Continuous blowdown valve
Continuous blowdown valve from selection to delivery
Continuous blowdown valve examined up close
A continuous blowdown valve removes a small water flow from the boiler drum continuously, in order to hold the dissolved solids concentration at a stable level. In practice continuous blowdown valve is rarely a standard question once medium and temperature move away from average. There are assumptions circulating about continuous blowdown valve that do not hold up under closer examination. A pressure reducing station brings steam pressure back to the level the consumers require and holds that pressure stable under varying demand. In superheated steam the temperature sits above saturation, and soft seats and ordinary packings are then no longer usable. An emergency stop valve shuts off supply in a hazardous situation, and closing time there is a safety parameter rather than a comfort requirement. That principle explains why continuous blowdown valve behaves differently from a standard execution under heavier duty. With continuous blowdown valve it pays to include phase changes in the medium, because those sharply increase the load on the seal. A correct execution of continuous blowdown valve accounts for real operating conditions and not only for design values. On a boiler, blowdown valves control the salt content of the boiler water, with continuous blowdown for fine control and periodic blowdown for sludge at the bottom. Condensate carried along in a steam line causes erosion and water hammer, and both attack a valve faster than the steam itself. The subject of continuous blowdown valve touches both the construction of the valve and the way the plant is operated.
Specifications and executions of continuous blowdown valve
Continuous blowdown keeps water chemistry steady, while periodic bottom blowdown deals with sludge in short bursts. How continuous blowdown valve behaves under varying load says more about the quality of the selection than behaviour under steady load. In practice we find that most failures around continuous blowdown valve come not from the material but from a wrong assumption during selection. Because the flow is small and the pressure drop is large, flashing occurs inside the valve and the trim has to be built for that. Steam is a demanding medium because pressure and temperature rise together and the medium can change phase within the same line. A turbine bypass routes steam around the turbine during start up and on a trip, and that valve has to handle a large duty within seconds. A desuperheater injects water into the steam flow to bring temperature back to just above saturation, where atomisation quality determines the result. Automatic control on conductivity measurement saves feedwater and energy against a fixed manual setting. Insulation around a steam valve should leave the actuator clear, because overheating of the actuator is a common cause of failure. On steam we always advise a condensate drain upstream of the valve, because it is the cheapest life extension available. Operating conditions govern the service life of continuous blowdown valve far more strongly than the nominal figures on a datasheet. For continuous blowdown valve this means that construction and operating conditions cannot be judged separately.
Continuous blowdown valve in chemicals, power and process industry
These valves sit on the drum of high pressure boilers in power generation and in industrial steam plant. In power generation these valves sit on the critical paths around boiler and turbine, where downtime costs money immediately. In process industry steam is used for heating, stripping and sterilisation, and each of those duties sets its own requirements. The application range of continuous blowdown valve runs from simple utility duty to heavy process plant, with a corresponding difference in execution. We supply continuous blowdown valve both for new build and for replacement within existing installations. We see demand for continuous blowdown valve rising in hydrogen and ammonia projects, where tightness requirements are high. In an existing plant continuous blowdown valve is often part of a wider question about availability and maintenance. Boiler houses, combined heat and power plants and district heating together form the largest application area for these valves. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users. What defines us is that we would rather spend an extra half hour on the specification than ship the wrong valve that comes back two months later. On project supply we record per position which execution of continuous blowdown valve was delivered, including materials and tests. During turnarounds continuous blowdown valve is regularly on the critical path, and then predictability matters more than the lowest price.
Selection criteria for continuous blowdown valve
Where there is doubt about continuous blowdown valve we quote two executions side by side, with the trade offs stated explicitly. On steam applications we always ask for pressure and temperature upstream and downstream, because pressure drop defines the trim construction. For safety functions we record the required closing time and fail position explicitly in the order. A steam test device makes it possible to test the operation of safety valves while the plant stays in service. If a simpler type will do the job, we say so on continuous blowdown valve, even when that means a smaller order. We never recommend a heavier execution of continuous blowdown valve than needed, because over specification only raises price and lead time. On continuous blowdown valve we check that the actuator is sized on torque at maximum differential pressure and not on an average value. The required leakage class often drives the choice around continuous blowdown valve more strongly than the budget does. PRUSS is strongly represented in this segment with valves for steam, boiler, turbine and gas turbine duty. On commissioning we record set pressure, closing time and test results, so the plant can be shown to run within specification. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. On continuous blowdown valve we also state what an execution cannot do, because that prevents more problems than a list of advantages. For continuous blowdown valve we ask as standard for DN, pressure class, medium, temperature and required actuation.
Ordering continuous blowdown valve from Dutch Valve Vision
We supply continuous blowdown valve as a loose product or as a fully assembled unit with actuator and accessories. We work as a technical supplier rather than a catalogue reseller, which means we carry out the selection ourselves on the basis of medium, pressure, temperature and code requirements. Even when the specification for continuous blowdown valve is not yet finalised, you can bring the question to us. We handle an enquiry for continuous blowdown valve on its technical merits rather than as a price request that only produces a number. On continuous blowdown valve we come back with a proposal that explains why we recommend a particular execution. For shutdowns and turnarounds we look at accelerated routes, and in those cases we are honest up front about what is and is not achievable. Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. We work on continuous blowdown valve under a KIWA ISO 9001 certified quality system, which safeguards traceability. A tag plate with project data belongs with continuous blowdown valve as standard where the project requires it. We keep the configuration data for continuous blowdown valve on file, which saves a great deal of searching if a fault occurs later. We think along on the spare parts strategy for continuous blowdown valve, so critical positions stay covered. Call +31 (0)70-2210560 or send your specification to sales@dutchvalvevision.com and we will pick it up.
Frequently asked questions about continuous blowdown valve
What exactly does continuous blowdown valve mean?
A pressure reducing station brings steam pressure back to the level the consumers require and holds that pressure stable under varying demand. In superheated steam the temperature sits above saturation, and soft seats and ordinary packings are then no longer usable. An emergency stop valve shuts off supply in a hazardous situation, and closing time there is a safety parameter rather than a comfort requirement. A turbine bypass routes steam around the turbine during start up and on a trip, and that valve has to handle a large duty within seconds. On continuous blowdown valve we include start up and shutdown, because that is where the heaviest loading occurs. The answer to this question on continuous blowdown valve changes as soon as the medium or the temperature changes. The term continuous blowdown valve is used broadly in the market, which is why it helps to define precisely what it means in your case. We think along from the basic specification through to the tag plate, and supply documentation that a buyer or inspector accepts without discussion.
Which executions of continuous blowdown valve are available?
On a boiler, blowdown valves control the salt content of the boiler water, with continuous blowdown for fine control and periodic blowdown for sludge at the bottom. Condensate carried along in a steam line causes erosion and water hammer, and both attack a valve faster than the steam itself. Continuous blowdown keeps water chemistry steady, while periodic bottom blowdown deals with sludge in short bursts. A desuperheater injects water into the steam flow to bring temperature back to just above saturation, where atomisation quality determines the result. For continuous blowdown valve a good specification up front is cheaper than a correction afterwards. In most projects continuous blowdown valve turns out to be less standard than it first appears. The balance between required tightness and available operating force is a recurring tension on continuous blowdown valve. What defines us is that we would rather spend an extra half hour on the specification than ship the wrong valve that comes back two months later.
Which materials are used for continuous blowdown valve?
Automatic control on conductivity measurement saves feedwater and energy against a fixed manual setting. On steam we always advise a condensate drain upstream of the valve, because it is the cheapest life extension available. On commissioning we record set pressure, closing time and test results, so the plant can be shown to run within specification. Because the flow is small and the pressure drop is large, flashing occurs inside the valve and the trim has to be built for that. If you are unsure about this on continuous blowdown valve, we are glad to put the question alongside the actual process data. We see this come back regularly in enquiries about continuous blowdown valve, and the answer is rarely a single sentence. On continuous blowdown valve we always check the full operating envelope, including start up and shutdown. Dutch Valve Vision supplies special valves for special applications from its base in Monster, the Netherlands, with QUADAX and PRUSS as the core brands in the programme.
What should I watch technically on continuous blowdown valve?
What should I watch technically on continuous blowdown valve?
Which applications call for continuous blowdown valve?
In process industry steam is used for heating, stripping and sterilisation, and each of those duties sets its own requirements. Boiler houses, combined heat and power plants and district heating together form the largest application area for these valves. In power generation these valves sit on the critical paths around boiler and turbine, where downtime costs money immediately. These valves sit on the drum of high pressure boilers in power generation and in industrial steam plant. We always explain why we arrive at a particular recommendation on continuous blowdown valve, so you can follow the reasoning yourself. This is one of the points on continuous blowdown valve where suppliers differ most clearly from one another. Our customers use continuous blowdown valve in positions where a failure has immediate consequences for production. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users.
What determines the price and lead time of continuous blowdown valve?
We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. For shutdowns and turnarounds we look at accelerated routes, and in those cases we are honest up front about what is and is not achievable. Lead times depend on the execution, because a standard size from a running series behaves very differently from a valve in an exotic alloy with NACE certification. On continuous blowdown valve we prefer a well founded answer to a fast one that turns out to be wrong later. The answer on continuous blowdown valve depends strongly on operating conditions, which is why we always ask for those first. Dutch Valve Vision stays available after delivery of continuous blowdown valve for technical questions and for parts. Bring us your question at sales@dutchvalvevision.com or +31 (0)70-2210560, even when the specification is not finalised yet.
What about maintenance and spare parts on continuous blowdown valve?
We quote a realistic lead time rather than an optimistic one, because a missed delivery date costs more than an extra week in the planning. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. We keep spare parts and overhaul kits mapped per project, so that a breakdown does not start with a search from scratch. Lead times depend on the execution, because a standard size from a running series behaves very differently from a valve in an exotic alloy with NACE certification. The answer on continuous blowdown valve depends strongly on operating conditions, which is why we always ask for those first. In most projects continuous blowdown valve turns out to be less standard than it first appears. Documentation on continuous blowdown valve has to be the kind a buyer or inspector accepts without discussion. Alongside QUADAX and PRUSS we represent Pibiviesse, Schroeder, Striko, Malbranque, Daume, FluoroSeal and Guichon, so we can select the right brand for each project.
How do I request a quotation for continuous blowdown valve?
If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. A P&ID, a datasheet or even a photograph of the existing installation often helps us faster than a long description. We see this come back regularly in enquiries about continuous blowdown valve, and the answer is rarely a single sentence. Our experience with continuous blowdown valve comes from projects in chemicals, power generation, technical gases and offshore. Our specialists are happy to discuss continuous blowdown valve on the basis of your P&ID, your datasheet or simply a photograph of the situation. Send us your DN, pressure class, medium and temperature at sales@dutchvalvevision.com, or call +31 (0)70-2210560 to speak to a specialist.