WO2015100708A1

WO2015100708A1 - Drying equipment and drying method

Info

Publication number: WO2015100708A1
Application number: PCT/CN2014/001182
Authority: WO
Inventors: 李胜; 史勇春; 蒋斌; 梁国林; 窦刚; 贾世阳; 万象明; 高俊荣
Original assignee: 山东科院天力节能工程有限公司
Priority date: 2014-01-06
Filing date: 2014-12-26
Publication date: 2015-07-09

Abstract

Drying equipment and method for drying materials using the same. The drying equipment comprises a feeder (10), a fluidized moving bed dryer(12) and an unloader (14) sequentially connected; the fluidized moving bed dryer (12) comprises a constant-speed drying fluidized bed segment (120) and a reduced-speed drying moving bed segment (122); the feeder (10) is connected to the constant-speed drying fluidized bed segment (120), and the unloader (14) is connected to the reduced-speed drying moving bed segment (122); at least one set of heat exchangers (124) for heating materials is disposed within the constant-speed drying fluidized bed segment (120) and the reduced-speed drying moving bed segment (122) respectively; and a gas distributor (1200) for adjusting the flow speed and pressure of fluidized gas is disposed between the constant-speed drying fluidized bed segment (120) and the reduced-speed drying moving bed segment (122), the fluidized gas passing through the gas distributor (1200) into the constant-speed drying fluidized bed segment (120).

Description

Drying device and drying method

Technical field

The invention relates to a drying device and a drying method, in particular to a fluidized moving bed steam drying device and a drying method.

Background technique

In industrial production, there are many types of high-humidity materials that need to be dried to a lower moisture content. Taking lignite as an example, whether it is burning, transporting or meeting the requirements of coal chemical processes, it is often necessary to have the original moisture of 30%-60%. Lignite is dried to a lignite product with a final moisture of 3% to 5%.

Conventional equipment and methods for drying high humidity materials employ: A) hot flue gas as a heat source to directly heat the material, or B) hot steam as a heat source to indirectly heat the material. Due to the high volatile content of the material or the influence of the inlet air temperature, the material with low ignition point (such as lignite) is easy to ignite and burn, and there is a safety hazard; the latter adopts indirect heating, the heat value of steam is high, and the process is safe and reliable. However, the latter needs to consume high calorific value fuels and has high economic costs.

However, due to the majority of wet materials, such as lignite, the drying process is divided into two stages, namely, a constant-speed drying stage from the drying of the original moisture content to its critical moisture content and drying from its critical moisture content to the target moisture content of the product. Slow down drying stage. When the wet material adopts the technical scheme of CN101581533A in the constant-speed drying stage, the drying efficiency is higher; but in the slow-drying drying stage, since the drying rate mainly depends on the migration rate of moisture inside the material, if the technical scheme of CN101581533A is continued, due to the wet material The state of motion has little effect on the rate of dehydration. At the same time, the materials to be dried such as lignite are maintained in a "fluidized" state through higher energy consumption, resulting in a problem of high energy consumption per unit of production.

Therefore, from the perspective of safety, economy and efficiency of the drying method, it is necessary to design a new drying equipment and drying method for the drying characteristics of wet materials such as lignite, so that the wet materials are dried at a constant speed. Efficient and rapid water removal in the stage, and low-energy deep dewatering in the slow-down drying stage to reduce the energy consumption per unit of production.

Summary of the invention

The object of the present invention is to overcome the deficiencies of the prior art described above, and to provide a drying apparatus and a drying method, which combines the characteristics of the drying process of most wet materials into a constant-speed drying and a slow-down drying stage, and adopts fluidized movement. The bed dryer is divided into a constant-speed dry fluidized bed section and a reduced-speed dry moving bed section. The constant-speed dry fluidized bed section wets the wet material to a critical moisture content in a fluidized form, and then slows down the moving bed section. Deeply dewatering wet materials to low moisture products in a more energy efficient manner.

To achieve the above object, the drying apparatus of the present invention is designed such that:

A drying apparatus comprising: a sequentially connected feeder, a fluidized moving bed dryer, a discharger, the fluidized moving bed dryer comprising a constant speed dry fluidized bed section and a reduced speed drying moving bed section, The feeder is connected to the constant-speed dry fluidized bed section, the slow-moving dry moving bed section is connected to the unloader; the constant-speed dry fluidized bed section and the deceleration drying movement At least one set of heat exchangers for heating the materials are respectively disposed in the bed section; a flow rate and pressure for adjusting the flow rate and pressure of the fluidizing gas are arranged between the constant-speed dry fluidized bed section and the deceleration drying moving bed section. A gas distributor through which the fluidizing gas enters the constant velocity dry fluidized bed section.

In a preferred embodiment, the drying device is provided with at least a primary dust collector, the dust collector is connected to an upper portion of the drying device, and the waste heat steam generated by the constant-speed dry fluidized bed section and the reduced-speed dry moving bed section is After the dust collector is dedusted, a part of the waste heat steam is returned to the gas distributor through a circulating pressurizing device, and a part of the waste heat is taken out of the system.

In a preferred embodiment, the dust remover is one or more of a series combination of a cyclone, a baghouse, an electrostatic precipitator, and a wet scrubber.

In a preferred embodiment, a material looser for loosening the material in the bed is provided between the deceleration drying moving bed section and the unloader, and the material looser makes saturated or superheated steam or nitrogen or other inert gas. The low-speed drying moving bed section is entered by means of pulsed air inflow, and the material layer in the moving bed section is moved from bottom to top through the dryer to play the role of loosening the material in the moving bed section of the dryer.

In a preferred embodiment, the heat exchanger provides a heat source from saturated or superheated steam, and the heat exchanger is connected to the boiler feed water system or its equipment. After the heat exchange, the condensed water generated in the heat exchanger flows to the boiler feed water system. Or use it according to the process requirements.

In a preferred embodiment, the feeder is disposed at an upper portion of the drying device, the reduced-speed drying moving bed segment is disposed under the constant-speed dry fluidized bed section, and the unloader is disposed at a bottom of the drying device The material to be dried is moved from top to bottom by gravity.

As a preferred embodiment, the moisture content of the wet material after drying in the constant-speed dry fluidized bed section has a certain upper or lower offset of its critical water content or its critical water content, and the offset range is 20% of its critical moisture content. Within.

In a preferred embodiment, the lower portion of the reduced-speed drying moving bed section is provided with a pipeline through saturated or superheated steam or nitrogen or wet material moisture or inert gas for system shutdown, emergency treatment or fluidization adjustment. Move the internal temperature of the bed dryer.

The drying method of the present invention comprises the following steps:

Step A, the wet material to be dried enters the fluidized moving bed dryer through the feeder;

Step B, feeding the steam heat source into the heat exchanger in the constant-speed dry fluidized bed section of the fluidized moving bed dryer, and the heat exchanger in the slow-moving moving bed section;

In step C, the fluidized gas is sent into the fluidized moving bed dryer, and the wet material particles are in a fluidized state and indirect heat exchange with the steam in the heat exchanger in the constant-speed drying fluidized bed section, and the wet material is controlled. The residence time of the particles in the constant-speed dry fluidized bed section, and when the wet material is dried to approach the critical moisture content, enter the deceleration drying moving bed section and continue to dry;

Step D, the wet material particles entering the reduced-speed drying moving bed section continue to exchange heat with the steam in the heat exchanger, and are dried to the product satisfying the required moisture;

In step E, the product is discharged from the drying device by the unloader.

It will be understood by those skilled in the art that the steam fed to the heat exchanger in the constant-speed dry fluidized bed section in the step B is 0.01-10 MPa (G) of saturated or superheated steam, and is sent to the reduced-speed dry moving bed section. The steam of the heat exchanger is 0.01-10 MPa (G) of saturated or superheated steam.

Those skilled in the art can understand that the pulsed gas in the step D first passes through the material looser, so that saturated or superheated steam or nitrogen or other inert gas enters the slow-moving and moving moving bed section by pulsed air inlet. Loose material helps the material fall.

It will be understood by those skilled in the art that in step C, the frequency of the frequency converter of the circulating pressurizing device is adjusted or the valve on the air outlet of the circulating pressurizing device is adjusted to control the amount of circulating fluidizing gas entering the constant-speed dry fluidized bed section. Ensure that the material in the constant-speed dry fluidized bed section is stable Fluidization.

The beneficial effects of the drying apparatus and drying method of the present invention are:

1) After the drying equipment is divided into constant-speed drying bed section and deceleration drying bed section, compared with the simple internal heating fluidized bed dryer, the single-machine processing capacity is larger, the power consumption is lower, and the energy saving effect is remarkable.

2) The whole superheated steam drying process is an oxygen-free environment, safe and reliable, continuous operation, and can be seamlessly connected with the supporting process of the original power plant.

DRAWINGS

Figure 1 is a schematic view of the structure of the present invention.

detailed description

The invention will now be further described with reference to the drawings and embodiments.

Referring to Figure 1, the drying apparatus 1 of the present invention comprises: a sequentially connected feeder 10, a fluidized moving bed dryer 12, and a discharger 14. The feeder 10 is disposed at an upper portion of the drying apparatus 1, and the unloader 14 is disposed at the bottom of the drying apparatus 1 to facilitate movement of the material to be dried from top to bottom by gravity.

The fluidized moving bed dryer 12 includes a constant speed dry fluidized bed section 120 and a reduced speed dry moving bed section 122, and the reduced speed dry moving bed section 122 is disposed below the constant speed dry fluidized bed section 120. The feeder 10 is connected to the constant-speed dry fluidized bed section 120, and the slow-drying moving moving bed section 122 is connected to the unloader 14.

At least one set of heat exchangers 124 for heating the materials is disposed in the constant-speed dry fluidized bed section 120 and the reduced-speed dry moving bed section 122, respectively. The heat exchanger 124 is provided with a heat source by steam, and the branch connecting the heat source inlet of each set of heat exchangers can determine whether there is a device for adjusting parameters such as steam flow, pressure or temperature according to design requirements, and the heat exchanger 124 and The boiler feed water system of the drying equipment 1 is connected to it or connected by equipment. After heat exchange, the condensed water generated in the heat exchanger 124 flows to the boiler feed water system or according to the process requirements, and the branches or branches of the condensed water generated by each group of the heat exchangers 124 are discharged. The main pipe can be arbitrarily set according to the design requirements, such as a trap group.

Between the constant-speed dry fluidized bed section 120 and the reduced-speed dry moving bed section 122 A gas distributor 1200 for regulating the flow rate and pressure of the fluidizing gas, through which the fluidizing gas enters the constant-speed dry fluidized bed section 120.

Preferably, the drying device further includes a dust remover 11, a circulating pressurizing device 13, and an air guiding device 15. Those skilled in the art can understand that the dust remover 11 can be one level or multiple stages. The upper portion of the fluidized moving bed dryer 12 is connected to a dust remover 11 (preferably a first stage dust remover), and the dust remover 11 (preferably a final stage dust remover) is also connected to the circulating pressurizing device 13 and the air introducing device 15, respectively. The waste heat steam generated by the constant-speed dry fluidized bed section 120 and the reduced-speed dry moving bed section 122 is dusted by the dust remover 11, and a part is returned to the gas distributor 1200 through the circulating pressurizing device 13, and a part of the waste heat is returned to the gas distributor 1200. The wind unit 15 leads to the system. The dust remover 11 may be one or a combination of one or more of a cyclone, a baghouse, an electrostatic precipitator, and a wet scrubber.

Preferably, a material loosening device 1220 for loosening the material in the bed is provided between the deceleration drying moving bed section 122 and the unloader 14, and the material loosening device 1220 makes saturated or superheated steam or nitrogen or other The inert gas enters the deceleration drying moving bed section 122 in a pulsed air inlet manner, and passes through the material layer in the deceleration drying moving bed section 122 from bottom to top to loosen the deceleration drying moving bed. The role of the material in segment 122.

Preferably, a lower portion of the reduced-speed drying moving bed section is provided with a pipeline 1221 that is saturated or superheated with steam or nitrogen or wet material moisture or inert gas for system shutdown, emergency processing or adjustment of fluidized movement. Bed dryer internal temperature.

The drying method of the present invention is:

The drying method of the present invention divides the fluidized moving bed dryer 12 into different bed sections by controlling the residence time of the wet material in different bed sections (the wet material is dried in a constant speed dry fluidized bed section 120 close to critical) The amount of water, if it happens to be its critical water content or up and down within 20% of its critical moisture content, then enters the deceleration drying moving bed section 122 to continue drying), and the product that is finally dried to acceptable moisture is discharged through the unloader 14 Equipment 1, the moisture of the wet material removed in the process is in the form of waste heat steam, which is discharged from the upper part of the drying equipment 1 in the state of superheated steam, and is divided into two paths after dust removal, one way is taken out by the air guiding device 15, and the other is cyclically pressurized. The device 13 returns to the gas distributor 1200 of the constant velocity dry fluidized bed section 120. In addition to providing a small amount of heat, the waste heat steam will mainly enter the wet material flow state in the constant-speed dry fluidized bed section 120 as a fluidizing gas. In the fluidized state, the wet material is indirectly exchanged with the steam in the heat exchanger 124 of the constant-speed drying fluidized bed section 120, and the wet time is controlled by controlling the residence time of the wet material in the fluidized bed section of the dryer. It is dried close to the critical moisture content, such as just within its critical water content or up and down within 20% of its critical moisture content, and then enters the reduced speed drying moving bed section 122 to continue drying. In this process, by adjusting the frequency of the frequency converter of the circulating pressurizing device 13 (the valve on the air outlet of the pressurizing device can be adjusted when the circulating pressurizing device is not equipped with the frequency converter), the control enters the constant-speed dry fluidized bed. The amount of waste heat steam in section 120 is such that the amount of waste heat steam is always maintained within the fluidized bed operating range, thereby ensuring that the material in the constant-speed dry fluidized bed section 120 maintains a stable fluidization; entering the reduced-speed drying moving bed section 122 The wet material therein continues to indirectly exchange heat with the steam in the bed-integrated heat exchanger 124, and is finally discharged to the bottom of the drying apparatus 1 by the unloader 14 after being dried to the qualified moisture required by the product.

During this process, saturated or superheated steam or nitrogen or wet material moisture or inert gas is introduced into the pipeline 1221 provided in the lower part of the slow-moving moving moving bed section for system shutdown, emergency treatment or adjustment. Fluidized moving bed dryer internal temperature.

During this process, when the material processed by the drying device is not conducive to moving and blanking in the slow-moving moving moving bed segment 122, the material loosening device is used to loosen the material in the bed of the reduced-speed drying moving bed segment 122, which will be saturated or overheated. After the steam or nitrogen or other inert gas passes through the material loosener 1220, it enters the slow-drying moving moving bed section 122 by pulsed air, and passes through the material of the slow-moving moving moving bed section 122 from bottom to top, pulse gas. In addition to providing a small amount of heat, it mainly serves to loosen and slow down the material in the moving bed section 122 and take away the moisture.

The following is an example of selecting lignite from the material to be dried:

The lignite raw coal containing 30%-60% of water is crushed and sieved to form lignite particles having a particle diameter of less than 6 mm, and the lignite particles are fed into the feeder 10 and then sent to the fluidized moving bed dryer 12 through the feeder 10. a 0.01-10 MPa (G) saturated or superheated steam heat source is fed into the heat exchanger 124 in the constant-speed dry fluidized bed section 120, and a 0.01-10 MPa (G) saturated or superheated steam heat source is sent to the reduced speed drying. The heat exchanger 124 of the moving bed section 122, the branch connecting the steam inlet of each set of heat exchangers 124 can be determined according to design requirements whether there is a device for adjusting parameters such as steam flow, pressure or temperature, and the heat exchanger 124 and the drying device 1 External boiler feed water system or it is connected by equipment. After heat exchange, the condensed water generated in the heat exchanger 124 flows to the boiler feed water system or According to the process requirements, the branches of the condensed water generated by each group of heat exchangers 124 or the manifolds of the branches can be arbitrarily set according to design requirements, such as a trap group. Waste heat steam from the circulating pressurizing device 13 in a superheated steam state is passed into a gas distributor 1200 between the constant-speed dry fluidized bed section 120 and the decelerating dry moving bed section 122, the waste heat steam being provided In addition to a small amount of heat, the constant velocity dry fluidized bed section 120, which primarily enters the fluidized moving bed dryer 12 as a fluidizing medium, maintains fluidization of the wet material entering the constant velocity dry fluidized bed section. The wet lignite particles in the constant-speed dry fluidized bed section 120 are indirectly exchanged with the steam in the heat exchanger 124 in a fluidized state by controlling the wet lignite particles in the constant-speed dry fluidized bed section 120. The residence time, the wet material is dried close to the critical water content. For different types of lignite with a critical moisture content of about 12%-15% of the water weight, the wet lignite particles can be just placed in the constant-speed dry fluidized bed section 120. Drying from the initial moisture content to its critical moisture content, that is, the weight ratio of water is about 12%-15%, or drying to the upper and lower offset within 20% of its critical moisture content, that is, the weight of water accounts for about 9%-18%, then Entering the deceleration drying moving bed section 122 to continue drying, in the process, by adjusting the frequency of the frequency converter of the circulating pressurizing device 13 (when the circulating pressurizing device 13 is not equipped with an inverter, the circulating pressurizing device 13 can be adjusted The valve on the air line) controls the amount of waste heat steam entering the constant-speed dry fluidized bed section 120, thereby ensuring that the material in the constant-speed dry fluidized bed section 120 maintains a stable fluidization; entering the reduced-speed drying moving bed section Within 122 Coal particles continue to achieve indirect heat exchange with steam in heat exchanger 124, finally dried to meet process requirements such as the weight of water accounted for 3% -5% of lignite qualified product, drying and then discharged by the discharge device 14. During this process, saturated or superheated steam or nitrogen or wet material moisture or inert gas is introduced into the pipeline 1221 provided in the lower portion of the slow-moving moving moving bed section 122 for system shutdown, emergency treatment or The internal temperature of the fluidized moving bed dryer 12 is adjusted, such as when the wet lignite particles are fed into the fluidized moving bed dryer 12 through the feeder 10 at the initial start of the system, to the fluidized moving bed dryer 12 via line 1221. The internal air in the fluidized moving bed dryer 12 is displaced into the system by passing saturated or superheated steam or nitrogen or an inert gas to obtain an oxygen-free drying environment to prevent the lignite particles fed into the fluidized moving bed dryer 12. Self-ignition or explosion or chemical reaction occurs; or when the system is shut down or in emergency conditions, saturated or superheated steam or nitrogen or inert gas is introduced through line 1221 to maintain the oxygen-free environment inside the fluidized moving bed dryer 12 Preventing lignite particles in the fluidized moving bed dryer 12 from spontaneous combustion or Explosion or chemical reaction, or adjust the internal temperature of the fluidized moving bed dryer 12 according to the process requirements, to avoid material decomposition or denaturation during the drying process when drying some heat sensitive materials. In the process, in order to make the lignite particles move smoothly in the slow-moving moving moving bed section 122, the material-dissolving moving bed section 122 is provided with a material loosening device 1220, saturated or superheated steam or nitrogen or other inert gas. The material looser enters the deceleration drying moving bed section 122 by pulsed air inlet, and the saturated or superheated steam or nitrogen or other inert gas passes through the material in the slowing drying moving bed section 122 from bottom to top. In addition to providing a small amount of heat, it mainly serves to loosen the material in the slow-moving moving bed section 122 and take away the moisture.

The steam formed by the fluidized gas, the loose gas, and the moisture removed by the lignite particles together form waste heat steam, which is discharged from the upper portion of the drying device 1 in a superheated steam state, and is removed by the dust remover 11 and then passed through the circulating pressurizing device 13 Returning to the gas distributor 1200 of the constant velocity dry fluidized bed section 120, the other path is led out of the system via the air guiding means 15. The steam in the heat exchanger 124 built in the drying device 1 is condensed water generated by indirect heat exchange to the boiler feed water system or used according to the process requirements.

The above description of the specific embodiments of the present invention has been described with reference to the accompanying drawings, but it is not intended to limit the scope of the present invention. Those skilled in the art should understand that the skilled in the art does not require the creative work on the basis of the technical solutions of the present invention. Various modifications or variations that can be made are still within the scope of the invention.

Claims

A drying apparatus comprising: a sequentially connected feeder, a fluidized moving bed dryer, and a discharger, characterized in that:

The fluidized moving bed dryer comprises a constant-speed dry fluidized bed section and a reduced-speed dry moving bed section, and the feeder is connected to the constant-speed dry fluidized bed section, and the reduced-speed drying moving bed section and The unloader is connected;

The heat exchangers for heating the materials are respectively disposed in the constant-speed dry fluidized bed section and the deceleration drying moving bed section;

A gas distributor for regulating the flow rate and pressure of the fluidizing gas is disposed between the constant-speed dry fluidized bed section and the decelerating dry moving bed section, and the fluidizing gas enters the constant velocity through the gas distributor Dry fluidized bed section.
A drying apparatus according to claim 1, wherein said drying device is provided with at least a primary dust collector, said dust collector being connected to an upper portion of said drying device, said constant-speed dry fluidized bed section and a reduced-speed drying movement After the waste heat steam generated in the bed section is dusted by the dust remover, a part of the waste heat steam is returned to the gas distributor through a circulating pressurizing device, and a part of the waste heat is taken out.
The drying apparatus according to claim 2, wherein the dust remover is one or more of a series combination of a cyclone, a baghouse, an electrostatic precipitator, and a wet scrubber.
The drying apparatus according to any one of claims 1 to 3, wherein a material loosener for loosening the material in the bed is disposed between the deceleration drying moving bed section and the unloader, The material looser causes saturated or superheated steam or nitrogen or other inert gas to enter the deceleration drying moving bed section by pulsed air inlet, and moves the material layer in the moving bed section from bottom to top through the dryer to loosen The role of materials in the dryer.
A drying apparatus according to claim 1, wherein said heat exchanger supplies a heat source from saturated or superheated steam, said heat exchanger being connected to a boiler feed water system or its equipment, and after heat exchange, the heat exchanger The internally generated condensate flows to the boiler feed water system or it is used according to the process requirements.
A drying apparatus according to claim 1, wherein said feeder is disposed at an upper portion of said drying device, and said reduced-speed drying moving bed portion is disposed under said constant-speed dry fluidized bed section, said The unloader is placed at the bottom of the drying device to facilitate the movement of the material to be dried from top to bottom by gravity.
The drying apparatus according to claim 1, wherein the moisture content of the wet material after drying in the constant-speed dry fluidized bed section is a critical water content or a certain upper and lower offset with respect to its critical water content, offset The range is within 20% of its critical moisture content.
A drying apparatus according to claim 1, wherein said lower portion of said slow-moving moving moving bed section is provided with a line for passing saturated or superheated steam or nitrogen or wet material moisture or inert gas for system opening and stopping. , emergency treatment or adjustment of the internal temperature of the fluidized moving bed dryer.
A drying method comprising the following steps:

Step A, the wet material to be dried enters the fluidized moving bed dryer through the feeder;

Step B, feeding the steam heat source into the heat exchanger in the constant-speed dry fluidized bed section of the fluidized moving bed dryer, and the heat exchanger in the slow-moving moving bed section;

In step C, the fluidized gas is sent into the fluidized moving bed dryer, and the wet material particles are in a fluidized state and indirect heat exchange with the steam in the heat exchanger in the constant-speed drying fluidized bed section, and the wet material is controlled. The residence time of the particles in the constant-speed dry fluidized bed section, and when the wet material is dried to approach the critical moisture content, enter the deceleration drying moving bed section and continue to dry;

Step D, the wet material particles entering the reduced-speed drying moving bed section continue to exchange heat with the steam in the heat exchanger, and are dried to the product satisfying the required moisture;

In step E, the product is discharged from the drying device by the unloader.
The drying method according to claim 9, wherein the steam fed to the heat exchanger in the constant-speed dry fluidized bed section in the step B is 0.01-10 MPa (G) of saturated or superheated steam, which is fed. The steam in the heat exchanger in the reduced-speed drying moving bed section is 0.01-10 MPa (G) of saturated or superheated steam.
The drying method according to claim 9, wherein the saturated or superheated steam or nitrogen or other inert gas in the step D is first passed through a material looser to make looseness. The gas enters the slow-moving and moving moving bed section by means of pulsed air inlet, and plays a role of loosening the material to help the material fall.
The drying method according to claim 9, wherein in the step C, the frequency of the frequency converter of the circulating pressure device is adjusted or the valve on the air outlet of the circulating pressure device is adjusted to control the flow into the constant-speed dry fluidized bed section. The amount of circulating fluidized gas ensures that the material in the constant-speed dry fluidized bed section maintains a stable fluidization.