CN102531322B - Novel energy-saving sludge drying system - Google Patents

Abstract

The invention discloses a sludge drying system, which comprises a solar greenhouse (12), a solar heat collector system (7), a heat pump system, a heat storage device (2) and a sludge drying device; The heat pump system (7) is placed on the roof of the solar greenhouse (12), the heat pump system, the thermal storage device (2) and the sludge drying device are installed in the solar greenhouse (12), and the thermal storage device (2) is installed in the pipeline of the heat pump system . The sludge drying system of the present invention has stable operation, high degree of automation, simple equipment, low initial investment, low energy consumption and operating cost, and the sludge after drying has been stabilized, reduced, harmless, and resourceful. Sludge treatment effect is good.

Description

An energy-saving sludge drying system

technical field

The invention relates to a drying system, in particular to a novel energy-saving sludge drying system for drying wet materials in large quantities, such as dewatered sludge.

Background technique

With economic development, population growth, accelerated urbanization, and increased sewage treatment rates, the amount of municipal sludge produced is also increasing. However, my country's sludge treatment technology and equipment are generally backward, and the safety of sludge treatment and disposal is limited. The guarantee rate is very low, which has become an urgent problem facing our country.

Sludge drying is a treatment method for deep dehydration of sludge with a heat source. It can significantly reduce the volume of sludge, and the volume can be reduced by 4-5 times. The product is stable, odorless, and free of pathogenic organisms. The sludge after drying treatment The product has many uses and can be used as fertilizer, soil conditioner, alternative energy, etc. Conventional sludge dryers use high-grade energy such as electric heating or coal-fired or oil-fired boilers to generate steam, which not only consumes a lot of energy and increases carbon emissions, but also has a high drying temperature, a large temperature difference with the environment, high exhaust temperature, and high energy utilization efficiency. Low and high operating costs, it is not suitable for the energy-saving and emission-reduction goals advocated by the society. In addition, the flue gas generated by the heat source of coal-fired and oil-fired boilers will cause secondary pollution to the atmosphere, requiring additional gas pollution treatment costs. Another common method of sludge drying is radiation drying. Its principle is to directly act on the material to reduce the resistance of internal heat transfer. The drying speed is fast, but the thermal efficiency is low, and the drying cost and operating cost are high. The high one-time investment and operating costs of sludge drying hinder the application and promotion of sludge drying to a large extent, and delay the process of sludge treatment in small and medium-sized urban sewage treatment plants. Now many sewage treatment plants have accumulated a large amount of sludge, which has caused serious secondary pollution to the environment.

In recent years, many research papers and patents use solar energy to dry sludge. For example, the paper written by Wang Chuanqi et al. (Research on Greenhouse Solar Sludge Drying, Science and Technology Herald 2010, 28 (22)) analyzed the use of solar radiation to dry sludge, pointing out that The use of solar energy can make an area of 1 square meter produce nearly 1 ton of sludge drying capacity in a year. In the invention patent: solar energy, high temperature dual heat source heat pump sludge drying system (patent number zL200710020057.8, authorized announcement number CN100559103C, authorized by the Chinese Patent Office on November 11, 2009), the solar air collector is used to collect solar energy and provide it to the heat pump At the same time, the heat pump can also recover the heat in the humid air, so as to achieve the purpose of saving energy. Another example is the invention patent: the system for drying sludge using solar energy (patent application number 200810059068.1, China Patent Office) adopts a heat transfer oil type solar heat collector, and dries the sludge through heat transfer oil heated by solar energy, which can also save the cost of drying. part energy. In general, these solar energy utilization methods are generally divided into two categories: one uses direct radiation drying, and the other uses solar collectors to collect heat energy first, and then supply it to other devices.

However, a practical problem has been overlooked in these studies: most regions in my country have distinct seasons and climates, and the temperature difference between summer and winter is large. At the same time, day and night alternate, resulting in instability and volatility of solar heat sources. In addition, the air temperature is low in winter, and the utilization efficiency of air heat energy is low. On the other hand, the humid air emitted by evaporation has a high temperature and contains a lot of available energy, and many studies or patents have not considered recycling. Generally speaking, the existing devices or methods for drying using solar energy are complicated, have poor stability and reliability, fail to make full use of heat energy, and have low practical feasibility.

Contents of the invention

In order to overcome the shortcomings of high energy consumption, instability, and low reliability of the original sludge drying technology, the purpose of the present invention is to provide a sludge drying system, which is simple and reliable, and can reduce the waste generated during the sludge drying process. Secondary pollution.

Technical scheme of the present invention is as follows:

The invention provides a sludge drying system, which comprises a solar greenhouse, a solar heat collector system, a heat pump system, a thermal storage device and a sludge drying device; the solar heat collector system is placed on the roof of the solar greenhouse, and the heat pump The system, heat storage device and sludge drying device are installed in the solar greenhouse, and the heat storage device is installed in the pipeline of the heat pump system.

The solar greenhouse roof is a transparent glass roof.

A temperature sensor and a temperature controller are further installed in the solar greenhouse.

The solar thermal collector system includes a solar thermal collector and an evaporator, the evaporator is placed in the solar thermal collector, the evaporator is placed behind a temperature control valve, and is connected in parallel with the heat-absorbing and dehumidifying evaporator.

The solar heat collector adopts vacuum flat-plate vacuum tubes or vacuum tubes arranged in an array.

The heat pump system includes a heat pump compressor, a condenser, a heat pump throttle valve, a heat pump pipeline, a heat-absorbing dehumidification evaporator and an evaporator placed in a solar heat collector, a heat pump compressor, a condenser, a heat pump throttle valve , The heat-absorbing dehumidification evaporator and the evaporator placed in the solar collector are connected through a heat pump pipeline, the heat-absorbing dehumidification evaporator and the evaporator placed in the solar collector are connected in parallel, and the evaporator arranged after the throttle valve The temperature control valve controls the flow of working fluid into the heat-absorbing dehumidification evaporator and the evaporator placed in the solar collector.

The heat-absorbing and dehumidifying evaporator is provided with a drainage structure.

The heat storage device is in the form of a single tank.

The heat storage device is installed in the pipeline of the heat pump system, and has the following three connection modes: the heat storage device is located behind the heat pump compressor; or the heat storage device is located before the heat pump compressor; or the heat storage device, condenser, sludge The tumbler and the sludge drying bed together form a drying device.

The sludge drying device includes a condenser, a sludge drying bed and a sludge tanning machine, the condenser is installed at the bottom of the sludge drying bed, and the sludge tanning machine is placed horizontally above the sludge drying bed.

The present invention is also provided with a temperature controller, each pipeline and the solar heat collector are provided with a temperature sensor, the valves on each pipeline are electromagnetic valves, and each electromagnetic valve and temperature sensor are respectively connected to the temperature controller.

Compared with the prior art, the present invention adopts the latest heat storage device, so that heat can be stored during the peak period of obtaining heat energy, and the stored heat can be released for use during intermittent periods, avoiding solar fluctuations caused by day and night, and improving system stability performance and drying efficiency. The specific working method is that the high-temperature working medium first passes through the heat storage device after it comes out of the compressor, or the working medium enters the heat storage device before entering the compressor, and after the working medium absorbs or releases heat, it can achieve the heat pump working medium at all times during the day and night. Maintain a stable temperature into the heat exchanger of the sludge drying unit.

At the same time, the present invention cleverly combines the solar heat collector with the evaporator in the heat pump system to effectively absorb solar energy, and arranges another evaporator in the solar greenhouse to recover the low-quality heat energy in the hot and humid steam generated by sludge drying , thus effectively reducing the overall energy consumption required for drying. In addition, the combination of heating the sludge at the bottom by the heat pump condenser and tumbling can improve the drying efficiency.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The present invention changes the traditional technology of using high-grade heat source to dry sludge, introduces solar collectors and greenhouses into the system as drying heat source, and adopts heat pump to recover the heat energy in the hot and humid steam generated by drying, which saves a lot Reduce energy consumption; the sludge is based on the basic principle of heat pump heating, using the evaporator in the heat pump system to absorb outdoor solar energy and low-quality heat in the solar greenhouse, and use this heat to heat the sludge in the condenser section to achieve the purpose of drying the sludge .

2. The present invention adopts the combination of heating sludge at the bottom and turning over the sun, heating the sludge in depth, and can fully use the heat energy for sludge drying. Compared with the traditional method of directly drying the sludge surface by the sun, the energy utilization rate and drying efficiency are higher .

3. The present invention can run and dry continuously throughout the day, overcomes the defects that traditional solar energy cannot be used at night and cannot work normally in rainy and cloudy days without sunlight, and ensures that the sludge drying will not be affected in extreme cases.

4. The present invention does not need to use outdoor air, and the method of condensing the moisture in the humid air through the evaporator removes the moisture brought by the sludge drying, and at the same time collects the latent heat of evaporated moisture, which greatly reduces the drying energy consumption.

5. In the present invention, the indoor air is circulated indoors, and the foul smell produced by the sludge will not be discharged outside, which is conducive to environmental protection requirements.

6. The sludge drying system of the present invention is stable in operation, high in automation, simple in equipment, low in initial investment, low in energy consumption and operating costs, and the sludge after drying has been stabilized, reduced, harmless, and resource-efficient. chemical, and the sludge treatment effect is good.

Description of drawings

FIG. 1 is a schematic diagram of the overall system structure of Embodiment 1 of the present invention.

In the figure: 1 is the heat pump compressor, 2 is the heat storage device, 3 is the sludge tanning machine, 4 is the condenser, 5 is the heat pump throttle valve, 6 is the temperature control valve, 7 is the solar collector system, 8 is the Heat-absorbing and dehumidifying evaporator, 9 is a heat pump pipeline, 10 is a transparent glass roof, 11 is a sludge drying bed, and 12 is a solar greenhouse.

FIG. 2 is a schematic diagram of the overall system structure of Embodiment 2 of the present invention.

FIG. 3 is a schematic diagram of the overall system structure of Embodiment 3 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.

Example 1

FIG. 1 is a schematic diagram of the overall system structure of Embodiment 1 of the present invention.

As shown in Figure 1, this sludge drying system comprises solar greenhouse 12, solar thermal collector system 7, heat pump system, heat storage device 2 and sludge drying device; Solar thermal collector system 7 is placed on the roof of solar greenhouse 12, and heat pump The system, the thermal storage device 2 and the sludge drying device are installed in the solar greenhouse 12, and the thermal storage device 2 is installed in the pipeline of the heat pump system.

The roof of the solar greenhouse 12 is a transparent glass roof 10; a temperature sensor and a temperature controller are further installed in the solar greenhouse 12. The solar greenhouse 12 improves the ability to absorb solar radiation through the transparent glass roof 10, improves the air temperature in the greenhouse, and increases the heat source supply of the heat-absorbing and dehumidifying evaporator 8. In addition, through the temperature sensor and controller, the air temperature in the greenhouse can be sensed. Once the temperature is too high, the fan speed of the heat-absorbing and dehumidifying evaporator 8 can be increased to speed up the heat absorption speed of the heat-absorbing and dehumidifying evaporator 8 to maintain a constant indoor temperature and humidity. , improve drying efficiency.

The solar heat collector system 7 includes a solar heat collector and an evaporator, the evaporator is placed in the solar heat collector, the evaporator is placed after the temperature control valve 6, and is connected in parallel with the heat-absorbing and dehumidifying evaporator 8. The solar collector adopts vacuum flat-plate vacuum tubes or vacuum tubes arranged in arrays.

Different from the common solar hot water collector system, the solar collector system 7 of the present invention is designed with the solar collector and the evaporator in the heat pump system as an integral structure, which can heat the working medium in the evaporator with the collected solar energy. The solar thermal collector system 7 is the main heat source of the heat pump, providing thermal energy for sludge drying. The solar heat collector system 7 can effectively collect solar radiation energy and convert it into heat energy, and transfer the heat energy to the heat pump through the evaporator arranged therein. The solar heat collector system 7 can adopt vacuum flat plate type or vacuum tube type, and the array arrangement can increase the receiving radiation area, and at the same time, a good thermal insulation layer can be used to ensure the maximum conversion of the sun's radiant energy and improve the absorption efficiency.

The heat pump system includes a heat pump compressor 1, a condenser 4, a heat pump throttle valve 5, a heat pump pipeline 9, a heat-absorbing dehumidification evaporator 8 and an evaporator placed in a solar heat collector, the heat pump compressor 1, the condenser 4, The heat pump throttle valve 5, the heat-absorbing and dehumidifying evaporator 8 and the evaporator placed in the solar heat collector are connected through a heat pump pipeline 9, and the heat-absorbing and dehumidifying evaporator 8 and the evaporator placed in the solar heat collector are connected in parallel , the temperature control valve 6 arranged after the throttle valve controls the flow of the working fluid entering the heat-absorbing dehumidification evaporator 8 and the evaporator placed in the solar collector. The heat-absorbing and dehumidifying evaporator 8 is provided with a drainage structure, and is larger in size than the evaporator in an ordinary air-conditioning system. The reason is that: the sludge drying device discharges a large amount of hot and humid gas with high moisture content. When it enters the heat-absorbing and dehumidifying evaporator 8 of the heat pump, since the surface temperature of the evaporator is lower than the dew point temperature of the gas, water is condensed on the surface of the evaporator, and at the same time The latent heat of liquefaction of water vapor is absorbed, so that the heat energy consumed by drying sludge is recovered, and the water vapor generated by drying sludge will be discharged outside in the form of liquid water.

The circulating fluid in the heat pump system absorbs the heat in the hot and humid gas discharged from the dried sludge in the heat-absorbing dehumidification evaporator 8 and the solar heat energy collected in the solar collector system 7, and evaporates from the low-pressure liquid working fluid into low-pressure steam , transported to the heat pump compressor 1 through the heat pump pipeline 9 to be pressurized into high-temperature and high-pressure steam, and enter the condenser 4 through the heat pump pipeline 9, the high-temperature and high-pressure working medium releases heat to heat the wet sludge, while the working medium itself The gas is condensed into a high-pressure liquid, and after passing through the throttle valve 5 of the heat pump, it becomes a low-temperature and low-pressure fluid, which continues to absorb the heat provided by the evaporator, and the sludge is heated and dried repeatedly in this way.

The heat storage device 2 is in the form of a single tank; the heat storage device 2 is installed in the pipeline of the heat pump system. This embodiment adopts the following installation method: the heat storage device 2 is installed behind the heat pump compressor 1 .

The heat pump line 9 passes through the heat storage device 2 and only heat exchange takes place. Due to the instability of solar energy, heat storage device 2 must be used. During the peak period of solar radiation, such as at noon, when the heat pump working fluid flows through the working medium pipeline placed in heat storage device 2, excess heat energy in the working medium will be stored. In the heat storage device 2; during the low solar radiation period, such as late at night, the heat storage device 2 releases heat energy to the working medium in the pipeline to make up for the lack of heat required for sludge drying.

The sludge drying device includes a condenser 4, a sludge drying bed 11, and a sludge tumbler 3. The condenser 4 is installed at the bottom of the sludge drying bed 11, and the sludge tumbler 3 is placed horizontally above the sludge drying bed 11. , to discharge the hot and humid steam in the sludge in time. In the case of good sunlight radiation, the solar radiation can directly dry the sludge through the glass roof 10 of the greenhouse to improve the drying efficiency.

The basic process of the heat pump system of the present invention is: the solar collector uses water or other heat transfer medium to collect solar energy, heats the heat pump evaporator installed in the heat collection system, and the working medium in the evaporator pipeline is heated to obtain heat energy. The other way is to collect the low-quality heat energy in the humid air through the evaporator in the solar greenhouse 12 for heating the working medium. At the same time, the evaporator condenses water vapor, reducing the humidity in the room. After the two heated working fluids meet, they enter the heat pump compressor 1 along with the heat pump pipeline 9 and are compressed to high temperature and high pressure. accumulate. The working medium that reaches the set temperature continues to enter the condenser 4 in the sludge drying device to heat and dry the sludge. The cooled high-pressure and low-temperature working fluid enters the throttle valve 5 along with the pipeline, and the throttling becomes a low-temperature and low-pressure working medium, which is controlled by the temperature control valve 6. A part of the working medium enters the solar collector system 7 to continue absorbing solar energy, and a part enters the room The evaporator 8 absorbs the heat energy of the hot and humid air and condenses the moisture of the humid air to form a closed heat pump circulation system.

The sludge after mechanical dehydration is poured into the sludge drying bed 11, and the sludge is heated by the high-temperature working medium placed in the condenser 4 at the bottom of the drying bed, and the sludge tumbler 3 regularly tumbles the sludge, and the drying process produces Hot and humid steam. The sludge tumbler 3 is programmed to turn the sludge regularly to speed up the sludge drying. The heat storage device 2 is placed in the heat pump pipeline 9 to absorb excess heat energy in the working fluid or release heat to the working fluid to maintain the stable operation of the heat pump system for drying sludge. In addition, the glass roof 10 of the solar greenhouse is designed as transparent glass, which can directly radiate and dry the sludge during the day when the solar radiation is sufficient to improve the drying efficiency.

The controller, sensor and solenoid valve set in the system can make the system realize automatic operation according to the environmental conditions, and can adjust the fan speed of the dehumidification heat exchanger according to the ambient temperature of the greenhouse to maintain the temperature of the greenhouse at a low level; it can also sense solar energy Whether the temperature of the collector is lower than the working fluid outlet temperature of the throttle valve under severe conditions, adjust the flow direction of the working fluid through the temperature control valve 6, for example, in the case of severe cold in winter, avoid the reverse heating of the solar heater by the working fluid.

To sum up, the solar energy and the heat pump in the system of the present invention work together, and the heat pump can not only utilize the green energy of solar energy, but also recover the sensible heat and latent heat in the hot and humid air generated by sludge drying, and the energy is fully and reasonably utilized. High energy utilization efficiency and low energy consumption costs. The drying sludge system of the present invention is closed, does not need to discharge moisture to the outside, and does not discharge harmful odor, and the dried sludge becomes odorless particles, which does not pollute the environment. At the same time, by adding heat storage device 2, the heat pump is less affected by external climate conditions, the equipment runs smoothly, and the quality of sludge drying products is stable, which is beneficial to the utilization of sludge resources. The equipment adopted by the system of the present invention is simple and highly automatic, and can be widely used in drying various wet materials.

Example 2

FIG. 2 is a schematic diagram of the overall system structure of Embodiment 2 of the present invention.

The heat storage device 2 is installed in the pipeline of the heat pump system, and the following installation method is adopted: the heat storage device 2 is installed before the heat pump compressor 1; the others are the same as in the first embodiment.

Example 3

FIG. 3 is a schematic diagram of the overall system structure of Embodiment 3 of the present invention.

The heat storage device 2 is installed in the pipeline of the heat pump system, and the following installation method is adopted: the heat storage device 2, the condenser 4, the sludge remedial machine 3 and the sludge drying bed 11 together form a drying device; the others are the same as in the first embodiment.

The above description of the embodiments is for those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the embodiments herein. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (9)

1. sludge dry system, it is characterized in that: this sludge dry system comprises solar energy greenhouse (12), solar energy collector system (7), heat pump, regenerative apparatus (2) and sludge drying mechanism; Solar energy collector system (7) is placed in solar energy greenhouse (12) roof, and heat pump, regenerative apparatus (2) and sludge drying mechanism are arranged in solar energy greenhouse (12), and regenerative apparatus (2) is arranged in the heat pump pipeline;

Described heat pump comprises heat pump compressor (1), condenser (4), throttling of heat pump valve (5), heat pump circuits (9), heat absorption dehumidifying vaporizer (8) and is placed in the vaporizer of solar energy collector, heat pump compressor (1), condenser (4), throttling of heat pump valve (5), heat absorption dehumidifying vaporizer (8) and the vaporizer that is connected solar energy collector connect by heat pump circuits (9), and the vaporizer that heat absorption dehumidifies vaporizer (8) and is placed in solar energy collector is for being connected in parallel.

2. sludge dry system according to claim 1, it is characterized in that: described solar energy greenhouse (12) roof is transparent glass roof (10).

3. sludge dry system according to claim 1, it is characterized in that: described solar energy greenhouse is equipped with temperature inductor and temperature regulator in (12).

4. sludge dry system according to claim 1, it is characterized in that: described solar energy collector system (7) comprises solar energy collector and vaporizer, vaporizer is placed in solar energy collector, vaporizer is placed in temperature control valve (6) afterwards, and is in parallel with heat absorption dehumidifying vaporizer (8).

5. sludge dry system according to claim 4, is characterized in that: the valve tube of described solar energy collector employing evacuated flat panel type valve tube or arranged in arrays.

6. sludge dry system according to claim 1 is characterized in that: described heat absorption dehumidifying vaporizer (8) is provided with discharge structure.

7. sludge dry system according to claim 1, it is characterized in that: described regenerative apparatus (2) is shaped as single tank form.

8. sludge dry system according to claim 1, it is characterized in that: described regenerative apparatus (2) is arranged in the heat pump pipeline, and following three kinds of mode of connection are arranged: regenerative apparatus (2) is positioned at heat pump compressor (1) afterwards; Or regenerative apparatus (2) is positioned at heat pump compressor (1) before; Or regenerative apparatus (1), condenser (4), mud tedder (3) and sludge drying bed (11) form desiccation apparatus together.

9. sludge dry system according to claim 1, it is characterized in that: described sludge drying mechanism comprises condenser (4), sludge drying bed (11) and mud tedder (3), condenser (4) is arranged on sludge drying bed (11) bottom, and mud tedder (3) is horizontal in sludge drying bed (11) top.

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