2734 Serenade Drive
Las Vegas, NV 89100
Memorandum 2
This is a business memorandum in response to your memorandum regarding the selection of a proper boiler for our Salt City property. I am very glad that your proposal to upgrade the heating system has been approved, as it is in dire need for a superior boiler. The current heating solutions installed at Salt City make us of water boilers, which use obsolete technology. This is the reason of frequent customer complaints and inefficient heating at lower temperatures. As I have mentioned in my previous memo, we can make use of the water tube heating or the fire tube heating boilers for the replacement at our 800 beds, 5-story property. In this memo, I have tried to choose the best boiler solution according to our requirements.
There are various types of Boilers available in the market. These come in different shapes, sizes and types and can be classified by firesides, furnaces, and the watertubes or the volume of water they can hold. However, there are two main types of boilers. These are fire-tube boilers and water-tube boilers. A lot of factors need to be considered in order to decide which boiler will suit our needs the best and work out most efficiently to us in the long run. For this purpose it is important to understand the workings, strengths, weaknesses and differences between the two boilers. In Firetube oilers, the flue gases pass through the horizontal or vertical steel tubes. These steel tubes are surrounded by water to be heated. The flue gases change direction up to four times in order to provide maximum heating to the water around them. In the Watertube boilers, the water circulates inside the tubes. The combustion gases flow outside these tubes and work to heat up the water inside the tubes. The watertube boilers have a furnace in which fuel is burned. This fuel is used to heat up the water in the steam-generating tubes. After been heated to a high-temperature, the water rises up to a steam drum. Saturated steam is pulled from top of this steam drum.
The intrinsic design of watertube boilers makes them safer for use and last much longer than the firetubes. Watertube boilers can handle high pressures up to 5000 psig and recover faster. If used in conjunction with superheaters, watertube boilers can reach very high temperatures. In comparison, firetube boilers are not safe for use over pressures of 350 psig. They provide considerable lower steam output. Due to their design, firetube boilers have lower manufacturing costs. The firetubes used in these boilers are easy to replace and the firesides can be easily cleaned.
Another major point of difference between the two boilers is the water volume difference that exists. Water tube boilers have lesser water volume and hence, are able to follow load swings very precisely and provide much better turndown. Since firetube boilers have much more water volume it takes a longer time for elevated operating temperatures to be reached, which are needed to heat up the water. One of the advantages that the firetube boilers offer, if the huge steam disengaging area, Due to this area, an abrupt load surge can be handled much more efficiently. On the flipside, once the pressure on the firetubes is dropped, it takes much longer for the boiler to bounce back. The general rule followed in the industry is to use watertube boilers when varying load is expected. Wherever there is steady of fixed load required, firetube boilers are recommended.
Since we have a 4-pipe system available at our Salt City property, we can provide heating and cooling solutions all through seasons. Though, the initial setup and manufacturing costs of watertube boilers is high, it is my opinion that the watertube boiler would fit best in our design. There are various reasons for this. First, a major advantage of watertube boiler would be that is takes away the chance of any catastrophic failure occurring. The volume of water in the boiler is not large and there are fewer mechanical elements, which can lead, are subject to failure. These boilers provide rapid warming since these have a large heating surface per every pound of water. Small watertube boilers are available which are sized below 10MMBtu/hr. These are usually gas and oil-fired boilers.
In case a superheater needs to be installed, a watertube boiler makes this installation much simpler. With watertube boilers, we can afford maximum allowable pressure without the danger of any ill happening. These boilers are also much more environment friendly due to smaller footprint. There is a higher efficiency due to a high water volume being exposed to the heating tubes. Even if there be a rupture, it would be into the furnace area, thus maintaining the safety of people and premise. It would work well with our 4-pipe system due to the quick load change response. This faster response is possible due to less water volume. We can use some accessories with the water tube boilers in order to increase the efficiency. One of the most important of these accessories is the superheater. These superheaters works to improve the efficiency of the boiler. The superheater material should be elevated temperature and corrosion resistance.
There are lots of advantages that the current technology for the watertube boilers offers us. As mentioned above using preheaters or economizers along with the boiler will guarantee better efficiency for us. In case of fuel-fired heating devices, taking the waste heat and utilizing a part of it in the flue gas can raise the efficiency considerably. One of the most commonly used techniques for this purpose is the preheating of the combustion air and water heating. Heat is transferred from the flue gases to the incoming air by air-heaters. Two types of air-heaters are regenerators and recuperators. Recuperators have gas-to-gas heat exchanging devices that are mostly placed on the boiler stacks. There are internal tubes that transfer heat from flue gases and provide the same to the incoming combustion gases. An economizer is used to capture any waste or lost heat energy. Using this otherwise wasted heat energy will lead to overall fuel needs of our boiler. The reduced fuel intake will reduce costs and lower the number of emissions. Hence the use of an economizer will automatically lead to higher efficiency.
Another technology that we can employ is the used of superior soot blowing facilities. These are called Intelligent Sootblowing systems (ISS). The ISS make use of feedback messages like exit gas temperatures, heat transfer sensor devices, etc. The determination that which soot blower needs to be used when is made by the ISS. This automatically results in better operations and efficiency.
There are various steps that can be taken in order to further improve are HVAC systems and functionalities in order for much lower costs, smaller footprints and better guest comfort. We must devise a plan that will help us make better energy efficient choices. We need to have frequent and strict energy audits to understand and calculate our current and future energy requirements. This can be done based on what our current usage is and what improvement options are available to us. Having this data with us will help us identify the area in which we can make considerable changes and the areas where we can continue as is. Once this current data is in our hands, we need to formulate SMART goals for energy conservation.
It is imperative to form an energy conservation and monitoring team. The responsibility of this team would be to oversee our goals and energy patterns. We also need to factor in contingencies. This will ensure that our efforts for energy conservation in our HVAC system are not interfering with any other systems negatively. Once our plan is finalized, we need to recognize action steps for implementation of our plan and evaluation of the results. It is important to identify the stakeholders and key personnel for this implementation and evaluation. Roles need to be sharply defined and consequences set if we fall short of achieving our goals.
There are a lot of possibilities of energy conservation and cost reduction in the HVAC system. It is imperative to ensure that the HVAC settings in the offices, lobbies and other peripheral rooms must be set to their minimum settings especially during hours of reduced usage. These areas are not a top priority as far as guests are concerned and using maximum settings in these areas all through the day leads to exponential increase in our expenses. The guests do not spend a lot of time in these areas and energy conserved here can be used in comfortable arrangements in the guest rooms. We can also use fan coil units in places where comfortable temperature is not a major need. This will help us reduce our costs and also reduce energy wastage. Another way to improve our HVAS systems is my setting hot water for laundry at a temperature of 120 degree Fahrenheit. This is the optimum temperature for all areas outside the kitchen wherever hot water is needed.
As mentioned in your memo to me, we are facing lot of complaints from the guests regarding uncomfortable temperatures in the guest rooms. In the long run we can shift to centralized cooling and heating solutions over individual units. Though the initial costs of centrally controlled systems are twice of that of the individual units, these central systems save a lot of energy in the long-term usage. These not only increase the efficiency tremendously, but also are in the control of our facility operators. It will become much more easier to observe, implement and control energy usage if we switch to central systems. These are some of the practices being used by several hotels, which have become front-runners in sustainability and high-comfort hotels. Sustainability has become a very important criterion with the deteriorating health of the planet. Implementing these practices will very positively impact our image and patronage.
References:
"Reduce Energy Costs While Increasing Environmental Sustainability, by Rowan Sanders." HotelExecutivecom Daily Headlines. Web. 16 Nov. 2014. <http://hotelexecutive.com/business_review/3092/reduce-energy-costs-while-increasing-environmental-sustainability>.
Web. 16 Nov. 2014. <http://docs.caba.org/documents/IS/IS-2013-84.pdf>.
"Economizers For Boilers." Economizers for Boilers. Web. 16 Nov. 2014. <http://www.economizersforboilers.com>.
Web. 16 Nov. 2014. <http://www.epa.gov/nsr/ghgdocs/iciboilers.pdf>.
"Firetube or Watertube? What's the Difference?" Firetube Boiler. Web. 16 Nov. 2014. <http://www.mckenziecorp.com/boiler_tip_8.htm>.
"Re: Fire Tube vs Water Tube." Re: Fire Tube vs Water Tube. Web. 16 Nov. 2014. <http://www.steamforum.com/steamforum_display.asp?post=1943>.
