An industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas

Abstract

The present invention discloses an industrial silicon waste heat boiler with a vertical and horizontal heat exchange section and independent ash cleaning in different areas, which belongs to the technical field of industrial flue gas waste heat utilization. The boiler is arranged with an inlet flue, a steel ball spreading device, a superheater, a high-temperature evaporator, a guide plate, an ash hopper, and a steel ball collecting device in order from high to low; the suspended steel ball lifting device is respectively connected to the steel ball spreading device and the steel ball collecting device, and is placed outside the boiler shell; the low-temperature evaporator, the economizer, and the outlet flue are arranged parallel to the ground; the low-temperature evaporator is close to the guide plate, and the economizer is close to the outlet flue; a soot blower is provided between the low-temperature evaporator and the economizer, and is placed on the boiler shell; the drum is placed outside the boiler shell, and is respectively connected to the superheater, the high-temperature evaporator, the low-temperature evaporator, and the economizer. The present invention can reduce the number of pipeline arrangements and increase the heat exchange area at the same time, which is conducive to achieving the optimal heat exchange between flue gas and working fluid, realizing the efficient recovery of flue gas waste heat, and achieving the goal of energy saving and consumption reduction.

Description

Technical Field

[0001] The invention relates to the technical field of industrial flue gas waste heat utilization, and in particular to an industrial silicon waste heat boiler with a vertical and horizontal heat exchange section combined and independent ash cleaning in different areas. Background Art

[0002] Waste heat belongs to secondary heat energy. It is the heat energy emitted by the products of primary energy and combustible materials after the conversion process. It is the remaining heat after the process project of fuel combustion process is completed. Waste heat is generally divided into the following seven categories: high-temperature flue gas, high-temperature steam, hot slag, high-temperature heat recovery products (including intermediate products), heat of cooling medium, combustible waste heat, chemical reaction and waste heat of carbon residue. Common waste heat recovery methods include: using waste heat boiler to produce hot water or steam, flue gas preheating air, fluid heat exchanger to treat high-temperature flue gas, etc. In the production process of industrial silicon submerged arc furnace, carbonaceous reducing agent is usually used, which will generate a large amount of flue gas containing components such as CO, CO2, H2, etc., and the exhaust gas contains a large amount of waste heat. The heat contained in the flue gas is equivalent to about 50% of the total energy consumption of the submerged arc furnace. Therefore, it is of great significance to select advanced process technology to recycle the flue gas energy of submerged arc furnace, which can improve energy utilization efficiency and reduce industrial production costs.

[0003] Waste heat from submerged arc furnaces is heat energy that cannot be effectively utilized in the production of submerged arc furnaces or cannot be reasonably utilized during the heating process. The flue gas generated during the smelting process of submerged arc furnaces is currently the main object of waste heat utilization from submerged arc furnaces. Waste heat power generation can not only save energy, but also be beneficial to environmental protection. Waste heat boilers are the most important equipment for waste heat power generation. Waste heat boilers use the heat of waste working fluids as a heat source or combustible material to produce steam for power generation.

[0004] The exhaust gas of industrial silicon ore-fired furnace contains a large number of fine fly ash particles. When the dusty airflow enters the waste heat boiler, the particles may settle on the heating surface, causing serious damage. The thermal conductivity of ash is very small, which increases the thermal resistance and reduces the heat transfer capacity of the heating surface. If the flue gas temperature in the high-temperature area becomes higher, the melting tendency of the particles increases, and it is easier to adhere to the wall surface, causing slagging, which will cause a vicious cycle. Ash accumulation in the low-temperature area may also block the flow channel, increasing the resistance, increasing the fan load, and increasing power consumption. When slagging and ash accumulation are serious, the boiler can only operate at low load or even shut down for maintenance, resulting in a decrease in equipment utilization and inevitable economic losses.

[0005] At present, conventional industrial silicon waste heat boilers are divided into vertical and horizontal structures, but there are structural limitations in operation, which cause dust accumulation and wear, affecting the long-term safe operation of industrial silicon waste heat boilers. First, the flue gas of the vertical arrangement structure flushes the high, medium and low temperature sections of the heating surfaces from the top to the bottom in turn. Considering that the high temperature section of the industrial silicon waste heat boiler is prone to sticky slagging, a steel ball cleaner is usually selected. The steel ball cleaner is arranged on the top of the industrial silicon waste heat boiler to throw steel balls downward to clean the heating surfaces of each level in turn. This will cause large pieces of slag formed during the cleaning of the superheater and the high-temperature evaporator to block the flue gas flow channel between the tube bundles, and the subsequent medium and low temperature sections of the heating surface only deposit loose ash, which only requires compressed air cleaning. Therefore, the medium and low temperature sections of the heating surface are over-cleaned, and the steel ball cleaning causes compaction on the medium and low temperature sections of the heating surface, which is difficult to remove, thereby causing the loose ash to be continuously compacted and deposited, increasing thermal resistance and reducing the thermal energy utilization efficiency of the industrial silicon waste heat boiler. Secondly, the flue gas of the horizontal arrangement structure flushes the heating surfaces of the high and low temperature sections horizontally in turn. At this time, the steel ball cleaning method cannot be selected, and other methods except the steel ball cleaning method can only be used, such as steel brush cleaning, etc. However, these cleaning methods cannot effectively remove the sticky slag on the heating surface of the high temperature section, and the steel brush cleaning has moving parts, which are easy to be damaged during operation, causing the industrial silicon waste heat boiler to have to operate intermittently and often shut down for maintenance, seriously affecting production continuity. Therefore, an industrial silicon waste heat boiler with a combination of vertical and horizontal heat exchange sections and independent cleaning in different areas is needed to effectively prevent and control the slagging and ash accumulation problems on the heating surface. Summary of the invention

[0006] The purpose of the present invention is to provide an industrial silicon waste heat boiler with a vertical and horizontal heat exchange section and independent ash cleaning in different areas, characterized in that the industrial silicon waste heat boiler includes a steel ball spreading device, a superheater, a steel ball lifting device, a high-temperature evaporator, a guide plate, an ash hopper, a steel ball collecting device, a low-temperature evaporator, an economizer, a steel frame, an outlet flue, a soot blower, a boiler shell, a drum and an inlet flue;

[0007] Among them, the inlet flue, steel ball spreading device, superheater, high-temperature evaporator, guide plate, ash hopper and steel ball collecting device are arranged vertically from high to low in sequence; the suspended steel ball lifting device is respectively connected to the steel ball spreading device and the steel ball collecting device, and is placed outside the boiler shell; the low-temperature evaporator, economizer and outlet flue are arranged parallel to the ground; the low-temperature evaporator is close to the guide plate, and the economizer is close to the outlet flue; a soot blower is provided between the low-temperature evaporator and the economizer, and is placed on the boiler shell; the boiler drum is placed outside the boiler shell, and is respectively connected to the superheater, high-temperature evaporator, low-temperature evaporator and economizer; the steel frame supports the industrial silicon waste heat boiler.

[0008] The superheater and high-temperature evaporator are composed of a number of light tubes arranged in a matrix, with gaps between adjacent light tubes, and the center line of the light tube bundle is arranged horizontally and perpendicular to the flue gas flow direction.

[0009] The low-temperature evaporator and the economizer are both composed of a number of H-shaped fin tubes arranged in a matrix, and gaps are provided between adjacent H-shaped fin tubes.

[0010] The fin pitch of H-type fin tube is not less than 30mm.

[0011] The superheater, high temperature evaporator, low temperature evaporator and economizer are all water tube heat exchangers.

[0012] The inlet flue comprises a smoke inlet and an air inlet which are arranged perpendicularly to each other, and a switch valve is arranged on each air inlet.

[0013] The working method of the industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas is characterized in that the switch valve of the inlet flue is opened, and the flue gas is mixed with air and first passes through the superheater and the high-temperature evaporator in sequence, and then is homogenized by the guide plate, and then passes through the low-temperature evaporator and the economizer in sequence for heat exchange before leaving the industrial silicon waste heat boiler from the outlet flue; the steam-water mixture discharged from the high-temperature evaporator enters the boiler drum for steam-water separation, and the steam enters the superheater for heating, is heated to the first temperature and is sent to the steam turbine for power generation or other process, and the downcomer at the lower part of the boiler drum introduces undersaturated water into the high-temperature evaporator and the low-temperature evaporator respectively, and the undersaturated water is sent to the boiler drum after being deoxygenated. After entering the economizer, it absorbs the waste heat of the flue gas and is heated to the second temperature, and then sent to the boiler drum from the economizer; after the industrial silicon waste heat boiler recovers the waste heat of the flue gas, the flue gas is subjected to the centrifugal force at the bottom of the boiler, and the large ash particles are thrown into the ash hopper to achieve primary separation, and the small ash particles are homogenized with the flue gas through the guide plate and then the waste heat is recovered; the steel ball spreading device spreads steel balls for cleaning, and the steel balls collide with the superheater and the high-temperature evaporator, hit the slag on the heating surface and fall into the ash hopper together with the slag, the steel ball collecting device collects the steel balls that fall into the ash hopper, and the steel ball lifting device sends the steel balls back to the steel ball spreading device; the soot blower removes the accumulated ash on the low-temperature evaporator and the economizer.

[0014] The soot blowing method of the soot blower is a compressed air method or a shock wave method.

[0015] The diameter of large ash particles is greater than 20 μm, and the diameter of small ash particles is less than or equal to 20 μm.

[0016] The first temperature is 510°C and the second temperature is 105°C.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention divides the boiler into two sections and arranges them in a vertical and horizontal combination. Different heat exchangers and cleaning methods are selected for the two sections, which can effectively reduce slagging. The self-cleaning advantage of the H-type fin tube can be used to reduce dust accumulation on the heating surface. At the same time, the arrangement of soot blowers can effectively remove dust accumulation on the low-temperature evaporator and economizer.

[0019] 2. The present invention can reduce the number of pipeline arrangements and increase the heat exchange area, which is conducive to achieving the best heat exchange between flue gas and working fluid, realizing efficient recovery of flue gas waste heat, and achieving the goal of energy saving and consumption reduction.

[0020] 3. The structural method of the present invention can not only give full play to various cleaning advantages, but also reduce investment, occupy a medium area and has the characteristics of low carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the main cross-sectional structure of an industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas according to the present invention.

[0022] Figure 2 It is a main schematic diagram of an industrial silicon waste heat boiler with a vertical and horizontal heat exchange section combined and independent cleaning in different areas according to the present invention.

[0023] Figure 3 It is a schematic diagram of the heat exchange tube bundle structure of the superheater and the high-temperature evaporator in the present invention.

[0024] Figure 4 It is a schematic diagram of the heat exchange tube bundle structure of the low-temperature heat exchanger and economizer of the present invention.

[0025] In the figure: 1- steel ball spreading device; 2-superheater; 3- steel ball lifting device; 4-high temperature evaporator; 5-guide plate; 6-ash hopper; 7-steel ball collecting device; 8-low temperature evaporator; 9-economizer; 10-steel frame; 11-exit flue; 12-soot blower; 13-boiler shell; 14-boiler drum; 15-inlet flue. DETAILED DESCRIPTION

[0026] The present invention provides an industrial silicon waste heat boiler with a vertical and horizontal heat exchange section and independent cleaning of different areas. The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] Figure 1 , Figure 2They are respectively a schematic diagram of the main cross-sectional structure and a schematic diagram of the main body of an industrial silicon waste heat boiler with a vertical and horizontal combination of heat exchange sections and independent cleaning in different areas of the present invention. The waste heat boiler is arranged in two sections, in a vertical and horizontal combination. The first section is arranged vertically (the direction of flue gas flow is perpendicular to the ground), and the second section is arranged horizontally (the direction of flue gas flow is parallel to the ground). The first section of the boiler includes a superheater 2 and a high-temperature evaporator 4, whose heating surfaces are bare tubes, and steel balls are used for cleaning. A steel ball spreading device 1 is arranged at the top of the first section of the boiler, a steel ball lifting device 3 is arranged on the side, and an ash hopper 6 and a steel ball collecting device 7 are arranged at the bottom. The second section of the boiler includes a low-temperature evaporator 8 and an economizer 9, whose heating surfaces are H-shaped finned tubes, and a soot blower 12 such as compressed air or shock wave is used. An inlet flue 15 is arranged at the top of the first section of the boiler, and an outlet flue 11 is arranged at the tail of the second section of the boiler. A drum 14 is arranged outside the boiler shell 13 for steam-water separation to form a complete water circulation loop, and a steel frame 10 is arranged to support the entire boiler;

[0028] The inlet flue 15 includes a flue gas inlet and an air inlet. Both the inlet and the air inlet are provided with multiple air inlets. The air inlet is provided with a switch valve. When the flue gas temperature from the industrial silicon ore furnace is too high, the valve of the air inlet is opened, and the flue gas and air are mixed and enter the waste heat boiler.

[0029] The superheater 2 and the high-temperature evaporator 4 are composed of a number of parallel light tubes, the center line of the light tube bundle is arranged horizontally and perpendicular to the flue gas flow direction, and there is a gap between adjacent light tubes. Figure 3 shown.

[0030] The low-temperature evaporator 8 and the economizer 9 are composed of a number of H-shaped finned tubes arranged in parallel, and gaps are provided between adjacent H-shaped finned tubes. Figure 4 shown.

[0031] The first section of the boiler is arranged vertically, and the second section is arranged horizontally. After the first section of the boiler recovers the waste heat of the flue gas, the flue gas is subjected to centrifugal force at the bottom of the first section of the boiler, and large ash particles with a diameter greater than 20μm are thrown into the ash hopper 6 to achieve primary separation, reducing ash accumulation and wear on the second section. The remaining small ash particles with a diameter of less than or equal to 20μm enter the second section of the boiler for waste heat recovery after being homogenized with the flue gas through the guide plate 5.

[0032] The first section of the boiler uses steel balls for ash cleaning. A steel ball spreading device 1 is arranged on the top, and the removed ash falls into the ash hopper 6. A steel ball collecting device 7 is arranged at the bottom to recover the steel balls dropped after ash cleaning, and a steel ball lifting device 3 is arranged to send the steel balls back to the steel ball spreading device 1.

[0033] The second section of the boiler is provided with a low-temperature evaporator 8, an economizer 9 and a soot blower 12. The soot blowing method can be selected from a variety of methods such as a compressed air method or a shock wave method.

[0034] A guide plate 5 is arranged at the outlet of the first section of the boiler to guide the flue gas so that the flue gas can be homogenized and then enter the second section of the boiler from the first section.

[0035] The superheater 2, the high-temperature evaporator 4, the low-temperature evaporator 8 and the economizer 9 are all water-tube heat exchangers.

[0036] The fin pitch of the H-type fin tubes used in the low-temperature evaporator 8 and the economizer 9 is not less than 30 mm.

[0037] The working process of the industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas is as follows:

[0038] The temperature of the waste gas generated during the production of industrial silicon is about 500-600℃, but there may be instantaneous high temperatures reaching more than 1000℃. In order to prevent the instantaneous high temperature from causing more serious slagging, the inlet flue 15 contains a flue gas inlet and an air inlet. Both the inlet and the air inlet are provided with multiple air inlets. The air inlet is provided with a switch valve. When the flue gas temperature is too high, the valve is opened, and the flue gas and air are mixed and then enter the boiler to prevent the instantaneous temperature of the flue gas entering the boiler heating surface from being too high. The flue gas enters the first section of the boiler from the inlet flue 15, passes through the superheater 2 and the high-temperature evaporator 4 in turn, and then enters the second section of the boiler after being homogenized by the guide plate 5. The flue gas leaves the waste heat boiler from the flue gas outlet 11 after sufficient heat exchange with the low-temperature evaporator 8 and the economizer 9 in the second section of the boiler. The waste heat boiler of the present invention is provided with a drum 15 between the high temperature evaporator outlet header and the superheater inlet header. After the steam-water mixture discharged from the high temperature evaporator 4 outlet header enters the drum for steam-water separation, the steam enters the superheater 2 inlet header, is heated to a certain superheat temperature and sent to the turbine for power generation or to other processes. The large diameter downcomer at the bottom of the drum introduces undersaturated water into the inlet headers of the high temperature evaporator 4 and the low temperature evaporator 8 respectively, forming a complete water circulation loop. The boiler feed water is sent to the economizer 9 inlet header after deoxygenation, and is heated to a certain temperature after absorbing the flue gas waste heat and sent to the drum from the economizer 9 inlet header. The first stage of boiler cleaning is steel ball cleaning. During cleaning, the steel balls are spread by the steel ball spreading device 1, collide with the superheater 2 and the high temperature evaporator 4, knock down the slag on the heating surface, and then fall into the ash hopper 6. The steel ball collecting device 7 at the bottom collects the steel balls falling into the ash hopper 6, and the steel ball lifting device 3 is arranged to send the steel balls back to the steel ball spreading device 1. A soot blower 12 is arranged in the second section of the boiler. The soot cleaning method can be selected from a variety of methods such as compressed air method and shock wave method, which can effectively remove the soot accumulated on the low-temperature evaporator 8 and the economizer 9.

[0039] The industrial silicon waste heat boiler of this embodiment reduces the number of pipeline arrangements and increases the heat exchange area, which is conducive to achieving optimal heat exchange between flue gas and working fluid. It occupies a medium area and has the characteristics of low carbon emissions.

Claims

1. An industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas, characterized in that: The industrial silicon waste heat boiler comprises a steel ball spreading device (1), a superheater (2), a steel ball lifting device (3), a high-temperature evaporator (4), a guide plate (5), an ash hopper (6), a steel ball collecting device (7), a low-temperature evaporator (8), an economizer (9), a steel frame (10), an outlet flue (11), a soot blower (12), a boiler shell (13), a boiler drum (14) and an inlet flue (15); wherein an inlet flue (15), a steel ball spreading device (1), a superheater (2), a high-temperature evaporator (4), a guide plate (5), an ash hopper (6), and a steel ball collecting device (7) are arranged in order from high to low perpendicular to the ground; a suspended steel ball lifting device (3) is respectively connected to the steel ball spreading device (1) and the steel ball collecting device (7) and is placed outside the boiler shell (13); a low-temperature evaporator (8), an economizer (9), and an outlet flue (11) are arranged parallel to the ground; the low-temperature evaporator (8) is close to the guide plate (5), and the economizer (9) is close to the outlet flue (11); a soot blower (12) is arranged between the low-temperature evaporator (8) and the economizer (9), and is placed on the boiler shell (13); a boiler drum (14) is placed outside the boiler shell (13), and is respectively connected to the superheater (2), the high-temperature evaporator (4), the low-temperature evaporator (8), and the economizer (9); the steel frame (10) supports the industrial silicon waste heat boiler; The superheater (2) and the high-temperature evaporator (4) are both composed of a plurality of light tubes arranged in a matrix, with gaps between adjacent light tubes, and the center lines of the light tube bundles are arranged horizontally and perpendicular to the direction of flue gas flow; The low-temperature evaporator (8) and the economizer (9) are both composed of a plurality of H-shaped fin tubes arranged in a matrix, with gaps being provided between adjacent H-shaped fin tubes; and the fin pitch of the H-shaped fin tubes is not less than 30 mm.

2. According to claim 1, the industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas is characterized by: The superheater (2), the high-temperature evaporator (4), the low-temperature evaporator (8) and the economizer (9) are all water-tube heat exchangers.

3. The industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning in different areas according to claim 1 is characterized in that: The inlet flue (15) comprises a smoke inlet and an air inlet which are arranged perpendicularly to each other, and each air inlet is provided with a switch valve.

4. An operating method for an industrial silicon waste heat boiler with a vertical and horizontal heat exchange section combined and independent cleaning of each area as claimed in any one of claims 1 to 3, characterized in that: The switch valve of the inlet flue (15) is opened, and the flue gas is mixed with air and first passes through the superheater (2) and the high-temperature evaporator (4) in sequence, then is homogenized by the guide plate (5), and then passes through the low-temperature evaporator (8) and the economizer (9) in sequence for heat exchange before leaving the industrial silicon waste heat boiler from the outlet flue (11); The steam-water mixture discharged from the high-temperature evaporator (4) enters the boiler drum (14) for steam-water separation, and then the steam enters the superheater (2) for heating. After being heated to a first temperature, it is sent to a steam turbine for power generation or other process. The downcomer at the bottom of the boiler drum (14) introduces undersaturated water into the high-temperature evaporator (4) and the low-temperature evaporator (8) respectively. After being deoxygenated, the undersaturated water is sent to the economizer (9), and after absorbing the waste heat of the flue gas, it is heated to a second temperature and sent from the economizer (9) to the boiler drum (14). After the industrial silicon waste heat boiler recovers the waste heat of the flue gas, the flue gas is subjected to the centrifugal force at the bottom of the boiler, and the large ash The slag particles are thrown into the ash hopper (6) to achieve primary separation. The small ash particles are homogenized with the flue gas through the guide plate (5) and then the waste heat is recovered. The steel ball spreading device (1) spreads steel balls for ash cleaning. The steel balls collide with the superheater (2) and the high-temperature evaporator (4), hit the slag on the heating surface and fall into the ash hopper (6) together with the slag. The steel ball collecting device (7) collects the steel balls that fall into the ash hopper (6). The steel ball lifting device (3) sends the steel balls back to the steel ball spreading device (1). The soot blower (12) removes the ash accumulated on the low-temperature evaporator (8) and the economizer (9).

5. The working method of the industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas according to claim 4 is characterized in that: The soot blowing method of the soot blower (12) is a compressed air method or a shock wave method.

6. The working method of the industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas according to claim 4 is characterized in that: The diameter of large ash particles is greater than 20 μm, and the diameter of small ash particles is less than or equal to 20 μm.

7. The working method of the industrial silicon waste heat boiler with vertical and horizontal heat exchange sections and independent cleaning of different areas according to claim 4 is characterized in that: The first temperature is 510°C and the second temperature is 105°C.

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