CN116096475A

CN116096475A - Exhaust gas treatment device and exhaust gas treatment method

Info

Publication number: CN116096475A
Application number: CN202280005787.3A
Authority: CN
Inventors: 糸川和芳; 当山广幸
Original assignee: Fuji Electric Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2021-03-23
Filing date: 2022-02-10
Publication date: 2023-05-09
Also published as: JPWO2022201947A1; JP7380946B2; KR20230044491A; WO2022201947A1

Abstract

The present invention provides an exhaust gas treatment device capable of switching an operation mode between a closed-loop operation of circulating a used liquid used in treating exhaust gas and an open-loop operation of discharging the used liquid to the outside, the exhaust gas treatment device comprising: a reaction tower to which the offgas is supplied and which purifies the offgas by a liquid; a storage unit for storing a used liquid for purifying the exhaust gas and supplying the used liquid, which is recovered in a closed-loop operation by the purification ability of the alkaline agent, to the inside of the reaction tower; and an input unit for inputting the alkaline agent into the storage unit before starting to supply the used liquid from the storage unit into the reaction tower when the closed-loop operation is started.

Description

Exhaust gas treatment device and exhaust gas treatment method

Technical Field

The present invention relates to an exhaust gas treatment device and an exhaust gas treatment method.

An exhaust gas treatment device called a scrubber device is widely used, which neutralizes sulfur components (sulfur components) in exhaust gas by scrubber liquid such as seawater. The operation of the scrubber device includes an open loop operation and a closed loop operation. In the open-loop operation, the scrubber device discharges the used scrubber liquid, which has been used in purifying the exhaust gas, to the outside. In the closed-loop operation, the scrubber device recovers the purifying ability of the used scrubber liquid by adding an alkaline agent to the used scrubber liquid, and circulates the used scrubber liquid recovered in the purifying ability. A marine scrubber device that performs a closed-loop operation using magnesium hydroxide or magnesium oxide is known (for example, patent document 1). In scrubber devices for purifying boiler exhaust gas or the like used on land, there is known a scrubber device for purifying boiler exhaust gas or the like based on the amount of sulfur component (SO _X ) Techniques for controlling the amount of magnesium hydroxide to be charged by concentration (for example, patent documents 2 to 4). As a related art, a technique of performing pH control using an alkaline agent in a scrubber device is known (for example, patent documents 5 and 6). As related art, a technique of estimating the amount of sulfur components absorbed by a scrubber liquid is known (for example, patent documents 7 and 8).

Patent document 1: international publication No. WO2017/194645

Patent document 2: japanese patent laid-open No. 9-66119

Patent document 3: japanese patent laid-open No. 7-275649

Patent document 4: japanese patent laid-open No. 8-196863

Patent document 5: international publication No. WO2012/000790

Patent document 6: japanese patent laid-open No. 3-267114

Patent document 7: international publication No. WO2014/119513

Patent document 8: international publication WO2016/009549

The invention aims to solve the technical problems

In the closed-loop operation, when a sodium-containing alkaline agent having a lower solubility, that is, a lower reaction rate than sodium hydroxide, sodium carbonate, sodium hydrogencarbonate or the like is used, it takes a longer time to dissolve the alkaline agent in the scrubber liquid. Therefore, a buffer tank (storage unit) for storing the scrubber liquid for dissolving the alkaline agent needs to be enlarged or a plurality of tanks need to be provided, as compared with the use of the sodium-containing alkaline agent. However, in the exhaust gas treatment device, it is desired to reduce the capacity of the storage portion.

Disclosure of Invention

In order to solve the above-described problems, in one aspect of the present invention, an exhaust gas treatment device is provided that can switch an operation mode between a closed-loop operation of circulating used liquid that has been used in treating exhaust gas and an open-loop operation of discharging the used liquid to the outside. The exhaust treatment device may comprise a reaction tower. In the reaction tower, the off-gas is supplied and purified by a liquid. The exhaust treatment device may include a storage portion. The storage portion may store used liquid that has been used in purifying the exhaust gas. The storage unit may supply the liquid used to recover the purification ability by the alkaline agent in the closed-loop operation to the reaction column. The exhaust gas treatment device may include an input portion. In the case of starting the closed-loop operation, the charging section may charge the alkaline agent into the storage section before starting the supply of the used liquid from the storage section into the reaction column.

The charging section may charge at least one of magnesium oxide and magnesium hydroxide as the alkaline agent into the storage section.

The charging section may charge solid powder of at least one of magnesium oxide and magnesium hydroxide as the alkaline agent into the storage section.

The charging section may charge magnesium oxide as the alkaline agent into the storage section.

When the operation mode is switched to the closed-loop operation, the charging unit may charge magnesium oxide, which is larger than the amount capable of undergoing a neutralization reaction with the amount of sulfur component absorbed by the liquid in one cycle, into the storage unit at the first timing in the closed-loop operation.

When the operation mode is switched to the closed-loop operation, the charging unit may charge magnesium oxide into the storage unit at the first timing, the amount of magnesium oxide being 2 to 400 times the amount of the sulfur component that can be absorbed by the liquid in one cycle for neutralization reaction.

When the operation mode is switched to the closed-loop operation, the charging unit may charge magnesium oxide, which is larger than the amount capable of undergoing a neutralization reaction with the amount of sulfur component absorbed by the liquid in one cycle, into the storage unit at the first timing.

In the closed-loop operation continuing process, the input unit may supplement the magnesium oxide in the storage unit at a smaller amount than the input amount at the first timing at a second timing subsequent to the first timing.

The exhaust gas treatment device may further include an adjustment portion. The adjustment unit may adjust the amount of magnesium oxide to be charged into the storage unit before starting to supply the used liquid from the storage unit into the reaction column when the operation mode is switched from the open-loop operation to the closed-loop operation.

The adjustment unit may estimate the amount of sulfur component absorbed by the liquid in one cycle based on the output of the combustion device that generates the exhaust gas and the concentration of sulfur component contained in the fuel oil used by the combustion device. The adjustment unit can adjust the amount of sulfur added based on the estimated amount of sulfur component.

The adjustment unit can adjust the amount of sulfur component in the gas released from the reaction tower during the open-loop operation and the planned output value of the combustion device that generates the exhaust gas after switching the operation mode to the closed-loop operation.

The adjustment unit can adjust the input amount according to the hydrogen ion index (pH) of each of the liquid supplied to the reaction tower during the open-loop operation and the used liquid discharged from the reaction tower to the outside, and the output planned value of the combustion device that generates the exhaust gas after the operation mode is switched to the closed-loop operation.

When the operation mode is switched from the open-loop operation to the closed-loop operation, the adjustment unit may adjust the input amount based on the amount of magnesium oxide remaining in the storage unit in the last closed-mode operation.

The exhaust treatment device may further include a reservoir cleaning mechanism. The storage part cleaning mechanism can clean the storage part.

The exhaust gas treatment device may further include a pipe cleaning mechanism. The pipe cleaning mechanism may clean the inside of the pipe between the reaction tower and the storage unit.

In a second aspect of the present invention, an exhaust gas treatment method is provided that can switch an operation mode between a closed-loop operation for circulating used liquid that has been used in treating exhaust gas and an open-loop operation for discharging the used liquid to the outside. The exhaust gas treatment method may include the step of storing used liquid that has been used in purifying the exhaust gas. The exhaust treatment method may include the step of contacting the used liquid, which has recovered the purification capacity by the alkaline agent in a closed loop action, with the exhaust. The exhaust gas treatment method may include a step of adding an alkaline agent to the stored used liquid before the used liquid is supplied to contact the exhaust gas in the case where the closed-loop operation is started.

The summary of the invention is not intended to list all of the essential features of the invention. Further, sub-combinations of these feature sets may also constitute the invention.

Drawings

Fig. 1 is a diagram illustrating a schematic configuration of an exhaust gas treatment device 1 according to an embodiment of the present invention.

FIG. 2 is a graph showing experimental values of the rate of increase of pH based on the MgO concentration.

Fig. 3 is a graph showing an example of experimental values of reaction rate constants.

Fig. 4 is a diagram illustrating a schematic configuration of the exhaust gas treatment device 2 of the comparative example.

Fig. 5 is a flowchart showing an example of an exhaust gas treatment method in the exhaust gas treatment device 1.

Fig. 6 is a flowchart showing another example of the exhaust gas treatment method in the exhaust gas treatment device 1.

Fig. 7 is a flowchart showing an example of the input amount adjustment process.

Fig. 8 is a flowchart showing another example of the input amount adjustment process.

Fig. 9 is a flowchart showing another example of the input amount adjustment process.

Fig. 10 is a flowchart showing another example of the input amount adjustment process.

Fig. 11 is a flowchart showing an example of the cleaning process.

Detailed Description

The present invention will be described below by way of embodiments of the invention, but the following embodiments are not intended to limit the invention as claimed. The combination of the features described in the embodiments is not always necessary for the solution of the invention.

Fig. 1 is a diagram illustrating a schematic configuration of an exhaust gas treatment device 1 according to an embodiment of the present invention. The exhaust gas treatment device 1 purifies the exhaust gas 100 by reducing sulfur components in the exhaust gas 100 generated in the combustion device 3. The combustion device 3 may be an engine or a boiler, preferably an engine, in particular a marine engine. The sulfur component may contain sulfur compounds such as SOx (sulfur oxide).

The exhaust gas treatment device 1 includes a reaction tower 10. In the reaction tower 10, the exhaust gas 100 from the combustion device 3 is contacted with seawater, i.e. scrubber liquid. The scrubber liquid may be seawater or an aqueous alkaline solution. The exhaust gas 100 from the combustion device 3 is introduced into the reaction tower 10 via the combustion gas exhaust pipe 12. Scrubber liquid is sprayed from nozzles 13 within reaction column 10. The scrubber liquid is led to the nozzle 13 via a scrubber liquid pipe 14.

When the off-gas 100 and the scrubber liquid are in gas-liquid contact, the sulfur component of the off-gas 100 is absorbed into the scrubber liquid. The sulfur component is dissolved in the scrubber to produce sulfurous acid H ₂ SO ₃ . In fact, sulfurous acid H ₂ SO ₃ Dissociation into hydrogen ions H ⁺ Bisulphite ion HSO ₃ ^- Acidic. By absorbing the sulfur components into the scrubber liquid, the sulfur components in the exhaust gas 100 are reduced. The purified gas in which the sulfur component is reduced is discharged to the outside from the gas discharge portion 15.

When the scrubber liquid is seawater, the alkaline component in the seawater is bicarbonate ion (HCO) ₃ ^- ) Carbonate ion (CO) ₃ ^2- ) And sulfurous acid H ₂ SO ₃ And (5) neutralization. The scrubber liquid in the state of insufficient alkaline component due to the neutralization reaction becomes the used scrubberLiquid (used liquid) is collected in the lower portion of the reaction column 10. The used scrubber liquid passes through the used scrubber piping 16.

The exhaust gas treatment device 1 is configured to be capable of switching an operation mode between an open-loop operation and a closed-loop operation. When the operation mode is an open-loop operation, the valve 18 between the used scrubber pipe 16 and the discharge pipe 17 is opened, and the valve 20 between the used scrubber pipe 16 and the circulation pipe 19 is closed. In the open loop operation, the used scrubber liquid is sent from the used scrubber piping 16 to the discharge pipe 17, and the used scrubber liquid is discharged from the sea water discharge port 21. In the open loop operation, seawater is introduced from the seawater inlet port 22 as scrubber liquid. In the open loop operation, sea water is introduced into the scrubber liquid pipe 14 via the sea water pipe 24, the valve 32 and the pump 23 for scrubber liquid. In an open loop action, the valve 32 between the sea water pipe 24 and the scrubber liquid pipe 14 is opened. On the other hand, a valve 33 described later is closed. Thus, the used scrubber liquid is discharged to the outside in the open loop operation.

The exhaust gas treatment device 1 includes a storage unit 30 and an input unit 40. When the operation mode is closed-loop operation, the valve 20 between the used scrubber pipe 16 and the circulation pipe 19 is opened, and the valve 18 between the used scrubber pipe 16 and the discharge pipe 17 is closed.

The used scrubber liquid is stored in the storage section 30 from the used scrubber piping 16 via the circulation pipe 19. Then, the input unit 40 inputs the alkaline agent into the storage unit 30. The alkaline agent is thrown into the used scrubber liquid in the storage section 30 by the throw-in section 40, and the purification ability of the used scrubber liquid in the storage section 30 for the exhaust gas 100 is recovered. The purification ability of the exhaust gas 100 may refer to the neutralization ability of sulfurous acid or the like in the exhaust gas 100. The storage unit 30 may supply the liquid used to recover the purification ability by the alkaline agent in the closed-loop operation into the reaction column 10. Specifically, the used scrubber liquid, which recovers the purification ability, is supplied to the reaction tower 10 via the circulating scrubber liquid supply pipe 34, the valve 33, the pump 23, and the scrubber liquid pipe 14 inside the storage section 30.

In a closed loop action, it is essentially the valve 33 between the circulating scrubber liquid feed line 34 and the scrubber liquid line 14 that is opened, and the valve 32 between the sea water line 24 and the scrubber liquid line 14 that is closed. However, if the liquid volume of the scrubber used during the closed loop action is reduced, the valve 32 may be temporarily opened to capture seawater and replenish the liquid volume to an appropriate level.

The storage section 30 is a tank for storing the used scrubber liquid and supplying the used liquid, which recovers the purification ability, into the reaction tower 10. The storage section 30 may be a buffer tank. A circulation path including the reaction column 10, the used scrubber piping 16, the circulation pipe 19, the storage unit 30, the circulation scrubber liquid supply pipe 34, and the scrubber liquid pipe 14 is formed, and the storage unit 30 is provided in a path through which the scrubber liquid circulates.

When the closed-loop operation is started, the charging unit 40 may charge the alkaline agent into the storage unit 30 before starting to supply the used scrubber liquid from the storage unit 30 into the reaction column 10. For example, the input unit 40 inputs the alkaline agent into the storage unit 30 in a state where the valve 33 is closed.

The input portion 40 may be made of magnesium oxide (MgO) and magnesium hydroxide (Mg (OH) ₂ ) At least one of them is put into the storage section 30 as an alkaline agent. With respect to magnesium oxide and magnesium hydroxide, since the volume of the medicine required for purifying the exhaust gas 100 is smaller than that of sodium-containing alkaline agents such as sodium hydroxide, sodium carbonate, sodium bicarbonate, and the like, the storage space for the alkaline agents can be saved.

In particular, the charging section 40 may charge solid powder of at least one of magnesium oxide and magnesium hydroxide as an alkaline agent into the storage section 30. Therefore, magnesium oxide or magnesium hydroxide does not have to be dissolved in the scrubber liquid in advance to make it slurry-like. Thus, a space for dissolving magnesium oxide or magnesium hydroxide in the scrubber liquid in advance to maintain a slurry state is not required. The input unit 40 inputs magnesium oxide as an alkaline agent into the storage unit 30, and the cost of magnesium oxide is lower than that of magnesium hydroxide.

Dissolving magnesium oxide in a scrubber liquor containing water as the main component will produce MgO (magnesium oxide) +H ₂ O (Water) →Mg (OH) ₂ Hydration reaction of (magnesium hydroxide). ThenProducing Mg (OH) ₂ (magnesium hydroxide) +H ₂ SO ₃ (sulfurous acid) →MgSO ₃ (magnesium sulfite) +2H ₂ Neutralization of O (water). MgSO (MgSO) ₃ (magnesium sulfite) is converted into MgSO by oxidation ₄ (magnesium sulfate).

When magnesium oxide (MgO) is used as an alkaline agent, the presence of magnesium Oxide (OH) is believed to be responsible for the presence of magnesium oxide (MgO) ₂ (magnesium hydroxide) and thus is subjected to Mg (OH) ₂ (magnesium hydroxide) solubility. Mg (OH) ₂ The solubility of (magnesium hydroxide) is calculated as follows.

Mg(OH) ₂ The pH of the saturated aqueous solution of (magnesium hydroxide) was 10.5.Mg (OH) ₂ The pOH of the saturated aqueous solution of (magnesium hydroxide) is represented by the following formula 1.

[ mathematics 1]

pOH＝14-pH＝3.5 (1)

According to the above formula 1, mg (OH) ₂ OH of saturated aqueous solution of (magnesium hydroxide) ^- The ion (hydroxide ion) concentration is represented by the following formula 2.

[ math figure 2]

[OH ^- ]＝10 ^-pOH ＝10 ^-3.5 ＝0.316×10 ^-3 [mol/L] (2)

OH ^- The ions (hydroxide ions) are Mg (OH) ₂ The valence number in (magnesium hydroxide) is 2. Therefore, if the solubility of MgO (magnesium oxide) is Cs, cs is represented by the following formula 3.

[ math 3]

Cs＝0.3162×10-3÷2＝0.158×10-3[mol/L](3)

According to the above formula 3, mgO (magnesium oxide) has a solubility of 0.158×10 ^-3 mol/L (liter). The solubility is less than that of sodium-containing alkaline agents. Therefore, it takes time to increase the pH of the scrubber liquid (circulating water) with magnesium oxide (MgO) as the oxidizing agent. By increasing the concentration (input) of magnesium oxide (MgO), the solid surface area S can be increased. As shown in the following reaction rate formula, the hydration reaction can be promoted by increasing the fixed surface area (S) of the alkaline agent powder. In addition, C: mg (OH) ₂ Concentration, k: reaction rate constant, S: solid surface area.

[ mathematics 4]

The scrubber liquid contains H ₂ SO ₄ Mg (OH) thus dissolved in the scrubber liquid ₂ (magnesium hydroxide) with the scrubber liquor. Therefore, c=0 can be given in equation 4. Furthermore, from the MgO (magnesium oxide) dissolution rate calculated from the experimental results with respect to 1L of pure water, it was found that kS was 2.7X10 ^-4 (described below). From the above, formula 4 is shown in formula 5 below.

[ math 5]

From the

above formulas

3 and 5, the following formula 6 can be obtained.

[ math figure 6]

The target value of the dissolution rate dC/dt is represented by the following formula 7 with the aim of dissolving MgO (magnesium oxide) of M [ m.mol/L ] in the scrubber liquid during the time t.

[ math 7]

According to the

above formulas

6 and 7, the fixed surface area (S) of the alkaline agent powder reaching the target dC/dt is represented by the following formula 8.

[ math figure 8]

The dissolution rate dC/dt can be set to a target dC/dt by setting the fixed surface area (S) of the alkaline agent powder to a value equal to or larger than the value calculated by the formula 8. As a result, the hydration reaction is promoted. Thus, the time for obtaining the used scrubber liquid having the recovery purification ability (neutralization ability) can be shortened by increasing the pH of the used scrubber liquid due to MgO.

FIG. 2 is a graph showing experimental values of the rate of increase of pH based on the MgO concentration. The horizontal axis represents elapsed time. The vertical axis represents the hydrogen ion index (pH). In this experimental example, water was used as the scrubber liquid. The pH of the scrubber liquid was about 6, and as a result of absorbing 2mmol/L of sulfur component (SOx), the pH was lowered to about 3. As described above, the pH of the scrubber liquid, in which the purification performance of the exhaust gas 100 was lowered, was reduced, and the time required for the pH of the scrubber liquid to return to the original level when MgO of concentration a was added and MgO of concentration 2A (2 times the concentration a) was added was compared. According to the present experiment, it was shown that the time until the pH of the scrubber liquid was recovered to the original level and the purification ability of the exhaust gas 100 was recovered was reduced to 1/2 or less by increasing the MgO concentration by 2 times.

When the operation mode is switched to the closed-loop operation, the charging unit 40 may charge magnesium oxide, which is larger in amount than the amount of neutralization reaction with the amount of sulfur component absorbed by the scrubber liquid in one cycle, into the storage unit 30 at the first timing t1 in the closed-loop operation. The amount larger than the amount capable of undergoing the neutralization reaction may be an amount of 2 times or more and 400 times or less the amount capable of undergoing the neutralization reaction with the sulfur component amount. The first timing t1 may be at the start of an operation in a closed-loop operation.

By adding such magnesium oxide (MgO) in excess, the solid surface area is increased, and thus the magnesium oxide (MgO) to Mg (OH) can be promoted ₂ Hydration reaction of (magnesium hydroxide). Therefore, by excessively adding magnesium oxide (MgO) to the storage unit 30, the time required for the pH of the scrubber liquid to return to the original level and the purification performance of the exhaust gas 100 to return can be shortened.

Fig. 3 is a graph showing an example of experimental values of reaction rate constants. In FIG. 3, the horizontal axis represents the elapsed time(s), and the vertical axis represents In (Cs/(Cs-C)). From the experimental result of the dissolution rate of 2mmol MgO relative to 1L (liter) of pure water shown in FIG. 3, the product of the reaction rate constant k and the solid surface area S, kS, was calculated to obtain kS=2.7X10 ^-4 (s ^-1 ). In additionThe presence of H in the scrubber liquid ₂ SO ₃ (sulfurous acid), dissolved Mg (OH) ₂ (magnesium hydroxide) is immediately consumed by the neutralization reaction. Therefore, c=0 can be set in the reaction rate formula (formula 1), so that the dissolution rate becomes dC/dt=ks×cs.

In order to achieve the same pH as the seawater, the target value of the pH of the scrubber liquid was set to 8.1. The retention time in the reservoir 30 was set to 120 seconds, and the concentration of the sulfur component absorbed by the scrubber liquid in one cycle was set to 2mmol/L. The dissolution rate dC/dt=ks×cs was calculated from these conditions. Values of 2.7X10 using kS ^-4 (s ^-1 ) When the concentration of magnesium oxide which can be neutralized with the concentration of 2mmol/L sulfur component absorbed by the scrubber liquid in one cycle is Cs, the dissolution rate dC/dt is 4.27X10 ^-8 (mol/L/s). On the other hand, the target value of the dissolution rate dC/dt was 0.002 mol/L/120(s) =1.67×10 with the objective of dissolving 2mmol/L of MgO in 120 seconds ^-5 (mol/L/s)。

Although it is also affected by the target pH value or the like, the charging unit 40 may charge magnesium oxide into the storage unit 30 in an amount larger than the amount of neutralization reaction with the amount of sulfur component absorbed by the scrubber liquid in one cycle, before starting the supply of the used scrubber liquid from the storage unit 30 to the reaction column 10. The magnesium oxide in an amount larger than the amount capable of neutralizing the amount of the sulfur component absorbed by the scrubber liquid in one cycle may be 2 times or more and 400 times or less the amount capable of neutralizing the amount of the sulfur component absorbed by the scrubber liquid in one cycle, or may be 100 times or more and 400 times or less the amount, and more preferably 300 times or more and 400 times or less the amount.

Fig. 4 is a diagram illustrating a schematic configuration of the exhaust gas treatment device 2 of the comparative example. In the exhaust gas treatment device 2 of the comparative example, the charging section 60 charges magnesium oxide (MgO) into the dispensing section 62 and the storage section 64 located outside the circulation path of the reaction tower 10, the used scrubber piping 16, the circulation pipe 19, the storage section 30, the circulation scrubber liquid supply pipe 34, and the scrubber liquid pipe 14. The dispensing portion 62 isA tank for dissolving magnesium oxide (MgO), a storage portion 64 for dissolving magnesium oxide (MgO) and storing magnesium hydroxide Mg (OH) generated by hydration reaction ₂ Is provided. The magnesium oxide (MgO) dissolved in the dispensing portion 62 is introduced into the storage portion 64 by the pump 63. Magnesium hydroxide Mg (OH) stored in the storage portion 64 ₂ Is introduced into the circulation pipe 19 by a pump 65.

Thus, if magnesium oxide (MgO) is dissolved in a plurality of tanks other than the circulation path different from the storage unit 30, magnesium hydroxide Mg (OH) is stored ₂ (magnesium hydroxide), the hydration reaction can be sufficiently performed. Therefore, when the closed-loop operation is started, it is not necessary to charge an excessive amount of magnesium oxide before the supply of the used scrubber liquid from the storage unit 30 into the reaction column 10 is started. However, according to the comparative example, the dispensing portion 62 and the storage portion 64 are required in addition to the storage portion 30 as the buffer tank, so that space saving is difficult to achieve.

As shown in fig. 1, the exhaust gas treatment device 1 may include an adjusting portion 50, a control portion 51, a storage portion 53, and a setting portion 54. The control unit 51 performs control of the entire exhaust gas treatment device 1 of the

valves

18, 20, 32, 33, and the like. The control section 51 may be a computer.

The adjustment unit 50 adjusts the amount of magnesium oxide to be charged into the storage unit 30 before the supply of the used scrubber liquid from the storage unit 30 to the reaction column 10 is started. However, the exhaust gas treatment device 1 is not limited to the adjustment of the amount of the alkaline agent to be added, as long as the alkaline agent is added in excess during the closed-loop operation.

The setting unit 54 sets the sulfur content of the fuel oil used in the combustion device 3, the planned output value of the combustion device 3 that generates the exhaust gas 100 after the operation mode is switched to the closed-loop operation, and the like. In one example, in a closed loop action, the output of the combustion device 3 sometimes drops from 80% of nominal to 40% as the vessel sails around the port. The output schedule value may contain information about the output value of the combustion device 3 predetermined due to the course of the ship. The setting unit 54 may set the sulfur content concentration, the output planned value, and the like of the fuel oil based on the input information of the user, and may set the sulfur content concentration, the output planned value, and the like of the fuel oil based on the measurement device. The storage unit 53 may store various information set by the setting unit 54, that is, the sulfur concentration of the fuel oil and the output planned value of the combustion apparatus 3, as a database.

The adjustment unit 50 acquires information set by the setting unit 54 and stored in the storage unit 53, output information (engine load, etc.) of the combustion device 3, and information on detection values of various sensors. The adjustment unit 50 adjusts the amount of magnesium oxide, which is the alkaline agent, to be charged by the charging unit 40 based on the acquired information. The exhaust gas treatment device 1 may include a pH sensor 35, a pH sensor 36, and a sulfur component sensor 37 as various sensors. The pH sensor 35 measures the pH of the scrubber liquid (seawater) supplied to the reaction tower 10 in the open-loop operation. For example, the pH sensor 35 measures the pH of the seawater in the navigation of the ship. The pH sensor 36 measures the pH of the used scrubber liquid discharged from the reaction tower 10 to the outside. The sulfur component sensor 37 measures the amount of sulfur component of the gas released from the reaction column 10 in the open-loop operation.

The adjustment unit 50 may estimate the amount of sulfur component absorbed by the liquid in one cycle based on the output of the combustion device 3 that generates the exhaust gas 100 and the concentration of sulfur component contained in the fuel oil used by the combustion device 3, and adjust the amount of sulfur component input based on the estimated amount of sulfur component. Thus, the estimated value of the amount of the absorbed sulfur component in the liquid in one cycle is increased, and the amount of the alkaline agent to be added is increased, so that finer adjustment is possible.

The adjustment unit 50 can adjust the amount of sulfur component in the gas released from the reaction column 10 during the open-loop operation and the planned output value of the combustion device 3 that generates the off-gas 100 after the operation mode is switched to the closed-loop operation. When the amount of sulfur component in the gas released from the reaction column 10 during the ring-opening operation is large, the amount of the alkaline agent to be added can be increased to enhance the absorption of sulfur component. The lower the output schedule value is, the smaller the amount of alkaline agent to be added is.

The adjustment unit 50 can adjust the input amount according to the hydrogen ion index (pH) of each of the scrubber liquid (sea water) supplied to the reaction tower 10 during the open-loop operation and the used scrubber liquid discharged from the reaction tower 10 to the outside, and the planned output value of the combustion device 3 that generates the off-gas 100 after the operation mode is switched to the closed-loop operation. The higher the pH of the scrubber liquid (seawater) supplied to the reaction column 10 during the ring-opening operation, the smaller the amount of the alkaline agent to be added. The lower the pH of the used scrubber liquid discharged from the reaction tower 10 to the outside, the larger the amount of the alkaline agent to be charged. The adjustment unit 50 may estimate the sulfur component amount in the closed-loop operation from the information in the open-loop operation.

When the operation mode is switched from the open-loop operation to the closed-loop operation, the adjustment unit 50 may adjust the input amount based on the amount of magnesium oxide remaining in the storage unit 30 in the last closed-mode operation. When the magnesium oxide remains more in the last off mode operation, the amount of magnesium oxide newly added can be reduced.

The exhaust gas treatment device 1 may include a reservoir cleaning mechanism 38 and a pipe cleaning mechanism 39. The exhaust gas treatment device 1 is charged with an excessive amount of magnesium oxide to increase the solid surface area of the alkaline agent such as magnesium oxide, thereby promoting the hydration reaction. Therefore, magnesium hydroxide and magnesium oxide are liable to aggregate in the storage portion 30, the circulating scrubber liquid supply pipe 34, the valve 33, the pump 23 and the scrubber liquid pipe 14. The reservoir cleaning mechanism 38 may clean the reservoir 30 at the end of each closed loop action. Reservoir cleaning mechanism 38 may remove agglutinated substances from within reservoir 30. The reservoir cleaning mechanism 38 may be cleaned by injecting a cleaning liquid into the reservoir 30.

The pipe cleaning mechanism 39 can clean the circulating scrubber liquid supply pipe 34, the valve 33, the pump 23, and the scrubber liquid pipe 14 between the inlet of the scrubber liquid into the reaction tower 10 and the supply port from the storage unit 30 every time the closed-loop operation is completed.

The exhaust gas treatment device 1 configured as described above performs the following processing.

Fig. 5 is a flowchart showing an example of an exhaust gas treatment method in the exhaust gas treatment device 1. If the open-loop operation instruction is given (yes in step S10), the control unit 51 executes the open-loop operation (step S12). Specifically, the control section 51 opens the

valves

18 and 32 and closes the

valves

20 and 33.

When there is no open loop operation instruction (no in step S10) and there is no closed loop operation instruction (no in step S14), the process of the control unit 51 returns to step S10. When there is no open-loop operation instruction (no in step S10) and there is a closed-loop operation instruction (yes in step S14), the exhaust gas treatment device 1 executes the processes of steps S16 to S28.

The control section 51 opens the valve 20 and closes the valve 18. However, even if there is a closed-loop action instruction, the control section 51 maintains the valve 33 closed for a predetermined time, and maintains the valve 32 open. As a result, the storage unit 30 stores the used scrubber liquid (step S16).

The storage of the used scrubber liquid is waited for to be completed until a predetermined storage amount is reached in the storage section 30 (yes at step S18). The adjustment unit 50 can adjust the initial amount of the alkaline agent, preferably magnesium oxide, to be added (step S20). The processing of step S18 and step S20 may be performed in parallel.

The charging unit 40 charges an alkaline agent, preferably magnesium oxide, into the stored used scrubber liquid at a first timing t1 (step S22). As described above, the first timing t1 may be one timing in the closed-loop operation, or may be the start of the operation in the closed-loop operation. In particular, the input 40 inputs an alkaline agent, preferably magnesium oxide, into the stored used scrubber liquid before the used scrubber liquid is supplied to be brought into contact with the exhaust gas 100. Specifically, the input section 40 inputs an alkaline agent, preferably magnesium oxide, into the stored used scrubber liquid before the valve 33 is kept closed and the supply of the used scrubber liquid from the storage section 30 to the circulating scrubber liquid supply pipe 34 is started.

After the lapse of the predetermined time (yes in step S24), the control unit 51 closes the valve 32 and opens the valve 33. As a result, the storage unit 30 supplies the scrubber liquid, which has recovered the purification ability by the alkaline agent being introduced, to the reaction tower 10 (step S26). Scrubber liquid is supplied from the storage section 30 into the reaction column 10 via the recycle scrubber liquid supply pipe 34, the valve 33, the pump 23 and the scrubber liquid pipe 14. Thus, the scrubber liquid is contacted with the exhaust gas 100 to purify the exhaust gas 100.

The used scrubber liquid is returned to the storage section 30 via the storage section 30, the circulating scrubber liquid supply pipe 34, the scrubber liquid pipe 14, the reaction column 10, the used scrubber piping 16, and the circulating pipe 19. During the closed-loop operation, the input unit 40 may supplement the storage unit with a smaller amount of magnesium oxide than the input amount of the first timing t1 at the second timing t2 after the first timing t1 (step S28). The process of step S28 may be repeatedly performed during the duration of the closed loop action.

Fig. 6 is a flowchart showing another example of the exhaust gas treatment method in the exhaust gas treatment device 1. If the open-loop operation instruction is given (yes in step S30), the control unit 51 executes the open-loop operation (step S32). However, when a predetermined amount of the used scrubber liquid is not stored in the storage section 30 (no in step S34), the control section 51 closes the valve 18 and opens the valve 20. As a result, the storage unit 30 stores the used scrubber liquid (step S36). Waiting for a predetermined amount of used scrubber liquid to be stored in the storage section 30 (yes in step S34), the control section 51 may open the valve 18 and close the valve 20. The control unit 51 generates a closed-loop operation preparation completion signal, which is a signal indicating the preparation completion of the closed-loop operation.

In a state where the closed-loop operation preparation is completed, the control unit 51 receives a closed-loop operation instruction (step S40). If the closed-loop operation instruction is not given (no in step S40), the process returns to step S30. When the control unit 51 receives the closed-loop operation instruction (yes in step S40), the processing from step S42 to step S49 is executed. The processing of step S42 to step S49 is the same as the processing of step S20 to step S28 of fig. 5, and thus duplicate explanation is omitted.

Fig. 7 is a flowchart showing an example of the input amount adjustment process. Fig. 7 may be a subroutine of the process of step S20 of fig. 5 or step S42 of fig. 6.

The adjusting unit 50 acquires an output value of the combustion device 3, for example, an engine of a ship (step S50). The adjustment unit 50 acquires information on the sulfur content concentration contained in the fuel oil used in the combustion device 3 from the storage unit 53 (step S52). The information of the sulfur concentration contained in the fuel oil may be input in advance by the user using the setting unit 54.

The adjusting unit 50 estimates the amount of sulfur component absorbed by the scrubber liquid in one cycle based on the output value of the combustion device 3 and the concentration of sulfur component contained in the fuel oil (step S54). The amount of sulfur component absorbed by the scrubber liquid in one cycle is the amount of sulfur component absorbed when the scrubber liquid is returned to the storage section 30 via the storage section 30, the circulating scrubber liquid supply pipe 34, the scrubber liquid pipe 14, the reaction column 10, the used scrubber piping 16 and the circulation pipe 19. The adjustment unit 50 can estimate the amount of sulfur components using the flow rate of scrubber liquid per hour, the flow rate of the off-gas 100 flowing through the reaction tower 10 per unit time, and the amount of sulfur components contained in the off-gas 100.

The adjustment unit 50 estimates the amount of sulfur component absorbed by the liquid in one cycle, and adjusts the amount of magnesium oxide (alkaline agent) to be charged based on the estimated amount of sulfur component (step S56). The adjustment unit 50 adjusts the amount of magnesium oxide (alkaline agent) to be charged so as to be a predetermined multiple of the amount of neutralization reaction that can be performed with the estimated amount of sulfur component absorbed by the liquid in one cycle. The prescribed multiple may be, for example, a value determined in the range of 2 to 400 times.

Fig. 8 is a flowchart showing another example of the input amount adjustment process. Fig. 8 may be a subroutine of the process of step S20 of fig. 5 or step S42 of fig. 6.

The adjustment unit 50 acquires the amount of sulfur component of the gas released from the reaction column 10 during the ring-opening operation from the sulfur component sensor 37 (step S60). The adjustment unit 50 acquires the output planned value of the combustion device 3 that generates the exhaust gas 100 after the operation mode is switched to the closed-loop operation, from the storage unit 53 or the like. The adjustment unit 50 adjusts the amount of magnesium oxide (alkaline agent) to be charged based on the amount of sulfur component in the gas released from the reaction tower 10 during the open-loop operation and the planned output value of the combustion device 3 during the closed-loop operation (step S64).

Fig. 9 is a flowchart showing another example of the input amount adjustment process. Fig. 9 may be a subroutine of the process of step S20 of fig. 5 or step S42 of fig. 6.

The adjustment unit 50 obtains the pH of the scrubber liquid (seawater) supplied to the reaction tower 10 in the open loop operation from the pH sensor 35. The adjustment unit 50 obtains the pH of the used scrubber liquid discharged from the reaction tower 10 to the outside from the pH sensor 36 (step S72). The adjusting unit 50 acquires the output planned value of the combustion device 3 that generates the exhaust gas 100 after the operation mode is switched to the closed-loop operation from the storage unit 53 or the like (step S74).

The adjustment unit 50 adjusts the amount of magnesium oxide (alkaline agent) to be charged based on the pH of each of the scrubber liquid (sea water) supplied to the reaction tower 10 during the open-loop operation and the used scrubber liquid discharged to the outside from the reaction tower 10, and the planned output value of the combustion apparatus 3 after the operation mode is switched to the closed-loop operation (step S76).

Fig. 10 is a flowchart showing another example of the input amount adjustment process. Fig. 10 may be a subroutine of the process of step S20 of fig. 5 or step S42 of fig. 6.

The adjustment unit 50 acquires the amount of magnesium oxide (alkaline agent) remaining in the storage unit 30 in the last closing mode operation (step S80). The adjustment unit 50 can adjust the amount of magnesium oxide (alkaline agent) newly added based on the amount of magnesium oxide (alkaline agent) remaining.

The adjustment unit 50 may adjust the input amount adjustment using one or more of the input amount adjustment processes shown in fig. 7 to 10 in combination.

Fig. 11 is a flowchart showing an example of the cleaning process. The control unit 51 determines whether or not to switch from the closed-loop operation to the open-loop operation (step S90). When the closed-loop operation is switched to the open-loop operation (yes in step S90), the reservoir cleaning mechanism 38 cleans the reservoir 30 (step S92). When switching from the closed-loop operation to the open-loop operation (yes in step S90), the pipe cleaning mechanism 39 may clean the circulating scrubber liquid supply pipe 34, the valve 33, the pump 23, and the scrubber liquid pipe 14 between the inlet of the scrubber liquid into the reaction tower 10 and the supply port from the storage unit 30.

The present invention has been described above using the embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. Those skilled in the art will appreciate that various alterations and modifications can be made to the above described embodiments. It is to be understood from the description of the claims that such modifications and improvements are also included in the technical scope of the present invention.

Note that the order of execution of the respective processes such as the operations, steps, procedures, and stages in the apparatus, system, program, and method shown in the claims, the specification, and the drawings may be implemented in any order unless "before", and the like are specifically indicated, and unless the output of the previous process is used in the subsequent process. In the following claims, the description and the drawings, the "first", "then" and the like are used for convenience of description, but do not necessarily mean that the operations are performed in this order.

Description of the reference numerals

1 an exhaust gas treatment device, 2 an exhaust gas treatment device, 3 a combustion device, 10 a reaction tower, 12 a combustion gas exhaust pipe, 13 a nozzle, 14 a scrubber liquid pipe, 15 a gas discharge portion, 16 a scrubber piping, 17 a discharge pipe, 18 a valve, 19 a circulation pipe, 20 a valve, 21 a seawater discharge port, 22 a seawater introduction port, 23 a pump, 24 a seawater pipe, 30 a storage portion, 32 a valve, 33 a valve, 34 a circulation scrubber liquid supply pipe, 35 a pH sensor, 36 a pH sensor, 37 a sulfur component sensor, 38 a storage portion cleaning mechanism, 39 a piping cleaning mechanism, 40 a throw-in portion, 50 an adjustment portion, 51 a control portion, 53 a storage portion, 54 a setting portion, 60 a throw-in portion, 62 a dispensing portion, 63 a pump, 64 a storage portion, 65 a pump, 100 exhaust gas.

Claims

1. An exhaust gas treatment device, comprising a housing,

an operation mode that can be switched between a closed-loop operation for circulating a used liquid used in a process exhaust gas and an open-loop operation for discharging the used liquid to the outside, comprising:

a reaction tower supplied with the off-gas and purifying the off-gas by a liquid;

a storage unit for storing the used liquid used for purifying the exhaust gas and supplying the used liquid, the purification capacity of which is recovered by the alkaline agent in the closed-loop operation, to the reaction tower; and

and an input unit for inputting the alkaline agent into the storage unit before starting the supply of the used liquid from the storage unit into the reaction column when the closed-loop operation is started.

2. The exhaust gas treatment device according to claim 1, wherein,

the input unit inputs at least one of magnesium oxide and magnesium hydroxide as the alkaline agent into the storage unit.

3. The exhaust gas treatment device according to claim 2, wherein,

the charging section charges solid powder of at least one of the magnesium oxide and the magnesium hydroxide into the storage section as the alkaline agent.

4. The exhaust gas treatment device according to any one of claims 1 to 3, wherein the input portion inputs magnesium oxide as the alkaline agent into the storage portion.

5. The exhaust gas treatment device according to claim 4, wherein,

when the operation mode is switched to the closed-loop operation, the input unit inputs magnesium oxide into the storage unit at a first timing in the closed-loop operation, the amount of magnesium oxide being larger than an amount capable of undergoing a neutralization reaction with a sulfur component amount absorbed by the liquid in one cycle.

6. The exhaust gas treatment device according to claim 5, wherein,

during the closed-loop operation, the input unit supplements the magnesium oxide in the storage unit at a second timing subsequent to the first timing, the amount of magnesium oxide being smaller than the input amount at the first timing.

7. The exhaust gas treatment device according to any one of claims 4 to 6,

and an adjusting unit configured to adjust an amount of magnesium oxide to be added to the storage unit before starting to supply the used liquid from the storage unit to the reaction column when the operation mode is switched from the open-loop operation to the closed-loop operation.

8. The exhaust gas treatment device according to claim 7, wherein,

the adjustment unit estimates the amount of sulfur component absorbed by the liquid in one cycle based on the output of the combustion device that generates the exhaust gas and the concentration of sulfur component contained in the fuel oil used by the combustion device, and adjusts the input amount based on the estimated amount of sulfur component.

9. The exhaust gas treatment device according to claim 7, wherein,

the adjustment unit adjusts the input amount based on the amount of sulfur component in the gas discharged from the reaction tower during the open-loop operation and an output planned value of a combustion device that generates the exhaust gas after the operation mode is switched to the closed-loop operation.

10. The exhaust gas treatment device according to claim 7, wherein,

the adjustment unit adjusts the input amount based on the hydrogen ion index (pH) of each of the liquid supplied to the reaction column and the used liquid discharged from the reaction column during the open-loop operation, and an output planned value of a combustion device that generates the exhaust gas after the operation mode is switched to the closed-loop operation.

11. The exhaust gas treatment device according to claim 7, wherein,

when the operation mode is switched from the open-loop operation to the closed-loop operation, the adjustment unit adjusts the input amount based on the amount of magnesium oxide remaining in the storage unit in the last closing-mode operation.

12. The exhaust gas treatment device according to any one of claims 1 to 10, characterized in that,

the apparatus further includes a storage unit cleaning mechanism that cleans the storage unit every time the operation mode is switched from the closed-loop operation to the open-loop operation.

13. The exhaust gas treatment device according to any one of claims 1 to 12, characterized in that,

and a pipe cleaning mechanism for cleaning the inside of the pipe between the reaction tower and the storage unit when the operation mode is switched from the closed-loop operation to the open-loop operation.

14. A method for treating an exhaust gas, which comprises the steps of,

a step of storing the used liquid which has been used in the purified exhaust gas;

a step of contacting the exhaust gas with a used liquid, the purifying capacity of which is recovered by an alkaline agent in the closed-loop action; and

and a step of charging the alkaline agent into the stored used liquid before the used liquid is supplied to contact the exhaust gas when the closed-loop operation is started.