CN112047597A

CN112047597A - Comprehensive treatment process and system for preparing gas fertilizer by combining biological drying and gasification of sludge

Info

Publication number: CN112047597A
Application number: CN202010904053.1A
Authority: CN
Inventors: 胡艳军; 仝克
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2020-09-01
Filing date: 2020-09-01
Publication date: 2020-12-08

Abstract

A comprehensive treatment process for preparing an air fertilizer by combining biological drying and gasification of sludge comprises the steps of firstly, dehydrating residual sludge with the water content of 80% by utilizing mechanical filter pressing, and reducing the water content to 55-65%; then carrying out biological drying and further dehydrating treatment on the wet sludge subjected to conditioning and filter pressing by using cheap and easily-obtained biomass powder, and reducing the water content to 30-40%; the addition of the biomass powder has the advantages of conditioning the characteristics of the sludge, improving the calorific value of the sludge and the like, the sludge is sent into a low-temperature gasification furnace after secondary dehydration to finally obtain the carbon fertilizer, and high-temperature tar gas generated in the treatment process is subjected to photocatalytic cracking, adsorption, purification and purification to obtain high-quality synthesis gas. And provides a comprehensive treatment system for preparing the air fertilizer by combining biological drying and gasification of the sludge. The invention provides a comprehensive treatment process and a system for preparing an air fertilizer by combining biological drying and gasification of sludge, which have the advantages of stable and reliable operation, easy operation, environmental protection and energy conservation.

Description

Comprehensive treatment process and system for preparing gas fertilizer by combining biological drying and gasification of sludge

Technical Field

The invention relates to a synergistic preparation treatment process and system for energy-saving deep drying and gasification of sludge to prepare synthetic fuel gas and carbon fertilizer, and belongs to the technical field of sludge energy treatment.

Background

Since the innovation, along with the development of the social economy and the rapid development of the urbanization of China, the population number is increasing day by day, the urbanization level is increasing continuously, the number and the scale of urban sewage plants are increasing continuously, the discharge amount and the treatment amount of urban sewage are rising rapidly, and the output of the byproduct sludge of sewage is also increasing remarkably. By 12 months in 2017, the sludge is accumulated in cities and counties in cities and cities arranged in the country to form 5027 sewage treatment plants, the sewage treatment capacity reaches 1.88 billion cubic meters per day, 5000 million tons of sludge with 80 percent of water content is produced every year, and the sludge yield breaks through 6000 million tons in 2020.

The water content of the sludge after the primary dehydration is still more than 80 percent, and the composition of the sludge is complex and generally contains heavy metals, bacterial thalli, parasites, toxic organic matters, nutrient substances and the like. Not only can pollute the environment and threaten human health, but also can waste useful resources in the sludge. Therefore, the sludge treatment is generally concerned all over the world, and how to scientifically and efficiently treat sludge with huge yield is one of the subjects of extensive research in China and even all over the world.

Currently, there are three main ways for sludge treatment and disposal worldwide: landfill, land utilization and incineration. According to the investigation of the Chinese environmental engineering research center, in the sludge treatment and disposal method in China, the agricultural use accounts for about 44.8%, land landfill accounts for about 31%, other disposal accounts for about 10.5%, and about 13.7% of the municipal sludge is returned to the nature without any treatment, and the reduction, stabilization and recycling of the sludge treatment are not realized.

Landfill is a mature disposal technology, has the advantages of no need of high dehydration (natural drying), less investment, quick effect, large capacity, strong adaptability and the like, is beneficial to popularization, and has a plurality of problems. For example, the land is seriously invaded, and suitable sites are difficult to select; toxic and harmful components can permeate into the ground, and the waste water and odor of the landfill site can cause secondary pollution to underground water, soil and surrounding environment; the nutrient substances contained in the sludge can also cause a large amount of pathogenic bacteria to propagate; the sludge landfill gas is not properly collected, which may cause explosion and the like. Therefore, these problems limit the development of sludge landfills.

The land utilization has the advantages of low energy consumption, low investment, low operating cost and the like, and the treated sludge can be used as a soil conditioner to replace part of artificial fertilizers which are produced by consuming a large amount of energy. However, considering whether the heavy metals in the sludge can cause secondary pollution to soil and crops and then enter human bodies through food chains, whether parasitic ova and virus pathogens in the sludge can influence public environmental sanitation, whether underground water can be polluted and the like, the land utilization of the sludge, particularly the agriculture of the sludge, is controversial.

In contrast, sludge incineration is a relatively new sludge treatment technology, which is a sludge treatment method in which sludge is heated under the condition of excessive air supply, and is oxidized and pyrolyzed at high temperature (850 to 1100 ℃) to thoroughly destroy organic substances, pathogens and other substances therein. The dewatered sludge is put into an incinerator for aerobic combustion, most organic matters in the sludge can be carbonized, and the sludge is remarkably reduced, so that harmful bacteria in the sludge are thoroughly killed by incineration, and heavy metals after the sludge is incinerated are in an oxidation state, and stable ash can be finally obtained.

And a patent (CN109111075A) which describes that the sludge drying gasification indirect heating is coupled with a coal-fired system for power generation, and the waste heat are recycled; and a patent (CN107721112A) which describes the self-sustaining combustion of drying, pyrolysis and gasification of municipal sludge, and the generated biomass gas is used as a preheating source for recycling; and a patent (CN103319065A) which explains that self-sufficiency of energy is realized by utilizing the self heat value of sludge, and the treatment combining sludge drying and gasification is carried out, so that the reduction and resource treatment of the sludge are realized.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a comprehensive treatment process and a system for preparing an air fertilizer by combining sludge biological drying and gasification, which have the advantages of stable and reliable operation, easy operation, environmental protection and energy conservation.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a comprehensive treatment process for preparing an air fertilizer by combining biological drying and gasification of sludge comprises the steps of firstly, dehydrating residual sludge with the water content of 80% by utilizing mechanical filter pressing, and reducing the water content to 55-65%; then carrying out biological drying and further dehydrating treatment on the wet sludge subjected to conditioning and filter pressing by using cheap and easily-obtained biomass powder, and reducing the water content to 30-40%; the addition of the biomass powder has the advantages of conditioning the characteristics of the sludge, improving the calorific value of the sludge and the like, the sludge is sent into a low-temperature gasification furnace after secondary dehydration to finally obtain the carbon fertilizer, and high-temperature tar gas generated in the treatment process is subjected to photocatalytic cracking, adsorption, purification and purification to obtain high-quality synthesis gas.

Preferably, the synthesis gas can be directly combusted on site to recycle heat, and the residual heat of the flue gas generated after direct combustion is used as the heat required by biological drying.

Preferably, the whole process forms closed-loop treatment of energy, can realize reduction, stabilization and energy conversion treatment of sludge, furthest reduces pollutant discharge in the sludge treatment process, and improves the sludge resource conversion efficiency.

Further, the comprehensive treatment process comprises the following steps:

(1) firstly, carrying out primary mechanical plate and frame filter pressing on wet sludge with water content of 80% in a sewage treatment plant, and reducing the water content of the sludge to 55-65%;

(2) the sludge subjected to filter pressing by the mechanical plate frame is sent to a skid-mounted sludge biological drying bin device, low-price and easily-obtained biomass powder and wet sludge are mixed, stirred and conditioned, wherein heat required in the biological dehydration process is derived from the waste heat of flue gas of a water heating system and is supplied to hot air required in the biological drying process; stirring the wet sludge and the biomass powder stack by using a variable frequency stirrer, fermenting while stirring, further dehydrating the sludge after biological conditioning by using a rotary screw extruder in a drying bin, and reducing the water content to about 30-40% after dehydration;

(3) after biomass conditioning and biological drying dehydration, the water content of the sludge is 30-40%, the conditioned sludge is sent into a gasification furnace, the gasification temperature is controlled to be 550-700 ℃, the conditioned sludge is gasified by oxygen enrichment (industrial waste oxygen can be selected on site) or water vapor (industrial waste water vapor), and in addition, industrial waste heat can be selected on site to be used as part of energy consumption of gasification;

(4) the purified crude synthesis gas enters a photocatalytic cracking reaction device, so that macromolecular organic matters can be further decomposed into micromolecular combustible gas components, and the gas quality of the gasified synthesis gas is improved;

(5) introducing the synthesis gas subjected to photocatalytic treatment into an adsorption purification device to further remove CO in the synthesis gas₂And NO₂And combustible synthesis gas with higher quality is obtained.

Further, the process also comprises the following steps:

(6) the obtained high-quality synthetic gas is sent into a gas boiler system and is combusted together with auxiliary gas to prepare hot water, and the waste heat of the flue gas of the hot water system can also be used for biological drying of sludge.

Furthermore, in the step (2), the main structure of the skid-mounted sludge biological drying bin is made of light steel, HDPE (high-density polyethylene) plates and polyurethane, so that the requirement on overall strength is met, and a good heat-insulating effect is achieved; the peripheral walls of the biological drying bin are sealed, and one side wall is provided with an opening door, so that the material is conveniently discharged; the device is relatively closed, two variable frequency blowers are adopted to carry out forced ventilation on the stockpile, the top of the reactor is provided with an air exhaust hole, a large amount of water vapor and harmful gases generated in the biological drying process are exhausted out of the closed bin through an induced draft fan, condensed and deodorized and then discharged, and a micro-negative pressure state is formed in the reactor; the position of a jack and a sampling position of a temperature instrument and the like are respectively arranged on one side wall of the drying bin and the bottom of the stack body;

the start and stop of the blower adopts a time relay to set the aeration duration and the aeration interval or can feed back the aeration duration and the aeration interval to a PC control system through a temperature probe according to the setting of the temperature; the start and stop of the induced draft fan are controlled in a linkage mode with the air blower and in a dual mode of a pressure feedback system, and a dual mode PLC control system can be switched according to test requirements;

the blower is used for ventilating warm air to the stockpile, and firstly, oxygen required by the growth and metabolism of aerobic fermentation microorganisms is provided; secondly, regulating the temperature of the pile body and controlling the activity of microorganisms; thirdly, removing redundant moisture in the materials;

the stirring device is used for uniformly mixing the materials, turning the materials in the process of fermenting the materials, and generating stirring force through the rotation of the blades on the rotating shaft;

and tail gas is pumped out by the draught fan, water vapor in the gas is exhausted through the U-shaped pipe, and toxic gas is discharged after being treated by activated carbon of a tail gas absorption system.

Further, in the step (3), the gasification process of the conditioned sludge in the gasification furnace comprises the following steps:

the semi-dry sludge (with the water content of 30-40%) after biological conditioning, dehydration and mechanical filter pressing is fed into a gasification furnace from a feeding bin in a spiral feeding mode, secondary air supply is adopted in the gasification furnace, and the gasification medium is O₂Steam, the most economical way is to use the waste oxygen or waste steam of some plants, and to input O in the reactor₂And a gasification medium such as steam to complete the gasification reaction; the method comprises the following steps that firstly, crude synthesis gas generated by a gasification reactor is sent into a dust remover for dust removal, then the crude synthesis gas is sent to a next-stage treatment system to obtain relatively pure synthesis gas, solids removed in the dust remover return to the bottom of a gasification furnace, and ash is discharged through a spiral ash remover; wherein the temperature of the gasifier bed is maintained at 550 ℃, the temperature is controlled to ensure that the ash melting point is not exceeded, and the temperature of the upper suspension section of the bed may be quite high; in the whole gasification process, the pressure in the system is controlled to be in a normal pressure state, and the pressure regulation cabinet is adopted to monitor the internal pressure change of the gasification system in real time.

Preferably, in the step (4), the gasified tar photocatalytic cracking device comprises an outer cylinder and an inner cylinder sleeved on the outer cylinder, wherein a light heating furnace layer is arranged on the inner side surface of the inner cylinder, a catalyst layer is arranged inside the inner cylinder, and a spiral heat exchange layer is arranged between the outer cylinder and the inner cylinder corresponding to the position of the light heating furnace layer;

the device adopts the inner and outer cylinder bilayer structure, carries out catalytic cracking to tar in the gasified gas, and has simple and compact structure and convenient operation, and can be very easily connected to the reactor rear end of the gasification furnace. And, the double-deck design of interior outer tube adds spiral heat transfer, makes the heat in the light heating furnace outside return to the catalyst layer again through spiral heat transfer layer, and the heat obtains make full use of, has reduced the heat loss, has improved catalytic cracking efficiency, can further realize that macromolecule organic matter decomposes into micromolecular combustible gas component, promotes the gasification synthesis gas quality.

Preferably, in the step (5), the purpose of the synthesis gas purification device is to purify the raw synthesis gas to remove the non-combustible components as much as possible, so as to prepare qualified purified synthesis gas for the combustible gas synthesis device, and the process is described as follows:

the crude synthesis gas enters a low-temperature methanol washing unit after partial conversion and process waste heat recovery, and after most of hydrogen sulfide, organic sulfur and carbon dioxide are removed in the low-temperature methanol washing unit, the crude synthesis gas enters a fine desulfurization unit to reduce the total sulfur content and is sent to a downstream oil product or fuel gas synthesis device. Carbon dioxide desorbed from the low-temperature methanol washing unit is treated by CO₂The compressed gas is returned to the gasification device as gas for coal transportation and then is sent to the boiler for combustion.

A sludge biological drying and gasification cooperated gas fertilizer co-production comprehensive treatment system comprises a sludge mechanical plate and frame filter-press dehydration system I, a skid-mounted sludge biological drying bin device II, a conditioning sludge gasification system III, a photocatalytic cracking reaction system IV and an adsorption purification system V;

the mechanical plate frame filter-pressing dehydration system I for the sludge comprises a thrust plate, a filter plate and a filter frame, a cross beam, a hold-down plate, a hydraulic cylinder seat, a locking device, a material conveying pipe, a machine foot, a machine base, a water inlet flange and a hydraulic station, wherein the mechanical plate frame filter press comprises a group of filter chambers formed by the filter plates and the filter frames which are alternately arranged, the surface of each filter plate is provided with a groove structure, the convex part of each filter plate is used for supporting filter cloth, the corners of the filter plates and the filter frames are respectively provided with a through hole which are assembled to form a complete channel, washing water and suspension can be introduced in and filtrate is led out, the two sides of the filter plates and the filter frames are respectively provided with a handle which is supported on the cross beam, the hold-down plate and the frames are arranged by the hold-down plate device, the filter cloth between the plates and the frames plays the role of a sealing gasket, the hydraulic cylinder and the hydraulic cylinder seat, after filtering, introducing clean washing water to wash filter residue; after washing, compressed air is needed to be introduced to remove the residual washing liquid, then the filter press can be opened to remove filter residues, filter cloth is cleaned, the filter plates and the filter frames are compressed again to carry out the next work cycle, and the sludge after filter pressing and dehydration is introduced into the hydraulic station through the material conveying pipe and is discharged after pressurization;

the skid-mounted sludge biological drying bin device II comprises a feeding hole, an air suction opening, a temperature and pressure regulating cabinet controller, a material, a pile turning roller, an air supply opening, a sealed biological drying bin, a PC system controller, a stirrer, an air outlet, a temperature probe and a discharging hole; the sealed biological drying bin is relatively sealed, a variable frequency blower is adopted to forcibly ventilate the stockpile through an air supply outlet, a feed inlet and an air exhaust hole are formed in the top of the reactor, a large amount of water vapor and harmful gas generated in the sludge biological drying process are exhausted out of the sealed bin through an air outlet by a draught fan, the water vapor in the gas is exhausted through a U-shaped pipe, and the toxic gas is treated by activated carbon of a tail gas absorption system and then is exhausted, so that a micro negative pressure state is formed in the drying bin; the start and stop of the blower adopts a time relay to set the aeration duration and the aeration interval or can control the double modes fed back to the temperature controller and the PC controller through the temperature probe according to the setting of the temperature, so that the pressure and the temperature reach the specified set range, wherein the stirring device and the pile turning roller uniformly mix the materials, the materials are turned in the fermentation process of the materials, and stirring force is generated by the rotation of the blades on the rotating shaft;

the conditioning sludge gasification system III comprises a lock hopper bin, a primary air supply port, a feeder, a temperature and pressure regulating cabinet controller, a secondary air supply port, a spiral ash removal device, a coal lock hopper, a refractory lining, a crude synthesis gas cooler, a cyclone dust collector, a stirrer, a grate driver and a slag quenching chamber; the semi-dry sludge after biological drying dehydration and mechanical filter pressing and the cosolvent are sent into a gasification furnace from a lock hopper through a feeder in a spiral feeding mode, the coal lock hopper at the top of the gasification furnace is fed periodically, a container of the gasification furnace is provided with a refractory lining material to prevent heat loss caused by excessive bed layers, and the refractory material is separated from the hottest part of the bed layers by the furnace bed and is not subjected to high temperature; after entering the gasification furnace, the fuel is fully mixed with a gasification agent introduced from a primary air supply port and a secondary air supply port, the fuel leaves the gasification furnace after being dried, gasified and combusted in different bed layers of a fuel bed, enters a cyclone dust collector for filtering and dust removal, then is introduced into a crude synthesis gas cooler for cooling and discharging, and the residual slag is cooled through a slag quenching chamber through a series of processes and then is discharged out of the furnace;

the photocatalytic cracking reaction system IV comprises a sealed feeding bin, a screw extrusion feeder, a liquid inlet control valve, a gas inlet, an electric rotor, a fractionator, a liquid outlet control valve, a solid reactant discharge device, a stripping pipe, a catalytic cracking furnace, a settling pipe, a separation tank and a cooling water outlet valve; synthetic gasified gas is introduced into the catalytic cracking furnace through the sealed feeding bin and the spiral extrusion feeder, oil gas in the synthetic gas is fractionated through a fractionator, the oil gas and the steam introduced from the gas inlet are mixed for catalytic cracking reaction, light energy is used as energy for catalytic cracking, the synthetic gas after the reaction is introduced into a separation tank through a stripping pipe, the oil gas and the catalyst in the synthetic gas are separated, and relatively pure gasified gas is obtained;

the adsorption purification system V comprises a temperature and pressure regulating cabinet controller, a cyclone separator, a waste gas outlet, a cooler, a flowmeter, an adsorption section and a throttle valve; the gasified synthesis gas after the second-stage degradation is introduced into an adsorption purification device to further remove CO in the gasified synthesis gas₂And NO₂The raw synthesis gas is subjected to partial conversion by a cyclone separator and a cooler and process waste heat recovery, wherein the waste gas is obtained from the waste gasAnd (4) discharging the synthesis gas from an outlet, removing most of hydrogen sulfide, organic sulfur and carbon dioxide from the synthesis gas through an adsorption section, introducing the synthesis gas into a boiler for combustion, and discharging the flue gas from the boiler through a flue gas outlet.

Furthermore, the comprehensive treatment system also comprises a synthesis gas combustion system VI, which comprises a flue gas waste heat utilization heat return pipe, a temperature and pressure regulation cabinet controller, an air inlet, a boiler main body part, an ash outlet and a combustor; the high-quality synthetic gas that absorption purification system V obtained is sent into gas boiler system, mixes with the burning of part supplementary gas by the primary air that the air intake sent into and prepares hot water, and hot water system's flue gas waste heat can be used to mud biological drying through flue gas waste heat backheat pipe, and the boiler includes combustor, boiler main part and cigarette ash export, temperature and pressure regulator cabinet controller is used for adjusting boiler internal parameter, guarantees its temperature operation.

The invention provides a novel sludge comprehensive treatment process and system for mechanical filter pressing, biological drying and gasification gas fertilizer production, and aims to realize reduction, harmless, recycling and stabilization treatment of sludge. The organic characteristics of sludge organisms are conditioned by utilizing the synergistic effect of the mixed matrix, so that biological drying is carried out, high-quality synthetic gas is obtained, the synthetic gas can be sent to a coal-fired boiler of a heating water system for direct combustion, a part of coal-fired load is replaced under the condition that the normal operation of the coal-fired boiler system is not influenced, and the sludge combustion heating water is realized. Moreover, the invention utilizes the sludge to prepare high-quality synthesis gas and carbon fertilizer, thereby not only reducing the environmental pollution caused by the discharge of organic solid wastes, but also utilizing renewable resources to create clean energy, and having low energy consumption and high energy efficiency.

The invention has the following beneficial effects:

(1) the invention adopts a novel sludge comprehensive treatment process of 'mechanical filter pressing, biological drying and gasification for preparing gas fertilizer', fully recycles the waste heat and industrial waste heat of a heating water system, is used for sludge dehydration and drying, improves the cyclic utilization rate of energy sources, and greatly reduces the system investment and the operation cost;

(2) adding low-price and easily-obtained biomass powder in the stage of biological dehydration and drying of the sludge, so that the physical and chemical properties of the sludge are more uniform, and the combustion heat value is higher;

(3) the synthesis gas obtained by the process is subjected to catalytic cracking by using light as a heat source, and is purified by combining an adsorption technology to obtain high-quality synthesis gas, and then the synthesis gas is directly combusted, so that the energy consumption is low and the energy efficiency is high;

(4) the high-quality synthesis gas enters a coal-fired boiler of a hot water system for combustion, and the waste heat of the flue gas generated by the hot water system is sent into a sludge biological drying closed bin device for cyclic utilization;

(5) the gas fertilizer is co-produced, and the produced carbon fertilizer can be used for greening, mine restoration and the like, so that the pollutant emission in the sludge drying and gasifying process is greatly reduced, and the full utilization of energy is realized.

Drawings

FIG. 1 is a flow chart of a comprehensive treatment process for producing air fertilizer by combining sludge biological drying and gasification.

FIG. 2 is a schematic view of a comprehensive treatment system for producing air fertilizer by combining sludge biological drying and gasification.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1 and 2, a comprehensive treatment process for preparing an air fertilizer by combining biological drying and gasification of sludge comprises the steps of firstly dehydrating residual sludge with the water content of about 80% by using mechanical filter pressing, and reducing the water content to 55-65%; then carrying out biological drying and further dehydrating treatment on the wet sludge subjected to conditioning and filter pressing by using cheap and easily-obtained biomass powder, and reducing the water content to 30-40%; the addition of the biomass powder has the advantages of conditioning the characteristics of the sludge, improving the calorific value of the sludge and the like, the sludge is sent into a low-temperature gasification furnace after secondary dehydration to finally obtain the carbon fertilizer, and high-temperature tar gas generated in the treatment process is subjected to photocatalytic cracking, adsorption, purification and purification to obtain high-quality synthesis gas.

Further, the comprehensive treatment process comprises the following steps:

(2) the sludge subjected to filter pressing by the mechanical plate frame is sent to a skid-mounted sludge biological drying bin device, in order to better realize the biological dehydration effect of the sludge, low-price and easily-obtained biomass powder and wet sludge are mixed, stirred and conditioned, wherein the heat required in the biological dehydration process is derived from the waste heat of the flue gas of a water heating system and is supplied to the biological drying process; stirring the wet sludge and the biomass powder stack by using a variable frequency stirrer, fermenting while stirring, further dehydrating the sludge after biological conditioning by using a rotary screw extruder in a drying bin, and reducing the water content to 30-40% after dehydration;

the skid-mounted sludge biological drying bin adopts a main body structure made of light steel, HDPE plates, polyurethane and the like, so that the requirement on overall strength is met, and a good heat preservation effect is achieved; the peripheral walls of the biological drying bin are sealed, and one side wall is provided with an opening door, so that the material is conveniently discharged; the device is relatively closed, two variable frequency blowers are adopted to carry out forced ventilation on the stockpile, the top of the reactor is provided with an air exhaust hole, a large amount of water vapor and harmful gases generated in the biological drying process are exhausted out of the closed bin through an induced draft fan, condensed and deodorized and then discharged, and a micro-negative pressure state is formed in the reactor; the position of a jack and a sampling position of a temperature instrument and the like are respectively arranged on one side wall of the drying bin and the bottom of the stack body;

the start and stop of the blower adopts a time relay to set the aeration duration and the aeration interval or can feed back the aeration duration and the aeration interval to a PC control system through a temperature probe according to the setting of the temperature; the start and stop of the induced draft fan are controlled in a linkage mode with the air blower and in a dual mode with a pressure feedback system; the dual-mode PLC control system can be switched according to the test requirement;

the tail gas is pumped out by a draught fan, water vapor in the gas is exhausted through a U-shaped pipe, and the toxic gas is discharged after being treated by activated carbon of a tail gas absorption system;

(3) after biological dehydration and biomass conditioning, the water content of the sludge is about 35 percent, the conditioned sludge is sent into a gasification furnace, the gasification temperature is controlled to be 550-700 ℃, the conditioned sludge is gasified by oxygen enrichment (industrial waste oxygen can be selected on site) or water vapor (industrial waste water vapor), and in addition, industrial waste heat can be selected on site as the energy consumption of a gasification part;

the gasification process of the conditioned sludge in the gasifier is as follows:

the semi-dry sludge (with water content of about 35%) after biological conditioning, dehydration and mechanical filter pressing is fed into a gasification furnace by a spiral feeding mode from a feeding bin, the gasification furnace adopts secondary air supply, and the gasification medium can be O₂Steam, the most economical way is to use the waste oxygen or waste steam of some plants, and to input O in the reactor₂And a gasification medium such as steam to complete the gasification reaction. The method comprises the following steps of firstly sending the crude synthesis gas generated by the gasification reactor into a dust remover for dust removal, then sending the crude synthesis gas to a next-stage treatment system to obtain relatively pure synthesis gas, returning the solids removed in the dust remover to the bottom of the gasification furnace, and discharging ash through a spiral ash remover. Wherein the temperature of the gasifier bed is maintained at about 550 c, the temperature is controlled to ensure that its ash melting point is not exceeded, and the temperature of the upper suspension section of the bed may be quite high. In the whole gasification process, the pressure in the system is controlled to be in a normal pressure state, and the pressure regulation cabinet is adopted to monitor the internal pressure change of the gasification system in real time.

(4) The crude synthesis gas after purification treatment enters the photocatalytic cracking reaction device, can further realize the decomposition of macromolecular organic matters into micromolecular combustible gas components, improves the gas quality of the gasified synthesis gas, and is introduced by the photocatalytic cracking device as follows:

the gasified tar photocatalytic cracking device comprises an outer cylinder and an inner cylinder sleeved on the outer cylinder, wherein a light heating furnace layer is arranged on the inner side surface of the inner cylinder, a catalyst layer is arranged inside the inner cylinder, and a spiral heat exchange layer is arranged between the outer cylinder and the inner cylinder and corresponds to the position of the light heating furnace layer.

(5) The synthesis gas is treated by photocatalysis and then is introduced into an adsorption purification device to further remove CO in the synthesis gas₂And NO₂To obtain a higher quality combustible synthesis gas, the following is the main flow of the synthesis gas purification device:

the purpose of the synthesis gas purification device is to purify synthesis gas, remove non-combustible components as much as possible, and prepare qualified purified synthesis gas for the combustible gas synthesis device, and the process is described as follows:

the synthesis gas firstly enters a low-temperature methanol washing unit, after most of hydrogen sulfide, organic sulfur and carbon dioxide are removed in the low-temperature methanol washing unit, the synthesis gas enters a fine desulfurization unit to reduce the total sulfur content, and the synthesis gas is sent to a downstream oil product or combustible gas synthesis device. Carbon dioxide desorbed from the low-temperature methanol washing unit is treated by CO₂The compressed gas is returned to the gasification device as gas for coal transportation and then is sent to the boiler for combustion.

The whole sludge treatment system of the embodiment is closed loop from the energy flow perspective.

Referring to fig. 2, a sludge biological drying and gasification synergistic gas fertilizer co-production comprehensive treatment system comprises a sludge mechanical plate frame filter-pressing dehydration system I, a skid-mounted sludge biological drying bin device II, a conditioning sludge gasification system III, a photocatalytic cracking reaction system IV (a primary high-temperature gasification synthetic gas tar degradation system), an adsorption purification system V (a secondary gasification synthetic gas purification system) and a synthetic gas combustion system VI;

the mechanical sludge plate frame filter-pressing dehydration system I comprises a thrust plate 1, a filter plate 2, a filter frame, a cross beam 3, a compacting plate 4, a hydraulic cylinder 5, a hydraulic cylinder seat 6, a locking device 7, a material conveying pipe 8, a machine foot 9, a machine base 10, a water inlet flange 11 and a hydraulic station 12;

the skid-mounted sludge biological drying bin device II comprises a feed inlet 13, an air suction opening 14, a temperature and pressure regulating cabinet controller 15, a material 16, a turning drum 17, an air supply opening 18, a sealed biological drying bin 19, a PC system controller 20, a stirrer 21, an air outlet 22, a temperature probe 23 and a discharge opening 24;

the conditioning sludge gasification system III comprises a 25-lock hopper, a 26-primary air supply port, a 27-feeder, a 28-temperature pressure regulation cabinet controller, a 29-secondary air supply port, a 30-spiral ash removal device, a 31-coal lock hopper, a 32-refractory lining, a 33-crude synthesis gas cooler, a 34-cyclone dust collector, a 35-stirrer, a 36-grate, a 37-grate driver and a 38-slag quenching chamber;

the photocatalytic cracking reaction system IV (a first-stage high-temperature gasification synthesis gas tar degradation system) comprises a 39-sealed feeding bin, a 40-spiral extrusion feeding machine, a 41-liquid inlet control valve, a 42-air inlet, a 43-electric rotor, a 44-fractionator, a 45-liquid outlet control valve, a 46-solid reactant discharge device, a 47-stripping pipe, a 48-catalytic cracking furnace, a 49-settling pipe, a 50-separation tank and a 51-cooling water outlet valve;

the adsorption purification system V (a two-stage gasification synthesis gas purification system) comprises a temperature and pressure regulation cabinet controller 52, a cyclone separator 53, a waste gas outlet 54, a cooler 55, a flowmeter 56, an adsorption section 57 and a throttle valve 58;

the synthesis gas combustion system VI comprises 59-a flue gas waste heat utilization heat return pipe, 60-a temperature and pressure regulation cabinet controller, 61-an air inlet, 62-a boiler main body part, 63-an ash outlet and 64-a combustor.

In the mechanical plate-and-frame filter-pressing dehydration system I for sludge, the mechanical plate-and-frame filter press is a group of filter chambers formed by 2-filter plates and filter frames which are alternately arranged, the surfaces of the filter plates are provided with groove structures, and the protruding parts of the groove structures are used for supporting filter cloth. And 2, the corners of the filter plate and the filter frame are respectively provided with a through hole which are assembled to form a complete channel, washing water and suspension can be introduced, and filtrate is led out. 2-the two sides of the filter plate and the filter frame are respectively provided with a handle which is supported on the 3-beam, the 4-pressing plate device presses the plate and the frame, and the filter cloth between the plate and the frame plays the role of a sealing gasket. A5-hydraulic cylinder and a 6-hydraulic cylinder seat are arranged above the tail end of the cross beam and are fixed by a 7-locking device. And after the filtrate enters a plate-and-frame filter press, the filtrate passes through the filter cloth and flows to plate-and-frame corner channels along the grooves of the filter plates to be discharged in a concentrated manner, and after the filtration is finished, cleaning and washing the filter residue can be carried out. After washing, compressed air is needed to be introduced to remove the residual washing liquid, then the filter press can be opened to remove filter residues, the filter cloth is cleaned, the 2-filter plate and the filter frame are compressed again, and the next working cycle is carried out. The sludge after filter pressing and dehydration is led into a 12-hydraulic station through a 8-material conveying pipe, and is discharged out of the device after being pressurized.

The mechanical plate-and-frame filter press has very large compressibility of filter residues, so that the filter press can be suitable for almost incompressible suspensions, the concentration of solid particles of the selected suspensions is generally below 10%, the operating pressure is generally 0.3-0.6 MPa, and even the operating pressure can reach 3MPa or higher. The 2-filter plate and the filter frame are usually square, the inner side length of the filter frame is 320-2000 mm, the thickness of the filter frame is 16-80 mm, and the filter area is 1000-1200 cm². The 2-filter plate and the filter frame are made of materials such as wood, cast iron, cast steel, stainless steel, polypropylene, rubber and the like, and the compression mode is manual screw, electric screw, hydraulic pressure and the like.

In skid-mounted sludge biological drying storehouse II, its major structure adopts materials such as light steel, HDPE board, polyurethane cool, has both satisfied the requirement of bulk strength, has reached good heat preservation effect again. The biological drying bin is relatively closed, a variable frequency blower is adopted to carry out forced ventilation on the stockpile through an 18-air supply outlet, a 13-feed inlet and a 14-air exhaust hole are formed in the top of the reactor, a large amount of water vapor and harmful gases generated in the sludge biological drying process are exhausted out of the closed bin through a draught fan and a 22-air outlet, the water vapor in the gases is exhausted through a U-shaped pipe, and the toxic gases are discharged after being treated by activated carbon of a tail gas absorption system. So that a micro negative pressure state is formed in the drying bin. The start and stop of the blower adopts a time relay to set the aeration duration and the aeration interval or can feed back the aeration duration and the aeration interval to the 15-temperature controller and the 20-PC controller through the 23-temperature probe according to the setting of the temperature so as to ensure that the pressure and the temperature reach the specified set range. Wherein, the 21-stirring device and the 17-turning roller uniformly mix the materials, the turning is carried out in the material fermentation process, and the stirring force is generated by the rotation of the blades on the rotating shaft.

In the conditioning sludge gasification system III, the semi-dry sludge subjected to biological drying dehydration and mechanical filter pressing and the cosolvent are sent into the gasification furnace from a 25-lock hopper in a spiral feeding mode through a 27-feeder, and the semi-dry sludge and the cosolvent are periodically fed into a 31-coal lock hopper at the top of the gasification furnace. The gasifier vessel has a 32-refractory lining to prevent heat loss due to excessive bed volume, and is not subjected to high temperatures because the refractory is separated from the hottest part of the bed (top of the nozzle) by the bed itself. After entering the gasification furnace, the fuel is fully mixed with the gasification agent introduced from the 26-primary air supply port and the 29-secondary air supply port, the fuel leaves the gasification furnace after being dried, gasified and combusted in different bed layers of a fuel bed, enters a 34-cyclone dust collector for filtering and dust removal, then is introduced into a 33-crude synthesis gas cooler for cooling and discharging, and the residual slag is cooled to the outside of the furnace after a series of processes through a 38-slag quenching chamber.

In the photocatalytic cracking reaction system IV (a first-stage high-temperature gasification synthesis gas tar degradation system), synthesis gasification gas is fed into a 48-catalytic cracking furnace from a 39-sealed feeding bin and a 40-spiral extrusion feeding machine, oil gas in the synthesis gas is fractionated by a 44-fractionator, the oil gas and the steam are mixed with each other to carry out catalytic cracking reaction, and light energy is used as energy to carry out catalytic cracking. And introducing the reacted synthesis gas into a 50-separation tank through a 47-stripping pipe, and separating oil gas and a catalyst in the synthesis gas to obtain relatively pure gasification gas.

In the adsorption purification system V (a two-stage gasification synthesis gas purification system), the gasification synthesis gas after the two-stage degradation is introduced into an adsorption purification device to further remove CO in the gasification synthesis gas₂And NO₂The raw synthesis gas is subjected to partial conversion and process waste heat recovery through a 53-cyclone separator and a 55-cooler, wherein the waste gas is discharged from a 54-waste gas outlet, and then the synthesis gas is subjected to 57-adsorption section to remove most of hydrogen sulfide, organic sulfur and carbon dioxide, and then the synthesis gas is introduced into a boiler to combust, and the flue gas in the synthesis gas is discharged from a 54-flue gas outlet.

In the synthesis gas combustion system VI, the obtained high-quality synthesis gas is fed into a gas boiler system, primary air fed from a 61-air inlet is mixed with part of auxiliary gas to combust to prepare hot water, the waste heat of the flue gas of the hot water system can be used for biological drying of sludge through a 59-flue gas waste heat regenerative tube, the boiler mainly comprises a 62-combustor, a 63-boiler main body part and a 64-soot outlet, wherein a 60-temperature pressure regulating cabinet controller is used for regulating the internal parameters of the boiler and ensuring the temperature operation of the boiler.

Claims

1. A comprehensive treatment process for preparing an air fertilizer by combining biological drying and gasification of sludge is characterized by comprising the following steps of firstly, dehydrating residual sludge with the water content of 80% by utilizing mechanical filter pressing, and reducing the water content to 55-65%; then carrying out biological drying and further dehydrating treatment on the wet sludge subjected to conditioning and filter pressing by using cheap and easily-obtained biomass powder, and reducing the water content to 30-40%; the addition of the biomass powder has the advantages of conditioning the characteristics of the sludge, improving the calorific value of the sludge and the like, the sludge is sent into a low-temperature gasification furnace after secondary dehydration to finally obtain the carbon fertilizer, and high-temperature tar gas generated in the treatment process is subjected to photocatalytic cracking, adsorption, purification and purification to obtain high-quality synthesis gas.

2. The integrated treatment process for sludge bio-drying and gasification cooperated air fertilizer as claimed in claim 1, wherein the integrated treatment process comprises the following steps:

(2) the sludge subjected to filter pressing by the mechanical plate frame is sent to a skid-mounted sludge biological drying bin device, low-price and easily-obtained biomass powder and wet sludge are mixed, stirred and conditioned, wherein the heat required in the biological dehydration process is derived from the waste heat of flue gas of a water heating system and is supplied to the biological drying process; stirring the wet sludge and the biomass powder stack by using a variable frequency stirrer, fermenting while stirring, further dehydrating the sludge after biological conditioning by using a rotary screw extruder in a drying bin, and reducing the water content to 30-40% after dehydration;

(3) the water content of the sludge after biomass conditioning and biological drying dehydration is 30-40%, the conditioned sludge is sent into a gasification furnace, the gasification temperature is controlled to be 550-700 ℃, the conditioned sludge is subjected to oxygen enrichment or steam gasification, and in addition, industrial waste heat can be selected on the spot as part of energy consumption of gasification;

(5) the synthesis gas is treated by photocatalysis and then is introduced into an adsorption purification device to further remove CO in the synthesis gas₂And NO₂And combustible synthesis gas with higher quality is obtained.

3. The comprehensive treatment process for sludge bio-drying and gasification combined air fertilizer production according to claim 2, further comprising the following steps:

4. The comprehensive treatment process for sludge bio-drying and gasification cooperated gas fertilizer as claimed in claim 2, wherein in the step (2), the main structure of the skid-mounted sludge bio-drying bin adopts light steel, HDPE board and polyurethane material, which not only meets the requirement of overall strength, but also achieves good heat preservation effect; the peripheral walls of the biological drying bin are sealed, and one side wall is provided with an opening door, so that the material is conveniently discharged; the device is relatively closed, two variable frequency blowers are adopted to carry out forced ventilation on the stockpile, the top of the reactor is provided with an air exhaust hole, a large amount of water vapor and harmful gases generated in the biological drying process are exhausted out of the closed bin through an induced draft fan, condensed and deodorized and then discharged, and a micro-negative pressure state is formed in the reactor; the position of a jack and a sampling position of a temperature instrument and the like are respectively arranged on one side wall of the drying bin and the bottom of the stack body;

5. The integrated treatment process for sludge bio-drying and gasification combined air fertilizer as claimed in claim 2, wherein in the step (3), the gasification process of the conditioned sludge in the gasification furnace is as follows:

the half-dry sludge after biological conditioning, dehydration and mechanical filter pressing is sent into a gasification furnace by a spiral feeding mode through a feeding bin, the gasification furnace adopts secondary air supply, and the gasification medium is O₂Steam, the most economical way being to utilize the waste oxygen of some plants orWaste water steam, O is input into the reactor₂And a gasification medium such as steam to complete the gasification reaction; the method comprises the following steps that firstly, crude synthesis gas generated by a gasification reactor is sent into a dust remover for dust removal, then the crude synthesis gas is sent to a next-stage treatment system, solids removed in the dust remover return to the bottom of a gasification furnace, and ash is discharged through a spiral ash remover so as to obtain relatively pure synthesis gas; wherein the temperature of the gasifier bed is maintained at 550 ℃, the temperature is controlled to ensure that the ash melting point is not exceeded, and the temperature of the upper suspension section of the bed may be quite high; in the whole gasification process, the pressure in the system is controlled to be in a normal pressure state, and the pressure regulation cabinet is adopted to monitor the internal pressure change of the gasification system in real time.

6. The integrated treatment process for sludge bio-drying and gasification combined air fertilizer production according to claim 2, wherein in the step (4), the gasified tar photocatalytic cracking device comprises an outer cylinder and an inner cylinder sleeved on the outer cylinder, wherein a photo-heating furnace layer is arranged on the inner side surface of the inner cylinder, a catalyst layer is arranged inside the inner cylinder, and a spiral heat exchange layer is arranged between the outer cylinder and the inner cylinder corresponding to the position of the photo-heating furnace layer;

7. The integrated treatment process for sludge biological drying and gasification cooperated gas fertilizer as claimed in claim 2, wherein in the step (5), the purpose of the syngas purification device is to purify the raw syngas to remove the non-combustible components as much as possible and to prepare qualified purified syngas for the combustible gas synthesis device, and the process is described as follows:

8. The system realized by the sludge biological drying and gasification cooperated gas fertilizer co-production comprehensive treatment process as claimed in claim 1, which is characterized by comprising a sludge mechanical plate-and-frame filter-press dehydration system I, a skid-mounted sludge biological drying bin device II, a conditioning sludge gasification system III, a photocatalytic cracking reaction system IV and an adsorption purification system V;

the adsorption purification system V comprises a temperature and pressure regulating cabinet controller, a cyclone separator, a waste gas outlet, a cooler, a flowmeter, an adsorption section and a throttle valve; the gasified synthesis gas after the second-stage degradation is introduced into an adsorption purification device to further remove CO in the gasified synthesis gas₂And NO₂The raw synthesis gas is subjected to partial conversion and process waste heat recovery through a cyclone separator and a cooler, wherein waste gas is discharged from a waste gas outlet, and then the synthesis gas is subjected to most of hydrogen sulfide, organic sulfur and carbon dioxide removal through an adsorption section, and then introduced into a boiler to combust flue gas therein, and the flue gas is discharged from a flue gas outlet.

9. The system of claim 8, wherein the integrated processing system further comprises a syngas combustion system VI comprising a flue gas waste heat utilization regenerator tube, a temperature and pressure regulator cabinet controller, an air intake, a boiler body portion, a soot outlet, and a burner; the high-quality synthetic gas that absorption purification system V obtained is sent into gas boiler system, mixes with the burning of part supplementary gas by the primary air that the air intake sent into and prepares hot water, and hot water system's flue gas waste heat can be used to mud biological drying through flue gas waste heat backheat pipe, and the boiler includes combustor, boiler main part and cigarette ash export, temperature and pressure regulator cabinet controller is used for adjusting boiler internal parameter, guarantees its temperature operation.