CN105276603B - Coal sludge mixture burning control system based on high temperature flue gas drying and Geldart-D particle - Google Patents

Abstract

The invention relates to a coal-sludge co-firing system based on high-temperature flue gas drying and pneumatic conveying. The sludge storage bin is connected to the spray drying pipe through a screw pump, and the air inlet of the spray drying pipe is connected to the cyclone separator of the circulating fluidized bed boiler. The outlet flue is connected, the outlet one of the spray drying pipe is connected to the rotary feeder one, the outlet two of the spray drying pipe is connected to the cyclone separator, and the exhaust port of the cyclone separator is connected to the circulating fluidized bed boiler through the cooling condenser and the exhaust fan, and the cyclone is separated The discharge port of the rotary feeder is connected to the second rotary feeder; the limestone silo is connected to the third rotary feeder, and the outlets of the first rotary feeder, the second rotary feeder and the third rotary feeder are connected to the inlet of the jet feeder. The inlet of the feeder is connected with the Roots blower, and the outlet of the jet feeder is connected with the circulating fluidized bed boiler. The invention can realize functions such as sludge drying and transportation, waste heat utilization of drying tail gas, co-firing of sludge and coal, and pollutant control, which is beneficial to prevent the diffusion of odor and dust, and has the characteristics of simple system, environmental protection and high efficiency.

Description

Coal-sludge co-combustion system based on high temperature flue gas drying and pneumatic conveying

technical field

The invention relates to a waste disposal system, in particular to a system for drying sludge and co-firing with coal.

Background technique

With the increasing amount of urban sewage generation and treatment, the sludge produced in the process of urban sewage treatment is also increasing day by day. Sludge is a floc composed of water, organic particles and inorganic particles, which contains a large amount of heavy metals, pathogens and refractory toxic organic substances, and emits odor. Therefore, sludge must be properly disposed of.

Sludge pretreatment includes conditioning, concentration, dehydration, stabilization, and drying technologies. The final disposal of sludge mainly includes landfill, land use, construction material utilization, biological treatment, and incineration. Pyrolysis, gasification, and Emerging technologies such as thermal hydrolysis are also being researched and developed. Due to the increasing requirements for soil protection, groundwater protection and food safety, the application of traditional technologies such as landfill and land use is facing more and more constraints, and incineration and other new technologies for sludge disposal are developing rapidly.

According to the fuel used in the incineration system, sludge incineration can be divided into two types: separate incineration and mixed incineration with other fuels; according to whether drying treatment is carried out, sludge incineration is divided into two types: direct incineration and incineration after drying; Incineration device, sludge incineration can be divided into grate furnace incineration, fluidized bed incineration, melting furnace incineration, rotary kiln incineration and power plant boiler mixed combustion.

Since the dewatered sludge from the sewage treatment plant generally has high water content and low calorific value, when it is directly burned in the furnace, it needs more auxiliary fuel, the proportion of mixed sludge is low, and the treatment scale is small. The loss of smoke exhaust is large, and the thermal efficiency decreases. Drying the dewatered sludge and then incinerating it in the furnace can improve the stability of the combustion in the furnace and the scale of treatment.

Drying-incineration technology widely uses low-pressure steam from power plants and other heating media to heat dewatered sludge with high moisture content from sewage treatment plants, so that the water in the sludge can be further evaporated to obtain sludge with low moisture content and high calorific value. The dried sludge is then sent to the boiler for incineration through the dried sludge feeding system; the high-temperature flue gas generated by the incineration is discharged after heat recovery and purification treatment, so as to realize the volume reduction, volume reduction and harmlessness of the sludge.

There are three typical processes in sludge thermal drying: direct drying, indirect drying and combined drying. Direct drying means that during the operation process, the heat medium (hot air, hot flue gas or hot ash, etc.) is in direct contact with the sludge, and the heat medium flows through the sludge layer at a low speed, absorbing the moisture in the sludge during the process, and treating The final dry sludge needs to be separated from the heat medium. Part of the exhausted exhaust gas is returned to the original system through the heat recovery system for reuse, and the remaining part is discharged after being harmless. In the indirect drying process, the heat medium does not directly contact the sludge, but transfers heat to the sludge through a heat exchanger to evaporate the water in the sludge. The heat medium is generally 160-200°C saturated water vapor or heat conduction Oil. The water evaporated during the process is condensed in the condenser, and part of the heat medium is returned to the original system for reuse to save energy. Direct-indirect combined drying combines the above two technologies.

Among several commonly used furnace types in sludge incineration, grate furnaces, melting furnaces and rotary kilns have relatively small processing capacity; large fluidized bed boilers and pulverized coal boilers consume a lot of fuel, even with a low proportion of mixed combustion The amount of sludge that can be treated is still large, and the low proportion of sludge blended will not affect the safe operation of the boiler. The combustion in the furnace is stable, the temperature is high, and the pollutants are completely decomposed. Moreover, these power plants Boilers are often equipped with advanced flue gas purification systems, which can purify the pollutants brought about by sludge combustion. It can be seen that the co-processing of sludge by using power plant boilers has a good application prospect.

Combined with different sludge drying and incineration methods, in the sludge drying-incineration project that has been put into operation, steam drying-fluidized bed incineration, steam drying-coal pulverized boiler combustion, flue gas drying -Different process routes such as rotary kiln incineration. Since most of the projects are technical transformation of the boiler units that have been in operation for many years, and the addition of sludge storage, drying and conveying systems, the needs of sludge incineration were not considered when the boiler units were originally designed, so the additional sludge drying The workshop generally adopts the indirect steam drying process, and the distance between its position and the boiler is usually far away. It is necessary to transfer the dried sludge to the coal yard of the power plant for storage, and then send it to the pulverizing system by belt conveyor, or directly Sent into the furnace for incineration. This leads to complex system process, many equipments, large floor area and high investment cost; and because the dried sludge will emit dust and odor during the stacking and transportation process, and the sealing performance of the belt conveying system is poor, Therefore, it is easy to cause odor to spread in the factory area and nearby areas, resulting in poor working environment and seriously affecting the enthusiasm of the power plant for incinerating sludge. At present, there is also a sludge flue gas drying-pulverized coal boiler co-firing process scheme based on the fan mill pulverization system, but the gas-powder mixture produced during the process of drying the sludge in the fan mill and grinding it into powder has a strong The irritating smell, corrosiveness and high dust concentration make it difficult to separate the gas and powder, and the explosion-proof requirements are relatively high, so there is no engineering application yet.

Therefore, in view of the needs of power plants for incinerating sludge, it is necessary to develop a sludge drying and incineration power generation system with a simple system, a short process, and environmental protection and efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to provide a coal-sludge co-combustion system based on high-temperature flue gas drying and pneumatic conveying, which can stably dry sludge and realize the mixing of sludge and coal after drying. Incineration, effectively control the spread of odor and dust, and overcome the shortcomings of existing sludge incineration projects.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A coal-sludge co-combustion system based on high-temperature flue gas drying and pneumatic conveying, including sludge storage bin, screw pump, spray drying pipe, rotary feeder 1, cyclone separator 1, rotary feeder 2, Luo Ci fan, jet feeder, cooling condenser, exhaust fan, circulating fluidized bed boiler, limestone silo, rotary feeder 3. The outlet of the sludge storage bin is connected to the feed of the spray drying pipe through a screw pump The air inlet of the spray drying pipe is connected with the second outlet flue of the cyclone separator of the circulating fluidized bed boiler, and the high-temperature flue gas is extracted from the second outlet flue of the cyclone separator of the circulating fluidized bed boiler. Outlet one is connected to rotary feeder one, so that the heated and dried large-particle sludge that settles to the lower part of the drying pipe enters rotary feeder one, and outlet two of the spray drying pipe is connected to cyclone separator one to make the remaining sludge particles Together with the dry tail gas, it enters the cyclone separator 1 for gas-solid separation. The exhaust port of the cyclone separator 1 is connected to the circulating fluidized bed boiler through the cooling condenser and the exhaust gas fan in turn, so that the exhaust gas with high moisture content is cooled by the cooling condenser. After dehumidification, enter the dilute-phase zone of the circulating fluidized bed boiler through the exhaust fan for combustion, and the discharge port of the cyclone separator 1 is connected to the rotary feeder 2, so that the separated sludge particles enter the rotary feeder 2; The limestone silo is connected with the rotary feeder 3, so that the limestone particles in the limestone silo enter into the rotary feeder 3; The feed port of the jet feeder is connected to the inlet of the jet feeder, and the outlet of the jet feeder is connected to the circulating fluidized bed boiler, so that the drying from the first rotary feeder and the second rotary feeder After the sludge and limestone from the rotary feeder 3 enter the jet feeder, they are carried by the compressed air from the outlet of the Roots blower and sent to the dense phase zone of the circulating fluidized bed boiler to participate in combustion.

The feed port of the circulating fluidized bed boiler is connected to the coal feeding hopper through the coal feeder, so that the coal in the coal feeding hopper is sent to the dense phase zone of the circulating fluidized bed boiler for combustion through the coal feeder; the circulating fluidized bed boiler The outlet is connected to the chimney through the dust collector, desulfurization device and induced draft fan in turn.

The beneficial effects of the present invention are: adopting the above-mentioned technical scheme, the sludge is directly contact-dried by extracting high-temperature flue gas, compared with the currently widely used steam indirect drying technology, the drying rate and processing capacity of the sludge can be significantly improved, And through the cooling condenser to recover the waste heat of drying exhaust gas, reduce the energy consumption of drying, reduce the moisture brought into the boiler by sludge, thereby reducing the dew point temperature of the flue gas at the boiler outlet and the heat loss of exhaust flue gas, and improve the thermal efficiency of the boiler; the incineration equipment adopts circulating fluidization For bed boilers, the average particle size of the coal particles and sludge particles burned in the furnace can generally be controlled at the level of a few millimeters, and there is no need to use equipment such as fan mills to grind the sludge to a particle size of microns, thereby reducing spray drying. The difficulty of sludge granulation at the pipe inlet and subsequent gas-solid separation; the extraction of high-temperature flue gas from the outlet flue of the circulating fluidized bed boiler cyclone separator, and the extraction of high-temperature flue gas near the outlet of the pulverized coal boiler furnace in the fan mill drying system Ratio, greatly reducing the impact of high-temperature flue gas extraction on boiler heating surface steam temperature deviation and work safety; can give full play to the desulfurization, denitrification and dust removal functions of circulating fluidized bed boilers, and effectively control pollutant emissions from sludge blending; The pneumatic conveying method is used to convey the dried sludge and limestone, which is conducive to improving the airtightness of the conveying process, preventing the leakage of odor and dust into the environment, and does not need to set up a dry sludge storage bin, which improves the feeding of the furnace. Flexibility in equipment placement.

Therefore, the coal-sludge co-combustion system based on high-temperature flue gas drying and circulating fluidized bed boiler proposed by the present invention integrates sludge drying, incineration and pollutant control functions, and has the characteristics of simple system, environmental protection and high efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present invention.

detailed description

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

As shown in Figure 1, the coal-sludge co-combustion system based on high-temperature flue gas drying and pneumatic conveying of the present invention includes a sludge storage bin 1, a screw pump 2, a spray drying pipe 3, a rotary feeder-4, Cyclone separator 1, rotary feeder 2 6, Roots blower 7, jet feeder 8, cooling condenser 9, exhaust fan 10, circulating fluidized bed boiler 11, coal hopper 12, coal feeder 13 , limestone bin 14, rotary feeder three 15, dust collector 16, desulfurization device 17, induced draft fan 18 and chimney 19.

The outlet of coal feeder 12 is connected to coal feeder 13, the outlet of coal feeder 13 is connected to circulating fluidized bed boiler 11, and the outlet of circulating fluidized bed boiler 11 is connected to dust collector 16, desulfurization device 17, induced draft fan 18, chimney 19 are connected in turn.

The sludge storage bin 1 is connected to the screw pump 2, the outlet of the screw pump 2 is connected to the feed port of the spray drying pipe 3, and the air inlet of the spray drying pipe 3 is connected to the second outlet flue of the cyclone separator of the circulating fluidized bed boiler 11 Connection, the outlet one of the spray drying pipe 3 is connected with the rotary feeder one 4, the outlet two of the spray drying pipe 3 is connected with the cyclone separator one 5, and the discharge port of the cyclone separator one 5 is connected with the rotary feeder two 6 , the exhaust port of the cyclone separator one 5 is connected to the cooling condenser 9 and the exhaust fan 10 in sequence, and the outlet of the exhaust fan 10 is connected to the circulating fluidized bed boiler 11.

The limestone silo 14 is connected to the rotary feeder 3 15, the outlets of the rotary feeder 1 4, the rotary feeder 2 6 and the rotary feeder 3 15 are connected to the feed port of the jet feeder 8, and the jet feeder The air inlet of 8 is connected with Roots blower 7, and the outlet of jet feeder 8 is connected with circulating fluidized bed boiler 11.

The working principle of the coal-sludge co-firing system based on high-temperature flue gas drying and circulating fluidized bed boiler is:

The sludge stored in the sludge storage bin 1 is transported to the spray drying pipe 3 through the screw pump 2, and the high-temperature flue gas is extracted from the second outlet flue of the cyclone separator of the circulating fluidized bed boiler 11 as the sludge drying medium, and enters the spray drying pipe. The drying pipe 3 heats and dries the sludge, and the large-particle sludge settles to the lower part of the drying pipe 3 and enters the rotary feeder-4, and the remaining sludge particles and the drying tail gas enter the cyclone separator-5 together for gas-solid separation. The exhaust gas with high humidity is cooled and dehumidified by the cooling condenser 9, and enters the dilute phase zone of the circulating fluidized bed boiler 11 through the exhaust fan 10 for combustion, and the separated sludge particles enter the rotary feeder 2 6; the limestone bin 14 The limestone particles in the rotary feeder enter the three 15 of the rotary feeder; after the dried sludge from the first rotary feeder 4 and the second 6 of the rotary feeder and the limestone from the three 15 of the rotary feeder enter the jet feeder 8, the The compressed air from the outlet of the Roots blower 7 is carried into the dense-phase area of the circulating fluidized bed boiler 11 to participate in combustion; After the dust is removed, it enters the desulfurization device 17, further removes SOx in the flue gas, and then enters the chimney 19 through the induced draft fan 18 for discharge.

This system has the following characteristics:

(1) Compared with the steam indirect drying system, the high-temperature flue gas is extracted as the desiccant of the sludge, the drying rate of the direct contact between the sludge and the flue gas is high, the system process is simple, and the equipment occupies a small area;

(2) By changing the rotation speed of the exhaust fan to adjust the high-temperature flue gas extraction volume, it can meet the needs of different sludge drying loads. Compared with the two-media drying system that simultaneously extracts high-temperature flue gas and low-temperature flue gas, the flue gas pipeline is reduced, The total flue gas extraction volume is reduced, the operating characteristics of the boiler are easy to control, and the system is more economical when the sludge drying load changes less;

(3) The incineration equipment adopts a circulating fluidized bed boiler. Compared with the pulverized coal furnace, the average particle size of the coal particles and sludge particles burned in the furnace is larger, which reduces the sludge granulation at the entrance of the spray drying tube and the subsequent gas consumption. The difficulty of solid separation; extracting high-temperature flue gas from the outlet flue of circulating fluidized bed boiler cyclone separator also reduces the impact of high-temperature flue gas extraction on the deviation of steam temperature on the heating surface of the boiler and work safety;

(4) The condensed water of the unit can be used as the cooling medium in the cooling condenser to recover the waste heat of the waste gas after the sludge is dried, reduce the drying energy consumption, and reduce the moisture brought into the boiler by the sludge, thereby reducing the dew point temperature of the flue gas at the boiler outlet and the exhaust gas. Smoke heat loss, improve boiler thermal efficiency.

(5) Pneumatic conveying is used to convey dried sludge and limestone. Compared with belt conveying and screw conveying, it is beneficial to improve the airtightness of the conveying process and prevent odor and dust from leaking into the environment. No need to install Dried sludge storage bins improve the flexibility of the layout of feeding equipment in front of the furnace.

Therefore, the coal-sludge co-combustion system based on high-temperature flue gas drying and circulating fluidized bed boiler can realize sludge drying and transportation, waste heat utilization of drying tail gas, co-combustion of sludge and coal, and pollutant control functions. It is beneficial to prevent the spread of odor and dust, and has the characteristics of simple system, environmental protection and high efficiency. It is a new type of sludge disposal system.

Claims (3)

1. a kind of coal based on high temperature flue gas drying and Geldart-D particle-sludge mixture burning control system, including warehouse of sludge（1）, screw pump （2）, spray drying pipe（3）, rotary feeder one（4）, cyclone separator one（5）, rotary feeder two（6）, roots blower （7）, injection loader（8）, cooling condenser（9）, weary gas blower fan（10）, CFBB（11）, Limestone silo（14）、 Rotary feeder three（15）, it is characterised in that：The warehouse of sludge（1）Discharging opening passes through screw pump（2）Connection spray drying pipe （3）Charging aperture, spray drying pipe（3）Air inlet and CFBB（11）The exhaust pass of cyclone separator two connect Connect, from CFBB（11）The exhaust pass extracting high-temperature flue gas of cyclone separator two as drying sludge medium, carry High drying sludge speed, reduces fume extraction amount, mitigates high-temperature flue gas and extracts to boiler heating surface Temperature Deviation and work safety The influence of property；The spray drying pipe（3）Outlet one connection rotary feeder one（4）, make to be deposited to drying tube（3）Bottom The bulky grain sludge by heated drying enter rotary feeder one（4）, the spray drying pipe（3）The connection of outlet two whirlwind point From device one（5）, make remaining mud granule and dry tail gas together into cyclone separator one（5）Carry out gas solid separation, whirlwind point From device one（5）Exhaust outlet pass sequentially through cooling condenser（9）, weary gas blower fan（10）Connect CFBB（11）, make Height is containing wet weary gas through cooling down condenser（9）Cool-down dehumidification, reclaims and dries the waste heat of weary gas to heat unit condensate, reduction is dry Dry energy consumption, reduces sludge and brings CFBB into（11）Moisture, so as to reduce CFBB（11）Export cigarette Gas dew-point temperature and heat loss due to exhaust gas, improve the thermal efficiency；Weary gas after cool-down dehumidification passes through weary gas blower fan（10）Into recycle stream Fluidized bed boiler（11）Dilute-phase zone burning, by changing the rotational speed regulation high-temperature flue gas rate of air sucked in required of weary gas blower fan, meet different dirts The need for mud drying load.

2. the coal based on high temperature flue gas drying and Geldart-D particle-sludge mixture burning control system according to claim 1, its feature exists In：The CFBB（11）Charging aperture passes through feeder（13）Connect feeding-coal bucket（12）, make feeding-coal bucket（12）In Coal is through feeder（13）Send into CFBB（11）Emulsion zone burning；The CFBB（11）Outlet Pass sequentially through deduster（16）, desulfurizer（17）, air-introduced machine（18）Connect chimney（19）.

3. the coal based on high temperature flue gas drying and Geldart-D particle-sludge mixture burning control system according to claim 1, its feature exists In：

The cyclone separator one（5）Discharge port connection rotary feeder two（6）, the mud granule isolated is entered rotation Dispenser two（6）；Limestone silo（14）With rotary feeder three（15）Connection, makes Limestone silo（14）In limestone particle enter Enter rotary feeder three（15）；The rotary feeder one（4）, rotary feeder two（6）With rotary feeder three（15）Go out Mouth and injection loader（8）Charging aperture connection, spray loader（8）Air inlet and roots blower（7）Connection, injection feed Device（8）Outlet and CFBB（11）Connection, makes to come from rotary feeder one（4）, rotary feeder two（6）It is dry Change sludge and from rotary feeder three（15）Lime stone enter injection loader（8）Afterwards, by from roots blower（7）Outlet Compressed air carry feeding CFBB（11）Emulsion zone participate in burning, improve course of conveying seal, prevent Only foul smell and dust are outwards leaked in environment.