Before proceeding with the installation of an industrial biomass boiler, there are several key factors to consider. Among these, your specific energy requirements take centre stage. By conducting a comprehensive assessment of your energy needs, you can have confidence that the cost of a biomass boiler installation will prove to be a worthwhile investment, delivering both economic benefits and sustainable energy solutions.
Naturally, customers vary in terms of their energy requirements. For example, a school will have a seasonal high demand with times of no demand, while a hospital will have a seasonal peak of demand but a year-round base load. Similarly, factories will usually have a consistent year-round need for energy to run their core industrial processes. However, they will experience higher energy demands in the winter to heat the work environment.
Scale can also affect the installation costs and the economics of a biomass boiler installation. Generally, the larger the biomass boiler, the better economies of scale. This is because while some miniaturisation of biomass boilers can happen, this is the point where the cost of the control system and combustion chamber cannot be scaled down. In addition, if you are having fuel delivered, you will require a storage capacity of 100m3 to ensure optimum efficiency. For many smaller and medium installations, this is not cost-effective or space-efficient.
This cost-saving benefit due to scale remains effective until the local biomass supply chain is depleted, after which you may incur higher expenses to transport the fuel over longer distances.
When it comes to size, it is advisable to opt for a biomass boiler with a power capacity that matches the expected heat loads. What does this mean? Well, if you have a kiln that requires 1MW of thermal energy, you should purchase a 1.1MW boiler. This is because of the turn-down ratio or the lowest power setting a boiler can run at.
A gas boiler may have a low power burn setting of 10:1, so it can operate at 10% of maximum power. Biomass boilers have a slower response time because it takes more time to load fuel into the fire chamber and for evaporation, pyrolysis and combustion to occur and generate heat.
Control systems with better fire chambers excel at maintaining consistent thermal energy production in response to fluctuations. In contrast, some cheap biomass boilers rely solely on hysteresis-based control systems, causing the feed to cycle on and off without modulation. Ranheat boilers are better equipped for this specific task as they can continuously adjust their speed to seamlessly manage fluctuations in thermal energy demand, resulting in improved control and enhanced efficiency.
In certain biomass boiler installations, buffer tanks are incorporated to compensate for the limited control in the combustion system. However, this approach does come with a significant trade-off, leading to a notable decrease in both efficiency and cost-effectiveness.
For users with variable heat loads, using multiple boilers may offer the highest level of performance and efficiency, all while ensuring duty and standby protection. In instances where there is a winter heating demand alongside a consistent need for domestic hot water, this combination could present the ideal solution.
For individuals overseeing industrial processes, the necessary temperature level plays a significant role in the choice of biomass boiler installation. For example, a low temperature hot water (LTHW) pressure vessel is unsuitable when an industrial process demands steam or high temperatures.
The exact definition of LTHW can vary slightly depending on industry standards. In European standards, it is typically defined as water with temperatures below 110°C and pressures up to 3 bar. However, according to ASME H standards, this threshold extends to around 122°C, often serving as the boundary between LTHW and medium temperature hot water (MTHW) and high temperature hot water (HTHW).
LTHW is the preferred choice for most heating systems due to its cost-effectiveness in terms of delivering thermal energy for heating buildings and low-temperature applications. Operating at higher temperatures results in additional expenses, including increased pressure requirements for biomass boilers and heating circulation equipment. Therefore, LTHW is typically the favoured option unless higher temperatures are specifically required.
The exception to this rule is larger-scale heating applications where there is a substantial simultaneous demand for electricity. In such cases, Combined Heat and Power (CHP) units can offer notable advantages, albeit at the expense of significantly higher initial capital costs for the entire system.
Typically, steam and HTHW are primarily utilised for industrial processes, such as those in the chemical or food production industries, or for integration with existing industrial equipment. There must be a reason to make the “juice worth the squeeze” for using HTHW, as the benefits must outweigh the associated complexities and the cost of biomass boiler installation.
With other fuels, thermal oil is used to obtain higher temperatures without the pressure. Thermal oil has certain issues when used in biomass combustion chambers as they cannot be turned off in an instant as they require a fire bed to produce the gases to combust. This means in a situation where there is a leak in the thermal oil pressure vessel, the thermal oil can add fuel to the fire. As a result, it is incompatible with biomass boilers.
All this talk about biomass boilers has ignored another option: warm air heaters. These appliances are useful for sizes from 35kW to 1MW, and the Ranheat WA range provides the best-in-class warm air heaters. Warm air heaters operate on a similar conveying and combustion system as other heating methods, with the key distinction being that they heat the air directly instead of using water in a boiler.
If a biomass system is used to provide warmth for an open factory or warehouse area, warm air heaters frequently emerge as the most cost-effective solution. This is because the ducting and dampers required to distribute the hot air are cheaper than installing pipework and heaters. However, you need to give up the same degree of control as you have with an LTHW system. Warm air systems can be used for industrial processes but not with the same level of control associated with hot water and steam.
The way in which you deliver the energy generated from biomass boilers can vary hugely. The specifics of how biomass boilers work mean that “standard” mechanical designs appropriate for fossil fuel-fired boilers will not be ideal for a biomass system.
At Ranheat Engineering Ltd., we have been manufacturing industrial biomass boilers in the UK since 1991 and we can offer a range of biomass boilers and warm air heaters from 75kW to 4MW. For more information or for some expert advice, please contact a member of our team.
MATT LOCAL
