JP7744183B2 - Sludge supply device, cement clinker manufacturing device, and cement clinker manufacturing method - Google Patents

Description

This disclosure relates to a sludge supply device, a cement clinker manufacturing device, and a cement clinker manufacturing method.

Patent Document 1 discloses a method for transporting low-moisture content sludge. This transportation method includes the steps of crushing the sludge to form lumps, adding a lubricant to the lumps, and transporting the lubricant-added lumps via a pressure pump. Furthermore, this transportation method involves adjusting the moisture content of the lumps.

Japanese Patent Application Laid-Open No. 2007-260526

This disclosure provides a sludge supply device, cement clinker manufacturing device, and cement clinker manufacturing method that are useful for achieving both reduced transportation problems and improved combustion efficiency for sludge supplied to a heating furnace.

A sludge supplying device according to one aspect of the present disclosure is a device that supplies sludge to a heating furnace that heats cement raw materials. This sludge supplying device includes a hopper that stores sludge, a screw feeder that sends the sludge in the hopper downstream by rotating a screw in an internal space connected to the hopper's discharge outlet, and a liquid injection unit that supplies liquid to at least the portion of the internal space that connects to the discharge outlet. When the connection is divided into two virtual regions in the center of the sludge discharge direction, the liquid injection unit supplies liquid to the connection so that the amount of liquid supplied to one of the upstream regions is greater than the amount supplied to the other downstream region.

When the moisture content of sludge delivered by a screw feeder becomes low, the load on the motor driving the screw increases. If the moisture content of the sludge becomes extremely low, the motor may become overloaded, resulting in transportation problems such as the inability to deliver the sludge. On the other hand, if a large amount of liquid is supplied to avoid overloading the motor, sludge containing a large amount of moisture may be supplied to the heating furnace, which may reduce the combustion efficiency of the heating furnace. In response, it has been discovered that when sludge is introduced into the internal space from the hopper's discharge outlet, more sludge is introduced into the internal space in the upstream portion of the hopper than in the downstream portion of the hopper in the direction of sludge delivery. In the sludge supply device described above, the amount of liquid supplied to one upstream region is greater than the amount of liquid supplied to the other downstream region. This allows for efficient supply of liquid to the sludge, and motor overload can be avoided by supplying the minimum necessary amount of moisture. Therefore, this sludge supply device is useful for achieving both reduced transportation problems and improved combustion efficiency for sludge supplied to a heating furnace.

The liquid injection section may include multiple supply pipes arranged in a row along the sludge discharge direction, each supplying liquid to at least the connected portion. Of the multiple supply pipes, the supply pipe supplying the largest amount of liquid may be arranged at the most upstream position. In the internal space connected to the hopper's discharge outlet, voids may form in the more upstream portion of the sludge discharge direction as the sludge is discharged. Therefore, a larger amount of new sludge is introduced from inside the hopper to the upstream portion of the internal space. With the above configuration, the most liquid is supplied from the most upstream supply pipe, allowing for more efficient liquid supply to the sludge. This is therefore useful for preventing transport problems that could result in the motor becoming overloaded while suppressing an increase in the amount of liquid supplied.

The sludge contained in the hopper may include at least one selected from the group consisting of sewage sludge, human waste sludge, and excess sludge. In this case, the flow path within the pipe through which the sludge is transported must be sealed to prevent the sludge's odor from leaking to the outside. If the sludge has a low moisture content, problems may occur in which the sludge cannot be transported within the pipe, but the liquid injection section supplies liquid to the sludge. Therefore, this is useful for preventing transportation problems when transporting sludge containing any one of sewage sludge, human waste sludge, and excess sludge in a sealed state.

The moisture content of the sludge contained in the hopper may be 80% or less. If the moisture content of the sludge is 80% or less, there is a high possibility that the motor that rotates the screw will become overloaded unless liquid is supplied from the liquid injection section. In the above-mentioned sludge supply device, by supplying more liquid from the upstream region, it is possible to avoid an increase in the amount of liquid supplied while reducing the possibility of the motor becoming overloaded. Therefore, this is useful for reducing transportation problems when transporting sludge with a low moisture content.

The liquid supplied by the liquid injection unit may include industrial wastewater. In this case, the industrial wastewater is introduced into the heating furnace along with the sludge. Therefore, the industrial wastewater can be treated while being used to reduce sludge transportation problems.

The sludge supply device may further include a drive unit that rotates the screw, and a control unit that controls the drive unit and the liquid injection unit. The control unit may adjust the amount of liquid supplied from the liquid injection unit so that the value of the current output to the drive unit falls within a predetermined set range. In this case, even if the value of the current output to the drive unit increases, the amount of liquid supplied is adjusted to increase, thereby reducing the load on the drive unit's motor. This is therefore useful for reducing the frequency of problems such as the motor becoming overloaded and sludge transport stopping.

The sludge supply device may further include a pumping unit that pumps the sludge delivered from the screw feeder toward the heating furnace through a transport pipe connected to the heating furnace. The sludge pumped by the pumping unit may be supplied to the inside of the heating furnace without being dewatered. In the sludge supply device, the increase in the amount of liquid supplied to the sludge is suppressed, and even without dewatering, the extent of the decrease in combustion efficiency in the heating furnace caused by the supply of liquid can be reduced. This is therefore useful for simplifying the sludge supply device.

A cement clinker manufacturing apparatus according to one aspect of the present disclosure includes the sludge supply device and the heating furnace. Because this manufacturing apparatus includes the sludge supply device, it is useful for achieving both reduced transportation problems with the sludge supplied to the heating furnace and improved combustion efficiency.

A method for producing cement clinker according to one aspect of the present disclosure includes the steps of: discharging sludge from a hopper containing sludge downstream using a screw feeder having an internal space connected to the discharge outlet of the hopper; supplying liquid to at least a portion of the internal space connected to the discharge outlet; supplying the sludge discharged from the screw feeder to a heating furnace; and heating the cement raw material in the heating furnace with the sludge supplied. In the step of supplying liquid to at least the connection portion, when the connection portion is divided into two imaginary regions at the center of the sludge discharge direction, the liquid is supplied to the connection portion so that the amount of liquid supplied to one of the upstream regions is greater than the amount of liquid supplied to the other downstream region. In this production method, the amount of liquid supplied to one of the upstream regions is greater than the amount of liquid supplied to the other downstream region. This allows for efficient supply of liquid to the sludge, and by supplying the minimum necessary amount of water, sludge transportation problems due to low moisture content can be reduced. Therefore, this production method is useful for achieving both reduced transportation problems and high combustion efficiency for sludge supplied to a heating furnace.

This disclosure provides a sludge supply device, cement clinker manufacturing device, and cement clinker manufacturing method that are useful for achieving both reduced transportation problems and improved combustion efficiency for sludge supplied to a heating furnace.

FIG. 1 is a schematic diagram showing an example of a cement clinker manufacturing apparatus. FIG. 2 is a schematic diagram showing an example of a sludge supplying device. FIG. 3 is a schematic diagram illustrating the details of a portion of the sludge supply device. Fig. 4(a) is a plan view showing an example of a sludge supplying device, and Fig. 4(b) is a schematic view showing an example of a cross section of a screw feeder. FIG. 5 is a schematic diagram for explaining an example of the relationship between the movement of sludge in the hopper and the supply of liquid by the liquid injection unit. FIG. 6 is a block diagram illustrating an example of a hardware configuration of the control device. 7A and 7B are flowcharts showing an example of a series of processes executed by the control device. 8(a) and 8(b) are schematic diagrams showing an example of a sludge supplying device.

One embodiment will be described below with reference to the drawings. In the description, identical elements or elements with identical functions will be given the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings, and the dimensional ratios of each element are not limited to those shown. Some drawings show a Cartesian coordinate system defined by the X-axis, Y-axis, and Z-axis. In the following embodiment, the Z-axis corresponds to the vertical direction, and the X-axis and Y-axis correspond to the horizontal direction.

[Cement clinker manufacturing equipment]
Fig. 1 shows a schematic diagram of a cement clinker manufacturing apparatus according to one embodiment. The manufacturing apparatus 1 shown in Fig. 1 is an apparatus for producing cement clinker by burning cement raw materials. The manufacturing apparatus 1 includes, for example, a preheater 10, a rotary kiln 30, a clinker cooler 38, and a sludge supply device 40.

The preheater 10 is a new suspension preheater (NSP). The preheater 10 preheats and calcines the cement raw materials using high-temperature gas (hereinafter simply referred to as "high-temperature gas"), including exhaust gas from the rotary kiln 30, before the cement raw materials are fired in the rotary kiln 30. The high-temperature gas has a temperature sufficient to preheat and calcinate the cement raw materials. The preheater 10 has multiple cyclones, a calciner 14, a rising duct 16, and a raw material supply section 18. The multiple cyclones include, for example, cyclones C1, C2, C3, and C4. Unlike the example shown in FIG. 1, the number of cyclones may be five or more or three or less.

Cyclones C1, C2, C3, and C4 are arranged in this order from top to bottom, and each cyclone separates the cement raw materials (preheated raw materials) from the high-temperature gas. The calciner 14 is a furnace body that calcines the cement raw materials using high-temperature gas, including exhaust gas from the rotary kiln 30. The calciner 14 functions as a heating furnace that heats the cement raw materials. The heating temperature in the calciner 14 is, for example, approximately 700°C to 900°C. The calciner 14 is connected to the end 32 of the rotary kiln 30 via a rising duct 16. The rising duct 16 guides the exhaust gas from the rotary kiln 30 to the calciner 14. The exhaust gas from the end 32 of the rotary kiln 30 flows upward through the rising duct 16 and the calciner 14.

The calciner 14 has a burner (not shown) that mixes an energy source (fuel) such as coal with air and supplies combustion gas to the interior of the calciner 14. The high-temperature gas includes exhaust gas from the rotary kiln 30 and combustion gas from the burner of the calciner 14. Inside the calciner 14, the combustion gas from the burner may form a swirling flow that rises while swirling. The high-temperature gas generated in the calciner 14 flows into cyclone C4 and then flows upward, passing through cyclones C3, C2, and C1 in that order.

The raw material supply unit 18 inputs the cement raw material produced in the previous process (raw material process) into the gas duct between cyclones C1 and C2. The supplied cement raw material descends through cyclones C1, C2, and C3 in this order, repeatedly exchanging heat with high-temperature gas in the gas duct between the cyclones and separating it from the high-temperature gas in the cyclones. The cement raw material separated from the high-temperature gas in cyclone C3 is introduced into the calciner 14. The heat exchange with the high-temperature gas in the calciner 14 decarbonates limestone (calcium carbonate: CaCO ₃ ) contained in the cement raw material. The calcined (decarbonated) cement raw material is introduced into cyclone C4 together with the high-temperature gas, separated from the high-temperature gas in cyclone C4, and then supplied to the kiln end 32 of the rotary kiln 30.

The rotary kiln 30 is a device that burns cement raw materials after they have been preheated and calcined in the preheater 10. The rotary kiln 30 functions as a heating furnace that heats the cement raw materials. The heating temperature in the rotary kiln 30 is, for example, approximately 1000°C to 1500°C. The rotary kiln 30 has a main body 34 and a burner 36 provided at the rear end of the main body 34. The rotary kiln 30 produces cement clinker by heating the cement raw materials with combustion gas from the burner 36. The rotary kiln 30 discharges the produced cement clinker to a clinker cooler 38. The clinker cooler 38 cools the cement clinker using cooling air or the like.

The sludge supplying device 40 is a device that supplies sludge to the calciner 14. By supplying sludge into the calciner 14, the sludge is used as an energy source for heating the cement raw material, and some components of the sludge (e.g., Al ₂ O ₃ ) are also used as a cement raw material. The sludge supplying device 40 may supply any type of sludge to the calciner 14. The sludge supplying device 40 may also supply sludge that is a mixture of multiple types of sludge to the calciner 14.

The sludge supplied by the sludge supply device 40 may include undigested sludge, which has a high moisture content, and digested sludge, which has a low moisture content. In one example, the moisture content of the undigested sludge is 83% to 85%, while the moisture content of the digested sludge is 78% to 79%, or less than 78%. The sludge supplied by the sludge supply device 40 may include sludge with a strong odor. Organic sludge (organic sludge) tends to have a strong odor. Specific examples of organic sludge include sewage sludge, fecal sludge, and excess sludge.

Figure 2 shows a schematic diagram of an example of a sludge supplying device 40 that supplies strong-odor sludge to the calciner 14. In the sludge supplying device 40 shown in Figure 2, the sludge is stored in a sealed space to prevent odors from leaking to the outside, and the sludge is transported to the calciner 14 in a sealed state. The sludge supplying device 40 includes, for example, a sealing device 42, a hopper 44, a screw feeder 50, a liquid injection unit 60, a pump pressure delivery unit 82, a transport pipe 84, and a control device 90 (control unit).

The sealed equipment 42 is equipment that forms a sealed space to prevent odor leakage. The sealed equipment 42 houses the hopper 44, the screw feeder 50, part of the liquid injection section 60, the pump pressure delivery section 82, and part of the transport pipe 84. One side wall of the sealed equipment 42 may be provided with an inlet that can be opened and closed by a shutter. Various types of sludge may be supplied to the hopper 44 from this inlet using a truck or the like.

The sludge contained in the hopper 44 may include at least one selected from the group consisting of sewage sludge, fecal sludge, and excess sludge. The moisture content of the sludge contained in the hopper 44 may be 80% or less. In one example, the upper limit of the moisture content of the sludge contained in the hopper 44 is 78%, 76%, or 75%. The moisture content of the sludge in the hopper 44 can be calculated by drying a sample of the sludge in an oven at 40°C for 24 hours and using the following formula (1) based on the weight of the sample before and after drying.
Moisture content (%) = (weight before drying - weight after drying) / weight before drying x 100 (1)

Figure 3 shows a schematic diagram of the hopper 44, screw feeder 50, and liquid injection unit 60 in detail. Figure 4(a) is a plan view taken along line IV-IV in Figure 3, and Figure 4(b) is a diagram showing a portion of a cross section taken along line IVB-IVB in Figure 4(a). The hopper 44 shown in Figure 3 is a tank (container) that stores sludge. In more detail, the hopper 44 temporarily stores sludge before it is supplied to the calciner 14.

The upper half of the hopper 44 is cylindrical with a roughly constant diameter, while the lower half of the hopper 44 has a cylindrical shape with a diameter that decreases downward. The upper end of the hopper 44 is open, and sludge is supplied into the hopper 44 through this opening. A bottom 44a is provided at the lower end of the hopper 44. The bottom 44a is disc-shaped and is provided to cover the opening at the lower end of the hopper 44. The bottom 44a is positioned horizontally. As shown in Figure 4(a), the bottom 44a is formed with a discharge port 44b through which sludge is discharged from the hopper 44.

At the lower end of the hopper 44, the interior and exterior of the hopper 44 are connected via the discharge port 44b. The discharge port 44b is formed to extend in one horizontal direction (the X-axis direction in the figure). The discharge port 44b is located along the bottom 44a and approximately in the center of the hopper 44 in the direction perpendicular to the extension direction of the discharge port 44b (the Y-axis direction in the figure). The distance between one end and the other end of the extension direction of the discharge port 44b approximately matches the diameter of the upper surface of the bottom 44a.

The screw feeder 50 is a device that sends out sludge in the hopper 44 in a predetermined direction. The screw feeder 50 sends out the sludge in the hopper 44 at least from one end of the discharge port 44b to the other end in the extension direction of the discharge port 44b. In the example shown in Figures 3 and 4, the screw feeder 50 sends out the sludge at least in the positive direction of the X axis. Hereinafter, the terms "upstream" and "downstream" are used based on the flow of the transported sludge. In other words, the sludge is transported from upstream to downstream, and the screw feeder 50 sends out the sludge in the hopper 44 downstream. In addition, the terms "front," "rear," and "front-rear direction" are used based on the view from the end located upstream of the discharge port 44b to the end located downstream of the discharge port 44b.

As shown in FIG. 3, the screw feeder 50 has a discharge section 52, a screw 54, a screw drive section 58, and a chute 56. The discharge section 52 is a housing that forms an internal space S in which the screw 54 is housed. The discharge section 52 is formed to extend in the front-to-rear direction (the extension direction of the discharge port 44b). The total length of the discharge section 52 in the front-to-rear direction is longer than the total length of the discharge port 44b in the front-to-rear direction. When viewed from below, the discharge section 52 is positioned to cover the entire area of the discharge port 44b. The discharge section 52 protrudes from the lower end of the hopper 44 on both the front and rear sides.

As shown in FIG. 4(b), the discharge section 52 may include a sidewall whose upper end is connected to the bottom 44a of the hopper 44 and extending in the vertical direction (the Z-axis direction in the figure), and a bottom wall connected to the lower end of the sidewall and having an arc-shaped cross section. The upper end of the discharge section 52 is open where it overlaps with the discharge outlet 44b. The open portion of the upper end of the discharge section 52 may be formed so that its outer edge surrounds the discharge outlet 44b. The internal space S formed by the discharge section 52 is connected to the discharge outlet 44b, and the internal space S is connected to the interior of the hopper 44 via the discharge outlet 44b. Sludge in the hopper 44 can be introduced into the internal space S of the discharge section 52 via the discharge outlet 44b.

The screw 54 is disposed in the internal space S of the discharge section 52 (see Figure 3). Note that the screw 54 is not shown in Figures 4(a) and 4(b). The screw 54 is rotatable about a rotation axis along the front-to-rear direction, and is configured to send sludge in the internal space S downstream by rotation about the rotation axis. The screw driver 58 includes a motor (power source) that rotates the screw 54 about the rotation axis. The screw driver 58 rotates the screw 54 at a rotation speed based on operation instructions from the control device 90. The screw driver 58 may also include a sensor that can measure the current rotation speed of the screw 54 (or the motor).

The chute 56 is a section that sends the sludge delivered by the screw 54 downward. The chute 56 is connected to the lower end of the front end of the screw 54 and is formed to extend downward from that lower end. The inside of the chute 56 is connected to the internal space S, and its lower end is open. The sludge delivered forward by the screw 54 is discharged from the lower end of the chute 56. As described above, the screw feeder 50 sends the sludge in the hopper 44 downstream by rotating the screw 54 in the internal space S connected to the discharge port 44b.

The rotation speed of the screw 54 is controlled by the control device 90. In one example, the screw drive unit 58 is controlled so that the rotation speed (rotational speed) of the screw 54 follows a target rotation speed. The screw drive unit 58 may be controlled by adjusting the power (e.g., drive current) supplied to a motor included in the screw drive unit 58 to adjust the motor rotation speed. As the moisture content of the sludge decreases, the sludge hardens, and in order to rotate the screw 54 at the same rotation speed, it is necessary to increase the power supplied to the motor. Because there is an upper limit to the amount of current that can be passed through the motor, the sludge supply device 40 sends out sludge using the screw 54 while increasing the moisture content of the sludge.

The liquid injection unit 60 supplies liquid to the internal space S to increase the moisture content of the sludge. Specifically, the liquid injection unit 60 supplies liquid at least to the connection portion CP of the internal space S with the discharge outlet 44b. The connection portion CP is the entire space between the rearmost (upstream) end of the internal space S of the discharge outlet 44b and the frontmost (downstream) end of the discharge outlet 44b. Figure 3 shows boundary B1, which is an imaginary plane perpendicular to the front-to-rear direction and includes the rearmost end of the discharge outlet 44b, and boundary B2, which is an imaginary plane perpendicular to the front-to-rear direction and includes the frontmost end of the discharge outlet 44b. The connection portion CP is an area defined by boundaries B1 and B2, the side walls and bottom wall of the discharge unit 52, and an imaginary plane including the underside of the bottom 44a of the hopper 44.

In the internal space S, the liquid injection unit 60 may supply liquid to the region forward of the connection part CP (boundary B1) in addition to the connection part CP. The liquid injection unit 60 may supply any type of liquid to the connection part CP, or may supply two or more types of liquid to the connection part CP. The liquid injection unit 60 may, for example, supply industrial water and industrial wastewater to the connection part CP. Industrial wastewater is wastewater that contains chemicals (e.g., harmful pollutants) and requires waste treatment. Industrial wastewater is, for example, wastewater that has been used in various processes in a factory where machining or other processes are performed.

The liquid injection unit 60 includes a wastewater supply unit 61 and an industrial water supply unit 71. The wastewater supply unit 61 supplies industrial wastewater to the connection part CP. The wastewater supply unit 61 has a liquid source 62, a wastewater supply pipe 64, and a liquid injection valve 68. The liquid source 62 is a source of industrial wastewater. The liquid source 62 may be located outside the above-mentioned sealing equipment 42 and may include a tank that stores industrial wastewater and a pump that pressure-pumps the industrial wastewater in the tank. The wastewater supply pipe 64 is a single pipe that connects the liquid source 62 and the delivery unit 52.

The end of the wastewater supply pipe 64 that connects to the connection portion CP may be connected to a water inlet provided on one side wall of the discharge section 52. The water inlet is a hole that connects the internal space S to the space outside the discharge section 52. Industrial wastewater pumped from the liquid source 62 flows through a flow path within the wastewater supply pipe 64 and is supplied to the internal space S of the discharge section 52. A liquid inlet valve 68 is provided in the wastewater supply pipe 64 and switches the open/close state of the flow path within the wastewater supply pipe 64. The liquid inlet valve 68 may be a valve with an adjustable aperture. By adjusting the aperture of the liquid inlet valve 68, the amount of industrial wastewater supplied to the internal space S (amount supplied per unit time) changes.

The industrial water supply unit 71 supplies industrial water to the connection part CP. The industrial water supply unit 71 has a liquid source 72, a common supply pipe 74, multiple individual supply pipes, and a liquid injection valve 78. The liquid source 72 is a source of industrial water. The liquid source 72 may be located outside the sealed equipment 42 and may include a tank that stores industrial water and a pump that pressure-pumps the industrial water in the tank. The common supply pipe 74 is a single pipe that connects the liquid source 72 to each of the multiple individual supply pipes.

In the example shown in FIG. 3, the industrial water supply unit 71 has multiple individual supply pipes, individual supply pipes 76a to 76h (eight individual supply pipes). The individual supply pipes 76a to 76h branch off from the common supply pipe 74. One end of the individual supply pipe 76a is connected midway through the common supply pipe 74, and the other end of the individual supply pipe 76a is connected to the delivery unit 52. The other end of the individual supply pipe 76a may be connected to a water inlet provided on one side wall of the delivery unit 52. Like the individual supply pipe 76a, each of the individual supply pipes 76b to 76h also connects the common supply pipe 74 to the delivery unit 52.

Industrial water pumped from the liquid source 72 flows through the flow path within the common supply pipe 74, branches off into the respective flow paths within the individual supply pipes 76a-76h, and is then supplied to the internal space S of the delivery unit 52. A liquid injection valve 78 is provided on the common supply pipe 74 and switches the common supply pipe 74 between open and closed states. The liquid injection valve 78 may be a valve with an adjustable opening. Adjusting the opening of the liquid injection valve 78 changes the amount of industrial water supplied to the internal space S (amount supplied per unit time). Although not shown, the wastewater supply unit 61 may have a flow meter that measures the flow rate through the wastewater supply pipe 64, and the industrial water supply unit 71 may have a flow meter that measures the flow rate through the common supply pipe 74.

Now, with reference to Figure 5, we will explain the movement of sludge within the hopper 44 when it is discharged by the screw feeder 50, the arrangement of the wastewater supply pipe 64 and individual supply pipes 76a-76h, and the distribution of the amount of liquid supplied from the liquid injection unit 60. As shown in Figure 5, a greater amount of sludge is introduced into the internal space S of the discharge unit 52 from the rear portion of the hopper 44 (the portion closer to boundary B1) than from the front portion of the hopper 44 (the portion closer to boundary B2). This phenomenon occurs because sludge is discharged from boundary B1 toward boundary B2 in the internal space S by the screw 54, and the portion in front of the connection portion CP in the internal space S is clogged with sludge, forming a void in the portion behind the connection portion CP.

Considering the above-described flow of sludge from the hopper 44 to the internal space S, more new sludge is introduced from the hopper 44 into the internal space S at the rear part of the connection part CP. The liquid injection unit 60 supplies liquid to the connection part CP to correspond to the difference in the amount of sludge introduced from the hopper 44 at the connection part CP. Specifically, when the connection part CP is divided into two virtual regions at the center in the direction in which the sludge is discharged, the liquid injection unit 60 supplies liquid to the connection part CP so that the amount supplied to one region located upstream is greater than the amount supplied to the other region located downstream.

In Figure 5, the boundary located at the center of the connection portion CP in the direction in which the sludge is discharged is indicated by "BC," one upstream region is indicated by "R1," and the other downstream region is indicated by "R2." Boundary BC is parallel to boundaries B1 and B2, and the distance in the front-to-back direction between boundary B1 and boundary BC is equal to the distance in the front-to-back direction between boundary B2 and boundary BC. The liquid injection unit 60 supplies liquid to the connection portion CP so that the amount of liquid supplied to the first region R1 (amount supplied per unit time) is greater than the amount of liquid supplied to the second region R2 (amount supplied per unit time).

The wastewater supply pipe 64 of the wastewater supply unit 61 and the individual supply pipes 76a-76h of the industrial water supply unit 71 are arranged side by side in the direction in which the sludge is discharged (front-to-back direction). In this disclosure, "arrangement of multiple supply pipes side by side in the front-to-back direction" means that at least the ends of these supply pipes that connect to the discharge unit 52 are lined up in the front-to-back direction. In this case, the multiple water inlets provided on the side walls of the discharge unit 52 to respectively correspond to the multiple supply pipes are also lined up in the front-to-back direction.

In the example shown in FIG. 5, the wastewater supply pipe 64 and individual supply pipes 76a-76h are arranged in this order from upstream to downstream. The wastewater supply pipe 64 and individual supply pipes 76a-76c are connected to the first region R1, the individual supply pipes 76d-76g are connected to the second region R2, and the individual supply pipe 76h is connected to a region downstream of the second region R2 (connection portion CP). The multiple water inlets corresponding to the multiple supply pipes may be arranged at approximately equal intervals along the front-to-rear direction.

Of the multiple supply pipes, the supply pipe with the largest liquid supply volume may be located at the most upstream position. The wastewater supply pipe 64 is located at the most upstream position in the front-to-rear direction. The amount of industrial wastewater supplied from the wastewater supply pipe 64 (amount supplied per unit time) may be greater than the amount of industrial water supplied from each of the individual supply pipes 76a to 76h (amount supplied per unit time). In other words, the amount of liquid supplied from the wastewater supply pipe 64 may be greater than the amount of liquid supplied from any one individual supply pipe. In one example, the diameter of the wastewater supply pipe 64 is greater than the diameter of each of the individual supply pipes 76a to 76h.

The industrial water supply amount (amount supplied per unit time) from each of the individual supply pipes 76a-76h may be the same or different. The diameters of the individual supply pipes 76a-76h may be the same or different. The liquid supply amount from the wastewater supply pipe 64 may be approximately 1.1 to 3.0 times the liquid supply amount from a single individual supply pipe. When liquid is supplied by the liquid injection unit 60 configured as described above, the amount of liquid supplied to the first region R1 is greater than the amount of liquid supplied to the second region R2.

Returning to Figure 2, the pump pressure delivery unit 82 receives sludge delivered from the screw feeder 50 and pumps the sludge toward the calciner 14. A transport pipe 84 is provided between the pump pressure delivery unit 82 and the calciner 14. The transport pipe 84 connects the pump pressure delivery unit 82 and the calciner 14, and is sealed to prevent the odor of the sludge from leaking to the outside. The sludge pumped from the pump pressure delivery unit 82 is guided through the transport pipe 84 into the interior of the calciner 14.

In the sludge supply device 40, sludge pumped by the pump pressure delivery unit 82 is supplied to the interior of the calciner 14 without being dehydrated. In this case, the sludge after liquid is supplied from the liquid injection unit 60 in the screw feeder 50 is introduced into the interior of the calciner 14 while maintaining a substantially constant moisture content. The sludge supply device 40 may supply sludge to the interior of the rotary kiln 30 in the same way as it supplies sludge to the calciner 14 (using a similar device configuration).

The control device 90 is a computer that controls each element included in the sludge supply device 40. As shown in FIG. 6, the control device 90 has a circuit 91. The circuit 91 includes at least one processor 92, memory 94, storage 96, an input/output port 98, and a timer 99. The storage 96 records programs for controlling each element included in the sludge supply device 40. The storage 96 is a computer-readable recording medium such as a hard disk, non-volatile semiconductor memory, magnetic disk, or optical disk.

The memory 94 temporarily stores programs loaded from the storage 96, calculation results of the processor 92, etc. The processor 92 executes programs in cooperation with the memory 94, thereby controlling each element included in the sludge supply device 40. The input/output port 98 inputs and outputs electrical signals between the screw drive unit 58, wastewater supply unit 61, industrial water supply unit 71, etc. in response to commands from the processor 92. The timer 99 counts clock pulses at a predetermined cycle in response to commands from the processor 92 to measure elapsed time. The control device 90 may be part of a computer for controlling the manufacturing apparatus 1.

[Method of manufacturing cement clinker]
Cement clinker can be produced using the above-described production apparatus 1. The method for producing cement clinker includes, for example, a supplying step, a preheating and calcining step, a firing step, and a cooling step.

In the supply process, sludge is supplied into the calciner 14 by the sludge supply device 40. The supply process includes, for example, a storage process, a discharge process, a liquid injection process, and a pressure transfer process. In the storage process, sludge with a moisture content of 80% or less is stored in the hopper 44. In the discharge process, the sludge in the hopper 44 is discharged downstream by the screw feeder 50. In the discharge process, the screw drive unit 58 may be controlled by the control device 90 so that the rotation speed of the screw 54 driven by the screw drive unit 58 tracks the target rotation speed.

In the liquid injection process, the liquid injection unit 60 supplies liquid to the connection portion CP of the internal space S housing the screw 54, where the connection portion CP is connected to the discharge port 44b of the hopper 44. In this liquid injection process, liquid is supplied to the connection portion CP so that the amount of liquid supplied to the first region R1, which is located upstream of the center (boundary BC) in the front-to-back direction of the connection portion CP, is greater than the amount of liquid supplied to the second region R2, which is located downstream of the center. In the liquid injection process, the control device 90 may control the liquid injection unit 60 so that the value of the current output to the screw drive unit 58 falls within a predetermined set range.

In the pressure-feeding process, the sludge delivered from the screw feeder 50 is pressure-fed by the pump pressure-fed unit 82 through the transport pipe 84 toward the interior of the calciner 14. In the pressure-fed process, the sludge pumped from the pump pressure-fed unit 82 may be supplied to the interior of the calciner 14 without being dehydrated.

In the preheating and calcining process, the preheater 10 preheats and calcines the cement raw materials. In the preheating and calcining process, the cement raw materials are calcined (heated) in the calciner 14, into which sludge is supplied. In the firing process, the cement raw materials are calcined in the rotary kiln 30, resulting in cement clinker. In the firing process, the preheated and calcined cement raw materials are calcined (heated) in the rotary kiln 30. In the cooling process, the cement clinker produced in the rotary kiln 30 is cooled in the clinker cooler 38. The cement clinker produced by the above manufacturing method is then subjected to a finishing process, including crushing, to produce cement.

(Control Method)
Next, an example of a control method by the control device 90 will be described. The control device 90 adjusts the amount of liquid supplied from the liquid injecting unit 60 so that at least the value of the current output to the screw driving unit 58 falls within a predetermined set range. Figures 7(a) and 7(b) are flowcharts showing a series of processes executed by the control device 90 at predetermined intervals in the above-mentioned delivery step and liquid injecting step. In this series of processes, control of the rotation speed of the screw 54 and control of the amount of liquid supplied into the internal space S of the screw feeder 50 (water injection control) are executed in parallel.

To control the rotation speed of the screw 54, the control device 90 executes steps S11 and S12. In step S11, for example, the control device 90 acquires information indicating the current rotation speed of the screw 54 from the screw drive unit 58. In step S12, for example, the control device 90 determines whether the deviation between the current rotation speed acquired in step S11 and the target rotation speed is greater than a predetermined value. The target rotation speed is set by an operator, for example, based on the amount of sludge to be discharged from the screw feeder 50 per unit time. The predetermined value to be compared with the deviation is determined in advance by an operator, for example, based on the allowable fluctuation range of the amount of sludge discharged from the screw feeder 50.

If it is determined in step S12 that the deviation in the rotation speed is greater than a predetermined value (step S12: YES), the processing executed by the control device 90 proceeds to step S13. In step S13, for example, the control device 90 adjusts the current value supplied to the screw drive unit 58 so as to reduce the deviation in the rotation speed. If it is determined in step S12 that the deviation in the rotation speed is equal to or less than a predetermined value (step S12: NO), the control device 90 does not execute step S13 and ends the processing for that cycle. This completes the rotation speed control executed in one cycle.

In water injection control, the control device 90 executes steps S21 and S22. In step S21, for example, the control device 90 acquires information indicating the current value of the current being supplied to the motor included in the screw drive unit 58. In step S22, for example, the control device 90 determines whether the value of the current being output to the motor included in the screw drive unit 58 (the current value acquired in step S21) is outside a predetermined setting range. The setting range (its upper limit) is predetermined by an operator, for example, based on the rated current set for the motor. In one example, the upper limit of the setting range is set to approximately 60% to 90% of the rated current of the motor.

If, in step S22, the current current value to the motor is outside the set range (step S22: YES), the processing executed by the control device 90 proceeds to step S23. In step S23, for example, the control device 90 adjusts the aperture of at least one of the liquid injection valves 68 and 78 so that the current value to the motor is within the set range. In one example, if the current value obtained in step S22 exceeds the upper limit of the set range, the control device 90 increases the aperture of at least one of the liquid injection valves 68 and 78. Increasing the aperture of the valve increases the amount of liquid supplied from the liquid injection section 60 to the connection part CP, and the moisture content of the sludge in the internal space S increases.

If the current value obtained in step S22 is below the lower limit of the set range, the control device 90 reduces the opening of at least one of the liquid injection valves 68 and 78. Reducing the valve opening reduces the amount of liquid supplied from the liquid injection unit 60 to the connection part CP, lowering the water content of the sludge in the internal space S. On the other hand, if the current current value to the motor is within the set range in step S22 (step S22: NO), the control device 90 does not execute step S23 and ends the water injection control for that cycle. Thereafter, the control device 90 repeatedly executes the rotation speed control and water injection control at predetermined cycles.

Since the rotation speed control and water injection control are performed separately, the execution timing of each cycle may differ. While this series of processes is repeated, if the moisture content of the sludge discharged by the screw 54 decreases due to fluctuations in the moisture content of the sludge in the hopper 44, the load (current value) on the motor of the screw drive unit 58 increases. If the moisture content of the sludge discharged by the screw 54 increases due to fluctuations in the moisture content of the sludge in the hopper 44, the motor load decreases. If the motor load exceeds the specified set range due to an excessive decrease in the moisture content of the sludge, the amount of liquid supplied from the liquid injection unit 60 increases. This prevents the motor from becoming overloaded.

(Modification)
The above-described series of processes is an example and can be modified as appropriate. In the above-described series of processes, the control device 90 may execute one step and the next step in parallel, or may execute each step in an order different from that of the above-described example. The control device 90 may omit any step, or may execute a process in any step different from that of the above-described example.

The method of supplying liquid to the connection portion CP is not limited to the above example. Liquid may be supplied only to the first region R1 upstream of the connection portion CP. Figure 8(a) schematically shows a modified sludge supplying device 40A. The sludge supplying device 40A has a liquid supplying section 60A instead of the liquid supplying section 60. The liquid supplying section 60A does not have an industrial water supplying section 71, but has a wastewater supplying section 61. The liquid supplying section 60A supplies industrial wastewater to the first region R1 via the wastewater supply pipe 64 without supplying any liquid to the second region R2. Thus, in the present disclosure, supplying liquid to the connection portion CP so that the amount of liquid supplied to the first region R1 is greater than the amount of liquid supplied to the second region R2 includes supplying liquid to the first region R1 while keeping the amount of liquid supplied to the second region R2 zero.

Figure 8(b) schematically shows a modified sludge supplying device 40B. The sludge supplying device 40B has a liquid supplying section 60B instead of the liquid supplying section 60. In the liquid supplying section 60B, the individual supply pipe 76a of the industrial water supplying section 71, the wastewater supply pipe 64 of the wastewater supplying section 61, and the individual supply pipes 76b-76h of the industrial water supplying section 71 are arranged in this order from upstream to downstream. In this way, the supply volume from the supply pipe located most upstream does not need to be the largest. Even in this case, liquid is supplied from the wastewater supply pipe 64 to the first region R1, so the relationship in which the liquid supply volume to the first region R1 is greater than the liquid supply volume to the second region R2 is satisfied.

The liquid injection unit 60 may have multiple supply pipes that supply the same amount of liquid. In this case, the multiple supply pipes may be arranged so that the number of supply pipes that supply liquid to the first region R1 is greater than the number of supply pipes that supply liquid to the second region R2. The liquid injection unit 60 may have an industrial water supply unit 71 without a wastewater supply unit 61. In this case, the industrial water supply unit 71 may supply industrial water to the connection portion CP so that the amount of liquid supplied to the first region R1 is greater than the amount of liquid supplied to the second region R2. In any of the examples of the liquid injection unit, two or more supply pipes may be arranged in positions where they at least partially overlap each other in the front-to-rear direction.

Unlike the control of the screw drive unit 58 in the above example, the control device 90 may control the screw drive unit 58 so that the supply amount sent out from the chute 56 of the screw feeder 50 is a target supply amount. Control to adjust the amount of liquid supplied from the liquid injection unit 60 according to the load on the motor does not need to be performed. In this case, the liquid injection unit 60 may supply a substantially constant amount of liquid to the internal space S while the screw feeder 50 is operating, regardless of the load on the motor.

[Effects of the embodiment]
When the moisture content of the sludge delivered by the screw feeder 50 becomes low, the load on the motor of the screw drive unit 58 that drives the screw 54 increases. If the moisture content of the sludge becomes extremely low, the motor may become overloaded, resulting in a transportation problem in which the sludge cannot be delivered. On the other hand, if a large amount of liquid is supplied to avoid overloading the motor of the screw drive unit 58, sludge containing a large amount of moisture may be supplied to the calciner 14, which may reduce the combustion efficiency of the calciner 14. In the sludge supply device 40 described above, when sludge is introduced into the internal space S from the discharge port 44b of the hopper 44, more sludge is introduced into the internal space S in the upstream portion of the hopper 44 than in the downstream portion of the hopper 44 in the direction in which the sludge is delivered. Accordingly, the liquid injection unit 60 supplies liquid to the connection portion CP so that the amount of liquid supplied to the first region R1 located upstream is greater than the amount of liquid supplied to the second region R2 located downstream. Therefore, liquid can be efficiently supplied to the sludge, and supplying the minimum necessary amount of water can prevent the motor of the screw drive unit 58 from becoming overloaded. Therefore, the sludge supply device 40 described above is useful for achieving both suppression of transportation problems of the sludge supplied to the calciner 14 and improvement of combustion efficiency in the calciner 14.

The liquid injection section 60 may include multiple supply pipes (wastewater supply pipe 64, individual supply pipes 76a-76g) arranged in a line along the sludge discharge direction, each supplying liquid to at least the connection portion CP. The wastewater supply pipe 64, which supplies the largest amount of liquid among the multiple supply pipes, may be located at the most upstream position. In the internal space S connected to the discharge outlet 44b of the hopper 44, voids may form in the more upstream portion of the sludge discharge direction due to the sludge being discharged. Therefore, a large amount of new sludge is introduced from the hopper 44 to the upstream portion. In the above configuration, the most liquid is supplied from the wastewater supply pipe 64 located at the most upstream position, thereby enabling a more efficient liquid supply to the sludge. For example, it is conceivable to arrange the supply pipe with the largest supply amount at the most downstream position of the connection portion CP. However, compared to this arrangement, the above configuration provides more opportunities for sludge introduced upstream of the connection portion CP to become mixed with water before reaching the chute 56. This is useful for preventing an increase in the amount of liquid supplied while also preventing transport problems caused by the motor becoming overloaded.

The sludge contained in the hopper 44 may include at least one selected from the group consisting of sewage sludge, human waste sludge, and excess sludge. In this case, the flow path within the pipe through which the sludge is transported must be sealed to prevent the sludge's odor from leaking to the outside. If the sludge has a low moisture content, problems may occur in which the sludge cannot be transported within the pipe, but the liquid injection unit 60 supplies liquid to the sludge. Therefore, this is useful for preventing transportation problems when transporting sludge containing any one of sewage sludge, human waste sludge, and excess sludge in a sealed state.

The moisture content of the sludge contained in the hopper 44 may be 80% or less. If the moisture content of the sludge is 80% or less, there is a high possibility that the motor rotating the screw 54 will become overloaded unless liquid is supplied from the liquid injection section 60. In the sludge supply device 40, more liquid is supplied from the upstream first region R1. This reduces the possibility of the motor becoming overloaded while suppressing an increase in the amount of liquid supplied. This is therefore useful for preventing transportation problems when transporting sludge with a low moisture content.

The liquid supplied by the liquid injection unit 60 may include industrial wastewater. In this case, the industrial wastewater is introduced into the calciner 14 along with the sludge. Therefore, the industrial wastewater can be treated while being used to reduce sludge transportation problems.

The sludge supply device 40 further includes a screw driver 58 that rotates the screw 54, and a control device 90 that controls the screw driver 58 and the liquid injection device 60. The control device 90 may adjust the amount of liquid supplied from the liquid injection device 60 so that the value of the current output to the screw driver 58 falls within a predetermined set range. In this case, even if the value of the current output to the motor of the screw driver 58 increases, the amount of liquid supplied is adjusted to increase, thereby reducing the load on the motor of the screw driver 58. This is therefore useful for reducing the frequency of problems such as the motor becoming overloaded and sludge transport stopping.

The sludge supply device 40 may include a pump pressure delivery unit 82 that pumps the sludge delivered from the screw feeder 50 toward the calciner 14 through a transport pipe 84 connected to the calciner 14. The sludge pumped by the pump pressure delivery unit 82 may be supplied to the calciner 14 without being dehydrated. The sludge supply device 40 prevents an increase in the amount of liquid supplied to the sludge, and therefore reduces the extent of the decrease in combustion efficiency in the calciner 14 caused by the supply of liquid to the sludge, even without dehydration. This is therefore useful for simplifying the sludge supply device 40.

1...cement clinker manufacturing apparatus, 14...calciner, 30...rotary kiln, 40...sludge supply device, 44...hopper, 44b...discharge outlet, 50...screw feeder, 54...screw, 58...screw drive unit, S...internal space, CP...connection part, R1...first region, R2...second region, 60...liquid injection unit, 64...wastewater supply pipe, 76a-76h...individual supply pipes, 82...pump pressure unit, 84...transport pipe, 90...control device.

Claims (9)

A sludge supplying device that supplies sludge to a heating furnace that heats cement raw materials,
a hopper for storing sludge;
a screw feeder having an internal space connected to a discharge port located at the bottom of the hopper, and rotating a screw in the internal space to send downstream the sludge introduced from inside the hopper through the discharge port into the internal space;
a liquid injection unit that supplies liquid to at least a portion of the internal space connected to the discharge port in the screw feeder ,
A sludge supply device in which the liquid injection section supplies liquid to the connection section so that, when the connection section is divided into two virtual regions in the center of the sludge discharge direction, the amount of liquid supplied to one region located upstream is greater than the amount of liquid supplied to the other region located downstream. the liquid injection unit includes a plurality of supply pipes arranged side by side along the sludge delivery direction, each supplying liquid to at least the connection portion;
The sludge supplying device according to claim 1 , wherein the supply pipe that supplies the largest amount of liquid among the plurality of supply pipes is arranged at the most upstream position. The sludge supply device according to claim 1 or 2, wherein the sludge contained in the hopper includes at least one selected from the group consisting of sewage sludge, fecal sludge, and excess sludge. A sludge supplying device according to any one of claims 1 to 3, wherein the moisture content of the sludge contained in the hopper is 80% or less. The sludge supply device according to any one of claims 1 to 4, wherein the liquid supplied by the liquid injection unit includes industrial wastewater. a drive unit that rotates the screw;
a control unit that controls the drive unit and the liquid injection unit,
The sludge supply device according to any one of claims 1 to 5, wherein the control unit adjusts the amount of liquid supplied from the liquid injection unit so that the value of the current output to the drive unit falls within a predetermined setting range. The sludge treatment device further includes a pumping unit that pumps the sludge delivered from the screw feeder toward the heating furnace through a transport pipe connected to the heating furnace,
7. The sludge supplying device according to claim 1, wherein the sludge pumped by the pumping section is supplied to the inside of the heating furnace without being dehydrated. The sludge supply device according to any one of claims 1 to 7,
and a heating furnace. a step in which a screw feeder including an internal space connected to a discharge port located at the bottom of a hopper that stores sludge rotates a screw in the internal space , thereby sending downstream the sludge introduced from the hopper through the discharge port into the internal space ;
a step of supplying liquid by a liquid injection unit to at least a portion of the internal space connected to the discharge port in the screw feeder ;
supplying the sludge delivered from the screw feeder to a heating furnace;
and heating the cement raw material in the heating furnace to which the sludge has been supplied,
A method for manufacturing cement clinker, wherein, in at least the step of supplying liquid to the connection portion, when the connection portion is divided into two virtual regions in the center in the direction in which the sludge is discharged, the liquid is supplied to the connection portion by the liquid injection section so that the amount of liquid supplied to one region located upstream is greater than the amount of liquid supplied to the other region located downstream.