JP2012207870A - Multistage organic matter drying system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multistage organic matter drying system, which achieves easy overall temperature control, high heat utilization efficiency, and the prevention of the flow rate of superheated steam from becoming excessively high even when a low-temperature heat source is used.SOLUTION: The multistage organic matter drying system which is provided with a conveying means for conveying an organic matter to multiple stages 4 from an upper stage to a lower stage, and a drying chamber 1 for housing the conveying means, and sends the superheated steam (a-c) into a drying chamber to dry the organic matter is characterized by comprising N (N is a natural number larger than or equal to 2) lead-in ports (21-23) for leading the superheated steam into the drying chamber, and N±1 lead-out ports (31, 32) for leading the superheated steam out of the drying chamber.

Description

  The present invention relates to a multi-stage organic matter drying system, and more particularly, to a multi-stage organic matter drying system used for drying organic matter containing a lot of moisture such as sludge.

  In order to dry organic matter containing a lot of moisture such as sludge, a multi-stage type organic matter drying system has been proposed in which the organic matter is transported in multiple stages from the upper stage toward the lower stage, and the organic substance is dried by blowing superheated steam.

  As shown in Patent Document 1, the organic matter is sequentially transported in the horizontal direction by a plurality of rakes arranged and rotated in each stage, and falls to the next lower stage at the end of each stage, and then continues to the lower rake. It is configured to be conveyed in the lateral direction. In this way, the organic matter is conveyed in multiple stages from the upper stage toward the lower stage. And it is comprised so that heating gas may be flowed in the same direction as the conveyance direction of organic substance (cocurrent flow), and organic substance may be dried.

  Further, in Patent Document 2, in the final step (end of drying) of the organic substance conveying means, the vaporized vapor having a small air volume is brought into contact to compensate for insufficient drying, and dust is prevented from being mixed into the vapor, and the dust collector It is disclosed to suppress the increase in size.

  The relationship between the organic material transport direction and the superheated steam flow direction is not only the “parallel flow method” in which both move in the same direction, but also the “alternating current (counter current) method” in which both move in opposite directions. The parallel flow method has an advantage that the temperature control is stable, but there is a problem of insufficient heating at the end as in Patent Document 1. The AC method has high thermal efficiency and can carbonize organic matter, but has a drawback that heating is likely to be local and it is difficult to control the entire temperature.

  In addition, as a combination of the parallel flow method and the alternating current method, superheated steam is supplied to the intermediate position of the transport path, superheated steam is flowed in the upstream with respect to the organic material transport direction, and superheated steam is flowed in the downstream with parallel flow. There is also a drying method that uses a so-called “two-divided flow system”. However, in the multi-stage organic material drying system, high temperature is required in the upper stage, and drying at low temperature is required in the lower stage. For this reason, since the superheated steam temperature at the dryer inlet is one in the diversion method, it is difficult to satisfy the upstream condition and the downstream condition at the same time, and it is inefficient and operation control is difficult. There were difficulties.

  In addition, when the passage channel is formed only by the parallel flow method or the alternating current method, or when the passage channel is formed only by the diversion method, the passage passage becomes longer and the temperature response of the superheated steam is poor. There was a problem that drying or under-drying was likely to occur. Moreover, the long flow path has a problem that the internal pressure loss increases and the circulation fan becomes large.

  Furthermore, when drying with a low-temperature heat source (exhaust gas in the range of 300 ° C.), the heat transfer area increases, and in the case of a superheated steam circulation dryer, the flow rate of the circulating steam is about 12 to 15 times the generated steam flow rate. Therefore, the flow velocity inside the dryer tends to be excessive, and problems such as dust scattering occur.

JP-A-2-71900 JP 2004-190990 A

  The problem to be solved by the present invention is to solve the above problems, to easily control the entire temperature, to have high heat utilization efficiency, and to prevent the flow rate of superheated steam from becoming excessive even when using a low-temperature heat source. It is to provide a possible multi-stage organic matter drying system.

In order to solve the above problems, the multistage organic matter drying system of the present invention has the following technical features.
(1) Transport means for transporting organic matter in multiple stages from the upper stage toward the lower stage, a drying chamber for housing the transport means, and a multistage organic matter drying system for blowing superheated steam into the drying chamber to dry the organic matter In which N superheated steam is introduced into the drying chamber (N is a natural number equal to or greater than 2) and N ± 1 deriving ports through which the superheated steam is led out from the drying chamber. .

(2) In the multi-stage organic matter drying system according to (1), the introduction port and the outlet port are alternately arranged in the height direction, and the superheated steam introduced from the introduction port is transferred to the transport port. An air flow that flows in a direction opposite to the conveying direction of the means and an air flow that flows in the same direction as the conveying direction of the conveying means are formed.

(3) The multistage organic matter drying system according to (1) or (2) is characterized in that superheated steam having different temperatures are introduced into the N introduction ports.

(4) In the multistage organic matter drying system according to (3) above, the temperature of the superheated steam introduced from the introduction port is, when the water content of the organic matter treated with the superheated steam is 45% or less, It is characterized by being 250 ° C. or less.

  In the multistage organic matter drying system of the present invention, N (N is a natural number of 2 or more) inlet ports for introducing superheated steam into the drying chamber, and N ± 1 outlet ports for deriving superheated steam from the drying chamber, Therefore, the flow path of superheated steam can be set short, and the part of the parallel flow system and AC system can be set appropriately in the middle of the organic material transport path, making it easy to control the temperature and using the heat of superheated steam. High efficiency can be set. In addition, the flow rate of the superheated steam can be suppressed. Further, when the number of outlet ports is N−1, the superheated steam is likely to stay in the drying chamber, the pressure of the superheated steam can be increased, and the heat capacity of the superheated steam can be increased. Further, when the number of outlet ports is N + 1, it is possible to smooth the flow of superheated steam and to efficiently circulate the superheated steam.

  Furthermore, the introduction port and the outlet port are alternately arranged in the height direction, and the superheated steam introduced from the introduction port flows in the direction opposite to the conveyance direction of the conveyance means (alternating current method), Since an air flow (parallel flow method) flowing in the same direction as the transfer direction of the transfer means is formed, the AC method and the parallel flow method can be selectively used for each stage, and heat utilization efficiency can be increased. In addition, when the number of outlet ports is N−1, the upper stage starts with a parallel flow system and the lower stage ends with an AC system, so it is difficult for the superheated steam to go outside. Therefore, it is also possible to suppress a large amount of dust from the dried organic matter being led out to the lead-out port. When the number of outlet ports is N + 1, the AC method is used on the upper side, the organic matter is efficiently dried, and the parallel current method is used on the lower side, so that temperature control can be easily performed.

  Further, since the superheated steam having different temperatures is introduced into the N introduction ports, the superheated steam having the optimum temperature corresponding to each stage can be provided, and the temperature control becomes easy.

  Furthermore, since the temperature of the superheated steam introduced from the introduction port is 250 ° C. or lower when the moisture content of the organic matter treated with the superheated steam is 45% or less, overdrying of the organic matter can be suppressed.

It is a figure which shows the outline of the multistage type organic substance drying system of this invention. It is a figure which shows an example of the conveyance means used for the multistage type organic substance drying system of this invention.

The present invention is illustrated by the following preferred examples, but is not limited thereto.
The multi-stage organic matter drying system of the present invention comprises transport means for transporting organic matter containing water such as sludge from the upper stage to the lower stage in multiple stages (each stage is indicated by reference numeral 4), and a drying chamber that houses the transport means. 1 and N pieces of superheated steam (ac) introduced into the drying chamber 1 in a multi-stage organic matter drying system that blows superheated steam (ac) into the drying chamber and dries the organic matter (N is N It has an introduction port (21 to 23) having 2 or more natural numbers) and N ± 1 outlet ports (31, 32) for leading the superheated steam (d, e) from the drying chamber 1. .

  As shown in FIG. 2, a plurality of rakes 8 are arranged on the conveyance table 4 of each stage, and the rakes 8 pass through the respective stages as conveying means used in the multistage organic matter drying system of the present invention. It is comprised by rotating with the rotating shaft 9 arrange | positioned. FIG. 2A is a plan view of a rake arranged in each stage, and FIG. 2B is a side view seen from the lateral direction. As each rake rotates, the organic matter is sequentially conveyed in the directions of arrows A and B. The conveying means is not limited to the rake shown in FIG. 2, but an conveying means using an endless belt can also be used. However, in order to increase the contact area between the organic matter and the superheated steam, a conveying means with an agitating function such as rake is added. Is preferably used.

  As shown in FIG. 1, the organic matter is dried by the superheated steam introduced into the drying chamber while being sequentially transported from the upper stage to the lower stage of the drying chamber, and finally discharged as dried organic matter (dry organic matter) such as dry sludge. Is done. The dried organic matter is incinerated in a combustion furnace or incinerated as a fuel for a cement manufacturing facility or the like.

  In the multistage organic matter drying system of the present invention, it is preferable to circulate and use superheated steam. This is because the odor generated when drying organic matter such as sludge can be prevented from being released to the outside, and the amount of heat retained by the superheated steam is effectively utilized. As shown in FIG. 1, superheated steam (ac) is introduced into the drying chamber 1 from the introduction ports (21 to 23) and discharged from the discharge ports (31, 32). Circulating steam (symbols d, e) is blown (f, g) by the fans (51, 52), heated by the heat exchangers (61, 62), and again as the superheated steam (ac) to the drying chamber 1. To be introduced.

  When organic matter is dried, steam is generated and mixed with superheated steam. For this reason, since the pressure of superheated steam increases, unnecessary steam is discharged to the outside as surplus steam (steam evaporated from organic matter). At this time, the surplus steam can be treated at a high temperature by using the surplus steam as a part of the air supplied to the incinerator or the cement production facility, and the odor contained in the steam is also decomposed and removed.

  A high-temperature exhaust gas such as a combustion gas exhausted from a combustion furnace or a cement manufacturing facility is introduced into the heat exchanger (61, 62). In the multistage organic matter drying system of the present invention, the temperature of the heating gas such as the combustion gas introduced into the heat exchanger is the flow rate of the superheated steam in the drying chamber even when a low-temperature heat source of about 300 ° C. is used. Is configured so as not to be excessive.

  In the multistage organic matter drying system of the present invention, N (N is a natural number of 2 or more) inlet ports for introducing superheated steam into the drying chamber, and N ± 1 outlet ports for deriving superheated steam from the drying chamber, have. By disposing two or more introduction ports for introducing superheated steam, it is possible to set a short passage path for superheated steam introduced from one introduction port. In addition, since the number of outlet ports is configured to be one less than the number of introduction ports, it is possible to appropriately set the parallel current method and the alternating current method part in the middle of the organic material transport path. The heat utilization efficiency of superheated steam can be set high.

  In addition, when using a low-temperature heat source, even if the amount of superheated steam (circulated steam) is 12 to 15 times the amount of evaporated steam evaporating from the organic matter, the passage of each superheated steam is shortened so that the steam passes. Since the area can be suppressed, the flow rate of superheated steam does not become excessive.

  Also, when the number of outlet ports is N-1, the number of outlet ports is smaller than the number of inlet ports, so superheated steam tends to stay in the drying chamber, increasing the pressure of superheated steam and increasing the heat capacity of superheated steam. It is possible to perform drying. Also, when the number of outlet ports is N + 1, the number of outlet ports is larger than the number of inlet ports, so the flow of superheated steam can be smoothed and the superheated steam can be circulated efficiently. It becomes.

  Furthermore, in the multistage organic matter drying system of the present invention, the introduction ports (21 to 23) and the outlet ports (31, 32) are alternately arranged in the height direction, and the superheated steam introduced from the introduction port is In order to form an air flow (alternating current method) flowing in the direction opposite to the conveying direction of the conveying means and an air flow (parallel flow method) flowing in the same direction as the conveying direction of the conveying means, an alternating current method is provided for each stage. And the parallel flow method can be used separately, and the heat utilization efficiency can be further increased.

  In addition, when the number of outlet ports is N−1, the upper stage starts with a parallel flow system and ends with an AC system on the lower stage, so that superheated steam exits from the organic material inlet and outlet. Is suppressed. In particular, since it is an alternating current system in the lower stage, it is possible to suppress a large amount of dust from the dried organic matter being led out to the outlet port. Of course, when dust or the like is likely to be mixed into the superheated steam, a dust collector such as a cyclone dust collector may be disposed in the middle of the superheated steam circulation path (symbol e or d).

  When the number of outlet ports is N + 1, the AC method is used on the upper side, the organic matter is efficiently dried, and the parallel current method is used on the lower side, so that temperature control can be easily performed.

  In the multistage organic matter drying system of the present invention, superheated steam having different temperatures is introduced into the N introduction ports. When using a low-temperature heat source, as shown in FIG. 1, high-temperature superheated steam at 280 ° C. or higher or around it is introduced into the upper introduction port 21, and 260 ° C. or more is introduced into the middle introduction port 22. Alternatively, a medium-temperature superheated steam before and after that is introduced, and a low-temperature superheated steam of 220 ° C. or higher or around it is introduced into the lower introduction port 23.

  Thus, it is preferable to reduce the temperature of the superheated steam introduced from the upper stage toward the lower stage. This is because the water content in the organic matter decreases as it goes down. In particular, the temperature of the superheated steam introduced from the introduction port is preferably set to 250 ° C. or less when the moisture content of the organic substance treated with the superheated steam is 45% or less. This is to suppress overdrying, such as dry distillation that evaporates to volatile components contained in the organic matter and generation of tar in the vapor.

  From the lead-out ports (31, 32), superheated steam (d, e) that has lost its amount of heat due to drying of the organic matter is discharged. The temperature of this superheated steam is a temperature of 140 ° C. or higher or around it, and in order to increase heat utilization efficiency, these are reheated as circulating steam and supplied as new superheated steam (ac).

  In order to adjust the temperature in the drying chamber 1, it is necessary to adjust the flow rate and temperature of the superheated steam entering the drying chamber. For this reason, there are methods for adjusting the temperature of a heating gas such as combustion gas introduced into the heat exchanger, and adjusting the flow rate of superheated steam passing through the heat exchanger. Further, by operating the damper 7 to change the passage path or passage flow rate of the superheated steam g introduced into the heat exchanger, and changing the flow rate ratio between the high temperature superheated steam a and the low temperature superheated steam c, It is also possible to control the temperature of the drying chamber. In FIG. 1, the heating gas such as the combustion gas is introduced into the other heat exchanger 62 as used in the heat exchanger 61, but is not limited thereto, and a different heating gas is introduced for each heat exchanger. It is also possible to do.

  In the multi-stage organic matter drying system of the present invention, even when using a low-temperature heat source of 300 ° C. or less, which is industrially less useful, FIG. 1 also shows four superheated steam channels (introduction port 21 → outlet port 31, similar). In addition, four channels (22 → 31, 22 → 32, 23 → 32) are secured, the channel is short, and an increase in the flow rate can be suppressed, so that the dryer body and the heat exchanger can be downsized. Become.

  Since the so-called diversion process is performed in which the organic material conveyance path is divided into a plurality of portions and brought into contact with the superheated steam, temperature control at the inlet or outlet of the superheated steam to the drying chamber is facilitated, and stable drying becomes possible. Moreover, for example, as shown in FIG. 1, in a 13-stage multi-stage dryer (the first stage in the upper stage does not allow superheated steam to pass, the number of effective stages is 12), and if four steam channels are formed, 1 Since there are three stages per steam flow path, the temperature responsiveness is improved and the internal flow rate is 1/4 compared to the single flow path system compared to the conventional technology that processed about 10 or more stages per steam flow path. Therefore, the size can be reduced and scattering of dust and the like can be suppressed.

  As described above, according to the present invention, there is provided a multistage organic matter drying system that is easy to control the entire temperature, has high heat utilization efficiency, and can suppress an excessive flow rate of superheated steam even when using a low-temperature heat source. It becomes possible to provide.

DESCRIPTION OF SYMBOLS 1 Drying chambers 21-23 Introduction ports 31, 32 Derivation ports 4 Transfer tables 51, 52 Blower fans 61, 62 Heat exchanger 7 Damper 8 Rake 9 Rotating shaft ae Flow of superheated steam

Claims (4)

In a multi-stage type organic matter drying system that transports organic matter in multiple stages from the upper stage to the lower stage, a drying chamber that houses the transportation means, and superheated steam is blown into the drying chamber to dry the organic matter.
N (N is a natural number of 2 or more) introduction ports for introducing superheated steam into the drying chamber;
A multistage organic drying system having N ± 1 outlet ports for leading superheated steam from the drying chamber.   2. The multistage organic matter drying system according to claim 1, wherein the inlet port and the outlet port are alternately arranged in a height direction, and superheated steam introduced from the inlet port is transported in the transport direction of the transport means. A multi-stage organic drying system characterized by forming an air flow flowing in the opposite direction to the air flow and an air flow flowing in the same direction as the conveying direction of the conveying means.   3. The multi-stage organic matter drying system according to claim 1, wherein superheated steam having different temperatures are introduced into the N introduction ports. 4.   The multistage organic matter drying system according to claim 3, wherein the temperature of the superheated steam introduced from the introduction port is 250 ° C or less when the moisture content of the organic matter treated with the superheated steam is 45% or less. A multi-stage organic matter drying system characterized by

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