System for removing noxious odors from a chemical tanker truck

Apparatus for removing noxious odors from a chemical tanker truck hauling hot hydrocarbon products includes a condensation box mounted below the tank. The condensation box has a perforate metal mesh filter media positioned within its interior. A pair of conduits delivers hot chemical vapor from the top of the tank to the condensation box in a location spaced below the metal mesh filter media. The hot vapor passes upwardly through the metal mesh filter media and is cooled to cause condensation of a noxious fraction from the vapor which collects in the bottom of the box. A less noxious fraction of the vapor leaves the condensation box through a plurality of vent pipes positioned above the filter media.

BACKGROUND OF THE INVENTION 
The present invention relates generally to air filtration apparatus and, 
more particularly, to apparatus and methods for treating noxious vapors 
emitted from tanker trucks in the transport of hot coal tar, pitch, 
creosote, naphthalene and other hot hydrocarbon products. In the transport 
of hot hydrocarbon products, it is necessary to vent the tank to the 
atmosphere so as to permit the hot vapors to escape from the tank. 
Typically, hydrocarbon chemical products are transported at elevated 
temperatures on the order of about 500.degree.-700.degree. F. in a tanker 
truck having a capacity of from about 5,000 to 7,000 gallons. It is an 
absolute necessity in non-pressure vessel style tanks to vent the vapors 
from a tank of this size, otherwise, the tank may explode due to the great 
pressure generated by the hydrocarbon vapors within. 
Heretofore, it has been conventional practice in the transport of such hot 
hydrocarbon products, to merely vent the tank to the atmosphere. This 
practice results in the continuous escape of noxious vapors into the 
atmosphere which causes a number of problems. One of the more common 
problems is the objectionable odor emitted by the vapor and the complaints 
generated from people exposed to these foul vapors along the transport 
route. Certain unknown environmental hazards may also be present. In 
addition, the conventionally vented vapors cause unsightly black deposits 
along the exterior of the tanker truck while also representing an economic 
loss due to the escaping vapors. 
The present invention is directed to an apparatus and method for solving 
the problems heretofore encountered in transporting hot hydrocarbon 
products such as coal tar products, pitch, creosote, naphthalene and the 
like. The present invention provides an apparatus and method for filtering 
the hot vapors from a chemical tanker truck to remove noxious odors 
therefrom while recovering a liquid hydrocarbon component for recycling 
thereof. The invention also includes an apparatus and method for inducing 
a draft of vapor from the chemical product tank to the filter unit while 
the tanker truck is in motion so as to increase the efficiency of the 
filtration system. 
The present invention further provides a filtration system for chemical 
tanker trucks which is economical to fabricate and trouble-free to 
operate, requiring no supplemental power or moving parts, other than the 
truck itself. 
Still further, the present invention is also suitable for use in connection 
with pressurized tank trucks for filtering vapors which remain in the tank 
under pressure after the tank is unloaded. 
SUMMARY OF THE INVENTION 
Briefly stated, the apparatus of my invention includes a condensation box 
mounted beneath the tank portion of the tanker truck. The condensation box 
has a top, a bottom and enclosing side walls defining an open interior 
therein. A filter, preferably in the form of a perforate metal mesh 
filter, is mounted within the interior of the condensation box at a 
location spaced above the bottom thereof. The condensation box also 
includes vent means, preferably in the form of a plurality of pipes 
angularly disposed from the rear side wall to permit communication between 
the interior of the box and the atmosphere. At least one, and preferably, 
a pair of conduits extend from an upper portion of the tank having first 
ends in communication with the interior of the tank and second ends 
communicating with the interior of the condensation box, at a position 
below the perforate metal filter. 
In use, pressurized hot hydrocarbon vapor leaves the tank and passes 
through the conduits to enter the lower part of the condensation box. The 
vapor passes upwardly through the perforate metal filter media and, in the 
process, is cooled. A noxious fraction of the hot vapor then condenses as 
it is cooled by the metal filter and the condensed liquid collects at the 
bottom of the condensation box. A fraction of less noxious vapor passes 
through the perforate metal filter media and leaves the box in a gaseous 
state via the vent pipes to the atmosphere. The condensation box includes 
an access door preferably at a front side wall to permit access to the 
interior of the box to permit changing and/or cleaning of the filter media 
periodically. The invention also includes drain means at the bottom of the 
condensation box to allow for recapture and recycling of the condensed 
liquid fraction of the hydrocarbon product which collects at the bottom of 
the condensation box. 
One aspect of the invention pertains to the operation of the vent pipes. 
Preferably four vent pipes are fitted on the rear wall of the condensation 
box. The condensation box also preferably includes a transverse wall 
spanning the interior of the box from opposed side walls, extending 
upwardly from a rearward end of the filter with an upper edge spaced from 
the top of the box. The transverse wall defines an isolation area adjacent 
to the vent pipes. The vent pipes are fitted at about a 45.degree. angle 
relative to the end wall such that their outer ends are lower than the 
attached ends. In this manner, when the tanker truck is in motion, the 
ambient air passing along the condensation box and vent pipes causes a 
lower pressure area to exist at the outside ends of the vent pipes, and 
within the isolation area of the condensation box. This vacuum-like 
condition causes an induced draft within the condensation box and induces 
a flow of vapors from the tank through the conduits to the condensation 
box as the truck is in motion.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to the drawings, a typical tanker truck 2 is shown in FIG. 
1A which includes a conventional tractor truck 4, and a tanker trailer 6. 
The tanker trailer 6 has a tank 8 which may typically have a liquid 
capacity of between 5,000 to 7,000 gallons. The conventional tank trailer 
has eight rear wheels, a dolly 9 for supporting the trailer when it is 
detached from the truck and a hingeably-mounted domed lid 10 at the top 
for loading a liquid chemical product into the interior of the tank 8. As 
seen in FIGS. 1A and 1B, the tank 8 includes a so-called dog box 12 
surrounding the lid 10. A pair of breather pipes 14 is mounted in the dog 
box 12, each breather pipe having an inner end 16 communicating with the 
interior of the tank 8 and an outer end 18 positioned outside of the tank. 
Breather pipes are conventionally used on hot chemical tanks to vent hot 
vapors to the atmosphere so as to avoid pressure build-up in the tank. 
The filtration system of the present invention, generally designated by 
reference numeral 15, includes a condensation box 20 mounted by frame 
means 30 to the bottom of the tank 8 of the trailer 6. The system 15 
further includes at least one, and preferably two, conduits 40 extending 
from the top of the tank 8 to the condensation box 20. The conduits 40 
each have a first end 41 attached to the respective outer ends 18 of the 
breather pipes 14 and second ends 42 attached to the condensation box, as 
more fully described below. 
The condensation box 20 is preferably made from welded steel or aluminum 
plate. The condensation box 20 comprises a top plate 21 and a bottom plate 
22 enclosed by lateral side walls 23 and 24 and a front end wall 25 and a 
rear end wall 26. The enclosing plates; namely, top plate 21, bottom plate 
22, lateral side walls 23, 24, and end walls 25 and 26, when joined, 
define an open interior 28 within the condensation box 20. 
A filter plate assembly 50 is mounted within the interior 28 of the 
condensation box 20 as shown in FIGS. 5 and 6. The filter plate assembly 
50 is mounted in a position spaced above the bottom plate 22 to define a 
liquid condensate collection area 52 therein. As described above, the 
first ends 41 of each of the conduits 40 are connected at the top of the 
tank 8 in communication with the hot vapors emitted from the liquid 
chemical product being transported. A second end 42 of each of the 
conduits 40 is affixed to an elbow fitting 44 which, in turn, is attached 
to the condensation box 20 in a position 45 below the filter plate 
assembly 50, communicating with the interior of the filtration box in the 
area of the liquid condensate collection zone 52, see FIGS. 3 and 5. The 
first ends 41 of the conduits 40 are attached to the respective outer ends 
18 of breather pipes 14 at the top of tank 8 and the second ends 42 of the 
conduits are attached to respective outer ends of the elbow fittings 44, 
using conventional hose clamps 48 or the like. 
The filter plate assembly 50 comprises a pair of perforate metal mesh 
filters 54 and 56. The perforate metal mesh filters 54 and 56 are 
preferably made from aluminum mesh and may, for example, be rectangular in 
shape, on the order of sixteen inches wide by twenty-five inches long by 
two inches (16".times.25".times.2") thick for each filter. A perforate 
metal mesh filter of this type and size is marketed by Air Kontrol Inc. of 
Memphis Tennessee under type PH7735. An aluminum mesh filter is 
advantageous because of its light weight and ability to resist corrosion 
when exposed to hydrocarbons, as well as its high coefficient of thermal 
conductivity. 
The perforate metal mesh filters 54 and 56 are mounted in a plate-like tray 
58 which has two rectangularly-shaped holes formed therein to receive the 
filters 54 and 56. The tray 58 includes a border 60 which surrounds the 
open filter receiving portion and which is attached at its outer periphery 
to the side walls of the condensation box 20. As seen in FIGS. 5 and 6, a 
divider strip 61 extends between the side walls 24 and 25 to separate the 
filters 54 and 56. The filter tray 58 may also include a ledge 62 formed 
at the edges of the filter receiving opening to support the peripheral 
edges and align the metal mesh filters 54 and 56 within the tray opening. 
An elongated, rigid bar or strap 64 overlays the filters 54 and 56 and is 
attached at its opposed ends to the border area 60 of the filter tray 58. 
The hold-down strap 64 may include a tab end 66 fitted within a slot 
formed in the transverse wall 80 and a thumb screw 68 at the other end to 
provide securement of the strap 64 to the tray 58 When it is necessary to 
remove the filters 54 and 56 from the tray, the thumbscrew 68 is removed 
and the strap 64 is merely pulled away from the tray to permit removal of 
the filters for cleaning or replacement thereof. In order to gain access 
to the interior 28 of the condensation box 20 and the filters 54 and 56, 
the front side wall 25 has a removable panel 25' provided with bolts 27 
(FIG. 2 and FIG. 5) to permit the selective removal thereof. Panel 25' has 
a handle 29 to allow for easy handling when removal is necessary. 
As best seen in FIG. 6, the filter tray 58 also has two rupture discs 65 
formed therein as a safety feature. The rupture discs 65 are partially 
stamped out areas designed to break free from the filter tray 58 at a 
given threshold pressure in the event the filters become plugged and the 
vapor pressure builds up in the region 52. 
The condensation box is affixed to the tank 8 by a hanger mount 30. The 
mount 30 comprises four beam members 32 forming a rectangular, frame-like 
structure. Attachment legs 34 extend upwardly from each corner of the 
frame-like structure formed by the beam members 32, see FIGS. 2 and 4. 
Each of the attachment legs 34 carries an upper flange 36 which is 
attached to the outside of the tank 8 by rivets, bolts, or by welding, for 
example. Vertical members 37 extend downwardly adjacent each of the 
attachment legs 34 and corners of the beam members 32. A pair of vertical 
members 37 at each end of the mount 30 is attached to a pair of steel 
channels 38 which span and support the bottom 22 of the condensation box. 
A gusset 39 may be welded at the joint between each of the vertical 
members 37 and the channels 38 to provide additional rigidity and strength 
to the hanger mount structure 30. 
As shown in FIG. 5, the bottom plate 22 of the condensation box 20 includes 
a drain pipe 46 fitted with a threaded plug or valved orifice to permit 
selective draining of the liquid hydrocarbon product which has condensed 
in the collection area 52. Chemical product recovered from the drain 
orifice 46 may then be recycled. 
As best seen in FIGS. 5 and 6, the end wall 26 contains a plurality, 
preferably four, vent or exhaust pipes 70. Each exhaust pipe 70 has a 
first end 72 attached to the end wall 26 communicating with the interior 
28 of the condensation box in a position above the filter plate assembly 
50. The vent pipes 70 also include a second or terminal end 74 which is 
lower in elevation then the first end 72 so that the pipes 70 are disposed 
at an angle of about 45.degree. relative to the vertical rear end wall 26. 
The second ends 74 of the vent pipes, of course, communicate with the 
exterior atmosphere. When the truck 2 is in motion, the ambient air 
rapidly moves past the vent pipes 70 and causes a low pressure area to 
exist in the region of the second ends 74. The creation of a low pressure 
area causes an induced draft from the higher pressure region existing in 
the interior 28 of the condensation box. This action provides a natural 
pumping action from the interior of the box to ensure efficient operation 
of the device, acting much like a fan to induce a draft but without any 
exterior power or moving parts involved--the vacuum being created by the 
movement of the tanker truck itself. By way of further example, the vent 
pipes 70 may be one and a quarter inches (11/4") in diameter and about six 
inches (6") long. 
A transverse wall 80 is preferably disposed within the interior space 28 of 
the condensation box 20, extending between the long side walls 23 and 24 
of the condensation box above the filter plate assembly 50. The partition 
wall 80 has a top edge 82 which terminates about an inch below the upper 
plate 21 of the condensation box. In this manner, the partition wall 80 
forms an isolated vent chamber 90 to further enhance the vacuum effect of 
the angled vent pipes 70. 
In use, hot vapors leave the top of the tank 8 via the exhaust breather 
pipes 14 and travel through the conduits 40 to enter the liquid condensate 
collection area 52 of the interior of the collection box 20. The hot 
vapors flow upwardly through the metal mesh filters 54 and 56. The metal 
mesh cools the hot vapor as it passes therethrough whereupon a noxious 
fraction of the hot vapor liquefies and collects at the bottom portion 52 
of the condensation box 20. Concurrently, a fraction of less noxious vapor 
flows upwardly from the perforate metal mesh filters and passes through 
the opening above the partition wall 80 entering the isolated vent chamber 
90 to then exit into the atmosphere through the vent pipes 70. As 
mentioned above, as the tanker truck 2 moves, the air moving past the 
second ends 74 of the vent pipes 70 causes a lower pressure area to exist 
at the second ends, which, in turn, induces a draft of vapors from the 
conduits 40 through the filters 54 and 56 to the vent chamber 90. 
It will be appreciated by those skilled in the art that while the present 
invention has been described above in connection with vented tank trucks, 
the invention is also effective when used on pressurized tank trucks which 
are typically unvented during transport. Naturally, tanks of this class 
are pressure vessels and are constructed in a robust manner which is 
capable of containing hot, volatile hydrocarbon chemical products without 
the danger of rupture. Pressurized tanks of this type are unloaded under 
pressure and when the liquid product has been removed from the tank, a 
pressurized noxious hydrocarbon vapor remains in the tank. My invention 
also is useful in treating the vapor remaining in such pressurized tanks. 
In such cases, only one vapor conduit is needed extending from the 
so-called "Christmas tree" valve of the tank to the condensation box 
mounted on the tank. A multi-ported distributor (not shown) is presently 
preferred to evenly distribute the high pressure vapor in the condensation 
box. The vapor then travels upwardly through the filter media and liquid 
product condenses and the less noxious fraction of vapor is vented to the 
atmosphere. The liquid product collected in the condensation box may then 
be recovered, as previously described. 
While specific embodiments of the invention have been described in detail, 
it will be appreciated by those skilled in the art that various 
modifications and alternatives to those details could be developed in 
light of the overall teachings of the disclosure. The presently preferred 
embodiments described herein are meant to be illustrative only and not 
limiting as to the scope of the invention which is to be given the full 
breadth of the appended claims and any and all equivalents thereof.