CN112707626A - Sludge drying system and sludge drying method thereof - Google Patents

Sludge drying system and sludge drying method thereof Download PDF

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Publication number
CN112707626A
CN112707626A CN202110014122.6A CN202110014122A CN112707626A CN 112707626 A CN112707626 A CN 112707626A CN 202110014122 A CN202110014122 A CN 202110014122A CN 112707626 A CN112707626 A CN 112707626A
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China
Prior art keywords
sludge
water
air
heat
drying
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CN202110014122.6A
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Inventor
王阳
李继荣
姜雨生
李岳
钱景春
陶能烨
王义春
秦二兰
张大龙
高鹏飞
周晓明
张威
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Beijing Jinyu Beishui Environmental Protection Technology Co ltd
Bbmg Hongshulin Environmental Protection Technology Co ltd
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Beijing Jinyu Beishui Environmental Protection Technology Co ltd
Bbmg Hongshulin Environmental Protection Technology Co ltd
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Priority to CN202110014122.6A priority Critical patent/CN112707626A/en
Publication of CN112707626A publication Critical patent/CN112707626A/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/02—Particle separators, e.g. dust precipitators, having hollow filters made of flexible material
    • B01D46/023—Pockets filters, i.e. multiple bag filters mounted on a common frame
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B30/00—Heat pumps
    • F25B30/02—Heat pumps of the compression type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B30/00—Heat pumps
    • F25B30/06—Heat pumps characterised by the source of low potential heat
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/52—Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Drying Of Solid Materials (AREA)
  • Treatment Of Sludge (AREA)

Abstract

The invention discloses a sludge drying system and a sludge drying method thereof, and relates to the technical field of sludge drying treatment, wherein the sludge drying system comprises a drying chamber and a waste heat recovery heat pump, and air is in closed circulation between the drying chamber and the waste heat recovery heat pump; the drying chamber is provided with an upper air outlet, an upper air return inlet and a lower air return inlet which are communicated with the waste heat recovery heat pump. The sludge drying system combines the heat pump with the heat drying, can improve the partial pressure of water vapor in the drying chamber compared with the pure heat pump technology, thereby improving the drying efficiency, and can improve the condensing efficiency compared with the heat drying, thereby improving the drying efficiency and reducing the volume of a cooling device.

Description

Sludge drying system and sludge drying method thereof
Technical Field
The invention relates to the technical field of sludge drying treatment, in particular to a sludge drying system for drying sludge by using dry-method cement kiln waste heat and a sludge drying method thereof.
Background
According to statistics, China only processes domestic sewage to generate hundreds of millions of tons of sludge every year, and in addition, a large amount of sludge is generated in the production process of the industries such as chemical industry, papermaking, pharmacy and the like and in the dredging engineering of rivers and lakes. Generally, the water content of the sludge is as high as 97%, the sludge is easy to be decomposed and smelly, and contains toxic and harmful substances such as pathogenic bacteria, parasitic ova, heavy metals and the like, and the sludge is a potential secondary pollution source if harmless treatment is not carried out. The sludge treatment aims at reduction, stabilization, harmlessness and resource utilization, avoids secondary pollution of sludge and realizes resource utilization of organic matters.
The common sludge treatment method is to firstly perform mechanical filter pressing and then perform drying, and the drying method is more, such as natural drying, solar drying, thermal drying and the like. Domestic and foreign sludge drying process equipment mainly adopts a heat drying technology, and specifically comprises rotary kiln hot air drying, belt type hot air drying, fluidized bed hot air drying, paddle type drying and the like, and the heat drying has the advantages of high efficiency and compact structure. In addition, the working temperature of the traditional heat drying technology generally needs to be more than 110 ℃, and a great amount of dust and odor generated in the drying process need to be treated by additionally arranging facilities.
In recent years, a low-temperature sludge drying technology utilizing the operating principle of a dehumidifying heat pump is gradually favored, but the evaporation amount of water in sludge is limited while the temperature is reduced in the drying process. At a certain temperature, when the saturated water vapor in the drying chamber reaches a corresponding limit value, the ideal drying effect of the sludge can be achieved only by long enough drying time, so that the power consumption of electric equipment is indirectly increased, and the energy-saving effect is not obvious.
The kiln head cooling residual air of the drying rotary kiln cement production line, the smoke of a kiln tail preheater and the like still contain low heat, the temperature of the smoke passing through the power generation boiler is still as high as about 210 ℃, the smoke is an ideal heat source which can be reused for drying sludge, and the energy cost can be saved. The content of organic matters in the domestic sludge can generally account for 30-40% of the dry weight of the sludge, the heat value of the dry sludge can be comparable to that of lignite, the heat value of part of kinds of industrial sludge is higher, and the domestic sludge can replace part of cement kiln fuel, so that the resource consumption is saved.
The patent with application publication number CN103739184A introduces a method for drying domestic sludge by using the waste heat of a dry-process cement kiln and directly co-firing the domestic sludge, the sludge is firstly mixed with an additive formed by sodium hydroxide, glycerol, diglycolamine, sodium alkyl benzene sulfonate and water, and then pulverized coal and slaked lime are metered and added, and the dried domestic sludge is dried by introducing the waste air at the kiln head of the dry-process cement kiln or flue gas after a power generation boiler into a drying rotary kiln. The method takes the rotary kiln as the drier, has lower efficiency and large floor area; the cost of the additive is high; the sludge and the hydrated lime are mixed to easily cause conveying blockage; the flue gas directly heats the sludge, the temperature is too high, harmful gas is excessively removed, and the tail gas treatment pressure is increased.
Disclosure of Invention
Therefore, the invention provides a sludge drying system and a sludge drying method thereof, and aims to solve the problems of poor energy-saving effect, low drying efficiency, high cost, more harmful gas separation and the like of the conventional sludge drying method.
In order to achieve the above purpose, the invention provides the following technical scheme:
according to a first aspect of the invention, a sludge drying system comprises a drying chamber and a waste heat recovery heat pump, wherein air is in closed circulation between the drying chamber and the waste heat recovery heat pump; and the drying chamber is provided with an upper air outlet, an upper air return inlet and a lower air return inlet which are communicated with the waste heat recovery heat pump.
Furthermore, at least two layers of mesh conveyor belts are arranged in the drying chamber; and a circulating fan and a heater are arranged above the conveyor belt.
Further, the waste heat recovery heat pump comprises a pump shell, wherein a cloth bag filter is arranged in the pump shell, and the cloth bag filter is arranged above the inside of the pump shell.
Furthermore, a heat regenerator, a first condenser, a first water-air heat exchanger, a second condenser, a second water-air heat exchanger, a water-cooled evaporator, an evaporator and a compressor are also arranged in the pump shell.
Further, the sludge drying system also comprises a cooling tower, and the cooling tower is connected with the water-cooling evaporator through a first circulating water pipeline; and a first circulating water pump is installed on the first circulating water pipeline.
Further, the sludge drying system also comprises a flue gas heat exchanger, and the flue gas heat exchanger is in heat exchange connection with the first water-air heat exchanger and the second water-air heat exchanger through a second circulating water pipeline; and a second circulating water pump is installed on the second circulating water pipeline.
According to a second aspect of the present invention, a sludge drying method using the above sludge drying system comprises the following steps:
the sludge is conveyed into the drying chamber through a screw conveyer; the sludge passes through at least two layers of mesh conveyor belts from top to bottom in the drying chamber, hot dry air is introduced below the conveyor belts, and the hot dry air passes through the sludge on the conveyor belts to exchange heat with the sludge and take away moisture in the sludge to form damp and hot air; the damp and hot air is pumped by a circulating fan above the conveyor belt and enters the waste heat recovery heat pump through an upper air outlet of the drying chamber;
the wet hot air entering the waste heat recovery heat pump is filtered by the cloth bag filter to remove dust;
a part of the hot and humid air filtered by the cloth bag filter directly exchanges heat with a first condenser and a first water-air heat exchanger, and then enters the drying chamber through the upper air return inlet for cyclic utilization;
the other part of the damp and hot air filtered by the cloth bag filter is subjected to heat exchange by the heat regenerator, then is subjected to primary cooling by the water-cooled evaporator, is subjected to secondary cooling by the evaporator, is condensed into condensed water to be discharged out of the waste heat recovery heat pump, and dry and cold air formed after cooling is subjected to heat absorption by the compressor, primary heating, secondary heating by the heat regenerator, enters a second water-air heat exchanger for heat exchange, is heated by a second condenser and then enters the drying chamber from the lower air return port for recycling;
water in the water-cooled evaporator enters a cooling tower through a first circulating water pipeline under the action of a first circulating water pump to be cooled and cooled circularly;
and the flue gas discharged by the cement kiln is discharged into the atmosphere after heat exchange by the flue gas heat exchanger, meanwhile, the water temperature in the flue gas heat exchanger rises, and the rising hot water in the flue gas heat exchanger enters the first water-air heat exchanger and the second water-air heat exchanger through a second circulating water pipeline under the action of a second circulating water pump to exchange heat with the dry and cold air in the waste heat recovery heat pump, so that the temperature of the dry and cold air is raised.
Further, the sludge is subjected to simple mechanical dehydration before entering the drying chamber, and the water content of the sludge is 50-85%; the feeding amount of the sludge is 1.8-2.4 t/h; the retention time of the sludge in the drying chamber is 90-150 min; the temperature of the circulating damp-heat air in the drying chamber is kept between 50 and 75 ℃, and the drying temperature of the equipment is between 65 and 85 ℃.
Further, the temperature of the flue gas discharged by the cement kiln is 100-400 ℃, and the flow rate is 10-30 ten thousand Nm3H, relative humidity is less than 6%, and dust content is less than 3mg/m3；
The flue gas discharged by the cement kiln can be waste gas of air-cooled cement clinker, the temperature is 100-130 ℃, and the waste gas is organized discharged through a chimney directly after dust collection by a high-efficiency bag; the flue gas discharged by the cement kiln can be kiln head cooling residual air with the temperature of 360-400 ℃, can also be flue gas from the outlet of a kiln tail preheater separator with the temperature of 340-350 ℃, and can also be flue gas after passing through a power generation boiler with the temperature of 170-250 ℃.
Furthermore, the water content of the dried sludge obtained after drying by the sludge drying system is 10% -40%, and the dried sludge enters a cement kiln for cooperative treatment and can replace part of fuel; the dried tail gas generated by the sludge drying system can enter a cement kiln, and organic matters are removed at high temperature and then enter a cement kiln tail gas treatment system; condensed water generated by an evaporator of the sludge drying system can directly enter a water treatment system of a cement plant, and dry and cold air passing through the evaporator is periodically discharged and introduced into a cement kiln for incineration treatment.
The invention has the following advantages:
the sludge drying system combines the heat pump with the heat drying, can improve the partial pressure of water vapor in the drying chamber compared with the pure heat pump technology, thereby improving the drying efficiency, and can improve the condensing efficiency compared with the heat drying, thereby improving the drying efficiency and reducing the volume of a cooling device.
The sludge drying system is added with a cooling tower as cold source supplement of the waste heat recovery heat pump and a flue gas heat exchanger as heat source supplement of the waste heat recovery heat pump on the basis of the waste heat recovery heat pump.
According to the sludge drying method, the sludge is dried by using the heat in the flue gas discharged by the cement kiln, and the dried sludge partially replaces fuel, so that the volume reduction can reach 67%, the weight reduction can reach 80%, the organic matter is not lost in the drying process, the sludge drying energy consumption is reduced, and the cement production energy consumption is reduced.
The sludge drying method adopts the heat exchange principle to indirectly supply heat through hot flue gas, controls the drying temperature, greatly reduces the precipitation amount of harmful gas, circularly utilizes hot air in the drying chamber, prevents gas generated in the drying process from being mixed into the flue gas of a cement plant to increase the tail gas treatment amount, and also prevents the gas generated in the drying process from escaping into the atmosphere to pollute the environment, thereby being capable of inputting a small amount of organic gas into a cement kiln for disposal.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the functions and purposes of the present invention, should still fall within the scope of the present invention.
Fig. 1 is a schematic structural diagram of a sludge drying system provided in embodiment 1 of the present invention;
fig. 2 is a process flow chart of a sludge drying method provided in embodiment 2 of the present invention.
Detailed Description
The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The sludge drying system shown in fig. 1 comprises a drying chamber 1 and a waste heat recovery heat pump 2, wherein air is in closed circulation between the drying chamber 1 and the waste heat recovery heat pump 2; the drying chamber 1 is provided with an upper air outlet 101, an upper air return inlet 102 and a lower air return inlet 103 which are communicated with the waste heat recovery heat pump 2.
The sludge drying system combines the heat pump with the heat drying, improves the water vapor partial pressure in the drying chamber and the drying efficiency compared with the pure heat pump technology, improves the condensing efficiency and the drying efficiency compared with the heat drying, and reduces the volume of the cooling device at the same time. The sludge drying system recycles hot air in the drying chamber, hot air in the drying chamber 1 enters the waste heat recovery heat pump 2 through the upper air outlet 101 for treatment and temperature rise, and then returns to the drying chamber 1 through the upper air return inlet 102 and the lower air return inlet 103 for drying of sludge, so that gas generated in the drying process is prevented from being mixed into smoke gas of a cement plant to increase tail gas treatment amount, gas generated in the drying process is prevented from being dissipated into atmosphere to pollute the environment, and a small amount of organic gas can be input into a cement kiln for treatment.
Three layers of net-shaped conveyor belts 3 are arranged in the drying chamber 1; and a circulating fan and two heaters 4 are arranged above the conveyor belt 3. Two heaters 4 are respectively arranged above the bottom layer conveyor belt 3 and the middle layer conveyor belt 3, so that temperature change caused by flue gas temperature fluctuation is compensated, and heat guarantee is provided when the flue gas temperature is too low. The damp and hot air is pumped into the waste heat recovery heat pump 2 by the circulating fan.
The waste heat recovery heat pump 2 comprises a pump shell 20, wherein a cloth bag filter 21 is arranged in the pump shell 20, and the cloth bag filter 21 is arranged above the inside of the pump shell 20. The pump casing 20 is also provided therein with a regenerator 22, a first condenser 23, a first water-air heat exchanger 24, a second condenser 25, a second water-air heat exchanger 26, a water-cooled evaporator 27, an evaporator 28 and a compressor 29. The cloth bag filter 21 is used for filtering the hot and humid air entering the waste heat recovery heat pump 2.
A part of the hot and humid air filtered by the cloth bag filter 21 directly exchanges heat with a first condenser 23 and a first water-air heat exchanger 24, and then enters the drying chamber through the upper air return inlet for cyclic utilization; the other part passes through earlier after the heat regenerator 22 heat transfer the first cooling of water-cooled evaporator 27, passes through evaporator 28 secondary cooling (evaporator 28 is the evaporation plant of waste heat recovery heat pump 2, when damp and hot air flows through evaporator 28, the heat that inside low pressure refrigerant absorbed the air is become the gaseous state by liquid, thereby the air cooling makes aqueous vapor wherein condense back and discharge with the form of liquid water, moisture that the cooling back formed is condensed and is discharged for the comdenstion water outside waste heat recovery heat pump 2, the dry cold air that forms after the cooling passes through first the compressor 29 absorbs heat (the inside refrigerant of compression is exothermic, the dry cold air heat absorption) once heaies up the temperature and passes through after regenerator 22 heats the secondary intensification, gets into second water-air heat exchanger 26 heat transfer, then heats through second condenser 25 (the inside refrigerant of second condenser 25 cools off and releases heat, dry and cold air absorbs heat and is heated), and then enters the drying chamber 1 from the lower air return opening 103 for recycling.
The sludge drying system further comprises a cooling tower 5, and the cooling tower 5 is connected with the water-cooled evaporator 27 through a first circulating water pipeline 6; and a first circulating water pump 7 is installed on the first circulating water pipeline 6. The sludge drying system of the invention is added with a water cooling tower 5 as cold source supplement of the waste heat recovery heat pump 2.
The sludge drying system further comprises a flue gas heat exchanger 8, and the flue gas heat exchanger 8 is in heat exchange connection with the first water-air heat exchanger 24 and the second water-air heat exchanger 26 through a second circulating water pipeline 9; and a second circulating water pump 10 is installed on the second circulating water pipeline 9. The sludge drying system of the invention is added with a flue gas heat exchanger 8 as the heat source supplement of the waste heat recovery heat pump 2.
Example 2
A sludge drying method, the process flow of which is shown in fig. 2, wherein the method uses the sludge drying system of embodiment 1, and the method comprises the following steps:
domestic sludge is selected and poured into the material buffer tank, and then lifted into a sludge slitter hopper of the drying chamber 1 through a screw conveyor with a lifting angle of 30 degrees, and the slitter uniformly tiles the sludge to the mesh conveyor belt 3 after slitting pretreatment. Wherein the equipment drying temperature of the drying chamber 1 is 69 ℃.
The sludge passes through the three layers of mesh conveyor belts 3 from top to bottom in the drying chamber 1, hot dry air is introduced below the conveyor belts 3, and the hot dry air passes through the sludge on the conveyor belts 3 to exchange heat with the sludge and take away moisture in the sludge to form damp and hot air; the damp and hot air is pumped by a circulating fan above the conveyor belt and enters the waste heat recovery heat pump 2 through an upper air outlet 101 of the drying chamber 1; wherein the temperature of the circulating damp and hot air in the drying chamber 1 is 50-75 ℃.
The wet hot air entering the waste heat recovery heat pump 2 is filtered by the cloth bag filter 21 to remove dust;
a part of the hot and humid air filtered by the cloth bag filter 21 directly exchanges heat with a first condenser 23 and a first water-air heat exchanger 24, and then enters the drying chamber 1 through the upper air return inlet 102 for cyclic utilization;
the other part of the damp and hot air filtered by the cloth bag filter 21 is subjected to heat exchange by the heat regenerator 22, then is subjected to primary cooling by the water-cooling evaporator 27, is subjected to secondary cooling by the evaporator 28, is condensed into condensed water to be discharged out of the waste heat recovery heat pump 2, and dry and cold air formed after cooling is subjected to heat absorption by the compressor 29, primary heating, secondary heating by the heat regenerator 22, enters the second water-air heat exchanger 26 for heat exchange, is heated by the second condenser 25, and then enters the drying chamber 1 from the lower air return port 103 for recycling;
in the process of carrying out closed circulation on the damp and hot air between the drying chamber 1 and the waste heat recovery heat pump 2, water in the water-cooling evaporator 27 enters the cooling tower 5 through the first circulating water pipeline 6 under the action of the first circulating water pump 7 to carry out circulating cooling and temperature reduction; waste gas of air-cooled cement clinker at the temperature of 113 ℃ (the waste gas is organized emission waste gas which is collected by a high-efficiency bag and directly emitted through a chimney) is discharged into the atmosphere after heat exchange by the flue gas heat exchanger 8, meanwhile, the water temperature of 70 ℃ in the flue gas heat exchanger 8 is raised to 90 ℃, hot water raised in the flue gas heat exchanger 8 enters the first water-air heat exchanger 24 and the second water-air heat exchanger 26 through the second circulating water pipe 9 under the action of the second circulating water pump 10 to exchange heat with dry and cold air in the waste heat recovery heat pump 2, so that the dry and cold air is heated to 60-85 ℃ and returns to the drying chamber 1 for cyclic utilization.
The water content of the dried sludge obtained after drying by the sludge drying system is 22.73 percent, the heat value is 2286kcal/kg, the physical form is stable, the dried sludge is not agglomerated and is easy to store and convey, and then the dried sludge enters a cement kiln for cooperative treatment and can replace part of fuel; the dried tail gas generated by the sludge drying system can enter a cement kiln, and organic matters are removed at high temperature and then enter a cement kiln tail gas treatment system; the condensed water produced by the evaporator 28 of the sludge drying system can directly enter a water treatment system of a cement plant, dry and cold air passing through the evaporator 28 is periodically discharged, is exhausted once every 2 to 4 hours for 10 minutes, and is introduced into a cement kiln for incineration treatment, so that the waste gas in the kiln is not continuously enriched, and the concentration is controlled within a reasonable range.
Example 3
On the basis of the method of embodiment 2, the method of this embodiment further includes:
the sludge is simply and mechanically dewatered before entering the drying chamber, and the water content of the sludge is 50-85%; the feeding amount of the sludge is 1.8-2.4 t/h; the retention time of the sludge in the drying chamber is 90-150 min.
The flow rate of the waste gas of the air-cooled cement clinker is 10-30 ten thousand Nm3H, relative humidity is less than 6%, and dust content is less than 3mg/m3。
Example 4
On the basis of the method in the embodiment 2, the waste gas of the air cooled cement clinker in the method is replaced by the kiln head cooling residual air with the temperature of 360-400 ℃, or the flue gas from the outlet of a kiln tail preheater separator with the temperature of 340-350 ℃, or the flue gas after passing through a power generation boiler with the temperature of 170-250 ℃. The specific flow rate is adaptively adjusted according to factors such as the flue gas temperature, the target temperature of the drying chamber, the drying amount of the sludge and the like. The flue gas discharged by the cement kiln is not directly used for drying the sludge, but the flue gas discharged by the cement kiln exchanges heat with hot water by using a heat exchange principle, then the hot water exchanges heat with dry and cold air in the waste heat recovery heat pump 2 through the first water-air heat exchanger 24 and the second water-air heat exchanger 26, and then the hot water is conveyed into a drying chamber, so that the temperature of the air in the drying chamber is kept at 75-90 ℃ for indirectly drying the sludge, and the first water-air heat exchanger 24 and the second water-air heat exchanger 26 both use copper and fin heat exchangers with nano coatings.
The sludge drying method realizes the recycling of the waste heat of the cement kiln flue gas, saves energy consumption and cost, but the sludge is dried by using pure waste heat, so that the water consumption is higher, the volume of the cooling tower is very large, and the volume of the cooling tower can be obviously reduced and the drying efficiency is improved by adding the secondary cooling of the evaporator in the heat pump system.
Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims (10)

1. A sludge drying system is characterized by comprising a drying chamber and a waste heat recovery heat pump, wherein air is in closed circulation between the drying chamber and the waste heat recovery heat pump; and the drying chamber is provided with an upper air outlet, an upper air return inlet and a lower air return inlet which are communicated with the waste heat recovery heat pump.
2. The sludge drying system of claim 1, wherein at least two layers of mesh conveyor belts are disposed in the drying chamber; and a circulating fan and a heater are arranged above the conveyor belt.
3. The sludge drying system of claim 1, wherein the waste heat recovery heat pump comprises a pump housing, a cloth bag filter is arranged in the pump housing, and the cloth bag filter is arranged above and inside the pump housing.
4. The sludge drying system of claim 3, wherein a heat regenerator, a first condenser, a first water-air heat exchanger, a second condenser, a second water-air heat exchanger, a water-cooled evaporator, an evaporator and a compressor are further disposed within the pump housing.
5. The sludge drying system of claim 4, further comprising a cooling tower connected to the water-cooled evaporator via a first water circulation conduit; and a first circulating water pump is installed on the first circulating water pipeline.
6. The sludge drying system of claim 4, further comprising a flue gas heat exchanger in heat exchange connection with the first water-air heat exchanger and the second water-air heat exchanger through a second circulating water conduit; and a second circulating water pump is installed on the second circulating water pipeline.
7. A method for drying sludge by using the sludge drying system of claim 6, comprising the steps of:
the sludge is conveyed into the drying chamber through a screw conveyer; the sludge passes through at least two layers of mesh conveyor belts from top to bottom in the drying chamber, hot dry air is introduced below the conveyor belts, and the hot dry air passes through the sludge on the conveyor belts to exchange heat with the sludge and take away moisture in the sludge to form damp and hot air; the damp and hot air is pumped by a circulating fan above the conveyor belt and enters the waste heat recovery heat pump through an upper air outlet of the drying chamber;
the wet hot air entering the waste heat recovery heat pump is filtered by the cloth bag filter to remove dust;
a part of the hot and humid air filtered by the cloth bag filter directly exchanges heat with a first condenser and a first water-air heat exchanger, and then enters the drying chamber through the upper air return inlet for cyclic utilization;
the other part of the damp and hot air filtered by the cloth bag filter is subjected to heat exchange by the heat regenerator, then is subjected to primary cooling by the water-cooled evaporator, is subjected to secondary cooling by the evaporator, is condensed into condensed water to be discharged out of the waste heat recovery heat pump, and dry and cold air formed after cooling is subjected to heat absorption by the compressor, primary heating, secondary heating by the heat regenerator, enters a second water-air heat exchanger for heat exchange, is heated by a second condenser and then enters the drying chamber from the lower air return port for recycling;
water in the water-cooled evaporator enters a cooling tower through a first circulating water pipeline under the action of a first circulating water pump to be cooled and cooled circularly;
and the flue gas discharged by the cement kiln is discharged into the atmosphere after heat exchange by the flue gas heat exchanger, meanwhile, the water temperature in the flue gas heat exchanger rises, and the rising hot water in the flue gas heat exchanger enters the first water-air heat exchanger and the second water-air heat exchanger through a second circulating water pipeline under the action of a second circulating water pump to exchange heat with the dry and cold air in the waste heat recovery heat pump, so that the temperature of the dry and cold air is raised.
8. The method of claim 7, wherein the sludge is simply mechanically dewatered before entering the drying chamber, and the water content of the sludge is 50-85%; the feeding amount of the sludge is 1.8-2.4 t/h; the retention time of the sludge in the drying chamber is 90-150 min; the temperature of the circulating damp-heat air in the drying chamber is kept between 50 and 75 ℃, and the drying temperature of the equipment is between 65 and 85 ℃.
9. The method of claim 7, wherein the water isThe temperature of the flue gas discharged by the mud kiln is 100-400 ℃, and the flow rate is 10-30 ten thousand Nm3H, relative humidity is less than 6%, and dust content is less than 3mg/m3；
The flue gas discharged by the cement kiln can be waste gas of air-cooled cement clinker, the temperature is 100-130 ℃, and the waste gas is organized discharged through a chimney directly after dust collection by a high-efficiency bag; the flue gas discharged by the cement kiln can be kiln head cooling residual air with the temperature of 360-400 ℃, can also be flue gas from the outlet of a kiln tail preheater separator with the temperature of 340-350 ℃, and can also be flue gas after passing through a power generation boiler with the temperature of 170-250 ℃.
10. The method of claim 7, wherein the moisture content of the dried sludge obtained by drying the sludge drying system is 10% -40%, and the dried sludge enters a cement kiln for cooperative treatment and can replace part of fuel; the dried tail gas generated by the sludge drying system can enter a cement kiln, and organic matters are removed at high temperature and then enter a cement kiln tail gas treatment system; condensed water generated by an evaporator of the sludge drying system can directly enter a water treatment system of a cement plant, and dry and cold air passing through the evaporator is periodically discharged and introduced into a cement kiln for incineration treatment.
CN202110014122.6A 2021-01-06 2021-01-06 Sludge drying system and sludge drying method thereof Pending CN112707626A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114656124A (en) * 2022-04-01 2022-06-24 北京金隅红树林环保技术有限责任公司 Sludge drying process by using cement pit waste heat
CN115090658A (en) * 2022-06-27 2022-09-23 北京金隅红树林环保技术有限责任公司 Method for treating kitchen waste, kitchen waste and domestic sludge by virtue of cooperation of cement kiln and drying

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114656124A (en) * 2022-04-01 2022-06-24 北京金隅红树林环保技术有限责任公司 Sludge drying process by using cement pit waste heat
CN115090658A (en) * 2022-06-27 2022-09-23 北京金隅红树林环保技术有限责任公司 Method for treating kitchen waste, kitchen waste and domestic sludge by virtue of cooperation of cement kiln and drying

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