Legislation, the environment, economic and corporate social responsibility are some of the key factors that are governing the recovery of flared gas worldwide. There is growing awareness of the issues associated with flaring and efforts are being made globally by operators and governments to minimise it. There are several technologies for reducing flaring at source or in a processing plant. The choice of technology depends on the economics of the project, frequency of flaring, infrastructure available and location of the producing facility. This paper covers innovative Flare Gas Recovery Systems using Surface jet Pumps and avoiding the use of compressors.
Conventional Flare gas Recovery systems usually comprise of one or more compressors, which compress the collected flare gas and route it for further processing. The compressor design is critical and determines the system's capacity and turndown capability. However compressor based solutions can be quite large, complex and have high capital and operating costs. They are also very sensitive to changes in gas composition and MW.
Surface jet pumps (SJPs) are simple, low cost passive devices that can also be used to recover flare gas. They use a high pressure (HP) fluid as the motive force to boost the pressure of the LP or LLP flare gas and deliver it for processing. The high pressure fluid that is needed as the source of energy or motive flow is usually gas taken from the discharge of a compressor or from the export gas line. However HP liquids, such as oil or injection water can also be used. Advantages of using SJPs include low cost, no moving parts, zero maintenance, zero power or fuel gas usage, small footprint and varying layout configurations. SJPs are well suited to liquid ingestion and to changes in process conditions (without affecting performance).
This paper discusses the use of Surface Jet Pumps as an alternative to compressors for flare gas recovery and cites several case studies of where this technology has been successfully utilised. The design and operational criteria of SJPs, as well as the economics is also highlighted.