Improving the energy efficiency of the blowing ventilation system by utilizing the heat of the compressor station of a hydro cracker

Summary

Hydrocracker compressor equipment generates up to 35–40% of the low-grade heat consumed; however, irretrievably lost through the cooling systems. The objective of this study was to analyze the efficiency of utilizing this heat for the needs of the blowing ventilation system of an oil refinery production building. The heat balance was calculated for the compressor station, and the available thermal capacity (560 kW) was determined based on the equipment specifications. A hydraulic circuit with an intermediate coolant (water, 70/50°C temperature chart) was proposed. For a facility (in the climatic conditions of the central region of Russia) with three compressors (one for the circulating gas, two for the makeup, and one for the backup) and a 60,000 m3/h air handling unit, the recovery was found to cover 63.3% of the heat load during extreme cold periods and completely replace the external heat source at temperatures above –3.1°C. The system operates only during the heating season (5,136 hours/year). The annual thermal energy savings amount to 1,872 Gcal, resulting in savings of over 5.05 million rubles with a capital investment payback period of approximately 2.5 years. The proposed solution is economically feasible and can be recommended for the application at oil refining facilities.

Key words

energy efficiency , air-blowing (compressor) station , pay-back period , heat recovery , hydrocracker , blowing ventilation , heat balance , low-potential heat , cooling system , intermediate coolant

Feasibility study of using thermal power of wastewater
for improving the efficiency of wastewater treatment facilities operation

Summary

A cost effectiveness analysis of using a system for recovering the thermal power of effluent for heating incoming wastewater to enhance the biological treatment process, as well as for heating the premises of wastewater treatment facilities was conducted. With account of the energy cost in the Republic of Bashkortostan, the operating and capital costs of the proposed method for arranging the heating of wastewater treatment facilities with two alternative options: using gaseous fuel (a block-type gas boiler house) and electric heating devices were estimated. The pay-back period was determined using the overhead cost equivalence method for the proposed design options. The energy efficiency was calculated based on the annual fuel and energy consumption expressed in tons of fuel equivalent. It was shown that the wastewater heating system using a heat pump requires the lowest operating costs (RUB 6.9 to heat 1 m³ of wastewater by 10°C, or RUB 1.3 million per year). The system is also the most energy- and cost-effective since it consumes the minimum fuel equivalent and provides for reducing the cost of expensive primary energy resources by 127 tons of fuel equivalent per year.

Key words

sewerage treatment facilities , heat pump , power efficiency , secondary thermal energy , recovery , pay-back period