Titanium dioxide calcination rotary kiln feed process and equipment
Technical field
The present invention relates to a kind of rotary kiln feed process and equipment, be specifically related to a kind of rotary kiln feed process for titanium dioxide calcining and equipment, belong to field of titanium dioxide production.
Background technology
In sulfuric acid method titanium pigment production technique, calcining is one of three most critical operations determining titanium dioxide quality.The calcination process of titanium dioxide is roughly as follows: hydrolysate metatitanic acid is sloughed after most of moisture through diaphragm filter press, by worm conveyor input, there is constant slope (being generally 3-5%) and slow pivotal titanium dioxide rotary kiln (also claiming feed end or high-end), simultaneously the flame of cleaning and hot blast are blown in kiln by the combustion chamber of kiln hood (i.e. discharge end or low side), are dewatered, desulfurization and transformation of crystal to material.Material after high-temperature calcination, by the kiln body tilted and self gravitation, from the combustion chamber blanking port of kiln hood out, then delivers to abrasive dust operation through cooling.In order to meet titanium dioxide calcining process, must ensure that rotary kiln end temperature is at 900-950 DEG C, kiln end temperature is at 350-450 DEG C.Hot gas flow in rotary kiln and material after direct heat exchange, remove most solid particulate by kiln tail gravity settling and cyclone dust removal, then through Venturi spray washing cooling, secondary packing tower spray washing cooling and electric demist removing acid mist after cause chimney discharged to air by induced draft fan.
There is following point in existing titanium dioxide calcining process: 1. moisture content 50-55% when metatitanic acid material enters rotary kiln, and moisture content is higher, cause calcination process energy consumption high, yield poorly, general titanium dioxide per ton needs energy consumption 280-300 ten thousand kilocalorie,
rotary kiln annual production only about 20,000 tons; 2. titanium dioxide calcining is gradient calcining, and the temperature difference is large, unstable product quality; 3. kiln tail exhaust temperature is up to 350-450 DEG C, needs spraying cooling discharged to air after dedusting, and high-temperature flue gas heat does not make full use of.The object of the invention is for above-mentioned prior art Problems existing, rotary kiln dehydration feeding process is improved, changes expansion drying feed system into by original barrier film press filtration feed system, thus raising plant factor, improve output, reduce energy consumption, improve product burning quality simultaneously.
Summary of the invention
The object of this invention is to provide a kind of titanium dioxide calcination rotary kiln expansion drying feed process and equipment, can improve calciner utilization ratio, separate unit rotary kiln production capacity improves 50-80%, and energy consumption reduces 10-35%, also can improve product burning quality.
The present invention is achieved through the following technical solutions:
A kind of titanium dioxide calcination rotary kiln feed process, comprises supplying step, flash drying step, recycling step, collection step and vent gas treatment step;
Described supplying step is will be separated through diaphragm filter press (1) to press dry to moisture content to be the metatitanic acid material of 50-55%, to input expansion drying main frame (4) through rotary conveyor (2) and the first worm conveyor (3);
Described flash drying step contacts with the high-temperature flue gas from kiln tail for the metatitanic acid material entering expansion drying main frame (4), under the high speed rotating effect of bottom rotating paddle (11), material is broken, disperse, dry, the material that part falls into bottom imports the second worm conveyor (5) by the first star-shaped discharge valve (8) and enters rotary kiln (7) again;
Described recycling step is dry powdery and small particles material, under vacuum negative pressure condition under high-pressure suction fan (14) effect, tangentially enter tornado dust collector (6) with gyration airflow from expansion drying main frame top, the material of separation imports the second worm conveyor (5) by the second star-shaped discharge valve (9) and enters rotary kiln (7) again;
Described collection step be containing powdery or granule materials water vapour from tornado dust collector (6) top out, collect powder or granule materials by bag filter (12);
Described vent gas treatment step is the flue gas through bag filter (12), and temperature is reduced to 100-150 DEG C, then absorbs a small amount of SO in flue gas through alkali liquor absorption tower 10
2and SO
3after, will qualified tail gas be processed discharged to air by high-pressure suction fan (14).
Implement the equipment of the method for the invention, comprise: diaphragm filter press (1), rotary conveyor (2), first worm conveyor (3), expansion drying main frame (4), second worm conveyor (5), tornado dust collector (6), rotary kiln (7), high-pressure suction fan (14), alkali liquor absorption tower (10), alkali lye spray pump (13), alkali lye storage tank (15), bag filter (12);
Wherein: material to be dried is flowed to expansion drying main frame (4) by the first worm conveyor (3), the bottom of expansion drying main frame (4) arranges rotating paddle (11), main frame top connects tornado dust collector (6), tornado dust collector (6) connecting bag filter (12), bag filter (12) connects alkali liquor absorption tower (10), alkali liquor absorption tower (10) is connected with alkali lye spray pump (13), alkali lye spray pump (13) connects alkali lye storage tank (15), and alkali liquor absorption tower (10) connects high-pressure suction fan (14); Expansion drying main frame (4) and tornado dust collector (6) bottom are respectively equipped with the first star-shaped discharge valve (8), the second star-shaped discharge valve (9);
Described expansion drying main frame, cylindrical shell serves as a contrast two-layer corundum-mullite refractory brick again by carbon steel line with rubber and carries out rotproofing;
Described expansion drying main frame, bottom is made into taper and perforate, is connected with the second worm conveyor (5) by the first star-shaped discharge valve (8);
Described cyclonic separator (6) bottom is made into taper and perforate, is connected with the second worm conveyor (5) by the second star-shaped discharge valve (9);
Described rotating paddle (11) is four layers of squirrel-cage disperser blade, and to improve resistance to impact shock and breaking capacity, improve the dispersity of material, accelerate heat transfer effect, material adopts Hastelloy.
Described alkali liquor absorption tower (10) installs a valve in bottom tank body perforate, and alkali concn is low by the time, regularly carries out being disposed to sewage plant when can not meet processing requirement; Alkali lye spray pump (13) connects alkali liquor absorption tower (10) and alkali lye storage tank (15) respectively, can add alkali lye to meet processing requirement when the alkali lye basicity in alkali liquor absorption tower (10) is inadequate.
Adopt above-mentioned expansion drying feed process and equipment, when entering rotary kiln, metatitanic acid moisture drops to 10-15%, three phases is divided into calcine in rotary kiln, each phase temperature gradient comparatively traditional technology diminishes, rotary kiln rotating speed keeps 0.25-0.33 rev/min, metatitanic acid ensures the residence time of 5-6.5 hour in rotary kiln, and calcination time shortens.
The present invention has following advantages:
1. because feed moisture content is low, calcination time shortens, and calciner utilization ratio is improved, and separate unit rotary kiln production capacity improves 50-80%, also reduces calcinating consumption simultaneously.
2. make full use of the high-temperature flue gas of rotary kiln, provide thermal source, do not need external source, obvious energy conservation by it to expansion drying system, energy consumption reduces 10-35%.
3. the improvement of feeding process, the thermograde of calcining process is diminished, improves product burning quality, titanium dioxide reducing power reaches 120, and brightness reaches 94.5.
Accompanying drawing explanation
Fig. 1 is titanium dioxide calcination rotary kiln expansion drying apparatus for feeding of the present invention
In figure: 1-diaphragm filter press; 2-rotary conveyor; 3-first worm conveyor; 4-expansion drying main frame; 5-second worm conveyor; 6-tornado dust collector; 7-rotary kiln; 14-high-pressure suction fan; 8-first star-shaped discharge valve; 9-second star-shaped discharge valve; 10-alkali liquor absorption tower; 13-alkali lye spray pump; 11-rotating paddle; 12-bag filter; 15-alkali lye storage tank.
Embodiment
Titanium dioxide calcination rotary kiln feed process, comprises the following steps:
1. supplying step: will be separated through diaphragm filter press (1) and press dry to moisture content to be the metatitanic acid material of 50-55%, to input expansion drying main frame (4) through rotary conveyor (2) and the first worm conveyor (3);
2. flash drying step: the metatitanic acid material entering expansion drying main frame (4) contacts with the high-temperature flue gas from kiln tail, high-temperature flue-gas is 350-450 DEG C, under the high speed rotating effect of bottom rotating paddle 11, material is broken, disperse, dry, the material that part falls into bottom imports the second worm conveyor (5) by the first star-shaped discharge valve (8) and enters rotary kiln (7) again;
3. recycling step: dry powdery and small particles material, under vacuum negative pressure condition under high-pressure suction fan (14) effect, tangentially enter tornado dust collector (6) with gyration airflow from expansion drying main frame top, moisture content is that the material of 10-15% imports the second worm conveyor (5) by the second star-shaped discharge valve (9) and enters rotary kiln (7) again;
4. collect step: containing powdery or granule materials water vapour from tornado dust collector (6) top out, collect powder or granule materials by bag filter (12);
5. vent gas treatment step: through the flue gas of bag filter (12), temperature is reduced to 100-150 DEG C, then absorb a small amount of SO in flue gas through alkali liquor absorption tower (10)
2and SO
3after, will qualified tail gas be processed discharged to air by high-pressure suction fan (14).
Adopt above-mentioned expansion drying feed process and equipment, the material entering rotary kiln (7) divides three phases to calcine, each stage accounts for 1/3rd of the whole length of rotary kiln respectively, namely 13 meters, first stage temperature controls at 500-700 DEG C, residence time 1.5-2 hour, this section of Main Function was the crystal water again sloughed inside metatitanic acid; Subordinate phase temperature controls at 700-850 DEG C, and residence time 1.5-2 hour, this section of Main Function was desulfurization; Phase III temperature controls at 850-950 DEG C, residence time 2-2.5 hour, and this section of Main Function is transformation of crystal, particle diameter is grown up and calcining qualified product flow out to cooling drum from rotary kiln low side.Rotating speed in calcination process in rotary kiln is controlled by variable-frequency motor, and per minute keeps 0.25-0.33 rev/min, and metatitanic acid ensures the residence time of 5-6.5 hour in rotary kiln.
Titanium dioxide calcination rotary kiln expansion drying apparatus for feeding, comprise the diaphragm filter press (1) that filtration area is 120 square metres, the rotary conveyor (2) of 6000*1100*600, first worm conveyor (3) of 4000*350, model is the expansion drying main frame (4) of XSG-10000, second worm conveyor (5) of 4000*350, the tornado dust collector (6) of model C ZT-850, 1.83*39m rotary kiln (7), high-pressure suction fan (14), alkali liquor absorption tower (10), alkali lye spray pump (13), alkali lye storage tank (15), bag filter (12), wherein material to be dried is flowed to expansion drying main frame (4) by the first worm conveyor (3), the bottom of expansion drying main frame (4) arranges rotating paddle (11), main frame top connects tornado dust collector (6), tornado dust collector (6) connecting bag filter (12), bag filter (12) connects alkali liquor absorption tower (10), alkali liquor absorption tower is connected with alkali lye spray pump (13), alkali lye spray pump (13) connects alkali lye storage tank (15), and alkali liquor absorption tower (10) connects high-pressure suction fan (14), expansion drying main frame (4) and tornado dust collector (6) bottom are respectively equipped with the first star-shaped discharge valve (8), second star-shaped discharge valve (9) of model XXL200.
Described expansion drying main frame, cylindrical shell serves as a contrast two-layer corundum-mullite refractory brick again by carbon steel line with rubber and carries out rotproofing;
Described expansion drying main frame, bottom is made into taper and perforate, and by the first star-shaped discharge valve (8), (5 are connected with the second worm conveyor; After material adds main frame, part not by swirling eddy take away the material be deposited on bottom expansion drying main frame need not stop process be directly delivered to rotary kiln;
Described cyclonic separator (6) bottom is made into taper and perforate, is connected with the second worm conveyor (5) by the second star-shaped discharge valve (9);
Described rotating paddle (11) is four layers of squirrel-cage disperser blade, and to improve resistance to impact shock and breaking capacity, improve the dispersity of material, accelerate heat transfer effect, material adopts Hastelloy.
Described alkali liquor absorption tower (10) installs a valve in bottom tank body perforate, and alkali concn is low by the time, regularly carries out being disposed to sewage plant when can not meet processing requirement; Alkali lye spray pump (13) connects alkali liquor absorption tower (10) and alkali lye storage tank (15) respectively, can add alkali lye to meet processing requirement when the alkali lye basicity in alkali liquor absorption tower (10) is inadequate.
After adopting above-mentioned expansion drying feed process and equipment, produce titanium dioxide every day and bring up to 18-20 ton by original 10-12 ton, rotary kiln flue-gas temperature drops to 100-150 DEG C by original 350-450 DEG C, and energy consumption consumes anthracite 550-650Kg by original titanium dioxide per ton and drops to titanium dioxide per ton consumption anthracite 360-430Kg.