CN104764300B - Heat power fluidization evaporating separation device and technique - Google Patents
Heat power fluidization evaporating separation device and technique Download PDFInfo
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- 238000005243 fluidization Methods 0.000 title claims abstract description 53
- 238000001704 evaporation Methods 0.000 title claims abstract description 48
- 238000000926 separation method Methods 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title abstract description 19
- 230000008020 evaporation Effects 0.000 claims abstract description 43
- 239000002245 particle Substances 0.000 claims abstract description 22
- 239000000463 material Substances 0.000 claims description 157
- 239000000428 dust Substances 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 16
- 238000004364 calculation method Methods 0.000 claims description 8
- 239000013590 bulk material Substances 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 15
- 239000011343 solid material Substances 0.000 abstract 2
- 238000004134 energy conservation Methods 0.000 abstract 1
- 239000012530 fluid Substances 0.000 abstract 1
- 238000001035 drying Methods 0.000 description 16
- 239000007789 gas Substances 0.000 description 14
- 238000012546 transfer Methods 0.000 description 14
- 238000010438 heat treatment Methods 0.000 description 7
- 239000003077 lignite Substances 0.000 description 7
- 238000013461 design Methods 0.000 description 6
- 238000005265 energy consumption Methods 0.000 description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000003889 chemical engineering Methods 0.000 description 2
- 238000007791 dehumidification Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
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- 230000007547 defect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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Abstract
Heat power fluidization evaporating separation device and technique, including evaporator, the heat exchanger being arranged on the evaporator and the heat source being connected with the heat exchanger, it is characterised in that：The wet solid material for meeting certain particle size requirement enters in the evaporator, by with heat transferring medium indirect heat exchange in the heat exchanger, hygroscopic water in wet stock is evaporated, it is detached from wet solid material in the form of a vapor, generate secondary steam, the secondary steam of generation overflows from bottom to top inside the evaporator, reaches a certain critical bed height hmfWhen, secondary steam is in the critical bed height hmfPlace, which reaches, makes the fluidised minimum fluidization velocity u of top bed wet stockmf, with this critical bed height hmfFor separation, top bed is fluid bed section, and wet stock is in fluidized state, and lower part bed is moving bed section, and bed wet stock is in moving bed state.For the present invention in entirely evaporation separation process, system does not need external impetus input, can be achieved with the fluidization of bed wet stock, process energy conservation, efficiently.
Description
Technical Field
The invention relates to a thermodynamic fluidization evaporation separation device for separating moisture in wet materials, and also relates to a thermodynamic fluidization evaporation separation process.
Background
In industrial production, moisture content in various high-moisture materials needs to be reduced to a low moisture content, and taking lignite as an example, lignite with initial moisture of 30% -60% is often required to be dried to a lignite product with final moisture of 3% -5% no matter combustion, transportation or to meet the process requirements of coal chemical industry.
The conventional equipment and method for drying high-humidity materials adopts the following steps: A) the hot flue gas is used as a heat source to directly heat the materials, or B) the hot steam is used as a heat source to indirectly heat the materials. The former is influenced by high material volatile matter or air inlet temperature, so that the material with low ignition point (such as lignite) is easy to ignite and burn, and has potential safety hazard; the latter adopts indirect heating, the heat value of the steam is high, and the process is safe and reliable.
However, due to most wet materials, such as lignite and the like, the drying process is divided into two stages, namely a constant-speed drying stage and a deceleration drying stage. When the technical scheme of CN101581533A is adopted in the constant-speed drying stage, the wet material has higher drying efficiency; however, in the deceleration drying stage, since the drying rate mainly depends on the migration rate of moisture in the material, if the technical scheme of CN101581533A is continued, the dehydration rate is not greatly affected by the motion state of the wet material, and the material to be dried, such as brown coal, is maintained under the "fluidized" state by higher energy consumption, which causes a problem of higher energy consumption per unit of product.
Therefore, from the viewpoint of safety, economy and high efficiency of the drying method, it is necessary to design a new moisture separation apparatus and a new separation method for the drying characteristics of wet materials such as brown coal, so as to achieve efficient and rapid dehumidification of the wet materials in a constant-speed drying stage and low-energy-consumption deep dehumidification in a reduced-speed drying stage, thereby reducing the energy consumption of the product per unit of production.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art and provide an energy-saving and high-efficiency thermodynamic fluidization evaporation separation device and process.
The invention provides a thermal power fluidization evaporation separation device, which comprises evaporationThe solid wet material meeting certain granularity requirement enters the evaporator, the moisture in the wet material is evaporated through indirect heat exchange with a heat exchange medium in the heat exchanger and is separated from the solid wet material in a gaseous state to generate secondary steam, and the generated secondary steam overflows from the inside of the evaporator from bottom to top and reaches a certain critical bed height hmfWhile the secondary steam is at the critical bed height hmfAt a minimum fluidization velocity u for fluidizing wet material in the upper bedmfThe critical bed height hmfThe upper bed layer is a fluidized bed section as a boundary point, wet materials are in a fluidized state, the lower bed layer is a moving bed section, and the wet materials in the bed layer are in a moving bed state.
The thermodynamic fluidization evaporation separation device provided by the invention also has the following auxiliary technical characteristics:
preferably comprising the height of the bed in the moving bed section of the evaporator, i.e.the critical bed height hmf：
Wherein,
m′moisture content＝ρQi (Qi)VQi (Qi)＝ρQi (Qi)uExercise and control deviceACutting block
In the formula mMoving deviceMaterial throughput in kg/h in the moving bed section of the evaporator
Tau-residence time of wet material in moving bed section of evaporator, unit h
ρbBulk Material Density in kg/m3
ACutting block-steamingThe cross section area of the bed layer of the moving section of the hair cutter is m2
MMoisture content' - - -the amount of moisture separated by evaporation in the moving bed section of the evaporator, in kg/h
Omega 1- -initial moisture content (wet basis) of wet material entering moving bed section of evaporator in kg/kg wet material
ω2The final moisture content of the wet material (wet basis) in kg/kg wet material
ρQi (Qi)Density of vapour separated by evaporation in the moving bed section of the evaporator, in kg/m3
VQi (Qi)The amount of vapour separated by evaporation in the moving bed section of the evaporator, in m3/h
uExercise and control deviceOperating gas velocity in m/s in the fluidized bed section of the evaporator.
Preferably comprising an evaporator fluidized bed section operating gas velocity uExercise and control device：
uExercise and control device＝kumf
In the formula, k is an engineering empirical constant, because the evaporator is a self-heating power fluidization evaporation separation device, no external power input exists, when the operating gas velocity reaches the minimum fluidization velocity, the material on the upper bed layer starts to fluidize, the value of k is 1,
umfthe minimum fluidization velocity is m/s, and can be obtained through theoretical calculation or experiment, and the detailed calculation process can be described in the relevant data of chemical engineering handbook and the like.
Preferably, the evaporator is further connected with a dust removal device, and the dust removal device is one or a combination of a cyclone dust collector, a bag-type dust collector, an electrostatic dust collector and a wet dust collector.
Preferably, the evaporator is provided with a heat exchanger, the heat exchanger is one or a combination of a built-in heat exchanger, a jacketed heat exchanger and a coil heat exchanger, and when the evaporator is provided with the built-in heat exchanger, at least one group of built-in heat exchangers is arranged.
Preferably the profile comprising the evaporator is plumb.
The invention provides a thermal power fluidization evaporation separation process, which comprises the following steps
A, crushing wet materials to be dried into solid particles with certain particle sizes, and then feeding the solid particles into an evaporator through a feeder;
step B, the wet material indirectly exchanges heat with a heat exchange medium in a heat exchanger on the evaporator, the moisture in the wet material is evaporated and is separated from the solid wet material in a gaseous state to generate secondary steam, and the generated secondary steam overflows from the inside of the evaporator from bottom to top and reaches a certain critical bed height hmfWhile the secondary steam is at the critical bed height hmfAt a minimum fluidization velocity u for fluidizing wet material in the upper bedmfThe critical bed height hmfThe upper bed layer is a fluidized bed section, the wet material is in a fluidized state, the lower bed layer is a moving bed section, and the wet material in the bed layer is in a moving bed state;
step C, evaporating and separating the wet material through a naturally formed fluidized bed section and a moving bed section to obtain a product with the moisture content meeting the requirement;
and D, discharging the product out of the evaporator through a discharger.
The thermal power fluidization evaporation separation process provided by the invention also has the following auxiliary technical characteristics:
preferably including the evaporator moving bed section bed height, i.e., the critical bed height hmf:
wherein,
m′moisture content＝ρQi (Qi)VQi (Qi)＝ρQi (Qi)uExercise and control deviceACutting block
In the formula mMoving deviceMaterial throughput in kg/h in the moving bed section of the evaporator
Tau-residence time of wet material in moving bed section of evaporator, unit h
ρbBulk Material Density in kg/m3
ACutting blockCross-sectional area of the bed in the moving bed section of the evaporator, in m2
mMoisture content' - - -the amount of moisture separated by evaporation in the moving bed section of the evaporator, in kg/h
ω1The initial moisture content (wet basis) of the wet material entering the moving bed section of the evaporator in kg/kg wet material
ω2The final moisture content of the wet material (wet basis) in kg/kg wet material
ρQi (Qi)Density of vapour separated by evaporation in the moving bed section of the evaporator, in kg/m3
VQi (Qi)The amount of vapour separated by evaporation in the moving bed section of the evaporator, in m3/h
uExercise and control deviceOperating gas velocity in m/s in the fluidized bed section of the evaporator.
Preferably comprising an evaporator fluidized bed section operating gas velocity uExercise and control device：
uExercise and control device＝kumf
And k-is an engineering empirical constant, and since the evaporator is a self-heating power fluidization evaporation separation device, no external power is input, when the operating gas velocity reaches the minimum fluidization velocity, the material on the upper bed layer starts to fluidize, and the value of k is 1.
umfThe minimum fluidization velocity is m/s, and can be obtained through theoretical calculation or experiment, and the detailed calculation process can be described in the relevant data of chemical engineering handbook and the like.
Compared with the prior art, the thermodynamic fluidization evaporation separation device and the process provided by the invention have the following advantages: in the whole evaporation separation process, the system does not need external power input, phase change is carried out through heat transfer and mass transfer, moisture in the wet materials is evaporated and separated to form steam, a driving force with a certain pressure gradient is generated, the evaporated and separated gas passes through the materials of a bed layer in a moving bed section of an evaporator from bottom to top, the gas amount evaporated and separated is continuously increased along with the increase of the height of the bed layer, the generated driving force is correspondingly and continuously increased, when the autogenous thermal power reaches a certain value, the drag force of the gas to upper particles is increased to be equal to the net weight of the particles, and the height h of the critical bed layer is enabled to be equal to the net weight h of the particlesmfThe bed material fluidization greatly enhances the heat transfer and mass transfer coefficients between the bed material and the heat exchanger at the fluidized bed section, realizes the fluidization of the bed material without consuming external power, and has energy-saving and high-efficiency process.
Drawings
FIG. 1 is a schematic diagram of the system architecture of the present invention.
Fig. 2 is a schematic height of the inventive bed.
Detailed Description
Referring to fig. 1, the embodiment of the present invention provides a thermodynamic fluidization evaporation separation apparatus, comprising an evaporator 1, a heat exchanger 4 disposed on the evaporator 1, and a heat source connected to the heat exchanger 4, and a wet material separatorThe moisture content is water, the solid wet material which meets the requirement of certain granularity enters the evaporator 1, the moisture in the wet material is evaporated through indirect heat exchange with the heat exchange medium in the heat exchanger 4, the wet material is separated from the solid wet material in a gaseous state to generate secondary steam, and the generated secondary steam overflows from the inside of the evaporator 1 from bottom to top and reaches the height h of a certain critical bed layermfWhile the secondary steam is at the critical bed height hmfAt a minimum fluidization velocity u for fluidizing wet material in the upper bedmfThe critical bed height hmfThe upper bed layer is a fluidized bed section as a boundary point, wet materials are in a fluidized state, the lower bed layer is a moving bed section, and the wet materials in the bed layer are in a moving bed state. The flow velocity of the secondary steam at the uppermost bed of the fluidized bed section is highest, so that fluidization of the wet material with larger specific gravity which is just added can be ensured, the wet material which is just added and the bed material with fluidized upper part are uniformly mixed and fluidized, the heat transfer coefficient and the mass transfer coefficient are high, the secondary steam which is separated by evaporation is continuously used as a fluidizing medium to fluidize the wet material of the upper bed, the power consumption is not needed to provide fluidizing medium gas, and the energy consumption is reduced. Wet materials move from top to bottom in the moving bed section, indirect heat exchange is continuously realized between the wet materials and a heat exchange medium in a heat exchanger 4 on the moving bed section in the downward moving process, moisture in the wet materials is continuously evaporated and separated until the moisture content required by qualified products is reached, the wet materials are discharged out of the evaporator 1, the heat exchange medium is discharged out of the heat exchanger 4 after indirect heat exchange, and secondary steam generated by the system is discharged out of the evaporator 1.
The device provided by the invention realizes the self-heating power fluidization evaporation separation technology which forms a fluidized bed section and a moving bed section in the evaporator by means of self-heating power. The self-heating power is a driving force with a certain pressure gradient generated by phase change of the system through heat transfer and mass transfer without external power input. The moisture to be evaporated and separated contained in the wet material can be water, methanol, ethanol, organic or inorganic acid and the like, and the wet material is generally referred to as wet material and is granular. Taking the example that the moisture contained in the wet material is water, the water is in a gaseous state from the solid wet material after heat exchangeSeparating the materials, reducing the water content in the wet materials, allowing the secondary steam to overflow from bottom to top through gaps among wet material particles in the evaporator, increasing the vapor amount of the secondary steam passing through the unit cross-sectional area of the evaporator with the increase of the bed height of the wet materials, and reaching a certain critical bed height hmfWhen the flow rate of the steam passing through the unit cross-sectional area of the evaporator reaches a certain value, the drag force of the steam on the upper particles is increased to be equal to the net weight of the particles, the particles start to float, the upper layer wet material reaches an initial fluidization state, and the corresponding steam flow rate is the minimum fluidization velocity u for fluidizing the upper bed wet material at the momentmfAs shown in FIG. 2, the critical bed height hmfThe upper bed layer is a fluidized bed section as a boundary point, wet materials are in a fluidized state, the gas empty bed flow rate at the uppermost bed layer is the highest, the newly added wet materials with larger specific gravity can be fluidized, the newly added wet materials and the wet materials on the upper fluidized bed layer are uniformly mixed and fluidized, the heat transfer coefficient and the mass transfer coefficient are high, the evaporated and separated gas is continuously used as a fluidizing medium to fluidize the wet materials on the upper bed layer, the power consumption is not needed to provide fluidizing medium gas, and the energy consumption is reduced; the lower bed layer is a moving bed section, wet materials of the bed layer are in a moving bed state, the wet materials continuously realize indirect heat exchange with heat exchange media in a heat exchanger on the moving bed section of the evaporator in the moving process of the moving bed section, and moisture in the wet materials is continuously evaporated and separated until the moisture of the wet materials is evaporated and reduced to the moisture content required by qualified products.
In the whole evaporation separation process, the system does not need external power input, phase change is generated through heat transfer and mass transfer, moisture in wet materials separated by evaporation forms steam, a driving force with a certain pressure gradient is generated, the steam separated by evaporation passes through bed materials in a moving bed section from bottom to top, the steam separated by evaporation continuously increases along with the rising of the bed height, the generated driving force is correspondingly and continuously increased, when the self-generated thermal power reaches a certain value, the drag force of the steam to upper particles is increased to be equal to the net weight of the particles, and the height h of the critical bed is enabled to be equal to the net weight of the particlesmfThe wet material of the bed layer is fluidized and greatly strengthenedThe heat transfer and mass transfer coefficients in the bed layer of the fluidized bed section are realized, the fluidization of wet materials in the bed layer can be realized without consuming external power, and the process is energy-saving and efficient.
In the above embodiment of the present invention, the evaporator 1 is provided with the feeder 2 at the upper part and the discharger 5 at the lower part, so as to facilitate the inlet and outlet of the wet material. Of course, the evaporator 1 may also be connected with other devices and components, and these structures are adjusted at will as required, which belongs to a mature technology, and the present invention does not describe these peripheral devices again. The main inventive point of the invention is that the wet material is heated to form a fluidized bed section and a moving bed section in the evaporator.
In the present invention, the parameters in the formulas are consistent, and the following definitions are adopted for the parameters in the following examples, which are not described separately. All parameters are defined as:
m0total wet material throughput of evaporator in kg/h
m' -amount of evaporator product material in kg/h
ω0Initial moisture content of the wet material (wet basis) in kg/kg wet material
ω1The initial moisture content (wet basis) of the wet material entering the moving bed section of the evaporator in kg/kg wet material
ω2The final moisture content of the wet material (wet basis) in kg/kg wet material
Q- -Total Heat input to the evaporator in kcal/h
Q' - -heat provided by a heat exchanger on the evaporator, in kcal/h
Q1The amount of heat required to heat the material, in kcal/h
Q2The heat required for the separation of the moisture by evaporation, expressed in kcal/h
QDecrease in the thickness of the steelEvaporator System Heat loss in kcal/h
Tau-residence time of wet material in moving bed section of evaporator, unit h
ρbBulk Material Density in kg/m3
ACutting blockCross-sectional area of the bed in the moving bed section of the evaporator, in m2
k-engineering empirical constant
umfMinimum fluidization velocity in m/s
hmfHeight of bed in moving bed section, i.e. critical bed height, in m
mMoving deviceMaterial throughput in kg/h in the moving bed section of the evaporator
mMoisture contentThe total moisture content of the wet material separated by evaporation in kg/h
mMoisture content' - - -the amount of moisture separated by evaporation in the moving bed section of the evaporator, in kg/h
ρQi (Qi)Density of vapour separated by evaporation in the moving bed section of the evaporator, in kg/m3
VQi (Qi)The amount of vapour separated by evaporation in the moving bed section of the evaporator, in m3/h
uExercise and control device- -operating gas velocity in m/s of the fluidized bed section of the evaporator
h- -total bed height of evaporator, m
u- -speed of gas passing through empty bed unit cross-sectional area of evaporator, m/s
u1The velocity of the gas at the bottom of the evaporator per unit cross-sectional area of the empty bed of the evaporator, m/s
Critical bed height h in the present inventionmfIs made by the smallestFluidization velocity umfTo determine that the secondary steam reaches the minimum fluidization velocity umfThe bed height is the critical bed height hmfTherefore, the dividing position of the fluidized bed section and the moving bed section of the present invention is determined by the above formula, and the setting of the fluidized bed section and the moving bed section can be conveniently realized by adjusting the above parameters. The parameters in the above formula are determined by those skilled in the art according to design requirements and practical experience, and the determined parameters are substituted into the above formula, so that whether the design is reasonable or not and whether the process is complete or not can be conveniently verified. If the design requirement cannot be met or the effect is not good according to the calculation result, the corresponding parameters can be adjusted to meet the requirement.
In the above-described embodiments of the invention, the evaporator 1 is designed for a bed height of the moving bed section, i.e. the critical bed height hmf：
Wherein,
m′moisture content＝ρQi (Qi)VQi (Qi)＝ρQi (Qi)uExercise and control deviceACutting block
The invention can calculate the critical bed height when the material of the bed layer in the evaporator reaches the initial fluidization state through the formula, thereby calculating whether the fluidization requirement can be met.
In the above examples given in this invention, the evaporator fluidized bed section operating gas velocity uExercise and control device：
uExercise and control device＝kumf
In the above embodiment of the present invention, the evaporator 1 is further connected to a dust removing device 3, and the dust removing device 3 is a cyclone dust remover, a bag-type dust remover, or an electrostatic precipitatorOne or more of a dust remover and a wet dust remover. Total height of evaporator 1 of the present invention: less than or equal to 150 m; particle size of the wet material: dpLess than or equal to 60 mm; fluidization velocity range: 0.01-50 m/s; heat source: can be saturated or superheated steam, organic moisture steam, flue gas, heat conduction oil, hot water, molten salt and the like; heat source pressure: p1Less than or equal to 100 Mpa; appearance of evaporator: is plumb; heat exchanger 4 on evaporator 1: when the built-in heat exchanger 4 is provided, at least one group of built-in heat exchangers are arranged; the flow direction of the heat exchange medium stream in the heat exchanger 4 on the evaporator 1 can be arbitrarily determined by a person skilled in the art according to design requirements and practical experience; on the heat source branch connected with the heat exchange medium inlet of the heat exchanger 4 on the evaporator 1, a person skilled in the art can determine whether a device for adjusting parameters such as heat source flow, pressure or temperature is provided according to design requirements and practical experience.
Example, assuming that the evaporator is to evaporate water from a particulate wet material, the amount m of wet material to be treated0300kg/h, initial moisture content omega050% (wet basis), the desired final moisture content after treatment omega29% (wet basis), normal pressure of operation in the evaporator, and operation temperature t2At 110 ℃ and the initial temperature theta of the wet mass1At 25 ℃, specific heat c of product materialm0.3 kcal/(kg. K), bulk density rhobIs 600kg/m3The evaporator is internally provided with a saturated steam heat source with the pressure of 0.5MPa (G) in a heat exchanger, and the latent heat of vaporization r of water02257.6kJ/kg, specific heat capacity of water cwAbout 4.187kJ/(kg water. DEG C.), specific heat capacity c of water vaporvAbout 1.88kJ/(kg steam), the moisture in the wet material is evaporated and separated by indirect heat exchange between a heat exchange medium and the wet material in a built-in heat exchanger on the evaporator, the wet material is sent into the evaporation separator by a feeder 2 and sequentially passes through a fluidized bed section and a moving bed section of the evaporation separator from top to bottom, and after the material reaches the qualified moisture, the product is discharged out of the evaporation separator by a discharger 5. By calculatingObtaining the operating gas velocity u in the bed section of the self-heating power evaporatorExercise and control deviceTo a minimum fluidization velocity umfThe bed height of the corresponding moving section, namely the critical bed height hmf。
In the evaporation separation process, the moisture content of the wet material obtained by evaporation separation is as follows:
product material amount after evaporation and separation:
m′＝m0-mwater (W)＝300-135.16＝164.84kg/h
The evaporator has a system heat balance:
Q＝Q′
wherein, the heat required by the temperature rise of the product materials is as follows:
Q1＝m’cm△t1＝164.84×0.3×(110-25)＝4204kcal/h
the evaporator evaporates and separates the heat required by water content:
Q2＝mwater (W)(r0+1.88t2-4.187θ1)
＝135.16×(2257.6+1.88×110-4.187×25)/4.187
＝76174kcal/h
The system heat loss is 10%, the heat provided by the heat exchanger on the evaporator is as follows:
Q'＝Q＝Q1+Q2+Qdecrease in the thickness of the steel＝(Q1+Q2)×(1+10％)＝(4204+76174)×1.1＝88416kcal/h
It is assumed that for this specification type of wet material, according to engineering experience, a minimum fluidization velocity u is reached in the bed section of the autothermal evaporator to initiate fluidization of the particles of wet materialmfThe evaporator is not input with external power, the initial fluidization state is achieved by the self-generated thermal power of the system, and the operating gas velocity u is takenExercise and control device＝umf0.2 m/s; the residence time tau of the wet material in the moving bed section of the evaporator is closely related to the drying rate, which is usually measured under constant drying conditions due to the complexity of drying, and a drying rate curve similar to the production conditions can be obtained by experiment, and then the residence time tau of the wet material in the moving bed section of the evaporator can be obtained by a graphical method or an approximate calculation, assuming that the residence time tau of the wet material in the moving bed section of the evaporator is 1 h.
The initial moisture content of the wet material entering the moving bed section of the evaporator is approximately equal to the initial moisture content of the wet material, namely omega1＝ω0Not equal to 50% (wet basis)
There is the evaporator moving bed section bed height, i.e. the critical bed height:
the invention provides a thermodynamic fluidization evaporation separation process, which comprises the following steps:
a, crushing wet materials to be dried into solid particles with certain particle sizes, and then feeding the solid particles into an evaporator through a feeder;
step B, the wet material indirectly exchanges heat with a heat exchange medium in a heat exchanger on the evaporator, the moisture in the wet material is evaporated and is separated from the solid wet material in a gaseous state to generate secondary steam, and the generated secondary steam overflows from the inside of the evaporator from bottom to top and reaches a certain critical bed height hmfWhile the secondary steam is at the critical bed height hmfAt a minimum fluidization velocity u for fluidizing wet material in the upper bedmfThe critical bed height hmfThe upper bed layer is a fluidized bed section as a boundary point, wet materials are in a fluidized state, the lower bed layer is a moving bed section, and the wet materials in the bed layer areMoving bed state;
step C, evaporating and separating the wet material through a naturally formed fluidized bed section and a moving bed section to obtain a product with the moisture content meeting the requirement;
and D, discharging the product out of the evaporator through a discharger.
The process embodiments given in this embodiment are the same as the device embodiments and are not described again here. According to the formula, whether the process is reasonable or not can be conveniently verified, so that the separation process can be determined.
Claims (9)
1. The thermodynamic fluidization evaporation separation device comprises an evaporator, a heat exchanger arranged on the evaporator and a heat source connected with the heat exchanger, and is characterized in that: the solid wet material which meets certain granularity requirement enters the evaporator, the moisture in the wet material is evaporated through indirect heat exchange with the heat exchange medium in the heat exchanger, the wet material is separated from the solid wet material in a gaseous state to generate secondary steam, and the generated secondary steam overflows from the inside of the evaporator from bottom to top and reaches a certain critical bed height hmfWhen the secondary steam is at the critical bed heightDegree hmfAt a minimum fluidization velocity u for fluidizing wet material in the upper bedmfThe critical bed height hmfThe upper bed layer is a fluidized bed section as a boundary point, wet materials are in a fluidized state, the lower bed layer is a moving bed section, and the wet materials in the bed layer are in a moving bed state.
2. The thermodynamic fluidization evaporative separation apparatus of claim 1, wherein: the height of the bed at the moving bed section of the evaporator, i.e. the critical bed height hmf：
Wherein,
m′moisture content＝ρQi (Qi)VQi (Qi)＝ρQi (Qi)uExercise and control deviceACutting block
In the formula mMoving deviceMaterial throughput in kg/h in the moving bed section of the evaporator
Tau-residence time of wet material in moving bed section of evaporator, unit h
ρbBulk Material Density in kg/m3
ACutting blockCross-sectional area of the bed in the moving bed section of the evaporator, in m2
mMoisture content' - - -the amount of moisture separated by evaporation in the moving bed section of the evaporator, in kg/h
ω1The initial moisture content of the wet material entering the moving bed section of the evaporator, in kg/kg wet material
ω2The final moisture content of the wet material in kg/kg wet material
ρQi (Qi)Density of vapour separated by evaporation in the moving bed section of the evaporator, in kg/m3
VQi (Qi)The amount of vapour separated by evaporation in the moving bed section of the evaporator, in m3/h
uExercise and control deviceOperating gas velocity in m/s in the fluidized bed section of the evaporator.
3. The thermodynamic fluidization evaporative separation apparatus of claim 2, wherein: operating gas velocity u of evaporator fluidized bed sectionExercise and control device：
uExercise and control device＝kumf
Wherein k-is an engineering empirical constant, when the operating gas velocity reaches the minimum fluidization velocity, the material in the upper bed layer starts to fluidize, the value of k is 1,
umf- -is the minimum fluidization velocity in m/s, which can be obtained by theoretical calculation or experimentally.
4. The thermodynamic fluidization evaporative separation apparatus of claim 1, wherein: the heat exchanger on the evaporator is one or a combination of a built-in heat exchanger, a jacketed heat exchanger and a coil heat exchanger, and when the built-in heat exchanger is provided, at least one group of built-in heat exchangers are arranged.
5. The thermodynamic fluidization evaporative separation apparatus of claim 1, wherein: the evaporator is also connected with a dust removing device which is one or a combination of a cyclone dust collector, a bag-type dust collector, an electrostatic dust collector and a wet dust collector.
6. The thermodynamic fluidization evaporative separation apparatus of claim 1, wherein: the shape of the evaporator is plumb.
7. A thermal power fluidization evaporation separation process is characterized in that: comprises the following steps
A, crushing wet materials to be dried into solid particles with certain particle sizes, and then feeding the solid particles into an evaporator through a feeder;
step B, wet materials are subjected to heat exchange with the heat exchanger on the evaporatorIndirect heat exchange is carried out, moisture in the wet material is evaporated and is separated from the solid wet material in a gaseous state to generate secondary steam, and the generated secondary steam overflows from the inside of the evaporator from bottom to top and reaches a certain critical bed height hmfWhile the secondary steam is at the critical bed height hmfAt a minimum fluidization velocity u for fluidizing wet material in the upper bedmfThe critical bed height hmfThe upper bed layer is a fluidized bed section, the wet material is in a fluidized state, the lower bed layer is a moving bed section, and the wet material in the bed layer is in a moving bed state;
step C, evaporating and separating the wet material through a naturally formed fluidized bed section and a moving bed section to obtain a product with the moisture content meeting the requirement;
and D, discharging the product out of the evaporator through a discharger.
8. The thermodynamic fluidized evaporative separation process of claim 7, wherein: the height of the bed at the moving bed section of the evaporator, i.e. the critical bed height hmf：
Wherein,
m′moisture content＝ρQi (Qi)VQi (Qi)＝ρQi (Qi)uExercise and control deviceACutting block
In the formula mMoving deviceMaterial throughput in kg/h in the moving bed section of the evaporator
Tau-residence time of wet material in moving bed section of evaporator, unit h
ρbBulk Material Density in kg/m3
ACutting blockCross-sectional area of the bed in the moving bed section of the evaporator, in m2
mMoisture content' - - -evaporator moving bed section evaporation separationThe moisture content of (a) is in kg/h
ω1The initial moisture content of the wet material entering the moving bed section of the evaporator, in kg/kg wet material
ω2The final moisture content of the wet material in kg/kg wet material
ρQi (Qi)Density of vapour separated by evaporation in the moving bed section of the evaporator, in kg/m3
VQi (Qi)The amount of vapour separated by evaporation in the moving bed section of the evaporator, in m3/h
uExercise and control deviceOperating gas velocity in m/s in the fluidized bed section of the evaporator.
9. The thermodynamic fluidized evaporative separation process of claim 7, wherein: operating gas velocity u of evaporator fluidized bed sectionExercise and control device：
uExercise and control device＝kumf
And k-is an engineering empirical constant, when the operating gas velocity reaches the minimum fluidization velocity, the material on the upper bed layer starts to fluidize, and the value of k is 1.
umf- -is the minimum fluidization velocity in m/s, which can be obtained by theoretical calculation or experimentally.
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| NL7210255A (en) * | 1971-07-26 | 1973-01-30 | ||
| US3851405A (en) * | 1972-05-11 | 1974-12-03 | Agency Ind Science Techn | Fluidizing device |
| CN201151710Y (en) * | 2007-10-27 | 2008-11-19 | 太原海力丰科技发展有限公司 | Grading coal gasification device |
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