How centrifugal separation works | Alfa Laval

separation technology hero3

How centrifugal separation works

Separation technologies are essential to a broad range of industries—from food, beverage and pharma to marine and energy through to water and waste treatment. Various technologies are used for separating liquid from liquid and solids from liquids with the purpose to turn them into cleaner substances, valuable by-products and less volume of waste to dispose. For the food industry, for instance, olive oil is separated from olive paste. For pharma, separators are used for cell harvest clarification. For the marine industry, fuel treatment and fuel cleaning remove impurities from the fuel oil to protect ship engines, ensuring they run more efficiently. For the energy industry, biodiesel and biofuels can be extracted from renewable plant-based sources. In this chapter you will find out how various types of centrifugal separators work and what technologies are used to separate liquid from liquid and solids from liquids

Different separation technologies

There are various ways to separate liquid phases and solids from liquids. Two most common technologies are centrifugal separation and filtration. Decanters and disc stack separators (also referred to as centrifuges) are both centrifugal separators. In many processes both decanters, discs stack separators and filters are used, in different stages of the process - or even used in series - to achieve the required separation result.

Decanter centrifuges

Decanter centrifuges remove large particles from slurries or liquids with a high concentration of solids as well as separate two liquid phases of varying densities by means of centrifugal force.

how it works decanter centrifuges

Disc stack centrifuges

Disc stack centrifuges uses centrifugal force to separate liquids with a lower concentration of solids and relatively small particle sizes. It is highly suitable for separating two liquid phases as well as a solids phase.

how it works discstack centrifuges

Membrane filters

Membrane filters typically handle low solids concentrations and capture the smallest particles. Membrane filters typically remove particles up to 1 micron is size, in liquids where the solids content is 5% or less.

how it works membrane filters

How a disc stack centrifuge works

As you see above, there are various types of separation technologies available. Separation technology involving a disc stack separator/centrifuge is used for centrifugation in which various phases of solids and liquids are isolated from one another based on the difference in densities.

Learn more
how it works how disc stack works

Separator designs for solids handling

A disc stack separator separates solids and one or two liquid phases from one another using extremely high centrifugal forces. The centripetal force generated by the rotating bowl pushes solids against the periphery of the bowl, while the less dense liquid phases form concentric inner layers. The separation process can be either a discontinuous or continuous, depending on the amount of separated solids.

Learn more
HiW separator designs illustration

Designs for different separation duties

Generally speaking, there are three types of separators depending on the type of separation duty: clarifiers, purifiers, concentrators.

Clarifier

A clarifier is a centrifugal separator for solid – liquid separation, that removes solids such as particles, sediments, oil, natural organic matter and colour from process liquids. In doing so, the process liquid becomes clear.

HiW clarifier illustration

Purifier

A purifier is a centrifugal separator for liquid – liquid – solid separation, that separates two liquids of different densities, and a solids, such as water, oil, and fines, from each other. Using a purifier the light liquid phase is typically the large fraction which is meant to cleaned.

HiW purifier illustration

Concentrator

The Alfa Laval concentrator is a centrifugal separator designed to separate three different phases, one solid phase and two liquid phases of different densities, and clean the densest/heaviest liquid phase.

HiW concentrator illustration

Separator components

An Alfa Laval separator consists of a number of proven functions and high-quality components. Click on the hot-spots to learn more about each.

<style> /* misc */ .right {float: right; } /* overlay */ .overlay.show-fullscreen {opacity: 1; z-index: 100000; } /* c-modal */ .c-modal { position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%); background-color: white; border-radius: 3px; box-shadow: 0 10px 10px 0 rgba(0, 0, 0, 0.25); font-family: roboto; height: auto; width: 90%; max-width: 800px; z-index: -100; } .c-modal.show { z-index: 100000; } .c-modal .c-button { font-size: 16px; } .c-modal-title { font-size: 20px !important; font-weight: 300 !important; margin: 0 0 8px 0; padding: 0; } .c-modal-text { font-size: 14px; } .c-modal-wrapper { display: block; flex-direction: column; overflow-x: hidden; } .c-modal-image { flex: 1; text-align: center; } .c-modal-image img { max-height: 200px; width: auto; } .c-modal-content { flex: 1; } @media (max-width: 800px) { .c-modal .c-close-button { display: block; } } /* c-intersection-point */ .c-intersection-point { position: absolute; } .c-intersection-point:hover { cursor: pointer; } .c-intersection-point:hover svg g#Oval-Copy-2 { fill: white; } .c-intersection-point:hover svg g#Group-2 g { fill: #23337e; } .c-intersection-point svg { position: absolute; margin-left: -18px; margin-top: -18px; display: block; width: 36px; height: 36px; border-radius: 50%; background: #5a99d4; cursor: pointer; box-shadow: 0 0 0 0 #23337e; -webkit-animation: pulse 1.5s infinite; animation: pulse 1.5s infinite; } .c-intersection-point svg:hover { box-shadow: none; } _:-ms-fullscreen, .c-intersection-point:hover svg { animation: none; } @keyframes pulse { 0% { transform: scale(1); } 70% { transform: scale(1); box-shadow: 0 0 0 15px rgba(90, 153, 212, 0); } 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(90, 153, 212, 0); } } @-webkit-keyframes pulse { 0% { transform: scale(1); } 70% { transform: scale(1); box-shadow: 0 0 0 15px rgba(90, 153, 212, 0); } 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(90, 153, 212, 0); } } </style> <script> "use strict"; var flowchart = function() { var intersectionPoints = {}; var updateFunctions = []; function init() { createModal(); addCloseToOverlay(); createCharts(); window.addEventListener("keydown", function(event) { if (event.key === "Escape" || event.key === "Esc") closeModal(); }); for (var i = 0; i < 5000; i += 200) { setTimeout(updatePoints, i); } } function createCharts() { Object.keys(intersectionPoints).forEach(function(key) { var id = document.getElementById(key); if (id) { var chartParent = id.nextElementSibling.nextElementSibling; if (chartParent) { var img = chartParent.children[0]; img.style.display = "block"; img.style.width = "100%"; var imgContainer = document.createElement("div"); imgContainer.appendChild(img); chartParent.appendChild(imgContainer); renderCordsOnChart(key, imgContainer); } } }); } function addPoints(id, object) { intersectionPoints[id] = object; } function addCloseToOverlay() { var overlay = document.querySelector(".overlay"); var modal = document.querySelector("#modal"); if (overlay) { overlay.addEventListener("click", function() { overlay.classList.remove("show-fullscreen"); modal.classList.remove("show"); }); } } function renderCordsOnChart(id, chart) { chart.style.position = "relative"; var cords = intersectionPoints[id]; var renderedCords = []; var _loop = function _loop() { var hover = cords[i].title || "Click for more information"; cord = document.createElement("div"); cord.innerHTML = icon.replace('_hotspotTitle_', hover); cord.classList.add("c-intersection-point"); cord.style.left = cords[i].x + "px"; cord.x = cords[i].x; cord.style.top = cords[i].y + "px"; cord.y = cords[i].y; var card = cords[i]; cord.addEventListener("click", function() { return showModal(card); }); chart.appendChild(cord); renderedCords.push(cord); }; for (var i = 0; i < cords.length; i++) { var cord; _loop(); } window.addEventListener("resize", function() { return updateCordsPositions(chart.children[0], renderedCords); }); updateFunctions.push(function() { return updateCordsPositions(chart.children[0], renderedCords); }); } function updateCordsPositions(image, cords) { var ratio = image.width / image.naturalWidth; for (var i = 0; i < cords.length; i++) { cords[i].style.left = parseInt(cords[i].x) * ratio + "px"; cords[i].style.top = parseInt(cords[i].y) * ratio + "px"; } } function showModal(card) { var overlay = document.querySelector(".overlay"); if (overlay) { overlay.classList.add("show-fullscreen"); } var modal = document.getElementById("modal"); if (!modal) return; modal.children[1].innerHTML = renderModalTemplate(card); modal.classList.add("show"); } function createModal() { var modal = document.createElement("div"); var modalInner = document.createElement("div"); var closeButton = document.createElement("i"); modal.id = "modal"; closeButton.classList.add("c-close-button"); closeButton.classList.add("m-16"); modalInner.classList.add("c-modal-inner"); modal.classList.add("c-modal"); closeButton.innerHTML = closeButtonMarkup; closeButton.addEventListener("click", function() { return closeModal(); }); modal.appendChild(closeButton); modal.appendChild(modalInner); document.body.appendChild(modal); } function closeModal() { var overlay = document.querySelector(".overlay"); if (overlay) { overlay.classList.remove("show-fullscreen"); } var modal = document.getElementById("modal"); if (!modal) return; modal.classList.remove("show"); } function updatePoints() { updateFunctions.forEach(function(f) { return f(); }); } return { init: init, addPoints: addPoints, intersectionPoints: intersectionPoints, updatePoints: updatePoints }; }(); var icon = '<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="36px" height="36px" viewBox="0 0 36 36" version="1.1"><title>_hotspotTitle_</title><defs><circle id="path-1" cx="18" cy="18" r="18"/></defs><g id="icons/flowchart-marker-hover" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd"><g id="Oval-Copy-2"><use fill="#23337e" fill-rule="evenodd" xlink:href="#path-1"></use><circle stroke="#23337E" stroke-width="3" cx="18" cy="18" r="16.5"></circle></g><g id="Group-2" transform="translate(12.5, 12.5)" fill="#ffffff"><g id="Group"><rect id="Rectangle" x="4" y="0" width="2.647" height="11" rx="1"></rect></g><g id="Group-Copy"><rect id="Rectangle" x="0" y="4" width="11" height="2.647" rx="1"></rect></g></g></g></svg>'; var closeButtonMarkup = '<svg width="16px" height="16px" viewBox="0 0 16 16" version="1.1" xmlns="http://www.w3.org/2000/svg"><title>Close</title><g id="Icons/Close" stroke="none" strokeWidth="1" fillRule="evenodd"><path d="M8,7.3228206 L15.3228206,0 L16,0.677179397 L8.6771794,8 L16,15.3228206 L15.3228206,16 L8,8.6771794 L0.677179397,16 L0,15.3228206 L7.3228206,8 L0,0.677179397 L0.677179397,0 L8,7.3228206 Z" id="Combined-Shape" fillRule="nonzero" /></g></svg>'; function renderModalTemplate(card) { var CTAMarkup = card.CTA ? '<div class="mt-32"><a href="'+ card.href +'" class="c-button is-primary is-large right">'+ card.CTA +'</a></div>' : ''; var imageMarkup = card.image ? '<div class="c-modal-image"><img src="'+ card.image +'""></div>' : ''; return '<div class="c-modal-wrapper p-32">'+ imageMarkup +'<div class="c-modal-content"><div class="flex column justify-content-between"><div class="wysiwyg"><p class="c-modal-title">'+ card.title +'</p><p class="c-modal-text">'+ card.text +'</p></div>'+ CTAMarkup +'</div></div></div>'; } </script><style type="text/css"> #modal.c-modal table { border-width: 0; margin: 24px 0 0 0; } #modal.c-modal td { vertical-align: top; width:33.33%;} #modal.c-modal a.c-button, #modal.c-modal a.c-button:visited { color:#fff; } </style> <div id="fuel-line-troubleshootingg"></div> <script> flowchart.addPoints("fuel-line-troubleshootingg", [ { x : 425, y : 92, title: 'Outlet zone', text : '<p>Area where the cleaned liquids leavethe bowl.</p>' }, { x : 520, y : 140, title: 'Seals', text : '<p>Separators with Hermetic Design have seals in the outlet zone to ensure no leakage of the process liquid from the separator, or for air to encounter the process fluid in the separator</p>' }, { x : 569, y : 290, title: 'Disc stack', text : '<p>Conical discs (bowl discs) stacked on top of each other provide high additional separation surface area. Thin caulks on each disc provide space in between the discs in the disc stack.</p>' }, { x : 683, y : 350, title: 'Solids discharge port', text : '<p>Automatic removal of solids from disc stack separators is made in one of two ways:<br>-Continuous solids discharge through nozzles in the periphery of the bowl <br>-Intermittent solids discharge, in which a carefully designed system opens ports in the periphery of the bowl, at controlled intervals</p>' }, { x : 590, y : 675, title: 'Drive', text : '<p>A drive unit, including an electric motor, is needed to transfer the power required to rotate the bowl. Typical drive units are gear-drive, belt-drive and direct drive.</p>' }, { x : 520, y : 952, title: 'Inlet zone', text : '<p>Point of entry for the feed (process liquid to be cleaned), either at the top or bottom of the separator.</p>' }, { x : 450, y : 248, title: 'Bowl', text : '<p>The central vessel, including the disc stack where separation takes place.</p>' } ]) </script>
HiW hotspot separator
<script>flowchart.init(); flowchart.updatePoints();</script>

Explore our innovations

Would you like to know more about our innovations in separation technology? Click on the link below. Alfa Laval invented the first disc stack separator and has led the way in the development of centrifuge technology for over a century. We are glad to share with you the expertise we have gained along the way. Visit our Separator Innovator knowledge base to learn more about advancements in separation and the steps Alfa Laval is taking to continue revolutionizing the technology.

Learn more about our innovations for separation industry
Separator Innovator 640x360