Heat pump energy saving device in renewable desulfurization process

Abstract

The utility model discloses a kind of heat pump energy-saving devices in renewable desulfurization process, it is related to chemical industry field, especially to separation field, purpose is to reduce desorption process live steam consumption and industrial water consumption, to reduce the energy consumption of desorption process.The technical scheme adopted by the utility model is: heat pump energy-saving device in renewable desulfurization process, including regenerator, heat recovery tower and heat pump, the desorption steam outlet of the top of regenerator is connected with the desorption steam inlet of the lower section of heat recovery tower, one condensate outlet of heat recovery tower is connected with regenerator by reflux pump, another condensate outlet is connected with heat recovery tower by second circulating pump, the evaporation end of heat pump, third circulation pipeline for heat medium circulation is formed between the condensation end of heat pump and first reboiler, and the top of heat recovery tower is equipped with incondensable gas outlet.The utility model reduces live steam consumption and industrial water consumption, and is used to adopt water vapor desorption process to SO2-rich rich amine liquid.

Description

Technical Field

[0001] This utility model relates to the chemical industry, and more particularly to the field of separation, specifically a heat pump energy-saving device in a renewable desulfurization process. Background Technology

[0002] SO2 in flue gas is absorbed using aqueous monoamines or diamines as absorbents in a regenerable desulfurization process in an absorption tower. The absorbent absorbs SO2 from the flue gas, generating an amine-rich liquid containing SO2-rich amine SO2 salts. Under the action of stripping steam in a regeneration tower (also called a desorption tower or stripping tower), the amine SO2 salts decompose into gaseous SO2 and free amines containing a small amount of SO2, thus yielding a lean amine liquid. The lean amine liquid is returned to the absorption tower for recycling, while the gaseous SO2 exits from the top of the regeneration tower. Because the gaseous SO2 contains water vapor, it is called desorption steam.

[0003] The bottom of the regeneration tower is supplied with steam by the reboiler. Most of this steam leaves with the desorption steam at the top, resulting in extremely high energy consumption, very low thermodynamic efficiency, and significant energy waste during the desorption process. The desorption steam leaving the top of the regeneration tower typically contains ≤10% SO2, with the remainder being water vapor. The temperature of this desorption steam is generally 90℃~118℃, possessing low-temperature waste heat. Since the temperature of the desorption steam leaving the top of the regeneration tower is lower than that at the bottom, it cannot be directly used as a heat source for the reboiler. It is typically cooled directly with industrial water, resulting in substantial energy waste and the consumption of large quantities of industrial water. Utility Model Content

[0004] This invention provides a heat pump energy-saving device for a regenerative desulfurization process, which aims to reduce the consumption of live steam and industrial water during the desorption process, thereby reducing the energy consumption of the desorption process.

[0005] The technical solution adopted in this utility model is: a heat pump energy-saving device in a regenerative desulfurization process, including a regeneration tower, a heat recovery tower and a heat pump. The regeneration tower is provided with a rich amine liquid inlet, a lean amine liquid outlet, a lean amine liquid circulation outlet and a lean amine liquid circulation inlet. The lean amine liquid circulation outlet and the lean amine liquid circulation inlet are connected through a first circulation pipe. The first circulation pipe is provided with a first circulation pump and a first reboiler in sequence along the flow direction of the lean amine liquid. The top of the regeneration tower is provided with a desorption steam outlet, which is connected to the desorption steam inlet of the lower section of the heat recovery tower.

[0006] The lower section of the heat recovery tower is equipped with packing or trays and a condensate spray pipe. It has two condensate outlets: one connected to the inlet of a reflux pump, whose outlet is connected to the condensate inlet of the regeneration tower; the other connected to the inlet of a second circulation pump, whose outlet is connected to the inlet of the heat pump's evaporator end, whose outlet is connected to the condensate spray pipe in the lower section of the heat recovery tower. The heat pump's condensing end has a heat medium inlet and outlet, and the first reboiler has a heat medium inlet and outlet. A third circulation pipe is formed between the heat pump's condensing end and the first reboiler, and this third circulation pipe is connected in series with a third circulation pump. The upper section of the heat recovery tower has a condensate circulation outlet and a condensate circulation inlet, which are connected by a fourth circulation pipe. This fourth circulation pipe, along the condensate flow direction, has a fourth circulation pump and a condenser for cooling the condensate. The top of the heat recovery tower has a non-condensable gas outlet.

[0007] In order to supplement a small amount of heat to this heat pump energy-saving device during startup and operation, the heat pump energy-saving device in the regenerative desulfurization process further includes a second reboiler. The second reboiler is equipped with a steam inlet and a condensate outlet, and a heat replenishment circulation pipeline is formed between the second reboiler and the regeneration tower.

[0008] In order to make full use of the low-temperature enthalpy of the lean amine liquid discharged from the lean amine liquid outlet of the regeneration tower, the heat pump energy-saving device in the regenerative desulfurization process further includes a lean-rich amine liquid heat exchanger. The rich amine liquid inlet of the regeneration tower is connected to a rich amine liquid inlet pipe, and the lean amine liquid outlet of the regeneration tower is connected to a lean amine liquid outlet pipe. Both the rich amine liquid inlet pipe and the lean amine liquid outlet pipe are connected to the lean-rich amine liquid heat exchanger. The lean amine liquid outlet pipe between the lean-rich amine liquid heat exchanger and the lean amine liquid outlet is also equipped with a discharge pump.

[0009] To facilitate stable circulation and heat transfer of the heat medium within the third circulation pipeline, specifically: the third circulation pipeline is also equipped with an intermediate tank. The third circulation pipeline is as follows: heat medium inlet of the first reboiler → heat medium outlet of the first reboiler → intermediate tank → third circulation pump → heat medium inlet of the heat pump condenser → heat medium outlet of the heat pump condenser → heat medium inlet of the first reboiler.

[0010] To facilitate the cooling of the condensate in the fourth circulation pipe by the condenser, specifically: the condenser is equipped with a cooling water inlet and a cooling water outlet.

[0011] Specifically: The heat pump is a high-temperature water source heat pump.

[0012] The beneficial effects of this invention are as follows: The amine-rich liquid is stripped by steam in the regeneration tower to form desorption steam containing gaseous SO2. This desorption steam rises and leaves the regeneration tower, entering the lower section of the heat recovery tower. The lower section of the heat recovery tower sprays condensate through a condensate spray pipe to cool the liquid. High-concentration gaseous SO2 is discharged from the non-condensable gas outlet at the top of the heat recovery tower and sent outside the boundary area. The desorption steam entering the heat recovery tower acts as a low-temperature heat source, exchanging heat with the condensate circulating in the lower section of the heat recovery tower. The temperature of the condensate rises, and the condensate is then further heated by a heat pump, converting it into a high-temperature heat source for use in the first reboiler. This achieves the goal of reducing live steam consumption and industrial water consumption, reducing desulfurization energy consumption, and lowering production costs.

[0013] The desorbed steam leaving the regeneration tower is mainly composed of water vapor containing SO2. This SO2-containing water vapor has a relatively high low-temperature enthalpy, which is recovered by the condensate in the heat recovery tower. Inside the heat recovery tower, the desorbed steam and condensate undergo mass and heat transfer through direct vapor-liquid contact, resulting in a decrease in the temperature of the desorbed steam and an increase in the temperature of the condensate. The heat pump transfers the enthalpy of the condensate to its working fluid, raising its temperature, and then delivers it to the condenser end of the heat pump. The heat medium at the condenser end also increases in temperature and provides heat to the first reboiler through the third circulation pipe. The first reboiler transfers heat to the lean amine liquid in the regeneration tower, where it undergoes secondary vaporization, converting into stripping steam for the desorption process. This stripping steam replaces the live steam from the outside, achieving energy savings and reducing industrial water consumption. The condensate from the lower section of the heat recovery tower returns to the heat recovery tower after passing through the evaporation end of the heat pump, forming a cycle and achieving energy savings. The heat recovery tower also serves to store condensate, facilitating the regulation of the amount of condensate fed into the regeneration tower via a reflux pump. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of one embodiment of the present invention.

[0015] Figure reference numerals: Regeneration tower 1, Rich amine liquid inlet 1-1, Lean amine liquid outlet 1-2, Lean amine liquid circulation outlet 1-3, Lean amine liquid circulation inlet 1-4, Desorption steam outlet 1-5, Condensate inlet 1-6, Heat recovery tower 2, Desorption steam inlet 2-1, Condensate outlet 2-2, Condensate spray pipe 2-3, Condensate circulation outlet 2-4, Condensate circulation inlet 2-5, Non-condensable gas outlet 2-6, Heat pump 3, Evaporation end 3-1, Condensation end 3-2, First circulation pipe 4, First circulation pump 4-1, First reboiler 5, Reflux pump 6, Second circulation pump 7, Third circulation pipe 8, Third circulation pump 8-1, Intermediate tank 8-2, Fourth circulation pipe 9, Fourth circulation pump 9-1, Condenser 10, Second reboiler 11, Steam inlet 11-1, Condensate outlet 11-2, Reheat circulation pipe 12, Lean-rich amine liquid heat exchanger 13, Drain pump 14. Figure 1 The arrows on the pipeline indicate the direction of flow of the medium within the pipeline. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] The heat pump energy-saving device in the regenerative desulfurization process of this utility model recovers the waste heat of the desorption steam discharged from the regeneration tower 1, and converts the low-temperature waste heat of the desorption steam into a high-temperature heat source through the heat pump 3, and then sends it to the first reboiler 5 for reuse, thereby reducing the consumption of live steam and industrial water in the desorption process, reducing desulfurization energy consumption, and reducing production costs.

[0018] like Figure 1 As shown, the heat pump energy-saving device in the regenerative desulfurization process includes a regeneration tower 1, a heat recovery tower 2, and a heat pump 3. The regeneration tower 1 is used for steam stripping of the rich amine solution. The regeneration tower 1 has a rich amine solution inlet 1-1, a lean amine solution outlet 1-2, a lean amine solution circulation outlet 1-3, and a lean amine solution circulation inlet 1-4. The rich amine solution inlet 1-1 is the channel through which rich amine solution from the outside enters the regeneration tower 1, and the lean amine solution outlet 1-2 is the channel through which the lean amine solution obtained from steam stripping leaves the regeneration tower 1. The lean amine solution circulation outlet 1-3 and the lean amine solution circulation inlet 1-4 are connected by a first circulation pipe 4. The first circulation pipe 4 is sequentially equipped with a first circulation pump 4-1 and a first reboiler 5 along the flow direction of the lean amine solution. The lean amine solution circulates along the first circulation pipe 4 and the regeneration tower 1. The first circulation pump 4-1 provides power for the circulation of the lean amine solution, and the first reboiler 5 heats the lean amine solution, causing it to vaporize and convert into stripping steam for the desorption process. The top of the regeneration tower 1 is provided with a desorption steam outlet 1-5, which is connected to the desorption steam inlet 2-1 of the lower section of the heat recovery tower 2.

[0019] The heat recovery tower 2 is vertically divided into an upper section and a lower section. The desorption steam in the regeneration tower 1 leaves the regeneration tower 1 through the desorption steam outlet 1-5 and enters the lower section of the heat recovery tower 2 via a pipeline. The lower section of the heat recovery tower 2 is equipped with packing or trays and a condensate spray pipe 2-3. The sprayed condensate comes into countercurrent contact with the desorption steam, undergoing mass and heat transfer. Water vapor in the desorption steam condenses, lowering its temperature; simultaneously, the sprayed condensate absorbs heat, raising its temperature. The lower section of the heat recovery tower 2 has two condensate outlets 2-2. One condensate outlet 2-2 is connected to the inlet of the reflux pump 6, and the outlet of the reflux pump 6 is connected to the condensate inlet 1-6 of the regeneration tower 1. The heat recovery tower 2 serves to store condensate, facilitating the regulation of the amount of condensate fed into the regeneration tower 1 via the reflux pump 6. Another condensate outlet 2-2 in the lower section of heat recovery tower 2 is connected to the inlet of the second circulation pump 7. The outlet of the second circulation pump 7 is connected to the inlet of the evaporation end 3-1 of heat pump 3. The outlet of the evaporation end 3-1 is connected to the condensate spray pipe 2-3 in the lower section of heat recovery tower 2, thereby forming a condensate circulation pipeline and realizing the utilization of condensate heat.

[0020] Heat pump 3 transfers the enthalpy of the condensate in heat recovery tower 2 to the working fluid of heat pump 3, raising the temperature of the working fluid, and then provides heat to the first reboiler 5 via the third circulation pipe 8. Specifically, heat pump 3 is a high-temperature water source heat pump. The condensing end 3-2 of heat pump 3 is provided with a heat medium inlet and a heat medium outlet, which are the channels for the heat medium to enter and exit the condensing end 3-2 of heat pump 3. The first reboiler 5 is provided with a heat medium inlet and a heat medium outlet. A third circulation pipe 8 is formed between the condensing end of heat pump 3 and the first reboiler 5, and the heat medium circulates in the third circulation pipe 8 to achieve heat transfer. After the evaporating end 3-1 of heat pump 3 absorbs heat from the condensate in heat recovery tower 2, the working fluid of heat pump 3 vaporizes. The compressor of heat pump 3 compresses the working fluid, raising its temperature. The working fluid is sent to the condensing end 3-2 of heat pump 3, raising the temperature of the heat medium at the condensing end 3-2, and then sent to the first reboiler 5 through the third circulation pipe 8. The temperature of the heat medium exiting the first reboiler 5 decreases, and it returns to the condenser end 3-2 of the heat pump 3 to absorb heat again, forming a cycle. To ensure continuous circulation of the heat medium along the third circulation pipe 8, a third circulation pump 8-1 is also installed in the third circulation pipe 8, connected in series. The third circulation pump 8-1 provides power for the circulation of the heat medium within the third circulation pipe 8. To facilitate stable circulation and heat transfer of the heat medium within the third circulation pipe 8, an intermediate tank 8-2 is also connected in series in the third circulation pipe 8, which acts as a buffer for the heat medium. With the intermediate tank 8-2 present, the inlet of the third circulation pump 8-1 is connected to the intermediate tank 8-2. In this case, the third circulation pipe 8 is: heat medium inlet of the first reboiler 5 → heat medium outlet of the first reboiler 5 → intermediate tank 8-2 → third circulation pump 8-1 → heat medium inlet of the condenser end 3-2 of the heat pump 3 → heat medium outlet of the condenser end 3-2 of the heat pump 3 → heat medium inlet of the first reboiler 5.

[0021] The upper section of the heat recovery tower 2 is equipped with a condensate circulation outlet 2-4 and a condensate circulation inlet 2-5, which are connected by a fourth circulation pipe 9. The condensate circulation outlet 2-4 is located at the lower part of the upper section of the heat recovery tower 2 and is connected to a condensate spray pipe inside the upper section of the heat recovery tower 2. The condensate circulation inlet 2-5 is located at the upper part of the upper section of the heat recovery tower 2. Along the condensate flow direction, the fourth circulation pipe 9 is equipped with a fourth circulation pump 9-1 and a condenser 10. The fourth circulation pump 9-1 provides power for the circulation of condensate in the fourth circulation pipe 9 and the heat recovery tower 2. The condenser 10 is used to cool the condensate in the fourth circulation pipe 9. To facilitate cooling of the condensate by the condenser 10, the condenser 10 is equipped with a cooling water inlet and a cooling water outlet; that is, the condenser 10 is water-cooled, and the cooling water inlet and outlet are for connecting to external cooling water.

[0022] The top of the heat recovery tower 2 is equipped with a non-condensable gas outlet 2-6. The desorbed steam leaving the regeneration tower 1 enters the heat recovery tower 2. The heat recovery tower 2 cools the desorbed steam by spraying condensate. The non-condensable gas at the top of the heat recovery tower 2 is a high-concentration SO2 gas, which is sent to the outside through the non-condensable gas outlet 2-6.

[0023] During startup and operation, in order to supplement a small amount of heat to the regeneration tower 1 of this utility model, the heat pump energy-saving device in the regenerative desulfurization process also includes a second reboiler 11. The second reboiler 11 is provided with a steam inlet 11-1 and a condensate outlet 11-2. The steam inlet 11-1 is connected to a live steam pipe from the outside, and the condensate outlet 11-2 is used to discharge the condensate generated by the release of heat from the steam. A heat replenishment circulation pipe 12 is formed between the second reboiler 11 and the regeneration tower 1, that is, the second reboiler 11 can use live steam from the outside to supplement the heat of the regeneration tower 1 through the heat replenishment circulation pipe 12.

[0024] To fully utilize the low-temperature enthalpy of the lean amine liquid discharged from the lean amine liquid outlet 1-2 of regeneration tower 1, the heat pump energy-saving device in the regenerative desulfurization process also includes a lean-rich amine liquid heat exchanger 13. The rich amine liquid inlet 1-1 of regeneration tower 1 is connected to a rich amine liquid inlet pipe, and the lean amine liquid outlet 1-2 of regeneration tower 1 is connected to a lean amine liquid outlet pipe. Both the rich amine liquid inlet pipe and the lean amine liquid outlet pipe are connected to the lean-rich amine liquid heat exchanger 13, enabling heat exchange between the rich amine liquid entering regeneration tower 1 and the lean amine liquid discharged from regeneration tower 1. A drain pump 14 is also installed on the lean amine liquid outlet pipe between the lean-rich amine liquid heat exchanger 13 and the lean amine liquid outlet 1-2, providing power for the discharge of the lean amine liquid. The lean amine liquid can generally be cooled to 25℃~60℃ through the lean-rich amine liquid heat exchanger 13 before being sent to absorb SO2 in the flue gas, achieving recycling.

[0025] The condensate in the lower section of heat recovery tower 2, after exchanging heat with the desorption steam, reaches a temperature of 100℃~115℃. It is then sent to the evaporation end 3-1 of heat pump 3 via the second circulation pump 7. After the working fluid of heat pump 3 absorbs heat at the evaporation end 3-1, the temperature of the condensate drops to 90℃~105℃. After the working fluid is compressed by the compressor of heat pump 3, the temperature of the heat medium at the condensation end 3-2 of heat pump 3 rises from 100℃~120℃ to 120℃~140℃. The heat medium transfers heat to the lean amine liquid in regeneration tower 1 via the first reboiler 5. The lean amine liquid undergoes secondary vaporization and is converted into stripping steam for the desorption process, replacing the live steam from the outside.

Claims

1. A heat pump energy-saving device in a renewable desulfurization process, characterized in that: The regeneration tower (1), heat recovery tower (2), and heat pump (3) are included. The regeneration tower (1) is provided with a rich amine liquid inlet (1-1), a lean amine liquid outlet (1-2), a lean amine liquid circulation outlet (1-3), and a lean amine liquid circulation inlet (1-4). The lean amine liquid circulation outlet (1-3) and the lean amine liquid circulation inlet (1-4) are connected by a first circulation pipe (4). The first circulation pipe (4) is provided with a first circulation pump (4-1) and a first reboiler (5) in sequence along the flow direction of the lean amine liquid. The top of the regeneration tower (1) is provided with a desorption steam outlet (1-5), which is connected to the desorption steam inlet (2-1) of the lower section of the heat recovery tower (2). The lower section of the heat recovery tower (2) is equipped with packing or trays and a condensate spray pipe (2-3). The lower section of the heat recovery tower (2) has two condensate outlets (2-2). One condensate outlet (2-2) is connected to the inlet of the reflux pump (6), and the outlet of the reflux pump (6) is connected to the condensate inlet (1-6) of the regeneration tower (1). The other condensate outlet (2-2) is connected to the inlet of the second circulation pump (7), and the outlet of the second circulation pump (7) is connected to the inlet of the evaporation end (3-1) of the heat pump (3). The outlet of the evaporation end (3-1) is connected to the condensate spray pipe (2-3) of the lower section of the heat recovery tower (2). The condensation end (3-2) of the heat pump (3) is equipped with a heat medium inlet and The heat medium outlet, the first reboiler (5) is provided with a heat medium inlet and a heat medium outlet, the condenser end (3-2) of the heat pump (3) and the first reboiler (5) form a third circulation pipe (8), the third circulation pipe (8) is also provided with a third circulation pump (8-1); the upper section of the heat recovery tower (2) is provided with a condensate circulation outlet (2-4) and a condensate circulation inlet (2-5), the condensate circulation outlet (2-4) and the condensate circulation inlet (2-5) are connected by a fourth circulation pipe (9), the fourth circulation pipe (9) is provided with a fourth circulation pump (9-1) and a condenser (10) for cooling the condensate in sequence along the condensate flow direction; the top of the heat recovery tower (2) is provided with a non-condensable gas outlet (2-6).

2. The heat pump energy-saving device in the regenerative desulfurization process as described in claim 1, characterized in that: It also includes a second reboiler (11), which is provided with a steam inlet (11-1) and a condensate outlet (11-2). A heat replenishment circulation pipe (12) is formed between the second reboiler (11) and the regeneration tower (1).

3. The heat pump energy-saving device in the regenerative desulfurization process as described in claim 1, characterized in that: It also includes a lean-rich amine liquid heat exchanger (13), the rich amine liquid inlet (1-1) of the regeneration tower (1) is connected to a rich amine liquid inlet pipe, the lean amine liquid outlet (1-2) of the regeneration tower (1) is connected to a lean amine liquid outlet pipe, the rich amine liquid inlet pipe and the lean amine liquid outlet pipe are both connected to the lean-rich amine liquid heat exchanger (13), and the lean amine liquid outlet pipe between the lean-rich amine liquid heat exchanger (13) and the lean amine liquid outlet (1-2) is also equipped with a discharge pump (14).

4. The heat pump energy-saving device in the regenerative desulfurization process as described in claim 1, 2, or 3, characterized in that: The third circulation pipeline (8) is also equipped with an intermediate tank (8-2). The third circulation pipeline (8) is as follows: the heat medium inlet of the first reboiler (5) → the heat medium outlet of the first reboiler (5) → the intermediate tank (8-2) → the third circulation pump (8-1) → the heat medium inlet of the condenser end (3-2) of the heat pump (3) → the heat medium outlet of the condenser end (3-2) of the heat pump (3) → the heat medium inlet of the first reboiler (5).

5. The heat pump energy-saving device in the regenerative desulfurization process as described in claim 1, 2, or 3, characterized in that: The condenser (10) is provided with a cooling water inlet and a cooling water outlet.

6. The heat pump energy-saving device in the regenerative desulfurization process as described in claim 1, 2, or 3, characterized in that: The heat pump (3) is a high-temperature water source heat pump.

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