During years of operation on a power plant, the heat transfer oil cracks and permeates through the wall of absorber tube and enters the vacuum annulus. This causes a drop in vacuum level and an increase in heat loss. Therefore it is important to have a reliable solution to keep the vacuum and thus maintain a high efficiency. Re-evacuation is a technology that allows online service of the receiver tube to restore the vacuum. This solution can reduce the lost caused by losing efficiency and stop in power plant operation, and increase up to 30% the output.
Huiyin’ patented solution for hydrogen problem allows the receiver tubes to be serviced online, without having to stop the whole loop to cut the tubes and replace them. It takes only 5 minutes to restore a receiver tube, by simply opening the nozzle on the receiver and connecting it to the vacuum pumping system. This can be done during the evening so that the loop can still work during the day time. Huiyin’s re-evacutable receiver aims to reduce the cost for its client in purchasing, replacing the receiver tubes and cost to stop the loop.
Glass metal seal technology
Glass-metal seal is a critical and difficult part in a receiver tube. Due to the difference in expansion rate of glass and metal, and thermal cycling during operation, the seal has to be strong enough to take the thermal shock and thermal fatigue.
There are normally two ways of making glass metal seals for receiver tubes: a matched seal and unmatched seal. A matched seal has a low expansion alloy (such as kovar 4J29), welded directly to a 5.0 glass. Unmatched seal is made out of stainless steel and 3.3 borosilicate glass. As the 5.0 glass industry in China is not mature enough yet, and foreign 5.0 glass is expensive, most Chinese producers adapt a transitional seal, which connects a metal part with around 5.0 expansion rate to 3.3 borosilicate by putting in between several different glass with different expansion rate between the metal and the glass.
Huiyin has a special technology of working the metal ring, which enables it to compensate the stress and deformation caused by the difference in expansion rates, so that the seal can take enough thermal cycles with a long life time. With this technology, Huiyin’s extremely reliable glass metal seals are produced. These seals have passed all tough tests to ensure the reliability in any hazardous working conditions. This technology has been used in CSP plants in the US for almost 30 years, verified to be reliable. Huiyin’s glass metal seal technology has reduced the failure rate and on the other hand, reduced cost and price.
Highly efficient solar selective surface technology
Huiyin receiver for oil system is equipped with the latest generation of ceramic based selective surface, which has shown superior efficiency and excellent temperature stability. This coating is stable at 450 ℃ working temperature with no degradation in optical properties, keeping its high absorptivity and low emissivity.
Huiyin’s has developed and supplied receivers with 550 ℃stable highly efficient selective surface to molten salt projects as the only producer in China that has molten salt receiver technology.
High efficient Anti- Reflection coating technology
Huiyin’s AR coating technology helps to enhance solar transmittance, and on the other hand has a hydrophobic self-cleaning effect. The glass envelop of receiver tubes can absorb humidity in air that alters the refractive index at the surface of the coating. This reduces the solar transmittance of the glass envelop. The hydrophobic surface helps the coating to resist water, and enables the water to form small drops and roll down from the coating surface while taking away dirt or dust. In this way the coating is kept clean and is able to maintain its high transmittance.