Abstract:
A method for purifying and muffling exhaust gas from an internal combustion engine, comprising the following steps: 1) allowing exhaust gas discharged by the internal combustion engine to enter into the interior of a housing ( 6 ) via an exhaust gas inlet ( 7 ) of the housing ( 6 ), wherein abrupt expansion of cross section occurs from the exhaust gas inlet ( 7 ) to the interior of the housing ( 6 ); 2) allowing scrubbing water which can absorb SO 2  to enter via a scrubbing water inlet ( 11 ), and allowing the exhaust gas in the interior of the housing and the scrubbing water to come into contact with each other, then discharging the scrubbing water via a scrubbing water outlet ( 12 ) of the housing; and 3) discharging the exhaust gas via an exhaust gas outlet ( 10 ) of the housing. The method simultaneously produces effects of purifying SO 2 , muffling and saving energy, and eliminates sparks in the exhaust gas. A device and system for purifying and muffling exhaust gas from an internal combustion engine are also provided.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a method for purifying and muffling exhaust gas from an internal combustion engine and, in particular, to a method of purifying sulfur dioxide (SO 2 ) in the exhaust gas or purifying sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ) synchronously while highly efficiently and safely decreasing the noise of the exhaust gas from the internal combustion engine. The invention also relates to a device and system for purifying and muffling exhaust gas from an internal combustion engine. The method, device and system provided by the invention are especially suitable for, but not limited to, offshore platforms such as vessels, drillings and floating factories, etc. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    Modern large and medium sized diesel engines, especially two-stroke diesel engines with poor ventilation conditions, often produce sparks from chimneys, usually called the flaming chimney. The flaming chimney effect of a diesel engine is usually caused by unburned fuel or oil-containing accumulation brought out of the chimney by high-temperature fuel gas and burned after contacting air, that is, the continuation of fuel combustion process inside the cylinder. 
         [0003]    Marine diesel engine flaming chimney will not only result in a fire but also endanger the safety of oil tankers. Most of the main propulsion engines of the modern large and medium sized tankers concerning economic globalization are two-stroke diesel engine. Thus, an endmost device at the exhaust gas passage of the engine—a muffler must have the function of extinguishing sparks. The problem is that the process and structure of the existing muffler not only has poor muffling effect, but also does not reduce the temperature of the hot fuel gas, so that sparks are not completely extinguished, which is always a security risk of the oil tanker. 
         [0004]    On the other hand, over the past 20 years, the international legislation on purification of gaseous pollutants emitted by industrial facilities, mainly as SO 2 , gradually becomes more rigorous and complete, with regulated objects expanded from the land-based industrial facilities to the sea-based vessels. International legislation on limiting the sulfur oxide emissions from an internal combustion engine such as vessels has come into effect since 2005. 
         [0005]    Since the SO 2  purification problem has been raised worldwide, a trend of valuing the seawater flue gas desulfurization technology soon prevailed. In 2007, a joint institution of four internationally renowned universities articulated a research report which clearly expressed the following idea: to realize vessel SO 2  purification by utilizing marine resources, namely seawater, has once again long been eagerly wanted but not yet actualized. The natural seawater is usually alkaline, whose pH value is generally higher than 7, so that the seawater has a natural acid-base buffering capacity and the ability of absorbing SO 2 . The technology of realizing mineral fuel sulfur oxide purification by natural seawater scrubbing is applied maturely on the land-based coal-fired power plants. 
         [0006]    For the application of seawater flue gas desulfurization technology on the vessel, one representative solution is the international application PCT/CN2008/071304 (incorporated herein by reference). The technical solution adopted by the invention is as follows: actualizing countercurrent scrubbing in the padding scrubbing layer with internal combustion engine exhaust gas and the seawater flowing from top to bottom, in order to absorb SO 2 , thus effectively solving the above problem. The applicant found that during the implementation of the invention, due to space constraints of the existing vessel structure, it is hard to implement the invention on an existing vessel. Current vessels barely have sulfur oxides cleaning device installed thereon, on one hand this is because the international legislation on limitation of internal combustion engine sulfur oxides emissions has only progressively introduced from 2005, and on the other hand, this is also due to space limitations in the existing vessels&#39; structures, so that it is almost impossible to install sulfur oxides cleaning devices that need to occupy a larger space. Seawater desulfurization process is primarily composed of a cleaner responsible for scrubbing the flue gas and a seawater processor for processing the scrubbing seawater. Both of the cleaner and seawater processor require larger space. The arrangement of the seawater processer is rather flexible, while the exhaust gas cleaner must be disposed in the exhaust passage of the internal combustion engine, and therefore a larger residual space is needed in the exhaust passage of the internal combustion engine along the way, which is a conflict to configuration of almost all offshore platforms because the internal combustion engine exhaust passage along the way happens to be the most crowded area of the space. Due to the regulations of the relevant provisions on muffling and energy saving, with the existing vessel structure, a waste heat boiler and a muffler are installed in the internal combustion engine exhaust passage. Moreover, in the position where the internal combustion engine exhaust passage is, no extra space is left for the desulphurization equipment. For future new construction of offshore platforms, leaving space for the exhaust gas cleaning device means an increase in operating costs. For those large number of underway vessels who in recent years face the difficult conditions of implementation of international legislation on purification of sulfur oxides, they do not have (and impossibly have) reserved space for installing exhaust gas cleaning device during the initial construction. However, along with progressive implementation of the international legislation on the restriction of sulfur oxide emissions from internal combustion engines such as vessels in 2005, the purification of sulfur oxides from the internal combustion engine such as that used in vessels has become unavoidable, therefore there is an urgent need to provide a purification and muffling device and method for exhaust gas from an internal combustion engine, which can be used in offshore platforms such as vessels with limited space. 
         [0007]    In addition, international legislations on the purification of nitrogen oxides (NO x ) will be gradually improved. It has been already difficult when only desulfurization equipment is added in the existing vessel structure. It would be harder to further add an apparatus for purifying NO x  in the existing technology. 
         [0008]    In sum, it can be seen that, space limitations is the constraint of applying seawater scrubbing purification process to offshore platforms such as vessels. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the difficulties of installing a purifying device on a vessel or other offshore platform, the present invention provides a new solution. The solution is to provide a device which achieves purification and muffling effects simultaneously, and the device is installed in the position where a muffler is currently located on an existing vessel. In addition, the applicant also found that the device can also save energy or recover residual heat, so it can replace the original residual heat boiler. Thus, sufficient space can be provided for the device for purifying SO 2  and oxynitride, so as to purify exhaust gas more comprehensively from the internal combustion engine. 
         [0010]    The first object of the present invention is to provide a method for purifying and muffling exhaust gas from an internal combustion engine, wherein the method can purify SO 2 , muffle noise, and save energy simultaneously, and can eliminate sparks in the exhaust gas. The method realizes the three functions of purifying SO 2 , muffling, saving energy with a single device, which can be used to replace the existing vessel mufflers and residual heat boilers. Therefore, using the method provided by the present invention, required space is provided for purifying exhaust gas from an internal combustion engine. The technical solution provided by the present invention for purifying and muffling exhaust gas from an internal combustion engine is: (a) allowing exhaust gas discharged by an internal combustion engine to enter into the interior of a housing via an exhaust gas inlet of the housing, wherein abrupt expansion of cross section occurs from the exhaust gas inlet to the interior of the housing; (b) allowing scrubbing water which can absorb SO 2  to enter via a scrubbing water inlet of the housing, and allowing the exhaust gas in the interior of the housing and the scrubbing water to come into contact with each other, then discharging the scrubbing water via a scrubbing water outlet of the housing; and (c) allowing the exhaust gas to be discharged via an exhaust gas outlet of the housing. 
         [0011]    The method for purifying and muffling exhaust gas from an internal combustion engine provided by the present application simultaneously realizes the three functions of purifying SO 2 , muffling, and residual heat recovery i.e. saving energy with a single device. First, the high-temperature exhaust gas discharged by an internal combustion engine is allowed to enter into the interior of a housing via an exhaust gas inlet of a housing, wherein abrupt expansion of cross section occurs from the exhaust gas inlet to the interior of the housing, which uses the principle of reactive muffling to achieve the muffling effect, and the rapid cooling of the high-temperature exhaust gas enhances the effect of resistive and reactive muffling; second, the exhaust gas and the scrubbing water that can absorb SO 2  in the interior of the housing are allowed to come into contact with each other to achieve the object of purifying SO 2 ; finally, the scrubbing water certainly absorbs heat from the high-temperature exhaust gas when it contacts the high-temperature exhaust gas, turns into utilizable hot water, and then is discharged via a scrubbing water outlet for utilization, thus to recover residual heat or save energy. 
         [0012]    The method for purifying and muffling exhaust gas from an internal combustion engine provided by the present application simultaneously realizes the three functions of purifying SO 2 , muffling, and saving energy with a single device. Therefore, using the method provided by the present invention, a device can be used to replace traditional muffler and residual heat boiler on an existing vessel, simultaneously achieving muffling exhaust gas from an internal combustion engine and recovering residual heat, which satisfies the relative regulation on muffling and energy saving for vessels; in the meantime, using the method provided by the present invention, on the basis of muffling internal combustion engine exhaust gas and recovering residual heat, the function of purifying SO 2  is also obtained, so as to meet the new requirements for the purification of sulfur oxides regarding vessels. 
         [0013]    Moreover, in the aspect of purification of exhaust gas from an internal combustion engine, it requires not only the purification of SO 2 , but also purification of NO x . Due to fact that the method for purifying and muffling exhaust gas from an internal combustion engine provided by the present application simultaneously realizes the three functions of purifying SO2, muffling, and recovering residual heat with a single device, the residual heat boiler can be replaced or partially replaced. Accordingly, the device for purifying NO x  can be mounted at the position where a residual heat boiler of an existing vessel is. Therefore, the method for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention may further include: at least partially eliminating the NO x  in the exhaust gas before the exhaust gas discharged from the internal combustion engine enters the housing. 
         [0014]    Since one of the technical effects of the method provided by the present invention is recovering and utilizing heat of high-temperature exhaust gas from an internal combustion engine, and therefore, the method for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention also may include: transferring the scrubbing water that has absorbed the heat from the exhaust gas to a heat utilization device or heat exchanger. 
         [0015]    The present invention also provides a device for purifying and muffling the exhaust gas from an internal combustion engine, comprising a housing provided with a scrubbing water inlet for allowing the scrubbing water to enter into the interior of the housing and a scrubbing water outlet for allowing the scrubbing water to be discharged from the housing; wherein the housing is also provided with an exhaust gas inlet for allowing exhaust gas to enter into the interior of the housing and an exhaust gas outlet for allowing the exhaust gas to be discharged from the housing, the scrubbing water inlet, the scrubbing water outlet, the exhaust gas inlet and the exhaust gas outlet are all arranged to allow the scrubbing water and the exhaust gas to come into contact in the interior of the housing, and abrupt expansion of cross section occurs from the exhaust gas inlet to the interior of the housing. 
         [0016]    Based on the above principle, the device for purifying and muffling exhaust gas from an internal combustion engine provided by the present application simultaneously realizes the three functions of purifying SO 2 , muffling, and saving energy. 
         [0017]    Further, the present invention also provide a system for purifying and muffling exhaust gas from an internal combustion engine, which comprises an internal combustion engine exhaust passage, the system also comprising a device for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention, and the device for purifying and muffling exhaust gas from an internal combustion engine is mounted in the internal combustion engine exhaust passage. Using the system for purifying and muffling exhaust gas from an internal combustion engine provided by the present application, the three functions of purifying SO 2 , muffling, and saving energy can be simultaneously realized with a single device. 
         [0018]    The system provided by the present invention may also include a denitration subsystem, such as SCR system, which is mounted in the internal combustion engine exhaust passage and located upstream of the deice for purifying and muffling exhaust gas from an internal combustion engine, so that the exhaust gas discharged from the internal combustion engine can sequentially flow through the denitration device and the device for purifying and muffling exhaust gas from an internal combustion engine provided by the invention, and ultimately can be discharged into the atmosphere. 
         [0019]    Exhaust gas from an internal combustion engine of a vessel enters the SCR device via the exhaust pipeline, thereby reducing the NO x  emission, and it then enters the device for purifying and muffling exhaust gas from an internal combustion engine provided by the present application, so as to reduce the SO 2  emission. At the same time, as previously described, using the system provided by the present invention, the functions of muffling and saving energy are also obtained. 
         [0020]    In order to utilize the scrubbing water that has absorbed the heat from the high-temperature exhaust gas, the system provided by the present invention also comprises a heat utilization device or heat exchanger, and pipelines used for transferring fluid in the housing to the heat utilization device or the heat exchanger. 
         [0021]    The method, device and system for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention can simultaneously reduce sulfur oxides and noise emissions without increasing the space for installing the cleaning device, so that they have the technical effect of breaking through the space constraints. When implemented on offshore platforms such as vessels, they can reduce the sulfur oxides in the exhaust gas from an internal combustion engine by 60 to 99% and the noise from the internal combustion engine by 20 to 30 dB. No doubt, the sparks elimination function of the present invention is far better than the existing muffler, which significantly enhances the security of the oil tanker. 
         [0022]    The present invention effectively reduces the space occupied by the entire cleaning device, realizing application of the sea scrubbing desulphurization, which is publically recognized as a green purifying process, to the limited space of offshore platforms like vessels, following the successful application of land-based coal-fired power plants. 
         [0023]    The main principle of the method or device for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention is to enable the contact between the scrubbing water which can absorb SO 2  and the exhaust gas from an internal combustion engine, so as to achieve the purpose of purifying SO 2  in the exhaust gas. 
         [0024]    Here, the scrubbing water which can absorb SO 2  may be any liquid that is capable of at least partially absorbing SO 2 , especially alkaline liquid. For vessels traveling in natural waters, such as the freshwater river/lake or seawater, freshwater or seawater from the natural environment can be easily used. Natural seawater usually is alkaline, the pH value thereof is generally greater than 7, so the water has a natural pH buffering capacity and the ability to absorb SO 2 . Therefore, the seawater used as the scrubbing water is a preferred embodiment. 
         [0025]    In order to allow the scrubbing water and the exhaust gas from an internal combustion engine to come into contact with each other inside the housing, the exhaust gas from the internal combustion engine may be allowed to enter via an exhaust gas inlet of the housing and be discharged from the exhaust gas outlet, so that an exhaust gas flow path is formed; further, the scrubbing water may be allowed to enter via the scrubbing water inlet of the housing and be discharged via the scrubbing water outlet, so that a scrubbing water flow path is formed. The exhaust gas inlet mentioned herein means any opening that enables fluid to enter into the interior of the housing. The exhaust gas inlet can be an opening directly opened on the wall of the housing, and the opening may communicate with the pipeline used for transferring fluid via a connection component. As an alternative embodiment, the housing can also be integrally formed with the transferring pipeline. As another alternative embodiment, the transferring pipeline may also extend into the interior of the housing, and then, the exhaust gas inlet means the pipeline orifice extending into the interior of the housing. The scrubbing water inlet, the scrubbing water outlet and the exhaust gas outlet can also use the various forms above-mentioned. 
         [0026]    The housing used in the present invention may be a closed housing, that is, except for the positions of the exhaust gas inlet, the exhaust gas outlet, the scrubbing water inlet and the scrubbing water outlet, the other parts are all sealed, the gas or liquid entering the housing can only pass in or out by the above-mentioned inlets and outlets. 
         [0027]    In order to achieve the object of absorbing SO 2 , in the method and device provided in the present invention, exhaust gas from the internal combustion engine and the scrubbing water are required to come into contact with each other, that is, the flow path of exhaust gas from the internal combustion engine and the flow path of the scrubbing water need overlap each other. 
         [0028]    If you want to achieve a more optimized effect of absorbing SO 2 , a preferred embodiment is to make the exhaust gas from the internal combustion engine and the scrubbing water come into contact in opposite directions, in other words, the flow direction of the exhaust gas and the flow direction of the scrubbing water are contrary or opposite, or nearly contrary or opposite. Accordingly, in a preferred embodiment, the exhaust gas from an internal combustion engine and the scrubbing water come into contact in opposite directions. In a more preferred embodiment, exhaust gas from an internal combustion engine passes through the interior of the housing from bottom to top, and the scrubbing water passes through the interior of the housing from top to bottom, so that they come into contact in opposite directions. The benefits of doing so is that, exhaust gas from an internal combustion engine can be more fully diffused in the interior of the housing, while the scrubbing water can flow completely by the effect of gravity without applying additional pressure to maintain its liquidity. Thus, the scrubbing water inlet can be arranged higher than the scrubbing water outlet in the direction of gravity, so that the scrubbing water entering the housing via the scrubbing water inlet can pass through the interior of the housing from top to down; the exhaust gas inlet is lower than the exhaust gas outlet in the direction of gravity, so that the exhaust gas entering the housing via the exhaust gas inlet passes through the interior of the housing from bottom to up. In this way, the scrubbing water and exhaust gas can come into contact more fully in opposite directions. 
         [0029]    In order to further enhance the full contact between the scrubbing water and the exhaust gas, the dispersion degree of the scrubbing water into the housing may be improved by finding some solutions. For instance, it is possible to set one or a plurality of water distributors with porous spraying components, uniformly disposed at the top of the interior of the housing. The scrubbing water is sprayed evenly to the entire interior of the housing, such that the cross section of the housing can be uniformly distributed with water. Accordingly, the present invention provides a method further comprising: dispersing the scrubbing water entering into the interior of the housing. A component such as a water distributor for dispersing the scrubbing water entering into the interior of the housing is also provided inside the housing of the device. 
         [0030]    In a more preferred embodiment, in order to prevent the scrubbing water from entering the internal combustion engine exhaust passage via the exhaust gas inlet, the scrubbing water outlet is arranged to be lower than the exhaust gas inlet in the direction of gravity, such that before the liquid surface of the scrubbing water flowing to or falling onto the bottom of the housing reaches the position of the exhaust gas inlet, the scrubbing water is discharged from the scrubbing water outlet. 
         [0031]    In addition, a water seal may be provided at the bottom of the housing, that is, to ensure the liquid surface of the scrubbing water is above the scrubbing water outlet, and below the exhaust gas inlet, so that the exhaust gas will not flow out from the scrubbing water outlet. Further, the water seal is provided to prevent the scrubbing water from entering the exhaust gas inlet, even if the inclination angles of the water seal surface in all directions reach up to 22.5°. 
         [0032]    In a more preferred embodiment, the exhaust gas inlet is located in the lower part of the side surface of the housing, the exhaust gas outlet is located at the top of the housing, and the exhaust gas outlet can be connected to the chimney to directly discharge the exhaust gas into the atmosphere; the scrubbing water inlet is located on the upper part of the side surface of the housing, the scrubbing water outlet is located in the lower part of the side surface; moreover, the scrubbing water outlet is lower than the exhaust gas inlet in the direction of gravity. In a most preferred embodiment, the exhaust gas inlet is located at the bottom of the housing, the exhaust gas outlet is located at the top of the housing, so that the exhaust gas inlet can be directly connected to the exhaust pipeline of the internal combustion engine, and the exhaust gas outlet is connected to the chimney, directly discharging the exhaust gas into the atmosphere. 
         [0033]    Generally, the exhaust gas emitted from a vessel diesel internal combustion engine has a temperature up to about 500° C., and for the effect of absorbing SO 2  by scrubbing water such as the seawater, the lower the temperature is, the higher the ratio of absorption is. Therefore, before absorbing SO 2  using the scrubbing water, reducing the temperature of the exhaust gas is helpful to improve the efficiency of the absorption of SO 2 . Accordingly, the present invention provides a method further comprising: cooling the exhaust gas by allowing the exhaust gas and the scrubbing water to come into contact with each other. In the method provided by the present invention, the scrubbing water flows from top to bottom to come into contact with the high temperature exhaust gas in opposed directions. Therefore, the scrubbing water itself can effect cooling. The device provided by the present invention further comprises a component capable of cooling the exhaust gas. The component may be the housing itself, e.g., in the housing, the scrubbing water and the high-temperature exhaust gas come into contact with each other so that the high-temperature exhaust gas is cooled. The component also may be another cooling component added in the housing, such as a spraying component additionally provided in the interior of the housing. Further, other cooling measures can also be attached to the cooling method. The high-temperature exhaust gas may be cooled before entering the interior of the housing. For example, cooling tubes or cooling fins may be installed in the exhaust passage of the internal combustion engine. The cooling tube, cooling fins, spraying component can be made of high temperature resistant material. 
         [0034]    In a preferred embodiment of the present invention, the housing of the method and device provided by the present invention is padded with padding materials that can form gaps therebetween, forming a padding layer, so as to make the scrubbing water and the exhaust gas from an internal combustion engine fully come into contact with each other to further enhance the absorption efficiency of SO 2 . The padding layer having large numbers of gaps is formed in the housing by padding the housing with padding materials which can form gaps therebetween. The padding layer enables large numbers of gaps to be formed in at least part of the space within the housing for liquid and gas to pass through. Thus, the scrubbing water and the exhaust gas must be dispersed to pass through the gap between the padding materials. In these gaps, the scrubbing water and exhaust gas can fully contact, so as to achieve the purpose of absorbing more sulfur oxides. 
         [0035]    If the housing is padded with padding materials, the lower part of the padding layer can also cool high-temperature exhaust gas. Since the scrubbing water, that is, the cooling water come into contact with the high temperature exhaust gas in the gaps between the padding materials, the temperature of the exhaust gas can be quickly reduced. Then, a large amount of SO 2  in the cooled exhaust gas is absorbed by the upper part of the padding layer. Thus, the interaction between the scrubbing water and the exhaust gas in the padding layer not only allows the exhaust gas to be cooled, but also SO 2  to be absorbed. The scrubbing water becomes acid due to the absorption of SO 2 , so that the padding material preferably is material that can withstand acidic corrosion, such as plastic, ceramic, and so on. In this case, the padding material at the lower part of the padding layer can give priority to high temperature resistance material, such as a ceramic material. The padding material located at the upper part of the padding layer is preferably a high polymer material, such as polypropylene, polyethylene, or ABS engineering plastics. The housing is also made of a material able to withstand the acidic corrosion. 
         [0036]    Another main principle of the method or device for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention is utilizing rapid cooling of high-temperature exhaust gas to enhance the effects of the resistive muffling and reactive muffling, and also to facilitate completely eliminating sparks. 
         [0037]    Based on muffling principle, mufflers can have different types such as resistive muffler, reactive muffler and impedance composite muffler. Resistive mufflers mainly use a porous sound-absorbing material to reduce the noise. When sound waves enter the resistive muffler, part of the sound energy is turned into heat to be dissipated by the friction in the pores of the porous material, so that the sound waves are weakened through the muffler. Resistive mufflers have better effect on muffling middle and high frequency noises, but poor performance in muffling low-frequency noises. Reactive mufflers are combined by tubes and chambers with abruptly changed interface by means of the sudden expansion or contraction of the pipeline cross-section, sound waves at certain frequencies propagate along the pipeline are reflected back in the mutation position toward the sound source direction, so as to achieve the purpose of muffling. Reactive mufflers are more suitable for eliminating low and middle frequency noise, and are poor in muffling the high-frequency noises. Resistive structure and reactive structure are combined in a certain way to constitute impedance composite mufflers, which have both characteristics of the above two kinds of mufflers. 
         [0038]    Following schemes for helping enhancing the muffling effect have been found to achieve good muffling effect: 1) changing the directions of gas flow by many times, 2) repeatedly making gas flow pass through the cross section which is first contracted and then enlarged, 3) dividing the gas flow into many small tributary flow to flow along many unsmooth planes, 4) cooling the gas flow. 
         [0039]    The exhaust gas discharged from an internal combustion engine is allowed to enter into the interior of the housing via an exhaust gas inlet of the housing, wherein abrupt expansion of cross section occurs from the exhaust gas inlet to the interior of the housing, so as to achieve the muffling effect. 
         [0040]    The internal combustion engine exhaust gas mentioned here are the exhaust gas discharged from an internal combustion engine without being processed by muffling, especially the exhaust gas discharged from a vessel internal combustion engine without being processed by muffling. Herein, the internal combustion engine exhaust gas mentioned here can also be the exhaust gas from an internal combustion engine with entrained sparks, especially those discharged by a vessel internal combustion engine. The exhaust gas discharged from the internal combustion engine can directly enter the housing, that is, no other mufflers are in the pipeline between the exhaust door and the housing of the internal combustion engine. After being processed by the housing, the exhaust gas discharged by the internal combustion engine can be directly discharged into the atmosphere, that is, there is no other mufflers between the exhaust outlet of the housing and the chimney outlet. The preferred embodiment is to make the exhaust gas discharged from the internal combustion engine directly enter into the housing, and directly discharged into the atmosphere after being processed by the housing. When the housing is mounted in the exhaust passage of an internal combustion engine of a vessel, it may be installed in the exhaust passage of the internal combustion engine to replace a muffler. For example, the housing is mounted in a position at a vessel where an existing muffler used to be disposed, replacing the existing muffler. 
         [0041]    Here, the method and device provided by the present invention at least utilize the principle of reactive muffling. Reactive mufflers are combined by tubes and chambers with abruptly changed interfaces, and by means of the sudden expansion or contraction of the cross sections of the pipeline, sound waves in certain frequencies propagating along the pipeline are reflected in the mutation position toward the sound source direction, so as to achieve the purpose of muffling. In the method and device provided by the present invention, abrupt expansion of cross section occurs from the exhaust gas inlet to the interior of the housing. The abrupt expansion of the cross section noted herein means utilizing the principle of reactive muffling to reduce the exhaust gas noise. 
         [0042]    If the housing is made into a regular shape, e.g. a cylindrical or other regular shape, according to the applicant&#39;s tests, the muffling effect is very significant when the cross-sectional area of the exhaust gas inlet is 0.05 to 0.5 times the cross-sectional area of the housing. Accordingly, in a preferred embodiment, the cross-sectional area of the inlet is 0.05 to 0.5 times the cross-sectional area of the housing. The applicant has also proved that when the volume of the housing is 3 to 30 times the displacement of the internal combustion engine, the muffling effect of the device is more remarkable. Therefore, in a more preferred embodiment, the volume of the housing is 3 to 30 times the displacement of the internal combustion engine. 
         [0043]    With respect to the existing mufflers, the method or device provided by the present invention may further enhance the reactive muffling effect. The principle is that, since the exhaust gas from an internal combustion engine and the scrubbing water come into contact with each other, the exhaust gas from the internal combustion engine is rapidly cooled in the housing when the scrubbing water also acts as the cooling water (for example, using seawater in the natural environment). According to the muffling principle, the cooling can further enhance the muffling effect, which is caused by significantly reducing the volume of the exhaust gas in the present invention, equivalent to increasing the expansion multiplying power of the cross sections of the exhaust passage. From another perspective, in situations where a great expansion multiplying power is required and the prior art fails to achieve it for space limitations, the method or device provided by the present invention can finely achieve the object. 
         [0044]    If the housing is padded with padding materials capable of forming gaps therebetween, the muffling effect may be further enhanced. The presence of padding material allows the device to become a resistive muffler, and part of the sound energy is converted into heat to be dissipated in the pores of the porous material by friction when the exhaust gas enters into the padding materials, so that the sound waves through the muffler are weakened. The applicant has also found that the large area of contact between the scrubbing water and the exhaust gas flow contributes to muffling. 
         [0045]    Thus, the present invention belongs to the impedance composite muffler, having both resistive and reactive muffling characteristics. Further, since the high-temperature exhaust gas of hundreds of degrees Celsius is cooled down to tens of degrees Celsius, the cooling expansion effect enhancing both resistive and reactive muffling effects simultaneously is produced. The resistive muffling of the present invention utilizes a large number of pores formed by materials such as the padding materials. Since the exhaust gas is cooled so that the volume is contracted and the flow rate is decreased, and the resistance generated by flowing through a large number of pores is decreased even more. Therefore, more padding materials can be used to constitute more, longer, more irregular pores, so that, in the present invention, the number of changes of gas flow directions, the repetition number of making gas flow pass through the cross sections which are firstly contracted and then enlarged, the number of small tributary flows obtained by dividing the gas flow, and the area for forming the unsmooth passage are all several order of magnitude higher than existing muffler technology. On the other hand, the reactive muffling of the present invention is actualized by the expansion of cross-sections formed from the exhaust gas inlet to the interior of the housing. As the volume of the exhaust gas is significantly reduced in the scheme of the present invention, which is equivalent to increasing the expansion multiplying power of the cross sections of the exhaust passage, the reactive muffling effect is further enhanced. 
         [0046]    As the cooling of exhaust gas per se can actualize the effect of muffling, the present invention also provides a second method for purifying and muffling of exhaust gas from an internal combustion engine, and the method comprises: 1) allowing exhaust gas discharged from an internal combustion engine to enter into the interior of a housing via an exhaust gas inlet of the housing; 2) allowing the scrubbing water which can absorb SO 2  to enter via a scrubbing water inlet of the housing, and allowing the exhaust gas in the interior of the housing and the scrubbing water to come into contact with each other, and then discharging the scrubbing water via a scrubbing water outlet of the housing; 3) discharging the exhaust gas via an exhaust gas outlet of the housing; further, the method also comprises cooling the exhaust gas by allowing the exhaust gas and the scrubbing water to come into contact with each other. 
         [0047]    The present invention also provides a second device for purifying and muffling exhaust gas from an internal combustion engine, and the device includes a housing provided with a scrubbing water inlet for allowing the scrubbing water to enter into the interior of the housing and a scrubbing water outlet for allowing the scrubbing water to be discharged from the housing; the housing is also provided with an exhaust gas inlet for allowing exhaust gas entering into the interior of the housing and an exhaust gas outlet for allowing the exhaust gas to be discharged from the housing, the scrubbing water inlet, the scrubbing water outlet, the exhaust gas inlet and the exhaust gas outlet are all arranged to enable the scrubbing water and the exhaust gas to come into contact in the interior of the housing. 
         [0048]    The present invention also provides a second system for purifying and muffling exhaust gas from an internal combustion engine, which includes an internal combustion engine exhaust passage, the system also comprises a second device for purifying and muffling exhaust gas from an internal combustion engine, which is mounted in the internal combustion engine exhaust passage. 
         [0049]    Since by allowing the exhaust gas from an internal combustion engine and the scrubbing water (cooling water) to come into contact with each other, sparks in the exhaust gas from an internal combustion engine of a vessel can be eliminated, the present invention also provides a method for eliminating the sparks in the exhaust gas from an internal combustion engine of a vessel, which comprises: 1) allowing exhaust gas discharged from an internal combustion engine to enter into the interior of a housing via an exhaust gas inlet of the housing, wherein abrupt expansion of cross section occurs from the exhaust gas inlet to the interior of the housing; 2) allowing the scrubbing water which can absorb SO 2  to enter via a scrubbing water inlet of the housing, and allowing the exhaust gas in the interior of the housing and the scrubbing water to come into contact with each other, and then discharging the scrubbing water via a scrubbing water outlet of the housing; discharging the exhaust gas via an exhaust gas outlet of the housing. The present invention also provides another method for eliminating the sparks in exhaust gas from an internal combustion engine of a vessel, which comprises: 1) allowing exhaust gas from an internal combustion engine to enter into the interior of a housing via an exhaust gas inlet of the housing; allowing the scrubbing water which can absorb SO 2  to enter via a scrubbing water inlet of the housing, and allowing the exhaust gas in the interior of the housing and the scrubbing water to come into contact with each other, and then discharging the scrubbing water via a scrubbing water outlet of the housing; 3) discharging the exhaust gas via an exhaust gas outlet; further, the method also comprises cooling the exhaust gas by allowing the exhaust gas and the scrubbing water to come into contact with each other. 
         [0050]    The present invention also provides another method for eliminating the sparks in exhaust gas from an internal combustion engine of a vessel, which comprises a housing provided with a scrubbing water inlet for allowing the scrubbing water to enter into the interior of the housing and a scrubbing water outlet for allowing the scrubbing water to be discharged from the housing; the housing is also provided with an exhaust gas inlet for allowing exhaust gas to enter into the interior of the housing and an exhaust gas outlet for allowing the exhaust gas to be discharged from the housing, the scrubbing water inlet, the scrubbing water outlet, the exhaust gas inlet and the exhaust gas outlet are all arranged to enable the scrubbing water and the exhaust gas to come into contact in the interior of the housing. 
         [0051]    The present invention also provides a system for eliminating the sparks in exhaust gas from an internal combustion engine of a vessel, including an internal combustion engine exhaust passage, and the system also comprises a device for purifying and muffling exhaust gas from an internal combustion engine of a vessel provided by the present invention, which is mounted in the internal combustion engine exhaust passage. 
         [0052]    Based on the principle mentioned above, the method, device and system for eliminating the sparks in exhaust gas from an internal combustion engine of a vessel provided by the present invention also simultaneously achieve the effects of purifying SO 2 , muffling and saving energy. 
         [0053]    Another major principle of the method or device for purifying and muffling exhaust gas from an internal combustion engine provided by the present invention is to achieve the object of residual heat recovery or energy saving by enabling the scrubbing water and the high-temperature exhaust gas to come into contact with each other. Here, the scrubbing water is also the cooling water. 
         [0054]    The scrubbing water, which has absorbed the heat from exhaust gas from an internal combustion engine, can be transferred to the heat utilization device for utilization. For example, in certain vessels transporting chemical raw materials, chemical raw material needs to be maintained at a certain temperature, so that the scrubbing water which has absorbed heat can be directly used. The scrubbing water, which has absorbed the heat of exhaust gas from an internal combustion engine, also can be transferred to a heat exchanger, transmitting the heat to another fluid for utilization. 
         [0055]    Accordingly, the method provided by the present invention can also include: transferring the scrubbing water that has absorbed the heat from the exhaust gas to a heat utilization device or heat exchanger. The system provided by the present invention may further include a heat utilization device or heat exchanger, and pipelines used for transferring fluid in the housing to the heat utilization device or the heat exchanger. The heat utilization device herein means a device that can directly use heat, such as the device above mentioned to maintain the chemical raw materials at a temperature. If the scrubbing water outlet communicates with the scrubbing water discharge pipe, and the heat utilization device or heat exchanger is installed in the scrubbing water discharge pipeline, then the scrubbing water discharge pipe is actually the pipeline mentioned herein that can transfer the fluid (i.e. the scrubbing water which has absorbed the heat from the high-temperature exhaust gas) in the housing to the heat utilization device or heat exchanger. 
         [0056]    The method, device and system provided by the present invention may also be designed in the form of both generating hot steam and hot water, in order to provide more varied manners for utilizing thermal energy. At this time, the high-temperature steam and low temperature hot water are sent to different heat utilization devices or heat exchangers. In this case, the scrubbing water forming the hot water is the first cooling water which is in direct contact with the high temperature exhaust gas; the cooling water producing hot steam is the second cooling water which is encapsulated in the pipeline, in indirect contact with the high temperature exhaust gas. The pipeline encapsulating the second cooling water is located below the scrubbing water inlet in the direction of gravity. If the housing is provided with padding materials, the pipeline encapsulating the second cooling water is located below the padding layer in the direction of gravity. Accordingly, the method provided by the present invention may further include: enabling the exhaust gas entering the housing to have heat exchange inside the housing with the second cooling water encapsulated in the pipeline, and transferring the hot water or steam generated in the pipeline to a second heat utilization device or second heat exchanger. 
         [0057]    The interior of the housing of the device provided by the present invention may also be provided with a cooling pipeline, and the inlet and outlet of the cooling pipeline communicate with the exterior of the housing. Thus, when in use, the second cooling water is allowed to enter into the interior of the housing via the inlet of the cooling pipeline, to have heat exchange with the high temperature exhaust gas, and the steam generated is discharged via the outlet of the cooling pipeline to be utilized. The system provided by the present invention may include a first heat utilization device or a first heat exchanger, and pipes for transferring fluid in the housing to the first heat utilization device or the first heat exchanger; further the system provided by the present invention also comprises a second heat utilization device or a second heat exchanger, and pipes for transferring fluid in the cooling pipeline to the second utilization device or the second heat exchanger. Thus, the scrubbing water that has absorbed heat from high temperature exhaust gas and the high temperature steam that is produced thereby can be utilized respectively. 
         [0058]    When the residual heat is recovered, the method, device and system provided by the present invention may also change the flow rate at the scrubbing water inlet to adjust the temperature of the generated hot water. The greater the flow rate at the scrubbing water inlet is, the greater the amount of scrubbing water entering into the interior of the housing per unit time is, and after the heat exchange takes place with the same high-temperature exhaust gas, the lower the temperature of the generated hot water is; and vice versa. Therefore, the temperature of the generated hot water can be adjusted by changing the flow rate of the scrubbing water at the scrubbing water inlet. Accordingly, the method provided by the present invention also may include: adjusting the flow rate of the scrubbing water entering into interior of the housing. The device provided by the present invention may also include a component for adjusting the influent flow rate of the scrubbing water, such as a regulating valve or speed governing pump arranged at the scrubbing water influent pipeline. 
         [0059]    If the housing is padded with padding materials that can form gaps therebetween, the scrubbing water and the exhaust gas from an internal combustion engine may come into contact more fully, so that the residual heat recovery may be more fully. 
         [0060]    If the seawater from the environment is used to perform the purification, the method provided by the present invention may further include: transferring the seawater in natural waters to the housing. The system provided by the present invention may also include a device for transferring the seawater from natural waters to the housing, such as the scrubbing water influent pipe provided with a water pump, and the scrubbing water influent pipe communicates with the scrubbing water inlet and seawater from natural waters. The system provided by the present invention may also include a device for discharging the liquid in the interior of the housing into the natural waters, such as the scrubbing water discharging pipe, which communicates with the scrubbing water outlet and seawater in natural waters. In this way, seawater from the natural environment where the vessel or other offshore platform is located can be directly drawn. Also, the seawater drawn from the natural environment may firstly be used as cooling water for the internal combustion engine, and then the cooling water for the internal combustion engine may be transferred to the device provided by the present invention for utilization. Thus, the method provided by the present invention may further comprise: transferring the seawater which has been used as cooling water for the internal combustion engine to the housing. The system provided by the present invention may also include a device for transferring the cooling water for the internal combustion engine to the housing. In addition, in order to adjust the influent flow rate of the scrubbing water, the system provided by the present invention may also include a device for adjusting the scrubbing water influent flow, such as the regulating valve or speed governing pump provided in the scrubbing water influent pipeline. To meet the requirement of being environmentally friendly, a device for increasing the pH value of the seawater which has absorbed SO 2  may be mounted in the scrubbing water discharging pipe, and increase the pH value of the seawater which has absorbed SO 2  before the seawater is discharged into the sea. 
         [0061]    The method or device for purifying and muffling exhaust gas from an internal combustion engine provided by the present application may also provide space for purification of NO x  on a vessel. 
         [0062]    The existing NO x  purification technology mainly is the SCR (Selective Catalyst Reduction) technology, namely the selective catalytic reduction technology. The SCR technology activation temperature zone generally needs to be higher than 350° C. In land-based vehicle applications, it is incorporated with a muffler to solve the space problem, whereas in other applications such as vessels, the difficulty in spatial location is very prominent; if the SCR device is incorporated with the muffler, the exhaust gas temperature is often less than 350° C. for being located in the rear of the residual heat boiler of the vessel, which is not suitable for the SCR device to work; If the SCR device is not incorporated with the muffler, there is hardly any accommodating space in the exhaust passage of the internal combustion engine. 
         [0063]    The method of the present invention is able to replace or partially replace the existing residual heat recovery process, can release or reduce the space required by the original residual heat recovery process, so that the SCR device can be located in the original position of the waste heat recovery process. In this case, the temperature of the exhaust gas at the inlet of the SCR device can be between 350° C. to 500° C., which satisfies the requirement for SCR technology activation temperature zone and facilitates NO x  purification. The design of the SCR apparatus per se belongs to the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0064]      FIG. 1  is a schematic diagram of a device for purifying and muffling exhaust gas from an internal combustion engine, according to a first embodiment of the present invention; 
           [0065]      FIG. 2  is a schematic diagram of a system for purifying and muffling exhaust gas from an internal combustion engine, according to a first embodiment of the present invention; 
           [0066]      FIG. 3  is a schematic diagram of a device for purifying and muffling exhaust gas from an internal combustion engine, according to a second embodiment of the present invention; 
           [0067]      FIG. 4  is a schematic diagram of a device for purifying and muffling exhaust gas from an internal combustion engine, according to a third embodiment of the present invention; 
           [0068]      FIG. 5  is a schematic diagram of a system for purifying and muffling exhaust gas from an internal combustion engine, according to a third embodiment of the present invention; and 
           [0069]      FIG. 6  is a schematic diagram of a device for purifying and muffling exhaust gas from an internal combustion engine, according to a fourth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0070]      FIG. 1  and  FIG. 2  show the device and system for purifying and muffling exhaust gas from an internal combustion engine according a first embodiment of the present invention. 
         [0071]    As shown in  FIG. 1 , the device for purifying and muffling exhaust gas from an internal combustion engine of the embodiment includes a housing  6  provided with a scrubbing water inlet  11  and a scrubbing water outlet  12 , wherein the scrubbing water inlet  11  is located on the upper part of the side surface of the housing and the scrubbing water outlet  12  is located on the lower part of the side surface of the housing. Under the gravity effect, the seawater entering the housing via the scrubbing water inlet  11  passes through from top to bottom and is discharged via the scrubbing water outlet  12 . 
         [0072]    The housing is also provided with an exhaust gas inlet pipe  8  and an exhaust gas outlet  10 , wherein the exhaust gas inlet pipe  8  extends into the interior of the housing, and the pipe orifice extending to the inside of the housing is an exhaust gas inlet  7 . The exhaust gas inlet  7  is located at the bottom of the housing, and the exhaust gas outlet  10  is located at the top of the housing. The exhaust gas entering the housing via the exhaust gas inlet  7  passes through in the interior of the housing from bottom to top and is discharged via the exhaust gas outlet  10 . 
         [0073]    The scrubbing water outlet  12  is located below the exhaust gas inlet  7  in the gravity direction, so that the scrubbing water flowing to or falling onto the bottom of the housing does not enter the exhaust gas inlet pipe  8  via the exhaust gas inlet  7 . 
         [0074]    The housing is further provided therein with padding materials that can form gaps therebetween so as to form a padding layer  13 . A water distributor  14  is disposed above the padding layer  13 . 
         [0075]    In addition, in order to prevent the scrubbing water from entering the exhaust gas inlet pipe  8  via the exhaust gas inlet  7 , a water baffle is provided between the exhaust gas inlet  7  and the padding layer  13 . The water baffle  16  is located over the exhaust gas inlet  7 , fully blocking the fluid coming from top to bottom in the gravity direction, so as not to allow the fluid to enter the exhaust gas inlet  7 . The edge part of the top plane of the water baffle  16  is lower than the center part thereof, so that the scrubbing water flowing to or falling onto the water baffle further flows to or falls onto the bottom the housing, thus further preventing the scrubbing water from entering the exhaust gas inlet  7 . 
         [0076]    As shown in  FIG. 1  and  FIG. 2 , in operation, the device  5  for purifying and muffling exhaust gas from an internal combustion engine according to the present embodiment is mounted in the exhaust passage of an internal combustion engine of a vessel, and the device together with the internal combustion engine exhaust passage forms a system for purifying and muffling exhaust gas from an internal combustion engine. Specifically, the device  5  for purifying and muffling exhaust gas from an internal combustion engine according to the present embodiment is mounted at the position where a muffler of an existing vessel used to be mounted, to replace the original muffler and waste heat boiler. The exhaust gas inlet pipe  8  communicates with the internal combustion engine exhaust pipe  2 . The chimney  4  communicates with the exhaust gas outlet  10 . A denitration device  3  (SCR device) is also mounted in the internal combustion engine exhaust passage of the vessel. The denitration device  3  is located upstream of the device  5  for purifying and muffling exhaust gas from an internal combustion engine. In addition, the exhaust gas purifying system of the present embodiment also includes a scrubbing water influent pipe  18 , a scrubbing water discharge pipe  19 , a water pump  20 , an adjusting valve  21 , a heat exchanger  22 , a heat utilization device  23  and an acid removal device  25 . A flow path for scrubbing water (i.e. seawater) is formed by the scrubbing water influent pipe  18 , the device  5  for purifying and muffling exhaust gas from an internal combustion engine, and the scrubbing water discharge pipe  19 . The heat exchanger  22  is mounted in the scrubbing water discharge pipe  19  and used for transmitting the heat from the high-temperature scrubbing water to another fluid and then to the heat utilization device  23  for utilization. The acid removal device  25  is mounted in the scrubbing water discharge pipe  19  and used for increasing the pH value of the scrubbing water so as to be allowable to be discharged into sea area. Here, the acid removal device  25  is the apparatus that can increase the pH value of the scrubbing water which absorbed SO 2 , and the detailed implementing method thereof is already described in the prior art. 
         [0077]    The following method can be taken to use the device and system of the present embodiment: when a vessel is travelling in the sea, the internal combustion engine does work and produces high-temperature (about 500□) exhaust gas containing SO 2  and NO x , which are discharged via the internal combustion engine exhaust pipe. NO x  is firstly removed via the denitration device, and then the exhaust gas enters the housing of the device for purifying and muffling exhaust gas from an internal combustion engine via the exhaust gas inlet pipe. The scrubbing water influent pipe draws seawater directly from natural waters where the scrubbing water influent pipe locates. The seawater is transferred into the housing via a water pump. Under the effects of the discharge pressure and natural diffusion, the exhaust gas flows through the interior of the housing from bottom to top; under the effects of gravity, the sea water flow through the interior of the housing from top to bottom. The high-temperature exhaust gas firstly comes into contact with the seawater before entering the padding layer and it is cooled thereby to some extent; then the exhaust gas enters the padding layer and it is quickly cooled down at the lower part of the padding layer; then the SO 2  in the exhaust gas is absorbed by the seawater at the upper part of the padding layer. The exhaust gas which is cooled and purified to remove SO 2  (about 30° C. after passing through the padding layer) is discharged into the atmosphere via chimney. At that moment, the low-temperature exhaust gas has no sparks at all. The seawater which has absorbed the SO 2  and heat is discharged via the scrubbing water outlet, and it flows through the heat exchanger via the scrubbing water discharge pipe. Then the pH value of the seawater is increased via the acid removal device before the seawater is discharged into the sea. Another kind of fluid that has absorbed heat in the heat exchanger is transferred to the heat utilization device for utilization. 
         [0078]    The present embodiment pertains to the impedance composite muffler, with both resistive muffling characteristic and reactive muffling characteristic. Since the high-temperature exhaust gas of hundreds of degrees Celsius is cooled down to tens of degrees Celsius, and the expansion cooling effect enhancing both of the resistive muffling effect and reactive muffling effect simultaneously is produced, effects of muffling and eliminating sparks are better than that of the muffler of prior art. 
         [0079]    An underway ton class oil tanker is installed with the system of the present invention, for purifying and muffling exhaust gas from an internal combustion engine, and the main pushing diesel engine displacement P=336 liters. According to the spatial conditions of the exhaust passage along the way, the volume of the housing is selected within the range of 3 to 30 times the displacement of the internal combustion engine. For example, according to the size of the exhaust gas inlet pipe  8  (the cross-sectional area of the exhaust gas inlet pipe is 0.3 m 2 ), the cross-sectional area of the housing is selected by 0.05 to 0.5 times, then the volume of the housing is selected as 5.3 m 3 , and the cross-sectional area is selected as 1.8 m 2 . The upper part of the padding layer is made of plastic, which adopts a plum blossom ring form, and common Pall ring form can also be used. The padding material at the lower part of the padding layer is ceramic, which adopts the saddle ring, and other common forms may also be used. The device for purifying and muffling exhaust gas from an internal combustion engine is mounted in the exhaust passage of the main diesel engine, and the exhaust passage are no longer arranged with a muffler or SO 2  scrubber, that is to say, the inlet exhaust gas of the device for purifying and muffling exhaust gas from an internal combustion engine derives from the discharged gas from the diesel engine without being specially muffled; after purification and muffling, the exhaust gas is directly discharged into the atmosphere through the chimney. The scrubbing water transferred to the device for purifying and muffling exhaust gas from an internal combustion engine is drawn from the seawater by the water pump. The amount of scrubbing water is controlled to be 20-100 m 3 /h. The discharged water of the present embodiment is discharged into the sea from the vessel after the pH value of the discharged water reaches the standards of environmental protection. 
         [0080]    After a test made by the applicant, it proved that after the above oil tanker adopts the present embodiment, the noise emitted by the vessel is reduced by 27 dB; SO 2  discharged is reduced by 99%; NO x  discharged is reduced by 80%. More importantly, the chimney flaming phenomenon is completely eliminated, and the tanker navigation safety performance is significantly improved. 
         [0081]      FIG. 3  shows the device for purifying and muffling exhaust gas from an internal combustion engine according to a second embodiment of the present invention. 
         [0082]    Different from the device for purifying and muffling exhaust gas from an internal combustion engine of the first embodiment, the exhaust gas inlet  7  of the device for purifying and muffling exhaust gas from an internal combustion engine in this embodiment is located at the lower part of the side surface of the housing  6 . In a gravity direction, the position of the exhaust gas inlet  7  is higher than the position of the scrubbing water outlet  12 . In this case, the exhaust passage of the internal combustion engine communicates with the side surface of the housing via the exhaust gas inlet pipe  8 . Since the exhaust gas enters from the side surface of the housing, a water baffle is unnecessary. The scrubbing water of the present embodiment reuses the engine cooling water. 
         [0083]    The exhaust passage of the internal combustion engine communicates with the side surface of the housing of the device. In the present embodiment, the displacement of the internal combustion engine P=33 liters, housing volume is 0.2 m 3 , the cross-sectional area is 0.3 m 2 , and the cross-sectional area of the exhaust gas inlet pipe is 0.06 m 2 . 
         [0084]      FIG. 4  and  FIG. 5  show the device and system for purifying and muffling exhaust gas from an internal combustion engine of a third embodiment of the present invention. 
         [0085]    Different from the device for purifying and muffling exhaust gas from an internal combustion engine of the first embodiment, in this embodiment, a cooling pipeline  17  is provided in the housing of the device for purifying and muffling exhaust gas from an internal combustion engine, i.e. the pipeline encapsulating the second cooling water. The cooling pipeline  17  is located below the water baffle  16 , so that the scrubbing water does not fall onto the cooling pipeline  17 , thereby producing high temperature steam. The inlet and outlet of the cooling pipeline  17  respectively extend out of the housing  6 , and the inlet is higher than the outlet in the direction of gravity. When the device is installed, the inlet and outlet are connected to the pipeline transporting fluids. As a variation of this embodiment, the inlet and outlet of the cooling pipeline  17  can also be located on the wall of housing  6 . When used, the second cooling water enters from the inlet of the cooling pipeline  17 , becomes steam after exchanging heat with high temperature exhaust gas and then is discharged from the outlet of the cooling pipeline  17  for utilization. Further, a defogger  15  is provided above the water distributor  14  and used for removing water mist entrained in the exhaust gas due to the scrubbing. 
         [0086]    As shown in  FIG. 4  and  FIG. 5 , in use, the device  5  for purifying and muffling exhaust gas from an internal combustion engine of the present embodiment is mounted in the exhaust passage of the internal combustion engine of the vessel, and the device together with the internal combustion engine exhaust passage constitutes a system for purifying and muffling exhaust gas from an internal combustion engine. In addition to the heat exchanger  22  (i.e. a first heat exchanger) and a heat utilization device  23 , the system further includes a second heat utilization device  24 , and the pipeline that can transfer the fluid in the cooling pipeline (i.e., the second cooling water) to the second heat utilization device  24 . The steam formed in the device is transferred to the second heat utilization device  24  for direct utilization. 
         [0087]      FIG. 6  shows the device for purifying and muffling exhaust gas from an internal combustion engine of a fourth embodiment of the present invention. 
         [0088]    Different from the device for purifying and muffling exhaust gas from an internal combustion engine of the third embodiment, a second exhaust gas inlet  9  is also provided in the interior of the housing of the device for purifying and muffling exhaust gas from an internal combustion engine. The second exhaust gas inlet  9  is higher than the scrubbing water outlet  12  in the direction of gravity. The cooling pipeline  17  is located between the exhaust gas inlet  7  and the second exhaust gas inlet  9 .