Chemical heat pump based on calcium oxide-calcium hydroxide three-stage digester

Abstract

The utility model discloses a chemical heat pump based on a calcium oxide-calcium hydroxide three-stage digester, and solves the problems of how to effectively and fully utilize heat energy of produced high-temperature steam and how to utilize the heat energy to improve the calcium hydroxide production efficiency of a quick lime digester in the process of producing slaked lime from quick lime. Based on the structure of a three-stage quick lime digester, the quick lime digester is transformed into a chemical heat pump capable of generating high-temperature steam, and in the process of converting calcium oxide into calcium hydroxide, heat energy generated in the chemical reaction process is fully excited and is led out and utilized in the form of high-temperature steam; part of led-out high-temperature steam is creatively circulated and returned to the digester, meanwhile, the double effects of exciting the high-temperature steam and improving the production efficiency of calcium hydroxide are achieved, and sufficient excitation of chemical reaction heat energy and sufficient leading-out and utilization of heat release energy are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a quicklime digester for generating calcium hydroxide from calcium oxide, and in particular to a chemical heat pump based on a three-stage calcium oxide-calcium hydroxide digester and a working method thereof. BACKGROUND

[0002] Thermo-chemical energy storage is a process of converting thermal energy into chemical energy by using reversible chemical reactions, and storing the chemical energy in a reaction medium; when needed, the stored chemical energy is released in the form of reaction heat by reversing the thermo-chemical reaction or by combustion; since the thermo-chemical energy storage process is achieved by breaking and recombining chemical bonds, the energy is converted from "thermal energy-chemical energy-thermal energy", therefore, thermo-chemical energy storage has the advantages of large energy storage capacity, high use temperature, small heat loss during energy storage, and long-distance transportation; the research on thermo-chemical energy storage systems is still in the laboratory stage, and the calcium hydroxide-calcium oxide conversion energy storage system has been selected by LUZ Company as the preferred object for a medium-temperature solar heat storage system; at present, the building material industry generally uses calcium oxide (quicklime) mixed with water to become calcium hydroxide (slaked lime) process, and the industry generally uses a quicklime digester device to complete the above process, the focus of the entire process is on the pursuit of slaked lime products, and the high-temperature steam generated during the process is only studied from the environmental protection point of view, and the research direction is to not produce environmental pollution, without paying attention to the generation and scientific use of high-temperature steam heat, in the chemical reaction process of quicklime generating slaked lime, how to effectively and fully utilize the heat of the additional product (high-temperature steam) generated during the process has become a new research topic.

[0003] The existing lime digester mainly completes the task of converting calcium oxide into calcium hydroxide after adding water. The calcium oxide at room temperature is digested to produce hot water above 80 DEG C. This chemical heat reaction is called chemical heat pump in the industry. The specific process is as follows: the calcium oxide powder is lifted from the bottom hopper of the elevator to the top, and then enters the calcium oxide powder bin from the top. The bin sends the calcium oxide powder into the first-stage screw conveying stirrer of the three-stage digester through the feeder. The water pump starts to spray water into the first-stage screw conveying stirrer (variable frequency water spraying according to the material quantity). The calcium oxide generates calcium hydroxide after meeting water, releases heat, produces hot water, and is conveyed into the second-stage and third-stage screw conveying stirrers in turn through the conveying mode of stirring on one side, so that the calcium oxide not subjected to chemical reaction is all reacted into calcium hydroxide powder. The calcium hydroxide powder is discharged from the bottom of the third-stage digester and enters the calcium hydroxide receiving hopper. The generated hot steam is discharged from the steam outlet of the digester to the air. In the above whole process, the purity and water content of the generated calcium hydroxide are mainly controlled, and the generated hot gas is only treated as byproduct and discharged, causing the waste of this part of heat energy. How to efficiently utilize this part of heat energy and how to utilize this part of heat energy to improve the production efficiency of the lime digester become a new topic to be studied. SUMMARY

[0004] The present application provides a chemical heat pump based on a three-stage calcium oxide-calcium hydroxide digester, which solves the technical problems of how to effectively and fully utilize the heat energy of the generated high-temperature steam in the process of generating lime and how to utilize this part of heat energy to improve the production efficiency of the lime digester.

[0005] The present application solves the above technical problems through the following technical scheme:

[0006] The general idea of the present application is to transform the structure of the three-stage lime digester into a chemical heat pump capable of generating high-temperature steam. In the process of converting calcium oxide into calcium hydroxide, the heat energy generated in the chemical reaction process is fully excited and is introduced and utilized in the form of high-temperature steam. Creatively, part of the introduced high-temperature steam is circulated and sent back to the digester, which plays a dual role of exciting high-temperature steam and improving the production efficiency of calcium hydroxide.

[0007] A chemical heat pump based on a three-stage lime-lime hydroxide digester, comprising a first-stage screw conveying agitator, a second-stage screw conveying agitator, a third-stage screw conveying agitator and lime powder, a lime powder inlet is arranged at the input end of the first-stage screw conveying agitator, a second-stage agitator inlet is arranged at the input end of the second-stage screw conveying agitator, a third-stage agitator inlet is arranged at the input end of the third-stage screw conveying agitator, and a lime hydroxide outlet is arranged at the output end of the third-stage screw conveying agitator, the output port of the first-stage screw conveying agitator is communicated with the second-stage agitator inlet, and the output port of the second-stage screw conveying agitator is communicated with the third-stage agitator inlet; a first agitator water injection port is arranged at the input end of the first-stage screw conveying agitator, a second agitator water injection port is arranged at the input end of the second-stage screw conveying agitator, and a third agitator water injection port is arranged at the input end of the third-stage screw conveying agitator; the lime powder enters the first-stage screw conveying agitator through the lime powder inlet, a high-temperature steam exhaust port is arranged at the output end of the first-stage screw conveying agitator, an induced draft fan is connected to the high-temperature steam exhaust port, and a high-temperature steam conveying pipeline is connected to the output end of the induced draft fan; a high-temperature steam circulation inlet is arranged at the input end of the second-stage screw conveying agitator, a high-temperature steam circulation conveying branch pipe is connected to the high-temperature steam conveying pipeline, and the other end of the high-temperature steam circulation conveying branch pipe is communicated with the high-temperature steam circulation inlet; a lime hydroxide bin is arranged below the lime hydroxide outlet.

[0008] A second agitator tail high-temperature steam extraction port is arranged at the output end of the second-stage screw conveying agitator, a third agitator tail high-temperature steam extraction port is arranged at the output end of the third-stage screw conveying agitator, a second agitator tail high-temperature steam extraction inlet and a third agitator tail high-temperature steam extraction inlet are respectively arranged at the input end of the first-stage screw conveying agitator, a second agitator tail high-temperature steam extraction pipe is arranged between the second agitator tail high-temperature steam extraction port and the second agitator tail high-temperature steam extraction inlet, and a third agitator tail high-temperature steam extraction pipe is arranged between the third agitator tail high-temperature steam extraction inlet and the third agitator tail high-temperature steam extraction port; a cooling air inlet is arranged at the input end of the third-stage screw conveying agitator, a cooling air inlet pipe is connected to the cooling air inlet, and the other end of the cooling air inlet pipe is communicated with a hot blast stove exhaust pipe.

[0009] A working method of a chemical heat pump based on a three-stage lime-lime hydroxide digester, wherein the first-stage screw conveying agitator, the second-stage screw conveying agitator and the third-stage screw conveying agitator are started simultaneously, and the method comprises the following steps:

[0010] The first step, the calcium oxide powder is added into the input end of the first stage screw conveying stirrer through the calcium oxide powder inlet, the first water sprayer connected to the first stirrer water outlet is turned on, and water is sprayed onto the calcium oxide powder in the input end of the first stage screw conveying stirrer; the water and the calcium oxide powder react to generate calcium hydroxide, and the water not participating in the chemical reaction is heated;

[0011] The second step, the first stage mixture of the unreacted calcium oxide powder, the heated water and the generated calcium hydroxide is conveyed to the output end of the first stage screw conveying stirrer along with the rotation of the screw stirring blade in the first stage screw conveying stirrer; in this process, a part of the unreacted calcium oxide powder continues to react with the heated water, continues to release heat, heats the water into steam, and the generated steam is sucked into the high-temperature steam conveying pipeline by the induced draft fan through the high-temperature steam exhaust port;

[0012] The third step, the first stage mixture conveyed to the output end of the first stage screw conveying stirrer enters the input end of the second stage screw conveying stirrer through the second stirrer inlet, the second water sprayer connected to the second stirrer water outlet is started, and water is sprayed onto the first stage mixture; the sprayed water reacts with the calcium oxide powder in the first stage mixture to generate calcium hydroxide and release heat; at the same time, a part of the steam in the high-temperature steam conveying pipeline enters the input end of the second stage screw conveying stirrer through the high-temperature steam circulating conveying branch and the high-temperature steam circulating inlet, and heats the first stage mixture;

[0013] The fourth step, the first stage mixture in the input end of the second stage screw conveying stirrer is conveyed to the output end of the second stage screw conveying stirrer along with the rotation of the screw stirring blade in the second stage screw conveying stirrer; in this process, a part of the unreacted calcium oxide powder reacts with the water sprayed by the second water sprayer and the steam entering through the high-temperature steam circulating inlet to continue to generate calcium hydroxide and release heat, and the steam in the second stage screw conveying stirrer is heated and warmed up;

[0014] The fifth step, the second stage mixture conveyed to the output end of the second stage screw conveying stirrer enters the input end of the third stage screw conveying stirrer through the third stirrer inlet, and the heated and warmed up steam enters the input end of the first stage screw conveying stirrer in turn through the second stirrer tail high-temperature steam outlet, the second stirrer tail high-temperature steam outlet pipe and the second stirrer tail high-temperature steam inlet;

[0015] The second stage mixture transported to the output end of the second stage screw conveyor mixer enters the input end of the third stage screw conveyor mixer through the third stage mixer feeding port, and is transported to the output end of the third stage screw conveyor mixer along with the rotation of the screw stirring blade in the third stage screw conveyor mixer, and is output from the calcium hydroxide discharging port to the calcium hydroxide storage bin, while the cooling air from the hot blast stove exhaust pipe enters the first stage screw conveyor mixer through the cooling air inlet pipe and the cooling air inlet port in sequence to cool the generated calcium hydroxide.

[0016] The third water sprayer connected to the third mixer water spraying port is started to spray water to the second stage mixture entering the input end of the third stage screw conveyor mixer; the third stage screw conveyor mixer output end steam is introduced into the first stage screw conveyor mixer input end through the third mixer tail high temperature steam outlet pipe.

[0017] The present application is based on the structure of the traditional lime digester used in the building material industry, and is based on the chemical heat pump principle that calcium oxide is converted into calcium hydroxide when water is added and heat is released, and aims to generate high temperature steam, and at the same time takes into account the generation of high purity calcium hydroxide, realizes the full excitation of chemical reaction heat and the full extraction and utilization of heat energy. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural schematic diagram of the present application. DETAILED DESCRIPTION

[0019] The present application will be described in detail below in conjunction with the drawings:

[0020] The application discloses a chemical heat pump based on a three-stage calcium oxide-calcium hydroxide digester, which comprises a first-stage screw conveying agitator 1, a second-stage screw conveying agitator 2, a third-stage screw conveying agitator 3 and calcium oxide powder, wherein a calcium oxide powder feeding port 4 is arranged at the input end of the first-stage screw conveying agitator 1, a second-stage agitator feeding port 5 is arranged at the input end of the second-stage screw conveying agitator 2, a third-stage agitator feeding port 6 is arranged at the input end of the third-stage screw conveying agitator 3, a calcium hydroxide discharging port 7 is arranged at the output end of the third-stage screw conveying agitator 3, the three screw conveying agitators are sequentially connected in series to form a closed serpentine material conveying shell, the output port of the first-stage screw conveying agitator 1 is communicated with the second-stage agitator feeding port 5, the output port of the second-stage screw conveying agitator 2 is communicated with the third-stage agitator feeding port 6, and the material entering from the calcium oxide powder feeding port 4 is sequentially rotated and stirred and pushed by the three groups of screw stirring blades and then is output from the calcium hydroxide discharging port 7; a first agitator water spraying port 8 is arranged at the input end of the first-stage screw conveying agitator 1, a second agitator water spraying port 9 is arranged at the input end of the second-stage screw conveying agitator 2, a third agitator water spraying port 10 is arranged at the input end of the third-stage screw conveying agitator 3, a water sprayer is connected to each of the three agitator water spraying ports, the calcium oxide powder enters the first-stage screw conveying agitator 1 through the calcium oxide powder feeding port 4, a high-temperature steam exhaust port 11 is arranged at the output end of the first-stage screw conveying agitator 1, an induced draft fan 12 is connected to the high-temperature steam exhaust port 11, a high-temperature steam conveying pipeline 13 is connected to the output end of the induced draft fan, the high-temperature steam in the first-stage screw conveying agitator 1 is sucked out to the high-temperature steam conveying pipeline 13 by the suction force of the induced draft fan 12, and the heat is fully utilized; a high-temperature steam circulation inlet 15 is arranged at the input end of the second-stage screw conveying agitator 2, a high-temperature steam circulation conveying branch pipe 14 is connected to the high-temperature steam conveying pipeline 13, the other end of the high-temperature steam circulation conveying branch pipe 14 is communicated with the high-temperature steam circulation inlet 15, the high-temperature steam is introduced into the input end of the second-stage screw conveying agitator 2, so that the calcium oxide which has not reacted in the second-stage screw conveying agitator 2 fully reacts, a calcium hydroxide bin is arranged below the calcium hydroxide discharging port 7, and the generated calcium hydroxide powder is collected in the calcium hydroxide bin.

[0021] The second agitator tail high-temperature steam outlet 17 is arranged at the output end of the second-stage screw conveying agitator 2, the third agitator tail high-temperature steam outlet 20 is arranged at the output end of the third-stage screw conveying agitator 3, the second agitator tail high-temperature steam inlet 19 and the third agitator tail high-temperature steam inlet 22 are respectively arranged on the input end of the first-stage screw conveying agitator 1, the second agitator tail high-temperature steam extraction pipe 18 is arranged between the second agitator tail high-temperature steam outlet 17 and the second agitator tail high-temperature steam inlet 19, the third agitator tail high-temperature steam extraction pipe 21 is arranged between the third agitator tail high-temperature steam inlet 22 and the third agitator tail high-temperature steam outlet 20, the second agitator tail high-temperature steam is introduced into the input end of the first-stage screw conveying agitator 1 to heat the water in the input end of the first-stage screw conveying agitator 1 to generate high-temperature steam, the generated high-temperature steam is output from the high-temperature steam exhaust port 11 into the high-temperature steam conveying pipeline 13, and then a part of the high-temperature steam is introduced back to the input end of the second-stage screw conveying agitator 2, and then the high-temperature steam is heated by the chemical reaction heat in the second-stage screw conveying agitator 2, and then the high-temperature steam is introduced into the input end of the first-stage screw conveying agitator 1 through the second agitator tail high-temperature steam extraction pipe 18, so as to realize the full absorption of the chemical reaction heat in the three-stage digester into the high-temperature steam, the chemical reaction heat released by the conversion of calcium oxide into calcium hydroxide is stored in the high-temperature steam, and the high-temperature steam is fully utilized after being introduced out; the cooling air inlet 16 is arranged at the input end of the third-stage screw conveying agitator 3, the cooling air inlet pipe 23 is connected to the cooling air inlet 16, and the other end of the cooling air inlet pipe 23 is communicated with the hot blast furnace exhaust pipe, so as to reduce the temperature of the output calcium hydroxide powder.

[0022] A working method of a chemical heat pump based on a calcium oxide-calcium hydroxide three-stage digester, characterized by the following steps:

[0023] In the first step, the calcium oxide powder is added into the input end of the first-stage screw conveying agitator 1 through the calcium oxide powder inlet 4, the first water sprayer connected to the first agitator water spraying port 8 is opened, water is sprayed onto the calcium oxide powder in the input end of the first-stage screw conveying agitator 1, the water and the calcium oxide powder react to generate calcium hydroxide, and the water not participating in the chemical reaction is heated;

[0024] Second step, the first level mixture of unreacted calcium oxide powder, heated water and generated calcium hydroxide is transported to the output end of the first level screw conveyor mixer 1 with the rotation of the screw stirring blade in the first level screw conveyor mixer 1, in the process, a part of the unreacted calcium oxide powder continues to react with the heated water to release heat, and the water is heated into steam, and the generated steam is sucked into the high-temperature steam conveying pipeline 13 by the induced draft fan through the high-temperature steam exhaust port 11;

[0025] Third step, the first level mixture transported to the output end of the first level screw conveyor mixer 1 enters the input end of the second level screw conveyor mixer 2 through the second mixer inlet 5, and the second water sprayer connected to the second mixer water spraying port 9 is started to spray water on the first level mixture, the sprayed water reacts with the calcium oxide powder in the first level mixture to generate calcium hydroxide and release heat; at the same time, a part of the steam in the high-temperature steam conveying pipeline 13 enters the input end of the second level screw conveyor mixer 2 through the high-temperature steam circulating conveying branch 14 and the high-temperature steam circulating inlet 15 to heat the first level mixture;

[0026] Fourth step, the first level mixture in the input end of the second level screw conveyor mixer 2 is transported to the output end of the second level screw conveyor mixer 2 with the rotation of the screw stirring blade in the second level screw conveyor mixer 2, in the process, a part of the unreacted calcium oxide powder reacts with the water sprayed by the second water sprayer and the steam entering through the high-temperature steam circulating inlet 15 to continue to generate calcium hydroxide and release heat, and the steam in the second level screw conveyor mixer 2 is heated and warmed up;

[0027] Fifth step, the second level mixture transported to the output end of the second level screw conveyor mixer 2 enters the input end of the third level screw conveyor mixer 3 through the third mixer inlet 6, and the warmed up steam enters the input end of the first level screw conveyor mixer 1 in turn through the second mixer tail high-temperature steam outlet 17, the second mixer tail high-temperature steam leading pipe 18 and the second mixer tail high-temperature steam inlet 19;

[0028] Sixth step, the second level mixture transported to the output end of the second level screw conveyor mixer 2 enters the input end of the third level screw conveyor mixer 3 through the third mixer inlet 6, and is transported to the output end of the third level screw conveyor mixer 3 with the rotation of the screw stirring blade in the third level screw conveyor mixer 3, and is output to the calcium hydroxide bin from the calcium hydroxide outlet 7, at the same time, the cooling air from the hot blast stove exhaust pipe enters the first level screw conveyor mixer 1 in turn through the cooling air inlet pipe 23 and the cooling air inlet 16 to cool the generated calcium hydroxide.

[0029] The third water sprayer connected to the third agitator water nozzle 10 is started to spray water to the second mixture entering into the input end of the third screw conveyor agitator 3. The third screw conveyor agitator 3 output end steam is introduced into the first screw conveyor agitator 1 input end through the third agitator tail high temperature steam outlet pipe 21. The above two measures can be used as a supplementary measure for the whole reaction process.

Claims

1. A chemical heat pump based on calcium oxide-calcium hydroxide three-stage digester, comprising a first-stage screw conveying agitator (1), a second-stage screw conveying agitator (2), a third-stage screw conveying agitator (3) and calcium oxide powder, a calcium oxide powder feeding port (4) is arranged at the input end of the first-stage screw conveying agitator (1), a second-stage agitator feeding port (5) is arranged at the input end of the second-stage screw conveying agitator (2), a third-stage agitator feeding port (6) is arranged at the input end of the third-stage screw conveying agitator (3), a calcium hydroxide discharging port (7) is arranged at the output end of the third-stage screw conveying agitator (3), the output port of the first-stage screw conveying agitator (1) and the second-stage agitator feeding port (5) are communicated together, the output port of the second-stage screw conveying agitator (2) and the third-stage agitator feeding port (6) are communicated together; a first agitator water spraying port (8) is arranged at the input end of the first-stage screw conveying agitator (1), a second agitator water spraying port (9) is arranged at the input end of the second-stage screw conveying agitator (2), a third agitator water spraying port (10) is arranged at the input end of the third-stage screw conveying agitator (3), characterized in that, The calcium oxide powder enters into the first stage screw conveying stirrer (1) through the calcium oxide powder feeding port (4), the high temperature steam exhaust port (11) is arranged on the output end of the first stage screw conveying stirrer (1), the induced draft fan (12) is connected on the high temperature steam exhaust port (11), the high temperature steam conveying pipeline (13) is connected on the output end of the induced draft fan; the high temperature steam circulating inlet port (15) is arranged on the input end of the second stage screw conveying stirrer (2), the high temperature steam circulating conveying branch pipe (14) is connected on the high temperature steam conveying pipeline (13), the other end of the high temperature steam circulating conveying branch pipe (14) is communicated with the high temperature steam circulating inlet port (15) together; the calcium hydroxide bin is arranged below the calcium hydroxide discharging port (7).

2. A chemical heat pump based on a calcium oxide-calcium hydroxide based three-stage digester according to claim 1, characterized in that, The second stirrer tail high temperature steam exhaust port (17) is arranged on the output end of the second stage screw conveying stirrer (2), the third stirrer tail high temperature steam exhaust port (20) is arranged on the output end of the third stage screw conveying stirrer (3), the second stirrer tail high temperature steam inlet port (19) and the third stirrer tail high temperature steam inlet port (22) are respectively arranged on the input end of the first stage screw conveying stirrer (1), the second stirrer tail high temperature steam exhaust pipe (18) is arranged between the second stirrer tail high temperature steam exhaust port (17) and the second stirrer tail high temperature steam inlet port (19), the third stirrer tail high temperature steam exhaust pipe (21) is arranged between the third stirrer tail high temperature steam inlet port (22) and the third stirrer tail high temperature steam exhaust port (20); the cooling air inlet port (16) is arranged on the input end of the third stage screw conveying stirrer (3), the cooling air inlet pipe (23) is connected on the cooling air inlet port (16), the other end of the cooling air inlet pipe (23) is communicated with the hot blast stove exhaust pipe together.

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