REFRIGERATION SUPPLY. A company of Bayer and LANXESS

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1 REFRIGERATION SUPPLY A company of Bayer and LANXESS

2 REFRIGERATION SUPPLY - Introduction INTRODUCTION CURRENTA ensures temperaturesensitive processes and products have the perfect environment by generating and distributing refrigeration. 02

3 The correct operating temperature is essential to the smooth running of processes in many production areas of the chemical industry. That is why refrigeration is required both for cooling products and for cooling or air-conditioning buildings and rooms where sensitive products are processed. Even the slightest variation in temperature can cause disruptions that often result in substantial costs. Generation and distribution of refrigeration About 70 production and service companies are currently based at the three CHEMPARK sites and are CURRENTA customers. In Leverkusen and Dormagen, the Refrigeration Supply segment provides these customers with refrigeration. This enables temperatures of -5 C, -20 C, -33 C or -45 C to be reached on the site of the customer or refrigeration consumer. A complete refrigeration plant is not required at that point, just an evaporator unit that takes up a comparatively small amount of space. The recovered heat is transferred to the central refrigeration station through the integrated networks. We carry out regular checks to ensure that high safety and environmental standards are maintained. The only refrigerant we use is ammonia, which is energy-efficient and climate-friendly, as it neither contributes to the greenhouse effect nor damages the ozone layer. Its typical smell also becomes noticeable from a concentration of just 5 ppm (parts per million), meaning that even minor leaks can be identified and remedied immediately. Our central refrigeration control station is permanently manned, so there is always someone available for you there. The Refrigeration Supply segment is made up of two areas generation and distribution. You will find a simplified representation of the refrigeration process in Fig. 1 (page 4). The Generation department is responsible for the operation of the central refrigeration stations at the various sites, while the Distribution department is responsible for technical support of the refrigeration networks and customers. The experienced employees in these departments also provide advice for customers on all aspects of refrigeration technology applications relating to technology and cost-effectiveness in order to develop perfect solutions together. 03

4 REFRIGERATION SUPPLY - Generation Distribution GENERATION CURRENTA Refrigeration Supply uses compression refrigeration plants to produce refrigeration at various temperatures. High pressure Low pressure EXPANSION VALVE Central refrigeration station Liquid Gaseous refrigerant Condenser Refrigeration network Compressor Evaporator Refrigeration customer Fig. 1: Refrigeration supply interfaces We basically control a process in which warmth is recovered at the customer s and then released into the surroundings at an accordingly higher temperature from the central refrigeration station. At the CHEMPARK Leverkusen and Dormagen sites, this takes place using a compression refrigeration process. As a result, we are able to provide refrigeration at the CHEMPARK Leverkusen site at temperatures of -5 C, -20 C and -45 C, and at the CHEMPARK Dormagen site at -5 C, -20 C and -33 C. The compression refrigeration process consists of four components evaporator, compressor, condenser and expansion valve. We use ammonia, which has become established as standard in the chemical industry. The compression refrigeration process The refrigeration circuit is a closed thermodynamic cycle that utilizes the fact that evaporation and condensation temperatures are dependent on pressure. The process goes through four stages evaporation, compression, condensation and expansion. The compressor extracts the gaseous refrigerant from the evaporator and compresses it. This increases the pressure and temperature of the refrigerant. In the condenser, the gaseous refrigerant transfers heat to the cooling medium, and condenses. The liquid refrigerant is then expanded back to evaporation pressure in the expansion valve, and fed back into the evaporator. This is where the refrigeration is actually generated. The expansion valve expands the refrigerant, which cools down in the process. The refrigerant then absorbs heat from its surroundings or from a cooling medium, which in turn causes this to cool. As a result, the refrigerant evaporates in the evaporator. Still cold, the gaseous refrigerant is again extracted into the compressors and the refrigeration cycle begins again. 04

5 DISTRIBUTION The pipelines of the refrigeration distribution network connect the central refrigeration stations with the refrigeration consumers. Most pipelines between the compression plants and the evaporator stations are laid on pipe bridges. Control unit in the central refrigeration station G 21 in Leverkusen The distribution network is made up of the liquid ammonia network and the gaseous ammonia network. At the Leverkusen site, the networks are a total of just under 30 kilometers long, in Dormagen over 17. The pressures in the gas networks are 3.55 bara (-5 C), 1.9 bara (-20 C) and 0.55 bara (-45 C). In the gas network, the diameter of the pipes ranges between DN 100 and DN 700. In the liquid network it is between DN 25 and DN

6 REFRIGERATION SUPPLY - Evaporation station EVAPORATION STATION This cost-effective facility takes up little space and generates refrigeration directly in your plant. Evaporation station When it comes to refrigerating products, there are basically two methods direct and indirect refrigeration. In the former, the refrigerant cools the product directly, while in the latter the refrigerant reduces the temperature of a cooling medium, which then acts as a refrigerant on the product. Since CHEMPARK uses indirect refrigeration almost without exception, the following refers exclusively to the evaporation station. to a low temperature in the heat exchanger and expanded in the expansion valve. It then evaporates at the corresponding temperature in the evaporator, which cools the cooling medium. The cold, gaseous ammonia is then fed back into the heat exchanger where it is heated back up to ambient temperature through heat transfer from the liquid ammonia. The evaporation station consists of two plant parts the heat exchanger, which transfers heat energy from the liquid to the gaseous ammonia, and the evaporator with an injector valve. The liquid ammonia comes from the refrigeration network at ambient temperature, is brought 06

7 Grid operator Customer Liquid NH 3 network TS-A Gaseous NH 3 network PS-A NH 3 / NH 3 heat exchanger Separator NH 3 evaporator Expansion valve Cooling medium Fig. 2: Illustration of the technical interface Further services To ensure the safety of the plants, all 156 evaporators in the customer plants must be inspected annually. This involves visual and functional tests, as well as a check for leaks. These are carried out by members of the Refrigeration Supply Distribution department. Alongside these annual inspections, our experts provide support for CHEMPARK companies in dealing with problems, repairs, maintenance, commissioning and safety reviews for their refrigeration plants. 07

8 Published by Currenta GmbH & Co. OHG Leverkusen Germany Last revised: May 2014