High Pressure Tanks
High Pressure Tanks
The prince said to his City Hall Director Barov explicitly, "Now you see, both labs and Graycastle's factories need hands, and so do I. I plan to manufacture soaps and perfume on a large scale, but I have to wait until another batch of students, and at most 600 to 700 of them, will graduate in the following year to be recruited as the workers I need. It's obvious that even at that time, the graduates won't be able to meet the manpower demand. Given that, I need larger population."
"What about recruiting more workers from the stronghold..."
"No," Roland interrupted. "I'll establish a city next year and by then the stronghold will become part of it. Recruiting people from there is like moving the money in one of your pockets to another. It's pointless. I need to recruit more people from outside the Western Region."
"It's..." Barov seemed a little baffled. "I'm afraid it's not an easy task, as the local lords won't neglect it when we're recruiting their people in their cities."
"No, we don't recruit from cities." Roland dipped his finger into his cup and started to draw with the ice water on the table. "Have you noticed that since the end of Months of Demons, Graycastle has been a theatre of war. Timothy has launched several rounds of attack on the Southern Territory. He burned down Eagle City and made its surrounding villages and towns suffer a lot. After that, he charged treason against Duke Ise and waged war in the north to deprive the duke of his title and domain. In the end, it's the attack from the sea in the east." Roland drummed the desk several times, leaving some water stains. "All big cities there such as Seawindshire, Valencia and Crow Castle were affected, let alone the small towns around them. Based on the number of refugees in the king's city from this area, it's plain to see that those places must have suffered a heavy loss."
"You mean..." Barov revealed a thoughtful look.
"Let your men advertise the Western Region." The prince wiped out the water stains. "Over the recent six months, only the Western Region has been peaceful, without any war or compulsory recruitment. Timothy used lots of drugged men in wars. He must have recruited or even grabbed lots of civilians for military service. No one can be sure that such a thing will never happen to himself. Given that, we should focus on emphasizing the peaceful and stable situation of the Western Region in our propaganda campaign."
"I see, you plan to attract people in the other towns and villages through promoting the safe and peaceful life here and through promising them that you'll provide them houses, food and jobs, right?" Barov said after a thought.
"Almost." Roland smiled and nodded with satisfaction to Barov who had been quick in mind and ready to embrace new things all along. "Besides, you need to highlight the excellent payments and conditions we offer to the literate people. I believe these will attract some broke knights and nobles in those places to seek opportunities in our Western Region."
Most villages and towns were lesser nobles' domains. No matter how barren the lands were or how badly they managed their domains, during peacetime, it was easy for them to have enough to live on. However, it would be difficult for them to get through the wartime when the population fell. Roland was confident that if he offered those troubled lesser nobles good opportunities at such a time, most of them would like to come to his Western Region. As for their own domains, even without any management, the lands would stay there anyway. After the hard time, they could go back with money and mercenary fighters to restart their lives on their domains if they wanted to.
Now the only problem was how to advertise the Western Region. Roland decided to leave it to Barov.
"But, Your Highness, we'll spend lots of money to attract those people and to help them settle down here, and we need to continue the grain purchase at the same time. If our arrangement with Margaret has some unexpected changes, the government's coffers will be almost empty," Barov hesitated and said.
"Uhm... I see your point." Roland touched his chin, thinking that as a new leader, he should give top priority to building his prestige and authority among the people and avoid things that would destroy his image, such as breaking his payment promises. "Well, you go back and draft a plan first. Let's start the propaganda campaign after we make enough money from the deal with the caravan in the next month."
"Yes, Your Highness," Barov said, with a hand on his chest.
After the talk with Barov, Roland went back to his office to think about how to complete Margaret's hydrogen balloon order.
Each balloon was sold at 1,000 gold royals, a much higher price than that of a steam engine, but its cost was much lower. The balloon was painted out by Soraya and the other parts such as bamboo basket and hemp ropes were cheap goods. Roland had made a simple prototype in the backyard of the arsenal, which could take both Lightning and Maggie in a flight.
He had abandoned the hot balloon plan after careful consideration, as now hydrogen was easier and cheaper compared with coal gas. Given that coal gas was obtained through coal dry distillation which required a large equipment, a complicated process, and a huge amount of coal imported from the other towns, it was clearly not economical to produce coal gas on a small scale.
The balloon of the prototype was made of a flexible, watery coating which was light as air. It was painted on a large paper which was burned afterward. In experiments, it was proven to be crash-worthy, waterproof and fireproof. Maggie had transformed into different kinds of bird to crash into and peck at the inflated balloon but failed to cause any damage. Only an iron needle could pierce through this 1-mm-thick coating. Due to its light weight, a hydrogen balloon which was about five meters in diameter was able to carry an adult up into the sky.
The remaining problem was how to refill the high pressure tank that stored hydrogen.
As one DC motor used for water electrolysis was enough to provide hydrogen for all balloons, Roland decided not to sell the motors to anyone in order to generate recurring revenues for himself. For that to happen, he needed to provide his clients high pressure tanks to store the hydrogen.
With Anna's help, he could have any tank he wanted. Even if he could only use pig iron or wrought iron as raw material, by asking Anna to increase the wall thickness of the tanks during manufacturing, he could easily make up for the material defect. However when it came to the refilling process, it was not that easy anymore. To blow up a large hydrogen balloon, the pressure inside the tank must be above 20 MPa, based on his experience in modern world. It was obviously impossible for him to refill the tanks with ordinary pumps. He needed high pressure air pump.
He thought of two different types of them, which were high pressure piston pump and turbopump. The former was included in the internal combustion engine tech tree, and the latter was a kind of turbines. Both of them required lots of time and energy to develop and manufacture, which was not what he wanted. It was already late afternoon when Roland finally thought of a solution, self-inflating inside the tank.
Before traveling into this era, he had read a piece of news about an explosion accident in a street caused by some hydrogen balloon seller's misconduct. Without careful calculation, the seller put dilute sulfuric acid and aluminum into a converted liquid gas storage tank to produce and store hydrogen. Unluckily, the tank's inner pressure got too high and it exploded.
Pouring dilute sulfuric acid and some active metal into a container was a self-inflating method used to produce hydrogen. In lab experiments, zinc was the most frequently used active metal and aluminum was the one most capable of producing a large amount of hydrogen. However, in this era, he could get neither of those single metals. Given that, Roland decided to use elemental Fe (pure iron) which could be produced by Lucia as the active metal. As this choice might lead to a low-speed chemical process at ambient temperature, Roland planned to activate the reaction by heating and expanding the reaction area (such as using pure iron plates or pure iron powders). He also planned to have the interior of the tanks coated by Soraya to resist the acid.
Having decided on the plan, Roland sketched out his design of the high pressure tank. To avoid gas leaks, the tank must be manufactured by integral moulding of iron, except for a protruding threaded opening. An air nozzle with valve would then be screwed into this opening.
Once the valve was tightened, the hydrogen generated inside by the metal and acid would never leak out, thus increasing the inner pressure to the desired level. This design was easy to use, as the clients just needed to open the valve to inflate the balloon. It also solved the refilling problem. He just had to remove the air nozzle, clean out all the ferrous sulfate crystallization and dry the tank before he put in metal and acid again.
Considering that dilute sulfuric acid was an alchemical product, he could not set a low price for refilling the tanks.
"I'll charge 50 gold royals for each refilling, and a client will get one free refill after 10 refillings," Roland thought.