Steam system and condensate drainage - most likely one of your low hanging fruit when it comes to energy saving

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1 NEWSLETTER June 20 system and condensate drainage - most likely one of your low hanging fruit when it comes to energy saving is the oldest and most widely used form of energy in industry. Yet in most plants and engineering offices it is still not understood to a large degree. It is neglected in an even larger degree. What is meant by that is that steam is used in such a wide spread manner in almost all industrial manufacturing plants that it s taken for granted until something fails. A good example of that is the care and maintenance of strainers installed upstream of steam traps in order to prevent the trap from plugging up from various deposits of pipe scale and chemical residue. That same thinking would logically conclude that if scale and residue are anticipated then it would stand to reason that the strainers should be blown down and/or cleaned out periodically. It is surprising the number of times a systems failure or reduction in efficiency can be attributed to something as simple as the impacted build-up of scale in strainers; something that could have been averted with a little planned preventative maintenance. In conjunction with that is the periodic testing of the steam traps, all too often steam systems are installed and forgotten. Until, as mentioned earlier, a system breaks down or gradually becomes more and more inefficient. Inefficiency translates into additional operating costs. In older plants the savings potential is enormous. Not only from a losing money standpoint, but also from an environmental aspect. A schematic diagram showing all relevant elements in a closed steam system Newsletter - June 20

2 Preventative maintenance An energy efficient steam system clearly has to start with a good design and with the selection of the correct elements such as adequate steam traps. Such systems then need to be maintained in a very professional and preventative way which means working conditions have to be monitored on a regular basis and measuring results have to be assessed and potential repair or replacement work has to be planned together with operation. Infrared technology enables to see each object in different colors which represents a certain temperature scale (see picture below) which makes it possible to see if a steam trap will lose steam or if there is build up of condensate. The pictures on the right were taken at Lonza Guangzhou using thermal imaging technology. Through these thermal images it is easy to identify sources with excessive heat loss. The two steam traps in the pictures on the right which are mainly red indicate improper function leading to loss of steam and require immediate replacement (repair). 2 3 Good examples can be seen from these two pictures, these steam traps operate according to specification (red or yellow show area of steam, whereas green represents condensate). 3 2 Newsletter - June 20

3 Traps and how to select the right types traps are essential for proper distribution system performance. During plant or system start-up, traps allow air and large quantities of condensate to escape. During system operation, the traps allow collected condensate to pass into the condensate return system, while minimizing the accompanying loss of steam. There are three primary types of traps: Thermostatic, Mechanical and The hermo Dynamic ynamic. In the following text and pictures you will see some good and bad design examples: Bad Good 2 3 Advantages: drainage at the lowest point Potential dirt and other particles can be drained through hand valve Bypass in order to isolate steam trap for maintenance 3 Newsletter - June 20

4 Thermostatic (bimetallic) Traps Cover Temperature feeler of Duo stainless steel plates Thermovit regulator Light and compact regulator unit, replaceable without removing body from pipeline. Withstands water hammer and freezing. Stage nozzle Thermodynamic control. Wear resistant. Freely mounted for non-return valve action Large-surface strainer Recessed flat gasket Metal base bushing Thermostatic traps use temperature differential to distinguish between condensate and live steam. This differential is used to open or close a valve. Under normal operating conditions, the condensate must cool below the steam temperature before the valve will open. Common types of thermostatic traps include membrane regulator and bimetallic traps. Thermostatic (membrane ( membrane) Cover Thermostatic capsule Rugulator unit replaceable without removing body from pipeline. Precise reaction to any change in temperature. Corrugated membrane of Hastelloy. Tandem seat Double sealing Non-return valve with hollow cone and reduced mass Quick closing in the event of waterhammer Large-surface strainer Recessed flat gasket Metal base bushing 4 Newsletter - June 20

5 Mechanical Traps Bolted cover Upper plug Installation of manual vent valve or air balance possible Thermostatic bellows For automatic air-venting ( Duplex control). Without bellows ( Simplex control) for cold fluids Control unit Easy maintenance after opening cover. Complete unit may be changed without removing body from pipeline Closing unit (orifice) A selection of orifice sizes for high and low pressure applications Deflector Guarantees the deflection of the condensate stream and reduces wear on the trap body Rolling ball valve Mechanical traps use the difference in density between condensate and live steam to produce a change in the position of a float or bucket. This movement causes a valve to open or close. There are a number of mechanical trap designs that are based on this principle. They include ball float, float and lever, inverted bucket, open bucket, and float compared with other trap types, they are the least affected by dirt. The traps are supplied with thermostatic bellows for automatic air-venting venting, alternatively without bellows. Close ball float Lower Plug Thermodynamic Disc Trap Thermodynamic traps work on the difference in dynamic response to velocity change in flow of compressible and incompressible fluids. As steam enters, static pressure above the disk forces the disc against the valve seat. The static pressure over a large area overcomes the high inlet pressure of the steam. As the steam starts to condense, the pressure against the disk lessens and the trap cycles. This essentially makes a thermodynamic trap a "time cycle" device: it will open even if there is only steam present, this can cause premature wear. If non condensable gas is trapped on top of the disc, it can cause the trap to be locked shut. & Bonnet Valve disc In Bonnet Chamber Liquid & Flash out 5 Newsletter - June 20

6 Short guide for steam trap selection Not all steam trap types are equally suitable for a given application. Depending on the operating conditions and service in question, one or more systems will be particularly well suited. The following table contains 5 criteria for steam trap selection based on the operation of the plant and the specific requirements on the part of the plant owner. Criteria. operation with different condensates 2.Different modes of operation trap types Trap with bimetallic regulator Trap with membrane regulator Ball float trap with automatic air venting Ball float trap without air venting Rating: =Excellent 2=Good 3=Fair or conditional - =Not recommended, unsuitable Please note from steam For cold condensate or condensate with a from compressed air saturation curve deviating from that of water only, distillate from chemical float traps without thermal venting can be used. products Continuous operation: Constant formation 2 of condensate; flow rate and pressure vary Discontinuous operation: intermittent 2 3* * e.g. air venting difficulties formation of condensate; flow rate and pressure vary strongly Any operation: Heat exchanger may be controlled on the steam side 3** 2 3* * Air venting difficulties **With partial load (reduced differential pressure) flow rate possibly not sufficient 3.Operation with back Up to approx. 30% of upstream pressure pressure From 30% to 60% of upstream pressure 3* * Adjustment may be necessary More than 60% of upstream pressure 3* * Adjustment may be necessary 4.Sensitivity to dirt Highly contaminated condensate 5.Air-venting Automatic 3* *Manual air-venting 6. discharge at definite temperature temperature nearly boiling temperature 2* 2** This may apply to small heat exchangers (e.g. laboratory equipment) * Adjustable may be necessary ** Might require special membrane regulator under cooling approximately 30K (required) * ** - - * with special regulator or through adjustment ** with special capsule under cooling adjustable 2* * Adjustable causes a reduction in flow rate! 7.For resistance * 3* * Only ensured with special design (type) 8. Intermittent condensate formation discharge without loss of live steam Reduced condensate formation(<0 kg/h) 9.Resistance to water hammer 0.Non-return valve action.application in vacuum 2.Installation in vacuum 3. Easy of maintenance 4.Service life of control unit 5.Use with superheated steam Continuous condensate formation(>0kg/h) * 3* 3* * Built-in non-return valve= * -* -* * Built-in non-return valve= 3 2 -* -* *Partially possible but need to be discussed with supplier 2 3 3* *Need to be discussed with supplier 6 Newsletter - June 20

7 Lonza Engineering Ltd Mechanical steam trap (ball float type) which has been damaged most likely by water hammering (deformed floating ball) Properly functioning steam and condensate systems are vital for the support of your production plant and such support systems need to be designed, operated and maintained with great care. Particles, magnetite formation, water hammering, air venting, back pressure, corrosion, etc. are all keywords for problem areas which need to be addressed to ensure steady operation. In this context, Lonza Engineering s service could include: Design of steam systems Gap analysis and advising on energy saving potential Maintenance training Process simulation Support procurement process Project management Pls. discuss your requirements with our experts, we would be very happy to offer our support. Lonza Engineering is a subsidiary of Lonza Group Ltd and provides customer oriented services with a professional, experienced and highly motivated engineering team. We have more than 5 years of successful project management experience in China which makes us a perfect partner for the chemical, pharmaceutical and biopharmaceutical industry. A broad range of services with a project reference list underlining our capabilities is available upon request. Lonza Engineering has successfully managed multiple and complex projects such as continuous operating plants for the production of food and feed additives as well as active pharmaceutical ingredient plants including waste gas and liquid waste treatment facilities. The management team of the new company consists of current Lonza employees from Switzerland and China. Contacts Lonza Engineering Ltd Muenchensteinerstrasse 38, CH-4002 Basel, Switzerland Tel: Fax: info.engineering@lonza.com sales.engineering@lonza.com Website: Lonza Guangzhou Engineering & Consulting Co. Ltd 68, Huanggedadao Bei, Nansha district, Guangzhou, 5455, Guangdong Province, China Tel: ext.2366 Fax: info.engineering@lonza.com sales.engineering@lonza.com Website: An extensive service list is available on our website: 7 Newsletter - June 20