KR101335891B1 - Electric exhaust gas treating method and electric exhaust gas treating device - Google Patents

Abstract

It solves the problem of the exhaust gas treatment technology of the conventional diesel engine using corona discharge, and can remove PM, especially SOF in the exhaust gas of the diesel engine using the low quality fuel of heavy oil or less efficiently, The present invention provides a method and apparatus for electric treatment of diesel engine exhaust gas that can exhibit stable performance. The electric exhaust gas treatment method of a large displacement diesel engine which removes, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gases of diesel engines using low quality fuel of heavy oil or less. The gas cooling means has lowered the temperature of all the exhaust gases containing the particulate matter to 100 ° C or higher, preferably 130 ° C or higher and below the temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio R = 0.85. Thereafter, the particulate matter is removed by electrical means.

Description

ELECTRIC EXHAUST GAS TREATING METHOD AND ELECTRIC EXHAUST GAS TREATING DEVICE}

Industrial Applicability The present invention particularly relates to heavy oils such as ships, power generation, industrial, etc., which remove and purify particulate matter (Particulate Matter: hereinafter referred to as "PM") mainly containing carbon contained in exhaust gas of diesel engines. Fuel oil is used in the marine industry, diesel oil (DO), marine diesel fuel (MDF) or marine diesel oil (MDO), marine fuel oil (MFO) ), Or HFO (Heavy Fuel Oil), but here we use these notations as 'Fuel Oil'. The present invention relates to an electric treatment method and an electric treatment apparatus of exhaust gas using corona discharge in a large displacement diesel engine that discharges high temperature exhaust gas.

Although diesel engines are widely used as power sources for various ships, generators, large construction machines, and even various automobiles, PM contained in exhaust gas emitted from these diesel engines not only causes air pollution, Since the substance is very harmful to the human body, the purification of the exhaust gas is very important. For this reason, many proposals have already been made, such as improvement of the combustion method of a diesel engine, the adoption of various exhaust gas filters, and the method of electrically treating using corona discharge, and some of them have been provided for practical use.

In such an exhaust gas purification technique, a method of electrically treating by using corona discharge is to charge PM in exhaust gas by corona discharge by a discharge electrode and collect the charged PM by electrostatic force, but the discharge Since a high voltage of tens of thousands of volts is applied to the electrode and further exposed to corrosive exhaust gas, it is required to maintain stable performance for a long time. It is also important to efficiently electrostatically collect charged PM.

Here, the components of PM (particulate matter) in the exhaust gas of a diesel engine are referred to as organic solvent solubles (hereinafter referred to as "SOF") and organic solvent insolubles (hereinafter referred to as "ISF"). The SOF component is mainly composed of unburned fuel and lubricating oil, and includes harmful substances such as polycyclic aromatics having carcinogenic effects. On the other hand, the ISF powder contains carbon (tin) and sulfate (sulfate) components having low electrical resistivity as the main components, and the SOF powder and the ISF powder are very exhaust gases due to their effects on the human body and the environment. I want less. In particular, the degree of adverse influence of PM in a living body becomes a problem especially when the particle diameter becomes nm size.

Therefore, the inventors of the present invention propose an electrostatic cyclone type exhaust gas purifying apparatus (DPF: Diesel) which combines an electrostatic precipitator and a cyclone dust collector as a means for collecting and removing PM mainly composed of SOF and ISF components in the exhaust gas of a diesel engine. First referred to as Particulate Filter) (see Patent Document 1). This purifying apparatus proposes a structure which maintains the insulation performance of the discharge electrode which performs the corona discharge for a long time even at the high voltage of DC50kV which enables the collection of PM containing carbon with low electrical resistivity in electrostatic dust collection.

That is, as shown in FIG. 6, the purification apparatus includes an exhaust gas induction tube 7 protruding from the body wall 1-1 of the apparatus body into the body and the exhaust gas induction tube 7. Seal gas pipe 5 and the seal which are inserted through the outer circumferential side wall outside the main body wall 1-1, and the tip reaches near the tip opening in the exhaust gas induction pipe 7, and the seal Electrode needles which are partially spaced from the exhaust gas passage 1 by the gas pipe 5 and protrude from the front end opening of the seal gas pipe 5 toward the downstream side of the exhaust gas passage 1. (4), a collecting plate 3 disposed downstream of the exhaust gas passage 1 in the apparatus main body, and a high voltage power supply device 6 that applies a high voltage direct current voltage to the electrode needle 4; A corona room configured to emit electrons 10 by corona discharge by the electrode needle 4. A discharge charging unit including the whole 2-1 and a charging unit 2-2 for charging the emitted corona electrons 10 to particulate matter S mainly composed of carbon in the exhaust gas G1 is provided. The collecting plate 3 for collecting the charged particulate matter S is arranged in the main body wall 1-1 of the apparatus main body. The electrode needle 4 is formed of carbon having low electrical resistivity in electrostatic dust collection. In order to enable the collection of the contained PM, the structure capable of maintaining the insulation performance of the electrode needle 4 of corona discharge even when a high voltage of DC 50 kV is applied, that is, the outer peripheral portion of the electrode needle 4 as shown in FIG. Is covered with a multilayer coating layer including a first layer insulator coating 4-a, a second layer conductor coating 4-b, and a third layer insulator coating 4-c coated with an insulating material, and the tip portion thereof. 4-1 has a structure in which a predetermined length protrudes from the open end of the seal gas pipe 5, This contributes greatly to the improvement of PM collection efficiency and its maintenance and sustainability. In addition, 4-d is an earth conductor line, G2 is a sealing gas.

On the other hand, as a method of electrostatic dust collection of charged PM, the exhaust gas purification apparatus disclosed by patent document 2 is known. The exhaust gas purifier has a sticky mist when the SOF component in the exhaust gas is cooled, condensed, and liquefied, and the SOF component in the mist phase is characterized in that the superfine particles are supplemented and coagulated and enlarged according to the "sticky principle". And the electrostatic agglomeration action occur in the vicinity of the dust collecting electrode, so that the charged PM aggregates with the charged PM using the property that the electrostatic agglomeration effect is promoted when the dust collecting electrode can be cooled down (FIG. 1 of Patent Document 2). By actively cooling only the wall surface and using the liquid SOF component attached to the dust collecting electrode wall surface as a binder to electrically aggregate the components to be collected.

[Prior Art Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 2008-19849

Patent Document 2: Japanese Patent No. 4529013

However, the problem described below arises in the waste gas processing technology of the diesel engine which electrically processes PM in waste gas using a corona discharge etc.

That is, compared with automobile diesel engines using light oil with low sulfur content, such as power generation or marine engines, they have a particularly large displacement and contain a lot of sulfur with low quality of heavy oil or less (heavy oil is about 10 to 70 times higher than light oil). Sulfur content: JIS K2204 "light oil" and JIS K2205 "heavy oil") When a large displacement diesel engine using fuel, for example, the exhaust gas purifying apparatus described in Patent Document 1 described above, It is necessary to overcome the problem that sulfur in fuel is not only contained in the exhaust gas as SOF but also as a sulfate to corrode engine components, particularly exhaust components.

In addition, the technique disclosed in Patent Literature 2 for diesel engines having a low exhaust capacity mounted on automobiles using diesel fuel, which is a high-quality fuel having a small amount of sulfur, has the electrostatic agglomeration action occurring near the dust collector, so that the entire gas is cooled. Since the electrostatic coagulation effect is promoted when the dust collector can be cooled near the dust collector, it can be continuously cooled only in the dust collector and can be condensed and liquefied, charged and collected. However, low quality fuel of less than heavy oil is used. In diesel engines with high flow rate and high exhaust gas temperature or high PM emissions as a large exhaust volume for ships or the like, the part which cools to the temperature which condenses and liquidizes PM in high temperature exhaust gas is near the dust collection electrode. Limited to local cooling only in Oman lacks cooling capacity, resulting in insufficient cooling, and large supply of PM If the cooling of M does not follow, the temperature is high without cooling, and the exhaust gas containing PM is discharged. In the cooling only in the vicinity of the dust collecting electrode, the SOF component and sulfate component in the exhaust gas flowing near the dust collecting electrode are condensed and collected, but the exhaust gas flowing through the part away from the dust collecting electrode is hardly cooled. The minute does not condense condensation. Therefore, the SOF component in the exhaust gas flowing through the portion away from the dust collecting electrode is discharged without being collected. Thus, when the exhaust gas purification apparatus of patent document 2 using light oil which is a high quality fuel with a small amount of sulfur content is used for the large displacement diesel engine which uses the low quality fuel below the said heavy oil, In addition to the problem of corrosion of engine components, there is a problem that PM, particularly SOF, in the exhaust gas is not sufficiently removed.

Therefore, in view of such a problem, the present inventors solve the above problems of the exhaust gas treatment technology of a conventional diesel engine using corona discharge, and in particular, the high speed and / or large flow rate can be achieved with Proposed method and apparatus for electric treatment of diesel engine exhaust gas which can remove PM in the exhaust gas of exhaust gas, especially SOF powder and sulfate component with high efficiency and exhibit stable performance for a long time. I would like to.

The first invention of the present invention is an electric exhaust of a large displacement diesel engine that removes, by electrical means, particulate matter mainly composed of SOF powder and ISF powder contained in exhaust gas of a diesel engine using low quality fuel of heavy oil or less. In the gas treatment method, the temperature of the entire exhaust gas containing the particulate matter by the gas cooling means is 100 ° C or higher, preferably 130 ° C or higher, and the temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio (R) = 0.85. After lowering, the particulate matter is removed by electrical means.

The second invention of the present invention is an electric exhaust of a large displacement diesel engine that removes, by electrical means, particulate matter mainly composed of SOF powder and ISF powder contained in exhaust gas of a diesel engine using low quality fuel of heavy oil or less. In the gas treating method, the temperature of the entire exhaust gas is set at 100 ° C or higher, preferably 130 ° C or higher, and the exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 in an upstream portion of the exhaust gas passage in the electric exhaust gas treating apparatus. The gas cooling part which falls below the temperature shown by this is arrange | positioned, and the particulate matter contained in exhaust gas whose temperature fell when it passed through this gas cooling part is removed by electric charge and collect | recovered, It is characterized by the above-mentioned.

The third invention of the present invention is an electric exhaust of a large displacement diesel engine that removes, by electrical means, particulate matter mainly composed of SOF powder and ISF powder contained in exhaust gas of a diesel engine using low quality fuel of heavy oil or less. In the gas treating method, the temperature of the entire exhaust gas is set at 100 ° C or higher, preferably 130 ° C or higher, and the exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 in an upstream portion of the exhaust gas passage in the electric exhaust gas treating apparatus. Disposing the gas cooling unit falling below the temperature indicated by and charging the particulate matter contained in the exhaust gas whose temperature is lowered when passing through the gas cooling unit by the electrons emitted by the corona discharge and collecting it to remove it. It is characterized by.

The fourth invention of the present invention is an electric exhaust of a large displacement diesel engine that removes, by electrical means, particulate matter mainly composed of SOF powder and ISF powder contained in exhaust gas of a diesel engine using low quality fuel of heavy oil or less. In the gas treating method, the temperature of the entire exhaust gas is set at 100 ° C or higher, preferably 130 ° C or higher, and the exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 in an upstream portion of the exhaust gas passage in the electric exhaust gas treating apparatus. When the gas cooling part which falls below the temperature shown by this is arrange | positioned and the gas cooling part passes through this gas cooling part, the organic solvent soluble component which comprises a particulate matter is in the supercooled gas state represented by exhaust gas temperature / fuel boiling point temperature ratio R of 0.85 or less. One particulate matter is removed by charging and collecting by electrons emitted by corona discharge.

In the electric exhaust gas processing method of this invention, as a 5th invention, it isolate | separates and removes condensed water from the exhaust gas which passed the gas cooling part by the water separator at the downstream side of a gas cooling part as a preferable aspect.

The sixth invention of the present invention is an electrical system for a large displacement diesel engine for removing particulate matter mainly composed of SOF powder and ISF powder contained in exhaust gas of a diesel engine using low quality fuel of heavy oil or less by electrical means. In the exhaust gas treating apparatus, the temperature of the entire exhaust gas is set at 100 ° C or higher, preferably 130 ° C or higher, and the exhaust gas temperature / fuel boiling point temperature ratio R at an upstream portion of the exhaust gas passage in the processing apparatus. It has a gas cooling part which falls below the temperature shown by the following, Comprising: The discharge charging part provided with the corona discharge part which discharges an electron by a corona discharge in the middle part of an exhaust gas path, and the charging part which charges discharged corona electrons to a particulate matter, And a collecting unit for collecting particulate matter charged to a downstream portion of the exhaust gas passage, and when the exhaust gas passes through the gas cooling unit, the particulate matter. Is a super-cooling the gas phase which is an organic solvent soluble represented minutes at an exhaust gas temperature / fuel boiling point temperature ratio (R) range of 0.85 to less, characterized in that the transmitted particulate matter discharge charging part configured to remove by electrical means.

In the seventh aspect of the present invention, an electric vehicle for a large displacement diesel engine for removing particulate matter mainly composed of SOF powder and ISF powder contained in exhaust gas of a diesel engine using low quality fuel of heavy oil or less by electrical means. In the exhaust gas treating apparatus, the temperature of the entire exhaust gas is set at 100 ° C or higher, preferably 130 ° C or higher, and the exhaust gas temperature / fuel boiling point temperature ratio R at an upstream portion of the exhaust gas passage in the processing apparatus. A corona discharge portion having a gas cooling portion that is lowered to or lower than the temperature indicated by the above, and having an electrode needle covered with a multilayer structure of a film having a periphery at the midstream portion of the exhaust gas passage, and emitting electrons by corona discharge by the electrode needle; A discharge charging unit including a charging unit for charging the discharged corona electrons to the particulate matter, and collecting the charged particulate matter downstream of the exhaust gas passage. When the exhaust gas passes through the gas cooling unit, the organic solvent soluble portion of the particulate matter becomes a supercooled gas state represented by the exhaust gas temperature / fuel boiling point temperature ratio R of 0.85 or less, and is sent to the discharge electrification unit to collect the particulate matter. It is characterized in that it is set as the structure removed by an electrical means.

In the electric exhaust gas treating apparatus of the present invention, as an eighth invention, it is a preferred embodiment to provide a water separator for separating condensate from the exhaust gas passing through the gas cooling unit on the downstream side of the gas cooling unit.

Electrical treatment method and apparatus for diesel engine exhaust gas according to the present invention is a diesel engine exhaust gas purification treatment means widely used as a power source for ships, generators, large construction machinery and various automobiles, in particular for ships, power generation, industrial equipment Diesel engines with high speed and / or large flow rate exhaust gas, or low quality fuel with heavy oil content with high exhaust gas temperature. It is possible to efficiently remove harmful particulate matter PM mainly composed of ISF powder and SOF powder such as carbon and sulfate contained in exhaust gas of diesel engine, and to achieve high level of purification rate of exhaust gas. Can be.

In addition, the removal of PM contained in the exhaust gas of diesel engines using low-quality fuel of heavy oil or the like can be stably sustained with high purification rate over a long period of time, and the practical maintenance required for, for example, automobile parts, etc. Excellent effects such as can be achieved even in diesel engines.

In addition, it is possible to drastically reduce the nm-size PM particles which adversely affect the living body, and greatly contribute to the improvement of the atmospheric environment.

In addition, the electric treatment method and treatment apparatus of the exhaust gas according to the present invention can be effectively utilized not only for diesel engines but also for the purification of exhaust gas of various engines and devices using low quality fuel of heavy oil or less containing a large amount of sulfur. Of course.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the relationship between the temperature of a waste gas and a collection rate of the diesel engine in this invention.
2 is a view showing the boiling point of heavy oil fuel used in a diesel engine.
3 is a block diagram showing a first embodiment of the arrangement of the electric exhaust gas treating apparatus of the diesel engine according to the present invention.
Fig. 4 is a block diagram showing a second embodiment of the arrangement of the electric exhaust gas treating apparatus of the diesel engine according to the present invention.
It is a figure which shows the particle diameter distribution of PM particle in Example 1 of this invention.
6 is a schematic cross-sectional view showing an example of the electrostatic dust collector of the electric exhaust gas treating apparatus of a conventional diesel engine.
FIG. 7 is an enlarged cross-sectional view of the corona discharge electrode of the electric exhaust gas treatment device shown in FIG. 6.

MEANS TO SOLVE THE PROBLEM The present inventors responded to the exhaust gas processing mechanism of a diesel engine, and the electrostatic cyclone DPF apparatus shown in FIG. 6, FIG. 7 to the exhaust pipe of a diesel engine, and the exhaust gas cooling means of this invention mentioned later in order to respond | strictly restrict exhaust gas. The system for collecting PMs in the exhaust gas was variously improved, and the purification state of the exhaust gas was carefully investigated.

As a result, by installing a heat exchanger in the exhaust gas pipe and pre-cooling the entire exhaust gas, as shown in FIG. 1, the high temperature of the exhaust gas introduced into the electrostatic cyclone DPF greatly affects the PM collection rate. I noticed that. Here, PM collection rate is defined as "capture rate = 1- (PM concentration after DPF process) / (PM concentration before DPF process)". In addition, PM concentration was measured by the method based on ISO / DIS8173-1.

In addition, PM in this invention means all the substances collected on the collection filter by the method of the said ISO / DIS8173-1.

In FIG. 1, the collection rate of all PMs (SOF minutes + ISF minutes) is denoted by ηPM and the SOF fraction is denoted by ηSOF and the ISF fractions are denoted by ηISF. 1 shows that PM collection rate improves as the temperature of waste gas falls. In other words, it can be seen that as the exhaust gas cools, the collection rate of all PMs (SOF minutes + ISF minutes) increases, and the upward tendency becomes ISF minutes <PM <SOF minutes.

In particular, the component that is most affected by the temperature of the exhaust gas is SOF component, and the collection rate (ηSOF) of the SOF component is remarkably improved as the temperature of the exhaust gas is lowered. In other words, it can be seen that in the state where the temperature of the exhaust gas is high, for example, the temperature of the exhaust gas exceeding 300 ° C, high collection of SOF content becomes difficult. On the other hand, it can be seen that the influence of the temperature of the exhaust gas is relatively small with respect to the ISF fraction.

Here, regarding the temperature trend of SOF powder collection, reference literature "Nihon Marine Engineering Society Edition: 2005 Ship Emission Air Pollutant Reduction Technology Review Survey Report, Nihon Marine Engineering Society, March 2006, p58-60." And reference document "Nihon Marine Engineering Society edition: Marine engineering engineer continuation education basic course, Nihon Marine engineering society, July, 2009, p315-3170." By PM concentration measurement method that was established in JISZ8808, filter for collection in exhaust pipe Although the exhaust gas is sucked in, the exhaust gas passes through the filter as it is at a high temperature. Therefore, ISF can be collected in the PM in the exhaust gas, but SOF can not be collected by this method.

The reason why this SOF powder cannot be collected is that the temperature of the exhaust gas at the stage discharged from the diesel engine is high, and therefore most of the SOF powder is considered to be in a gaseous state. From this, the SOF component cannot be collected by a mechanical filter such as JIS collection filter or ceramic DPF which can collect solid and liquid particles but cannot collect gas.

Therefore, diesel engines with large displacements such as ships, power generation, and industrial equipment, which have a high exhaust gas temperature, a high flow rate, a high flow rate, and a low temperature drop of the exhaust gas until discharged to the outside, are conventionally used. When the exhaust gas purification device of a mechanism corresponding to the exhaust gas treatment of a small displacement diesel engine such as a car is used, the temperature of the exhaust gas immediately before being blown into the exhaust gas purification device is high, and the SOF content in the exhaust gas is in a gaseous state. It is considered that the SOF component could not be sufficiently removed.

On the other hand, the substance which can be collected also in the case of electrostatic dust collection is solid or liquid particles capable of charging corona electrons, and since the gas is not charged, electrostatic collecting cannot be performed.

Therefore, when the SOF powder is collected in the electrostatic dust collection, the SOF powder, which was a gas in the exhaust gas immediately after being discharged from the engine, is condensed from the gas state by a certain action to change into a liquid state, and the electrostatic dust collector (for example, in FIG. 6). It is thought to exist in the area | region which exists in the vicinity of the collecting plate 3 from the charging discharge part 2 shown in particular, especially the charging part 2-2.

Moreover, even if it is thought that the gas component composition of SOF powder increases as the temperature of exhaust gas increases, the collection rate of SOF powder decreases as the exhaust gas becomes high temperature, and the temperature tendency of the collection rate shown in FIG. Can understand.

Hereinafter, the collection mechanism of the SOF component and the sulfate component in the electrostatic dust collection of the present invention will be described.

Fig. 2 is a diagram showing the boiling point of heavy oil fuel which is a hydrocarbon used in a diesel engine, where the horizontal axis represents the number of carbon (C) of the hydrocarbon component contained in the fuel, and the vertical axis represents the boiling point of the component. In FIG. 2, the boiling point of each component is shown connected by the curve. In the general formula C _n H _m of the hydrocarbon corresponding to the notation of carbon number n on the abscissa, m is CnH _{2n + 2} for alkanes (chain saturated hydrocarbons), for example, depending on the chemical structure of the hydrocarbon, and carbon number n is 17 In the case of larger general heavy oil fuel, the hydrocarbon component and the polycyclic aromatic component having a relatively high boiling point contain more than diesel. In addition, carbon number n of the standard diesel oil is 14 <n <20.

Here, since the SOF component is mainly produced as unburned powder of fuel or lubricating oil, consider the boiling point of the temperature of the exhaust gas flowing into the DPF and the fuel.

At the inlet side of the DPF provided in the exhaust relationship of the diesel engine, when the temperature of the exhaust gas is higher than the boiling point of the fuel, most of the SOF fraction is in a gaseous state, and conversely, the temperature of the exhaust gas is lower than the boiling point of the fuel. In this case, the SOF component in the exhaust gas is considered to be condensed and in a liquid state, but in reality, the SOF component remains in an unstable supercooled gas state. Therefore, only mechanical collecting mechanisms such as a collecting filter and a ceramic filter can be used. The gaseous SOF powder cannot be collected.

In addition, the sulphate powder is mainly composed of oxidized sulfur content contained in the fuel, and is considered to have the same form as the SOF powder in the condensation form.

Thus, the inventors of the present invention provide a cooling device that cools the entire amount of the exhaust gas on the inlet side of the electric exhaust gas processing device, as shown in Figs. As a result of experiments varying the temperature of, the trapping rate of PM was found to be improved by lowering the temperature of the exhaust gas as shown in FIG. 1.

That is, before the exhaust gas is introduced into the discharge charging portion of the exhaust gas processing apparatus, the temperature of the entire exhaust gas is lowered to increase the cooling degree (temperature difference between the boiling point of the above components and the temperature of the exhaust gas) of the SOF component, When electrons by corona discharge are radiated to the exhaust gas in this state, the SOF powder and the sulfate powder in the gaseous state (gas phase) in the supercooled state are condensed and liquefied by the magnetic poles of the electrons. This phenomenon is thought to be similar to what is known as the Wilson chamber. When the liquefied SOF particles are charged by corona discharge, the SOF powder can be collected by electrostatic dust collection. The sulfate component is also considered to be the same. This is the mechanism of SOF powder and sulfate powder collection in the electrostatic dust collection inferred by the present inventors.

According to this mechanism, the higher the cooling degree of the SOF powder and the sulfate powder, that is, the lower the exhaust gas temperature is, the more the condensation of the SOF powder and the sulfate component is promoted, so that the collection rate of the SOF powder and the sulfate component is improved.

By lowering the temperature of the exhaust gas in this manner, the collection rates of SOF powder and sulfate powder are improved. As a method of lowering the temperature of the exhaust gas, a heat exchange device such as a recuperator established in the ship may be provided as the exhaust gas cooling device on the inlet side of the apparatus for performing electrostatic dust collection. In addition, as the other exhaust gas cooling device, a spray device of water or seawater, etc. may be provided, and the method may be applied to completely evaporate the water droplets without condensing the droplets, and to take the heat of vaporization from the exhaust gas and lower the temperature. It is necessary to pay attention because it aggregates without completely evaporating and accumulates in the electrostatic precipitator as it is in a droplet state, since it causes corrosion of the apparatus. However, the material of the apparatus can be coped with, for example, stainless steel having corrosion resistance, sulfuric acid dew point corrosion steel (for example, S-TEN1 manufactured by Nippon Steel Co., Ltd.) and the like.

Moreover, in the point which evaporates completely, without condensing a water droplet, spraying of hot water or high temperature seawater is preferable. As pointed out in the reference document "Japanese Patent Laid-Open No. 2001-132937, Paragraph 0007", this high-temperature spraying is, firstly, high temperature water, so that the droplets do not become supersaturated vapor pressure, so that the aggregation of the droplets It does not occur, it evaporates and disappears as it is, and rapid cooling of the exhaust gas becomes possible. Second, since the viscosity of the water drops to about one third at room temperature, the droplets of water droplets can be sprayed in a very fine state. There is a point. Here, the spraying of water is economically advantageous if it is a marine sailing vessel.

In addition, as a method of lowering the temperature of the exhaust gas, not only may be used a heat exchanger such as the above-mentioned recuperator, a spray device of water or seawater, but may be used in combination.

In the present invention, the reason for limiting the temperature of the entire exhaust gas discharged from the gas cooling unit and flowing into the discharge electrification unit of the gas processing device to 100 ° C or higher is that when the temperature is less than 100 ° C, moisture in the exhaust gas and the like are collected on the collecting surface. Condensed on the surface, and the PM particles deposited on the collecting surface adhere to the condensed water, making it difficult to peel off from the collecting surface, and are dispersed in a sandstorm or blizzard in the exhaust gas stream or This is because it becomes difficult to become) and subsequent processing becomes difficult. Further, in reality, when the temperature of the entire exhaust gas flowing into the discharge charging unit of the gas treatment unit discharged from the gas cooling unit is about 130 ° C., the above problem hardly occurs, which is preferable for the post-treatment of PM fine particles. For this reason, in this invention, the temperature of all the said exhaust gas becomes like this. Preferably it is 130 degreeC or more.

In addition, by installing a water separator on the upstream side of the electrostatic dust collector on the downstream side of the gas cooling unit, condensed water suspended in steam, SOF powder, sulfate powder, carbon, etc. generated by combustion from exhaust gas passing through the gas cooling unit is suspended. Since separation can be carried out in advance, the temperature of the entire exhaust gas may be cooled to about 100 ° C.

In the present invention, as an index indicating the degree of cooling of the temperature of the exhaust gas, the exhaust gas temperature / fuel boiling point temperature ratio R defined by the following formula 1 is used.

[Formula 1]

Exhaust gas temperature / fuel boiling point Temperature ratio (R) = exhaust gas temperature ÷ heavy oil fuel boiling point

In addition, although the boiling point of each component contained in the heavy oil of a diesel engine fuel etc. differs naturally, in this invention, the exhaust gas temperature / fuel boiling point temperature ratio is taken based on the component of the minimum of carbon number of the heavy oil component used, and uses the boiling point. (R) is calculated. The reason for this is that if the exhaust gas temperature / fuel boiling point temperature ratio R is determined based on the boiling point of the lower limit component of carbon number, the higher the number of carbon components, the higher the boiling point. This is because the average overcooling for the filter becomes larger, which results in an advantage in terms of PM capture.

The appropriate value of this exhaust gas temperature / fuel boiling point temperature ratio R was determined by experiments using A heavy oil as fuel using a marine diesel engine. Heptadecane C17H36 (C = 17) was used as a lower limit component of the carbon number of the heavy oil component used for the test, and exhaust gas temperature / fuel boiling point temperature ratio R was computed using the boiling point (about 300 degreeC). As a result, it is preferable that it is 0.85 or less, More preferably, it is 0.70 or less as a preferable range of the exhaust gas temperature / fuel boiling point temperature ratio R in the inlet side of the discharge electrification part which electrostatically collects. This is because most SOF and sulfate components are not liquefied when the exhaust gas temperature / fuel boiling point temperature ratio R exceeds 0.85. That is, in the exhaust gas that has passed through the gas cooling unit, the SOF powder and sulfate powder, which are the organic solvent soluble powder of the PM particles, are discharged to the discharge electrification unit in a supercooled gas state in which the exhaust gas temperature / fuel boiling point temperature ratio R is 0.85 or less. In the state where the exhaust gas temperature / fuel boiling point temperature ratio (R) exceeds 0.85, a large amount of SOF powder and sulfate powder in the gaseous state remains, and a sufficient amount of SOF powder and sulfate powder is stored in the next charging chamber. This is because it is impossible to form a condensation liquefaction and a charged supercooled gas state in all, and a satisfactory purification effect cannot be obtained.

As described above, in the present invention, the PMs in all the exhaust gases are efficiently collected by cooling the temperature of all the exhaust gases discharged from the diesel engine at the inlet side of the exhaust gas treatment apparatus to a temperature suitable for the exhaust gas treatment. Especially when the temperature of exhaust gas is higher than the boiling point of the hydrocarbon component which comprises the main component of the fuel used, the effect is further exhibited. In particular, heating or heating C heavy oil and C heavy oil having a large amount of crude oil residues used in fuels of diesel engines in which high-speed and / or high-volume exhaust gases are discharged at large and large displacements such as for ships, power generation, and industrial equipment. This results in a remarkable effect when a fuel containing a heavy oil (containing a large amount of SOF or sulfate) and a sulfur-rich fuel that is hydrogenated in a tar (pitch) are used.

Moreover, the structure of the electric exhaust gas processing apparatus of this invention is equipped with only the electrostatic true part which includes the discharge electrification part 2 and the collection plate 3 as shown in FIG. 6 at the difference of the gas cooling apparatus. One device may further include a second collecting part, for example, a cyclone dust collecting part of Patent Document 1, on the difference between the electrostatic dust collecting parts.

[Example]

Next, the present invention will be described in more detail using examples.

In order to confirm the effect of this invention, the following test was implemented applying the electric exhaust gas treating apparatus of this invention to the marine diesel engine using A heavy oil as fuel. In addition, the boiling point of the heavy oil fuel in calculation of the exhaust gas temperature / fuel boiling point temperature ratio R by [Equation 1] in the following example is a boiling point (about 300 degreeC) of heptadecane C17H36 (C = 17). Was used.

In the following example, PM collection rate was measured by the method based on ISO / DIS8173-1 first.

Subsequently, in order to investigate the collection state of the PM particles having a size of nm in the exhaust gas, a diesel particulate measuring instrument (SMPS; scanning flowable particle sizer) measuring the number of particles per unit volume having a particle diameter of 500 nm or less was used. The PM particle number of the exhaust gas immediately after it was discharged from the engine was compared with the PM particle number of the exhaust gas after treating the entire exhaust gas by the purification method of the present invention. The unit of particle number is shown by piece / cm <3>.

In addition, Examples 1-5 which are 1st Example use the apparatus of the arrangement | positioning structure shown in FIG. 3 using the electrostatic cyclone DPF apparatus provided with an electrostatic dust collector and a cyclone dust collector, and Examples 6-9 which are 2nd Example are the The apparatus of the arrangement | positioning structure shown in FIG. 4 using the electrostatic dust collector provided with the discharge charging part and the collection part was used. In each embodiment, an exhaust gas cooling apparatus including a well-known water-cooled multi-tubular heat exchanger was used for the exhaust gas cooling method.

Example 1

In this embodiment, which is the first embodiment, the entire exhaust gas from the engine is cooled by the gas cooling device using the apparatus shown in Fig. 3, the exhaust gas temperature at the inlet side of the DPF is 247 ° C, and the exhaust gas temperature is The SOF capture rate (ηSOF), PM capture rate (ηPM) and ISF capture rate (ηISF) were measured by setting the / fuel boiling point temperature ratio (R) to 0.82. The results are shown in Table 1.

In Table 1, the temperature of the exhaust gas on the inlet side of the DPF indicates the temperature of the exhaust gas cooled by the cooling apparatus of the apparatus configuration shown in FIGS. 3 and 4. In addition, the evaluation of the collection property is "◎" for PM collection rate 80% or more, SOF collection rate 70% or more, ISF collection rate 85% or more, PM collection rate 70% or more, SOF collection rate 60% or more, ISF collection rate 80% Above "○", PM collection rate 60% or more, SOF collection rate 50%, ISF collection rate 70% or more "△", PM collection rate less than 60%, SOF collection rate less than 50%, ISF collection rate less than 80% Is evaluated as "x".

In addition, in this Example, the collection state of the PM particles of nm size was measured. The result is shown in FIG. From the results shown in FIG. 5, the distribution situation (shown by the dotted line) of the peak value of the PM particles contained in the exhaust gas immediately after the discharge from the diesel engine is 1.5 × 10 ⁷ particles / cm 3. After cooling the exhaust gas in advance, the distribution state (shown by the solid line) of the PM particle number after the purification treatment is 1.7 × 10 ⁶ / cm 3, indicating that the total number of PM particles having a size of nm is greatly reduced. Can be. Since most of the PM particles having a size of nm are SOF powder and sulfate powder, it is thought that SOF powder and sulfate powder are condensed and collected in the electrostatic dust collector by lowering the exhaust gas temperature.

Example 2

In this example, the test was conducted in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 223 ° C, and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.74. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 3

The present Example was conducted in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 198 ° C and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.66. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 4

In this example, the test was conducted in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 177 ° C and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.59. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 5

In this example, the test was conducted in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 155 ° C and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.52. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 6

In this embodiment, which is the second embodiment, the exhaust gas temperature / fuel boiling point temperature ratio R is 0.80 and the exhaust gas temperature at the inlet side is 240 ° C. using the apparatus shown in FIG. 4. Was tested in the same manner as in Example 1, and the SOF collection rate (ηSOF), PM collection rate (ηPM), and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 7

The present Example was tested in the same manner as in Example 6 except that the exhaust gas temperature at the inlet side of the DPF was 200 ° C. and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.67. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 8

The present Example was tested in the same manner as in Example 6 except that the exhaust gas temperature at the inlet side of the DPF was 151 ° C, and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.50. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

Example 9

The present Example was tested in the same manner as in Example 6 except that the temperature of the exhaust gas at the inlet side of the DPF was 105 ° C, and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.35. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

(Comparative Example 1)

In this comparative example, the test was conducted in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 357 ° C, and the exhaust gas temperature / fuel boiling point temperature ratio R was 1.19. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1. This comparative example corresponds to the case where the electric purification process is performed without actually cooling the exhaust gas.

(Comparative Example 2)

In this comparative example, the test was conducted in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 300 ° C. and the exhaust gas temperature / fuel boiling point temperature ratio R was 1.00. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown in Table 1 together.

(Comparative Example 3)

This comparative example was tested in the same manner as in Example 1 except that the exhaust gas temperature at the inlet side of the DPF was 274 ° C, and the exhaust gas temperature / fuel boiling point temperature ratio R was 0.91. ηSOF), PM collection rate (ηPM) and ISF collection rate (ηISF) were measured. The results are shown together in Table 1.

[Table 1]

As is apparent from Table 1, when the exhaust gas temperature / fuel boiling point temperature ratio R is 0.85 or less, the SOF collection rate (ηSOF) is 60% or more, the PM collection rate (ηPM) is 75% or more, and the ISF collection rate ( ηISF) was able to obtain a high collection rate of 80% or more.

On the other hand, satisfactory results were not obtained in the comparative example in a state where the exhaust gas temperature was high.

This result shows that the average PM emission rate of marine diesel engines is usually about 0.6 g / kWh, and therefore the ships equipped with the electric exhaust gas treatment apparatus for large displacement diesel engines shown in the examples in which the PM collection rate (ηPM) is 75% or more. The PM discharge rate from this indicates that it is possible to set 0.6 x (1-0.75) = 0.15 g / kWh or less.

This value is the regulation value in the 2012 third regulation of the United States which already regulates PM emissions from ships (reference literature "Nihon Marine Engineering Society edition: 2007 ship discharge air pollutant reduction technology examination investigation report, See Nippon Marine Engineering Society, March 2008, p. 90.) It is less than 0.27 g / kWh and fully meets the regulation.

In addition, in the apparatus shown in FIG. 3 used in Examples 1-5, when the aggregation accumulation thickness of PM collected by the electrostatic precipitating part increases and becomes excessive, it peels as agglomeration mass of PM. The peeled PM aggregated mass is collected by a cyclone dust collector at the rear stage, collected in a dust box, and accumulated. In the apparatus shown in Fig. 4 used in Examples 6 to 9, PM collected in the electrostatic dust collector may be collected and accumulated in the dust box by mechanical vibration, scraping (brushing) mechanism or the like.

3 and 4, the condensed water can be separated and removed from the exhaust gas by providing a water separator at the downstream side of the exhaust gas cooling apparatus. By removing the condensate in advance, the sulfur-containing product or nitrogen-containing product is contained in the condensate and reduced from the exhaust gas, and the sulfur-based product or nitrogen-based product is adsorbed and reduced by ISF (tin) in PM attached to the condensate. In addition, the content of PM (SOF, ISF) and nitrogen source products in the exhaust gas can be reduced to reduce the load of the DPF and further reduce the risk of impairing the durability of engine-related components. This effect is particularly remarkable when the exhaust gas temperature discharged from the exhaust gas cooling device is around 100 ° C. In addition, in the water separator, it is not necessary to completely remove the condensate, and large particles are separated by colliding with a baffle (separating plate) to charge fine liquid particles and solid particles by a corona discharge at a later stage and to be collected by a Coulomb force. It is good to remove by adsorb | sucking in and collecting and collecting.

DESCRIPTION OF SYMBOLS 1 Exhaust gas passage, 1-1: main body wall, 2: discharge charging portion, 2-1: corona discharge portion, 2-2: charging portion, 3: collecting plate, 4: electrode needle, 4-a: first Layer insulator sheath, 4-b: second layer conductor sheath, 4-c: third layer insulator sheath, 4-d: earth conductor wire, 5: seal gas pipe, 6: high voltage power supply, 7: exhaust gas induction pipe, 8: PM, 10: corona electron, G1: exhaust gas, G2: seal gas

Claims (10)

The electric exhaust gas treatment method of a large displacement diesel engine which removes, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gases of diesel engines using low quality fuel of heavy oil or less. In
The gaseous cooling means lowers the temperature of the entire exhaust gas containing the particulate matter to 100 ° C or more and below the temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio (R) = 0.85. An electric exhaust gas treatment method for a large displacement diesel engine, characterized by the removal. The electric exhaust gas treatment method of a large displacement diesel engine which removes, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gases of diesel engines using low quality fuel of heavy oil or less. In
The gas cooling part which arrange | positions the temperature of all the exhaust gas below 100 degreeC or more and below the temperature shown by exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 is arrange | positioned in the upstream part of the exhaust gas path | route in an electric exhaust gas processing apparatus, An electric exhaust gas treatment method for a large displacement diesel engine, wherein particulate matter contained in the exhaust gas whose temperature has passed when passing through the gas cooling unit is removed by charging and collecting by electrical means. The electric exhaust gas treatment method of a large displacement diesel engine which removes, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gases of diesel engines using low quality fuel of heavy oil or less. In
The gas cooling part which arrange | positions the temperature of all the exhaust gas below 100 degreeC or more and below the temperature shown by exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 is arrange | positioned in the upstream part of the exhaust gas path | route in an electric exhaust gas processing apparatus, The particulate matter contained in the exhaust gas whose temperature is lowered when passing through the gas cooling unit is charged by the electrons emitted by the corona discharge and removed by collecting the electric exhaust gas treatment method for a large displacement diesel engine. . The electric exhaust gas treatment method of a large displacement diesel engine which removes, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gases of diesel engines using low quality fuel of heavy oil or less. In
The gas cooling part which arrange | positions the temperature of all the exhaust gas below 100 degreeC or more and below the temperature shown by exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 is arrange | positioned in the upstream part of the exhaust gas path | route in an electric exhaust gas processing apparatus, Electron emitted by corona discharge of said particulate matter which made the organic solvent soluble component which comprises particulate matter into the supercooled gas state represented by the exhaust gas temperature / fuel boiling point temperature ratio R of 0.85 or less when it passed through the gas cooling part. An electric exhaust gas treatment method for a large displacement diesel engine, characterized in that it is removed by charging with electricity by collecting. The electric exhaust gas of a large displacement diesel engine according to any one of claims 1 to 4, wherein condensed water is separated and removed from the exhaust gas passing through the gas cooling unit by a water separator on the downstream side of the gas cooling unit. Treatment method. The temperature according to any one of claims 1 to 4, wherein the temperature of the entire exhaust gas is lowered to 130 ° C or more and below a temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio (R) = 0.85. How to treat electric exhaust gas of a displacement diesel engine. Electric exhaust gas treatment apparatus for large displacement diesel engines for removing, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gas of diesel engines using low quality fuel of heavy oil or less. To
An upstream portion of the exhaust gas passage in the processing apparatus is provided with a gas cooling unit for lowering the temperature of the entire exhaust gas to 100 ° C or more and the temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 or less,
A discharge charging portion including a corona discharge portion for emitting electrons by corona discharge and a charging portion for charging the discharged corona electrons to the particulate matter in an upstream portion of the exhaust gas passage,
A collecting portion for collecting the charged particulate matter downstream of the exhaust gas passage;
When the exhaust gas passes through the gas cooling unit, the organic solvent soluble portion of the particulate matter is in a supercooled gas state represented by an exhaust gas temperature / fuel boiling point temperature ratio R of 0.85 or less, and is sent to the discharge electrification unit. An electric exhaust gas treatment apparatus for a large displacement diesel engine, characterized in that the material is removed by electrical means. Electric exhaust gas treatment apparatus for large displacement diesel engines for removing, by electrical means, particulate matter mainly composed of organic solvent insoluble components and organic solvent soluble components contained in exhaust gas of diesel engines using low quality fuel of heavy oil or less. To
An upstream portion of the exhaust gas passage in the processing apparatus is provided with a gas cooling unit for lowering the temperature of the entire exhaust gas to 100 ° C or more and the temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio R = 0.85 or less,
In the middle part of the exhaust gas passage, an electrode needle whose outer periphery is covered with a multi-layered coating is disposed, and a corona discharge portion for emitting electrons by corona discharge by the electrode needle and charged corona electrons are charged to the particulate matter. It has a discharge charging unit having a charging unit to make,
A collecting portion for collecting the charged particulate matter downstream of the exhaust gas passage;
When the exhaust gas passes through the gas cooling unit, the organic solvent soluble content of the particulate matter is in a supercooled gas state represented by an exhaust gas temperature / fuel boiling point temperature ratio R of 0.85 or less, and is sent to the discharge electrification unit, whereby the particulate matter Electrical exhaust gas treatment apparatus for a large displacement diesel engine, characterized in that the configuration to remove by the electrical means. The electric exhaust gas treatment apparatus for a large displacement diesel engine according to claim 7 or 8, wherein a water separator for separating condensate from the exhaust gas passing through the gas cooling unit on the downstream side of the gas cooling unit is provided. The large exhaust gas diesel engine according to claim 7 or 8, wherein the temperature of the entire exhaust gas is lowered to 130 ° C or more and below the temperature represented by the exhaust gas temperature / fuel boiling point temperature ratio (R) = 0.85. Electric exhaust gas treatment device.

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