Process system for reducing water content of solid waste by countercurrent evaporation of low-temperature exhaust gas of cement kiln

Abstract

The invention provides a process system for reducing the water content of solid waste by countercurrent evaporation of low-temperature exhaust gas of a cement kiln, comprising: a storage bin for storing solid waste; the evaporation bin comprises a waste gas induced air pipeline connected to a cement kiln waste gas chimney and a vertically arranged evaporation bin body; solid waste enters an upper inlet of the evaporation bin body through a discharging port of the elevator; and the feeding end of the first screw conveyor communicates with the storage bin, the discharging end of the first screw conveyor communicates with a feeding port of the elevator, and the first screw conveyor is used for conveying the solid waste stored in the storage bin to the elevator. Solid waste freely falls under the action of gravity at the feed port of the evaporation bin, and fully contacts and exchanges heat with low-temperature waste gas introduced from the chimney of the cement kiln in the evaporation bin in a countercurrent manner, so that the water content of the solid waste is reduced. No extra heat source needs to be provided, fossil fuel consumption can be reduced, CO2 emission is reduced, and remarkable economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of cement kiln solid waste treatment, and in particular to a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln. Background Art

[0002] The co-treatment of solid waste in cement kilns is to use the high temperature (>1300℃) generated during the calcination of clinker in cement kilns to fully and stably burn solid waste, and at the same time completely incinerate toxic and harmful organic matter such as dioxins in the waste. The co-treatment of solid waste in cement kilns can bring higher economic benefits to cement companies, and can absorb various wastes. Among them, solid waste with calorific value can also be used as an alternative fuel. The waste residue after incineration can be used as a raw material to participate in the reaction in the cement kiln, decomposing or solidifying harmful substances including heavy metals in the cement crystal structure. There is no waste residue discharge, which realizes the reduction, harmlessness and resource utilization of solid waste.

[0003] Some solid wastes, such as biomass (wood, straw, sawdust, bagasse, rice bran, furfural residue), domestic garbage and sludge, have a high moisture content. For example, the moisture content of furfural residue used by cement companies can be as high as 50% or more. After entering the cement kiln, the water evaporates and becomes high-temperature water vapor, which takes away a lot of heat, reducing its value as an alternative fuel. What's more, the heat taken away exceeds its own calorific value, which directly leads to an increase in the heat consumption of the cement kiln system. Therefore, it is necessary to reduce the moisture content of solid waste entering the kiln for collaborative disposal. The utility model patent "Solid Waste Drying and Treatment Device" in the prior art provides a solid waste drying and treatment device, which has a complex structure and uses a hot air generating device to provide heat to dry the solid waste, requiring additional use of fossil fuels, which not only increases the production cost of the enterprise, but also generates additional CO2 emissions. Summary of the invention

[0004] The present invention provides a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln, so as to solve the problem of increased system heat consumption caused by the high moisture content of solid waste co-disposed of by cement kilns, thereby leading to increased costs and CO2 emissions.

[0005] The present invention provides a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln, comprising: A storage bin, wherein the storage bin is used to store solid waste; An evaporation chamber, the evaporation chamber comprising an exhaust gas duct connected to the cement kiln exhaust gas chimney and a vertically arranged evaporation chamber body; An elevator, including an elevator feed port and an elevator discharge port, through which solid waste enters the upper inlet of the evaporation bin body; A first screw conveyor, wherein a feed end of the first screw conveyor is connected to the storage bin, and a discharge end of the first screw conveyor is connected to a feed port of the elevator, and the first screw conveyor is used to convey the solid waste stored in the storage bin to the elevator.

[0006] According to a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature exhaust gas from a cement kiln provided by the present invention, a second screw conveyor is provided at the bottom of the evaporation bin body, and the second screw conveyor is used to transport the solid waste with reduced moisture content falling from the upper inlet of the evaporation bin body.

[0007] According to the present invention, a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature exhaust gas from a cement kiln is provided, which also includes an induced draft fan, which is arranged in the exhaust gas induced draft duct and is used to drive the low-temperature exhaust gas in the cement kiln exhaust gas chimney to flow into the exhaust gas induced draft duct.

[0008] According to a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln provided by the present invention, the evaporation bin body includes multiple sections of pipes, and the multiple sections of the pipes are used to form different heights.

[0009] According to a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature exhaust gas from a cement kiln provided by the present invention, the angle between the conveying section of the discharge port of the elevator and the horizontal plane is greater than or equal to 60°.

[0010] According to the present invention, a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature exhaust gas from a cement kiln also includes a third conveyor, which is arranged between the discharge port of the elevator and the feed port of the evaporation bin, and is used to discharge the solid waste transported by the elevator into the evaporation bin.

[0011] According to a process system provided by the present invention for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature exhaust gas from a cement kiln, the conveying range of the first screw conveyor covers the storage bin and the elevator, and the first screw conveyor is used to transport the solid waste in the storage bin to the elevator.

[0012] According to a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature exhaust gas from a cement kiln provided by the present invention, the second screw conveyor and the first screw conveyor are arranged obliquely.

[0013] The present invention provides a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns, and uses low-temperature waste gas at about 100°C discharged from the waste gas chimney of cement kilns to bake solid waste. The solid waste is lifted to the feed port of the evaporation bin by a conveying device, and the solid waste falls freely under the action of gravity. The low-temperature waste gas introduced from the chimney of the cement kiln fully contacts and exchanges heat with the solid waste from bottom to top in the evaporation bin under the action of atmospheric pressure, and the water in the solid waste is evaporated, thereby achieving the effect of reducing the moisture content of the solid waste. No additional heat source is required, and fossil fuel consumption can be reduced, and CO2 emissions can be reduced, which has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a schematic diagram of a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln provided by the present invention.

[0016] Reference numerals: 1. Evaporation chamber; 11. Exhaust air duct; 12. Evaporation chamber body; 2. Cement kiln exhaust chimney; 3. Storage warehouse; 4. Elevator; 41. Elevator feed port; 42. Elevator housing; 43. Elevator discharge port; 5. Second screw conveyor; 6. Induced draft fan; 7. The first screw conveyor. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Combine the following Figure 1The present invention describes a process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln, comprising an evaporation bin 1, a storage bin 3 and an elevator 4. The evaporation bin 1 comprises an evaporation bin body 12 and an exhaust gas induced draft duct 11. The bottom of the evaporation bin body 12 is connected to a second screw conveyor 5. The solid waste with reduced moisture content is discharged through the second screw conveyor 5. The exhaust gas induced draft duct 11 is connected to a cement kiln exhaust gas chimney 2 of a cement kiln system. The storage bin 3 is used to store solid waste. The feeding end of the first screw conveyor 7 is connected to the storage bin 3, and the discharging end is connected to the elevator feeding port 41, which is used to transport the solid waste stored in the storage bin 3 to the elevator 4.

[0019] The elevator 4 includes an elevator feed port 41, an elevator housing 42 and an elevator discharge port 43. The elevator feed port 41 is connected to the discharge end of the first screw conveyor 7. The elevator discharge port 43 is located at the upper inlet of the evaporation bin body 12. The elevator 4 is used to transport solid waste to the upper inlet of the evaporation bin 1.

[0020] like Figure 1 As shown, in this embodiment, the exhaust air duct 11 is arranged horizontally, and the exhaust air duct 11 is connected to the lower part of the evaporation bin body 12. In different embodiments, the exhaust air duct 11 can also be arranged obliquely, which is not limited here. One end of the exhaust air duct 11 is connected to the evaporation bin body 12, and the other end is connected to the cement kiln exhaust chimney 2. The low-temperature exhaust gas in the cement kiln exhaust chimney 2 enters the evaporation bin body 12 through the induced draft fan 6, and under the action of atmospheric pressure, it flows from bottom to top in the evaporation bin body 12, and fully contacts and exchanges heat with the solid waste falling from top to bottom under the action of gravity, so as to evaporate the moisture in the solid waste.

[0021] This application is aimed at the problem of using low-temperature waste gas from cement kilns to reduce the moisture content of co-disposed solid wastes. Therefore, the cement kiln waste gas chimney 2 is a chimney used by the cement kiln to discharge waste gas (including the kiln head waste gas chimney and the kiln tail waste gas chimney). Therefore, the low-temperature waste gas in the cement kiln waste gas chimney 2 is the waste gas that needs to be discharged normally and does not require additional heat. Although the waste gas discharged from the cement kiln waste gas chimney 2 mentioned in this application is low-temperature waste gas, the low temperature here is only compared to the temperature at other locations in the cement kiln production process (such as the preheater C1 outlet and the grate cooler waste gas outlet). The temperature of the waste gas is relatively low. In fact, the temperature of the low-temperature waste gas discharged from the cement kiln waste gas chimney 2 is about 100°C, which can provide the heat required to evaporate the moisture in the solid waste.

[0022] In this embodiment, the exhaust air duct 11 is connected to the lower part of the evaporation bin body 12, so that the low-temperature exhaust gas can rise a longer distance along the evaporation bin body 12 after entering the evaporation bin body 12. It takes a longer time for the low-temperature exhaust gas to rise a longer distance, which prolongs the time for the solid waste water to evaporate, and can increase the evaporation amount of the solid waste water, so that the water content in the solid waste is reduced more. At the same time, the exhaust air duct 11 is also connected to the lower part of the cement kiln exhaust chimney 2. Because the low-temperature exhaust gas enters the cement kiln exhaust chimney 2 from the bottom of the cement kiln exhaust chimney 2, the temperature of the low-temperature exhaust gas is maintained at the initial temperature at this time, and the initial temperature is generally high. As the low-temperature exhaust gas rises in the cement kiln exhaust chimney 2, the temperature in the low-temperature exhaust gas will be dissipated into the air through heat radiation and heat conduction, thereby reducing the temperature of the low-temperature exhaust gas. If the exhaust air duct 11 is connected to the middle and upper part of the cement kiln exhaust chimney 2, the temperature of the low-temperature exhaust gas entering the evaporation bin body 12 will be lower, thereby reducing the evaporation efficiency. Therefore, in this embodiment, the exhaust gas duct 11 is connected to the lower part of the cement kiln exhaust gas chimney 2, which further improves the evaporation efficiency of the water in the solid waste.

[0023] The evaporation chamber body 12 is arranged vertically, so that after the low-temperature exhaust gas enters the evaporation chamber body 12, it rises along the evaporation chamber body 12 under the action of atmospheric pressure and is then discharged from the evaporation chamber body 12. Figure 1 As shown, in this embodiment, the evaporation bin body 12 is arranged vertically, that is, the evaporation bin body 12 is arranged along the gravity direction. The solid waste enters from the upper part of the evaporation bin body 12, falls from the evaporation bin 12 from top to bottom under the action of gravity, and fully contacts and exchanges heat with the low-temperature exhaust gas flowing from bottom to top in the evaporation bin under the action of atmospheric pressure, so that the water in the solid waste is evaporated.

[0024] A storage bin 3 is also provided outside the evaporation bin body 12 , and the storage bin 3 is used to store solid waste.

[0025] like Figure 1 As shown, a hoist 4 is provided between the storage bin 3 and the evaporation bin body 12. The specific height of the evaporation bin body 12 can be determined by heat balance calculation according to the moisture content of the solid waste that needs to be reduced. In this embodiment, the height difference between the storage bin 3 and the feed port of the evaporation bin body 12 is compensated by the hoist 4, so that the solid waste in the storage bin 3 can smoothly enter the evaporation bin body 12.

[0026] In this embodiment, the evaporation chamber body 12 is preferably a cylinder. In different embodiments, the evaporation chamber body 12 may also be a square or other shapes, which are not limited here.

[0027] In the present application, part of the low-temperature exhaust gas originally discharged into the atmosphere is introduced into the evaporation bin body 12 through the exhaust gas duct 11, and the low-temperature exhaust gas is discharged from the evaporation bin body 12. Then, the solid waste is lifted from the storage bin 3 to the top opening of the evaporation bin body 12 by the elevator 4, so that the solid waste falls from the top feed port of the evaporation bin body 12, so that the solid waste is fully contacted with the rising low-temperature exhaust gas in the evaporation bin body 12 in the process of falling, so as to achieve the effect of using the low-temperature exhaust gas to evaporate the water content of the solid waste and reduce the water content in the solid waste. Because the heat of the low-temperature exhaust gas that needs to be discharged into the atmosphere is used to evaporate the water content of the solid waste, no additional heat is required, which saves the cost of using fossil fuels to provide heat and reduces CO2 emissions.

[0028] In one embodiment, along the gravity direction, a second screw conveyor 5 is further provided at the bottom of the evaporation bin body 12, and the second screw conveyor 5 is used to convey the solid waste with reduced moisture content falling from the feed port above the evaporation bin body 12. Figure 1 As shown, in this embodiment, a transport vehicle is provided at the discharge port of the second screw conveyor 5, and the transport vehicle receives the solid waste conveyed by the second screw conveyor 5 and then transports it.

[0029] In one embodiment, it further includes an induced draft fan 6 , which is disposed in the exhaust gas induced draft duct 11 and is used to guide the exhaust gas in the cement kiln exhaust gas chimney 2 into the exhaust gas induced draft duct 11 .

[0030] In one embodiment, the specific height of the evaporation bin body 12 can be determined by heat balance calculation according to the moisture content of the solid waste that needs to be reduced. Increasing the length of the evaporation bin body 12 can increase the heat exchange time between the low-temperature exhaust gas and the solid waste. First, it is necessary to determine the value of the moisture content in the solid waste that needs to be reduced, and then calculate the required length of the evaporation bin body 12 based on this value. For example, to reduce the moisture content in the solid waste from 70% to 60%, the required length of the evaporation bin body 12 is X1; to reduce the moisture content in the solid waste from 70% to 50%, the required length of the evaporation bin body 12 is X2; when other conditions are the same, X2 is greater than X1.

[0031] In this embodiment, since the solid waste with high moisture content is generally sticky and wet material, in order to prevent the elevator discharge port 43 from being blocked, the angle between the elevator discharge port 43 and the horizontal plane should be greater than 60°.

[0032] In one embodiment, when the elevator 4 is arranged at a long distance from the evaporation bin 1 , a third conveyor (not shown) can be added under the elevator discharge port 43 and connected to the feed port of the evaporation bin 1 . The third conveyor is used to discharge the solid waste transported by the elevator 4 into the evaporation bin 1 .

[0033] In one embodiment, a first screw conveyor 7 is provided at the bottom of the storage bin 3 , and the conveying range of the first screw conveyor 7 covers the storage bin 3 and the elevator 4 . The first screw conveyor 7 is used to convey the solid waste in the storage bin 3 to the elevator 4 .

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from a cement kiln, characterized in that: include: A storage bin (3), wherein the storage bin (3) is used to store solid waste; An evaporation chamber (1), the evaporation chamber (1) comprising an exhaust gas duct (11) connected to a cement kiln exhaust gas chimney (2) and a vertically arranged evaporation chamber body (12); An elevator (4), comprising an elevator feed port (41) and an elevator discharge port (43), through which solid waste enters the upper inlet of the evaporation bin body (12); A first screw conveyor (7), wherein a feed end of the first screw conveyor (7) is connected to the storage bin (3), and a discharge end of the first screw conveyor (7) is connected to a feed port (41) of the elevator, and the first screw conveyor (7) is used to convey the solid waste stored in the storage bin (3) to the elevator (4).

2. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 1 is characterized in that: A second screw conveyor (5) is provided at the bottom of the evaporation bin body (12), and the second screw conveyor (5) is used to convey the solid waste with reduced moisture content that falls from the upper inlet of the evaporation bin body (12).

3. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 1 is characterized in that: It also includes an induced draft fan (6), which is arranged in the exhaust gas induced draft duct (11) and is used to drive the low-temperature exhaust gas in the cement kiln exhaust gas chimney (2) to flow into the exhaust gas induced draft duct (11).

4. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 1 is characterized in that: The evaporation bin body (12) comprises a plurality of sections of pipes, and the plurality of sections of pipes are used to form different heights.

5. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 1 is characterized in that: The angle between the conveying section of the elevator discharge port (43) and the horizontal plane is greater than or equal to 60°.

6. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 1 is characterized in that: It also comprises a third conveyor, which is arranged between the discharge port (43) of the elevator and the feed port of the evaporation bin (1), and is used to discharge the solid waste transported by the elevator (4) into the evaporation bin (1).

7. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 1 is characterized in that: The conveying range of the first screw conveyor (7) covers the storage bin (3) and the elevator (4), and the first screw conveyor (7) is used to convey the solid waste in the storage bin (3) to the elevator (4).

8. The process system for reducing the moisture content of solid waste by countercurrent evaporation of low-temperature waste gas from cement kilns according to claim 2 is characterized in that: The second screw conveyor (5) and the first screw conveyor (7) are arranged obliquely.

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