CN109928601A - Sludge deep drying method and system based on air heat pump - Google Patents

Abstract

The invention discloses a method and system for deep drying of sludge based on an air heat pump. Add the remaining sludge to be treated into the sludge pulverization and drying device, so that the sludge to be treated with a moisture content of 30% to 55% is pulverized and broken into sludge powder with a particle size of 30 to 250 μm, and then passed into the drying process. The air is mixed with the sludge powder under stirring conditions, and the sludge powder is dried to obtain the sludge dry powder. The low-temperature moisture-containing air carrying the sludge dry powder is separated from the gas powder through the separation device, and the separated solid material is the sludge dry powder material. The moisture content of the sludge dry powder is 15% to 25%. The separated low-temperature moisture-containing air enters the condensing dehumidifier to condense and remove water, and becomes low-low temperature air; the low-low temperature air is sent to the air heat pump for heating and becomes dry air again for reuse. The heat absorbed by the cooling air is returned to the air heat pump for heat exchange to the low and low temperature air. The invention has the advantages of deep drying of sludge, direct use of ambient air as a heat source, energy saving and high efficiency, and the like.

Description

Sludge deep drying method and system based on air heat pump

technical field

The invention relates to a method and system for deep drying of sludge based on an air heat pump, in particular to a method and a process system for deep dewatering of excess sludge, which belongs to the sub-field of waste sludge treatment of sewage treatment plants in the technical field of environmental protection.

Background technique

With the development of my country's society and urbanization, the amount of urban sewage is increasing, and the number of corresponding sewage treatment facilities is also increasing. . As of 2017, the annual output of excess sludge in my country has exceeded 40 million tons, and the harmless treatment rate is less than 10%. How to properly handle and dispose of these continuously generated and increasingly large sludge has become an urgent problem to be solved in my country's environmental protection.

The excess sludge produced by most domestic sewage treatment plants generally has a moisture content of more than 80%. Sludge dewatering is a key step in its treatment process. The difficulty of deep dewatering of sludge has become a bottleneck problem that restricts the harmless and resourceful treatment of sludge.

At present, the main processes of sludge dewatering and drying include solar drying, thermal drying, conditioning-filter press dehydration, etc. Among them, the solar drying process utilizes the thermal effect of solar energy, which can reduce the moisture content of the sludge to below 10% and achieve the purpose of deep drying. . Thermal drying technology evaporates the water in the sludge through direct heating or indirect heating, and the water content of the sludge can be reduced to less than 40%, and further reduction of the water content requires a significant increase in energy consumption; conditioning - filter press The dewatering technology is that the excess sludge is modified by a conditioner to improve the dewatering performance of the sludge, and then pressed and dewatered by a filter press, and the moisture content of the sludge can be reduced to 60%. The above process can quickly remove the moisture in the sludge, but the degree of dehydration is limited, and it is difficult to achieve deep drying of the sludge (water content ≤ 20%).

Therefore, it is the current development direction to further reduce the moisture content of the semi-dry sludge produced by thermal drying or mechanical dehydration process and realize the deep drying of excess sludge quickly and efficiently.

SUMMARY OF THE INVENTION

The present invention aims to provide a method and system for deep drying of sludge based on an air heat pump, which utilizes the air heat pump to obtain heat from ambient air to form both dry air and cooling air, and makes the overall system more efficient while drying the sludge. Energy efficient.

The present invention is achieved through the following technical solutions:

Sludge deep drying method based on air heat pump, the method includes:

The remaining sludge to be treated is added to the sludge pulverization and drying device, so that the sludge to be treated is pulverized and broken into sludge powder with a particle size of 30-250 μm, and then drying air is introduced to mix with the sludge under stirring conditions. The powder is mixed to make the sludge powder dry to obtain the sludge dry powder, and the drying air becomes the low-temperature moist air carrying the sludge dry powder at the same time;

The low-temperature moisture-containing air carrying the sludge dry powder is separated from the gas and solid through the separation device, and the separated solid material is the sludge dry powder material; the separated low-temperature moisture-containing air enters the condensing dehumidifier to condense and remove water, and becomes a low-low temperature Air; the low-low temperature air is sent to the air heat pump to be heated to become dry air, and the dry air is sent to the sludge pulverization and drying device to be mixed with the sludge powder under stirring conditions to dry the sludge powder.

The method also includes:

The fresh air is sent into the air heat pump to exchange heat with the low and low temperature air, so that the fresh air is cooled to become cooling air, and the low and low temperature air is heated to become dry air; Dry, realize the recycling of dry air.

The method also includes:

The cooling air is sent into the condensation dehumidifier and the low-temperature moisture-containing air is subjected to wall heat exchange, so that the low-temperature moisture-containing air is condensed and dewatered to become low-low temperature air, and the cooling air is heated to become warm air; The incoming air heat pump is used as a heat source for heat exchange of low and low temperature air to heat up, and at the same time, the temperature of warm air is cooled down and returned to the condensing dehumidifier for repeated use.

In the above technical solution, the moisture content of the excess sludge is 35% to 50%; the moisture content of the dry sludge powder is 15% to 25%.

A sludge deep drying system based on an air heat pump includes a sludge pulverization and drying device, a separation device, a condensation dehumidifier and an air heat pump; the sludge pulverization and drying device includes a connected pulverization chamber and a drying chamber, The pulverization chamber is provided with a feeding device; the separation device is respectively connected with the sludge pulverization and drying device and the condensation dehumidifier; the air and the heat pump are respectively connected with the condensation dehumidifier and the sludge pulverizer The drying device is connected.

In the above technical solution, both the pulverizing chamber and the drying chamber of the sludge pulverizing and drying device are provided with a screw stirring device; the drying chamber is provided with an air inlet which is connected to the air heat pump.

The invention has the following advantages and beneficial effects: the drying effect is improved, and the economical moisture content of sludge drying is greatly reduced from 40% to below 20%; Drying technology, more energy-saving and efficient.

Description of drawings

FIG. 1 is a schematic diagram of a sludge deep drying system based on an air heat pump according to the present invention.

In the figure: 1 – sludge pulverization and drying device; 2 – separation device; 3 – condensation dehumidifier; 4 – air heat pump.

Detailed ways

The specific embodiments and working process of the present invention will be further described below with reference to the accompanying drawings.

Orientation terms such as upper, lower, left, right, front and rear in this application document are established based on the positional relationship shown in the accompanying drawings. If the drawings are different, the corresponding positional relationship may also change accordingly, so this should not be construed as a limitation on the protection scope.

As shown in FIG. 1 , the air heat pump-based sludge deep drying system includes a sludge pulverization and drying device 1 , a separation device 2 , a condensation dehumidifier 3 and an air heat pump 4 . The sludge pulverizing and drying device 1 includes a connected pulverizing chamber and a drying chamber, and the pulverizing chamber is provided with a feeding device. Both the pulverizing chamber and the drying chamber of the sludge pulverizing and drying device 1 are provided with a screw stirring device. The drying chamber is provided with an air inlet to introduce dry air. The separation device 2 is respectively connected with the sludge pulverization and drying device 1 and the condensation dehumidifier 3 . The air heat pump 4 is respectively connected with the condensation dehumidifier 3 and the sludge pulverizing and drying device 1 . The air inlet is connected to the air heat pump 4 .

The excess sludge to be treated with a moisture content of 35% to 50% is added to the sludge pulverization and drying device 1 through the feeding device, so that the sludge to be treated is firstly pulverized and broken into particle sizes by the screw stirring device in the pulverizing chamber. It is 30～250μm sludge powder. Then, dry air is introduced through the air inlet, and stirred for 8-20 minutes at the stirring intensity of 1500-3000r/min of the screw stirring device, so that the dry air and the sludge particles are mixed evenly and a sufficient gas-water exchange reaction occurs, so that the sludge The powder particles are dried to obtain dry sludge powder, and the moisture content is reduced to 15% to 25%. At the same time, the drying air becomes the low-temperature moist air entrained with the dry sludge powder. One of the embodiments is that the dry air is low-temperature dry air heated by ambient air, its humidity is 20% to 40%, and its temperature is 25°C to 50°C. % of low temperature moist air.

The low-temperature moisture-containing air carrying the dry sludge powder is passed through the separation device 2 for gas-powder separation, and the separated solid material is the dry sludge powder. Separation device 2 can choose dust collector. The separated low-temperature moisture-containing air enters the condensation, and at the same time, the cooling air is sent to the condensation dehumidifier 3 to exchange heat with the low-temperature moisture-containing air, so that the low-temperature moisture-containing air is condensed and dewatered to become low-temperature air, and the condensed water is discharged from the condensation dehumidifier. . The low and low temperature air is sent to the air heat pump 4 to be heated into dry air, and the dry air is sent to the sludge pulverization and drying device 1 to be mixed with the sludge powder under stirring conditions to dry the sludge powder. That is, the air is circulated among the air heat pump 4 , the sludge pulverization and drying device 1 , the separation device 2 and the condensation dehumidifier 3 . Usually after 10 cycles, it is used as exhaust gas, and it is discharged after purification treatment. At this time, fresh air is supplied from the air heat pump 4 .

The fresh air serves as a supplementary source for drying air on the one hand and cooling air on the other hand. First, the fresh air is used as a heat source in the air heat pump 4 to exchange heat with the low and low temperature air. When the low and low temperature air is heated to become dry air, the fresh air is cooled to become cooling air, and enters the condensing dehumidifier 3 as a cooling medium. The cooling air absorbs heat from the low-temperature humid air in the condensing dehumidifier 3 so that the temperature rises to become warm air, and then the warm air is sent to the air heat pump 4 as a heat source. In the above embodiment, the cooling air is 5°C to 15°C, and the temperature rises to 8 to 18°C after heat exchange.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. the sludge deep drying method based on air heat pump, which is characterized in that the described method includes:

Excess sludge to be processed is added in sludge dusting desiccation apparatus, pending mud is made to be broken into partial size 30 by dusting ~250 μm of sludge powder then passes to dry air and mixes under agitation with sludge powder, does sludge powder Change obtains sludge dry powder, while dry air becomes the low temperature entrainment of sludge dry powder containing humid air；

Gas solid separation, the solid matter separated will be carried out by separator containing humid air entrainment of the low temperature of sludge dry powder As sludge dry powder material；After low temperature after separation enters the condensation water removal of dehumidification by condensation device containing humid air, become low Cryogenic air；It will The low Cryogenic air is sent into air heat pump and is heated as dry air, and dry air feeding sludge dusting desiccation apparatus is existed It is mixed under stirring condition with sludge powder, sludge powder is made to carry out desiccation.

2. the sludge deep drying method according to claim 1 based on air heat pump, which is characterized in that the method is also Include:

Fresh air is sent into air heat pump and low Cryogenic air exchanges heat, makes fresh air cooling while becoming cooling air Low Cryogenic air heating becomes dry air；Sludge powder is dried in dry air feeding sludge dusting desiccation apparatus, Realize the recycling of dry air.

3. the sludge deep drying method according to claim 2 based on air heat pump, which is characterized in that the method is also Include:

Cooling air is sent into the dehumidification by condensation device and the low temperature wall-type heat exchange containing humid air, keeps low temperature cold containing humid air Become low Cryogenic air after solidifying water removal, while becoming warm air after cooling air heating；Warm air is sent into air heat pump As heat source for the heat exchange heating of low Cryogenic air, while warm air cooling becomes cooling air again and returns to the dehumidification by condensation Device is reused.

4. the sludge deep drying method according to claim 1 based on air heat pump, which is characterized in that described remaining dirty The moisture content of mud is 35%~50%；The moisture content of the sludge dry powder is 15%~25%.

5. the sludge deep anhydration system based on air heat pump can be used in implementing such as the described in any item bases of Claims 1-4 In the sludge deep drying method of air heat pump, which is characterized in that the system comprises sludge dusting desiccation apparatus (1), separation Device (2), dehumidification by condensation device (3) and air heat pump (4)；The sludge dusting desiccation apparatus (1) include connection dusting room and Desiccation room, the dusting room are equipped with feeding device；The separator (2) respectively with the sludge dusting desiccation apparatus (1) and Dehumidification by condensation device (3) is connected；The air heat pump (4) fills with the dehumidification by condensation device (3) and the sludge dusting desiccation respectively (1) is set to be connected.

6. the sludge deep anhydration system according to claim 5 based on air heat pump, which is characterized in that the sludge powder Change in the dusting room and desiccation room of desiccation apparatus (1) and is provided with spiral agitator；The desiccation room is equipped with air inlet and institute Air heat pump (4) are stated to be connected.