Tag Archives: HRS Heat Exchangers

The Role of Zero Liquid Discharge in Reducing Hazardous Wastes

Thanks to tighter environmental regulations and greater public awareness, companies are increasingly looking to reduce or eliminate the waste that they produce. In recent years, Zero Liquid Discharge (ZLD) has become an important waste reduction technique, but its potential in dealing with hazardous waste streams has not been fully appreciated until now.

One of the advantages of ZLD over other treatment techniques is its theoretical ability to separate unwanted materials from water, whether they are benign, hazardous or toxic. The resulting solid residue is often more stable, making it suitable for recycling or landfill. A well-designed ZLD system should minimise or even eliminate liquid waste streams, resulting in clean water for reuse or environmentally-friendly discharge, and a solid residue suitable for further processing (often to recover valuable components for use elsewhere) or for safe disposal.

Correct analysis is crucial

The composition of wastewater streams varies greatly; certain wastewater sources, such as power plants and boilers with wet gas scrubbing, often contain salts which may be hazardous, valuable, or both. Environmental regulation usually means that treatment is required to reduce or remove such toxic compounds before wastewater can be discharged. Other sources, such as wet flue gas desulfurization, may contain highly soluble calcium and aluminium salts, as well as heavy metals, which are not easily crystallised by evaporation.

The effective design of any ZLD system, and the appropriate pre-treatment processes, is therefore dependent on the correct analysis of the water/waste stream, making it essential to have an accurate analysis of composition, flow rates, chemistry, etc. Without this, any designed solution will fail to deliver the required results, if it works at all.

Energy-efficient evaporation

Vapour compression evaporation is commonly used in ZLD as evaporation can recover up to 95 per cent wastewater as distillate. Any remaining concentrate is further treated physically or chemically to produce solid residues (such as crystals) and water. By running the evaporators at lower pressures, the boiling point of the liquid being treated is reduced. This means that multi-effect evaporation can be made possible; that is, steam from a previous evaporation stage is used as thermal energy in the next stage which works at a lower boiling point. This way, multiple evaporation stages are combined, generating significant energy savings. For many components, crystal precipitation is favoured at lower temperatures, therefore lowering evaporation temperatures helps to increase the solids yield.

The role of heat exchangers

HRS Heat Exchangers is in the final commissioning stage of a ZLD system for an industrial client in Europe. Heat exchangers play a crucial role in reducing the running costs of a ZLD system by utilising heat from process water and other existing sources, and also recapturing heat at the end of the process and reusing it to boost the energy efficiency of the overall ZLD system. Where there is a hazardous liquid waste stream to deal with, then the potential to utilise ZLD techniques as part of the overall treatment solution should definitely be investigated, and HRS staff would be happy to discuss the potential options with you.

1 http://nimkartek.com/blog/zero-liquid-discharge-a-solution-to-zero-discharge-of-hazardous-chemicals/

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Heat Exchangers to improve AD plant efficiency

At BioCycle REFOR18 stand 38, HRS Heat Exchangers will be demonstrating the crucial role that heat exchangers can play in improving the overall efficiency of biogas plants: from pre-heating feedstock to concentrating and pasteurising digestate.

HRS Heat Exchangers provides a wide range of dedicated heat exchangers for the anaerobic digestion sector around the world, including feedstock and sludge heaters, multi-tank pasteuriser systems, evaporators, exhaust gas cooling, thermal hydrolysis, the HRS Digestate Concentration Systems (DCS) and the HRS Biogas Dehumidification System (BDS). Due to their high efficiency design which can include heat regeneration, not only do many HRS units need no additional energy input – instead utilising existing previously wasted heat from CHPs and other processes, but they maximise the amount of heat which can be re-used again.

HRS Heat Exchangers’ International Sales & Marketing Director Matt Hale explains:
“Every anaerobic digestion (AD) facility is different, but all of our systems are designed to recapture and utilise energy which would otherwise go to waste. Not only does this increase the efficiency of both our equipment and the AD plant overall, but it is also good for your pocket and good for the environment.”

Experienced HRS staff will be on hand throughout the BioCycle REFOR18 event to explain the full range of HRS products to the anaerobic digestion sector, including:

  • Biogas cooling: cooling and recapturing the heat from exhaust gases, for example using an HRS G Series heat exchanger, can increase the efficiency of combined heat and power (CHP) plants, with the recovered energy being used elsewhere in the plant.
  • Feedstock and sludge heating: maintaining the ideal digester temperature (particularly in the case of thermophilic plants) is essential for full material conversion, while pre-heating the feedstock prior to putting it in the digester can reduce the amount of heat needed in the digester itself. For such applications the HRS DTI Series of heat exchangers is ideal for ensuring a high level of heat transfer while minimising blockages or fouling.
  • Feedstock or digestate pasteurisation: not only are there legislative or quality drivers for pasteurisation, but operators of AD plants are increasingly seeing pasteurisation as a way of demonstrating the quality of their digestate product and increasing its value. HRS DPS (Digestate Pasteurisation Systems) are specifically designed to cope with difficult materials while maximising energy efficiency.
  • Digestate concentration & evaporation: reducing the volume of digestate can not only improve its quality as an organic fertiliser, but it also reduces storage, transport, application and disposal costs. The HRS DCS (Digestate Concentration System) uses a multi-stage evaporation process to concentrate digestate.
    Thermal hydrolysis for enhance biogas production: HRS has developed a process for the continuous thermal hydrolysis of digester sludge. This treatment changes the cell structure of the compounds, breaking down lignin and hemi-cellulose chains to create free sugars which are easier for the bacteria to digest.
  • Biogas Dehumidification System: The HRS BDS Series is an efficient solution to cool and dehumidify biogas for combustion. The system condenses up to 90% of the water contained in the gas, which is continuously separated before the lean biogas is ready for use.

Matt Hale adds:
“If you have an AD plant, then we can supply the best system for any thermal process associated with the feedstock, digestion, biogas or digestate. Not only that, but a heat recovery step can be included as a standard option on most of our systems, reducing energy costs by between 20 and 40% which also reduces the payback period considerably. Most of our equipment is easily integrated into existing plants, or we can design bespoke solutions for more complex applications. In addition our systems include state of the art system monitoring and cleaning systems, to reduce management time and effort.”

Learn more about the full range of AD systems from HRS Heat Exchangers on Stand 38 at BioCycle REFOR18 in October.

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Think you can’t evaporate with low temperatures? Think again…

When treating wastewater, sludge and digestate, it can be beneficial to reduce the volume of material or increase the solids content. Mechanical dewatering via a centrifuge or belt press to separate solids and liquids is standard for the water treatment and anaerobic digestion sectors – but what if you want to further reduce the water content of the remaining liquid fraction?

The two main reasons to remove or reduce water from effluent and waste are either to reduce the volume of material in order to cut storage, handling and disposal costs; or to produce materials with distinct properties (such as liquid and solid fractions of digestate), which can then be stored and used in the most appropriate way. The traditional options are drying (which requires large quantities of heat and energy, is costly and inefficient) and evaporation (usually requiring temperatures in excess of 100ºC).

Energy efficient evaporation

However, for many types of effluent, low temperature evaporation can be very energy efficient. Where process temperatures are 85-90º C, low temperature evaporation combines the use of a vacuum to reduce the boiling point of the liquid to be removed, together with traditional high temperature evaporators, based on heat exchanger technology, and surplus heat from heaters and CHP engines can often be utilised for the process.

Heat exchangers from HRS are capable of recovering such heat and using it as the basis for an evaporation system can further improve overall process efficiency. Additionally, using a vacuum in the system to reduce the boiling point reduces the amount of energy required even further. Combining systems into a multiple-effect evaporator allows larger quantities of water to be removed for the same initial heat input, with the vapour boiled off in one vessel used to heat the next.

Selecting the right heat exchanger

The type of heat exchanger used will depend on the nature of the products being treated. For materials with low or medium viscosities, such as wastewater and effluent with low concentrations of organic solids, using the HRS K Series as an evaporator module provides high heat transfer rates with good resistance to fouling. For more challenging and viscous materials, such as thicker effluents, digestate and solids with higher dry matter concentrations, the HRS Unicus Series contains a self-cleaning scraper mechanism which reduces fouling and maintains heat transfer rates (and therefore operational efficiency).

While both the K Series and Unicus Series are commonly used in the type of multi-effect evaporation system described above, both heat exchanger models can also be used in other types of evaporator, such as mechanical vapour recompression (MVR) or thermal vapour recompression (TVR) systems, depending on the needs of the product or application.

The ultimate use of HRS heat exchangers for low temperature evaporation can be found in the HRS Digestate Concentration System (DCS), which uses multiple evaporation effects to increase the solids in liquid digestate three- to four-fold. Whether you want to minimise effluent and digestate volumes using the DCS, or simply reduce them in a more energy efficient way, HRS Heat Exchangers has a low temperature evaporation solution to achieve the required results.

The post Think you can’t evaporate with low temperatures? Think again… appeared first on HRS Heat Exchangers on 10 July 2018.

Heavy duty heat exchanger tackles nut butter challenge

Nut butter is one of the big food trends of the last two years. Once the only choice on the shelf would have been between smooth or crunchy peanut butter, but recently, as the health benefits of quality nut butter have been understood, the market has exploded to include peanut, almond, cashew, and even seed butters, often including other additives such as high quality cocoa, coconut and coffee. However, producers of these products all share one major challenge. Nut butter is extremely viscous – almost solid at low temperatures – making it very difficult to move through processing machinery.

Most nut butters are semi-solids, as shown by the fact that they will hold a peak. At room temperature peanut butter is at least five times thicker than tomato ketchup, but at colder conditions it becomes even more viscous, as anyone who has tried to spread it straight from the fridge will know. Adding stabilisers, such as partially hydrogenated vegetable oils, to prevent oil separation, can actually make the problem worse as they form a crystalline structure with higher levels of viscosity.

For HRS Heat Exchangers the problem was highlighted when a client ordered an R Series Scraped Surface heat exchanger for a nut butter line, as HRS International Sales and Marketing Director Matt Hale explains:

Although the R Series is purposely designed for viscous materials some very solid materials, like low temperature peanut butter, were a step too far. The thickness of the cold nut butter was beyond the parameters of the R Series gearbox and its mountings, and the unit we were testing failed. However, the experience highlighted the need for a heavy duty version of the R Series, so our R&D team set to work to produce a scraped surface heat exchanger for materials like nut butters that are almost solid. The result is the new HRS RHD Series for heavy duty applications.

The HRS engineering team set out to maintain the benefits of the standard R Series – such as the continuous scraping action to enhance the mixing of viscous products and the unique sealing system which allows for the removal of individual tubes for cleaning or maintenance – but increase its strength and durability.

As well as expanding the motor size from 4 kW to 7.5 kW, and bolstering the gearbox size accordingly, the overall heat exchanger was also reinforced. The scraping rod was made bigger and stronger, with heavy duty bearings and lips seals to accommodate increased torque. Further along the tube, an extra support for the scrapers was added to cope with the weight and increased forces. Finally, an extra external support was added to the motor end of each RHD unit to cope with the extra weight.

Matt continues: “The standard R Series of rotating scraped surface heat exchangers from HRS Heat Exchangers have been proven time and time again in both food and hygienic applications for their ability to reliably process viscous products such as sauces, purées, creams and gels. With the addition of the new HRS RHD Series, we can now deliver these benefits to the thickest and most difficult to handle materials, such as nut butters or any semi-solid product.”

The post Heavy duty heat exchanger tackles nut butter challenge appeared first on HRS Heat Exchangers on 7 August 2018.

Unique R Series scraped surface heat exchanger solves viscous product challenges

Different materials need different types of heat exchanger. For the simplest fluids such as water and milk, plate heat exchangers are often sufficient, but as products become more challenging (for example more viscous, or containing particles), then different types of tubular and scraped surface heat exchangers are required. For those products with extremely high fouling potential, or those which benefit from constant agitation (for example to keep solid particles in suspension), then the HRS R Series of rotating scraped surface heat exchangers is ideal.

Designed for both sanitary and industrial applications, the R Series from HRS Heat Exchangers uses a rotary scraper rod which is capable of reaching velocities of 300 rpm, providing high levels of shear and mixing at the heat transfer surface which dramatically increases heat transfer rates. This makes it particularly suitable for challenging heat transfer applications, such as those where the product has the potential to crystallise during processing or where aeration is required.

The scraper rod features both a helical mixing spiral (which reduces the pressure drop in the tube) and a series of scraper blades. Together these provide a continuous scraping action which mixes highly viscous products and reduces fouling. The unique design enables high viscosity products to be pumped with reduced back pressure and lower energy use, in a compact unit which features a much smaller footprint than traditional heat exchangers for similar applications.

A unique gearbox design not only reduces noise, but also allows multiple tubes to be fitted inside a single shell from a single electrical drive, further increasing the available heat transfer area within the same shell footprint and aiding maintenance. Cleaning and maintenance is further improved by the unique sealing system used in the R Series which allows individual tubes to be removed for easy servicing and replacement if necessary.

Thanks to its helical spiral, in many applications the R Series can also be run in reverse, enabling much valuable product to be recovered before routine cleaning or product change-over without the need for additional pigging or flushing systems. Not only does this reduce costs and complexity, but saving product adds dollars to the bottom line.

HRS International Sales & Marketing Director Matt Hale comments: “Normally, when processing viscous or sticky products such as honey, syrups and purées, a certain amount will adhere to surfaces. This greatly reduces heat transfer, meaning that longer exposure is required to compensate. With its clever scraper design the R Series overcomes this problem, and also reduces product  losses which can soon add up. For example, product lost during processing is estimated to account for 3% of total losses in the US dairy industry. The R Series can be emptied of the majority of the product without the need for any additional pumps or pressure systems, reducing both capital- and running-costs.

The HRS R Series is available in two lengths (1 and 2 meters) and with one-, three- or six-tube options providing a range of surface areas between 0.35 and 4.2 m2. For larger installations multiple units can be combined in series and units can be mounted horizontally or vertically and internal baffles can be specified within the tubes to overcome situations where shell-side flow may be limited. This also means that it is possible to obtain complete counter-current flow between the shell-side and tube-side fluids for multi-pass designs. In other situations, such as condensing (e.g. stem heating) and evaporating (e.g. ammonia cooling) the baffles are not used, in order to improve performance.

The R Series is suitable for a range of uses in the food processing and cosmetic industries, including heating, cooling, pasteurisation, crystallisation and evaporation.

For some materials, such as curd production in the dairy sector and many concentrated products and creams, increased turbulence is beneficial,” adds Matt. “With its small footprint, ease of maintenance and the ability to recover product, in these situations the unique design of the HRS R Series offers a number of advantages over other heat exchangers on the market.

The post Unique R Series scraped surface heat exchanger solves viscous product challenges appeared first on HRS Heat Exchangers on 19 June 2018.

Effectively recovering product from pasteurisers and sterilisers

A key challenge in the food industry is recovering valuable product which is left in equipment and pipework after production runs, for example between product change-overs and before cleaning. Product lost in this way increases operating costs unnecessarily and affects beverage manufactures to sauce producers, fruit and vegetable purées, and many other products.

Companies often use ‘pigging’ systems to remove such retained product, particularly in the last portions of their production process. Some of these systems are very simple, while others can be very complex. The pigging device physically recovers material from the system and is often an integral part of CIP (Cleaning in Place) cycles. Other alternatives are to use water or clean air to ‘push’ the product through the system until such time as the product is either too diluted or the product seal in the pipework is broken.

All three of these approaches will salvage some residual product, but a certain amount of usable product will inevitably be lost as waste. However, by using inline measurement and automatic control, you can guarantee that the maximum amount of product possible is recovered from pasteurisers and sterilisers in the production line.

Re-using an established concept

The concept of a feedback loop to continually measure and control a process is well established in automated food production. For example, every HRS pasteuriser or steriliser has a temperature transmitter and a three-way valve installed after the holding tube. If, for any reason, the set pasteurisation or sterilisation temperature is not maintained in the holding tube, the temperature transmitter sends a signal to the valve to return the product back to the holding tank.

This prevents any product that may not have been adequately pasteurised or sterilised entering the food chain and allows products to be recovered and reworked if appropriate. The same principle can be applied to universal product recovery, measuring different parameters.

Some practical examples

If we imaging a fruit juice production line, an inline Brix meter positioned after the pasteuriser can monitor the sugar concentration against a target level of 12 oBx (the set point). When the concentration falls below the set point, a controller diverts the remaining product away from the filler.

Such an approach overcomes any doubts about where the ‘mixing zone’ may begin when water is used to push product through the system as it can be accurately measured in situ. In addition to maximising product recovery, the waste being produced will be cleaner (as there is less product in it), potentially reducing disposal or treatment costs.

In the previous example we have used an inline Brix meter to measure sugar concentration, but it is possible to use a suitable device to measure any physical property (pH, viscosity, density) depending on the best criteria for the product.

For example, a US manufacturer of BBQ sauces makes a profit of $2 on every gallon of sauce produced. If the company loses 100 gallons of sauce per day, profits decrease by $200 per day. Based on 300 days of production a year, this equals $60,000 dollars a year. If this was repeated across four production lines the company could be losing almost a quarter million dollars ($240,000), not to mention the costs of treating and disposing of the wasted product. Even a 50% reduction on waste across all lines would save $120,000 a year, covering the costs for the installation of a system.

Using the system in practice

These examples have focused on the end-of-run condition for processing. However, this system also helps reduce product loss on start-up. For example, if a production line is ‘warmed up’ with water, the water is typically ‘pushed’ out by the product until a certain condition is reached. This system accurately establishes when that point occurs, eliminating the guesswork and automatically saving even more usable product each run.

This type of system can be installed with any existing system (pasteuriser, steriliser, hot filling) with very little downtime. Real world payback times will depend on the quality of the instrument used and the value of the product, but average payback periods are between 1 and 6 months. In addition to improving bottom line profits, there are also environmental benefits. Recovering more product saves on energy required to process waste streams, reducing waste and lowering the carbon footprint.

HRS Heat Exchangers have successfully installed several of these systems in plants around the world, helping clients choose the right instrumentation and the correct software for the system. If you have a project that involves product recovery or you are interested in learning more, please contact us.

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Reduce digestate volumes with HRS

At UK AD & World Biogas Expo 2018 stand D603, HRS Heat Exchangers will showcase its novel Digestate Concentration System (DCS), which increases the dry solid content of digestate three-or four-fold, typically to between 10-20 per cent.

By reducing the liquid fraction and therefore the overall volume of digestate produced, the DCS minimises the economic and logistical challenges associated with digestate storage, transportation and application. Up to 60 per cent less storage capacity is needed and fewer tanker loads are required, helping to curb an AD plant’s transportation costs and carbon footprint. And with an average 1.5 MW AD plant generating 40,000 tonnes of liquid digestate each year, that can mean significant carbon and financial savings.

By reusing heat from existing sources, such as the CHP engine, the DCS is virtually energy self-sufficient. Water removed by the process is recovered and can be mixed with AD feedstock at the front-end of the plant, increasing the efficiency of the digester. The DCS also overcomes odour issues and increases the nutrient content of digestate via acid-dosing with sulphuric acid – while the volume of digestate is reduced, the nutrient content actually increases.

The HRS DCS is a plug-and-play, fully automated system which is completely flexible and can be tailored to meet the requirements of individual AD plants. The technology is installed at a number of facilities worldwide and is helping operators to reduce their storage, transport and application costs, as well as their water usage, while using spare heat which would otherwise be wasted.

International Sales & Marketing Director Matt Hale explains why increasing numbers of AD operators are specifying the Digestate Concentration System for their sites: “At a time when the efficiency of AD plants and bio-waste management is under scrutiny around the world, being able to maximise the financial and nutrient value of your digestate, while at the same time reducing storage, transport and application costs, is an exciting proposition. The HRS DCS represents the most efficient method of achieving these goals.”

Learn more about how the HRS Digestate Concentration System (DCS) can solve your digestate challenges and improve your overall plant efficiency on Stand D603 at the UK AD & World Biogas Expo, NEC Birmingham, in July.

The post Reduce digestate volumes with HRS appeared first on HRS Heat Exchangers on 6 June 2018.

Unique heat exchanger increases resource efficiency by cutting process waste

With resource efficiency topping the agenda at this year’s Anuga FoodTec show, HRS Heat Exchangers is shining a light on a forgotten area of wastage in food processing – food lost during cleaning cycles and production changes. The HRS R Series of scraped surface heat exchangers removes food residue, meaning that food factories can now recover valuable product from the exchanger when heating, cooling or pasteurising viscous/sticky foods.

HRS International Sales & Marketing Director Matt Hale explains: “Normally, when processing viscous food products such as honey, syrups and purées, a certain amount will adhere to surfaces, such as the inside of pipe work, or become left in equipment after processing. The value of these lost products soon adds up. For example, this issue is estimated to account for 3% of product losses in the US dairy industry1.”

Globally some 5% of food loses occur during processing, although this varies according to region. In European countries the average figure is around 5% but this rises to 9% in North America2. To put this into context, that’s 4.1 million tonnes of food being lost during processing each year in the UK alone3. The sectors with the highest waste levels are dairy, animal and meat processing, fruit and vegetable processing and the manufacture of oils and fats4.

Traditionally flushing or so-called ‘pigging systems’ have been used to push product through key parts of the production system, like heat exchangers. However, both add complexity to the system and can result in high levels of product wastage. However, running a suitable scraped-surface heat exchanger, such as the HRS R Series, in reverse, enables the recovery of material without the need for such additional equipment.

The HRS R Series scraped surface heat exchanger is capable of removing much of the product before the cleaning or change-over cycle commences. This is made possible thanks to a scraper bar within each inner tube which enhances product flow; prevents fouling during operation and minimises the pressure drop. The scraper bar features a helical screw which rotates at high speed. When configured correctly, this screw can be run in reverse, removing product from the heat exchanger tubes without damaging it or changing its characteristics. The R-Series can be configured for both horizontal and vertical operation, so that gravity can also be used to help recover product from the tubes. Each unit can be supplied with one, three or six tubes and multiple units can be combined for larger installations.

“The R Series is particularly suitable for high value viscous products such as honey, treacle, custards and creams, where lost product can be expensive,” adds Matt. “The R Series can be emptied of the majority of the product without the need for any additional pumps or pressure systems, reducing both capital- and running-costs.”

Learn about the benefits of the HRS R Series on Stand D069 in Hall 10.2.

Originally posted at PandCT.com on 5 February 2018.

The benefits of on-site heat and power generation for food companies

Sustainability has never been higher on the agenda for food and drink companies than it is now. Not only does operating in an ethical and environmentally responsible way make sense for both planet and pocket, but it’s clear that this is what consumers want, too. Research from Globescan revealed that 92 per cent of shoppers think food companies should focus their efforts on securing the future sustainability of food, with two-thirds also believing that farmers should be paid more for their produce. So, what more could the UK’s food producers be doing to increase their sustainability credentials?

Making the most of waste

In recent years, some of the country’s most forward thinking food companies have developed a truly circular approach to resource use. Alongside minimising the volume of waste they generate, they are also turning the unavoidable fraction that does occur into renewable energy, for use in their on-site operations. Anaerobic digestion (or AD) – in which organic matter is naturally broken down to produce energy and biofertiliser – has taken big strides in the UK over the past seven years, with over 540 AD plants now in operation.

While the vast majority of the country’s AD facilities treat sewage sludge, agricultural feedstocks or commercial/municipal food waste, almost 40 facilities are on-site industrial plants. Together, these generate over 50 MWe-e from a variety of process residues, ranging from vegetable peelings and sugar beet pulp to liquid malt waste and whisky draff. The benefits for the companies operating these plants are multiple – reduced waste disposal costs; reduced energy costs; security of energy supply, with reduced reliance on fossil-fuel derived power; carbon mitigation; superior green credentials; and creation of a nutrient-rich biofertiliser. And the fact that these plants have an on-site use for the power they produce means they are exempt from the current crisis in renewable energy incentives which is affecting plants that export power to the grid.

Take the heat

However, any AD facility that wants to maximise its returns also needs to be making use of its full heat output, not just its power output. The AD process generates plenty of surplus heat – most commonly, heat produced by biogas combustion in a combined heat and power (CHP) unit, but also via digestate pre-heating, pasteurisation, biogas upgrading to biomethane and digestate concentration. Ensuring this heat is used either within the AD process itself or within other on-site operations can make a big difference to a plant’s efficiency and therefore profitability.

By using heat exchangers within an AD plant, surplus heat can be taken from one process or place and transferred to another. Common everyday examples include domestic radiators (which transfer heat from a boiler to a room) and car radiators (which take heat away from the engine). Two of the most common types supplied to AD plants by HRS Heat Exchangers are Plate Heat Exchangers and Tubular Heat Exchangers. However, there are many different models and refinements and it is advisable to consult a specialist who can explain the benefits of different types and perhaps offer different solutions.

Potential uses for heat in the AD process

When it comes to making full use of the heat, there are a number of options with the AD process itself, including: preheating feedstock; for pasteurising; to reduce the volume of digestate; or to upgrade biogas to biomethane. For on-site plants within the food industry, it can also be used for space heating, cooking, heating liquids, or pasteurising and sterilising foodstuffs. In addition, large sites may have significant office and staff facilities, where there may be the scope to install district heating systems.

As the demand on resources increases, there will be a greater need for food companies to demonstrate sustainability across all areas of their business. On-site AD, where full use is made of both the heat and power generated by waste materials, offers an obvious solution.

This post first appeared on PandCT.com.

HRS pasteurisation system helps Shanks achieve PAS 110 certification

Pasteurisation technology supplied by HRS Heat Exchangers has helped international waste-to-product business Shanks Group plc, gain PAS 110 certification for its Westcott Park anaerobic digestion (AD) facility in Buckinghamshire.

Publicly Available Specification 110 (‘PAS 110’) is a demanding industry specification which verifies the quality of digestate (the organic biofertiliser output from the AD process) and covers the product quality, standards for input materials and the management system for the AD process.

This important development, which was achieved in April this year,means that the digestate produced by Westcott Park is of a consistent high quality which can be sold and applied as an agricultural fertiliser.The facility also received a Certificate of Compliance by Organic Farmers & Growers Ltd, meaning that the digestate can be used by both conventional and organic farmers to provide nutrients and valuable organic matter to their crops.

The Westcott Park facility has the capacity to process 48,000 tonnes of food waste, from sources including the retail and catering sectors, each year and supplies the National Grid with enough electricity to power 6,000 homes.

As well as setting limits for physical contaminants, such as plastics, the PAS 110 standard requires pasteurisation of the material before or after it is digested at the AD facility. HRS designed and supplied a HRS 3 Tank Batch Sludge Pasteuriser System to pre-pasteurise the food waste feedstock before it is fed into one of the three digester tanks.

The system makes use of heat from the facility’s existing combined heat and power engine which would otherwise be wasted, helping to maximise the overall efficiency of the site. It also recovers heat from the hot feedstock which has been pasteurised and uses it to pre-warm the feedstock as it enters the pasteuriser system. This provides energy savings of up to 70 per cent.

Ray Nattrass, Head of Process Design & Engineering at Shanks Waste Management, said: We chose the HRS system because they offered a complete pasteurisation solution -we wanted the tanks, pumps, control system, control logic and everything built into that.

HRS demonstrated that they had the ability to design the facility as a standalone solution. It was their ability to do that which was key for us.”

Peter Eglinton, Managing Director of Shanks’ Municipal Division, commented:

“I am delighted that our Westcott Park AD facility has achieved this quality standard for our digestate product.By achieving PAS 110, we can assure our customers that our nutrient-rich digestate is recognised as best-in-class.By deploying the digestate back to land we are making more from waste and enhancing our position in the market as a leading waste-to-product company.”

Matt Hale, International Sales Manager for HRS, added:

“We are delighted to have helped Shanks achieve this important milestone in the commissioning and development of their AD facility at Westcott Park. Our 3 Tank Batch Sludge Pasteuriser System ensured that the facility complied with the requirements for treating Animal By-Products when it was fully commissioned last year. Now it has been an integral part of achieving PAS110 certification.

This article was first posted on the HRS Website in August 2015.