An apparatus and method for reducing energy consumption in an ionic liquid desulfurization system

Abstract

This invention discloses an apparatus and method for reducing energy consumption in an ionic liquid desulfurization system. The apparatus includes a desulfurization tower, a lean-rich amine heat exchanger, a desorption tower, a lean amine cooler, a lean amine storage tank, a desorbed gas condenser, and a gas-liquid separator. A flue gas flow meter and an inlet flue gas SO2 concentration analyzer are installed on the flue gas inlet pipe of the desulfurization tower; lean amine flow meters and rich amine flow meters are respectively installed at the outlet of the lean amine spray pump and the outlet of the rich amine transfer pump. The lean amine spray rate entering the desulfurization tower is adjusted in real time according to the flue gas flow rate and SO2 concentration in the flue gas. This invention achieves appropriate and reduced spraying of lean amine into the desulfurization tower, reducing the total amount of lean amine consumed during spraying and the amount of rich amine generated during the desulfurization process, resulting in a rich amine liquid with a stable SO2 concentration. Simultaneously, the amount of rich amine entering the desorption tower is stabilized, resulting in a stable high-concentration SO2 desorbed gas. This invention reduces steam consumption in the ionic liquid desulfurization system and achieves energy savings for the lean amine spray pump and the rich amine transfer pump.

Description

Technical Field

[0001] This invention relates to the field of flue gas desulfurization technology, and in particular to an apparatus and method for reducing energy consumption in an ionic liquid desulfurization system. Background Technology

[0002] In the field of flue gas desulfurization, ion-liquid desulfurization is one of the most efficient desulfurization methods. However, it also has the following drawbacks and shortcomings:

[0003] 1. Traditional ionic liquid desulfurization systems, due to the use of lean amine constant or relatively constant spraying, consume a huge amount of lean amine during the desulfurization process when dealing with fluctuating sulfur-containing flue gas with varying sulfur content, resulting in high pump energy consumption.

[0004] 2. Traditional ionic liquid desulfurization systems generate a huge amount of rich amines during the desulfurization process when dealing with fluctuating sulfur content in flue gas. The steam consumption during the desorption and regeneration of rich amines is large, resulting in extremely high energy consumption.

[0005] 3. Traditional ionic liquid desulfurization systems are prone to problems when dealing with fluctuating sulfur content in flue gas. The SO2 concentration in the amine-rich liquid is unstable, and the amount of high-concentration SO2 desorbed gas generated during regeneration fluctuates greatly, which significantly affects the recovery and utilization of high-concentration SO2 desorbed gas in subsequent processes.

[0006] The above-mentioned defects of traditional ion liquid desulfurization systems have seriously hindered their promotion and application. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention presents a device and method for reducing energy consumption in ion liquid desulfurization systems.

[0008] The present invention adopts the following technical solution:

[0009] An apparatus for reducing energy consumption in an ionic liquid desulfurization system includes a desulfurization tower, a lean amine heat exchanger, a desorption tower, a lean amine cooler, a lean amine storage tank, a desorption gas condenser, and a gas-liquid separator.

[0010] The lean amine solution in the lean amine storage tank is transported to the desulfurization tower for spray desulfurization via a lean amine spray pump. The rich amine solution produced after desulfurization is preheated by a rich amine transfer pump through a lean-rich amine heat exchanger and then sent to the desorption tower for desorption regeneration. The high-concentration SO2 desorbed gas discharged from the top of the desorption tower is cooled and condensed by a desorbed gas condenser and separated by a gas-liquid separator before being discharged from the exhaust port at the top of the gas-liquid separator for use in external processes. The desorbed lean amine solution in the bottom of the desorption tower is cooled by a lean-rich amine heat exchanger and then sent by a lean amine transfer pump to a lean amine cooler for further cooling before being sent to the lean amine storage tank for use in the desulfurization tower.

[0011] The flue gas inlet pipe of the desulfurization tower is equipped with a flue gas flow meter and an inlet flue gas SO2 concentration analyzer.

[0012] Preferably, the lean amine spray pump is a variable frequency pump, which can adjust the amount of lean amine sprayed into the desulfurization tower by frequency conversion. The outlet pipe of the lean amine spray pump is equipped with a lean amine flow meter to display and measure the amount of lean amine sprayed into the desulfurization tower.

[0013] Optionally, a reflux pipe to the lean amine storage tank can be installed on the outlet pipe of the lean amine spray pump (before the lean amine flow meter), and the amount of lean amine sprayed into the desulfurization tower can be adjusted by the reflux flow rate.

[0014] Optionally, the flue gas flow meter and the inlet flue gas SO2 concentration analyzer can also be installed before the inlet flue gas pipeline of the desulfurization tower, on other equipment and pipelines that can accurately measure the amount of SO2 entering the desulfurization tower.

[0015] As a priority, when the location of the flue gas flow meter and the inlet flue gas SO2 concentration analyzer is far from the inlet of the desulfurization tower, the control and adjustment of the amine-poor spray volume into the desulfurization tower by this device and method is delayed. The delay time t = the internal volume of the system between the installation location of the flue gas flow meter and the inlet flue gas SO2 concentration analyzer and the inlet of the desulfurization tower ÷ the flue gas operating flow rate.

[0016] Preferably, the amine delivery pump for the desulfurization tower is a variable frequency pump, which can adjust the pump's delivery rate through frequency conversion. An amine flow meter is installed on the outlet pipe of the amine delivery pump to display and measure the amine delivery rate. The amine delivery rate is adjusted based on the average value of the lean amine spray volume entering the desulfurization tower, as displayed by the lean amine flow meter, ensuring a relatively stable amount of amine desorption delivered to the desorption tower.

[0017] Preferably, the relative stability of the SO2 content and the relative stability of the amount of rich amine transported ensure the stability of the amount of SO2 in the rich amine entering the desorption tower. Therefore, the amount of high-concentration SO2 gas desorbed by the desorption tower is necessarily relatively stable. This greatly facilitates the subsequent processing and reuse of this portion of high-concentration SO2 gas.

[0018] Optionally, the upper part of the desulfurization tower is provided with an amine recovery section, which uses an external amine recovery tank and an amine recovery pump for circulating spraying to recover the amine liquid entrained in the flue gas.

[0019] Preferably, an outlet flue gas SO2 concentration analyzer is installed on the outlet pipe of the desulfurization tower. This allows for real-time detection and display of the residual SO2 concentration in the outlet flue gas, enabling real-time monitoring of the desulfurization performance of the tower and effectively ensuring the reliable operation of the desulfurization system.

[0020] Preferably, both the lean amine transfer pump and the reflux pump are variable frequency pumps, which can adjust the pump's delivery rate by frequency conversion.

[0021] A method for reducing energy consumption in an ionic liquid desulfurization system involves adjusting the lean amine spray rate into the desulfurization tower based on the flue gas flow rate Q measured by the inlet flue gas flow meter and the SO2 concentration c measured by the inlet flue gas SO2 concentration analyzer. Specifically, the lean amine spray rate is adjusted in real-time according to fluctuations in the SO2 content of the sulfur-containing process flue gas entering the desulfurization tower. The lean amine spray rate V = Q × c × a, where V is the lean amine spray rate, Q is the flue gas flow rate, c is the SO2 concentration of the flue gas, and a is the amine spray coefficient, determined by the properties of the amine solution used. The SO2 content in the desulfurized rich amine obtained by spraying in this manner is relatively stable.

[0022] As a preferred option, the amount of amine-poor spraying in the desulfurization tower is adjusted according to the amount of flue gas Q entering the desulfurization tower and the SO2 concentration c of the flue gas. The adjustment method can be automatic adjustment by instrument interlock or manual tracking adjustment based on the calculated value displayed by the control system.

[0023] The beneficial effects of this invention are: (1) By installing a flue gas flow meter and a flue gas SO2 concentration analyzer on the flue gas inlet pipe of the desulfurization tower, real-time measurement of the flue gas flow rate and SO2 concentration in the flue gas entering the desulfurization tower is realized. Furthermore, the real-time fluctuation of SO2 in the sulfur-containing process flue gas entering the desulfurization tower can be tracked in real time; (2) By linking the lean amine spraying rate into the desulfurization tower with the flue gas flow rate and SO2 concentration in the flue gas entering the desulfurization tower, the lean amine spraying rate into the desulfurization tower can be adjusted in real time according to the fluctuation of SO2 in the flue gas entering the desulfurization tower. This achieves appropriate spraying of SO2 in the flue gas entering the desulfurization tower by the lean amine liquid, greatly reducing the total amount of lean amine spraying consumed in the desulfurization process, reducing the operating power consumption of the lean amine spraying pump, and ensuring the relative stability of the sulfur concentration of the rich amine after desulfurization. At the same time, it reduces the amount of rich amine produced during the desulfurization process, reduces the total amount of rich amine that the system needs to desorb, and greatly reduces the steam consumption of the desorption tower; (3) By controlling the amount of rich amine transported to the desulfurization tower according to the average value of the amount of lean amine sprayed into the desulfurization tower displayed by the lean amine flow meter, the amount of rich amine desorbed by the rich amine transport pump to the desorption tower is relatively stable. (4) The relative stability of the sulfur concentration of rich amine after desulfurization and the relative stability of the amount of rich amine desorbed into the desorption tower together achieve the relative stability of SO2 content in the rich amine liquid entering the desorption tower. Therefore, the amount of high-concentration SO2 gas desorbed from the desorption tower is also relatively stable. This is conducive to the recovery and utilization of high-concentration SO2 desorbed gas in subsequent processes; (5) The relative stability of the sulfur concentration of rich amine after desulfurization and the relative stability of the amount of rich amine desorbed into the desorption tower together achieve the stability of the steam consumption of the desorption tower, which is conducive to the stable and efficient operation of the external steam supply network and greatly reduces the operating energy consumption of the ion liquid desulfurization system due to the change in the sulfur content of the flue gas entering the desulfurization tower. The reduction in energy consumption of the ion-liquid desulfurization system varies depending on the fluctuation range of sulfur content in the flue gas entering the desulfurization tower. For an ion-liquid desulfurization system for fluctuating sulfur-containing process gas with a maximum instantaneous SO2 content ÷ average SO2 content = 10, the steam consumption, power consumption of the rich amine transfer pump, and power consumption of the lean amine spray pump of this invention are approximately 1 / 10 of those of a traditional ion-liquid desulfurization system, significantly reducing the operating energy consumption of the ion-liquid desulfurization system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention;

[0025] Figure 2 This is a flue gas volume fluctuation curve in the flue gas of the flue gas containing sulfur in this embodiment.

[0026] Figure 3 This is a graph showing the SO2 concentration in flue gas from a sulfur-containing process in this embodiment.

[0027] Figure 4 This is a curve showing the SO2 content in flue gas from a sulfur-containing process in this embodiment.

[0028] In the diagram: 1. Desulfurization tower, 2. Lean and rich amine heat exchanger, 3. Desorption tower, 4. Lean amine cooler, 5. Lean amine storage tank, 6. Desorption gas condenser, 7. Gas-liquid separator, 8. Reboiler, 9. Amine recovery tank, 10. Rich amine transfer pump, 11. Lean amine transfer pump, 12. Lean amine spray pump, 13. Amine recovery pump, 14. Reflux liquid pump, 15. Flue gas flow meter, 16. Inlet flue gas SO2 concentration analyzer, 17. Lean amine flow meter, 18. Rich amine flow meter, 19. Outlet flue gas SO2 concentration analyzer. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0030] like Figure 1 As shown, an apparatus for reducing energy consumption in an ionic liquid desulfurization system includes a desulfurization tower 1, a lean amine heat exchanger 2, a desorption tower 3, a lean amine cooler 4, a lean amine storage tank 5, a desorption gas condenser 6, a gas-liquid separator 7, a reboiler 8, and an amine recovery tank 9.

[0031] The lean amine liquid in the lean amine storage tank 5 is transported to the desulfurization tower 1 for spray desulfurization by the lean amine spray pump 12; the rich amine liquid produced after desulfurization is preheated by the rich amine transfer pump 10 through the lean-rich amine heat exchanger 2 and then sent to the desorption tower 3 for desorption regeneration; the high-concentration SO2 desorption gas discharged from the top of the desorption tower 3 is cooled and condensed by the desorption gas condenser 6 and separated by the gas-liquid separator 7, and then discharged from the exhaust port at the top of the gas-liquid separator 7 for use in external processes; the desorbed lean amine liquid in the bottom of the desorption tower 3 is first cooled by the lean-rich amine heat exchanger 2, and then sent by the lean amine transfer pump 11 to the lean amine cooler 4 for further cooling before being sent to the lean amine storage tank 5 for use in the desulfurization tower 1;

[0032] The flue gas inlet pipe of the desulfurization tower 1 is equipped with a flue gas flow meter 15 and an inlet flue gas SO2 concentration analyzer 16.

[0033] The liquid separated by gas-liquid separator 7 is transported back to the desorption tower for spraying by reflux pump 14. An amine recovery section is set at the top of the desulfurization tower, which is circulated and sprayed through an external amine recovery tank 9 and amine recovery pump 13 to recover the amine liquid entrained in the flue gas.

[0034] A reboiling section is provided at the bottom of the desorption tower 3, so that the desorbed lean amine solution is reboiled through the reboiler 8 and then returned to the desorption tower 3 for complete desorption.

[0035] The lean amine spray pump 12 is a variable frequency pump, and the outlet pipe of the lean amine spray pump 12 is equipped with a lean amine flow meter 17.

[0036] The amine transfer pump 10 is a variable frequency pump, and the outlet pipe of the amine transfer pump 10 is equipped with an amine flow meter 18.

[0037] An outlet flue gas SO2 concentration analyzer 19 is installed on the outlet flue gas duct of desulfurization tower 1. The lean amine transfer pump 11 and the reflux liquid pump 14 are variable frequency pumps.

[0038] A method for reducing energy consumption in an ionic liquid desulfurization system includes the following steps: Adjusting the lean amine spray rate into the desulfurization tower based on the flue gas flow rate Q measured by the inlet flue gas flow meter and the SO2 concentration c measured by the inlet flue gas SO2 concentration analyzer. Specifically, adjusting the lean amine spray rate in real time based on fluctuations in the SO2 content of the sulfur-containing process flue gas entering the desulfurization tower. The lean amine spray rate V = Q × c × a, where V is the lean amine spray rate, Q is the flue gas flow rate into the desulfurization tower, c is the SO2 concentration of the flue gas entering the desulfurization tower, and a is the amine spray coefficient, determined by the properties of the amine liquid used.

[0039] Example: For a fluctuation period of 10 hours, the maximum peak SO2 content is 3000 Nm³. 3 / h, with an average SO2 content of 500 Nm³. 3 Flue gas containing sulfur and flue gas with a flue gas volume of / h. Its flue gas volume fluctuation curve, flue gas SO2 concentration curve, and flue gas SO2 content curve are shown below. Figure 2-4 As shown.

[0040] Using the traditional ionic liquid desulfurization method, the amine-poor spray rate in the desulfurization tower is 3000 × am. 3 / h (where a is the amine spray coefficient, determined by the properties of the amine liquid used in the ion-liquid desulfurization system), the total lean amine spraying amount in one cycle is 3000a × 10 = 30000a m 3 The amount of amine-rich material produced after desulfurization is 30,000 a m. 3 The SO2 concentration in the amine-rich gas fluctuates dramatically with changes in the SO2 content of the sulfur-containing process flue gas. The amount of high-concentration SO2 gas obtained after desorption in the desorption tower also fluctuates dramatically with the SO2 content curve of the sulfur-containing process flue gas.

[0041] According to embodiments of the present invention, such as Figure 1 As shown:

[0042] Before the sulfur-containing process flue gas enters the desulfurization tower 1, the flue gas flow rate Q and the SO2 concentration c in the flue gas are measured in real time in advance by the flue gas flow meter 15 and the inlet flue gas SO2 concentration analyzer 16 installed in front of the desulfurization tower. Thus, the amount of SO2 to enter the desulfurization tower (SO2 amount = Q × c) can be calculated in advance by the control system.

[0043] The control system adjusts the operating frequency of the lean amine spray pump 12 based on the received flue gas flow rate Q and SO2 concentration c at the desulfurization tower 1, according to the formula: Lean amine spray rate V = Q × c × a (where V is the lean amine spray rate, Q is the flue gas flow rate, c is the SO2 concentration, and a is the amine spray coefficient determined by the properties of the amine solution used). After spray desulfurization, a relatively stable SO2 concentration of rich amine is obtained.

[0044] Because the flue gas from this sulfur-containing process has a fluctuation period of 10 hours and an average SO2 content of 500 Nm³, 3 / h, therefore the total SO2 entering the desulfurization tower in one cycle is 500*10=5000Nm 3 / h. Since the entire desulfurization process in this unit involves spraying lean amine solution at an appropriate rate based on the SO2 input to desulfurization tower 1, the total amount of lean amine sprayed into desulfurization tower 1 within a 10-hour fluctuation cycle is 5000 a m. 3 Simultaneously generating 5000 a m 3 Ammonia-rich liquid.

[0045] The desulfurized rich amine solution produced after the lean amine solution is sprayed and desulfurized in desulfurization tower 1 is fed into the desulfurization tower by the rich amine transfer pump 10 according to the average value of the lean amine spray rate displayed by the lean amine flow meter 17 (5000a ÷ 10 = 500a m). 3 The rich amine solution is heated by the lean amine heat exchanger 2 and then fed into the desorption tower 3 at a constant flow rate for desorption. The flow rate is displayed by the rich amine flow meter 18. A nearly stable high-concentration SO2 desorbed gas (5000 ÷ 10 = 500 Nm³) is obtained. 3 / h).

[0046] The lean amine solution obtained after desorption and regeneration (500 a m) 3 The amine is first cooled by the lean amine heat exchanger 2, then sent by the lean amine transfer pump 11 to the lean amine cooler 4 for further cooling, and finally sent to the lean amine storage tank 5 for continued use.

[0047] The sulfur-containing process flue gas is desulfurized by the lean amine spray in desulfurization tower 1 and the amine is recovered in the upper part of the desulfurization tower before being discharged from the top of desulfurization tower 1.

[0048] The residual SO2 concentration in the flue gas after desulfurization is detected in real time by an outlet flue gas SO2 concentration analyzer 19 installed on the outlet flue gas pipeline of desulfurization tower 1, so as to realize the monitoring and tracking of the desulfurization effect of the desulfurization tower.

[0049] Through the above process, the total amount of lean amine spray consumed by this invention within one flue gas cycle (10h) is 5000 am. 3 At the same time, it generates 5000 a m 3 Amine-rich liquid. Compared to traditional ionic liquid desulfurization at 30,000 m...3 Total amount of amine-poor spray and 30,000 a m 3 Compared to the desorption capacity of rich amine, the power consumption of the lean amine spray pump and the rich amine delivery pump of this invention, as well as the steam consumption during the desorption process of rich amine, are all about 16.7% of those of the traditional ion liquid desulfurization system, which greatly reduces the operating energy consumption of the ion liquid desulfurization system.

[0050] Meanwhile, since the sulfur concentration of the rich amine and the amount of rich amine desorbed into the desorption tower are relatively constant in this invention, a stable high-concentration SO2 desorbed gas (where the SO2 content is 500 Nm³) can be obtained. 3 / h).

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A method for reducing energy consumption in an ionic liquid desulfurization system, characterized in that, The device used in this method includes a desulfurization tower (1), a lean amine heat exchanger (2), a desorption tower (3), a lean amine cooler (4), a lean amine storage tank (5), a desorbed gas condenser (6), and a gas-liquid separator (7). The lean amine liquid in the lean amine storage tank (5) is transported to the desulfurization tower (1) for spray desulfurization by the lean amine spray pump (12); the rich amine liquid produced after desulfurization is preheated by the rich amine transfer pump (10) through the lean-rich amine heat exchanger (2) and then sent to the desorption tower (3) for desorption regeneration; the high concentration SO2 desorption gas discharged from the top of the desorption tower (3) is cooled and condensed by the desorption gas condenser (6) and separated by the gas-liquid separator (7) and then discharged from the exhaust port at the top of the gas-liquid separator (7) for use in external processes; the desorbed lean amine liquid in the bottom of the desorption tower (3) is cooled by the lean-rich amine heat exchanger (2) and then sent by the lean amine transfer pump (11) to the lean amine cooler (4) for further cooling and then sent to the lean amine storage tank (5) for use in the desulfurization tower; The flue gas inlet pipe of the desulfurization tower (1) is equipped with a flue gas flow meter (15) and an inlet flue gas SO2 concentration analyzer (16). The amine-poor spray pump (12) is a variable frequency pump, and the outlet pipe of the amine-poor spray pump (12) is equipped with an amine-poor flow meter (17). The amine delivery pump (10) is a variable frequency pump, and the outlet pipe of the amine delivery pump (10) is equipped with an amine flow meter (18). The method is as follows: Based on the flue gas flow rate Q of the desulfurization tower (15) measured by the flue gas flow meter (15) and the SO2 concentration c of the flue gas in the desulfurization tower (16) measured by the flue gas SO2 concentration analyzer, the lean amine spray rate of the desulfurization tower (1) is adjusted. That is, based on the fluctuation of SO2 in the sulfur-containing process flue gas of the desulfurization tower (1), the lean amine spray rate of the desulfurization tower (1) is adjusted in real time. The lean amine spray rate of the desulfurization tower V = Q × c × a, where V is the lean amine spray rate of the desulfurization tower, Q is the flue gas flow rate of the desulfurization tower, c is the SO2 concentration of the flue gas in the desulfurization tower, and a is the amine spray coefficient, which is determined by the properties of the amine liquid used. The rich amine transfer pump (10) delivers the rich amine liquid according to the average value of the poor amine spray volume measured by the poor amine flow meter (17).

2. The method for reducing energy consumption in an ionic liquid desulfurization system according to claim 1, characterized in that, The liquid separated by the gas-liquid separator (7) is transported back to the desorption tower (3) by the return liquid pump (14) for spraying.

3. The method for reducing energy consumption in an ionic liquid desulfurization system according to claim 1, characterized in that, The upper part of the desulfurization tower is equipped with an amine recovery section, which is circulated and sprayed through an external amine recovery tank (9) and an amine recovery pump (13) to recover the amine liquid entrained in the flue gas.

4. The method for reducing energy consumption in an ionic liquid desulfurization system according to claim 1, characterized in that, The bottom of the desorption tower (3) is provided with a reboiling section, through which the desorbed lean amine solution is reboiled by the reboiler (8) and then returned to the desorption tower (3) for full desorption.

5. The method for reducing energy consumption in an ionic liquid desulfurization system according to claim 1, characterized in that, An outlet flue gas SO2 concentration analyzer (19) is installed on the outlet flue gas pipe of the desulfurization tower (1).

6. A method for reducing energy consumption in an ionic liquid desulfurization system according to claim 2, characterized in that, The lean amine transfer pump (11) and the reflux pump (14) are variable frequency pumps.

7. The method for reducing energy consumption in an ionic liquid desulfurization system according to claim 1, characterized in that, The amount of lean amine sprayed in the desulfurization tower is adjusted according to the amount of flue gas Q entering the desulfurization tower and the SO2 concentration c of the flue gas. The adjustment method is either automatic adjustment by instrument interlock or manual tracking and adjustment based on the calculated value displayed by the control system.

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