RU2363672C2 - Hydrator-separator for manufacturing of slaked lime and method for slaked lime making with its application - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention is related to the field of construction, namely to devices for lime slaking and preparation of slaked lime, and may be used in metallurgical, chemical and food industries. Hydrator-separator for lime making comprises body with hopper-feeder and unloading nozzles equipped with locks, vibrating screen installed in body, cooling system and irrigating device installed inside body, which uses water heated in cooling system. Vibrating screen consists of set of screens, having sign-alternating slopes, with cell size that reduces from upper screen to the lower one. Cooling system consists of cooling jacket and capacitor-refrigerator arranged in the upper part of body with plate device for condensate distribution to vibrating screen. Capacitor-refrigerator uses cooling water coming out of body. Method for manufacturing of slaked lime in above specified hydrator-separator includes screening of quicklime on vibrating screen together with hydration, in which water is used that is heated in cooling system.

EFFECT: lower power inputs for mixing and transportation of lime, lower heat emission, accelerated hydration, increased product yield.

2 cl, 1 tbl, 2 ex, 1 dwg

Description

The invention relates to the field of construction, and in particular to devices for the extinguishing of lime and the preparation of lime-fluff, and can be used in the metallurgical, chemical and food industries.

Known hydrator-separator for the production of hydrated oxide, containing a container with nozzles and a cooling casing, a metering feeder and an adjustable inclined grate with an adjacent perforated movable slide and shutters located at its lower end [SU 1463724].

Disadvantages: significant energy costs for fluidization, loss of product as a result of its carbonization with carbon dioxide, which is part of the air, significant thermal emissions.

A device for extinguishing lime (RU 2192398) is known, having a hydration chamber with loading and unloading openings, a chimney with an inlet, a lower part and an expansion chamber with a drain element, a means of cooling the walls of the expansion chamber to condense the outgoing liquid particles on them, made in the form a water shirt, said means of cooling the walls of the expansion chamber is combined with a sprayer, which is made in the form of a pair of disks mounted coaxially and with the possibility of free rotation around the exhaust axis pipes with the formation of a nozzle in the form of an annular gap between them, and the nozzle of the sprayer is directed radially relative to the axis of the exhaust pipe with the possibility of washing off the side walls of the expansion chamber with water, the lower part of the exhaust pipe is made for draining water from the expansion chamber, and the drain element is mounted on the bottom of the pipes with the possibility of converting the flow of water flowing from its walls into a vertical water curtain located in front of the inlet of the exhaust pipe.

Disadvantages: the complexity of the device and the significant energy consumption for mixing and conveying lime, significant heat emissions from the walls of the hydration chamber, inefficient use of the heat transfer surface of the heat transfer of the water jacket, since they are washed by a cool stream of water intended for lime hydration from the side of the air-vapor mixture, low hydration rate due to the use of cool water for her and, as a result, a low yield of product.

A known method of producing lime fluff, including calcining and extinguishing lime with water, transferring the lime fluff to a suspended state with a steam-air medium by supplying air at a rate of 22.4-112.0 l per 1 mol of lime and removing it with subsequent precipitation [RU 99106719] .

Disadvantages: significant energy consumption for transferring lime-fluff to a suspended state, carbonization of the finished product with carbon dioxide, which is part of the air.

The closest analogue of the proposed method is a method of preparing lime-fluff, including hydration of quicklime, mixing quicklime by rotating the slaking device around the longitudinal axis, sequential sieving on a vibrating screen consisting of a set of screens having different cell sizes, while the size of the cells of the lower sieves is reduced in comparison with the higher ones, division of lime-fluff into fractions in one cyclone and gravitational separator or in several cyclones, packing in packages of all fractions soda lime [RU 2003113951].

Disadvantages: significant energy costs for mixing quicklime; the untimely removal of fluff-lime from the quenching device creates the conditions for the formation of Ca (OH) ₂ films on quicklime particles and a slowdown in hydration; loss of lime and water with a gas-vapor mixture discharged from the apparatus during the quenching process; carbonization of the finished product with carbon dioxide, which is part of the air, during transportation and separation into fractions.

The technical result of the invention is to reduce energy consumption for mixing and transportation of lime, reducing heat emissions, accelerating hydration and increasing product yield.

The technical result is achieved in that a hydrator-separator for the manufacture of lime, comprising a housing with a metering feeder and discharge nozzles equipped with gates, a cooling system installed in the housing a vibrating screen, consisting of a set of screens with a mesh size decreasing from the top to the bottom, and having different sign biases. In this case, the cooling system consists of a cooling casing and a condenser-cooler installed in the upper part of the casing with a plate condensate distribution device for the indicated vibrating screen using cooling water leaving the cooling casing; inside the casing there is an irrigation device using quickheated water in the specified cooling system.

The manufacturing process of lime-fluff in the proposed hydrator-separator includes hydration of quicklime, sequential sieving on a vibrating screen, consisting of a set of sieves having different mesh sizes, decreasing from higher sieves to lower sieves. In this case, sieving and hydration of quicklime are carried out simultaneously; for hydration, water is used, heated in the cooling system of the hydrator-separator, and condensate flowing down the condensate distribution device to the indicated vibrating screen from the condenser-cooler.

The invention is illustrated in the drawing, which shows a vertical section of a hydrator-separator, shown in figure 1.

The hydrator-separator consists of a housing 1 with a cooling casing 2, to which a loading hopper with a dispenser 3, a condenser-cooler 4, discharge nozzles with valves for unloading lime-fluff 5 and not enough 6 are connected, inside the housing there are: an irrigation device 7 with a control valve 8, a plate condensate distribution device 9 and a vibrating screen 10, consisting of a set of sieves having different sign slopes, with a mesh size decreasing from the top to the bottom.

Hydrator-separator operates as follows. Quicklime enters the housing 1 through the hopper with dispenser 3, passes the zone of action of the irrigation device 7 and falls on the top screen of the vibrating screen 10. Starting from the zone of action of the irrigation device 7, the hydration process, which is the interaction of lime with water: CaO + H ₂ O = Ca (OH) ₂ . During hydration, pieces of lime decompose into finely divided particles of lime-fluff and heat, due to which the reaction mixture is heated and partial evaporation of water occurs. Water vapor, together with entrained fine particles of lime, getting into the condenser-cooler, condenses and flows in the form of milk of lime through the plate condensate distribution device 9 onto the vibrating screen 10. On it, fluffy lime wakes up through a set of screens having a mesh size decreasing from the top sieve to the bottom, and through the discharge pipe with a shutter for unloading lime-fluff 5 is removed from the device. Unfinished pieces of lime and nedal are sequentially separated by particle size on a vibrating screen 10. At the same time, the pieces that are retained on the sieves are irrigated with milk of lime flowing from the condenser-cooler 4, undergo final hydration and move through them, and the nedopal and non-quenched pieces approach the discharge the nozzle with a shutter for unloading was not reached 6 and is removed from the device. The cooling system of the hydrator-separator, consisting of a cooling casing 2 and a condenser-cooler 4, serves to maintain the optimum temperature of the hydration process, heat the water supplied to the irrigation device 7, and reduce heat emissions. The cooling water sequentially passes through the cooling jacket 2, the condenser-cooler 4 and is heated to the temperature necessary to ensure a high intensity of the quenching process. Excess cooling water is diverted for external consumption.

Reducing the energy costs of mixing and transporting lime is achieved by using vibration transportation, combined with hydration and separation, instead of using shafts with vanes for transportation and mixing, used in the analogue.

Reducing heat emissions is achieved by removing heat generated during hydration, the cooling system. The use of a condenser-cooler allows, on the one hand, to provide vapor condensation and gas cooling, and on the other hand, to create a condensate film on a large heat-exchange surface that traps lime particles entrained by the vapor-air mixture from the reaction volume. Moreover, in the prototype, heat removal from the vapor-gas mixture to the cooling water in the water jacket is difficult, since the inner side is irrigated with a stream of cold water supplied by the sprayers. Hot water discharged from the cooling system of the hydrator-separator is intended for external consumption, i.e. the proposed hydrator-separator provides for the use of thermal waste.

Acceleration of hydration is achieved by maintaining the optimal process temperature, achieved, on the one hand, by using water heated in the cooling system for it, and on the other, by removing excess heat from the reaction volume by the cooling system.

Reducing product losses is achieved by accelerating the hydration process, timely separation of the product from raw materials and the ability to control the residence time of quicklime in the reaction volume, by changing the frequency and amplitude of vibrating screens. Fine particles of lime, carried away by the gas-vapor mixture, are returned to the apparatus together with the condensate in the form of milk of lime. Unfinished pieces of lime and nedal are sequentially separated by particle size on a vibrating screen 10. In this case, the pieces held on the sieves are irrigated with condensate draining from the condenser-cooler 4, undergo final hydration and move through them until the last sieve with the smallest cells is reached , and the pieces that have not been extinguished go to the discharge port with a shutter for the discharge 6 and are removed from the case of the hydrator-separator.

The advantages of the invention are illustrated by examples.

Example 1. Get lime fluff. To do this, they extinguish 2.27 kg of quicklime containing 92% CaO + MgO, mixing it with 0.752 kg of water with a temperature of 80 ° C in a container with a cooling casing on a vibrating screen for 10 minutes. The resulting water vapor is condensed and returned to the reaction volume. Water with a temperature of 20 ° C is supplied for cooling and condensation and discharged with a temperature of 80 ° C. The amount of cooling water is 8.24 kg. Measure the temperature in the tank. It is 90 ° C. Lime-fluff separated on a vibrating screen and weakened are weighed and the chemical composition of the feedstock and product is analyzed. The results are placed in a table.

Example 2. Carry out the process by a known method. Get lime fluff. To do this, they extinguish 2.27 kg of quicklime containing 92% CaO + MgO, mix it with 1.577 kg of water with a temperature of 20 ° C in a rotating container for 10 minutes. Measure the temperature in the tank: it is 97 ° C. The reaction mixture is separated on a vibrating screen. Separated on a vibrating screen, lime-fluff and nedopal are weighed and the chemical composition of the feedstock and product is analyzed. The results are placed in a table.

Analysis of the data in the table shows that the proposed method allows to increase the yield of the finished product for CaO + MgO from 94% to 96%, to reduce the loss of water and quicklime from 26.5% to 1%, to reduce the amount of water supplied to the quenching, from 41% up to 24.9%. Moreover, in the proposed method, the temperature of the reaction mixture is reduced, which allows to obtain fluff lime with a smaller particle size, and hence with higher solubility in water and higher activity. The proposed method produces 8.24 kg of water with a temperature of 80 ° C, which can be used for technological needs both directly in the process of producing lime fluff, and for other technological purposes or domestic needs.

Comparison of the parameters of production methods Material Example No. 1 Example No. 2 Quicklime, kg
including 2,270 2,270 CaO + MgO, kg
% 2,088 2,088 92 92 CaCO ₃ , kg
% 0.01 0.01 0.4 0.4 Ballast kg
% 0.171 0.171 7.9 7.9 Water kg
% 0.872 1,577 24.9 41.0 Lime fluff, kg
including 2,649 2,594 CaO + MgO, kg
%
exit % 2,005 1,962 73.1 72.9 96.0 94.0 CaCO ₃ , kg
% 0.010 0,020 0.4 0.7 Water kg
% 0.725 0.712 26.5 26,4 Not enough, kg
% 0.265 0.244 11.7 10.8 Loss kg
% 0,030 1.019 1,0 26.5

Claims (2)

1. A hydrator-separator for the manufacture of lime, comprising a housing with a metering feeder and discharge nozzles equipped with gates, a vibrating screen installed in the housing, consisting of a set of screens having different slopes, with a mesh size decreasing from the top to the bottom, a cooling system, consisting of a cooling casing and a condenser-cooler made in the upper part of the casing with a plate condensate distribution device for said vibrating screen using cooling water leaving the cooling system casing, and an irrigation device located inside the casing using water heated in said cooling system. 2. A method of manufacturing lime-fluff, including hydration of quicklime, sequential sieving on a vibrating screen, consisting of a set of sieves having different mesh sizes, decreasing from the upper sieve to the lower one, characterized in that when it is carried out in a hydrator-separator according to claim 1 sifting and hydration of quicklime are carried out simultaneously, in which water heated in the specified cooling system is used.

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