CN112479445A - Process and equipment for treating coal gasification ash water - Google Patents
Process and equipment for treating coal gasification ash water Download PDFInfo
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- CN112479445A CN112479445A CN202011172421.4A CN202011172421A CN112479445A CN 112479445 A CN112479445 A CN 112479445A CN 202011172421 A CN202011172421 A CN 202011172421A CN 112479445 A CN112479445 A CN 112479445A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 81
- 239000003245 coal Substances 0.000 title claims abstract description 48
- 238000002309 gasification Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000005189 flocculation Methods 0.000 claims abstract description 46
- 230000016615 flocculation Effects 0.000 claims abstract description 46
- 239000010866 blackwater Substances 0.000 claims abstract description 28
- 238000000926 separation method Methods 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 230000000694 effects Effects 0.000 claims abstract description 13
- 239000010797 grey water Substances 0.000 claims description 65
- 239000000706 filtrate Substances 0.000 claims description 47
- 239000007787 solid Substances 0.000 claims description 19
- 230000005484 gravity Effects 0.000 claims description 17
- 238000004062 sedimentation Methods 0.000 claims description 13
- 239000007790 solid phase Substances 0.000 claims description 12
- 239000002351 wastewater Substances 0.000 claims description 10
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims description 9
- 238000004065 wastewater treatment Methods 0.000 claims description 9
- 238000001704 evaporation Methods 0.000 claims description 8
- 230000008020 evaporation Effects 0.000 claims description 8
- 239000012065 filter cake Substances 0.000 claims description 8
- 238000011010 flushing procedure Methods 0.000 claims description 8
- 238000011144 upstream manufacturing Methods 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 abstract description 10
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 abstract description 10
- 239000011575 calcium Substances 0.000 abstract description 10
- 229910001424 calcium ion Inorganic materials 0.000 abstract description 10
- 229910001425 magnesium ion Inorganic materials 0.000 abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052782 aluminium Inorganic materials 0.000 abstract description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 abstract description 2
- 229910052742 iron Inorganic materials 0.000 abstract description 2
- -1 firstly Substances 0.000 abstract 1
- 238000001556 precipitation Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 3
- 230000002035 prolonged effect Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000013049 sediment Substances 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000009297 electrocoagulation Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/463—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrocoagulation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/46—Apparatus for electrochemical processes
- C02F2201/461—Electrolysis apparatus
- C02F2201/46105—Details relating to the electrolytic devices
- C02F2201/4612—Controlling or monitoring
- C02F2201/46125—Electrical variables
- C02F2201/4614—Current
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/46—Apparatus for electrochemical processes
- C02F2201/461—Electrolysis apparatus
- C02F2201/46105—Details relating to the electrolytic devices
- C02F2201/4612—Controlling or monitoring
- C02F2201/4615—Time
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/05—Conductivity or salinity
- C02F2209/055—Hardness
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/10—Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
- C02F2301/066—Overpressure, high pressure
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/14—Maintenance of water treatment installations
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
The invention relates to a process and equipment for treating coal gasification ash water, firstly, black water generated by coal gasification enters a settling tank for coarse separation to achieve the purpose of removing most suspended matters, clear liquid in the settling tank is pumped to an electric flocculation integrated equipment for fine separation by an ash water pump, and Al ionized by an iron plate or an aluminum plate is utilized3+Or Fe2+And OH generated from the cathode plate‑The complex generates a high-activity hydroxyl complex, the calcium and magnesium ions in the ash water are subjected to hardness removal treatment, meanwhile, the suspended matters in the clarified liquid can be removed, the calcium and magnesium ions in the ash water after passing through the electric flocculation integrated equipment can obtain a removal rate of 70 percent, the suspended matters can obtain a removal rate of 99 percent, the ash water after passing through the electric flocculation integrated equipment can reduce the amount of the discharged ash water on the one hand due to the improvement of water quality, and meanwhile, the ash water in a return system can reduce the risk of scaling of the equipment and a pipeline due to the reduction of hardness and the suspended matters, so that the operation safety of the device is improved.
Description
Technical Field
The invention relates to a treatment process and equipment for coal gasification grey water.
Background
After the black water discharged by the coal gasification device needs to carry out solid-liquid separation on suspended matters and solid particles, one part of grey water is used as discharged wastewater and enters a whole plant wastewater treatment device, and the other part of grey water returns to a system for recycling. The level of the sedimentation and separation effect directly influences the amount of discharged water and the quality of water returned to the system. If the sedimentation and separation effects are good, the amount of discharged water is small, the quality of the grey water returned to the system for reuse is good, and the stable operation period of the device can be prolonged; if the settling and separating effects are poor, the amount of discharged water is increased, the quality of the grey water returned to the system for reuse is poor, and the risk of scaling of pipelines and equipment is increased.
CN201710160557.5 discloses a method for electrochemically removing hardness and turbidity of coal gasification grey water or black water, which comprises the steps of electrochemically treating coal gasification black water to be treated to generate floccules and form a floccule-core network, adjusting the pH value of the treated black water to be 7-14, enabling scaling ions in the coal gasification grey water or the black water to react to generate precipitates, then enabling the precipitates to enter a precipitation zone, and sending the precipitates to a sludge treatment device after precipitation treatment. Although the method can reduce the hardness of the coal gasification grey water or black water and reduce the risk of scaling and fouling of the system, the black water with higher solid content of the grey water system directly enters the electric flocculation device, so that the problems of deposition of large solid particles on the surface of the electrode plate and erosion of abrasion equipment in the flocculation device can be caused, and the stable operation of the device is influenced.
CN106630307A discloses a system and method for treating coal gasification grey water, which comprises an electrochemical reaction zone and a precipitation zone. The coal gasification ash water firstly enters an electric flocculation reactor, air is introduced into the electric flocculation reactor to form high-efficiency adsorption groups in the reactor, and then the pH value and the alkalinity of water quality are adjusted in a precipitation zone to ensure that Ca2+、Mg2+The ions precipitate, thereby reducing the hardness of the grey water. The sediment is sent to a vacuum filtration system for filtration through a slurry pump, and clear water obtained after the sediment is sent to a grey water buffer tank. Although the method can reduce the hardness of the grey water, the system is more complex in arrangement, needs additional settling tanks, electric flocculation reactors and the like, and has larger investment.
The black water discharged by the conventional coal gasification device is treated by a flocculating agent, and is subjected to gravity settling separation in a settling tank, so that the size of the settling tank is larger in consideration of the limitation of settling velocity; meanwhile, the gravity settling separation effect of suspended matters in the settling tank is not ideal. In practice, there is considerable entrainment of suspended matter into the clarified liquor in the settler. In addition, calcium and magnesium ions in the grey water are not removed in the settling tank, and the total hardness of the grey water is not effectively reduced. Therefore, this method results in a large amount of effluent from the clarifier in the settling tank, and the grey water returned to the system increases the risk of equipment and piping fouling due to the influence of calcium and magnesium ions.
Disclosure of Invention
The first technical problem to be solved by the invention is to provide a treatment process of coal gasification grey water, which can effectively solve the defects of large specification and size of a settling tank, high scaling rate of pipelines and equipment, large amount of discharged waste water and the like of the existing device, and can reduce particles, suspended matters and hardness in the recycled grey water to the maximum extent and prolong the operation period of the device.
The second technical problem to be solved by the present invention is to provide a device for implementing the above coal gasification grey water treatment process, aiming at the current state of the prior art.
The technical scheme adopted by the invention for solving at least one technical problem is as follows: a process for treating coal gasification grey water is characterized by comprising the following steps:
(1) after the black water with high ammonia nitrogen, high suspended matters and high hardness from the black water flash evaporation and grey water treatment processes of an upstream coal gasification device is subjected to coarse effect gravity liquid-solid separation in a settling tank, clear liquid overflows into the grey water tank, and the settled solid phase is conveyed into a vacuum suction filter after being pressurized for forced liquid-solid separation;
(2) the obtained filtrate flows to a settling tank or a filtrate tank by utilizing gravity flow, the filtrate in the filtrate tank is pressurized and then sent to a coal mill, and a filter cake is sent out;
(3) and (3) pressurizing the grey water in the grey water tank, conveying the grey water to the electric flocculation integrated equipment for electric flocculation treatment, and conveying the treated grey water to the lock bucket flushing water tank, the deaerator and the downstream wastewater treatment device respectively.
Preferably, the process for treating coal gasification grey water comprises the following steps:
(1) after coarse effect gravity liquid-solid separation is carried out on high ammonia nitrogen, high suspended matters, high-hardness 0.1-0.2 MPaG and black water at 45 ℃ from black water flash evaporation and grey water treatment processes of an upstream coal gasification device in a settling tank, clear liquid overflows into the grey water tank, and settled solid is pressurized to 0.2-0.3 MPaG by a settling tank underflow pump and is conveyed into a vacuum suction filter for forced liquid-solid separation;
(2) the filtrate flows into a settling tank or a filtrate tank by utilizing gravity flow, the filtrate in the filtrate tank is pressurized to 0.3-0.4 MPaG by utilizing a filtrate pump and then is sent to a coal mill, and the filter cake is sent out;
(3) and pressurizing the ash water in the ash water tank to 0.4-0.5 MPaG by using an ash water pump, then conveying the ash water to an electric flocculation integrated device for electric flocculation treatment, and respectively conveying the treated ash water to a lock hopper flushing water tank, a deaerator and a downstream wastewater treatment device.
In the scheme, the current density of the electric flocculation integrated equipment for electric flocculation treatment is 5-15 mA/cm2The distance between the polar plates is 5-20 mm, and the retention time is 1-3 min.
After the step (3) is finished, the total hardness removal rate of the grey water is more than 70%, and the reduction of the discharged wastewater amount is more than or equal to 30%.
An apparatus for carrying out the above coal gasification grey water treatment process is characterized by comprising:
the settling tank is used for carrying out coarse effect gravity liquid-solid separation on high ammonia nitrogen, high suspended matters and high hardness black water from the black water flash evaporation and grey water treatment processes of an upstream coal gasification device;
the ash water tank is arranged at the downstream of the settling tank and is used for receiving the clarified liquid obtained in the settling tank;
the electric flocculation integrated equipment is arranged at the downstream of the ash water tank and used for receiving the ash water in the ash water tank and performing electric flocculation treatment, and the electric flocculation integrated equipment is provided with an output port used for conveying treated materials to the lock bucket flushing water tank, the deaerator and the downstream wastewater pretreatment device according to different use amounts of terminal equipment;
the vacuum suction filter is used for receiving the solid phase output by the settling tank and carrying out forced solid-liquid separation on the solid phase, and the bottom of the vacuum suction filter is provided with a first pipeline for conveying at least part of the obtained filtrate to the settling tank and an output end for conveying the obtained filter cake to the outside; and
and the filtrate tank is arranged at the downstream of the vacuum suction filter and used for receiving part of filtrate output by the vacuum suction filter, and the bottom of the vacuum suction filter is provided with a second pipeline used for conveying part of the obtained filtrate to the filtrate tank.
Preferably, a sedimentation tank underflow pump for providing power for solid phase conveying at the bottom of the sedimentation tank is arranged between the sedimentation tank and the vacuum suction filter.
Preferably, an ash water pump for providing power for conveying the ash water is arranged between the ash water tank and the electric flocculation integrated equipment. The outlet of the grey water pump is arranged in the electric flocculation integrated equipment, the self pressure head of the grey water is fully utilized, the energy consumption is reduced, the generation rate of hydrogen in water can be effectively reduced under a pressurization state, the safety of the device is improved, meanwhile, the scaling rate of the equipment and a pipeline can be reduced, and the continuous operation period of the device is prolonged.
Preferably, a filtrate pump for providing power for conveying the filtrate to the coal mill is arranged on the output end of the filtrate tank.
Preferably, the output end of the electric flocculation integrated equipment is provided with a grey water cooler for cooling materials conveyed to a downstream wastewater treatment device.
According to the invention, the sedimentation tank is firstly utilized for coarse separation, and then the electric flocculation integrated equipment is utilized for high-efficiency separation, so that the total hardness of suspended matters and calcium and magnesium ions in the whole coal gasification water system is reduced, the specification and size of the sedimentation tank are reduced, the occupied area and the investment cost are reduced, and the economy of the device is finally improved.
The traditional electrolysis equipment is normal-pressure equipment, the electrolyzed grey water needs to be pumped into a coal gasification water system again, electric energy is consumed to a large extent, and the economy is poor. The total hardness of ash water suspended matters and calcium and magnesium after being treated by the electrocoagulation integrated equipment can be improved to a greater extent, so that the amount of the discharged ash water can be reduced, and the scale and the investment of a downstream wastewater treatment device are reduced; on the other hand, because the amount of the discharged ash water is reduced, the amount of the fresh water supplemented in the coal gasification water system is also reduced, and the purposes of energy conservation and consumption reduction are achieved.
The invention utilizes the electric flocculation integrated equipment method to reduce the concentration and suspended solids of calcium and magnesium ions in the coal gasification ash water circulating system, and can also reduce the treatment load, the total hardness of inlet ash water and the content of ammonia nitrogen of a downstream wastewater treatment device.
Compared with the prior art, the invention has the advantages that: in the invention, firstly, black water generated by coal gasification enters a settling tank for coarse separation to achieve the aim of removing most suspended matters, clear liquid in the settling tank is conveyed to an electric flocculation integrated device for fine separation by using a grey water pump, and Al ionized by an iron plate or an aluminum plate is used3+Or Fe2+And OH generated from the cathode plate-The complex generates a high-activity hydroxyl complex, the calcium and magnesium ions in the ash water are subjected to hardness removal treatment, meanwhile, the suspended matters in the clarified liquid can be removed, the calcium and magnesium ions in the ash water after passing through the electric flocculation integrated equipment can obtain a removal rate of 70 percent, the suspended matters can obtain a removal rate of 99 percent, the ash water after passing through the electric flocculation integrated equipment can reduce the amount of the discharged ash water on the one hand due to the improvement of water quality, and meanwhile, the ash water in a return system can reduce the risk of scaling of the equipment and a pipeline due to the reduction of hardness and the suspended matters, so that the operation safety of the device is improved.
Drawings
FIG. 1 is a flow diagram of a process apparatus according to an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
As shown in FIG. 1, the process for treating coal gasification grey water of the present embodiment comprises the following steps:
(1) after coarse effect gravity liquid-solid separation is carried out on high ammonia nitrogen, high suspended matters, high-hardness 0.1-0.2 MPaG and 45 ℃ black water from black water flash evaporation and grey water treatment processes of an upstream coal gasification device in a settling tank 1, a clear solution overflows into a grey water tank 2, and a settled solid phase is pressurized to 0.2-0.3 MPaG by a settling tank underflow pump 7 and is conveyed into a vacuum suction filter 5 for forced liquid-solid separation;
(2) the filtrate flows to a settling tank 1 or a filtrate tank 4 by gravity flow, the filtrate in the filtrate tank 4 is pressurized to 0.3-0.4 MPaG by a filtrate pump 9 and then is sent to a coal mill, and the filter cake is sent out;
(3) and (3) pressurizing the ash water in the ash water tank 2 to 0.4-0.5 MPaG by using an ash water pump 8, then sending the ash water to the electric flocculation integrated equipment 3 for electric flocculation treatment, and respectively conveying the treated ash water to a lock bucket flushing water tank, a deaerator and a downstream wastewater treatment device.
The current density adopted by the electric flocculation integrated equipment 3 is 5-15 mA/cm2The distance between the polar plates is 5-20 mm, the residence time is 1-3 min, the total hardness removal rate of the ash water can reach more than 70%, and the amount of discharged wastewater can be reduced by more than 30%.
The equipment for realizing the treatment process of the coal gasification grey water comprises the following steps:
the settling tank 1 is used for performing coarse-effect gravity liquid-solid separation on high ammonia nitrogen, high suspended matters and high-hardness black water from a black water flash evaporation and grey water treatment process of an upstream coal gasification device;
the ash water tank 2 is arranged at the downstream of the settling tank 1 and is used for receiving the clarified liquid obtained in the settling tank 1;
the electric flocculation integrated equipment 3 is arranged at the downstream of the ash water tank 2 and used for receiving the ash water in the ash water tank 2 and performing electric flocculation treatment, and the electric flocculation integrated equipment 3 is provided with an output port used for respectively conveying treated materials to the lock bucket flushing water tank, the deaerator and the downstream wastewater pretreatment device according to different use amounts of terminal equipment;
the vacuum suction filter 5 is used for receiving the solid phase output by the settling tank 1 and carrying out forced solid-liquid separation on the solid phase, and the bottom of the vacuum suction filter 5 is provided with a first pipeline for conveying part of the obtained filtrate to the settling tank 1 and an output end for conveying the obtained filter cake to the outside; and
and the filtrate tank 4 is arranged at the downstream of the vacuum filter 5 and is used for receiving part of the filtrate output by the vacuum filter 5, and the bottom of the vacuum filter 5 is provided with a second pipeline for conveying part of the obtained filtrate to the filtrate tank 4.
A sedimentation tank underflow pump 7 for providing power for solid phase conveying at the bottom of the sedimentation tank 1 is arranged between the sedimentation tank 1 and the vacuum suction filter 5. A grey water pump 8 for providing power for conveying grey water is arranged between the grey water tank 2 and the electric flocculation integrated equipment 3. The electric flocculation integrated equipment 3 is placed at the outlet of the grey water pump, the self pressure head of the grey water is fully utilized, the energy consumption is reduced, the generation rate of hydrogen in water can be effectively reduced under a pressurization state, the safety of the device is improved, meanwhile, the scaling rate of the equipment and a pipeline can be reduced, and the continuous operation period of the device is prolonged.
And a filtrate pump 9 for supplying filtrate to the coal mill to improve power is arranged on the output end of the filtrate tank 4. And an ash water cooler 6 for cooling the materials conveyed to the downstream wastewater pretreatment device is arranged on the output end of the electric flocculation integrated equipment 3.
400m produced by coal water slurry gasification process3The process and equipment of this example are described with respect to/h black water as a calculation standard. The black water from the coal water slurry gasification device firstly enters a settling tank 1 for preliminary gravity settling separation. And sending the settled clarified liquid to the electric flocculation integrated equipment 3 by using an ash water pump 8 for subdivision to remove suspended matters and calcium and magnesium ions. And discharging a part of the ionized grey water to the outside, and returning a part of the ionized grey water to the system for recycling.
The above table shows the data relating to the process of the present invention and the prior art treatment process, and it can be seen from the above table that: if the conventional gravity precipitation process is adopted, the specification and the size of the settling tank are larger and reach the specification and the size
The discharged ash water amount is also large; the quality of the clear liquid is not ideal, the total hardness of the clear liquid is up to 1000mg/L, and the hardness removal cost of the discharged sewage and the risk of scaling of equipment and pipelines caused by returning to a system are increased. The process and the equipment of the invention not only have small size, but also discharge the grey waterGreatly reduces the particle, suspended substance and hardness in the recycled grey water.
Claims (9)
1. A process for treating coal gasification grey water is characterized by comprising the following steps:
(1) after the black water with high ammonia nitrogen, high suspended matters and high hardness from the black water flash evaporation and grey water treatment processes of an upstream coal gasification device is subjected to coarse effect gravity liquid-solid separation in a settling tank, clear liquid overflows into the grey water tank, and the settled solid phase is conveyed into a vacuum suction filter after being pressurized for forced liquid-solid separation;
(2) the obtained filtrate flows to a settling tank or a filtrate tank by utilizing gravity flow, the filtrate in the filtrate tank is pressurized and then sent to a coal mill, and a filter cake is sent out;
(3) and (3) pressurizing the grey water in the grey water tank, conveying the grey water to the electric flocculation integrated equipment for electric flocculation treatment, and conveying the treated grey water to the lock bucket flushing water tank, the deaerator and the downstream wastewater treatment device respectively.
2. The process for treating coal gasification grey water according to claim 1, characterized by the following steps:
(1) after coarse effect gravity liquid-solid separation is carried out on high ammonia nitrogen, high suspended matters, high-hardness 0.1-0.2 MPaG and black water at 45 ℃ from black water flash evaporation and grey water treatment processes of an upstream coal gasification device in a settling tank, clear liquid overflows into the grey water tank, and settled solid is pressurized to 0.2-0.3 MPaG by a settling tank underflow pump and is conveyed into a vacuum suction filter for forced liquid-solid separation;
(2) the filtrate flows into a settling tank or a filtrate tank by utilizing gravity flow, the filtrate in the filtrate tank is pressurized to 0.3-0.4 MPaG by utilizing a filtrate pump and then is sent to a coal mill, and the filter cake is sent out;
(3) and pressurizing the ash water in the ash water tank to 0.4-0.5 MPaG by using an ash water pump, then conveying the ash water to an electric flocculation integrated device for electric flocculation treatment, and respectively conveying the treated ash water to a lock hopper flushing water tank, a deaerator and a downstream wastewater treatment device.
3. According to claim 2The treatment process of the coal gasification grey water is characterized by comprising the following steps: the current density of the electric flocculation integrated equipment for electric flocculation treatment is 5-15 mA/cm2The distance between the polar plates is 5-20 mm, and the retention time is 1-3 min.
4. The process for treating coal gasification grey water according to claim 3, characterized in that: after the step (3) is finished, the total hardness removal rate of the grey water is more than 70%, and the reduction of the discharged wastewater amount is more than or equal to 30%.
5. An apparatus for implementing a process for treating coal gasification grey water as claimed in any of claims 1 to 4, comprising:
the settling tank is used for carrying out coarse effect gravity liquid-solid separation on high ammonia nitrogen, high suspended matters and high hardness black water from the black water flash evaporation and grey water treatment processes of an upstream coal gasification device;
the ash water tank is arranged at the downstream of the settling tank and is used for receiving the clarified liquid obtained in the settling tank;
the electric flocculation integrated equipment is arranged at the downstream of the ash water tank and used for receiving the ash water in the ash water tank and performing electric flocculation treatment, and the electric flocculation integrated equipment is provided with an output port used for conveying treated materials to the lock bucket flushing water tank, the deaerator and the downstream wastewater pretreatment device according to different use amounts of terminal equipment;
the vacuum suction filter is used for receiving the solid phase output by the settling tank and carrying out forced solid-liquid separation on the solid phase, and the bottom of the vacuum suction filter is provided with a first pipeline for conveying at least part of the obtained filtrate to the settling tank and an output end for conveying the obtained filter cake to the outside; and
and the filtrate tank is arranged at the downstream of the vacuum suction filter and used for receiving part of filtrate output by the vacuum suction filter, and the bottom of the vacuum suction filter is provided with a second pipeline used for conveying part of the obtained filtrate to the filtrate tank.
6. The apparatus of claim 5, wherein: and a sedimentation tank underflow pump used for providing power for solid phase conveying at the bottom of the sedimentation tank is arranged between the sedimentation tank and the vacuum suction filter.
7. The apparatus of claim 5, wherein: and an ash water pump for providing power for conveying ash water is arranged between the ash water tank and the electric flocculation integrated equipment.
8. The apparatus of claim 5, wherein: and a filtrate pump for conveying filtrate to the coal mill to improve power is arranged at the output end of the filtrate tank.
9. The apparatus of any one of claims 5 to 9, wherein: and an ash water cooler for cooling the materials conveyed to the downstream wastewater pretreatment device is arranged on the output end of the electric flocculation integrated equipment.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114014465A (en) * | 2021-11-18 | 2022-02-08 | 恒力石化（大连）炼化有限公司 | System and process for reducing suspended matters and hardness of gasified ash water |
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Application publication date: 20210312 |