7 ppm NO x 50MM Btu/hr Oil Field Steam Generator Operating on Low Btu Waste Gas in The Los Angeles Basin
Authors: Whitaker W. 
Published: December 2007

This paper reviews the application of a 50MM Btu/hr oil field steam generator operating on low Btu produced "waste" gas. The generator is the first 50MM Btu/hr oil field steam generator permitted in the Los Angeles Basin since the 1980's. Stack emissions of less than 7 ppm NO × corrected to 3%O2 were achieved using a Low NO × burner without selective catalytic reduction with ammonium injection (SCR) and without flue gas recirculation (FGR). (Future references to NO × ppm will be corrected to 3% O2).

Introduction

Tidelands Oil Production Company is an operator of 922 wells consisting of mature water flood and steam flood wells. These wells are in the Wilmington Oil Field, Los Angeles County, California. The steam generator is on the Parcel "A" Lease in the Port of Long Beach (fig. 1).

In the 1960's, wells on the Parcel "A" Lease were steam stimulated using the huff and puff method with portable steam. Results of steam stimulation were encouraging and showed that a steam flood should be economical. The installation of a steam source is part of a pilot program to develop a steam flood on the Parcel "A" Lease.

Tidelands produces approximately 2000 MCFD of gas with a higher heating value of 550 to 1000 Btu/scf yielding approximately 62 MM Btu/hr of fuel. The fuel contains 40% to 60% CO2 and has no commercial value. Varying composition, varying delivery pressure, and varying volume of the produced gas posed unique design and operational considerations that will be discussed later in this paper.

A steam requirement and the availability of waste fuel were a good fit for a S50MM Btu/hr steam generator. A used steam generator was rebuilt and retrofitted with a low NO × burner designed to burn fuel with a higher heating value of 550 Btu/scf. The generator was rated at 58,500 lb/hr with a maximum working pressure of 1700 psi.

The South Coast Air Quality Management District (SCAQMD) is the environmental regulatory agency with jurisdiction in the Los Angeles Basin. The SCAQMD is considered the toughest district to permit a major emitting source. The SCAQMD permit to construct required that the generator stack be monitored real time with a continuous emission monitoring system(CEMS). Maximum NO × allowed by the permit is 15 ppm.

The steam generator was delivered in February 1996 and system check out started in June 1996. The emissions data presented in this paper were taken in October 1996. Data was independently tested and verified by World Environmental with the results of these tests presented to SCAQMD as required by the SCAQMD permit.

Air Quality Regulations and Permit Requirements

The applicable emission compliance requirements are defined in the permit to construct that is issued by the SCAQMD. The governing regulation that sets the permissible NO × level is Rule 11.46 of the Rules and Regulations for SCAQMD. The SCAQMD permit to construct allows this generator installation a maximum permissible level of 1 5 ppm of NO ×.

Regulation 13 of the Rules and Regulations for SCAQMD are the guidelines for Best Available Control Technology (BACT) and cross references the SCAQMD document titled BACT Guidelines. These documents set guidelines for what type of pollution control equipment must be installed. The SCAQMD also takes into account past permit requirements for the same type of equipment and current pollution control technology.

For natural gas combustion, SCR has been established as the BACT on many systems and is required for many permits. A SCR system requires ammonium injection. Installation is costly, operating costs are high, and it requires the use of hazardous substance(s). For our project, a Low NO × burner with FGR was allowed by the SCAQMD. This was the first steam generator of its type to be reviewed by the SCAQMD since the 1980's and establishes BACT in the Los Angeles Basin.

Rule 20.12 Appendix A Chapter 2 of the Rules and Regulations for SCAQMD requires that stack emissions data be measured real time and daily reports be sent to the SCAQMD via a modem using a continuous emission monitoring system (CEMS). NO x, wet O2, dry O2, stack gas flow rate, steam output, fuel flow rate, and FOR recirculation rates are measured as required by Rule 20.12.

In the past, CEMS were costly sensitive analyzers that required frequent cleaning and repair. Dependability was poor and equipment failure was common. The equipment required constant attention by field personnel and the manufacturer. Going into this project, I expected a long CEMS start up and debugging.

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