CN107654276A - The processing system of ship double fuel or natural gas engine escape methane - Google Patents

Abstract

The invention provides a treatment system for escaped methane from a ship's dual-fuel or natural gas engine. It includes an oxidation catalyst connected behind the exhaust pipe of the engine, and a post-burner, which is connected to the oil tank through a separate post-burner oil pump, and the outlet of the post-burner is integrated into the engine exhaust pipe to heat the exhaust gas in the exhaust pipe. The methane-containing exhaust gas from the engine makes the exhaust gas temperature reach the temperature required for methane oxidation catalysis. The invention increases the temperature of the tail gas of the ship's dual-fuel/natural gas engine by adding a supplementary burner, and then uses an oxidation catalytic device to remove escaped methane from the dual-fuel/natural gas engine, thereby reducing environmental pollution.

Description

Treatment system for escaped methane from marine dual-fuel or natural gas engines

technical field

The invention relates to an exhaust post-treatment system for escaped methane from an engine, in particular to an exhaust post-treatment system for escaped methane from a ship's dual-fuel engine/natural gas engine.

Background technique

Marine dual-fuel/natural gas engines have many sources of fuel (CH ₄ ) and low fuel costs. Compared with traditional low-speed marine engines, NOx emissions are reduced by more than 20%, and there are almost no sulfur oxides and particulate matter emissions. They are being used on river, sea and ocean-going ships. Get more and more applications. However, HC emissions from dual-fuel/natural gas engines, especially methane (CH ₄ ) emissions from dual-fuel/natural gas engines based on the Otto cycle are relatively large, causing serious pollution to the environment.

At present, the environmental protection regulations of IMO and other countries in the world are becoming more and more stringent, and the requirements for the control of ship engine exhaust emissions are also becoming more and more stringent. How to take effective measures to reduce the emission of engine pollutants has become an important topic in the field of engine emission technology research. Hydrocarbons (HC) are the main emissions of dual-fuel/natural gas engines, mainly including methane and its derivatives (formaldehyde CH ₂ O and methanol CH ₃ OH).

Hydrocarbons emitted by marine dual-fuel/natural gas engines include unburned and incompletely burned fuels, lubricating oils and their cracking products and partial oxides, such as more than 200 kinds of methane, formaldehyde, benzene, aldehydes, ketones and related derivatives Element. In order to reduce the emission of hydrocarbons, installing DOC (Diesel Oxidation Catalyst, oxidation catalyst) in the engine exhaust aftertreatment system is the main technical means at present. The oxidation catalyst is composed of four parts: housing, vibration damping layer, carrier and catalyst. As the exhaust gas passes through the oxidation catalyst, pollutants such as CO and hydrocarbons (except methane) will be oxidized, thereby reducing pollutant emissions .

Methane among hydrocarbons is a greenhouse gas with a high thermal potential, and its warming potential is 21 times greater than that of carbon dioxide. Methane is a highly stable compound that requires high activation energy to break carbon-hydrogen bonds and oxidize methane molecules. Effective oxidation of catalytic methane requires tail gas temperatures above 600°C. Oxidation catalysts in exhaust aftertreatment systems have difficulty removing methane, a greenhouse effect component, from exhaust gases from dual-fuel/natural gas engines due to their low temperatures.

In the prior art, the oxidation catalytic technologies for engine exhaust mainly include:

1. The "diesel engine oxidation catalyst" disclosed in the patent document with application number 201020620945.0 is a design of a diesel engine oxidation catalyst, which is packaged in a clam shell and uses lower-priced palladium to reduce production costs. However, this device is only suitable for vehicle diesel engines, and the oxidation catalytic efficiency is not high enough, nor can it remove methane in the exhaust components of marine dual-fuel/natural gas engines.

2. The "Diesel Oxidation Catalyst and Method for Treating Engine Exhaust" disclosed in the patent document with application number 201180074031.6, designed a diesel oxidation catalyst, the device has carried out the inlet port and outlet channel of the oxidation catalyst Improvement, which is beneficial to improve the problem that the oxidation catalyst is susceptible to clogging by soot and hydrocarbon particles. However, the device is designed for diesel engines and has a low oxidation and catalytic temperature, so it cannot handle methane in the exhaust components of marine dual-fuel/natural gas engines.

Contents of the invention

The object of the present invention is to provide a kind of treatment system that can remove multiple environmental pollutants including methane that cannot be oxidized by ordinary oxidation catalytic converters, reduce ship exhaust pollutants and greenhouse effect gas emissions, and escape methane from ship dual-fuel or natural gas engines .

The purpose of the present invention is achieved like this:

It includes the oxidation catalyst connected behind the exhaust pipe of the engine, and also includes the afterburner. The afterburner is connected to the oil tank through a separate afterburner oil pump. The outlet of the afterburner is integrated into the engine exhaust pipe to heat the exhaust pipe. The methane-containing exhaust gas from the engine makes the exhaust gas temperature reach the temperature required for methane oxidation catalysis.

The present invention may also include:

It also includes a temperature sensor and an electronic control device. The temperature sensor is installed on the exhaust pipe of the engine after the outlet of the afterburner is incorporated. The temperature sensor monitors the exhaust gas temperature before the oxidation catalyst and inputs it into the electronic control device, and the electronic control device controls the afterburner. Oil pump and afterburner.

The invention provides an oxidation catalytic device for post-treatment exhaust gas of a marine dual-fuel/natural gas engine capable of removing various environmental pollutants including methane. The system is composed of an oxidation catalytic device and an afterburner, which can increase the temperature of the engine exhaust gas to the temperature required for methane oxidation and catalysis, remove various environmental pollutants including methane that cannot be oxidized by ordinary oxidation catalysts, and reduce ship exhaust pollution. emissions of pollutants and greenhouse gases.

The technical solution of the invention includes an oxidation catalyst, an afterburner, a temperature sensor, an electric control device, a pump and pipelines. The afterburner is connected with the fuel tank through a separate afterburner oil pump, and the afterburner and the oil delivery pump are connected with the electric control device. The oxidation catalyst is installed in the exhaust pipe of the engine, and the exhaust gas enters the exhaust pipe from the engine. When it is necessary to deal with the methane in the dual fuel/natural gas exhaust gas of the ship, the afterburner starts to work, and the fuel in the fuel tank is sent to the afterburner through the oil transfer pump. The high-temperature exhaust gas produced by the afterburner is incorporated into the engine exhaust pipe to heat the methane-containing exhaust gas from the engine in the exhaust pipe. The temperature sensor monitors the exhaust gas temperature in front of the oxidation catalyst and selects the start Stop the burner. The system increases the temperature of tail gas oxidation and catalysis by adding an afterburner to make it reach the temperature required for methane oxidation and catalysis, so as to achieve the purpose of removing escaped methane from tail gas.

The main features of the technical solution of the present invention are reflected in:

1. Use high-temperature exhaust to increase the temperature of the exhaust gas of the ship's dual-fuel/natural gas engine so that it reaches the temperature at which the oxidation catalyst can remove methane, so that the escaped methane in the engine exhaust gas can be oxidized in the oxidation catalyst.

2. The method of combining the afterburner and the oxidation catalyst is adopted.

3. Control the temperature of the exhaust gas to ensure that the temperature of the exhaust gas in the oxidation catalyst is within a suitable range for oxidation and catalytic methane.

4. The temperature of the exhaust gas passing through the afterburner is controlled to be 600°C to 750°C.

5. The inlet end of the afterburner is connected to the oil pump of the afterburner and the fuel tank in turn. An oxidation catalyst is installed on the exhaust pipe of the engine. The temperature sensor is arranged on the exhaust pipe in front of the oxidation catalyst. The input end of the electronic control device is connected to the temperature The output end of the sensor is connected to the afterburner and the oil pump of the afterburner. The high-temperature exhaust gas produced by the afterburner flows into the engine exhaust pipe through the exhaust pipe of the afterburner, and flows into the oxidation catalyst together with the methane-containing exhaust gas produced by the engine.

6. The methane-containing tail gas from the ship's dual-fuel/natural gas engine enters the oxidation catalyst through the exhaust pipe. The temperature sensor measures the temperature of the exhaust gas in front of the oxidation catalyst, and inputs the temperature signal into the electronic control device. If the temperature is lower than 600°C ( methane oxidation catalytic reaction temperature), the output signal of the electronic control device makes the afterburner oil pump inject oil, the afterburner ignites and runs, and the afterburner generates high-temperature exhaust gas that flows into the engine exhaust pipe to heat the exhaust gas in the exhaust pipe. If the temperature signal input by the temperature sensor to the electronic control device is higher than 750°C, the output signal of the electronic control device will stop the operation of the afterburner oil pump and the afterburner, so that the temperature of the exhaust gas flowing through the oxidation catalyst can be kept at a temperature that can oxidize and catalyze methane In the appropriate range, so as to achieve the purpose of removing methane, but also can oxidize CO, hydrocarbons (except methane) and other pollutants.

7. When the ship's dual-fuel engine works in fuel mode or the engine operating condition does not need to remove methane, the electronic control device controls the afterburner oil pump and the afterburner to shut down, no high-temperature exhaust gas is produced, and only the engine generates At this time, CO, hydrocarbons (except methane) and other pollutants can be oxidized, which can effectively save energy consumption and improve economy.

8. According to the operating mode of the ship's dual-fuel engine or the operating conditions of the engine, it is actively selected whether to deal with the methane in the tail gas.

The advantage of the present invention compared with prior art is:

(1) The combination of the oxidation catalyst and the afterburner increases the temperature of the exhaust gas oxidation catalytic reaction, can remove the methane that cannot be removed by the ordinary oxidation catalyst, and reduces the emission of engine exhaust HC and greenhouse gas.

(2) The afterburner is independent from the engine exhaust pipe, and has little influence on the combustion performance of the engine.

(3) When the marine dual-fuel engine is running in the fuel mode or the operating condition does not need to remove methane, the afterburner can be stopped through the electronic control device, so that the exhaust gas can be oxidized and catalyzed at a lower temperature, which can effectively reduce energy consumption. Improve economy.

Description of drawings

Figure 1 is a schematic diagram of the present invention.

Detailed ways

The following examples describe the present invention in more detail.

Referring to Fig. 1, the present invention mainly includes an oxidation catalyst 8, an afterburner 5, an afterburner oil pump 4, an electronic control device 6, a temperature sensor 7, and auxiliary pipelines and control lines. The inlet end of the afterburner 5 is connected to the afterburner oil pump 4 and the fuel tank 1 in turn, the engine 2 is connected to the engine fuel pump 3 and the fuel tank 1 through the oil circuit (for engine fuel mode or pilot gas fuel), and the engine exhaust pipe An oxidation catalyst 8 is provided, and a temperature sensor 7 is arranged on the exhaust pipe in front of the oxidation catalyst 8. The input end of the electronic control device 6 is connected to the temperature sensor 7, and the output end is connected to the afterburner 5 and the afterburner oil pump 4. The high-temperature exhaust gas generated by the afterburner 5 flows into the engine exhaust pipe through the afterburner exhaust pipe, and flows into the oxidation catalyst 8 together with the methane-containing tail gas generated by the engine 2 .

The function of this device to oxidize and catalyze methane is realized in this way: the methane-containing tail gas from the ship's dual-fuel/natural gas engine 2 enters the oxidation catalyst 8 through the exhaust pipe, and the temperature sensor 7 measures the temperature of the tail gas before the oxidation catalyst 8, and the temperature The signal is input into the electronic control device 6. If the temperature is lower than 600°C, the electronic control device 6 outputs a signal to make the afterburner oil pump 4 inject oil, the afterburner 5 ignites and run, and the afterburner 5 generates high-temperature exhaust gas to flow into the engine In the exhaust line, the methane-containing tail gas in the exhaust line is heated. If the temperature signal input by the temperature sensor 7 to the electronic control device 6 is higher than 750°C, the electronic control device 6 outputs a signal to stop the operation of the afterburner oil pump 4 and the afterburner 5, so that the temperature of the exhaust gas flowing through the oxidation catalyst 8 Keep within the appropriate range for oxidation and catalytic methane, so as to achieve the purpose of methane removal, and also be able to oxidize CO, hydrocarbons (except methane) and other pollutants.

When the ship's dual-fuel engine is running in fuel mode or the engine operating condition does not need to deal with methane, the electronic control device 6 controls the afterburner oil pump 4 and the afterburner 5 to close, no high-temperature exhaust gas is generated, and only the secondary burner in the oxidation catalyst 8 The exhaust gas produced by the engine 2 flows through, and at this time, the oxidation of CO, hydrocarbons (except methane) and other pollutants can be completed, which can effectively reduce energy consumption and improve economy.

While the invention has been described in connection with the examples in this faming, it is to be understood that the invention is not limited to the disclosed embodiments but encompasses various combinations of features thereof as defined in the appended claims Or modify some other applications already included within the scope of the present invention.

Claims (3)

1. A treatment system for marine dual-fuel or natural gas engine escaping methane, comprising an oxidation catalytic converter connected behind the engine exhaust pipe, characterized in that it also includes an afterburner, and the afterburner communicates with the afterburner through a separate afterburner oil pump The oil tanks are connected, and the outlet of the auxiliary burner is merged into the engine exhaust pipe to heat the methane-containing tail gas from the engine in the exhaust pipe, so that the temperature of the tail gas reaches the temperature required for methane oxidation and catalysis. 2. The processing system of marine dual-fuel or natural gas engine escaping methane according to claim 1, characterized in that: it also includes a temperature sensor and an electric control device, and the temperature sensor is installed in the outlet of the after-burner after the engine exhaust is incorporated On the pipeline, the temperature sensor monitors the exhaust gas temperature in front of the oxidation catalyst and inputs it into the electronic control device, and the electronic control device controls the afterburner oil pump and the afterburner. 3. The processing system for marine dual-fuel or natural gas engine escaping methane according to claim 2, wherein the electronic control device controls the afterburner oil pump and the afterburner specifically includes: a temperature sensor measures the tail gas before the oxidation catalyst Temperature, input the temperature signal into the electronic control device, if the temperature is lower than 600°C, the electronic control device will output a signal to make the afterburner oil pump inject oil, the afterburner will ignite and run, and the afterburner will generate high-temperature exhaust gas and flow it into the exhaust of the engine In the pipeline, the exhaust gas in the exhaust pipe is heated; if the temperature signal input by the temperature sensor to the electronic control device is higher than 750°C, the output signal of the electronic control device will stop the operation of the afterburner oil pump and the afterburner, so that the gas flowing through the oxidation catalyst The exhaust gas temperature of the device is kept in an appropriate range capable of oxidizing catalytic methane.