Alternative fuel vertical pre-combustion furnace

Abstract

An alternative fuel vertical pre-combustion furnace comprises a vertical combustion chamber furnace body, a multi-stage stepped furnace hearth arranged on the side wall of the pre-combustion furnace body and a pneumatic pulse injection device arranged on the furnace hearth, and castable is arranged on the inner wall of the whole furnace body. Light flammable substances are completely incinerated under the driving of high-speed airflow, heavier flame-retardant substances fall into the next step to be continuously incinerated, the burn-off rate of the alternative fuel is greatly improved after the alternative fuel stays, is scattered and is pre-combusted, and completely-combusted material residues are dispersed by strong injection of compressed air of an air cannon system; therefore, the influence on the cement kiln caused by sedimentation of the material slag agglomerated in the decomposing furnace is solved. And materials on the uppermost combustion platform sequentially slide to the second-stage combustion step platform and then slide to the next-stage combustion platform layer by layer, and the process is repeated. And waste gas and ash after incineration are discharged from the bottom of the pre-combustion furnace and enter a kiln tail decomposing furnace system, when the material slag is harmful to the kiln system, the material slag can be discharged, and high-temperature airflow enters the decomposing furnace.

Description

Technical Field

[0001] The utility model belongs to the technical field of pre - combustion furnaces, and mainly relates to a vertical pre - combustion furnace for alternative fuels in cement production. Background Art

[0002] The utilization of alternative fuels has become an industry consensus as an important measure for carbon emission reduction and carbon neutrality in the cement industry, and it is one of the effective ways for the low - carbon, green and circular development of the cement industry.

[0003] Currently, in the technical routes of using alternative fuels in the cement industry, there are two types: directly entering the decomposition furnace and alternative - fuel pre - combustion furnace + cement - kiln decomposition furnace. Directly entering the decomposition furnace has a great impact on the kiln condition, with a low substitution rate and poor adaptability. To avoid the impact of directly entering the decomposition furnace with alternative fuels on the kiln condition, the "alternative - fuel pre - combustion furnace + cement - kiln decomposition furnace" technical route is widely used. In this route, the alternative fuel is pre - burned in the pre - combustion furnace and then enters the kiln system. The heat generated by the combustion of the alternative fuel is used to heat and decompose the raw meal, thus replacing part of the heat generated by the combustion of pulverized coal in the decomposition furnace to achieve the purpose of coal saving and cost reduction. The residue after the combustion of the alternative fuel in the pre - combustion furnace enters the cement - kiln system and is sintered and solidified by the clinker to realize the resource utilization and reduction of the alternative fuel. When using alternative fuels in the cement - kiln system, to increase the utilization rate of alternative fuels, conditions such as incineration temperature, residence time, and complete combustion need to be met. Therefore, it is particularly important to select a suitable core equipment for the pre - combustion furnace.

[0004] In the existing equipment technology, a stepped combustion platform is generally used to achieve stepped combustion of fuels. However, when fuels are burned on the stepped combustion platform, due to the complexity of alternative fuels and the fact that alternative fuels in the pre - combustion furnace rely on tertiary air for combustion support, most alternative fuels only come into limited contact with the tertiary air on the surface of the stepped furnace for ignition and combustion. Its processing capacity is affected by the tertiary air and the residence time of alternative fuels in the stepped furnace, resulting in incomplete combustion or a single type of alternative fuel for supporting combustion; the unburned ash residues are in a lumpy shape and are likely to settle in the decomposition furnace, causing great interference to the cement kiln and affecting the normal production of the cement kiln. Moreover, the stepped furnace has a large inclination angle and a large floor area, requiring a high - standard transformation site for the existing system.

[0005] The patent number CN204786433U discloses a diversion incineration device capable of dynamically regulating gas - solid flow, and proposes a vertical - structure pre - combustion furnace. However, there are still problems such as the agglomeration of the slag after incineration and its settlement in the decomposition furnace; the internal diversion plate structure and angle adjustment make it difficult to lay refractory materials, or cause air leakage due to poor furnace body sealing, or cause local high temperature in the furnace body, resulting in structural deformation and affecting the use.

[0006] Resources such as straw are abundant and are a good type of biomass fuel. However, the content of alkali metals, especially potassium, in straw fuel is relatively high, which is prone to caking and clogging, affecting the rotary kiln system, and enriching a relatively high content of alkali in the clinker, having a greater impact on the later strength of the cement clinker. In the prior art, the precalciner is connected to the decomposition furnace, and the ash residue after incineration enters the cement clinker calcination, which is not suitable for alternative fuels such as straw. Summary of the Invention

[0007] In order to overcome the above deficiencies, the present utility model provides a vertical precalciner for alternative fuels.

[0008] The technical solution adopted by the present utility model to solve its technical problems:

[0009] A vertical precalciner for alternative fuels, comprising:

[0010] A furnace body, the upper end of the furnace body is provided with a feed inlet and an air inlet; the lower end is provided with an exhaust gas and slag outlet and an external discharge channel, and the inner wall of the furnace body is lined with castable.

[0011] Multiple hearths, the hearths are arranged in a multi-stage stepped shape and are staggeredly distributed on the inner wall of the furnace body;

[0012] A pneumatic pulse injection device, including buried injection holes horizontally arranged on each step of the hearth, the pneumatic pulse injection device is connected to the buried injection holes, and is used to disperse combustibles and their combustion residues on the steps, so that they flip and rotate forward on the hearth steps, and at the same time supplement combustion-supporting air into the furnace.

[0013] The number of the hearths is not less than 2, and the hearth angle is 20° to 50°; the steps of the hearth gradually decrease from the furnace wall to the center of the furnace body.

[0014] The pneumatic pulse injection device includes an air cannon and an injection unit, and the injection unit is connected to the buried injection holes; by controlling the starting frequency and sequence of the air cannon, the actuating mechanism of the injection unit is driven point by point in layers to distribute compressed air pulses to the buried injection holes in the furnace.

[0015] A screw conveyor is provided at the feed inlet of the furnace body.

[0016] A circular pipe for introducing cooling C4 raw meal is also provided at the upper end of the furnace body.

[0017] The exhaust gas and slag outlet is communicated with the decomposition furnace.

[0018] An electric ash discharge valve is provided in the external discharge channel.

[0019] A thermocouple and a fire-viewing monitoring device are provided on the side of the furnace body, which are used to monitor and observe the incineration temperature and the stockpiling situation in the furnace.

[0020] The pneumatic pulse injection device can be replaced by a push rod.

[0021] Due to the adoption of the technical solution as described above, the utility model has the following advantages:

[0022] 1. The internal structure of the pre-combustion furnace of the utility model is improved, and the air cannon system is used as the power source, which solves the problems of difficult refractory construction caused by the deflector structure, or local high temperature of the furnace body, resulting in structural deformation and affecting the use effect.

[0023] 2. The alternative fuel stays at the intermediate step, is blown and dispersed by high-pressure air injection, and is pre-combusted. The residence time of the alternative fuel and the thickness of the material layer are controlled by the starting frequency of the air cannon in the pneumatic pulse injection system, thereby improving the burnout rate and substitution rate of the alternative fuel.

[0024] 3. The fully combusted material slag is strongly blown and dispersed by the compressed air of the air cannon system, thus solving the influence of the agglomeration of the slag settling in the decomposition furnace on the cement kiln.

[0025] 4. A slag discharge channel is provided at the bottom of the furnace body. When the slag composition is harmful to the kiln system and is not suitable for entering the kiln, it can be discharged for treatment to avoid affecting the kiln system and the quality of the cement clinker. Description of the Drawings

[0026] Figure 1 is the overall structural schematic diagram of the utility model;

[0027] Figure 2 is the top view of the internal structure of the furnace when the number of furnace bed steps is 5. Detailed Embodiment

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the utility model. Usually, the components of the embodiments of the utility model described and illustrated herein can be arranged and designed in various different configurations.

[0029] As Figure 1 shown, an alternative fuel vertical pre-combustion furnace includes a vertical combustion chamber furnace body 1, a multi-stage stepped furnace bed 2 provided on the side wall of the pre-combustion furnace body 1, a pneumatic pulse injection device 3 on the furnace bed, and a castable is applied to the inner wall of the overall furnace body 1.

[0030] The top of the pre - combustion furnace is provided with a feed inlet, a circular pipe 4 for cooling C4 raw meal, and a tertiary air inlet 5. The feed inlet is respectively connected to two screw conveyors 6 for feeding alternative fuels; at the bottom of the pre - combustion furnace body 1, there are an exhaust gas and slag outlet 7 communicating with the inside of the decomposition furnace, a slag discharge channel 8, and an electric ash discharge valve 9 in the discharge channel 8. On the side of the pre - combustion furnace shell, there are thermocouples and fire - watching monitoring devices for monitoring and observing the incineration temperature and the stockpiling situation in the furnace.

[0031] Figure 2 It is a top - view of the internal structure when the number of steps on the furnace bed is 5 levels.

[0032] There is an electric discharge valve 9 in the slag discharge channel 8. Under normal circumstances, the electric discharge valve 9 is in a closed state, which plays a role of material sealing for the discharge channel 8 after being filled with slag, and the slag enters the decomposition furnace; when the slag is not suitable for entering the kiln, the electric discharge valve 9 opens and the slag is discharged.

[0033] The pre - combustion furnace is internally provided with multiple stepped furnace beds 2 which are staggered in the furnace. Figure 2 In [a certain situation], the number of furnace beds is 2 sections, the angle of the furnace bed is 30°, that is, the inclined plane where the steps are located forms a 30 - degree angle with the horizontal plane. And the two furnace beds 2 are arranged opposite to each other. Among them, the furnace bed 2 is provided with 5 - step stepped - type steps, and the steps decrease in sequence from the furnace wall to the center of the furnace body.

[0034] Each step of the stepped furnace bed 2 is horizontally provided with buried blow - holes, which are connected to the blow - unit and air cannon installed outside the furnace bed 2, constituting a multi - stage pneumatic pulse blowing device 3 composed of the air cannon and the blow - unit.

[0035] The pneumatic pulse blowing device 3 controls the execution mechanism of the blow - unit in a layered and point - driven manner by controlling the start frequency and sequence of the air cannon, and distributes compressed air pulses to the blow - holes in the furnace. The high - pressure air flow is used to blow away the combustibles and their combustion residues on the steps, making them flip and rotate forward on the combustion steps in the furnace, and at the same time supplementing combustion - supporting air to the furnace.

[0036] The pneumatic pulse blowing device 3 can be replaced by a push rod. One end of the push rod is set on the step surface of the furnace bed 2, and the other end passes through the hole reserved in the furnace body 1 and extends to the outside. The push rod located outside the furnace body 1 can be connected to a cylinder, and the cylinder is controlled by a solenoid valve and a controller to realize the sliding of the push rod on the step surface, thereby pushing the materials or incompletely burned impurities on the step surface to the next step.

[0037] The alternative fuel enters the furnace from the feed inlet. Driven by the tertiary air, it is dried, pre-combusted, and stays and burns on the stepped furnace bed to achieve full reaction and combustion. The light and flammable substances are completely incinerated under the drive of the high-speed air flow, and the heavier and difficult-to-burn substances fall to the next level to continue incineration. After the alternative fuel stays, is dispersed, and pre-combusted in the middle, the burnout rate of the alternative fuel is greatly increased. The completely burned material slag is strongly blown and dispersed by the compressed air of the air cannon system, thus solving the influence of the agglomeration of the material slag settling in the decomposition furnace on the cement kiln. The materials on the topmost combustion platform slide down to the second-level combustion stepped platform in sequence and then slide down to the lower combustion platforms layer by layer to repeat this process. The incinerated waste gas and ash are discharged from the bottom of the pre-combustion furnace and enter the decomposition furnace system at the kiln tail. When the material slag is harmful to the kiln system, it can be discharged for treatment, and the high-temperature air flow enters the decomposition furnace.

[0038] The parts not described in detail above are prior arts, so no detailed description is given.

Claims

1. An alternative fuel vertical pre-combustion furnace, characterized in that: Including: A furnace body, the upper end of the furnace body is provided with a feed inlet and an air inlet; the lower end is provided with an exhaust gas and slag outlet and an external discharge channel, and the inner wall of the furnace body is lined with castable. Multiple hearths, the hearths are in a multi-stage stepped shape and are staggeredly distributed on the inner wall of the furnace body. A pneumatic pulse jetting device, including buried jetting holes horizontally arranged on each step of each hearth. The pneumatic pulse jetting device is connected to the buried jetting holes, and is used to blow away combustibles and their combustion residues on the steps, so that they flip and rotate forward on the hearth steps, and at the same time supplement combustion-supporting air into the furnace.

2. The vertical pre-combustion furnace with alternative fuel according to claim 1, wherein: The number of the hearths is not less than 2, and the angle of the hearths is 20° - 50°; the steps of the hearths decrease in sequence from the furnace wall to the center of the furnace body.

3. The alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: The pneumatic pulse jetting device further includes an air cannon and a jetting unit. The jetting unit is connected to the buried jetting holes; by controlling the starting frequency and sequence of the air cannon, the actuating mechanisms of the jetting unit are driven point by point in layers, and compressed air pulses are distributed to the buried jetting holes in the furnace.

4. An alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: A screw conveyor is provided at the feed inlet of the furnace body.

5. An alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: A circular pipe for introducing cooled C4 raw meal is further provided at the upper end of the furnace body.

6. The alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: The exhaust gas and slag outlet is communicated with a precalciner.

7. An alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: An electric dust discharge valve is provided in the external discharge channel.

8. An alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: Thermocouples and a fire-watching monitoring device are provided on the side of the furnace body, which are used to monitor and observe the incineration temperature and the stockpiling situation in the furnace.

9. An alternative fuel vertical pre-combustion furnace according to claim 1, characterized in that: The pneumatic pulse jetting device can be replaced by a push rod.

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