Pyramid E&C specializes in building optimized compact modular LNG plants by utilizing mixed refrigerant cycle technology. We optimize refrigerant conditions to precisely meet the refrigeration requirements for each application while minimizing compression power. Mixed refrigerant cycle process is contained in a perlite-filled cold box module, which simplifies installation and optimizes performance with minimal maintenance.
Our LNG modular plant offers several advantages as indicated below:
- Plants are designed to be easily operated and maintained with minimal plant support.
- Low OPEX for a small-scale LNG plant due to highly efficient, optimized mixed refrigerant (OMR) process.
- Low CAPEX due to modular equipment offerings and minimal site work.
- Designed with flexible operating range between 30% to 110% of design capacity.
- Minimized field work by innovative packaging.
- Rapid installation and re-deployment of plant mitigates long term project risks.
The process comprises of following steps:
Feed gas from the gas station is filtered through an inlet filter coalescer to separate any liquids/solids to prevent foaming in the acid gas removal unit. Filtered feed gas is sent to acid gas removal unit for removal of acid gases (Typical requirements for LNG: Max 50 ppmv CO2, Max 4 ppmv H2S) using a proprietary amine solution. Sweet gas from acid gas removal unit is then dehydrated in molecular sieve dehydration unit. The dehydration unit dries gas to remove water down to <0.1 ppmv. A mercury removal unit is provided after the molecular sieve dust filters, for removal of any trace of mercury in the gas prior to entering the liquefaction unit.
This unit separates lighter hydrocarbon (used to produce LNG) from the heavier hydrocarbons, which would freeze at LNG temperature. The heavier hydrocarbons are further treated in fractionation unit to produce plant condensate.
The heavy hydrocarbon removal plant design is dependent upon a detailed analysis of the range of components in the feed gas.
The liquefaction plant cools and liquefies the feed gas from approximately 18°F to -260°F. The Optimized Mixed Refrigerant (OMR) liquefaction plant process, comprises a simple vapor compression cycle using a mix of refrigerants providing a close fit of cooling curves in the main cryogenic heat exchanger (cold box).
The mixed refrigerant vapour from cold box is compressed by a centrifugal compressor directly driven by a highly fuel efficient, low emissions gas turbine (Optionally Electrical Motor). Air coolers remove the heat of compression followed by propane refrigerant coolers, causing mixed refrigerant to condense partially. Pre-cooled mixed refrigerant will be separated in liquid and gas. Each liquid and vapour stream will be fed to main cryogenic exchanger separately.
The High-pressure mixed refrigerant (HPMR) is then fully liquefied in the cold box and expanded (partially flashed), using Joule-Thomson expansion, providing refrigeration for the system. The flashed low-pressure mixed refrigerant (LPMR) provides the refrigeration in the cold box and cool mixed refrigerant vapor returns to the compressor via the suction scrubber. The liquid stream also cooled in cryogenic exchanger and flashed to low pressure and fed to shell of the exchanger providing cooling to process side gas.