T>DE ^rj/^^-Ta

Paraho Development C o r p o r a t i o n 101 South Thi rd

E n t e r p r i s e B u i l d i n g , S u i t e 300 Grand J u n c t i o n , Co lo rado 81501

- D I S C L A I M E R .

This book was prepared as art account of work sponsored by an agency of ihe United States Government

^Tfl ' h e U n ' l e d S ' a , e S G o v e r n m e m n o r dnV ^ency thereof, nor any of their employees, makes any "" o r , m P | l e d - o r assumes any legal liability or responsibility for the accuracy

usefulness of any information, apparatus, product, or process disclosed, or it infringe privately owned rights. Reference herein to any specific service by trade name, trademark, manufacturer, or otherwise, does

completeness, represents tha commercial product, process,

necessarily constitute or imply its endorsement, recommendation, or favoring by the United

TlXll G ° v e ™ m e m °rp

anV^gencv thereof. The views and opinions of authors expressed herein do not

any agency thereof. * reilecl those of the United States Governm

C r i t i c a l I t ems I d e n t i f i c a t i o n

T o p i c a l Repor t — Task 1 1

PARAHO OIL SHALE MODULE

O c t o b e r , 1981

This document is PUBLICLY RELEASABLE

Authorizing Official Date: I/9.L/4L?

Work Per formed Under C o n t r a c t :

..DE-FC03-80ET1 410.3

Des ign P l a n f o r D e m o n s t r a t i o n of a S u r f a c e O i l S h a l e R e t o r t i n g Module

#

#

<&> DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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TABLE OF CONTENTS

Section

1 1.0

11.1

SUMMARY—CRITICAL ITEMS

MINE AND PROCESSED SHALE AREAS

Page No.

i

11 .1

1.1 Mine Access 1.2 Mining System 1.3 Mine Classification (Gassy vs. Non-Gassy) 1.4 Mine Classification (Dry vs. Wet) 1.5 Resource Extraction 1.6 Bench Drilling (Upper and Lower) 1.7 Muck Removal (Underground) 1.8 Muck Removal (To Surface) 1.9 Mine Ventilation 1.10 Roof Bolting 1.11 Roof Monitoring 1.12 Scaling 1.13 Blasting 1.14 Primary Crushing 1.15 Processed-Shale Transport 1.16 Processed-Shale Retaining Structure

ABOVEGROUND PROCESS AREAS

1.2.1 Hot Conveyor Belts 1.2.2 Rotary Feeder Valves 1.2.3 Electrostatic Precipitator & Oil Recovery 1.2.4 Oxygen Analyzers 1.2.5 Safety Water Supply 1.2.6 Bearing Life 1.2.7 Mist Eliminator for Middle Gas Distributor 1.2.8 Refractory Selection 1.2.9 Instrumentation - Thermocouples 1.2.10 Grates 1.2.11 Air/Gas Distributors 1.2.12 Installed Spares 1.2.13 Tripper Conveyor Component Changeout Time 1.2.14 Tubesheet Flushing 1.2.15 Start-Up Procedure 1.2.16 Shale Dust as a Fire Hazard 1.2.17 Electrical Grounding 1.2.18 Operating Area Reduction Within Retort 1.2.19 Recycle-Gas Moisture Content 1.2.20 Product Oil/Water Separation 1.2.21 Recycle Gas Blowers 1.2.22 Scale-Up of Plant Components 1.2.23 Crusher Design ;.. 1.2.24 Screening 1.2.25 Recycle Gas Cooling 1.2.26 Raw Shale Feed Control 1.2.27 Retort Support Structure

BLR

Section

1 1 .3

TABLE OF CONTENTS cont.

ENVIRONMENTAL/RESOURCE

Page No.

11.28

1.3.1 Air Pollution Control (Sulfur & Nitrogen) 11.28 1.3.2 Fugitive Dust Abatement-Surface Plant 11.29 1.3.3 Fugitive Dust Abatement-Mine 11.30 1.3.4 Processed Shale Treatment 11.30 1.3.5 Wastewater Treatment 11.31 1.3.6 Hazardous Process Wastes 11.31 1.3.7 Water Requirements 11.32

- l a o A l —

11.0 SUMMARY - CRITICAL ITEMS

A critical item in the demonstration plant is one that has a

notable impact on plant performance. Generally, these items have

required that decisions be made throughout the course of the Phase

I work to facilitate design work and preparation of estimates. The

approach taken in each case represents the engineer's best

judgement, based on both experience and timely evaluations.

Certain critical items were identified as important enough to

justify formal trade-off studies to document the alternatives

considered and to justify explicitly the selected design. These

key trade-offs are included in the Topical Report for Task 12.

The listing which follows (Table 11-1) summarizes the critical

items addressed during the phase I work. This tabulation covers

both the critical items and the area of performance affected.

A brief description of each critical item is included in the text

of the Task 11 Topical Report.

i

CRITICAL ITEMS REL

1 MINE AND PROCESSED'SHALE AREAS

11.1.1 Mine Access 11.1.2 Mining System 11.1.3 Mine Classification (Gassy vs.

Non-Gassy) , 11.1.4 Mine Classification (Dry vs. Wet) 11.1.5 Resource Extraction 11.1.6 Bench Drilling (Upper and Lower) 11.1.7 Muck Removal (Underground) 11-1.8= Muck Removal (To Surface) .11.1.9 Mine Ventilation 11.1.10 Roof Bolting 11.1.11 Roof Monitoring 11.1.12 Roof Scaling 11.1.13 Blasting 11.1.14 Primary Crushing 11.1.15 Processed Shale Transport •11.1.16 Processed Shale Retaining

Structure (Surface)

2 ABOVEGROUND PROCESS AREAS

11.2.1 Hot Conveyor Belts 11.2.2 Rotary Feeder Valves 11.2.3 Electrostatic Precipitators

and Oil Recovery System 11.2.4 Oxygen Analyzers 11.2.5 Safety Water Supply 11.2.6 Bearing Life

PERFORMANCE IMPACT

CRITICAL ITEMS RELIABILITY MAINTENANCE PROCESS ENVIRONMENTAL SAFETY COST

11.2.7 Mist Eliminator at Middle A/G

11 11 11. 11 11 11

11. 11 I 1 1 1

1 1 11 I 1. 11. 11 11 1 1 11. 11,

Distributor 8 Refractory Selection X 9 Instrumentation - Thermocouples X 10 Paraho Feeders (Grates) X 11 Air/Gas,Distributors X 12 Installed Spares X 13 Tripper Conveyor Component X

Changeout time 14 Tubesheet Flushing 15 .Start-Up.Procedure X 16 Shale Dust as a Fire Hazard IT Operating Area Reduction X

within the Retort 18 Recycle Gas Moisture Content 19 Product Oil/Water Separation X 20 Recycle Gas Blowers X 21 Scale-Up of Plant Components X 22 Crusher Design X ,23 Screening X 24 Recycle Gas Cooling ,25 Raw Shale Feed Control X 26 Retort Support Structure X

X X X X

11.3 ENVIRONMENTAL/RESOURCE

11.3.1 Air Pollution Control (Sulfur and Nitrogen)

11.3.2 Fugitive Dust Abatement -Surface Plant

11.3-3 Fugitive Dust Abatement -Mine

11.3.'I Processed Shale Treatment 11.3.5 Wastewater Treatment 11.3.6 Hazardous Process Wastes 11.3.7 Water Requirements

X

X

X

X X X X

O'J'ljK

—laoaM — 11.1 MINE AND PROCESSED SHALE AREAS

11.1.1 Mine Access

The method of accessing the mine is a key decision affecting

the efficiency, safety, and cost of the mining operation.

The system selected consists of inclined-conveyor shale

haulage, vertical-shaft access for men and material, and

heavy-equipment access through a ventilation adit. This

item is fully evaluated in a trade-off study (see Topical

Report, Task 12, Trade-Off Studies).

11.1.2 Mining System

Consideration was given to the use of underground mining

systems other than room and pillar, such as: block-caving,

long walling, boring or ripping, stoping, etc. However,

various factors, including the physical nature of western

shale, the vertical dimension of the projected mining zone

and its depth below the surface, the requirements of the

Paraho retorting method (minimization of minus 1/2-inch

material), and environmental restrictions related to

long-term stability of mined-out areas, effectively ruled

out all proven methods of extraction except room and

pillar.

11.1.3 Mine Classification (Gassy vs. Non-Gassy)

Available-data indicate that methane occurs sporadically and

in very small amounts in the projected mining zone in the

Section 32 locale. Since there is no assurance that the

mine can be operated as a non-gassy mine throughout the life

of the program, all mining activities meet established

ventilation requirements according to MSHA.

11.1

—laraM!

11.1.4 Mine Classification (Dry vs. Wet)

Core hole information indicates minor occurrence of

subsurface water in the stratigraphic interval penetrated by

the proposed mine workings. Thus, a dry mining environment

is expected and little or no water will be pumped to the

surface.

11.1.5 Resource Extraction

The shale resource to be mined is a strata 60 foot high. A

two-bench mining system has been selected since equipment is

not available for single pass mining.

11.1.6 Bench Drilling (Upper and Lower)

For purposes of bench drilling underground, vertically

oriented holes are usually the simplest method if: 1) the

mining configuration provides adequate headroom; 2)

horizontal dimensions are sufficient to allow rapid

maneuvering and set-up by the drilling unit; and 3) minimal

amounts of formation water are encountered in the drill

holes. All three requirements characterize the mining plan

for Section 32. A pattern of vertical holes was chosen as

the best means of drilling and blasting the lower-bench

portion of the mined interval.

In some instances, bench blasting and rubblizing by means of

horizontal drill holes may have a less-damaging effect on

adjacent pillars. Compared to vertical drilling, horizontal

drilling is less efficient and control of drill-hole

orientation is more difficult.

11.2

~taEaMi—— :

11.1.7 Muck Removal (Underground)

A trade-off study was conducted to select equipment for

upper-bench loading and hauling. The study indicates that a

front-end loader and truck system is superior to a

load-haul-dump (LHD) and conveyor system. That result led

to the predictable conclusion that an expansion of the same

system would be most appropriate for the lower bench loading

and hauling.

11.1.8 Muck Removal (To Surface)

The muck removal system from underground (inclined conveyor)

is an integral part of the mine access system that was

chosen by means of a trade-off study (see Topical Report,

Task 12, Trade-Off Studies).

11.1.9 Mine Ventilation

An exhaust fan ventilation system was chosen for the

project. This eliminates the need for the airlocks required

with positive pressure systems. Intake airways (the intake

adit and the service shaft) are to be used as accessways for

men and equipment. The installation of airlock doors in

these accessways would impede traffic and be an additional

maintenance item. A positive pressure system would also

require fan .installations on both the intake adit and the

service shaft in order to ensure fresh-air streams in both

locations.

Three types of stopings are contemplated for the mine:

permanent concrete stopings, temporary brattice stopings,

and air curtains. Concrete bulkheads will be used as

permanent stopings to conform with MSHA requirements for

'• :

11.3

—laiaUS

such stopings. Stopings made of brattice instead of

concrete or metal were chosen for use within the mining

panels. Brattice stopings are much cheaper and can be more

easily repaired or replaced if blasting damage occurs. Air

curtains will be used in lieu of airlock doors as a

drive-through stoping for the lower level truck haulage

crosscuts.

11.1.10 Roof Bolting

Except for shaft collars and adit portal areas, roof bolting

is the only means of roof or wall support that is considered

in the mine design study. Past experience in oil shale

mining has shown that no other means is needed.

Split-set bolts are recommended as they provide continuous

anchorage throughout the length of the bolt. Conventional

bolts provide only point anchorage. The support capability

of each bolt is dependent on the type of material the anchor

rests in.

The length of the bolts and the pattern in which they are

placed is determined by the results of the

rock-characterization study, the lateral dimensions of the

mine openings, and an allowance for an acceptable margin of

safety.

11.1.11 Roof Monitoring

Mine roof monitoring will be largely confined to the

installation and periodic checking of sagmeters at key

intersections. Other types of rock monitoring equipment

such as borescopes, extensometers, strain gauges, and

geophones are available if needed.

11.4

~~laucaMl

1 1 . 1 . 1 2 S c a l i n g

Scaling will consist of systematically raking and prying

loose slabs of rock from the mine walls and (to some extent)

from the roof, following the drilling, blasting, and mucking

cycles in each heading. The proposed unit will have a

hydraulically operated, telescopic boom equipped with a

ripper tooth capable of prying upward, downward, and

horizontally. No other viable alternative for accomplishing

the work is known.

As a followup to scaling, periodic visual wall examination

and roof monitoring, featuring the use of a remotely

controlled aerial platform, will be conducted in active

parts of the mine. This function will include some hand

scaling with pry bars.

11.1.13 Blasting

Blasting will be accomplished by the use of a bulk mixture

of ammonium nitrate and fuel oil (AN/FO). Other blasting

agents are available but AN/FO is the cheapest and safest

and has proved to be an effective oil shale blasting agent.

Single and dual high-strength primers, electric blasting

caps and detonating cord (for lower-bench downholes) will

make up the blasting array. This configuration is the most

reliable as. well as permissible if a gassy environment

should develop.

11.1.14 Primary Crushing

For the demonstration module an optimal method of primary

crushing must be tailored to the physical characteristics of

the mined material and to the retorting restrictions.

11.5

—EucaJjS Section 32 oil shale is a tough, abrasive sedimentary

(layered) rock of varying degrees of resiliency that must be

crushed to less than 12 inches with minimal degradation

below 1/2 inch. Although crushing data related to western

oil shale are lacking, enough is known to state that a

toothed-roll crusher creates less fine material than any

other type of crusher. Crushing units compatible with

module requirements are available; so a toothed-roll primary

crusher was chosen.

11.1.15 Processed Shale Transport

The processed shale disposal plan requires that the material

be transported to the disposal site, spread systematically

throughout the site, and compacted. The use of scrapers for

the final stage of transport is the most feasible, because

it provides controlled spreading by the hauling units. By

using a system of constantly varying routes, the same units

will provide most of the needed compactive effort in the

formation of the disposal pile. At the retort end of the

disposal system, belt conveying is considered to be most

reliable, the least expensive, and the most compatible with

the final delivery system, and it generates the least dust.

11.1.16 Processed Shale Retaining Structure (Surface)

For economic and environmental reasons (see Topical Report,

Task 12, Trade-Off Studies), rip-rap has been selected for

the facing of the processed shale retaining structure.

11.6

—iaraftiS 11.2 ABOVEGROUND PROCESS AREAS

11.2.1 Hot Conveyor Belts

The conveyor belts CO-2027 A & B are located at the bottom

of the retort discharge and serve to remove retorted shale

from the retort area. Normal operating temperature of the

conveyor belt is 295"F with a maximum design temperature of

395°F. The conveyor belts were designed to carry shale this

hot without adverse effects. The dust-collection system

also removes purge gas and dust from the immediate area.

This is done with hooded enclosures and skirtboards around

these two conveyors.

Each conveyor is designed to handle the full retorted shale

load. The installation of two conveyors increases operating

reliability.

The retorted shale will be removed from the retort in

essentially the same size distribution as the raw shale

entering the retort, some of which will be as large as three

inches. Surface temperatures should not exceed 295°F during

normal operation. under upset conditions, retorted shale

may exceed temperatures of 395UF, in which case water-sprays

on both the bottom and sides of the conveying belt would be

activated to prolong the life ,of the belt. Sprays will not

be necessary under normal operating conditions. in addition

to water sprays directed On the conveyor belting during

adverse conditions, the dust collection system blowdown

(from wet scrubbers) is deposited on the retorted shale

conveyors. This will also decrease the temperature of the

retorted shale.

In-house and vendor data were evaluated for proper selection

of belting material. Detailed engineering requisitions were

11.7

—SaEaft! written and quotations solicited from reputable suppliers to

meet operating conditions as specified. Quotations have

been received and evaluated to ensure proper

belting-materials selection.

11.2.2 Rotary Feeder Valves

The rotary feeder valves FE-2004 A through p are located at

the retort discharge below the retort hoppers and above the

retorted shale conveyors. These valves have dual functions.

The upper valve seals the retort from the downstream

equipment. The lower valve feeds the retorted shale

conveyors. Between the two valves, provisions are made for

injection of a purge gas. The design permits the use of

inert gas, air, or low pressure steam as purge gas.

The feeders are essentially the same as those used at the

Paraho Semi-Works except for the size. Paraho had

experienced bearing failures and excessive wear with seals

in the semi-works, but has worked with one vendor to develop

an acceptable, maintenance-free design. Care has been taken

to ensure that the valves supplied will incorporate the

design features developed for the semi-works. The valves

operate at a 50% volumetric fill factor in order to reduce

wear and shearing of retorted shale.

11.2.3 Electrostatic Precipitators and Oil Recovery

Four electrostatic precipitators (ESP) (Tags: M-4003 A, B,

C, D) are connected in parallel in the off-gas stream and

share equally in the gas flow. The purpose of these

precipitators is to.complete the separation of the oil

droplets from the gas.

11.8

-iaraMI The main design consideration with this system is to

maintain full retort production. Consulting with suppliers

experienced in similar applications has resulted in an

arrangement of four ESP's in parallel. This is the optimum

case for equipment sizing and operating requirements.

Normal operations consist of all four ESP's in operation;

however, three ESP's can handle 100% of the retort

production if one unit must be taken out of service. Other

components in the oil-recovery section, such as the

coalescer, recycle pumps, and knock-out drums, have been

duplicated in each train for operational flexibility.

11.2.4 Oxygen Analyzers

The oxygen content of the retort off-gas and of the gas in

the combustion zones in the retort will be monitored and

used to control the retort.

Oxygen content of the off-gas (O2 breakthrough) is related

to irregular pressure gradients in the combustion zone.

Adjustments in gas and air flows will be made to correct

this condition and obtain steady-state combustion. Total

pressure at the top of the retort will be controlled to

maintain steady-state operation.

To ensure continuous monitoring of oxygen, the analyzers

will be supplied with power from an uninterruptible power

supply.

11.2.5 Safety Water Supply

Safety-water supply will be integrated with the overall

plant water-supply system, which depends upon raw water

11.9

—EataMS supply from the White River . Raw-water pumps w i l l pump water from the- White River up to the p l a n t e l e v a t i o n . The water w i l l be?held in s to rage tanks for d i s t r i b u t i o n to the va r ious user sys tems.

-•The fixer-water supply isys-tem u t i l i ze - s a s e r v i c e water pump i: to ;maintain . sys tem-pressure and: both main ( e l e c t r i c ) and

s tandby ):(.diesel) f i r e - w a t e r pumps during emergency . c o n d i t i o n s . S ta r t ing ; :of- the f i r e - w a t e r pumps is'-' t r i g g e r e d

. ,. au tomat i ca l ly , by low rf i re : -water . system p r e s s u r e .

>. :-By; u t i l i s i n g - t h e . raw-water s t o r a g e -tanks as a source for

-f ir eh water yand/iSafeeFty syst«ms;,:uan-adequate supply of water : x i s ; assured? ;i-fUa. i p o t e n t i a l l y hazardous; cond i t ion a r i s e s . The • rawr7wateri;rsupply ipumpsiswild nnormalily smaitttarn : aosa t i s f a c to ry ^ s t o r a g e dejvel-cin-:the astorage :tanks;.-I S u c t i o n - l e v e l •:. l i m i t a t i o n s -fqrjneitheji p u r ^ ^ i l l i - p r e v e n t u l t i m a t e drawdown

b.y:ot;her sys tems.

.•:--,.::;-: =:Fire^wate:r--suppjly;:asystHiBSi have! gbeeTi rdesigned -to allow for

•;•••;: f i r e .^hydrantiS:caiid morcitorsnatr ;key loxrations -.throughout the

-.. ,, surfia^ie?sfaciil:iitijes..: tGKite:ria vused^lfox estab.li.s;hing these • : i • locations-: have! been- usedr-in :^^frinery.:;safety--systems for

s e v e r a l y e a r s .

11 .2 .6 Bearing Life

'<-:v;.- cBe^ri^sxareK-key-:^^ of

-;- !T;M j ro ta t ing . equipment and/ machinery;::': EquipjmentKoesigri and

, s e l e c t i o n rfor t h i s r p ro jec t ; adheEest to ••conventional r e f i n e r y p r a c t i c e s . ;Both custom-designed components and s tandard bea r ings have a minimum Ite-n-year l i f e u n d e r normal; main tenance . , ' This a l so vconformsvwith'AFBMAB-1 0 r a t i n g c r i t e r i a ; and inc ludes an accep tab le margin of sa fe ty to minimize f a i l u r e s during? upset o p e r a t i n g c o n d i t i o n s .

11.10

"laEaWKr Extensive use of "taconite" grease-purged bearing seals

should reduce maintenance in areas of severe service.

11.2.7 Mist Eliminator for Middle Gas Distributor

The electrostatic precipitator (M-3001) is located in the

recycle gas stream to the middle air/gas distributor. This

precipitator ensures that any oil mist carry-over in the

off-gas would be removed from the recycle gas stream, thus

preventing potential coke buildup on the retort middle

air/gas distributor orifices. In the semi-works it was

noted that during recycle overload conditions, some oil mist

was carried over and coked on the distributor.

11.2.8 Refractory Selection

Refractory selection is based on characteristics of oil

shale recycle gas and products of combustion within the

retort. Normal temperatures in the range of 1200"F to

1400"F are expected, with possible excursions to 1800T or

1900"F. Combinations of refractory and insulation have been

used in the roof, floor, and walls of the retort to keep

casing temperatures at an acceptable level.

Brick and block designs are used in this application. The

brick is retained by mild steel clips and alloy-steel

anchors. The roof and overhead portions of the retort are

installed in place using a gunned refractory containing

stainless-steel needles for interwoven strength. This

practice has been successful in other industries.

The design features ensure suitable expansion/contraction

joints in all vertical walls. Tube sheets have similar

provisions for temperature variations.

11.11

-laraftB 11.2.9 Instrumentation - Thermocouples

The most critical control requirement for retort operations

is successful temperature measurement and profiling. For

the demonstration module more than 600 thermocouples have

been included, each at a different point in the retort.

This many thermocouples is more than adequate to provide

redundancy for the temperature profiles in the various zones

of the retort. The retort can be operated even if some

thermocouples fail. The thermocouples can also be replaced

during operations if necessary. The extra thermocouples

also provide alternate locations that can be used for zonal

control.

11.2.10 Grates

The Paraho grate is a reciprocating mechanical device which

controls the volumetric flow rate of retorted shale leaving

the bottom of the retort. It also ensures a uniform rate of

descent of shale in all areas of the retort's cross

section.

The module retort grate is divided into 16 independent

sectiona located below the bottom gas distributors. Each of

these sections has five retorted shale discharge openings

between the bottom gas distributors, five retarder plates,

five pusher bars, and one pair of hydraulic cylinders. The

discharge openings, retarder plates, and pusher bars are

oriented longitudinally with the retort. The retorted shale

from two of the 16 grates drops into one of eight discharge

hoppers below the grates, i

11.12

-larsAB The retorted shale flows in the following manner: As the

retorted shale descends slowly from the main bed of the

retort, it passes through discharge openings between the

bottom gas distributors. The sloping sides of the bottom

gas distributors are the deflector or diverter plates which

cause the shale to flow through the discharge openings.

After the retorted shale lumps pass through the narrow

discharge openings they come to rest on the retarder plates.

The pusher bar on each retarder plate is reciprocated in a

motion less than the width of the discharge opening. A

volume of shale equal to the volume displaced by the

movement of the pusher bar falls from the edge of the

retarder plate and into the hopper below. Five pusher bars

are trussed together in a steel framework so that one pair

of hydraulic cylinders acting from opposite sides can pull

them back and forth in a reciprocating manner. The

controlled speed and stroke distance of the pusher bars

determine the flow rate of retorted shale from the retort as

well as the flow rate of raw shale through the retort. Wall

effects are compensated for by designing the grate so that

the volumetric displacement of retorted shale is somewhat

greater from the two retarder plates near the walls of the

retort than from the three center retarder plates.

The 16 sections are operated at about equal displacement

rates but act independently to control uniform longitudinal

temperatures in the retort! bed. Temperatures can be

fine-tuned by adjusting valves in the pipes leading to each

air/gas distributor.

11.2.11 Air/Gas Distributors

There are three levels of |air/gas distributors in the

retort. The lower distributor admits only recycle gas to

the retort. The middle and upper air/gas distributors

.

11.13

-|ara\H supply a mixture of air/gas to the shale bed. Orifices in

each distributor distribute the air and gas throughout the

shale bed. Uniform, repeatable gas distribution is critical

to stable combustion and retorting. The air/gas

distributors must perform this function while maintaining

their structural integrity.

The upper and middle air/gas distributors are insulated and

armor protected. A cooling water system for orifice cooling

is provided as a precaution against coking of the orifices

in the upper air/gas distributor. The bottom gas

distributor has provisions for injecting steam. This can

assist in the control of local temperature upsets and/or

maintaining constant moisture of the recycle gas.

The upper air/gas distributors will have control valves to

adjust the amount of air/gas mixture going to each end of a

distributor. Tests have been run on scale model facilities

to determine the optimum baffle position within the upper

air/gas distributors. These baffles are intended to ensure

reasonable temperature and pressure gradients across the

length of the distributor.

Expansion joints are supplied in the air/gas distributors to

minimize the transferal of thermal stresses to supporting

structures. Provisions have been made to allow for

incremental; removal of manifolds and distributors as

required during a .retort shutdown.

11.2.12 Installed Spares

• • ' ' • " '•• •' " ! V ' "

Spare equipment is provided throughout the plant to increase

the likelihood that the 90:% plant-operating factor can be

achieved. The selection of equipment items or systems for

which spare equipment would be provided represents a

judicious trade-off between expending capital and

11.14

-laiafyi maintaining operations. Industry practices and engineering

judgement prevail in such considerations. Installed spares

for the demonstration plant include:

One Spare Secondary Crusher

One Spare Secondary Screen

One Spare Tertiary Crusher

One Spare Tertiary Screen

One Spare Final Screen

One Spare Retorted Shale Conveyor

One Spare Pump for each Operating Pump

33% Spare Capacity in Oil/Gas Recovery Section

11.2.13 Tripper Conveyor Component Changeout Time

Tripper conveyor, CO-2025, is a key factor in retort

operations. The expense of adding a spare conveyor could

not be justified. Suitable design criteria have been

included to assure the 90% on-stream factor. These criteria

include additional tonnage capacity, direct connected speed

reducers, taconite seals, component service factors,

spare-part interchangeability, idler spacing and materials,

and belting-materials splicing methods. Further, the feed

hoppers on top of the retort have surge capacity to permit

continued retorting even in the event of a tripper failure.

11.2.14 Tubesheet Flushing

Solids buildup was experienced during the semi-works retort

operation at the above-bed off-gas collector. Operating

practice dictated periodic cleaning, using hand held hot-oil

or steam hoses. A commercial facility would require

excessive time to accomplish this by hand; therefore, a

mechanical flushing system is required.

11.15

"SaraMi An oil-flushing system has been included in the design to

flush the lower tubesheet. The function of the flush is to

permit in-place washing of the tubesheet to free shale fines

or solids which may be carried up with the retorted oil-mist

into a low velocity plenum chamber.

11.2.15 Start-Up Procedure

Semi-works operating experience and a thorough evaluation of

the particular, scaled-up needs of the module have been used

to develop the start-up procedure described below.

The Paraho Retort is designed to produce oil and gas from

sized oil shale. This is accomplished by controlled heating

of the shale and collection of the oil/gas mist for further

refining. The retorting is successful when the temperature

pattern within the retort has been established to an

acceptable predetermined, controllable profile.

At start-up, the retort is filled with oil shale, which is

then removed from the bottom at the rate of approximately

six inches of bed travel per hour. The oxygen content is

reduced to an acceptable level and the shale is preheated by

externally burning fuel oil and admitting the products of

combustion into the retort.' The heating medium is cycled

through the recycle gas equipment and flared as required.

This process is continued until the oil shale is heated to

approximately 70CTF.

When, the temperature is approximately 700"F, air preheated

via the start-up burner is introduced into the retort,

causing auto-ignition of the hydrocarbons. Once combustion

is confirmed, the shale drawn down rate is increased to one

11.16

-feraMl foot per hour and the gas/oil production begins. The

gas/air streams and grate speeds are gradually increased

until the predetermined temperature profile and product

stream-flow rates are realized.

11.2.16 Shale Dust As A Fire Hazard

Shale dust is generated as a natural consequence of crushing

and handling. These operations produce a shale in the

required retort feed-size range.

The main potential hazards of shale dust result from both

ignition sensitivity and explosivity. Results of ignition

and explosion hazards can be combined and expressed as an

"explosivity index". The index can then be compared to that

of Pittsburgh bituminous coal as a relative indication of

dust hazards. With Pittsburgh seam coal having a reference

value of 1.0, oil shale typically has an explosivity index

of 0.0001. In light of this, it was determined that

shale-handling areas can be classified as non-hazardous.

Further tests have indicated that oil shale dust in the

presence of hydrocarbons (such as retort gas) can be

explosive. This information is based on a report entitled

"An Evaluation of the Fire and Explosion Hazards of Oil

Shale Mining and Processing," prepared for the U.S. Dept. of

the Interior, by Tosco Corporation and Denver Research

Institute, 1978. For this reason, the area atop the retort

has been classified as Class I, Division II, and the

necessary electrical provisions have been included in the

design.

11.2.17 Electrical Grounding ,

Electrical grounding has been established in accordance with

general refinery practice.

1-1.17

"BaraMi The grounding system will be a loop-type system with

equipment taps. The system will include ground-driven rods

and bare copper cables throughout the plant. All electrical

equipment and process equipment will be grounded.

The electrical power system will consist of various levels

of high- and low-resistance grounding. The 13.8 kV will be

grounded, utilizing a 400 amp, low-resistance ground. The

4160-volt system will utilize 200-amp, low-resistance

ground, and the 480-volt system will utilize a high-

resistance ground of various ampere ratings. The main

grounding loop will utilize #00 cable, and process equipment

will use #2 stranded and annealed copper cable.

11.2.18 Operating Area Reduction Within the Retort

The demonstration module represents a considerable scale-up

of capacity from the semi-works. Therefore, having the

capability to isolate and operate a smaller section of the

retort may help in resolving start-up or operational

problems.

The retort design has been investigated for possible scaling

down during the operational phase to a capacity considerably

less than 10,000 barrels per day, utilizing the same grade

of oil shale. The investigations showed that the present

retort design theoretically permits independent operation of

a cell 1/8 the retort length.

To contain the oil shale, \a.

needed. This would require

refractory and steel work; - i

intermediate end wall would.

of the retort.

special brick wall would be

the removal of some existing

Operation utilizing this

preclude operating the remainder

11.18

-taraftll By utilizing three or more discharge hoppers it is possible

to evaluate the end-wall and straight-side effects for a

retort. Any less than that would result in the loss of the

sidewall effects and combine the end-walls into one

continuous variation for end-wall effects. The reduction of

size of the retort would considerably reduce the amount of

oil shale which would be used.

Retort support systems such as off-gas manifolds, gas supply

manifolds, recycle gas equipment, etc. require further

investigation to establish the number of components to be

onstream during reduced operations. Considering the modular

design and the spare capacity of downstream equipment, it is

likely that the equipment will be satisfactory for a

reduced-rate operation.

11.2.19 Recycle Gas Moisture Content

Provisions for adjusting the moisture in the recycle gas or

in the oil shale bed have been made by inserting

steam-injection tubes through the bottom gas distributor.

These steam-injection points have the capability of

adjusting individual zones of the retort for control of the

retort-bed temperature and optimizing moisture content of

the retort off-gas.

11.2.20 Product Oil/Water Separation

Achieving adequate oil/water separation after retorting is

critical in meeting product oil specifications.

The semi-works facility successfully used a stagnant

separation system (day-tanks) for separating water from

product oil. Because of tlhe relatively low capacity and

short operating life of the demonstration facilities, it is

not worthwhile investing in a more sophisticated separation

system than that used by Paraho at Anvil Points.

11.19

pL^i 1 Three day-tanks would permit a batched sequencing operation:

one is filling, one is settling, and the other is being

pumped out. Internal baffling in these day tanks permits

separate pumping of oil and water.

11.2.21 Recycle Gas Blowers

Recycle gas blowers were evaluated on the basis of capacity,

pressure relationship and vendor conventional designs.

Since the demonstration facility is not intended to utilize

unproven designs, various vendors were contacted for

evaluation of existing blower designs that can be used in

this service. Results of these discussions with vendors

indicated that the specified pressure flow-rate

relationships are taxing the existing capabilities of

centrifugal blowers when the total volume is put through one

blower casing. Alternates of this particular design are two

centrifugal blowers or one axial blower.

Since the axials have not yet been developed for this

particular service, severe cost penalties would be imposed

on the purchaser of this equpment in order to properly

design a compressor casing. A two-train system, which would

give spare-equipment capability to the recycle gas system,

has been determined to be the most practical. One of two

60%-capacity machines can support the retorting process at a

reduced rate when the second blower requires repairs.

Another consideration was a large, single-drive blower

(approximately 15,000 hp) in recycle gas service. It is

questionable whether the local power company could provide

suitable start-up inrush power for a single unit system and

the existing local power line capacity at 69 kV would have

to be increased to 138 kV.

11.20

"lataUS 11.2.22 Scale-Up of Plant Components

The increased capacity of the module has required that

certain items be scaled-up from the semi-works plant. The

increased retort size is the main change, although

supporting systems have obviously increased in size to match

the higher retort throughput.

The retort vessel itself is a direct scale-up in size of the

existing semi-works facility. Vertical dimensions and

retorting zones are identical to the semi-works. Horizontal

dimensions in width are increased from the semi-works

facility of approximately 8 feet in diameter to 24 feet in

width using the same air/gas distributor spacings as used in

the semi-works. The horizontal length of the retort has

been expanded to the minimum practical-size retort allowing

the same spacing of the air/gas distributors as used in the

semi-works facility. A more complete discussion of the

retort configuration is included in Task 12 Topical Report,

Trade-Off Studies.

The hopper feed system equipment is made up of standard

components used in the solids-handling industry.

The rotary valves at the lower end of the retort are sized

in accordance with those used by the existing semi-works

facility and are within the capabilities of manufacturers.

These are not off-the-shelf designs, but are considered

standard by many manufacturers. Sufficient volume has been

built-in to give performance equal to that of the

semi-works. Feed conveyor} components are based on

conventional solids-handling designs within their normal

capacities.

Recycle system equipment is based on conventional refinery

and coke-oven-type process designs. Compressors,

11.21

-fataM coalescers, knock-out drums, precipitators, etc., are based

on commercially available items which do not exceed limits

of previously proven equipment.

11.2.23 Crusher Design

Crushers are required in the surface plant to reduce the

minus 12" shale from the primary crusher to a size

distribution suitable for retort feed (nominally 3/8" to

3"). Maintaining retort feed and minimizing fines

generation are key design considerations in the crushing

systems.

Previous experience in crushing indicates that double roll

crushers are suitable for the demonstration facility. The

design incorporates a minimum number of stages to reduce

minus 12" shale to 3/8" to 3" with a minimum amount of

fines.

In order to accomplish this, double-roll crushers were

selected for secondary and tertiary stages of crushing. The

secondary stage would reduce the minus 12" shale to minus

6". The tertiary stage would reduce the minus 6" to 3/8" to

3".

Testing will be required to evaluate shale crushing

characteristics prior to procurement.

11.2.24 Screening

As with crushing, screening is a key operation to ensure an

acceptable shale size range for the retort feed.

There are three screening locations in the shale feed stream

to the retort. The first screening location is directly

upstream from the secondary crushers. These screens serve

11.22

QucahE to separate the 6" to 12" from the minus 6" shale. The plus

6" shale will be crushed and combined with the minus 6"

material downstream of the secondary crusher. Two screening

stations are located in this area with one operating and one

spare.

The next screening station is upstream of the tertiary

crushers. The purpose of these screens is to separate the

3" and larger shale from the 3" and smaller shale. This is

done through a double deck screen, which further separates

ths shale into two increments: 3/8" to 3" and minus 3/8".

This allows for the minus 3/8" to be sent to fines storage,

while the 3/8" to 3" (retort feed material) goes to the

blending site and the plus 3" goes to the tertiary crushers.

Crusher product is recycled back to the bin ahead of the

screen for closed circuit processing. In this lineup, three

screens are provided; two are normally operating and the

third is a spare. The closed-circuit system around the

tertiary crushers is designed to minimize generation of

minus 3/8" fines.

The third screening station is directly ahead of the retort

where blended shale is received. Three screen lines are

provided in this area; two are normal operation and one is a

spare. This location is a final or finish screening area to

ensure that all minus 3/8" particles are removed from the

retort feed.. The fines from this final separation are again

sent to fines storage. Single-deck screens are used in the

first station at,the secondary.crusher. Double-deck screens

are used in the tertiary-crusher area and for final

screening before retorting.

Woven-wire cloth has been specified with even-sided

openings. Quotations received indicate that a perforated

plate may be an acceptable alternate to the woven wire, and

crushing tests indicate that an oblong opening is more

11.23

-&tM desirable for splinters of prepared shale.

Screen selection, along with the crusher selection, should

be further evaluated by full-scale tests with potential

vendors.

11.2.25 Recycle Gas Cooling

Cooling of the off-gas external to the retort improves separation of the oil from the gas, reduces blower horsepower, reduces product gas volume, and cools the retorted shale.

The current design cools the gas/mist by oil-washing in the

knockout drum with cooled-oil circulation from the

coalescer. Further cooling upstream of the gas compressors

may prove advantageous in future designs. Obviously, the

benefits mentioned above (horsepower reduction, cooling of

retorted shale, etc.) must be contrasted with resulting

increase in capital cost and water required to achieve the

desired cooling.

11.2.26 Raw Shale Feed Control

Maintaining feed to the retort requires a fairly elaborate

mechanical system to ensure that shale is spread evenly

across the bed.

Conveyor #CO-2025 is equipped with a traveling tripper to

allow infinite discharge positions. The tripper itself is a

structure which runs on rails astride the tripper conveyor.

The belting for the tripper conveyor is reeved through the

tripper and thus provides a traveling discharge.

11.24

isucaJilS Both the tripper and a dust-collection car are without

traverse drives. They are towed by the rock distributor.

Shuttle conveyor #CO-2026, at normal tonnage, is 55% full

but the level of oil shale in it rises and falls dependent

on tripper movement.

The rock distributor is basically a bridge crane that spans

the width and travels the length of the retort. Atop the

bridge is the shuttle conveyor that can be indexed to any of

the four hopper rows. The rock distributor provides the

longitudinal movement, while the shuttle conveyor provides

the transverse movement across the area that is the top of

the retort.

Attached to the shuttle conveyor, and moving transversely

with the shuttle conveyor, is the traveling hopper. During

normal operation, the traveling hopper is kept half full.

To provide an equal volume discharge to all of the 320

compartments, regardless of the variable feed rate, and

still maintain a constant level in the traveling hopper, it

is necessary to vary the traverse speed of the rock

distributor.

As the rock distributor moves downstream (in the same

direction as the tripper conveyor), a volume of shale is

placed upon the shuttle conveyor. As the rock distributor

travels upstream, the shuttle conveyor carries a larger

volume.

Again, to equalize this uneven feed into the traveling

hopper with a constant discharge rate, it is necessary to

have the rock distributor travel at different upstream and

downstream speeds.

11.25

In addition to these obvious speed changes for the rock distributor, it is necessary to adjust the traverse speed to

account for the load fluctuations upon the tripper

conveyor.

The traveling hopper is mounted on load cells that sense the

level within the hopper and control the rock distributor

speed accordingly. This system is backed up by nuclear and

microwave systems that also read the level within the

hopper. In addition, sonic gages read the feed level at the

top of the retort on either side of the traveling hopper.

11.2.27 Retort Support Structure

The retort structure is a crucial design area because of the

special design and operating requirements of the retort

itself. These requirements include provisions for retort

expansion, air/gas distributor removal and rearrangement,

and accommodations of mobile tripper/shuttle arrangement.

The retort vessel is designed to be self-supporting in a

vertical direction, with its dead loads transmitted to

columns directly below it. All horizontal loading is to be

absorbed through structural steel external to the retort

itself. The retort vessel will be free to expand and

contract through thermal stresses separate from this support

structure.

Preliminary design for the support structure had allowed for

complete access to both side walls of the retort. During

detailed design, this provision resulted in box trusses

running the length of the iretort, with sections requiring a i '

19-foot by 21-foot box girder. This unit would require

excessive field fabrication and special handling for

transportation to the job site.

11.26

tamM Another design allows for a bay-type structure along the

length of the retort. This alternative permits future

expansion of the retort, as contrasted to the box structure.

Both alternatives were evaluated. The bay design proved to

be practical, more economical, easier to fabricate, easier

to ship to the job site, and easier to expand in the field.

Clearances required for the removal of the gas distributors

are acceptable.

The structure is designed to be satisfactory in the wind

zones and earthquake zones as established by The Uniform

Building Code. Provisions have been included to allow for

charge floor, its supported building and control systems,

and also access platforms, ladders, elevators, hydraulic

pump rooms, etc., at various levels throughout the elevation

of the retort.

11.27

—laoASS — 11.3 ENVIRONMENTAL/RESOURCE

11.3.1 Air Pollution Control (Sulfur and Nitrogen)

The Paraho Direct Heated Oil Shale Retorting Process

provides a low Btu fuel-gas by-product. This low Btu gas

contains 0.3% H2S (hydrogen sulfide) measured on a dry

basis. Of course, this H2S would convert to S02 (sulfur

dioxide) upon combustion. The gas also contains traces of

other sulfur compounds such as carbonyl sulfide, sulfur

dioxide, carbon disulfide, and mercaptans. While data on

the concentrations of these compounds is not conclusive, it

appears that sulfur emissions due to these trace

constituents should not be a problem. These sulfur

compounds will not be removed to any great extent in washing

processes.

Although specific regulations for SO2 emissions from shale

oil retorting facilities have not yet been promulgated, it

is obvious that the uncontrolled emission of more than six

pounds of SO2 per barrel is far too high and that

substantial reductions must be made. A target emission

factor of 0.3 pounds of S02 per barrel is realistic for

this project. Removal of about 98% of the H2S is

necessary if the suggested emission level is to be met.

Of the several processes examined, the Stretford Process

offers the lowest cost for H2S removal. The cost of

removing sulfur from Paraho- gas by this method is less than

half of that of the Alkazid; DIK Process and offers even

greater savings when compared to MDEA (mono and

diethanolamine) or ADIP (diisopropylamine), the other two

common processes that are reasonable for this application.

The Stretford Process renders sulfur less pure than that

from a selective absorption process followed by a Claus unit

(in order to produce sulfur from the concentrated H2S

11.28

-jacafyi

gas). Economics for the Stretford unit were calculated

assuming no value for the sulfur produced.

If the Stretford sulfur cannot be sold, it can be disposed

of at the same location as the retorted shale. As long as

the sulfur is produced in the form of cast blocks, rather

than finely divided powder which could be carried away by

wind, it should not be regarded as a dangerous waste.

Ammonia is removed from the product gas by means of a water

wash, which is adequate to meet projected emission

requirements.

11.3.2 Fugitive Dust Abatement - Surface Plant

Dust-abatement measures have been included throughout the

raw-shale preparation area and the retorted-shale removal

system. These are key systems to ensure that particulate

emission levels are met.

Six dust-collection stations have been provided to control

airborne dust generated in material handling. The bag house

locations have been selected to centrally locate the dust

collection points. The systems consist of dust collection

hoods, bag filters located in bag houses, exhaust fans,

rotary airlocks with screen conveyors, and discharge

stacks.

One dust collection station has been designed to collect

dust from wet air at the retort discharge. This system

consists of dust hoods, centrifugal fans with a water wash,

and the exhaust stacks.

Two additional dust collection stations have been designed

to collect fugitive dust and add moisture to both the

retorted shale and the raw-shale fines. These systems

11.29

—iaraMh consist of dust hoods, exhaust fans, cyclone separator with

water wash, and exhaust fans.

Water sprayed on the roads at the facility will suppress the

dust that could arise from them.

11.3.3 Fugitive Dust Abatement - Mine

Of the available mine-dust controls (including water spray,

baghouse, chemical suppressant, filtration, and reduced

velocity), emphasis was placed on the use of water sprays on

muck piles and automated sprays combined with wetting agents

at truck dumps, crushing stations, and transfer points. To

minimize gaseous pollutants, all diesel engine exhaust

systems will be equipped with catalytic converters or wet

scrubbers.

These suppressive methods are considered to be the simplest

and most reliable and are expected to confine mine-emission

rates to an acceptable level. For that reason, additional,

more costly methods of dust suppression are unnecessary.

11.3.4 Processed Shale Treatment

At issue are when and in what amounts to apply moisture in

the loading, hauling, spreading and compacting of processed

shale. Maintenance of acceptable levels of dust-emissions

will require dust suppression measures at all belt and bin

transfer points in the disposal system. Sprayed water is

recommended for dust-suppression for three reasons:

o The system is simpler and more cost effective than

baghouses or filtration systems.

11.30

—iaraMI

o Early introduction of moisture into the hot (about

300°F) waste product will exert a cooling effect which,

in turn, will enhance belt and tire life and improve

working conditions.

o A projected moisture content of seven percent will be

needed to attain the prescribed compaction standard in

the disposal pile, and twenty-two percent will be needed

to attain the maximum compaction standard required of

the disposal-area lining.

11.3.5 Wastewater Treatment

Wastewater treatment makes various process and sanitary

wastes suitable for direct use or disposal. A properly

designed wastewater treatment system makes possible "zero

discharge" disposal.

The sources of the water are process-contaminated runoff,

gas clean-up wastewater, oil-separation wastewater, process

wastewaters, boiler blow-downs, cooling-tower blow-down,

sanitary wastewater, water-treating waste and inorganic

contaminated runoff. These will be combined and treated

through equalization, aeration, clarification, disinfection,

and evaporation via disposal on the retorted-shale area.

11.3.6 Hazardous Process wastes

The disposal of hazardous wastes such as API separator

sludge, waste lubricating oil, biological treatment sludge,

and oil storage-tank residue may require an acceptable

hazardous-waste management program, transportation system,

and approved disposal site prior to disposal of such waste.

A hazardous-waste permit would be required from the State or

EPA before the waste is emitted. Therefore, identification

of hazardous wastes and development of a preliminary waste-

11.31

disposal plan will be results of the Phase I environmental

effort.

11.3.7 Water Requirements

The estimated water requirements for the plant are 609,120

GPD (0.94 cfs). The proposed source of water supply is the

White River under a statement of intent from the State of

Utah to provide 5,000 acre-feet per year. The construction

of the White River reservoir is pending BLM review and a

one-year study by the U.S. Fish and Wildlife Service of the

potential extinction of the endangered squawfish species.

In any event, a dam with sufficient reservoir capacity for

this withdrawal will not be built until 1985 at the

earliest.

To avoid dependence on the dam project, the current plan for

the module calls for drawing water from alluvial wells.

This approach also requires resolution of the squawfish

study before it can be implemented.

11.32