0 ° C., urea water, air, dilution water, and the like are added, and denitration treatment by denitration reaction is performed in the reaction tower 113. The clean exhaust gas used in the auxiliary heater 11 of the steam circulation system has an appropriate temperature (about 400 ° C.), and it is uneconomic to discharge it as it is, so that all (or a part of) may be used as a heating medium in the preheater 111. It is desirable to use it. Further, as shown in the figure, the exhaust gas after the denitration treatment also has an appropriate temperature (about 350 ° C.), so it is also preferable to use it in the preheater 111 after this and the clean exhaust gas from the auxiliary heater 11 are mixed and mixed. The mixed gas is released into the atmosphere from the chimney 114 after heat exchange in the preheater 111. In particular, by mixing the clean exhaust gas used in the auxiliary heater 11 into the exhaust gas after the denitration treatment, there is an advantage that the generation of white smoke when released into the atmosphere can be prevented. Of course, only clean exhaust gas from the auxiliary heater 11, only denitrated exhaust gas, or other heat sources can be used. Reference numeral 115 denotes an air fan that feeds air into the heating furnace.

<Others>
(B) Although the heat exchanger of the above example is provided in four stages, the number of stages of the heat exchanger can be appropriately determined according to the degree of exhaust heat recovery.

(B) Although the drying heat medium in the above example is steam, other heat medium may be used in the present invention.

(C) Further, the above example is a sewage sludge melting treatment facility, but the present invention is not limited to this, and it can be applied to treatment of other wastes and non-wastes as long as it contains water. It can also be applied to combustion treatment equipment such as incineration equipment that is not performed.

  DESCRIPTION OF SYMBOLS 1 ... Sludge pit, 2 ... Sludge supply pump, 3 ... Dryer, 4 ... Dry sludge transport blower, 5 ... Melting furnace, 6 ... Water-cooled slag conveyor, 7 ... Air preheater, 8, 9, 10 ... Steam heater, DESCRIPTION OF SYMBOLS 11 ... Auxiliary heater, 12 ... Auxiliary furnace, 70, 71, 72 ... Exhaust gas communication path, 80, 81 ... Steam communication path, 100 ... Exhaust gas cooler, 101 ... Bag filter, 102 ... Smoke treatment tower, 111 ... Denitration Preheater, 112 ... heating furnace, 113 ... reaction tower, 114 ... chimney.

Claims (3)

A drying machine that dries the hydrated material using a heating medium as a drying heat source; and a combustion furnace that burns the dried material dried by the drying machine, and the spent heating medium used by the drying machine is an exhaust gas of the combustion furnace. In the hydrated material combustion treatment equipment configured to heat by heat exchange and to circulate and supply again to the dryer,
The first stage indirect heat exchanger, the second stage indirect heat exchanger, and the third stage indirect heat exchanger that perform heat exchange between the used heat medium and the exhaust gas of the combustion furnace,
The used heat medium is circulated in the order of the first-stage indirect heat exchanger, the second-stage indirect heat exchanger, and the third-stage indirect heat exchanger, while the combustion furnace exhaust gas is in the first-stage indirect heat exchanger. The indirect heat exchanger of the eye, the indirect heat exchanger of the third stage and the indirect heat exchanger of the second stage are configured to be distributed in this order.
A hydrated substance combustion treatment facility characterized by that.   The hydrate-containing combustion treatment facility according to claim 1, wherein the heat medium is steam, and the dryer is a steam direct dryer that performs drying by directly contacting the steam and the hydrated material. The water-containing material is dried using a heat medium as a drying heat source, and the dried dry material is combusted, while the used heat medium used for the drying is heated by heat exchange with the combustion furnace exhaust gas generated by the combustion, In using again for the drying,
Using the first stage indirect heat exchanger, the second stage indirect heat exchanger, and the third stage indirect heat exchanger that perform heat exchange between the used heat medium and the exhaust gas of the combustion furnace,
The spent heat medium is circulated in the order of the first-stage indirect heat exchanger, the second-stage indirect heat exchanger, and the third-stage indirect heat exchanger, while the combustion furnace exhaust gas is passed through the first-stage indirect heat exchanger. Indirect heat exchanger, the third-stage indirect heat exchanger and the second-stage indirect heat exchanger in order,
A hydrated combustion method characterized by the above.

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