P.1 

OAR Box 1107 

Prepped by Ollie Stewart 

Document Number: 

45) IV-E-1 

Docket Number: 

A-81-21 

Printed 4/11/2008 3:03:46 PM Sheet 45 of 90 
P.2 

p-7 *' A-81-21 

CORPORATION IV-E-1 

MEMORANDUM 

DATE: December 21, 1984 

TO: W. Fred Dimmick, Standards Development Branch 

FROM: Karen K. Fidler, Radian 

SUBJECT: Meeting Report - Incinerator Bypass Discussion With Vista 

Chemical Company Representatives 

I. Purpose 

Representatives of Vista Chemical Company provided information on 

incinerator operations and incinerator bypass occurrences at their ethylene 

dichloride/vinyl chloride (EDC/VC) plant in Westlake, Louisiana. This 

information will be used to study the need for a control device bypass 

provision for the VC standard. The purpose of the meeting was to gain 

familiarity with EDC/VC process incineration system design and operations. 

II. Place and Date 

U.S. Environmental Protection Agency 

North Carolina Mutual Building 

Durham, North Carolina 

December 12, 1984 

III. Attendees 

Fred Din-mick, EPA/OAQPS/ESED/SDB 

Leslie Evans, EPA/OAQPS/ESED/CPB 

Bob Rosensteel, EPA/OAQPS/ESED/CPB 

Susan Wyatt, EPA/OAQPS/ESED/CPB 

Karen Fidler, Radian Corporation 

Jeff Shumaker, Radian Corporation 

Ron Bryan, Chief Process Engineer, Vista Chemical Company 

Joe Ledvina, Director, Environmental Activities, Vista Chemical Company 

IV. Discussion 

Prior to the meeting, EPA provided the Vista representatives with a 

list of information needs to serve as the basis for the meeting discussion. 

(See letter from Evans, L. to Ledvina, J., December 5, 1984, Docket No. 

).. Vista's response to each of the identified discussion items is 

summarized below. 

Progress Center/3200 E. Chapel Hill Rd./Nelson Hwy./P.O. Box 13000/Research Triangle Park, N.C. 27709/(919)541-9100 
P.3 

Vista began the discussion with a general description of their EDC/VC 

production facility in Westlake, Louisiana. Attachment A is a block flow 

diagram of the facility. In addition, the following general information was 

provided: 

- The Westlake facility was previously owned and operated by Conoco 

Chemicals. Since mid-1984, the facility has been owned and 

operated by Vista with the exception of the ship loading dock 

facilities which are leased from Conoco. 

- The ethylene and chlorine feedstocks for the process are normally 

obtained from neighboring Vista and PPG plants, respectively. 

- EDC is currently produced by an oxygen-based "balanced" process 

and is used primarily to produce VC at the Westlake facility; some 

EDC is sold. 

- Most of the VC produced at this location is transferred via rail 

to other Vista facilities where polyvinyl chloride (PVC) is made; 

the remainder is sold and transferred via pipeline, railcar or 

ship. 

Incineration System Design and Operation 

A primary and a secondary incineration system, each consisting of a 

John Zink incinerator, waste heat boiler, HCl absorber and caustic scrubber, 

were installed in 1978 to reduce VC emissions in exhaust gases to 10 ppm. 

The two systems are virtually identical except for some construction 

materials. Each system is capable of handling the vent gases generated 

under normal process operating conditions while operating at about 50 percent 

of the design heat input capacity. This leaves about 50 percent of the 

capacity of the operating incinerator available to handle vent gas surges. 

Periodically, liquid ends from the EDC purification process are burned along 

with vent gases in the incinerator. No significant operating problems are 

normally encountered while burning liquids. Liquids are not being.burned 

currently. The secondary system serves as a backup and is operated only 

when the primary system is down for maintenance, or in parallel with the 

primary incinerator during plant startups and shutdowns and during occasional 

ship loading. 

Design and operating parameters for each incinerator include the 

following: 

- Heat input rate (vent gas and natural gas combined) 

design capacity - 48 x 10 gBtu/hr 

normal operation - 25 x 10 Btu/hr 
P.4 

- Temperature 

adiabatic - 1600°C 

operating - 1315°C 

standby - 600°C 

- Firebox pressure 

maximum design - 70- 80 in. H„0 gauge 

normal operation - 20- 30 in. H-0 gauge 

- Vent gas 

nominal flow rate - 40,000 scfh (^11,000 scfh from the direct 

chlorination vent, 23,000 scfh from the light ends column 

vent) 

nominal heat content - 7,000 Btu/lb 

- Natu ral gas 

normal 

range -

input 

• 2.4 -

- 5 

12 

X 

X IO6 

Btu/hr 

Btu/hr 

- Steam production 

normal rate - 16,000 - 20,000 lb/hr (350 psi) 

- Maintenance 

annual cost - $500,000 

s 

Incinerator temperature is controlled by a water quench system 

consisting of six nozzles spraying steam condensate into the combustion 

chamber. The primary control parameter for the combustion air flow to the 

incinerator is the rate of steam produced by the waste heat boiler. In 

addition, there is an 02 monitor in the flue gas as a trim control. The 

natural gas input to the incinerator is adjusted manually as needed. 

Turndown capability can handle any vent flow; low vent gas flows are 

accommodated by increased natural gas usage. 

The secondary (or standby) incinerator is maintained at 600°C. At that 

temperature, it can be heated up and brought on-line in 10 minutes. Past 

operating experience indicates that a 900°C standby temperature allows the 

incinerator to be heated up in 5 minutes. A "cold start" requires 

25 hours. Approximately two-thirds (8 - 9 x 10 Btu/hr) of the natural gas 

requirement for both incinerators is used to maintain the secondary' 

incinerator on hot standby. Some steam is generated by the secondary 

incineration system while on standby. 

In the event the primary incinerator trips and cannot be restarted, 

vents are switched manually (from the control room) to the secondary system. 

At least 10 minutes are required to switch the vent gases to the secondary 

system. Usually, switching takes place in less than 30 minutes. A planned 

switch to the secondary incinerator for scheduled maintenance of the primary 

system can be performed without venting to the atmosphere. 
P.5 

Incinerator Bypasses 

As shown in Attachment A, all vents containing VC in the Westlake 

facility are ducted to the incineration system with the exception of the 

relief valve header. Other equipment vented to the incineration system not 

shown in Attachment A include pumps, agitator seals, and EDC intermediate 

and final product storage tanks. The VC-containing vents are separated into 

two vent headers, the dry vent header and the wet vent header (see Attachment B). Both headers are equipped with automatic pressure control valves 

which divert a portion or all of the vent gases away from the incineration 

system when necessary to an emergency vent scrubber. 

Process Upsets 

Pressure surges caused by a variety of process upsets are detected by 

pressure sensors upstream and downstream of the incinerator, which activate 

the bypass control valves. Incinerator bypasses typically have been caused 

by the following although other causes have been noted: 

Ethane contamination of the ethylene feedstock and air contamination of the chlorine feedstock causing high volume of vents in 

direct chlorination header, 

High concentration of contaminants in the crude EDC product 

causing high inerts or light ends vent volume in light ends column 

vent, and 

Manual venting during equipment purging operations. 

Incinerator bypasses caused by feedstock contamination are not readily 

predictable by the EDC/VC plant since these materials are obtained from 

outside of the plant. Vista has implemented procedures to minimize incinerator bypasses during equipment purging operations such as placing restrictions 

on manual vents and stressing operator communications during manual equipment 

purging. Operator errors causing incinerator bypasses are treated similarly 

to safety incidents. An investigation of the cause of the bypass is conducted 

to stress the seriousness of their occurrence and the importance of preventive 

measures. This is intended to provide the main plant operators with incentive 

to notify and work with the incinerator operators prior to venting so that 

vent gas surges can be accommodated. 

Incinerator Malfunctions 

Attachment C presents a complete list of conditions that result in 

automatic shutdown of the incinerator and subsequent bypassing of vent 

gases. When automatic shutdown of the incinerator occurs, Vista's procedure 

is to identify the cause of the shutdown and to attempt to restart the 

incinerator unless maintenance is needed to repair the incinerator. For 

instance, when a high temperature trip occurs, the incinerator can be 
P.6 

restarted after the fuel content of the vent stream is corrected. Temperature sensor failure, however, would require repair and vents would probably 

be switched to the secondary incineration system. In most cases, attempts 

to restart the primary incinerator are successful within 2 minutes. Consequently, with any given shutdown incident, the operator must make a judgment 

as to whether the 10 minute heat-up procedure for the secondary incinerator 

or the restart procedure for the primary incinerator is the most appropriate 

action to be taken to minimize the bypass duration. 

In addition, the primary incinerator occasionally requires shutdown for 

maintenance to alleviate burner plugging problems and leakage around water 

quench nozzles. Because burner plugging and quench nozzle leaks are usually 

detectable, a planned switch from the primary to the secondary incineration 

system can be performed without a bypass. 

In order to minimize vent gas bypasses due to incinerator malfunctions, 

During maintenance periods, the secondary incineration system is brought 

on-line to handle all of the vent gases. Maintenance of the secondary 

system occurs on an as-needed basis throughout the year. If possible, all 

incinerator maintenance occurs during n<»riods other than the annual plant 

turnaround. 

Other methods have been investigated for minimizing bypasses due to 

pressure surges and incinerator trips. For example, construction of a 

gasholder to be used as a vent gas surge tank has been considered. However, 

it was determined that containment of a typical vent stream for a 10 minute 

period would require a 40 foot diameter vessel constructed of exotic 

material. Also, there are safety considerations. On this basis, the 

alternative was determined to be unjustifiable. 

Method for Estimating VC Emissions During Bypasses 

The amount of VC discharged to the atmosphere during incinerator 

bypasses is currently estimated by Vista for reporting purposes. (Earlier 

this year, Louisiana began requiring VC plants to report bypass incidents 

and associated VC emissions on a quarterly basis.) Bypasses are detected by 

flowmeters downstream of the control valve which record the duration of the 

bypass. Estimates of VC emissions during bypasses are based on the 

following: 

Results of a general material balance (updated periodically by the 

process engineering group) on the dry and wet vent headers assuming 

design capacity ratioed for actual production, 

Whether a full or partial bypass occurred, and 

Bypass duration. 
P.7 

VC Monitoring 

VC monitoring points are located in the incinerator stack as part of 

the multipoint VC monitoring system operated in the plant. Because the 

current multipoint monitoring system is not capable of operating over the 

wide range of VC concentrations and operating conditions likely to occur in 

the incinerator bypass streams, these streams are not monitored. 

Impact of Oxychlorination Vent 

Conversion of the EDC production process in 1983 from an air-based to 

an oxygen-based process resulted in elimination of the oxychlorination vent. 

(Currently, roughly about 6,000 lb/hr of purge gases from the oxychlorination 

reactor containing 85 percent ethylene and 15 percent inerts are vented to 

the direct chlorination reactor where the ethylene is reacted; the direct 

chlorination.reactor vents to the incinerator.) Consequently, all VCcontaining exhaust gases in the Westlake facility are required to meet the 

10 ppm standards of the VC standard. The inerts from the oxychlorination 

vent stream comprise about 40 to 50 percent of the direct chlorination' 

reactor vent. 

VC Emissions During Startup/Shutdown 

Vista's plant startup/shutdown procedures normally require both 

incinerators to be on-line throughout the startup/shutdown sequence. This 

procedure significantly reduces the risk of bypasses during startup/shutdown 

operations. 

Incinerator Bypass History 

Attachment D summarizes the bypass history for the Vista/Westlake 

facility for the period January through November 1984. The percent bypass 

time given in Attachment D refers to the percentage of plant operating hours 

(i.e., excluding plant turnarounds) that partial or complete bypasses 

occurred. 

In addition, the following information on bypass durations was provided 

for the period January through November 1984. 

Sixty percent of bypass incidents last less than 10 minutes, and 

the majority of these are 2 to 5 minutes in duration. 

Twenty-one percent of bypass incidents last 10 to 30 minutes. 

These incidents generally require switching to the secondary 

incinerator. 

Twenty-one percent of bypass incidents were 30 minutes or longer 

in duration. The majority of these bypasses were due to 

mechanical failures or power outages which prevented operation of 

either incineration system. 
Key 

a) 

o 

+•> 

•x. 

— Continuous Vent 

— Intermittent Vent 

Chlorine 

Ethylene• 

, Direct 

Chlorination 

Vent 

Direct 

Chlorination 

EDC 

TT 

Oxy Vent 

Purge Gas 

Oxygen -

Ethylene. 

Oxychlorination 

Vent i Light Ends 

Column Vent Vent 

EDC 

Washing 

EDC 

Purification 

Steam 

Stripper 

Water to 

Effluent 

Treatment 

EDC Light 

Ends 

_SJtor.age 

Pure 

EDC 

Uncracked Recycle EDC 

u EDC 

Cracking 

Vinyl 

Purification 

Vinyl 

Chloride 

HCl 

Oxy 

Shutdown 

Vents 

Relief 

Valves 

Vent 

Scrubber 

Main Plant 

Vent Stack 

Note: *A11 dock facilities owned and operated by Conoco Inc. 

tlncineration 

1 System 

I Non-point source 

I emissions, Manual 

I venting 

Incinerator 

Vent Stack 

Ship 

Loading 

1 

Railcar 

Loading 

Carbon 

Bed 

Ship 

Vent 

Dock 

Vent Stack* 

Pipeline 

Vent 

Recovery 

System 

VISTA CHEMICAL CO. 

VCM PLANT 

FLOW DIAGRAM AND VENT 

IDENTIFICATION 

RB 

11-30-84 
VCM PLANT VENT HEADER SYSTEM 

CD 

C 

a> 

E 

r—• 

o 

VCM 

Recovery 

System 

Vent 

Dry Vents. 

Tank Farm 

Vent 

Wet Vents 

Dry Vent 

KO Pot 

Wet Vent 

KO Pot 

Relief Valve. 

Header 

Relief 

Valve KO 

Pot 

""*"" Incinerators 

~sIncinerator 

Vent Stack 

Main Plant 

Vent Stack 

Vent Scrubber 

RB 

11-30-84 
P.10 

Attachment C 

VII. Shutdown System 

The burner management system contains interlocks which automatically 

shutdown the incinerator. The conditions which activate shutdown are: 

1. High firebox temperature (1,590°C) sensed by both temperature 

switches, TSDH-901A and TSDH-901B. 

2. Low steam drum level (2'-2") sensed by both level switches, 

LSDL-905A and LSDL-905B. 

3. High gas temperature in the HCl absorber sensed by both TSDH-908 

(120°C) and TI-907 (230°C). 

4. Low primary combustion air flow rate (2,000 SCFM) sensed by both 

flow switches, FSDL-926A and FSDL-926B. 

a. Low standby air flow rate (200 SCFM) sensed by flow switch, 

FSDL-945. 

5. Flame out sensed by both main flame scanners, XI-901A and XI-901B. 

"6. Flame scanner failure sensed by both main flame scanners. 

7. Manual shutdown at the main control panel. 

8. Manual shutdown at the burner management panel. 

9. Power outages of more than 3 seconds. 

10. High temperature or level (.low), in the flame arrestor. 

The shutdown condition that caused shutdown is identified by a flashing light on the main control room annunciator panel. Prior to 

reaching any of the automatic shutdowns, warning alarms and lights 

are indicated on the main control board annunciator panel and on 

the burner management panel. Warning alarms and shutdown conditions 

are discussed further in Section VII.B. 

A. Shutdown Sequence 

Whenever the incinerator shuts down, the following actions occur 

automatically. 

1. Natural gas block and bleed valves, SSOV-906A.B, and C, are 

de-energized which forces the valves to their failure positions (block valves-> closed, bleed valve-> open). 

106 -
VISTA CHEMICAL VCM PLANT 

INCINERATOR BYPASS HISTORY (1) 

p.n 

/•.ttaclimoirt J 

Cause 

High Vent Pressure 

Flame-Out 

Mechanical Failures 

Power Failure 

TOTAL 

No. Of 

Bypasses 

22 

13 

4 

48 

Bypass 

Hours 

5.5 

4.2 

1.8 

3.1 

14.6 

% Bypass 

Time 

.065 

.050 

.020 

.036 

.171 

Avg. Lbs. 

Per Bypass 

6.0 

8.2 

5.0 

20.0 

Note; 

The above data is for illustrative purposes only and may not necessarily 

reflect future operation. 

(1) Data base period Jan. - Nov. 1984.