JP2024053731A - Cement clinker manufacturing equipment, cement clinker manufacturing method, and mercury removal method - Google Patents

Abstract

To provide a facility for producing a cement clinker capable of efficiently removing mercury.SOLUTION: A facility 1 for producing a cement clinker includes a raw material preparation device 2, a calcination device 3, and a mercury removing device 4, wherein the mercury removing device 4 has: a dust collector 41 for collecting dust in exhaust gas discharged from the raw material preparation device 2 or the calcination device 3; a mercury vaporization chamber 42 for heating the dust collected by the dust collector 41 to vaporize mercury attached to the dust; and a mercury adsorbing chamber 43 for adsorbing the mercury vaporized in the mercury vaporization chamber 42 onto an adsorbent.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cement clinker manufacturing facility and manufacturing method for manufacturing cement clinker while removing mercury. It also relates to a mercury removal method for removing mercury during the cement clinker manufacturing process.

When mercury (including mercury compounds) is contained in natural raw materials such as limestone, fuels such as coal and heavy oil, or waste materials such as sludge and incineration ash used in the cement clinker manufacturing process, the mercury vaporizes and becomes mercury gas in the high-temperature parts of cement clinker manufacturing equipment such as rotary kilns. The mercury gas-containing exhaust gas generated in the rotary kiln is sent to a raw material dryer or other raw material preparation device in order to use the residual heat for drying raw materials. After passing through the raw material dryer or other raw material preparation device, the exhaust gas is sent to a dust collection device such as a bag filter or an electric dust collector, and the dust contained in the exhaust gas is collected. Mercury condenses and adheres to this dust as the temperature decreases, or even if it does not condense, it is adsorbed to the dust (in this invention, both are simply referred to as "adhering"). Therefore, by collecting this dust, mercury is removed from the exhaust gas. Meanwhile, the collected dust is reused as a cement clinker raw material.

However, as mentioned above, when the raw materials and fuel brought into the cement clinker manufacturing facility contain a large amount of mercury, there is a risk that the mercury gas sent to the dust recovery device together with the exhaust gas will not completely adhere to the dust and will be released in that state into the atmosphere from the chimney together with the exhaust gas.

As a solution to these problems, for example, Patent Document 1 discloses an invention entitled "Method for Removing Mercury from Combustion Exhaust Gas," which relates to a method for easily and at low cost to remove mercury contained in combustion exhaust gas generated in cement manufacturing facilities.

The invention disclosed in Patent Document 1 is characterized in that the flue gas discharged from the top cyclone of a suspension preheater in a cement manufacturing facility is introduced into a coal drying and crushing device, and the mercury contained in the flue gas is adsorbed onto the pulverized coal obtained by crushing the coal in the coal drying and crushing device, and then the flue gas and the pulverized coal are introduced into a bag filter to capture only the pulverized coal, thereby purifying the flue gas.

This mercury removal method, which uses a coal drying and crushing device that is ancillary equipment of a cement manufacturing facility, does not require the installation of new mercury removal equipment, and therefore can easily purify combustion exhaust gas at low cost.

Patent Document 2, titled "Method for treating exhaust gas from a cement kiln," discloses an invention that is related to a method for removing mercury, organic chlorine compounds, and dust from exhaust gas generated in a cement kiln, which uses various types of waste as raw materials and fuel.

The invention disclosed in Patent Document 2 is characterized in that exhaust gas is extracted from a dust collector and sent to an adsorption tower, where mercury and organic chlorine compounds contained in the exhaust gas are adsorbed onto activated carbon or pulverized coal, and the activated carbon or pulverized coal is then heated to 400°C or higher in a heating furnace to remove the mercury and organic chlorine compounds, and the activated carbon or pulverized coal obtained in this process is then fed into a cement kiln.

This method of treating exhaust gas from cement kilns makes it possible to downsize the heating furnace used to remove mercury and organic chlorine compounds, and to reduce the energy required for heating.

JP 2010-75784 A JP 2006-96615 A

As mentioned above, various methods have been proposed for removing mercury from exhaust gases generated in cement manufacturing facilities, but new methods for removing mercury more efficiently are needed.

The objective of the present invention is to provide a cement clinker manufacturing facility and manufacturing method capable of efficiently removing mercury. It is also to provide a mercury removal method capable of efficiently removing mercury in the cement clinker manufacturing process.

As a result of intensive research into solving the above problems, the inventors discovered that by capturing and recovering dust in exhaust gas and subjecting the dust to a specified treatment, it is possible to efficiently remove mercury from exhaust gas as well as from within the cement clinker production system, and thus completed the present invention.

That is, the present invention is as follows.
[1] A cement clinker production facility including a raw material preparation device, a calcination device, and a mercury removal device,
The mercury removal device comprises:
a dust recovery device that captures and recovers dust in exhaust gas discharged from the raw material preparation device or the calcination device;
a mercury vaporization chamber for heating the dust collected by the dust collection device to vaporize mercury adhering to the dust;
a mercury adsorption chamber for adsorbing the mercury vaporized in the mercury vaporization chamber onto an adsorbent;
A cement clinker production facility comprising:
[2] The mercury adsorption chamber comprises:
a stirring means for stirring the adsorbent contained in the mercury adsorption chamber, the stirring means comprising a rotating shaft and a stirring blade provided on the rotating shaft;
a mercury gas introduction means for introducing the mercury vaporized in the mercury vaporization chamber;
an adsorbent supplying means for continuously or intermittently supplying additional adsorbent;
an adsorbent discharge means for continuously or intermittently discharging the adsorbent to which mercury has been adsorbed;
The cement clinker production facility according to [1], further comprising:
[3] The cement clinker production facility according to [1] or [2], characterized in that the volume of the mercury adsorption chamber is smaller than the volume of the mercury vaporization chamber.

[4] The cement clinker production facility according to any one of [1] to [3], characterized in that the mercury vaporization chamber is equipped with a heating means for maintaining an inside temperature of the chamber at 370°C or higher, and the mercury adsorption chamber is equipped with a heating means for maintaining an inside temperature of the chamber at more than 100°C and not more than 200°C.
[5] The cement clinker production facility according to any one of [1] to [4], wherein the adsorbent is at least one selected from the group consisting of cement dust, fly ash, and coal ash.
[6] The cement clinker production facility according to any one of [1] to [5], characterized in that the mercury removal device includes a mercury separation and recovery device that separates and recovers the mercury adsorbed by the adsorbent in the mercury adsorption chamber.
[7] The cement clinker production facility according to [6], wherein the mercury separation and recovery device is provided with an adsorbent introducing means for introducing the adsorbent from which mercury has been separated into a raw material preparation device or a calcination device.

[8] A method for removing mercury from exhaust gas generated in the production of cement clinker, comprising the steps of:
a dust recovery step of collecting and recovering dust in the exhaust gas;
a mercury vaporization step of heating the dust collected in the dust collection step to vaporize mercury adhering to the dust;
a mercury adsorption step of adsorbing the mercury vaporized in the mercury vaporization step onto an adsorbent;
A method for removing mercury comprising the steps of:
[9] The mercury removal method according to [8], wherein the mercury adsorption step is a step of introducing vaporized mercury into a mercury adsorption chamber while stirring a predetermined amount of adsorbent contained therein to adsorb mercury onto the adsorbent, and wherein additional adsorbent is introduced continuously or intermittently while the adsorbent with mercury adsorbed thereon is discharged continuously or intermittently.
[10] The mercury removal method according to [8] or [9], wherein the volume of the adsorbent used in the mercury adsorption step is smaller than the volume of the dust treated in the mercury vaporization step.
[11] The mercury removal method according to any one of [8] to [10], wherein the treatment temperature in the mercury vaporization step is 370°C or higher, and the treatment temperature in the mercury adsorption step is higher than 100°C and lower than 200°C.

[12] The method for removing mercury according to any one of [8] to [11], wherein the adsorbent is at least one selected from the group consisting of cement dust, fly ash, and coal ash.
[13] The mercury removal method according to any one of [8] to [12], further comprising a mercury separation and recovery step of separating and recovering the mercury adsorbed onto the adsorbent in the mercury adsorption step, from the adsorbent.
[14] A method for producing cement clinker while carrying out the mercury removal method according to [13], comprising the steps of:
A method for producing cement clinker, comprising the steps of: separating mercury from an adsorbent in a mercury separation and recovery process; and using the adsorbent as a raw material in a cement clinker production process.

The cement clinker manufacturing equipment and manufacturing method of the present invention can efficiently remove mercury from exhaust gas and can efficiently remove mercury from within the system. Furthermore, the mercury removal method of the present invention can efficiently remove mercury in the cement clinker manufacturing process.

1 is a schematic diagram showing an entire cement clinker production facility according to an embodiment of the present invention. 1 is a schematic diagram of a mercury removal device for a cement clinker production facility according to an embodiment of the present invention. 1 is a schematic diagram of a mercury adsorption chamber of a mercury removal device in a cement clinker production facility according to one embodiment of the present invention.

The cement clinker manufacturing facility of the present invention comprises a raw material preparation device, a calcination device, and a mercury removal device. The mercury removal device comprises a dust recovery device that captures and recovers dust in the exhaust gas discharged from the raw material preparation device or the calcination device, a mercury vaporization chamber that heats the dust recovered by the dust recovery device to vaporize the mercury (including mercury compounds; the same applies below) attached to the dust, and a mercury adsorption chamber that adsorbs the mercury vaporized in the mercury vaporization chamber onto an adsorbent.

The raw material preparation equipment includes a raw material dryer and a raw material mill. The calcination equipment includes a cyclone and a calcination furnace, a preheater section that calcines the cement clinker raw material, and a rotary kiln that calcines the calcined cement clinker raw material.

In the present invention, the exhaust gas for recovering dust is not particularly limited as long as it is gas before being discharged into the atmosphere from the raw material preparation device or the calcination device, and is preferably exhaust gas discharged from the rotary kiln of the calcination device, and more preferably exhaust gas discharged from the rotary kiln and then introduced into the raw material dryer of the raw material preparation device and discharged.

In the cement clinker manufacturing facility of the present invention, mercury can be efficiently removed from the exhaust gas and from the system by treatment in the mercury removal device, which includes a dust recovery device, a mercury vaporization chamber, and a mercury adsorption chamber. In addition, in the present invention, volatile heavy metals such as zinc, lead, and cadmium can also be removed at the same time as mercury.

Below, a cement clinker production facility according to one embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the entire cement clinker production facility. Note that the solid arrows in the figure represent the flow of raw materials moving through the cement clinker production facility, the dotted arrows represent the flow of exhaust gas, and the dashed arrows represent the flow of dust collected from the exhaust gas by the dust collection device.

As shown in FIG. 1, the cement clinker production facility 1 includes a raw material preparation device 2 that prepares the cement clinker raw material, a calcination device 3 that calcines the cement clinker raw material prepared by the raw material preparation device 2, and a mercury removal device 4 that removes mercury from the exhaust gas.

The raw material preparation device 2 includes a raw material dryer 21, a raw material mill 22, a raw material mixing silo 23, and a raw material storage silo 24. The raw material preparation device 2 is used to prepare the cement clinker raw materials (raw material preparation process).

In the raw material preparation process, limestone, clay, silica, iron oxide raw materials, etc. are mixed and then sent to the raw material dryer 21 for drying. In the raw material dryer 21, the raw materials are dried using high-temperature exhaust gas sent from the calcination device 3. The raw materials are then sent to the raw material mill 22 for pulverization. The raw materials pulverized in the raw material mill 22 are sent to the raw material mixing silo 23 and homogeneously blended, and then stored in the raw material storage silo 24. Meanwhile, the exhaust gas discharged from the raw material dryer 21 is sent to the hydrogen removal device 4.

The calcination device 3 is equipped with multiple cyclones 31 and a calcination furnace 32, a preheater section 33 for calcining the cement clinker raw materials, a rotary kiln 34 for calcining the calcined cement clinker raw materials, and a clinker cooler 35 for cooling the calcined cement clinker. The calcination device 3 is used to calcinate the cement clinker raw materials (calcination process).

In the firing process, the powdered raw materials that have been dried, crushed, etc. in the raw material preparation process are sent to the preheater section 33 and pre-fired. The rotary kiln 34 has a gentle slope, and the powdered raw materials preheated in the preheater section 33 are fired at a high temperature (e.g., about 1450°C) while moving slowly inside the rotary kiln 34 due to this slope and rotational motion. The powdered raw materials fired in the rotary kiln 34 are rapidly cooled in the clinker cooler 35 and become a black, lumpy fired product called cement clinker.

Following the firing process, a finishing process is carried out in which gypsum and other materials are added to the produced cement clinker to produce cement.

Next, the main flow of exhaust gas in the cement clinker manufacturing process will be described.
As shown by the dotted arrow in Figure 1, the exhaust gas generated in the rotary kiln 34 rises inside the preheater section 33 against the flow of the powder raw material, and is discharged from the topmost cyclone 31. This exhaust gas is then sent to the raw material dryer 21 so that its residual heat can be used to dry the raw materials. The exhaust gas discharged from the raw material dryer 21 is sent to the mercury removal device 4, where mercury (mercury-containing dust) is removed, and the exhaust gas is then released into the atmosphere from the chimney 5. Therefore, the exhaust gas released to the outside contains almost no mercury.

Note that mercury vaporizes into mercury gas inside the preheater section 33 and rotary kiln 34, so it is not included in the cement clinker sent to the finishing process.

Next, the mercury removal device 4 will be described with reference to Figures 2 and 3. Figure 2 is a schematic diagram of a mercury removal device in a cement clinker production facility according to one embodiment of the present invention, and Figure 3 is a schematic diagram of the mercury adsorption chamber of the mercury removal device.

As shown in FIG. 2, the mercury removal device 4 includes a dust collection device 41, a mercury vaporization chamber 42, a mercury adsorption chamber 43, and a mercury separation and recovery device 44.

(Dust collection device)
The dust collection device 41 includes a bag filter 45 (first bag filter), a cyclone 46 that classifies the dust collected from the bag filter 45, and a bag filter 47 (second bag filter) that collects fine dust particles obtained by classification in the cyclone 46.

First, dust is collected from the exhaust gas discharged from the raw material dryer 21 by the bag filter 45. A portion of this collected dust is sent to the cyclone 46, and the remaining dust is returned to the clinker production facility 1 system. In the cyclone 46, fine dust particles are separated, and the fine dust particles are collected in the bag filter 47. The relatively heavy dust particles are returned to the clinker production facility 1 system. Fine dust particles have a high concentration of mercury, so by removing this, the mercury can be removed efficiently.

The dust collection device is not particularly limited as long as it can collect dust from the exhaust gas, and in addition to a bag filter, an electric dust collector can be used. In order to collect fine dust particles, it is preferable to combine it with a cyclone (powder separator) as necessary. When using a multi-stage electric dust collector, it is preferable to collect dust from the latter stage in order to collect fine dust particles with a high mercury concentration.

(Mercury vaporization chamber)
The mercury vaporization chamber 42 is a means for vaporizing the mercury adhering to the dust by heating the fine particles of dust with a high mercury concentration collected by the dust collection device 41. In the mercury vaporization chamber 42, a mercury vaporization process is carried out.

The mercury vaporization chamber 42 is equipped with a heating means and a stirring means, and heats the dust introduced into the mercury vaporization chamber 42 while stirring it, vaporizing the mercury attached to the dust into mercury gas. Dust is continuously or intermittently introduced into the mercury vaporization chamber 42 from the bag filter 47 of the dust recovery device 41, and the mercury gas vaporized in the mercury vaporization chamber 42 is sent to the downstream mercury adsorption chamber 43 together with the carrier gas. The dust from which the mercury has been removed in the mercury vaporization chamber 42 is continuously or intermittently discharged and returned to the system of the cement clinker production facility 1.

The capacity of the mercury vaporization chamber is, for example, 0.5 to ²⁰ m3, and preferably 1 to ¹⁰ m3. The temperature inside the mercury vaporization chamber is preferably maintained at 370° C. or higher by a heating means, more preferably at 400° C. or higher, and even more preferably at 450° C. or higher. By heating to a temperature in this range, mercury can be effectively vaporized and removed from the dust, since the boiling point of mercury is 356° C.

(Mercury adsorption chamber)
The mercury adsorption chamber 43 is a means for adsorbing the mercury (mercury gas) vaporized in the mercury vaporization chamber 42 onto an adsorbent. In this mercury adsorption chamber 43, a mercury adsorption process is carried out.

Specifically, the mercury adsorption process is a process in which, for example, vaporized mercury gas is introduced into the mercury adsorption chamber while a predetermined amount of adsorbent is stirred to adsorb the mercury to the adsorbent, and at the same time, additional adsorbent is continuously or intermittently introduced while the adsorbent with the adsorbed mercury is continuously or intermittently discharged.

The mercury adsorption chamber 43 is not particularly limited as long as it is a means capable of adsorbing mercury gas to the adsorbent. For example, as shown in Figures 2 and 3, it can be equipped with a rotating shaft 49 arranged horizontally and an agitating blade 50 attached to the rotating shaft 49, and includes a stirring means 51 for stirring the adsorbent contained in the mercury adsorption chamber 43, a mercury gas introduction means 52 for introducing the mercury vaporized in the mercury vaporization chamber 42, an adsorbent introduction means 53 for continuously or intermittently introducing additional adsorbent, and an adsorbent discharge means 54 for continuously or intermittently discharging the adsorbent to which mercury has been adsorbed.

The capacity of the mercury adsorption chamber is preferably smaller than that of the mercury vaporization chamber, preferably 1/2 or less, more preferably 1/3 or less, and even more preferably 1/4 or less, and the lower limit may be appropriately determined in consideration of the treatment efficiency, but is, for example, 1/20 or more. Specifically, it is, for example, 0.05 to ¹⁰ m3, and preferably 0.1 to 5 ^m3 .

The volume of the adsorbent used is preferably smaller than the volume of the treated dust, preferably 1/2 or less, more preferably 1/5 or less, and even more preferably 1/10 or less, with the lower limit being determined appropriately in consideration of the efficiency of mercury recovery, for example 1/50 or more. This allows mercury to be concentrated and recovered, and the subsequent mercury separation and recovery process and disposal of the adsorbent can be carried out efficiently.

The mercury adsorption chamber is preferably heated to a temperature above 100°C and below 200°C, more preferably between 110 and 180°C, and even more preferably between 120 and 150°C. By maintaining the temperature within this range, the mercury gas can be sufficiently cooled and sufficiently adsorbed by the adsorbent. In addition, the adsorbent often contains moisture, but even in this case, the moisture is discharged as water vapor, so the inside of the mercury adsorption chamber can be kept dry and the adsorbent can be prevented from adhering to the inner walls of the chamber.

The adsorbent is not particularly limited as long as it can adsorb mercury, and may be cement dust, fly ash, coal ash, or the like. Of these, coal ash is preferred because it is lightweight and has high adsorption performance. When cement dust is used as the adsorbent, dust collected by the bag filter 45 may be used, but it is preferable to use fine particle dust collected by the bag filter 47 (fine particle dust introduced into the mercury vaporization chamber).

The bulk density (loose bulk density) of the adsorbent is preferably 0.2 to 1.0 g/cm ³ , more preferably 0.3 to 0.8 g/cm ³ , and even more preferably 0.4 to 0.7 g/cm ^3. The average particle size (volume basis) of the adsorbent is generally preferably 0.001 to 1 mm, and more preferably 0.002 to 0.5 mm. However, in the case of coal ash, a relatively large particle size is preferable, and for example, the average particle size is preferably 0.02 to 2 mm, and more preferably 0.05 to 1 mm.

The bulk density (loose bulk density) is measured, for example, using a Scott volumeter conforming to ASTM 32990. The average particle size (volume basis) is measured, for example, using a laser diffraction/scattering method conforming to JIS Z 8825-1.

In this embodiment, the mercury adsorption chamber 43 is a horizontal type with the rotating shaft 49 arranged horizontally, but it may be a vertical type with the rotating shaft arranged vertically, or an inclined type with the rotating shaft arranged diagonally. In addition, as shown in FIG. 3, it is preferable that the mercury gas introduction means 52 is provided with a heating means 56 and a heat insulating material 57 around the gas ventilation pipe 55 to maintain a high temperature (e.g., 370°C or higher) up to the tip (just before release). This makes it possible to prevent blockage of the gas ventilation pipe 55 due to solidification of heavy metal-containing gas such as mercury gas.

The exhaust gas discharged from the mercury adsorption chamber 43 may be treated with activated carbon or the like before being released into the atmosphere, but it is preferable to return it to the cement clinker production facility 1 system in order to utilize the residual heat.

(Mercury separation and recovery equipment)
The mercury adsorbed to the adsorbent in the mercury adsorption chamber is preferably separated from the adsorbent and recovered by a mercury separation and recovery device. For example, as shown in Fig. 2, an example of the mercury separation and recovery device is a mercury separation and recovery device 44 equipped with a first heating furnace (temperature-raising furnace) 58 for heating the adsorbent introduced, a second heating furnace (constant temperature furnace) 59 for maintaining the adsorbent at a high temperature and separating mercury from the adsorbent, and a cooler 60 for cooling the adsorbent from which mercury has been separated. Specifically, a so-called Hagenmeyer furnace can be used as the mercury separation and recovery device 44, which allows for simultaneous decomposition of dioxins.

The first heating furnace 58 and the second heating furnace 59 are structured to allow the introduction of an inert gas such as nitrogen gas. The inert gas creates an oxygen-deficient state inside the furnace with an oxygen concentration of 0.1% or less, and the furnace is heated to a temperature of approximately 400°C to 600°C in this oxygen-deficient reducing atmosphere. The heat treatment in the first heating furnace 58 and the second heating furnace 59 vaporizes mercury, which has a boiling point of 356°C, into mercury gas, and the mercury is separated from the adsorbent. In addition, mercury oxide and mercury chloride are not produced, and the mercury can be recovered in the form of metal mercury.

The mercury gas (and water vapor) generated in the second heating furnace 59 is cooled, and the metallic mercury is recovered in the metallic mercury recovery device 61. The metallic mercury recovery device 61 is designed so that mercury, which has a higher specific gravity than water, accumulates at the bottom, and water, which has a lower specific gravity than mercury, accumulates above the mercury, making it possible to recover the metallic mercury.

Meanwhile, in the cooler 60, the adsorbent that has been removed from the second heating furnace 59 and from which the mercury has been removed is cooled to about 70°C. If the cooling rate is slow, the dioxin that has once decomposed will be resynthesized at around 250°C, so it is preferable to cool it quickly (for example, by quickly lowering the temperature to 70°C in about 60 minutes). This prevents the resynthesis of dioxin.

The adsorbent from which mercury has been separated and cooled in the cooler 60 is preferably returned to the system of the cement clinker production facility 1. In other words, the mercury separation and recovery device 44 is preferably equipped with an adsorbent introduction means 62 that introduces the adsorbent from which mercury has been separated into the raw material preparation device 2 or the calcination device 3. This allows the adsorbent from which mercury has been separated in the mercury separation and recovery device to be used in the cement clinker production process, and the adsorbent can be effectively used as a raw material for cement clinker.

The mercury removal method of the present invention can be carried out using the cement clinker production equipment of the present invention. That is, the mercury removal method of the present invention is a method for removing mercury attached to dust in exhaust gas generated in the production of cement clinker, and includes a dust recovery process for capturing and recovering dust in the exhaust gas, a mercury vaporization process for heating the dust recovered in the dust recovery process to vaporize the mercury attached to the dust, and a mercury adsorption process for adsorbing the mercury vaporized in the mercury vaporization process onto an adsorbent. Each process is the same as that described in the cement clinker production equipment of the present invention, so a description thereof will be omitted.

[Example 1]
Below, we confirmed the relationship between dust particle size and the mercury content in the dust.
Specifically, dust collected in the bag filter 45 (first bag filter) was classified using a cyclone 46, and the relationship between the particle size and the mercury concentration was examined. The results are shown in Table 1. Note that "D10,""D50," and "D90" in the table refer to particle sizes at which the cumulative frequency is 10%, 50%, and 90%, respectively.

As is clear from Table 1, the mercury concentration of the dust before classification was 28.0 ppm, whereas the mercury concentration of the dust after classification was about 0.8 times that of coarse powder (D50 = 17.79 μm) and about 1.6 times that of fine powder (D50 = 2.91 μm). This means that in order to reduce the amount of mercury contained in the raw materials and fuel brought into the cement production process system and circulating in the raw material preparation process and the firing process, it is effective to remove mercury contained in the fine particle dust (corresponding to the fine powder shown in Table 1) obtained by classifying the dust recovered from the bag filter 45 (first bag filter).
The fine powder obtained by classifying the dust at this time had a loose bulk density of 0.66 g/cm ³ .

[Example 2]
Next, the effect of mercury removal using the mercury removal device (mercury vaporization chamber and mercury adsorption chamber) of the present invention was confirmed.
Specifically, ^{4,300 cm3} (2,838 g) of fine dust collected in the bag filter 47 (second bag filter) was divided into 4,100 ^cm3 (2,706 g) as a first dust and 200 ^cm3 (132 g) as a second dust, the first dust was supplied to the mercury vaporization chamber 42 and heated to about 500°C to gasify the mercury, and the mercury gas was brought into contact with the second dust as an adsorbent at about 100°C in the mercury adsorption chamber 43, thereby recovering the second dust containing a high concentration of mercury. The results are shown in Table 2.

As is clear from Table 2, the mercury concentrations of the first and second dusts fed were 44.2 ppm, while the mercury concentration of the first dust discharged was 0.4 ppm, and the mercury concentration of the second dust (adsorbent) was 675.4 ppm (concentration ratio of approximately 15 times). Therefore, according to the method of the present invention, it is possible to adsorb and recover high concentrations of mercury on a small amount of adsorbent, making it possible to reduce the amount of processing in subsequent processes such as mercury separation.

[Example 3]
In Example 2, coal ash was used instead of the second dust used as the adsorbent, and the effect of mercury removal using the mercury removal device (mercury vaporization chamber and mercury adsorption chamber) of the present invention was confirmed. Coal ash was obtained from a thermal power generation facility in Tokuyama Corporation and treated with a 90 μm vibrating sieve to obtain sieved coal ash. The loose bulk density of the sieved coal ash obtained in this manner was 0.51 g/ ^cm3 .

Specifically, the fine dust obtained in Example 1 was supplied to the mercury vaporization chamber 42, and the coal ash was supplied to the mercury adsorption chamber 43. The mercury vaporization chamber 42 was heated to about 500°C to gasify the mercury, and the mercury gas was brought into contact with the coal ash as an adsorbent in the mercury adsorption chamber 43 at about 110°C to recover coal ash containing a high concentration of mercury. The results are shown in Table 3.

As is clear from Table 3, the mercury concentrations of the charged fine dust and coal ash were 44.2 ppm and 2.2 ppm, respectively, whereas the mercury concentration of the discharged fine dust was 0.5 ppm and the mercury concentration of the coal ash (adsorbent) was 515.2 ppm (a concentration ratio of approximately 12 times). Therefore, according to the method of the present invention, it is possible to adsorb and recover high concentrations of mercury on a small amount of adsorbent, making it possible to reduce the amount of processing in subsequent processes such as mercury separation.

The cement clinker production equipment of the present invention is industrially useful because it can produce cement clinker while suppressing mercury emissions into the atmosphere.

Reference Signs List 1: Cement clinker manufacturing equipment 2: Raw material preparation equipment 3: Calcination equipment 4: Mercury removal equipment 5: Chimney 21: Raw material dryer 22: Raw material mill 23: Raw material mixing silo 24: Raw material storage silo 31: Cyclone 32: Calcination furnace 33: Preheater section 34: Rotary kiln 35: Clinker cooler 41: Dust recovery equipment 42: Mercury vaporization chamber 43: Mercury adsorption chamber 44: Mercury separation and recovery equipment 45: Bag filter (first bag filter)
46...Cyclone 47...Bag filter (second bag filter)
49: Rotating shaft 50: Stirring blade 51: Stirring means 52: Mercury gas introducing means 53: Adsorbent introducing means 54: Adsorbent discharging means 55: Gas vent pipe 56: Heating means 57: Heat retaining material 58: First heating furnace (heating furnace)
59...Second heating furnace (constant temperature furnace)
60: Cooler 61: Metallic mercury recovery device 62: Adsorbent introduction means

Claims (14)

A cement clinker production facility including a raw material preparation device, a calcination device, and a mercury removal device,
The mercury removal device comprises:
a dust recovery device that captures and recovers dust in exhaust gas discharged from the raw material preparation device or the calcination device;
a mercury vaporization chamber for heating the dust collected by the dust collection device to vaporize mercury adhering to the dust;
a mercury adsorption chamber for adsorbing the mercury vaporized in the mercury vaporization chamber onto an adsorbent;
A cement clinker production facility comprising: The mercury adsorption chamber comprises:
a stirring means for stirring the adsorbent contained in the mercury adsorption chamber, the stirring means comprising a rotating shaft and a stirring blade provided on the rotating shaft;
a mercury gas introduction means for introducing the mercury vaporized in the mercury vaporization chamber;
an adsorbent supplying means for continuously or intermittently supplying additional adsorbent;
an adsorbent discharge means for continuously or intermittently discharging the adsorbent to which mercury has been adsorbed;
2. The cement clinker production facility according to claim 1, further comprising: The cement clinker production facility according to claim 1 or 2, characterized in that the capacity of the mercury adsorption chamber is smaller than the capacity of the mercury vaporization chamber. The cement clinker production facility according to claim 1 or 2, characterized in that the mercury vaporization chamber is equipped with a heating means for maintaining the inside of the chamber at 370°C or higher, and the mercury adsorption chamber is equipped with a heating means for maintaining the inside of the chamber at more than 100°C and not more than 200°C. The cement clinker production facility according to claim 1 or 2, characterized in that the adsorbent is at least one selected from cement dust, fly ash, and coal ash. The cement clinker production facility according to claim 1 or 2, characterized in that the mercury removal device is equipped with a mercury separation and recovery device that separates and recovers the mercury adsorbed by the adsorbent in the mercury adsorption chamber. The cement clinker production facility according to claim 6, characterized in that the mercury separation and recovery device is equipped with an adsorbent introduction means for introducing the adsorbent from which mercury has been separated into a raw material preparation device or a calcination device. A method for removing mercury from exhaust gas generated in the production of cement clinker, comprising the steps of:
a dust recovery step of collecting and recovering dust in the exhaust gas;
a mercury vaporization step of heating the dust collected in the dust collection step to vaporize mercury adhering to the dust;
a mercury adsorption step of adsorbing the mercury vaporized in the mercury vaporization step onto an adsorbent;
A method for removing mercury comprising the steps of: The mercury removal method according to claim 8, characterized in that the mercury adsorption process is a process in which vaporized mercury is introduced into the mercury adsorption chamber while stirring a predetermined amount of adsorbent contained therein to adsorb the mercury to the adsorbent, and additional adsorbent is continuously or intermittently introduced while the adsorbent to which mercury has been adsorbed is continuously or intermittently discharged. The mercury removal method according to claim 8 or 9, characterized in that the volume of the adsorbent used in the mercury adsorption process is smaller than the volume of the dust treated in the mercury vaporization process. The mercury removal method according to claim 8 or 9, characterized in that the processing temperature in the mercury vaporization process is 370°C or higher, and the processing temperature in the mercury adsorption process is higher than 100°C and lower than 200°C. The mercury removal method according to claim 8 or 9, characterized in that the adsorbent is at least one selected from cement dust, fly ash, and coal ash. The mercury removal method according to claim 8 or 9, further comprising a mercury separation and recovery process for separating and recovering the mercury adsorbed to the adsorbent in the mercury adsorption process from the adsorbent. A method for producing cement clinker while carrying out the mercury removal method according to claim 13, comprising the steps of:
A method for producing cement clinker, comprising the steps of: separating mercury from an adsorbent in a mercury separation and recovery process; and using the adsorbent as a raw material in a cement clinker production process.