Mechanism and process for reducing particulate emissions from a belt pre-dryer

Abstract

The present application relates to a mechanism and process method for reducing the particle emission of a belt pre-dryer, which comprises a flexible conveying assembly including a rotatingly arranged mesh belt and mesh holes penetrating through the mesh belt, and a layer of wet shavings to be dried is laid on the mesh belt; a flexible supporting assembly including a straightly arranged rigid guide rail, a rotatingly arranged flexible traction member, and a transversely connecting link arranged between the flexible traction members; the present application changes the fluctuating running state of the shavings layer into a steady parallel moving state, avoids the loose-dense-loose changes of the upper and lower layers of the shavings layer caused by the fluctuating running, reduces the phenomenon that the fine particles adsorbed and filtered by the upper layer of the shavings move and gather to the lower layer and the mesh belt caused by the fluctuating running, reduces the pressure difference between the upper and lower sides of the mesh belt caused by the gathering of the fine particles on the mesh belt, and improves the drying and filtering purification effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of shaving drying tail gas treatment, and particularly relates to a mechanism and process method for reducing particle emission of a belt pre-dryer. BACKGROUND

[0002] Shaving board, also known as particle board, is made of various branches, small-diameter wood, fast-growing wood, wood chips and the like cut into a certain specification of shavings, dried, mixed with glue, hardener, waterproof agent and the like, and pressed under a certain temperature and pressure. The wood before being cut into shavings cannot be too dry, usually with an absolute moisture content of more than 40%, otherwise the shavings after being cut will be too powdery due to the over-dryness of the raw material, losing the mechanical properties of the shavings. The shaving board standard requires that the moisture content of the finished product be less than 13%, and the moisture content of the shavings is strictly required in the processes of screening, gluing, laying and hot pressing, otherwise it will have an important impact on the stability of product quality and production efficiency. Shaving drying is an important and key process in the production of shaving board.

[0003] The total heat consumption of the shaving board production line accounts for 80% to 85% of the total energy consumption of the production line, and the heat consumption of the drying section accounts for 80% to 90% of the total heat consumption of the production line. Low-carbon energy-saving and environmental protection of shaving drying is the most important part of green production of shaving board. The shaving channel type dryer is the mainstream equipment for large-capacity shaving drying, but the drying tail gas after heat exchange is as high as 120-140℃, containing considerable heat and a part of particles, which will cause waste of most heat and pollution of the environment if directly discharged. Therefore, the existing conventional method is to collect the tail gas and use the waste heat of the tail gas to preheat and dry the wet shavings. At present, the main form of tail gas treatment is shaving belt pre-drying treatment.

[0004] The shaving belt pre-dryer is placed at the front end of the channel type dryer, and the wet shavings are uniformly distributed on the continuously running air permeable mesh belt. The tail gas of the channel type dryer is sucked through the wet shaving layer by the induced draft fan, and the heat exchange between the tail gas and the wet shavings conducts the waste heat to the wet shavings to be dried, and then the tail gas is discharged from the belt pre-dryer at a low temperature of about 60-70℃ to the tail gas treatment equipment. While the tail gas exchanges heat with the wet shavings, the fine particles contained in the tail gas are adsorbed and filtered by the wet shavings, achieving the effect of tail gas purification and reducing the content of particles. The wet shaving layer simultaneously achieves the energy-saving and emission-reducing effects of waste heat recovery and particle adsorption of tail gas.

[0005] The tail gas penetrates the wet shaving layer and the mesh belt by the forced suction of the induced draft fan. The belt type pre-drying machine increases the power consumption of the induced draft fan while saving heat and reducing emissions. In the existing belt type pre-drying technology, the mesh belt is supported by mesh belt rollers and is dragged horizontally by a motor and a driving roller. Due to the spacing of the mesh belt rollers, the suction of the induced draft fan forms a pressure difference between the upper and lower sides of the mesh belt. Under the action of the pressure difference, the mesh belt runs with a certain opening upward between the two rollers. When the mesh belt runs to the roller, the mesh belt is supported by the roller and is deflected downward due to the pressure difference between the two sides. Thus, the wet shaving layer supported by the mesh belt runs forward between the upward opening and the downward deflection of the mesh belt. The wet shaving layer on the mesh belt has a certain thickness, and the upper and lower layers of the wet shaving layer running in a wave form will be periodically opened and closed. Under the action of the dynamic pressure of the penetrating gas flow, the fine particles adsorbed and filtered by the wet shaving layer gradually move downward on the mesh belt, fill the gap between the mesh belt, and form a certain thickness of the dense layer, further increasing the pressure difference between the two sides of the mesh belt and the power consumption of the induced draft fan. Under the action of the increased pressure difference of the mesh belt, the probability of the fine particles in the dense layer penetrating the mesh belt pores increases, and the content of the particulate matter in the tail gas increases. SUMMARY

[0006] The purpose of the present application is to overcome the problem of the increase of the power consumption of the induced draft fan and the increase of the content of the particulate matter in the tail gas caused by the downward movement of the fine particles on the mesh belt due to the wave running state of the wet shaving layer and the mesh belt in the existing belt type pre-drying machine, and to provide a mechanism and process method for reducing the particulate matter emission of the belt type pre-drying machine.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a mechanism for reducing the particulate matter emission of a belt type pre-drying machine, comprising:

[0008] a flexible conveying assembly, the flexible conveying assembly comprising a mesh belt rotatingly arranged and a mesh hole penetrating through the mesh belt, and a wet shaving layer to be dried being laid on the mesh belt;

[0009] a flexible supporting assembly, the flexible supporting assembly comprising a rigid guide rail arranged straightly, a flexible traction member arranged rotatingly, and a transverse connecting rod arranged between the flexible traction members, the flexible traction members and the transverse connecting rod moving on the guide rail and bearing the mesh belt below the mesh belt, the speed of the flexible traction member being synchronous with the speed of the mesh belt;

[0010] a tail gas suction assembly, the tail gas suction assembly being used for suction of the tail gas penetrating the wet shaving layer and the mesh belt.

[0011] Optimally, the flexible conveying assembly comprises a driving roller and a driven roller arranged rotatingly, and an auxiliary roller arranged rotatingly below the driving roller and the driven roller, and the mesh belt is wound around the driving roller, the driven roller and the auxiliary roller.

[0012] Optimally, the flexible supporting assembly further comprises a driving wheel and a driven wheel arranged in rotation and a lug fixed inside the flexible traction member, the driving wheel and the driven wheel being arranged inside the driving roller and the driven roller, the flexible traction member being arranged around the driving wheel and the driven wheel, and the transverse connecting rod being fixed on top of the lug.

[0013] Optimally, it further comprises a flexible driving member for connecting the flexible conveying assembly and the flexible supporting assembly, the flexible driving member comprising a flexible primary wheel arranged coaxially with the driving roller, a flexible secondary wheel arranged coaxially with the driving wheel, and a flexible belt arranged around the flexible primary wheel and the flexible secondary wheel.

[0014] Optimally, the transverse connecting rod is perpendicular to the guide rail, and the length of the transverse connecting rod is less than the working width of the mesh belt.

[0015] Optimally, the exhaust gas suction assembly comprises an air guide fan arranged below the mesh belt.

[0016] The application also discloses a process method for reducing particle emission of a belt type pre-dryer, which adopts the above-mentioned mechanism for reducing particle emission of a belt type pre-dryer and comprises the following steps.

[0017] Step one: a layer of wet shavings to be dried is laid on the mesh belt, and dry exhaust gas is introduced above the layer of wet shavings;

[0018] Step two: the layer of wet shavings is moved by rotating the flexible traction member and the transverse connecting rod on the guide rail, and the mesh belt and the layer of wet shavings carried thereby are translated, so that the fluctuation operation of the layer of wet shavings is changed into steady operation;

[0019] Step three: under the suction action of the lower exhaust gas suction assembly, the exhaust gas penetrates through the layer of wet shavings and the mesh belt, and the exhaust gas exchanges heat with the layer of wet shavings, so that the waste heat is transferred to the layer of wet shavings, the layer of wet shavings is heated, the particles contained in the exhaust gas are filtered and adsorbed by the layer of wet shavings when penetrating through the layer of wet shavings, the exhaust gas is purified and the content of the particles is reduced, the exhaust gas after waste heat recovery and filtration purification is discharged from the exhaust gas suction assembly and sent to an exhaust gas reprocessing device;

[0020] Step four: the layer of wet shavings after pre-drying in step three is sent out of the pre-dryer by the mesh belt.

[0021] Thanks to the use of the above technical solutions, the application has the following advantages compared with the prior art:

[0022] The present application changes the fluctuant operation state of the shavings in the pre-drying process into a stable parallel moving state by setting the flexible supporting assembly to assist the support of the net belt, avoids the relaxation-dense-relaxation change of the upper and lower layers of the shavings caused by the fluctuant operation, reduces the phenomenon that the fine particles adsorbed and filtered by the upper layer of the shavings move and gather to the lower layer and the net belt caused by the fluctuant operation, and reduces the pressure difference between the upper and lower sides of the net belt caused by the gathering of the fine particles on the net belt. Due to the reduction of the pressure difference, the resistance of the tail gas suction and the power consumption of the fan are reduced, the probability of the fine particles penetrating the net belt caused by the rising of the pressure difference is reduced, the content of the tail gas particles is reduced, and the dual benefits of power saving and environmental protection are achieved. Due to the use of the flexible traction member, the driving load of the net belt is reduced, and due to the good guiding property of the flexible traction member, the tendency of the long net belt deviation is reduced, which is helpful to prolong the service life of the net belt. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a front view of the present application;

[0024] Figure 2 is an enlarged view of A in the present application Figure 1

[0025] Figure 3 is a schematic view of the fluctuant operation of the shavings in the present application;

[0026] Figure 4 is a schematic view of the stable operation of the shavings in the present application;

[0027] BRIEF DESCRIPTION OF DRAWINGS:

[0028] 1. driving roller; 2. driven roller; 3. auxiliary roller; 4. net belt; 5. driving wheel; 6. driven wheel; 7. flexible traction member; 8. flexible main wheel; 9. flexible auxiliary wheel; 10. flexible belt; 11. guide rail; 12. lug; 13. transverse connecting rod; 14. air blower. DETAILED DESCRIPTION

[0029] The present application will be further described below in combination with the embodiments shown in the drawings.

[0030] As shown in Figure 1 , 2 , it is a structural schematic view of the mechanism for reducing the particle emission of the belt type pre-dryer, which is usually used for conveying the wet shavings to be dried. The wet shavings are dried by using the dry tail gas, and at the same time, the particles in the tail gas are adsorbed and filtered by using the wet shavings, so that the effect of tail gas purification is achieved. The present application can change the fluctuant operation of the existing shavings into a stable operation, and improve the drying and purification effects. The device comprises a flexible conveying assembly, a flexible supporting assembly, a flexible driving member and an air blower 14.

[0031] ​The flexible conveying assembly comprises a driving roller 1, a driven roller 2, an auxiliary roller 3 and a mesh belt 4. The driving roller 1 and the driven roller 2 are rotatably arranged on the two sides of the drying machine and are spaced apart. The mesh belt 4 is arranged around the driving roller 1 and the driven roller 2. The outer side of the mesh belt 4 is fixed with a driving motor connected with the driving roller 1, so as to drive the driving roller 1 to rotate, and then drive the driven roller 2 to rotate through the mesh belt 4, thereby realizing the circulation conveying of the mesh belt 4.

[0032] The wet shavings to be dried are laid on the mesh belt 4 and are synchronously conveyed forward with the mesh belt 4. The mesh belt 4 is provided with through mesh holes, which facilitate the passing of the drying tail gas. The auxiliary roller 3 is rotatably arranged on the side plate and is provided in at least two groups. The mesh belt 4 is arranged around the auxiliary roller 3. The auxiliary roller 3 can change the winding direction of the mesh belt 4 and move away from the flexible traction member 7, so as to avoid the interference and collision between the flexible traction member 7 and the mesh belt 4. The auxiliary roller 3 is symmetrically arranged below the mesh belt 4, so as to ensure that the mesh belt 4 is more stable during the conveying process.

[0033] The tail gas passes through the mesh belt 4 and the wet shavings layer carried by the mesh belt 4 under the extraction of the lower induced draft fan 14, so that there is a pressure difference between the upper and lower mesh belts 4. If the fixed roller type supporting device is used between the driving roller 1 and the driven roller 2, the mesh belt 4 will appear a certain upward sagging opening when running on the roller. When the mesh belt 4 passes between the two supporting rollers, it will form a certain downward deflection due to the pressure difference on the two sides. The mesh belt 4 and the wet shavings layer thereon periodically appear upward and downward deflection between the driving roller 1 and the driven roller 2 when being driven to run, and present a kind of fluctuating running state, as shown in FIG. 6, which will cause the content of particulate matter in the tail gas to increase. Figure 3

[0034] The flexible supporting assembly is arranged below the mesh belt 4 and is used to carry the mesh belt 4, so as to convert the fluctuating motion of the mesh belt 4 into stable running. The flexible supporting assembly comprises a driving wheel 5, a driven wheel 6, a flexible traction member 7, a guide rail 11, a lug 12 and a transverse connecting rod 13. The driving wheel 5 and the driven wheel 6 are rotatably arranged below the inner side of the mesh belt 4. The flexible traction member 7 is arranged around the driving wheel 5 and the driven wheel 6 and synchronously rotates with the driving wheel 5 (at least two groups of the flexible traction member 7 are respectively used to carry the two ends of the transverse connecting rod 13, so as to improve the stability of the overall structure and the reliability of the transverse connecting rod 13 carrying the mesh belt 4. The speed of the flexible traction member 7 is synchronous with or slightly higher than the speed of the mesh belt 4).

[0035] ​The inner side of the flexible traction member 7 is fixed with a lug 12, the lug 12 rotates synchronously with the flexible traction member 7, a transverse connecting rod 13 is fixed on the lug 12 and rotates with the flexible traction member 7 (the transverse connecting rod 13 abuts against the lower surface of the mesh belt 4, which is used to support the mesh belt 4, so as to avoid the mesh belt 4 from being concave downward, thereby affecting the drying effect of the wet shavings and the filtering effect of the tail gas).

[0036] The guide rail 11 is fixed on the inner side of the side plate and located between the driving wheel 5 and the driven wheel 6, the rotating flexible traction member 7 abuts against the upper surface of the guide rail 11, the guide rail 11 supports the flexible traction member 7 and the transverse connecting rod 13, and finally realizes the support of the mesh belt 4. The guide rail 11 is arranged along the conveying direction of the mesh belt 4, the transverse connecting rod 13 is arranged along the width direction of the mesh belt 4 and is perpendicular to the guide rail 11 (the transverse connecting rod 13 cannot be parallel to the guide rail 11, otherwise it will interfere with the rotation of the lower flexible traction member 7, and the length of the transverse connecting rod 13 is less than the working width of the mesh belt 4, which avoids collision with the flexible traction members 7 on both sides during conveying).

[0037] The guide rail 11 is a rigid guide rail, the flexible traction member 7 and the transverse connecting rod 13 moving and carrying the mesh belt 4 on the rigid guide rail make the mesh belt 4 and the shavings thereon run stably, although it cannot avoid the mesh belt 4 from being concave, but it avoids the fluctuant running of the mesh belt 4 and the shavings (because it runs directly or indirectly on the flat guide rail), thereby reducing the movement of fine particles from the upper layer of the shavings to the lower layer and the mesh belt 4, and thereby reducing the air pressure difference between the upper and lower sides of the mesh belt 4.

[0038] The flexible driving member includes a flexible main wheel 8, a flexible secondary wheel 9 and a flexible belt 10, the flexible main wheel 8 is coaxially arranged with the driving roller 1, the flexible secondary wheel 9 is coaxially arranged with the driving wheel 5, and the flexible belt 10 is wound around the flexible main wheel 8 and the flexible secondary wheel 9. When the external driving motor drives the driving roller 1 to rotate, it will synchronously drive the flexible main wheel 8 to rotate, and then drive the flexible secondary wheel 9 to rotate through the flexible belt 10, and finally drive the driving wheel 5 and the driven wheel 6 to drive the flexible traction member 7 to rotate, so as to carry the mesh belt 4 above and reduce the concave arc of the mesh belt 4.

[0039] The tail gas suction assembly is an induced draft fan 14, which is arranged below the mesh belt 4 and is used to suck the drying tail gas above, so that the tail gas can pass through the mesh holes of the wet shavings layer and the mesh belt 4, and the pre-drying tail gas is discharged to a tail gas reprocessing device for external discharge.

[0040] The following will combine the above-mentioned mechanism for reducing the emission of particulate matter of the belt type pre-drying machine to provide a process method for reducing the emission of particulate matter of the belt type pre-drying machine, which specifically includes the following steps:

[0041] Step one: laying the wet shavings layer to be dried on the mesh belt 4, and introducing the drying tail gas above the wet shavings layer;

[0042] Step two: moving on the guide rail 11 by the rotating flexible traction member 7 and the transverse connecting rod 13, and carrying the mesh belt 4 together with the wet sawdust layer to translate, converting the fluctuation operation of the wet sawdust layer into a steady operation;

[0043] Step three: under the suction of the lower exhaust suction assembly, the exhaust gas passes through the wet sawdust layer and the mesh belt 4, and the exhaust gas exchanges heat with the wet sawdust, and the residual heat is transferred to the wet sawdust, realizing the pre-drying of the to-be-dried sawdust; the particulate matter contained in the exhaust gas is filtered and adsorbed by the wet sawdust when penetrating the sawdust layer, realizing the purification of the exhaust gas and the reduction of the particulate matter content, and the exhaust gas after heat recovery and filtration purification is discharged to the exhaust gas treatment device through the exhaust suction assembly;

[0044] Step four: the wet sawdust layer after pre-drying in step three is sent out of the pre-dryer by the mesh belt 4.

[0045] The present application converts the existing mesh belt fluctuation operation into a steady operation (i.e. from Figure 3 to Figure 4 ), reduces the tendency of fine particulate matter to descend to the mesh belt during the pre-drying process, so as to achieve the purpose of reducing the pressure difference of the mesh belt, reducing the load of the induced draft fan, and reducing the particulate matter content in the exhaust gas.

[0046] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A mechanism for reducing particulate emissions from a belt pre-dryer, characterized by, It comprises: a flexible conveying assembly, which comprises a rotatingly arranged mesh belt (4) and mesh holes penetrating through the mesh belt (4), and a layer of wet shavings to be dried is laid on the mesh belt (4); a flexible supporting assembly arranged below the mesh belt (4) to support the mesh belt (4) and convert the fluctuating movement of the mesh belt (4) into stable operation, the flexible supporting assembly comprises a straightly arranged rigid guide rail (11), rotatingly arranged flexible traction members (7) and transversely arranged connecting rods (13) arranged between the flexible traction members (7), the flexible traction members (7) and the connecting rods (13) move on the guide rail (11) and support the mesh belt (4) below the mesh belt (4), and the speed of the flexible traction members (7) is synchronized with the speed of the mesh belt (4); the flexible supporting assembly further comprises a driving wheel (5) and a driven wheel (6) arranged in rotation, and lugs (12) fixed to the inner side of the flexible traction members (7), the flexible traction members (7) are arranged around the driving wheel (5) and the driven wheel (6), and the connecting rods (13) are fixed to the top of the lugs (12); a tail gas suction assembly for sucking tail gas penetrating through the layer of wet shavings and the mesh belt (4), which can dry the wet shavings by using the drying tail gas and filter the particles in the tail gas by using the wet shavings, so as to realize tail gas purification.

2. A mechanism for reducing particulate emissions from a belt pre-dryer according to claim 1, characterized in that: The flexible conveying assembly comprises a driving roller (1) and a driven roller (2) arranged in rotation, and an auxiliary roller (3) arranged below the driving roller (1) and the driven roller (2), and the mesh belt (4) is arranged around the driving roller (1), the driven roller (2) and the auxiliary roller (3).

3. A mechanism for reducing particulate emissions from a belt pre-dryer according to claim 2, wherein: The driving wheel (5) and the driven wheel (6) are arranged inside the driving roller (1) and the driven roller (2).

4. A mechanism for reducing particulate emissions from a belt pre-dryer according to claim 3, wherein: It further comprises a flexible driving member for connecting the flexible conveying assembly and the flexible supporting assembly, the flexible driving member comprises a flexible primary wheel (8) coaxially arranged with the driving roller (1), a flexible secondary wheel (9) coaxially arranged with the driving wheel (5), and a flexible belt (10) arranged around the flexible primary wheel (8) and the flexible secondary wheel (9).

5. The mechanism for reducing particulate emissions from a belt pre-dryer according to claim 1, wherein: The connecting rods (13) are perpendicular to the guide rail (11), and the length of the connecting rods (13) is less than the working width of the mesh belt (4).

6. The mechanism for reducing particulate emissions from a belt pre-dryer according to claim 1, wherein: The tail gas suction assembly comprises an air blower (14) arranged below the mesh belt (4).

7. A process for reducing particulate emissions from a belt pre-dryer characterized by: A mechanism for reducing the emission of particulate matter of a belt type pre-dryer according to any one of claims 1-6, comprising the following steps: Step one: laying a layer of wet shavings to be dried on the mesh belt (4), and introducing drying tail gas from the upper surface of the layer of wet shavings to the lower surface; Step two: moving the flexible traction members (7) and the connecting rods (13) on the guide rail (11) by rotation, and supporting the mesh belt (4) and the layer of wet shavings on the mesh belt (4) to translate, and converting the fluctuating movement of the layer of wet shavings into stable operation; Step three: sucking the tail gas penetrating through the layer of wet shavings and the mesh belt (4) by using the tail gas suction assembly, and drying the wet shavings by using the drying tail gas, and filtering the particles in the tail gas by using the wet shavings, so as to realize tail gas purification. Step three: under the suction of the lower exhaust suction assembly, the exhaust gas passes through the wet shavings layer and the mesh belt (4), and the exhaust gas exchanges heat with the wet shavings, transfers the residual heat to the wet shavings, and realizes the temperature rise of the to-be-dried shavings; the particulate matter contained in the exhaust gas is filtered and adsorbed by the wet shavings when penetrating the shavings layer, realizing the purification of the exhaust gas and the reduction of the particulate matter content; the exhaust gas after residual heat recovery and filtration purification is discharged to the exhaust gas reprocessing device through the exhaust suction assembly; Step four: the wet shavings layer after pre-drying in step three is sent out of the pre-dryer by the mesh belt (4).

Images