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Environmental Aspects of the TROLL Terminal Design

IP.com Disclosure Number: IPCOM000182779D
Publication Date: 2009-May-05

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Environmental Aspects of the TROLL Terminal Design

D.J. WEEKS

M W Kellogg Ltd

Middlesex, United Kingdom

ABSTRACT

  Norway, in common with many countries nowadays, is very protective of its environment. This consciousness and responsibility are reflected by the strict limits on air pollution, in particular noise, and hydrocarbon contaminant levels in discharged wa"ter that were imposed for the TROLL terminal design. The capacity of the terminal and the size of its equipment have necessitated new research in the field of noise prediction some of which conflicts with current industry beliefs.

  This paper discusses some of the engineered solutions to in-plant and community noise abatement and describes the water treatment facilities installed to meet hydrocarbon discharge limits of 5 mgll.

INTRODUCTION

  By any standards the TROLL on-shore gas terminal at KoHsnes. Norway is big! It is designed to produce 84 x 106 Sm3/day of sales gas product, equivalent to approximately 10<7( of Western Europe's total gas demand. In fact, because most of the plant equipment is designed for field plateau conditions when feed gas arrival pressure has fallen to 60 bara, the terminal will be able to process and produce substantially more sales gas than the nominal nameplate capacity during the early years of operation. The terminal has been designed for a production life of 50 years.

  The large capacity of the terminal plus the regulated emission standards imposed on the design and guaranteed by the joint venture engineering partners, Aker/KelIogg, have led to some interesting design solutions, particularly in the areas of effluent water treatment and noise abatement.

PROCESS DESCRIPTION

System 20 • Gas Reception, Figure 1

Wet feed gas, containing 0.3 moltK CO2, is delivered

63 km to shore via two 36" pipelines. Hydrates are inhibited and corrosion in the pipeline is controlled by the injection of 90<7( wt mono-ethylene glycol (MEG) solution. The feed pipelines rise some 300 metres from

the sea bed, through a specially constructed tunnel system and enter two slugcatchers, one per pipeline. Each slugcatcher comprises 8" x 48" bottles with a total length of 176 metres, which effect primary separation between the gas and liquid phases. Additional liquid residence time is provided in condensate and glycol bottles below the slugcatcher fingers to effect a further separation between the hydrocarbon condensate and the aqueous glycol streams.

  The gas phase exits each slugcatcher through risers and is combined in a common header before processing for hydrocarbon dew point and water content control on three parallel conditioning trains. Hydrocarbon and aqueous liquid streams from the slugcatchers are separately filtered and let down in pressure, before recombining at low velocity for stabilization in the condensate train.

System 25 • Gas...