CN113474312B

CN113474312B - Sludge treatment method and cement production system

Info

Publication number: CN113474312B
Application number: CN202080016997.3A
Authority: CN
Inventors: 青松慎之介; 吉永昭宏; 安藤文典; 凡茂树
Original assignee: Kawasaki Jukogyo KK
Current assignee: Kawasaki Motors Ltd
Priority date: 2019-07-05
Filing date: 2020-07-01
Publication date: 2023-02-21
Anticipated expiration: 2040-07-01
Also published as: JP7245128B2; JP2021010877A; TW202108257A; TWI826700B; WO2021006155A1; KR20220028020A; CN113474312A

Abstract

A cement production system is provided with: a suspension preheater for preheating the cement raw material; a calciner for calcining the preheated cement raw material; and a firing furnace for firing the fired cement raw material. In the cement production system, a granular material containing dry sludge is fed into a temperature range of 600 ℃ or higher and less than 800 ℃ of a suspension preheater, and the dry sludge is used as a cement raw material and a fuel.

Description

Sludge treatment method and cement production system

Technical Field

The present invention relates to a sludge treatment method and a cement production system using sludge.

Background

The cement manufacturing process generally comprises the following steps: a raw material step of drying, pulverizing and blending a cement raw material, a firing step of firing clinker, which is an intermediate product fired from the raw material, and a grinding step of adding gypsum to the clinker, pulverizing the mixture into cement. In the firing step, generally, the cement raw material passes through a preheater, a calciner (decomposing furnace), and a firing furnace in this order. The following proposals are made: combustion heat of sludge such as sewage sludge and factory drainage sludge is used as heat energy in the firing step, and further, the fired ash is used as a cement raw material. Patent documents 1 and 2 disclose techniques of using sludge in a cement firing step.

Patent document 1 discloses that a solvent for providing fluidity is added to a waste containing organic matter, and the mixture is pulverized by a wet mill, and then the pulverized mixture in the form of a slurry is subjected to a firing step to produce cement clinker. The solvent may be sludge. The place to be charged with the slurry-like pulverized mixture may be a high-temperature part of a preheater at 800 to 1000 ℃.

Patent document 2 shows: in the case of using a cement firing apparatus in which a calciner and a lowermost cyclone are directly connected, hydrous sludge is charged into a region from an outlet of the calciner to an outlet of the lowermost cyclone, and in the case where the calciner and the lowermost cyclone are not directly connected, hydrous sludge is charged into a region from the inlet of the lowermost cyclone to the outlet of the lowermost cyclone. The temperature of the atmosphere at the place where the water-containing sludge is put is 800 ℃ to 900 ℃.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2004-123513

Patent document 2: japanese patent laid-open publication No. 2009-95804

Disclosure of Invention

Technical problem to be solved by the invention

In patent document 1, the generation of dioxin is prevented by feeding sludge containing a large amount of water, such as a slurry-like pulverized mixture, to a position at 800 ℃ or higher in a preheater. In patent document 2, by feeding the hydrous sludge to a position of 800 ℃ or higher in the preheater, the hydrous sludge can be efficiently dried, and the heat required for raising the temperature of the sludge can be reduced, thereby suppressing the heat loss of the cement burning apparatus.

The applicant of Japanese patent application 2018-006471 has proposed the following: the dewatered sludge and the cement raw material are mixed to prepare granules, the granules are dried by contacting with a drying gas, and the obtained granular mixture is fed into a calciner in the cement firing step. Since the mixture is dried by using a low-temperature drying gas as compared with the furnace temperature of the calciner, the dried mixture may contain more water than a normal cement raw material; the temperature of the mixture charged into the calciner is lower than the temperature inside the calciner.

When a mixture having a temperature lower than the temperature in the furnace is charged into the calciner, the combustion state may be disturbed, and the fuel consumption may be increased. In addition, a local temperature decrease occurs near the introduction port of the mixture, and the life of the refractory coating layer may be reduced or coating may occur.

Here, the present invention proposes the following: a method for treating sludge using sludge as a part of a cement raw material and a fuel, and a technique for stabilizing the operation in a cement production system using sludge.

Means for solving the problems

A method for treating sludge according to one aspect of the present invention is characterized in that,

the method for treating sludge by using a cement production system comprises: a suspension preheater for preheating the cement raw material; a calciner for calcining the preheated cement raw material; and a firing furnace for firing the fired cement raw material; wherein, the first and the second end of the pipe are connected with each other,

the granular material containing the dried sludge is put into the temperature range of 600 ℃ or more and less than 800 ℃ of the suspension preheater, and the dried sludge is used as a cement raw material and a fuel.

Further, a cement production system according to an aspect of the present invention includes:

a suspension preheater for preheating the cement raw material; a calciner for calcining the preheated cement raw material; and a firing furnace for firing the fired cement raw material;

the suspension preheater has at least 1 inlet for introducing the granular material containing the dried sludge into a temperature range of 600 ℃ or higher and less than 800 ℃.

In the above sludge treatment method and cement production system, the granular material including the dried sludge is fed into the temperature range of 600 ℃ or more and less than 800 ℃ of the suspension preheater. The particulate matter is heated together with the cement raw material to a charging temperature (about 850 ℃ C. To 900 ℃ C.) at which the particulate matter is charged into the calciner while the particulate matter moves from a charging port (charging position) at which the particulate matter is charged into the suspension preheater to the calciner.

Conventionally, as in patent documents 1 and 2, the material is charged into a region of 800 ℃ or higher; in contrast, in the present invention, the residence time of the particulate matter in the suspension preheater is long, and the particulate matter is sufficiently preheated together with the cement raw material and then fed into the calciner. This can suppress disturbance of the combustion state and increase in fuel consumption caused by the introduction of low-temperature substances into the calciner. This contributes to stabilization of system operation in a cement production system using sludge as a part of a cement raw material and fuel.

Further, in the present invention, the difference between the atmospheric temperature at the inlet (the input position) of the suspension preheater and the temperature of the particulate matter is smaller than in the conventional case. This can suppress a local temperature drop in the vicinity of the inlet of the particulate matter, and can suppress a reduction in the life of the refractory coating layer or the occurrence of coating.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the following proposals can be made: a method for treating sludge using sludge as a part of a cement raw material and a fuel, and a technique for stabilizing the operation in a cement production system using sludge.

Drawings

Fig. 1 is a schematic block diagram of a system showing a cement production system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram showing a schematic configuration of the suspension preheater.

Detailed Description

Next, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic block diagram of a system of a cement production system 100 according to an embodiment of the present invention.

The cement manufacturing process generally comprises the following steps: a raw material step of drying, pulverizing and blending a cement raw material, a firing step of firing clinker, which is an intermediate product fired from the raw material, and a grinding step of adding gypsum to the clinker, pulverizing the mixture into cement. In the cement production system 100 shown in fig. 1, a cement burning apparatus 2 and a grate cooler 3 which perform a burning step thereof, and peripheral devices thereof are described in detail.

The cement production system 100 includes: a cement burning device 2 for burning the cement raw material, and a grate cooler 3 for cooling the burned material from the cement burning device 2.

The cement burning apparatus 2 includes: a suspension preheater (hereinafter, simply referred to as "preheater 21") for preheating a cement raw material, a calciner 22 for calcining (decomposing) the preheated cement raw material, and a firing furnace 23 for firing the preheated and calcined cement raw material.

In the cement burning apparatus 2, the preheater 21, the calciner 22, and the calciner 23 communicate with each other so that the cement raw materials move in this order. In the cement burning apparatus 2, the high-temperature exhaust gas from the burning furnace 23 flows through the calciner 22 and the preheater 21 in this order. The preheater 21 is connected to a firing device exhaust gas line 9 for exhaust gas flowing out of the cement firing device 2. The exhaust line 9 of the firing device is provided with a boiler 91, an exhaust fan 92, a raw mill 93, a dust collector 94, an exhaust fan 95, and a stack 96 in this order from the upstream to the downstream of the exhaust flow.

Fig. 2 is a schematic diagram showing a schematic configuration of the preheater 21. The preheater 21 shown in fig. 2 includes 2 or more stages of cyclone dust collectors connected in series. The preheater 21 of the present embodiment includes 5-stage cyclone units U1 to U5 connected in series upward from the calciner 22. However, the number of stages of the cyclone units U included in the preheater 21 may be 3 or more.

Each cyclone unit U has: a cyclone separator C; a duct D which introduces the airflow to the cyclone C; and a pipe B for sending the solids separated from the gas flow by the cyclone C to at least one of the duct D, the calciner 22, and the calciner 23 of the cyclone unit U at the lower stage thereof. In fig. 2, the numbers attached to B, C, D, and U indicate the number of segments.

The 1 st cyclone unit U1 at the lowermost stage includes a 1 st cyclone C1, a 1 st duct D1, and a 1 st pipe B1. The gas stream inlet of the 1 st cyclone C1 is connected to the outlet of the calciner 22 via a 1 st duct D1. The solids outlet of the 1 st cyclone C1 is connected to a connection part between the calciner 23 and the calciner 22 via a pipe B1.

The second 2 nd cyclone unit U2 in the second stage from below includes a 2 nd cyclone C2, a 2 nd duct D2, and a 2 nd pipe B2. The gas outlet of the 1 st cyclone C1 is connected to the gas flow inlet of the 2 nd cyclone C2 via a 2 nd conduit D2. The solids outlet of the 2 nd cyclone C2 is connected to the calciner 22 via a pipe B2.

The 3 rd cyclone unit U3 in the third stage from below includes a 3 rd cyclone C3, a 3 rd duct D3, and a 3 rd pipe B3. The gas outlet of the 2 nd cyclone C2 is connected to the gas flow inlet of the 3 rd cyclone C3 via a 3 rd duct D3. The solids outlet of the 3 rd cyclone C3 is connected to the 2 nd duct D2 via a pipe B3.

The 4 th cyclone unit U4 in the fourth stage from the bottom includes a 4 th cyclone C4, a 4 th duct D4, and a 4 th piping B4. The gas outlet of the 3 rd cyclone C3 is connected to the gas flow inlet of the 4 th cyclone C4 via a 4 th conduit D4. The solids outlet of the 4 th cyclone C4 is connected to the 3 rd duct D3 via a pipe B4.

The 5 th cyclone unit U5 at the uppermost stage includes a 5 th cyclone C5, a 5 th duct D5, and a 5 th pipe B5. The gas outlet of the 4 th cyclone C4 is connected to the gas flow inlet of the 5 th cyclone C5 via a 5 th conduit D5. The solids outlet of the 5 th cyclone C5 is connected to a 4 th duct D4 via a pipe B5. The gas outlet of the 5 th cyclone C5 is connected to the upstream end of the burner exhaust line 9.

In the preheater 21 having the above configuration, the high-temperature exhaust gas from the calciner 23 flows into the 1 st cyclone C1 through the calciner 22 and the 1 st duct D1. The off-gas moves from the lowermost cyclone C1 toward the uppermost cyclone C5. That is, the exhaust gas sequentially passes through the 1 st cyclone C1, the 2 nd duct D2, the 2 nd cyclone C2, the 3 rd duct D3, the 3 rd cyclone C3, the 4 th duct D4, the 4 th cyclone C4, the 5 th duct D5, and the 5 th cyclone C5.

The 5 th pipe D5 is provided with a cement raw material supply port 28. The cement raw material is supplied to the 5 th pipe D5 through the cement raw material supply port 28. The cement raw material supplied to the 5 th pipe D5 flows into the 5 th cyclone C5 along the exhaust gas flow. In the 5 th cyclone C5, the cement raw material is separated from the exhaust gas flow, and the cement raw material is sent to the 4 th pipe D4 through the pipe B5. The cement raw material sent to the 4 th pipe D4 flows into the 4 th cyclone C4 along the exhaust gas flow. In the 4 th cyclone C4, the cement raw material is separated from the exhaust gas flow, and the cement raw material is sent to the 3 rd duct D3 through the pipe B4.

The 3 rd pipe D3 is provided with a mixture inlet 29 described later. The inlet 29 is connected to a mixture supply line 8 (transfer line 84) described later. The cement raw material sent from the 4 th cyclone C4 to the 3 rd duct D3 and the cement raw material and the mixture (particulates) supplied to the 3 rd duct D3 through the input port 29 flow into the 3 rd cyclone C3 along the exhaust gas flow. In the 3 rd cyclone C3, the cement raw material (including the mixture) is separated from the exhaust gas flow, and the cement raw material is sent to the 2 nd duct D2 through the pipe B3. The cement raw material sent to the 2 nd pipe D2 flows into the 2 nd cyclone C2 along the exhaust gas flow. In the 2 nd cyclone C2, the cement raw material is separated from the exhaust gas flow, and the cement raw material is sent to the calciner 22 through the pipe B2. The exhaust gas from the calciner 22 flows into the 1 st cyclone C1 through the 1 st duct D1. In the 1 st cyclone C1, the cement raw material is separated from the exhaust gas flow, and the cement raw material is sent to a connection portion between the calciner 23 and the calciner 22 through the pipe B1. In this way, in the preheater 21, the cement raw material (including the mixture) moves in sequence from the uppermost cyclone C5 toward the lowermost cyclone C1. The cement raw material in the preheater 21 is heated by heat exchange with the exhaust gas from the calciner 22 as it passes through each cyclone C.

The calciner 22 is provided with a calciner burner 25. An exhaust duct 41 for the calciner 22 for conveying waste heat from the grate cooler 3 to the calciner 22 is connected to the calciner 22. In the calciner 22, the cement raw materials and the mixture exiting the preheater 21 are calcined at an atmosphere of about 900 ℃. In the present embodiment, the temperature of the exhaust gas flowing into the 1 st duct D1 is about 900 ℃, the temperature of the exhaust gas flowing into the 2 nd duct D2 is about 850 ℃, the temperature of the exhaust gas flowing into the 3 rd duct D3 is about 750 ℃, the temperature of the exhaust gas flowing into the 4 th duct D4 is about 600 ℃, the temperature of the exhaust gas flowing into the 5 th duct D5 is about 450 ℃, and the temperature of the exhaust gas flowing out of the cyclone C5 to the exhaust gas line 9 of the firing apparatus is about 310 ℃. However, the temperature of the exhaust gas flowing into each duct D is merely an example.

Returning to fig. 1, in the present embodiment, a horizontally long cylindrical rotary kiln, i.e., a rotary kiln, is used as the firing furnace 23. The firing furnace 23 is provided with a slight downward gradient from the raw material inlet to the raw material outlet. The firing furnace 23 is provided with a burner 26 on the raw material outlet side. In the firing furnace 23, the cement raw material preheated and calcined in the preheater 21 and the calciner 22 is fired by the waste heat of the grate cooler 3 and the combustion gas of the burner 26.

The outlet of the firing furnace 23 is connected to the inlet of the grate cooler 3. In the grate cooler 3, the high-temperature burned product from the burning furnace 23 is brought into contact with cold air, and the burned product is rapidly cooled to form clinker. The clinker from the grate cooler 3 is sent to a clinker silo by a clinker conveyor 32.

A cooler waste heat line 4 through which waste heat of the grate cooler 3 flows out is connected to the grate cooler 3. The cooler waste heat line 4 includes: an air exhaust duct 41 for the calciner, a high temperature waste heat line 42 for exhausting the waste heat of about less than 200 ℃, and a low temperature waste heat line 43 for exhausting the waste heat of about less than 200 ℃ from the grate cooler 3.

The high temperature waste heat line 42 is connected to a boiler 45. The exhaust gas from the grate cooler 3 is sent to a boiler 45 through a high temperature exhaust heat line 42.

In the low-temperature exhaust heat pipe 43, a dust collector 46, an exhaust fan 47, and a stack 48 are provided in this order from upstream to downstream of the exhaust gas flow. In the present embodiment, an exhaust gas line 45a of a boiler 45 is connected to the low-temperature exhaust heat line 43 upstream of the dust collector 46.

The cement production system 100 further includes: a mixing device 5 for mixing the dewatered sludge and the cement raw material to prepare a granular mixture; a dryer 6 that dries the mixture by contacting the mixture with a drying gas; a dryer exhaust gas line 7 for sending the exhaust gas from the dryer 6 to the grate cooler 3; a mixture supply line 8 for supplying the dried mixture from the dryer 6 to a preheater 21 of the cement burning apparatus 2; and a drying gas supply line 61 for supplying a drying gas to the dryer 6.

The mixing device 5 comprises: a cement raw material hopper 51; a dewatered sludge hopper 52; and a mixer 53 for mixing and delivering the cement raw material and the dewatered sludge.

The cement raw material dried, pulverized, and blended in the raw material step is charged into the cement raw material hopper 51. The cement raw material may be the same as the cement raw material supplied to the cement raw material supply port 28 of the preheater 21. The cement raw material is not particularly limited, and a known raw material containing limestone as a main component is used. Specifically, the cement raw material is usually mainly limestone, and clay, silica, iron oxide, and the like are added thereto and used. For example, the chemical composition of the cement raw material contains 12 to 15 mass% of SiO ₂ 3 to 4 mass% of Al ₂ O ₃ 1.5 to 2.5 mass% of Fe ₂ O ₃ 43 to 44 mass% CaO, 0.6 to 0.9 mass% MgO, 35 to 37 mass% volatile components, and 0 to 1 mass% (the remainder) of other materials.

The dewatered sludge is fed into the dewatered sludge hopper 52. The dewatered sludge is a solid matter (dewatered cake) remaining after dewatering sludge such as sewage sludge, factory drainage sludge, and activated sludge with a dewatering machine (not shown). Typically the dewatered sludge treated to a dewatered cake comprises 60 to 90 mass% moisture.

An outlet of the cement raw material hopper 51 is connected to an inlet of the mixer 53 via a cement raw material metering device 55. The amount of the cement raw material fed from the cement raw material hopper 51 to the mixer 53 is adjusted by the cement raw material adjusting device 55. Further, an outlet of the dewatered sludge hopper 52 is connected to an inlet of the mixer 53 via a sludge metering device 56. The amount of the dewatered sludge fed from the dewatered sludge hopper 52 to the mixer 53 is adjusted by the sludge adjusting device 56. The mixing ratio of the dewatered sludge and the cement raw material in the mixer 53 is a mass ratio or a volume ratio of the dewatered sludge and the cement raw material in the form of a mixture of the dewatered sludge and the cement raw material in the form of granules.

When the mixing ratio of the dewatered sludge and the cement raw material is within a specific range, the mixture of the dewatered sludge and the cement raw material is granulated without being subjected to granulation treatment. The mixing ratio of the dewatered sludge and the cement raw material is not constant, and varies depending on the properties of the dewatered sludge (particularly, the moisture content and the proportion of organic matter) and the properties of the cement raw material (particularly, the water content and the composition). Accordingly, it is desirable to set the mixing ratio of the dewatered sludge and the cement raw material every time the properties of the dewatered sludge and the cement raw material change. The range of the mixing ratio of the dewatered sludge and the cement raw material can be calculated, for example, by experiment.

In the present embodiment, since a fluidized bed dryer is used as the dryer 6, it is desirable that the mixture ratio of the dewatered sludge and the cement raw material is a value at which the mixture becomes an appropriate granular state as a fluid medium. Specifically, the mixing ratio of the dewatered sludge and the cement raw material is determined by a test so that the total moisture of the mixture becomes 10 mass% or more and 25 mass% or less, preferably 13 mass% or more and 22 mass% or less, and is set in advance in the control device 57. The control means 57 controls the cement raw material adjusting means 55 and the sludge adjusting means 56 to obtain the above-mentioned mixing ratio of the dewatered sludge and the cement raw material. The total moisture of the mixture is the sum of moisture as the moisture adhering to the surface of the mixture and moisture as the adsorbed moisture of the mixture. The total moisture of the mixture was measured according to the moisture determination method defined in "JIS M8812 coal and coke-industrial analysis method" for coal.

According to the test of the inventor, the following steps are confirmed: when the total moisture of the mixture is 10 mass% or more and 25 mass% or less, the particle size distribution of the mixture is small (that is, the variation in particle size is small), and a granular mixture having an average particle size suitable as a flow medium can be obtained.

The above "size suitable as a flow medium" is considered to be a range of particles having a diameter of about several μm to 5mm which can uniformly flow in the layer. In the test results of the inventors, the average particle diameter (median diameter d 50) of the mixture having a total moisture content in the range of 10 mass% to 25 mass% is 0.5mm to 5mm, and is a size suitable as a flow medium.

A mixture prepared by mixing the dewatered sludge and the cement raw material with the mixer 53 is supplied to the dryer 6. In the dryer 6, a fluidized bed is formed using the mixture as a fluidizing medium and the drying gas as a fluidizing gas. In the dryer 6, a drying gas is supplied into the mixture layer formed at the bottom of the drying chamber, and the drying gas rises into the mixture layer to contact the mixture with the drying gas, thereby drying the mixture. As such, a fluidized bed type dryer having a high drying efficiency (i.e., a large volumetric heat exchange rate) as compared with other types of dryers is used as the dryer 6. However, the dryer 6 is not limited to the fluidized bed dryer.

The drying gas is sent to the dryer 6 through the drying gas supply line 61. The air volume (air velocity) of the drying gas supplied to the dryer 6 can be adjusted by a throttle valve, a fan, or the like according to the properties (i.e., particle diameter, moisture, density, or the like) of the mixture so that the fluidized bed of the dryer 6 can be brought into an appropriate fluidized state. In the present embodiment, as the drying gas, exhaust gas from a cement production process or exhaust gas from a thermal process at 50 ℃ or higher and less than 200 ℃ is used. Examples of such exhaust gas include exhaust gas at a temperature of less than 200 ℃ from the grate cooler 3, exhaust gas at a temperature of less than 200 ℃ from the boiler 45 using the exhaust gas from the grate cooler 3, and exhaust gas at a temperature of less than 200 ℃ from the raw material mill 93 using the exhaust gas from the cement burning apparatus 2.

The mixture dried by the dryer 6 is discharged from the bottom of the drying chamber and is supplied to the calciner 22 through a mixture supply line 8. The mixture to be supplied to the calciner 22 is not particularly limited, and may have a water content of about 2 to 5 mass% and a temperature of about 60 to 100 ℃. The mixture supply line 8 includes:

conveyors

81, 82 that convey the dried mixture from the dryer 6; a mixture hopper 83 that temporarily stores the mixture; and a transfer line 84 that transfers the mixture quantitatively discharged from the mixture hopper 83. The mixture supplied to the calciner 22 through the mixture supply line 8 is used as a part of the fuel, and further, the combustion ash of the mixture is used as a part of the cement raw material.

The exhaust gas of the dryer 6 is supplied to the grate cooler 3 through a dryer exhaust gas line 7. A dust collector 71, an exhaust fan 72, and a blower fan 74 are provided in the dryer exhaust gas line 7 in this order from the upstream side to the downstream side of the dryer exhaust gas flow. The dryer exhaust gas discharged from the dryer 6 by the exhaust fan 72 is subjected to dust removal by the dust collector 71. The removed dust is sent from the dust collector 71 to the mixture hopper 83, and is supplied to the calciner 22 together with the mixture stored in the mixture hopper 83. The dryer exhaust gas flowing through the dust collector 71 is sent to the grate cooler 3 by the blower fan 74.

As described above, the cement production system 100 of the present embodiment includes the preheater 21 that preheats the cement raw material, the calciner 22 that calcines the preheated cement raw material, and the calciner 23 that calcines the calcined cement raw material; the preheater 21 has at least one inlet 29 for introducing the pellets containing the dried sludge into a temperature range of 600 ℃ or higher and less than 800 ℃.

The sludge treatment method according to the present embodiment is a method for treating sludge by using a cement production system 100, and the cement production system 100 includes: a preheater 21 for preheating the cement raw material; a calciner 22 for calcining the preheated cement raw material; and a firing furnace 23 for firing the fired cement raw material; wherein the granular material containing the dried sludge is charged into a temperature range of 600 ℃ or higher and less than 800 ℃ of the preheater 21, and the dried sludge is used as a cement raw material and a fuel.

In the present embodiment, the "granular material containing dried sludge" is a mixture of dried sludge and a cement raw material. Therefore, the cement production system 100 according to the present embodiment further includes: a mixing device 5 for mixing the dewatered sludge and the cement raw material to obtain a granular mixture; a dryer 6 that dries the mixture; and a transfer line 84 for transferring the mixture dried by the dryer 6 as pellets to the inlet 29.

However, the granular matter containing the dried sludge is not limited to the mixture of the dried sludge and the cement raw material. For example, the granular material containing the dried sludge may be a pulverized material of the dried sludge, a mixture of raw sludge and dried sludge, or the like. The size of the particulate matter may be any size as long as it can be conveyed by the exhaust gas from the calciner 22, and may be in the form of powder, flakes, or pellets.

In the above-described sludge treatment method and cement production system 100, the granular material including the dried sludge is fed into the preheater 21 in a temperature range of 600 ℃ or higher and less than 800 ℃. While the particulate matter moves from the inlet 29 (the charging position) of the preheater 21 to the calciner 22, the temperature of the particulate matter increases together with the cement raw material to the charging temperature (about 850 ℃ to 900 ℃) for charging into the calciner 22.

Conventionally, as in patent documents 1 and 2, the casting is carried out in a region of 800 ℃ or higher; in contrast, in the present invention, the residence time of the pellets in the preheater 21 is long, and the pellets are fed into the calciner 22 after being sufficiently preheated. Therefore, disturbance of the combustion state and increase in the fuel consumption due to the input of low-temperature substances into the calciner 22 can be suppressed. In addition, the temperature difference between the atmosphere temperature at the inlet 29 (the charging position) of the preheater 21 and the particulate matter is smaller than in the conventional case. Therefore, a local temperature decrease in the vicinity of the granular material inlet 29 can be suppressed, and a decrease in the life of the refractory coating layer or the occurrence of coating can be suppressed. As a result, in the cement production system 100 using the sludge as a part of the cement raw material and the fuel, it is possible to contribute to stabilization of the system operation.

In the cement production system 100 of the present embodiment, the preheater 21 includes 3 or more stages of cyclone units U1 to U5 connected in series upward from the calciner 22. The cyclone units U1 to U5 each have: cyclone separators C1-C5; ducts D1 to D5 that introduce airflows to the cyclone separators C1 to C5; and pipes B1 to B5 for sending the solids separated from the gas flow by the cyclones C1 to C5 to at least one of the ducts D1 to D4 of the cyclone units U1 to U4 at the lower stage thereof, the calciner 22, and the firing furnace 23.

From the viewpoint of extending the residence time in the preheater 21, it is preferable that the inlet 29 be provided in the duct D of the cyclone unit U at a temperature in the upper stage of the temperature region of the preheater 21 of 600 ℃. Therefore, in the present embodiment, the inlet 29 is provided in the vicinity of the inlet of the duct D3 of the cyclone unit U3 in the third stage from below. However, the temperature of the exhaust gas flowing into the duct D2 of the cyclone unit U2 in the second stage from the lower side is about 850 ℃, but immediately after that, the temperature is lowered to less than 800 ℃, and therefore, the inlet port 29 may be provided in the duct D2. As described above, in the cement production system 100 of the present embodiment, the inlet 29 may be provided in at least one of the ducts D2 and D3 of the cyclone units U2 and U3 in the second and third stages from below. In other words, the particulate matter can be fed to at least one of the ducts D2 and D3 of the cyclone units U2 and U3 in the second and third stages from below. The position of the inlet 29 can be appropriately adjusted for each preheater 21 of the cement manufacturing system 100.

When the pellets containing the dried sludge are thrown into the temperature region of the preheater 21 at a temperature of less than 600 ℃, the odor generated from the sludge contained in the pellets is discharged to the exhaust gas line 9 of the firing apparatus without being thermally decomposed. Therefore, a means for decomposing odors is required in the exhaust gas line 9 of the firing device. In addition, the temperature region of the preheater 21 above 800 ℃ is also roughly designated as the 1 st duct D1 connecting the calciner 22 and the lowest stage cyclone C1. When the granular material including the dried sludge is fed into the 1 st duct D1 of the preheater 21, the granular material passes only through the 1 st cyclone unit U1 in the preheater 21, and therefore, the temperature may not be sufficiently raised, and it may be difficult to suppress a local temperature decrease in the vicinity of the inlet 29 of the granular material.

Although the preferred embodiments of the present invention have been described above, the present invention may include modifications of the specific structures and/or detailed functions of the above embodiments without departing from the scope of the concept of the present invention.

Description of the symbols

2: cement firing device

3: grate type cooler

4: waste heat pipeline of cooler

5: mixing device

6: drying machine

7: dryer exhaust gas line

8: mixture supply line

9: exhaust gas line of firing apparatus

21: suspension preheater

22: calcining furnace

23: firing furnace

25: burner of calcining furnace

26: burner apparatus

28: cement raw material supply port

29: input port

32: cooked material conveyor

41: air exhaust pipeline for calcining furnace

42: high temperature waste heat pipeline

43: low temperature waste heat pipeline

45: boiler

45a: waste gas line

46: dust collector

47: exhaust fan

48: chimney

51: cement raw material hopper

52: dewatered sludge hopper

53: mixing machine

55: cement raw material quantity adjusting device

56: sludge quantity adjusting device

57: control device

61: drying gas supply line

71: dust collector

72: exhaust fan

74: air supply fan

81: conveyor

82: conveyor

83: mix material hopper

84: transfer line

91: boiler

92: exhaust fan

93: raw material mill

94: dust collector

95: exhaust fan

96: chimney

100: cement manufacturing system

B, B1 to B5: piping

C, C1 to C5: cyclone separator

D, D1 to D5: pipeline

U, U1 to U5: cyclone separator unit

Claims

1. A sludge treatment method for treating sludge by using a cement production system, the cement production system comprising: a suspension preheater for preheating the cement raw material; a calciner for calcining the preheated cement raw material; and a firing furnace for firing the calcined cement raw material; wherein, the first and the second end of the pipe are connected with each other,

the method comprises the following steps:

mixing the dewatered sludge with the cement raw material to prepare granules;

drying the granular material to a water content of 2 to 5 mass%;

the granular material is charged into a charging port disposed in a temperature range of 600 ℃ or higher and less than 750 ℃ of the suspension preheater, and the dried sludge is used as a cement raw material and a fuel.

2. The sludge treatment method according to claim 1, wherein,

the suspension preheater is provided with 3 or more stages of cyclone units connected in series upward from the calciner,

the cyclone separator units each have: a cyclone separator; a conduit for directing a gas stream into the cyclone; and piping for sending the solids separated from the gas stream by the cyclone to at least one of the duct of the cyclone unit, the calciner, and the firing furnace at a lower stage thereof;

the particulate matter is fed into at least one of the ducts of the cyclone units in the second and third stages from below.

3. A cement production system is provided with: a mixing device for mixing the dewatered sludge and a cement raw material to produce granules; a dryer that dries the granular material to a water content of 2 to 5 mass%; a suspension preheater for preheating the cement raw material; a calciner for calcining the preheated cement raw material; a firing furnace for firing the calcined cement raw material; and a transfer line for transferring the pellets dried by the dryer to a feed port of the suspension preheater;

the suspension preheater has at least 1 of the input ports that input the pellets to a temperature zone above 600 ℃ and less than 750 ℃.

4. A cement manufacturing system as claimed in claim 3, wherein said suspension preheater is provided with 3 or more stages of cyclone units connected in series upward from said calciner,

the inlet is provided in at least one of the ducts of the cyclone units in the second and third stages from below.