Dual-channel gas state mercury exhaust gas sampling system

Abstract

The invention belongs to the technical field of environmental monitoring, and relates to a dual-channel gas state mercury exhaust gas sampling system. The dual-channel gas stage mercury exhaust gas sampling system comprises a sampling gun, a heat tracing pipeline and a sampling host machine, wherein two sampling pipes can be installed on the sampling gun. A water removal device and an acid removal device are sequentially connected between the heat tracing pipeline and the sampling host machine. The sampling host machine comprises a sampling pump, a flow control valve used for regulating sampling flow, and a gas flow metering device, wherein the sampling pump, the flow control valve and the gas flow metering device are communicated through pipelines. Vacuum degree control valves are connected at two ends of the sampling pump in a parallel mode. The gas flow metering device comprises a dry-type gas flow meter, a rotary coder and a counter, wherein the rotary coder is fixed on a transmission shaft of a counting plate of the dry-type gas flow meter, a signal output by the rotary coder is sent to the counter, and the counter measures volume of gas according to the output signal of the rotary coder. According to the dual-channel gas state mercury exhaust gas sampling system, accurate measurement of gas flow can be achieved and the sampling pipes can be effectively protected.

Description

technical field [0001] The invention relates to a sampling device in the field of environmental monitoring, in particular to a collection device for gaseous mercury in flue gas. Background technique [0002] my country is the world's largest coal-producing country. Coal has long accounted for about 70% of China's energy production and consumption structure. According to data from the US Environmental Protection Agency, about 31% of mercury in the atmosphere comes from coal-fired power plants. The burning of coal is the first source of anthropogenic mercury emissions. According to a UNEP research report, China's atmospheric mercury emissions reached 825 tons in 2005, accounting for about 40% of the world's anthropogenic mercury emissions. my country has become the country with the largest mercury usage and emissions. The human health and ecological impact of such a large amount of mercury discharge on my country and the world is unpredictable, and it also brings new challeng...

AI Technical Summary

Problems solved by technology

However, the sampling equipment of the EPA30B method mainly has the following disadvantages: first, the adsorption tube is directly installed on the front end of the sampling gun and inserted into the flue for sampling. Second, the flue gas contains a certain amount of particulate matter. During the process of collecting mercury in the flue gas, the adsorption tube directly contacts the flue gas, and the particulate matter in the flue gas easily enters the adsorption tube, resulting in inaccurate monitoring data; third. , the existing sampling equipment temperature detection point is placed at the casing of the dry gas flowmeter. The casing of the flowmeter is mainly made of aluminum alloy, which has the disadvantages of conduction temperature difference and large interference by outdoor temperature, and cannot reflect the flue gas well. Actual temperature; Fourth, the flue gas contains a large amount of SO 2 Such acidic substances, these substances will cause damage to the instrument after directly entering the sampling system without treatment

At present, the sampling equipment based on the EPA30B method mainly installs the adsorption tube directly on the front end of the sampling gun and inserts it into the flue for sampling. The adsorption tube is generally made of glass and is fragile. It is easy to break when inserted into the flue or pipe, resulting in sampling Failed, in order to avoid this phenomenon, there are also inventions that install the adsorption tube at the back of the sampling gun, but the sampling pipeline will cause adsorption loss of mercury, and these two methods may cause particulate mercury in the flue gas to enter the sampling tube, causing The high monitoring value cannot accurately measure the gaseous mercury content

[0007] In terms of temperature measurement before the meter, the current sampling equipment places the detection point at the casing of the dry gas flowmeter. The casing of the flowmeter is mainly made of aluminum alloy, which has the disadvantages of conduction temperature difference and large interference by outdoor temperature, and the flue gas contains A large amount of acidic substances, these substances directly enter the sampling equipment without removal, which may cause corrosion damage to the sampling equipment

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