A direct-fired heat pump process and equipment for produced water in strong corrosion and high salinity oilfields

Abstract

The invention relates to a direct-fired heat pump process and equipment for produced water in strong corrosion and high salinity oilfields. The process first sends the oilfield produced water from the sewage tank to the tube side of the produced water low-pressure heat exchange evaporator, and the produced water low-pressure heat exchange evaporator shell side has low-pressure clean water, which enters the low-pressure absorber shell side after absorbing heat and vaporized, and is concentrated After the lithium bromide solution is absorbed, it becomes a dilute lithium bromide solution and releases heat. The dilute lithium bromide solution is boosted by an anti-corrosion water pump and then sent to the direct-fired generator to be heated to boiling. The vaporized atmospheric pressure water vapor is sent to the shell side of the atmospheric pressure condenser through the pipeline. The present invention extracts part of the heat energy from the oilfield produced water, and uses it for production or daily life after the direct-fired heat pump drives the temperature up, not only can the low-grade heat energy of the oilfield produced water be efficiently utilized, but also the thermal efficiency of the system is about 1.85, which is about the same as that of a common heating furnace. Compared with the existing technology, the heating coefficient has been improved three times, two processes and water pumps have been omitted, and the corrosion and scaling problems of oilfield produced water have been solved.

Description

technical field [0001] The invention relates to a process and equipment for utilization of low-grade heat energy, in particular to a process and equipment for a direct-fired heat pump of produced water from oilfields with strong corrosion and high salinity. Background technique [0002] my country's energy consumption is dominated by coal and oil, and environmental problems have become increasingly prominent. It is the second largest energy consumer in the world. The resulting soot and sulfur dioxide emissions accounted for 70% and 90% of the country's total emissions, respectively, and the area of ​​acid rain formed by sulfur dioxide emissions has already accounted for one-third of the country's land area. [0003] The National Development and Reform Commission requires strengthening research on energy-saving technologies, energy-saving theories and methods in the exploration, development, production, and construction of the onshore oil and gas industry. Reduce energy cons...

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Problems solved by technology

[0006] In the past few years, oilfields such as Shengli and Zhongyuan have carried out tests and applications of oilfield produced water direct-fired heat pump heating or water-containing crude oil dehydration and external heating. The metal is highly corrosive and fouling is serious. Therefore, for the safety of the equipment in the application, a clear water circulation heat exchange system is added in front of the low-pressure evaporator, which also increases the first-level temperature difference and circulation pump work; for the dehydration and heating of water-containing crude oil , also adopts the process of heating clean water with a direct-fired heat pump first, and then heating water-containing crude oil with clean water, so there are the following problems: 1. The produced water heat exchanger is severely corroded and perforated, and then high-strength titanium heat exchange tubes are used, but the cost Too high; 2. The produced water heat exchanger is seriously fouled, and it cannot be used after one to two years; 3. The produced water-clean water heat exchanger makes the temperature of the low-pressure heat exchange evaporator of the produced water entering the direct-fired heat pump oil field only 35 -40°C, which is 8-10°C lower than the temperature of produced water; 4. The produced water-clean water heat exchange process requires long-term operation of the water pump; The high-temperature clean water outlet in the combustion-type heat pump is reduced by 20-80°C, and the entropy increases greatly, which reduces the heating coefficient; 6. The water-containing crude oil-high-temperature clean water heat exchanger process requires long-term operation of the water pump; 7. Low-pressure absorber, atmospheric pressure condensation There is no step utilization of the temperature difference in the device, which increases the entropy of the system

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