CN207537309U - IGCC plant coal gasification and sulfur-bearing composite waste treatment for reuse Zero discharging system - Google Patents

Abstract

The utility model discloses a zero-emission system for the treatment and reuse of coal gasification and sulfur-containing mixed wastewater in an IGCC power plant, which comprises an ozone generator, a homogeneous adjustment tank, an A/O biochemical sedimentation tank, a flocculation sedimentation tank, a filter device, and an ozone catalytic oxidation system. device, ABFT tank, micro-flocculation settling tank, sand filter, vibrating reverse osmosis membrane device and evaporation crystallization device, among which, the homogeneous adjustment tank passes through A/O biochemical settling tank, flocculation settling tank, filter device, ozone catalytic oxidation device, The ABFT tank, microflocculation settling tank and sand filter are connected with the vibrating reverse osmosis membrane device, the concentrated water outlet of the vibrating reverse osmosis membrane device is connected with the inlet of the evaporation crystallization device, the outlet of the ozone generator is connected with the ozone inlet of the ozone catalytic oxidation device The system can realize the coal gasification of IGCC power plant and the treatment, reuse and zero discharge of sulfur-containing mixed wastewater.

Description

IGCC Power Plant Coal Gasification and Sulfur-Containing Mixed Wastewater Treatment and Reuse Zero Discharge System

technical field

The utility model belongs to the technical field of industrial waste water treatment and zero discharge, and relates to a zero discharge system for the treatment and reuse of coal gasification and sulfur-containing mixed waste water in an IGCC power plant.

Background technique

At present, in the domestic power industry, integrated coal gasification-steam gas combined cycle (IGCC) power generation is still a new technology, with few projects in operation and little experience in operation. The utilization and drainage systems of IGCC power plants are very different from those of conventional thermal power plants, especially the coal gasification wastewater and sulfur-containing wastewater produced by the coal gasification and purification units are very complex and difficult to treat and reuse. The water quality and quantity characteristics of the above two complex wastewaters are as follows.

Coal gasification waste water is a kind of waste water produced by coal gas ash removal, washing and condensate separation, and ash flushing during the pressurized coal gasification process. After the initial treatment, part of it is recycled, and the rest is discharged to the subsequent wastewater treatment system. After preliminary treatment, the coal gasification wastewater has low content of phenols and volatile benzenes, but the content of suspended solids and chromaticity are still high, and contains a large amount of complex and refractory organic compounds such as single-ring aromatic hydrocarbons and polycyclic aromatic hydrocarbons. In addition, the wastewater It also contains a small amount of toxic and harmful substances such as cyanide, inorganic fluoride ions and ammonia nitrogen, which is difficult to biochemically treat. The water quality of IGCC coal gasification wastewater fluctuates greatly, the COD concentration is about 400-1000mg/L, the ammonia nitrogen concentration is about 300-400mg/L, the cyanide concentration is about 0-10mg/L, and the salt content is about 3000-4000mg/L; About 26-30m ³ /h.

Sulfur- ^containing wastewater is another special wastewater with high salt content and high COD content produced by the sulfur recovery unit. The filtrate is formed after being washed and diluted with desalinated water, and contains biochemically refractory organic matter such as chelating agents and surfactants, ammonia nitrogen and other substances. The COD content is as high as 4000-10000mg/L, the salt content is as high as 10000-20000mg/L, and the ammonia nitrogen content is about 200-500mg/L.

The existing treatment process of coal gasification wastewater in IGCC power plants is: CaCl ₂ defluoride precipitation, ammonia blow-off, cyanide breaking, and integrated A/O process. The operation effect is poor. The main reason is that the process design is unreasonable and difficult to operate and maintain. Heterocyclic and polycyclic aromatic compounds in coal gasification wastewater are difficult to be biodegraded, and microbial domestication is difficult. According to investigations, the coal gasification wastewater generated in the domestic coal chemical industry is usually treated by chemical unit operations such as stripping, extraction, low-pressure flash distillation, and rectification, and then biochemically treated, but it is often difficult to meet the discharge standards. Therefore, it is difficult to achieve standard discharge and deep reuse of coal gasification wastewater relying on purely traditional biochemical treatment processes. In addition, for the unique sulfur-containing wastewater of IGCC power plants, due to the special water quality and small amount of water, there is no report on the relevant treatment process.

In order to treat the chemical wastewater of the IGCC power plant, it is necessary to mix the coal gasification wastewater and the sulfur-containing wastewater for reuse, and realize zero discharge of wastewater on this basis. The COD content of the mixed wastewater of coal gasification wastewater and sulfur-containing wastewater is as high as 1000-1500mg/L, and the content of ammonia nitrogen is about 350-450mg/L. It is more difficult to treat than pure coal gasification wastewater.

Therefore, for the mixed wastewater of coal gasification wastewater and sulfur-containing wastewater, it is urgent to develop an effective treatment process to achieve deep reuse and zero discharge, greatly reduce the environmental hazards caused by wastewater discharge and reduce the fresh tap water intake of power plants.

Utility model content

The purpose of this utility model is to overcome the shortcomings of the above-mentioned prior art, and provide a zero-discharge system for coal gasification and sulfur-containing mixed wastewater treatment and reuse of IGCC power plants. use and zero emissions.

In order to achieve the above-mentioned purpose, the zero discharge system for IGCC power plant coal gasification and sulfur-containing mixed wastewater treatment and reuse described in the utility model includes an ozone generator, a homogeneous adjustment tank, an A/O biochemical sedimentation tank, a flocculation sedimentation tank, a filter device, Ozone catalytic oxidation device, ABFT tank, micro-flocculation settling tank, sand filter, vibrating reverse osmosis membrane device and evaporation crystallization device, among which, the homogeneous adjustment tank passes through A/O biochemical settling tank, flocculation settling tank, filter device, ozone catalytic The oxidation device, ABFT tank, micro-flocculation sedimentation tank and sand filter are connected with the vibrating reverse osmosis membrane device, the concentrated water outlet of the vibrating reverse osmosis membrane device is connected with the inlet of the evaporation crystallization device, and the outlet of the ozone generator is connected with the ozone catalytic oxidation device The ozone inlet is connected.

It also includes a sludge tank and a sludge thickening and dewatering system, wherein the inlet of the sludge tank is connected to the sludge outlet of the A/O biochemical settling tank, the sludge outlet at the bottom of the flocculation settling tank and the sludge outlet at the bottom of the micro-flocculation settling tank The outlet of the sludge tank is connected with the inlet of the sludge thickening and dewatering system, and the filtrate outlet of the sludge thickening and dewatering system is connected with the inlet of the homogeneous regulating tank.

The utility model has the following beneficial effects:

During the specific operation of the IGCC power plant coal gasification and sulfur-containing mixed wastewater treatment and reuse zero-emission system described in the utility model, the IGCC coal gasification and sulfur-containing mixed wastewater are homogenized in the homogeneous adjustment tank and biochemical in the A/O biochemical settling tank. Settling, flocculation settling tank flocculation settling, filtering device filtration, ozone catalytic oxidation device catalytic oxidation, ABFT tank removal of ammonia nitrogen, micro-flocculation settling tank flocculation settling, sand filtration, vibrating reverse osmosis membrane device vibration reverse osmosis and evaporation crystallization device after evaporation and crystallization The solid salt is formed to realize the coal gasification of IGCC power plant and the treatment, reuse and zero discharge of sulfur-containing mixed wastewater. The overall process route is efficient and the connection is reasonable. Among them, the COD of IGCC coal gasification and sulfur-containing mixed wastewater is reduced to below 60, and the BOD ₅ is reduced to below 20 through the catalytic oxidation of the ozone catalytic oxidation device. The ammonia nitrogen content of IGCC coal gasification and sulfur-containing mixed wastewater is reduced to below 5mg/L after being treated by the ABFT pool. In addition, the utility model aims at the characteristics of high TOC content in wastewater, and selects an anti-fouling and anti-pollution vibrating reverse osmosis membrane to carry out deep concentration treatment on it. The membrane group vibrates continuously, so that the vibrating reverse osmosis membrane can withstand the wastewater with high hardness and more pollutants, which is beneficial to the long-term operation of the system and reduces the number of cleanings. Among them, the produced water output by the vibrating reverse osmosis membrane device can be used as replenishment water for reuse To the IGCC fresh water circulation tower. The utility model can make the difficult IGCC coal gasification and sulfur-containing mixed wastewater treatment COD, BOD ₅ and ammonia nitrogen indicators better than the first-level discharge standard in the national "Sewage Comprehensive Discharge Standard" GB 8978-1996, and then it can be realized after further advanced treatment Reuse and zero discharge of waste water, while reducing the intake of fresh tap water for IGCC power plants. In addition, it should be noted that the overall removal of COD and ammonia nitrogen in this utility model is mainly based on biological technology, which greatly reduces the dosage of system chemicals and operating costs.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Among them, 1 is the homogeneous adjustment tank, 2 is the A/O biochemical sedimentation tank, 3 is the flocculation sedimentation tank, 4 is the filter device, 5 is the ozone catalytic oxidation device, 6 is the ABFT tank, 7 is the micro-flocculation sedimentation tank, and 8 is the Sand filter, 9 is a vibrating reverse osmosis membrane device, 10 is an evaporation crystallization device, 11 is a sludge tank, and 12 is a sludge concentration and dehydration system.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in further detail:

Referring to Fig. 1, the zero discharge system for IGCC power plant coal gasification and sulfur-containing mixed wastewater treatment and reuse described in the utility model includes an ozone generator, a homogeneous regulating tank 1, an A/O biochemical settling tank 2, a flocculation settling tank 3, and a filter Device 4, ozone catalytic oxidation device 5, ABFT tank 6, micro-flocculation sedimentation tank 7, sand filter 8, vibrating reverse osmosis membrane device 9 and evaporation crystallization device 10, wherein, the homogeneous adjustment tank 1 passes through the A/O biochemical sedimentation tank in turn 2. Flocculation settling tank 3, filter device 4, ozone catalytic oxidation device 5, ABFT tank 6, micro-flocculation settling tank 7 and sand filter 8 are connected with vibrating reverse osmosis membrane device 9, and the concentrated water outlet of vibrating reverse osmosis membrane device 9 It communicates with the inlet of the evaporation crystallization device 10 , and the outlet of the ozone generator communicates with the ozone inlet of the ozone catalytic oxidation device 5 .

The utility model also includes a sludge tank 11 and a sludge concentration and dehydration system 12, wherein the inlet of the sludge tank 11 is connected to the sludge outlet of the A/O biochemical settling tank 2, the sludge outlet at the bottom of the flocculation settling tank 3 and the micro-flocculation The sludge outlet at the bottom of the settling tank 7 is connected, the outlet of the sludge tank 11 is connected with the inlet of the sludge thickening and dewatering system 12, and the filtrate outlet of the sludge thickening and dewatering system 12 is connected with the inlet of the homogeneous regulating tank 1.

The working process of the present utility model is:

1) IGCC coal gasification and sulfur-containing mixed wastewater enters the homogeneous adjustment tank 1 to keep the water quality pollutant load of IGCC coal gasification and sulfur-containing mixed wastewater stable, and then enters the A/O biochemical sedimentation tank 2, and in A In the /O biochemical settling tank 2, microorganisms are used to remove the refractory organic matter in the IGCC coal gasification and sulfur-containing mixed wastewater, and the IGCC coal gasification and sulfur-containing mixed wastewater output from the A/O biochemical settling tank 2 enters the flocculation settling tank 3;

2) Add PAC coagulant and PAM coagulant to the flocculation settling tank 3, remove the colloidal particles in the IGCC coal gasification and sulfur-containing mixed wastewater through the PAC coagulant and PAM coagulant, and coagulate the IGCC output from the flocculation settling tank 3 The coal gasification and sulfur-containing mixed wastewater is filtered through the filter device 4 to remove suspended solids in the IGCC coal gasification and sulfur-containing mixed wastewater, and the IGCC coal gasification and sulfur-containing mixed wastewater filtered by the filter device 4 enters the ozone catalytic oxidation device 5 ;

3) The ozone generator generates ozone, and then aerates the ozone into the IGCC coal gasification and sulfur-containing mixed wastewater through the titanium aeration plate at the bottom of the ozone catalytic oxidation device 5, so that the IGCC coal gasification and sulfur-containing mixed wastewater and ozone are fully mixed. After mixing, fully contact and react in the catalyst bed of the ozone catalytic oxidation device 5, and the IGCC coal gasification and sulfur-containing mixed wastewater output from the ozone catalytic oxidation device 5 enter the ABFT pool 6;

4) The ammonia nitrogen in the IGCC coal gasification and sulfur-containing mixed wastewater is removed through the ABFT pool 6, and the IGCC coal gasification and sulfur-containing mixed wastewater output from the ABFT pool 6 is successively passed through the micro-flocculation settling tank 7 and filtered by the sand filter 8 before entering the Vibrating reverse osmosis is performed in the vibrating reverse osmosis membrane device 9, wherein the concentrated water output by the vibrating reverse osmosis membrane device 9 enters the evaporation crystallization device 10 to evaporate and crystallize to form solid salt, and the output of the evaporation crystallization device 10 and the vibrating reverse osmosis membrane device 9 Produced water is recycled.

The residence time of the IGCC coal gasification and sulfur-containing mixed wastewater in the A/O biochemical sedimentation tank 2 in step 1) is 20 h.

The addition amount of PAC coagulant in step 2) is 100mg/L, and the addition amount of PAM coagulant aid is 0.5mg/L.

The dosage of ozone in the ozone catalytic oxidation device 5 in step 3) is 200mg/L, and the residence time of IGCC coal gasification and sulfur-containing mixed wastewater in the ozone catalytic oxidation device 5 is 40min.

In step 4), the residence time of IGCC coal gasification and sulfur-containing mixed wastewater in the ABFT pool is 24 hours.

A number of microbial carriers are added in the ABFT pool 6, wherein the total volume of all the microbial carriers is 40%-45% of the capacity of the ABFT pool 6, microorganisms are attached and fixed on each microbial carrier, and there are good bacteria in each microbial carrier. Oxygen environment, anoxic environment and anaerobic environment make each microbial carrier form a miniature nitrification and denitrification reactor, so as to remove ammonia nitrogen in IGCC coal gasification and sulfur-containing mixed wastewater through microbial carrier.

In addition, the sludge at the bottom of the A/O biochemical settling tank 2, the sludge at the bottom of the flocculation settling tank 3, and the sludge at the bottom of the micro-flocculation settling tank 7 are regularly discharged into the sludge tank 11, and then passed through the sludge concentration and dehydration system 12 for dehydration, wherein the filtrate produced by the sludge concentration and dewatering system 12 enters the homogeneous adjustment tank 1, and the mud cake produced by the sludge concentration and dewatering system 12 is transported out for recovery.

In addition, PAC is put into the micro-flocculation settling tank 7, so that the bacterial cell bodies, metabolite particles and colloidal suspended matter carried in the IGCC coal gasification and sulfur-containing mixed wastewater are all precipitated.

In addition, when the vibrating reverse osmosis membrane device 9 performs deep concentration, through the continuous reciprocating vibration and the wide-gap inlet channel, the clogging and fouling of the membrane pores are greatly delayed, the cleaning burden is reduced, and the long-term stable operation of the system is ensured. The vibrating reverse osmosis membrane device 9 The quality of the output water is close to that of the tap water, and can be reused in the fresh water tower as supplementary water. The water production rate of the vibrating reverse osmosis membrane can be controlled above 75%.

In addition, the evaporation and crystallization device 10 adopts MVR technology, through mechanical compression, the temperature and pressure of the secondary steam are increased again, and the enthalpy value is increased, and it is reused as raw steam, which greatly saves steam consumption and reduces energy consumption. The wastewater slurry continues to be concentrated, crystallized and evaporated to dryness, and the condensate obtained by evaporation can be reused together with the water produced by vibration reverse osmosis.

Embodiment one

The water quality of coal gasification and sulfur-containing mixed wastewater of IGCC power plant is shown in Table 1, and the total water volume is 30m ³ /h.

Table 1

Concrete work process of the present utility model is:

1) IGCC coal gasification and sulfur-containing mixed wastewater enters the homogeneous adjustment tank 1 to keep the water quality pollutant load of IGCC coal gasification and sulfur-containing mixed wastewater basically stable, and then enters the A/O biochemical sedimentation tank 2, and In the A/O biochemical settling tank 2, microbes are used to remove refractory organic matter in IGCC coal gasification and sulfur-containing mixed wastewater. Among them, the COD removal rate reaches 70%-80%, the effluent COD drops to 200-250mg/L, and ammonia nitrogen removal The ammonia nitrogen content is about 300-350mg/L; among them, the residence time of IGCC coal gasification and sulfur-containing mixed wastewater in A/O biochemical sedimentation tank 2 is about 20h; the output of A/O biochemical sedimentation tank 2 IGCC coal gasification and sulfur-containing mixed wastewater enters the flocculation and sedimentation tank 3;

2) Add PAC coagulant and PAM coagulant to the flocculation settling tank 3, the PAC coagulant is hydrolyzed in the wastewater to generate positively charged polynuclear hydroxyl complexes with strong adsorption and electrical neutralization capabilities, and then gasified with IGCC coal and the colloidal suspended matter such as negatively charged biological cells and metabolites in the sulfur-containing mixed wastewater, making it gradually destabilized, coagulated and precipitated, thereby removing IGCC coal gasification and sulfur-containing mixed waste water through PAC coagulant and PAM coagulant Colloidal particles in wastewater, among which, the amount of PAC coagulant added is 100mg/L, and the amount of PAM coagulant aid added is 0.5mg/L. The pores are not blocked and silted by colloidal suspended matter, and the IGCC coal gasification and sulfur-containing mixed wastewater output from the flocculation settling tank 3 is filtered through the filter device 4, and further, the suspended matter in the IGCC coal gasification and sulfur-containing mixed wastewater is removed. The COD of the IGCC coal gasification and sulfur-containing mixed wastewater filtered by the device 4 is lower than 200mg/L, and the IGCC coal gasification and sulfur-containing mixed wastewater filtered by the filter device 4 enters the ozone catalytic oxidation device 5;

3) Generate ozone through the ozone generator, and then aerate the IGCC coal gasification and sulfur-containing mixed wastewater through the titanium aeration plate at the bottom of the ozone catalytic oxidation device 5, so that the IGCC coal gasification and sulfur-containing mixed wastewater are fully mixed with ozone After that, fully contact and react in the catalyst bed of the ozone catalytic oxidation device 5, wherein the dosage of ozone is 200mg/L, the residence time of IGCC coal gasification and sulfur-containing mixed wastewater in the ozone catalytic oxidation device 5 is 40min, and the ozone catalytic oxidation The COD of the IGCC coal gasification and sulfur-containing mixed wastewater output from the device 5 is reduced to below 60mg/L, and the IGCC coal gasification and sulfur-containing mixed wastewater output from the ozone catalytic oxidation device 5 enters the ABFT pool 6;

4) A microbial carrier is added in the ABFT pool 6, wherein the volume of the microbial carrier is 40%-45% of the capacity of the ABFT pool 6, microorganisms are attached and fixed on the microbial carrier, and there are aerobic and anaerobic microorganisms in each microbial carrier. Oxygen and anaerobic environment, so that each microbial carrier forms a miniature nitrification and denitrification reactor, thereby removing ammonia nitrogen in IGCC coal gasification and sulfur-containing mixed wastewater through microbial carriers, and increasing the ammonia nitrogen content in IGCC coal gasification and sulfur-containing mixed wastewater When the COD of IGCC coal gasification and sulfur-containing mixed wastewater is reduced to below 5mg/L, the residence time of IGCC coal gasification and sulfur-containing mixed wastewater in ABFT pool 6 is about 24h;

The IGCC coal gasification and sulfur-containing mixed wastewater output from the ABFT tank 6 enters the vibrating reverse osmosis membrane device 9 for vibrating reverse osmosis after passing through the micro-flocculation settling tank 7 flocculation sedimentation and sand filter 8 for vibrating reverse osmosis, wherein the vibrating reverse osmosis membrane device 9 The concentrated water output enters the evaporative crystallization device 10 for evaporative crystallization to form solid salt, and the product water output from the evaporative crystallization device 10 and the vibrating reverse osmosis membrane device 9 is recycled. The entire process can realize deep reuse of wastewater and liquid zero emission.

Claims (2)

1. a kind of IGCC plant coal gasification and sulfur-bearing composite waste treatment for reuse Zero discharging system, which is characterized in that including ozone Generator, homogeneous regulating reservoir (1), A/O biochemistry settling tank (2), Flocculating setting basin (3), filter device (4), catalytic ozonation Device (5), ABFT ponds (6), tiny flocculation settling tank (7), sand filtration (8), vibration reverse osmosis membrane apparatus (9) and evaporated crystallization device (10), wherein, homogeneous regulating reservoir (1) is successively through A/O biochemistry settling tank (2), Flocculating setting basin (3), filter device (4), ozone Catalytic oxidizing equipment (5), ABFT ponds (6), tiny flocculation settling tank (7) and sand filtration (8) are connected with vibration reverse osmosis membrane apparatus (9) Logical, the concentrated water outlet of vibration reverse osmosis membrane apparatus (9) is connected with the entrance of evaporated crystallization device (10), and ozone generator goes out Mouth is connected with the ozone inlet of device for catalyzing and oxidating ozone (5).

2. IGCC plant coal gasification according to claim 1 and sulfur-bearing composite waste treatment for reuse Zero discharging system, special Sign is, further includes sludge-tank (11) and sludge concentration and dewatering system (12), wherein, the entrance and A/O of sludge-tank (11) are biochemical The sludge of the sludge outlet of settling tank (2), the sludge outlet of Flocculating setting basin (3) bottom and tiny flocculation settling tank (7) bottom goes out Mouth is connected, and the outlet of sludge-tank (11) is connected with the entrance of sludge concentration and dewatering system (12), sludge concentration and dewatering system (12) filtrate (liquid is connected with the entrance of homogeneous regulating reservoir (1).