Method and device for circulating hot air in a gravel production process using a mother pipe

Abstract

This invention provides a method and apparatus for circulating hot air through a main pipe in gravel production. The method includes feeding coal gangue with a particle size of 20-80mm into the ignition section of a decarbonization combustion device, and sequentially passing through a first self-ignition stage, a second self-ignition stage, a homogenization stage, a first cooling stage, and a second cooling stage before exiting the decarbonization combustion device. Simultaneously, high-temperature hot air from the first cooling stage is fed into a high-temperature main pipe; low-temperature hot air from the second cooling stage is fed into a low-temperature main pipe; the low-temperature hot air in the first branch pipe mixes with the high-temperature hot air and enters the homogenization stage; the low-temperature hot air in the second branch pipe mixes with the high-temperature hot air and enters the second self-ignition stage; the low-temperature hot air in the third branch pipe mixes with the high-temperature hot air and enters the first self-ignition stage; and the low-temperature hot air in the fourth branch pipe directly enters the ignition stage. The flue gas generated in the ignition stage, the first self-ignition stage, the second self-ignition stage, and the homogenization stage is then led out of the decarbonization combustion device. This invention achieves adjustable flue gas temperature range during the combustion stage, as well as stable combustion and temperature control during the combustion process.

Description

Technical Field

[0001] This invention relates to the field of hot air utilization technology, and in particular to a method and apparatus for circulating hot air through a main pipe in the gravel production process. Background Technology

[0002] Coal gangue is a common solid waste in the coal industry. Open-air stockpiles of coal gangue not only pollute the environment but also pose a risk of spontaneous combustion. Therefore, proper disposal of coal gangue is essential for resource utilization and environmental protection. Gravel is a commonly used stone material, typically obtained by directly decarbonizing and burning coal gangue blocks with a particle size of 20-80mm. The process of producing gravel from decarbonized coal gangue requires stable combustion and controlled combustion temperature, with the highest temperature reaching 800-1000℃. The high-temperature gravel after decarbonization needs to be cooled by introducing a large amount of air. This air cooling process provides high-temperature cooling air at approximately 500-700℃ and low-temperature cooling air at approximately 200-300℃. Generally, the high-temperature and low-temperature hot air generated during the cooling process can be treated by waste heat power generation, steam generation, or direct discharge. However, these high-temperature and low-temperature hot air blasts are typically high-temperature and low-temperature air with high oxygen content and calorific value. Using them solely for power generation and other processes does not fully utilize their value. If this heated air could be fully utilized in the coal gangue decarbonization and combustion process, it would not only effectively utilize waste heat but also reduce the amount of air blown in during combustion, facilitating the adjustment and control of combustion temperature and airflow, reducing pipeline layout and fan usage, and lowering equipment construction costs.

[0003] In view of this, the present invention proposes a method and apparatus for using a main pipe to circulate hot air in the gravel production process. Summary of the Invention

[0004] This invention provides a method and apparatus for circulating hot air through a main pipe in the gravel production process. The circulation via the main pipe adjusts the hot air temperature to control the combustion temperature of coal gangue and achieve stable combustion. This addresses the technical problem of insufficient utilization of hot air resources in existing technologies.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for using a main pipe to circulate hot air in a gravel production process includes:

[0007] Crushed coal gangue, with a particle size of 20-80mm obtained from screening, is fed into the ignition section of the decarbonization combustion device. It then sequentially passes through a first self-ignition section, a second self-ignition section, a homogenization section, a first cooling section, and a second cooling section before exiting the decarbonization combustion device. Simultaneously, the decarbonization combustion of coal gangue produces gravel feedstock.

[0008] The first stream of cold air is sent into a cooling section to obtain high-temperature hot air, which is then sent directly or after pretreatment into the high-temperature main pipe.

[0009] The second stream of cold air is sent into the second cooling stage to obtain low-temperature hot air, which is then sent directly or after pretreatment into the low-temperature main pipe.

[0010] The low-temperature main pipe is equipped with a first branch pipe, a second branch pipe, a third branch pipe and a fourth branch pipe. The low-temperature hot air in the first branch pipe mixes with the high-temperature hot air and enters the heat equalization section. The low-temperature hot air in the second branch pipe mixes with the high-temperature hot air and enters the second auto-ignition section. The low-temperature hot air in the third branch pipe mixes with the high-temperature hot air and enters the first auto-ignition section. The low-temperature hot air in the fourth branch pipe directly enters the ignition section.

[0011] The flue gas generated in the ignition section, the first stage of auto-ignition, the second stage of auto-ignition, and the heat spreader is drawn out of the decarbonization combustion device.

[0012] Optionally, the coal gangue raw material may also include one or more mixtures of oil shale, ceramsite pellets, or other fuels with calorific value, wherein the calorific value of the coal gangue raw material is greater than 400 kcal / kg.

[0013] Optionally, the high-temperature hot air temperature is 500-800℃, and the low-temperature hot air temperature is 150-450℃.

[0014] Optionally, the high-temperature hot air and the low-temperature hot air are pre-sent to the high-temperature waste heat boiler and the low-temperature waste heat boiler for heat recovery, and then the cooled high-temperature hot air and the cooled low-temperature hot air are respectively sent to the high-temperature header and the low-temperature header.

[0015] Alternatively, the high-temperature waste heat boiler or the low-temperature waste heat boiler can also be a radiant or convective heat exchanger arranged inside the kiln.

[0016] Optionally, the temperature of the cooling high-temperature hot air is 180-600℃, and the temperature of the cooling low-temperature hot air is 100-250℃.

[0017] Optionally, the flue gas generated in the ignition section, the first stage of self-ignition, the second stage of self-ignition, and the heat soaking section is led out through pipelines and sent to a waste heat recovery boiler for heat recovery. The flue gas after heat recovery is then sent to a flue gas treatment device for environmental protection treatment before being discharged into the atmosphere.

[0018] Furthermore, the present invention also provides an apparatus for the above-described method, comprising:

[0019] The decarbonization combustion device includes an ignition section, a first stage of auto-ignition, a second stage of auto-ignition, a heat equalization section, a first stage of cooling, and a second stage of cooling.

[0020] A first cold air inlet pipe and a high-temperature hot air outlet pipe are connected to a cooling section;

[0021] The second cold air inlet pipe and the low-temperature hot air outlet pipe are connected to the second cooling stage;

[0022] The low-temperature main pipe is directly or indirectly connected to the low-temperature hot air output pipe, and is equipped with a first branch pipe connected to the heat spreader section, a second branch pipe connected to the self-ignition section, a third branch pipe connected to the self-ignition section, and a fourth branch pipe connected to the ignition section.

[0023] The high-temperature main pipe is directly or indirectly connected to the high-temperature hot air output pipe, and is connected to the first branch pipe, the second branch pipe and the third branch pipe by means of direct connection to the branch pipe through valves or by mixing with the outside air before entering the branch pipe. The hot air in the main pipe and the branch pipe can be drawn into the kiln by the exhaust fan at the bottom of each process section of the kiln.

[0024] The first exhaust pipe is connected to the heat spreader section, the second exhaust pipe is connected to the auto-ignition section, the third exhaust pipe is connected to the auto-ignition section, and the fourth exhaust pipe is connected to the ignition section.

[0025] Optionally, if the strength performance of the product after decarbonization and combustion is not considered, the heat spreader and the first branch pipe can be omitted.

[0026] Optionally, the low-temperature header is connected to the low-temperature hot air output pipe via a low-temperature waste heat boiler; the high-temperature header is connected to the high-temperature hot air output pipe via a high-temperature waste heat boiler.

[0027] Optionally, both the low-temperature header and the high-temperature header are tapered pipes; the first exhaust pipe, the second exhaust pipe, the third exhaust pipe, and the fourth exhaust pipe are directly or through the flue gas collecting pipe connected to the waste heat boiler.

[0028] The beneficial effects of the technical solution provided by this invention include at least the following:

[0029] This method aims to fully utilize the heat and flow rate of hot air, achieving an optimal match between the temperature and air volume required by each process stage. Traditionally, the high-temperature hot air discharged after rapid cooling is sent to the calcination and soaking sections. These two sections have high sintering temperatures, and the calcination section requires a large air volume. However, when the raw materials contain calorific value, a calcination section is unnecessary; only a soaking section is needed, which requires less hot air. Simultaneously, the inlet air temperature required for the self-ignition process of internally heated raw materials is low, and the inlet air temperature varies at different stages, leading to increased diversity in the required inlet air temperature and volume. Therefore, by setting up high-temperature and low-temperature headers, not only can flue gas be supplied to different combustion stages of the decarbonization combustion device, but energy is also saved during the combustion process.

[0030] This facilitates stable combustion and temperature control during the combustion process using hot air at different temperatures. When raw materials with calorific value are heated, fluctuations in calorific value can lead to temperature fluctuations, especially in the gravel combustion layer where the temperature may increase rapidly due to the increased calorific value. The self-combustion process of gravel can be regulated by detecting the flue gas temperature at the self-combustion calcination outlet, adjusting the ratio of high-temperature and low-temperature headers, and considering the heat exchange effect of the upstream waste heat boiler.

[0031] This achieves the goal of saving on piping and fans. By setting up branch pipes, different proportions of low-temperature flue gas and high-temperature flue gas can be mixed. According to the actual needs of each combustion stage, the temperature range of the flue gas supplied for each combustion stage can be adjusted, which can effectively control the temperature and flow of the supplied flue gas. At the same time, it reduces the layout of pipes and fans, and can effectively reduce construction costs.

[0032] This method is highly adaptable and is suitable not only for coal gangue with calorific value, but also for oil shale with calorific value, and for ceramsite pellets formed by grinding and granulating solid waste with calorific value, either alone or mixed with other raw materials. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a process flow diagram of the gravel production process of the present invention, which uses a main pipe to circulate hot air. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, this invention provides a method for circulating hot air through a main pipe during gravel production:

[0037] Crushed and sieved coal gangue with a particle size of 20-80mm is fed into the ignition section of the decarburization combustion device. The combustion nozzles are activated, raising the temperature of the ignition section to 600-1000℃. The ignition section primarily dries the coal gangue and generates water-containing flue gas. After drying in the ignition section, the coal gangue sequentially enters a first stage of auto-ignition where the calorific value components undergo stable combustion; a second stage of auto-ignition where the calorific value components are fully combusted; and a third stage of homogenization where the temperature of the upper and lower layers is uniform. During this stage, the carbon in the coal gangue gradually burns, decarburizing the gangue into gravel. The gravel exiting the homogenization section is cooled to 600-750℃ in a rapid cooling stage and then to 80-180℃ in a slow cooling stage before being sent out of the kiln for subsequent processes.

[0038] In the first and second cooling stages, a first stream of cold air and a second stream of cold air are introduced respectively to air-cool the high-temperature gravel. Since the gravel entering the second cooling stage has already undergone one cooling cycle, the first and second cooling stages respectively obtain high-temperature hot air and low-temperature hot air. The high-temperature hot air temperature is 500-800℃, and the low-temperature hot air temperature is 150-450℃. The high-temperature hot air and low-temperature hot air are introduced into the high-temperature header and low-temperature header respectively through high-temperature hot air outlet pipe and low-temperature hot air outlet pipe. Preferably, in order to fully utilize the energy of the hot air, a high-temperature waste heat boiler and a low-temperature waste heat process can be set up between the hot air outlet pipe and the header to perform a heat recovery of the high-temperature hot air and low-temperature hot air in advance, thereby improving the energy utilization rate.

[0039] The low-temperature main pipe is equipped with a first branch pipe connected to the heat spreader section, a second branch pipe connected to the self-ignition section, and a third branch pipe connected to the self-ignition section. These branch pipes are connected to the high-temperature main pipe through direct connection, bypass, or mixer. In the first branch pipe, high-temperature hot air is the main component, supplemented by a small amount of low-temperature hot air, and the mixed hot air with a temperature of 400-500°C enters the heat spreader section. In the second branch pipe, low-temperature hot air is the main component, supplemented by a small amount of high-temperature hot air, and the mixed hot air with a temperature of 200-450°C enters the self-ignition section. In the third branch pipe, high-temperature hot air is the main component, supplemented by a small amount of low-temperature hot air, and the mixed hot air with a temperature of 180-350°C enters the self-ignition section. In the fourth branch pipe, the remaining low-temperature hot air with a temperature of 100-180°C enters the ignition section. The above configuration allows high-temperature and low-temperature hot air to mix within the branch pipes, and the appropriately heated mixed air is then delivered to its respective combustion stage, thus stabilizing the combustion of coal gangue. By adjusting the mixing ratio of high-temperature and low-temperature hot air within each branch pipe, the temperature of the mixed hot air can be adjusted, effectively controlling the combustion temperature of the coal gangue. Since the hot air in the high-temperature and low-temperature main pipes is gradually drawn into the decarbonization combustion device through the branch pipes, the air volume in the main pipes gradually decreases; therefore, both the low-temperature and high-temperature main pipes are tapered pipes. Additionally, the low-temperature main pipe also has a fourth branch pipe directly connected to the ignition section.

[0040] The first, second, third, and fourth exhaust pipes, connected to the heat exchange section, the second self-ignition section, the first self-ignition section, and the ignition section, guide the flue gas generated in each combustion section out of the decarbonization combustion device. The flue gas can be directly introduced into the waste heat boiler, or it can be collected in a flue gas collecting pipe before being introduced into the waste heat boiler, thus effectively recovering heat from the flue gas. The flue gas exiting the waste heat boiler is sent to a flue gas treatment device for environmental treatment before being discharged into the atmosphere.

[0041] Example 1

[0042] Coal gangue with a particle size of 20-80mm is fed into the decarbonization combustion device, and then exits the device after passing through an ignition section with an average temperature of 1050℃, a first auto-ignition section at 350℃, a second auto-ignition section at 700℃, a soaking section at 1000℃, a first cooling section at 750℃, and a second cooling section at 250℃. The first and second streams of cold air enter the first and second cooling sections respectively, forming high-temperature hot air and low-temperature hot air, with temperatures of 785℃ and 450℃ respectively. These two streams of hot air are then sent to the high-temperature and low-temperature waste heat boilers, where they are cooled to 580℃ and 120℃ respectively, before entering the high-temperature header and low-temperature header respectively. In the first branch pipe, mixed hot air at a temperature of 450°C enters the soaking section; in the second branch pipe, mixed hot air at a temperature of 320°C enters the second auto-ignition section; in the third branch pipe, mixed hot air at a temperature of 250°C enters the first auto-ignition section; and in the fourth branch pipe, the remaining 110°C low-temperature hot air enters the ignition section. The first to fourth exhaust pipes discharge the flue gas from the soaking section, the second auto-ignition section, the first auto-ignition section, and the ignition section. The gas is then collected in the flue gas collection pipe, sent to the waste heat boiler for heat recovery, and finally sent to the flue gas treatment device for environmental treatment before being discharged into the atmosphere.

[0043] Example 2

[0044] Low-calorific-value coal gangue blocks (30-70mm in diameter, calorific value below 100kcal / kg) are mixed with high-calorific-value ceramsite (1100kcal / kg) granulated from coal gangue and coal slime in a 1:1 ratio and fed into a decarbonization combustion device. The mixture then passes through an ignition section with an average temperature of 1000℃, a first auto-ignition section at 350℃, a second auto-ignition section at 850℃, a first cooling section at 750℃, and a second cooling section at 250℃ before exiting the device. The first and second streams of cold air enter the first and second cooling sections respectively, forming high-temperature hot air and low-temperature hot air, with temperatures of 700℃ and 420℃ respectively. These two streams of hot air are then fed into high-temperature and low-temperature waste heat boilers, where they are cooled to 450℃ and 120℃ respectively, before entering the high-temperature header and low-temperature header respectively. In the second branch pipe, mixed hot air at a temperature of 380℃ enters the second stage of auto-ignition; in the third branch pipe, mixed hot air at a temperature of 300℃ enters the first stage of auto-ignition; in the fourth branch pipe, the remaining 120℃ low-temperature hot air enters the ignition stage. The first to fourth exhaust pipes discharge the flue gas from the heat spreader, the second stage of auto-ignition, the first stage of auto-ignition, and the ignition stage. The gas is then collected in the flue gas collection pipe, sent to the waste heat boiler for heat recovery, and finally sent to the flue gas treatment device for environmental treatment before being discharged into the atmosphere.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for circulating hot air through a main pipe in a gravel production process, characterized in that, include: Crushed coal gangue, with a particle size of 20-80mm obtained from screening, is fed into the ignition section of the decarbonization combustion device. It then sequentially passes through a first self-ignition section, a second self-ignition section, a homogenization section, a first cooling section, and a second cooling section before exiting the decarbonization combustion device. Simultaneously, the decarbonization combustion of coal gangue produces gravel. The first stream of cold air is sent into the first cooling stage to obtain high-temperature hot air, and the second stream of cold air is sent into the second cooling stage to obtain low-temperature hot air. The high-temperature hot air and the low-temperature hot air are first sent into the high-temperature waste heat boiler and the low-temperature waste heat boiler for heat recovery. Then the cooled high-temperature hot air is sent into the high-temperature main pipe, and the cooled low-temperature hot air is sent into the low-temperature main pipe. The low-temperature main pipe is equipped with a first branch pipe, a second branch pipe, a third branch pipe and a fourth branch pipe. The low-temperature hot air in the first branch pipe mixes with the high-temperature hot air and enters the heat equalization section. The low-temperature hot air in the second branch pipe mixes with the high-temperature hot air and enters the second auto-ignition section. The low-temperature hot air in the third branch pipe mixes with the high-temperature hot air and enters the first auto-ignition section. The low-temperature hot air in the fourth branch pipe directly enters the ignition section. The flue gas generated in the ignition section, the first stage of auto-ignition, the second stage of auto-ignition, and the heat soaking section is led out of the decarbonization combustion device and sent to the waste heat recovery boiler for heat recovery. The flue gas after heat recovery is sent to the flue gas treatment device for environmental protection treatment before being discharged into the atmosphere. An apparatus for the method includes: The decarbonization combustion device includes an ignition section, a first stage of auto-ignition, a second stage of auto-ignition, a heat equalization section, a first stage of cooling, and a second stage of cooling. A first cold air inlet pipe and a high-temperature hot air outlet pipe are connected to a cooling section; The second cold air inlet pipe and the low-temperature hot air outlet pipe are connected to the second cooling stage; The low-temperature main pipe is directly or indirectly connected to the low-temperature hot air output pipe, and is equipped with a first branch pipe connected to the heat spreader section, a second branch pipe connected to the self-ignition section, a third branch pipe connected to the self-ignition section, and a fourth branch pipe connected to the ignition section. The high-temperature main pipe is directly or indirectly connected to the high-temperature hot air output pipe, and is connected to the first branch pipe, the second branch pipe and the third branch pipe by means of direct connection to the branch pipe through valves or by mixing with the outside air before entering the branch pipe. The hot air in the main pipe and the branch pipe can be drawn into the kiln by the exhaust fan at the bottom of each process section of the kiln. The first exhaust pipe is connected to the heat spreader section, the second exhaust pipe is connected to the auto-ignition section, the third exhaust pipe is connected to the auto-ignition section, and the fourth exhaust pipe is connected to the ignition section.

2. The method according to claim 1, characterized in that, Coal gangue raw materials also include one or more mixtures of oil shale, ceramsite pellets, or other fuels with calorific value, and the calorific value of coal gangue raw materials is greater than 400 kcal / kg.

3. The method according to claim 1, characterized in that, The high-temperature hot air temperature is 500-800℃, and the low-temperature hot air temperature is 150-450℃.

4. The method according to claim 1, characterized in that, The temperature of the high-temperature hot air for cooling is 180-600℃, and the temperature of the low-temperature hot air for cooling is 100-250℃.

5. The method according to claim 1, characterized in that, If the strength performance of the product after decarbonization and combustion is not considered, the heat spreader and the first branch pipe are omitted.

6. The method according to claim 1, characterized in that, The low-temperature main pipe is connected to the low-temperature hot air output pipe through a low-temperature waste heat boiler; the high-temperature main pipe is connected to the high-temperature hot air output pipe through a high-temperature waste heat boiler.

7. The method according to claim 1, characterized in that, Both the low-temperature header and the high-temperature header are tapered pipes; the first exhaust pipe, the second exhaust pipe, the third exhaust pipe and the fourth exhaust pipe are directly connected to the waste heat boiler through the flue gas collection pipe.

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