Energy Saving in Cleanrooms

Transcription

1 Energy Saving in Cleanrooms Energy Saving in Cleanrooms Dr. Alexander Fedotov, Director of Invar-project Company, Moscow, Russia Presentation discusses : Methods of energy saving; Air change rate: how big it should be? Recovery time: norms and real sense; Clothes and energy consumption; Design and operation: different estimation of cleanliness level Examples were presented by Invar-project 2 Energy Saving in Cleanrooms Cleanrooms consume a lot of energy and are extremely ineffective facilities; But there is still not enough attention to it; In contrary over-specifying and over-designs are in common practice; This negative picture is often based on normative documents or wrong interpretation of them Energy Saving in Cleanrooms Existing International Standards for energy effectiveness are too general and useless; At national level two standards give detailed guidance: - British standard BS 8568:201; - German VDI 208 standard; But the problem is so complicated that further researches are necessary 4 Table 1. Examples of energy consumption in CR Class Power, kw/m 2 Energy consumption growth Semiconductor facility Non-classified % or 1,0 ISO % or 2,0 ISO % or 4,4 ISO % or 2 ISO 4/ % or 48 5 Table 1 Examples of energy consumption in CR (continuation) Class Power, kw/m 2 Energy consumption growth Non-sterile ointments Non-classified 0,05 100% or 1,0 D 0,10 200% or 2,0 Aseptic production Non-classified 0,06 100% or 1,0 D 0,41 680% or 6,8 C 0,50 80% or 8, B 1,52 250% or 25, 6

2 2. Methods of Energy Saving General for any kind of rooms and buildings Specific for cleanrooms General methods (numerous): Isolation of buildings; Heat recuperation; Air recirculation minimum outdoor air; High efficiency ventilators, AHUs and chillers; Temperature and humidity avoiding unnecessary narrow tolerances; Removal of heat load from equipment by local in-built means rather then by HVAC; etc. 8 Specific Cleanroom methods: Reducing cleanroom squares to minimum; Avoiding over-specifying of cleanliness class; Use of HEPA filters with small pressure drop; Minimizing of personnel present closed systems (RABS, isolators etc.); Good clothes, Good Operation Practice; Not to over-specify air flow rate; Not to over-specify recovery time; etc. 9 Unidirectional air flow Air flow velocity is the key factor; It was discussed in many publications that 0,45 m/s is over-specifying; 0,45 m/s = 90 feet/min from early version of Fed. Std. 209; It migrated to GMPs; In s it was shown that 0, m/s is enough; In 1980-s this norm was withdrawn from Fed. Std. 209 but remained in GMP 10 Unidirectional air flow GMP requests 0,6-0,54 m/s (0,4510%); In EU it is the same for aseptic and terminal sterilization processes: what about sense? GMP EU 1989: Laminar air flow systems should provide homogeneous air speed of 0,0 m/s for vertical flow and 0,45 m/s for horizontal flow 11 Non-unidirectional air flow: Cleanrooms ISO 8 ISO 6 classes and ISO 5 at rest only (most cleanrooms); Two parameters are of key importance: - Air change rate; - Recovery time. They can request great energy consumption for air heating, cooling, humidification and drying. 12

3 How does energy consumption depend on air change rate? Different sources of information present different numbers; BS 8568:201 says: A 50% reduction on flow gives 88% reduction in power that means 8 times reduction in power; In fact it is hardly possible to give one formula for any case; So practical examples can be helpful. Power consumption for non-sterile ointments facility (Moscow region) Energy consumer Power, kw for air flow m /h m /h Ventilators HVAC 0 15 Air heating: - hot water (1 st stage) - electricity (2 nd stage) Cooler (electric power) 5 1,5 Humidification (steam) 1 45 Total consumption: -winter:electric power 24 0 hot water summer: electric power Air change rate depends on: Necessary volume of outdoor air for hygiene reasons (fresh air for breathing); Typical diagram of air change rate for cleanroom Air change rate, h Compensation of local exhausts; Maintaining air pressure difference; Elimination of heat loads; Bad Good Bad Providing necessary cleanroom class. 0 Outdoor air Compensation of local exhausts Pressure difference Heat loads Cleanroom class What air change rate is needed? 1950s USA norms for surgical suites: - 12 h for existing ones; - 25 h as a minimum for new ones. 1960s early Fed Std h ; 1980s Fed Std 209D CANCELLED these 20 h ; 198 FDA Aseptic Guide copied 20 h ; 2004 revision of this Guide remained it Interesting picture again: - Cleanroom professionals study cleanrooms and understand them better Recommendations become easier - GMP regulators move in contrary direction Norms become tighter This is one of reasons for over-specifying 1 18

4 Norms for Air change rate FDA Aseptic Guide (ISO 8 in operation) Sterile products (supporting rooms) Terminal Aseptic sterilization These are norms But what is really needed? Non-sterile products GMP EU ISPE Guide WHO Report Reducing of particles concentration in zone C (ISO at rest ) At rest Particles/m in room at start: 5 E+ = 5 õ10 Particles/s from process: 1 E+2 = Å+6 ISO N=5 h N=10 h 1 Å+ N=15 h N=20 h 20 Reducing of particles concentration in zone C in operation (ISO 8 is the target) In operation Clean room clothes Particles/m in room at start: 5 E+ = 5 õ10 4 Particles/s from process: 1 E+4 = 10 People: 4 8 ISO 1 Å+6 N=5 h N=10 h ISO N=15 h N=20 h 1 Å+ Conclusions from curves: All curves tend to some constant value that is quite good for this cleanroom; Cleanliness class can be reached even for air change rate 5 h ; Difference is in stabilizing period or in recovery time! Air change rate depends mainly on recovery time for many applications What is recovery time? ISO standard says: It is time required for decreasing initial contamination of particles by factor of 100 (100:1 recovery time); Some other guides say that it is time to reduce contamination level to at rest state after being in operation. What is recovery time? Normally it is deemed that Recovery time should be min. But WHY? Why min, not 40 or 60? if Risk for different processes is very different 2 24

5 Requirements for Recovery time Sterile products (supporting rooms) Aseptic, before and after sterilization Before After Terminal sterilization Non-sterile products GMP EU ISPE Guide WHO Report Aseptic manufacturing scheme Increasing recovery time from 20 to 40 min allows to reduce air change rate from 20 to 10 or to reduce energy consumption to 25 % At rest Particles/m in room at start: 5 E+ = 5 õ10 2 Particles/s from process: 1 E+2 = 10 1 Å+6 ISO N=10 h 1 Å+ N=20 h Energy consumption for Start-up and Stable operation are different dramatically: - Driving a car; - Start-up of electric engines, etc. Start-up Stabilized work Why Cleanrooms shall work with big air change rates after reaching stabilized period? - Why not to switch on cleanroom min before start of process? - and to arrange monitoring even for ISO ISO 8 classes to keep process under control? 29 Clothes Clothes have great impact on particles generation as shown by Dr. B. Reinmüller and Prof. B. Ljungqvist Particle emission can be estimated at design stage to determine air change rate 0

6 Clothes Rounded numbers of particles emission are used to make illustration simpler: Cleanroom clothes (jacket and trousers) particles/s; Good cleanroom clothes (overall) 1000 particles/s. Reducing of particles concentration for different clothes for air change rate 20 h In operation Particles/s from process: 1 E+ = 10 People: 4 1 Å+6 ISO clean room clothes 1 Å+ good clean room clothes 1 2 Reducing of particles concentration for different clothes for air change rate 10 h In operation Particles/s from process: 1 E+ = 10 People: 4 1 Å+6 ISO clean room clothes good clean room clothes 1 Å+ Clothes Good clothes can dramatically reduce air change rate and energy consumption; Changing Cleanroom clothes to Good cleanroom clothes allows to upgrade cleanroom class for one level without other expenses; It is preferable to use good cleanroom clothes even for ISO ISO 8 classes rather than to increase air change rate. 4 Sources of contamination in cleanrooms Sources Knowledge on Particles emission Design Operation Gap External air ~ 0 ~ 0 0 Personnel Can be estimated Can be checked ~ 0 Equipment and process Contamination because of poor operation, cleaning, etc. Lack of knowledge, approximate estimation ~0 Considered that operation is Good Can be checked Gap 1 Is operation really good? Gap 2 Design and operation huge gap of information Gap 1 Lack of knowledge on particles emission at design stage Reserve or Margin of cleanliness (can be big) The first reason of over-design 5 6

7 Design and operation huge gap of information Gap 2 Bad Operation Practice Reserve of cleanliness is used to cover poor operation The second reason of over-design Flexible approach Design stage: to make reasonable Margin of Air change rate (redundancy); Testing: to determine real particles generation and to learn how big Margin is; Operation: -to consider Margin and to operate Cleanroom at reduced capacity; - to follow Good Operation Practice; -tomonitor cleanliness and to make trend analysis. 8 Design Testing Stages Flexible approach (offered) Practice of determining and maintaining Air change rate N Now Offered Specifying Air change rate N Testing on compliance to N and Cleanliness class Specifying Air change rate N Determining real particle emission and necessary N 1 << N Thank you for your attention! Operation Operation with N Operation with N 1 << N Energy consumption 100% 20-50% 9 40