Coal gasification black water treatment device system and method

Abstract

The present application provides a coal gasification black water treatment device system and method, which adopts two-stage vortex separation devices for heat recovery and solid-liquid separation, wherein the secondary vortex separation device improves the solid-liquid separation effect by adding a specific composite medicament, and the treated grey water meets the requirements of the subsequent biochemical treatment; the coal gasification black water treatment device system cancels the high-pressure flash evaporation device, low-pressure flash evaporation device, deoxygenation device and sedimentation device required to be arranged in the traditional coal gasification black water treatment device system, and solves the problems of complex existing process flow, large equipment occupation area and low heat utilization rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal chemical industry, and in particular to a coal gasification black water treatment device system and method. BACKGROUND

[0002] The black water generated in the coal gasification process is cooled by high pressure, low pressure and vacuum flash evaporation, and the fine slag solids and suspended solids less than 30 ppm in the ash water are separated by flocculation and sedimentation. The ash water is heated and returned to the gasifier for recycling. The whole process is complex, the equipment failure rate is high, the land occupation is large, and the heat utilization rate of the flash evaporation method is low.

[0003] CN112624471A discloses a short process coal gasification black water purification method and device. The black water is first subjected to flash evaporation treatment, then sent to a micro-cyclone separator for centrifugal separation, the top of the separator is sent to a boiling bed separator for secondary purification, and then sent to an oxygen remover for heating and recycling. The process does not solve the problem of low heat utilization rate of the flash evaporation method, and the boiling bed in the process needs to be backwashed periodically according to the pressure difference. The particles in the fluidized state are prone to wear, and the problem of stable operation needs to be solved.

[0004] CN109485190A discloses a coal gasification black water treatment method, a coal gasification method and a system thereof. The black water after high pressure flash evaporation is subjected to cyclone solid removal treatment, the top clear flow is subjected to low pressure and vacuum flash evaporation in turn, and the black water after flash evaporation and the thick water at the bottom of the cyclone are subjected to sedimentation treatment. The main function of this process is to reduce the wear of low flash and vacuum flash, but it does not solve the problems of complex process and low heat utilization rate. Moreover, the liquid at the bottom of the cyclone is directly introduced into the sedimentation tank, which may flash evaporate in the tank, causing environmental problems.

[0005] CN111453906A discloses a coal gasification black water treatment system and process. The black water is first heated and recycled with deoxygenated water, then subjected to cyclone separation after heat exchange, the pressure energy in the overflow is recovered by a liquid turbine, and finally the condensate is recovered after normal pressure and vacuum flash evaporation. In this process, the black water is indirectly heat exchanged with the deoxygenated water. Since the black water has a high solid content, there are problems such as wear and blockage of the heat exchanger. Moreover, the overall water circulation amount does not change, and the required equipment processing capacity is still large.

[0006] CN220223877 discloses a high pressure black water treatment system. A carbon dioxide injection channel is arranged in the quenching water treatment device to reduce the PH of the high pressure black water by injecting carbon dioxide into the high pressure black water, thereby eliminating the risk of scaling. This process focuses on solving the problem of black water scaling, but has no obvious effect on simplifying the black water treatment process and improving heat utilization.

[0007] In summary, the coal gasification black water treatment process still has problems such as complex process, high equipment failure rate, large land occupation, and low heat utilization rate, and a more optimal treatment process needs to be developed to simplify the process and equipment and improve the heat utilization rate to increase the benefit. SUMMARY

[0008] In view of the problems in the prior art, the present application provides a coal gasification black water treatment device system and method, which adopts two-stage vortex separation devices to realize solid-liquid separation of coal gasification black water, wherein a composite medicament is added in the second-stage vortex separation device, which can greatly improve the solid-liquid separation effect, and cancels the high-pressure flash device, low-pressure flash device, oxygen removal device and sedimentation device that need to be set in the traditional coal gasification black water treatment device system, solving the problems of complex process flow, large equipment land occupation and low heat utilization rate.

[0009] To achieve this purpose, the present application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a coal gasification black water treatment device system, which comprises a first-stage vortex separation device, a flash device, a mixing device, a second-stage vortex separation device and a grey water storage device connected in sequence.

[0011] The coal gasification black water treatment device system adopts two-stage vortex separation devices to realize solid-liquid separation of coal gasification black water, wherein a composite medicament is added in the second-stage vortex separation device, which can greatly improve the solid-liquid separation effect, so that the coal gasification black water can meet the grey water outlet requirements of the original traditional process after simple treatment, meet the requirements of the downstream biochemical treatment, cancel the high-pressure flash device, low-pressure flash device, oxygen removal device and sedimentation device that need to be set in the traditional coal gasification black water treatment device system, and solve the problems of complex process flow, large equipment land occupation and low heat utilization rate.

[0012] Preferably, the coal gasification black water treatment device system further comprises a circulating pump connected with the first-stage vortex separation device, and the high-temperature clear liquid at the top of the first-stage vortex separation device can be directly returned to the water washing tower after being pressurized by the circulating pump to wash and remove the solid from the process gas, realizing the reuse of high-temperature hot water.

[0013] Preferably, the coal gasification black water treatment device system further comprises a medicament storage device and a medicament adding pump connected in sequence.

[0014] Preferably, the medicament adding pump is connected with the mixing device.

[0015] Preferably, the flash device is connected with the grey water storage device through a water cooling device.

[0016] Preferably, a pressure reducing valve is arranged between the first-stage vortex separation device and the flash device.

[0017] In a second aspect, the present application further provides a coal gasification black water treatment method, which is performed by using the coal gasification black water treatment device system of the first aspect, and comprises the following steps:

[0018] After the coal gasification black water enters the primary vortex separation device for solid concentration, the concentrated liquid at the bottom enters the flash device for cooling; the flash steam generated at the top of the flash device enters the grey water storage device after being cooled; and the solid-containing liquid generated at the bottom of the flash device enters the secondary vortex separation device after being mixed with the composite reagent in the mixing device, and the grey water generated at the top enters the grey water storage device.

[0019] The coal gasification black water treatment method has the advantages of simple operation, high-efficiency solid-liquid separation of the coal gasification black water by adding the composite reagent in the secondary vortex separation device, and low treatment cost of the obtained grey water meeting the requirement of the subsequent biochemical treatment.

[0020] Preferably, the clear liquid generated at the top of the primary vortex separation device is returned to the water washing tower after being pressurized by a circulating pump to wash and remove the solid from the process gas.

[0021] Preferably, the flash steam is cooled by a cooling device.

[0022] Preferably, the composite reagent is stored in a reagent storage device and is delivered to the mixing device by a reagent delivery pump.

[0023] Preferably, the solid concentrated liquid generated at the bottom of the secondary vortex separation device is delivered to a filter pressing device for treatment.

[0024] Preferably, the mass of the composite reagent accounts for 0.01-0.02% of the mass of the solid-containing liquid generated at the bottom of the flash device, for example, 0.01%, 0.012%, 0.015%, 0.017%, 0.019% or 0.02%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0025] Preferably, the composite reagent comprises reagent A and reagent B in a mass ratio of (0.1-10):1, for example, 0.1:1, 0.5:1, 1:1, 3:1, 5:1, 8:1 or 10:1, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0026] Preferably, the composite reagent comprises reagent A and reagent B in a mass ratio of (0.1-10):1, so as to ensure that the secondary vortex separation device has a good solid-liquid separation effect, the solid content of the treated grey water is low, and the treated grey water meets the requirement of the subsequent biochemical treatment. When the proportion of reagent A is low, fine particles cannot form flocs; and when the proportion of reagent A is high, the flocs cannot settle and are in a floating state. The reagent A comprises a coagulant, and the reagent B comprises a flocculant.

[0027] Preferably, the preparation method of the medicament A comprises mixing aluminum chloride and ferrous sulfite in water in a mass ratio of (1-2):1, for example, 1:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1, 1.8:1 or 2:1, but not limited to the listed values, and other values not listed in the range are also applicable;

[0028] After adding a sulfuric acid solution with a concentration of 95-98wt% and sodium chloride, for example, 95wt%, 95.5wt%, 96wt%, 96.5wt%, 97wt%, 97.5wt% or 98wt%, but not limited to the listed values, and other values not listed in the range are also applicable;

[0029] Adjusting the pH of the solution to 4-5, for example, 4, 4.2, 4.4, 4.5, 4.8 or 5, but not limited to the listed values, and other values not listed in the range are also applicable;

[0030] Performing a first solid-liquid separation; dissolving the filter cake with water and heating to 80-90℃, for example, 80℃, 82℃, 85℃, 86℃, 88℃ or 90℃, but not limited to the listed values, and other values not listed in the range are also applicable;

[0031] Maintaining for 1-3h, for example, 1h, 1.2h, 1.5h, 2h, 2.5h or 3h, but not limited to the listed values, and other values not listed in the range are also applicable;

[0032] Performing a second solid-liquid separation to obtain the filtrate as the medicament A.

[0033] The role of the sulfuric acid solution in the preparation method of the medicament A is to adjust the pH and provide polymerization conditions. When the amount of sulfuric acid solution added is too much or too little, it will lead to an unsuitable pH and affect the polymerization reaction. The role of sodium chloride is to provide a chlorine source. The purpose of heating the filter cake dissolved in water to 80-90℃ is to promote the polymerization reaction.

[0034] Preferably, the sodium chloride is added in an amount of 8-10% by mass of the mixed solution, for example, 8%, 8.5%, 9%, 9.5%, 9.8%, or 10%, etc., but not limited to the listed values, and other values not listed within the range are also applicable. When the amount of sodium chloride added is too much, more impurities will be generated; when the amount of sodium chloride added is too little, the amount of chlorine source provided will be insufficient, affecting the degree of polymerization.

[0035] Preferably, the preparation method of the medicament B comprises mixing a complexing agent solution and a dimethyldiallylammonium chloride aqueous solution in a mass ratio of 1:(0.5-1), to obtain a mixed solution; for example, 1:0.5, 1:0.6, 1:0.7, 1:0.75, 1:0.8, 1:0.9, or 1:1, etc., but not limited to the listed values, and other values not listed within the range are also applicable; when the complexing agent solution accounts for too much, the active sites of the flocculant will be reduced, which is not conducive to the effective aggregation and sedimentation of particles; when the complexing agent solution accounts for too little, less complex will be formed, resulting in low charge density and poor stability, affecting the flocculation effect.

[0036] In an inert gas atmosphere, the mixed solution is mixed with an initiator solution in a mass ratio of (10-100):1, for example, 10:1, 20:1, 30:1, 50:1, 80:1, or 100:1, etc., but not limited to the listed values, and other values not listed within the range are also applicable; when the initiator solution accounts for too much, the reaction rate will be too fast, and the side reactions will increase, affecting the flocculation effect; when the initiator solution accounts for too little, the monomer molecules will have less polymerization, resulting in smaller molecular weight, affecting the flocculation effect.

[0037] Mixing at a temperature of 70-80°C, for example, 70°C, 72°C, 74°C, 76°C, 78°C, 79°C, or 80°C, etc., but not limited to the listed values, and other values not listed within the range are also applicable;

[0038] Stirring for 10-20h, for example, 10h, 12h, 14h, 16h, 18h, 19h, or 20h, etc., but not limited to the listed values, and other values not listed within the range are also applicable; to obtain the medicament B.

[0039] Preferably, the complexing agent solution comprises any one or a combination of at least two of disodium ethylenediaminetetraacetate solution, sodium nitrilotriacetate solution, or diethylenetriamine pentacarboxylate solution, wherein a typical but non-limiting combination includes a combination of disodium ethylenediaminetetraacetate solution and sodium nitrilotriacetate solution, a combination of diethylenetriamine pentacarboxylate solution and disodium ethylenediaminetetraacetate solution, or a combination of sodium nitrilotriacetate solution and diethylenetriamine pentacarboxylate solution.

[0040] Preferably, the concentration of the complexing agent solution is 5-15 g / L, for example, it can be 5 g / L, 8 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L or 15 g / L, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0041] Preferably, the inert gas comprises nitrogen.

[0042] Preferably, the concentration of the aqueous dimethyl diallyl ammonium chloride solution is 50-60 wt%, for example, it can be 50 wt%, 53 wt%, 55 wt%, 57 wt%, 59 wt% or 60 wt%, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0043] Preferably, the initiator solution comprises any one or a combination of at least two of ammonium persulfate solution, azobisisobutyronitrile solution or dibenzoyl peroxide solution, wherein a typical but non-limiting combination includes a combination of ammonium persulfate solution and azobisisobutyronitrile solution, a combination of dibenzoyl peroxide solution and ammonium persulfate solution or a combination of azobisisobutyronitrile solution and dibenzoyl peroxide solution.

[0044] Preferably, the concentration of the initiator solution is 60-80 g / L, for example, it can be 60 g / L, 62 g / L, 65 g / L, 70 g / L, 72 g / L, 75 g / L or 80 g / L, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0045] Preferably, the coal gasification black water enters the primary vortex separation device as tangential feed, and the mass flow rate of the clear liquid is 60-80%, for example, it can be 60%, 62%, 65%, 70%, 72%, 75% or 80%, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0046] The solid content of the clear liquid is 0.1-0.3%, for example, it can be 0.1%, 0.13%, 0.15%, 0.2%, 0.25%, 0.27% or 0.3%, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0047] Preferably, the solid-liquid-containing mixture produced at the bottom of the flash device and the composite agent in the agent storage device are mixed in the mixing device and then enter the secondary vortex separation device as tangential feed, and the mass flow rate of the grey water is 80-90%, for example, it can be 80%, 83%, 85%, 88%, 89% or 90%, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0048] The solid content of the grey water is 5-30 ppm, for example, it can be 5 ppm, 8 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm or 30 ppm, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0049] As a preferred technical solution of the present application, the coal gasification black water treatment method comprises:

[0050] The coal gasification black water enters the primary vortex separation device in a tangential feeding manner, and after solid concentration, the clear liquid with a mass flow rate of 60-80% and a solid content of 0.1-0.3% generated at the top is pressurized by a circulating pump and returned to the water washing tower to wash and remove solids from the process gas; the thick liquid at the bottom enters the flash device for cooling;

[0051] The flash steam generated at the top of the flash device is cooled by a water cooling device and then enters the grey water storage device; the solid-containing liquid generated at the bottom of the flash device is mixed with the composite reagent in the reagent storage device in a mixing device, and then enters the secondary vortex separation device in a tangential feeding manner, the grey water with a mass flow rate of 80-90% and a solid content of 5-30 ppm generated at the top enters the grey water storage device; and the solid concentrated liquid generated at the bottom is sent to a filter press for treatment;

[0052] The mass of the composite reagent accounts for 0.01-0.02% of the mass of the solid-containing liquid generated at the bottom of the flash device; the composite reagent comprises reagent A and reagent B in a mass ratio of (0.1-10):1; the reagent A comprises a coagulant, and the reagent B comprises a flocculant;

[0053] The preparation method of the reagent A comprises: mixing aluminum chloride and ferrous sulfite in a mass ratio of (1-2):1 in water to obtain a mixed solution with a mass concentration of 40-60%; then adding a sulfuric acid solution with a concentration of 95-98 wt% and sodium chloride, adjusting the pH of the solution to 4-5, and performing first solid-liquid separation; dissolving the filter cake with water, heating to 80-90°C, and keeping for 1-3 h to perform second solid-liquid separation, and the obtained filtrate is the reagent A;

[0054] The amount of sodium chloride added accounts for 8-10% of the mass of the mixed solution;

[0055] The preparation method of the reagent B comprises: mixing a complexing agent solution and a dimethyldiallylammonium chloride aqueous solution in a mass ratio of 1:(0.5-1) to obtain a mixed solution; under a nitrogen atmosphere, the mixed solution is mixed with an initiator solution in a mass ratio of (10-100):1 at a temperature of 70-80°C, and stirred for 10-20 h to obtain the reagent B;

[0056] The complexing agent solution comprises any one of disodium ethylenediaminetetraacetate solution, sodium nitrilotriacetate solution or diethylenetriaminepentaacetate solution or a combination of at least two thereof; the concentration of the complexing agent solution is 5-15 g / L;

[0057] The concentration of the dimethyl diallyl ammonium chloride aqueous solution is 50-60 wt%.

[0058] The initiator solution comprises any one of ammonium persulfate solution, azobisisobutyronitrile solution or dibenzoyl peroxide solution or a combination of at least two thereof; the concentration of the initiator solution is 60-80 g / L.

[0059] Compared with the prior art, the present application has at least the following beneficial effects:

[0060] (1) The coal gasification black water treatment device system provided by the present application cancels the high-pressure flash evaporation device, low-pressure flash evaporation device, oxygen removal device and sedimentation device that need to be provided in the traditional coal gasification black water treatment device system, adopts two-stage vortex separation devices to improve the solid-liquid separation effect of the coal gasification black water, so that the coal gasification black water can meet the requirements of the traditional process after simple treatment, and the requirements of the downstream biochemical treatment, thereby solving the problems of complex process flow, large equipment occupation area and low heat utilization rate in the prior art.

[0061] (2) The coal gasification black water treatment device system provided by the present application returns the high-temperature clear liquid at the top of the first-stage vortex separation device to the water washing tower to wash and remove solids from the process gas, thereby realizing the reuse of high-temperature hot water and increasing the heat utilization rate by more than 10%. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 is a schematic diagram of the coal gasification black water treatment device system provided by the embodiment 1 of the present application.

[0063] In the figure, 1 is a first-stage vortex separation device, 2 is a circulating pump, 3 is a pressure reducing valve, 4 is a flash evaporation device, 5 is a mixing device, 6 is a reagent storage device, 7 is a reagent feeding pump, 8 is a water cooling device, 9 is a second-stage vortex separation device, and 10 is a grey water storage device. DETAILED DESCRIPTION

[0064] The technical solutions of the present application will be further described below by means of specific embodiments and in conjunction with the accompanying drawings.

[0065] The present application will be further described below. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0066] It should be understood that, in the description of the present application, the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0067] It should be noted that, in the description of the present application, unless otherwise specified and limited, the terms "provided", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0068] Those skilled in the art should understand that the present application necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing the complete process, but the above content is not the main point of the present application, and those skilled in the art can add layout by themselves based on process flow and equipment structure selection, and the present application does not make special requirements and specific limitations.

[0069] The coal gasification black water in the following examples and comparative examples is the black water obtained by mixing coal residue with water in the process of producing CO and H2 by coal gasification. The solid content of the untreated coal gasification black water is 1wt%.

[0070] Example 1

[0071] The present embodiment provides a coal gasification black water treatment device system, a schematic diagram of which is shown in Figure 1 .

[0072] The coal gasification black water treatment device system comprises a first vortex separation device 1, a flash device 4, a mixing device 5, a second vortex separation device 9 and a grey water storage device 10 connected in sequence.

[0073] The coal gasification black water treatment device system further comprises a circulating pump 2 connected with the first vortex separation device 1.

[0074] The coal gasification black water processor system further comprises a medicament storage device 6 and a medicament feeding pump 7 connected in sequence; the medicament feeding pump 7 is connected with the mixing device 5; the flash device 4 is connected with a grey water storage device 10 through a water cooling device 8; a pressure reducing valve 3 is arranged between the first vortex separation device 1 and the flash device 4.

[0075] Embodiment 2

[0076] The embodiment provides a coal gasification black water treatment method, which is performed by using the coal gasification black water treatment device system in embodiment 1; the coal gasification black water treatment method comprises the following steps.

[0077] After the coal gasification black water enters the first vortex separation device in a tangential feeding mode and is concentrated, the clear liquid with a mass flow ratio of 60% and a solid content of 0.3% generated at the top is returned to the water washing tower through a circulating pump after being pressurized, so as to wash and remove the solid from the process gas; the concentrated liquid at the bottom enters the flash device for cooling;

[0078] The flash steam generated at the top of the flash device enters the grey water storage device after being cooled by the water cooling device; the solid-containing liquid generated at the bottom of the flash device and the composite medicament in the medicament storage device are mixed in the mixing device and then enter the second vortex separation device in a tangential feeding mode, the grey water with a mass flow ratio of 90% and a solid content of 20ppm generated at the top enters the grey water storage device; and the concentrated solid liquid generated at the bottom is sent to the pressure filtration device for treatment.

[0079] The mass of the composite medicament accounts for 0.01% of the mass of the solid-containing liquid generated at the bottom of the flash device; the composite medicament comprises medicament A and medicament B in a mass ratio of 1:1;

[0080] The preparation method of the medicament A comprises the following steps: aluminum chloride and ferrous sulfite in a mass ratio of 1:1 are mixed in water to obtain a mixed solution with a mass concentration of 40%; after a 98wt% sulfuric acid solution and sodium chloride are added, the pH of the solution is adjusted to 5, and first solid-liquid separation is performed; the filter cake is dissolved in water, heated to 90℃ and kept for 2h, and second solid-liquid separation is performed, so that the filtrate is obtained as the medicament A;

[0081] The added amount of the sodium chloride accounts for 9% of the mass of the mixed solution;

[0082] The preparation method of the medicament B comprises the following steps: a dimethyl diallyl ammonium chloride aqueous solution and an ethylenediaminetetraacetic acid disodium solution are mixed in a mass ratio of 1:0.5 to obtain a mixed solution; under a nitrogen atmosphere, the mixed solution and an ammonium persulfate solution are mixed in a mass ratio of 10:1 at a temperature of 70℃, and stirred for 10h, so that the medicament B is obtained.

[0083] The concentration of the ethylenediamine tetraacetic acid disodium solution is 10 g / L; the concentration of the dimethyl diallyl ammonium chloride aqueous solution is 60 wt%; and the concentration of the ammonium persulfate solution is 60 g / L.

[0084] The solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device in the embodiment is 15%, which meets the inlet requirement of the filter press and achieves the purpose of replacing the traditional treatment process.

[0085] Embodiment 3

[0086] The embodiment provides a coal gasification black water treatment method, which is performed by using the coal gasification black water treatment device system in embodiment 1; the coal gasification black water treatment method comprises the following steps.

[0087] After the coal gasification black water enters the primary vortex separation device in a tangential feeding mode and is concentrated, the clear liquid with a mass flow ratio of 65% and a solid content of 0.23% generated at the top is pressurized by a circulating pump and then returned to the water washing tower to wash and remove the solid from the process gas; and the concentrated liquid generated at the bottom enters a flash device to be cooled.

[0088] The flash steam generated at the top of the flash device is cooled by a water cooling device and then enters a grey water storage device; the solid-containing liquid generated at the bottom of the flash device and the composite reagent in the reagent storage device are mixed in a mixing device and then enter the secondary vortex separation device in a tangential feeding mode; the grey water with a top mass flow ratio of 88% and a solid content of 18 ppm generated at the top enters the grey water storage device; and the solid concentrated liquid generated at the bottom is sent to a filter press device for treatment.

[0089] The mass of the composite reagent accounts for 0.016% of the mass of the solid-containing liquid generated at the bottom of the flash device; and the composite reagent comprises reagent A and reagent B in a mass ratio of 3:1.

[0090] The preparation method of the reagent A comprises the following steps: aluminum chloride and ferrous sulfite in a mass ratio of 1.5:1 are mixed in water to obtain a mixed solution with a mass concentration of 40%; then a sulfuric acid solution with a concentration of 95.8 wt% and sodium chloride are added, the pH of the solution is adjusted to 4.7, and first solid-liquid separation is performed; the filter cake is dissolved in water, heated to 90 ℃ and kept for 2 h, and then second solid-liquid separation is performed, so that the filter liquor is obtained as the reagent A.

[0091] The added amount of the sodium chloride accounts for 10% of the mass of the mixed solution.

[0092] The preparation method of the reagent B comprises the following steps: a diethylenetriamine pentaacetate solution and a dimethyl diallyl ammonium chloride aqueous solution are mixed in a mass ratio of 1:0.7 to obtain a mixed solution; under a nitrogen atmosphere, the mixed solution and a dibenzoyl peroxide solution are mixed in a mass ratio of 40:1 at a temperature of 78 ℃, and stirred for 11 h, so that the reagent B is obtained.

[0093] The concentration of the diethylenetriamine pentacarboxylate solution is 13 g / L; the concentration of the dimethyl diallyl ammonium chloride aqueous solution is 60 wt%; and the concentration of the benzoyl peroxide solution is 70 g / L.

[0094] In this embodiment, the solid concentrate produced at the bottom of the secondary vortex separator has a solid content of 17%, which meets the inlet requirements of the filter press and achieves the purpose of replacing the traditional processing flow.

[0095] Example 4

[0096] This embodiment provides a method for treating black water from coal gasification, using the coal gasification black water treatment device system described in Embodiment 1; the method includes:

[0097] The coal gasification black water enters the first-stage vortex separator for solid concentration via tangential feeding. The clear liquid generated at the top, with a mass flow rate of 62% and a solid content of 0.2%, is pressurized by a circulating pump and returned to the water washing tower to wash and remove solids from the process gas. The concentrated liquid at the bottom enters the flash evaporator for cooling.

[0098] The flash steam generated at the top of the flash evaporator is cooled by a water cooling device and then enters the ash water storage device; the solid-liquid mixture generated at the bottom of the flash evaporator is mixed with the composite reagent in the reagent storage device and then fed tangentially into the secondary vortex separator; the ash water generated at the top with a mass flow rate of 85% and a solid content of 25 ppm enters the ash water storage device; the solid concentrate generated at the bottom is sent to the filter press for treatment.

[0099] The mass of the composite agent accounts for 0.016% of the solid-liquid mixture generated at the bottom of the flash evaporator; the composite agent comprises agent A and agent B in a mass ratio of 6:1.

[0100] The preparation method of the reagent A includes: mixing aluminum chloride and ferrous sulfite in water at a mass ratio of 2:1 to obtain a mixed solution with a mass concentration of 40%; then adding sulfuric acid solution with a concentration of 97wt% and sodium chloride, adjusting the pH of the solution to 4.4, and performing a first solid-liquid separation; dissolving the filter cake in water, heating it to 85°C, maintaining it for 3 hours, and performing a second solid-liquid separation, the resulting filtrate being reagent A;

[0101] The amount of sodium chloride added accounts for 8% of the mass of the mixed solution;

[0102] The preparation method of the reagent B includes: mixing a disodium ethylenediaminetetraacetate solution and a dimethyldiallylammonium chloride aqueous solution at a mass ratio of 1:0.6 to obtain a mixed solution; and mixing the mixed solution with an ammonium persulfate solution at a mass ratio of 60:1 at a temperature of 73°C under a nitrogen atmosphere and stirring for 12 hours to obtain reagent B.

[0103] The concentration of the disodium ethylenediaminetetraacetate solution is 13 g / L; the concentration of the dimethyl diallyl ammonium chloride aqueous solution is 55 wt%; and the concentration of the ammonium persulfate solution is 63 g / L.

[0104] In this embodiment, the solid concentrate produced at the bottom of the secondary vortex separator has a solid content of 14%, which meets the inlet requirements of the filter press and achieves the purpose of replacing the traditional processing flow.

[0105] Example 5

[0106] This embodiment provides a method for treating black water from coal gasification, using the coal gasification black water treatment device system described in Embodiment 1; the method includes:

[0107] The coal gasification black water enters the first-stage vortex separator for solid concentration via tangential feeding. The clear liquid generated at the top, with a mass flow rate of 60% and a solid content of 0.3%, is pressurized by a circulating pump and returned to the water washing tower to wash and remove solids from the process gas. The concentrated liquid at the bottom enters the flash evaporator for cooling.

[0108] The flash steam generated at the top of the flash evaporator is cooled by a water cooling device and then enters the ash water storage device; the solid-liquid mixture generated at the bottom of the flash evaporator is mixed with the composite reagent in the reagent storage device and then fed tangentially into the secondary vortex separator; the ash water generated at the top with a mass flow rate of 90% and a solid content of 10 ppm enters the ash water storage device; the solid concentrate generated at the bottom is sent to the filter press for treatment.

[0109] The mass of the composite agent accounts for 0.01% of the solid-liquid mixture generated at the bottom of the flash evaporator; the composite agent comprises agent A and agent B in a mass ratio of 1:1.

[0110] The preparation method of the reagent A includes: mixing aluminum chloride and ferrous sulfite in water at a mass ratio of 1.3:1 to obtain a mixed solution with a mass concentration of 40%; then adding sulfuric acid solution with a concentration of 95wt% and sodium chloride, adjusting the pH of the solution to 4, and performing a first solid-liquid separation; dissolving the filter cake in water, heating it to 80℃, maintaining it for 1 hour, and performing a second solid-liquid separation, the obtained filtrate being reagent A;

[0111] The amount of sodium chloride added accounts for 8.8% of the mass of the mixed solution;

[0112] The preparation method of the reagent B includes: mixing sodium triacetate solution and dimethyl diallyl ammonium chloride aqueous solution in a mass ratio of 1:0.5 to obtain a mixed solution; under a nitrogen atmosphere, mixing the mixed solution with ammonium persulfate solution in a mass ratio of 10:1 at a temperature of 70°C and stirring for 20 hours to obtain reagent B;

[0113] The concentration of the sodium nitrilotriacetate solution is 10 g / L; the concentration of the dimethyl diallyl ammonium chloride aqueous solution is 50 wt%; and the concentration of the ammonium persulfate solution is 60 g / L.

[0114] The solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device in this embodiment is 16%, which meets the inlet requirement of the filter press and achieves the purpose of replacing the traditional treatment process.

[0115] Example 6

[0116] This embodiment provides a coal gasification black water treatment method, which is carried out by using the coal gasification black water treatment device system in Example 1; and the coal gasification black water treatment method is the same as that in Example 2, except that the mass ratio of the agent A to the agent B in the composite agent is 0.01:1.

[0117] Example 7

[0118] This embodiment provides a coal gasification black water treatment method, which is carried out by using the coal gasification black water treatment device system in Example 1; and the coal gasification black water treatment method is the same as that in Example 2, except that the mass ratio of the agent A to the agent B in the composite agent is 15:1.

[0119] It can be seen from the combination of Example 1 and Examples 6-7 that the low proportion of the agent A in the composite agent in Example 6 can cause part of the fine particles to be unable to form flocs and to be entrained by the top overflow, resulting in a high solid content of the top overflow; and the high proportion of the agent A in the composite agent in Example 7 can cause the flocs to be unable to settle and to be in a floating state, which are entrained by the top overflow, resulting in a high solid content of the top overflow.

[0120] Comparative Example 1

[0121] This comparative example provides a coal gasification black water treatment device system, which is the same as that in Example 1, except that the mixing device 5, the agent storage device 6 and the dosing pump 7 are not arranged.

[0122] This comparative example also provides a coal gasification black water treatment method, which is carried out by using the above-mentioned coal gasification black water treatment device system; and the coal gasification black water treatment method is the same as that in Example 2, except that no composite agent is added, i.e., the solid-liquid containing liquid generated at the bottom of the flash device 4 directly enters the secondary vortex separation device in a tangential feeding mode.

[0123] The solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device in this comparative example is 14%, which meets the inlet requirement of the filter press, and the mass flow proportion of the grey water generated at the top is 88%, and the solid content is too high, i.e., 1000 ppm, which can cause the activity of the biochemical sludge at the rear end to be reduced and unable to meet the treatment requirement.

[0124] Comparative Example 2

[0125] The comparative example provides a coal gasification black water treatment method, which is carried out by using the coal gasification black water treatment device system described in Example 1; the coal gasification black water treatment method is the same as that in Example 2, except that only reagent A is used, and reagent B is not prepared.

[0126] In the comparative example, the solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device is 14.2%, which meets the inlet requirement of the filter press, and the mass flow rate of the ash water generated at the top accounts for 90%, and the solid content is too high, which is 800 ppm, which will reduce the activity of the biochemical sludge at the rear end and cannot meet the treatment requirement.

[0127] Comparative Example 3

[0128] The comparative example provides a coal gasification black water treatment method, which is carried out by using the coal gasification black water treatment device system described in Example 1; the coal gasification black water treatment method is the same as that in Example 2, except that only reagent B is used, and reagent A is not prepared.

[0129] In the comparative example, the solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device is 14.4%, which meets the inlet requirement of the filter press, and the mass flow rate of the ash water generated at the top accounts for 90%, and the solid content is too high, which is 600 ppm, which will reduce the activity of the biochemical sludge at the rear end and cannot meet the treatment requirement.

[0130] Comparative Example 4

[0131] The comparative example provides a coal gasification black water treatment method, which is carried out by using the coal gasification black water treatment device system described in Example 1; the coal gasification black water treatment method is the same as that in Example 2, except that the complexing agent solution ethylenediaminetetraacetic acid disodium solution is not added when preparing reagent B.

[0132] In the comparative example, the solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device is 14.2%, which meets the inlet requirement of the filter press, and the mass flow rate of the ash water generated at the top accounts for 90%, and the solid content is too high, which is 780 ppm, which will reduce the activity of the biochemical sludge at the rear end and cannot meet the treatment requirement.

[0133] Comparative Example 5

[0134] The comparative example provides a coal gasification black water treatment method, which is carried out by using the coal gasification black water treatment device system described in Example 1; the coal gasification black water treatment method is the same as that in Example 2, except that the initiator solution ammonium persulfate solution is not added when preparing reagent B.

[0135] The solid content of the solid concentrated liquid generated at the bottom of the secondary vortex separation device in the present comparative example is 14.3%, which meets the inlet requirement of the filter press, and the mass flow rate of the grey water generated at the top accounts for 90%, and the solid content is too high, 750 ppm, which will reduce the activity of the biochemical sludge at the rear end and cannot meet the treatment requirement.

[0136] In conclusion, the coal gasification black water treatment device system and method provided by the present application adopts two-stage vortex separation devices for heat recovery and solid-liquid separation, wherein the secondary vortex separation device improves the solid-liquid separation effect by adding a specific composite medicament, and the treated grey water meets the requirement of the biochemical treatment at the rear end, and is suitable for wide range of popularization and application.

[0137] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for treating coal gasification black water, characterized by, The coal gasification black water treatment method is performed by using a coal gasification black water treatment device system as follows; The coal gasification black water treatment device system comprises a first vortex separation device, a flash device, a mixing device, a second vortex separation device and a grey water storage device connected in sequence; The coal gasification black water treatment method comprises: After the coal gasification black water enters the first vortex separation device for solid concentration, the concentrated liquid at the bottom enters the flash device for cooling; the flash steam generated at the top of the flash device enters the grey water storage device after cooling; the solid-containing liquid generated at the bottom of the flash device is mixed with a composite reagent in the mixing device and then enters the second vortex separation device for separation, and the grey water generated at the top enters the grey water storage device; The mass of the composite reagent accounts for 0.01-0.02% of the mass of the solid-containing liquid generated at the bottom of the flash device; the composite reagent comprises a reagent A and a reagent B in a mass ratio of (0.1-10):1, the reagent A comprises a coagulant, and the reagent B comprises a flocculant; The preparation method of the reagent A comprises: mixing aluminum chloride and iron sulfite in a mass ratio of (1-2):1 in water to obtain a mixed solution; then adding a sulfuric acid solution with a concentration of 95-98wt% and sodium chloride, adjusting the pH of the solution to 4-5, and performing first solid-liquid separation; dissolving the filter cake with water, heating to 80-90℃ and keeping for 1-3h, and performing second solid-liquid separation to obtain the reagent A.

2. The coal gasification black water treatment method of claim 1, wherein, The coal gasification black water treatment device system further comprises a circulating pump connected with the first vortex separation device.

3. The coal gasification black water treatment method of claim 1, wherein, The coal gasification black water treatment device system further comprises a reagent storage device and a reagent feeding pump connected in sequence.

4. The coal gasification black water treatment method of claim 3, wherein, The reagent feeding pump is connected with the mixing device.

5. The coal gasification black water treatment method of claim 1, wherein, The flash device is connected with the grey water storage device through a water cooling device.

6. The coal gasification black water treatment method of claim 1, wherein, A pressure reducing valve is arranged between the first vortex separation device and the flash device.

7. The coal gasification black water treatment method of claim 1, wherein, The clear liquid generated at the top of the first vortex separation device is returned to the water washing tower after being pressurized by the circulating pump to wash and remove the solid from the process gas.

8. The coal gasification black water treatment method of claim 1, wherein, The flash steam is cooled by the cooling device.

9. The method of claim 1, wherein the coal gasification black water is treated by, The composite reagent is stored in the reagent storage device and is delivered to the mixing device by the reagent feeding pump.

10. The method of claim 1, wherein the coal gasification black water is treated by, The solid concentrated liquid generated at the bottom of the second vortex separation device is sent to a filter press device for treatment.

11. The method of claim 1, wherein the coal gasification black water is treated by, The mass concentration of the mixed solution is 40%-60%.

12. The method of claim 1, wherein the coal gasification black water is treated by, The amount of sodium chloride added accounts for 8-10% of the mass of the mixed solution.

13. The method of claim 1, wherein the coal gasification black water is treated by a process comprising: The preparation method of the reagent B comprises: mixing a complexing agent solution and a dimethyldiallylammonium chloride aqueous solution in a mass ratio of 1:(0.5-1) to obtain a mixed solution; in an inert gas atmosphere, the mixed solution is mixed with an initiator solution in a mass ratio of (10-100):1 at a temperature of 70-80℃, and stirred for 10-20h to obtain the reagent B; The complexing agent solution comprises any one or a combination of at least two of disodium ethylenediaminetetraacetate solution, sodium nitrilotriacetate solution or diethylenetriamine pentacarboxylate solution.

14. The method of claim 13, wherein the coal gasification black water is treated by, The concentration of the complexing agent solution is 5-15g / L.

15. The method of claim 13, wherein the coal gasification black water is treated by a process comprising: The inert gas comprises nitrogen.

16. The method of claim 13, wherein the coal gasification black water is treated by, The concentration of the dimethyldiallylammonium chloride aqueous solution is 50-60wt%.

17. The method of claim 13, wherein the coal gasification black water is treated by, The initiator solution comprises any one or a combination of at least two of ammonium persulfate solution, azobisisobutyronitrile solution or dibenzoyl peroxide solution.

18. The method of claim 13, wherein the coal gasification black water is treated by, The concentration of the initiator solution is 60-80 g / L.

19. The method of claim 1, wherein the coal gasification black water is treated by, The coal gasification black water enters a tangential inlet of a first vortex separation device, the mass flow rate of the clear liquid is 60-80%, and the solid content of the clear liquid is 0.1-0.3%.

20. The method of claim 1, wherein the coal gasification black water is treated by, The solid-liquid containing the solid produced at the bottom of the flash device and the composite medicament in the medicament storage device are mixed in a mixing device and then enter a tangential inlet of a second vortex separation device, the mass flow rate of the grey water is 80-90%, and the solid content of the grey water is 5-30 ppm.

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