The Confounding Science of Selecting a Still
In the last 24 months or so, while my income from copper stills has plumetted, I have been helping distillers become compliant with Hazardous Areas. What I have discovered is that most people are now buying Chinese stills. To be perfectly honest, this is not a bad decision. I should not say that because the Chinese fabricators are my competition, but if I were in another pair of shoes, I would probably do the same. However, there are a number of potential pitfalls that most people don’t know aboutwhen selecting a still and one of my objectives at HHH is make sure that our industry builds for the better and not for the worse. By Better I mean we achive compliance, efficiency and production convenience all at the same time. So, here are some tips (and if you need help, my email is at the end):
- The size of your still needs to match your business model. Some distillers love distilling and are happy to distil 3 times a week; some want to distil no more than 6 times a year. This will feed into the size of your still. Making gin and vodka using purchased neutral alcohol requires a much smaller still than making whisky, rum or brandy from scratch. I always ask a customer for the target number of bottles per year, the type of product and the number of times per month they are prepared to distil, and from this I calculate the size of still required. Getting a bigger still just in case doesn’t really help most of the time as there are other logistical issues that are affected by a bigger still. A right sized still is always a better option; think of buying a huge 4×4 to go camping once a year while every day you drive to the city for work and park in a high rise parking lot.
- The process you want to use for your product makes a difference. Are you making vapour infused gin pot distilled? Or vapour infused on reflux? Is the reflux before or after the botanicals? Or macerated in a pot still or a reflux still? Or the ability to do all of the above? Or whisky pot distilled with one still, or two stills? Whisky through plates? There are a lot of options and it is much better to know exactly what you want to do and why. I can assure you that buying a still that everything to every person is NOT a good way to start as it wastes precious financial resources at the expense of an efficient, productive distillery.
- How is the still heated? There are four main methods: direct immersion heating (most common for smaller stills under 500L), oil heated jacket, water heated jacket and steam heated jacket. The most expensive of all of these is the steam heated jacket and if you go that route you are probably a big distillery with a lot of money and will have a fancy consultant. Direct immersion heating works well but it needs attention to the product you are making. For gin and vodka the power density of the elements is not critical but probably best to keep it below 10W/cm2. For water heated jacket the power density is not an issue, but the jacket becomes a pressurised vessel and needs to be assessed under AS4343 to see what its class is and whether the designs needs to be registered, or the design and the still need regiatration. All of this needs to be known BEFORE fabrication to ensure that all the calculations are done, the wall thicknesses are approved and the necessary NDT is completed during fabrication. You don’t want to be caught out by an inspector and find that you can’t use your still. For an oil heated jacket there is no problem with pressure because there is no pressure, but power density is critical as oil will burn onto the element. What I have found is that most Chinese stills have a heating box at the base of the jacket where the elements are connected, and the box is often about 300mm long. When the power density calculations are done they will show that box should be up to 1000mm long.
- For heating jackets you will need a mixer to improve the efficiency of thermal transfer, and there are two types: electricaly or pneumatically driven. Most stills have an electric mixer and this will need an IEC Ex certified motor. You only need one speed so don’t go for a VFD driven motor. It is not allowed under the IEC Ex certification, at least I should say that 99.5% of IEC Ex motors out there specifically exclude the use of VFD because it can cause additional heat in the motor.
- For all heating done by elements, the elements must be Explosion proof and IEC Ex certified. This is something you can’t get away from; I have tried to find ways to ventilate to the point that the ethanol concentration is less than 1.5% and it is impossible without a fan the size of a jet engine. While we are on this point, all electrical equipment attached to the still must be IEC Ex certified for Zone 1 and this includes temperature probes like PT100s or any thermocouple. Stills with direct imersion elements need to have a level switch as well to avoid the accident like the one in Victoria are few years ago (it is also a requirement of AS60079.14).
- Most heating elements are made to connect to a 2″ tri-clamp ferrule. This great because it standardises the connection and reduces the cost. The tricky part is that Explosion proof elements have a diameter of 47mm and some 2″ ferrules have an internal diameter less than that. I advise all of you to make sure that your ferrules are checked before having them welded, especially where the still has insulation around it as the job to retrofit a new ferrule is massive in those circumstances (and expensive).
- If you are making gin and you have a basket for the botanicals, please calculate the size of the basket. You do not want to be stopping the distillation halfway through to change botanicals – it is dangerous in the first instance and inconvenient in the second. It will also change the hazardous area assessment of your zone to Zone 0 and your explosion proof equipment will explode in price. Here is a useful metric: 1kg juniper takes up about 2.7L. If you double the volume of your juniper you will probably have enough space for the other botanicals.
- The location of the botanical basket is important for operations. I recently looked a still design for someone and they had a carter head 3.5m high. Apart from being inconvenient and difficult to fill, there are HSE issues working at heights with all sorts of time consuming procedures.
- The location of the parrot, if you actually use the information from the alcometer bobbing inside it, is also important. You want it to be at a height where you can easily read it. It seems obvious, but I recently saw a design where the parrot was about 2.5m high and even Luc Longly would need a ladder to read the alcometer. There are easy and inexpensive solutions to this problem.
If you need help please get in touch at hilton@www.hhhdistill.com. I will provide you with a consulting service that will save you $1000s. But if you can do some maths, you can probably figure out all you need from this blog.
