A scrubber for removing hazardous particles from and regulating temperature of an exhaust gas

Abstract

A scrubber (100) for removing hazardous particles from and regulating temperature of an exhaust gas, the scrubber (100) comprising a scrubbing medium (101) for removing the hazardous particles from the exhaust gas while they are in contact with each other; a plurality of nozzles (102) for directing and spraying the scrubbing medium (101) towards the exhaust gas; and a heat exchanging unit (103) configured to regulate the scrubbing medium (101) at a predetermined temperature such that the exhaust gas is in contact with a temperature regulated scrubbing medium (101).

Description

[0001]

[0002] A SCRUBBER FOR REMOVING HAZARDOUS PARTICLES FROM AND

[0003] REGULATING TEMPERATURE OF AN EXHAUST GAS

[0004] FIELD OF INVENTION

[0005] The invention relates to the field of waste treatment. More particularly, the invention relates to a scrubber.

[0006] BACKGROUND OF THE INVENTION

[0007] Solid waste management refers to a discipline that is associated with control of generation, storage, collection, transport, and processing of solid waste materials, with an objective to minimize adverse impacts of the solid waste materials on public health and environment. Therefore, thermal decomposition process such as pyrolysis emerged as solution of solid waste management. However, exhaust gas released from the thermal decomposition process of the solid waste materials contains harmful substances such as carbon monoxide, carbon dioxide, hydrocarbons, heavy metals, dioxins, furans, and particulate matter. These harmful substances may not be completely removed from the exhaust gas when released to the environment.

[0008] Over the years, various scrubbers have been developed to minimize the content of these harmful substances in the exhaust gas. For instance, China Utility Model No. CN206799551U discloses a combustible gas purification device for purifying combustible gas generated from pyrolysis of rice husk. The combustible gas purification device generally comprises a cooling tower and a deodorisation tank. The cooling tower comprises a first set of sprinkler heads and a cooling fan for cooling and purifying the combustible gas. Water is sprinkled from the first set of sprinkler head to remove impurities in the combustible gas, in which the water and the removed impurities in the cooling tower are collected in a first purification tank. On the other hand, the deodorisation tank is in fluid communication with the cooling tower for further cooling and purifying the combustible gas received from the cooling tower. Particularly, the deodorisation tank comprises a plurality of alternatively arranged baffles and a second set of sprinkler heads. The baffles form a flow path in the deodorisation tank, whereas the second set of sprinkler heads sprinkles water to purify the combustible gas as the combustible gas travels along the flow path. The water and the impurities in the deodorisation tank are collected in a second purification tank.

[0009] However, the water is not cooled prior to circulation back into the cooling tower and the deodorisation tank. This may result in gradual increase in temperature of the water in the purification tanks due to continuous release of the combustible gas throughout the pyrolysis process. Consequently, this gradually reduces efficiency of the cooling tower and the deodorisation tank in cooling and purifying the combustible gas. Accordingly, it would be desirable to provide a scrubber that overcomes the abovementioned problem. This invention provides a solution to the problem.

[0010] SUMMARY OF INVENTION

[0011] One objective of the invention is to provide a scrubber for removing hazardous particles from and regulating temperature of an exhaust gas with improved efficiency. Particularly, the scrubber comprises a heat exchanging unit that regulates scrubbing medium at a predetermined temperature.

[0012] In a first aspect of the invention, there is provided a scrubber for removing hazardous particles from and regulating temperature of an exhaust gas, the scrubber comprising: a scrubbing medium for removing the hazardous particles from the exhaust gas while they are in contact with each other; a plurality of nozzles for directing and spraying the scrubbing medium towards the exhaust gas; and a heat exchanging unit configured to regulate the scrubbing medium at a predetermined temperature such that the exhaust gas is in contact with a temperature regulated scrubbing medium.

[0013] Preferably, the heat exchanging unit regulates the scrubbing medium at the predetermined temperature by removing heat from the scrubbing medium.

[0014] Preferably, the heat exchanging unit is in the form of at least one tube having at least one portion that is in contact with the scrubbing medium to allow heat exchange between the scrubbing medium and a refrigerant that flows within the tube.

[0015] Preferably, the heat exchanging unit is in fluid communication with a refrigerant reservoir for receiving the refrigerant therefrom.

[0016] Preferably, the scrubber further comprises a plurality of baffles configured to lengthen a travelling pathway of the exhaust gas within the scrubber.

[0017] Preferably, the scrubber further comprises a first filtration unit in fluid communication with an inlet of the scrubber for separating the hazardous particles from the exhaust gas.

[0018] Preferably, the scrubber further comprises a second filtration unit in fluid communication with an outlet of the scrubber for separating residual hazardous particles from the exhaust gas.

[0019] Preferably, the scrubber further comprises a suction fan in fluid communication with the outlet of the scrubber for removing the exhaust gas from the scrubber.

[0020] Preferably, the scrubber further comprises a blower fan in fluid communication with the outlet of the scrubber for facilitating discharge of the exhaust gas from the scrubber.

[0021] In a second aspect of the invention, there is provided a thermal decomposition system comprising a thermal decomposition reactor for decomposing waste materials while forming an exhaust gas; a cooling unit in fluid communication with the thermal decomposition reactor for cooling the exhaust gas; and a scrubber in fluid communication with the cooling unit for removing hazardous particles from and regulating temperature of the exhaust gas, wherein the scrubber comprises a scrubbing medium for removing the hazardous particles from the exhaust gas while they are in contact with each other; a plurality of nozzles for directing and spraying the scrubbing medium towards the exhaust gas; and a heat exchanging unit configured to regulate the scrubbing medium at a predetermined temperature such that the exhaust gas is in contact with a temperature regulated scrubbing medium.

[0022] Preferably, the thermal decomposition system further comprises a second scrubber in fluid communication between the cooling unit and the scrubber for removing the hazardous particles from the exhaust gas.

[0023] Preferably, the thermal decomposition system further comprises a temperature regulating circuit in fluid communication between the cooling unit and the heat exchanging unit configured to regulate temperature of a refrigerant that is circulating between the cooling unit and the heat exchanging unit in a loop for respectively cooling the exhaust gas and regulating the temperature of the scrubbing medium, the arrangement being such that the temperature of the refrigerant is regulated by the temperature regulating circuit before entering the cooling unit and the heat exchanging unit.

[0024] Preferably, the temperature regulating circuit is further in fluid communication with the second scrubber such that the refrigerant is circulated to the second scrubber for regulating the temperature of the scrubbing medium therein.

[0025] Preferably, the temperature regulating circuit comprises an evaporator, a compressor, and a condenser.

[0026] One skilled in the art will readily appreciate that the invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments described herein are not intended as limitations on the scope of the invention.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] For the purpose of facilitating an understanding of the invention, there is illustrated in the accompanying drawing the preferred embodiments from an inspection of which when considered in connection with the following description, the invention, its construction and operation and many of its advantages would be readily understood and appreciated.

[0029] Fig. 1 is a schematic diagram illustrating a left side view of a scrubber.

[0030] Fig. 2 is a schematic diagram a right side view of the scrubber.

[0031] Fig. 3 is a schematic diagram illustrating a left side view of a thermal decomposition system.

[0032] Fig. 4 is a schematic diagram illustrating a right side view of the thermal decomposition system.

[0033] DETAILED DESCRIPTION OF THE INVENTION

[0034] The invention will now be described in greater detail, by way of example, with reference to the drawings.

[0035] Figs. 1 and 2 illustrate schematic diagrams of a preferred embodiment of a scrubber

[0036] (100) for removing hazardous particles from and regulating temperature of an exhaust gas produced from a pyrolysis process. The pyrolysis process decomposes waste materials such as scheduled waste and medical waste. In the preferred embodiment of the invention, the scrubber (100) generally comprises a scrubbing medium (101), a plurality of nozzles (102), and a heat exchanging unit (103).

[0037] The scrubbing medium (101) removes hazardous particles from the exhaust gas when the scrubbing medium (101) is brought into contact with the exhaust gas in the scrubber

[0038] (100). Preferably, a liquid holding section is disposed in the scrubber (100) for containing the scrubbing medium (101). By way of example, the scrubbing medium

[0039] (101) can be water. Alternatively, the scrubbing medium (101) can be a formulated solution.

[0040] The plurality of nozzles (102) are preferably in fluid communication with the liquid holding section for directing and spraying the scrubbing medium (101) towards the exhaust gas. Preferably, four nozzles (102) are arranged in the scrubber. The nozzles

[0041] (102) preferably directs and spray the scrubbing medium (101) continuously in the form of mist for removing hazardous particles from and regulating temperature of the exhaust gas. Advantageously, this improves surface area to volume ratio of the scrubbing medium (101), thereby improving the efficiency of removing hazardous particles from the exhaust gas. Upon contacting, the temperature of the exhaust gas is reduced to about 30°C, whereas the directed and sprayed scrubbing medium (101) settles back into the liquid holding section.

[0042] In the preferred embodiment of the invention, the heat exchanging unit (103) is configured to regulate the scrubbing medium (101) at a predetermined temperature. Preferably, the predetermined temperature is about 23°C to 25°C. Advantageously, this ensures that the exhaust gas is constantly is contact with a temperature regulated scrubbing medium (101), thereby improving efficiency in removing hazardous particles from and regulating temperature of the exhaust gas. Preferably, the heat exchanging unit (103) regulates the scrubbing medium (101) at the predetermined temperature by removing heat from the scrubbing medium (101).

[0043] Preferably, the heat exchanging unit (103) is in the form of at least one tube (104) having at least one portion that is in contact with the scrubbing medium (101) to allow heat exchange between the scrubbing medium (101) and a refrigerant that flows within the tube (104). Preferably, the tube (104) is submerged in the liquid holding section that contains the scrubbing medium (101) such that an outer surface of the tube (104) is in contact with the scrubbing medium (101) to allow heat exchange between the scrubbing medium (101) and the refrigerant. The heat exchanging unit (103) is preferably in fluid communication with a refrigerant reservoir for receiving refrigerant therefrom. The heat exchanging unit (103) can be a single tube pass heat exchanger, in which the tube (104) is in the form of a straight tube that passes through the heat exchanging unit (103). Alternatively, the heat exchanging unit (103) can be a multiple tube pass heat exchanger, in which the tube (104) passes through the heat exchanging unit (103) in a serpentine manner.

[0044] In the preferred embodiment of the invention, the scrubber (100) further comprises a plurality of baffles configured to lengthen a travelling pathway of the exhaust gas within the scrubber (100). Particularly, the baffles are alternately arranged such that the exhaust gas travels within the scrubber (100) in a meandering manner, as illustrated in Fig. 1. Advantageously, the baffles increase retention time of the exhaust gas in the scrubber (100) for an increased exposure time to the scrubbing medium (101), thereby improving removal of hazardous particles from and temperature regulation of the exhaust gas.

[0045] The scrubber (100) further comprises a first filtration unit (106), a blower fan (108), a second filtration unit (109), and a suction fan (111). Preferably, the first filtration unit (106) is in fluid communication with an inlet (107) of the scrubber (100) for separating the hazardous particles from the incoming exhaust gas. The first filtration unit (106) preferably comprises at least one layer of vapour filter. Additionally, the second filtration unit (109) is in fluid communication with an outlet (110) of the scrubber (100) for separating residual hazardous particles from the exhaust gas. Preferably, the second filtration unit (109) comprises at least one layer of air filter net and activated carbon filter. More preferably, the second filtration unit (109) comprises two layers of air filter net and 3 layers of activated carbon filter. The suction fan (111) is preferably in fluid communication with the outlet (110) of the scrubber (100) for removing the exhaust gas from the scrubber (100) through the second filtration unit (109). Preferably, the blower fan (108) is preferably in fluid communication with the outlet (110) of the scrubber and positioned after the suction fan (111). The blower fan facilitates discharge of the exhaust gas from the scrubber (100). Advantageously, the scrubber (100) in the present invention minimizes pollutant content and reduces temperature of the exhaust gas, thereby minimizing negative impacts to the environment.

[0046] The present invention further provides a thermal decomposition system (200) for decomposing the waste materials, as illustrated in Fig. 2. The thermal decomposition system (200) generally comprises athermal decomposition reactor (201), a cooling unit (202), and the scrubber (100). The thermal decomposition reactor (201) comprises a chamber where the waste materials are received and decomposed. During the decomposition of the waste materials, the exhaust gas are formed. Preferably, the cooling unit (202) is in fluid communication with the thermal decomposition reactor (201) for cooling the exhaust gas.

[0047] Preferably, the scrubber (100) is in communication with the cooling unit (202) for removing the hazardous particles from and regulating temperature of the exhaust gas.

[0048] Preferably, the scrubber (100) comprises the scrubbing medium (101), the nozzles (102), and the heat exchanging unit (103). The scrubbing medium (101) removes the hazardous particles from the exhaust gas while they are in contact with each other, whereas the nozzles (102) directs and spray the scrubbing medium (101) towards the exhaust gas. Additionally, the heat exchanging unit (103) is configured to regulate the scrubbing medium (101) at the predetermined temperature such that the exhaust gas is in contact with the temperature regulated scrubbing medium (101).

[0049] Referring to Figs. 3 and 4, the thermal decomposition system (200) further comprises a second scrubber (203) in fluid communication between the cooling unit (202) and the scrubber (100) for removing the hazardous particles from the exhaust gas. The second scrubber (203) preferably acts as a pre-treatment stage prior to the scrubber (100), in which majority of the hazardous particles are removed from the exhaust gas. Alternatively, the second scrubber (203) can be in fluid communication with the scrubber (100). The second scrubber (203) in this alternate embodiment preferably acts as a post-treatment stage after the scrubber (100) for removing residual hazardous particles from the exhaust gas before discharging.

[0050] The second scrubber (203) comprises another liquid holding section that contains the scrubbing medium (101) for removing the hazardous particles from the exhaust gas. Preferably, the second scrubber (203) also comprises the nozzles for directing and spraying the scrubbing medium in the form of mist towards the exhaust gas. The second scrubber (203) preferably comprises a third filtration unit (205) and a fourth filtration (207) unit in fluid communication with an inlet (206) and an outlet (208) of the second scrubber (203), respectively. The third filtration unit (205) preferably comprises at least one layer of oil filter for separating oil particles from the exhaust gas. On the other hand, the fourth filtration unit (207) preferably comprises at least one layer of vapour filter and activated carbon filter. More preferably, the fourth filtration unit (207) comprises two layers of vapour filter and three layers of activated carbon filters.

[0051] Preferably, the second scrubber (203) comprise another blower fan (209) in fluid communication with the outlet (208) of the second scrubber (203) for facilitating outflow of the exhaust gas from the second scrubber (203). Additionally, the second scrubber (203) preferably comprises a scrubbing medium filtration unit (210) in fluid communication with the liquid holding section of the second scrubber (203). The scrubbing medium filtration unit (210) filters the scrubbing medium (101) to remove the scrubbed hazardous particles from the scrubbing medium (101). Advantageously, this prevents the nozzles from being clogged by the scrubbed hazardous particles when the scrubbing medium (101) is circulated to the nozzles.

[0052] The thermal decomposition system (200) preferably further comprises a temperature regulating circuit (204), as illustrated in Fig. 2. Preferably, the temperature regulating circuit (204) is in fluid communication between the cooling unit (202) and the heat exchanging unit (103), configured to regulate temperature of the refrigerant that is circulating between the cooling unit (202) and the heat exchanging unit (103) in a loop for respectively cooling the exhaust gas and regulating the temperature of the scrubbing medium (101). Advantageously, such arrangement ensures that the temperature of the refrigerant is regulated by the temperature regulating circuit (204) before entering the cooling unit (202) and the heat exchanging unit (103), thereby maintaining the efficiencies of the cooling unit (202) and the heat exchanging unit (103). Preferably, the temperature regulating circuit (204) comprises an evaporator, a compressor, and a condenser.

[0053] In another embodiment of the thermal decomposition system (200), the temperature regulating circuit (204) is further in fluid communication with the second scrubber (203). This allows the refrigerant to be circulated to the second scrubber (203) for regulating the temperature of the scrubbing medium (101) therein. Advantageously, this improves efficiency of the second scrubber (203).

[0054] The present disclosure includes as contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangements of parts may be resorted to without departing from the scope of the invention.

Claims

CLAIMS1. A scrubber (100) for removing hazardous particles from and regulating temperature of an exhaust gas, the scrubber (100) comprising: a scrubbing medium (101) for removing the hazardous particles from the exhaust gas while they are in contact with each other; a plurality of nozzles (102) for directing and spraying the scrubbing medium (101) towards the exhaust gas; and a heat exchanging unit (103) configured to regulate the scrubbing medium (101) at a predetermined temperature such that the exhaust gas is in contact with a temperature regulated scrubbing medium (101).

2. The scrubber (100) according to claim 1, wherein the heat exchanging unit (103) regulates the scrubbing medium (101) at the predetermined temperature by removing heat from the scrubbing medium (101).

3. The scrubber (100) according to claim 1, wherein the heat exchanging unit (103) is in the form of at least one tube (104) having at least one portion that is in contact with the scrubbing medium (101) to allow heat exchange between the scrubbing medium (101) and a refrigerant that flows within the tube (104).

4. The scrubber (100) according to claim 3, wherein the heat exchanging unit (103) is in fluid communication with a refrigerant reservoir for receiving the refrigerant therefrom.

5. The scrubber (100) according to claim 1, further comprising a plurality of baffles configured to lengthen a travelling pathway of the exhaust gas within the scrubber (100).

6. The scrubber (100) according to claim 1, further comprising a first filtration unit(106) in fluid communication with an inlet (107) of the scrubber (100) for separating the hazardous particles from the exhaust gas.

7. The scrubber (100) according to claim 1, further comprising a second filtration unit(109) in fluid communication with an outlet (110) of the scrubber (100) for separating residual hazardous particles from the exhaust gas.

8. The scrubber (100) according to claim 7, further comprising a suction fan (111) in fluid communication with the outlet (110) of the scrubber (100) for removing the exhaust gas from the scrubber (100).

9. The scrubber (100) according to claim 7, further comprising a blower fan (108) in fluid communication with the outlet (110) of the scrubber (100) for facilitating discharge of the exhaust gas from the scrubber (100).

10. Athermal decomposition system (200) comprising: athermal decomposition reactor (201) for decomposing waste materials while forming an exhaust gas; a cooling unit (202) in fluid communication with the thermal decomposition reactor (201) for cooling the exhaust gas; and a scrubber (100) as claimed in claim 1, in fluid communication with the cooling unit (201) for removing hazardous particles from and regulating temperature of the exhaust gas, wherein the scrubber (100) comprises a scrubbing medium (101) for removing the hazardous particles from the exhaust gas while they are in contact with each other; a plurality of nozzles (102) for directing and spraying the scrubbing medium (101) towards the exhaust gas; and a heat exchanging unit (103) configured to regulate the scrubbing medium (101)at a predetermined temperature such that the exhaust gas is in contact with a temperature regulated scrubbing medium (101).

11. The thermal decomposition system (200) according to claim 10, further comprising a second scrubber (203) in fluid communication between the cooling unit (202) and the scrubber (100) for removing the hazardous particles from the exhaust gas.

12. The thermal decomposition system (200) according to claim 11, further comprising a temperature regulating circuit (204) in fluid communication between the cooling unit (202) and the heat exchanging unit (103) configured to regulate temperature of a refrigerant that is circulating between the cooling unit (202) and the heat exchanging unit (103) in a loop for respectively cooling the exhaust gas and regulating the temperature of the scrubbing medium (101), the arrangement being such that the temperature of the refrigerant is regulated by the temperature regulating circuit (204) before entering the cooling unit (202) and the heat exchanging unit (103).

13. The thermal decomposition system (200) according to claim 12, wherein the temperature regulating circuit (204) is further in fluid communication with the second scrubber (203) such that the refrigerant is circulated to the second scrubber (203) for regulating the temperature of the scrubbing medium (101) therein.

14. The thermal decomposition system (200) according to claim 12, wherein the temperature regulating circuit (204) comprises an evaporator, a compressor, and a condenser.

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