the present invention is a process for reducing particulate , hg , nox , and so 2 emissions from the combustion of fossil fuels that provides the ability to produce commercially valuable acids as reaction products . throughout this specification , nox is intended to include , but not be limited to , no and no 2 . turning to fig1 flue gas 10 is created by the combustion of fossil fuel in a boiler . fuels that are typically used in electric utilities and manufacturing plants include coal and oil , but may comprise other substances like gas , tires , trash , or biomass . flue gas emissions 10 enter a electrostatic precipitator casing ( esp ) 15 . a standard dry esp 14 is provided that typically removes approximately 90 % of the particulate ash . in practice , it is anticipated that the present invention is likely to be retrofitted into existing esp &# 39 ; s . the last fields of the existing dry esp are removed to make room for a barrier discharge reactor 100 and wet esp 120 . &# 34 ; barrier discharge &# 34 ; is also known as silent , and non - thermal plasma discharge . it is not the same as corona or electron beam discharge . the reactor 100 converts a portion of the hg , nox and so 2 present in the flue gas to hgo , hno 3 and h 2 so 4 . the acids , hgo , and most of the fine particles not collected by the dry esp 14 are collected in the wet esp 120 . the wet esp 120 also collects no 2 and so 2 gas . having had most of the hg , nox , so 2 , and particulate matter removed , the flue gas exits the precipitator 20 with greatly reduced amounts of hg , nox and so 2 , and almost no particles . as an alternative to the preferred embodiment , the reactor 100 and wet esp 120 can be installed outside the existing esp casing 15 . yet another alternative is to follow the reactor 100 and wet esp 120 sections with an additional converter and wet esp section , either inside or outside the esp casing 15 , in order to obtain a desired conversion efficiency . the reactor 100 and wet esp 120 can be thought of as stages , and any number of stages can be provided to reduce emissions to their desired levels . the effluent from the wet esp 120 is collected as a mixture and travels to an optional separator apparatus 140 , where the particulates 144 are removed . the separator apparatus may comprise a settling tank , a filter , a centrifuge , or any combination of the three as is commonly practiced in the art . the remaining mixture travels to an optional processing apparatus 160 . one embodiment of processor separates the hno 3 and h 2 so 4 , and concentrates them for industrial use . the result is concentrated h 2 so 4 200 and concentrated hno 3 210 . another processor 160 would be an acid neutralization plant , or other chemical processing means . the acids can also be reused in the wet esp or in a packed bed scrubber . the choice of whether to employ the separating and processing steps depends on the economics at an individual plant location . acid prices vary from region to region , and there may be some regions in which it is more economical to dispose of the acid products instead of refining them for industrial use , thereby providing a cash stream from the effluent . turning to fig2 the composition of the flue gas 12 before the dry esp 14 is primarily particulate ash , n 2 , co 2 , h 2 o , o 2 , so 2 , nox , hg and other trace heavy metals . after the dry esp 14 and before the converter apparatus 100 , the composition of the flue gas 16 is primarily fine particulates on the order of 2 . 5 microns , n 2 , co 2 , h 2 o , o 2 , so 2 , nox , hg and other trace heavy metals . the barrier discharge reactor 100 in the preferred embodiment is a coaxial tube - style reactor , where a conductive tube is one electrode , a center electrode is secured inside along the longitudinal axis , and a dielectric material is disposed between them within the tube . the tubes can be arranged in tube bundles 106 , here shown as four bundles high within the esp casing 15 . the actual number of bundles 106 arranged high and across are engineering decisions within the capability of those having skill in the art , and is shown here as four as an example only . the electrodes are energized by a power supply 102 that converts station - provided , three - phase power into high voltage alternating current power . the power supply is electrically connected to the reactor . the voltage supplied to the converter is preferably between about 15 , 000 and about 50 , 000 volts rms at a frequency between about 50 hz and about 10 khz . the preferred embodiment operates at about 1 khz . operating at a lower frequency reduces the size and cost of the high voltage transformer required . in using barrier electrical discharge , high voltage alternating current is applied to electrodes which are separated by a gas space and a dielectric barrier . the voltage can be applied in any one of several waveforms , including but not limited to sine , square , triangle , and pulsed voltages . the major chemical reactions in the conversion of nox to hno 3 are as follows : the major chemical reactions in the conversion of sox to h 2 so 4 are as follows : the composition of the flue gas 18 after the converter but before the wet esp 120 is primarily fine particulates , n 2 , co 2 , h 2 o , o 2 , 75 % of the original so 2 , 25 % of the original nox ( predominantly in the form of no 2 ), hgo , h 2 so 4 and hno 3 . note that the reactor 100 converted hg present in the flue gas to hgo that is readily collected in the wet esp 120 . an optional packed bed scrubber 110 can be provided between the reactor 100 and wet esp 120 . packing 112 is held in place by a grid , screen or other structure that allows flue gas to pass through and holds the packing . the packing 112 is charged with a concentrated acid spray 114 shown coming from the top , but can be from the sides . preferably , the acid is about 70 % sulfuric acid and less than 5 % nitric acid . however , the nitric acid should be less than 10 %. the acids used may be the products of the acid processing step . the selection of packing material and geometry is within the ability of one having skill in the chemical engineering art . an evaporative cooling water spray injection apparatus 122 sprays water into the flue gas just before it reaches the wet esp 120 . like the dry esp 14 , the wet esp 120 comprises a plurality of plates 128 . in the preferred embodiment , the plates are subcooled below the saturation temperature of the flue gas , for example , by the use of cooling water 124 provided at the station . in this manner the acids in the composition of the flue gas 18 tends to condense on the surfaces of the wet esp plates 128 . very little of the acids in the composition 18 exits the esp 20 and goes into the environment through the stack 22 . the effluent from the wet esp 126 is primarily a slurry or mostly - liquid mixture of dilute h 2 so 4 , dilute hno 3 , scrubbed so 2 , fine particles , and hgo . it travels to a separation apparatus 140 . the mixture is separated by a settling tank , centrifuge , or filter 142 . the resulting solids 144 are removed and safely disposed of . the remaining dilute acids 148 are transported by an optional pump 146 to a processing apparatus 160 . one embodiment of a processing apparatus 160 separates the acids and concentrates them to produce hno 3 200 and h 2 so 4 210 . another processing apparatus my neutralize the acids for disposal . still others may perform other desired chemical reactions . fig3 shows one embodiment of a tube bundle 106 of coaxial reactors . a plurality of coaxial electrode tubes 180 are secured in a spaced relationship to each other using preferably a rectangular structure 192 . the tubes are preferably made of 11 / 4 inch diameter stainless steel tube , but other sizes and materials may be used . wire electrodes 182 are secured inside the coaxial electrodes along the longitudinal axes of the tubes . some tubes may not be provided with wire electrodes . although the term &# 34 ; wire &# 34 ; is used , these electrodes can be rods , or other shaped material smaller than the inside diameter of the tubes . the material does not necessarily have to be smooth like a wire , but is preferably made of stainless steel . the bundle 106 is arranged so that flue gas flows substantially horizontally through the reactor 100 . in this way , pressure drop across the reactor is minimized . the bundles may also slant slightly downhill from the upstream side to prevent ash accumulation . sonic horns , vibrators , or rappers can also be employed for preventing ash buildup in the reactor . although the reactor tubes are preferably horizontal , which is parallel to flue gas flow , the tubes can also be secured vertically within the casing 15 . an externally cooled reactor 100 is shown in fig3 . a cooling fluid 190 enters the support structure 192 . heat generated by the barrier discharge reaction passes through the tubular electrode 180 walls to the fluid 190 . the chemical reactions that take place in the reactor vary according to the temperature . it has been found to be advantageous to maintain a reactor temperature greater than about 300 degrees fahrenheit . the reactor can also be effectively operated at higher or lower temperatures , however . the heat transfer fluid 190 can be oil , water , air , or other heat transfer medium that is known in the art . the heat recovered from the reactor can be dissipated to the environment , or it can recovered for use in other processes at the plant . the heat can be used to increase the efficiency of an acid processing and concentration apparatus 160 . it can also be used to pre - heat the air going into the combustion chamber of the plant to increase its efficiency . fig4 is a cross section of a coaxial tube electrode 180 . the wire electrode 182 is secured in the middle along the tubes longitudinal axis . surrounding the wire electrode is a dielectric barrier material 184 necessary for initiating and sustaining a barrier discharge . in the preferred embodiment , it is a hollow cylinder of quartz or alumina . preferred sizes are cylinders having a 3 mm inside diameter and 5 mm outside diameter , or 5 mm inside diameter and 8 mm outside diameter . preferably , the outside of the wire electrode 182 is in a contacting relationship to the inside diameter of the dielectric 184 . although flat plate electrodes have been used in barrier discharge reactors for pollution control in the past , coaxial reactors greatly improve performance of the process . of the many benefits , it is easier to establish a barrier discharge within the whole discharge area in a coaxial reactor than a flat plate reactor . temperature gradients between the top and bottom of a flat plate reactor often provide inhomogeneous reactions , which decrease reactor efficiency . the tops are hotter than the bottoms , and the middles are hotter than the sides in flat plate reactors . coaxial reactors , on the other hand , tend to &# 34 ; light off &# 34 ; evenly throughout the whole tube as soon as temperature and power requirements reach the threshold for the particular reactor geometry . the reaction is very homogeneous . the result is that more gas is exposed to the barrier discharge , and more flue gas is treated . it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention . accordingly , it is intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention .