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

Abstract

The invention discloses a chemical heat pump based on a calcium oxide-calcium hydroxide three-stage digester and a working method, 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 invention 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 digester of calcium oxide-calcium hydroxide and a working method thereof. Background Art

[0002] Thermochemical energy storage uses reversible chemical reactions to convert thermal energy into chemical energy and stores it in the reaction medium. When it is needed, the stored chemical energy is released in the form of reaction heat through reverse thermochemical reactions or combustion. Since the thermochemical energy storage process is through the rupture and recombination of chemical bonds, energy conversion from "thermal energy-chemical energy-thermal energy" is achieved, thermochemical energy storage has the advantages of large energy storage capacity, high operating temperature, low heat loss in the energy storage process, and long-distance transportation. The research on thermochemical energy storage system is still in the laboratory stage, and the energy storage system converted from calcium hydroxide and calcium oxide has been developed by LUZ. The company has determined it as the preferred object for medium-temperature solar thermal storage systems; currently, the building materials industry generally uses a process in which calcium oxide (quicklime) is mixed with water to become calcium hydroxide (slaked lime). The industry generally completes the above process through quicklime digester equipment. The focus of the entire process is on the pursuit of slaked lime products. The high-temperature steam generated in the process is only studied from an environmental perspective, with the research direction of not generating environmental pollution. There is no attention paid to the generation and scientific utilization of high-temperature steam heat energy. 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 has become a new research topic.

[0003] The existing quicklime digester is mainly used to convert calcium oxide into calcium hydroxide after adding water. Calcium oxide at room temperature is digested with water to produce high-temperature hot water above 80°C. This chemical thermal reaction is called a chemical heat pump in the industry. The specific process is as follows: calcium oxide powder enters from the bottom hopper of the elevator and is lifted to the top. Then, it enters the calcium oxide powder silo from the top. The silo feeds the calcium oxide powder into the first-stage screw conveyor agitator of the three-stage digester through the feeder. The water pump starts to spray water to the first-stage screw conveyor agitator (spray water with variable frequency according to the amount of material). Calcium oxide generates calcium hydroxide when it meets water, releases heat, generates hot water, and passes through one side. The calcium oxide that has not undergone chemical reaction is reacted into calcium hydroxide powder. The calcium hydroxide powder is discharged from the bottom of the third digestion stage and enters the calcium hydroxide receiving hopper. The generated hot steam is discharged into the air from the exhaust port of the digester. In the above whole process, the purity and water content of the generated calcium hydroxide are mainly controlled, and the generated hot air is only discharged as a by-product, resulting in a waste of this part of heat energy. How to efficiently utilize this part of heat energy and how to use this part of heat energy to improve the efficiency of producing calcium hydroxide in the quicklime digester has become a new topic to be studied. Summary of the invention

[0004] The present invention provides a chemical heat pump and a working method based on a calcium oxide-calcium hydroxide three-stage digester, which solves the technical problems of how to effectively and fully utilize the thermal energy of high-temperature steam produced in the process of producing quicklime and mature lime, and how to utilize this part of the thermal energy to improve the efficiency of producing calcium hydroxide in the quicklime digester.

[0005] The present invention solves the above technical problems through the following technical solutions: The overall concept of the present invention is as follows: based on the structure of a three-stage quicklime digester, it is transformed into a chemical heat pump that can generate high-temperature steam. In the process of converting calcium oxide into calcium hydroxide, the heat energy generated in the chemical reaction process is fully stimulated and extracted and utilized in the form of high-temperature steam, and part of the extracted high-temperature steam is creatively circulated back to the digester, thereby playing a dual role of stimulating high-temperature steam and improving the production efficiency of calcium hydroxide.

[0006] A chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide comprises a first-stage screw conveying agitator, a second-stage screw conveying agitator, a third-stage screw conveying agitator and calcium oxide powder, wherein a calcium oxide 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, a calcium 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 connected to the inlet of the second-stage agitator, and the output port of the second-stage screw conveying agitator is connected to the inlet of the third-stage agitator; a first Agitator water spray port, a second agitator water spray port is provided at the input end of the second-stage screw conveying agitator, a third agitator water spray port is provided at the input end of the third-stage screw conveying agitator, calcium oxide powder enters the first-stage screw conveying agitator through the calcium oxide powder inlet, a high-temperature steam exhaust port is provided 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 delivery pipeline is connected to the output end of the induced draft fan; a high-temperature steam circulation inlet is provided at the input end of the second-stage screw conveying agitator, a high-temperature steam circulation delivery branch pipe is connected to the high-temperature steam delivery pipeline, and the other end of the high-temperature steam circulation delivery branch pipe is connected to the high-temperature steam circulation inlet; a calcium hydroxide silo is provided below the calcium hydroxide discharge port.

[0007] A high-temperature steam outlet at the tail of the second agitator is provided at the output end of the second-stage spiral conveying agitator, a high-temperature steam outlet at the tail of the third agitator is provided at the output end of the third-stage spiral conveying agitator, a high-temperature steam inlet at the tail of the second agitator and a high-temperature steam inlet at the tail of the third agitator are provided at the input end of the first-stage spiral conveying agitator, respectively, a high-temperature steam outlet at the tail of the second agitator and a high-temperature steam inlet at the tail of the second agitator are provided, a high-temperature steam outlet pipe at the tail of the second agitator is provided between the high-temperature steam outlet at the tail of the second agitator and the high-temperature steam inlet at the tail of the second agitator, and a high-temperature steam outlet pipe at the tail of the third agitator is provided between the high-temperature steam inlet at the tail of the third agitator and the high-temperature steam outlet at the tail of the third agitator; a cooling air inlet is provided at the input end of the third-stage spiral 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 connected to the exhaust pipe of the hot air furnace.

[0008] A working method of a chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide, wherein a first-stage screw conveying agitator, a second-stage screw conveying agitator and a third-stage screw conveying agitator are started simultaneously, characterized by the following steps: The first step is to add calcium oxide powder to the input end of the first-stage screw conveyor stirrer through the calcium oxide powder feed port, open the first water sprayer connected to the water spray port of the first stirrer, spray water onto the calcium oxide powder entering the input end of the first-stage screw conveyor stirrer, and chemically react the water and the calcium oxide powder to generate calcium hydroxide, and heat the water that does not participate in the chemical reaction; In the second step, the first-stage mixture of unreacted calcium oxide powder, heated water and generated calcium hydroxide is transported to the output end of the first-stage screw conveying stirrer as the spiral stirring blades in the first-stage screw conveying stirrer rotate. During this process, a portion of the unreacted calcium oxide powder continues to chemically react with the heated water, continues to release heat, and heats the water into steam. The generated steam passes through the high-temperature steam exhaust port and is sucked into the high-temperature steam conveying pipeline by the induced draft fan; Step 3: The first-stage mixture transported to the output end of the first-stage screw conveying agitator enters the input end of the second-stage screw conveying agitator through the feeding port of the second-stage agitator, and the second water sprayer connected to the water spray port of the second agitator is started to spray water 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 agitator through the high-temperature steam circulation conveying branch pipe and the high-temperature steam circulation steam inlet to heat the first-stage mixture; Step 4: The first-stage mixture in the input end of the second-stage screw conveying stirrer is transported to the output end of the second-stage screw conveying stirrer as the spiral stirring blades in the second-stage screw conveying stirrer rotate. During this process, a portion of the unreacted calcium oxide powder reacts chemically with the water sprayed from the second water sprayer and the steam entering through the high-temperature steam circulation steam inlet, and continues to generate calcium hydroxide, and continues to release heat to heat the steam in the second-stage screw conveying stirrer. Step 5: The second-stage mixture transported to the output end of the second-stage screw conveying agitator enters the input end of the third-stage screw conveying agitator through the third-stage agitator inlet, and the heated steam enters the input end of the first-stage screw conveying agitator through the high-temperature steam outlet at the tail of the second agitator, the high-temperature steam outlet pipe at the tail of the second agitator, and the high-temperature steam inlet at the tail of the second agitator in turn; Step 6. The second-stage mixture conveyed to the output end of the second-stage spiral conveying agitator enters the input end of the third-stage spiral conveying agitator through the third-stage agitator inlet, and is conveyed to the output end of the third-stage spiral conveying agitator as the spiral stirring blades in the third-stage spiral conveying agitator rotate, and is output from the calcium hydroxide outlet to the calcium hydroxide silo. At the same time, the cooling air from the hot blast furnace exhaust duct enters the first-stage spiral conveying agitator through the cooling air inlet pipe and the cooling air inlet in turn to cool the generated calcium hydroxide.

[0009] Start the third water sprinkler connected to the water spray port of the third agitator to spray water to the second-stage mixture entering the input end of the third-stage screw conveying agitator; connect the high-temperature steam outlet pipe at the tail of the third agitator to introduce the steam at the output end of the third-stage screw conveying agitator into the input end of the first-stage screw conveying agitator.

[0010] The present invention is based on the structure of the quicklime digester used in the traditional building materials industry, and is based on the chemical heat pump principle that calcium oxide is converted into calcium hydroxide when it meets water and releases heat. It aims to generate high-temperature steam and simultaneously takes into account the generation of high-purity calcium hydroxide, thereby achieving full stimulation of the heat energy of the chemical reaction and full extraction and utilization of the exothermic energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0012] The present invention is described in detail below in conjunction with the accompanying drawings: A chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide 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 inlet 4 is arranged at the input end of the first-stage screw conveying agitator 1, a second-stage agitator inlet 5 is arranged at the input end of the second-stage screw conveying agitator 2, a third-stage agitator inlet 6 is arranged at the input end of the third-stage screw conveying agitator 3, and a calcium hydroxide outlet 7 is arranged at the output end of the third-stage screw conveying agitator 3. The three screw conveying agitators are connected end to end in sequence. The first stage screw conveying agitator 1 is connected to form a closed serpentine material conveying shell, the output port of the first stage screw conveying agitator 1 is connected to the second stage agitator inlet 5, the output port of the second stage screw conveying agitator 2 is connected to the third stage agitator inlet 6, the material entering from the calcium oxide powder inlet 4 is sequentially stirred and pushed by the three groups of spiral stirring blades, and then output from the calcium hydroxide outlet 7; a first agitator water spray port 8 is provided at the input end of the first stage screw conveying agitator 1, a second agitator water spray port 9 is provided at the input end of the second stage screw conveying agitator 2, and a third stage screw conveying agitator 2 is provided with a third agitator water spray port 10; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 11; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 12; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 13; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 14; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 15; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 16; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 17; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 18; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 19; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 10; a third stage screw conveying agitator 2 is provided with a third agitator water spray port 11; a third stage screw conveying agitator 2 is provided with a third a The input end of the agitator 3 is provided with a third agitator water spray port 10, and each of the three agitator water spray ports is connected to a water sprayer. The calcium oxide powder enters the first-stage screw conveying agitator 1 through the calcium oxide powder feed port 4. A high-temperature steam exhaust port 11 is provided 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 delivery 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 into the high-temperature steam delivery pipeline 13 by the suction force of the induced draft fan 12, so that this part of the heat is fully utilized. A high-temperature steam circulation inlet 15 is provided at the input end of the second-stage screw conveying agitator 2, and a high-temperature steam circulation delivery branch pipe 14 is connected to the high-temperature steam delivery pipeline 13. The other end of the high-temperature steam circulation delivery branch pipe 14 is connected to the high-temperature steam circulation inlet 15, and this part of the high-temperature steam is introduced into the input end of the second-stage screw conveying agitator 2 to achieve a full chemical reaction of the unreacted calcium oxide in the second-stage screw conveying agitator 2; a calcium hydroxide silo is provided below the calcium hydroxide discharge port 7, and the generated calcium hydroxide powder is collected in the calcium hydroxide silo.

[0013] A second agitator tail high-temperature steam outlet 17 is provided at the output end of the second-stage screw conveying agitator 2, a third agitator tail high-temperature steam outlet 20 is provided at the output end of the third-stage screw conveying agitator 3, a second agitator tail high-temperature steam inlet 19 and a third agitator tail high-temperature steam inlet 22 are provided at the input end of the first-stage screw conveying agitator 1, respectively, a second agitator tail high-temperature steam outlet 18 is provided between the second agitator tail high-temperature steam outlet 17 and the second agitator tail high-temperature steam inlet 19, a third agitator tail high-temperature steam outlet 21 is provided 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, and the water in the input end of the first-stage screw conveying agitator 1 is heated. Heat is generated to generate high-temperature steam. After the generated high-temperature steam is output from the high-temperature steam exhaust port 11 and enters the high-temperature steam conveying pipeline 13, a part of it is led back to the input end of the second-stage spiral conveying agitator 2, and then heated by the heat of the chemical reaction in the second-stage spiral conveying agitator 2, and then introduced into the input end of the first-stage spiral conveying agitator 1 through the high-temperature steam lead-out pipe 18 at the tail of the second agitator, and the cycle is repeated, so that the heat of the chemical reaction in the three-stage digester is fully absorbed into the high-temperature steam, and the heat energy released by the chemical reaction of converting calcium oxide into calcium hydroxide is stored in the high-temperature steam and fully utilized after being led out; a cooling air inlet 16 is provided at the input end of the third-stage spiral conveying agitator 3, and a 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 connected to the exhaust pipe of the hot blast furnace to reduce the temperature of the output calcium hydroxide powder.

[0014] A working method of a chemical heat pump of a three-stage digester based on calcium oxide-calcium hydroxide, wherein a first-stage screw conveying agitator 1, a second-stage screw conveying agitator 2 and a third-stage screw conveying agitator 3 are started simultaneously, characterized by the following steps: The first step is to add calcium oxide powder to the input end of the first-stage screw conveyor stirrer 1 through the calcium oxide powder feed port 4, open the first water sprayer connected to the first stirrer water spray port 8, spray water onto the calcium oxide powder entering the input end of the first-stage screw conveyor stirrer 1, and chemically react the water and the calcium oxide powder to generate calcium hydroxide, and heat the water that does not participate in the chemical reaction; Step 2: The first-stage mixture of unreacted calcium oxide powder, heated water and generated calcium hydroxide is transported to the output end of the first-stage screw conveying stirrer 1 as the spiral stirring blades in the first-stage screw conveying stirrer 1 rotate. During this process, a portion of the unreacted calcium oxide powder continues to chemically react with the heated water, continues to release heat, and heats the water into steam. The generated steam passes through the high-temperature steam exhaust port 11 and is sucked into the high-temperature steam conveying pipeline 13 by the induced draft fan; Step 3: The first-stage mixture transported to the output end of the first-stage screw conveying stirrer 1 enters the input end of the second-stage screw conveying stirrer 2 through the second-stage stirrer feed port 5, and the second water sprayer connected to the second stirrer water spray port 9 is started to spray water 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 portion of the steam in the high-temperature steam delivery pipeline 13 enters the input end of the second-stage screw conveying stirrer 2 through the high-temperature steam circulation delivery branch pipe 14 and the high-temperature steam circulation steam inlet 15 to heat the first-stage mixture. Step 4: The first-stage mixture in the input end of the second-stage screw conveying stirrer 2 is transported to the output end of the second-stage screw conveying stirrer 2 as the spiral stirring blades in the second-stage screw conveying stirrer 2 rotate. During this process, a portion of the unreacted calcium oxide powder reacts chemically with the water sprayed from the second water sprayer and the steam entering through the high-temperature steam circulation steam inlet 15 to continue to generate calcium hydroxide and continue to release heat to heat the steam in the second-stage screw conveying stirrer 2. Step 5: The second-stage mixture transported to the output end of the second-stage screw conveying agitator 2 enters the input end of the third-stage screw conveying agitator 3 through the third-stage agitator inlet 6, and the heated steam enters the input end of the first-stage screw conveying agitator 1 through the high-temperature steam outlet 17 at the tail of the second agitator, the high-temperature steam outlet pipe 18 at the tail of the second agitator, and the high-temperature steam inlet 19 at the tail of the second agitator in turn; Step 6. The second-stage mixture conveyed to the output end of the second-stage spiral conveying agitator 2 enters the input end of the third-stage spiral conveying agitator 3 through the third-stage agitator inlet 6, and is conveyed to the output end of the third-stage spiral conveying agitator 3 as the spiral stirring blades in the third-stage spiral conveying agitator 3 rotate, and is output from the calcium hydroxide outlet 7 to the calcium hydroxide silo. At the same time, the cooling air from the hot blast furnace exhaust duct enters the first-stage spiral conveying agitator 1 through the cooling air inlet pipe 23 and the cooling air inlet 16 in turn to cool the generated calcium hydroxide.

[0015] Start the third water sprayer connected to the third agitator water spray port 10 to spray water to the second-stage mixture entering the input end of the third-stage screw conveying agitator 3; connect the high-temperature steam outlet pipe 21 at the tail of the third agitator to introduce the steam at the output end of the third-stage screw conveying agitator 3 into the input end of the first-stage screw conveying agitator 1; the above two measures can be used as a supplementary measure for the entire reaction process.

Claims

1. A chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide, 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, wherein a calcium oxide powder inlet (4) is provided at the input end of the first-stage screw conveying agitator (1), a second-stage agitator inlet (5) is provided at the input end of the second-stage screw conveying agitator (2), a third-stage agitator inlet (6) is provided at the input end of the third-stage screw conveying agitator (3), and a calcium oxide powder inlet (7) is provided at the output end of the third-stage screw conveying agitator (3). A calcium hydroxide discharge port (7) is provided at the end, the output port of the first-stage screw conveying agitator (1) is connected to the feed port (5) of the second-stage screw conveying agitator (2), and the output port of the second-stage screw conveying agitator (2) is connected to the feed port (6) of the third-stage agitator; a first agitator water spray port (8) is provided at the input end of the first-stage screw conveying agitator (1), a second agitator water spray port (9) is provided at the input end of the second-stage screw conveying agitator (2), and a third agitator water spray port (10) is provided at the input end of the third-stage screw conveying agitator (3), characterized in that: Calcium oxide powder enters the first-stage screw conveying agitator (1) through a calcium oxide powder feed port (4); a high-temperature steam exhaust port (11) is provided 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); and a high-temperature steam delivery pipeline (13) is connected to the output end of the induced draft fan; a high-temperature steam circulation inlet (15) is provided at the input end of the second-stage screw conveying agitator (2); a high-temperature steam circulation delivery branch pipe (14) is connected to the high-temperature steam delivery pipeline (13); and the other end of the high-temperature steam circulation delivery branch pipe (14) is connected to the high-temperature steam circulation inlet (15); and a calcium hydroxide silo is provided below the calcium hydroxide discharge port (7).

2. A chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide according to claim 1, characterized in that: A second agitator tail high-temperature steam outlet (17) is provided at the output end of the second-stage screw conveying agitator (2), a third agitator tail high-temperature steam outlet (20) is provided at the output end of the third-stage screw conveying agitator (3), a second agitator tail high-temperature steam inlet (19) and a third agitator tail high-temperature steam inlet (22) are provided at the input end of the first-stage screw conveying agitator (1), and a second agitator tail high-temperature steam inlet (19) and a third agitator tail high-temperature steam inlet (22) are provided at the second agitator tail high-temperature steam outlet (17) and the second agitator tail high-temperature steam inlet (20). A second stirrer tail high-temperature steam outlet pipe (18) is provided between the inlet (19), and a third stirrer tail high-temperature steam outlet pipe (21) is provided between the third stirrer tail high-temperature steam inlet (22) and the third stirrer tail high-temperature steam outlet (20); a cooling air inlet (16) is provided at the input end of the third-stage spiral conveying stirrer (3), a 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 connected to the hot air furnace exhaust pipe.

3. The working method of a chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide according to claim 2, wherein the first-stage screw conveying agitator (1), the second-stage screw conveying agitator (2) and the third-stage screw conveying agitator (3) are started simultaneously, characterized in that the following steps are performed: The first step is to add calcium oxide powder to the input end of the first-stage screw conveyor agitator (1) through the calcium oxide powder feed port (4), open the first water sprayer connected to the first agitator water spray port (8), spray water onto the calcium oxide powder entering the input end of the first-stage screw conveyor agitator (1), and chemically react the water and the calcium oxide powder to generate calcium hydroxide, and heat the water that has not participated in the chemical reaction; In the second step, the first-stage mixture of unreacted calcium oxide powder, heated water and generated calcium hydroxide is transported to the output end of the first-stage screw conveying stirrer (1) as the spiral stirring blades in the first-stage screw conveying stirrer (1) rotate. During this process, a portion of the unreacted calcium oxide powder continues to chemically react with the heated water, continues to release heat, and heats the water into steam. The generated steam passes through the high-temperature steam exhaust port (11) and is sucked into the high-temperature steam conveying pipeline (13) by the induced draft fan; Step 3: The first-stage mixture transported to the output end of the first-stage screw conveying stirrer (1) enters the input end of the second-stage screw conveying stirrer (2) through the second-stage stirrer feed port (5), and the second water sprayer connected to the second stirrer water spray port (9) is started to spray water 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 portion of the steam in the high-temperature steam transport pipeline (13) enters the input end of the second-stage screw conveying stirrer (2) through the high-temperature steam circulation transport branch pipe (14) and the high-temperature steam circulation steam inlet (15), thereby heating the first-stage mixture. Step 4: The first-stage mixture in the input end of the second-stage screw conveying stirrer (2) is transported to the output end of the second-stage screw conveying stirrer (2) as the spiral stirring blades in the second-stage screw conveying stirrer (2) rotate. During this process, a portion of the unreacted calcium oxide powder reacts chemically with the water sprayed from the second water sprayer and the steam entering through the high-temperature steam circulation steam inlet (15), and calcium hydroxide is continuously generated, and heat is continuously released, thereby heating the steam in the second-stage screw conveying stirrer (2); Step 5: The second-stage mixture transported to the output end of the second-stage screw conveying agitator (2) enters the input end of the third-stage screw conveying agitator (3) through the third-stage agitator feed port (6), and the heated steam enters the input end of the first-stage screw conveying agitator (1) through the high-temperature steam outlet (17) at the rear of the second agitator, the high-temperature steam outlet pipe (18) at the rear of the second agitator, and the high-temperature steam inlet (19) at the rear of the second agitator in sequence; Step 6: The second-stage mixture transported to the output end of the second-stage screw conveying stirrer (2) enters the input end of the third-stage screw conveying stirrer (3) through the third-stage stirrer inlet (6), and is transported to the output end of the third-stage screw conveying stirrer (3) as the spiral stirring blades in the third-stage screw conveying stirrer (3) rotate, and is output from the calcium hydroxide outlet (7) to the calcium hydroxide silo. At the same time, the cooling air from the hot air furnace exhaust pipe enters the first-stage screw conveying stirrer (1) through the cooling air inlet pipe (23) and the cooling air inlet (16) in sequence to cool the generated calcium hydroxide.

4. The working method of a chemical heat pump based on a three-stage digester of calcium oxide-calcium hydroxide according to claim 3, characterized in that: The third water sprayer connected to the water spray port (10) of the third agitator is started to spray water onto the second-stage mixture entering the input end of the third-stage screw conveying agitator (3); and the high-temperature steam outlet pipe (21) at the tail of the third agitator is connected to introduce the steam at the output end of the third-stage screw conveying agitator (3) into the input end of the first-stage screw conveying agitator (1).

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