Processes and compositions are provided for decreasing emissions of mercury upon combustion of fuels such as coal. Various sorbent compositions are provided that contain components that reduce the level of mercury and/or sulfur emitted into the atmosphere upon burning of coal. In various embodiments, the sorbent compositions are added directly to the fuel before combustion; are added partially to the fuel before combustion and partially into the flue gas post combustion zone; or are added completely into the flue gas post combustion zone. In preferred embodiments, the sorbent compositions comprise a source of halogen and preferably a source of calcium. Among the halogens, iodine and bromine are preferred. In various embodiments, inorganic bromides make up a part of the sorbent compositions.

Reducing mercury emissions from the burning of coal

The invention relates to an air pollution sensor system (1) comprising an air inlet (11), an air outlet (12), a sensor unit (2), and an air displacement device (3). The air displacement device is arranged to establish an air flow (4) from the air inlet through the sensor unit to the air outlet. The sensor unit comprises, a filter (22) for removing airborne pollutants from the air flow. The sensor unit is arranged to generate an output signal (21) based on the amount of airborne pollutants removed from the air flow by the filter. The air displacement device is arranged to be controlled by the output signal, thereby improving the lifetime of the air pollution sensor system by minimizing the amount of pollutants that will be deposited inside the sensor unit when the air pollution sensor system is operated under predetermined conditions.

Air pollution sensor system

There is disclosed a particulate matter detection device having a high measurement sensitivity. A particulate matter detection device 100 of the present invention includes a plate-like element base material 11, and a pair of measurement electrodes 12a and 12b arranged in the element base material 11, each of the measurement electrodes 12a and 12b is a combteeth-like electrode including a plurality of planarly arranged combteeth portions 13, and a comb spine portion 14 which connects the plurality of combteeth portions 13 of each of the measurement electrodes 12a and 12b to one another at one end of each of the plurality of combteeth portions, the combteeth portions 13 of the measurement electrodes 12a and 12b are arranged to engage with each other with a space being left therebetween, and the comb spine portion 14 of at least one of the measurement electrodes 12 is covered with a comb spine covering portion 15 made of a dielectric material. The particulate matter detection device 100 allows a particulate matter to adhere to and around the pair of measurement electrodes 12a and 12b, and measured a change of electric characteristics between the pair of measurement electrodes 12a and 12b, to detect the particulate matter.

Particulate matter detection device

According to an embodiment, combustion in a combustion volume is affected by at least two sequentially applied non-parallel electric fields. According to an embodiment, a combustion volume is equipped with at least three individually modulatable electrodes. According to an embodiment, an electric field application apparatus for a combustion volume includes a safety apparatus to reduce or eliminate danger.

System and apparatus for applying an electric field to a combustion volume

A method and apparatus for reducing particle emissions from combustion processes and increasing combustion efficiency. A high voltage electrical potential is passed through a combustion flame to agglomerate particles, which are then removed from the exhaust gases through combustion or deposition on nearby surfaces of the apparatus. It is believed that application of high voltage electrical potential increases movement of the ions and free electrons within the combustion flame, causing increased oxygen mixing, and combustion efficiency. In one embodiment of the invention, a high voltage electrical potential is applied to the combustion flames of a wood stove and secondary air is supplied in the vicinity of the upper periphery of the flames. Application of the high voltage electrical potential and secondary air dramatically reduces particle emissions produced by the wood stove.

Apparatus and method for reducing particulate emissions from combustion processes

Unburned particulate matter is removed from a combustion gas stream by adding a conditioning agent to modify the resistivity of the particulate matter and passing the conditioned combustion gas stream through an electrostatic precipitator whose precipitating elements are energized with an intermittent applied voltage. The addition of conditioning agent and the precipitating voltage signal are mutually optimized. A controller receives measurement signals from sensors that monitor the total flow rate of particulate matter in the gas stream before the electrostatic precipitation treatment, and the concentration of particulate matter in the gas stream after the treatment. Performance of the system may be optimized according to selected combinations of variables.

Removal of particulate matter from combustion gas streams

The sulfur trioxide in the combustion gas stream of a power plant is reacted with injected ammonia to produce a solid ammonium sulfate that is captured, and not released to the atmosphere. A feedforward signal indicative of the total mass flow of sulfur trioxide is determined as the product of the measured boiler load and the sulfur trioxide content of the combustion gas, as measured prior to the addition of ammonia. The ammonia mass flow injection rate is preferably at a normal stoichiometric ratio of from about 1.0 to about 1.1 relative to the sulfur trioxide mass flow rate (that is, from about 2.0 to about 2.2 times the molar mass flow rate of the sulfur trioxide), avoiding the production of ammonia bisulfate. The ammonia content of the combustion gas stream is measured downstream of the location at which ammonia is added. Based upon this feedback measurement, the amount of ammonia added is adjusted to be just sufficient to react with all of the sulfur trioxide, but not in such excess as to be environmentally detrimental.

Reduction of acidic emissions from combustion of sulfur-laden fuels

Additions of conditioning agents to a particulate-containing flue gas stream are controlled by a controller operating from feedforward and feedback signals received from sensors in the combustion and gas cleanup system, and, optionally, from the power consumption level of the electrostatic precipitator. The flow rates of the conditioning agents, such as sulfur trioxide and ammonia, are thereby balanced to achieve an optimal removal of particulate matter and also sulfur and sulfur compounds from the gas stream before it is exhausted to the atmosphere. A typical feedforward signal is the boiler loading, and typical feedback signals include residual sulfur trioxide and ammonia levels and stack gas opacity.

Control of addition of conditioning agents to flue gas

The resistivity of particulate matter in a gas stream, such as a combustion gas stream produced in a coal-fired power plant, is measured by collecting a sample of the particulate on the surface of a porous ceramic cylinder (62), either with or without an applied collection voltage, and then determining the resistance of the sample with a compound measurement electrode (82) having multiple conductors (84,86). The referece electrode (89) and the measurement electrode (82) are spirally wound on the ceramic cylinder (62) in an interdigitated manner, so that the two (82,98) are laterally adjacent down the length of the cylinder (62). The pressure within the cylinder (62) is controllable, with a pressure below atmospheric being applied to draw the particulate to the surface and ascertain when a sufficient sample for measurement is present, and a pressure above atmospheric being applied to blow away the sample after the measurement is completed, thereby preparing the instrument for the taking of another sample.

Measurement of electrical resistivity of particulate entrained in a gas stream

Effluent gas streams from power plants, or other sources, containing entrained particulate matter are conditioned by injecting a conditioning gas such as sulfur trioxide into the flowing gas stream. The conditioning gas is deposited upon the surface of the particulate and reduces its electrical resistivity, improving the performance of electrostatic precipitators through which the flowing gas is passed to precipitate the particulate. At the point of injection, an electrostatic potential is established between the particulate in the flowing gas stream and the conditioning gas molecules, so that the conditioning gas is attracted to the particulate. Interaction of the conditioning gas with the particulate is stronger and more rapid than in the absence of the electrostatic potential at the point of injection.

Everett L. Coe

Papers

Removal of particulate matter from combustion gas streams

Reduction of acidic emissions from combustion of sulfur-laden fuels

Control of addition of conditioning agents to flue gas

Measurement of electrical resistivity of particulate entrained in a gas stream

Conditioning of gas streams containing particulate