A hot subject: Heat recovery in process air generation Investments pay off quickly: AERZEN offers solutions for retrofitting In process air applications, operators can really work up a sweat, because compressed air generation is by far the most expensive form of energy for physical reasons. Following the laws of thermodynamics, there is no compressed air without heat. In view of the long operating times of compressors, it is particularly important to recover these costs for two reasons, first for environmental reasons, and then still because of business management reasons. Appropriate solutions for new construction and retrofitting are now an integral part of the AERZEN portfolio. Compressed air is a hot topic from an energetic point of view. Limited resources, strict environmental regulations, limited CO2 emissions, rising energy costs and increasing price pressure are the driving forces behind energy efficiency projects. On the one hand, this is based on precise design, so that systems can operate around the clock and closest to the optimum operating point, but also due to the use of frequency inverters for speed control. On the other hand, for physical reasons, compressors offer an enormous potential to utilise the inevitably rising air temperature during pressure increase. In view of the growing interest in ecological sustainability and economic cost awareness, plant operators are increasingly looking on heat recovery.Laws of ThermodynamicsAccording to the laws of thermodynamics, air, in an enclosed space, heats up as soon as pressure rises. The reason for this is that air molecules must move closer together due to smaller space and, thus, friction increases. For further analysis, the law of ideal gases is applied for the typical range of process air pressures. Together with the efficiency of the compressor at the respective operating point, the air temperature can be calculated downstream of compression. This mainly depends on the pressure ratio. At an intake temperature of 20°C, a pressure ratio of three, and an isentropic compressor efficiency of 74 percent, the air is heated to approx. 166°C during compression. The higher the temperature, the wider the range of applications for waste heat recovery. The amount of heat contained in the process air typically accounts for about 85 percent of the total amount of heat potentially to be recovered in plants. The remaining 15 percent are distributed more or less equally between losses from the drive motor, the mechanics and radiation from the hot compressor stage underneath the acoustic hood.Waste heat for heating roomsBut these 15 percent can also be used for heating adjacent office areas, or production areas within heat recovery measures. AERZEN equips the exhaust air louvers of the positive displacement blower Delta Blower, rotary lobe compressor Delta Hybrid and screw compressor Delta Screw with an exhaust air duct. The heated air, which previously cooled the compressor stage, the silencer, and the piping system underneath the acoustic hood, escapes from this exhaust air duct. The return flow in the central exhaust air duct, from which branching air ducts supply the rooms to be heated, has a temperature between 30°C and 60°C. Regulated flaps are used in this system for individual temperature control.Compact pipe bundle heat exchangersThe amount of heat contained in the process air typically accounts for about 85 percent of the total amount of heat potentially to be recovered in plants. AERZEN offers heat recovery solutions for the respective application, which effectively channel the available energy into production processes, hot water preparation or heating systems.The first way of heat recovery is to exploit the 85 percent share of thermal energy, i.e. concerning the compressor air itself. AERZEN already successfully uses flow-optimised pipe bundle heat exchangers for a large number of applications. These compact units are located just downstream of the assembly on discharge side. The installation is simple. Consequently, this technology is also recommended for retrofitting, in order to noticeably improve the energy efficiency of existing plants, and the CO2 balance. The pipe bundle heat exchangers used by AERZEN are designed in such a way that the performance loss due to the increasing duct pressure of less than 2-3%, depending on applications and requirements, is negligible. While the thermal energy from the pure exhaust air can be used most effectively for direct room heating, the use of pipe bundle heat exchangers opens up an energy source with significantly higher temperatures. This results in a multitude of application possibilities in the implementation. Typical applications are the support of heating systems, the preparation of hot water for showers and washrooms, as well as the heating of service water in industrial environments. In wastewater technology, the heat can also be used to dry sewage sludge. When planning such systems, it must be ensured that they are dimensioned to match the base load. The basis for optimum waste heat utilisation is the determination of the usable amount of heat. Of course, it depends on the usable temperature difference, the prevailing volume flow, and the degree of simultaneity of supply and use. AERZEN offers smart heat recovery solutions for the respective application, which effectively channel the available energy into production processes, hot water preparation or heating systems.SummaryCompressed air generation is automatically connected to waste heat due to thermodynamics. Since this law cannot be repealed, solutions are needed to integrate the previously unused heat into the own energy demand. It must be noted that the real extent of possible savings is often not recognised by the plant operator in its entirety. However, a look into practice shows that this technology pays for itself quickly, plus reducing CO2 emissions.
Aerzen Asia at the SIWW in Singapore Aerzen Asia participated in the Singapore International Water Week (SIWW) with its own stand from 9-11 July 2018. This trade fair takes place every two years and is the most important exhibition of its kind in South East Asia. The exhibition brought together visitors and exhibitors from the water management industry from all parts of Asia. Aerzen Asia used the SIWW as a platform to further develop regional developing markets such as China and India. The company presented the products Aerzen AT200 G5plus, Delta Hybrid D12S and AERsmart, as well as our after sales services, at an exhibition stand covering more than 50 square meters. Also, the German Ambassador in Singapore, Dr. Ulrich A. Sante, was welcomed at the stand and was informed about the solutions and the history of AERZEN by Chuck Lim, Vice President Aerzen Asia Pacific.The three trade fair days of SIWW were very positive for AERZEN’s brand awareness and have confirmed the position of our company as a leader in the wastewater and environmental market.
Aerzen Argentina: Partnership with Bioingepro Following intensive discussions, Aerzen Argentina has agreed to cooperate with Bioingepro S.R.L., one of the country’s largest manufacturers of wastewater treatment plants. The Buenos Aires-based company has already built over 450 wastewater treatment plants. Therefore, it makes Aerzen Argentina proud that Bioingepro relies on our portfolio and our technologies. Gastón Jares of Bioingepro says: “We are happy to cooperate with a company like AERZEN. We share the same values, including the constant pursuit of progress and the most modern and sustainable technologies to protect our most precious asset: water.” The first two units have already been supplied by Aerzen Argentina.
AERZEN’s aftercoolers set standards With minimum pressure losses and extremely high cooler inlet temperatures, all AERZEN aftercoolers are suitable for cooling air and nitrogen up to 280°C! Developed in cooperation with well-known international manufacturers, AERZEN offers a complete range of air-air and water-air aftercoolers. The independent series is specially tailored to the machine types Delta Screw, Delta Hybrid and Delta Blower, including downstream cyclone separator and condensate drain. Furthermore, an extensive range of accessories is available. AERZEN has its own design programs. In just a few minutes, a suitable cooler can be selected and its process data calculated in a customer- specific manner – to achieve the most efficient solution for each temperature-critical subsequent process.
