A sludge drying system using steam fluidization heating

Abstract

A sludge drying system with steam fluidization heating comprises a bubbling bed sludge dryer, a cyclone purifier and a steam regenerator connected in sequence, wherein the bubbling bed sludge dryer is divided into at least two spaces connected at the top from the inlet to the outlet, and an air distribution chamber is arranged below each space, and the slag discharge pipe of the cyclone purifier is inserted below the bed material layer of the first space, and the steam regenerator comprises a main working room, a drain tank and an auxiliary water tank, wherein the drain tank and the auxiliary water tank are located on both sides of the main working room, and a plurality of heat exchange surfaces are arranged from top to bottom in the main working room, and the main working room is connected to each air distribution chamber through a pipeline. The present invention effectively solves the problems of flow, heating and drying of garbage, sludge and other materials with high humidity, strong viscosity and difficult flow, and has the advantages of simple system, high heat exchange coefficient, high material drying degree and low equipment energy consumption, thus creating favorable conditions for further resource utilization of garbage and sludge.

Description

Technical Field

[0001] The invention relates to a sludge treatment system, in particular to a sludge drying system using steam fluidization heating. Background Art

[0002] In recent years, with the improvement of the country's requirements for waste treatment, the reduction, harmlessness and resource utilization of solid wastes with high water content such as urban sludge and industrial sludge are important directions and policies for sludge treatment. Sludge drying and calcination are the main ways to reduce and harmlessly treat sludge. Thermal power plants have unique advantages in sludge drying and calcination. While providing various qualities of heating media for sludge drying, they can effectively recover the heat generated by sludge combustion, truly achieving sludge reduction, harmlessness and resource utilization. Because the sludge moisture content is as high as 60-80%, in order to reduce the impact of sludge on boilers, sludge generally needs to be dried. At present, mature sludge dryers on the market can only dry sludge to a moisture content of 30-40%. If the sludge moisture is further reduced, the drying equipment and drying energy consumption will increase significantly.

[0003] The sludge itself is difficult to flow and has viscosity, which brings great difficulties to the manufacture of heating and drying equipment. More importantly, the sludge heating and drying process will release ammonia and H 2 S and combustible volatile gases and other harmful and dangerous gases, thus limiting the sludge heating method and the choice of heating medium. At present, the sludge drying technologies that are widely used in the market mainly include flue gas thin layer drying technology, which uses low-temperature flue gas to heat the sludge and utilizes the waste heat of flue gas. However, this technology has problems such as large equipment and difficult flue gas purification. Another widely used technology is disc or paddle sludge drying technology, which uses steam to heat the sludge through the partition wall. Due to the characteristics of the sludge, this technology has defects such as small heat transfer coefficient, low effective utilization rate of heat exchange surface, low material drying degree, large equipment, high energy consumption, and small capacity of a single device. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a

[0005] The technical solution adopted by the present invention to solve its technical problems is: a steam fluidized heating sludge drying system, comprising a bubbling bed sludge dryer, a cyclone purifier and a steam regenerator connected in sequence, the bubbling bed sludge dryer is divided into at least two upper connected spaces from the inlet to the outlet, and an air distribution chamber is provided below each space. The slag discharge pipe of the cyclone purifier is inserted below the bed material layer of the first space. The steam regenerator comprises a main working room, a drain tank and an auxiliary water tank. The drain tank and the auxiliary water tank are located on both sides of the main working room. A plurality of heat exchange surfaces are arranged at intervals from top to bottom in the main working room, and the main working room is connected to each air distribution chamber through a pipeline.

[0006] Furthermore, the heat exchange surface includes a serpentine heat exchange tube bundle and a spray heat exchange tube bundle, the cyclone purifier is connected to the serpentine heat exchange tube bundle, the serpentine heat exchange tube bundle is connected to the spray heat exchange tube bundle through a pipeline located outside the main working room, the spray heat exchange tube bundle is connected to the drain tank, the upper air space of the drain tank and the upper air space of the auxiliary water tank are connected through the residual air heat exchange tube bundle, the lower water space of the drain tank and the lower water space of the auxiliary water tank are connected through the condensate heat exchange tube bundle, the auxiliary water tank is connected to the spray layer located in the main working room through a pipeline, and the spray layer is located above the spray heat exchange tube bundle.

[0007] The spray layer is provided with a distribution pipe network and an atomizing nozzle, and the atomizing nozzle adopts a mechanical atomization method.

[0008] Furthermore, an inlet header is provided at the inlet of the serpentine heat exchange tube bundle, and an outlet header is provided at the outlet of the serpentine heat exchange tube bundle; a steam distributor is provided at the inlet of the spray heat exchange tube bundle, and a steam collector is provided at the outlet of the spray heat exchange tube bundle.

[0009] Furthermore, a booster fan is provided on the pipeline connecting the cyclone purifier and the main working chamber.

[0010] Furthermore, a steam reheater is provided on the main pipeline connecting the main working room and the air distribution chamber.

[0011] Furthermore, the upper end of the bubbling bed sludge dryer is provided with a steam outlet, and the lower end thereof is provided with a dry sludge outlet.

[0012] Furthermore, a first sewage outlet is provided at the lower end of the auxiliary water tank, a gas outlet is provided at the upper end thereof, and a second sewage outlet is provided at the lower end of the main working chamber.

[0013] Furthermore, the spray heat exchange tube bundle, the residual gas heat exchange tube bundle and the condensate heat exchange tube bundle are all straight-through tube bundles.

[0014] The present invention effectively solves the problems of flow, heating and drying of garbage, sludge and other materials with high humidity, strong viscosity and difficulty in flowing, and has the advantages of simple system, high heat exchange coefficient, high degree of material drying and low equipment energy consumption, thus creating favorable conditions for further resource utilization of garbage and sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown, this embodiment includes a bubbling bed sludge dryer 1, a cyclone purifier 2, a booster fan 3, a steam regenerator 4, etc. which are connected in sequence.

[0018] The upper part of the bubbling bed sludge dryer 1 is a rectangular bubbling bed 101, and three intermediate low walls 102 are arranged in the length direction of the bubbling bed, and the height of the low walls decreases successively. The low wall divides the rectangular bubbling bed into four upper connected spaces, and a wind chamber 104 is arranged below the first space to the fourth space, and a steam inlet 107 is arranged on the wind chamber 104, wherein a wet sludge inlet 105 is arranged above the first space. Below the fourth space is an ash hopper 103, and a dry sludge outlet 106 is arranged below the ash hopper 103, and a steam outlet 108 is arranged above the ash hopper 103. Preferably, a spare interface 109 is arranged at the top of the dryer for adding heat carrier materials such as high-temperature dust (such as high-temperature slag or ash discharge of a fluidized bed boiler).

[0019] The cyclone purifier 2 preferably uses a rotary spray drying purification tower to purify the steam. Lime slurry is sprayed into the cyclone purifier 2 to remove smoke and acid gases entering the steam. The particles separated by the purifier are discharged into the bubbling bed 101 through a slag discharge pipe. The slag discharge pipe of the cyclone purifier 2 passes through the top plate of the first space of the bubbling bed 101 and is inserted below the bed material layer in the space.

[0020] The steam regenerator 4 as a whole is composed of a main working room 401, a drain tank 408 and an auxiliary water tank 411, which are all rectangular cavities. The drain tank 408 and the auxiliary water tank 411 are close to both sides of the main working room 401 and are flush with its lower bottom surface.

[0021] Heat exchange surfaces such as a serpentine heat exchange tube bundle 403, a spray layer 412, a spray heat exchange tube bundle 406, a residual gas heat exchange tube bundle 410, and a condensate heat exchange tube bundle 409 are arranged in sequence from top to bottom in the main working room 401. The serpentine heat exchange tube bundle 403 is connected to the cyclone purifier 2, and an inlet header 402 is provided at the inlet of the serpentine heat exchange tube bundle 403, and an outlet header 404 is provided at the outlet of the serpentine heat exchange tube bundle 403; the spray heat exchange tube bundle 406 is a straight-through tube bundle, and the spray heat exchange tube bundle 406 passes through the main working room 401. A steam distribution box 405 is provided at the inlet of the spray heat exchange tube bundle 406, and a steam collecting box 407 is provided at the outlet of the spray heat exchange tube bundle 406. The serpentine heat exchange tube bundle 403 is connected to the spray heat exchange tube bundle 406 through a pipeline located outside the main working room 401, and the spray heat exchange tube bundle 406 is connected to the drain box 408 through a pipeline located outside the main working room 401. The upper air space of the drain tank 408 is connected to the upper air space of the auxiliary water tank 411 through the residual air heat exchange tube bundle 410, and the lower water space of the drain tank 408 is connected to the lower water space of the auxiliary water tank 411 through the condensate heat exchange tube bundle 409. The residual air heat exchange tube bundle 410 and the condensate heat exchange tube bundle 409 pass through the main working room 401 horizontally.

[0022] The booster fan 3 is located on the pipeline connecting the cyclone purifier 2 and the main working chamber 401.

[0023] The auxiliary water tank 411 is connected to the inlet of the regeneration pump 5 through a pipeline, and the outlet of the regeneration pump 5 is connected to the spray layer 412 through a pipeline. Generally, the spray layer 412 is provided with a distribution pipe network and an atomizing nozzle, and the atomizing nozzle adopts a mechanical atomization method.

[0024] A regeneration steam outlet 413 is provided at the upper portion of the main working chamber 401 and is connected to the inlet of the steam reheater 6 through a pipeline. The outlet of the steam reheater 6 is connected to the steam inlet 107 of the air distribution chamber 104 through pipelines.

[0025] A second sewage outlet 414 is provided at the bottom of the main working room 401 , a first sewage outlet 415 is provided at the bottom of the auxiliary water tank 411 , and a non-condensable gas outlet 416 is provided at the top of the auxiliary water tank 411 .

[0026] During operation, the bubbling bed sludge dryer 1 is filled with bed material, which can be fine particles such as coal ash, sand or dry sludge. New steam with a pressure of about 10kPa and a temperature of 200-300℃ enters the bubbling bed 101 from the air distribution chamber 104, blows the bed material into a dispersed state, and continuously climbs over the middle low wall, moving from the left end to the right end, that is, from the wet sludge inlet 105 to the dry sludge outlet 106. Finally, the larger particles fall into the ash hopper 103 and are discharged from the bubbling bed sludge dryer 1. The finer sludge ash enters the cyclone purifier 2 with the steam. 90%-95% of the dust particles are captured and re-enter the bubbling bed 101 to complete the circulation of fine ash particles; by controlling the steam fluidization speed, the circulation rate of fine ash is controlled to be about 3-5 times. Wet sludge with a moisture content of 60-80% is crushed into sludge particles with a particle size of about 3-5 mm, and enters the dryer from the wet sludge inlet 105 of the bubbling bed sludge dryer 1. In the bed, it is immediately wrapped by the fine ash particles in the bubbling bed 101, dispersed in the bed material and moved with the bed material. During the movement, the wet sludge particles continuously absorb the heat of the hot bed material and steam, and the water evaporates and becomes dry, and finally discharged from the dryer.

[0027] The steam transfers heat to the wet sludge and dries it, and then is discharged from the steam outlet of the bubbling bed sludge dryer 1. The steam temperature drops and is maintained at about 150°C. The discharged steam carries sludge ash particles, H2O2 precipitated during the sludge drying process, and the steam is discharged from the bubbling bed sludge dryer 1. 2 S, methane and other gases form exhaust steam. The exhaust steam enters the cyclone purifier 2 to remove the dust and acidic gas in the waste, and then passes through the booster fan 3 to increase the exhaust steam pressure by about 80-100 kPa, and the condensation point of the waste steam under the corresponding pressure rises to about 120°C. Then the exhaust steam enters the steam regenerator 4. The steam in the steam regenerator 4 passes through the heat exchange surfaces such as the serpentine heat exchange tube bundle 403, the spray heat exchange tube bundle 406, the residual gas heat exchange tube bundle 410 and the condensate heat exchange tube bundle 409 in turn. The steam condenses into stable water at about 120°C, and the non-condensable gas is separated and discharged from the system. In the serpentine heat exchange tube bundle 403, the exhaust steam transfers heat to the new steam generated by the steam regenerator 4, and the temperature drops to near the saturation temperature, but it is still dry steam. After passing through the spray heat exchange tube bundle 406, the steam is converted into wet steam with a high humidity content and enters the drain box 408, and the condensate and gas are initially separated.

[0028] The gas space and water space of the drain tank 408 and the auxiliary water tank 411 are connected through the residual gas heat exchange tube bundle 410 and the condensate heat exchange tube bundle 409 respectively, and the two tube bundles are immersed in the lower water pool in the main working room 401. When the residual gas enters the auxiliary water tank 411 from the drain tank 408 through the residual gas heat exchange tube bundle 410, the steam in the gas further condenses and heats the water in the main working room 401. The condensate in the drain tank 408 enters the auxiliary water tank 411 through the condensate heat exchange tube bundle 409. When passing through the condensate heat exchange tube bundle 409, the temperature of the condensate itself is reduced, and the condensate in the main working room 401 is heated to evaporate. The non-condensable gas is finally discharged from the gas outlet 416 above the auxiliary water tank 411.

[0029] The water in the auxiliary water tank 411 is pressurized and atomized by the regeneration pump 5 and then sprayed onto the top of the spray heat exchange tube bundle 406 in the main working room 401. The pressure in the main working room 401 is maintained at about 10 kPa, and the saturation temperature of water under the corresponding pressure is about 105°C. The pressure of the atomized water droplets is rapidly reduced and evaporated. The falling water droplets absorb heat on the surface of the spray heat exchange tube bundle 406 and further evaporate to generate new steam. The unevaporated water droplets finally fall into the water pool below and absorb the heat of the heat exchange tube bundle in the water pool to evaporate.

[0030] The new steam generated in the main working room 401 is heated by the serpentine heat exchange tube bundle 403 to a temperature of about 120-130°C, with a certain degree of superheat, and is discharged from the steam regenerator 4 to become new steam. After absorbing external heat through the steam reheater 4, the temperature rises to about 250°C and re-enters the bubbling bed sludge dryer 1 to realize steam circulation.

[0031] During the conversion of spent steam into new steam and the circulation process in the regenerator, a small amount of dust brought into the steam regenerator 4 with the spent steam is deposited under each water pool along with the condensed water and discharged through the sewage outlet. The main heat losses of the system include the heat loss of sewage discharge from the steam regenerator, the physical heat loss brought out by the discharge of dry sludge from the dryer, and the heat brought out by non-condensable gases. The sewage discharge, ash discharge, and exhaust temperature levels of the system are all low. The heat absorbed by the sludge drying in the conventional sludge dryer is discharged from the system in the form of waste steam, which consumes a large amount of cooling water and is difficult to recover the heat. Compared with conventional sludge drying technology, the sludge dryer of the present invention has small energy losses, and the required energy is supplemented from the steam reheater.

[0032] Those skilled in the art may make various modifications and variations to the present invention. If these modifications and variations are within the scope of the claims of the present invention and their equivalents, then these modifications and variations are also within the protection scope of the present invention. In particular, simple changes such as changing the form of the bubbling bed or changing the arrangement of the heat exchange surface in the steam regenerator are still within the protection scope of this right.

[0033] The contents not described in detail in the specification are prior art known to those skilled in the art.

Claims

1. A steam fluidized heating sludge drying system, comprising a bubbling bed sludge dryer, a cyclone purifier and a steam regenerator connected in sequence, characterized in that: The bubbling bed sludge dryer is divided into at least two spaces connected at the top from the inlet to the outlet, and an air distribution chamber is provided below each space. The slag discharge pipe of the cyclone purifier is inserted below the bed material layer of the first space. The steam regenerator includes a main working room, a drain tank and an auxiliary water tank. The drain tank and the auxiliary water tank are located on both sides of the main working room. A plurality of heat exchange surfaces are arranged at intervals from top to bottom in the main working room, and the main working room is connected to each air distribution chamber through a pipeline. The heat exchange surface includes a serpentine heat exchange tube bundle and a spray heat exchange tube bundle, the cyclone purifier is connected to the serpentine heat exchange tube bundle, the serpentine heat exchange tube bundle is connected to the spray heat exchange tube bundle through a pipeline located outside the main working room, the spray heat exchange tube bundle is connected to the drain tank, the upper air space of the drain tank is connected to the upper air space of the auxiliary water tank through the residual air heat exchange tube bundle, the lower water space of the drain tank is connected to the lower water space of the auxiliary water tank through the condensate heat exchange tube bundle, the auxiliary water tank is connected to the spray layer located in the main working room through a pipeline, and the spray layer is located above the spray heat exchange tube bundle.

2. The steam fluidized heating sludge drying system according to claim 1 is characterized in that: An inlet header is provided at the inlet of the serpentine heat exchange tube bundle, and an outlet header is provided at the outlet of the serpentine heat exchange tube bundle; a steam distributor is provided at the inlet of the spray heat exchange tube bundle, and a steam collector is provided at the outlet of the spray heat exchange tube bundle.

3. The steam fluidized heating sludge drying system according to claim 1 is characterized in that: A booster fan is provided on the pipeline connecting the cyclone purifier and the main working room.

4. The steam fluidized heating sludge drying system according to claim 1 is characterized in that: A steam reheater is arranged on the main pipeline connecting the main working room and the air distribution chamber.

5. The steam fluidized heating sludge drying system according to claim 1 is characterized in that: The upper end of the bubbling bed sludge dryer is provided with a steam outlet, and the lower end thereof is provided with a dry sludge outlet.

6. The steam fluidized heating sludge drying system according to claim 1 is characterized in that: The lower end of the auxiliary water tank is provided with a first sewage outlet, the upper end thereof is provided with a gas outlet, and the lower end of the main working chamber is provided with a second sewage outlet.

7. The steam fluidized heating sludge drying system according to claim 1 is characterized in that: The spray heat exchange tube bundle, the residual gas heat exchange tube bundle and the condensate water heat exchange tube bundle are all straight-through tube bundles.

8. The steam fluidized heating sludge drying system according to claim 1 is characterized by: A water pump is arranged on the connecting pipeline between the auxiliary water tank and the spray layer.

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