Solids feeder having a solids-liquid separator

An apparatus for transferring solid materials between zones of substantially different pressures, the solid materials being supplied to a lockhopper containing a liquid having a density less than the solid materials, the solid materials with associated liquid passing through a solids-liquid separator chamber separating the solid materials and liquids so that the solid materials, substantially free of liquids, are passed into a vessel such as a pressurized reaction vessel.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an apparatus for transferring solid materials 
between zones of substantially different pressures, the solid materials 
being supplied to a lockhopper containing a liquid having a density less 
than the solid materials, the solid materials with associated liquid 
passing through a solids-liquid separator chamber separating the solid 
materials and liquids so that the solid materials substantially free of 
liquids, are passed into a vessel such as a pressurized reaction vessel. 
The liquid in the lockhopper acts as a liquid seal between the pressurized 
reaction vessel and lockhopper which is at a much lower pressure. 
Utilization of the solids-liquid separator chamber provides more rapid 
recycling of the lockhopper, prevents liquid from being carried into the 
reactor vessel if there is a pressure surge and allows handling finer 
solid materials. 
2. Description of the Prior Art 
Several methods utilizing different apparatus have been used in the past 
for the introduction of solids into pressurized reactors. Gas pressurized 
lockhoppers have been used for transferring solids into a pressurized 
reactor. Solids are added to a lockhopper at ambient pressure and the 
lockhopper closed and pressurized with gas to the pressure of the reactor. 
The solids are then added to the reactor which is at about the same 
pressure as the lockhopper. The lockhopper must then be isolated from the 
reactor and reduced to ambient pressures for introduction of the solid 
materials. Gas pressurized lockhoppers require complicated valving and in 
practice, have long cycle times. 
Lockhoppers are frequently constructed in the form of a long gravity feed 
leg above the reactor to overcome the pressure differential and thus are 
feasible over relatively small pressure differentials in the order of 
about 10 psi, due to the high pressure legs required. U.S. Pat. Nos. 
2,626,230 and 2,885,099 relate to different gravity feed leg 
configurations but do not overcome the basic problems of length of the leg 
required for high pressure differentials. 
High density liquids are suggested by U.S. Pat. Nos. 2,704,704 and 
3,009,588 to develop the desired pressure differential, but the liquids 
suggested, such as molten lead, mercury, tin, provide severe economic and 
environmental disadvantages. 
Sealing liquid such as water, is suggested by U.S. Pat. No. 2,828,026 in a 
system employing a drum with rotating feeder buckets. The operating 
pressure of a retort is balanced by a liquid standpipe and is again 
restricted to use over small pressure differentials, due to the height 
requirements of the liquid standpipe. 
U.S. Pat. No. 2,925,928 suggests feeding coarse solids through a fluidized 
bed of finely divided solids in a standpipe to balance the pressure 
difference between two zones of different pressure. However, use of this 
system over pressure differentials of only about 10 to 20 psi is 
practical. 
U.S. Pat. No. 3,729,105 teaches a lockhopper which contains liquid, serving 
as a liquid seal, through which a higher density solid falls and is fed to 
a pressurized vessel by a feeder, such as a screw feeder. This system may 
be used with higher pressure differentials than prior systems, but has 
disadvantages of the solids carrying undesired liquids into the 
pressurized vessel, especially with small particle size solids, and 
permits the liquid to be carried into the pressurized vessel, such as a 
reactor, if there is a depressurization surge in the reactor. It is 
apparent that in many reaction systems entry of the liquid into the 
reactor may be ruinous. 
SUMMARY OF THE INVENTION 
The apparatus of this invention for transferring solid materials between a 
storage means or bin and a closed vessel or reactor of substantially 
different pressures comprises in combination a solid materials storage 
means, a closed lockhopper containing a liquid having a density less than 
the density of the solid materials, a feeder means between a solids outlet 
of the lockhopper and the inlet of a solids-liquid separator chamber, and 
a screen separator means within the separator chamber sized to retain 
solid materials and pass them into the closed vessel or reactor while 
permitting passage of the liquid for recycle to the lockhopper. The closed 
lockhopper has a valved inlet in its upper portion and a valved outlet in 
its lower portion. A solid materials transfer means is provided for 
transfer of solid material from the storage means to the lockhopper inlet. 
A single liquid feed tank is provided having a liquid return conduit from 
the upper portion of the lockhopper to the lower portion of the tank and a 
liquid supply-withdrawal conduit from the lower portion of the lockhopper 
to the lower portion of the tank with a pump in the supply-withdrawal 
conduit for supply or withdrawal of liquid to or from the lockhopper for 
pressure adjustment. The solids-liquid separator chamber has an inlet in 
its upper portion in communication with a feeder means which is in 
communication with the lockhopper valved outlet. A solids outlet is 
provided below the inlet and passes from the separator chamber to the 
closed vessel. Within the solids-liquid separator chamber a screen 
separator means sized to retain the solid materials and permit passage of 
the liquid connects the separator chamber inlet and the solids outlet. A 
liquid reservoir is provided in the lower portion of the separator chamber 
and conduit means with pump means provides recycle of the liquid to the 
lockhopper. The solid materials and associated liquid are supplied by the 
feeder means to the upper portion of the screen separator means, the solid 
materials being retained on top of the screen separator means and passing 
out of the solids outlet into the closed vessel or reactor while the 
liquid passes through the screen separator means to the liquid reservoir 
at the bottom of the solids-liquid separator chamber for recycle to the 
lockhopper. 
The apparatus of this invention overcomes disadvantages of prior art 
apparatus for transferring solid materials between zones of substantially 
different pressures by providing removal of substantially all of the 
liquid from the solids prior to introduction into a reactor and prevents 
liquid used in the lockhopper system from being carried into a reactor if 
there is a pressure surge in the system. 
These and other objects, advantages and features of this invention will be 
apparent from the description together with the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, solids are stored in solids storage means 10 shown as 
an open bin-type hopper. The solids may be in particulate form of any 
desired shape or size for most expeditious use in any type of chemical 
reaction carried on in a closed pressurized reactor. Most usually, the 
solid particulates are in the order of 1 mm to 10 cm in diameter. Solids 
storage means 10 may be used to measure the quantity of solids desired. 
Solid transfer means is shown as endless belt 11 around a drive pulley and 
an idler pulley and positioned such that when in operation, the belt 
transfers solids from solids storage means 10 to lockhopper inlet valve 
12. It is seen that when solids transfer means 11 is not in operation, the 
endless belt provides a closure for the opening at the bottom of solids 
storage means 10, thus permitting opening of the main lockhopper inlet 
valves to the atmosphere. 
Lockhopper 16 is shown with inlet conduit 15 and two inlet valves 12 and 
14. Likewise, at the bottom of the lockhopper, outlet conduit 19 is shown 
with two outlet valves 17 and 18. Multiple inlet and outlet valves for 
isolation of the lockhopper are desired to assure satisfactory closure 
when required. Lockhopper inlet valve 12 is shown with purge means 13, a 
valved purge conduit. A liquid pressure seal is formed by the liquid in 
lockhopper 16. The liquid may be any liquid having a density lower than 
that of the solids being transferred and preferably, non-reactive with the 
solids. For many uses, water is a suitable liquid. A liquid feed tank 30 
has liquid supply conduit 31 to supply liquid to the system from an 
exterior source. Liquid in liquid feed tank 30 may be supplied to 
lockhopper 16 by pump 32 in liquid supply-withdrawal conduit 33, or liquid 
in lockhopper 16 may be withdrawn through supply-withdrawal conduit 33 by 
pump 32 to liquid feed tank 30 to provide the desired pressure 
compensation in lockhopper 16. Liquid return conduit 34 is shown from the 
upper portion of lockhopper 16 to liquid feed tank 30. Liquid return 
conduit 34 provides for passage of liquid displaced by solids in 
lockhopper 16. 
Lockhopper outlet conduit 19 supplies solids from lockhopper 16 to feeder 
means chamber 20. FIG. 1 shows screw feeder 21 activated by motor 22 
supplying solids from the bottom of lockhopper 16 to the upper portion of 
solids-liquid separator chamber 23. It is seen that when the lockhopper 
outlet valves 17 and 18 are opened, liquid from lockhopper 16 flows into 
feeder means chamber 20. 
FIG. 2 shows another embodiment of a feeder means useful in the apparatus 
of this invention. FIG. 2 shows feeder means chamber 20, representing the 
same feeder means chamber 20 as shown in FIG. 1 and enclosing continuous 
belt feeder 40 trained over belt drive wheel 42 and belt idler wheel 43. 
Continuous belt feeder 40 has spaced buckets 41 which convey solids from 
the bottom of feeder means 20 to the upper portion of solids-liquid 
separator chamber 23. 
Solids-liquid separator chamber 23 has screen separator means 24 leading 
from the solids inlet in the upper portion of the chamber to the solids 
outlet to the pressure vessel in the lower portion of the chamber. The 
screen separator means is sized to retain the solid particulates on its 
upper surface and permit passage of the liquid to a liquid reservoir 
portion in the lower portion of the separator chamber. By the terminology 
"screen separator means" is meant any perforated material, formed 
material, woven material and the like, which provides through passageways 
for the liquid to the lower portion of the solids-liquid separator chamber 
while retaining the solid particulates and guiding them to the solids 
outlet. The solids-liquid separator chamber separates substantially all of 
the liquid from the solid particles by the tumbling, rolling action of the 
particles. Removal of associated liquid from the solid particles is 
important in many instances where as low as a few percent liquid carried 
over into a pressurized reactor seriously affects the reaction. Further, 
in prior lockhopper reactor feed systems not having solids-liquid 
separation as the apparatus of this invention, pressure or 
de-pressurization surges would cause liquid to be carried into the reactor 
and frequently necessitate shutdown and cleanout of the entire system. The 
solids-liquid separation step of the apparatus of this invention also 
makes possible handling of smaller particles than prior lockhopper feed 
systems. The solids-liquid separator also provides flexibility in allowing 
use of various feeder means from the bottom of the solids-liquid 
containing lockhopper to the pressurized reactor, such as the continuous 
belt feeder with buckets as illustrated in FIG. 2. 
In operation, the lockhopper and feeder means are filled about halfway with 
liquid. The lockhopper outlet valves are closed, the lockhopper inlet 
valves are open, and solids are fed into the lockhopper. As the solids 
drop into the lockhopper they collect in the lower portion and the liquid 
displaced rises to the upper portion and if there is excess liquid, it 
returns to the liquid feed tank. The lockhopper inlet valves are then 
closed and the pressure within the lockhopper adjusted by supplying or 
withdrawing liquid by pump 32. When the pressure differential between the 
reactor and the lockhopper is compensated for, lockhopper outlet valves 
are opened and the solids drop and are fed by the feeder means to the 
solids-liquid separator. The liquid level in the feeder means and 
lockhopper is maintained by pump 32 at a sufficient height to prevent 
backflow from the reactor into the lockhopper. When the solids have been 
completely fed to the solids-liquid separator, the lockhopper outlet 
valves are closed and the lockhopper inlet valves are opened and the cycle 
repeated. Continuous solid feed may be achieved by having multiple valved 
lockhoppers used in parallel to feed the feeder means. 
The apparatus of this invention may be built of any suitable materials 
known to the art providing desired structural properties and resistance to 
corrosion and abrasion of the materials involved. The lockhopper valves, 
solids transfer means and feeder means may all be motor operated and 
together with pumps 32 and 36, electronically controlled to provide a 
completely automatic operation. Techniques for providing such automatic 
operation are well known in the art and apparent to one reading this 
disclosure. 
While in the foregoing specification this invention has been described in 
relation to certain preferred embodiments thereof, and many details have 
been set forth for purpose of illustration, it will be apparent to those 
skilled in the art that the invention is susceptible to additional 
embodiments and that certain of the details described herein can be varied 
considerably without departing from the basic principles of the invention.